1457c8996SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-only 21da177e4SLinus Torvalds /* 31da177e4SLinus Torvalds * INET An implementation of the TCP/IP protocol suite for the LINUX 41da177e4SLinus Torvalds * operating system. INET is implemented using the BSD Socket 51da177e4SLinus Torvalds * interface as the means of communication with the user level. 61da177e4SLinus Torvalds * 71da177e4SLinus Torvalds * Implementation of the Transmission Control Protocol(TCP). 81da177e4SLinus Torvalds * 902c30a84SJesper Juhl * Authors: Ross Biro 101da177e4SLinus Torvalds * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 111da177e4SLinus Torvalds * Mark Evans, <evansmp@uhura.aston.ac.uk> 121da177e4SLinus Torvalds * Corey Minyard <wf-rch!minyard@relay.EU.net> 131da177e4SLinus Torvalds * Florian La Roche, <flla@stud.uni-sb.de> 141da177e4SLinus Torvalds * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> 151da177e4SLinus Torvalds * Linus Torvalds, <torvalds@cs.helsinki.fi> 161da177e4SLinus Torvalds * Alan Cox, <gw4pts@gw4pts.ampr.org> 171da177e4SLinus Torvalds * Matthew Dillon, <dillon@apollo.west.oic.com> 181da177e4SLinus Torvalds * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 191da177e4SLinus Torvalds * Jorge Cwik, <jorge@laser.satlink.net> 201da177e4SLinus Torvalds */ 211da177e4SLinus Torvalds 221da177e4SLinus Torvalds /* 231da177e4SLinus Torvalds * Changes: Pedro Roque : Retransmit queue handled by TCP. 241da177e4SLinus Torvalds * : Fragmentation on mtu decrease 251da177e4SLinus Torvalds * : Segment collapse on retransmit 261da177e4SLinus Torvalds * : AF independence 271da177e4SLinus Torvalds * 281da177e4SLinus Torvalds * Linus Torvalds : send_delayed_ack 291da177e4SLinus Torvalds * David S. Miller : Charge memory using the right skb 301da177e4SLinus Torvalds * during syn/ack processing. 311da177e4SLinus Torvalds * David S. Miller : Output engine completely rewritten. 321da177e4SLinus Torvalds * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. 331da177e4SLinus Torvalds * Cacophonix Gaul : draft-minshall-nagle-01 341da177e4SLinus Torvalds * J Hadi Salim : ECN support 351da177e4SLinus Torvalds * 361da177e4SLinus Torvalds */ 371da177e4SLinus Torvalds 3891df42beSJoe Perches #define pr_fmt(fmt) "TCP: " fmt 3991df42beSJoe Perches 401da177e4SLinus Torvalds #include <net/tcp.h> 41eda7acddSPeter Krystad #include <net/mptcp.h> 421da177e4SLinus Torvalds 431da177e4SLinus Torvalds #include <linux/compiler.h> 445a0e3ad6STejun Heo #include <linux/gfp.h> 451da177e4SLinus Torvalds #include <linux/module.h> 4660e2a778SUrsula Braun #include <linux/static_key.h> 471da177e4SLinus Torvalds 48e086101bSCong Wang #include <trace/events/tcp.h> 4935089bb2SDavid S. Miller 509799ccb0SEric Dumazet /* Refresh clocks of a TCP socket, 519799ccb0SEric Dumazet * ensuring monotically increasing values. 529799ccb0SEric Dumazet */ 539799ccb0SEric Dumazet void tcp_mstamp_refresh(struct tcp_sock *tp) 549799ccb0SEric Dumazet { 559799ccb0SEric Dumazet u64 val = tcp_clock_ns(); 569799ccb0SEric Dumazet 575f6188a8SEric Dumazet tp->tcp_clock_cache = val; 58e6d14070SEric Dumazet tp->tcp_mstamp = div_u64(val, NSEC_PER_USEC); 599799ccb0SEric Dumazet } 609799ccb0SEric Dumazet 6146d3ceabSEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 6246d3ceabSEric Dumazet int push_one, gfp_t gfp); 63519855c5SWilliam Allen Simpson 6467edfef7SAndi Kleen /* Account for new data that has been sent to the network. */ 6575c119afSEric Dumazet static void tcp_event_new_data_sent(struct sock *sk, struct sk_buff *skb) 666ff03ac3SIlpo Järvinen { 676ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 686ff03ac3SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 6966f5fe62SIlpo Järvinen unsigned int prior_packets = tp->packets_out; 709e412ba7SIlpo Järvinen 71e0d694d6SEric Dumazet WRITE_ONCE(tp->snd_nxt, TCP_SKB_CB(skb)->end_seq); 728512430eSIlpo Järvinen 7375c119afSEric Dumazet __skb_unlink(skb, &sk->sk_write_queue); 7475c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, skb); 7575c119afSEric Dumazet 7685369750SCambda Zhu if (tp->highest_sack == NULL) 7785369750SCambda Zhu tp->highest_sack = skb; 7885369750SCambda Zhu 7966f5fe62SIlpo Järvinen tp->packets_out += tcp_skb_pcount(skb); 80bec41a11SYuchung Cheng if (!prior_packets || icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) 81750ea2baSYuchung Cheng tcp_rearm_rto(sk); 82f19c29e3SYuchung Cheng 83f7324acdSDavid S. Miller NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT, 84f19c29e3SYuchung Cheng tcp_skb_pcount(skb)); 854bfe744fSEric Dumazet tcp_check_space(sk); 866a5dc9e5SEric Dumazet } 871da177e4SLinus Torvalds 88a4ecb15aSCui, Cheng /* SND.NXT, if window was not shrunk or the amount of shrunk was less than one 89a4ecb15aSCui, Cheng * window scaling factor due to loss of precision. 901da177e4SLinus Torvalds * If window has been shrunk, what should we make? It is not clear at all. 911da177e4SLinus Torvalds * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( 921da177e4SLinus Torvalds * Anything in between SND.UNA...SND.UNA+SND.WND also can be already 931da177e4SLinus Torvalds * invalid. OK, let's make this for now: 941da177e4SLinus Torvalds */ 95cf533ea5SEric Dumazet static inline __u32 tcp_acceptable_seq(const struct sock *sk) 961da177e4SLinus Torvalds { 97cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 989e412ba7SIlpo Järvinen 99a4ecb15aSCui, Cheng if (!before(tcp_wnd_end(tp), tp->snd_nxt) || 100a4ecb15aSCui, Cheng (tp->rx_opt.wscale_ok && 101a4ecb15aSCui, Cheng ((tp->snd_nxt - tcp_wnd_end(tp)) < (1 << tp->rx_opt.rcv_wscale)))) 1021da177e4SLinus Torvalds return tp->snd_nxt; 1031da177e4SLinus Torvalds else 10490840defSIlpo Järvinen return tcp_wnd_end(tp); 1051da177e4SLinus Torvalds } 1061da177e4SLinus Torvalds 1071da177e4SLinus Torvalds /* Calculate mss to advertise in SYN segment. 1081da177e4SLinus Torvalds * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: 1091da177e4SLinus Torvalds * 1101da177e4SLinus Torvalds * 1. It is independent of path mtu. 1111da177e4SLinus Torvalds * 2. Ideally, it is maximal possible segment size i.e. 65535-40. 1121da177e4SLinus Torvalds * 3. For IPv4 it is reasonable to calculate it from maximal MTU of 1131da177e4SLinus Torvalds * attached devices, because some buggy hosts are confused by 1141da177e4SLinus Torvalds * large MSS. 1151da177e4SLinus Torvalds * 4. We do not make 3, we advertise MSS, calculated from first 1161da177e4SLinus Torvalds * hop device mtu, but allow to raise it to ip_rt_min_advmss. 1171da177e4SLinus Torvalds * This may be overridden via information stored in routing table. 1181da177e4SLinus Torvalds * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, 1191da177e4SLinus Torvalds * probably even Jumbo". 1201da177e4SLinus Torvalds */ 1211da177e4SLinus Torvalds static __u16 tcp_advertise_mss(struct sock *sk) 1221da177e4SLinus Torvalds { 1231da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 124cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1251da177e4SLinus Torvalds int mss = tp->advmss; 1261da177e4SLinus Torvalds 1270dbaee3bSDavid S. Miller if (dst) { 1280dbaee3bSDavid S. Miller unsigned int metric = dst_metric_advmss(dst); 1290dbaee3bSDavid S. Miller 1300dbaee3bSDavid S. Miller if (metric < mss) { 1310dbaee3bSDavid S. Miller mss = metric; 1321da177e4SLinus Torvalds tp->advmss = mss; 1331da177e4SLinus Torvalds } 1340dbaee3bSDavid S. Miller } 1351da177e4SLinus Torvalds 1361da177e4SLinus Torvalds return (__u16)mss; 1371da177e4SLinus Torvalds } 1381da177e4SLinus Torvalds 1391da177e4SLinus Torvalds /* RFC2861. Reset CWND after idle period longer RTO to "restart window". 1406f021c62SEric Dumazet * This is the first part of cwnd validation mechanism. 1416f021c62SEric Dumazet */ 1426f021c62SEric Dumazet void tcp_cwnd_restart(struct sock *sk, s32 delta) 1431da177e4SLinus Torvalds { 144463c84b9SArnaldo Carvalho de Melo struct tcp_sock *tp = tcp_sk(sk); 1456f021c62SEric Dumazet u32 restart_cwnd = tcp_init_cwnd(tp, __sk_dst_get(sk)); 14640570375SEric Dumazet u32 cwnd = tcp_snd_cwnd(tp); 1471da177e4SLinus Torvalds 1486687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_CWND_RESTART); 1491da177e4SLinus Torvalds 1506687e988SArnaldo Carvalho de Melo tp->snd_ssthresh = tcp_current_ssthresh(sk); 1511da177e4SLinus Torvalds restart_cwnd = min(restart_cwnd, cwnd); 1521da177e4SLinus Torvalds 153463c84b9SArnaldo Carvalho de Melo while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) 1541da177e4SLinus Torvalds cwnd >>= 1; 15540570375SEric Dumazet tcp_snd_cwnd_set(tp, max(cwnd, restart_cwnd)); 156c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 1571da177e4SLinus Torvalds tp->snd_cwnd_used = 0; 1581da177e4SLinus Torvalds } 1591da177e4SLinus Torvalds 16067edfef7SAndi Kleen /* Congestion state accounting after a packet has been sent. */ 16140efc6faSStephen Hemminger static void tcp_event_data_sent(struct tcp_sock *tp, 162cf533ea5SEric Dumazet struct sock *sk) 1631da177e4SLinus Torvalds { 164463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 165d635fbe2SEric Dumazet const u32 now = tcp_jiffies32; 1661da177e4SLinus Torvalds 16705c5a46dSNeal Cardwell if (tcp_packets_in_flight(tp) == 0) 16805c5a46dSNeal Cardwell tcp_ca_event(sk, CA_EVENT_TX_START); 16905c5a46dSNeal Cardwell 1704a41f453SWei Wang tp->lsndtime = now; 1714d8f24eeSWei Wang 1724d8f24eeSWei Wang /* If it is a reply for ato after last received 173562b1fdfSHaiyang Zhang * packet, increase pingpong count. 1744d8f24eeSWei Wang */ 1754d8f24eeSWei Wang if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) 176562b1fdfSHaiyang Zhang inet_csk_inc_pingpong_cnt(sk); 1771da177e4SLinus Torvalds } 1781da177e4SLinus Torvalds 17967edfef7SAndi Kleen /* Account for an ACK we sent. */ 180059217c1SNeal Cardwell static inline void tcp_event_ack_sent(struct sock *sk, u32 rcv_nxt) 1811da177e4SLinus Torvalds { 1825d9f4262SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 1835d9f4262SEric Dumazet 1842b195850SEric Dumazet if (unlikely(tp->compressed_ack)) { 185200d95f4SEric Dumazet NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPACKCOMPRESSED, 1862b195850SEric Dumazet tp->compressed_ack); 1872b195850SEric Dumazet tp->compressed_ack = 0; 1885d9f4262SEric Dumazet if (hrtimer_try_to_cancel(&tp->compressed_ack_timer) == 1) 1895d9f4262SEric Dumazet __sock_put(sk); 1905d9f4262SEric Dumazet } 19127cde44aSYuchung Cheng 19227cde44aSYuchung Cheng if (unlikely(rcv_nxt != tp->rcv_nxt)) 19327cde44aSYuchung Cheng return; /* Special ACK sent by DCTCP to reflect ECN */ 194059217c1SNeal Cardwell tcp_dec_quickack_mode(sk); 195463c84b9SArnaldo Carvalho de Melo inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 1961da177e4SLinus Torvalds } 1971da177e4SLinus Torvalds 1981da177e4SLinus Torvalds /* Determine a window scaling and initial window to offer. 1991da177e4SLinus Torvalds * Based on the assumption that the given amount of space 2001da177e4SLinus Torvalds * will be offered. Store the results in the tp structure. 2011da177e4SLinus Torvalds * NOTE: for smooth operation initial space offering should 2021da177e4SLinus Torvalds * be a multiple of mss if possible. We assume here that mss >= 1. 2031da177e4SLinus Torvalds * This MUST be enforced by all callers. 2041da177e4SLinus Torvalds */ 205ceef9ab6SEric Dumazet void tcp_select_initial_window(const struct sock *sk, int __space, __u32 mss, 2061da177e4SLinus Torvalds __u32 *rcv_wnd, __u32 *window_clamp, 20731d12926Slaurent chavey int wscale_ok, __u8 *rcv_wscale, 20831d12926Slaurent chavey __u32 init_rcv_wnd) 2091da177e4SLinus Torvalds { 2101da177e4SLinus Torvalds unsigned int space = (__space < 0 ? 0 : __space); 2111da177e4SLinus Torvalds 2121da177e4SLinus Torvalds /* If no clamp set the clamp to the max possible scaled window */ 2131da177e4SLinus Torvalds if (*window_clamp == 0) 214589c49cbSGao Feng (*window_clamp) = (U16_MAX << TCP_MAX_WSCALE); 2151da177e4SLinus Torvalds space = min(*window_clamp, space); 2161da177e4SLinus Torvalds 2171da177e4SLinus Torvalds /* Quantize space offering to a multiple of mss if possible. */ 2181da177e4SLinus Torvalds if (space > mss) 219589c49cbSGao Feng space = rounddown(space, mss); 2201da177e4SLinus Torvalds 2211da177e4SLinus Torvalds /* NOTE: offering an initial window larger than 32767 22215d99e02SRick Jones * will break some buggy TCP stacks. If the admin tells us 22315d99e02SRick Jones * it is likely we could be speaking with such a buggy stack 22415d99e02SRick Jones * we will truncate our initial window offering to 32K-1 22515d99e02SRick Jones * unless the remote has sent us a window scaling option, 22615d99e02SRick Jones * which we interpret as a sign the remote TCP is not 22715d99e02SRick Jones * misinterpreting the window field as a signed quantity. 2281da177e4SLinus Torvalds */ 2290f1e4d06SKuniyuki Iwashima if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows)) 2301da177e4SLinus Torvalds (*rcv_wnd) = min(space, MAX_TCP_WINDOW); 23115d99e02SRick Jones else 232a337531bSYuchung Cheng (*rcv_wnd) = min_t(u32, space, U16_MAX); 233a337531bSYuchung Cheng 234a337531bSYuchung Cheng if (init_rcv_wnd) 235a337531bSYuchung Cheng *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); 23615d99e02SRick Jones 23719bf6261SEric Dumazet *rcv_wscale = 0; 2381da177e4SLinus Torvalds if (wscale_ok) { 239589c49cbSGao Feng /* Set window scaling on max possible window */ 24002739545SKuniyuki Iwashima space = max_t(u32, space, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2])); 2411227c177SKuniyuki Iwashima space = max_t(u32, space, READ_ONCE(sysctl_rmem_max)); 242316c1592SStephen Hemminger space = min_t(u32, space, *window_clamp); 24319bf6261SEric Dumazet *rcv_wscale = clamp_t(int, ilog2(space) - 15, 24419bf6261SEric Dumazet 0, TCP_MAX_WSCALE); 2451da177e4SLinus Torvalds } 2461da177e4SLinus Torvalds /* Set the clamp no higher than max representable value */ 247589c49cbSGao Feng (*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp); 2481da177e4SLinus Torvalds } 2494bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_select_initial_window); 2501da177e4SLinus Torvalds 2511da177e4SLinus Torvalds /* Chose a new window to advertise, update state in tcp_sock for the 2521da177e4SLinus Torvalds * socket, and return result with RFC1323 scaling applied. The return 2531da177e4SLinus Torvalds * value can be stuffed directly into th->window for an outgoing 2541da177e4SLinus Torvalds * frame. 2551da177e4SLinus Torvalds */ 25640efc6faSStephen Hemminger static u16 tcp_select_window(struct sock *sk) 2571da177e4SLinus Torvalds { 2581da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 259b650d953Smfreemon@cloudflare.com struct net *net = sock_net(sk); 260e2142825SMenglong Dong u32 old_win = tp->rcv_wnd; 261e2142825SMenglong Dong u32 cur_win, new_win; 2621da177e4SLinus Torvalds 263e2142825SMenglong Dong /* Make the window 0 if we failed to queue the data because we 264e2142825SMenglong Dong * are out of memory. The window is temporary, so we don't store 265e2142825SMenglong Dong * it on the socket. 266e2142825SMenglong Dong */ 267e2142825SMenglong Dong if (unlikely(inet_csk(sk)->icsk_ack.pending & ICSK_ACK_NOMEM)) 268e2142825SMenglong Dong return 0; 269e2142825SMenglong Dong 270e2142825SMenglong Dong cur_win = tcp_receive_window(tp); 271e2142825SMenglong Dong new_win = __tcp_select_window(sk); 2721da177e4SLinus Torvalds if (new_win < cur_win) { 2731da177e4SLinus Torvalds /* Danger Will Robinson! 2741da177e4SLinus Torvalds * Don't update rcv_wup/rcv_wnd here or else 2751da177e4SLinus Torvalds * we will not be able to advertise a zero 2761da177e4SLinus Torvalds * window in time. --DaveM 2771da177e4SLinus Torvalds * 2781da177e4SLinus Torvalds * Relax Will Robinson. 2791da177e4SLinus Torvalds */ 280b650d953Smfreemon@cloudflare.com if (!READ_ONCE(net->ipv4.sysctl_tcp_shrink_window) || !tp->rx_opt.rcv_wscale) { 281b650d953Smfreemon@cloudflare.com /* Never shrink the offered window */ 2828e165e20SFlorian Westphal if (new_win == 0) 283b650d953Smfreemon@cloudflare.com NET_INC_STATS(net, LINUX_MIB_TCPWANTZEROWINDOWADV); 284607bfbf2SPatrick McHardy new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); 2851da177e4SLinus Torvalds } 286b650d953Smfreemon@cloudflare.com } 287b650d953Smfreemon@cloudflare.com 2881da177e4SLinus Torvalds tp->rcv_wnd = new_win; 2891da177e4SLinus Torvalds tp->rcv_wup = tp->rcv_nxt; 2901da177e4SLinus Torvalds 2911da177e4SLinus Torvalds /* Make sure we do not exceed the maximum possible 2921da177e4SLinus Torvalds * scaled window. 2931da177e4SLinus Torvalds */ 294ceef9ab6SEric Dumazet if (!tp->rx_opt.rcv_wscale && 295b650d953Smfreemon@cloudflare.com READ_ONCE(net->ipv4.sysctl_tcp_workaround_signed_windows)) 2961da177e4SLinus Torvalds new_win = min(new_win, MAX_TCP_WINDOW); 2971da177e4SLinus Torvalds else 2981da177e4SLinus Torvalds new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 2991da177e4SLinus Torvalds 3001da177e4SLinus Torvalds /* RFC1323 scaling applied */ 3011da177e4SLinus Torvalds new_win >>= tp->rx_opt.rcv_wscale; 3021da177e4SLinus Torvalds 30331770e34SFlorian Westphal /* If we advertise zero window, disable fast path. */ 3048e165e20SFlorian Westphal if (new_win == 0) { 30531770e34SFlorian Westphal tp->pred_flags = 0; 3068e165e20SFlorian Westphal if (old_win) 307b650d953Smfreemon@cloudflare.com NET_INC_STATS(net, LINUX_MIB_TCPTOZEROWINDOWADV); 3088e165e20SFlorian Westphal } else if (old_win == 0) { 309b650d953Smfreemon@cloudflare.com NET_INC_STATS(net, LINUX_MIB_TCPFROMZEROWINDOWADV); 3108e165e20SFlorian Westphal } 3111da177e4SLinus Torvalds 3121da177e4SLinus Torvalds return new_win; 3131da177e4SLinus Torvalds } 3141da177e4SLinus Torvalds 31567edfef7SAndi Kleen /* Packet ECN state for a SYN-ACK */ 316735d3831SFlorian Westphal static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) 317bdf1ee5dSIlpo Järvinen { 31830e502a3SDaniel Borkmann const struct tcp_sock *tp = tcp_sk(sk); 31930e502a3SDaniel Borkmann 3204de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; 321bdf1ee5dSIlpo Järvinen if (!(tp->ecn_flags & TCP_ECN_OK)) 3224de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; 32391b5b21cSLawrence Brakmo else if (tcp_ca_needs_ecn(sk) || 32491b5b21cSLawrence Brakmo tcp_bpf_ca_needs_ecn(sk)) 32530e502a3SDaniel Borkmann INET_ECN_xmit(sk); 326bdf1ee5dSIlpo Järvinen } 327bdf1ee5dSIlpo Järvinen 32867edfef7SAndi Kleen /* Packet ECN state for a SYN. */ 329735d3831SFlorian Westphal static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) 330bdf1ee5dSIlpo Järvinen { 331bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 33291b5b21cSLawrence Brakmo bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk); 3334785a667SKuniyuki Iwashima bool use_ecn = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn) == 1 || 33491b5b21cSLawrence Brakmo tcp_ca_needs_ecn(sk) || bpf_needs_ecn; 335f7b3bec6SFlorian Westphal 336f7b3bec6SFlorian Westphal if (!use_ecn) { 337f7b3bec6SFlorian Westphal const struct dst_entry *dst = __sk_dst_get(sk); 338f7b3bec6SFlorian Westphal 339f7b3bec6SFlorian Westphal if (dst && dst_feature(dst, RTAX_FEATURE_ECN)) 340f7b3bec6SFlorian Westphal use_ecn = true; 341f7b3bec6SFlorian Westphal } 342bdf1ee5dSIlpo Järvinen 343bdf1ee5dSIlpo Järvinen tp->ecn_flags = 0; 344f7b3bec6SFlorian Westphal 345f7b3bec6SFlorian Westphal if (use_ecn) { 3464de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; 347bdf1ee5dSIlpo Järvinen tp->ecn_flags = TCP_ECN_OK; 34891b5b21cSLawrence Brakmo if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn) 34930e502a3SDaniel Borkmann INET_ECN_xmit(sk); 350bdf1ee5dSIlpo Järvinen } 351bdf1ee5dSIlpo Järvinen } 352bdf1ee5dSIlpo Järvinen 35349213555SDaniel Borkmann static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb) 35449213555SDaniel Borkmann { 35512b8d9caSKuniyuki Iwashima if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback)) 35649213555SDaniel Borkmann /* tp->ecn_flags are cleared at a later point in time when 35749213555SDaniel Borkmann * SYN ACK is ultimatively being received. 35849213555SDaniel Borkmann */ 35949213555SDaniel Borkmann TCP_SKB_CB(skb)->tcp_flags &= ~(TCPHDR_ECE | TCPHDR_CWR); 36049213555SDaniel Borkmann } 36149213555SDaniel Borkmann 362735d3831SFlorian Westphal static void 3636ac705b1SEric Dumazet tcp_ecn_make_synack(const struct request_sock *req, struct tcphdr *th) 364bdf1ee5dSIlpo Järvinen { 3656ac705b1SEric Dumazet if (inet_rsk(req)->ecn_ok) 366bdf1ee5dSIlpo Järvinen th->ece = 1; 367bdf1ee5dSIlpo Järvinen } 368bdf1ee5dSIlpo Järvinen 36967edfef7SAndi Kleen /* Set up ECN state for a packet on a ESTABLISHED socket that is about to 37067edfef7SAndi Kleen * be sent. 37167edfef7SAndi Kleen */ 372735d3831SFlorian Westphal static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, 373ea1627c2SEric Dumazet struct tcphdr *th, int tcp_header_len) 374bdf1ee5dSIlpo Järvinen { 375bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 376bdf1ee5dSIlpo Järvinen 377bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_OK) { 378bdf1ee5dSIlpo Järvinen /* Not-retransmitted data segment: set ECT and inject CWR. */ 379bdf1ee5dSIlpo Järvinen if (skb->len != tcp_header_len && 380bdf1ee5dSIlpo Järvinen !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { 381bdf1ee5dSIlpo Järvinen INET_ECN_xmit(sk); 382bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { 383bdf1ee5dSIlpo Järvinen tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; 384ea1627c2SEric Dumazet th->cwr = 1; 385bdf1ee5dSIlpo Järvinen skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 386bdf1ee5dSIlpo Järvinen } 38730e502a3SDaniel Borkmann } else if (!tcp_ca_needs_ecn(sk)) { 388bdf1ee5dSIlpo Järvinen /* ACK or retransmitted segment: clear ECT|CE */ 389bdf1ee5dSIlpo Järvinen INET_ECN_dontxmit(sk); 390bdf1ee5dSIlpo Järvinen } 391bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) 392ea1627c2SEric Dumazet th->ece = 1; 393bdf1ee5dSIlpo Järvinen } 394bdf1ee5dSIlpo Järvinen } 395bdf1ee5dSIlpo Järvinen 396e870a8efSIlpo Järvinen /* Constructs common control bits of non-data skb. If SYN/FIN is present, 397e870a8efSIlpo Järvinen * auto increment end seqno. 398e870a8efSIlpo Järvinen */ 399e870a8efSIlpo Järvinen static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) 400e870a8efSIlpo Järvinen { 4012e8e18efSDavid S. Miller skb->ip_summed = CHECKSUM_PARTIAL; 402e870a8efSIlpo Järvinen 4034de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags; 404e870a8efSIlpo Järvinen 405cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 406e870a8efSIlpo Järvinen 407e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->seq = seq; 408a3433f35SChangli Gao if (flags & (TCPHDR_SYN | TCPHDR_FIN)) 409e870a8efSIlpo Järvinen seq++; 410e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->end_seq = seq; 411e870a8efSIlpo Järvinen } 412e870a8efSIlpo Järvinen 413a2a385d6SEric Dumazet static inline bool tcp_urg_mode(const struct tcp_sock *tp) 41433f5f57eSIlpo Järvinen { 41533f5f57eSIlpo Järvinen return tp->snd_una != tp->snd_up; 41633f5f57eSIlpo Järvinen } 41733f5f57eSIlpo Järvinen 4183b65abb8SLeonard Crestez #define OPTION_SACK_ADVERTISE BIT(0) 4193b65abb8SLeonard Crestez #define OPTION_TS BIT(1) 4203b65abb8SLeonard Crestez #define OPTION_MD5 BIT(2) 4213b65abb8SLeonard Crestez #define OPTION_WSCALE BIT(3) 4223b65abb8SLeonard Crestez #define OPTION_FAST_OPEN_COOKIE BIT(8) 4233b65abb8SLeonard Crestez #define OPTION_SMC BIT(9) 4243b65abb8SLeonard Crestez #define OPTION_MPTCP BIT(10) 42560e2a778SUrsula Braun 42660e2a778SUrsula Braun static void smc_options_write(__be32 *ptr, u16 *options) 42760e2a778SUrsula Braun { 42860e2a778SUrsula Braun #if IS_ENABLED(CONFIG_SMC) 42960e2a778SUrsula Braun if (static_branch_unlikely(&tcp_have_smc)) { 43060e2a778SUrsula Braun if (unlikely(OPTION_SMC & *options)) { 43160e2a778SUrsula Braun *ptr++ = htonl((TCPOPT_NOP << 24) | 43260e2a778SUrsula Braun (TCPOPT_NOP << 16) | 43360e2a778SUrsula Braun (TCPOPT_EXP << 8) | 43460e2a778SUrsula Braun (TCPOLEN_EXP_SMC_BASE)); 43560e2a778SUrsula Braun *ptr++ = htonl(TCPOPT_SMC_MAGIC); 43660e2a778SUrsula Braun } 43760e2a778SUrsula Braun } 43860e2a778SUrsula Braun #endif 43960e2a778SUrsula Braun } 44033ad798cSAdam Langley 44133ad798cSAdam Langley struct tcp_out_options { 4422100c8d2SYuchung Cheng u16 options; /* bit field of OPTION_* */ 4432100c8d2SYuchung Cheng u16 mss; /* 0 to disable */ 44433ad798cSAdam Langley u8 ws; /* window scale, 0 to disable */ 44533ad798cSAdam Langley u8 num_sack_blocks; /* number of SACK blocks to include */ 446bd0388aeSWilliam Allen Simpson u8 hash_size; /* bytes in hash_location */ 447331fca43SMartin KaFai Lau u8 bpf_opt_len; /* length of BPF hdr option */ 448bd0388aeSWilliam Allen Simpson __u8 *hash_location; /* temporary pointer, overloaded */ 4492100c8d2SYuchung Cheng __u32 tsval, tsecr; /* need to include OPTION_TS */ 4502100c8d2SYuchung Cheng struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ 451eda7acddSPeter Krystad struct mptcp_out_options mptcp; 45233ad798cSAdam Langley }; 45333ad798cSAdam Langley 454ea66758cSPaolo Abeni static void mptcp_options_write(struct tcphdr *th, __be32 *ptr, 455ea66758cSPaolo Abeni struct tcp_sock *tp, 456fa3fe2b1SFlorian Westphal struct tcp_out_options *opts) 457eda7acddSPeter Krystad { 458eda7acddSPeter Krystad #if IS_ENABLED(CONFIG_MPTCP) 459eda7acddSPeter Krystad if (unlikely(OPTION_MPTCP & opts->options)) 460ea66758cSPaolo Abeni mptcp_write_options(th, ptr, tp, &opts->mptcp); 461eda7acddSPeter Krystad #endif 462eda7acddSPeter Krystad } 463eda7acddSPeter Krystad 464331fca43SMartin KaFai Lau #ifdef CONFIG_CGROUP_BPF 4650813a841SMartin KaFai Lau static int bpf_skops_write_hdr_opt_arg0(struct sk_buff *skb, 4660813a841SMartin KaFai Lau enum tcp_synack_type synack_type) 4670813a841SMartin KaFai Lau { 4680813a841SMartin KaFai Lau if (unlikely(!skb)) 4690813a841SMartin KaFai Lau return BPF_WRITE_HDR_TCP_CURRENT_MSS; 4700813a841SMartin KaFai Lau 4710813a841SMartin KaFai Lau if (unlikely(synack_type == TCP_SYNACK_COOKIE)) 4720813a841SMartin KaFai Lau return BPF_WRITE_HDR_TCP_SYNACK_COOKIE; 4730813a841SMartin KaFai Lau 4740813a841SMartin KaFai Lau return 0; 4750813a841SMartin KaFai Lau } 4760813a841SMartin KaFai Lau 477331fca43SMartin KaFai Lau /* req, syn_skb and synack_type are used when writing synack */ 478331fca43SMartin KaFai Lau static void bpf_skops_hdr_opt_len(struct sock *sk, struct sk_buff *skb, 479331fca43SMartin KaFai Lau struct request_sock *req, 480331fca43SMartin KaFai Lau struct sk_buff *syn_skb, 481331fca43SMartin KaFai Lau enum tcp_synack_type synack_type, 482331fca43SMartin KaFai Lau struct tcp_out_options *opts, 483331fca43SMartin KaFai Lau unsigned int *remaining) 484331fca43SMartin KaFai Lau { 4850813a841SMartin KaFai Lau struct bpf_sock_ops_kern sock_ops; 4860813a841SMartin KaFai Lau int err; 4870813a841SMartin KaFai Lau 488331fca43SMartin KaFai Lau if (likely(!BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), 489331fca43SMartin KaFai Lau BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG)) || 490331fca43SMartin KaFai Lau !*remaining) 491331fca43SMartin KaFai Lau return; 492331fca43SMartin KaFai Lau 4930813a841SMartin KaFai Lau /* *remaining has already been aligned to 4 bytes, so *remaining >= 4 */ 4940813a841SMartin KaFai Lau 4950813a841SMartin KaFai Lau /* init sock_ops */ 4960813a841SMartin KaFai Lau memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); 4970813a841SMartin KaFai Lau 4980813a841SMartin KaFai Lau sock_ops.op = BPF_SOCK_OPS_HDR_OPT_LEN_CB; 4990813a841SMartin KaFai Lau 5000813a841SMartin KaFai Lau if (req) { 5010813a841SMartin KaFai Lau /* The listen "sk" cannot be passed here because 5020813a841SMartin KaFai Lau * it is not locked. It would not make too much 5030813a841SMartin KaFai Lau * sense to do bpf_setsockopt(listen_sk) based 5040813a841SMartin KaFai Lau * on individual connection request also. 5050813a841SMartin KaFai Lau * 5060813a841SMartin KaFai Lau * Thus, "req" is passed here and the cgroup-bpf-progs 5070813a841SMartin KaFai Lau * of the listen "sk" will be run. 5080813a841SMartin KaFai Lau * 5090813a841SMartin KaFai Lau * "req" is also used here for fastopen even the "sk" here is 5100813a841SMartin KaFai Lau * a fullsock "child" sk. It is to keep the behavior 5110813a841SMartin KaFai Lau * consistent between fastopen and non-fastopen on 5120813a841SMartin KaFai Lau * the bpf programming side. 513331fca43SMartin KaFai Lau */ 5140813a841SMartin KaFai Lau sock_ops.sk = (struct sock *)req; 5150813a841SMartin KaFai Lau sock_ops.syn_skb = syn_skb; 5160813a841SMartin KaFai Lau } else { 5170813a841SMartin KaFai Lau sock_owned_by_me(sk); 5180813a841SMartin KaFai Lau 5190813a841SMartin KaFai Lau sock_ops.is_fullsock = 1; 5200813a841SMartin KaFai Lau sock_ops.sk = sk; 5210813a841SMartin KaFai Lau } 5220813a841SMartin KaFai Lau 5230813a841SMartin KaFai Lau sock_ops.args[0] = bpf_skops_write_hdr_opt_arg0(skb, synack_type); 5240813a841SMartin KaFai Lau sock_ops.remaining_opt_len = *remaining; 5250813a841SMartin KaFai Lau /* tcp_current_mss() does not pass a skb */ 5260813a841SMartin KaFai Lau if (skb) 5270813a841SMartin KaFai Lau bpf_skops_init_skb(&sock_ops, skb, 0); 5280813a841SMartin KaFai Lau 5290813a841SMartin KaFai Lau err = BPF_CGROUP_RUN_PROG_SOCK_OPS_SK(&sock_ops, sk); 5300813a841SMartin KaFai Lau 5310813a841SMartin KaFai Lau if (err || sock_ops.remaining_opt_len == *remaining) 5320813a841SMartin KaFai Lau return; 5330813a841SMartin KaFai Lau 5340813a841SMartin KaFai Lau opts->bpf_opt_len = *remaining - sock_ops.remaining_opt_len; 5350813a841SMartin KaFai Lau /* round up to 4 bytes */ 5360813a841SMartin KaFai Lau opts->bpf_opt_len = (opts->bpf_opt_len + 3) & ~3; 5370813a841SMartin KaFai Lau 5380813a841SMartin KaFai Lau *remaining -= opts->bpf_opt_len; 539331fca43SMartin KaFai Lau } 540331fca43SMartin KaFai Lau 541331fca43SMartin KaFai Lau static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb, 542331fca43SMartin KaFai Lau struct request_sock *req, 543331fca43SMartin KaFai Lau struct sk_buff *syn_skb, 544331fca43SMartin KaFai Lau enum tcp_synack_type synack_type, 545331fca43SMartin KaFai Lau struct tcp_out_options *opts) 546331fca43SMartin KaFai Lau { 5470813a841SMartin KaFai Lau u8 first_opt_off, nr_written, max_opt_len = opts->bpf_opt_len; 5480813a841SMartin KaFai Lau struct bpf_sock_ops_kern sock_ops; 5490813a841SMartin KaFai Lau int err; 5500813a841SMartin KaFai Lau 5510813a841SMartin KaFai Lau if (likely(!max_opt_len)) 552331fca43SMartin KaFai Lau return; 553331fca43SMartin KaFai Lau 5540813a841SMartin KaFai Lau memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); 5550813a841SMartin KaFai Lau 5560813a841SMartin KaFai Lau sock_ops.op = BPF_SOCK_OPS_WRITE_HDR_OPT_CB; 5570813a841SMartin KaFai Lau 5580813a841SMartin KaFai Lau if (req) { 5590813a841SMartin KaFai Lau sock_ops.sk = (struct sock *)req; 5600813a841SMartin KaFai Lau sock_ops.syn_skb = syn_skb; 5610813a841SMartin KaFai Lau } else { 5620813a841SMartin KaFai Lau sock_owned_by_me(sk); 5630813a841SMartin KaFai Lau 5640813a841SMartin KaFai Lau sock_ops.is_fullsock = 1; 5650813a841SMartin KaFai Lau sock_ops.sk = sk; 5660813a841SMartin KaFai Lau } 5670813a841SMartin KaFai Lau 5680813a841SMartin KaFai Lau sock_ops.args[0] = bpf_skops_write_hdr_opt_arg0(skb, synack_type); 5690813a841SMartin KaFai Lau sock_ops.remaining_opt_len = max_opt_len; 5700813a841SMartin KaFai Lau first_opt_off = tcp_hdrlen(skb) - max_opt_len; 5710813a841SMartin KaFai Lau bpf_skops_init_skb(&sock_ops, skb, first_opt_off); 5720813a841SMartin KaFai Lau 5730813a841SMartin KaFai Lau err = BPF_CGROUP_RUN_PROG_SOCK_OPS_SK(&sock_ops, sk); 5740813a841SMartin KaFai Lau 5750813a841SMartin KaFai Lau if (err) 5760813a841SMartin KaFai Lau nr_written = 0; 5770813a841SMartin KaFai Lau else 5780813a841SMartin KaFai Lau nr_written = max_opt_len - sock_ops.remaining_opt_len; 5790813a841SMartin KaFai Lau 5800813a841SMartin KaFai Lau if (nr_written < max_opt_len) 5810813a841SMartin KaFai Lau memset(skb->data + first_opt_off + nr_written, TCPOPT_NOP, 5820813a841SMartin KaFai Lau max_opt_len - nr_written); 583331fca43SMartin KaFai Lau } 584331fca43SMartin KaFai Lau #else 585331fca43SMartin KaFai Lau static void bpf_skops_hdr_opt_len(struct sock *sk, struct sk_buff *skb, 586331fca43SMartin KaFai Lau struct request_sock *req, 587331fca43SMartin KaFai Lau struct sk_buff *syn_skb, 588331fca43SMartin KaFai Lau enum tcp_synack_type synack_type, 589331fca43SMartin KaFai Lau struct tcp_out_options *opts, 590331fca43SMartin KaFai Lau unsigned int *remaining) 591331fca43SMartin KaFai Lau { 592331fca43SMartin KaFai Lau } 593331fca43SMartin KaFai Lau 594331fca43SMartin KaFai Lau static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb, 595331fca43SMartin KaFai Lau struct request_sock *req, 596331fca43SMartin KaFai Lau struct sk_buff *syn_skb, 597331fca43SMartin KaFai Lau enum tcp_synack_type synack_type, 598331fca43SMartin KaFai Lau struct tcp_out_options *opts) 599331fca43SMartin KaFai Lau { 600331fca43SMartin KaFai Lau } 601331fca43SMartin KaFai Lau #endif 602331fca43SMartin KaFai Lau 60367edfef7SAndi Kleen /* Write previously computed TCP options to the packet. 60467edfef7SAndi Kleen * 60567edfef7SAndi Kleen * Beware: Something in the Internet is very sensitive to the ordering of 606fd6149d3SIlpo Järvinen * TCP options, we learned this through the hard way, so be careful here. 607fd6149d3SIlpo Järvinen * Luckily we can at least blame others for their non-compliance but from 6088e3bff96Sstephen hemminger * inter-operability perspective it seems that we're somewhat stuck with 609fd6149d3SIlpo Järvinen * the ordering which we have been using if we want to keep working with 610fd6149d3SIlpo Järvinen * those broken things (not that it currently hurts anybody as there isn't 611fd6149d3SIlpo Järvinen * particular reason why the ordering would need to be changed). 612fd6149d3SIlpo Järvinen * 613fd6149d3SIlpo Järvinen * At least SACK_PERM as the first option is known to lead to a disaster 614fd6149d3SIlpo Järvinen * (but it may well be that other scenarios fail similarly). 615fd6149d3SIlpo Järvinen */ 616ea66758cSPaolo Abeni static void tcp_options_write(struct tcphdr *th, struct tcp_sock *tp, 617bd0388aeSWilliam Allen Simpson struct tcp_out_options *opts) 618bd0388aeSWilliam Allen Simpson { 619ea66758cSPaolo Abeni __be32 *ptr = (__be32 *)(th + 1); 6202100c8d2SYuchung Cheng u16 options = opts->options; /* mungable copy */ 621bd0388aeSWilliam Allen Simpson 622bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_MD5 & options)) { 6231a2c6181SChristoph Paasch *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 6241a2c6181SChristoph Paasch (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); 625bd0388aeSWilliam Allen Simpson /* overload cookie hash location */ 626bd0388aeSWilliam Allen Simpson opts->hash_location = (__u8 *)ptr; 62733ad798cSAdam Langley ptr += 4; 62833ad798cSAdam Langley } 62933ad798cSAdam Langley 630fd6149d3SIlpo Järvinen if (unlikely(opts->mss)) { 631fd6149d3SIlpo Järvinen *ptr++ = htonl((TCPOPT_MSS << 24) | 632fd6149d3SIlpo Järvinen (TCPOLEN_MSS << 16) | 633fd6149d3SIlpo Järvinen opts->mss); 634fd6149d3SIlpo Järvinen } 635fd6149d3SIlpo Järvinen 636bd0388aeSWilliam Allen Simpson if (likely(OPTION_TS & options)) { 637bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 63833ad798cSAdam Langley *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | 63933ad798cSAdam Langley (TCPOLEN_SACK_PERM << 16) | 64033ad798cSAdam Langley (TCPOPT_TIMESTAMP << 8) | 64133ad798cSAdam Langley TCPOLEN_TIMESTAMP); 642bd0388aeSWilliam Allen Simpson options &= ~OPTION_SACK_ADVERTISE; 64333ad798cSAdam Langley } else { 644496c98dfSYOSHIFUJI Hideaki *ptr++ = htonl((TCPOPT_NOP << 24) | 64540efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 64640efc6faSStephen Hemminger (TCPOPT_TIMESTAMP << 8) | 64740efc6faSStephen Hemminger TCPOLEN_TIMESTAMP); 64840efc6faSStephen Hemminger } 64933ad798cSAdam Langley *ptr++ = htonl(opts->tsval); 65033ad798cSAdam Langley *ptr++ = htonl(opts->tsecr); 65133ad798cSAdam Langley } 65233ad798cSAdam Langley 653bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 65433ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 65533ad798cSAdam Langley (TCPOPT_NOP << 16) | 65633ad798cSAdam Langley (TCPOPT_SACK_PERM << 8) | 65733ad798cSAdam Langley TCPOLEN_SACK_PERM); 65833ad798cSAdam Langley } 65933ad798cSAdam Langley 660bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_WSCALE & options)) { 66133ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 66233ad798cSAdam Langley (TCPOPT_WINDOW << 16) | 66333ad798cSAdam Langley (TCPOLEN_WINDOW << 8) | 66433ad798cSAdam Langley opts->ws); 66533ad798cSAdam Langley } 66633ad798cSAdam Langley 66733ad798cSAdam Langley if (unlikely(opts->num_sack_blocks)) { 66833ad798cSAdam Langley struct tcp_sack_block *sp = tp->rx_opt.dsack ? 66933ad798cSAdam Langley tp->duplicate_sack : tp->selective_acks; 67040efc6faSStephen Hemminger int this_sack; 67140efc6faSStephen Hemminger 67240efc6faSStephen Hemminger *ptr++ = htonl((TCPOPT_NOP << 24) | 67340efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 67440efc6faSStephen Hemminger (TCPOPT_SACK << 8) | 67533ad798cSAdam Langley (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * 67640efc6faSStephen Hemminger TCPOLEN_SACK_PERBLOCK))); 6772de979bdSStephen Hemminger 67833ad798cSAdam Langley for (this_sack = 0; this_sack < opts->num_sack_blocks; 67933ad798cSAdam Langley ++this_sack) { 68040efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].start_seq); 68140efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].end_seq); 68240efc6faSStephen Hemminger } 6832de979bdSStephen Hemminger 68440efc6faSStephen Hemminger tp->rx_opt.dsack = 0; 68540efc6faSStephen Hemminger } 6862100c8d2SYuchung Cheng 6872100c8d2SYuchung Cheng if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { 6882100c8d2SYuchung Cheng struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; 6897f9b838bSDaniel Lee u8 *p = (u8 *)ptr; 6907f9b838bSDaniel Lee u32 len; /* Fast Open option length */ 6912100c8d2SYuchung Cheng 6927f9b838bSDaniel Lee if (foc->exp) { 6937f9b838bSDaniel Lee len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; 6947f9b838bSDaniel Lee *ptr = htonl((TCPOPT_EXP << 24) | (len << 16) | 6952100c8d2SYuchung Cheng TCPOPT_FASTOPEN_MAGIC); 6967f9b838bSDaniel Lee p += TCPOLEN_EXP_FASTOPEN_BASE; 6977f9b838bSDaniel Lee } else { 6987f9b838bSDaniel Lee len = TCPOLEN_FASTOPEN_BASE + foc->len; 6997f9b838bSDaniel Lee *p++ = TCPOPT_FASTOPEN; 7007f9b838bSDaniel Lee *p++ = len; 7012100c8d2SYuchung Cheng } 7027f9b838bSDaniel Lee 7037f9b838bSDaniel Lee memcpy(p, foc->val, foc->len); 7047f9b838bSDaniel Lee if ((len & 3) == 2) { 7057f9b838bSDaniel Lee p[foc->len] = TCPOPT_NOP; 7067f9b838bSDaniel Lee p[foc->len + 1] = TCPOPT_NOP; 7077f9b838bSDaniel Lee } 7087f9b838bSDaniel Lee ptr += (len + 3) >> 2; 7092100c8d2SYuchung Cheng } 71060e2a778SUrsula Braun 71160e2a778SUrsula Braun smc_options_write(ptr, &options); 712eda7acddSPeter Krystad 713ea66758cSPaolo Abeni mptcp_options_write(th, ptr, tp, opts); 71460e2a778SUrsula Braun } 71560e2a778SUrsula Braun 71660e2a778SUrsula Braun static void smc_set_option(const struct tcp_sock *tp, 71760e2a778SUrsula Braun struct tcp_out_options *opts, 71860e2a778SUrsula Braun unsigned int *remaining) 71960e2a778SUrsula Braun { 72060e2a778SUrsula Braun #if IS_ENABLED(CONFIG_SMC) 72160e2a778SUrsula Braun if (static_branch_unlikely(&tcp_have_smc)) { 72260e2a778SUrsula Braun if (tp->syn_smc) { 72360e2a778SUrsula Braun if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { 72460e2a778SUrsula Braun opts->options |= OPTION_SMC; 72560e2a778SUrsula Braun *remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; 72660e2a778SUrsula Braun } 72760e2a778SUrsula Braun } 72860e2a778SUrsula Braun } 72960e2a778SUrsula Braun #endif 73060e2a778SUrsula Braun } 73160e2a778SUrsula Braun 73260e2a778SUrsula Braun static void smc_set_option_cond(const struct tcp_sock *tp, 73360e2a778SUrsula Braun const struct inet_request_sock *ireq, 73460e2a778SUrsula Braun struct tcp_out_options *opts, 73560e2a778SUrsula Braun unsigned int *remaining) 73660e2a778SUrsula Braun { 73760e2a778SUrsula Braun #if IS_ENABLED(CONFIG_SMC) 73860e2a778SUrsula Braun if (static_branch_unlikely(&tcp_have_smc)) { 73960e2a778SUrsula Braun if (tp->syn_smc && ireq->smc_ok) { 74060e2a778SUrsula Braun if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { 74160e2a778SUrsula Braun opts->options |= OPTION_SMC; 74260e2a778SUrsula Braun *remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; 74360e2a778SUrsula Braun } 74460e2a778SUrsula Braun } 74560e2a778SUrsula Braun } 74660e2a778SUrsula Braun #endif 74740efc6faSStephen Hemminger } 74840efc6faSStephen Hemminger 749cec37a6eSPeter Krystad static void mptcp_set_option_cond(const struct request_sock *req, 750cec37a6eSPeter Krystad struct tcp_out_options *opts, 751cec37a6eSPeter Krystad unsigned int *remaining) 752cec37a6eSPeter Krystad { 753cec37a6eSPeter Krystad if (rsk_is_mptcp(req)) { 754cec37a6eSPeter Krystad unsigned int size; 755cec37a6eSPeter Krystad 756cec37a6eSPeter Krystad if (mptcp_synack_options(req, &size, &opts->mptcp)) { 757cec37a6eSPeter Krystad if (*remaining >= size) { 758cec37a6eSPeter Krystad opts->options |= OPTION_MPTCP; 759cec37a6eSPeter Krystad *remaining -= size; 760cec37a6eSPeter Krystad } 761cec37a6eSPeter Krystad } 762cec37a6eSPeter Krystad } 763cec37a6eSPeter Krystad } 764cec37a6eSPeter Krystad 76567edfef7SAndi Kleen /* Compute TCP options for SYN packets. This is not the final 76667edfef7SAndi Kleen * network wire format yet. 76767edfef7SAndi Kleen */ 76895c96174SEric Dumazet static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, 76933ad798cSAdam Langley struct tcp_out_options *opts, 770cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 771cf533ea5SEric Dumazet { 77233ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 77395c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 774783237e8SYuchung Cheng struct tcp_fastopen_request *fastopen = tp->fastopen_req; 77533ad798cSAdam Langley 7768c2320e8SEric Dumazet *md5 = NULL; 777cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 778459837b5SDmitry Safonov if (static_branch_unlikely(&tcp_md5_needed.key) && 7796015c71eSEric Dumazet rcu_access_pointer(tp->md5sig_info)) { 78033ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 78133ad798cSAdam Langley if (*md5) { 78233ad798cSAdam Langley opts->options |= OPTION_MD5; 783bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 784cfb6eeb4SYOSHIFUJI Hideaki } 7858c2320e8SEric Dumazet } 786cfb6eeb4SYOSHIFUJI Hideaki #endif 78733ad798cSAdam Langley 78833ad798cSAdam Langley /* We always get an MSS option. The option bytes which will be seen in 78933ad798cSAdam Langley * normal data packets should timestamps be used, must be in the MSS 79033ad798cSAdam Langley * advertised. But we subtract them from tp->mss_cache so that 79133ad798cSAdam Langley * calculations in tcp_sendmsg are simpler etc. So account for this 79233ad798cSAdam Langley * fact here if necessary. If we don't do this correctly, as a 79333ad798cSAdam Langley * receiver we won't recognize data packets as being full sized when we 79433ad798cSAdam Langley * should, and thus we won't abide by the delayed ACK rules correctly. 79533ad798cSAdam Langley * SACKs don't matter, we never delay an ACK when we have any of those 79633ad798cSAdam Langley * going out. */ 79733ad798cSAdam Langley opts->mss = tcp_advertise_mss(sk); 798bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 79933ad798cSAdam Langley 8003666f666SKuniyuki Iwashima if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_timestamps) && !*md5)) { 80133ad798cSAdam Langley opts->options |= OPTION_TS; 802614e8316SEric Dumazet opts->tsval = tcp_skb_timestamp_ts(tp->tcp_usec_ts, skb) + tp->tsoffset; 80333ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 804bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 80533ad798cSAdam Langley } 8063666f666SKuniyuki Iwashima if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_window_scaling))) { 80733ad798cSAdam Langley opts->ws = tp->rx_opt.rcv_wscale; 80889e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 809bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 81033ad798cSAdam Langley } 8113666f666SKuniyuki Iwashima if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_sack))) { 81233ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 813b32d1310SDavid S. Miller if (unlikely(!(OPTION_TS & opts->options))) 814bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 81533ad798cSAdam Langley } 81633ad798cSAdam Langley 817783237e8SYuchung Cheng if (fastopen && fastopen->cookie.len >= 0) { 8182646c831SDaniel Lee u32 need = fastopen->cookie.len; 8192646c831SDaniel Lee 8202646c831SDaniel Lee need += fastopen->cookie.exp ? TCPOLEN_EXP_FASTOPEN_BASE : 8212646c831SDaniel Lee TCPOLEN_FASTOPEN_BASE; 822783237e8SYuchung Cheng need = (need + 3) & ~3U; /* Align to 32 bits */ 823783237e8SYuchung Cheng if (remaining >= need) { 824783237e8SYuchung Cheng opts->options |= OPTION_FAST_OPEN_COOKIE; 825783237e8SYuchung Cheng opts->fastopen_cookie = &fastopen->cookie; 826783237e8SYuchung Cheng remaining -= need; 827783237e8SYuchung Cheng tp->syn_fastopen = 1; 8282646c831SDaniel Lee tp->syn_fastopen_exp = fastopen->cookie.exp ? 1 : 0; 829783237e8SYuchung Cheng } 830783237e8SYuchung Cheng } 831bd0388aeSWilliam Allen Simpson 83260e2a778SUrsula Braun smc_set_option(tp, opts, &remaining); 83360e2a778SUrsula Braun 834cec37a6eSPeter Krystad if (sk_is_mptcp(sk)) { 835cec37a6eSPeter Krystad unsigned int size; 836cec37a6eSPeter Krystad 837cc7972eaSChristoph Paasch if (mptcp_syn_options(sk, skb, &size, &opts->mptcp)) { 838cec37a6eSPeter Krystad opts->options |= OPTION_MPTCP; 839cec37a6eSPeter Krystad remaining -= size; 840cec37a6eSPeter Krystad } 841cec37a6eSPeter Krystad } 842cec37a6eSPeter Krystad 843331fca43SMartin KaFai Lau bpf_skops_hdr_opt_len(sk, skb, NULL, NULL, 0, opts, &remaining); 844331fca43SMartin KaFai Lau 845bd0388aeSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 84633ad798cSAdam Langley } 84733ad798cSAdam Langley 84867edfef7SAndi Kleen /* Set up TCP options for SYN-ACKs. */ 84960e2a778SUrsula Braun static unsigned int tcp_synack_options(const struct sock *sk, 85060e2a778SUrsula Braun struct request_sock *req, 85195c96174SEric Dumazet unsigned int mss, struct sk_buff *skb, 85233ad798cSAdam Langley struct tcp_out_options *opts, 85380f03e27SEric Dumazet const struct tcp_md5sig_key *md5, 854e114e1e8SEric Dumazet struct tcp_fastopen_cookie *foc, 855331fca43SMartin KaFai Lau enum tcp_synack_type synack_type, 856331fca43SMartin KaFai Lau struct sk_buff *syn_skb) 8574957faadSWilliam Allen Simpson { 85833ad798cSAdam Langley struct inet_request_sock *ireq = inet_rsk(req); 85995c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 86033ad798cSAdam Langley 86133ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 86280f03e27SEric Dumazet if (md5) { 86333ad798cSAdam Langley opts->options |= OPTION_MD5; 8644957faadSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 8654957faadSWilliam Allen Simpson 8664957faadSWilliam Allen Simpson /* We can't fit any SACK blocks in a packet with MD5 + TS 8674957faadSWilliam Allen Simpson * options. There was discussion about disabling SACK 8684957faadSWilliam Allen Simpson * rather than TS in order to fit in better with old, 8694957faadSWilliam Allen Simpson * buggy kernels, but that was deemed to be unnecessary. 8704957faadSWilliam Allen Simpson */ 871e114e1e8SEric Dumazet if (synack_type != TCP_SYNACK_COOKIE) 872de213e5eSEric Dumazet ireq->tstamp_ok &= !ireq->sack_ok; 87333ad798cSAdam Langley } 87433ad798cSAdam Langley #endif 87533ad798cSAdam Langley 8764957faadSWilliam Allen Simpson /* We always send an MSS option. */ 87733ad798cSAdam Langley opts->mss = mss; 8784957faadSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 87933ad798cSAdam Langley 88033ad798cSAdam Langley if (likely(ireq->wscale_ok)) { 88133ad798cSAdam Langley opts->ws = ireq->rcv_wscale; 88289e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 8834957faadSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 88433ad798cSAdam Langley } 885de213e5eSEric Dumazet if (likely(ireq->tstamp_ok)) { 88633ad798cSAdam Langley opts->options |= OPTION_TS; 887614e8316SEric Dumazet opts->tsval = tcp_skb_timestamp_ts(tcp_rsk(req)->req_usec_ts, skb) + 888614e8316SEric Dumazet tcp_rsk(req)->ts_off; 889eba20811SEric Dumazet opts->tsecr = READ_ONCE(req->ts_recent); 8904957faadSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 89133ad798cSAdam Langley } 89233ad798cSAdam Langley if (likely(ireq->sack_ok)) { 89333ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 894de213e5eSEric Dumazet if (unlikely(!ireq->tstamp_ok)) 8954957faadSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 89633ad798cSAdam Langley } 8977f9b838bSDaniel Lee if (foc != NULL && foc->len >= 0) { 8987f9b838bSDaniel Lee u32 need = foc->len; 8997f9b838bSDaniel Lee 9007f9b838bSDaniel Lee need += foc->exp ? TCPOLEN_EXP_FASTOPEN_BASE : 9017f9b838bSDaniel Lee TCPOLEN_FASTOPEN_BASE; 9028336886fSJerry Chu need = (need + 3) & ~3U; /* Align to 32 bits */ 9038336886fSJerry Chu if (remaining >= need) { 9048336886fSJerry Chu opts->options |= OPTION_FAST_OPEN_COOKIE; 9058336886fSJerry Chu opts->fastopen_cookie = foc; 9068336886fSJerry Chu remaining -= need; 9078336886fSJerry Chu } 9088336886fSJerry Chu } 9094957faadSWilliam Allen Simpson 910cec37a6eSPeter Krystad mptcp_set_option_cond(req, opts, &remaining); 911cec37a6eSPeter Krystad 91260e2a778SUrsula Braun smc_set_option_cond(tcp_sk(sk), ireq, opts, &remaining); 91360e2a778SUrsula Braun 914331fca43SMartin KaFai Lau bpf_skops_hdr_opt_len((struct sock *)sk, skb, req, syn_skb, 915331fca43SMartin KaFai Lau synack_type, opts, &remaining); 916331fca43SMartin KaFai Lau 9174957faadSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 91833ad798cSAdam Langley } 91933ad798cSAdam Langley 92067edfef7SAndi Kleen /* Compute TCP options for ESTABLISHED sockets. This is not the 92167edfef7SAndi Kleen * final wire format yet. 92267edfef7SAndi Kleen */ 92395c96174SEric Dumazet static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, 92433ad798cSAdam Langley struct tcp_out_options *opts, 925cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 926cf533ea5SEric Dumazet { 92733ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 92895c96174SEric Dumazet unsigned int size = 0; 929cabeccbdSIlpo Järvinen unsigned int eff_sacks; 93033ad798cSAdam Langley 9315843ef42SAndi Kleen opts->options = 0; 9325843ef42SAndi Kleen 9338c2320e8SEric Dumazet *md5 = NULL; 93433ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 935459837b5SDmitry Safonov if (static_branch_unlikely(&tcp_md5_needed.key) && 9366015c71eSEric Dumazet rcu_access_pointer(tp->md5sig_info)) { 93733ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 9388c2320e8SEric Dumazet if (*md5) { 93933ad798cSAdam Langley opts->options |= OPTION_MD5; 94033ad798cSAdam Langley size += TCPOLEN_MD5SIG_ALIGNED; 94133ad798cSAdam Langley } 9428c2320e8SEric Dumazet } 94333ad798cSAdam Langley #endif 94433ad798cSAdam Langley 94533ad798cSAdam Langley if (likely(tp->rx_opt.tstamp_ok)) { 94633ad798cSAdam Langley opts->options |= OPTION_TS; 947614e8316SEric Dumazet opts->tsval = skb ? tcp_skb_timestamp_ts(tp->tcp_usec_ts, skb) + 948614e8316SEric Dumazet tp->tsoffset : 0; 94933ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 95033ad798cSAdam Langley size += TCPOLEN_TSTAMP_ALIGNED; 95133ad798cSAdam Langley } 95233ad798cSAdam Langley 953cec37a6eSPeter Krystad /* MPTCP options have precedence over SACK for the limited TCP 954cec37a6eSPeter Krystad * option space because a MPTCP connection would be forced to 955cec37a6eSPeter Krystad * fall back to regular TCP if a required multipath option is 956cec37a6eSPeter Krystad * missing. SACK still gets a chance to use whatever space is 957cec37a6eSPeter Krystad * left. 958cec37a6eSPeter Krystad */ 959cec37a6eSPeter Krystad if (sk_is_mptcp(sk)) { 960cec37a6eSPeter Krystad unsigned int remaining = MAX_TCP_OPTION_SPACE - size; 961cec37a6eSPeter Krystad unsigned int opt_size = 0; 962cec37a6eSPeter Krystad 963cec37a6eSPeter Krystad if (mptcp_established_options(sk, skb, &opt_size, remaining, 964cec37a6eSPeter Krystad &opts->mptcp)) { 965cec37a6eSPeter Krystad opts->options |= OPTION_MPTCP; 966cec37a6eSPeter Krystad size += opt_size; 967cec37a6eSPeter Krystad } 968cec37a6eSPeter Krystad } 969cec37a6eSPeter Krystad 970cabeccbdSIlpo Järvinen eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; 971cabeccbdSIlpo Järvinen if (unlikely(eff_sacks)) { 97295c96174SEric Dumazet const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; 9739cfcca23SMat Martineau if (unlikely(remaining < TCPOLEN_SACK_BASE_ALIGNED + 9749cfcca23SMat Martineau TCPOLEN_SACK_PERBLOCK)) 9759cfcca23SMat Martineau return size; 9769cfcca23SMat Martineau 97733ad798cSAdam Langley opts->num_sack_blocks = 97895c96174SEric Dumazet min_t(unsigned int, eff_sacks, 97933ad798cSAdam Langley (remaining - TCPOLEN_SACK_BASE_ALIGNED) / 98033ad798cSAdam Langley TCPOLEN_SACK_PERBLOCK); 9819cfcca23SMat Martineau 98233ad798cSAdam Langley size += TCPOLEN_SACK_BASE_ALIGNED + 98333ad798cSAdam Langley opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; 98433ad798cSAdam Langley } 98533ad798cSAdam Langley 986331fca43SMartin KaFai Lau if (unlikely(BPF_SOCK_OPS_TEST_FLAG(tp, 987331fca43SMartin KaFai Lau BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG))) { 988331fca43SMartin KaFai Lau unsigned int remaining = MAX_TCP_OPTION_SPACE - size; 989331fca43SMartin KaFai Lau 990331fca43SMartin KaFai Lau bpf_skops_hdr_opt_len(sk, skb, NULL, NULL, 0, opts, &remaining); 991331fca43SMartin KaFai Lau 992331fca43SMartin KaFai Lau size = MAX_TCP_OPTION_SPACE - remaining; 993331fca43SMartin KaFai Lau } 994331fca43SMartin KaFai Lau 99533ad798cSAdam Langley return size; 99640efc6faSStephen Hemminger } 9971da177e4SLinus Torvalds 99846d3ceabSEric Dumazet 99946d3ceabSEric Dumazet /* TCP SMALL QUEUES (TSQ) 100046d3ceabSEric Dumazet * 100146d3ceabSEric Dumazet * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) 100246d3ceabSEric Dumazet * to reduce RTT and bufferbloat. 100346d3ceabSEric Dumazet * We do this using a special skb destructor (tcp_wfree). 100446d3ceabSEric Dumazet * 100546d3ceabSEric Dumazet * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb 100646d3ceabSEric Dumazet * needs to be reallocated in a driver. 10078e3bff96Sstephen hemminger * The invariant being skb->truesize subtracted from sk->sk_wmem_alloc 100846d3ceabSEric Dumazet * 100946d3ceabSEric Dumazet * Since transmit from skb destructor is forbidden, we use a tasklet 101046d3ceabSEric Dumazet * to process all sockets that eventually need to send more skbs. 101146d3ceabSEric Dumazet * We use one tasklet per cpu, with its own queue of sockets. 101246d3ceabSEric Dumazet */ 101346d3ceabSEric Dumazet struct tsq_tasklet { 101446d3ceabSEric Dumazet struct tasklet_struct tasklet; 101546d3ceabSEric Dumazet struct list_head head; /* queue of tcp sockets */ 101646d3ceabSEric Dumazet }; 101746d3ceabSEric Dumazet static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); 101846d3ceabSEric Dumazet 101973a6bab5SEric Dumazet static void tcp_tsq_write(struct sock *sk) 10206f458dfbSEric Dumazet { 10216f458dfbSEric Dumazet if ((1 << sk->sk_state) & 10226f458dfbSEric Dumazet (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | 1023f9616c35SEric Dumazet TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) { 1024f9616c35SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 1025f9616c35SEric Dumazet 1026f9616c35SEric Dumazet if (tp->lost_out > tp->retrans_out && 102740570375SEric Dumazet tcp_snd_cwnd(tp) > tcp_packets_in_flight(tp)) { 10283a91d29fSKoichiro Den tcp_mstamp_refresh(tp); 1029f9616c35SEric Dumazet tcp_xmit_retransmit_queue(sk); 10303a91d29fSKoichiro Den } 1031f9616c35SEric Dumazet 1032f9616c35SEric Dumazet tcp_write_xmit(sk, tcp_current_mss(sk), tp->nonagle, 1033bf06200eSJohn Ogness 0, GFP_ATOMIC); 10346f458dfbSEric Dumazet } 1035f9616c35SEric Dumazet } 103673a6bab5SEric Dumazet 103773a6bab5SEric Dumazet static void tcp_tsq_handler(struct sock *sk) 103873a6bab5SEric Dumazet { 103973a6bab5SEric Dumazet bh_lock_sock(sk); 104073a6bab5SEric Dumazet if (!sock_owned_by_user(sk)) 104173a6bab5SEric Dumazet tcp_tsq_write(sk); 104273a6bab5SEric Dumazet else if (!test_and_set_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags)) 104373a6bab5SEric Dumazet sock_hold(sk); 104473a6bab5SEric Dumazet bh_unlock_sock(sk); 104573a6bab5SEric Dumazet } 104646d3ceabSEric Dumazet /* 10478e3bff96Sstephen hemminger * One tasklet per cpu tries to send more skbs. 104846d3ceabSEric Dumazet * We run in tasklet context but need to disable irqs when 10498e3bff96Sstephen hemminger * transferring tsq->head because tcp_wfree() might 105046d3ceabSEric Dumazet * interrupt us (non NAPI drivers) 105146d3ceabSEric Dumazet */ 1052c6533ca8SAllen Pais static void tcp_tasklet_func(struct tasklet_struct *t) 105346d3ceabSEric Dumazet { 1054c6533ca8SAllen Pais struct tsq_tasklet *tsq = from_tasklet(tsq, t, tasklet); 105546d3ceabSEric Dumazet LIST_HEAD(list); 105646d3ceabSEric Dumazet unsigned long flags; 105746d3ceabSEric Dumazet struct list_head *q, *n; 105846d3ceabSEric Dumazet struct tcp_sock *tp; 105946d3ceabSEric Dumazet struct sock *sk; 106046d3ceabSEric Dumazet 106146d3ceabSEric Dumazet local_irq_save(flags); 106246d3ceabSEric Dumazet list_splice_init(&tsq->head, &list); 106346d3ceabSEric Dumazet local_irq_restore(flags); 106446d3ceabSEric Dumazet 106546d3ceabSEric Dumazet list_for_each_safe(q, n, &list) { 106646d3ceabSEric Dumazet tp = list_entry(q, struct tcp_sock, tsq_node); 106746d3ceabSEric Dumazet list_del(&tp->tsq_node); 106846d3ceabSEric Dumazet 106946d3ceabSEric Dumazet sk = (struct sock *)tp; 10700a9648f1SEric Dumazet smp_mb__before_atomic(); 10717aa5470cSEric Dumazet clear_bit(TSQ_QUEUED, &sk->sk_tsq_flags); 10727aa5470cSEric Dumazet 10736f458dfbSEric Dumazet tcp_tsq_handler(sk); 107446d3ceabSEric Dumazet sk_free(sk); 107546d3ceabSEric Dumazet } 107646d3ceabSEric Dumazet } 107746d3ceabSEric Dumazet 107840fc3423SEric Dumazet #define TCP_DEFERRED_ALL (TCPF_TSQ_DEFERRED | \ 107940fc3423SEric Dumazet TCPF_WRITE_TIMER_DEFERRED | \ 108040fc3423SEric Dumazet TCPF_DELACK_TIMER_DEFERRED | \ 1081133c4c0dSEric Dumazet TCPF_MTU_REDUCED_DEFERRED | \ 1082133c4c0dSEric Dumazet TCPF_ACK_DEFERRED) 108346d3ceabSEric Dumazet /** 108446d3ceabSEric Dumazet * tcp_release_cb - tcp release_sock() callback 108546d3ceabSEric Dumazet * @sk: socket 108646d3ceabSEric Dumazet * 108746d3ceabSEric Dumazet * called from release_sock() to perform protocol dependent 108846d3ceabSEric Dumazet * actions before socket release. 108946d3ceabSEric Dumazet */ 109046d3ceabSEric Dumazet void tcp_release_cb(struct sock *sk) 109146d3ceabSEric Dumazet { 1092fac30731SEric Dumazet unsigned long flags = smp_load_acquire(&sk->sk_tsq_flags); 1093fac30731SEric Dumazet unsigned long nflags; 109446d3ceabSEric Dumazet 10956f458dfbSEric Dumazet /* perform an atomic operation only if at least one flag is set */ 10966f458dfbSEric Dumazet do { 10976f458dfbSEric Dumazet if (!(flags & TCP_DEFERRED_ALL)) 10986f458dfbSEric Dumazet return; 10996f458dfbSEric Dumazet nflags = flags & ~TCP_DEFERRED_ALL; 1100fac30731SEric Dumazet } while (!try_cmpxchg(&sk->sk_tsq_flags, &flags, nflags)); 11016f458dfbSEric Dumazet 110273a6bab5SEric Dumazet if (flags & TCPF_TSQ_DEFERRED) { 110373a6bab5SEric Dumazet tcp_tsq_write(sk); 110473a6bab5SEric Dumazet __sock_put(sk); 110573a6bab5SEric Dumazet } 1106c3f9b018SEric Dumazet 110740fc3423SEric Dumazet if (flags & TCPF_WRITE_TIMER_DEFERRED) { 11086f458dfbSEric Dumazet tcp_write_timer_handler(sk); 1109144d56e9SEric Dumazet __sock_put(sk); 1110144d56e9SEric Dumazet } 111140fc3423SEric Dumazet if (flags & TCPF_DELACK_TIMER_DEFERRED) { 11126f458dfbSEric Dumazet tcp_delack_timer_handler(sk); 1113144d56e9SEric Dumazet __sock_put(sk); 1114144d56e9SEric Dumazet } 111540fc3423SEric Dumazet if (flags & TCPF_MTU_REDUCED_DEFERRED) { 11164fab9071SNeal Cardwell inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); 1117144d56e9SEric Dumazet __sock_put(sk); 1118144d56e9SEric Dumazet } 1119133c4c0dSEric Dumazet if ((flags & TCPF_ACK_DEFERRED) && inet_csk_ack_scheduled(sk)) 1120133c4c0dSEric Dumazet tcp_send_ack(sk); 112146d3ceabSEric Dumazet } 112246d3ceabSEric Dumazet EXPORT_SYMBOL(tcp_release_cb); 112346d3ceabSEric Dumazet 112446d3ceabSEric Dumazet void __init tcp_tasklet_init(void) 112546d3ceabSEric Dumazet { 112646d3ceabSEric Dumazet int i; 112746d3ceabSEric Dumazet 112846d3ceabSEric Dumazet for_each_possible_cpu(i) { 112946d3ceabSEric Dumazet struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); 113046d3ceabSEric Dumazet 113146d3ceabSEric Dumazet INIT_LIST_HEAD(&tsq->head); 1132c6533ca8SAllen Pais tasklet_setup(&tsq->tasklet, tcp_tasklet_func); 113346d3ceabSEric Dumazet } 113446d3ceabSEric Dumazet } 113546d3ceabSEric Dumazet 113646d3ceabSEric Dumazet /* 113746d3ceabSEric Dumazet * Write buffer destructor automatically called from kfree_skb. 11388e3bff96Sstephen hemminger * We can't xmit new skbs from this context, as we might already 113946d3ceabSEric Dumazet * hold qdisc lock. 114046d3ceabSEric Dumazet */ 1141d6a4a104SEric Dumazet void tcp_wfree(struct sk_buff *skb) 114246d3ceabSEric Dumazet { 114346d3ceabSEric Dumazet struct sock *sk = skb->sk; 114446d3ceabSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 1145408f0a6cSEric Dumazet unsigned long flags, nval, oval; 1146b548b17aSEric Dumazet struct tsq_tasklet *tsq; 1147b548b17aSEric Dumazet bool empty; 11489b462d02SEric Dumazet 11499b462d02SEric Dumazet /* Keep one reference on sk_wmem_alloc. 11509b462d02SEric Dumazet * Will be released by sk_free() from here or tcp_tasklet_func() 11519b462d02SEric Dumazet */ 115214afee4bSReshetova, Elena WARN_ON(refcount_sub_and_test(skb->truesize - 1, &sk->sk_wmem_alloc)); 11539b462d02SEric Dumazet 11549b462d02SEric Dumazet /* If this softirq is serviced by ksoftirqd, we are likely under stress. 11559b462d02SEric Dumazet * Wait until our queues (qdisc + devices) are drained. 11569b462d02SEric Dumazet * This gives : 11579b462d02SEric Dumazet * - less callbacks to tcp_write_xmit(), reducing stress (batches) 11589b462d02SEric Dumazet * - chance for incoming ACK (processed by another cpu maybe) 11599b462d02SEric Dumazet * to migrate this flow (skb->ooo_okay will be eventually set) 11609b462d02SEric Dumazet */ 116114afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) 11629b462d02SEric Dumazet goto out; 116346d3ceabSEric Dumazet 1164b548b17aSEric Dumazet oval = smp_load_acquire(&sk->sk_tsq_flags); 1165b548b17aSEric Dumazet do { 1166408f0a6cSEric Dumazet if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED)) 1167408f0a6cSEric Dumazet goto out; 1168408f0a6cSEric Dumazet 116973a6bab5SEric Dumazet nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED; 1170b548b17aSEric Dumazet } while (!try_cmpxchg(&sk->sk_tsq_flags, &oval, nval)); 1171408f0a6cSEric Dumazet 117246d3ceabSEric Dumazet /* queue this socket to tasklet queue */ 117346d3ceabSEric Dumazet local_irq_save(flags); 1174903ceff7SChristoph Lameter tsq = this_cpu_ptr(&tsq_tasklet); 1175a9b204d1SEric Dumazet empty = list_empty(&tsq->head); 117646d3ceabSEric Dumazet list_add(&tp->tsq_node, &tsq->head); 1177a9b204d1SEric Dumazet if (empty) 117846d3ceabSEric Dumazet tasklet_schedule(&tsq->tasklet); 117946d3ceabSEric Dumazet local_irq_restore(flags); 11809b462d02SEric Dumazet return; 11819b462d02SEric Dumazet out: 11829b462d02SEric Dumazet sk_free(sk); 118346d3ceabSEric Dumazet } 118446d3ceabSEric Dumazet 118573a6bab5SEric Dumazet /* Note: Called under soft irq. 118673a6bab5SEric Dumazet * We can call TCP stack right away, unless socket is owned by user. 1187218af599SEric Dumazet */ 1188218af599SEric Dumazet enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer) 1189218af599SEric Dumazet { 1190218af599SEric Dumazet struct tcp_sock *tp = container_of(timer, struct tcp_sock, pacing_timer); 1191218af599SEric Dumazet struct sock *sk = (struct sock *)tp; 1192218af599SEric Dumazet 119373a6bab5SEric Dumazet tcp_tsq_handler(sk); 119473a6bab5SEric Dumazet sock_put(sk); 1195218af599SEric Dumazet 1196218af599SEric Dumazet return HRTIMER_NORESTART; 1197218af599SEric Dumazet } 1198218af599SEric Dumazet 1199a7a25630SEric Dumazet static void tcp_update_skb_after_send(struct sock *sk, struct sk_buff *skb, 1200a7a25630SEric Dumazet u64 prior_wstamp) 1201e2080072SEric Dumazet { 1202ab408b6dSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 1203ab408b6dSEric Dumazet 1204ab408b6dSEric Dumazet if (sk->sk_pacing_status != SK_PACING_NONE) { 120528b24f90SEric Dumazet unsigned long rate = READ_ONCE(sk->sk_pacing_rate); 1206ab408b6dSEric Dumazet 1207ab408b6dSEric Dumazet /* Original sch_fq does not pace first 10 MSS 1208ab408b6dSEric Dumazet * Note that tp->data_segs_out overflows after 2^32 packets, 1209ab408b6dSEric Dumazet * this is a minor annoyance. 1210ab408b6dSEric Dumazet */ 121176a9ebe8SEric Dumazet if (rate != ~0UL && rate && tp->data_segs_out >= 10) { 1212a7a25630SEric Dumazet u64 len_ns = div64_ul((u64)skb->len * NSEC_PER_SEC, rate); 1213a7a25630SEric Dumazet u64 credit = tp->tcp_wstamp_ns - prior_wstamp; 1214a7a25630SEric Dumazet 1215a7a25630SEric Dumazet /* take into account OS jitter */ 1216a7a25630SEric Dumazet len_ns -= min_t(u64, len_ns / 2, credit); 1217a7a25630SEric Dumazet tp->tcp_wstamp_ns += len_ns; 1218ab408b6dSEric Dumazet } 1219ab408b6dSEric Dumazet } 1220e2080072SEric Dumazet list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); 1221e2080072SEric Dumazet } 1222e2080072SEric Dumazet 122305e22e83SEric Dumazet INDIRECT_CALLABLE_DECLARE(int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)); 122405e22e83SEric Dumazet INDIRECT_CALLABLE_DECLARE(int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)); 1225dd2e0b86SEric Dumazet INDIRECT_CALLABLE_DECLARE(void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)); 122605e22e83SEric Dumazet 12271da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 12281da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 12291da177e4SLinus Torvalds * transmission and possible later retransmissions. 12301da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 12311da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 12321da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 12331da177e4SLinus Torvalds * device. 12341da177e4SLinus Torvalds * 12351da177e4SLinus Torvalds * We are working here with either a clone of the original 12361da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 12371da177e4SLinus Torvalds */ 12382987babbSYuchung Cheng static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, 12392987babbSYuchung Cheng int clone_it, gfp_t gfp_mask, u32 rcv_nxt) 12401da177e4SLinus Torvalds { 12416687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 1242dfb4b9dcSDavid S. Miller struct inet_sock *inet; 1243dfb4b9dcSDavid S. Miller struct tcp_sock *tp; 1244dfb4b9dcSDavid S. Miller struct tcp_skb_cb *tcb; 124533ad798cSAdam Langley struct tcp_out_options opts; 124695c96174SEric Dumazet unsigned int tcp_options_size, tcp_header_size; 12478c72c65bSEric Dumazet struct sk_buff *oskb = NULL; 1248cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 12491da177e4SLinus Torvalds struct tcphdr *th; 1250a7a25630SEric Dumazet u64 prior_wstamp; 12511da177e4SLinus Torvalds int err; 12521da177e4SLinus Torvalds 1253dfb4b9dcSDavid S. Miller BUG_ON(!skb || !tcp_skb_pcount(skb)); 12546f094b9eSLawrence Brakmo tp = tcp_sk(sk); 12557f12422cSYuchung Cheng prior_wstamp = tp->tcp_wstamp_ns; 12567f12422cSYuchung Cheng tp->tcp_wstamp_ns = max(tp->tcp_wstamp_ns, tp->tcp_clock_cache); 1257a1ac9c8aSMartin KaFai Lau skb_set_delivery_time(skb, tp->tcp_wstamp_ns, true); 1258ccdbb6e9SEric Dumazet if (clone_it) { 12598c72c65bSEric Dumazet oskb = skb; 1260e2080072SEric Dumazet 1261e2080072SEric Dumazet tcp_skb_tsorted_save(oskb) { 1262e2080072SEric Dumazet if (unlikely(skb_cloned(oskb))) 1263e2080072SEric Dumazet skb = pskb_copy(oskb, gfp_mask); 1264dfb4b9dcSDavid S. Miller else 1265e2080072SEric Dumazet skb = skb_clone(oskb, gfp_mask); 1266e2080072SEric Dumazet } tcp_skb_tsorted_restore(oskb); 1267e2080072SEric Dumazet 1268dfb4b9dcSDavid S. Miller if (unlikely(!skb)) 1269dfb4b9dcSDavid S. Miller return -ENOBUFS; 1270b738a185SEric Dumazet /* retransmit skbs might have a non zero value in skb->dev 1271b738a185SEric Dumazet * because skb->dev is aliased with skb->rbnode.rb_left 1272b738a185SEric Dumazet */ 1273b738a185SEric Dumazet skb->dev = NULL; 1274dfb4b9dcSDavid S. Miller } 12755f6188a8SEric Dumazet 1276dfb4b9dcSDavid S. Miller inet = inet_sk(sk); 1277dfb4b9dcSDavid S. Miller tcb = TCP_SKB_CB(skb); 127833ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 12791da177e4SLinus Torvalds 1280051ba674SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) { 128133ad798cSAdam Langley tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); 1282051ba674SEric Dumazet } else { 128333ad798cSAdam Langley tcp_options_size = tcp_established_options(sk, skb, &opts, 128433ad798cSAdam Langley &md5); 1285051ba674SEric Dumazet /* Force a PSH flag on all (GSO) packets to expedite GRO flush 1286051ba674SEric Dumazet * at receiver : This slightly improve GRO performance. 1287051ba674SEric Dumazet * Note that we do not force the PSH flag for non GSO packets, 1288051ba674SEric Dumazet * because they might be sent under high congestion events, 1289051ba674SEric Dumazet * and in this case it is better to delay the delivery of 1-MSS 1290051ba674SEric Dumazet * packets and thus the corresponding ACK packet that would 1291051ba674SEric Dumazet * release the following packet. 1292051ba674SEric Dumazet */ 1293051ba674SEric Dumazet if (tcp_skb_pcount(skb) > 1) 1294051ba674SEric Dumazet tcb->tcp_flags |= TCPHDR_PSH; 1295051ba674SEric Dumazet } 129633ad798cSAdam Langley tcp_header_size = tcp_options_size + sizeof(struct tcphdr); 12971da177e4SLinus Torvalds 1298726e9e8bSEric Dumazet /* We set skb->ooo_okay to one if this packet can select 1299726e9e8bSEric Dumazet * a different TX queue than prior packets of this flow, 1300726e9e8bSEric Dumazet * to avoid self inflicted reorders. 1301726e9e8bSEric Dumazet * The 'other' queue decision is based on current cpu number 1302726e9e8bSEric Dumazet * if XPS is enabled, or sk->sk_txhash otherwise. 1303726e9e8bSEric Dumazet * We can switch to another (and better) queue if: 1304726e9e8bSEric Dumazet * 1) No packet with payload is in qdisc/device queues. 1305726e9e8bSEric Dumazet * Delays in TX completion can defeat the test 1306726e9e8bSEric Dumazet * even if packets were already sent. 1307726e9e8bSEric Dumazet * 2) Or rtx queue is empty. 1308726e9e8bSEric Dumazet * This mitigates above case if ACK packets for 1309726e9e8bSEric Dumazet * all prior packets were already processed. 1310547669d4SEric Dumazet */ 1311726e9e8bSEric Dumazet skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1) || 1312726e9e8bSEric Dumazet tcp_rtx_queue_empty(sk); 13131da177e4SLinus Torvalds 131438ab52e8SEric Dumazet /* If we had to use memory reserve to allocate this skb, 131538ab52e8SEric Dumazet * this might cause drops if packet is looped back : 131638ab52e8SEric Dumazet * Other socket might not have SOCK_MEMALLOC. 131738ab52e8SEric Dumazet * Packets not looped back do not care about pfmemalloc. 131838ab52e8SEric Dumazet */ 131938ab52e8SEric Dumazet skb->pfmemalloc = 0; 132038ab52e8SEric Dumazet 1321aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 1322aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 132346d3ceabSEric Dumazet 132446d3ceabSEric Dumazet skb_orphan(skb); 132546d3ceabSEric Dumazet skb->sk = sk; 13261d2077acSEric Dumazet skb->destructor = skb_is_tcp_pure_ack(skb) ? __sock_wfree : tcp_wfree; 132714afee4bSReshetova, Elena refcount_add(skb->truesize, &sk->sk_wmem_alloc); 13281da177e4SLinus Torvalds 1329eb44ad4eSEric Dumazet skb_set_dst_pending_confirm(skb, READ_ONCE(sk->sk_dst_pending_confirm)); 1330c3a2e837SJulian Anastasov 13311da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 1332ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 1333c720c7e8SEric Dumazet th->source = inet->inet_sport; 1334c720c7e8SEric Dumazet th->dest = inet->inet_dport; 13351da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 13362987babbSYuchung Cheng th->ack_seq = htonl(rcv_nxt); 1337df7a3b07SAl Viro *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | 13384de075e0SEric Dumazet tcb->tcp_flags); 1339dfb4b9dcSDavid S. Miller 13401da177e4SLinus Torvalds th->check = 0; 13411da177e4SLinus Torvalds th->urg_ptr = 0; 13421da177e4SLinus Torvalds 134333f5f57eSIlpo Järvinen /* The urg_mode check is necessary during a below snd_una win probe */ 13447691367dSHerbert Xu if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { 13457691367dSHerbert Xu if (before(tp->snd_up, tcb->seq + 0x10000)) { 13461da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up - tcb->seq); 13471da177e4SLinus Torvalds th->urg = 1; 13487691367dSHerbert Xu } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { 13490eae88f3SEric Dumazet th->urg_ptr = htons(0xFFFF); 13507691367dSHerbert Xu th->urg = 1; 13517691367dSHerbert Xu } 13521da177e4SLinus Torvalds } 13531da177e4SLinus Torvalds 135451466a75SEric Dumazet skb_shinfo(skb)->gso_type = sk->sk_gso_type; 1355ea1627c2SEric Dumazet if (likely(!(tcb->tcp_flags & TCPHDR_SYN))) { 1356ea1627c2SEric Dumazet th->window = htons(tcp_select_window(sk)); 1357ea1627c2SEric Dumazet tcp_ecn_send(sk, skb, th, tcp_header_size); 1358ea1627c2SEric Dumazet } else { 1359ea1627c2SEric Dumazet /* RFC1323: The window in SYN & SYN/ACK segments 1360ea1627c2SEric Dumazet * is never scaled. 1361ea1627c2SEric Dumazet */ 1362ea1627c2SEric Dumazet th->window = htons(min(tp->rcv_wnd, 65535U)); 1363ea1627c2SEric Dumazet } 1364fa3fe2b1SFlorian Westphal 1365ea66758cSPaolo Abeni tcp_options_write(th, tp, &opts); 1366fa3fe2b1SFlorian Westphal 1367cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 1368cfb6eeb4SYOSHIFUJI Hideaki /* Calculate the MD5 hash, as we have all we need now */ 1369cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 1370aba54656SEric Dumazet sk_gso_disable(sk); 1371bd0388aeSWilliam Allen Simpson tp->af_specific->calc_md5_hash(opts.hash_location, 137239f8e58eSEric Dumazet md5, sk, skb); 1373cfb6eeb4SYOSHIFUJI Hideaki } 1374cfb6eeb4SYOSHIFUJI Hideaki #endif 1375cfb6eeb4SYOSHIFUJI Hideaki 1376331fca43SMartin KaFai Lau /* BPF prog is the last one writing header option */ 1377331fca43SMartin KaFai Lau bpf_skops_write_hdr_opt(sk, skb, NULL, NULL, 0, &opts); 1378331fca43SMartin KaFai Lau 1379dd2e0b86SEric Dumazet INDIRECT_CALL_INET(icsk->icsk_af_ops->send_check, 1380dd2e0b86SEric Dumazet tcp_v6_send_check, tcp_v4_send_check, 1381dd2e0b86SEric Dumazet sk, skb); 13821da177e4SLinus Torvalds 13834de075e0SEric Dumazet if (likely(tcb->tcp_flags & TCPHDR_ACK)) 1384059217c1SNeal Cardwell tcp_event_ack_sent(sk, rcv_nxt); 13851da177e4SLinus Torvalds 1386a44d6eacSMartin KaFai Lau if (skb->len != tcp_header_size) { 1387cf533ea5SEric Dumazet tcp_event_data_sent(tp, sk); 1388a44d6eacSMartin KaFai Lau tp->data_segs_out += tcp_skb_pcount(skb); 1389ba113c3aSWei Wang tp->bytes_sent += skb->len - tcp_header_size; 1390a44d6eacSMartin KaFai Lau } 13911da177e4SLinus Torvalds 1392bd37a088SWei Yongjun if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) 1393aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, 1394aa2ea058STom Herbert tcp_skb_pcount(skb)); 13951da177e4SLinus Torvalds 13962efd055cSMarcelo Ricardo Leitner tp->segs_out += tcp_skb_pcount(skb); 13970ae5b43dSYuchung Cheng skb_set_hash_from_sk(skb, sk); 1398f69ad292SEric Dumazet /* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */ 1399cd7d8498SEric Dumazet skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); 1400f69ad292SEric Dumazet skb_shinfo(skb)->gso_size = tcp_skb_mss(skb); 1401cd7d8498SEric Dumazet 1402d3edd06eSEric Dumazet /* Leave earliest departure time in skb->tstamp (skb->skb_mstamp_ns) */ 1403971f10ecSEric Dumazet 1404971f10ecSEric Dumazet /* Cleanup our debris for IP stacks */ 1405971f10ecSEric Dumazet memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), 1406971f10ecSEric Dumazet sizeof(struct inet6_skb_parm))); 1407971f10ecSEric Dumazet 1408a842fe14SEric Dumazet tcp_add_tx_delay(skb, tp); 1409a842fe14SEric Dumazet 141005e22e83SEric Dumazet err = INDIRECT_CALL_INET(icsk->icsk_af_ops->queue_xmit, 141105e22e83SEric Dumazet inet6_csk_xmit, ip_queue_xmit, 141205e22e83SEric Dumazet sk, skb, &inet->cork.fl); 14137faee5c0SEric Dumazet 14148c72c65bSEric Dumazet if (unlikely(err > 0)) { 14155ee2c941SChristoph Paasch tcp_enter_cwr(sk); 14168c72c65bSEric Dumazet err = net_xmit_eval(err); 14178c72c65bSEric Dumazet } 1418fc225799SEric Dumazet if (!err && oskb) { 1419a7a25630SEric Dumazet tcp_update_skb_after_send(sk, oskb, prior_wstamp); 1420fc225799SEric Dumazet tcp_rate_skb_sent(sk, oskb); 1421fc225799SEric Dumazet } 14228c72c65bSEric Dumazet return err; 14231da177e4SLinus Torvalds } 14241da177e4SLinus Torvalds 14252987babbSYuchung Cheng static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 14262987babbSYuchung Cheng gfp_t gfp_mask) 14272987babbSYuchung Cheng { 14282987babbSYuchung Cheng return __tcp_transmit_skb(sk, skb, clone_it, gfp_mask, 14292987babbSYuchung Cheng tcp_sk(sk)->rcv_nxt); 14302987babbSYuchung Cheng } 14312987babbSYuchung Cheng 143267edfef7SAndi Kleen /* This routine just queues the buffer for sending. 14331da177e4SLinus Torvalds * 14341da177e4SLinus Torvalds * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, 14351da177e4SLinus Torvalds * otherwise socket can stall. 14361da177e4SLinus Torvalds */ 14371da177e4SLinus Torvalds static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 14381da177e4SLinus Torvalds { 14391da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 14401da177e4SLinus Torvalds 14411da177e4SLinus Torvalds /* Advance write_seq and place onto the write_queue. */ 14420f317464SEric Dumazet WRITE_ONCE(tp->write_seq, TCP_SKB_CB(skb)->end_seq); 1443f4a775d1SEric Dumazet __skb_header_release(skb); 1444fe067e8aSDavid S. Miller tcp_add_write_queue_tail(sk, skb); 1445ab4e846aSEric Dumazet sk_wmem_queued_add(sk, skb->truesize); 14463ab224beSHideo Aoki sk_mem_charge(sk, skb->truesize); 14471da177e4SLinus Torvalds } 14481da177e4SLinus Torvalds 144967edfef7SAndi Kleen /* Initialize TSO segments for a packet. */ 14505bbb432cSEric Dumazet static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now) 1451f6302d1dSDavid S. Miller { 14524a64fd6cSEric Dumazet if (skb->len <= mss_now) { 1453f6302d1dSDavid S. Miller /* Avoid the costly divide in the normal 1454f6302d1dSDavid S. Miller * non-TSO case. 1455f6302d1dSDavid S. Miller */ 1456cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 1457f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = 0; 1458f6302d1dSDavid S. Miller } else { 1459cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); 1460f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = mss_now; 14611da177e4SLinus Torvalds } 14621da177e4SLinus Torvalds } 14631da177e4SLinus Torvalds 1464797108d1SIlpo Järvinen /* Pcount in the middle of the write queue got changed, we need to do various 1465797108d1SIlpo Järvinen * tweaks to fix counters 1466797108d1SIlpo Järvinen */ 1467cf533ea5SEric Dumazet static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) 1468797108d1SIlpo Järvinen { 1469797108d1SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1470797108d1SIlpo Järvinen 1471797108d1SIlpo Järvinen tp->packets_out -= decr; 1472797108d1SIlpo Järvinen 1473797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 1474797108d1SIlpo Järvinen tp->sacked_out -= decr; 1475797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) 1476797108d1SIlpo Järvinen tp->retrans_out -= decr; 1477797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) 1478797108d1SIlpo Järvinen tp->lost_out -= decr; 1479797108d1SIlpo Järvinen 1480797108d1SIlpo Järvinen /* Reno case is special. Sigh... */ 1481797108d1SIlpo Järvinen if (tcp_is_reno(tp) && decr > 0) 1482797108d1SIlpo Järvinen tp->sacked_out -= min_t(u32, tp->sacked_out, decr); 1483797108d1SIlpo Järvinen 1484797108d1SIlpo Järvinen if (tp->lost_skb_hint && 1485797108d1SIlpo Järvinen before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && 1486713bafeaSYuchung Cheng (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) 1487797108d1SIlpo Järvinen tp->lost_cnt_hint -= decr; 1488797108d1SIlpo Järvinen 1489797108d1SIlpo Järvinen tcp_verify_left_out(tp); 1490797108d1SIlpo Järvinen } 1491797108d1SIlpo Järvinen 14920a2cf20cSSoheil Hassas Yeganeh static bool tcp_has_tx_tstamp(const struct sk_buff *skb) 14930a2cf20cSSoheil Hassas Yeganeh { 14940a2cf20cSSoheil Hassas Yeganeh return TCP_SKB_CB(skb)->txstamp_ack || 14950a2cf20cSSoheil Hassas Yeganeh (skb_shinfo(skb)->tx_flags & SKBTX_ANY_TSTAMP); 14960a2cf20cSSoheil Hassas Yeganeh } 14970a2cf20cSSoheil Hassas Yeganeh 1498490cc7d0SWillem de Bruijn static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) 1499490cc7d0SWillem de Bruijn { 1500490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo = skb_shinfo(skb); 1501490cc7d0SWillem de Bruijn 15020a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(skb)) && 1503490cc7d0SWillem de Bruijn !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { 1504490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo2 = skb_shinfo(skb2); 1505490cc7d0SWillem de Bruijn u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; 1506490cc7d0SWillem de Bruijn 1507490cc7d0SWillem de Bruijn shinfo->tx_flags &= ~tsflags; 1508490cc7d0SWillem de Bruijn shinfo2->tx_flags |= tsflags; 1509490cc7d0SWillem de Bruijn swap(shinfo->tskey, shinfo2->tskey); 1510b51e13faSMartin KaFai Lau TCP_SKB_CB(skb2)->txstamp_ack = TCP_SKB_CB(skb)->txstamp_ack; 1511b51e13faSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack = 0; 1512490cc7d0SWillem de Bruijn } 1513490cc7d0SWillem de Bruijn } 1514490cc7d0SWillem de Bruijn 1515a166140eSMartin KaFai Lau static void tcp_skb_fragment_eor(struct sk_buff *skb, struct sk_buff *skb2) 1516a166140eSMartin KaFai Lau { 1517a166140eSMartin KaFai Lau TCP_SKB_CB(skb2)->eor = TCP_SKB_CB(skb)->eor; 1518a166140eSMartin KaFai Lau TCP_SKB_CB(skb)->eor = 0; 1519a166140eSMartin KaFai Lau } 1520a166140eSMartin KaFai Lau 152175c119afSEric Dumazet /* Insert buff after skb on the write or rtx queue of sk. */ 152275c119afSEric Dumazet static void tcp_insert_write_queue_after(struct sk_buff *skb, 152375c119afSEric Dumazet struct sk_buff *buff, 152475c119afSEric Dumazet struct sock *sk, 152575c119afSEric Dumazet enum tcp_queue tcp_queue) 152675c119afSEric Dumazet { 152775c119afSEric Dumazet if (tcp_queue == TCP_FRAG_IN_WRITE_QUEUE) 152875c119afSEric Dumazet __skb_queue_after(&sk->sk_write_queue, skb, buff); 152975c119afSEric Dumazet else 153075c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, buff); 153175c119afSEric Dumazet } 153275c119afSEric Dumazet 15331da177e4SLinus Torvalds /* Function to create two new TCP segments. Shrinks the given segment 15341da177e4SLinus Torvalds * to the specified size and appends a new segment with the rest of the 15351da177e4SLinus Torvalds * packet to the list. This won't be called frequently, I hope. 15361da177e4SLinus Torvalds * Remember, these are still headerless SKBs at this point. 15371da177e4SLinus Torvalds */ 153875c119afSEric Dumazet int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, 153975c119afSEric Dumazet struct sk_buff *skb, u32 len, 15406cc55e09SOctavian Purdila unsigned int mss_now, gfp_t gfp) 15411da177e4SLinus Torvalds { 15421da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 15431da177e4SLinus Torvalds struct sk_buff *buff; 1544b4a24397SEric Dumazet int old_factor; 1545b617158dSEric Dumazet long limit; 1546b60b49eaSHerbert Xu int nlen; 15479ce01461SIlpo Järvinen u8 flags; 15481da177e4SLinus Torvalds 15492fceec13SIlpo Järvinen if (WARN_ON(len > skb->len)) 15502fceec13SIlpo Järvinen return -EINVAL; 15516a438bbeSStephen Hemminger 1552b4a24397SEric Dumazet DEBUG_NET_WARN_ON_ONCE(skb_headlen(skb)); 15531da177e4SLinus Torvalds 1554b617158dSEric Dumazet /* tcp_sendmsg() can overshoot sk_wmem_queued by one full size skb. 1555b617158dSEric Dumazet * We need some allowance to not penalize applications setting small 1556b617158dSEric Dumazet * SO_SNDBUF values. 1557b617158dSEric Dumazet * Also allow first and last skb in retransmit queue to be split. 1558b617158dSEric Dumazet */ 15597c4e983cSAlexander Duyck limit = sk->sk_sndbuf + 2 * SKB_TRUESIZE(GSO_LEGACY_MAX_SIZE); 1560b617158dSEric Dumazet if (unlikely((sk->sk_wmem_queued >> 1) > limit && 1561b617158dSEric Dumazet tcp_queue != TCP_FRAG_IN_WRITE_QUEUE && 1562b617158dSEric Dumazet skb != tcp_rtx_queue_head(sk) && 1563b617158dSEric Dumazet skb != tcp_rtx_queue_tail(sk))) { 1564f070ef2aSEric Dumazet NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPWQUEUETOOBIG); 1565f070ef2aSEric Dumazet return -ENOMEM; 1566f070ef2aSEric Dumazet } 1567f070ef2aSEric Dumazet 1568c4777efaSEric Dumazet if (skb_unclone_keeptruesize(skb, gfp)) 15691da177e4SLinus Torvalds return -ENOMEM; 15701da177e4SLinus Torvalds 15711da177e4SLinus Torvalds /* Get a new skb... force flag on. */ 15725882efffSEric Dumazet buff = tcp_stream_alloc_skb(sk, gfp, true); 157351456b29SIan Morris if (!buff) 15741da177e4SLinus Torvalds return -ENOMEM; /* We'll just try again later. */ 157541477662SJakub Kicinski skb_copy_decrypted(buff, skb); 15765a369ca6SPaolo Abeni mptcp_skb_ext_copy(buff, skb); 1577ef5cb973SHerbert Xu 1578ab4e846aSEric Dumazet sk_wmem_queued_add(sk, buff->truesize); 15793ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1580b4a24397SEric Dumazet nlen = skb->len - len; 1581b60b49eaSHerbert Xu buff->truesize += nlen; 1582b60b49eaSHerbert Xu skb->truesize -= nlen; 15831da177e4SLinus Torvalds 15841da177e4SLinus Torvalds /* Correct the sequence numbers. */ 15851da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 15861da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 15871da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 15881da177e4SLinus Torvalds 15891da177e4SLinus Torvalds /* PSH and FIN should only be set in the second packet. */ 15904de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 15914de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 15924de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1593e14c3cafSHerbert Xu TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; 1594a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 15951da177e4SLinus Torvalds 15961da177e4SLinus Torvalds skb_split(skb, buff, len); 15971da177e4SLinus Torvalds 1598a1ac9c8aSMartin KaFai Lau skb_set_delivery_time(buff, skb->tstamp, true); 1599490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 16001da177e4SLinus Torvalds 16016475be16SDavid S. Miller old_factor = tcp_skb_pcount(skb); 16026475be16SDavid S. Miller 16031da177e4SLinus Torvalds /* Fix up tso_factor for both original and new SKB. */ 16045bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 16055bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 16061da177e4SLinus Torvalds 1607b9f64820SYuchung Cheng /* Update delivered info for the new segment */ 1608b9f64820SYuchung Cheng TCP_SKB_CB(buff)->tx = TCP_SKB_CB(skb)->tx; 1609b9f64820SYuchung Cheng 16106475be16SDavid S. Miller /* If this packet has been sent out already, we must 16116475be16SDavid S. Miller * adjust the various packet counters. 16126475be16SDavid S. Miller */ 1613cf0b450cSHerbert Xu if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { 16146475be16SDavid S. Miller int diff = old_factor - tcp_skb_pcount(skb) - 16156475be16SDavid S. Miller tcp_skb_pcount(buff); 16161da177e4SLinus Torvalds 1617797108d1SIlpo Järvinen if (diff) 1618797108d1SIlpo Järvinen tcp_adjust_pcount(sk, skb, diff); 16191da177e4SLinus Torvalds } 16201da177e4SLinus Torvalds 16211da177e4SLinus Torvalds /* Link BUFF into the send queue. */ 1622f4a775d1SEric Dumazet __skb_header_release(buff); 162375c119afSEric Dumazet tcp_insert_write_queue_after(skb, buff, sk, tcp_queue); 1624f67971e6SEric Dumazet if (tcp_queue == TCP_FRAG_IN_RTX_QUEUE) 1625e2080072SEric Dumazet list_add(&buff->tcp_tsorted_anchor, &skb->tcp_tsorted_anchor); 16261da177e4SLinus Torvalds 16271da177e4SLinus Torvalds return 0; 16281da177e4SLinus Torvalds } 16291da177e4SLinus Torvalds 1630f4d01666SEric Dumazet /* This is similar to __pskb_pull_tail(). The difference is that pulled 1631f4d01666SEric Dumazet * data is not copied, but immediately discarded. 16321da177e4SLinus Torvalds */ 16337162fb24SEric Dumazet static int __pskb_trim_head(struct sk_buff *skb, int len) 16341da177e4SLinus Torvalds { 16357b7fc97aSEric Dumazet struct skb_shared_info *shinfo; 16361da177e4SLinus Torvalds int i, k, eat; 16371da177e4SLinus Torvalds 1638b4a24397SEric Dumazet DEBUG_NET_WARN_ON_ONCE(skb_headlen(skb)); 16391da177e4SLinus Torvalds eat = len; 16401da177e4SLinus Torvalds k = 0; 16417b7fc97aSEric Dumazet shinfo = skb_shinfo(skb); 16427b7fc97aSEric Dumazet for (i = 0; i < shinfo->nr_frags; i++) { 16437b7fc97aSEric Dumazet int size = skb_frag_size(&shinfo->frags[i]); 16449e903e08SEric Dumazet 16459e903e08SEric Dumazet if (size <= eat) { 1646aff65da0SIan Campbell skb_frag_unref(skb, i); 16479e903e08SEric Dumazet eat -= size; 16481da177e4SLinus Torvalds } else { 16497b7fc97aSEric Dumazet shinfo->frags[k] = shinfo->frags[i]; 16501da177e4SLinus Torvalds if (eat) { 1651b54c9d5bSJonathan Lemon skb_frag_off_add(&shinfo->frags[k], eat); 16527b7fc97aSEric Dumazet skb_frag_size_sub(&shinfo->frags[k], eat); 16531da177e4SLinus Torvalds eat = 0; 16541da177e4SLinus Torvalds } 16551da177e4SLinus Torvalds k++; 16561da177e4SLinus Torvalds } 16571da177e4SLinus Torvalds } 16587b7fc97aSEric Dumazet shinfo->nr_frags = k; 16591da177e4SLinus Torvalds 16601da177e4SLinus Torvalds skb->data_len -= len; 16611da177e4SLinus Torvalds skb->len = skb->data_len; 16627162fb24SEric Dumazet return len; 16631da177e4SLinus Torvalds } 16641da177e4SLinus Torvalds 166567edfef7SAndi Kleen /* Remove acked data from a packet in the transmit queue. */ 16661da177e4SLinus Torvalds int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 16671da177e4SLinus Torvalds { 16687162fb24SEric Dumazet u32 delta_truesize; 16697162fb24SEric Dumazet 1670c4777efaSEric Dumazet if (skb_unclone_keeptruesize(skb, GFP_ATOMIC)) 16711da177e4SLinus Torvalds return -ENOMEM; 16721da177e4SLinus Torvalds 16737162fb24SEric Dumazet delta_truesize = __pskb_trim_head(skb, len); 16741da177e4SLinus Torvalds 16751da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq += len; 16761da177e4SLinus Torvalds 16777162fb24SEric Dumazet skb->truesize -= delta_truesize; 1678ab4e846aSEric Dumazet sk_wmem_queued_add(sk, -delta_truesize); 16799b65b17dSTalal Ahmad if (!skb_zcopy_pure(skb)) 16807162fb24SEric Dumazet sk_mem_uncharge(sk, delta_truesize); 16811da177e4SLinus Torvalds 16825b35e1e6SNeal Cardwell /* Any change of skb->len requires recalculation of tso factor. */ 16831da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 16845bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb)); 16851da177e4SLinus Torvalds 16861da177e4SLinus Torvalds return 0; 16871da177e4SLinus Torvalds } 16881da177e4SLinus Torvalds 16891b63edd6SYuchung Cheng /* Calculate MSS not accounting any TCP options. */ 16901b63edd6SYuchung Cheng static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) 16915d424d5aSJohn Heffner { 1692cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1693cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 16945d424d5aSJohn Heffner int mss_now; 16955d424d5aSJohn Heffner 16965d424d5aSJohn Heffner /* Calculate base mss without TCP options: 16975d424d5aSJohn Heffner It is MMS_S - sizeof(tcphdr) of rfc1122 16985d424d5aSJohn Heffner */ 16995d424d5aSJohn Heffner mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); 17005d424d5aSJohn Heffner 17015d424d5aSJohn Heffner /* Clamp it (mss_clamp does not include tcp options) */ 17025d424d5aSJohn Heffner if (mss_now > tp->rx_opt.mss_clamp) 17035d424d5aSJohn Heffner mss_now = tp->rx_opt.mss_clamp; 17045d424d5aSJohn Heffner 17055d424d5aSJohn Heffner /* Now subtract optional transport overhead */ 17065d424d5aSJohn Heffner mss_now -= icsk->icsk_ext_hdr_len; 17075d424d5aSJohn Heffner 17085d424d5aSJohn Heffner /* Then reserve room for full set of TCP options and 8 bytes of data */ 170978eb166cSKuniyuki Iwashima mss_now = max(mss_now, 171078eb166cSKuniyuki Iwashima READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_snd_mss)); 17115d424d5aSJohn Heffner return mss_now; 17125d424d5aSJohn Heffner } 17135d424d5aSJohn Heffner 17141b63edd6SYuchung Cheng /* Calculate MSS. Not accounting for SACKs here. */ 17151b63edd6SYuchung Cheng int tcp_mtu_to_mss(struct sock *sk, int pmtu) 17161b63edd6SYuchung Cheng { 17171b63edd6SYuchung Cheng /* Subtract TCP options size, not including SACKs */ 17181b63edd6SYuchung Cheng return __tcp_mtu_to_mss(sk, pmtu) - 17191b63edd6SYuchung Cheng (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); 17201b63edd6SYuchung Cheng } 1721c7bb4b89SEric Dumazet EXPORT_SYMBOL(tcp_mtu_to_mss); 17221b63edd6SYuchung Cheng 17235d424d5aSJohn Heffner /* Inverse of above */ 172467469601SEric Dumazet int tcp_mss_to_mtu(struct sock *sk, int mss) 17255d424d5aSJohn Heffner { 1726cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1727cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 17285d424d5aSJohn Heffner 1729e57a3447SYan Zhai return mss + 17305d424d5aSJohn Heffner tp->tcp_header_len + 17315d424d5aSJohn Heffner icsk->icsk_ext_hdr_len + 17325d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 17335d424d5aSJohn Heffner } 1734556c6b46SNeal Cardwell EXPORT_SYMBOL(tcp_mss_to_mtu); 17355d424d5aSJohn Heffner 173667edfef7SAndi Kleen /* MTU probing init per socket */ 17375d424d5aSJohn Heffner void tcp_mtup_init(struct sock *sk) 17385d424d5aSJohn Heffner { 17395d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 17405d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 1741b0f9ca53SFan Du struct net *net = sock_net(sk); 17425d424d5aSJohn Heffner 1743f47d00e0SKuniyuki Iwashima icsk->icsk_mtup.enabled = READ_ONCE(net->ipv4.sysctl_tcp_mtu_probing) > 1; 17445d424d5aSJohn Heffner icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + 17455d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 174688d78bc0SKuniyuki Iwashima icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, READ_ONCE(net->ipv4.sysctl_tcp_base_mss)); 17475d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 174805cbc0dbSFan Du if (icsk->icsk_mtup.enabled) 1749c74df29aSEric Dumazet icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; 17505d424d5aSJohn Heffner } 17514bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_mtup_init); 17525d424d5aSJohn Heffner 17531da177e4SLinus Torvalds /* This function synchronize snd mss to current pmtu/exthdr set. 17541da177e4SLinus Torvalds 17551da177e4SLinus Torvalds tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts 17561da177e4SLinus Torvalds for TCP options, but includes only bare TCP header. 17571da177e4SLinus Torvalds 17581da177e4SLinus Torvalds tp->rx_opt.mss_clamp is mss negotiated at connection setup. 1759caa20d9aSStephen Hemminger It is minimum of user_mss and mss received with SYN. 17601da177e4SLinus Torvalds It also does not include TCP options. 17611da177e4SLinus Torvalds 1762d83d8461SArnaldo Carvalho de Melo inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. 17631da177e4SLinus Torvalds 17641da177e4SLinus Torvalds tp->mss_cache is current effective sending mss, including 17651da177e4SLinus Torvalds all tcp options except for SACKs. It is evaluated, 17661da177e4SLinus Torvalds taking into account current pmtu, but never exceeds 17671da177e4SLinus Torvalds tp->rx_opt.mss_clamp. 17681da177e4SLinus Torvalds 17691da177e4SLinus Torvalds NOTE1. rfc1122 clearly states that advertised MSS 17701da177e4SLinus Torvalds DOES NOT include either tcp or ip options. 17711da177e4SLinus Torvalds 1772d83d8461SArnaldo Carvalho de Melo NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache 1773d83d8461SArnaldo Carvalho de Melo are READ ONLY outside this function. --ANK (980731) 17741da177e4SLinus Torvalds */ 17751da177e4SLinus Torvalds unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 17761da177e4SLinus Torvalds { 17771da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1778d83d8461SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 17795d424d5aSJohn Heffner int mss_now; 17801da177e4SLinus Torvalds 17815d424d5aSJohn Heffner if (icsk->icsk_mtup.search_high > pmtu) 17825d424d5aSJohn Heffner icsk->icsk_mtup.search_high = pmtu; 17831da177e4SLinus Torvalds 17845d424d5aSJohn Heffner mss_now = tcp_mtu_to_mss(sk, pmtu); 1785409d22b4SIlpo Järvinen mss_now = tcp_bound_to_half_wnd(tp, mss_now); 17861da177e4SLinus Torvalds 17871da177e4SLinus Torvalds /* And store cached results */ 1788d83d8461SArnaldo Carvalho de Melo icsk->icsk_pmtu_cookie = pmtu; 17895d424d5aSJohn Heffner if (icsk->icsk_mtup.enabled) 17905d424d5aSJohn Heffner mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); 1791c1b4a7e6SDavid S. Miller tp->mss_cache = mss_now; 17921da177e4SLinus Torvalds 17931da177e4SLinus Torvalds return mss_now; 17941da177e4SLinus Torvalds } 17954bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_sync_mss); 17961da177e4SLinus Torvalds 17971da177e4SLinus Torvalds /* Compute the current effective MSS, taking SACKs and IP options, 17981da177e4SLinus Torvalds * and even PMTU discovery events into account. 17991da177e4SLinus Torvalds */ 18000c54b85fSIlpo Järvinen unsigned int tcp_current_mss(struct sock *sk) 18011da177e4SLinus Torvalds { 1802cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1803cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1804c1b4a7e6SDavid S. Miller u32 mss_now; 180595c96174SEric Dumazet unsigned int header_len; 180633ad798cSAdam Langley struct tcp_out_options opts; 180733ad798cSAdam Langley struct tcp_md5sig_key *md5; 18081da177e4SLinus Torvalds 1809c1b4a7e6SDavid S. Miller mss_now = tp->mss_cache; 1810c1b4a7e6SDavid S. Miller 18111da177e4SLinus Torvalds if (dst) { 18121da177e4SLinus Torvalds u32 mtu = dst_mtu(dst); 1813d83d8461SArnaldo Carvalho de Melo if (mtu != inet_csk(sk)->icsk_pmtu_cookie) 18141da177e4SLinus Torvalds mss_now = tcp_sync_mss(sk, mtu); 18151da177e4SLinus Torvalds } 18161da177e4SLinus Torvalds 181733ad798cSAdam Langley header_len = tcp_established_options(sk, NULL, &opts, &md5) + 181833ad798cSAdam Langley sizeof(struct tcphdr); 181933ad798cSAdam Langley /* The mss_cache is sized based on tp->tcp_header_len, which assumes 182033ad798cSAdam Langley * some common options. If this is an odd packet (because we have SACK 182133ad798cSAdam Langley * blocks etc) then our calculated header_len will be different, and 182233ad798cSAdam Langley * we have to adjust mss_now correspondingly */ 182333ad798cSAdam Langley if (header_len != tp->tcp_header_len) { 182433ad798cSAdam Langley int delta = (int) header_len - tp->tcp_header_len; 182533ad798cSAdam Langley mss_now -= delta; 182633ad798cSAdam Langley } 1827cfb6eeb4SYOSHIFUJI Hideaki 18281da177e4SLinus Torvalds return mss_now; 18291da177e4SLinus Torvalds } 18301da177e4SLinus Torvalds 183186fd14adSWeiping Pan /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. 183286fd14adSWeiping Pan * As additional protections, we do not touch cwnd in retransmission phases, 183386fd14adSWeiping Pan * and if application hit its sndbuf limit recently. 183486fd14adSWeiping Pan */ 183586fd14adSWeiping Pan static void tcp_cwnd_application_limited(struct sock *sk) 1836a762a980SDavid S. Miller { 18379e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1838a762a980SDavid S. Miller 183986fd14adSWeiping Pan if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && 184086fd14adSWeiping Pan sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { 184186fd14adSWeiping Pan /* Limited by application or receiver window. */ 184286fd14adSWeiping Pan u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); 184386fd14adSWeiping Pan u32 win_used = max(tp->snd_cwnd_used, init_win); 184440570375SEric Dumazet if (win_used < tcp_snd_cwnd(tp)) { 184586fd14adSWeiping Pan tp->snd_ssthresh = tcp_current_ssthresh(sk); 184640570375SEric Dumazet tcp_snd_cwnd_set(tp, (tcp_snd_cwnd(tp) + win_used) >> 1); 184786fd14adSWeiping Pan } 184886fd14adSWeiping Pan tp->snd_cwnd_used = 0; 184986fd14adSWeiping Pan } 1850c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 185186fd14adSWeiping Pan } 185286fd14adSWeiping Pan 1853ca8a2263SNeal Cardwell static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) 1854a762a980SDavid S. Miller { 18551b1fc3fdSWei Wang const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1856a762a980SDavid S. Miller struct tcp_sock *tp = tcp_sk(sk); 1857a762a980SDavid S. Miller 1858f4ce91ceSNeal Cardwell /* Track the strongest available signal of the degree to which the cwnd 1859f4ce91ceSNeal Cardwell * is fully utilized. If cwnd-limited then remember that fact for the 1860f4ce91ceSNeal Cardwell * current window. If not cwnd-limited then track the maximum number of 1861f4ce91ceSNeal Cardwell * outstanding packets in the current window. (If cwnd-limited then we 1862f4ce91ceSNeal Cardwell * chose to not update tp->max_packets_out to avoid an extra else 1863f4ce91ceSNeal Cardwell * clause with no functional impact.) 1864ca8a2263SNeal Cardwell */ 1865f4ce91ceSNeal Cardwell if (!before(tp->snd_una, tp->cwnd_usage_seq) || 1866f4ce91ceSNeal Cardwell is_cwnd_limited || 1867f4ce91ceSNeal Cardwell (!tp->is_cwnd_limited && 1868f4ce91ceSNeal Cardwell tp->packets_out > tp->max_packets_out)) { 1869ca8a2263SNeal Cardwell tp->is_cwnd_limited = is_cwnd_limited; 1870f4ce91ceSNeal Cardwell tp->max_packets_out = tp->packets_out; 1871f4ce91ceSNeal Cardwell tp->cwnd_usage_seq = tp->snd_nxt; 1872ca8a2263SNeal Cardwell } 1873e114a710SEric Dumazet 187424901551SEric Dumazet if (tcp_is_cwnd_limited(sk)) { 1875a762a980SDavid S. Miller /* Network is feed fully. */ 1876a762a980SDavid S. Miller tp->snd_cwnd_used = 0; 1877c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 1878a762a980SDavid S. Miller } else { 1879a762a980SDavid S. Miller /* Network starves. */ 1880a762a980SDavid S. Miller if (tp->packets_out > tp->snd_cwnd_used) 1881a762a980SDavid S. Miller tp->snd_cwnd_used = tp->packets_out; 1882a762a980SDavid S. Miller 18834845b571SKuniyuki Iwashima if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) && 1884c2203cf7SEric Dumazet (s32)(tcp_jiffies32 - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto && 18851b1fc3fdSWei Wang !ca_ops->cong_control) 1886a762a980SDavid S. Miller tcp_cwnd_application_limited(sk); 1887b0f71bd3SFrancis Yan 1888b0f71bd3SFrancis Yan /* The following conditions together indicate the starvation 1889b0f71bd3SFrancis Yan * is caused by insufficient sender buffer: 1890b0f71bd3SFrancis Yan * 1) just sent some data (see tcp_write_xmit) 1891b0f71bd3SFrancis Yan * 2) not cwnd limited (this else condition) 189275c119afSEric Dumazet * 3) no more data to send (tcp_write_queue_empty()) 1893b0f71bd3SFrancis Yan * 4) application is hitting buffer limit (SOCK_NOSPACE) 1894b0f71bd3SFrancis Yan */ 189575c119afSEric Dumazet if (tcp_write_queue_empty(sk) && sk->sk_socket && 1896b0f71bd3SFrancis Yan test_bit(SOCK_NOSPACE, &sk->sk_socket->flags) && 1897b0f71bd3SFrancis Yan (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) 1898b0f71bd3SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_SNDBUF_LIMITED); 1899a762a980SDavid S. Miller } 1900a762a980SDavid S. Miller } 1901a762a980SDavid S. Miller 1902d4589926SEric Dumazet /* Minshall's variant of the Nagle send check. */ 1903d4589926SEric Dumazet static bool tcp_minshall_check(const struct tcp_sock *tp) 1904d4589926SEric Dumazet { 1905d4589926SEric Dumazet return after(tp->snd_sml, tp->snd_una) && 1906d4589926SEric Dumazet !after(tp->snd_sml, tp->snd_nxt); 1907d4589926SEric Dumazet } 1908d4589926SEric Dumazet 1909d4589926SEric Dumazet /* Update snd_sml if this skb is under mss 1910d4589926SEric Dumazet * Note that a TSO packet might end with a sub-mss segment 1911d4589926SEric Dumazet * The test is really : 1912d4589926SEric Dumazet * if ((skb->len % mss) != 0) 1913d4589926SEric Dumazet * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1914d4589926SEric Dumazet * But we can avoid doing the divide again given we already have 1915d4589926SEric Dumazet * skb_pcount = skb->len / mss_now 19160e3a4803SIlpo Järvinen */ 1917d4589926SEric Dumazet static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, 1918d4589926SEric Dumazet const struct sk_buff *skb) 1919d4589926SEric Dumazet { 1920d4589926SEric Dumazet if (skb->len < tcp_skb_pcount(skb) * mss_now) 1921d4589926SEric Dumazet tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1922d4589926SEric Dumazet } 1923d4589926SEric Dumazet 1924d4589926SEric Dumazet /* Return false, if packet can be sent now without violation Nagle's rules: 1925d4589926SEric Dumazet * 1. It is full sized. (provided by caller in %partial bool) 1926d4589926SEric Dumazet * 2. Or it contains FIN. (already checked by caller) 1927d4589926SEric Dumazet * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. 1928d4589926SEric Dumazet * 4. Or TCP_CORK is not set, and all sent packets are ACKed. 1929d4589926SEric Dumazet * With Minshall's modification: all sent small packets are ACKed. 1930d4589926SEric Dumazet */ 1931d4589926SEric Dumazet static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, 1932cc93fc51SPeter Pan(潘卫平) int nonagle) 1933d4589926SEric Dumazet { 1934d4589926SEric Dumazet return partial && 1935d4589926SEric Dumazet ((nonagle & TCP_NAGLE_CORK) || 1936d4589926SEric Dumazet (!nonagle && tp->packets_out && tcp_minshall_check(tp))); 1937d4589926SEric Dumazet } 1938605ad7f1SEric Dumazet 1939605ad7f1SEric Dumazet /* Return how many segs we'd like on a TSO packet, 194065466904SEric Dumazet * depending on current pacing rate, and how close the peer is. 194165466904SEric Dumazet * 194265466904SEric Dumazet * Rationale is: 194365466904SEric Dumazet * - For close peers, we rather send bigger packets to reduce 194465466904SEric Dumazet * cpu costs, because occasional losses will be repaired fast. 194565466904SEric Dumazet * - For long distance/rtt flows, we would like to get ACK clocking 194665466904SEric Dumazet * with 1 ACK per ms. 194765466904SEric Dumazet * 194865466904SEric Dumazet * Use min_rtt to help adapt TSO burst size, with smaller min_rtt resulting 194965466904SEric Dumazet * in bigger TSO bursts. We we cut the RTT-based allowance in half 195065466904SEric Dumazet * for every 2^9 usec (aka 512 us) of RTT, so that the RTT-based allowance 195165466904SEric Dumazet * is below 1500 bytes after 6 * ~500 usec = 3ms. 1952605ad7f1SEric Dumazet */ 1953dcb8c9b4SEric Dumazet static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, 19541b3878caSNeal Cardwell int min_tso_segs) 1955605ad7f1SEric Dumazet { 195665466904SEric Dumazet unsigned long bytes; 195765466904SEric Dumazet u32 r; 1958605ad7f1SEric Dumazet 195928b24f90SEric Dumazet bytes = READ_ONCE(sk->sk_pacing_rate) >> READ_ONCE(sk->sk_pacing_shift); 1960605ad7f1SEric Dumazet 19612455e61bSKuniyuki Iwashima r = tcp_min_rtt(tcp_sk(sk)) >> READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_rtt_log); 196265466904SEric Dumazet if (r < BITS_PER_TYPE(sk->sk_gso_max_size)) 196365466904SEric Dumazet bytes += sk->sk_gso_max_size >> r; 1964605ad7f1SEric Dumazet 196565466904SEric Dumazet bytes = min_t(unsigned long, bytes, sk->sk_gso_max_size); 196665466904SEric Dumazet 196765466904SEric Dumazet return max_t(u32, bytes / mss_now, min_tso_segs); 1968605ad7f1SEric Dumazet } 1969605ad7f1SEric Dumazet 1970ed6e7268SNeal Cardwell /* Return the number of segments we want in the skb we are transmitting. 1971ed6e7268SNeal Cardwell * See if congestion control module wants to decide; otherwise, autosize. 1972ed6e7268SNeal Cardwell */ 1973ed6e7268SNeal Cardwell static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now) 1974ed6e7268SNeal Cardwell { 1975ed6e7268SNeal Cardwell const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1976dcb8c9b4SEric Dumazet u32 min_tso, tso_segs; 1977ed6e7268SNeal Cardwell 1978dcb8c9b4SEric Dumazet min_tso = ca_ops->min_tso_segs ? 1979dcb8c9b4SEric Dumazet ca_ops->min_tso_segs(sk) : 1980e0bb4ab9SKuniyuki Iwashima READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs); 1981dcb8c9b4SEric Dumazet 1982dcb8c9b4SEric Dumazet tso_segs = tcp_tso_autosize(sk, mss_now, min_tso); 1983350c9f48SEric Dumazet return min_t(u32, tso_segs, sk->sk_gso_max_segs); 1984ed6e7268SNeal Cardwell } 1985ed6e7268SNeal Cardwell 1986d4589926SEric Dumazet /* Returns the portion of skb which can be sent right away */ 1987d4589926SEric Dumazet static unsigned int tcp_mss_split_point(const struct sock *sk, 1988d4589926SEric Dumazet const struct sk_buff *skb, 1989d4589926SEric Dumazet unsigned int mss_now, 1990d4589926SEric Dumazet unsigned int max_segs, 1991d4589926SEric Dumazet int nonagle) 1992c1b4a7e6SDavid S. Miller { 1993cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1994d4589926SEric Dumazet u32 partial, needed, window, max_len; 1995c1b4a7e6SDavid S. Miller 199690840defSIlpo Järvinen window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 19971485348dSBen Hutchings max_len = mss_now * max_segs; 19980e3a4803SIlpo Järvinen 19991485348dSBen Hutchings if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) 20001485348dSBen Hutchings return max_len; 20010e3a4803SIlpo Järvinen 20025ea3a748SIlpo Järvinen needed = min(skb->len, window); 20035ea3a748SIlpo Järvinen 20041485348dSBen Hutchings if (max_len <= needed) 20051485348dSBen Hutchings return max_len; 20060e3a4803SIlpo Järvinen 2007d4589926SEric Dumazet partial = needed % mss_now; 2008d4589926SEric Dumazet /* If last segment is not a full MSS, check if Nagle rules allow us 2009d4589926SEric Dumazet * to include this last segment in this skb. 2010d4589926SEric Dumazet * Otherwise, we'll split the skb at last MSS boundary 2011d4589926SEric Dumazet */ 2012cc93fc51SPeter Pan(潘卫平) if (tcp_nagle_check(partial != 0, tp, nonagle)) 2013d4589926SEric Dumazet return needed - partial; 2014d4589926SEric Dumazet 2015d4589926SEric Dumazet return needed; 2016c1b4a7e6SDavid S. Miller } 2017c1b4a7e6SDavid S. Miller 2018c1b4a7e6SDavid S. Miller /* Can at least one segment of SKB be sent right now, according to the 2019c1b4a7e6SDavid S. Miller * congestion window rules? If so, return how many segments are allowed. 2020c1b4a7e6SDavid S. Miller */ 2021cf533ea5SEric Dumazet static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, 2022cf533ea5SEric Dumazet const struct sk_buff *skb) 2023c1b4a7e6SDavid S. Miller { 2024d649a7a8SEric Dumazet u32 in_flight, cwnd, halfcwnd; 2025c1b4a7e6SDavid S. Miller 2026c1b4a7e6SDavid S. Miller /* Don't be strict about the congestion window for the final FIN. */ 20274de075e0SEric Dumazet if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && 20284de075e0SEric Dumazet tcp_skb_pcount(skb) == 1) 2029c1b4a7e6SDavid S. Miller return 1; 2030c1b4a7e6SDavid S. Miller 2031c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 203240570375SEric Dumazet cwnd = tcp_snd_cwnd(tp); 2033d649a7a8SEric Dumazet if (in_flight >= cwnd) 2034c1b4a7e6SDavid S. Miller return 0; 2035d649a7a8SEric Dumazet 2036d649a7a8SEric Dumazet /* For better scheduling, ensure we have at least 2037d649a7a8SEric Dumazet * 2 GSO packets in flight. 2038d649a7a8SEric Dumazet */ 2039d649a7a8SEric Dumazet halfcwnd = max(cwnd >> 1, 1U); 2040d649a7a8SEric Dumazet return min(halfcwnd, cwnd - in_flight); 2041c1b4a7e6SDavid S. Miller } 2042c1b4a7e6SDavid S. Miller 2043b595076aSUwe Kleine-König /* Initialize TSO state of a skb. 204467edfef7SAndi Kleen * This must be invoked the first time we consider transmitting 2045c1b4a7e6SDavid S. Miller * SKB onto the wire. 2046c1b4a7e6SDavid S. Miller */ 20475bbb432cSEric Dumazet static int tcp_init_tso_segs(struct sk_buff *skb, unsigned int mss_now) 2048c1b4a7e6SDavid S. Miller { 2049c1b4a7e6SDavid S. Miller int tso_segs = tcp_skb_pcount(skb); 2050c1b4a7e6SDavid S. Miller 2051f8269a49SIlpo Järvinen if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { 20525bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 2053c1b4a7e6SDavid S. Miller tso_segs = tcp_skb_pcount(skb); 2054c1b4a7e6SDavid S. Miller } 2055c1b4a7e6SDavid S. Miller return tso_segs; 2056c1b4a7e6SDavid S. Miller } 2057c1b4a7e6SDavid S. Miller 2058c1b4a7e6SDavid S. Miller 2059a2a385d6SEric Dumazet /* Return true if the Nagle test allows this packet to be 2060c1b4a7e6SDavid S. Miller * sent now. 2061c1b4a7e6SDavid S. Miller */ 2062a2a385d6SEric Dumazet static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, 2063c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 2064c1b4a7e6SDavid S. Miller { 2065c1b4a7e6SDavid S. Miller /* Nagle rule does not apply to frames, which sit in the middle of the 2066c1b4a7e6SDavid S. Miller * write_queue (they have no chances to get new data). 2067c1b4a7e6SDavid S. Miller * 2068c1b4a7e6SDavid S. Miller * This is implemented in the callers, where they modify the 'nonagle' 2069c1b4a7e6SDavid S. Miller * argument based upon the location of SKB in the send queue. 2070c1b4a7e6SDavid S. Miller */ 2071c1b4a7e6SDavid S. Miller if (nonagle & TCP_NAGLE_PUSH) 2072a2a385d6SEric Dumazet return true; 2073c1b4a7e6SDavid S. Miller 20749b44190dSYuchung Cheng /* Don't use the nagle rule for urgent data (or for the final FIN). */ 20759b44190dSYuchung Cheng if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) 2076a2a385d6SEric Dumazet return true; 2077c1b4a7e6SDavid S. Miller 2078cc93fc51SPeter Pan(潘卫平) if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) 2079a2a385d6SEric Dumazet return true; 2080c1b4a7e6SDavid S. Miller 2081a2a385d6SEric Dumazet return false; 2082c1b4a7e6SDavid S. Miller } 2083c1b4a7e6SDavid S. Miller 2084c1b4a7e6SDavid S. Miller /* Does at least the first segment of SKB fit into the send window? */ 2085a2a385d6SEric Dumazet static bool tcp_snd_wnd_test(const struct tcp_sock *tp, 2086a2a385d6SEric Dumazet const struct sk_buff *skb, 2087056834d9SIlpo Järvinen unsigned int cur_mss) 2088c1b4a7e6SDavid S. Miller { 2089c1b4a7e6SDavid S. Miller u32 end_seq = TCP_SKB_CB(skb)->end_seq; 2090c1b4a7e6SDavid S. Miller 2091c1b4a7e6SDavid S. Miller if (skb->len > cur_mss) 2092c1b4a7e6SDavid S. Miller end_seq = TCP_SKB_CB(skb)->seq + cur_mss; 2093c1b4a7e6SDavid S. Miller 209490840defSIlpo Järvinen return !after(end_seq, tcp_wnd_end(tp)); 2095c1b4a7e6SDavid S. Miller } 2096c1b4a7e6SDavid S. Miller 2097c1b4a7e6SDavid S. Miller /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet 2098c1b4a7e6SDavid S. Miller * which is put after SKB on the list. It is very much like 2099c1b4a7e6SDavid S. Miller * tcp_fragment() except that it may make several kinds of assumptions 2100c1b4a7e6SDavid S. Miller * in order to speed up the splitting operation. In particular, we 2101c1b4a7e6SDavid S. Miller * know that all the data is in scatter-gather pages, and that the 2102c1b4a7e6SDavid S. Miller * packet has never been sent out before (and thus is not cloned). 2103c1b4a7e6SDavid S. Miller */ 210456483341SEric Dumazet static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, 2105c4ead4c5SEric Dumazet unsigned int mss_now, gfp_t gfp) 2106c1b4a7e6SDavid S. Miller { 2107c1b4a7e6SDavid S. Miller int nlen = skb->len - len; 210856483341SEric Dumazet struct sk_buff *buff; 21099ce01461SIlpo Järvinen u8 flags; 2110c1b4a7e6SDavid S. Miller 2111c1b4a7e6SDavid S. Miller /* All of a TSO frame must be composed of paged data. */ 2112b4a24397SEric Dumazet DEBUG_NET_WARN_ON_ONCE(skb->len != skb->data_len); 2113c1b4a7e6SDavid S. Miller 21145882efffSEric Dumazet buff = tcp_stream_alloc_skb(sk, gfp, true); 211551456b29SIan Morris if (unlikely(!buff)) 2116c1b4a7e6SDavid S. Miller return -ENOMEM; 211741477662SJakub Kicinski skb_copy_decrypted(buff, skb); 21185a369ca6SPaolo Abeni mptcp_skb_ext_copy(buff, skb); 2119c1b4a7e6SDavid S. Miller 2120ab4e846aSEric Dumazet sk_wmem_queued_add(sk, buff->truesize); 21213ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 2122b60b49eaSHerbert Xu buff->truesize += nlen; 2123c1b4a7e6SDavid S. Miller skb->truesize -= nlen; 2124c1b4a7e6SDavid S. Miller 2125c1b4a7e6SDavid S. Miller /* Correct the sequence numbers. */ 2126c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 2127c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 2128c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 2129c1b4a7e6SDavid S. Miller 2130c1b4a7e6SDavid S. Miller /* PSH and FIN should only be set in the second packet. */ 21314de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 21324de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 21334de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 2134c1b4a7e6SDavid S. Miller 2135a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 2136a166140eSMartin KaFai Lau 2137c1b4a7e6SDavid S. Miller skb_split(skb, buff, len); 2138490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 2139c1b4a7e6SDavid S. Miller 2140c1b4a7e6SDavid S. Miller /* Fix up tso_factor for both original and new SKB. */ 21415bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 21425bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 2143c1b4a7e6SDavid S. Miller 2144c1b4a7e6SDavid S. Miller /* Link BUFF into the send queue. */ 2145f4a775d1SEric Dumazet __skb_header_release(buff); 214656483341SEric Dumazet tcp_insert_write_queue_after(skb, buff, sk, TCP_FRAG_IN_WRITE_QUEUE); 2147c1b4a7e6SDavid S. Miller 2148c1b4a7e6SDavid S. Miller return 0; 2149c1b4a7e6SDavid S. Miller } 2150c1b4a7e6SDavid S. Miller 2151c1b4a7e6SDavid S. Miller /* Try to defer sending, if possible, in order to minimize the amount 2152c1b4a7e6SDavid S. Miller * of TSO splitting we do. View it as a kind of TSO Nagle test. 2153c1b4a7e6SDavid S. Miller * 2154c1b4a7e6SDavid S. Miller * This algorithm is from John Heffner. 2155c1b4a7e6SDavid S. Miller */ 2156ca8a2263SNeal Cardwell static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, 2157f9bfe4e6SEric Dumazet bool *is_cwnd_limited, 2158f9bfe4e6SEric Dumazet bool *is_rwnd_limited, 2159f9bfe4e6SEric Dumazet u32 max_segs) 2160c1b4a7e6SDavid S. Miller { 21616687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 2162f1c6ea38SEric Dumazet u32 send_win, cong_win, limit, in_flight; 216350c8339eSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 216450c8339eSEric Dumazet struct sk_buff *head; 2165ad9f4f50SEric Dumazet int win_divisor; 2166f1c6ea38SEric Dumazet s64 delta; 2167c1b4a7e6SDavid S. Miller 216899d7662aSEric Dumazet if (icsk->icsk_ca_state >= TCP_CA_Recovery) 2169ae8064acSJohn Heffner goto send_now; 2170ae8064acSJohn Heffner 21715f852eb5SEric Dumazet /* Avoid bursty behavior by allowing defer 2172a682850aSEric Dumazet * only if the last write was recent (1 ms). 2173a682850aSEric Dumazet * Note that tp->tcp_wstamp_ns can be in the future if we have 2174a682850aSEric Dumazet * packets waiting in a qdisc or device for EDT delivery. 21755f852eb5SEric Dumazet */ 2176a682850aSEric Dumazet delta = tp->tcp_clock_cache - tp->tcp_wstamp_ns - NSEC_PER_MSEC; 2177a682850aSEric Dumazet if (delta > 0) 2178ae8064acSJohn Heffner goto send_now; 2179908a75c1SDavid S. Miller 2180c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 2181c1b4a7e6SDavid S. Miller 2182c8c9aeb5SStefano Brivio BUG_ON(tcp_skb_pcount(skb) <= 1); 218340570375SEric Dumazet BUG_ON(tcp_snd_cwnd(tp) <= in_flight); 2184c1b4a7e6SDavid S. Miller 218590840defSIlpo Järvinen send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 2186c1b4a7e6SDavid S. Miller 2187c1b4a7e6SDavid S. Miller /* From in_flight test above, we know that cwnd > in_flight. */ 218840570375SEric Dumazet cong_win = (tcp_snd_cwnd(tp) - in_flight) * tp->mss_cache; 2189c1b4a7e6SDavid S. Miller 2190c1b4a7e6SDavid S. Miller limit = min(send_win, cong_win); 2191c1b4a7e6SDavid S. Miller 2192ba244fe9SDavid S. Miller /* If a full-sized TSO skb can be sent, do it. */ 2193605ad7f1SEric Dumazet if (limit >= max_segs * tp->mss_cache) 2194ae8064acSJohn Heffner goto send_now; 2195ba244fe9SDavid S. Miller 219662ad2761SIlpo Järvinen /* Middle in queue won't get any more data, full sendable already? */ 219762ad2761SIlpo Järvinen if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) 219862ad2761SIlpo Järvinen goto send_now; 219962ad2761SIlpo Järvinen 22005bbcc0f5SLinus Torvalds win_divisor = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_win_divisor); 2201ad9f4f50SEric Dumazet if (win_divisor) { 220240570375SEric Dumazet u32 chunk = min(tp->snd_wnd, tcp_snd_cwnd(tp) * tp->mss_cache); 2203c1b4a7e6SDavid S. Miller 2204c1b4a7e6SDavid S. Miller /* If at least some fraction of a window is available, 2205c1b4a7e6SDavid S. Miller * just use it. 2206c1b4a7e6SDavid S. Miller */ 2207ad9f4f50SEric Dumazet chunk /= win_divisor; 2208c1b4a7e6SDavid S. Miller if (limit >= chunk) 2209ae8064acSJohn Heffner goto send_now; 2210c1b4a7e6SDavid S. Miller } else { 2211c1b4a7e6SDavid S. Miller /* Different approach, try not to defer past a single 2212c1b4a7e6SDavid S. Miller * ACK. Receiver should ACK every other full sized 2213c1b4a7e6SDavid S. Miller * frame, so if we have space for more than 3 frames 2214c1b4a7e6SDavid S. Miller * then send now. 2215c1b4a7e6SDavid S. Miller */ 22166b5a5c0dSNeal Cardwell if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) 2217ae8064acSJohn Heffner goto send_now; 2218c1b4a7e6SDavid S. Miller } 2219c1b4a7e6SDavid S. Miller 222075c119afSEric Dumazet /* TODO : use tsorted_sent_queue ? */ 222175c119afSEric Dumazet head = tcp_rtx_queue_head(sk); 222275c119afSEric Dumazet if (!head) 222375c119afSEric Dumazet goto send_now; 2224f1c6ea38SEric Dumazet delta = tp->tcp_clock_cache - head->tstamp; 222550c8339eSEric Dumazet /* If next ACK is likely to come too late (half srtt), do not defer */ 2226f1c6ea38SEric Dumazet if ((s64)(delta - (u64)NSEC_PER_USEC * (tp->srtt_us >> 4)) < 0) 222750c8339eSEric Dumazet goto send_now; 222850c8339eSEric Dumazet 2229f9bfe4e6SEric Dumazet /* Ok, it looks like it is advisable to defer. 2230f9bfe4e6SEric Dumazet * Three cases are tracked : 2231f9bfe4e6SEric Dumazet * 1) We are cwnd-limited 2232f9bfe4e6SEric Dumazet * 2) We are rwnd-limited 2233f9bfe4e6SEric Dumazet * 3) We are application limited. 2234f9bfe4e6SEric Dumazet */ 2235f9bfe4e6SEric Dumazet if (cong_win < send_win) { 2236f9bfe4e6SEric Dumazet if (cong_win <= skb->len) { 2237ca8a2263SNeal Cardwell *is_cwnd_limited = true; 2238f9bfe4e6SEric Dumazet return true; 2239f9bfe4e6SEric Dumazet } 2240f9bfe4e6SEric Dumazet } else { 2241f9bfe4e6SEric Dumazet if (send_win <= skb->len) { 2242f9bfe4e6SEric Dumazet *is_rwnd_limited = true; 2243f9bfe4e6SEric Dumazet return true; 2244f9bfe4e6SEric Dumazet } 2245f9bfe4e6SEric Dumazet } 2246f9bfe4e6SEric Dumazet 2247f9bfe4e6SEric Dumazet /* If this packet won't get more data, do not wait. */ 2248d8ed257fSEric Dumazet if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) || 2249d8ed257fSEric Dumazet TCP_SKB_CB(skb)->eor) 2250f9bfe4e6SEric Dumazet goto send_now; 2251ca8a2263SNeal Cardwell 2252a2a385d6SEric Dumazet return true; 2253ae8064acSJohn Heffner 2254ae8064acSJohn Heffner send_now: 2255a2a385d6SEric Dumazet return false; 2256c1b4a7e6SDavid S. Miller } 2257c1b4a7e6SDavid S. Miller 225805cbc0dbSFan Du static inline void tcp_mtu_check_reprobe(struct sock *sk) 225905cbc0dbSFan Du { 226005cbc0dbSFan Du struct inet_connection_sock *icsk = inet_csk(sk); 226105cbc0dbSFan Du struct tcp_sock *tp = tcp_sk(sk); 226205cbc0dbSFan Du struct net *net = sock_net(sk); 226305cbc0dbSFan Du u32 interval; 226405cbc0dbSFan Du s32 delta; 226505cbc0dbSFan Du 22662a85388fSKuniyuki Iwashima interval = READ_ONCE(net->ipv4.sysctl_tcp_probe_interval); 2267c74df29aSEric Dumazet delta = tcp_jiffies32 - icsk->icsk_mtup.probe_timestamp; 226805cbc0dbSFan Du if (unlikely(delta >= interval * HZ)) { 226905cbc0dbSFan Du int mss = tcp_current_mss(sk); 227005cbc0dbSFan Du 227105cbc0dbSFan Du /* Update current search range */ 227205cbc0dbSFan Du icsk->icsk_mtup.probe_size = 0; 227305cbc0dbSFan Du icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + 227405cbc0dbSFan Du sizeof(struct tcphdr) + 227505cbc0dbSFan Du icsk->icsk_af_ops->net_header_len; 227605cbc0dbSFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); 227705cbc0dbSFan Du 227805cbc0dbSFan Du /* Update probe time stamp */ 2279c74df29aSEric Dumazet icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; 228005cbc0dbSFan Du } 228105cbc0dbSFan Du } 228205cbc0dbSFan Du 2283808cf9e3SIlya Lesokhin static bool tcp_can_coalesce_send_queue_head(struct sock *sk, int len) 2284808cf9e3SIlya Lesokhin { 2285808cf9e3SIlya Lesokhin struct sk_buff *skb, *next; 2286808cf9e3SIlya Lesokhin 2287808cf9e3SIlya Lesokhin skb = tcp_send_head(sk); 2288808cf9e3SIlya Lesokhin tcp_for_write_queue_from_safe(skb, next, sk) { 2289808cf9e3SIlya Lesokhin if (len <= skb->len) 2290808cf9e3SIlya Lesokhin break; 2291808cf9e3SIlya Lesokhin 22929b65b17dSTalal Ahmad if (unlikely(TCP_SKB_CB(skb)->eor) || 22939b65b17dSTalal Ahmad tcp_has_tx_tstamp(skb) || 22949b65b17dSTalal Ahmad !skb_pure_zcopy_same(skb, next)) 2295808cf9e3SIlya Lesokhin return false; 2296808cf9e3SIlya Lesokhin 2297808cf9e3SIlya Lesokhin len -= skb->len; 2298808cf9e3SIlya Lesokhin } 2299808cf9e3SIlya Lesokhin 2300808cf9e3SIlya Lesokhin return true; 2301808cf9e3SIlya Lesokhin } 2302808cf9e3SIlya Lesokhin 230373601329SEric Dumazet static int tcp_clone_payload(struct sock *sk, struct sk_buff *to, 230473601329SEric Dumazet int probe_size) 230573601329SEric Dumazet { 230673601329SEric Dumazet skb_frag_t *lastfrag = NULL, *fragto = skb_shinfo(to)->frags; 230773601329SEric Dumazet int i, todo, len = 0, nr_frags = 0; 230873601329SEric Dumazet const struct sk_buff *skb; 230973601329SEric Dumazet 231073601329SEric Dumazet if (!sk_wmem_schedule(sk, to->truesize + probe_size)) 231173601329SEric Dumazet return -ENOMEM; 231273601329SEric Dumazet 231373601329SEric Dumazet skb_queue_walk(&sk->sk_write_queue, skb) { 231473601329SEric Dumazet const skb_frag_t *fragfrom = skb_shinfo(skb)->frags; 231573601329SEric Dumazet 231673601329SEric Dumazet if (skb_headlen(skb)) 231773601329SEric Dumazet return -EINVAL; 231873601329SEric Dumazet 231973601329SEric Dumazet for (i = 0; i < skb_shinfo(skb)->nr_frags; i++, fragfrom++) { 232073601329SEric Dumazet if (len >= probe_size) 232173601329SEric Dumazet goto commit; 232273601329SEric Dumazet todo = min_t(int, skb_frag_size(fragfrom), 232373601329SEric Dumazet probe_size - len); 232473601329SEric Dumazet len += todo; 232573601329SEric Dumazet if (lastfrag && 232673601329SEric Dumazet skb_frag_page(fragfrom) == skb_frag_page(lastfrag) && 232773601329SEric Dumazet skb_frag_off(fragfrom) == skb_frag_off(lastfrag) + 232873601329SEric Dumazet skb_frag_size(lastfrag)) { 232973601329SEric Dumazet skb_frag_size_add(lastfrag, todo); 233073601329SEric Dumazet continue; 233173601329SEric Dumazet } 233273601329SEric Dumazet if (unlikely(nr_frags == MAX_SKB_FRAGS)) 233373601329SEric Dumazet return -E2BIG; 233473601329SEric Dumazet skb_frag_page_copy(fragto, fragfrom); 233573601329SEric Dumazet skb_frag_off_copy(fragto, fragfrom); 233673601329SEric Dumazet skb_frag_size_set(fragto, todo); 233773601329SEric Dumazet nr_frags++; 233873601329SEric Dumazet lastfrag = fragto++; 233973601329SEric Dumazet } 234073601329SEric Dumazet } 234173601329SEric Dumazet commit: 234273601329SEric Dumazet WARN_ON_ONCE(len != probe_size); 234373601329SEric Dumazet for (i = 0; i < nr_frags; i++) 234473601329SEric Dumazet skb_frag_ref(to, i); 234573601329SEric Dumazet 234673601329SEric Dumazet skb_shinfo(to)->nr_frags = nr_frags; 234773601329SEric Dumazet to->truesize += probe_size; 234873601329SEric Dumazet to->len += probe_size; 234973601329SEric Dumazet to->data_len += probe_size; 235073601329SEric Dumazet __skb_header_release(to); 235173601329SEric Dumazet return 0; 235273601329SEric Dumazet } 235373601329SEric Dumazet 23545d424d5aSJohn Heffner /* Create a new MTU probe if we are ready. 235567edfef7SAndi Kleen * MTU probe is regularly attempting to increase the path MTU by 235667edfef7SAndi Kleen * deliberately sending larger packets. This discovers routing 235767edfef7SAndi Kleen * changes resulting in larger path MTUs. 235867edfef7SAndi Kleen * 23595d424d5aSJohn Heffner * Returns 0 if we should wait to probe (no cwnd available), 23605d424d5aSJohn Heffner * 1 if a probe was sent, 2361056834d9SIlpo Järvinen * -1 otherwise 2362056834d9SIlpo Järvinen */ 23635d424d5aSJohn Heffner static int tcp_mtu_probe(struct sock *sk) 23645d424d5aSJohn Heffner { 23655d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 236612a59abcSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 23675d424d5aSJohn Heffner struct sk_buff *skb, *nskb, *next; 23686b58e0a5SFan Du struct net *net = sock_net(sk); 23695d424d5aSJohn Heffner int probe_size; 237091cc17c0SIlpo Järvinen int size_needed; 237112a59abcSEric Dumazet int copy, len; 23725d424d5aSJohn Heffner int mss_now; 23736b58e0a5SFan Du int interval; 23745d424d5aSJohn Heffner 23755d424d5aSJohn Heffner /* Not currently probing/verifying, 23765d424d5aSJohn Heffner * not in recovery, 23775d424d5aSJohn Heffner * have enough cwnd, and 237812a59abcSEric Dumazet * not SACKing (the variable headers throw things off) 237912a59abcSEric Dumazet */ 238012a59abcSEric Dumazet if (likely(!icsk->icsk_mtup.enabled || 23815d424d5aSJohn Heffner icsk->icsk_mtup.probe_size || 23825d424d5aSJohn Heffner inet_csk(sk)->icsk_ca_state != TCP_CA_Open || 238340570375SEric Dumazet tcp_snd_cwnd(tp) < 11 || 238412a59abcSEric Dumazet tp->rx_opt.num_sacks || tp->rx_opt.dsack)) 23855d424d5aSJohn Heffner return -1; 23865d424d5aSJohn Heffner 23876b58e0a5SFan Du /* Use binary search for probe_size between tcp_mss_base, 23886b58e0a5SFan Du * and current mss_clamp. if (search_high - search_low) 23896b58e0a5SFan Du * smaller than a threshold, backoff from probing. 23906b58e0a5SFan Du */ 23910c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 23926b58e0a5SFan Du probe_size = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high + 23936b58e0a5SFan Du icsk->icsk_mtup.search_low) >> 1); 239491cc17c0SIlpo Järvinen size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; 23956b58e0a5SFan Du interval = icsk->icsk_mtup.search_high - icsk->icsk_mtup.search_low; 239605cbc0dbSFan Du /* When misfortune happens, we are reprobing actively, 239705cbc0dbSFan Du * and then reprobe timer has expired. We stick with current 239805cbc0dbSFan Du * probing process by not resetting search range to its orignal. 239905cbc0dbSFan Du */ 24006b58e0a5SFan Du if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high) || 240192c0aa41SKuniyuki Iwashima interval < READ_ONCE(net->ipv4.sysctl_tcp_probe_threshold)) { 240205cbc0dbSFan Du /* Check whether enough time has elaplased for 240305cbc0dbSFan Du * another round of probing. 240405cbc0dbSFan Du */ 240505cbc0dbSFan Du tcp_mtu_check_reprobe(sk); 24065d424d5aSJohn Heffner return -1; 24075d424d5aSJohn Heffner } 24085d424d5aSJohn Heffner 24095d424d5aSJohn Heffner /* Have enough data in the send queue to probe? */ 24107f9c33e5SIlpo Järvinen if (tp->write_seq - tp->snd_nxt < size_needed) 24115d424d5aSJohn Heffner return -1; 24125d424d5aSJohn Heffner 241391cc17c0SIlpo Järvinen if (tp->snd_wnd < size_needed) 24145d424d5aSJohn Heffner return -1; 241590840defSIlpo Järvinen if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) 24165d424d5aSJohn Heffner return 0; 24175d424d5aSJohn Heffner 2418d67c58e9SIlpo Järvinen /* Do we need to wait to drain cwnd? With none in flight, don't stall */ 241940570375SEric Dumazet if (tcp_packets_in_flight(tp) + 2 > tcp_snd_cwnd(tp)) { 2420d67c58e9SIlpo Järvinen if (!tcp_packets_in_flight(tp)) 24215d424d5aSJohn Heffner return -1; 24225d424d5aSJohn Heffner else 24235d424d5aSJohn Heffner return 0; 24245d424d5aSJohn Heffner } 24255d424d5aSJohn Heffner 2426808cf9e3SIlya Lesokhin if (!tcp_can_coalesce_send_queue_head(sk, probe_size)) 2427808cf9e3SIlya Lesokhin return -1; 2428808cf9e3SIlya Lesokhin 24295d424d5aSJohn Heffner /* We're allowed to probe. Build it now. */ 24305882efffSEric Dumazet nskb = tcp_stream_alloc_skb(sk, GFP_ATOMIC, false); 243151456b29SIan Morris if (!nskb) 24325d424d5aSJohn Heffner return -1; 243373601329SEric Dumazet 243473601329SEric Dumazet /* build the payload, and be prepared to abort if this fails. */ 243573601329SEric Dumazet if (tcp_clone_payload(sk, nskb, probe_size)) { 243671c299c7SJakub Kicinski tcp_skb_tsorted_anchor_cleanup(nskb); 243773601329SEric Dumazet consume_skb(nskb); 243873601329SEric Dumazet return -1; 243973601329SEric Dumazet } 2440ab4e846aSEric Dumazet sk_wmem_queued_add(sk, nskb->truesize); 24413ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 24425d424d5aSJohn Heffner 2443fe067e8aSDavid S. Miller skb = tcp_send_head(sk); 244441477662SJakub Kicinski skb_copy_decrypted(nskb, skb); 24455a369ca6SPaolo Abeni mptcp_skb_ext_copy(nskb, skb); 24465d424d5aSJohn Heffner 24475d424d5aSJohn Heffner TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; 24485d424d5aSJohn Heffner TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; 24494de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; 24505d424d5aSJohn Heffner 245150c4817eSIlpo Järvinen tcp_insert_write_queue_before(nskb, skb, sk); 24522b7cda9cSEric Dumazet tcp_highest_sack_replace(sk, skb, nskb); 245350c4817eSIlpo Järvinen 24545d424d5aSJohn Heffner len = 0; 2455234b6860SIlpo Järvinen tcp_for_write_queue_from_safe(skb, next, sk) { 24565d424d5aSJohn Heffner copy = min_t(int, skb->len, probe_size - len); 24575d424d5aSJohn Heffner 24585d424d5aSJohn Heffner if (skb->len <= copy) { 24595d424d5aSJohn Heffner /* We've eaten all the data from this skb. 24605d424d5aSJohn Heffner * Throw it away. */ 24614de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; 2462808cf9e3SIlya Lesokhin /* If this is the last SKB we copy and eor is set 2463808cf9e3SIlya Lesokhin * we need to propagate it to the new skb. 2464808cf9e3SIlya Lesokhin */ 2465808cf9e3SIlya Lesokhin TCP_SKB_CB(nskb)->eor = TCP_SKB_CB(skb)->eor; 2466888a5c53SWillem de Bruijn tcp_skb_collapse_tstamp(nskb, skb); 2467fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 246803271f3aSTalal Ahmad tcp_wmem_free_skb(sk, skb); 24695d424d5aSJohn Heffner } else { 24704de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & 2471a3433f35SChangli Gao ~(TCPHDR_FIN|TCPHDR_PSH); 24725d424d5aSJohn Heffner __pskb_trim_head(skb, copy); 24735bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 24745d424d5aSJohn Heffner TCP_SKB_CB(skb)->seq += copy; 24755d424d5aSJohn Heffner } 24765d424d5aSJohn Heffner 24775d424d5aSJohn Heffner len += copy; 2478234b6860SIlpo Järvinen 2479234b6860SIlpo Järvinen if (len >= probe_size) 2480234b6860SIlpo Järvinen break; 24815d424d5aSJohn Heffner } 24825bbb432cSEric Dumazet tcp_init_tso_segs(nskb, nskb->len); 24835d424d5aSJohn Heffner 24845d424d5aSJohn Heffner /* We're ready to send. If this fails, the probe will 24857faee5c0SEric Dumazet * be resegmented into mss-sized pieces by tcp_write_xmit(). 24867faee5c0SEric Dumazet */ 24875d424d5aSJohn Heffner if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { 24885d424d5aSJohn Heffner /* Decrement cwnd here because we are sending 24895d424d5aSJohn Heffner * effectively two packets. */ 249040570375SEric Dumazet tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) - 1); 249166f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, nskb); 24925d424d5aSJohn Heffner 24935d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); 24940e7b1368SJohn Heffner tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; 24950e7b1368SJohn Heffner tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; 24965d424d5aSJohn Heffner 24975d424d5aSJohn Heffner return 1; 24985d424d5aSJohn Heffner } 24995d424d5aSJohn Heffner 25005d424d5aSJohn Heffner return -1; 25015d424d5aSJohn Heffner } 25025d424d5aSJohn Heffner 2503864e5c09SEric Dumazet static bool tcp_pacing_check(struct sock *sk) 2504218af599SEric Dumazet { 2505864e5c09SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 2506864e5c09SEric Dumazet 2507864e5c09SEric Dumazet if (!tcp_needs_internal_pacing(sk)) 2508864e5c09SEric Dumazet return false; 2509864e5c09SEric Dumazet 2510864e5c09SEric Dumazet if (tp->tcp_wstamp_ns <= tp->tcp_clock_cache) 2511864e5c09SEric Dumazet return false; 2512864e5c09SEric Dumazet 2513864e5c09SEric Dumazet if (!hrtimer_is_queued(&tp->pacing_timer)) { 2514864e5c09SEric Dumazet hrtimer_start(&tp->pacing_timer, 2515864e5c09SEric Dumazet ns_to_ktime(tp->tcp_wstamp_ns), 2516864e5c09SEric Dumazet HRTIMER_MODE_ABS_PINNED_SOFT); 2517864e5c09SEric Dumazet sock_hold(sk); 2518864e5c09SEric Dumazet } 2519864e5c09SEric Dumazet return true; 2520218af599SEric Dumazet } 2521218af599SEric Dumazet 2522f921a4a5SEric Dumazet static bool tcp_rtx_queue_empty_or_single_skb(const struct sock *sk) 2523f921a4a5SEric Dumazet { 2524f921a4a5SEric Dumazet const struct rb_node *node = sk->tcp_rtx_queue.rb_node; 2525f921a4a5SEric Dumazet 2526f921a4a5SEric Dumazet /* No skb in the rtx queue. */ 2527f921a4a5SEric Dumazet if (!node) 2528f921a4a5SEric Dumazet return true; 2529f921a4a5SEric Dumazet 2530f921a4a5SEric Dumazet /* Only one skb in rtx queue. */ 2531f921a4a5SEric Dumazet return !node->rb_left && !node->rb_right; 2532f921a4a5SEric Dumazet } 2533f921a4a5SEric Dumazet 2534f9616c35SEric Dumazet /* TCP Small Queues : 2535f9616c35SEric Dumazet * Control number of packets in qdisc/devices to two packets / or ~1 ms. 2536f9616c35SEric Dumazet * (These limits are doubled for retransmits) 2537f9616c35SEric Dumazet * This allows for : 2538f9616c35SEric Dumazet * - better RTT estimation and ACK scheduling 2539f9616c35SEric Dumazet * - faster recovery 2540f9616c35SEric Dumazet * - high rates 2541f9616c35SEric Dumazet * Alas, some drivers / subsystems require a fair amount 2542f9616c35SEric Dumazet * of queued bytes to ensure line rate. 2543f9616c35SEric Dumazet * One example is wifi aggregation (802.11 AMPDU) 2544f9616c35SEric Dumazet */ 2545f9616c35SEric Dumazet static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb, 2546f9616c35SEric Dumazet unsigned int factor) 2547f9616c35SEric Dumazet { 254876a9ebe8SEric Dumazet unsigned long limit; 2549f9616c35SEric Dumazet 255076a9ebe8SEric Dumazet limit = max_t(unsigned long, 255176a9ebe8SEric Dumazet 2 * skb->truesize, 255228b24f90SEric Dumazet READ_ONCE(sk->sk_pacing_rate) >> READ_ONCE(sk->sk_pacing_shift)); 2553c73e5807SEric Dumazet if (sk->sk_pacing_status == SK_PACING_NONE) 255476a9ebe8SEric Dumazet limit = min_t(unsigned long, limit, 25559fb90193SKuniyuki Iwashima READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_limit_output_bytes)); 2556f9616c35SEric Dumazet limit <<= factor; 2557f9616c35SEric Dumazet 2558a842fe14SEric Dumazet if (static_branch_unlikely(&tcp_tx_delay_enabled) && 2559a842fe14SEric Dumazet tcp_sk(sk)->tcp_tx_delay) { 256028b24f90SEric Dumazet u64 extra_bytes = (u64)READ_ONCE(sk->sk_pacing_rate) * 256128b24f90SEric Dumazet tcp_sk(sk)->tcp_tx_delay; 2562a842fe14SEric Dumazet 2563a842fe14SEric Dumazet /* TSQ is based on skb truesize sum (sk_wmem_alloc), so we 2564a842fe14SEric Dumazet * approximate our needs assuming an ~100% skb->truesize overhead. 2565a842fe14SEric Dumazet * USEC_PER_SEC is approximated by 2^20. 2566a842fe14SEric Dumazet * do_div(extra_bytes, USEC_PER_SEC/2) is replaced by a right shift. 2567a842fe14SEric Dumazet */ 2568a842fe14SEric Dumazet extra_bytes >>= (20 - 1); 2569a842fe14SEric Dumazet limit += extra_bytes; 2570a842fe14SEric Dumazet } 257114afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) > limit) { 2572f921a4a5SEric Dumazet /* Always send skb if rtx queue is empty or has one skb. 257375eefc6cSEric Dumazet * No need to wait for TX completion to call us back, 257475eefc6cSEric Dumazet * after softirq/tasklet schedule. 257575eefc6cSEric Dumazet * This helps when TX completions are delayed too much. 257675eefc6cSEric Dumazet */ 2577f921a4a5SEric Dumazet if (tcp_rtx_queue_empty_or_single_skb(sk)) 257875eefc6cSEric Dumazet return false; 257975eefc6cSEric Dumazet 25807aa5470cSEric Dumazet set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags); 2581f9616c35SEric Dumazet /* It is possible TX completion already happened 2582f9616c35SEric Dumazet * before we set TSQ_THROTTLED, so we must 2583f9616c35SEric Dumazet * test again the condition. 2584f9616c35SEric Dumazet */ 2585f9616c35SEric Dumazet smp_mb__after_atomic(); 2586ce8299b6SEric Dumazet if (refcount_read(&sk->sk_wmem_alloc) > limit) 2587f9616c35SEric Dumazet return true; 2588f9616c35SEric Dumazet } 2589f9616c35SEric Dumazet return false; 2590f9616c35SEric Dumazet } 2591f9616c35SEric Dumazet 259205b055e8SFrancis Yan static void tcp_chrono_set(struct tcp_sock *tp, const enum tcp_chrono new) 259305b055e8SFrancis Yan { 2594628174ccSEric Dumazet const u32 now = tcp_jiffies32; 2595efe967cdSArnd Bergmann enum tcp_chrono old = tp->chrono_type; 259605b055e8SFrancis Yan 2597efe967cdSArnd Bergmann if (old > TCP_CHRONO_UNSPEC) 2598efe967cdSArnd Bergmann tp->chrono_stat[old - 1] += now - tp->chrono_start; 259905b055e8SFrancis Yan tp->chrono_start = now; 260005b055e8SFrancis Yan tp->chrono_type = new; 260105b055e8SFrancis Yan } 260205b055e8SFrancis Yan 260305b055e8SFrancis Yan void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type) 260405b055e8SFrancis Yan { 260505b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 260605b055e8SFrancis Yan 260705b055e8SFrancis Yan /* If there are multiple conditions worthy of tracking in a 26080f87230dSFrancis Yan * chronograph then the highest priority enum takes precedence 26090f87230dSFrancis Yan * over the other conditions. So that if something "more interesting" 261005b055e8SFrancis Yan * starts happening, stop the previous chrono and start a new one. 261105b055e8SFrancis Yan */ 261205b055e8SFrancis Yan if (type > tp->chrono_type) 261305b055e8SFrancis Yan tcp_chrono_set(tp, type); 261405b055e8SFrancis Yan } 261505b055e8SFrancis Yan 261605b055e8SFrancis Yan void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type) 261705b055e8SFrancis Yan { 261805b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 261905b055e8SFrancis Yan 26200f87230dSFrancis Yan 26210f87230dSFrancis Yan /* There are multiple conditions worthy of tracking in a 26220f87230dSFrancis Yan * chronograph, so that the highest priority enum takes 26230f87230dSFrancis Yan * precedence over the other conditions (see tcp_chrono_start). 26240f87230dSFrancis Yan * If a condition stops, we only stop chrono tracking if 26250f87230dSFrancis Yan * it's the "most interesting" or current chrono we are 26260f87230dSFrancis Yan * tracking and starts busy chrono if we have pending data. 26270f87230dSFrancis Yan */ 262875c119afSEric Dumazet if (tcp_rtx_and_write_queues_empty(sk)) 262905b055e8SFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_UNSPEC); 26300f87230dSFrancis Yan else if (type == tp->chrono_type) 26310f87230dSFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_BUSY); 263205b055e8SFrancis Yan } 263305b055e8SFrancis Yan 26341da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 26351da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 26361da177e4SLinus Torvalds * window for us. 26371da177e4SLinus Torvalds * 2638f8269a49SIlpo Järvinen * LARGESEND note: !tcp_urg_mode is overkill, only frames between 2639f8269a49SIlpo Järvinen * snd_up-64k-mss .. snd_up cannot be large. However, taking into 2640f8269a49SIlpo Järvinen * account rare use of URG, this is not a big flaw. 2641f8269a49SIlpo Järvinen * 26426ba8a3b1SNandita Dukkipati * Send at most one packet when push_one > 0. Temporarily ignore 26436ba8a3b1SNandita Dukkipati * cwnd limit to force at most one packet out when push_one == 2. 26446ba8a3b1SNandita Dukkipati 2645a2a385d6SEric Dumazet * Returns true, if no segments are in flight and we have queued segments, 2646a2a385d6SEric Dumazet * but cannot send anything now because of SWS or another problem. 26471da177e4SLinus Torvalds */ 2648a2a385d6SEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 2649d5dd9175SIlpo Järvinen int push_one, gfp_t gfp) 26501da177e4SLinus Torvalds { 26511da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 265292df7b51SDavid S. Miller struct sk_buff *skb; 2653c1b4a7e6SDavid S. Miller unsigned int tso_segs, sent_pkts; 2654c1b4a7e6SDavid S. Miller int cwnd_quota; 26555d424d5aSJohn Heffner int result; 26565615f886SFrancis Yan bool is_cwnd_limited = false, is_rwnd_limited = false; 2657605ad7f1SEric Dumazet u32 max_segs; 26581da177e4SLinus Torvalds 2659c1b4a7e6SDavid S. Miller sent_pkts = 0; 26605d424d5aSJohn Heffner 2661ee1836aeSEric Dumazet tcp_mstamp_refresh(tp); 2662d5dd9175SIlpo Järvinen if (!push_one) { 26635d424d5aSJohn Heffner /* Do MTU probing. */ 2664d5dd9175SIlpo Järvinen result = tcp_mtu_probe(sk); 2665d5dd9175SIlpo Järvinen if (!result) { 2666a2a385d6SEric Dumazet return false; 26675d424d5aSJohn Heffner } else if (result > 0) { 26685d424d5aSJohn Heffner sent_pkts = 1; 26695d424d5aSJohn Heffner } 2670d5dd9175SIlpo Järvinen } 26715d424d5aSJohn Heffner 2672ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, mss_now); 2673fe067e8aSDavid S. Miller while ((skb = tcp_send_head(sk))) { 2674c8ac3774SHerbert Xu unsigned int limit; 2675c8ac3774SHerbert Xu 267679861919SEric Dumazet if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { 267779861919SEric Dumazet /* "skb_mstamp_ns" is used as a start point for the retransmit timer */ 2678a1ac9c8aSMartin KaFai Lau tp->tcp_wstamp_ns = tp->tcp_clock_cache; 2679a1ac9c8aSMartin KaFai Lau skb_set_delivery_time(skb, tp->tcp_wstamp_ns, true); 268079861919SEric Dumazet list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); 2681bf50b606SEric Dumazet tcp_init_tso_segs(skb, mss_now); 268279861919SEric Dumazet goto repair; /* Skip network transmission */ 268379861919SEric Dumazet } 268479861919SEric Dumazet 2685218af599SEric Dumazet if (tcp_pacing_check(sk)) 2686218af599SEric Dumazet break; 2687218af599SEric Dumazet 26885bbb432cSEric Dumazet tso_segs = tcp_init_tso_segs(skb, mss_now); 2689c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 2690c1b4a7e6SDavid S. Miller 2691b68e9f85SHerbert Xu cwnd_quota = tcp_cwnd_test(tp, skb); 26926ba8a3b1SNandita Dukkipati if (!cwnd_quota) { 26936ba8a3b1SNandita Dukkipati if (push_one == 2) 26946ba8a3b1SNandita Dukkipati /* Force out a loss probe pkt. */ 26956ba8a3b1SNandita Dukkipati cwnd_quota = 1; 26966ba8a3b1SNandita Dukkipati else 2697b68e9f85SHerbert Xu break; 26986ba8a3b1SNandita Dukkipati } 2699b68e9f85SHerbert Xu 27005615f886SFrancis Yan if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) { 27015615f886SFrancis Yan is_rwnd_limited = true; 2702b68e9f85SHerbert Xu break; 27035615f886SFrancis Yan } 2704b68e9f85SHerbert Xu 2705d6a4e26aSEric Dumazet if (tso_segs == 1) { 2706aa93466bSDavid S. Miller if (unlikely(!tcp_nagle_test(tp, skb, mss_now, 2707aa93466bSDavid S. Miller (tcp_skb_is_last(sk, skb) ? 2708aa93466bSDavid S. Miller nonagle : TCP_NAGLE_PUSH)))) 2709aa93466bSDavid S. Miller break; 2710c1b4a7e6SDavid S. Miller } else { 2711ca8a2263SNeal Cardwell if (!push_one && 2712605ad7f1SEric Dumazet tcp_tso_should_defer(sk, skb, &is_cwnd_limited, 2713f9bfe4e6SEric Dumazet &is_rwnd_limited, max_segs)) 2714aa93466bSDavid S. Miller break; 2715c1b4a7e6SDavid S. Miller } 2716aa93466bSDavid S. Miller 2717605ad7f1SEric Dumazet limit = mss_now; 2718d6a4e26aSEric Dumazet if (tso_segs > 1 && !tcp_urg_mode(tp)) 2719605ad7f1SEric Dumazet limit = tcp_mss_split_point(sk, skb, mss_now, 2720605ad7f1SEric Dumazet min_t(unsigned int, 2721605ad7f1SEric Dumazet cwnd_quota, 2722605ad7f1SEric Dumazet max_segs), 2723605ad7f1SEric Dumazet nonagle); 2724605ad7f1SEric Dumazet 2725605ad7f1SEric Dumazet if (skb->len > limit && 272656483341SEric Dumazet unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) 2727605ad7f1SEric Dumazet break; 2728605ad7f1SEric Dumazet 2729f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 0)) 273046d3ceabSEric Dumazet break; 2731c9eeec26SEric Dumazet 27321f85e626SEric Dumazet /* Argh, we hit an empty skb(), presumably a thread 27331f85e626SEric Dumazet * is sleeping in sendmsg()/sk_stream_wait_memory(). 27341f85e626SEric Dumazet * We do not want to send a pure-ack packet and have 27351f85e626SEric Dumazet * a strange looking rtx queue with empty packet(s). 27361f85e626SEric Dumazet */ 27371f85e626SEric Dumazet if (TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq) 27381f85e626SEric Dumazet break; 27391f85e626SEric Dumazet 2740d5dd9175SIlpo Järvinen if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) 27411da177e4SLinus Torvalds break; 27421da177e4SLinus Torvalds 2743ec342325SAndrew Vagin repair: 27441da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 27451da177e4SLinus Torvalds * This call will increment packets_out. 27461da177e4SLinus Torvalds */ 274766f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 27481da177e4SLinus Torvalds 27491da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 2750a262f0cdSNandita Dukkipati sent_pkts += tcp_skb_pcount(skb); 2751d5dd9175SIlpo Järvinen 2752d5dd9175SIlpo Järvinen if (push_one) 2753d5dd9175SIlpo Järvinen break; 27541da177e4SLinus Torvalds } 27551da177e4SLinus Torvalds 27565615f886SFrancis Yan if (is_rwnd_limited) 27575615f886SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_RWND_LIMITED); 27585615f886SFrancis Yan else 27595615f886SFrancis Yan tcp_chrono_stop(sk, TCP_CHRONO_RWND_LIMITED); 27605615f886SFrancis Yan 276140570375SEric Dumazet is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tcp_snd_cwnd(tp)); 2762299bcb55SNeal Cardwell if (likely(sent_pkts || is_cwnd_limited)) 2763299bcb55SNeal Cardwell tcp_cwnd_validate(sk, is_cwnd_limited); 2764299bcb55SNeal Cardwell 2765aa93466bSDavid S. Miller if (likely(sent_pkts)) { 2766684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2767684bad11SYuchung Cheng tp->prr_out += sent_pkts; 27686ba8a3b1SNandita Dukkipati 27696ba8a3b1SNandita Dukkipati /* Send one loss probe per tail loss episode. */ 27706ba8a3b1SNandita Dukkipati if (push_one != 2) 2771ed66dfafSNeal Cardwell tcp_schedule_loss_probe(sk, false); 2772a2a385d6SEric Dumazet return false; 27731da177e4SLinus Torvalds } 277475c119afSEric Dumazet return !tp->packets_out && !tcp_write_queue_empty(sk); 27756ba8a3b1SNandita Dukkipati } 27766ba8a3b1SNandita Dukkipati 2777ed66dfafSNeal Cardwell bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto) 27786ba8a3b1SNandita Dukkipati { 27796ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 27806ba8a3b1SNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 27811c2709cfSNeal Cardwell u32 timeout, timeout_us, rto_delta_us; 27822ae21cf5SEric Dumazet int early_retrans; 27836ba8a3b1SNandita Dukkipati 27846ba8a3b1SNandita Dukkipati /* Don't do any loss probe on a Fast Open connection before 3WHS 27856ba8a3b1SNandita Dukkipati * finishes. 27866ba8a3b1SNandita Dukkipati */ 2787d983ea6fSEric Dumazet if (rcu_access_pointer(tp->fastopen_rsk)) 27886ba8a3b1SNandita Dukkipati return false; 27896ba8a3b1SNandita Dukkipati 279052e65865SKuniyuki Iwashima early_retrans = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_early_retrans); 27916ba8a3b1SNandita Dukkipati /* Schedule a loss probe in 2*RTT for SACK capable connections 2792b4f70c3dSNeal Cardwell * not in loss recovery, that are either limited by cwnd or application. 27936ba8a3b1SNandita Dukkipati */ 27942ae21cf5SEric Dumazet if ((early_retrans != 3 && early_retrans != 4) || 2795bec41a11SYuchung Cheng !tp->packets_out || !tcp_is_sack(tp) || 2796b4f70c3dSNeal Cardwell (icsk->icsk_ca_state != TCP_CA_Open && 2797b4f70c3dSNeal Cardwell icsk->icsk_ca_state != TCP_CA_CWR)) 27986ba8a3b1SNandita Dukkipati return false; 27996ba8a3b1SNandita Dukkipati 2800bb4d991aSYuchung Cheng /* Probe timeout is 2*rtt. Add minimum RTO to account 2801f9b99582SYuchung Cheng * for delayed ack when there's one outstanding packet. If no RTT 2802f9b99582SYuchung Cheng * sample is available then probe after TCP_TIMEOUT_INIT. 28036ba8a3b1SNandita Dukkipati */ 2804bb4d991aSYuchung Cheng if (tp->srtt_us) { 28051c2709cfSNeal Cardwell timeout_us = tp->srtt_us >> 2; 28066ba8a3b1SNandita Dukkipati if (tp->packets_out == 1) 28071c2709cfSNeal Cardwell timeout_us += tcp_rto_min_us(sk); 2808bb4d991aSYuchung Cheng else 28091c2709cfSNeal Cardwell timeout_us += TCP_TIMEOUT_MIN_US; 28101c2709cfSNeal Cardwell timeout = usecs_to_jiffies(timeout_us); 2811bb4d991aSYuchung Cheng } else { 2812bb4d991aSYuchung Cheng timeout = TCP_TIMEOUT_INIT; 2813bb4d991aSYuchung Cheng } 28146ba8a3b1SNandita Dukkipati 2815a2815817SNeal Cardwell /* If the RTO formula yields an earlier time, then use that time. */ 2816ed66dfafSNeal Cardwell rto_delta_us = advancing_rto ? 2817ed66dfafSNeal Cardwell jiffies_to_usecs(inet_csk(sk)->icsk_rto) : 2818ed66dfafSNeal Cardwell tcp_rto_delta_us(sk); /* How far in future is RTO? */ 2819a2815817SNeal Cardwell if (rto_delta_us > 0) 2820a2815817SNeal Cardwell timeout = min_t(u32, timeout, usecs_to_jiffies(rto_delta_us)); 28216ba8a3b1SNandita Dukkipati 28228dc242adSEric Dumazet tcp_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, TCP_RTO_MAX); 28236ba8a3b1SNandita Dukkipati return true; 28246ba8a3b1SNandita Dukkipati } 28256ba8a3b1SNandita Dukkipati 28261f3279aeSEric Dumazet /* Thanks to skb fast clones, we can detect if a prior transmit of 28271f3279aeSEric Dumazet * a packet is still in a qdisc or driver queue. 28281f3279aeSEric Dumazet * In this case, there is very little point doing a retransmit ! 28291f3279aeSEric Dumazet */ 2830f4dae54eSEric Dumazet static bool skb_still_in_host_queue(struct sock *sk, 28311f3279aeSEric Dumazet const struct sk_buff *skb) 28321f3279aeSEric Dumazet { 283339bb5e62SEric Dumazet if (unlikely(skb_fclone_busy(sk, skb))) { 2834f4dae54eSEric Dumazet set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags); 2835f4dae54eSEric Dumazet smp_mb__after_atomic(); 2836f4dae54eSEric Dumazet if (skb_fclone_busy(sk, skb)) { 2837c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), 28381f3279aeSEric Dumazet LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); 28391f3279aeSEric Dumazet return true; 28401f3279aeSEric Dumazet } 2841f4dae54eSEric Dumazet } 28421f3279aeSEric Dumazet return false; 28431f3279aeSEric Dumazet } 28441f3279aeSEric Dumazet 2845b340b264SYuchung Cheng /* When probe timeout (PTO) fires, try send a new segment if possible, else 28466ba8a3b1SNandita Dukkipati * retransmit the last segment. 28476ba8a3b1SNandita Dukkipati */ 28486ba8a3b1SNandita Dukkipati void tcp_send_loss_probe(struct sock *sk) 28496ba8a3b1SNandita Dukkipati { 28509b717a8dSNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 28516ba8a3b1SNandita Dukkipati struct sk_buff *skb; 28526ba8a3b1SNandita Dukkipati int pcount; 28536ba8a3b1SNandita Dukkipati int mss = tcp_current_mss(sk); 28546ba8a3b1SNandita Dukkipati 285576be93fcSYuchung Cheng /* At most one outstanding TLP */ 285676be93fcSYuchung Cheng if (tp->tlp_high_seq) 285776be93fcSYuchung Cheng goto rearm_timer; 285876be93fcSYuchung Cheng 285976be93fcSYuchung Cheng tp->tlp_retrans = 0; 2860b340b264SYuchung Cheng skb = tcp_send_head(sk); 286175c119afSEric Dumazet if (skb && tcp_snd_wnd_test(tp, skb, mss)) { 2862b340b264SYuchung Cheng pcount = tp->packets_out; 2863b340b264SYuchung Cheng tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); 2864b340b264SYuchung Cheng if (tp->packets_out > pcount) 2865b340b264SYuchung Cheng goto probe_sent; 28666ba8a3b1SNandita Dukkipati goto rearm_timer; 28676ba8a3b1SNandita Dukkipati } 286875c119afSEric Dumazet skb = skb_rb_last(&sk->tcp_rtx_queue); 2869b2b7af86SYuchung Cheng if (unlikely(!skb)) { 2870b2b7af86SYuchung Cheng WARN_ONCE(tp->packets_out, 2871b2b7af86SYuchung Cheng "invalid inflight: %u state %u cwnd %u mss %d\n", 287240570375SEric Dumazet tp->packets_out, sk->sk_state, tcp_snd_cwnd(tp), mss); 2873b2b7af86SYuchung Cheng inet_csk(sk)->icsk_pending = 0; 2874b2b7af86SYuchung Cheng return; 2875b2b7af86SYuchung Cheng } 28766ba8a3b1SNandita Dukkipati 28771f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 28781f3279aeSEric Dumazet goto rearm_timer; 28791f3279aeSEric Dumazet 28806ba8a3b1SNandita Dukkipati pcount = tcp_skb_pcount(skb); 28816ba8a3b1SNandita Dukkipati if (WARN_ON(!pcount)) 28826ba8a3b1SNandita Dukkipati goto rearm_timer; 28836ba8a3b1SNandita Dukkipati 28846ba8a3b1SNandita Dukkipati if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { 288575c119afSEric Dumazet if (unlikely(tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, 288675c119afSEric Dumazet (pcount - 1) * mss, mss, 28876cc55e09SOctavian Purdila GFP_ATOMIC))) 28886ba8a3b1SNandita Dukkipati goto rearm_timer; 288975c119afSEric Dumazet skb = skb_rb_next(skb); 28906ba8a3b1SNandita Dukkipati } 28916ba8a3b1SNandita Dukkipati 28926ba8a3b1SNandita Dukkipati if (WARN_ON(!skb || !tcp_skb_pcount(skb))) 28936ba8a3b1SNandita Dukkipati goto rearm_timer; 28946ba8a3b1SNandita Dukkipati 289510d3be56SEric Dumazet if (__tcp_retransmit_skb(sk, skb, 1)) 2896b340b264SYuchung Cheng goto rearm_timer; 28976ba8a3b1SNandita Dukkipati 289876be93fcSYuchung Cheng tp->tlp_retrans = 1; 289976be93fcSYuchung Cheng 290076be93fcSYuchung Cheng probe_sent: 29019b717a8dSNandita Dukkipati /* Record snd_nxt for loss detection. */ 29029b717a8dSNandita Dukkipati tp->tlp_high_seq = tp->snd_nxt; 29039b717a8dSNandita Dukkipati 2904c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSSPROBES); 2905fcd16c0aSYuchung Cheng /* Reset s.t. tcp_rearm_rto will restart timer from now */ 2906fcd16c0aSYuchung Cheng inet_csk(sk)->icsk_pending = 0; 2907b340b264SYuchung Cheng rearm_timer: 2908fcd16c0aSYuchung Cheng tcp_rearm_rto(sk); 29091da177e4SLinus Torvalds } 29101da177e4SLinus Torvalds 2911a762a980SDavid S. Miller /* Push out any pending frames which were held back due to 2912a762a980SDavid S. Miller * TCP_CORK or attempt at coalescing tiny packets. 2913a762a980SDavid S. Miller * The socket must be locked by the caller. 2914a762a980SDavid S. Miller */ 29159e412ba7SIlpo Järvinen void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 29169e412ba7SIlpo Järvinen int nonagle) 2917a762a980SDavid S. Miller { 2918726e07a8SIlpo Järvinen /* If we are closed, the bytes will have to remain here. 2919726e07a8SIlpo Järvinen * In time closedown will finish, we empty the write queue and 2920726e07a8SIlpo Järvinen * all will be happy. 2921726e07a8SIlpo Järvinen */ 2922726e07a8SIlpo Järvinen if (unlikely(sk->sk_state == TCP_CLOSE)) 2923726e07a8SIlpo Järvinen return; 2924726e07a8SIlpo Järvinen 292599a1dec7SMel Gorman if (tcp_write_xmit(sk, cur_mss, nonagle, 0, 29267450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC))) 29279e412ba7SIlpo Järvinen tcp_check_probe_timer(sk); 2928a762a980SDavid S. Miller } 2929a762a980SDavid S. Miller 2930c1b4a7e6SDavid S. Miller /* Send _single_ skb sitting at the send head. This function requires 2931c1b4a7e6SDavid S. Miller * true push pending frames to setup probe timer etc. 2932c1b4a7e6SDavid S. Miller */ 2933c1b4a7e6SDavid S. Miller void tcp_push_one(struct sock *sk, unsigned int mss_now) 2934c1b4a7e6SDavid S. Miller { 2935fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 2936c1b4a7e6SDavid S. Miller 2937c1b4a7e6SDavid S. Miller BUG_ON(!skb || skb->len < mss_now); 2938c1b4a7e6SDavid S. Miller 2939d5dd9175SIlpo Järvinen tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); 2940c1b4a7e6SDavid S. Miller } 2941c1b4a7e6SDavid S. Miller 29421da177e4SLinus Torvalds /* This function returns the amount that we can raise the 29431da177e4SLinus Torvalds * usable window based on the following constraints 29441da177e4SLinus Torvalds * 29451da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 29461da177e4SLinus Torvalds * 2. We limit memory per socket 29471da177e4SLinus Torvalds * 29481da177e4SLinus Torvalds * RFC 1122: 29491da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 29501da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 29511da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 29521da177e4SLinus Torvalds * 29531da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 29541da177e4SLinus Torvalds * it at least MSS bytes. 29551da177e4SLinus Torvalds * 29561da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 29571da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 29581da177e4SLinus Torvalds * 29591da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 29601da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 29611da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 29621da177e4SLinus Torvalds * window to always advance by a single byte. 29631da177e4SLinus Torvalds * 29641da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 29651da177e4SLinus Torvalds * then this will not be a problem. 29661da177e4SLinus Torvalds * 29671da177e4SLinus Torvalds * BSD seems to make the following compromise: 29681da177e4SLinus Torvalds * 29691da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 29701da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 29711da177e4SLinus Torvalds * then set the window to 0. 29721da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 29731da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 29741da177e4SLinus Torvalds * and from being larger than the largest representable value. 29751da177e4SLinus Torvalds * 29761da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 29771da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 29781da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 29791da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 29801da177e4SLinus Torvalds * because the pipeline is full. 29811da177e4SLinus Torvalds * 29821da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 29831da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 29841da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 29851da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 29861da177e4SLinus Torvalds * of having a fixed window size at almost all times. 29871da177e4SLinus Torvalds * 29881da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 29891da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 29901da177e4SLinus Torvalds * 29911da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 29921da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 29931da177e4SLinus Torvalds */ 29941da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 29951da177e4SLinus Torvalds { 2996463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 29971da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2998b650d953Smfreemon@cloudflare.com struct net *net = sock_net(sk); 2999caa20d9aSStephen Hemminger /* MSS for the peer's data. Previous versions used mss_clamp 30001da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 30011da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 30021da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 30031da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 30041da177e4SLinus Torvalds */ 3005463c84b9SArnaldo Carvalho de Melo int mss = icsk->icsk_ack.rcv_mss; 30061da177e4SLinus Torvalds int free_space = tcp_space(sk); 300786c1a045SFlorian Westphal int allowed_space = tcp_full_space(sk); 3008071c8ed6SFlorian Westphal int full_space, window; 3009071c8ed6SFlorian Westphal 3010071c8ed6SFlorian Westphal if (sk_is_mptcp(sk)) 3011071c8ed6SFlorian Westphal mptcp_space(sk, &free_space, &allowed_space); 3012071c8ed6SFlorian Westphal 3013071c8ed6SFlorian Westphal full_space = min_t(int, tp->window_clamp, allowed_space); 30141da177e4SLinus Torvalds 301506425c30SEric Dumazet if (unlikely(mss > full_space)) { 30161da177e4SLinus Torvalds mss = full_space; 301706425c30SEric Dumazet if (mss <= 0) 301806425c30SEric Dumazet return 0; 301906425c30SEric Dumazet } 3020b650d953Smfreemon@cloudflare.com 3021b650d953Smfreemon@cloudflare.com /* Only allow window shrink if the sysctl is enabled and we have 3022b650d953Smfreemon@cloudflare.com * a non-zero scaling factor in effect. 3023b650d953Smfreemon@cloudflare.com */ 3024b650d953Smfreemon@cloudflare.com if (READ_ONCE(net->ipv4.sysctl_tcp_shrink_window) && tp->rx_opt.rcv_wscale) 3025b650d953Smfreemon@cloudflare.com goto shrink_window_allowed; 3026b650d953Smfreemon@cloudflare.com 3027b650d953Smfreemon@cloudflare.com /* do not allow window to shrink */ 3028b650d953Smfreemon@cloudflare.com 3029b92edbe0SEric Dumazet if (free_space < (full_space >> 1)) { 3030463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.quick = 0; 30311da177e4SLinus Torvalds 3032b8da51ebSEric Dumazet if (tcp_under_memory_pressure(sk)) 3033053f3684SWei Wang tcp_adjust_rcv_ssthresh(sk); 30341da177e4SLinus Torvalds 303586c1a045SFlorian Westphal /* free_space might become our new window, make sure we don't 303686c1a045SFlorian Westphal * increase it due to wscale. 303786c1a045SFlorian Westphal */ 303886c1a045SFlorian Westphal free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); 303986c1a045SFlorian Westphal 304086c1a045SFlorian Westphal /* if free space is less than mss estimate, or is below 1/16th 304186c1a045SFlorian Westphal * of the maximum allowed, try to move to zero-window, else 304286c1a045SFlorian Westphal * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and 304386c1a045SFlorian Westphal * new incoming data is dropped due to memory limits. 304486c1a045SFlorian Westphal * With large window, mss test triggers way too late in order 304586c1a045SFlorian Westphal * to announce zero window in time before rmem limit kicks in. 304686c1a045SFlorian Westphal */ 304786c1a045SFlorian Westphal if (free_space < (allowed_space >> 4) || free_space < mss) 30481da177e4SLinus Torvalds return 0; 30491da177e4SLinus Torvalds } 30501da177e4SLinus Torvalds 30511da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 30521da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 30531da177e4SLinus Torvalds 30541da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 30551da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 30561da177e4SLinus Torvalds */ 30571da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 30581da177e4SLinus Torvalds window = free_space; 30591da177e4SLinus Torvalds 30601da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 30611da177e4SLinus Torvalds * Import case: prevent zero window announcement if 30621da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 30631da177e4SLinus Torvalds */ 30641935299dSGao Feng window = ALIGN(window, (1 << tp->rx_opt.rcv_wscale)); 30651da177e4SLinus Torvalds } else { 30661935299dSGao Feng window = tp->rcv_wnd; 30671da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 30681da177e4SLinus Torvalds * Window clamp already applied above. 30691da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 30701da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 30711da177e4SLinus Torvalds * and multiply from happening most of the time. 30721da177e4SLinus Torvalds * We also don't do any window rounding when the free space 30731da177e4SLinus Torvalds * is too small. 30741da177e4SLinus Torvalds */ 30751da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 30761935299dSGao Feng window = rounddown(free_space, mss); 307784565070SJohn Heffner else if (mss == full_space && 3078b92edbe0SEric Dumazet free_space > window + (full_space >> 1)) 307984565070SJohn Heffner window = free_space; 30801da177e4SLinus Torvalds } 30811da177e4SLinus Torvalds 30821da177e4SLinus Torvalds return window; 3083b650d953Smfreemon@cloudflare.com 3084b650d953Smfreemon@cloudflare.com shrink_window_allowed: 3085b650d953Smfreemon@cloudflare.com /* new window should always be an exact multiple of scaling factor */ 3086b650d953Smfreemon@cloudflare.com free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); 3087b650d953Smfreemon@cloudflare.com 3088b650d953Smfreemon@cloudflare.com if (free_space < (full_space >> 1)) { 3089b650d953Smfreemon@cloudflare.com icsk->icsk_ack.quick = 0; 3090b650d953Smfreemon@cloudflare.com 3091b650d953Smfreemon@cloudflare.com if (tcp_under_memory_pressure(sk)) 3092b650d953Smfreemon@cloudflare.com tcp_adjust_rcv_ssthresh(sk); 3093b650d953Smfreemon@cloudflare.com 3094b650d953Smfreemon@cloudflare.com /* if free space is too low, return a zero window */ 3095b650d953Smfreemon@cloudflare.com if (free_space < (allowed_space >> 4) || free_space < mss || 3096b650d953Smfreemon@cloudflare.com free_space < (1 << tp->rx_opt.rcv_wscale)) 3097b650d953Smfreemon@cloudflare.com return 0; 3098b650d953Smfreemon@cloudflare.com } 3099b650d953Smfreemon@cloudflare.com 3100b650d953Smfreemon@cloudflare.com if (free_space > tp->rcv_ssthresh) { 3101b650d953Smfreemon@cloudflare.com free_space = tp->rcv_ssthresh; 3102b650d953Smfreemon@cloudflare.com /* new window should always be an exact multiple of scaling factor 3103b650d953Smfreemon@cloudflare.com * 3104b650d953Smfreemon@cloudflare.com * For this case, we ALIGN "up" (increase free_space) because 3105b650d953Smfreemon@cloudflare.com * we know free_space is not zero here, it has been reduced from 3106b650d953Smfreemon@cloudflare.com * the memory-based limit, and rcv_ssthresh is not a hard limit 3107b650d953Smfreemon@cloudflare.com * (unlike sk_rcvbuf). 3108b650d953Smfreemon@cloudflare.com */ 3109b650d953Smfreemon@cloudflare.com free_space = ALIGN(free_space, (1 << tp->rx_opt.rcv_wscale)); 3110b650d953Smfreemon@cloudflare.com } 3111b650d953Smfreemon@cloudflare.com 3112b650d953Smfreemon@cloudflare.com return free_space; 31131da177e4SLinus Torvalds } 31141da177e4SLinus Torvalds 3115cfea5a68SMartin KaFai Lau void tcp_skb_collapse_tstamp(struct sk_buff *skb, 3116082ac2d5SMartin KaFai Lau const struct sk_buff *next_skb) 3117082ac2d5SMartin KaFai Lau { 31180a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(next_skb))) { 31190a2cf20cSSoheil Hassas Yeganeh const struct skb_shared_info *next_shinfo = 31200a2cf20cSSoheil Hassas Yeganeh skb_shinfo(next_skb); 3121082ac2d5SMartin KaFai Lau struct skb_shared_info *shinfo = skb_shinfo(skb); 3122082ac2d5SMartin KaFai Lau 31230a2cf20cSSoheil Hassas Yeganeh shinfo->tx_flags |= next_shinfo->tx_flags & SKBTX_ANY_TSTAMP; 3124082ac2d5SMartin KaFai Lau shinfo->tskey = next_shinfo->tskey; 31252de8023eSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack |= 31262de8023eSMartin KaFai Lau TCP_SKB_CB(next_skb)->txstamp_ack; 3127082ac2d5SMartin KaFai Lau } 3128082ac2d5SMartin KaFai Lau } 3129082ac2d5SMartin KaFai Lau 31304a17fc3aSIlpo Järvinen /* Collapses two adjacent SKB's during retransmission. */ 3131f8071cdeSEric Dumazet static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) 31321da177e4SLinus Torvalds { 31331da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 313475c119afSEric Dumazet struct sk_buff *next_skb = skb_rb_next(skb); 313513dde04fSWei Yongjun int next_skb_size; 31361da177e4SLinus Torvalds 3137058dc334SIlpo Järvinen next_skb_size = next_skb->len; 31381da177e4SLinus Torvalds 3139058dc334SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); 31401da177e4SLinus Torvalds 3141bd446314SEric Dumazet if (next_skb_size && !tcp_skb_shift(skb, next_skb, 1, next_skb_size)) 3142f8071cdeSEric Dumazet return false; 3143bd446314SEric Dumazet 31442b7cda9cSEric Dumazet tcp_highest_sack_replace(sk, next_skb, skb); 3145a6963a6bSIlpo Järvinen 31461da177e4SLinus Torvalds /* Update sequence range on original skb. */ 31471da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 31481da177e4SLinus Torvalds 3149e6c7d085SIlpo Järvinen /* Merge over control information. This moves PSH/FIN etc. over */ 31504de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; 31511da177e4SLinus Torvalds 31521da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 31531da177e4SLinus Torvalds * packet counting does not break. 31541da177e4SLinus Torvalds */ 31554828e7f4SIlpo Järvinen TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; 3156a643b5d4SMartin KaFai Lau TCP_SKB_CB(skb)->eor = TCP_SKB_CB(next_skb)->eor; 3157b7689205SIlpo Järvinen 3158b7689205SIlpo Järvinen /* changed transmit queue under us so clear hints */ 3159ef9da47cSIlpo Järvinen tcp_clear_retrans_hints_partial(tp); 3160ef9da47cSIlpo Järvinen if (next_skb == tp->retransmit_skb_hint) 3161ef9da47cSIlpo Järvinen tp->retransmit_skb_hint = skb; 3162b7689205SIlpo Järvinen 3163797108d1SIlpo Järvinen tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); 3164797108d1SIlpo Järvinen 3165082ac2d5SMartin KaFai Lau tcp_skb_collapse_tstamp(skb, next_skb); 3166082ac2d5SMartin KaFai Lau 316775c119afSEric Dumazet tcp_rtx_queue_unlink_and_free(next_skb, sk); 3168f8071cdeSEric Dumazet return true; 31691da177e4SLinus Torvalds } 31701da177e4SLinus Torvalds 317167edfef7SAndi Kleen /* Check if coalescing SKBs is legal. */ 3172a2a385d6SEric Dumazet static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) 31734a17fc3aSIlpo Järvinen { 31744a17fc3aSIlpo Järvinen if (tcp_skb_pcount(skb) > 1) 3175a2a385d6SEric Dumazet return false; 31764a17fc3aSIlpo Järvinen if (skb_cloned(skb)) 3177a2a385d6SEric Dumazet return false; 31782331ccc5SEric Dumazet /* Some heuristics for collapsing over SACK'd could be invented */ 31794a17fc3aSIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 3180a2a385d6SEric Dumazet return false; 31814a17fc3aSIlpo Järvinen 3182a2a385d6SEric Dumazet return true; 31834a17fc3aSIlpo Järvinen } 31844a17fc3aSIlpo Järvinen 318567edfef7SAndi Kleen /* Collapse packets in the retransmit queue to make to create 318667edfef7SAndi Kleen * less packets on the wire. This is only done on retransmission. 318767edfef7SAndi Kleen */ 31884a17fc3aSIlpo Järvinen static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, 31894a17fc3aSIlpo Järvinen int space) 31904a17fc3aSIlpo Järvinen { 31914a17fc3aSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 31924a17fc3aSIlpo Järvinen struct sk_buff *skb = to, *tmp; 3193a2a385d6SEric Dumazet bool first = true; 31944a17fc3aSIlpo Järvinen 31951a63cb91SKuniyuki Iwashima if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_retrans_collapse)) 31964a17fc3aSIlpo Järvinen return; 31974de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 31984a17fc3aSIlpo Järvinen return; 31994a17fc3aSIlpo Järvinen 320075c119afSEric Dumazet skb_rbtree_walk_from_safe(skb, tmp) { 32014a17fc3aSIlpo Järvinen if (!tcp_can_collapse(sk, skb)) 32024a17fc3aSIlpo Järvinen break; 32034a17fc3aSIlpo Järvinen 320485712484SMat Martineau if (!tcp_skb_can_collapse(to, skb)) 3205a643b5d4SMartin KaFai Lau break; 3206a643b5d4SMartin KaFai Lau 32074a17fc3aSIlpo Järvinen space -= skb->len; 32084a17fc3aSIlpo Järvinen 32094a17fc3aSIlpo Järvinen if (first) { 3210a2a385d6SEric Dumazet first = false; 32114a17fc3aSIlpo Järvinen continue; 32124a17fc3aSIlpo Järvinen } 32134a17fc3aSIlpo Järvinen 32144a17fc3aSIlpo Järvinen if (space < 0) 32154a17fc3aSIlpo Järvinen break; 32164a17fc3aSIlpo Järvinen 32174a17fc3aSIlpo Järvinen if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) 32184a17fc3aSIlpo Järvinen break; 32194a17fc3aSIlpo Järvinen 3220f8071cdeSEric Dumazet if (!tcp_collapse_retrans(sk, to)) 3221f8071cdeSEric Dumazet break; 32224a17fc3aSIlpo Järvinen } 32234a17fc3aSIlpo Järvinen } 32244a17fc3aSIlpo Järvinen 32251da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 32261da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 32271da177e4SLinus Torvalds * error occurred which prevented the send. 32281da177e4SLinus Torvalds */ 322910d3be56SEric Dumazet int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 32301da177e4SLinus Torvalds { 32315d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 323210d3be56SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 32337d227cd2SSridhar Samudrala unsigned int cur_mss; 323410d3be56SEric Dumazet int diff, len, err; 3235536a6c8eSYonglong Li int avail_wnd; 323610d3be56SEric Dumazet 323710d3be56SEric Dumazet /* Inconclusive MTU probe */ 323810d3be56SEric Dumazet if (icsk->icsk_mtup.probe_size) 32395d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 32405d424d5aSJohn Heffner 32411f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 32421f3279aeSEric Dumazet return -EBUSY; 32431f3279aeSEric Dumazet 32441da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 32457f582b24SEric Dumazet if (unlikely(before(TCP_SKB_CB(skb)->end_seq, tp->snd_una))) { 32467f582b24SEric Dumazet WARN_ON_ONCE(1); 32477f582b24SEric Dumazet return -EINVAL; 32487f582b24SEric Dumazet } 32491da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 32501da177e4SLinus Torvalds return -ENOMEM; 32511da177e4SLinus Torvalds } 32521da177e4SLinus Torvalds 32537d227cd2SSridhar Samudrala if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 32547d227cd2SSridhar Samudrala return -EHOSTUNREACH; /* Routing failure or similar. */ 32557d227cd2SSridhar Samudrala 32560c54b85fSIlpo Järvinen cur_mss = tcp_current_mss(sk); 3257536a6c8eSYonglong Li avail_wnd = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 32587d227cd2SSridhar Samudrala 32591da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 32601da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 32611da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 3262536a6c8eSYonglong Li * our retransmit of one segment serves as a zero window probe. 32631da177e4SLinus Torvalds */ 3264536a6c8eSYonglong Li if (avail_wnd <= 0) { 3265536a6c8eSYonglong Li if (TCP_SKB_CB(skb)->seq != tp->snd_una) 32661da177e4SLinus Torvalds return -EAGAIN; 3267536a6c8eSYonglong Li avail_wnd = cur_mss; 3268536a6c8eSYonglong Li } 32691da177e4SLinus Torvalds 327010d3be56SEric Dumazet len = cur_mss * segs; 3271536a6c8eSYonglong Li if (len > avail_wnd) { 3272536a6c8eSYonglong Li len = rounddown(avail_wnd, cur_mss); 3273536a6c8eSYonglong Li if (!len) 3274536a6c8eSYonglong Li len = avail_wnd; 3275536a6c8eSYonglong Li } 327610d3be56SEric Dumazet if (skb->len > len) { 327775c119afSEric Dumazet if (tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, len, 327875c119afSEric Dumazet cur_mss, GFP_ATOMIC)) 32791da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 328002276f3cSIlpo Järvinen } else { 3281c4777efaSEric Dumazet if (skb_unclone_keeptruesize(skb, GFP_ATOMIC)) 3282c52e2421SEric Dumazet return -ENOMEM; 328310d3be56SEric Dumazet 328410d3be56SEric Dumazet diff = tcp_skb_pcount(skb); 328510d3be56SEric Dumazet tcp_set_skb_tso_segs(skb, cur_mss); 328610d3be56SEric Dumazet diff -= tcp_skb_pcount(skb); 328710d3be56SEric Dumazet if (diff) 328810d3be56SEric Dumazet tcp_adjust_pcount(sk, skb, diff); 3289536a6c8eSYonglong Li avail_wnd = min_t(int, avail_wnd, cur_mss); 3290536a6c8eSYonglong Li if (skb->len < avail_wnd) 3291536a6c8eSYonglong Li tcp_retrans_try_collapse(sk, skb, avail_wnd); 32921da177e4SLinus Torvalds } 32931da177e4SLinus Torvalds 329449213555SDaniel Borkmann /* RFC3168, section 6.1.1.1. ECN fallback */ 329549213555SDaniel Borkmann if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN_ECN) == TCPHDR_SYN_ECN) 329649213555SDaniel Borkmann tcp_ecn_clear_syn(sk, skb); 329749213555SDaniel Borkmann 3298678550c6SYuchung Cheng /* Update global and local TCP statistics. */ 3299678550c6SYuchung Cheng segs = tcp_skb_pcount(skb); 3300678550c6SYuchung Cheng TCP_ADD_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS, segs); 3301678550c6SYuchung Cheng if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 3302678550c6SYuchung Cheng __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 3303678550c6SYuchung Cheng tp->total_retrans += segs; 3304fb31c9b9SWei Wang tp->bytes_retrans += skb->len; 3305678550c6SYuchung Cheng 330650bceae9SThomas Graf /* make sure skb->data is aligned on arches that require it 330750bceae9SThomas Graf * and check if ack-trimming & collapsing extended the headroom 330850bceae9SThomas Graf * beyond what csum_start can cover. 330950bceae9SThomas Graf */ 331050bceae9SThomas Graf if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || 331150bceae9SThomas Graf skb_headroom(skb) >= 0xFFFF)) { 331210a81980SEric Dumazet struct sk_buff *nskb; 331310a81980SEric Dumazet 3314e2080072SEric Dumazet tcp_skb_tsorted_save(skb) { 331510a81980SEric Dumazet nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC); 331607f8e4d0SFlorian Westphal if (nskb) { 331707f8e4d0SFlorian Westphal nskb->dev = NULL; 331807f8e4d0SFlorian Westphal err = tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC); 331907f8e4d0SFlorian Westphal } else { 332007f8e4d0SFlorian Westphal err = -ENOBUFS; 332107f8e4d0SFlorian Westphal } 3322e2080072SEric Dumazet } tcp_skb_tsorted_restore(skb); 3323e2080072SEric Dumazet 33245889e2c0SYousuk Seung if (!err) { 3325a7a25630SEric Dumazet tcp_update_skb_after_send(sk, skb, tp->tcp_wstamp_ns); 33265889e2c0SYousuk Seung tcp_rate_skb_sent(sk, skb); 33275889e2c0SYousuk Seung } 3328117632e6SEric Dumazet } else { 3329c84a5711SYuchung Cheng err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 3330117632e6SEric Dumazet } 3331c84a5711SYuchung Cheng 33327f12422cSYuchung Cheng /* To avoid taking spuriously low RTT samples based on a timestamp 33337f12422cSYuchung Cheng * for a transmit that never happened, always mark EVER_RETRANS 33347f12422cSYuchung Cheng */ 33357f12422cSYuchung Cheng TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; 33367f12422cSYuchung Cheng 3337a31ad29eSLawrence Brakmo if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RETRANS_CB_FLAG)) 3338a31ad29eSLawrence Brakmo tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RETRANS_CB, 3339a31ad29eSLawrence Brakmo TCP_SKB_CB(skb)->seq, segs, err); 3340a31ad29eSLawrence Brakmo 3341fc9f3501SEric Dumazet if (likely(!err)) { 3342e086101bSCong Wang trace_tcp_retransmit_skb(sk, skb); 3343678550c6SYuchung Cheng } else if (err != -EBUSY) { 3344ec641b39SYuchung Cheng NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL, segs); 3345fc9f3501SEric Dumazet } 3346c84a5711SYuchung Cheng return err; 334793b174adSYuchung Cheng } 334893b174adSYuchung Cheng 334910d3be56SEric Dumazet int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 335093b174adSYuchung Cheng { 335193b174adSYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 335210d3be56SEric Dumazet int err = __tcp_retransmit_skb(sk, skb, segs); 33531da177e4SLinus Torvalds 33541da177e4SLinus Torvalds if (err == 0) { 33551da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 33561da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { 3357e87cc472SJoe Perches net_dbg_ratelimited("retrans_out leaked\n"); 33581da177e4SLinus Torvalds } 33591da177e4SLinus Torvalds #endif 33601da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 33611da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 33627ae18975SYuchung Cheng } 33631da177e4SLinus Torvalds 33647ae18975SYuchung Cheng /* Save stamp of the first (attempted) retransmit. */ 33651da177e4SLinus Torvalds if (!tp->retrans_stamp) 3366614e8316SEric Dumazet tp->retrans_stamp = tcp_skb_timestamp_ts(tp->tcp_usec_ts, skb); 33671da177e4SLinus Torvalds 33686e08d5e3SYuchung Cheng if (tp->undo_retrans < 0) 33696e08d5e3SYuchung Cheng tp->undo_retrans = 0; 33706e08d5e3SYuchung Cheng tp->undo_retrans += tcp_skb_pcount(skb); 33711da177e4SLinus Torvalds return err; 33721da177e4SLinus Torvalds } 33731da177e4SLinus Torvalds 33741da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 33751da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 33761da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 33771da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 33781da177e4SLinus Torvalds */ 33791da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 33801da177e4SLinus Torvalds { 33816687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 3382b9f1f1ceSEric Dumazet struct sk_buff *skb, *rtx_head, *hole = NULL; 33831da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 3384916e6d1aSEric Dumazet bool rearm_timer = false; 3385840a3cbeSYuchung Cheng u32 max_segs; 338661eb55f4SIlpo Järvinen int mib_idx; 33876a438bbeSStephen Hemminger 338845e77d31SIlpo Järvinen if (!tp->packets_out) 338945e77d31SIlpo Järvinen return; 339045e77d31SIlpo Järvinen 339175c119afSEric Dumazet rtx_head = tcp_rtx_queue_head(sk); 3392b9f1f1ceSEric Dumazet skb = tp->retransmit_skb_hint ?: rtx_head; 3393ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, tcp_current_mss(sk)); 339475c119afSEric Dumazet skb_rbtree_walk_from(skb) { 3395dca0aaf8SEric Dumazet __u8 sacked; 339610d3be56SEric Dumazet int segs; 33971da177e4SLinus Torvalds 3398218af599SEric Dumazet if (tcp_pacing_check(sk)) 3399218af599SEric Dumazet break; 3400218af599SEric Dumazet 34016a438bbeSStephen Hemminger /* we could do better than to assign each time */ 340251456b29SIan Morris if (!hole) 34036a438bbeSStephen Hemminger tp->retransmit_skb_hint = skb; 34046a438bbeSStephen Hemminger 340540570375SEric Dumazet segs = tcp_snd_cwnd(tp) - tcp_packets_in_flight(tp); 340610d3be56SEric Dumazet if (segs <= 0) 3407916e6d1aSEric Dumazet break; 3408dca0aaf8SEric Dumazet sacked = TCP_SKB_CB(skb)->sacked; 3409a3d2e9f8SEric Dumazet /* In case tcp_shift_skb_data() have aggregated large skbs, 3410a3d2e9f8SEric Dumazet * we need to make sure not sending too bigs TSO packets 3411a3d2e9f8SEric Dumazet */ 3412a3d2e9f8SEric Dumazet segs = min_t(int, segs, max_segs); 34130e1c54c2SIlpo Järvinen 3414840a3cbeSYuchung Cheng if (tp->retrans_out >= tp->lost_out) { 3415006f582cSIlpo Järvinen break; 34160e1c54c2SIlpo Järvinen } else if (!(sacked & TCPCB_LOST)) { 341751456b29SIan Morris if (!hole && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) 34180e1c54c2SIlpo Järvinen hole = skb; 341961eb55f4SIlpo Järvinen continue; 34201da177e4SLinus Torvalds 34210e1c54c2SIlpo Järvinen } else { 34220e1c54c2SIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Loss) 34230e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFASTRETRANS; 34240e1c54c2SIlpo Järvinen else 34250e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; 34260e1c54c2SIlpo Järvinen } 34270e1c54c2SIlpo Järvinen 34280e1c54c2SIlpo Järvinen if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) 342961eb55f4SIlpo Järvinen continue; 343040b215e5SPavel Emelyanov 3431f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 1)) 3432916e6d1aSEric Dumazet break; 3433f9616c35SEric Dumazet 343410d3be56SEric Dumazet if (tcp_retransmit_skb(sk, skb, segs)) 3435916e6d1aSEric Dumazet break; 343624ab6becSYuchung Cheng 3437de1d6578SYuchung Cheng NET_ADD_STATS(sock_net(sk), mib_idx, tcp_skb_pcount(skb)); 34381da177e4SLinus Torvalds 3439684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 3440a262f0cdSNandita Dukkipati tp->prr_out += tcp_skb_pcount(skb); 3441a262f0cdSNandita Dukkipati 344275c119afSEric Dumazet if (skb == rtx_head && 344357dde7f7SYuchung Cheng icsk->icsk_pending != ICSK_TIME_REO_TIMEOUT) 3444916e6d1aSEric Dumazet rearm_timer = true; 3445916e6d1aSEric Dumazet 3446916e6d1aSEric Dumazet } 3447916e6d1aSEric Dumazet if (rearm_timer) 34483f80e08fSEric Dumazet tcp_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 34493f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, 34508dc242adSEric Dumazet TCP_RTO_MAX); 34511da177e4SLinus Torvalds } 34521da177e4SLinus Torvalds 3453d83769a5SEric Dumazet /* We allow to exceed memory limits for FIN packets to expedite 3454d83769a5SEric Dumazet * connection tear down and (memory) recovery. 3455845704a5SEric Dumazet * Otherwise tcp_send_fin() could be tempted to either delay FIN 3456845704a5SEric Dumazet * or even be forced to close flow without any FIN. 3457a6c5ea4cSEric Dumazet * In general, we want to allow one skb per socket to avoid hangs 3458a6c5ea4cSEric Dumazet * with edge trigger epoll() 3459d83769a5SEric Dumazet */ 3460a6c5ea4cSEric Dumazet void sk_forced_mem_schedule(struct sock *sk, int size) 3461d83769a5SEric Dumazet { 3462c4ee1185SEric Dumazet int delta, amt; 3463d83769a5SEric Dumazet 3464c4ee1185SEric Dumazet delta = size - sk->sk_forward_alloc; 3465c4ee1185SEric Dumazet if (delta <= 0) 3466d83769a5SEric Dumazet return; 3467c4ee1185SEric Dumazet amt = sk_mem_pages(delta); 34685e6300e7SEric Dumazet sk_forward_alloc_add(sk, amt << PAGE_SHIFT); 3469e805605cSJohannes Weiner sk_memory_allocated_add(sk, amt); 3470e805605cSJohannes Weiner 3471baac50bbSJohannes Weiner if (mem_cgroup_sockets_enabled && sk->sk_memcg) 34724b1327beSWei Wang mem_cgroup_charge_skmem(sk->sk_memcg, amt, 34734b1327beSWei Wang gfp_memcg_charge() | __GFP_NOFAIL); 3474d83769a5SEric Dumazet } 3475d83769a5SEric Dumazet 3476845704a5SEric Dumazet /* Send a FIN. The caller locks the socket for us. 3477845704a5SEric Dumazet * We should try to send a FIN packet really hard, but eventually give up. 34781da177e4SLinus Torvalds */ 34791da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 34801da177e4SLinus Torvalds { 3481ee2aabd3SEric Dumazet struct sk_buff *skb, *tskb, *tail = tcp_write_queue_tail(sk); 34821da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 34831da177e4SLinus Torvalds 3484845704a5SEric Dumazet /* Optimization, tack on the FIN if we have one skb in write queue and 3485845704a5SEric Dumazet * this skb was not yet sent, or we are under memory pressure. 3486845704a5SEric Dumazet * Note: in the latter case, FIN packet will be sent after a timeout, 3487845704a5SEric Dumazet * as TCP stack thinks it has already been transmitted. 34881da177e4SLinus Torvalds */ 3489ee2aabd3SEric Dumazet tskb = tail; 349075c119afSEric Dumazet if (!tskb && tcp_under_memory_pressure(sk)) 349175c119afSEric Dumazet tskb = skb_rb_last(&sk->tcp_rtx_queue); 349275c119afSEric Dumazet 349375c119afSEric Dumazet if (tskb) { 3494845704a5SEric Dumazet TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN; 3495845704a5SEric Dumazet TCP_SKB_CB(tskb)->end_seq++; 34961da177e4SLinus Torvalds tp->write_seq++; 3497ee2aabd3SEric Dumazet if (!tail) { 3498845704a5SEric Dumazet /* This means tskb was already sent. 3499845704a5SEric Dumazet * Pretend we included the FIN on previous transmit. 3500845704a5SEric Dumazet * We need to set tp->snd_nxt to the value it would have 3501845704a5SEric Dumazet * if FIN had been sent. This is because retransmit path 3502845704a5SEric Dumazet * does not change tp->snd_nxt. 3503845704a5SEric Dumazet */ 3504e0d694d6SEric Dumazet WRITE_ONCE(tp->snd_nxt, tp->snd_nxt + 1); 3505845704a5SEric Dumazet return; 3506845704a5SEric Dumazet } 35071da177e4SLinus Torvalds } else { 3508845704a5SEric Dumazet skb = alloc_skb_fclone(MAX_TCP_HEADER, sk->sk_allocation); 3509d1edc085SColin Ian King if (unlikely(!skb)) 3510845704a5SEric Dumazet return; 3511d1edc085SColin Ian King 3512e2080072SEric Dumazet INIT_LIST_HEAD(&skb->tcp_tsorted_anchor); 3513d83769a5SEric Dumazet skb_reserve(skb, MAX_TCP_HEADER); 3514a6c5ea4cSEric Dumazet sk_forced_mem_schedule(sk, skb->truesize); 35151da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 3516e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tp->write_seq, 3517a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_FIN); 35181da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 35191da177e4SLinus Torvalds } 3520845704a5SEric Dumazet __tcp_push_pending_frames(sk, tcp_current_mss(sk), TCP_NAGLE_OFF); 35211da177e4SLinus Torvalds } 35221da177e4SLinus Torvalds 35231da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 35241da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 35251da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 352665bb723cSGerrit Renker * by RFC 2525, section 2.17. -DaveM 35271da177e4SLinus Torvalds */ 3528dd0fc66fSAl Viro void tcp_send_active_reset(struct sock *sk, gfp_t priority) 35291da177e4SLinus Torvalds { 35301da177e4SLinus Torvalds struct sk_buff *skb; 35311da177e4SLinus Torvalds 35327cc2b043SGao Feng TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); 35337cc2b043SGao Feng 35341da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 35351da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 35361da177e4SLinus Torvalds if (!skb) { 35374e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 35381da177e4SLinus Torvalds return; 35391da177e4SLinus Torvalds } 35401da177e4SLinus Torvalds 35411da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 35421da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 3543e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), 3544a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_RST); 35459a568de4SEric Dumazet tcp_mstamp_refresh(tcp_sk(sk)); 35461da177e4SLinus Torvalds /* Send it off. */ 3547dfb4b9dcSDavid S. Miller if (tcp_transmit_skb(sk, skb, 0, priority)) 35484e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 3549c24b14c4SSong Liu 3550c24b14c4SSong Liu /* skb of trace_tcp_send_reset() keeps the skb that caused RST, 3551c24b14c4SSong Liu * skb here is different to the troublesome skb, so use NULL 3552c24b14c4SSong Liu */ 3553c24b14c4SSong Liu trace_tcp_send_reset(sk, NULL); 35541da177e4SLinus Torvalds } 35551da177e4SLinus Torvalds 355667edfef7SAndi Kleen /* Send a crossed SYN-ACK during socket establishment. 355767edfef7SAndi Kleen * WARNING: This routine must only be called when we have already sent 35581da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 35591da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 35601da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 35611da177e4SLinus Torvalds */ 35621da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 35631da177e4SLinus Torvalds { 35641da177e4SLinus Torvalds struct sk_buff *skb; 35651da177e4SLinus Torvalds 356675c119afSEric Dumazet skb = tcp_rtx_queue_head(sk); 356751456b29SIan Morris if (!skb || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { 356875c119afSEric Dumazet pr_err("%s: wrong queue state\n", __func__); 35691da177e4SLinus Torvalds return -EFAULT; 35701da177e4SLinus Torvalds } 35714de075e0SEric Dumazet if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { 35721da177e4SLinus Torvalds if (skb_cloned(skb)) { 3573e2080072SEric Dumazet struct sk_buff *nskb; 3574e2080072SEric Dumazet 3575e2080072SEric Dumazet tcp_skb_tsorted_save(skb) { 3576e2080072SEric Dumazet nskb = skb_copy(skb, GFP_ATOMIC); 3577e2080072SEric Dumazet } tcp_skb_tsorted_restore(skb); 357851456b29SIan Morris if (!nskb) 35791da177e4SLinus Torvalds return -ENOMEM; 3580e2080072SEric Dumazet INIT_LIST_HEAD(&nskb->tcp_tsorted_anchor); 35812bec445fSEric Dumazet tcp_highest_sack_replace(sk, skb, nskb); 358275c119afSEric Dumazet tcp_rtx_queue_unlink_and_free(skb, sk); 3583f4a775d1SEric Dumazet __skb_header_release(nskb); 358475c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, nskb); 3585ab4e846aSEric Dumazet sk_wmem_queued_add(sk, nskb->truesize); 35863ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 35871da177e4SLinus Torvalds skb = nskb; 35881da177e4SLinus Torvalds } 35891da177e4SLinus Torvalds 35904de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; 3591735d3831SFlorian Westphal tcp_ecn_send_synack(sk, skb); 35921da177e4SLinus Torvalds } 3593dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 35941da177e4SLinus Torvalds } 35951da177e4SLinus Torvalds 35964aea39c1SEric Dumazet /** 3597331fca43SMartin KaFai Lau * tcp_make_synack - Allocate one skb and build a SYNACK packet. 3598331fca43SMartin KaFai Lau * @sk: listener socket 3599331fca43SMartin KaFai Lau * @dst: dst entry attached to the SYNACK. It is consumed and caller 3600331fca43SMartin KaFai Lau * should not use it again. 3601331fca43SMartin KaFai Lau * @req: request_sock pointer 3602331fca43SMartin KaFai Lau * @foc: cookie for tcp fast open 3603331fca43SMartin KaFai Lau * @synack_type: Type of synack to prepare 3604331fca43SMartin KaFai Lau * @syn_skb: SYN packet just received. It could be NULL for rtx case. 36054aea39c1SEric Dumazet */ 36065d062de7SEric Dumazet struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 3607e6b4d113SWilliam Allen Simpson struct request_sock *req, 3608ca6fb065SEric Dumazet struct tcp_fastopen_cookie *foc, 3609331fca43SMartin KaFai Lau enum tcp_synack_type synack_type, 3610331fca43SMartin KaFai Lau struct sk_buff *syn_skb) 36111da177e4SLinus Torvalds { 36122e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 36135d062de7SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 361480f03e27SEric Dumazet struct tcp_md5sig_key *md5 = NULL; 36155d062de7SEric Dumazet struct tcp_out_options opts; 36165d062de7SEric Dumazet struct sk_buff *skb; 3617bd0388aeSWilliam Allen Simpson int tcp_header_size; 36185d062de7SEric Dumazet struct tcphdr *th; 3619f5fff5dcSTom Quetchenbach int mss; 3620a842fe14SEric Dumazet u64 now; 36211da177e4SLinus Torvalds 3622ca6fb065SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 36234aea39c1SEric Dumazet if (unlikely(!skb)) { 36244aea39c1SEric Dumazet dst_release(dst); 36251da177e4SLinus Torvalds return NULL; 36264aea39c1SEric Dumazet } 36271da177e4SLinus Torvalds /* Reserve space for headers. */ 36281da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 36291da177e4SLinus Torvalds 3630b3d05147SEric Dumazet switch (synack_type) { 3631b3d05147SEric Dumazet case TCP_SYNACK_NORMAL: 36329e17f8a4SEric Dumazet skb_set_owner_w(skb, req_to_sk(req)); 3633b3d05147SEric Dumazet break; 3634b3d05147SEric Dumazet case TCP_SYNACK_COOKIE: 3635b3d05147SEric Dumazet /* Under synflood, we do not attach skb to a socket, 3636b3d05147SEric Dumazet * to avoid false sharing. 3637b3d05147SEric Dumazet */ 3638b3d05147SEric Dumazet break; 3639b3d05147SEric Dumazet case TCP_SYNACK_FASTOPEN: 3640ca6fb065SEric Dumazet /* sk is a const pointer, because we want to express multiple 3641ca6fb065SEric Dumazet * cpu might call us concurrently. 3642ca6fb065SEric Dumazet * sk->sk_wmem_alloc in an atomic, we can promote to rw. 3643ca6fb065SEric Dumazet */ 3644ca6fb065SEric Dumazet skb_set_owner_w(skb, (struct sock *)sk); 3645b3d05147SEric Dumazet break; 3646ca6fb065SEric Dumazet } 36474aea39c1SEric Dumazet skb_dst_set(skb, dst); 36481da177e4SLinus Torvalds 36493541f9e8SEric Dumazet mss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); 3650f5fff5dcSTom Quetchenbach 365133ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 3652614e8316SEric Dumazet if (tcp_rsk(req)->req_usec_ts < 0) 3653614e8316SEric Dumazet tcp_rsk(req)->req_usec_ts = dst_tcp_usec_ts(dst); 3654a842fe14SEric Dumazet now = tcp_clock_ns(); 36558b5f12d0SFlorian Westphal #ifdef CONFIG_SYN_COOKIES 3656f8ace8d9SFlorian Westphal if (unlikely(synack_type == TCP_SYNACK_COOKIE && ireq->tstamp_ok)) 3657a1ac9c8aSMartin KaFai Lau skb_set_delivery_time(skb, cookie_init_timestamp(req, now), 3658a1ac9c8aSMartin KaFai Lau true); 36598b5f12d0SFlorian Westphal else 36608b5f12d0SFlorian Westphal #endif 36619e450c1eSYuchung Cheng { 3662a1ac9c8aSMartin KaFai Lau skb_set_delivery_time(skb, now, true); 36639e450c1eSYuchung Cheng if (!tcp_rsk(req)->snt_synack) /* Timestamp first SYNACK */ 36649e450c1eSYuchung Cheng tcp_rsk(req)->snt_synack = tcp_skb_timestamp_us(skb); 36659e450c1eSYuchung Cheng } 366680f03e27SEric Dumazet 366780f03e27SEric Dumazet #ifdef CONFIG_TCP_MD5SIG 366880f03e27SEric Dumazet rcu_read_lock(); 3669fd3a154aSEric Dumazet md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req)); 367080f03e27SEric Dumazet #endif 36715e526552SEric Dumazet skb_set_hash(skb, READ_ONCE(tcp_rsk(req)->txhash), PKT_HASH_TYPE_L4); 3672331fca43SMartin KaFai Lau /* bpf program will be interested in the tcp_flags */ 3673331fca43SMartin KaFai Lau TCP_SKB_CB(skb)->tcp_flags = TCPHDR_SYN | TCPHDR_ACK; 367460e2a778SUrsula Braun tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, md5, 3675331fca43SMartin KaFai Lau foc, synack_type, 3676331fca43SMartin KaFai Lau syn_skb) + sizeof(*th); 367733ad798cSAdam Langley 3678aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 3679aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 36801da177e4SLinus Torvalds 3681ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 36821da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 36831da177e4SLinus Torvalds th->syn = 1; 36841da177e4SLinus Torvalds th->ack = 1; 36856ac705b1SEric Dumazet tcp_ecn_make_synack(req, th); 3686b44084c2SEric Dumazet th->source = htons(ireq->ir_num); 3687634fb979SEric Dumazet th->dest = ireq->ir_rmt_port; 3688e05a90ecSJamal Hadi Salim skb->mark = ireq->ir_mark; 36893b117750SEric Dumazet skb->ip_summed = CHECKSUM_PARTIAL; 36903b117750SEric Dumazet th->seq = htonl(tcp_rsk(req)->snt_isn); 36918336886fSJerry Chu /* XXX data is queued and acked as is. No buffer/window check */ 36928336886fSJerry Chu th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); 36931da177e4SLinus Torvalds 36941da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 3695ed53d0abSEric Dumazet th->window = htons(min(req->rsk_rcv_wnd, 65535U)); 3696ea66758cSPaolo Abeni tcp_options_write(th, NULL, &opts); 36971da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 3698bced3f7dSBreno Leitao TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS); 3699cfb6eeb4SYOSHIFUJI Hideaki 3700cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 3701cfb6eeb4SYOSHIFUJI Hideaki /* Okay, we have all we need - do the md5 hash if needed */ 370280f03e27SEric Dumazet if (md5) 3703bd0388aeSWilliam Allen Simpson tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, 370439f8e58eSEric Dumazet md5, req_to_sk(req), skb); 370580f03e27SEric Dumazet rcu_read_unlock(); 3706cfb6eeb4SYOSHIFUJI Hideaki #endif 3707cfb6eeb4SYOSHIFUJI Hideaki 3708331fca43SMartin KaFai Lau bpf_skops_write_hdr_opt((struct sock *)sk, skb, req, syn_skb, 3709331fca43SMartin KaFai Lau synack_type, &opts); 3710331fca43SMartin KaFai Lau 3711a1ac9c8aSMartin KaFai Lau skb_set_delivery_time(skb, now, true); 3712a842fe14SEric Dumazet tcp_add_tx_delay(skb, tp); 3713a842fe14SEric Dumazet 37141da177e4SLinus Torvalds return skb; 37151da177e4SLinus Torvalds } 37164bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_make_synack); 37171da177e4SLinus Torvalds 371881164413SDaniel Borkmann static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst) 371981164413SDaniel Borkmann { 372081164413SDaniel Borkmann struct inet_connection_sock *icsk = inet_csk(sk); 372181164413SDaniel Borkmann const struct tcp_congestion_ops *ca; 372281164413SDaniel Borkmann u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); 372381164413SDaniel Borkmann 372481164413SDaniel Borkmann if (ca_key == TCP_CA_UNSPEC) 372581164413SDaniel Borkmann return; 372681164413SDaniel Borkmann 372781164413SDaniel Borkmann rcu_read_lock(); 372881164413SDaniel Borkmann ca = tcp_ca_find_key(ca_key); 37290baf26b0SMartin KaFai Lau if (likely(ca && bpf_try_module_get(ca, ca->owner))) { 37300baf26b0SMartin KaFai Lau bpf_module_put(icsk->icsk_ca_ops, icsk->icsk_ca_ops->owner); 373181164413SDaniel Borkmann icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst); 373281164413SDaniel Borkmann icsk->icsk_ca_ops = ca; 373381164413SDaniel Borkmann } 373481164413SDaniel Borkmann rcu_read_unlock(); 373581164413SDaniel Borkmann } 373681164413SDaniel Borkmann 373767edfef7SAndi Kleen /* Do all connect socket setups that can be done AF independent. */ 3738f7e56a76Sstephen hemminger static void tcp_connect_init(struct sock *sk) 37391da177e4SLinus Torvalds { 3740cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 37411da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 37421da177e4SLinus Torvalds __u8 rcv_wscale; 374313d3b1ebSLawrence Brakmo u32 rcv_wnd; 37441da177e4SLinus Torvalds 37451da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 37461da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 37471da177e4SLinus Torvalds */ 37485d2ed052SEric Dumazet tp->tcp_header_len = sizeof(struct tcphdr); 37493666f666SKuniyuki Iwashima if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_timestamps)) 37505d2ed052SEric Dumazet tp->tcp_header_len += TCPOLEN_TSTAMP_ALIGNED; 37511da177e4SLinus Torvalds 37521da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 37531da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 37541da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 37551da177e4SLinus Torvalds tp->max_window = 0; 37565d424d5aSJohn Heffner tcp_mtup_init(sk); 37571da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 37581da177e4SLinus Torvalds 375981164413SDaniel Borkmann tcp_ca_dst_init(sk, dst); 376081164413SDaniel Borkmann 37611da177e4SLinus Torvalds if (!tp->window_clamp) 37621da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 37633541f9e8SEric Dumazet tp->advmss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); 3764f5fff5dcSTom Quetchenbach 37651da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 37661da177e4SLinus Torvalds 3767e88c64f0SHagen Paul Pfeifer /* limit the window selection if the user enforce a smaller rx buffer */ 3768e88c64f0SHagen Paul Pfeifer if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && 3769e88c64f0SHagen Paul Pfeifer (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) 3770e88c64f0SHagen Paul Pfeifer tp->window_clamp = tcp_full_space(sk); 3771e88c64f0SHagen Paul Pfeifer 377213d3b1ebSLawrence Brakmo rcv_wnd = tcp_rwnd_init_bpf(sk); 377313d3b1ebSLawrence Brakmo if (rcv_wnd == 0) 377413d3b1ebSLawrence Brakmo rcv_wnd = dst_metric(dst, RTAX_INITRWND); 377513d3b1ebSLawrence Brakmo 3776ceef9ab6SEric Dumazet tcp_select_initial_window(sk, tcp_full_space(sk), 37771da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 37781da177e4SLinus Torvalds &tp->rcv_wnd, 37791da177e4SLinus Torvalds &tp->window_clamp, 37803666f666SKuniyuki Iwashima READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_window_scaling), 378131d12926Slaurent chavey &rcv_wscale, 378213d3b1ebSLawrence Brakmo rcv_wnd); 37831da177e4SLinus Torvalds 37841da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 37851da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 37861da177e4SLinus Torvalds 3787e13ec3daSEric Dumazet WRITE_ONCE(sk->sk_err, 0); 37881da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 37891da177e4SLinus Torvalds tp->snd_wnd = 0; 3790ee7537b6SHantzis Fotis tcp_init_wl(tp, 0); 37917f582b24SEric Dumazet tcp_write_queue_purge(sk); 37921da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 37931da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 379433f5f57eSIlpo Järvinen tp->snd_up = tp->write_seq; 3795e0d694d6SEric Dumazet WRITE_ONCE(tp->snd_nxt, tp->write_seq); 3796ee995283SPavel Emelyanov 3797ee995283SPavel Emelyanov if (likely(!tp->repair)) 37981da177e4SLinus Torvalds tp->rcv_nxt = 0; 3799c7781a6eSAndrew Vagin else 380070eabf0eSEric Dumazet tp->rcv_tstamp = tcp_jiffies32; 3801ee995283SPavel Emelyanov tp->rcv_wup = tp->rcv_nxt; 38027db48e98SEric Dumazet WRITE_ONCE(tp->copied_seq, tp->rcv_nxt); 38031da177e4SLinus Torvalds 38048550f328SLawrence Brakmo inet_csk(sk)->icsk_rto = tcp_timeout_init(sk); 3805463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_retransmits = 0; 38061da177e4SLinus Torvalds tcp_clear_retrans(tp); 38071da177e4SLinus Torvalds } 38081da177e4SLinus Torvalds 3809783237e8SYuchung Cheng static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) 3810783237e8SYuchung Cheng { 3811783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3812783237e8SYuchung Cheng struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); 3813783237e8SYuchung Cheng 3814783237e8SYuchung Cheng tcb->end_seq += skb->len; 3815f4a775d1SEric Dumazet __skb_header_release(skb); 3816ab4e846aSEric Dumazet sk_wmem_queued_add(sk, skb->truesize); 3817783237e8SYuchung Cheng sk_mem_charge(sk, skb->truesize); 38180f317464SEric Dumazet WRITE_ONCE(tp->write_seq, tcb->end_seq); 3819783237e8SYuchung Cheng tp->packets_out += tcp_skb_pcount(skb); 3820783237e8SYuchung Cheng } 3821783237e8SYuchung Cheng 3822783237e8SYuchung Cheng /* Build and send a SYN with data and (cached) Fast Open cookie. However, 3823783237e8SYuchung Cheng * queue a data-only packet after the regular SYN, such that regular SYNs 3824783237e8SYuchung Cheng * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges 3825783237e8SYuchung Cheng * only the SYN sequence, the data are retransmitted in the first ACK. 3826783237e8SYuchung Cheng * If cookie is not cached or other error occurs, falls back to send a 3827783237e8SYuchung Cheng * regular SYN with Fast Open cookie request option. 3828783237e8SYuchung Cheng */ 3829783237e8SYuchung Cheng static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) 3830783237e8SYuchung Cheng { 3831ed0c99dcSJakub Kicinski struct inet_connection_sock *icsk = inet_csk(sk); 3832783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3833783237e8SYuchung Cheng struct tcp_fastopen_request *fo = tp->fastopen_req; 3834fbf93406SEric Dumazet struct page_frag *pfrag = sk_page_frag(sk); 3835355a901eSEric Dumazet struct sk_buff *syn_data; 3836fbf93406SEric Dumazet int space, err = 0; 3837783237e8SYuchung Cheng 383867da22d2SYuchung Cheng tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ 3839065263f4SWei Wang if (!tcp_fastopen_cookie_check(sk, &tp->rx_opt.mss_clamp, &fo->cookie)) 3840783237e8SYuchung Cheng goto fallback; 3841783237e8SYuchung Cheng 3842783237e8SYuchung Cheng /* MSS for SYN-data is based on cached MSS and bounded by PMTU and 3843783237e8SYuchung Cheng * user-MSS. Reserve maximum option space for middleboxes that add 3844783237e8SYuchung Cheng * private TCP options. The cost is reduced data space in SYN :( 3845783237e8SYuchung Cheng */ 38463541f9e8SEric Dumazet tp->rx_opt.mss_clamp = tcp_mss_clamp(tp, tp->rx_opt.mss_clamp); 3847ed0c99dcSJakub Kicinski /* Sync mss_cache after updating the mss_clamp */ 3848ed0c99dcSJakub Kicinski tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); 38493541f9e8SEric Dumazet 3850ed0c99dcSJakub Kicinski space = __tcp_mtu_to_mss(sk, icsk->icsk_pmtu_cookie) - 3851783237e8SYuchung Cheng MAX_TCP_OPTION_SPACE; 3852783237e8SYuchung Cheng 3853f5ddcbbbSEric Dumazet space = min_t(size_t, space, fo->size); 3854f5ddcbbbSEric Dumazet 3855fbf93406SEric Dumazet if (space && 3856fbf93406SEric Dumazet !skb_page_frag_refill(min_t(size_t, space, PAGE_SIZE), 3857fbf93406SEric Dumazet pfrag, sk->sk_allocation)) 3858fbf93406SEric Dumazet goto fallback; 38595882efffSEric Dumazet syn_data = tcp_stream_alloc_skb(sk, sk->sk_allocation, false); 3860355a901eSEric Dumazet if (!syn_data) 3861783237e8SYuchung Cheng goto fallback; 3862355a901eSEric Dumazet memcpy(syn_data->cb, syn->cb, sizeof(syn->cb)); 386307e100f9SEric Dumazet if (space) { 3864fbf93406SEric Dumazet space = min_t(size_t, space, pfrag->size - pfrag->offset); 3865fbf93406SEric Dumazet space = tcp_wmem_schedule(sk, space); 3866fbf93406SEric Dumazet } 3867fbf93406SEric Dumazet if (space) { 3868fbf93406SEric Dumazet space = copy_page_from_iter(pfrag->page, pfrag->offset, 3869fbf93406SEric Dumazet space, &fo->data->msg_iter); 3870fbf93406SEric Dumazet if (unlikely(!space)) { 3871ba233b34SEric Dumazet tcp_skb_tsorted_anchor_cleanup(syn_data); 3872355a901eSEric Dumazet kfree_skb(syn_data); 3873783237e8SYuchung Cheng goto fallback; 3874783237e8SYuchung Cheng } 3875fbf93406SEric Dumazet skb_fill_page_desc(syn_data, 0, pfrag->page, 3876fbf93406SEric Dumazet pfrag->offset, space); 3877fbf93406SEric Dumazet page_ref_inc(pfrag->page); 3878fbf93406SEric Dumazet pfrag->offset += space; 3879fbf93406SEric Dumazet skb_len_add(syn_data, space); 3880f859a448SWillem de Bruijn skb_zcopy_set(syn_data, fo->uarg, NULL); 388107e100f9SEric Dumazet } 3882355a901eSEric Dumazet /* No more data pending in inet_wait_for_connect() */ 3883355a901eSEric Dumazet if (space == fo->size) 3884355a901eSEric Dumazet fo->data = NULL; 3885355a901eSEric Dumazet fo->copied = space; 3886783237e8SYuchung Cheng 3887355a901eSEric Dumazet tcp_connect_queue_skb(sk, syn_data); 38880f87230dSFrancis Yan if (syn_data->len) 38890f87230dSFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_BUSY); 3890355a901eSEric Dumazet 3891355a901eSEric Dumazet err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation); 3892355a901eSEric Dumazet 3893a1ac9c8aSMartin KaFai Lau skb_set_delivery_time(syn, syn_data->skb_mstamp_ns, true); 3894355a901eSEric Dumazet 3895355a901eSEric Dumazet /* Now full SYN+DATA was cloned and sent (or not), 3896355a901eSEric Dumazet * remove the SYN from the original skb (syn_data) 3897355a901eSEric Dumazet * we keep in write queue in case of a retransmit, as we 3898355a901eSEric Dumazet * also have the SYN packet (with no data) in the same queue. 3899431a9124SEric Dumazet */ 3900355a901eSEric Dumazet TCP_SKB_CB(syn_data)->seq++; 3901355a901eSEric Dumazet TCP_SKB_CB(syn_data)->tcp_flags = TCPHDR_ACK | TCPHDR_PSH; 3902355a901eSEric Dumazet if (!err) { 390367da22d2SYuchung Cheng tp->syn_data = (fo->copied > 0); 390475c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, syn_data); 3905f19c29e3SYuchung Cheng NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT); 3906783237e8SYuchung Cheng goto done; 3907783237e8SYuchung Cheng } 3908783237e8SYuchung Cheng 390975c119afSEric Dumazet /* data was not sent, put it in write_queue */ 391075c119afSEric Dumazet __skb_queue_tail(&sk->sk_write_queue, syn_data); 3911b5b7db8dSEric Dumazet tp->packets_out -= tcp_skb_pcount(syn_data); 3912b5b7db8dSEric Dumazet 3913783237e8SYuchung Cheng fallback: 3914783237e8SYuchung Cheng /* Send a regular SYN with Fast Open cookie request option */ 3915783237e8SYuchung Cheng if (fo->cookie.len > 0) 3916783237e8SYuchung Cheng fo->cookie.len = 0; 3917783237e8SYuchung Cheng err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); 3918783237e8SYuchung Cheng if (err) 3919783237e8SYuchung Cheng tp->syn_fastopen = 0; 3920783237e8SYuchung Cheng done: 3921783237e8SYuchung Cheng fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ 3922783237e8SYuchung Cheng return err; 3923783237e8SYuchung Cheng } 3924783237e8SYuchung Cheng 392567edfef7SAndi Kleen /* Build a SYN and send it off. */ 39261da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 39271da177e4SLinus Torvalds { 39281da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 39291da177e4SLinus Torvalds struct sk_buff *buff; 3930ee586811SEric Paris int err; 39311da177e4SLinus Torvalds 3932de525be2SLawrence Brakmo tcp_call_bpf(sk, BPF_SOCK_OPS_TCP_CONNECT_CB, 0, NULL); 39338ba60924SEric Dumazet 3934*0aadc739SDmitry Safonov #if defined(CONFIG_TCP_MD5SIG) && defined(CONFIG_TCP_AO) 3935*0aadc739SDmitry Safonov /* Has to be checked late, after setting daddr/saddr/ops. 3936*0aadc739SDmitry Safonov * Return error if the peer has both a md5 and a tcp-ao key 3937*0aadc739SDmitry Safonov * configured as this is ambiguous. 3938*0aadc739SDmitry Safonov */ 3939*0aadc739SDmitry Safonov if (unlikely(rcu_dereference_protected(tp->md5sig_info, 3940*0aadc739SDmitry Safonov lockdep_sock_is_held(sk)))) { 3941*0aadc739SDmitry Safonov bool needs_ao = !!tp->af_specific->ao_lookup(sk, sk, -1, -1); 3942*0aadc739SDmitry Safonov bool needs_md5 = !!tp->af_specific->md5_lookup(sk, sk); 3943*0aadc739SDmitry Safonov struct tcp_ao_info *ao_info; 3944*0aadc739SDmitry Safonov 3945*0aadc739SDmitry Safonov ao_info = rcu_dereference_check(tp->ao_info, 3946*0aadc739SDmitry Safonov lockdep_sock_is_held(sk)); 3947*0aadc739SDmitry Safonov if (ao_info) { 3948*0aadc739SDmitry Safonov /* This is an extra check: tcp_ao_required() in 3949*0aadc739SDmitry Safonov * tcp_v{4,6}_parse_md5_keys() should prevent adding 3950*0aadc739SDmitry Safonov * md5 keys on ao_required socket. 3951*0aadc739SDmitry Safonov */ 3952*0aadc739SDmitry Safonov needs_ao |= ao_info->ao_required; 3953*0aadc739SDmitry Safonov WARN_ON_ONCE(ao_info->ao_required && needs_md5); 3954*0aadc739SDmitry Safonov } 3955*0aadc739SDmitry Safonov if (needs_md5 && needs_ao) 3956*0aadc739SDmitry Safonov return -EKEYREJECTED; 3957*0aadc739SDmitry Safonov 3958*0aadc739SDmitry Safonov /* If we have a matching md5 key and no matching tcp-ao key 3959*0aadc739SDmitry Safonov * then free up ao_info if allocated. 3960*0aadc739SDmitry Safonov */ 3961*0aadc739SDmitry Safonov if (needs_md5) { 3962*0aadc739SDmitry Safonov tcp_ao_destroy_sock(sk); 3963*0aadc739SDmitry Safonov } else if (needs_ao) { 3964*0aadc739SDmitry Safonov tcp_clear_md5_list(sk); 3965*0aadc739SDmitry Safonov kfree(rcu_replace_pointer(tp->md5sig_info, NULL, 3966*0aadc739SDmitry Safonov lockdep_sock_is_held(sk))); 3967*0aadc739SDmitry Safonov } 3968*0aadc739SDmitry Safonov } 3969*0aadc739SDmitry Safonov #endif 3970*0aadc739SDmitry Safonov #ifdef CONFIG_TCP_AO 3971*0aadc739SDmitry Safonov if (unlikely(rcu_dereference_protected(tp->ao_info, 3972*0aadc739SDmitry Safonov lockdep_sock_is_held(sk)))) { 3973*0aadc739SDmitry Safonov /* Don't allow connecting if ao is configured but no 3974*0aadc739SDmitry Safonov * matching key is found. 3975*0aadc739SDmitry Safonov */ 3976*0aadc739SDmitry Safonov if (!tp->af_specific->ao_lookup(sk, sk, -1, -1)) 3977*0aadc739SDmitry Safonov return -EKEYREJECTED; 3978*0aadc739SDmitry Safonov } 3979*0aadc739SDmitry Safonov #endif 3980*0aadc739SDmitry Safonov 39818ba60924SEric Dumazet if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 39828ba60924SEric Dumazet return -EHOSTUNREACH; /* Routing failure or similar. */ 39838ba60924SEric Dumazet 39841da177e4SLinus Torvalds tcp_connect_init(sk); 39851da177e4SLinus Torvalds 39862b916477SAndrey Vagin if (unlikely(tp->repair)) { 39872b916477SAndrey Vagin tcp_finish_connect(sk, NULL); 39882b916477SAndrey Vagin return 0; 39892b916477SAndrey Vagin } 39902b916477SAndrey Vagin 39915882efffSEric Dumazet buff = tcp_stream_alloc_skb(sk, sk->sk_allocation, true); 3992355a901eSEric Dumazet if (unlikely(!buff)) 39931da177e4SLinus Torvalds return -ENOBUFS; 39941da177e4SLinus Torvalds 3995a3433f35SChangli Gao tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); 39969a568de4SEric Dumazet tcp_mstamp_refresh(tp); 39979d0c00f5SEric Dumazet tp->retrans_stamp = tcp_time_stamp_ts(tp); 3998783237e8SYuchung Cheng tcp_connect_queue_skb(sk, buff); 3999735d3831SFlorian Westphal tcp_ecn_send_syn(sk, buff); 400075c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, buff); 40011da177e4SLinus Torvalds 4002783237e8SYuchung Cheng /* Send off SYN; include data in Fast Open. */ 4003783237e8SYuchung Cheng err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : 4004783237e8SYuchung Cheng tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); 4005ee586811SEric Paris if (err == -ECONNREFUSED) 4006ee586811SEric Paris return err; 4007bd37a088SWei Yongjun 4008bd37a088SWei Yongjun /* We change tp->snd_nxt after the tcp_transmit_skb() call 4009bd37a088SWei Yongjun * in order to make this packet get counted in tcpOutSegs. 4010bd37a088SWei Yongjun */ 4011e0d694d6SEric Dumazet WRITE_ONCE(tp->snd_nxt, tp->write_seq); 4012bd37a088SWei Yongjun tp->pushed_seq = tp->write_seq; 4013b5b7db8dSEric Dumazet buff = tcp_send_head(sk); 4014b5b7db8dSEric Dumazet if (unlikely(buff)) { 4015e0d694d6SEric Dumazet WRITE_ONCE(tp->snd_nxt, TCP_SKB_CB(buff)->seq); 4016b5b7db8dSEric Dumazet tp->pushed_seq = TCP_SKB_CB(buff)->seq; 4017b5b7db8dSEric Dumazet } 401881cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); 40191da177e4SLinus Torvalds 40201da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 40213f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 40223f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 40231da177e4SLinus Torvalds return 0; 40241da177e4SLinus Torvalds } 40254bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_connect); 40261da177e4SLinus Torvalds 4027bbf80d71SEric Dumazet u32 tcp_delack_max(const struct sock *sk) 4028bbf80d71SEric Dumazet { 4029bbf80d71SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 4030bbf80d71SEric Dumazet u32 delack_max = inet_csk(sk)->icsk_delack_max; 4031bbf80d71SEric Dumazet 4032bbf80d71SEric Dumazet if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) { 4033bbf80d71SEric Dumazet u32 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 4034bbf80d71SEric Dumazet u32 delack_from_rto_min = max_t(int, 1, rto_min - 1); 4035bbf80d71SEric Dumazet 4036bbf80d71SEric Dumazet delack_max = min_t(u32, delack_max, delack_from_rto_min); 4037bbf80d71SEric Dumazet } 4038bbf80d71SEric Dumazet return delack_max; 4039bbf80d71SEric Dumazet } 4040bbf80d71SEric Dumazet 40411da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 40421da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 40431da177e4SLinus Torvalds * for details. 40441da177e4SLinus Torvalds */ 40451da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 40461da177e4SLinus Torvalds { 4047463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 4048463c84b9SArnaldo Carvalho de Melo int ato = icsk->icsk_ack.ato; 40491da177e4SLinus Torvalds unsigned long timeout; 40501da177e4SLinus Torvalds 40511da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 4052463c84b9SArnaldo Carvalho de Melo const struct tcp_sock *tp = tcp_sk(sk); 40531da177e4SLinus Torvalds int max_ato = HZ / 2; 40541da177e4SLinus Torvalds 405531954cd8SWei Wang if (inet_csk_in_pingpong_mode(sk) || 4056056834d9SIlpo Järvinen (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) 40571da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 40581da177e4SLinus Torvalds 40591da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 40601da177e4SLinus Torvalds 40611da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 4062463c84b9SArnaldo Carvalho de Melo * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements 40631da177e4SLinus Torvalds * directly. 40641da177e4SLinus Torvalds */ 4065740b0f18SEric Dumazet if (tp->srtt_us) { 4066740b0f18SEric Dumazet int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3), 4067740b0f18SEric Dumazet TCP_DELACK_MIN); 40681da177e4SLinus Torvalds 40691da177e4SLinus Torvalds if (rtt < max_ato) 40701da177e4SLinus Torvalds max_ato = rtt; 40711da177e4SLinus Torvalds } 40721da177e4SLinus Torvalds 40731da177e4SLinus Torvalds ato = min(ato, max_ato); 40741da177e4SLinus Torvalds } 40751da177e4SLinus Torvalds 4076bbf80d71SEric Dumazet ato = min_t(u32, ato, tcp_delack_max(sk)); 40772b8ee4f0SMartin KaFai Lau 40781da177e4SLinus Torvalds /* Stay within the limit we were given */ 40791da177e4SLinus Torvalds timeout = jiffies + ato; 40801da177e4SLinus Torvalds 40811da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 4082463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 4083b6b6d653SEric Dumazet /* If delack timer is about to expire, send ACK now. */ 4084b6b6d653SEric Dumazet if (time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { 40851da177e4SLinus Torvalds tcp_send_ack(sk); 40861da177e4SLinus Torvalds return; 40871da177e4SLinus Torvalds } 40881da177e4SLinus Torvalds 4089463c84b9SArnaldo Carvalho de Melo if (!time_before(timeout, icsk->icsk_ack.timeout)) 4090463c84b9SArnaldo Carvalho de Melo timeout = icsk->icsk_ack.timeout; 40911da177e4SLinus Torvalds } 4092463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 4093463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.timeout = timeout; 4094463c84b9SArnaldo Carvalho de Melo sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 40951da177e4SLinus Torvalds } 40961da177e4SLinus Torvalds 40971da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 40982987babbSYuchung Cheng void __tcp_send_ack(struct sock *sk, u32 rcv_nxt) 40991da177e4SLinus Torvalds { 41001da177e4SLinus Torvalds struct sk_buff *buff; 41011da177e4SLinus Torvalds 4102058dc334SIlpo Järvinen /* If we have been reset, we may not send again. */ 4103058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 4104058dc334SIlpo Järvinen return; 4105058dc334SIlpo Järvinen 41061da177e4SLinus Torvalds /* We are not putting this on the write queue, so 41071da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 41081da177e4SLinus Torvalds * sock. 41091da177e4SLinus Torvalds */ 41107450aaf6SEric Dumazet buff = alloc_skb(MAX_TCP_HEADER, 41117450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 41127450aaf6SEric Dumazet if (unlikely(!buff)) { 4113a37c2134SEric Dumazet struct inet_connection_sock *icsk = inet_csk(sk); 4114a37c2134SEric Dumazet unsigned long delay; 4115a37c2134SEric Dumazet 4116a37c2134SEric Dumazet delay = TCP_DELACK_MAX << icsk->icsk_ack.retry; 4117a37c2134SEric Dumazet if (delay < TCP_RTO_MAX) 4118a37c2134SEric Dumazet icsk->icsk_ack.retry++; 4119463c84b9SArnaldo Carvalho de Melo inet_csk_schedule_ack(sk); 4120a37c2134SEric Dumazet icsk->icsk_ack.ato = TCP_ATO_MIN; 4121a37c2134SEric Dumazet inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, delay, TCP_RTO_MAX); 41221da177e4SLinus Torvalds return; 41231da177e4SLinus Torvalds } 41241da177e4SLinus Torvalds 41251da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 41261da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 4127a3433f35SChangli Gao tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); 41281da177e4SLinus Torvalds 412998781965SEric Dumazet /* We do not want pure acks influencing TCP Small Queues or fq/pacing 413098781965SEric Dumazet * too much. 413198781965SEric Dumazet * SKB_TRUESIZE(max(1 .. 66, MAX_TCP_HEADER)) is unfortunately ~784 413298781965SEric Dumazet */ 413398781965SEric Dumazet skb_set_tcp_pure_ack(buff); 413498781965SEric Dumazet 41351da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 41362987babbSYuchung Cheng __tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0, rcv_nxt); 41371da177e4SLinus Torvalds } 413827cde44aSYuchung Cheng EXPORT_SYMBOL_GPL(__tcp_send_ack); 41392987babbSYuchung Cheng 41402987babbSYuchung Cheng void tcp_send_ack(struct sock *sk) 41412987babbSYuchung Cheng { 41422987babbSYuchung Cheng __tcp_send_ack(sk, tcp_sk(sk)->rcv_nxt); 41431da177e4SLinus Torvalds } 41441da177e4SLinus Torvalds 41451da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 41461da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 41471da177e4SLinus Torvalds * 41481da177e4SLinus Torvalds * Question: what should we make while urgent mode? 41491da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 41501da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 41511da177e4SLinus Torvalds * 41521da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 41531da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 41541da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 41551da177e4SLinus Torvalds */ 4156e520af48SEric Dumazet static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib) 41571da177e4SLinus Torvalds { 41581da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 41591da177e4SLinus Torvalds struct sk_buff *skb; 41601da177e4SLinus Torvalds 41611da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 41627450aaf6SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, 41637450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 416451456b29SIan Morris if (!skb) 41651da177e4SLinus Torvalds return -1; 41661da177e4SLinus Torvalds 41671da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 41681da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 41691da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 41701da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 41711da177e4SLinus Torvalds * send it. 41721da177e4SLinus Torvalds */ 4173a3433f35SChangli Gao tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); 4174e2e8009fSRenato Westphal NET_INC_STATS(sock_net(sk), mib); 41757450aaf6SEric Dumazet return tcp_transmit_skb(sk, skb, 0, (__force gfp_t)0); 41761da177e4SLinus Torvalds } 41771da177e4SLinus Torvalds 4178385e2070SEric Dumazet /* Called from setsockopt( ... TCP_REPAIR ) */ 4179ee995283SPavel Emelyanov void tcp_send_window_probe(struct sock *sk) 4180ee995283SPavel Emelyanov { 4181ee995283SPavel Emelyanov if (sk->sk_state == TCP_ESTABLISHED) { 4182ee995283SPavel Emelyanov tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; 41839a568de4SEric Dumazet tcp_mstamp_refresh(tcp_sk(sk)); 4184e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE); 4185ee995283SPavel Emelyanov } 4186ee995283SPavel Emelyanov } 4187ee995283SPavel Emelyanov 418867edfef7SAndi Kleen /* Initiate keepalive or window probe from timer. */ 4189e520af48SEric Dumazet int tcp_write_wakeup(struct sock *sk, int mib) 41901da177e4SLinus Torvalds { 41911da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 41921da177e4SLinus Torvalds struct sk_buff *skb; 41931da177e4SLinus Torvalds 4194058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 4195058dc334SIlpo Järvinen return -1; 4196058dc334SIlpo Järvinen 419700db4124SIan Morris skb = tcp_send_head(sk); 419800db4124SIan Morris if (skb && before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { 41991da177e4SLinus Torvalds int err; 42000c54b85fSIlpo Järvinen unsigned int mss = tcp_current_mss(sk); 420190840defSIlpo Järvinen unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 42021da177e4SLinus Torvalds 42031da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 42041da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 42051da177e4SLinus Torvalds 42061da177e4SLinus Torvalds /* We are probing the opening of a window 42071da177e4SLinus Torvalds * but the window size is != 0 42081da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 42091da177e4SLinus Torvalds */ 42101da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 42111da177e4SLinus Torvalds skb->len > mss) { 42121da177e4SLinus Torvalds seg_size = min(seg_size, mss); 42134de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 421475c119afSEric Dumazet if (tcp_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE, 421575c119afSEric Dumazet skb, seg_size, mss, GFP_ATOMIC)) 42161da177e4SLinus Torvalds return -1; 42171da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 42185bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss); 42191da177e4SLinus Torvalds 42204de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 4221dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 422266f5fe62SIlpo Järvinen if (!err) 422366f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 42241da177e4SLinus Torvalds return err; 42251da177e4SLinus Torvalds } else { 422633f5f57eSIlpo Järvinen if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) 4227e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 1, mib); 4228e520af48SEric Dumazet return tcp_xmit_probe_skb(sk, 0, mib); 42291da177e4SLinus Torvalds } 42301da177e4SLinus Torvalds } 42311da177e4SLinus Torvalds 42321da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 42331da177e4SLinus Torvalds * a partial packet else a zero probe. 42341da177e4SLinus Torvalds */ 42351da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 42361da177e4SLinus Torvalds { 4237463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 42381da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 4239c6214a97SNikolay Borisov struct net *net = sock_net(sk); 4240c1d5674fSYuchung Cheng unsigned long timeout; 42411da177e4SLinus Torvalds int err; 42421da177e4SLinus Torvalds 4243e520af48SEric Dumazet err = tcp_write_wakeup(sk, LINUX_MIB_TCPWINPROBE); 42441da177e4SLinus Torvalds 424575c119afSEric Dumazet if (tp->packets_out || tcp_write_queue_empty(sk)) { 42461da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 42476687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 0; 4248463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff = 0; 42499d9b1ee0SEnke Chen icsk->icsk_probes_tstamp = 0; 42501da177e4SLinus Torvalds return; 42511da177e4SLinus Torvalds } 42521da177e4SLinus Torvalds 4253c1d5674fSYuchung Cheng icsk->icsk_probes_out++; 42541da177e4SLinus Torvalds if (err <= 0) { 425539e24435SKuniyuki Iwashima if (icsk->icsk_backoff < READ_ONCE(net->ipv4.sysctl_tcp_retries2)) 4256463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff++; 4257c1d5674fSYuchung Cheng timeout = tcp_probe0_when(sk, TCP_RTO_MAX); 42581da177e4SLinus Torvalds } else { 42591da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 4260c1d5674fSYuchung Cheng * Let senders fight for local resources conservatively. 42611da177e4SLinus Torvalds */ 4262c1d5674fSYuchung Cheng timeout = TCP_RESOURCE_PROBE_INTERVAL; 42631da177e4SLinus Torvalds } 4264344db93aSEnke Chen 4265344db93aSEnke Chen timeout = tcp_clamp_probe0_to_user_timeout(sk, timeout); 42668dc242adSEric Dumazet tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, timeout, TCP_RTO_MAX); 42671da177e4SLinus Torvalds } 42685db92c99SOctavian Purdila 4269ea3bea3aSEric Dumazet int tcp_rtx_synack(const struct sock *sk, struct request_sock *req) 42705db92c99SOctavian Purdila { 42715db92c99SOctavian Purdila const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific; 42725db92c99SOctavian Purdila struct flowi fl; 42735db92c99SOctavian Purdila int res; 42745db92c99SOctavian Purdila 4275cb6cd2ceSAkhmat Karakotov /* Paired with WRITE_ONCE() in sock_setsockopt() */ 4276cb6cd2ceSAkhmat Karakotov if (READ_ONCE(sk->sk_txrehash) == SOCK_TXREHASH_ENABLED) 42775e526552SEric Dumazet WRITE_ONCE(tcp_rsk(req)->txhash, net_tx_rndhash()); 4278331fca43SMartin KaFai Lau res = af_ops->send_synack(sk, NULL, &fl, req, NULL, TCP_SYNACK_NORMAL, 4279331fca43SMartin KaFai Lau NULL); 42805db92c99SOctavian Purdila if (!res) { 42810a375c82SEric Dumazet TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); 42820a375c82SEric Dumazet NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 4283e9d9da91SEric Dumazet if (unlikely(tcp_passive_fastopen(sk))) { 4284e9d9da91SEric Dumazet /* sk has const attribute because listeners are lockless. 4285e9d9da91SEric Dumazet * However in this case, we are dealing with a passive fastopen 4286e9d9da91SEric Dumazet * socket thus we can change total_retrans value. 4287e9d9da91SEric Dumazet */ 4288e9d9da91SEric Dumazet tcp_sk_rw(sk)->total_retrans++; 4289e9d9da91SEric Dumazet } 4290cf34ce3dSSong Liu trace_tcp_retransmit_synack(sk, req); 42915db92c99SOctavian Purdila } 42925db92c99SOctavian Purdila return res; 42935db92c99SOctavian Purdila } 42945db92c99SOctavian Purdila EXPORT_SYMBOL(tcp_rtx_synack); 4295