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 1734d8f24eeSWei Wang * packet, enter pingpong mode. 1744d8f24eeSWei Wang */ 1754d8f24eeSWei Wang if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) 1764d8f24eeSWei Wang inet_csk_enter_pingpong_mode(sk); 1771da177e4SLinus Torvalds } 1781da177e4SLinus Torvalds 17967edfef7SAndi Kleen /* Account for an ACK we sent. */ 18027cde44aSYuchung Cheng static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts, 18127cde44aSYuchung Cheng u32 rcv_nxt) 1821da177e4SLinus Torvalds { 1835d9f4262SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 1845d9f4262SEric Dumazet 1852b195850SEric Dumazet if (unlikely(tp->compressed_ack)) { 186200d95f4SEric Dumazet NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPACKCOMPRESSED, 1872b195850SEric Dumazet tp->compressed_ack); 1882b195850SEric Dumazet tp->compressed_ack = 0; 1895d9f4262SEric Dumazet if (hrtimer_try_to_cancel(&tp->compressed_ack_timer) == 1) 1905d9f4262SEric Dumazet __sock_put(sk); 1915d9f4262SEric Dumazet } 19227cde44aSYuchung Cheng 19327cde44aSYuchung Cheng if (unlikely(rcv_nxt != tp->rcv_nxt)) 19427cde44aSYuchung Cheng return; /* Special ACK sent by DCTCP to reflect ECN */ 195463c84b9SArnaldo Carvalho de Melo tcp_dec_quickack_mode(sk, pkts); 196463c84b9SArnaldo Carvalho de Melo inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 1971da177e4SLinus Torvalds } 1981da177e4SLinus Torvalds 1991da177e4SLinus Torvalds /* Determine a window scaling and initial window to offer. 2001da177e4SLinus Torvalds * Based on the assumption that the given amount of space 2011da177e4SLinus Torvalds * will be offered. Store the results in the tp structure. 2021da177e4SLinus Torvalds * NOTE: for smooth operation initial space offering should 2031da177e4SLinus Torvalds * be a multiple of mss if possible. We assume here that mss >= 1. 2041da177e4SLinus Torvalds * This MUST be enforced by all callers. 2051da177e4SLinus Torvalds */ 206ceef9ab6SEric Dumazet void tcp_select_initial_window(const struct sock *sk, int __space, __u32 mss, 2071da177e4SLinus Torvalds __u32 *rcv_wnd, __u32 *window_clamp, 20831d12926Slaurent chavey int wscale_ok, __u8 *rcv_wscale, 20931d12926Slaurent chavey __u32 init_rcv_wnd) 2101da177e4SLinus Torvalds { 2111da177e4SLinus Torvalds unsigned int space = (__space < 0 ? 0 : __space); 2121da177e4SLinus Torvalds 2131da177e4SLinus Torvalds /* If no clamp set the clamp to the max possible scaled window */ 2141da177e4SLinus Torvalds if (*window_clamp == 0) 215589c49cbSGao Feng (*window_clamp) = (U16_MAX << TCP_MAX_WSCALE); 2161da177e4SLinus Torvalds space = min(*window_clamp, space); 2171da177e4SLinus Torvalds 2181da177e4SLinus Torvalds /* Quantize space offering to a multiple of mss if possible. */ 2191da177e4SLinus Torvalds if (space > mss) 220589c49cbSGao Feng space = rounddown(space, mss); 2211da177e4SLinus Torvalds 2221da177e4SLinus Torvalds /* NOTE: offering an initial window larger than 32767 22315d99e02SRick Jones * will break some buggy TCP stacks. If the admin tells us 22415d99e02SRick Jones * it is likely we could be speaking with such a buggy stack 22515d99e02SRick Jones * we will truncate our initial window offering to 32K-1 22615d99e02SRick Jones * unless the remote has sent us a window scaling option, 22715d99e02SRick Jones * which we interpret as a sign the remote TCP is not 22815d99e02SRick Jones * misinterpreting the window field as a signed quantity. 2291da177e4SLinus Torvalds */ 2300f1e4d06SKuniyuki Iwashima if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows)) 2311da177e4SLinus Torvalds (*rcv_wnd) = min(space, MAX_TCP_WINDOW); 23215d99e02SRick Jones else 233a337531bSYuchung Cheng (*rcv_wnd) = min_t(u32, space, U16_MAX); 234a337531bSYuchung Cheng 235a337531bSYuchung Cheng if (init_rcv_wnd) 236a337531bSYuchung Cheng *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); 23715d99e02SRick Jones 23819bf6261SEric Dumazet *rcv_wscale = 0; 2391da177e4SLinus Torvalds if (wscale_ok) { 240589c49cbSGao Feng /* Set window scaling on max possible window */ 24102739545SKuniyuki Iwashima space = max_t(u32, space, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2])); 2421227c177SKuniyuki Iwashima space = max_t(u32, space, READ_ONCE(sysctl_rmem_max)); 243316c1592SStephen Hemminger space = min_t(u32, space, *window_clamp); 24419bf6261SEric Dumazet *rcv_wscale = clamp_t(int, ilog2(space) - 15, 24519bf6261SEric Dumazet 0, TCP_MAX_WSCALE); 2461da177e4SLinus Torvalds } 2471da177e4SLinus Torvalds /* Set the clamp no higher than max representable value */ 248589c49cbSGao Feng (*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp); 2491da177e4SLinus Torvalds } 2504bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_select_initial_window); 2511da177e4SLinus Torvalds 2521da177e4SLinus Torvalds /* Chose a new window to advertise, update state in tcp_sock for the 2531da177e4SLinus Torvalds * socket, and return result with RFC1323 scaling applied. The return 2541da177e4SLinus Torvalds * value can be stuffed directly into th->window for an outgoing 2551da177e4SLinus Torvalds * frame. 2561da177e4SLinus Torvalds */ 25740efc6faSStephen Hemminger static u16 tcp_select_window(struct sock *sk) 2581da177e4SLinus Torvalds { 2591da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 260b650d953Smfreemon@cloudflare.com struct net *net = sock_net(sk); 261e2142825SMenglong Dong u32 old_win = tp->rcv_wnd; 262e2142825SMenglong Dong u32 cur_win, new_win; 2631da177e4SLinus Torvalds 264e2142825SMenglong Dong /* Make the window 0 if we failed to queue the data because we 265e2142825SMenglong Dong * are out of memory. The window is temporary, so we don't store 266e2142825SMenglong Dong * it on the socket. 267e2142825SMenglong Dong */ 268e2142825SMenglong Dong if (unlikely(inet_csk(sk)->icsk_ack.pending & ICSK_ACK_NOMEM)) 269e2142825SMenglong Dong return 0; 270e2142825SMenglong Dong 271e2142825SMenglong Dong cur_win = tcp_receive_window(tp); 272e2142825SMenglong Dong new_win = __tcp_select_window(sk); 2731da177e4SLinus Torvalds if (new_win < cur_win) { 2741da177e4SLinus Torvalds /* Danger Will Robinson! 2751da177e4SLinus Torvalds * Don't update rcv_wup/rcv_wnd here or else 2761da177e4SLinus Torvalds * we will not be able to advertise a zero 2771da177e4SLinus Torvalds * window in time. --DaveM 2781da177e4SLinus Torvalds * 2791da177e4SLinus Torvalds * Relax Will Robinson. 2801da177e4SLinus Torvalds */ 281b650d953Smfreemon@cloudflare.com if (!READ_ONCE(net->ipv4.sysctl_tcp_shrink_window) || !tp->rx_opt.rcv_wscale) { 282b650d953Smfreemon@cloudflare.com /* Never shrink the offered window */ 2838e165e20SFlorian Westphal if (new_win == 0) 284b650d953Smfreemon@cloudflare.com NET_INC_STATS(net, LINUX_MIB_TCPWANTZEROWINDOWADV); 285607bfbf2SPatrick McHardy new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); 2861da177e4SLinus Torvalds } 287b650d953Smfreemon@cloudflare.com } 288b650d953Smfreemon@cloudflare.com 2891da177e4SLinus Torvalds tp->rcv_wnd = new_win; 2901da177e4SLinus Torvalds tp->rcv_wup = tp->rcv_nxt; 2911da177e4SLinus Torvalds 2921da177e4SLinus Torvalds /* Make sure we do not exceed the maximum possible 2931da177e4SLinus Torvalds * scaled window. 2941da177e4SLinus Torvalds */ 295ceef9ab6SEric Dumazet if (!tp->rx_opt.rcv_wscale && 296b650d953Smfreemon@cloudflare.com READ_ONCE(net->ipv4.sysctl_tcp_workaround_signed_windows)) 2971da177e4SLinus Torvalds new_win = min(new_win, MAX_TCP_WINDOW); 2981da177e4SLinus Torvalds else 2991da177e4SLinus Torvalds new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 3001da177e4SLinus Torvalds 3011da177e4SLinus Torvalds /* RFC1323 scaling applied */ 3021da177e4SLinus Torvalds new_win >>= tp->rx_opt.rcv_wscale; 3031da177e4SLinus Torvalds 30431770e34SFlorian Westphal /* If we advertise zero window, disable fast path. */ 3058e165e20SFlorian Westphal if (new_win == 0) { 30631770e34SFlorian Westphal tp->pred_flags = 0; 3078e165e20SFlorian Westphal if (old_win) 308b650d953Smfreemon@cloudflare.com NET_INC_STATS(net, LINUX_MIB_TCPTOZEROWINDOWADV); 3098e165e20SFlorian Westphal } else if (old_win == 0) { 310b650d953Smfreemon@cloudflare.com NET_INC_STATS(net, LINUX_MIB_TCPFROMZEROWINDOWADV); 3118e165e20SFlorian Westphal } 3121da177e4SLinus Torvalds 3131da177e4SLinus Torvalds return new_win; 3141da177e4SLinus Torvalds } 3151da177e4SLinus Torvalds 31667edfef7SAndi Kleen /* Packet ECN state for a SYN-ACK */ 317735d3831SFlorian Westphal static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) 318bdf1ee5dSIlpo Järvinen { 31930e502a3SDaniel Borkmann const struct tcp_sock *tp = tcp_sk(sk); 32030e502a3SDaniel Borkmann 3214de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; 322bdf1ee5dSIlpo Järvinen if (!(tp->ecn_flags & TCP_ECN_OK)) 3234de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; 32491b5b21cSLawrence Brakmo else if (tcp_ca_needs_ecn(sk) || 32591b5b21cSLawrence Brakmo tcp_bpf_ca_needs_ecn(sk)) 32630e502a3SDaniel Borkmann INET_ECN_xmit(sk); 327bdf1ee5dSIlpo Järvinen } 328bdf1ee5dSIlpo Järvinen 32967edfef7SAndi Kleen /* Packet ECN state for a SYN. */ 330735d3831SFlorian Westphal static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) 331bdf1ee5dSIlpo Järvinen { 332bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 33391b5b21cSLawrence Brakmo bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk); 3344785a667SKuniyuki Iwashima bool use_ecn = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn) == 1 || 33591b5b21cSLawrence Brakmo tcp_ca_needs_ecn(sk) || bpf_needs_ecn; 336f7b3bec6SFlorian Westphal 337f7b3bec6SFlorian Westphal if (!use_ecn) { 338f7b3bec6SFlorian Westphal const struct dst_entry *dst = __sk_dst_get(sk); 339f7b3bec6SFlorian Westphal 340f7b3bec6SFlorian Westphal if (dst && dst_feature(dst, RTAX_FEATURE_ECN)) 341f7b3bec6SFlorian Westphal use_ecn = true; 342f7b3bec6SFlorian Westphal } 343bdf1ee5dSIlpo Järvinen 344bdf1ee5dSIlpo Järvinen tp->ecn_flags = 0; 345f7b3bec6SFlorian Westphal 346f7b3bec6SFlorian Westphal if (use_ecn) { 3474de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; 348bdf1ee5dSIlpo Järvinen tp->ecn_flags = TCP_ECN_OK; 34991b5b21cSLawrence Brakmo if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn) 35030e502a3SDaniel Borkmann INET_ECN_xmit(sk); 351bdf1ee5dSIlpo Järvinen } 352bdf1ee5dSIlpo Järvinen } 353bdf1ee5dSIlpo Järvinen 35449213555SDaniel Borkmann static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb) 35549213555SDaniel Borkmann { 35612b8d9caSKuniyuki Iwashima if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback)) 35749213555SDaniel Borkmann /* tp->ecn_flags are cleared at a later point in time when 35849213555SDaniel Borkmann * SYN ACK is ultimatively being received. 35949213555SDaniel Borkmann */ 36049213555SDaniel Borkmann TCP_SKB_CB(skb)->tcp_flags &= ~(TCPHDR_ECE | TCPHDR_CWR); 36149213555SDaniel Borkmann } 36249213555SDaniel Borkmann 363735d3831SFlorian Westphal static void 3646ac705b1SEric Dumazet tcp_ecn_make_synack(const struct request_sock *req, struct tcphdr *th) 365bdf1ee5dSIlpo Järvinen { 3666ac705b1SEric Dumazet if (inet_rsk(req)->ecn_ok) 367bdf1ee5dSIlpo Järvinen th->ece = 1; 368bdf1ee5dSIlpo Järvinen } 369bdf1ee5dSIlpo Järvinen 37067edfef7SAndi Kleen /* Set up ECN state for a packet on a ESTABLISHED socket that is about to 37167edfef7SAndi Kleen * be sent. 37267edfef7SAndi Kleen */ 373735d3831SFlorian Westphal static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, 374ea1627c2SEric Dumazet struct tcphdr *th, int tcp_header_len) 375bdf1ee5dSIlpo Järvinen { 376bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 377bdf1ee5dSIlpo Järvinen 378bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_OK) { 379bdf1ee5dSIlpo Järvinen /* Not-retransmitted data segment: set ECT and inject CWR. */ 380bdf1ee5dSIlpo Järvinen if (skb->len != tcp_header_len && 381bdf1ee5dSIlpo Järvinen !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { 382bdf1ee5dSIlpo Järvinen INET_ECN_xmit(sk); 383bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { 384bdf1ee5dSIlpo Järvinen tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; 385ea1627c2SEric Dumazet th->cwr = 1; 386bdf1ee5dSIlpo Järvinen skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 387bdf1ee5dSIlpo Järvinen } 38830e502a3SDaniel Borkmann } else if (!tcp_ca_needs_ecn(sk)) { 389bdf1ee5dSIlpo Järvinen /* ACK or retransmitted segment: clear ECT|CE */ 390bdf1ee5dSIlpo Järvinen INET_ECN_dontxmit(sk); 391bdf1ee5dSIlpo Järvinen } 392bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) 393ea1627c2SEric Dumazet th->ece = 1; 394bdf1ee5dSIlpo Järvinen } 395bdf1ee5dSIlpo Järvinen } 396bdf1ee5dSIlpo Järvinen 397e870a8efSIlpo Järvinen /* Constructs common control bits of non-data skb. If SYN/FIN is present, 398e870a8efSIlpo Järvinen * auto increment end seqno. 399e870a8efSIlpo Järvinen */ 400e870a8efSIlpo Järvinen static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) 401e870a8efSIlpo Järvinen { 4022e8e18efSDavid S. Miller skb->ip_summed = CHECKSUM_PARTIAL; 403e870a8efSIlpo Järvinen 4044de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags; 405e870a8efSIlpo Järvinen 406cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 407e870a8efSIlpo Järvinen 408e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->seq = seq; 409a3433f35SChangli Gao if (flags & (TCPHDR_SYN | TCPHDR_FIN)) 410e870a8efSIlpo Järvinen seq++; 411e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->end_seq = seq; 412e870a8efSIlpo Järvinen } 413e870a8efSIlpo Järvinen 414a2a385d6SEric Dumazet static inline bool tcp_urg_mode(const struct tcp_sock *tp) 41533f5f57eSIlpo Järvinen { 41633f5f57eSIlpo Järvinen return tp->snd_una != tp->snd_up; 41733f5f57eSIlpo Järvinen } 41833f5f57eSIlpo Järvinen 4193b65abb8SLeonard Crestez #define OPTION_SACK_ADVERTISE BIT(0) 4203b65abb8SLeonard Crestez #define OPTION_TS BIT(1) 4213b65abb8SLeonard Crestez #define OPTION_MD5 BIT(2) 4223b65abb8SLeonard Crestez #define OPTION_WSCALE BIT(3) 4233b65abb8SLeonard Crestez #define OPTION_FAST_OPEN_COOKIE BIT(8) 4243b65abb8SLeonard Crestez #define OPTION_SMC BIT(9) 4253b65abb8SLeonard Crestez #define OPTION_MPTCP BIT(10) 42660e2a778SUrsula Braun 42760e2a778SUrsula Braun static void smc_options_write(__be32 *ptr, u16 *options) 42860e2a778SUrsula Braun { 42960e2a778SUrsula Braun #if IS_ENABLED(CONFIG_SMC) 43060e2a778SUrsula Braun if (static_branch_unlikely(&tcp_have_smc)) { 43160e2a778SUrsula Braun if (unlikely(OPTION_SMC & *options)) { 43260e2a778SUrsula Braun *ptr++ = htonl((TCPOPT_NOP << 24) | 43360e2a778SUrsula Braun (TCPOPT_NOP << 16) | 43460e2a778SUrsula Braun (TCPOPT_EXP << 8) | 43560e2a778SUrsula Braun (TCPOLEN_EXP_SMC_BASE)); 43660e2a778SUrsula Braun *ptr++ = htonl(TCPOPT_SMC_MAGIC); 43760e2a778SUrsula Braun } 43860e2a778SUrsula Braun } 43960e2a778SUrsula Braun #endif 44060e2a778SUrsula Braun } 44133ad798cSAdam Langley 44233ad798cSAdam Langley struct tcp_out_options { 4432100c8d2SYuchung Cheng u16 options; /* bit field of OPTION_* */ 4442100c8d2SYuchung Cheng u16 mss; /* 0 to disable */ 44533ad798cSAdam Langley u8 ws; /* window scale, 0 to disable */ 44633ad798cSAdam Langley u8 num_sack_blocks; /* number of SACK blocks to include */ 447bd0388aeSWilliam Allen Simpson u8 hash_size; /* bytes in hash_location */ 448331fca43SMartin KaFai Lau u8 bpf_opt_len; /* length of BPF hdr option */ 449bd0388aeSWilliam Allen Simpson __u8 *hash_location; /* temporary pointer, overloaded */ 4502100c8d2SYuchung Cheng __u32 tsval, tsecr; /* need to include OPTION_TS */ 4512100c8d2SYuchung Cheng struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ 452eda7acddSPeter Krystad struct mptcp_out_options mptcp; 45333ad798cSAdam Langley }; 45433ad798cSAdam Langley 455ea66758cSPaolo Abeni static void mptcp_options_write(struct tcphdr *th, __be32 *ptr, 456ea66758cSPaolo Abeni struct tcp_sock *tp, 457fa3fe2b1SFlorian Westphal struct tcp_out_options *opts) 458eda7acddSPeter Krystad { 459eda7acddSPeter Krystad #if IS_ENABLED(CONFIG_MPTCP) 460eda7acddSPeter Krystad if (unlikely(OPTION_MPTCP & opts->options)) 461ea66758cSPaolo Abeni mptcp_write_options(th, ptr, tp, &opts->mptcp); 462eda7acddSPeter Krystad #endif 463eda7acddSPeter Krystad } 464eda7acddSPeter Krystad 465331fca43SMartin KaFai Lau #ifdef CONFIG_CGROUP_BPF 4660813a841SMartin KaFai Lau static int bpf_skops_write_hdr_opt_arg0(struct sk_buff *skb, 4670813a841SMartin KaFai Lau enum tcp_synack_type synack_type) 4680813a841SMartin KaFai Lau { 4690813a841SMartin KaFai Lau if (unlikely(!skb)) 4700813a841SMartin KaFai Lau return BPF_WRITE_HDR_TCP_CURRENT_MSS; 4710813a841SMartin KaFai Lau 4720813a841SMartin KaFai Lau if (unlikely(synack_type == TCP_SYNACK_COOKIE)) 4730813a841SMartin KaFai Lau return BPF_WRITE_HDR_TCP_SYNACK_COOKIE; 4740813a841SMartin KaFai Lau 4750813a841SMartin KaFai Lau return 0; 4760813a841SMartin KaFai Lau } 4770813a841SMartin KaFai Lau 478331fca43SMartin KaFai Lau /* req, syn_skb and synack_type are used when writing synack */ 479331fca43SMartin KaFai Lau static void bpf_skops_hdr_opt_len(struct sock *sk, struct sk_buff *skb, 480331fca43SMartin KaFai Lau struct request_sock *req, 481331fca43SMartin KaFai Lau struct sk_buff *syn_skb, 482331fca43SMartin KaFai Lau enum tcp_synack_type synack_type, 483331fca43SMartin KaFai Lau struct tcp_out_options *opts, 484331fca43SMartin KaFai Lau unsigned int *remaining) 485331fca43SMartin KaFai Lau { 4860813a841SMartin KaFai Lau struct bpf_sock_ops_kern sock_ops; 4870813a841SMartin KaFai Lau int err; 4880813a841SMartin KaFai Lau 489331fca43SMartin KaFai Lau if (likely(!BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), 490331fca43SMartin KaFai Lau BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG)) || 491331fca43SMartin KaFai Lau !*remaining) 492331fca43SMartin KaFai Lau return; 493331fca43SMartin KaFai Lau 4940813a841SMartin KaFai Lau /* *remaining has already been aligned to 4 bytes, so *remaining >= 4 */ 4950813a841SMartin KaFai Lau 4960813a841SMartin KaFai Lau /* init sock_ops */ 4970813a841SMartin KaFai Lau memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); 4980813a841SMartin KaFai Lau 4990813a841SMartin KaFai Lau sock_ops.op = BPF_SOCK_OPS_HDR_OPT_LEN_CB; 5000813a841SMartin KaFai Lau 5010813a841SMartin KaFai Lau if (req) { 5020813a841SMartin KaFai Lau /* The listen "sk" cannot be passed here because 5030813a841SMartin KaFai Lau * it is not locked. It would not make too much 5040813a841SMartin KaFai Lau * sense to do bpf_setsockopt(listen_sk) based 5050813a841SMartin KaFai Lau * on individual connection request also. 5060813a841SMartin KaFai Lau * 5070813a841SMartin KaFai Lau * Thus, "req" is passed here and the cgroup-bpf-progs 5080813a841SMartin KaFai Lau * of the listen "sk" will be run. 5090813a841SMartin KaFai Lau * 5100813a841SMartin KaFai Lau * "req" is also used here for fastopen even the "sk" here is 5110813a841SMartin KaFai Lau * a fullsock "child" sk. It is to keep the behavior 5120813a841SMartin KaFai Lau * consistent between fastopen and non-fastopen on 5130813a841SMartin KaFai Lau * the bpf programming side. 514331fca43SMartin KaFai Lau */ 5150813a841SMartin KaFai Lau sock_ops.sk = (struct sock *)req; 5160813a841SMartin KaFai Lau sock_ops.syn_skb = syn_skb; 5170813a841SMartin KaFai Lau } else { 5180813a841SMartin KaFai Lau sock_owned_by_me(sk); 5190813a841SMartin KaFai Lau 5200813a841SMartin KaFai Lau sock_ops.is_fullsock = 1; 5210813a841SMartin KaFai Lau sock_ops.sk = sk; 5220813a841SMartin KaFai Lau } 5230813a841SMartin KaFai Lau 5240813a841SMartin KaFai Lau sock_ops.args[0] = bpf_skops_write_hdr_opt_arg0(skb, synack_type); 5250813a841SMartin KaFai Lau sock_ops.remaining_opt_len = *remaining; 5260813a841SMartin KaFai Lau /* tcp_current_mss() does not pass a skb */ 5270813a841SMartin KaFai Lau if (skb) 5280813a841SMartin KaFai Lau bpf_skops_init_skb(&sock_ops, skb, 0); 5290813a841SMartin KaFai Lau 5300813a841SMartin KaFai Lau err = BPF_CGROUP_RUN_PROG_SOCK_OPS_SK(&sock_ops, sk); 5310813a841SMartin KaFai Lau 5320813a841SMartin KaFai Lau if (err || sock_ops.remaining_opt_len == *remaining) 5330813a841SMartin KaFai Lau return; 5340813a841SMartin KaFai Lau 5350813a841SMartin KaFai Lau opts->bpf_opt_len = *remaining - sock_ops.remaining_opt_len; 5360813a841SMartin KaFai Lau /* round up to 4 bytes */ 5370813a841SMartin KaFai Lau opts->bpf_opt_len = (opts->bpf_opt_len + 3) & ~3; 5380813a841SMartin KaFai Lau 5390813a841SMartin KaFai Lau *remaining -= opts->bpf_opt_len; 540331fca43SMartin KaFai Lau } 541331fca43SMartin KaFai Lau 542331fca43SMartin KaFai Lau static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb, 543331fca43SMartin KaFai Lau struct request_sock *req, 544331fca43SMartin KaFai Lau struct sk_buff *syn_skb, 545331fca43SMartin KaFai Lau enum tcp_synack_type synack_type, 546331fca43SMartin KaFai Lau struct tcp_out_options *opts) 547331fca43SMartin KaFai Lau { 5480813a841SMartin KaFai Lau u8 first_opt_off, nr_written, max_opt_len = opts->bpf_opt_len; 5490813a841SMartin KaFai Lau struct bpf_sock_ops_kern sock_ops; 5500813a841SMartin KaFai Lau int err; 5510813a841SMartin KaFai Lau 5520813a841SMartin KaFai Lau if (likely(!max_opt_len)) 553331fca43SMartin KaFai Lau return; 554331fca43SMartin KaFai Lau 5550813a841SMartin KaFai Lau memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); 5560813a841SMartin KaFai Lau 5570813a841SMartin KaFai Lau sock_ops.op = BPF_SOCK_OPS_WRITE_HDR_OPT_CB; 5580813a841SMartin KaFai Lau 5590813a841SMartin KaFai Lau if (req) { 5600813a841SMartin KaFai Lau sock_ops.sk = (struct sock *)req; 5610813a841SMartin KaFai Lau sock_ops.syn_skb = syn_skb; 5620813a841SMartin KaFai Lau } else { 5630813a841SMartin KaFai Lau sock_owned_by_me(sk); 5640813a841SMartin KaFai Lau 5650813a841SMartin KaFai Lau sock_ops.is_fullsock = 1; 5660813a841SMartin KaFai Lau sock_ops.sk = sk; 5670813a841SMartin KaFai Lau } 5680813a841SMartin KaFai Lau 5690813a841SMartin KaFai Lau sock_ops.args[0] = bpf_skops_write_hdr_opt_arg0(skb, synack_type); 5700813a841SMartin KaFai Lau sock_ops.remaining_opt_len = max_opt_len; 5710813a841SMartin KaFai Lau first_opt_off = tcp_hdrlen(skb) - max_opt_len; 5720813a841SMartin KaFai Lau bpf_skops_init_skb(&sock_ops, skb, first_opt_off); 5730813a841SMartin KaFai Lau 5740813a841SMartin KaFai Lau err = BPF_CGROUP_RUN_PROG_SOCK_OPS_SK(&sock_ops, sk); 5750813a841SMartin KaFai Lau 5760813a841SMartin KaFai Lau if (err) 5770813a841SMartin KaFai Lau nr_written = 0; 5780813a841SMartin KaFai Lau else 5790813a841SMartin KaFai Lau nr_written = max_opt_len - sock_ops.remaining_opt_len; 5800813a841SMartin KaFai Lau 5810813a841SMartin KaFai Lau if (nr_written < max_opt_len) 5820813a841SMartin KaFai Lau memset(skb->data + first_opt_off + nr_written, TCPOPT_NOP, 5830813a841SMartin KaFai Lau max_opt_len - nr_written); 584331fca43SMartin KaFai Lau } 585331fca43SMartin KaFai Lau #else 586331fca43SMartin KaFai Lau static void bpf_skops_hdr_opt_len(struct sock *sk, struct sk_buff *skb, 587331fca43SMartin KaFai Lau struct request_sock *req, 588331fca43SMartin KaFai Lau struct sk_buff *syn_skb, 589331fca43SMartin KaFai Lau enum tcp_synack_type synack_type, 590331fca43SMartin KaFai Lau struct tcp_out_options *opts, 591331fca43SMartin KaFai Lau unsigned int *remaining) 592331fca43SMartin KaFai Lau { 593331fca43SMartin KaFai Lau } 594331fca43SMartin KaFai Lau 595331fca43SMartin KaFai Lau static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb, 596331fca43SMartin KaFai Lau struct request_sock *req, 597331fca43SMartin KaFai Lau struct sk_buff *syn_skb, 598331fca43SMartin KaFai Lau enum tcp_synack_type synack_type, 599331fca43SMartin KaFai Lau struct tcp_out_options *opts) 600331fca43SMartin KaFai Lau { 601331fca43SMartin KaFai Lau } 602331fca43SMartin KaFai Lau #endif 603331fca43SMartin KaFai Lau 60467edfef7SAndi Kleen /* Write previously computed TCP options to the packet. 60567edfef7SAndi Kleen * 60667edfef7SAndi Kleen * Beware: Something in the Internet is very sensitive to the ordering of 607fd6149d3SIlpo Järvinen * TCP options, we learned this through the hard way, so be careful here. 608fd6149d3SIlpo Järvinen * Luckily we can at least blame others for their non-compliance but from 6098e3bff96Sstephen hemminger * inter-operability perspective it seems that we're somewhat stuck with 610fd6149d3SIlpo Järvinen * the ordering which we have been using if we want to keep working with 611fd6149d3SIlpo Järvinen * those broken things (not that it currently hurts anybody as there isn't 612fd6149d3SIlpo Järvinen * particular reason why the ordering would need to be changed). 613fd6149d3SIlpo Järvinen * 614fd6149d3SIlpo Järvinen * At least SACK_PERM as the first option is known to lead to a disaster 615fd6149d3SIlpo Järvinen * (but it may well be that other scenarios fail similarly). 616fd6149d3SIlpo Järvinen */ 617ea66758cSPaolo Abeni static void tcp_options_write(struct tcphdr *th, struct tcp_sock *tp, 618bd0388aeSWilliam Allen Simpson struct tcp_out_options *opts) 619bd0388aeSWilliam Allen Simpson { 620ea66758cSPaolo Abeni __be32 *ptr = (__be32 *)(th + 1); 6212100c8d2SYuchung Cheng u16 options = opts->options; /* mungable copy */ 622bd0388aeSWilliam Allen Simpson 623bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_MD5 & options)) { 6241a2c6181SChristoph Paasch *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 6251a2c6181SChristoph Paasch (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); 626bd0388aeSWilliam Allen Simpson /* overload cookie hash location */ 627bd0388aeSWilliam Allen Simpson opts->hash_location = (__u8 *)ptr; 62833ad798cSAdam Langley ptr += 4; 62933ad798cSAdam Langley } 63033ad798cSAdam Langley 631fd6149d3SIlpo Järvinen if (unlikely(opts->mss)) { 632fd6149d3SIlpo Järvinen *ptr++ = htonl((TCPOPT_MSS << 24) | 633fd6149d3SIlpo Järvinen (TCPOLEN_MSS << 16) | 634fd6149d3SIlpo Järvinen opts->mss); 635fd6149d3SIlpo Järvinen } 636fd6149d3SIlpo Järvinen 637bd0388aeSWilliam Allen Simpson if (likely(OPTION_TS & options)) { 638bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 63933ad798cSAdam Langley *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | 64033ad798cSAdam Langley (TCPOLEN_SACK_PERM << 16) | 64133ad798cSAdam Langley (TCPOPT_TIMESTAMP << 8) | 64233ad798cSAdam Langley TCPOLEN_TIMESTAMP); 643bd0388aeSWilliam Allen Simpson options &= ~OPTION_SACK_ADVERTISE; 64433ad798cSAdam Langley } else { 645496c98dfSYOSHIFUJI Hideaki *ptr++ = htonl((TCPOPT_NOP << 24) | 64640efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 64740efc6faSStephen Hemminger (TCPOPT_TIMESTAMP << 8) | 64840efc6faSStephen Hemminger TCPOLEN_TIMESTAMP); 64940efc6faSStephen Hemminger } 65033ad798cSAdam Langley *ptr++ = htonl(opts->tsval); 65133ad798cSAdam Langley *ptr++ = htonl(opts->tsecr); 65233ad798cSAdam Langley } 65333ad798cSAdam Langley 654bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 65533ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 65633ad798cSAdam Langley (TCPOPT_NOP << 16) | 65733ad798cSAdam Langley (TCPOPT_SACK_PERM << 8) | 65833ad798cSAdam Langley TCPOLEN_SACK_PERM); 65933ad798cSAdam Langley } 66033ad798cSAdam Langley 661bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_WSCALE & options)) { 66233ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 66333ad798cSAdam Langley (TCPOPT_WINDOW << 16) | 66433ad798cSAdam Langley (TCPOLEN_WINDOW << 8) | 66533ad798cSAdam Langley opts->ws); 66633ad798cSAdam Langley } 66733ad798cSAdam Langley 66833ad798cSAdam Langley if (unlikely(opts->num_sack_blocks)) { 66933ad798cSAdam Langley struct tcp_sack_block *sp = tp->rx_opt.dsack ? 67033ad798cSAdam Langley tp->duplicate_sack : tp->selective_acks; 67140efc6faSStephen Hemminger int this_sack; 67240efc6faSStephen Hemminger 67340efc6faSStephen Hemminger *ptr++ = htonl((TCPOPT_NOP << 24) | 67440efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 67540efc6faSStephen Hemminger (TCPOPT_SACK << 8) | 67633ad798cSAdam Langley (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * 67740efc6faSStephen Hemminger TCPOLEN_SACK_PERBLOCK))); 6782de979bdSStephen Hemminger 67933ad798cSAdam Langley for (this_sack = 0; this_sack < opts->num_sack_blocks; 68033ad798cSAdam Langley ++this_sack) { 68140efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].start_seq); 68240efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].end_seq); 68340efc6faSStephen Hemminger } 6842de979bdSStephen Hemminger 68540efc6faSStephen Hemminger tp->rx_opt.dsack = 0; 68640efc6faSStephen Hemminger } 6872100c8d2SYuchung Cheng 6882100c8d2SYuchung Cheng if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { 6892100c8d2SYuchung Cheng struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; 6907f9b838bSDaniel Lee u8 *p = (u8 *)ptr; 6917f9b838bSDaniel Lee u32 len; /* Fast Open option length */ 6922100c8d2SYuchung Cheng 6937f9b838bSDaniel Lee if (foc->exp) { 6947f9b838bSDaniel Lee len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; 6957f9b838bSDaniel Lee *ptr = htonl((TCPOPT_EXP << 24) | (len << 16) | 6962100c8d2SYuchung Cheng TCPOPT_FASTOPEN_MAGIC); 6977f9b838bSDaniel Lee p += TCPOLEN_EXP_FASTOPEN_BASE; 6987f9b838bSDaniel Lee } else { 6997f9b838bSDaniel Lee len = TCPOLEN_FASTOPEN_BASE + foc->len; 7007f9b838bSDaniel Lee *p++ = TCPOPT_FASTOPEN; 7017f9b838bSDaniel Lee *p++ = len; 7022100c8d2SYuchung Cheng } 7037f9b838bSDaniel Lee 7047f9b838bSDaniel Lee memcpy(p, foc->val, foc->len); 7057f9b838bSDaniel Lee if ((len & 3) == 2) { 7067f9b838bSDaniel Lee p[foc->len] = TCPOPT_NOP; 7077f9b838bSDaniel Lee p[foc->len + 1] = TCPOPT_NOP; 7087f9b838bSDaniel Lee } 7097f9b838bSDaniel Lee ptr += (len + 3) >> 2; 7102100c8d2SYuchung Cheng } 71160e2a778SUrsula Braun 71260e2a778SUrsula Braun smc_options_write(ptr, &options); 713eda7acddSPeter Krystad 714ea66758cSPaolo Abeni mptcp_options_write(th, ptr, tp, opts); 71560e2a778SUrsula Braun } 71660e2a778SUrsula Braun 71760e2a778SUrsula Braun static void smc_set_option(const struct tcp_sock *tp, 71860e2a778SUrsula Braun struct tcp_out_options *opts, 71960e2a778SUrsula Braun unsigned int *remaining) 72060e2a778SUrsula Braun { 72160e2a778SUrsula Braun #if IS_ENABLED(CONFIG_SMC) 72260e2a778SUrsula Braun if (static_branch_unlikely(&tcp_have_smc)) { 72360e2a778SUrsula Braun if (tp->syn_smc) { 72460e2a778SUrsula Braun if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { 72560e2a778SUrsula Braun opts->options |= OPTION_SMC; 72660e2a778SUrsula Braun *remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; 72760e2a778SUrsula Braun } 72860e2a778SUrsula Braun } 72960e2a778SUrsula Braun } 73060e2a778SUrsula Braun #endif 73160e2a778SUrsula Braun } 73260e2a778SUrsula Braun 73360e2a778SUrsula Braun static void smc_set_option_cond(const struct tcp_sock *tp, 73460e2a778SUrsula Braun const struct inet_request_sock *ireq, 73560e2a778SUrsula Braun struct tcp_out_options *opts, 73660e2a778SUrsula Braun unsigned int *remaining) 73760e2a778SUrsula Braun { 73860e2a778SUrsula Braun #if IS_ENABLED(CONFIG_SMC) 73960e2a778SUrsula Braun if (static_branch_unlikely(&tcp_have_smc)) { 74060e2a778SUrsula Braun if (tp->syn_smc && ireq->smc_ok) { 74160e2a778SUrsula Braun if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { 74260e2a778SUrsula Braun opts->options |= OPTION_SMC; 74360e2a778SUrsula Braun *remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; 74460e2a778SUrsula Braun } 74560e2a778SUrsula Braun } 74660e2a778SUrsula Braun } 74760e2a778SUrsula Braun #endif 74840efc6faSStephen Hemminger } 74940efc6faSStephen Hemminger 750cec37a6eSPeter Krystad static void mptcp_set_option_cond(const struct request_sock *req, 751cec37a6eSPeter Krystad struct tcp_out_options *opts, 752cec37a6eSPeter Krystad unsigned int *remaining) 753cec37a6eSPeter Krystad { 754cec37a6eSPeter Krystad if (rsk_is_mptcp(req)) { 755cec37a6eSPeter Krystad unsigned int size; 756cec37a6eSPeter Krystad 757cec37a6eSPeter Krystad if (mptcp_synack_options(req, &size, &opts->mptcp)) { 758cec37a6eSPeter Krystad if (*remaining >= size) { 759cec37a6eSPeter Krystad opts->options |= OPTION_MPTCP; 760cec37a6eSPeter Krystad *remaining -= size; 761cec37a6eSPeter Krystad } 762cec37a6eSPeter Krystad } 763cec37a6eSPeter Krystad } 764cec37a6eSPeter Krystad } 765cec37a6eSPeter Krystad 76667edfef7SAndi Kleen /* Compute TCP options for SYN packets. This is not the final 76767edfef7SAndi Kleen * network wire format yet. 76867edfef7SAndi Kleen */ 76995c96174SEric Dumazet static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, 77033ad798cSAdam Langley struct tcp_out_options *opts, 771cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 772cf533ea5SEric Dumazet { 77333ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 77495c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 775783237e8SYuchung Cheng struct tcp_fastopen_request *fastopen = tp->fastopen_req; 77633ad798cSAdam Langley 7778c2320e8SEric Dumazet *md5 = NULL; 778cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 779459837b5SDmitry Safonov if (static_branch_unlikely(&tcp_md5_needed.key) && 7806015c71eSEric Dumazet rcu_access_pointer(tp->md5sig_info)) { 78133ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 78233ad798cSAdam Langley if (*md5) { 78333ad798cSAdam Langley opts->options |= OPTION_MD5; 784bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 785cfb6eeb4SYOSHIFUJI Hideaki } 7868c2320e8SEric Dumazet } 787cfb6eeb4SYOSHIFUJI Hideaki #endif 78833ad798cSAdam Langley 78933ad798cSAdam Langley /* We always get an MSS option. The option bytes which will be seen in 79033ad798cSAdam Langley * normal data packets should timestamps be used, must be in the MSS 79133ad798cSAdam Langley * advertised. But we subtract them from tp->mss_cache so that 79233ad798cSAdam Langley * calculations in tcp_sendmsg are simpler etc. So account for this 79333ad798cSAdam Langley * fact here if necessary. If we don't do this correctly, as a 79433ad798cSAdam Langley * receiver we won't recognize data packets as being full sized when we 79533ad798cSAdam Langley * should, and thus we won't abide by the delayed ACK rules correctly. 79633ad798cSAdam Langley * SACKs don't matter, we never delay an ACK when we have any of those 79733ad798cSAdam Langley * going out. */ 79833ad798cSAdam Langley opts->mss = tcp_advertise_mss(sk); 799bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 80033ad798cSAdam Langley 8013666f666SKuniyuki Iwashima if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_timestamps) && !*md5)) { 80233ad798cSAdam Langley opts->options |= OPTION_TS; 8037faee5c0SEric Dumazet opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset; 80433ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 805bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 80633ad798cSAdam Langley } 8073666f666SKuniyuki Iwashima if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_window_scaling))) { 80833ad798cSAdam Langley opts->ws = tp->rx_opt.rcv_wscale; 80989e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 810bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 81133ad798cSAdam Langley } 8123666f666SKuniyuki Iwashima if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_sack))) { 81333ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 814b32d1310SDavid S. Miller if (unlikely(!(OPTION_TS & opts->options))) 815bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 81633ad798cSAdam Langley } 81733ad798cSAdam Langley 818783237e8SYuchung Cheng if (fastopen && fastopen->cookie.len >= 0) { 8192646c831SDaniel Lee u32 need = fastopen->cookie.len; 8202646c831SDaniel Lee 8212646c831SDaniel Lee need += fastopen->cookie.exp ? TCPOLEN_EXP_FASTOPEN_BASE : 8222646c831SDaniel Lee TCPOLEN_FASTOPEN_BASE; 823783237e8SYuchung Cheng need = (need + 3) & ~3U; /* Align to 32 bits */ 824783237e8SYuchung Cheng if (remaining >= need) { 825783237e8SYuchung Cheng opts->options |= OPTION_FAST_OPEN_COOKIE; 826783237e8SYuchung Cheng opts->fastopen_cookie = &fastopen->cookie; 827783237e8SYuchung Cheng remaining -= need; 828783237e8SYuchung Cheng tp->syn_fastopen = 1; 8292646c831SDaniel Lee tp->syn_fastopen_exp = fastopen->cookie.exp ? 1 : 0; 830783237e8SYuchung Cheng } 831783237e8SYuchung Cheng } 832bd0388aeSWilliam Allen Simpson 83360e2a778SUrsula Braun smc_set_option(tp, opts, &remaining); 83460e2a778SUrsula Braun 835cec37a6eSPeter Krystad if (sk_is_mptcp(sk)) { 836cec37a6eSPeter Krystad unsigned int size; 837cec37a6eSPeter Krystad 838cc7972eaSChristoph Paasch if (mptcp_syn_options(sk, skb, &size, &opts->mptcp)) { 839cec37a6eSPeter Krystad opts->options |= OPTION_MPTCP; 840cec37a6eSPeter Krystad remaining -= size; 841cec37a6eSPeter Krystad } 842cec37a6eSPeter Krystad } 843cec37a6eSPeter Krystad 844331fca43SMartin KaFai Lau bpf_skops_hdr_opt_len(sk, skb, NULL, NULL, 0, opts, &remaining); 845331fca43SMartin KaFai Lau 846bd0388aeSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 84733ad798cSAdam Langley } 84833ad798cSAdam Langley 84967edfef7SAndi Kleen /* Set up TCP options for SYN-ACKs. */ 85060e2a778SUrsula Braun static unsigned int tcp_synack_options(const struct sock *sk, 85160e2a778SUrsula Braun struct request_sock *req, 85295c96174SEric Dumazet unsigned int mss, struct sk_buff *skb, 85333ad798cSAdam Langley struct tcp_out_options *opts, 85480f03e27SEric Dumazet const struct tcp_md5sig_key *md5, 855e114e1e8SEric Dumazet struct tcp_fastopen_cookie *foc, 856331fca43SMartin KaFai Lau enum tcp_synack_type synack_type, 857331fca43SMartin KaFai Lau struct sk_buff *syn_skb) 8584957faadSWilliam Allen Simpson { 85933ad798cSAdam Langley struct inet_request_sock *ireq = inet_rsk(req); 86095c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 86133ad798cSAdam Langley 86233ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 86380f03e27SEric Dumazet if (md5) { 86433ad798cSAdam Langley opts->options |= OPTION_MD5; 8654957faadSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 8664957faadSWilliam Allen Simpson 8674957faadSWilliam Allen Simpson /* We can't fit any SACK blocks in a packet with MD5 + TS 8684957faadSWilliam Allen Simpson * options. There was discussion about disabling SACK 8694957faadSWilliam Allen Simpson * rather than TS in order to fit in better with old, 8704957faadSWilliam Allen Simpson * buggy kernels, but that was deemed to be unnecessary. 8714957faadSWilliam Allen Simpson */ 872e114e1e8SEric Dumazet if (synack_type != TCP_SYNACK_COOKIE) 873de213e5eSEric Dumazet ireq->tstamp_ok &= !ireq->sack_ok; 87433ad798cSAdam Langley } 87533ad798cSAdam Langley #endif 87633ad798cSAdam Langley 8774957faadSWilliam Allen Simpson /* We always send an MSS option. */ 87833ad798cSAdam Langley opts->mss = mss; 8794957faadSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 88033ad798cSAdam Langley 88133ad798cSAdam Langley if (likely(ireq->wscale_ok)) { 88233ad798cSAdam Langley opts->ws = ireq->rcv_wscale; 88389e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 8844957faadSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 88533ad798cSAdam Langley } 886de213e5eSEric Dumazet if (likely(ireq->tstamp_ok)) { 88733ad798cSAdam Langley opts->options |= OPTION_TS; 88895a22caeSFlorian Westphal opts->tsval = tcp_skb_timestamp(skb) + 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; 9477faee5c0SEric Dumazet opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0; 94833ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 94933ad798cSAdam Langley size += TCPOLEN_TSTAMP_ALIGNED; 95033ad798cSAdam Langley } 95133ad798cSAdam Langley 952cec37a6eSPeter Krystad /* MPTCP options have precedence over SACK for the limited TCP 953cec37a6eSPeter Krystad * option space because a MPTCP connection would be forced to 954cec37a6eSPeter Krystad * fall back to regular TCP if a required multipath option is 955cec37a6eSPeter Krystad * missing. SACK still gets a chance to use whatever space is 956cec37a6eSPeter Krystad * left. 957cec37a6eSPeter Krystad */ 958cec37a6eSPeter Krystad if (sk_is_mptcp(sk)) { 959cec37a6eSPeter Krystad unsigned int remaining = MAX_TCP_OPTION_SPACE - size; 960cec37a6eSPeter Krystad unsigned int opt_size = 0; 961cec37a6eSPeter Krystad 962cec37a6eSPeter Krystad if (mptcp_established_options(sk, skb, &opt_size, remaining, 963cec37a6eSPeter Krystad &opts->mptcp)) { 964cec37a6eSPeter Krystad opts->options |= OPTION_MPTCP; 965cec37a6eSPeter Krystad size += opt_size; 966cec37a6eSPeter Krystad } 967cec37a6eSPeter Krystad } 968cec37a6eSPeter Krystad 969cabeccbdSIlpo Järvinen eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; 970cabeccbdSIlpo Järvinen if (unlikely(eff_sacks)) { 97195c96174SEric Dumazet const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; 9729cfcca23SMat Martineau if (unlikely(remaining < TCPOLEN_SACK_BASE_ALIGNED + 9739cfcca23SMat Martineau TCPOLEN_SACK_PERBLOCK)) 9749cfcca23SMat Martineau return size; 9759cfcca23SMat Martineau 97633ad798cSAdam Langley opts->num_sack_blocks = 97795c96174SEric Dumazet min_t(unsigned int, eff_sacks, 97833ad798cSAdam Langley (remaining - TCPOLEN_SACK_BASE_ALIGNED) / 97933ad798cSAdam Langley TCPOLEN_SACK_PERBLOCK); 9809cfcca23SMat Martineau 98133ad798cSAdam Langley size += TCPOLEN_SACK_BASE_ALIGNED + 98233ad798cSAdam Langley opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; 98333ad798cSAdam Langley } 98433ad798cSAdam Langley 985331fca43SMartin KaFai Lau if (unlikely(BPF_SOCK_OPS_TEST_FLAG(tp, 986331fca43SMartin KaFai Lau BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG))) { 987331fca43SMartin KaFai Lau unsigned int remaining = MAX_TCP_OPTION_SPACE - size; 988331fca43SMartin KaFai Lau 989331fca43SMartin KaFai Lau bpf_skops_hdr_opt_len(sk, skb, NULL, NULL, 0, opts, &remaining); 990331fca43SMartin KaFai Lau 991331fca43SMartin KaFai Lau size = MAX_TCP_OPTION_SPACE - remaining; 992331fca43SMartin KaFai Lau } 993331fca43SMartin KaFai Lau 99433ad798cSAdam Langley return size; 99540efc6faSStephen Hemminger } 9961da177e4SLinus Torvalds 99746d3ceabSEric Dumazet 99846d3ceabSEric Dumazet /* TCP SMALL QUEUES (TSQ) 99946d3ceabSEric Dumazet * 100046d3ceabSEric Dumazet * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) 100146d3ceabSEric Dumazet * to reduce RTT and bufferbloat. 100246d3ceabSEric Dumazet * We do this using a special skb destructor (tcp_wfree). 100346d3ceabSEric Dumazet * 100446d3ceabSEric Dumazet * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb 100546d3ceabSEric Dumazet * needs to be reallocated in a driver. 10068e3bff96Sstephen hemminger * The invariant being skb->truesize subtracted from sk->sk_wmem_alloc 100746d3ceabSEric Dumazet * 100846d3ceabSEric Dumazet * Since transmit from skb destructor is forbidden, we use a tasklet 100946d3ceabSEric Dumazet * to process all sockets that eventually need to send more skbs. 101046d3ceabSEric Dumazet * We use one tasklet per cpu, with its own queue of sockets. 101146d3ceabSEric Dumazet */ 101246d3ceabSEric Dumazet struct tsq_tasklet { 101346d3ceabSEric Dumazet struct tasklet_struct tasklet; 101446d3ceabSEric Dumazet struct list_head head; /* queue of tcp sockets */ 101546d3ceabSEric Dumazet }; 101646d3ceabSEric Dumazet static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); 101746d3ceabSEric Dumazet 101873a6bab5SEric Dumazet static void tcp_tsq_write(struct sock *sk) 10196f458dfbSEric Dumazet { 10206f458dfbSEric Dumazet if ((1 << sk->sk_state) & 10216f458dfbSEric Dumazet (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | 1022f9616c35SEric Dumazet TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) { 1023f9616c35SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 1024f9616c35SEric Dumazet 1025f9616c35SEric Dumazet if (tp->lost_out > tp->retrans_out && 102640570375SEric Dumazet tcp_snd_cwnd(tp) > tcp_packets_in_flight(tp)) { 10273a91d29fSKoichiro Den tcp_mstamp_refresh(tp); 1028f9616c35SEric Dumazet tcp_xmit_retransmit_queue(sk); 10293a91d29fSKoichiro Den } 1030f9616c35SEric Dumazet 1031f9616c35SEric Dumazet tcp_write_xmit(sk, tcp_current_mss(sk), tp->nonagle, 1032bf06200eSJohn Ogness 0, GFP_ATOMIC); 10336f458dfbSEric Dumazet } 1034f9616c35SEric Dumazet } 103573a6bab5SEric Dumazet 103673a6bab5SEric Dumazet static void tcp_tsq_handler(struct sock *sk) 103773a6bab5SEric Dumazet { 103873a6bab5SEric Dumazet bh_lock_sock(sk); 103973a6bab5SEric Dumazet if (!sock_owned_by_user(sk)) 104073a6bab5SEric Dumazet tcp_tsq_write(sk); 104173a6bab5SEric Dumazet else if (!test_and_set_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags)) 104273a6bab5SEric Dumazet sock_hold(sk); 104373a6bab5SEric Dumazet bh_unlock_sock(sk); 104473a6bab5SEric Dumazet } 104546d3ceabSEric Dumazet /* 10468e3bff96Sstephen hemminger * One tasklet per cpu tries to send more skbs. 104746d3ceabSEric Dumazet * We run in tasklet context but need to disable irqs when 10488e3bff96Sstephen hemminger * transferring tsq->head because tcp_wfree() might 104946d3ceabSEric Dumazet * interrupt us (non NAPI drivers) 105046d3ceabSEric Dumazet */ 1051c6533ca8SAllen Pais static void tcp_tasklet_func(struct tasklet_struct *t) 105246d3ceabSEric Dumazet { 1053c6533ca8SAllen Pais struct tsq_tasklet *tsq = from_tasklet(tsq, t, tasklet); 105446d3ceabSEric Dumazet LIST_HEAD(list); 105546d3ceabSEric Dumazet unsigned long flags; 105646d3ceabSEric Dumazet struct list_head *q, *n; 105746d3ceabSEric Dumazet struct tcp_sock *tp; 105846d3ceabSEric Dumazet struct sock *sk; 105946d3ceabSEric Dumazet 106046d3ceabSEric Dumazet local_irq_save(flags); 106146d3ceabSEric Dumazet list_splice_init(&tsq->head, &list); 106246d3ceabSEric Dumazet local_irq_restore(flags); 106346d3ceabSEric Dumazet 106446d3ceabSEric Dumazet list_for_each_safe(q, n, &list) { 106546d3ceabSEric Dumazet tp = list_entry(q, struct tcp_sock, tsq_node); 106646d3ceabSEric Dumazet list_del(&tp->tsq_node); 106746d3ceabSEric Dumazet 106846d3ceabSEric Dumazet sk = (struct sock *)tp; 10690a9648f1SEric Dumazet smp_mb__before_atomic(); 10707aa5470cSEric Dumazet clear_bit(TSQ_QUEUED, &sk->sk_tsq_flags); 10717aa5470cSEric Dumazet 10726f458dfbSEric Dumazet tcp_tsq_handler(sk); 107346d3ceabSEric Dumazet sk_free(sk); 107446d3ceabSEric Dumazet } 107546d3ceabSEric Dumazet } 107646d3ceabSEric Dumazet 107740fc3423SEric Dumazet #define TCP_DEFERRED_ALL (TCPF_TSQ_DEFERRED | \ 107840fc3423SEric Dumazet TCPF_WRITE_TIMER_DEFERRED | \ 107940fc3423SEric Dumazet TCPF_DELACK_TIMER_DEFERRED | \ 108040fc3423SEric Dumazet TCPF_MTU_REDUCED_DEFERRED) 108146d3ceabSEric Dumazet /** 108246d3ceabSEric Dumazet * tcp_release_cb - tcp release_sock() callback 108346d3ceabSEric Dumazet * @sk: socket 108446d3ceabSEric Dumazet * 108546d3ceabSEric Dumazet * called from release_sock() to perform protocol dependent 108646d3ceabSEric Dumazet * actions before socket release. 108746d3ceabSEric Dumazet */ 108846d3ceabSEric Dumazet void tcp_release_cb(struct sock *sk) 108946d3ceabSEric Dumazet { 1090fac30731SEric Dumazet unsigned long flags = smp_load_acquire(&sk->sk_tsq_flags); 1091fac30731SEric Dumazet unsigned long nflags; 109246d3ceabSEric Dumazet 10936f458dfbSEric Dumazet /* perform an atomic operation only if at least one flag is set */ 10946f458dfbSEric Dumazet do { 10956f458dfbSEric Dumazet if (!(flags & TCP_DEFERRED_ALL)) 10966f458dfbSEric Dumazet return; 10976f458dfbSEric Dumazet nflags = flags & ~TCP_DEFERRED_ALL; 1098fac30731SEric Dumazet } while (!try_cmpxchg(&sk->sk_tsq_flags, &flags, nflags)); 10996f458dfbSEric Dumazet 110073a6bab5SEric Dumazet if (flags & TCPF_TSQ_DEFERRED) { 110173a6bab5SEric Dumazet tcp_tsq_write(sk); 110273a6bab5SEric Dumazet __sock_put(sk); 110373a6bab5SEric Dumazet } 1104c3f9b018SEric Dumazet /* Here begins the tricky part : 1105c3f9b018SEric Dumazet * We are called from release_sock() with : 1106c3f9b018SEric Dumazet * 1) BH disabled 1107c3f9b018SEric Dumazet * 2) sk_lock.slock spinlock held 1108c3f9b018SEric Dumazet * 3) socket owned by us (sk->sk_lock.owned == 1) 1109c3f9b018SEric Dumazet * 1110c3f9b018SEric Dumazet * But following code is meant to be called from BH handlers, 1111c3f9b018SEric Dumazet * so we should keep BH disabled, but early release socket ownership 1112c3f9b018SEric Dumazet */ 1113c3f9b018SEric Dumazet sock_release_ownership(sk); 1114c3f9b018SEric Dumazet 111540fc3423SEric Dumazet if (flags & TCPF_WRITE_TIMER_DEFERRED) { 11166f458dfbSEric Dumazet tcp_write_timer_handler(sk); 1117144d56e9SEric Dumazet __sock_put(sk); 1118144d56e9SEric Dumazet } 111940fc3423SEric Dumazet if (flags & TCPF_DELACK_TIMER_DEFERRED) { 11206f458dfbSEric Dumazet tcp_delack_timer_handler(sk); 1121144d56e9SEric Dumazet __sock_put(sk); 1122144d56e9SEric Dumazet } 112340fc3423SEric Dumazet if (flags & TCPF_MTU_REDUCED_DEFERRED) { 11244fab9071SNeal Cardwell inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); 1125144d56e9SEric Dumazet __sock_put(sk); 1126144d56e9SEric Dumazet } 112746d3ceabSEric Dumazet } 112846d3ceabSEric Dumazet EXPORT_SYMBOL(tcp_release_cb); 112946d3ceabSEric Dumazet 113046d3ceabSEric Dumazet void __init tcp_tasklet_init(void) 113146d3ceabSEric Dumazet { 113246d3ceabSEric Dumazet int i; 113346d3ceabSEric Dumazet 113446d3ceabSEric Dumazet for_each_possible_cpu(i) { 113546d3ceabSEric Dumazet struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); 113646d3ceabSEric Dumazet 113746d3ceabSEric Dumazet INIT_LIST_HEAD(&tsq->head); 1138c6533ca8SAllen Pais tasklet_setup(&tsq->tasklet, tcp_tasklet_func); 113946d3ceabSEric Dumazet } 114046d3ceabSEric Dumazet } 114146d3ceabSEric Dumazet 114246d3ceabSEric Dumazet /* 114346d3ceabSEric Dumazet * Write buffer destructor automatically called from kfree_skb. 11448e3bff96Sstephen hemminger * We can't xmit new skbs from this context, as we might already 114546d3ceabSEric Dumazet * hold qdisc lock. 114646d3ceabSEric Dumazet */ 1147d6a4a104SEric Dumazet void tcp_wfree(struct sk_buff *skb) 114846d3ceabSEric Dumazet { 114946d3ceabSEric Dumazet struct sock *sk = skb->sk; 115046d3ceabSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 1151408f0a6cSEric Dumazet unsigned long flags, nval, oval; 1152b548b17aSEric Dumazet struct tsq_tasklet *tsq; 1153b548b17aSEric Dumazet bool empty; 11549b462d02SEric Dumazet 11559b462d02SEric Dumazet /* Keep one reference on sk_wmem_alloc. 11569b462d02SEric Dumazet * Will be released by sk_free() from here or tcp_tasklet_func() 11579b462d02SEric Dumazet */ 115814afee4bSReshetova, Elena WARN_ON(refcount_sub_and_test(skb->truesize - 1, &sk->sk_wmem_alloc)); 11599b462d02SEric Dumazet 11609b462d02SEric Dumazet /* If this softirq is serviced by ksoftirqd, we are likely under stress. 11619b462d02SEric Dumazet * Wait until our queues (qdisc + devices) are drained. 11629b462d02SEric Dumazet * This gives : 11639b462d02SEric Dumazet * - less callbacks to tcp_write_xmit(), reducing stress (batches) 11649b462d02SEric Dumazet * - chance for incoming ACK (processed by another cpu maybe) 11659b462d02SEric Dumazet * to migrate this flow (skb->ooo_okay will be eventually set) 11669b462d02SEric Dumazet */ 116714afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) 11689b462d02SEric Dumazet goto out; 116946d3ceabSEric Dumazet 1170b548b17aSEric Dumazet oval = smp_load_acquire(&sk->sk_tsq_flags); 1171b548b17aSEric Dumazet do { 1172408f0a6cSEric Dumazet if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED)) 1173408f0a6cSEric Dumazet goto out; 1174408f0a6cSEric Dumazet 117573a6bab5SEric Dumazet nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED; 1176b548b17aSEric Dumazet } while (!try_cmpxchg(&sk->sk_tsq_flags, &oval, nval)); 1177408f0a6cSEric Dumazet 117846d3ceabSEric Dumazet /* queue this socket to tasklet queue */ 117946d3ceabSEric Dumazet local_irq_save(flags); 1180903ceff7SChristoph Lameter tsq = this_cpu_ptr(&tsq_tasklet); 1181a9b204d1SEric Dumazet empty = list_empty(&tsq->head); 118246d3ceabSEric Dumazet list_add(&tp->tsq_node, &tsq->head); 1183a9b204d1SEric Dumazet if (empty) 118446d3ceabSEric Dumazet tasklet_schedule(&tsq->tasklet); 118546d3ceabSEric Dumazet local_irq_restore(flags); 11869b462d02SEric Dumazet return; 11879b462d02SEric Dumazet out: 11889b462d02SEric Dumazet sk_free(sk); 118946d3ceabSEric Dumazet } 119046d3ceabSEric Dumazet 119173a6bab5SEric Dumazet /* Note: Called under soft irq. 119273a6bab5SEric Dumazet * We can call TCP stack right away, unless socket is owned by user. 1193218af599SEric Dumazet */ 1194218af599SEric Dumazet enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer) 1195218af599SEric Dumazet { 1196218af599SEric Dumazet struct tcp_sock *tp = container_of(timer, struct tcp_sock, pacing_timer); 1197218af599SEric Dumazet struct sock *sk = (struct sock *)tp; 1198218af599SEric Dumazet 119973a6bab5SEric Dumazet tcp_tsq_handler(sk); 120073a6bab5SEric Dumazet sock_put(sk); 1201218af599SEric Dumazet 1202218af599SEric Dumazet return HRTIMER_NORESTART; 1203218af599SEric Dumazet } 1204218af599SEric Dumazet 1205a7a25630SEric Dumazet static void tcp_update_skb_after_send(struct sock *sk, struct sk_buff *skb, 1206a7a25630SEric Dumazet u64 prior_wstamp) 1207e2080072SEric Dumazet { 1208ab408b6dSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 1209ab408b6dSEric Dumazet 1210ab408b6dSEric Dumazet if (sk->sk_pacing_status != SK_PACING_NONE) { 121176a9ebe8SEric Dumazet unsigned long rate = sk->sk_pacing_rate; 1212ab408b6dSEric Dumazet 1213ab408b6dSEric Dumazet /* Original sch_fq does not pace first 10 MSS 1214ab408b6dSEric Dumazet * Note that tp->data_segs_out overflows after 2^32 packets, 1215ab408b6dSEric Dumazet * this is a minor annoyance. 1216ab408b6dSEric Dumazet */ 121776a9ebe8SEric Dumazet if (rate != ~0UL && rate && tp->data_segs_out >= 10) { 1218a7a25630SEric Dumazet u64 len_ns = div64_ul((u64)skb->len * NSEC_PER_SEC, rate); 1219a7a25630SEric Dumazet u64 credit = tp->tcp_wstamp_ns - prior_wstamp; 1220a7a25630SEric Dumazet 1221a7a25630SEric Dumazet /* take into account OS jitter */ 1222a7a25630SEric Dumazet len_ns -= min_t(u64, len_ns / 2, credit); 1223a7a25630SEric Dumazet tp->tcp_wstamp_ns += len_ns; 1224ab408b6dSEric Dumazet } 1225ab408b6dSEric Dumazet } 1226e2080072SEric Dumazet list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); 1227e2080072SEric Dumazet } 1228e2080072SEric Dumazet 122905e22e83SEric Dumazet INDIRECT_CALLABLE_DECLARE(int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)); 123005e22e83SEric Dumazet INDIRECT_CALLABLE_DECLARE(int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)); 1231dd2e0b86SEric Dumazet INDIRECT_CALLABLE_DECLARE(void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)); 123205e22e83SEric Dumazet 12331da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 12341da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 12351da177e4SLinus Torvalds * transmission and possible later retransmissions. 12361da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 12371da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 12381da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 12391da177e4SLinus Torvalds * device. 12401da177e4SLinus Torvalds * 12411da177e4SLinus Torvalds * We are working here with either a clone of the original 12421da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 12431da177e4SLinus Torvalds */ 12442987babbSYuchung Cheng static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, 12452987babbSYuchung Cheng int clone_it, gfp_t gfp_mask, u32 rcv_nxt) 12461da177e4SLinus Torvalds { 12476687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 1248dfb4b9dcSDavid S. Miller struct inet_sock *inet; 1249dfb4b9dcSDavid S. Miller struct tcp_sock *tp; 1250dfb4b9dcSDavid S. Miller struct tcp_skb_cb *tcb; 125133ad798cSAdam Langley struct tcp_out_options opts; 125295c96174SEric Dumazet unsigned int tcp_options_size, tcp_header_size; 12538c72c65bSEric Dumazet struct sk_buff *oskb = NULL; 1254cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 12551da177e4SLinus Torvalds struct tcphdr *th; 1256a7a25630SEric Dumazet u64 prior_wstamp; 12571da177e4SLinus Torvalds int err; 12581da177e4SLinus Torvalds 1259dfb4b9dcSDavid S. Miller BUG_ON(!skb || !tcp_skb_pcount(skb)); 12606f094b9eSLawrence Brakmo tp = tcp_sk(sk); 12617f12422cSYuchung Cheng prior_wstamp = tp->tcp_wstamp_ns; 12627f12422cSYuchung Cheng tp->tcp_wstamp_ns = max(tp->tcp_wstamp_ns, tp->tcp_clock_cache); 1263a1ac9c8aSMartin KaFai Lau skb_set_delivery_time(skb, tp->tcp_wstamp_ns, true); 1264ccdbb6e9SEric Dumazet if (clone_it) { 12658c72c65bSEric Dumazet oskb = skb; 1266e2080072SEric Dumazet 1267e2080072SEric Dumazet tcp_skb_tsorted_save(oskb) { 1268e2080072SEric Dumazet if (unlikely(skb_cloned(oskb))) 1269e2080072SEric Dumazet skb = pskb_copy(oskb, gfp_mask); 1270dfb4b9dcSDavid S. Miller else 1271e2080072SEric Dumazet skb = skb_clone(oskb, gfp_mask); 1272e2080072SEric Dumazet } tcp_skb_tsorted_restore(oskb); 1273e2080072SEric Dumazet 1274dfb4b9dcSDavid S. Miller if (unlikely(!skb)) 1275dfb4b9dcSDavid S. Miller return -ENOBUFS; 1276b738a185SEric Dumazet /* retransmit skbs might have a non zero value in skb->dev 1277b738a185SEric Dumazet * because skb->dev is aliased with skb->rbnode.rb_left 1278b738a185SEric Dumazet */ 1279b738a185SEric Dumazet skb->dev = NULL; 1280dfb4b9dcSDavid S. Miller } 12815f6188a8SEric Dumazet 1282dfb4b9dcSDavid S. Miller inet = inet_sk(sk); 1283dfb4b9dcSDavid S. Miller tcb = TCP_SKB_CB(skb); 128433ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 12851da177e4SLinus Torvalds 1286051ba674SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) { 128733ad798cSAdam Langley tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); 1288051ba674SEric Dumazet } else { 128933ad798cSAdam Langley tcp_options_size = tcp_established_options(sk, skb, &opts, 129033ad798cSAdam Langley &md5); 1291051ba674SEric Dumazet /* Force a PSH flag on all (GSO) packets to expedite GRO flush 1292051ba674SEric Dumazet * at receiver : This slightly improve GRO performance. 1293051ba674SEric Dumazet * Note that we do not force the PSH flag for non GSO packets, 1294051ba674SEric Dumazet * because they might be sent under high congestion events, 1295051ba674SEric Dumazet * and in this case it is better to delay the delivery of 1-MSS 1296051ba674SEric Dumazet * packets and thus the corresponding ACK packet that would 1297051ba674SEric Dumazet * release the following packet. 1298051ba674SEric Dumazet */ 1299051ba674SEric Dumazet if (tcp_skb_pcount(skb) > 1) 1300051ba674SEric Dumazet tcb->tcp_flags |= TCPHDR_PSH; 1301051ba674SEric Dumazet } 130233ad798cSAdam Langley tcp_header_size = tcp_options_size + sizeof(struct tcphdr); 13031da177e4SLinus Torvalds 1304*726e9e8bSEric Dumazet /* We set skb->ooo_okay to one if this packet can select 1305*726e9e8bSEric Dumazet * a different TX queue than prior packets of this flow, 1306*726e9e8bSEric Dumazet * to avoid self inflicted reorders. 1307*726e9e8bSEric Dumazet * The 'other' queue decision is based on current cpu number 1308*726e9e8bSEric Dumazet * if XPS is enabled, or sk->sk_txhash otherwise. 1309*726e9e8bSEric Dumazet * We can switch to another (and better) queue if: 1310*726e9e8bSEric Dumazet * 1) No packet with payload is in qdisc/device queues. 1311*726e9e8bSEric Dumazet * Delays in TX completion can defeat the test 1312*726e9e8bSEric Dumazet * even if packets were already sent. 1313*726e9e8bSEric Dumazet * 2) Or rtx queue is empty. 1314*726e9e8bSEric Dumazet * This mitigates above case if ACK packets for 1315*726e9e8bSEric Dumazet * all prior packets were already processed. 1316547669d4SEric Dumazet */ 1317*726e9e8bSEric Dumazet skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1) || 1318*726e9e8bSEric Dumazet tcp_rtx_queue_empty(sk); 13191da177e4SLinus Torvalds 132038ab52e8SEric Dumazet /* If we had to use memory reserve to allocate this skb, 132138ab52e8SEric Dumazet * this might cause drops if packet is looped back : 132238ab52e8SEric Dumazet * Other socket might not have SOCK_MEMALLOC. 132338ab52e8SEric Dumazet * Packets not looped back do not care about pfmemalloc. 132438ab52e8SEric Dumazet */ 132538ab52e8SEric Dumazet skb->pfmemalloc = 0; 132638ab52e8SEric Dumazet 1327aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 1328aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 132946d3ceabSEric Dumazet 133046d3ceabSEric Dumazet skb_orphan(skb); 133146d3ceabSEric Dumazet skb->sk = sk; 13321d2077acSEric Dumazet skb->destructor = skb_is_tcp_pure_ack(skb) ? __sock_wfree : tcp_wfree; 133314afee4bSReshetova, Elena refcount_add(skb->truesize, &sk->sk_wmem_alloc); 13341da177e4SLinus Torvalds 1335c3a2e837SJulian Anastasov skb_set_dst_pending_confirm(skb, sk->sk_dst_pending_confirm); 1336c3a2e837SJulian Anastasov 13371da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 1338ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 1339c720c7e8SEric Dumazet th->source = inet->inet_sport; 1340c720c7e8SEric Dumazet th->dest = inet->inet_dport; 13411da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 13422987babbSYuchung Cheng th->ack_seq = htonl(rcv_nxt); 1343df7a3b07SAl Viro *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | 13444de075e0SEric Dumazet tcb->tcp_flags); 1345dfb4b9dcSDavid S. Miller 13461da177e4SLinus Torvalds th->check = 0; 13471da177e4SLinus Torvalds th->urg_ptr = 0; 13481da177e4SLinus Torvalds 134933f5f57eSIlpo Järvinen /* The urg_mode check is necessary during a below snd_una win probe */ 13507691367dSHerbert Xu if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { 13517691367dSHerbert Xu if (before(tp->snd_up, tcb->seq + 0x10000)) { 13521da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up - tcb->seq); 13531da177e4SLinus Torvalds th->urg = 1; 13547691367dSHerbert Xu } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { 13550eae88f3SEric Dumazet th->urg_ptr = htons(0xFFFF); 13567691367dSHerbert Xu th->urg = 1; 13577691367dSHerbert Xu } 13581da177e4SLinus Torvalds } 13591da177e4SLinus Torvalds 136051466a75SEric Dumazet skb_shinfo(skb)->gso_type = sk->sk_gso_type; 1361ea1627c2SEric Dumazet if (likely(!(tcb->tcp_flags & TCPHDR_SYN))) { 1362ea1627c2SEric Dumazet th->window = htons(tcp_select_window(sk)); 1363ea1627c2SEric Dumazet tcp_ecn_send(sk, skb, th, tcp_header_size); 1364ea1627c2SEric Dumazet } else { 1365ea1627c2SEric Dumazet /* RFC1323: The window in SYN & SYN/ACK segments 1366ea1627c2SEric Dumazet * is never scaled. 1367ea1627c2SEric Dumazet */ 1368ea1627c2SEric Dumazet th->window = htons(min(tp->rcv_wnd, 65535U)); 1369ea1627c2SEric Dumazet } 1370fa3fe2b1SFlorian Westphal 1371ea66758cSPaolo Abeni tcp_options_write(th, tp, &opts); 1372fa3fe2b1SFlorian Westphal 1373cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 1374cfb6eeb4SYOSHIFUJI Hideaki /* Calculate the MD5 hash, as we have all we need now */ 1375cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 1376aba54656SEric Dumazet sk_gso_disable(sk); 1377bd0388aeSWilliam Allen Simpson tp->af_specific->calc_md5_hash(opts.hash_location, 137839f8e58eSEric Dumazet md5, sk, skb); 1379cfb6eeb4SYOSHIFUJI Hideaki } 1380cfb6eeb4SYOSHIFUJI Hideaki #endif 1381cfb6eeb4SYOSHIFUJI Hideaki 1382331fca43SMartin KaFai Lau /* BPF prog is the last one writing header option */ 1383331fca43SMartin KaFai Lau bpf_skops_write_hdr_opt(sk, skb, NULL, NULL, 0, &opts); 1384331fca43SMartin KaFai Lau 1385dd2e0b86SEric Dumazet INDIRECT_CALL_INET(icsk->icsk_af_ops->send_check, 1386dd2e0b86SEric Dumazet tcp_v6_send_check, tcp_v4_send_check, 1387dd2e0b86SEric Dumazet sk, skb); 13881da177e4SLinus Torvalds 13894de075e0SEric Dumazet if (likely(tcb->tcp_flags & TCPHDR_ACK)) 139027cde44aSYuchung Cheng tcp_event_ack_sent(sk, tcp_skb_pcount(skb), rcv_nxt); 13911da177e4SLinus Torvalds 1392a44d6eacSMartin KaFai Lau if (skb->len != tcp_header_size) { 1393cf533ea5SEric Dumazet tcp_event_data_sent(tp, sk); 1394a44d6eacSMartin KaFai Lau tp->data_segs_out += tcp_skb_pcount(skb); 1395ba113c3aSWei Wang tp->bytes_sent += skb->len - tcp_header_size; 1396a44d6eacSMartin KaFai Lau } 13971da177e4SLinus Torvalds 1398bd37a088SWei Yongjun if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) 1399aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, 1400aa2ea058STom Herbert tcp_skb_pcount(skb)); 14011da177e4SLinus Torvalds 14022efd055cSMarcelo Ricardo Leitner tp->segs_out += tcp_skb_pcount(skb); 14030ae5b43dSYuchung Cheng skb_set_hash_from_sk(skb, sk); 1404f69ad292SEric Dumazet /* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */ 1405cd7d8498SEric Dumazet skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); 1406f69ad292SEric Dumazet skb_shinfo(skb)->gso_size = tcp_skb_mss(skb); 1407cd7d8498SEric Dumazet 1408d3edd06eSEric Dumazet /* Leave earliest departure time in skb->tstamp (skb->skb_mstamp_ns) */ 1409971f10ecSEric Dumazet 1410971f10ecSEric Dumazet /* Cleanup our debris for IP stacks */ 1411971f10ecSEric Dumazet memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), 1412971f10ecSEric Dumazet sizeof(struct inet6_skb_parm))); 1413971f10ecSEric Dumazet 1414a842fe14SEric Dumazet tcp_add_tx_delay(skb, tp); 1415a842fe14SEric Dumazet 141605e22e83SEric Dumazet err = INDIRECT_CALL_INET(icsk->icsk_af_ops->queue_xmit, 141705e22e83SEric Dumazet inet6_csk_xmit, ip_queue_xmit, 141805e22e83SEric Dumazet sk, skb, &inet->cork.fl); 14197faee5c0SEric Dumazet 14208c72c65bSEric Dumazet if (unlikely(err > 0)) { 14215ee2c941SChristoph Paasch tcp_enter_cwr(sk); 14228c72c65bSEric Dumazet err = net_xmit_eval(err); 14238c72c65bSEric Dumazet } 1424fc225799SEric Dumazet if (!err && oskb) { 1425a7a25630SEric Dumazet tcp_update_skb_after_send(sk, oskb, prior_wstamp); 1426fc225799SEric Dumazet tcp_rate_skb_sent(sk, oskb); 1427fc225799SEric Dumazet } 14288c72c65bSEric Dumazet return err; 14291da177e4SLinus Torvalds } 14301da177e4SLinus Torvalds 14312987babbSYuchung Cheng static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 14322987babbSYuchung Cheng gfp_t gfp_mask) 14332987babbSYuchung Cheng { 14342987babbSYuchung Cheng return __tcp_transmit_skb(sk, skb, clone_it, gfp_mask, 14352987babbSYuchung Cheng tcp_sk(sk)->rcv_nxt); 14362987babbSYuchung Cheng } 14372987babbSYuchung Cheng 143867edfef7SAndi Kleen /* This routine just queues the buffer for sending. 14391da177e4SLinus Torvalds * 14401da177e4SLinus Torvalds * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, 14411da177e4SLinus Torvalds * otherwise socket can stall. 14421da177e4SLinus Torvalds */ 14431da177e4SLinus Torvalds static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 14441da177e4SLinus Torvalds { 14451da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 14461da177e4SLinus Torvalds 14471da177e4SLinus Torvalds /* Advance write_seq and place onto the write_queue. */ 14480f317464SEric Dumazet WRITE_ONCE(tp->write_seq, TCP_SKB_CB(skb)->end_seq); 1449f4a775d1SEric Dumazet __skb_header_release(skb); 1450fe067e8aSDavid S. Miller tcp_add_write_queue_tail(sk, skb); 1451ab4e846aSEric Dumazet sk_wmem_queued_add(sk, skb->truesize); 14523ab224beSHideo Aoki sk_mem_charge(sk, skb->truesize); 14531da177e4SLinus Torvalds } 14541da177e4SLinus Torvalds 145567edfef7SAndi Kleen /* Initialize TSO segments for a packet. */ 14565bbb432cSEric Dumazet static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now) 1457f6302d1dSDavid S. Miller { 14584a64fd6cSEric Dumazet if (skb->len <= mss_now) { 1459f6302d1dSDavid S. Miller /* Avoid the costly divide in the normal 1460f6302d1dSDavid S. Miller * non-TSO case. 1461f6302d1dSDavid S. Miller */ 1462cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, 1); 1463f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = 0; 1464f6302d1dSDavid S. Miller } else { 1465cd7d8498SEric Dumazet tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); 1466f69ad292SEric Dumazet TCP_SKB_CB(skb)->tcp_gso_size = mss_now; 14671da177e4SLinus Torvalds } 14681da177e4SLinus Torvalds } 14691da177e4SLinus Torvalds 1470797108d1SIlpo Järvinen /* Pcount in the middle of the write queue got changed, we need to do various 1471797108d1SIlpo Järvinen * tweaks to fix counters 1472797108d1SIlpo Järvinen */ 1473cf533ea5SEric Dumazet static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) 1474797108d1SIlpo Järvinen { 1475797108d1SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1476797108d1SIlpo Järvinen 1477797108d1SIlpo Järvinen tp->packets_out -= decr; 1478797108d1SIlpo Järvinen 1479797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 1480797108d1SIlpo Järvinen tp->sacked_out -= decr; 1481797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) 1482797108d1SIlpo Järvinen tp->retrans_out -= decr; 1483797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) 1484797108d1SIlpo Järvinen tp->lost_out -= decr; 1485797108d1SIlpo Järvinen 1486797108d1SIlpo Järvinen /* Reno case is special. Sigh... */ 1487797108d1SIlpo Järvinen if (tcp_is_reno(tp) && decr > 0) 1488797108d1SIlpo Järvinen tp->sacked_out -= min_t(u32, tp->sacked_out, decr); 1489797108d1SIlpo Järvinen 1490797108d1SIlpo Järvinen if (tp->lost_skb_hint && 1491797108d1SIlpo Järvinen before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && 1492713bafeaSYuchung Cheng (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) 1493797108d1SIlpo Järvinen tp->lost_cnt_hint -= decr; 1494797108d1SIlpo Järvinen 1495797108d1SIlpo Järvinen tcp_verify_left_out(tp); 1496797108d1SIlpo Järvinen } 1497797108d1SIlpo Järvinen 14980a2cf20cSSoheil Hassas Yeganeh static bool tcp_has_tx_tstamp(const struct sk_buff *skb) 14990a2cf20cSSoheil Hassas Yeganeh { 15000a2cf20cSSoheil Hassas Yeganeh return TCP_SKB_CB(skb)->txstamp_ack || 15010a2cf20cSSoheil Hassas Yeganeh (skb_shinfo(skb)->tx_flags & SKBTX_ANY_TSTAMP); 15020a2cf20cSSoheil Hassas Yeganeh } 15030a2cf20cSSoheil Hassas Yeganeh 1504490cc7d0SWillem de Bruijn static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) 1505490cc7d0SWillem de Bruijn { 1506490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo = skb_shinfo(skb); 1507490cc7d0SWillem de Bruijn 15080a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(skb)) && 1509490cc7d0SWillem de Bruijn !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { 1510490cc7d0SWillem de Bruijn struct skb_shared_info *shinfo2 = skb_shinfo(skb2); 1511490cc7d0SWillem de Bruijn u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; 1512490cc7d0SWillem de Bruijn 1513490cc7d0SWillem de Bruijn shinfo->tx_flags &= ~tsflags; 1514490cc7d0SWillem de Bruijn shinfo2->tx_flags |= tsflags; 1515490cc7d0SWillem de Bruijn swap(shinfo->tskey, shinfo2->tskey); 1516b51e13faSMartin KaFai Lau TCP_SKB_CB(skb2)->txstamp_ack = TCP_SKB_CB(skb)->txstamp_ack; 1517b51e13faSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack = 0; 1518490cc7d0SWillem de Bruijn } 1519490cc7d0SWillem de Bruijn } 1520490cc7d0SWillem de Bruijn 1521a166140eSMartin KaFai Lau static void tcp_skb_fragment_eor(struct sk_buff *skb, struct sk_buff *skb2) 1522a166140eSMartin KaFai Lau { 1523a166140eSMartin KaFai Lau TCP_SKB_CB(skb2)->eor = TCP_SKB_CB(skb)->eor; 1524a166140eSMartin KaFai Lau TCP_SKB_CB(skb)->eor = 0; 1525a166140eSMartin KaFai Lau } 1526a166140eSMartin KaFai Lau 152775c119afSEric Dumazet /* Insert buff after skb on the write or rtx queue of sk. */ 152875c119afSEric Dumazet static void tcp_insert_write_queue_after(struct sk_buff *skb, 152975c119afSEric Dumazet struct sk_buff *buff, 153075c119afSEric Dumazet struct sock *sk, 153175c119afSEric Dumazet enum tcp_queue tcp_queue) 153275c119afSEric Dumazet { 153375c119afSEric Dumazet if (tcp_queue == TCP_FRAG_IN_WRITE_QUEUE) 153475c119afSEric Dumazet __skb_queue_after(&sk->sk_write_queue, skb, buff); 153575c119afSEric Dumazet else 153675c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, buff); 153775c119afSEric Dumazet } 153875c119afSEric Dumazet 15391da177e4SLinus Torvalds /* Function to create two new TCP segments. Shrinks the given segment 15401da177e4SLinus Torvalds * to the specified size and appends a new segment with the rest of the 15411da177e4SLinus Torvalds * packet to the list. This won't be called frequently, I hope. 15421da177e4SLinus Torvalds * Remember, these are still headerless SKBs at this point. 15431da177e4SLinus Torvalds */ 154475c119afSEric Dumazet int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, 154575c119afSEric Dumazet struct sk_buff *skb, u32 len, 15466cc55e09SOctavian Purdila unsigned int mss_now, gfp_t gfp) 15471da177e4SLinus Torvalds { 15481da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 15491da177e4SLinus Torvalds struct sk_buff *buff; 1550b4a24397SEric Dumazet int old_factor; 1551b617158dSEric Dumazet long limit; 1552b60b49eaSHerbert Xu int nlen; 15539ce01461SIlpo Järvinen u8 flags; 15541da177e4SLinus Torvalds 15552fceec13SIlpo Järvinen if (WARN_ON(len > skb->len)) 15562fceec13SIlpo Järvinen return -EINVAL; 15576a438bbeSStephen Hemminger 1558b4a24397SEric Dumazet DEBUG_NET_WARN_ON_ONCE(skb_headlen(skb)); 15591da177e4SLinus Torvalds 1560b617158dSEric Dumazet /* tcp_sendmsg() can overshoot sk_wmem_queued by one full size skb. 1561b617158dSEric Dumazet * We need some allowance to not penalize applications setting small 1562b617158dSEric Dumazet * SO_SNDBUF values. 1563b617158dSEric Dumazet * Also allow first and last skb in retransmit queue to be split. 1564b617158dSEric Dumazet */ 15657c4e983cSAlexander Duyck limit = sk->sk_sndbuf + 2 * SKB_TRUESIZE(GSO_LEGACY_MAX_SIZE); 1566b617158dSEric Dumazet if (unlikely((sk->sk_wmem_queued >> 1) > limit && 1567b617158dSEric Dumazet tcp_queue != TCP_FRAG_IN_WRITE_QUEUE && 1568b617158dSEric Dumazet skb != tcp_rtx_queue_head(sk) && 1569b617158dSEric Dumazet skb != tcp_rtx_queue_tail(sk))) { 1570f070ef2aSEric Dumazet NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPWQUEUETOOBIG); 1571f070ef2aSEric Dumazet return -ENOMEM; 1572f070ef2aSEric Dumazet } 1573f070ef2aSEric Dumazet 1574c4777efaSEric Dumazet if (skb_unclone_keeptruesize(skb, gfp)) 15751da177e4SLinus Torvalds return -ENOMEM; 15761da177e4SLinus Torvalds 15771da177e4SLinus Torvalds /* Get a new skb... force flag on. */ 15785882efffSEric Dumazet buff = tcp_stream_alloc_skb(sk, gfp, true); 157951456b29SIan Morris if (!buff) 15801da177e4SLinus Torvalds return -ENOMEM; /* We'll just try again later. */ 158141477662SJakub Kicinski skb_copy_decrypted(buff, skb); 15825a369ca6SPaolo Abeni mptcp_skb_ext_copy(buff, skb); 1583ef5cb973SHerbert Xu 1584ab4e846aSEric Dumazet sk_wmem_queued_add(sk, buff->truesize); 15853ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1586b4a24397SEric Dumazet nlen = skb->len - len; 1587b60b49eaSHerbert Xu buff->truesize += nlen; 1588b60b49eaSHerbert Xu skb->truesize -= nlen; 15891da177e4SLinus Torvalds 15901da177e4SLinus Torvalds /* Correct the sequence numbers. */ 15911da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 15921da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 15931da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 15941da177e4SLinus Torvalds 15951da177e4SLinus Torvalds /* PSH and FIN should only be set in the second packet. */ 15964de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 15974de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 15984de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1599e14c3cafSHerbert Xu TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; 1600a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 16011da177e4SLinus Torvalds 16021da177e4SLinus Torvalds skb_split(skb, buff, len); 16031da177e4SLinus Torvalds 1604a1ac9c8aSMartin KaFai Lau skb_set_delivery_time(buff, skb->tstamp, true); 1605490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 16061da177e4SLinus Torvalds 16076475be16SDavid S. Miller old_factor = tcp_skb_pcount(skb); 16086475be16SDavid S. Miller 16091da177e4SLinus Torvalds /* Fix up tso_factor for both original and new SKB. */ 16105bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 16115bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 16121da177e4SLinus Torvalds 1613b9f64820SYuchung Cheng /* Update delivered info for the new segment */ 1614b9f64820SYuchung Cheng TCP_SKB_CB(buff)->tx = TCP_SKB_CB(skb)->tx; 1615b9f64820SYuchung Cheng 16166475be16SDavid S. Miller /* If this packet has been sent out already, we must 16176475be16SDavid S. Miller * adjust the various packet counters. 16186475be16SDavid S. Miller */ 1619cf0b450cSHerbert Xu if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { 16206475be16SDavid S. Miller int diff = old_factor - tcp_skb_pcount(skb) - 16216475be16SDavid S. Miller tcp_skb_pcount(buff); 16221da177e4SLinus Torvalds 1623797108d1SIlpo Järvinen if (diff) 1624797108d1SIlpo Järvinen tcp_adjust_pcount(sk, skb, diff); 16251da177e4SLinus Torvalds } 16261da177e4SLinus Torvalds 16271da177e4SLinus Torvalds /* Link BUFF into the send queue. */ 1628f4a775d1SEric Dumazet __skb_header_release(buff); 162975c119afSEric Dumazet tcp_insert_write_queue_after(skb, buff, sk, tcp_queue); 1630f67971e6SEric Dumazet if (tcp_queue == TCP_FRAG_IN_RTX_QUEUE) 1631e2080072SEric Dumazet list_add(&buff->tcp_tsorted_anchor, &skb->tcp_tsorted_anchor); 16321da177e4SLinus Torvalds 16331da177e4SLinus Torvalds return 0; 16341da177e4SLinus Torvalds } 16351da177e4SLinus Torvalds 1636f4d01666SEric Dumazet /* This is similar to __pskb_pull_tail(). The difference is that pulled 1637f4d01666SEric Dumazet * data is not copied, but immediately discarded. 16381da177e4SLinus Torvalds */ 16397162fb24SEric Dumazet static int __pskb_trim_head(struct sk_buff *skb, int len) 16401da177e4SLinus Torvalds { 16417b7fc97aSEric Dumazet struct skb_shared_info *shinfo; 16421da177e4SLinus Torvalds int i, k, eat; 16431da177e4SLinus Torvalds 1644b4a24397SEric Dumazet DEBUG_NET_WARN_ON_ONCE(skb_headlen(skb)); 16451da177e4SLinus Torvalds eat = len; 16461da177e4SLinus Torvalds k = 0; 16477b7fc97aSEric Dumazet shinfo = skb_shinfo(skb); 16487b7fc97aSEric Dumazet for (i = 0; i < shinfo->nr_frags; i++) { 16497b7fc97aSEric Dumazet int size = skb_frag_size(&shinfo->frags[i]); 16509e903e08SEric Dumazet 16519e903e08SEric Dumazet if (size <= eat) { 1652aff65da0SIan Campbell skb_frag_unref(skb, i); 16539e903e08SEric Dumazet eat -= size; 16541da177e4SLinus Torvalds } else { 16557b7fc97aSEric Dumazet shinfo->frags[k] = shinfo->frags[i]; 16561da177e4SLinus Torvalds if (eat) { 1657b54c9d5bSJonathan Lemon skb_frag_off_add(&shinfo->frags[k], eat); 16587b7fc97aSEric Dumazet skb_frag_size_sub(&shinfo->frags[k], eat); 16591da177e4SLinus Torvalds eat = 0; 16601da177e4SLinus Torvalds } 16611da177e4SLinus Torvalds k++; 16621da177e4SLinus Torvalds } 16631da177e4SLinus Torvalds } 16647b7fc97aSEric Dumazet shinfo->nr_frags = k; 16651da177e4SLinus Torvalds 16661da177e4SLinus Torvalds skb->data_len -= len; 16671da177e4SLinus Torvalds skb->len = skb->data_len; 16687162fb24SEric Dumazet return len; 16691da177e4SLinus Torvalds } 16701da177e4SLinus Torvalds 167167edfef7SAndi Kleen /* Remove acked data from a packet in the transmit queue. */ 16721da177e4SLinus Torvalds int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 16731da177e4SLinus Torvalds { 16747162fb24SEric Dumazet u32 delta_truesize; 16757162fb24SEric Dumazet 1676c4777efaSEric Dumazet if (skb_unclone_keeptruesize(skb, GFP_ATOMIC)) 16771da177e4SLinus Torvalds return -ENOMEM; 16781da177e4SLinus Torvalds 16797162fb24SEric Dumazet delta_truesize = __pskb_trim_head(skb, len); 16801da177e4SLinus Torvalds 16811da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq += len; 16821da177e4SLinus Torvalds 16837162fb24SEric Dumazet skb->truesize -= delta_truesize; 1684ab4e846aSEric Dumazet sk_wmem_queued_add(sk, -delta_truesize); 16859b65b17dSTalal Ahmad if (!skb_zcopy_pure(skb)) 16867162fb24SEric Dumazet sk_mem_uncharge(sk, delta_truesize); 16871da177e4SLinus Torvalds 16885b35e1e6SNeal Cardwell /* Any change of skb->len requires recalculation of tso factor. */ 16891da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 16905bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb)); 16911da177e4SLinus Torvalds 16921da177e4SLinus Torvalds return 0; 16931da177e4SLinus Torvalds } 16941da177e4SLinus Torvalds 16951b63edd6SYuchung Cheng /* Calculate MSS not accounting any TCP options. */ 16961b63edd6SYuchung Cheng static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) 16975d424d5aSJohn Heffner { 1698cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1699cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 17005d424d5aSJohn Heffner int mss_now; 17015d424d5aSJohn Heffner 17025d424d5aSJohn Heffner /* Calculate base mss without TCP options: 17035d424d5aSJohn Heffner It is MMS_S - sizeof(tcphdr) of rfc1122 17045d424d5aSJohn Heffner */ 17055d424d5aSJohn Heffner mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); 17065d424d5aSJohn Heffner 170767469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 170867469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 170967469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 171067469601SEric Dumazet 171167469601SEric Dumazet if (dst && dst_allfrag(dst)) 171267469601SEric Dumazet mss_now -= icsk->icsk_af_ops->net_frag_header_len; 171367469601SEric Dumazet } 171467469601SEric Dumazet 17155d424d5aSJohn Heffner /* Clamp it (mss_clamp does not include tcp options) */ 17165d424d5aSJohn Heffner if (mss_now > tp->rx_opt.mss_clamp) 17175d424d5aSJohn Heffner mss_now = tp->rx_opt.mss_clamp; 17185d424d5aSJohn Heffner 17195d424d5aSJohn Heffner /* Now subtract optional transport overhead */ 17205d424d5aSJohn Heffner mss_now -= icsk->icsk_ext_hdr_len; 17215d424d5aSJohn Heffner 17225d424d5aSJohn Heffner /* Then reserve room for full set of TCP options and 8 bytes of data */ 172378eb166cSKuniyuki Iwashima mss_now = max(mss_now, 172478eb166cSKuniyuki Iwashima READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_snd_mss)); 17255d424d5aSJohn Heffner return mss_now; 17265d424d5aSJohn Heffner } 17275d424d5aSJohn Heffner 17281b63edd6SYuchung Cheng /* Calculate MSS. Not accounting for SACKs here. */ 17291b63edd6SYuchung Cheng int tcp_mtu_to_mss(struct sock *sk, int pmtu) 17301b63edd6SYuchung Cheng { 17311b63edd6SYuchung Cheng /* Subtract TCP options size, not including SACKs */ 17321b63edd6SYuchung Cheng return __tcp_mtu_to_mss(sk, pmtu) - 17331b63edd6SYuchung Cheng (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); 17341b63edd6SYuchung Cheng } 1735c7bb4b89SEric Dumazet EXPORT_SYMBOL(tcp_mtu_to_mss); 17361b63edd6SYuchung Cheng 17375d424d5aSJohn Heffner /* Inverse of above */ 173867469601SEric Dumazet int tcp_mss_to_mtu(struct sock *sk, int mss) 17395d424d5aSJohn Heffner { 1740cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1741cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 17425d424d5aSJohn Heffner int mtu; 17435d424d5aSJohn Heffner 17445d424d5aSJohn Heffner mtu = mss + 17455d424d5aSJohn Heffner tp->tcp_header_len + 17465d424d5aSJohn Heffner icsk->icsk_ext_hdr_len + 17475d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 17485d424d5aSJohn Heffner 174967469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 175067469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 175167469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 175267469601SEric Dumazet 175367469601SEric Dumazet if (dst && dst_allfrag(dst)) 175467469601SEric Dumazet mtu += icsk->icsk_af_ops->net_frag_header_len; 175567469601SEric Dumazet } 17565d424d5aSJohn Heffner return mtu; 17575d424d5aSJohn Heffner } 1758556c6b46SNeal Cardwell EXPORT_SYMBOL(tcp_mss_to_mtu); 17595d424d5aSJohn Heffner 176067edfef7SAndi Kleen /* MTU probing init per socket */ 17615d424d5aSJohn Heffner void tcp_mtup_init(struct sock *sk) 17625d424d5aSJohn Heffner { 17635d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 17645d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 1765b0f9ca53SFan Du struct net *net = sock_net(sk); 17665d424d5aSJohn Heffner 1767f47d00e0SKuniyuki Iwashima icsk->icsk_mtup.enabled = READ_ONCE(net->ipv4.sysctl_tcp_mtu_probing) > 1; 17685d424d5aSJohn Heffner icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + 17695d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 177088d78bc0SKuniyuki Iwashima icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, READ_ONCE(net->ipv4.sysctl_tcp_base_mss)); 17715d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 177205cbc0dbSFan Du if (icsk->icsk_mtup.enabled) 1773c74df29aSEric Dumazet icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; 17745d424d5aSJohn Heffner } 17754bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_mtup_init); 17765d424d5aSJohn Heffner 17771da177e4SLinus Torvalds /* This function synchronize snd mss to current pmtu/exthdr set. 17781da177e4SLinus Torvalds 17791da177e4SLinus Torvalds tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts 17801da177e4SLinus Torvalds for TCP options, but includes only bare TCP header. 17811da177e4SLinus Torvalds 17821da177e4SLinus Torvalds tp->rx_opt.mss_clamp is mss negotiated at connection setup. 1783caa20d9aSStephen Hemminger It is minimum of user_mss and mss received with SYN. 17841da177e4SLinus Torvalds It also does not include TCP options. 17851da177e4SLinus Torvalds 1786d83d8461SArnaldo Carvalho de Melo inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. 17871da177e4SLinus Torvalds 17881da177e4SLinus Torvalds tp->mss_cache is current effective sending mss, including 17891da177e4SLinus Torvalds all tcp options except for SACKs. It is evaluated, 17901da177e4SLinus Torvalds taking into account current pmtu, but never exceeds 17911da177e4SLinus Torvalds tp->rx_opt.mss_clamp. 17921da177e4SLinus Torvalds 17931da177e4SLinus Torvalds NOTE1. rfc1122 clearly states that advertised MSS 17941da177e4SLinus Torvalds DOES NOT include either tcp or ip options. 17951da177e4SLinus Torvalds 1796d83d8461SArnaldo Carvalho de Melo NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache 1797d83d8461SArnaldo Carvalho de Melo are READ ONLY outside this function. --ANK (980731) 17981da177e4SLinus Torvalds */ 17991da177e4SLinus Torvalds unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 18001da177e4SLinus Torvalds { 18011da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1802d83d8461SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 18035d424d5aSJohn Heffner int mss_now; 18041da177e4SLinus Torvalds 18055d424d5aSJohn Heffner if (icsk->icsk_mtup.search_high > pmtu) 18065d424d5aSJohn Heffner icsk->icsk_mtup.search_high = pmtu; 18071da177e4SLinus Torvalds 18085d424d5aSJohn Heffner mss_now = tcp_mtu_to_mss(sk, pmtu); 1809409d22b4SIlpo Järvinen mss_now = tcp_bound_to_half_wnd(tp, mss_now); 18101da177e4SLinus Torvalds 18111da177e4SLinus Torvalds /* And store cached results */ 1812d83d8461SArnaldo Carvalho de Melo icsk->icsk_pmtu_cookie = pmtu; 18135d424d5aSJohn Heffner if (icsk->icsk_mtup.enabled) 18145d424d5aSJohn Heffner mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); 1815c1b4a7e6SDavid S. Miller tp->mss_cache = mss_now; 18161da177e4SLinus Torvalds 18171da177e4SLinus Torvalds return mss_now; 18181da177e4SLinus Torvalds } 18194bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_sync_mss); 18201da177e4SLinus Torvalds 18211da177e4SLinus Torvalds /* Compute the current effective MSS, taking SACKs and IP options, 18221da177e4SLinus Torvalds * and even PMTU discovery events into account. 18231da177e4SLinus Torvalds */ 18240c54b85fSIlpo Järvinen unsigned int tcp_current_mss(struct sock *sk) 18251da177e4SLinus Torvalds { 1826cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1827cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1828c1b4a7e6SDavid S. Miller u32 mss_now; 182995c96174SEric Dumazet unsigned int header_len; 183033ad798cSAdam Langley struct tcp_out_options opts; 183133ad798cSAdam Langley struct tcp_md5sig_key *md5; 18321da177e4SLinus Torvalds 1833c1b4a7e6SDavid S. Miller mss_now = tp->mss_cache; 1834c1b4a7e6SDavid S. Miller 18351da177e4SLinus Torvalds if (dst) { 18361da177e4SLinus Torvalds u32 mtu = dst_mtu(dst); 1837d83d8461SArnaldo Carvalho de Melo if (mtu != inet_csk(sk)->icsk_pmtu_cookie) 18381da177e4SLinus Torvalds mss_now = tcp_sync_mss(sk, mtu); 18391da177e4SLinus Torvalds } 18401da177e4SLinus Torvalds 184133ad798cSAdam Langley header_len = tcp_established_options(sk, NULL, &opts, &md5) + 184233ad798cSAdam Langley sizeof(struct tcphdr); 184333ad798cSAdam Langley /* The mss_cache is sized based on tp->tcp_header_len, which assumes 184433ad798cSAdam Langley * some common options. If this is an odd packet (because we have SACK 184533ad798cSAdam Langley * blocks etc) then our calculated header_len will be different, and 184633ad798cSAdam Langley * we have to adjust mss_now correspondingly */ 184733ad798cSAdam Langley if (header_len != tp->tcp_header_len) { 184833ad798cSAdam Langley int delta = (int) header_len - tp->tcp_header_len; 184933ad798cSAdam Langley mss_now -= delta; 185033ad798cSAdam Langley } 1851cfb6eeb4SYOSHIFUJI Hideaki 18521da177e4SLinus Torvalds return mss_now; 18531da177e4SLinus Torvalds } 18541da177e4SLinus Torvalds 185586fd14adSWeiping Pan /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. 185686fd14adSWeiping Pan * As additional protections, we do not touch cwnd in retransmission phases, 185786fd14adSWeiping Pan * and if application hit its sndbuf limit recently. 185886fd14adSWeiping Pan */ 185986fd14adSWeiping Pan static void tcp_cwnd_application_limited(struct sock *sk) 1860a762a980SDavid S. Miller { 18619e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1862a762a980SDavid S. Miller 186386fd14adSWeiping Pan if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && 186486fd14adSWeiping Pan sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { 186586fd14adSWeiping Pan /* Limited by application or receiver window. */ 186686fd14adSWeiping Pan u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); 186786fd14adSWeiping Pan u32 win_used = max(tp->snd_cwnd_used, init_win); 186840570375SEric Dumazet if (win_used < tcp_snd_cwnd(tp)) { 186986fd14adSWeiping Pan tp->snd_ssthresh = tcp_current_ssthresh(sk); 187040570375SEric Dumazet tcp_snd_cwnd_set(tp, (tcp_snd_cwnd(tp) + win_used) >> 1); 187186fd14adSWeiping Pan } 187286fd14adSWeiping Pan tp->snd_cwnd_used = 0; 187386fd14adSWeiping Pan } 1874c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 187586fd14adSWeiping Pan } 187686fd14adSWeiping Pan 1877ca8a2263SNeal Cardwell static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) 1878a762a980SDavid S. Miller { 18791b1fc3fdSWei Wang const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1880a762a980SDavid S. Miller struct tcp_sock *tp = tcp_sk(sk); 1881a762a980SDavid S. Miller 1882f4ce91ceSNeal Cardwell /* Track the strongest available signal of the degree to which the cwnd 1883f4ce91ceSNeal Cardwell * is fully utilized. If cwnd-limited then remember that fact for the 1884f4ce91ceSNeal Cardwell * current window. If not cwnd-limited then track the maximum number of 1885f4ce91ceSNeal Cardwell * outstanding packets in the current window. (If cwnd-limited then we 1886f4ce91ceSNeal Cardwell * chose to not update tp->max_packets_out to avoid an extra else 1887f4ce91ceSNeal Cardwell * clause with no functional impact.) 1888ca8a2263SNeal Cardwell */ 1889f4ce91ceSNeal Cardwell if (!before(tp->snd_una, tp->cwnd_usage_seq) || 1890f4ce91ceSNeal Cardwell is_cwnd_limited || 1891f4ce91ceSNeal Cardwell (!tp->is_cwnd_limited && 1892f4ce91ceSNeal Cardwell tp->packets_out > tp->max_packets_out)) { 1893ca8a2263SNeal Cardwell tp->is_cwnd_limited = is_cwnd_limited; 1894f4ce91ceSNeal Cardwell tp->max_packets_out = tp->packets_out; 1895f4ce91ceSNeal Cardwell tp->cwnd_usage_seq = tp->snd_nxt; 1896ca8a2263SNeal Cardwell } 1897e114a710SEric Dumazet 189824901551SEric Dumazet if (tcp_is_cwnd_limited(sk)) { 1899a762a980SDavid S. Miller /* Network is feed fully. */ 1900a762a980SDavid S. Miller tp->snd_cwnd_used = 0; 1901c2203cf7SEric Dumazet tp->snd_cwnd_stamp = tcp_jiffies32; 1902a762a980SDavid S. Miller } else { 1903a762a980SDavid S. Miller /* Network starves. */ 1904a762a980SDavid S. Miller if (tp->packets_out > tp->snd_cwnd_used) 1905a762a980SDavid S. Miller tp->snd_cwnd_used = tp->packets_out; 1906a762a980SDavid S. Miller 19074845b571SKuniyuki Iwashima if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) && 1908c2203cf7SEric Dumazet (s32)(tcp_jiffies32 - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto && 19091b1fc3fdSWei Wang !ca_ops->cong_control) 1910a762a980SDavid S. Miller tcp_cwnd_application_limited(sk); 1911b0f71bd3SFrancis Yan 1912b0f71bd3SFrancis Yan /* The following conditions together indicate the starvation 1913b0f71bd3SFrancis Yan * is caused by insufficient sender buffer: 1914b0f71bd3SFrancis Yan * 1) just sent some data (see tcp_write_xmit) 1915b0f71bd3SFrancis Yan * 2) not cwnd limited (this else condition) 191675c119afSEric Dumazet * 3) no more data to send (tcp_write_queue_empty()) 1917b0f71bd3SFrancis Yan * 4) application is hitting buffer limit (SOCK_NOSPACE) 1918b0f71bd3SFrancis Yan */ 191975c119afSEric Dumazet if (tcp_write_queue_empty(sk) && sk->sk_socket && 1920b0f71bd3SFrancis Yan test_bit(SOCK_NOSPACE, &sk->sk_socket->flags) && 1921b0f71bd3SFrancis Yan (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) 1922b0f71bd3SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_SNDBUF_LIMITED); 1923a762a980SDavid S. Miller } 1924a762a980SDavid S. Miller } 1925a762a980SDavid S. Miller 1926d4589926SEric Dumazet /* Minshall's variant of the Nagle send check. */ 1927d4589926SEric Dumazet static bool tcp_minshall_check(const struct tcp_sock *tp) 1928d4589926SEric Dumazet { 1929d4589926SEric Dumazet return after(tp->snd_sml, tp->snd_una) && 1930d4589926SEric Dumazet !after(tp->snd_sml, tp->snd_nxt); 1931d4589926SEric Dumazet } 1932d4589926SEric Dumazet 1933d4589926SEric Dumazet /* Update snd_sml if this skb is under mss 1934d4589926SEric Dumazet * Note that a TSO packet might end with a sub-mss segment 1935d4589926SEric Dumazet * The test is really : 1936d4589926SEric Dumazet * if ((skb->len % mss) != 0) 1937d4589926SEric Dumazet * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1938d4589926SEric Dumazet * But we can avoid doing the divide again given we already have 1939d4589926SEric Dumazet * skb_pcount = skb->len / mss_now 19400e3a4803SIlpo Järvinen */ 1941d4589926SEric Dumazet static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, 1942d4589926SEric Dumazet const struct sk_buff *skb) 1943d4589926SEric Dumazet { 1944d4589926SEric Dumazet if (skb->len < tcp_skb_pcount(skb) * mss_now) 1945d4589926SEric Dumazet tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 1946d4589926SEric Dumazet } 1947d4589926SEric Dumazet 1948d4589926SEric Dumazet /* Return false, if packet can be sent now without violation Nagle's rules: 1949d4589926SEric Dumazet * 1. It is full sized. (provided by caller in %partial bool) 1950d4589926SEric Dumazet * 2. Or it contains FIN. (already checked by caller) 1951d4589926SEric Dumazet * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. 1952d4589926SEric Dumazet * 4. Or TCP_CORK is not set, and all sent packets are ACKed. 1953d4589926SEric Dumazet * With Minshall's modification: all sent small packets are ACKed. 1954d4589926SEric Dumazet */ 1955d4589926SEric Dumazet static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, 1956cc93fc51SPeter Pan(潘卫平) int nonagle) 1957d4589926SEric Dumazet { 1958d4589926SEric Dumazet return partial && 1959d4589926SEric Dumazet ((nonagle & TCP_NAGLE_CORK) || 1960d4589926SEric Dumazet (!nonagle && tp->packets_out && tcp_minshall_check(tp))); 1961d4589926SEric Dumazet } 1962605ad7f1SEric Dumazet 1963605ad7f1SEric Dumazet /* Return how many segs we'd like on a TSO packet, 196465466904SEric Dumazet * depending on current pacing rate, and how close the peer is. 196565466904SEric Dumazet * 196665466904SEric Dumazet * Rationale is: 196765466904SEric Dumazet * - For close peers, we rather send bigger packets to reduce 196865466904SEric Dumazet * cpu costs, because occasional losses will be repaired fast. 196965466904SEric Dumazet * - For long distance/rtt flows, we would like to get ACK clocking 197065466904SEric Dumazet * with 1 ACK per ms. 197165466904SEric Dumazet * 197265466904SEric Dumazet * Use min_rtt to help adapt TSO burst size, with smaller min_rtt resulting 197365466904SEric Dumazet * in bigger TSO bursts. We we cut the RTT-based allowance in half 197465466904SEric Dumazet * for every 2^9 usec (aka 512 us) of RTT, so that the RTT-based allowance 197565466904SEric Dumazet * is below 1500 bytes after 6 * ~500 usec = 3ms. 1976605ad7f1SEric Dumazet */ 1977dcb8c9b4SEric Dumazet static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, 19781b3878caSNeal Cardwell int min_tso_segs) 1979605ad7f1SEric Dumazet { 198065466904SEric Dumazet unsigned long bytes; 198165466904SEric Dumazet u32 r; 1982605ad7f1SEric Dumazet 198365466904SEric Dumazet bytes = sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift); 1984605ad7f1SEric Dumazet 19852455e61bSKuniyuki Iwashima r = tcp_min_rtt(tcp_sk(sk)) >> READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_rtt_log); 198665466904SEric Dumazet if (r < BITS_PER_TYPE(sk->sk_gso_max_size)) 198765466904SEric Dumazet bytes += sk->sk_gso_max_size >> r; 1988605ad7f1SEric Dumazet 198965466904SEric Dumazet bytes = min_t(unsigned long, bytes, sk->sk_gso_max_size); 199065466904SEric Dumazet 199165466904SEric Dumazet return max_t(u32, bytes / mss_now, min_tso_segs); 1992605ad7f1SEric Dumazet } 1993605ad7f1SEric Dumazet 1994ed6e7268SNeal Cardwell /* Return the number of segments we want in the skb we are transmitting. 1995ed6e7268SNeal Cardwell * See if congestion control module wants to decide; otherwise, autosize. 1996ed6e7268SNeal Cardwell */ 1997ed6e7268SNeal Cardwell static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now) 1998ed6e7268SNeal Cardwell { 1999ed6e7268SNeal Cardwell const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 2000dcb8c9b4SEric Dumazet u32 min_tso, tso_segs; 2001ed6e7268SNeal Cardwell 2002dcb8c9b4SEric Dumazet min_tso = ca_ops->min_tso_segs ? 2003dcb8c9b4SEric Dumazet ca_ops->min_tso_segs(sk) : 2004e0bb4ab9SKuniyuki Iwashima READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs); 2005dcb8c9b4SEric Dumazet 2006dcb8c9b4SEric Dumazet tso_segs = tcp_tso_autosize(sk, mss_now, min_tso); 2007350c9f48SEric Dumazet return min_t(u32, tso_segs, sk->sk_gso_max_segs); 2008ed6e7268SNeal Cardwell } 2009ed6e7268SNeal Cardwell 2010d4589926SEric Dumazet /* Returns the portion of skb which can be sent right away */ 2011d4589926SEric Dumazet static unsigned int tcp_mss_split_point(const struct sock *sk, 2012d4589926SEric Dumazet const struct sk_buff *skb, 2013d4589926SEric Dumazet unsigned int mss_now, 2014d4589926SEric Dumazet unsigned int max_segs, 2015d4589926SEric Dumazet int nonagle) 2016c1b4a7e6SDavid S. Miller { 2017cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 2018d4589926SEric Dumazet u32 partial, needed, window, max_len; 2019c1b4a7e6SDavid S. Miller 202090840defSIlpo Järvinen window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 20211485348dSBen Hutchings max_len = mss_now * max_segs; 20220e3a4803SIlpo Järvinen 20231485348dSBen Hutchings if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) 20241485348dSBen Hutchings return max_len; 20250e3a4803SIlpo Järvinen 20265ea3a748SIlpo Järvinen needed = min(skb->len, window); 20275ea3a748SIlpo Järvinen 20281485348dSBen Hutchings if (max_len <= needed) 20291485348dSBen Hutchings return max_len; 20300e3a4803SIlpo Järvinen 2031d4589926SEric Dumazet partial = needed % mss_now; 2032d4589926SEric Dumazet /* If last segment is not a full MSS, check if Nagle rules allow us 2033d4589926SEric Dumazet * to include this last segment in this skb. 2034d4589926SEric Dumazet * Otherwise, we'll split the skb at last MSS boundary 2035d4589926SEric Dumazet */ 2036cc93fc51SPeter Pan(潘卫平) if (tcp_nagle_check(partial != 0, tp, nonagle)) 2037d4589926SEric Dumazet return needed - partial; 2038d4589926SEric Dumazet 2039d4589926SEric Dumazet return needed; 2040c1b4a7e6SDavid S. Miller } 2041c1b4a7e6SDavid S. Miller 2042c1b4a7e6SDavid S. Miller /* Can at least one segment of SKB be sent right now, according to the 2043c1b4a7e6SDavid S. Miller * congestion window rules? If so, return how many segments are allowed. 2044c1b4a7e6SDavid S. Miller */ 2045cf533ea5SEric Dumazet static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, 2046cf533ea5SEric Dumazet const struct sk_buff *skb) 2047c1b4a7e6SDavid S. Miller { 2048d649a7a8SEric Dumazet u32 in_flight, cwnd, halfcwnd; 2049c1b4a7e6SDavid S. Miller 2050c1b4a7e6SDavid S. Miller /* Don't be strict about the congestion window for the final FIN. */ 20514de075e0SEric Dumazet if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && 20524de075e0SEric Dumazet tcp_skb_pcount(skb) == 1) 2053c1b4a7e6SDavid S. Miller return 1; 2054c1b4a7e6SDavid S. Miller 2055c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 205640570375SEric Dumazet cwnd = tcp_snd_cwnd(tp); 2057d649a7a8SEric Dumazet if (in_flight >= cwnd) 2058c1b4a7e6SDavid S. Miller return 0; 2059d649a7a8SEric Dumazet 2060d649a7a8SEric Dumazet /* For better scheduling, ensure we have at least 2061d649a7a8SEric Dumazet * 2 GSO packets in flight. 2062d649a7a8SEric Dumazet */ 2063d649a7a8SEric Dumazet halfcwnd = max(cwnd >> 1, 1U); 2064d649a7a8SEric Dumazet return min(halfcwnd, cwnd - in_flight); 2065c1b4a7e6SDavid S. Miller } 2066c1b4a7e6SDavid S. Miller 2067b595076aSUwe Kleine-König /* Initialize TSO state of a skb. 206867edfef7SAndi Kleen * This must be invoked the first time we consider transmitting 2069c1b4a7e6SDavid S. Miller * SKB onto the wire. 2070c1b4a7e6SDavid S. Miller */ 20715bbb432cSEric Dumazet static int tcp_init_tso_segs(struct sk_buff *skb, unsigned int mss_now) 2072c1b4a7e6SDavid S. Miller { 2073c1b4a7e6SDavid S. Miller int tso_segs = tcp_skb_pcount(skb); 2074c1b4a7e6SDavid S. Miller 2075f8269a49SIlpo Järvinen if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { 20765bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 2077c1b4a7e6SDavid S. Miller tso_segs = tcp_skb_pcount(skb); 2078c1b4a7e6SDavid S. Miller } 2079c1b4a7e6SDavid S. Miller return tso_segs; 2080c1b4a7e6SDavid S. Miller } 2081c1b4a7e6SDavid S. Miller 2082c1b4a7e6SDavid S. Miller 2083a2a385d6SEric Dumazet /* Return true if the Nagle test allows this packet to be 2084c1b4a7e6SDavid S. Miller * sent now. 2085c1b4a7e6SDavid S. Miller */ 2086a2a385d6SEric Dumazet static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, 2087c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 2088c1b4a7e6SDavid S. Miller { 2089c1b4a7e6SDavid S. Miller /* Nagle rule does not apply to frames, which sit in the middle of the 2090c1b4a7e6SDavid S. Miller * write_queue (they have no chances to get new data). 2091c1b4a7e6SDavid S. Miller * 2092c1b4a7e6SDavid S. Miller * This is implemented in the callers, where they modify the 'nonagle' 2093c1b4a7e6SDavid S. Miller * argument based upon the location of SKB in the send queue. 2094c1b4a7e6SDavid S. Miller */ 2095c1b4a7e6SDavid S. Miller if (nonagle & TCP_NAGLE_PUSH) 2096a2a385d6SEric Dumazet return true; 2097c1b4a7e6SDavid S. Miller 20989b44190dSYuchung Cheng /* Don't use the nagle rule for urgent data (or for the final FIN). */ 20999b44190dSYuchung Cheng if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) 2100a2a385d6SEric Dumazet return true; 2101c1b4a7e6SDavid S. Miller 2102cc93fc51SPeter Pan(潘卫平) if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) 2103a2a385d6SEric Dumazet return true; 2104c1b4a7e6SDavid S. Miller 2105a2a385d6SEric Dumazet return false; 2106c1b4a7e6SDavid S. Miller } 2107c1b4a7e6SDavid S. Miller 2108c1b4a7e6SDavid S. Miller /* Does at least the first segment of SKB fit into the send window? */ 2109a2a385d6SEric Dumazet static bool tcp_snd_wnd_test(const struct tcp_sock *tp, 2110a2a385d6SEric Dumazet const struct sk_buff *skb, 2111056834d9SIlpo Järvinen unsigned int cur_mss) 2112c1b4a7e6SDavid S. Miller { 2113c1b4a7e6SDavid S. Miller u32 end_seq = TCP_SKB_CB(skb)->end_seq; 2114c1b4a7e6SDavid S. Miller 2115c1b4a7e6SDavid S. Miller if (skb->len > cur_mss) 2116c1b4a7e6SDavid S. Miller end_seq = TCP_SKB_CB(skb)->seq + cur_mss; 2117c1b4a7e6SDavid S. Miller 211890840defSIlpo Järvinen return !after(end_seq, tcp_wnd_end(tp)); 2119c1b4a7e6SDavid S. Miller } 2120c1b4a7e6SDavid S. Miller 2121c1b4a7e6SDavid S. Miller /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet 2122c1b4a7e6SDavid S. Miller * which is put after SKB on the list. It is very much like 2123c1b4a7e6SDavid S. Miller * tcp_fragment() except that it may make several kinds of assumptions 2124c1b4a7e6SDavid S. Miller * in order to speed up the splitting operation. In particular, we 2125c1b4a7e6SDavid S. Miller * know that all the data is in scatter-gather pages, and that the 2126c1b4a7e6SDavid S. Miller * packet has never been sent out before (and thus is not cloned). 2127c1b4a7e6SDavid S. Miller */ 212856483341SEric Dumazet static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, 2129c4ead4c5SEric Dumazet unsigned int mss_now, gfp_t gfp) 2130c1b4a7e6SDavid S. Miller { 2131c1b4a7e6SDavid S. Miller int nlen = skb->len - len; 213256483341SEric Dumazet struct sk_buff *buff; 21339ce01461SIlpo Järvinen u8 flags; 2134c1b4a7e6SDavid S. Miller 2135c1b4a7e6SDavid S. Miller /* All of a TSO frame must be composed of paged data. */ 2136b4a24397SEric Dumazet DEBUG_NET_WARN_ON_ONCE(skb->len != skb->data_len); 2137c1b4a7e6SDavid S. Miller 21385882efffSEric Dumazet buff = tcp_stream_alloc_skb(sk, gfp, true); 213951456b29SIan Morris if (unlikely(!buff)) 2140c1b4a7e6SDavid S. Miller return -ENOMEM; 214141477662SJakub Kicinski skb_copy_decrypted(buff, skb); 21425a369ca6SPaolo Abeni mptcp_skb_ext_copy(buff, skb); 2143c1b4a7e6SDavid S. Miller 2144ab4e846aSEric Dumazet sk_wmem_queued_add(sk, buff->truesize); 21453ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 2146b60b49eaSHerbert Xu buff->truesize += nlen; 2147c1b4a7e6SDavid S. Miller skb->truesize -= nlen; 2148c1b4a7e6SDavid S. Miller 2149c1b4a7e6SDavid S. Miller /* Correct the sequence numbers. */ 2150c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 2151c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 2152c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 2153c1b4a7e6SDavid S. Miller 2154c1b4a7e6SDavid S. Miller /* PSH and FIN should only be set in the second packet. */ 21554de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 21564de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 21574de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 2158c1b4a7e6SDavid S. Miller 2159a166140eSMartin KaFai Lau tcp_skb_fragment_eor(skb, buff); 2160a166140eSMartin KaFai Lau 2161c1b4a7e6SDavid S. Miller skb_split(skb, buff, len); 2162490cc7d0SWillem de Bruijn tcp_fragment_tstamp(skb, buff); 2163c1b4a7e6SDavid S. Miller 2164c1b4a7e6SDavid S. Miller /* Fix up tso_factor for both original and new SKB. */ 21655bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 21665bbb432cSEric Dumazet tcp_set_skb_tso_segs(buff, mss_now); 2167c1b4a7e6SDavid S. Miller 2168c1b4a7e6SDavid S. Miller /* Link BUFF into the send queue. */ 2169f4a775d1SEric Dumazet __skb_header_release(buff); 217056483341SEric Dumazet tcp_insert_write_queue_after(skb, buff, sk, TCP_FRAG_IN_WRITE_QUEUE); 2171c1b4a7e6SDavid S. Miller 2172c1b4a7e6SDavid S. Miller return 0; 2173c1b4a7e6SDavid S. Miller } 2174c1b4a7e6SDavid S. Miller 2175c1b4a7e6SDavid S. Miller /* Try to defer sending, if possible, in order to minimize the amount 2176c1b4a7e6SDavid S. Miller * of TSO splitting we do. View it as a kind of TSO Nagle test. 2177c1b4a7e6SDavid S. Miller * 2178c1b4a7e6SDavid S. Miller * This algorithm is from John Heffner. 2179c1b4a7e6SDavid S. Miller */ 2180ca8a2263SNeal Cardwell static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, 2181f9bfe4e6SEric Dumazet bool *is_cwnd_limited, 2182f9bfe4e6SEric Dumazet bool *is_rwnd_limited, 2183f9bfe4e6SEric Dumazet u32 max_segs) 2184c1b4a7e6SDavid S. Miller { 21856687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 2186f1c6ea38SEric Dumazet u32 send_win, cong_win, limit, in_flight; 218750c8339eSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 218850c8339eSEric Dumazet struct sk_buff *head; 2189ad9f4f50SEric Dumazet int win_divisor; 2190f1c6ea38SEric Dumazet s64 delta; 2191c1b4a7e6SDavid S. Miller 219299d7662aSEric Dumazet if (icsk->icsk_ca_state >= TCP_CA_Recovery) 2193ae8064acSJohn Heffner goto send_now; 2194ae8064acSJohn Heffner 21955f852eb5SEric Dumazet /* Avoid bursty behavior by allowing defer 2196a682850aSEric Dumazet * only if the last write was recent (1 ms). 2197a682850aSEric Dumazet * Note that tp->tcp_wstamp_ns can be in the future if we have 2198a682850aSEric Dumazet * packets waiting in a qdisc or device for EDT delivery. 21995f852eb5SEric Dumazet */ 2200a682850aSEric Dumazet delta = tp->tcp_clock_cache - tp->tcp_wstamp_ns - NSEC_PER_MSEC; 2201a682850aSEric Dumazet if (delta > 0) 2202ae8064acSJohn Heffner goto send_now; 2203908a75c1SDavid S. Miller 2204c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 2205c1b4a7e6SDavid S. Miller 2206c8c9aeb5SStefano Brivio BUG_ON(tcp_skb_pcount(skb) <= 1); 220740570375SEric Dumazet BUG_ON(tcp_snd_cwnd(tp) <= in_flight); 2208c1b4a7e6SDavid S. Miller 220990840defSIlpo Järvinen send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 2210c1b4a7e6SDavid S. Miller 2211c1b4a7e6SDavid S. Miller /* From in_flight test above, we know that cwnd > in_flight. */ 221240570375SEric Dumazet cong_win = (tcp_snd_cwnd(tp) - in_flight) * tp->mss_cache; 2213c1b4a7e6SDavid S. Miller 2214c1b4a7e6SDavid S. Miller limit = min(send_win, cong_win); 2215c1b4a7e6SDavid S. Miller 2216ba244fe9SDavid S. Miller /* If a full-sized TSO skb can be sent, do it. */ 2217605ad7f1SEric Dumazet if (limit >= max_segs * tp->mss_cache) 2218ae8064acSJohn Heffner goto send_now; 2219ba244fe9SDavid S. Miller 222062ad2761SIlpo Järvinen /* Middle in queue won't get any more data, full sendable already? */ 222162ad2761SIlpo Järvinen if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) 222262ad2761SIlpo Järvinen goto send_now; 222362ad2761SIlpo Järvinen 22245bbcc0f5SLinus Torvalds win_divisor = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_win_divisor); 2225ad9f4f50SEric Dumazet if (win_divisor) { 222640570375SEric Dumazet u32 chunk = min(tp->snd_wnd, tcp_snd_cwnd(tp) * tp->mss_cache); 2227c1b4a7e6SDavid S. Miller 2228c1b4a7e6SDavid S. Miller /* If at least some fraction of a window is available, 2229c1b4a7e6SDavid S. Miller * just use it. 2230c1b4a7e6SDavid S. Miller */ 2231ad9f4f50SEric Dumazet chunk /= win_divisor; 2232c1b4a7e6SDavid S. Miller if (limit >= chunk) 2233ae8064acSJohn Heffner goto send_now; 2234c1b4a7e6SDavid S. Miller } else { 2235c1b4a7e6SDavid S. Miller /* Different approach, try not to defer past a single 2236c1b4a7e6SDavid S. Miller * ACK. Receiver should ACK every other full sized 2237c1b4a7e6SDavid S. Miller * frame, so if we have space for more than 3 frames 2238c1b4a7e6SDavid S. Miller * then send now. 2239c1b4a7e6SDavid S. Miller */ 22406b5a5c0dSNeal Cardwell if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) 2241ae8064acSJohn Heffner goto send_now; 2242c1b4a7e6SDavid S. Miller } 2243c1b4a7e6SDavid S. Miller 224475c119afSEric Dumazet /* TODO : use tsorted_sent_queue ? */ 224575c119afSEric Dumazet head = tcp_rtx_queue_head(sk); 224675c119afSEric Dumazet if (!head) 224775c119afSEric Dumazet goto send_now; 2248f1c6ea38SEric Dumazet delta = tp->tcp_clock_cache - head->tstamp; 224950c8339eSEric Dumazet /* If next ACK is likely to come too late (half srtt), do not defer */ 2250f1c6ea38SEric Dumazet if ((s64)(delta - (u64)NSEC_PER_USEC * (tp->srtt_us >> 4)) < 0) 225150c8339eSEric Dumazet goto send_now; 225250c8339eSEric Dumazet 2253f9bfe4e6SEric Dumazet /* Ok, it looks like it is advisable to defer. 2254f9bfe4e6SEric Dumazet * Three cases are tracked : 2255f9bfe4e6SEric Dumazet * 1) We are cwnd-limited 2256f9bfe4e6SEric Dumazet * 2) We are rwnd-limited 2257f9bfe4e6SEric Dumazet * 3) We are application limited. 2258f9bfe4e6SEric Dumazet */ 2259f9bfe4e6SEric Dumazet if (cong_win < send_win) { 2260f9bfe4e6SEric Dumazet if (cong_win <= skb->len) { 2261ca8a2263SNeal Cardwell *is_cwnd_limited = true; 2262f9bfe4e6SEric Dumazet return true; 2263f9bfe4e6SEric Dumazet } 2264f9bfe4e6SEric Dumazet } else { 2265f9bfe4e6SEric Dumazet if (send_win <= skb->len) { 2266f9bfe4e6SEric Dumazet *is_rwnd_limited = true; 2267f9bfe4e6SEric Dumazet return true; 2268f9bfe4e6SEric Dumazet } 2269f9bfe4e6SEric Dumazet } 2270f9bfe4e6SEric Dumazet 2271f9bfe4e6SEric Dumazet /* If this packet won't get more data, do not wait. */ 2272d8ed257fSEric Dumazet if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) || 2273d8ed257fSEric Dumazet TCP_SKB_CB(skb)->eor) 2274f9bfe4e6SEric Dumazet goto send_now; 2275ca8a2263SNeal Cardwell 2276a2a385d6SEric Dumazet return true; 2277ae8064acSJohn Heffner 2278ae8064acSJohn Heffner send_now: 2279a2a385d6SEric Dumazet return false; 2280c1b4a7e6SDavid S. Miller } 2281c1b4a7e6SDavid S. Miller 228205cbc0dbSFan Du static inline void tcp_mtu_check_reprobe(struct sock *sk) 228305cbc0dbSFan Du { 228405cbc0dbSFan Du struct inet_connection_sock *icsk = inet_csk(sk); 228505cbc0dbSFan Du struct tcp_sock *tp = tcp_sk(sk); 228605cbc0dbSFan Du struct net *net = sock_net(sk); 228705cbc0dbSFan Du u32 interval; 228805cbc0dbSFan Du s32 delta; 228905cbc0dbSFan Du 22902a85388fSKuniyuki Iwashima interval = READ_ONCE(net->ipv4.sysctl_tcp_probe_interval); 2291c74df29aSEric Dumazet delta = tcp_jiffies32 - icsk->icsk_mtup.probe_timestamp; 229205cbc0dbSFan Du if (unlikely(delta >= interval * HZ)) { 229305cbc0dbSFan Du int mss = tcp_current_mss(sk); 229405cbc0dbSFan Du 229505cbc0dbSFan Du /* Update current search range */ 229605cbc0dbSFan Du icsk->icsk_mtup.probe_size = 0; 229705cbc0dbSFan Du icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + 229805cbc0dbSFan Du sizeof(struct tcphdr) + 229905cbc0dbSFan Du icsk->icsk_af_ops->net_header_len; 230005cbc0dbSFan Du icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); 230105cbc0dbSFan Du 230205cbc0dbSFan Du /* Update probe time stamp */ 2303c74df29aSEric Dumazet icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; 230405cbc0dbSFan Du } 230505cbc0dbSFan Du } 230605cbc0dbSFan Du 2307808cf9e3SIlya Lesokhin static bool tcp_can_coalesce_send_queue_head(struct sock *sk, int len) 2308808cf9e3SIlya Lesokhin { 2309808cf9e3SIlya Lesokhin struct sk_buff *skb, *next; 2310808cf9e3SIlya Lesokhin 2311808cf9e3SIlya Lesokhin skb = tcp_send_head(sk); 2312808cf9e3SIlya Lesokhin tcp_for_write_queue_from_safe(skb, next, sk) { 2313808cf9e3SIlya Lesokhin if (len <= skb->len) 2314808cf9e3SIlya Lesokhin break; 2315808cf9e3SIlya Lesokhin 23169b65b17dSTalal Ahmad if (unlikely(TCP_SKB_CB(skb)->eor) || 23179b65b17dSTalal Ahmad tcp_has_tx_tstamp(skb) || 23189b65b17dSTalal Ahmad !skb_pure_zcopy_same(skb, next)) 2319808cf9e3SIlya Lesokhin return false; 2320808cf9e3SIlya Lesokhin 2321808cf9e3SIlya Lesokhin len -= skb->len; 2322808cf9e3SIlya Lesokhin } 2323808cf9e3SIlya Lesokhin 2324808cf9e3SIlya Lesokhin return true; 2325808cf9e3SIlya Lesokhin } 2326808cf9e3SIlya Lesokhin 232773601329SEric Dumazet static int tcp_clone_payload(struct sock *sk, struct sk_buff *to, 232873601329SEric Dumazet int probe_size) 232973601329SEric Dumazet { 233073601329SEric Dumazet skb_frag_t *lastfrag = NULL, *fragto = skb_shinfo(to)->frags; 233173601329SEric Dumazet int i, todo, len = 0, nr_frags = 0; 233273601329SEric Dumazet const struct sk_buff *skb; 233373601329SEric Dumazet 233473601329SEric Dumazet if (!sk_wmem_schedule(sk, to->truesize + probe_size)) 233573601329SEric Dumazet return -ENOMEM; 233673601329SEric Dumazet 233773601329SEric Dumazet skb_queue_walk(&sk->sk_write_queue, skb) { 233873601329SEric Dumazet const skb_frag_t *fragfrom = skb_shinfo(skb)->frags; 233973601329SEric Dumazet 234073601329SEric Dumazet if (skb_headlen(skb)) 234173601329SEric Dumazet return -EINVAL; 234273601329SEric Dumazet 234373601329SEric Dumazet for (i = 0; i < skb_shinfo(skb)->nr_frags; i++, fragfrom++) { 234473601329SEric Dumazet if (len >= probe_size) 234573601329SEric Dumazet goto commit; 234673601329SEric Dumazet todo = min_t(int, skb_frag_size(fragfrom), 234773601329SEric Dumazet probe_size - len); 234873601329SEric Dumazet len += todo; 234973601329SEric Dumazet if (lastfrag && 235073601329SEric Dumazet skb_frag_page(fragfrom) == skb_frag_page(lastfrag) && 235173601329SEric Dumazet skb_frag_off(fragfrom) == skb_frag_off(lastfrag) + 235273601329SEric Dumazet skb_frag_size(lastfrag)) { 235373601329SEric Dumazet skb_frag_size_add(lastfrag, todo); 235473601329SEric Dumazet continue; 235573601329SEric Dumazet } 235673601329SEric Dumazet if (unlikely(nr_frags == MAX_SKB_FRAGS)) 235773601329SEric Dumazet return -E2BIG; 235873601329SEric Dumazet skb_frag_page_copy(fragto, fragfrom); 235973601329SEric Dumazet skb_frag_off_copy(fragto, fragfrom); 236073601329SEric Dumazet skb_frag_size_set(fragto, todo); 236173601329SEric Dumazet nr_frags++; 236273601329SEric Dumazet lastfrag = fragto++; 236373601329SEric Dumazet } 236473601329SEric Dumazet } 236573601329SEric Dumazet commit: 236673601329SEric Dumazet WARN_ON_ONCE(len != probe_size); 236773601329SEric Dumazet for (i = 0; i < nr_frags; i++) 236873601329SEric Dumazet skb_frag_ref(to, i); 236973601329SEric Dumazet 237073601329SEric Dumazet skb_shinfo(to)->nr_frags = nr_frags; 237173601329SEric Dumazet to->truesize += probe_size; 237273601329SEric Dumazet to->len += probe_size; 237373601329SEric Dumazet to->data_len += probe_size; 237473601329SEric Dumazet __skb_header_release(to); 237573601329SEric Dumazet return 0; 237673601329SEric Dumazet } 237773601329SEric Dumazet 23785d424d5aSJohn Heffner /* Create a new MTU probe if we are ready. 237967edfef7SAndi Kleen * MTU probe is regularly attempting to increase the path MTU by 238067edfef7SAndi Kleen * deliberately sending larger packets. This discovers routing 238167edfef7SAndi Kleen * changes resulting in larger path MTUs. 238267edfef7SAndi Kleen * 23835d424d5aSJohn Heffner * Returns 0 if we should wait to probe (no cwnd available), 23845d424d5aSJohn Heffner * 1 if a probe was sent, 2385056834d9SIlpo Järvinen * -1 otherwise 2386056834d9SIlpo Järvinen */ 23875d424d5aSJohn Heffner static int tcp_mtu_probe(struct sock *sk) 23885d424d5aSJohn Heffner { 23895d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 239012a59abcSEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 23915d424d5aSJohn Heffner struct sk_buff *skb, *nskb, *next; 23926b58e0a5SFan Du struct net *net = sock_net(sk); 23935d424d5aSJohn Heffner int probe_size; 239491cc17c0SIlpo Järvinen int size_needed; 239512a59abcSEric Dumazet int copy, len; 23965d424d5aSJohn Heffner int mss_now; 23976b58e0a5SFan Du int interval; 23985d424d5aSJohn Heffner 23995d424d5aSJohn Heffner /* Not currently probing/verifying, 24005d424d5aSJohn Heffner * not in recovery, 24015d424d5aSJohn Heffner * have enough cwnd, and 240212a59abcSEric Dumazet * not SACKing (the variable headers throw things off) 240312a59abcSEric Dumazet */ 240412a59abcSEric Dumazet if (likely(!icsk->icsk_mtup.enabled || 24055d424d5aSJohn Heffner icsk->icsk_mtup.probe_size || 24065d424d5aSJohn Heffner inet_csk(sk)->icsk_ca_state != TCP_CA_Open || 240740570375SEric Dumazet tcp_snd_cwnd(tp) < 11 || 240812a59abcSEric Dumazet tp->rx_opt.num_sacks || tp->rx_opt.dsack)) 24095d424d5aSJohn Heffner return -1; 24105d424d5aSJohn Heffner 24116b58e0a5SFan Du /* Use binary search for probe_size between tcp_mss_base, 24126b58e0a5SFan Du * and current mss_clamp. if (search_high - search_low) 24136b58e0a5SFan Du * smaller than a threshold, backoff from probing. 24146b58e0a5SFan Du */ 24150c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 24166b58e0a5SFan Du probe_size = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high + 24176b58e0a5SFan Du icsk->icsk_mtup.search_low) >> 1); 241891cc17c0SIlpo Järvinen size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; 24196b58e0a5SFan Du interval = icsk->icsk_mtup.search_high - icsk->icsk_mtup.search_low; 242005cbc0dbSFan Du /* When misfortune happens, we are reprobing actively, 242105cbc0dbSFan Du * and then reprobe timer has expired. We stick with current 242205cbc0dbSFan Du * probing process by not resetting search range to its orignal. 242305cbc0dbSFan Du */ 24246b58e0a5SFan Du if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high) || 242592c0aa41SKuniyuki Iwashima interval < READ_ONCE(net->ipv4.sysctl_tcp_probe_threshold)) { 242605cbc0dbSFan Du /* Check whether enough time has elaplased for 242705cbc0dbSFan Du * another round of probing. 242805cbc0dbSFan Du */ 242905cbc0dbSFan Du tcp_mtu_check_reprobe(sk); 24305d424d5aSJohn Heffner return -1; 24315d424d5aSJohn Heffner } 24325d424d5aSJohn Heffner 24335d424d5aSJohn Heffner /* Have enough data in the send queue to probe? */ 24347f9c33e5SIlpo Järvinen if (tp->write_seq - tp->snd_nxt < size_needed) 24355d424d5aSJohn Heffner return -1; 24365d424d5aSJohn Heffner 243791cc17c0SIlpo Järvinen if (tp->snd_wnd < size_needed) 24385d424d5aSJohn Heffner return -1; 243990840defSIlpo Järvinen if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) 24405d424d5aSJohn Heffner return 0; 24415d424d5aSJohn Heffner 2442d67c58e9SIlpo Järvinen /* Do we need to wait to drain cwnd? With none in flight, don't stall */ 244340570375SEric Dumazet if (tcp_packets_in_flight(tp) + 2 > tcp_snd_cwnd(tp)) { 2444d67c58e9SIlpo Järvinen if (!tcp_packets_in_flight(tp)) 24455d424d5aSJohn Heffner return -1; 24465d424d5aSJohn Heffner else 24475d424d5aSJohn Heffner return 0; 24485d424d5aSJohn Heffner } 24495d424d5aSJohn Heffner 2450808cf9e3SIlya Lesokhin if (!tcp_can_coalesce_send_queue_head(sk, probe_size)) 2451808cf9e3SIlya Lesokhin return -1; 2452808cf9e3SIlya Lesokhin 24535d424d5aSJohn Heffner /* We're allowed to probe. Build it now. */ 24545882efffSEric Dumazet nskb = tcp_stream_alloc_skb(sk, GFP_ATOMIC, false); 245551456b29SIan Morris if (!nskb) 24565d424d5aSJohn Heffner return -1; 245773601329SEric Dumazet 245873601329SEric Dumazet /* build the payload, and be prepared to abort if this fails. */ 245973601329SEric Dumazet if (tcp_clone_payload(sk, nskb, probe_size)) { 246073601329SEric Dumazet consume_skb(nskb); 246173601329SEric Dumazet return -1; 246273601329SEric Dumazet } 2463ab4e846aSEric Dumazet sk_wmem_queued_add(sk, nskb->truesize); 24643ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 24655d424d5aSJohn Heffner 2466fe067e8aSDavid S. Miller skb = tcp_send_head(sk); 246741477662SJakub Kicinski skb_copy_decrypted(nskb, skb); 24685a369ca6SPaolo Abeni mptcp_skb_ext_copy(nskb, skb); 24695d424d5aSJohn Heffner 24705d424d5aSJohn Heffner TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; 24715d424d5aSJohn Heffner TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; 24724de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; 24735d424d5aSJohn Heffner 247450c4817eSIlpo Järvinen tcp_insert_write_queue_before(nskb, skb, sk); 24752b7cda9cSEric Dumazet tcp_highest_sack_replace(sk, skb, nskb); 247650c4817eSIlpo Järvinen 24775d424d5aSJohn Heffner len = 0; 2478234b6860SIlpo Järvinen tcp_for_write_queue_from_safe(skb, next, sk) { 24795d424d5aSJohn Heffner copy = min_t(int, skb->len, probe_size - len); 24805d424d5aSJohn Heffner 24815d424d5aSJohn Heffner if (skb->len <= copy) { 24825d424d5aSJohn Heffner /* We've eaten all the data from this skb. 24835d424d5aSJohn Heffner * Throw it away. */ 24844de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; 2485808cf9e3SIlya Lesokhin /* If this is the last SKB we copy and eor is set 2486808cf9e3SIlya Lesokhin * we need to propagate it to the new skb. 2487808cf9e3SIlya Lesokhin */ 2488808cf9e3SIlya Lesokhin TCP_SKB_CB(nskb)->eor = TCP_SKB_CB(skb)->eor; 2489888a5c53SWillem de Bruijn tcp_skb_collapse_tstamp(nskb, skb); 2490fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 249103271f3aSTalal Ahmad tcp_wmem_free_skb(sk, skb); 24925d424d5aSJohn Heffner } else { 24934de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & 2494a3433f35SChangli Gao ~(TCPHDR_FIN|TCPHDR_PSH); 24955d424d5aSJohn Heffner __pskb_trim_head(skb, copy); 24965bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss_now); 24975d424d5aSJohn Heffner TCP_SKB_CB(skb)->seq += copy; 24985d424d5aSJohn Heffner } 24995d424d5aSJohn Heffner 25005d424d5aSJohn Heffner len += copy; 2501234b6860SIlpo Järvinen 2502234b6860SIlpo Järvinen if (len >= probe_size) 2503234b6860SIlpo Järvinen break; 25045d424d5aSJohn Heffner } 25055bbb432cSEric Dumazet tcp_init_tso_segs(nskb, nskb->len); 25065d424d5aSJohn Heffner 25075d424d5aSJohn Heffner /* We're ready to send. If this fails, the probe will 25087faee5c0SEric Dumazet * be resegmented into mss-sized pieces by tcp_write_xmit(). 25097faee5c0SEric Dumazet */ 25105d424d5aSJohn Heffner if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { 25115d424d5aSJohn Heffner /* Decrement cwnd here because we are sending 25125d424d5aSJohn Heffner * effectively two packets. */ 251340570375SEric Dumazet tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) - 1); 251466f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, nskb); 25155d424d5aSJohn Heffner 25165d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); 25170e7b1368SJohn Heffner tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; 25180e7b1368SJohn Heffner tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; 25195d424d5aSJohn Heffner 25205d424d5aSJohn Heffner return 1; 25215d424d5aSJohn Heffner } 25225d424d5aSJohn Heffner 25235d424d5aSJohn Heffner return -1; 25245d424d5aSJohn Heffner } 25255d424d5aSJohn Heffner 2526864e5c09SEric Dumazet static bool tcp_pacing_check(struct sock *sk) 2527218af599SEric Dumazet { 2528864e5c09SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 2529864e5c09SEric Dumazet 2530864e5c09SEric Dumazet if (!tcp_needs_internal_pacing(sk)) 2531864e5c09SEric Dumazet return false; 2532864e5c09SEric Dumazet 2533864e5c09SEric Dumazet if (tp->tcp_wstamp_ns <= tp->tcp_clock_cache) 2534864e5c09SEric Dumazet return false; 2535864e5c09SEric Dumazet 2536864e5c09SEric Dumazet if (!hrtimer_is_queued(&tp->pacing_timer)) { 2537864e5c09SEric Dumazet hrtimer_start(&tp->pacing_timer, 2538864e5c09SEric Dumazet ns_to_ktime(tp->tcp_wstamp_ns), 2539864e5c09SEric Dumazet HRTIMER_MODE_ABS_PINNED_SOFT); 2540864e5c09SEric Dumazet sock_hold(sk); 2541864e5c09SEric Dumazet } 2542864e5c09SEric Dumazet return true; 2543218af599SEric Dumazet } 2544218af599SEric Dumazet 2545f9616c35SEric Dumazet /* TCP Small Queues : 2546f9616c35SEric Dumazet * Control number of packets in qdisc/devices to two packets / or ~1 ms. 2547f9616c35SEric Dumazet * (These limits are doubled for retransmits) 2548f9616c35SEric Dumazet * This allows for : 2549f9616c35SEric Dumazet * - better RTT estimation and ACK scheduling 2550f9616c35SEric Dumazet * - faster recovery 2551f9616c35SEric Dumazet * - high rates 2552f9616c35SEric Dumazet * Alas, some drivers / subsystems require a fair amount 2553f9616c35SEric Dumazet * of queued bytes to ensure line rate. 2554f9616c35SEric Dumazet * One example is wifi aggregation (802.11 AMPDU) 2555f9616c35SEric Dumazet */ 2556f9616c35SEric Dumazet static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb, 2557f9616c35SEric Dumazet unsigned int factor) 2558f9616c35SEric Dumazet { 255976a9ebe8SEric Dumazet unsigned long limit; 2560f9616c35SEric Dumazet 256176a9ebe8SEric Dumazet limit = max_t(unsigned long, 256276a9ebe8SEric Dumazet 2 * skb->truesize, 25637c68fa2bSEric Dumazet sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift)); 2564c73e5807SEric Dumazet if (sk->sk_pacing_status == SK_PACING_NONE) 256576a9ebe8SEric Dumazet limit = min_t(unsigned long, limit, 25669fb90193SKuniyuki Iwashima READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_limit_output_bytes)); 2567f9616c35SEric Dumazet limit <<= factor; 2568f9616c35SEric Dumazet 2569a842fe14SEric Dumazet if (static_branch_unlikely(&tcp_tx_delay_enabled) && 2570a842fe14SEric Dumazet tcp_sk(sk)->tcp_tx_delay) { 2571a842fe14SEric Dumazet u64 extra_bytes = (u64)sk->sk_pacing_rate * tcp_sk(sk)->tcp_tx_delay; 2572a842fe14SEric Dumazet 2573a842fe14SEric Dumazet /* TSQ is based on skb truesize sum (sk_wmem_alloc), so we 2574a842fe14SEric Dumazet * approximate our needs assuming an ~100% skb->truesize overhead. 2575a842fe14SEric Dumazet * USEC_PER_SEC is approximated by 2^20. 2576a842fe14SEric Dumazet * do_div(extra_bytes, USEC_PER_SEC/2) is replaced by a right shift. 2577a842fe14SEric Dumazet */ 2578a842fe14SEric Dumazet extra_bytes >>= (20 - 1); 2579a842fe14SEric Dumazet limit += extra_bytes; 2580a842fe14SEric Dumazet } 258114afee4bSReshetova, Elena if (refcount_read(&sk->sk_wmem_alloc) > limit) { 258275c119afSEric Dumazet /* Always send skb if rtx queue is empty. 258375eefc6cSEric Dumazet * No need to wait for TX completion to call us back, 258475eefc6cSEric Dumazet * after softirq/tasklet schedule. 258575eefc6cSEric Dumazet * This helps when TX completions are delayed too much. 258675eefc6cSEric Dumazet */ 258775c119afSEric Dumazet if (tcp_rtx_queue_empty(sk)) 258875eefc6cSEric Dumazet return false; 258975eefc6cSEric Dumazet 25907aa5470cSEric Dumazet set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags); 2591f9616c35SEric Dumazet /* It is possible TX completion already happened 2592f9616c35SEric Dumazet * before we set TSQ_THROTTLED, so we must 2593f9616c35SEric Dumazet * test again the condition. 2594f9616c35SEric Dumazet */ 2595f9616c35SEric Dumazet smp_mb__after_atomic(); 2596ce8299b6SEric Dumazet if (refcount_read(&sk->sk_wmem_alloc) > limit) 2597f9616c35SEric Dumazet return true; 2598f9616c35SEric Dumazet } 2599f9616c35SEric Dumazet return false; 2600f9616c35SEric Dumazet } 2601f9616c35SEric Dumazet 260205b055e8SFrancis Yan static void tcp_chrono_set(struct tcp_sock *tp, const enum tcp_chrono new) 260305b055e8SFrancis Yan { 2604628174ccSEric Dumazet const u32 now = tcp_jiffies32; 2605efe967cdSArnd Bergmann enum tcp_chrono old = tp->chrono_type; 260605b055e8SFrancis Yan 2607efe967cdSArnd Bergmann if (old > TCP_CHRONO_UNSPEC) 2608efe967cdSArnd Bergmann tp->chrono_stat[old - 1] += now - tp->chrono_start; 260905b055e8SFrancis Yan tp->chrono_start = now; 261005b055e8SFrancis Yan tp->chrono_type = new; 261105b055e8SFrancis Yan } 261205b055e8SFrancis Yan 261305b055e8SFrancis Yan void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type) 261405b055e8SFrancis Yan { 261505b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 261605b055e8SFrancis Yan 261705b055e8SFrancis Yan /* If there are multiple conditions worthy of tracking in a 26180f87230dSFrancis Yan * chronograph then the highest priority enum takes precedence 26190f87230dSFrancis Yan * over the other conditions. So that if something "more interesting" 262005b055e8SFrancis Yan * starts happening, stop the previous chrono and start a new one. 262105b055e8SFrancis Yan */ 262205b055e8SFrancis Yan if (type > tp->chrono_type) 262305b055e8SFrancis Yan tcp_chrono_set(tp, type); 262405b055e8SFrancis Yan } 262505b055e8SFrancis Yan 262605b055e8SFrancis Yan void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type) 262705b055e8SFrancis Yan { 262805b055e8SFrancis Yan struct tcp_sock *tp = tcp_sk(sk); 262905b055e8SFrancis Yan 26300f87230dSFrancis Yan 26310f87230dSFrancis Yan /* There are multiple conditions worthy of tracking in a 26320f87230dSFrancis Yan * chronograph, so that the highest priority enum takes 26330f87230dSFrancis Yan * precedence over the other conditions (see tcp_chrono_start). 26340f87230dSFrancis Yan * If a condition stops, we only stop chrono tracking if 26350f87230dSFrancis Yan * it's the "most interesting" or current chrono we are 26360f87230dSFrancis Yan * tracking and starts busy chrono if we have pending data. 26370f87230dSFrancis Yan */ 263875c119afSEric Dumazet if (tcp_rtx_and_write_queues_empty(sk)) 263905b055e8SFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_UNSPEC); 26400f87230dSFrancis Yan else if (type == tp->chrono_type) 26410f87230dSFrancis Yan tcp_chrono_set(tp, TCP_CHRONO_BUSY); 264205b055e8SFrancis Yan } 264305b055e8SFrancis Yan 26441da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 26451da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 26461da177e4SLinus Torvalds * window for us. 26471da177e4SLinus Torvalds * 2648f8269a49SIlpo Järvinen * LARGESEND note: !tcp_urg_mode is overkill, only frames between 2649f8269a49SIlpo Järvinen * snd_up-64k-mss .. snd_up cannot be large. However, taking into 2650f8269a49SIlpo Järvinen * account rare use of URG, this is not a big flaw. 2651f8269a49SIlpo Järvinen * 26526ba8a3b1SNandita Dukkipati * Send at most one packet when push_one > 0. Temporarily ignore 26536ba8a3b1SNandita Dukkipati * cwnd limit to force at most one packet out when push_one == 2. 26546ba8a3b1SNandita Dukkipati 2655a2a385d6SEric Dumazet * Returns true, if no segments are in flight and we have queued segments, 2656a2a385d6SEric Dumazet * but cannot send anything now because of SWS or another problem. 26571da177e4SLinus Torvalds */ 2658a2a385d6SEric Dumazet static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 2659d5dd9175SIlpo Järvinen int push_one, gfp_t gfp) 26601da177e4SLinus Torvalds { 26611da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 266292df7b51SDavid S. Miller struct sk_buff *skb; 2663c1b4a7e6SDavid S. Miller unsigned int tso_segs, sent_pkts; 2664c1b4a7e6SDavid S. Miller int cwnd_quota; 26655d424d5aSJohn Heffner int result; 26665615f886SFrancis Yan bool is_cwnd_limited = false, is_rwnd_limited = false; 2667605ad7f1SEric Dumazet u32 max_segs; 26681da177e4SLinus Torvalds 2669c1b4a7e6SDavid S. Miller sent_pkts = 0; 26705d424d5aSJohn Heffner 2671ee1836aeSEric Dumazet tcp_mstamp_refresh(tp); 2672d5dd9175SIlpo Järvinen if (!push_one) { 26735d424d5aSJohn Heffner /* Do MTU probing. */ 2674d5dd9175SIlpo Järvinen result = tcp_mtu_probe(sk); 2675d5dd9175SIlpo Järvinen if (!result) { 2676a2a385d6SEric Dumazet return false; 26775d424d5aSJohn Heffner } else if (result > 0) { 26785d424d5aSJohn Heffner sent_pkts = 1; 26795d424d5aSJohn Heffner } 2680d5dd9175SIlpo Järvinen } 26815d424d5aSJohn Heffner 2682ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, mss_now); 2683fe067e8aSDavid S. Miller while ((skb = tcp_send_head(sk))) { 2684c8ac3774SHerbert Xu unsigned int limit; 2685c8ac3774SHerbert Xu 268679861919SEric Dumazet if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { 268779861919SEric Dumazet /* "skb_mstamp_ns" is used as a start point for the retransmit timer */ 2688a1ac9c8aSMartin KaFai Lau tp->tcp_wstamp_ns = tp->tcp_clock_cache; 2689a1ac9c8aSMartin KaFai Lau skb_set_delivery_time(skb, tp->tcp_wstamp_ns, true); 269079861919SEric Dumazet list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); 2691bf50b606SEric Dumazet tcp_init_tso_segs(skb, mss_now); 269279861919SEric Dumazet goto repair; /* Skip network transmission */ 269379861919SEric Dumazet } 269479861919SEric Dumazet 2695218af599SEric Dumazet if (tcp_pacing_check(sk)) 2696218af599SEric Dumazet break; 2697218af599SEric Dumazet 26985bbb432cSEric Dumazet tso_segs = tcp_init_tso_segs(skb, mss_now); 2699c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 2700c1b4a7e6SDavid S. Miller 2701b68e9f85SHerbert Xu cwnd_quota = tcp_cwnd_test(tp, skb); 27026ba8a3b1SNandita Dukkipati if (!cwnd_quota) { 27036ba8a3b1SNandita Dukkipati if (push_one == 2) 27046ba8a3b1SNandita Dukkipati /* Force out a loss probe pkt. */ 27056ba8a3b1SNandita Dukkipati cwnd_quota = 1; 27066ba8a3b1SNandita Dukkipati else 2707b68e9f85SHerbert Xu break; 27086ba8a3b1SNandita Dukkipati } 2709b68e9f85SHerbert Xu 27105615f886SFrancis Yan if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) { 27115615f886SFrancis Yan is_rwnd_limited = true; 2712b68e9f85SHerbert Xu break; 27135615f886SFrancis Yan } 2714b68e9f85SHerbert Xu 2715d6a4e26aSEric Dumazet if (tso_segs == 1) { 2716aa93466bSDavid S. Miller if (unlikely(!tcp_nagle_test(tp, skb, mss_now, 2717aa93466bSDavid S. Miller (tcp_skb_is_last(sk, skb) ? 2718aa93466bSDavid S. Miller nonagle : TCP_NAGLE_PUSH)))) 2719aa93466bSDavid S. Miller break; 2720c1b4a7e6SDavid S. Miller } else { 2721ca8a2263SNeal Cardwell if (!push_one && 2722605ad7f1SEric Dumazet tcp_tso_should_defer(sk, skb, &is_cwnd_limited, 2723f9bfe4e6SEric Dumazet &is_rwnd_limited, max_segs)) 2724aa93466bSDavid S. Miller break; 2725c1b4a7e6SDavid S. Miller } 2726aa93466bSDavid S. Miller 2727605ad7f1SEric Dumazet limit = mss_now; 2728d6a4e26aSEric Dumazet if (tso_segs > 1 && !tcp_urg_mode(tp)) 2729605ad7f1SEric Dumazet limit = tcp_mss_split_point(sk, skb, mss_now, 2730605ad7f1SEric Dumazet min_t(unsigned int, 2731605ad7f1SEric Dumazet cwnd_quota, 2732605ad7f1SEric Dumazet max_segs), 2733605ad7f1SEric Dumazet nonagle); 2734605ad7f1SEric Dumazet 2735605ad7f1SEric Dumazet if (skb->len > limit && 273656483341SEric Dumazet unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) 2737605ad7f1SEric Dumazet break; 2738605ad7f1SEric Dumazet 2739f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 0)) 274046d3ceabSEric Dumazet break; 2741c9eeec26SEric Dumazet 27421f85e626SEric Dumazet /* Argh, we hit an empty skb(), presumably a thread 27431f85e626SEric Dumazet * is sleeping in sendmsg()/sk_stream_wait_memory(). 27441f85e626SEric Dumazet * We do not want to send a pure-ack packet and have 27451f85e626SEric Dumazet * a strange looking rtx queue with empty packet(s). 27461f85e626SEric Dumazet */ 27471f85e626SEric Dumazet if (TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq) 27481f85e626SEric Dumazet break; 27491f85e626SEric Dumazet 2750d5dd9175SIlpo Järvinen if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) 27511da177e4SLinus Torvalds break; 27521da177e4SLinus Torvalds 2753ec342325SAndrew Vagin repair: 27541da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 27551da177e4SLinus Torvalds * This call will increment packets_out. 27561da177e4SLinus Torvalds */ 275766f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 27581da177e4SLinus Torvalds 27591da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 2760a262f0cdSNandita Dukkipati sent_pkts += tcp_skb_pcount(skb); 2761d5dd9175SIlpo Järvinen 2762d5dd9175SIlpo Järvinen if (push_one) 2763d5dd9175SIlpo Järvinen break; 27641da177e4SLinus Torvalds } 27651da177e4SLinus Torvalds 27665615f886SFrancis Yan if (is_rwnd_limited) 27675615f886SFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_RWND_LIMITED); 27685615f886SFrancis Yan else 27695615f886SFrancis Yan tcp_chrono_stop(sk, TCP_CHRONO_RWND_LIMITED); 27705615f886SFrancis Yan 277140570375SEric Dumazet is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tcp_snd_cwnd(tp)); 2772299bcb55SNeal Cardwell if (likely(sent_pkts || is_cwnd_limited)) 2773299bcb55SNeal Cardwell tcp_cwnd_validate(sk, is_cwnd_limited); 2774299bcb55SNeal Cardwell 2775aa93466bSDavid S. Miller if (likely(sent_pkts)) { 2776684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 2777684bad11SYuchung Cheng tp->prr_out += sent_pkts; 27786ba8a3b1SNandita Dukkipati 27796ba8a3b1SNandita Dukkipati /* Send one loss probe per tail loss episode. */ 27806ba8a3b1SNandita Dukkipati if (push_one != 2) 2781ed66dfafSNeal Cardwell tcp_schedule_loss_probe(sk, false); 2782a2a385d6SEric Dumazet return false; 27831da177e4SLinus Torvalds } 278475c119afSEric Dumazet return !tp->packets_out && !tcp_write_queue_empty(sk); 27856ba8a3b1SNandita Dukkipati } 27866ba8a3b1SNandita Dukkipati 2787ed66dfafSNeal Cardwell bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto) 27886ba8a3b1SNandita Dukkipati { 27896ba8a3b1SNandita Dukkipati struct inet_connection_sock *icsk = inet_csk(sk); 27906ba8a3b1SNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 2791a2815817SNeal Cardwell u32 timeout, rto_delta_us; 27922ae21cf5SEric Dumazet int early_retrans; 27936ba8a3b1SNandita Dukkipati 27946ba8a3b1SNandita Dukkipati /* Don't do any loss probe on a Fast Open connection before 3WHS 27956ba8a3b1SNandita Dukkipati * finishes. 27966ba8a3b1SNandita Dukkipati */ 2797d983ea6fSEric Dumazet if (rcu_access_pointer(tp->fastopen_rsk)) 27986ba8a3b1SNandita Dukkipati return false; 27996ba8a3b1SNandita Dukkipati 280052e65865SKuniyuki Iwashima early_retrans = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_early_retrans); 28016ba8a3b1SNandita Dukkipati /* Schedule a loss probe in 2*RTT for SACK capable connections 2802b4f70c3dSNeal Cardwell * not in loss recovery, that are either limited by cwnd or application. 28036ba8a3b1SNandita Dukkipati */ 28042ae21cf5SEric Dumazet if ((early_retrans != 3 && early_retrans != 4) || 2805bec41a11SYuchung Cheng !tp->packets_out || !tcp_is_sack(tp) || 2806b4f70c3dSNeal Cardwell (icsk->icsk_ca_state != TCP_CA_Open && 2807b4f70c3dSNeal Cardwell icsk->icsk_ca_state != TCP_CA_CWR)) 28086ba8a3b1SNandita Dukkipati return false; 28096ba8a3b1SNandita Dukkipati 2810bb4d991aSYuchung Cheng /* Probe timeout is 2*rtt. Add minimum RTO to account 2811f9b99582SYuchung Cheng * for delayed ack when there's one outstanding packet. If no RTT 2812f9b99582SYuchung Cheng * sample is available then probe after TCP_TIMEOUT_INIT. 28136ba8a3b1SNandita Dukkipati */ 2814bb4d991aSYuchung Cheng if (tp->srtt_us) { 2815bb4d991aSYuchung Cheng timeout = usecs_to_jiffies(tp->srtt_us >> 2); 28166ba8a3b1SNandita Dukkipati if (tp->packets_out == 1) 2817bb4d991aSYuchung Cheng timeout += TCP_RTO_MIN; 2818bb4d991aSYuchung Cheng else 2819bb4d991aSYuchung Cheng timeout += TCP_TIMEOUT_MIN; 2820bb4d991aSYuchung Cheng } else { 2821bb4d991aSYuchung Cheng timeout = TCP_TIMEOUT_INIT; 2822bb4d991aSYuchung Cheng } 28236ba8a3b1SNandita Dukkipati 2824a2815817SNeal Cardwell /* If the RTO formula yields an earlier time, then use that time. */ 2825ed66dfafSNeal Cardwell rto_delta_us = advancing_rto ? 2826ed66dfafSNeal Cardwell jiffies_to_usecs(inet_csk(sk)->icsk_rto) : 2827ed66dfafSNeal Cardwell tcp_rto_delta_us(sk); /* How far in future is RTO? */ 2828a2815817SNeal Cardwell if (rto_delta_us > 0) 2829a2815817SNeal Cardwell timeout = min_t(u32, timeout, usecs_to_jiffies(rto_delta_us)); 28306ba8a3b1SNandita Dukkipati 28318dc242adSEric Dumazet tcp_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, TCP_RTO_MAX); 28326ba8a3b1SNandita Dukkipati return true; 28336ba8a3b1SNandita Dukkipati } 28346ba8a3b1SNandita Dukkipati 28351f3279aeSEric Dumazet /* Thanks to skb fast clones, we can detect if a prior transmit of 28361f3279aeSEric Dumazet * a packet is still in a qdisc or driver queue. 28371f3279aeSEric Dumazet * In this case, there is very little point doing a retransmit ! 28381f3279aeSEric Dumazet */ 2839f4dae54eSEric Dumazet static bool skb_still_in_host_queue(struct sock *sk, 28401f3279aeSEric Dumazet const struct sk_buff *skb) 28411f3279aeSEric Dumazet { 284239bb5e62SEric Dumazet if (unlikely(skb_fclone_busy(sk, skb))) { 2843f4dae54eSEric Dumazet set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags); 2844f4dae54eSEric Dumazet smp_mb__after_atomic(); 2845f4dae54eSEric Dumazet if (skb_fclone_busy(sk, skb)) { 2846c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), 28471f3279aeSEric Dumazet LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); 28481f3279aeSEric Dumazet return true; 28491f3279aeSEric Dumazet } 2850f4dae54eSEric Dumazet } 28511f3279aeSEric Dumazet return false; 28521f3279aeSEric Dumazet } 28531f3279aeSEric Dumazet 2854b340b264SYuchung Cheng /* When probe timeout (PTO) fires, try send a new segment if possible, else 28556ba8a3b1SNandita Dukkipati * retransmit the last segment. 28566ba8a3b1SNandita Dukkipati */ 28576ba8a3b1SNandita Dukkipati void tcp_send_loss_probe(struct sock *sk) 28586ba8a3b1SNandita Dukkipati { 28599b717a8dSNandita Dukkipati struct tcp_sock *tp = tcp_sk(sk); 28606ba8a3b1SNandita Dukkipati struct sk_buff *skb; 28616ba8a3b1SNandita Dukkipati int pcount; 28626ba8a3b1SNandita Dukkipati int mss = tcp_current_mss(sk); 28636ba8a3b1SNandita Dukkipati 286476be93fcSYuchung Cheng /* At most one outstanding TLP */ 286576be93fcSYuchung Cheng if (tp->tlp_high_seq) 286676be93fcSYuchung Cheng goto rearm_timer; 286776be93fcSYuchung Cheng 286876be93fcSYuchung Cheng tp->tlp_retrans = 0; 2869b340b264SYuchung Cheng skb = tcp_send_head(sk); 287075c119afSEric Dumazet if (skb && tcp_snd_wnd_test(tp, skb, mss)) { 2871b340b264SYuchung Cheng pcount = tp->packets_out; 2872b340b264SYuchung Cheng tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); 2873b340b264SYuchung Cheng if (tp->packets_out > pcount) 2874b340b264SYuchung Cheng goto probe_sent; 28756ba8a3b1SNandita Dukkipati goto rearm_timer; 28766ba8a3b1SNandita Dukkipati } 287775c119afSEric Dumazet skb = skb_rb_last(&sk->tcp_rtx_queue); 2878b2b7af86SYuchung Cheng if (unlikely(!skb)) { 2879b2b7af86SYuchung Cheng WARN_ONCE(tp->packets_out, 2880b2b7af86SYuchung Cheng "invalid inflight: %u state %u cwnd %u mss %d\n", 288140570375SEric Dumazet tp->packets_out, sk->sk_state, tcp_snd_cwnd(tp), mss); 2882b2b7af86SYuchung Cheng inet_csk(sk)->icsk_pending = 0; 2883b2b7af86SYuchung Cheng return; 2884b2b7af86SYuchung Cheng } 28856ba8a3b1SNandita Dukkipati 28861f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 28871f3279aeSEric Dumazet goto rearm_timer; 28881f3279aeSEric Dumazet 28896ba8a3b1SNandita Dukkipati pcount = tcp_skb_pcount(skb); 28906ba8a3b1SNandita Dukkipati if (WARN_ON(!pcount)) 28916ba8a3b1SNandita Dukkipati goto rearm_timer; 28926ba8a3b1SNandita Dukkipati 28936ba8a3b1SNandita Dukkipati if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { 289475c119afSEric Dumazet if (unlikely(tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, 289575c119afSEric Dumazet (pcount - 1) * mss, mss, 28966cc55e09SOctavian Purdila GFP_ATOMIC))) 28976ba8a3b1SNandita Dukkipati goto rearm_timer; 289875c119afSEric Dumazet skb = skb_rb_next(skb); 28996ba8a3b1SNandita Dukkipati } 29006ba8a3b1SNandita Dukkipati 29016ba8a3b1SNandita Dukkipati if (WARN_ON(!skb || !tcp_skb_pcount(skb))) 29026ba8a3b1SNandita Dukkipati goto rearm_timer; 29036ba8a3b1SNandita Dukkipati 290410d3be56SEric Dumazet if (__tcp_retransmit_skb(sk, skb, 1)) 2905b340b264SYuchung Cheng goto rearm_timer; 29066ba8a3b1SNandita Dukkipati 290776be93fcSYuchung Cheng tp->tlp_retrans = 1; 290876be93fcSYuchung Cheng 290976be93fcSYuchung Cheng probe_sent: 29109b717a8dSNandita Dukkipati /* Record snd_nxt for loss detection. */ 29119b717a8dSNandita Dukkipati tp->tlp_high_seq = tp->snd_nxt; 29129b717a8dSNandita Dukkipati 2913c10d9310SEric Dumazet NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSSPROBES); 2914fcd16c0aSYuchung Cheng /* Reset s.t. tcp_rearm_rto will restart timer from now */ 2915fcd16c0aSYuchung Cheng inet_csk(sk)->icsk_pending = 0; 2916b340b264SYuchung Cheng rearm_timer: 2917fcd16c0aSYuchung Cheng tcp_rearm_rto(sk); 29181da177e4SLinus Torvalds } 29191da177e4SLinus Torvalds 2920a762a980SDavid S. Miller /* Push out any pending frames which were held back due to 2921a762a980SDavid S. Miller * TCP_CORK or attempt at coalescing tiny packets. 2922a762a980SDavid S. Miller * The socket must be locked by the caller. 2923a762a980SDavid S. Miller */ 29249e412ba7SIlpo Järvinen void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 29259e412ba7SIlpo Järvinen int nonagle) 2926a762a980SDavid S. Miller { 2927726e07a8SIlpo Järvinen /* If we are closed, the bytes will have to remain here. 2928726e07a8SIlpo Järvinen * In time closedown will finish, we empty the write queue and 2929726e07a8SIlpo Järvinen * all will be happy. 2930726e07a8SIlpo Järvinen */ 2931726e07a8SIlpo Järvinen if (unlikely(sk->sk_state == TCP_CLOSE)) 2932726e07a8SIlpo Järvinen return; 2933726e07a8SIlpo Järvinen 293499a1dec7SMel Gorman if (tcp_write_xmit(sk, cur_mss, nonagle, 0, 29357450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC))) 29369e412ba7SIlpo Järvinen tcp_check_probe_timer(sk); 2937a762a980SDavid S. Miller } 2938a762a980SDavid S. Miller 2939c1b4a7e6SDavid S. Miller /* Send _single_ skb sitting at the send head. This function requires 2940c1b4a7e6SDavid S. Miller * true push pending frames to setup probe timer etc. 2941c1b4a7e6SDavid S. Miller */ 2942c1b4a7e6SDavid S. Miller void tcp_push_one(struct sock *sk, unsigned int mss_now) 2943c1b4a7e6SDavid S. Miller { 2944fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 2945c1b4a7e6SDavid S. Miller 2946c1b4a7e6SDavid S. Miller BUG_ON(!skb || skb->len < mss_now); 2947c1b4a7e6SDavid S. Miller 2948d5dd9175SIlpo Järvinen tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); 2949c1b4a7e6SDavid S. Miller } 2950c1b4a7e6SDavid S. Miller 29511da177e4SLinus Torvalds /* This function returns the amount that we can raise the 29521da177e4SLinus Torvalds * usable window based on the following constraints 29531da177e4SLinus Torvalds * 29541da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 29551da177e4SLinus Torvalds * 2. We limit memory per socket 29561da177e4SLinus Torvalds * 29571da177e4SLinus Torvalds * RFC 1122: 29581da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 29591da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 29601da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 29611da177e4SLinus Torvalds * 29621da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 29631da177e4SLinus Torvalds * it at least MSS bytes. 29641da177e4SLinus Torvalds * 29651da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 29661da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 29671da177e4SLinus Torvalds * 29681da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 29691da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 29701da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 29711da177e4SLinus Torvalds * window to always advance by a single byte. 29721da177e4SLinus Torvalds * 29731da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 29741da177e4SLinus Torvalds * then this will not be a problem. 29751da177e4SLinus Torvalds * 29761da177e4SLinus Torvalds * BSD seems to make the following compromise: 29771da177e4SLinus Torvalds * 29781da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 29791da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 29801da177e4SLinus Torvalds * then set the window to 0. 29811da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 29821da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 29831da177e4SLinus Torvalds * and from being larger than the largest representable value. 29841da177e4SLinus Torvalds * 29851da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 29861da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 29871da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 29881da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 29891da177e4SLinus Torvalds * because the pipeline is full. 29901da177e4SLinus Torvalds * 29911da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 29921da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 29931da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 29941da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 29951da177e4SLinus Torvalds * of having a fixed window size at almost all times. 29961da177e4SLinus Torvalds * 29971da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 29981da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 29991da177e4SLinus Torvalds * 30001da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 30011da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 30021da177e4SLinus Torvalds */ 30031da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 30041da177e4SLinus Torvalds { 3005463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 30061da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 3007b650d953Smfreemon@cloudflare.com struct net *net = sock_net(sk); 3008caa20d9aSStephen Hemminger /* MSS for the peer's data. Previous versions used mss_clamp 30091da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 30101da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 30111da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 30121da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 30131da177e4SLinus Torvalds */ 3014463c84b9SArnaldo Carvalho de Melo int mss = icsk->icsk_ack.rcv_mss; 30151da177e4SLinus Torvalds int free_space = tcp_space(sk); 301686c1a045SFlorian Westphal int allowed_space = tcp_full_space(sk); 3017071c8ed6SFlorian Westphal int full_space, window; 3018071c8ed6SFlorian Westphal 3019071c8ed6SFlorian Westphal if (sk_is_mptcp(sk)) 3020071c8ed6SFlorian Westphal mptcp_space(sk, &free_space, &allowed_space); 3021071c8ed6SFlorian Westphal 3022071c8ed6SFlorian Westphal full_space = min_t(int, tp->window_clamp, allowed_space); 30231da177e4SLinus Torvalds 302406425c30SEric Dumazet if (unlikely(mss > full_space)) { 30251da177e4SLinus Torvalds mss = full_space; 302606425c30SEric Dumazet if (mss <= 0) 302706425c30SEric Dumazet return 0; 302806425c30SEric Dumazet } 3029b650d953Smfreemon@cloudflare.com 3030b650d953Smfreemon@cloudflare.com /* Only allow window shrink if the sysctl is enabled and we have 3031b650d953Smfreemon@cloudflare.com * a non-zero scaling factor in effect. 3032b650d953Smfreemon@cloudflare.com */ 3033b650d953Smfreemon@cloudflare.com if (READ_ONCE(net->ipv4.sysctl_tcp_shrink_window) && tp->rx_opt.rcv_wscale) 3034b650d953Smfreemon@cloudflare.com goto shrink_window_allowed; 3035b650d953Smfreemon@cloudflare.com 3036b650d953Smfreemon@cloudflare.com /* do not allow window to shrink */ 3037b650d953Smfreemon@cloudflare.com 3038b92edbe0SEric Dumazet if (free_space < (full_space >> 1)) { 3039463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.quick = 0; 30401da177e4SLinus Torvalds 3041b8da51ebSEric Dumazet if (tcp_under_memory_pressure(sk)) 3042053f3684SWei Wang tcp_adjust_rcv_ssthresh(sk); 30431da177e4SLinus Torvalds 304486c1a045SFlorian Westphal /* free_space might become our new window, make sure we don't 304586c1a045SFlorian Westphal * increase it due to wscale. 304686c1a045SFlorian Westphal */ 304786c1a045SFlorian Westphal free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); 304886c1a045SFlorian Westphal 304986c1a045SFlorian Westphal /* if free space is less than mss estimate, or is below 1/16th 305086c1a045SFlorian Westphal * of the maximum allowed, try to move to zero-window, else 305186c1a045SFlorian Westphal * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and 305286c1a045SFlorian Westphal * new incoming data is dropped due to memory limits. 305386c1a045SFlorian Westphal * With large window, mss test triggers way too late in order 305486c1a045SFlorian Westphal * to announce zero window in time before rmem limit kicks in. 305586c1a045SFlorian Westphal */ 305686c1a045SFlorian Westphal if (free_space < (allowed_space >> 4) || free_space < mss) 30571da177e4SLinus Torvalds return 0; 30581da177e4SLinus Torvalds } 30591da177e4SLinus Torvalds 30601da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 30611da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 30621da177e4SLinus Torvalds 30631da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 30641da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 30651da177e4SLinus Torvalds */ 30661da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 30671da177e4SLinus Torvalds window = free_space; 30681da177e4SLinus Torvalds 30691da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 30701da177e4SLinus Torvalds * Import case: prevent zero window announcement if 30711da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 30721da177e4SLinus Torvalds */ 30731935299dSGao Feng window = ALIGN(window, (1 << tp->rx_opt.rcv_wscale)); 30741da177e4SLinus Torvalds } else { 30751935299dSGao Feng window = tp->rcv_wnd; 30761da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 30771da177e4SLinus Torvalds * Window clamp already applied above. 30781da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 30791da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 30801da177e4SLinus Torvalds * and multiply from happening most of the time. 30811da177e4SLinus Torvalds * We also don't do any window rounding when the free space 30821da177e4SLinus Torvalds * is too small. 30831da177e4SLinus Torvalds */ 30841da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 30851935299dSGao Feng window = rounddown(free_space, mss); 308684565070SJohn Heffner else if (mss == full_space && 3087b92edbe0SEric Dumazet free_space > window + (full_space >> 1)) 308884565070SJohn Heffner window = free_space; 30891da177e4SLinus Torvalds } 30901da177e4SLinus Torvalds 30911da177e4SLinus Torvalds return window; 3092b650d953Smfreemon@cloudflare.com 3093b650d953Smfreemon@cloudflare.com shrink_window_allowed: 3094b650d953Smfreemon@cloudflare.com /* new window should always be an exact multiple of scaling factor */ 3095b650d953Smfreemon@cloudflare.com free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); 3096b650d953Smfreemon@cloudflare.com 3097b650d953Smfreemon@cloudflare.com if (free_space < (full_space >> 1)) { 3098b650d953Smfreemon@cloudflare.com icsk->icsk_ack.quick = 0; 3099b650d953Smfreemon@cloudflare.com 3100b650d953Smfreemon@cloudflare.com if (tcp_under_memory_pressure(sk)) 3101b650d953Smfreemon@cloudflare.com tcp_adjust_rcv_ssthresh(sk); 3102b650d953Smfreemon@cloudflare.com 3103b650d953Smfreemon@cloudflare.com /* if free space is too low, return a zero window */ 3104b650d953Smfreemon@cloudflare.com if (free_space < (allowed_space >> 4) || free_space < mss || 3105b650d953Smfreemon@cloudflare.com free_space < (1 << tp->rx_opt.rcv_wscale)) 3106b650d953Smfreemon@cloudflare.com return 0; 3107b650d953Smfreemon@cloudflare.com } 3108b650d953Smfreemon@cloudflare.com 3109b650d953Smfreemon@cloudflare.com if (free_space > tp->rcv_ssthresh) { 3110b650d953Smfreemon@cloudflare.com free_space = tp->rcv_ssthresh; 3111b650d953Smfreemon@cloudflare.com /* new window should always be an exact multiple of scaling factor 3112b650d953Smfreemon@cloudflare.com * 3113b650d953Smfreemon@cloudflare.com * For this case, we ALIGN "up" (increase free_space) because 3114b650d953Smfreemon@cloudflare.com * we know free_space is not zero here, it has been reduced from 3115b650d953Smfreemon@cloudflare.com * the memory-based limit, and rcv_ssthresh is not a hard limit 3116b650d953Smfreemon@cloudflare.com * (unlike sk_rcvbuf). 3117b650d953Smfreemon@cloudflare.com */ 3118b650d953Smfreemon@cloudflare.com free_space = ALIGN(free_space, (1 << tp->rx_opt.rcv_wscale)); 3119b650d953Smfreemon@cloudflare.com } 3120b650d953Smfreemon@cloudflare.com 3121b650d953Smfreemon@cloudflare.com return free_space; 31221da177e4SLinus Torvalds } 31231da177e4SLinus Torvalds 3124cfea5a68SMartin KaFai Lau void tcp_skb_collapse_tstamp(struct sk_buff *skb, 3125082ac2d5SMartin KaFai Lau const struct sk_buff *next_skb) 3126082ac2d5SMartin KaFai Lau { 31270a2cf20cSSoheil Hassas Yeganeh if (unlikely(tcp_has_tx_tstamp(next_skb))) { 31280a2cf20cSSoheil Hassas Yeganeh const struct skb_shared_info *next_shinfo = 31290a2cf20cSSoheil Hassas Yeganeh skb_shinfo(next_skb); 3130082ac2d5SMartin KaFai Lau struct skb_shared_info *shinfo = skb_shinfo(skb); 3131082ac2d5SMartin KaFai Lau 31320a2cf20cSSoheil Hassas Yeganeh shinfo->tx_flags |= next_shinfo->tx_flags & SKBTX_ANY_TSTAMP; 3133082ac2d5SMartin KaFai Lau shinfo->tskey = next_shinfo->tskey; 31342de8023eSMartin KaFai Lau TCP_SKB_CB(skb)->txstamp_ack |= 31352de8023eSMartin KaFai Lau TCP_SKB_CB(next_skb)->txstamp_ack; 3136082ac2d5SMartin KaFai Lau } 3137082ac2d5SMartin KaFai Lau } 3138082ac2d5SMartin KaFai Lau 31394a17fc3aSIlpo Järvinen /* Collapses two adjacent SKB's during retransmission. */ 3140f8071cdeSEric Dumazet static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) 31411da177e4SLinus Torvalds { 31421da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 314375c119afSEric Dumazet struct sk_buff *next_skb = skb_rb_next(skb); 314413dde04fSWei Yongjun int next_skb_size; 31451da177e4SLinus Torvalds 3146058dc334SIlpo Järvinen next_skb_size = next_skb->len; 31471da177e4SLinus Torvalds 3148058dc334SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); 31491da177e4SLinus Torvalds 3150bd446314SEric Dumazet if (next_skb_size && !tcp_skb_shift(skb, next_skb, 1, next_skb_size)) 3151f8071cdeSEric Dumazet return false; 3152bd446314SEric Dumazet 31532b7cda9cSEric Dumazet tcp_highest_sack_replace(sk, next_skb, skb); 3154a6963a6bSIlpo Järvinen 31551da177e4SLinus Torvalds /* Update sequence range on original skb. */ 31561da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 31571da177e4SLinus Torvalds 3158e6c7d085SIlpo Järvinen /* Merge over control information. This moves PSH/FIN etc. over */ 31594de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; 31601da177e4SLinus Torvalds 31611da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 31621da177e4SLinus Torvalds * packet counting does not break. 31631da177e4SLinus Torvalds */ 31644828e7f4SIlpo Järvinen TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; 3165a643b5d4SMartin KaFai Lau TCP_SKB_CB(skb)->eor = TCP_SKB_CB(next_skb)->eor; 3166b7689205SIlpo Järvinen 3167b7689205SIlpo Järvinen /* changed transmit queue under us so clear hints */ 3168ef9da47cSIlpo Järvinen tcp_clear_retrans_hints_partial(tp); 3169ef9da47cSIlpo Järvinen if (next_skb == tp->retransmit_skb_hint) 3170ef9da47cSIlpo Järvinen tp->retransmit_skb_hint = skb; 3171b7689205SIlpo Järvinen 3172797108d1SIlpo Järvinen tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); 3173797108d1SIlpo Järvinen 3174082ac2d5SMartin KaFai Lau tcp_skb_collapse_tstamp(skb, next_skb); 3175082ac2d5SMartin KaFai Lau 317675c119afSEric Dumazet tcp_rtx_queue_unlink_and_free(next_skb, sk); 3177f8071cdeSEric Dumazet return true; 31781da177e4SLinus Torvalds } 31791da177e4SLinus Torvalds 318067edfef7SAndi Kleen /* Check if coalescing SKBs is legal. */ 3181a2a385d6SEric Dumazet static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) 31824a17fc3aSIlpo Järvinen { 31834a17fc3aSIlpo Järvinen if (tcp_skb_pcount(skb) > 1) 3184a2a385d6SEric Dumazet return false; 31854a17fc3aSIlpo Järvinen if (skb_cloned(skb)) 3186a2a385d6SEric Dumazet return false; 31872331ccc5SEric Dumazet /* Some heuristics for collapsing over SACK'd could be invented */ 31884a17fc3aSIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 3189a2a385d6SEric Dumazet return false; 31904a17fc3aSIlpo Järvinen 3191a2a385d6SEric Dumazet return true; 31924a17fc3aSIlpo Järvinen } 31934a17fc3aSIlpo Järvinen 319467edfef7SAndi Kleen /* Collapse packets in the retransmit queue to make to create 319567edfef7SAndi Kleen * less packets on the wire. This is only done on retransmission. 319667edfef7SAndi Kleen */ 31974a17fc3aSIlpo Järvinen static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, 31984a17fc3aSIlpo Järvinen int space) 31994a17fc3aSIlpo Järvinen { 32004a17fc3aSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 32014a17fc3aSIlpo Järvinen struct sk_buff *skb = to, *tmp; 3202a2a385d6SEric Dumazet bool first = true; 32034a17fc3aSIlpo Järvinen 32041a63cb91SKuniyuki Iwashima if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_retrans_collapse)) 32054a17fc3aSIlpo Järvinen return; 32064de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 32074a17fc3aSIlpo Järvinen return; 32084a17fc3aSIlpo Järvinen 320975c119afSEric Dumazet skb_rbtree_walk_from_safe(skb, tmp) { 32104a17fc3aSIlpo Järvinen if (!tcp_can_collapse(sk, skb)) 32114a17fc3aSIlpo Järvinen break; 32124a17fc3aSIlpo Järvinen 321385712484SMat Martineau if (!tcp_skb_can_collapse(to, skb)) 3214a643b5d4SMartin KaFai Lau break; 3215a643b5d4SMartin KaFai Lau 32164a17fc3aSIlpo Järvinen space -= skb->len; 32174a17fc3aSIlpo Järvinen 32184a17fc3aSIlpo Järvinen if (first) { 3219a2a385d6SEric Dumazet first = false; 32204a17fc3aSIlpo Järvinen continue; 32214a17fc3aSIlpo Järvinen } 32224a17fc3aSIlpo Järvinen 32234a17fc3aSIlpo Järvinen if (space < 0) 32244a17fc3aSIlpo Järvinen break; 32254a17fc3aSIlpo Järvinen 32264a17fc3aSIlpo Järvinen if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) 32274a17fc3aSIlpo Järvinen break; 32284a17fc3aSIlpo Järvinen 3229f8071cdeSEric Dumazet if (!tcp_collapse_retrans(sk, to)) 3230f8071cdeSEric Dumazet break; 32314a17fc3aSIlpo Järvinen } 32324a17fc3aSIlpo Järvinen } 32334a17fc3aSIlpo Järvinen 32341da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 32351da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 32361da177e4SLinus Torvalds * error occurred which prevented the send. 32371da177e4SLinus Torvalds */ 323810d3be56SEric Dumazet int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 32391da177e4SLinus Torvalds { 32405d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 324110d3be56SEric Dumazet struct tcp_sock *tp = tcp_sk(sk); 32427d227cd2SSridhar Samudrala unsigned int cur_mss; 324310d3be56SEric Dumazet int diff, len, err; 3244536a6c8eSYonglong Li int avail_wnd; 324510d3be56SEric Dumazet 324610d3be56SEric Dumazet /* Inconclusive MTU probe */ 324710d3be56SEric Dumazet if (icsk->icsk_mtup.probe_size) 32485d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 32495d424d5aSJohn Heffner 32501f3279aeSEric Dumazet if (skb_still_in_host_queue(sk, skb)) 32511f3279aeSEric Dumazet return -EBUSY; 32521f3279aeSEric Dumazet 32531da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 32547f582b24SEric Dumazet if (unlikely(before(TCP_SKB_CB(skb)->end_seq, tp->snd_una))) { 32557f582b24SEric Dumazet WARN_ON_ONCE(1); 32567f582b24SEric Dumazet return -EINVAL; 32577f582b24SEric Dumazet } 32581da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 32591da177e4SLinus Torvalds return -ENOMEM; 32601da177e4SLinus Torvalds } 32611da177e4SLinus Torvalds 32627d227cd2SSridhar Samudrala if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 32637d227cd2SSridhar Samudrala return -EHOSTUNREACH; /* Routing failure or similar. */ 32647d227cd2SSridhar Samudrala 32650c54b85fSIlpo Järvinen cur_mss = tcp_current_mss(sk); 3266536a6c8eSYonglong Li avail_wnd = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 32677d227cd2SSridhar Samudrala 32681da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 32691da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 32701da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 3271536a6c8eSYonglong Li * our retransmit of one segment serves as a zero window probe. 32721da177e4SLinus Torvalds */ 3273536a6c8eSYonglong Li if (avail_wnd <= 0) { 3274536a6c8eSYonglong Li if (TCP_SKB_CB(skb)->seq != tp->snd_una) 32751da177e4SLinus Torvalds return -EAGAIN; 3276536a6c8eSYonglong Li avail_wnd = cur_mss; 3277536a6c8eSYonglong Li } 32781da177e4SLinus Torvalds 327910d3be56SEric Dumazet len = cur_mss * segs; 3280536a6c8eSYonglong Li if (len > avail_wnd) { 3281536a6c8eSYonglong Li len = rounddown(avail_wnd, cur_mss); 3282536a6c8eSYonglong Li if (!len) 3283536a6c8eSYonglong Li len = avail_wnd; 3284536a6c8eSYonglong Li } 328510d3be56SEric Dumazet if (skb->len > len) { 328675c119afSEric Dumazet if (tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, len, 328775c119afSEric Dumazet cur_mss, GFP_ATOMIC)) 32881da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 328902276f3cSIlpo Järvinen } else { 3290c4777efaSEric Dumazet if (skb_unclone_keeptruesize(skb, GFP_ATOMIC)) 3291c52e2421SEric Dumazet return -ENOMEM; 329210d3be56SEric Dumazet 329310d3be56SEric Dumazet diff = tcp_skb_pcount(skb); 329410d3be56SEric Dumazet tcp_set_skb_tso_segs(skb, cur_mss); 329510d3be56SEric Dumazet diff -= tcp_skb_pcount(skb); 329610d3be56SEric Dumazet if (diff) 329710d3be56SEric Dumazet tcp_adjust_pcount(sk, skb, diff); 3298536a6c8eSYonglong Li avail_wnd = min_t(int, avail_wnd, cur_mss); 3299536a6c8eSYonglong Li if (skb->len < avail_wnd) 3300536a6c8eSYonglong Li tcp_retrans_try_collapse(sk, skb, avail_wnd); 33011da177e4SLinus Torvalds } 33021da177e4SLinus Torvalds 330349213555SDaniel Borkmann /* RFC3168, section 6.1.1.1. ECN fallback */ 330449213555SDaniel Borkmann if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN_ECN) == TCPHDR_SYN_ECN) 330549213555SDaniel Borkmann tcp_ecn_clear_syn(sk, skb); 330649213555SDaniel Borkmann 3307678550c6SYuchung Cheng /* Update global and local TCP statistics. */ 3308678550c6SYuchung Cheng segs = tcp_skb_pcount(skb); 3309678550c6SYuchung Cheng TCP_ADD_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS, segs); 3310678550c6SYuchung Cheng if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 3311678550c6SYuchung Cheng __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 3312678550c6SYuchung Cheng tp->total_retrans += segs; 3313fb31c9b9SWei Wang tp->bytes_retrans += skb->len; 3314678550c6SYuchung Cheng 331550bceae9SThomas Graf /* make sure skb->data is aligned on arches that require it 331650bceae9SThomas Graf * and check if ack-trimming & collapsing extended the headroom 331750bceae9SThomas Graf * beyond what csum_start can cover. 331850bceae9SThomas Graf */ 331950bceae9SThomas Graf if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || 332050bceae9SThomas Graf skb_headroom(skb) >= 0xFFFF)) { 332110a81980SEric Dumazet struct sk_buff *nskb; 332210a81980SEric Dumazet 3323e2080072SEric Dumazet tcp_skb_tsorted_save(skb) { 332410a81980SEric Dumazet nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC); 332507f8e4d0SFlorian Westphal if (nskb) { 332607f8e4d0SFlorian Westphal nskb->dev = NULL; 332707f8e4d0SFlorian Westphal err = tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC); 332807f8e4d0SFlorian Westphal } else { 332907f8e4d0SFlorian Westphal err = -ENOBUFS; 333007f8e4d0SFlorian Westphal } 3331e2080072SEric Dumazet } tcp_skb_tsorted_restore(skb); 3332e2080072SEric Dumazet 33335889e2c0SYousuk Seung if (!err) { 3334a7a25630SEric Dumazet tcp_update_skb_after_send(sk, skb, tp->tcp_wstamp_ns); 33355889e2c0SYousuk Seung tcp_rate_skb_sent(sk, skb); 33365889e2c0SYousuk Seung } 3337117632e6SEric Dumazet } else { 3338c84a5711SYuchung Cheng err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 3339117632e6SEric Dumazet } 3340c84a5711SYuchung Cheng 33417f12422cSYuchung Cheng /* To avoid taking spuriously low RTT samples based on a timestamp 33427f12422cSYuchung Cheng * for a transmit that never happened, always mark EVER_RETRANS 33437f12422cSYuchung Cheng */ 33447f12422cSYuchung Cheng TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; 33457f12422cSYuchung Cheng 3346a31ad29eSLawrence Brakmo if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RETRANS_CB_FLAG)) 3347a31ad29eSLawrence Brakmo tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RETRANS_CB, 3348a31ad29eSLawrence Brakmo TCP_SKB_CB(skb)->seq, segs, err); 3349a31ad29eSLawrence Brakmo 3350fc9f3501SEric Dumazet if (likely(!err)) { 3351e086101bSCong Wang trace_tcp_retransmit_skb(sk, skb); 3352678550c6SYuchung Cheng } else if (err != -EBUSY) { 3353ec641b39SYuchung Cheng NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL, segs); 3354fc9f3501SEric Dumazet } 3355c84a5711SYuchung Cheng return err; 335693b174adSYuchung Cheng } 335793b174adSYuchung Cheng 335810d3be56SEric Dumazet int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 335993b174adSYuchung Cheng { 336093b174adSYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 336110d3be56SEric Dumazet int err = __tcp_retransmit_skb(sk, skb, segs); 33621da177e4SLinus Torvalds 33631da177e4SLinus Torvalds if (err == 0) { 33641da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 33651da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { 3366e87cc472SJoe Perches net_dbg_ratelimited("retrans_out leaked\n"); 33671da177e4SLinus Torvalds } 33681da177e4SLinus Torvalds #endif 33691da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 33701da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 33717ae18975SYuchung Cheng } 33721da177e4SLinus Torvalds 33737ae18975SYuchung Cheng /* Save stamp of the first (attempted) retransmit. */ 33741da177e4SLinus Torvalds if (!tp->retrans_stamp) 33757faee5c0SEric Dumazet tp->retrans_stamp = tcp_skb_timestamp(skb); 33761da177e4SLinus Torvalds 33776e08d5e3SYuchung Cheng if (tp->undo_retrans < 0) 33786e08d5e3SYuchung Cheng tp->undo_retrans = 0; 33796e08d5e3SYuchung Cheng tp->undo_retrans += tcp_skb_pcount(skb); 33801da177e4SLinus Torvalds return err; 33811da177e4SLinus Torvalds } 33821da177e4SLinus Torvalds 33831da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 33841da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 33851da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 33861da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 33871da177e4SLinus Torvalds */ 33881da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 33891da177e4SLinus Torvalds { 33906687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 3391b9f1f1ceSEric Dumazet struct sk_buff *skb, *rtx_head, *hole = NULL; 33921da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 3393916e6d1aSEric Dumazet bool rearm_timer = false; 3394840a3cbeSYuchung Cheng u32 max_segs; 339561eb55f4SIlpo Järvinen int mib_idx; 33966a438bbeSStephen Hemminger 339745e77d31SIlpo Järvinen if (!tp->packets_out) 339845e77d31SIlpo Järvinen return; 339945e77d31SIlpo Järvinen 340075c119afSEric Dumazet rtx_head = tcp_rtx_queue_head(sk); 3401b9f1f1ceSEric Dumazet skb = tp->retransmit_skb_hint ?: rtx_head; 3402ed6e7268SNeal Cardwell max_segs = tcp_tso_segs(sk, tcp_current_mss(sk)); 340375c119afSEric Dumazet skb_rbtree_walk_from(skb) { 3404dca0aaf8SEric Dumazet __u8 sacked; 340510d3be56SEric Dumazet int segs; 34061da177e4SLinus Torvalds 3407218af599SEric Dumazet if (tcp_pacing_check(sk)) 3408218af599SEric Dumazet break; 3409218af599SEric Dumazet 34106a438bbeSStephen Hemminger /* we could do better than to assign each time */ 341151456b29SIan Morris if (!hole) 34126a438bbeSStephen Hemminger tp->retransmit_skb_hint = skb; 34136a438bbeSStephen Hemminger 341440570375SEric Dumazet segs = tcp_snd_cwnd(tp) - tcp_packets_in_flight(tp); 341510d3be56SEric Dumazet if (segs <= 0) 3416916e6d1aSEric Dumazet break; 3417dca0aaf8SEric Dumazet sacked = TCP_SKB_CB(skb)->sacked; 3418a3d2e9f8SEric Dumazet /* In case tcp_shift_skb_data() have aggregated large skbs, 3419a3d2e9f8SEric Dumazet * we need to make sure not sending too bigs TSO packets 3420a3d2e9f8SEric Dumazet */ 3421a3d2e9f8SEric Dumazet segs = min_t(int, segs, max_segs); 34220e1c54c2SIlpo Järvinen 3423840a3cbeSYuchung Cheng if (tp->retrans_out >= tp->lost_out) { 3424006f582cSIlpo Järvinen break; 34250e1c54c2SIlpo Järvinen } else if (!(sacked & TCPCB_LOST)) { 342651456b29SIan Morris if (!hole && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) 34270e1c54c2SIlpo Järvinen hole = skb; 342861eb55f4SIlpo Järvinen continue; 34291da177e4SLinus Torvalds 34300e1c54c2SIlpo Järvinen } else { 34310e1c54c2SIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Loss) 34320e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFASTRETRANS; 34330e1c54c2SIlpo Järvinen else 34340e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; 34350e1c54c2SIlpo Järvinen } 34360e1c54c2SIlpo Järvinen 34370e1c54c2SIlpo Järvinen if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) 343861eb55f4SIlpo Järvinen continue; 343940b215e5SPavel Emelyanov 3440f9616c35SEric Dumazet if (tcp_small_queue_check(sk, skb, 1)) 3441916e6d1aSEric Dumazet break; 3442f9616c35SEric Dumazet 344310d3be56SEric Dumazet if (tcp_retransmit_skb(sk, skb, segs)) 3444916e6d1aSEric Dumazet break; 344524ab6becSYuchung Cheng 3446de1d6578SYuchung Cheng NET_ADD_STATS(sock_net(sk), mib_idx, tcp_skb_pcount(skb)); 34471da177e4SLinus Torvalds 3448684bad11SYuchung Cheng if (tcp_in_cwnd_reduction(sk)) 3449a262f0cdSNandita Dukkipati tp->prr_out += tcp_skb_pcount(skb); 3450a262f0cdSNandita Dukkipati 345175c119afSEric Dumazet if (skb == rtx_head && 345257dde7f7SYuchung Cheng icsk->icsk_pending != ICSK_TIME_REO_TIMEOUT) 3453916e6d1aSEric Dumazet rearm_timer = true; 3454916e6d1aSEric Dumazet 3455916e6d1aSEric Dumazet } 3456916e6d1aSEric Dumazet if (rearm_timer) 34573f80e08fSEric Dumazet tcp_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 34583f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, 34598dc242adSEric Dumazet TCP_RTO_MAX); 34601da177e4SLinus Torvalds } 34611da177e4SLinus Torvalds 3462d83769a5SEric Dumazet /* We allow to exceed memory limits for FIN packets to expedite 3463d83769a5SEric Dumazet * connection tear down and (memory) recovery. 3464845704a5SEric Dumazet * Otherwise tcp_send_fin() could be tempted to either delay FIN 3465845704a5SEric Dumazet * or even be forced to close flow without any FIN. 3466a6c5ea4cSEric Dumazet * In general, we want to allow one skb per socket to avoid hangs 3467a6c5ea4cSEric Dumazet * with edge trigger epoll() 3468d83769a5SEric Dumazet */ 3469a6c5ea4cSEric Dumazet void sk_forced_mem_schedule(struct sock *sk, int size) 3470d83769a5SEric Dumazet { 3471c4ee1185SEric Dumazet int delta, amt; 3472d83769a5SEric Dumazet 3473c4ee1185SEric Dumazet delta = size - sk->sk_forward_alloc; 3474c4ee1185SEric Dumazet if (delta <= 0) 3475d83769a5SEric Dumazet return; 3476c4ee1185SEric Dumazet amt = sk_mem_pages(delta); 3477100fdd1fSEric Dumazet sk->sk_forward_alloc += amt << PAGE_SHIFT; 3478e805605cSJohannes Weiner sk_memory_allocated_add(sk, amt); 3479e805605cSJohannes Weiner 3480baac50bbSJohannes Weiner if (mem_cgroup_sockets_enabled && sk->sk_memcg) 34814b1327beSWei Wang mem_cgroup_charge_skmem(sk->sk_memcg, amt, 34824b1327beSWei Wang gfp_memcg_charge() | __GFP_NOFAIL); 3483d83769a5SEric Dumazet } 3484d83769a5SEric Dumazet 3485845704a5SEric Dumazet /* Send a FIN. The caller locks the socket for us. 3486845704a5SEric Dumazet * We should try to send a FIN packet really hard, but eventually give up. 34871da177e4SLinus Torvalds */ 34881da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 34891da177e4SLinus Torvalds { 3490ee2aabd3SEric Dumazet struct sk_buff *skb, *tskb, *tail = tcp_write_queue_tail(sk); 34911da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 34921da177e4SLinus Torvalds 3493845704a5SEric Dumazet /* Optimization, tack on the FIN if we have one skb in write queue and 3494845704a5SEric Dumazet * this skb was not yet sent, or we are under memory pressure. 3495845704a5SEric Dumazet * Note: in the latter case, FIN packet will be sent after a timeout, 3496845704a5SEric Dumazet * as TCP stack thinks it has already been transmitted. 34971da177e4SLinus Torvalds */ 3498ee2aabd3SEric Dumazet tskb = tail; 349975c119afSEric Dumazet if (!tskb && tcp_under_memory_pressure(sk)) 350075c119afSEric Dumazet tskb = skb_rb_last(&sk->tcp_rtx_queue); 350175c119afSEric Dumazet 350275c119afSEric Dumazet if (tskb) { 3503845704a5SEric Dumazet TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN; 3504845704a5SEric Dumazet TCP_SKB_CB(tskb)->end_seq++; 35051da177e4SLinus Torvalds tp->write_seq++; 3506ee2aabd3SEric Dumazet if (!tail) { 3507845704a5SEric Dumazet /* This means tskb was already sent. 3508845704a5SEric Dumazet * Pretend we included the FIN on previous transmit. 3509845704a5SEric Dumazet * We need to set tp->snd_nxt to the value it would have 3510845704a5SEric Dumazet * if FIN had been sent. This is because retransmit path 3511845704a5SEric Dumazet * does not change tp->snd_nxt. 3512845704a5SEric Dumazet */ 3513e0d694d6SEric Dumazet WRITE_ONCE(tp->snd_nxt, tp->snd_nxt + 1); 3514845704a5SEric Dumazet return; 3515845704a5SEric Dumazet } 35161da177e4SLinus Torvalds } else { 3517845704a5SEric Dumazet skb = alloc_skb_fclone(MAX_TCP_HEADER, sk->sk_allocation); 3518d1edc085SColin Ian King if (unlikely(!skb)) 3519845704a5SEric Dumazet return; 3520d1edc085SColin Ian King 3521e2080072SEric Dumazet INIT_LIST_HEAD(&skb->tcp_tsorted_anchor); 3522d83769a5SEric Dumazet skb_reserve(skb, MAX_TCP_HEADER); 3523a6c5ea4cSEric Dumazet sk_forced_mem_schedule(sk, skb->truesize); 35241da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 3525e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tp->write_seq, 3526a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_FIN); 35271da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 35281da177e4SLinus Torvalds } 3529845704a5SEric Dumazet __tcp_push_pending_frames(sk, tcp_current_mss(sk), TCP_NAGLE_OFF); 35301da177e4SLinus Torvalds } 35311da177e4SLinus Torvalds 35321da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 35331da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 35341da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 353565bb723cSGerrit Renker * by RFC 2525, section 2.17. -DaveM 35361da177e4SLinus Torvalds */ 3537dd0fc66fSAl Viro void tcp_send_active_reset(struct sock *sk, gfp_t priority) 35381da177e4SLinus Torvalds { 35391da177e4SLinus Torvalds struct sk_buff *skb; 35401da177e4SLinus Torvalds 35417cc2b043SGao Feng TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); 35427cc2b043SGao Feng 35431da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 35441da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 35451da177e4SLinus Torvalds if (!skb) { 35464e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 35471da177e4SLinus Torvalds return; 35481da177e4SLinus Torvalds } 35491da177e4SLinus Torvalds 35501da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 35511da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 3552e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), 3553a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_RST); 35549a568de4SEric Dumazet tcp_mstamp_refresh(tcp_sk(sk)); 35551da177e4SLinus Torvalds /* Send it off. */ 3556dfb4b9dcSDavid S. Miller if (tcp_transmit_skb(sk, skb, 0, priority)) 35574e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 3558c24b14c4SSong Liu 3559c24b14c4SSong Liu /* skb of trace_tcp_send_reset() keeps the skb that caused RST, 3560c24b14c4SSong Liu * skb here is different to the troublesome skb, so use NULL 3561c24b14c4SSong Liu */ 3562c24b14c4SSong Liu trace_tcp_send_reset(sk, NULL); 35631da177e4SLinus Torvalds } 35641da177e4SLinus Torvalds 356567edfef7SAndi Kleen /* Send a crossed SYN-ACK during socket establishment. 356667edfef7SAndi Kleen * WARNING: This routine must only be called when we have already sent 35671da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 35681da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 35691da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 35701da177e4SLinus Torvalds */ 35711da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 35721da177e4SLinus Torvalds { 35731da177e4SLinus Torvalds struct sk_buff *skb; 35741da177e4SLinus Torvalds 357575c119afSEric Dumazet skb = tcp_rtx_queue_head(sk); 357651456b29SIan Morris if (!skb || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { 357775c119afSEric Dumazet pr_err("%s: wrong queue state\n", __func__); 35781da177e4SLinus Torvalds return -EFAULT; 35791da177e4SLinus Torvalds } 35804de075e0SEric Dumazet if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { 35811da177e4SLinus Torvalds if (skb_cloned(skb)) { 3582e2080072SEric Dumazet struct sk_buff *nskb; 3583e2080072SEric Dumazet 3584e2080072SEric Dumazet tcp_skb_tsorted_save(skb) { 3585e2080072SEric Dumazet nskb = skb_copy(skb, GFP_ATOMIC); 3586e2080072SEric Dumazet } tcp_skb_tsorted_restore(skb); 358751456b29SIan Morris if (!nskb) 35881da177e4SLinus Torvalds return -ENOMEM; 3589e2080072SEric Dumazet INIT_LIST_HEAD(&nskb->tcp_tsorted_anchor); 35902bec445fSEric Dumazet tcp_highest_sack_replace(sk, skb, nskb); 359175c119afSEric Dumazet tcp_rtx_queue_unlink_and_free(skb, sk); 3592f4a775d1SEric Dumazet __skb_header_release(nskb); 359375c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, nskb); 3594ab4e846aSEric Dumazet sk_wmem_queued_add(sk, nskb->truesize); 35953ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 35961da177e4SLinus Torvalds skb = nskb; 35971da177e4SLinus Torvalds } 35981da177e4SLinus Torvalds 35994de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; 3600735d3831SFlorian Westphal tcp_ecn_send_synack(sk, skb); 36011da177e4SLinus Torvalds } 3602dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 36031da177e4SLinus Torvalds } 36041da177e4SLinus Torvalds 36054aea39c1SEric Dumazet /** 3606331fca43SMartin KaFai Lau * tcp_make_synack - Allocate one skb and build a SYNACK packet. 3607331fca43SMartin KaFai Lau * @sk: listener socket 3608331fca43SMartin KaFai Lau * @dst: dst entry attached to the SYNACK. It is consumed and caller 3609331fca43SMartin KaFai Lau * should not use it again. 3610331fca43SMartin KaFai Lau * @req: request_sock pointer 3611331fca43SMartin KaFai Lau * @foc: cookie for tcp fast open 3612331fca43SMartin KaFai Lau * @synack_type: Type of synack to prepare 3613331fca43SMartin KaFai Lau * @syn_skb: SYN packet just received. It could be NULL for rtx case. 36144aea39c1SEric Dumazet */ 36155d062de7SEric Dumazet struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 3616e6b4d113SWilliam Allen Simpson struct request_sock *req, 3617ca6fb065SEric Dumazet struct tcp_fastopen_cookie *foc, 3618331fca43SMartin KaFai Lau enum tcp_synack_type synack_type, 3619331fca43SMartin KaFai Lau struct sk_buff *syn_skb) 36201da177e4SLinus Torvalds { 36212e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 36225d062de7SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 362380f03e27SEric Dumazet struct tcp_md5sig_key *md5 = NULL; 36245d062de7SEric Dumazet struct tcp_out_options opts; 36255d062de7SEric Dumazet struct sk_buff *skb; 3626bd0388aeSWilliam Allen Simpson int tcp_header_size; 36275d062de7SEric Dumazet struct tcphdr *th; 3628f5fff5dcSTom Quetchenbach int mss; 3629a842fe14SEric Dumazet u64 now; 36301da177e4SLinus Torvalds 3631ca6fb065SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 36324aea39c1SEric Dumazet if (unlikely(!skb)) { 36334aea39c1SEric Dumazet dst_release(dst); 36341da177e4SLinus Torvalds return NULL; 36354aea39c1SEric Dumazet } 36361da177e4SLinus Torvalds /* Reserve space for headers. */ 36371da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 36381da177e4SLinus Torvalds 3639b3d05147SEric Dumazet switch (synack_type) { 3640b3d05147SEric Dumazet case TCP_SYNACK_NORMAL: 36419e17f8a4SEric Dumazet skb_set_owner_w(skb, req_to_sk(req)); 3642b3d05147SEric Dumazet break; 3643b3d05147SEric Dumazet case TCP_SYNACK_COOKIE: 3644b3d05147SEric Dumazet /* Under synflood, we do not attach skb to a socket, 3645b3d05147SEric Dumazet * to avoid false sharing. 3646b3d05147SEric Dumazet */ 3647b3d05147SEric Dumazet break; 3648b3d05147SEric Dumazet case TCP_SYNACK_FASTOPEN: 3649ca6fb065SEric Dumazet /* sk is a const pointer, because we want to express multiple 3650ca6fb065SEric Dumazet * cpu might call us concurrently. 3651ca6fb065SEric Dumazet * sk->sk_wmem_alloc in an atomic, we can promote to rw. 3652ca6fb065SEric Dumazet */ 3653ca6fb065SEric Dumazet skb_set_owner_w(skb, (struct sock *)sk); 3654b3d05147SEric Dumazet break; 3655ca6fb065SEric Dumazet } 36564aea39c1SEric Dumazet skb_dst_set(skb, dst); 36571da177e4SLinus Torvalds 36583541f9e8SEric Dumazet mss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); 3659f5fff5dcSTom Quetchenbach 366033ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 3661a842fe14SEric Dumazet now = tcp_clock_ns(); 36628b5f12d0SFlorian Westphal #ifdef CONFIG_SYN_COOKIES 3663f8ace8d9SFlorian Westphal if (unlikely(synack_type == TCP_SYNACK_COOKIE && ireq->tstamp_ok)) 3664a1ac9c8aSMartin KaFai Lau skb_set_delivery_time(skb, cookie_init_timestamp(req, now), 3665a1ac9c8aSMartin KaFai Lau true); 36668b5f12d0SFlorian Westphal else 36678b5f12d0SFlorian Westphal #endif 36689e450c1eSYuchung Cheng { 3669a1ac9c8aSMartin KaFai Lau skb_set_delivery_time(skb, now, true); 36709e450c1eSYuchung Cheng if (!tcp_rsk(req)->snt_synack) /* Timestamp first SYNACK */ 36719e450c1eSYuchung Cheng tcp_rsk(req)->snt_synack = tcp_skb_timestamp_us(skb); 36729e450c1eSYuchung Cheng } 367380f03e27SEric Dumazet 367480f03e27SEric Dumazet #ifdef CONFIG_TCP_MD5SIG 367580f03e27SEric Dumazet rcu_read_lock(); 3676fd3a154aSEric Dumazet md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req)); 367780f03e27SEric Dumazet #endif 36785e526552SEric Dumazet skb_set_hash(skb, READ_ONCE(tcp_rsk(req)->txhash), PKT_HASH_TYPE_L4); 3679331fca43SMartin KaFai Lau /* bpf program will be interested in the tcp_flags */ 3680331fca43SMartin KaFai Lau TCP_SKB_CB(skb)->tcp_flags = TCPHDR_SYN | TCPHDR_ACK; 368160e2a778SUrsula Braun tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, md5, 3682331fca43SMartin KaFai Lau foc, synack_type, 3683331fca43SMartin KaFai Lau syn_skb) + sizeof(*th); 368433ad798cSAdam Langley 3685aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 3686aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 36871da177e4SLinus Torvalds 3688ea1627c2SEric Dumazet th = (struct tcphdr *)skb->data; 36891da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 36901da177e4SLinus Torvalds th->syn = 1; 36911da177e4SLinus Torvalds th->ack = 1; 36926ac705b1SEric Dumazet tcp_ecn_make_synack(req, th); 3693b44084c2SEric Dumazet th->source = htons(ireq->ir_num); 3694634fb979SEric Dumazet th->dest = ireq->ir_rmt_port; 3695e05a90ecSJamal Hadi Salim skb->mark = ireq->ir_mark; 36963b117750SEric Dumazet skb->ip_summed = CHECKSUM_PARTIAL; 36973b117750SEric Dumazet th->seq = htonl(tcp_rsk(req)->snt_isn); 36988336886fSJerry Chu /* XXX data is queued and acked as is. No buffer/window check */ 36998336886fSJerry Chu th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); 37001da177e4SLinus Torvalds 37011da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 3702ed53d0abSEric Dumazet th->window = htons(min(req->rsk_rcv_wnd, 65535U)); 3703ea66758cSPaolo Abeni tcp_options_write(th, NULL, &opts); 37041da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 3705bced3f7dSBreno Leitao TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS); 3706cfb6eeb4SYOSHIFUJI Hideaki 3707cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 3708cfb6eeb4SYOSHIFUJI Hideaki /* Okay, we have all we need - do the md5 hash if needed */ 370980f03e27SEric Dumazet if (md5) 3710bd0388aeSWilliam Allen Simpson tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, 371139f8e58eSEric Dumazet md5, req_to_sk(req), skb); 371280f03e27SEric Dumazet rcu_read_unlock(); 3713cfb6eeb4SYOSHIFUJI Hideaki #endif 3714cfb6eeb4SYOSHIFUJI Hideaki 3715331fca43SMartin KaFai Lau bpf_skops_write_hdr_opt((struct sock *)sk, skb, req, syn_skb, 3716331fca43SMartin KaFai Lau synack_type, &opts); 3717331fca43SMartin KaFai Lau 3718a1ac9c8aSMartin KaFai Lau skb_set_delivery_time(skb, now, true); 3719a842fe14SEric Dumazet tcp_add_tx_delay(skb, tp); 3720a842fe14SEric Dumazet 37211da177e4SLinus Torvalds return skb; 37221da177e4SLinus Torvalds } 37234bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_make_synack); 37241da177e4SLinus Torvalds 372581164413SDaniel Borkmann static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst) 372681164413SDaniel Borkmann { 372781164413SDaniel Borkmann struct inet_connection_sock *icsk = inet_csk(sk); 372881164413SDaniel Borkmann const struct tcp_congestion_ops *ca; 372981164413SDaniel Borkmann u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); 373081164413SDaniel Borkmann 373181164413SDaniel Borkmann if (ca_key == TCP_CA_UNSPEC) 373281164413SDaniel Borkmann return; 373381164413SDaniel Borkmann 373481164413SDaniel Borkmann rcu_read_lock(); 373581164413SDaniel Borkmann ca = tcp_ca_find_key(ca_key); 37360baf26b0SMartin KaFai Lau if (likely(ca && bpf_try_module_get(ca, ca->owner))) { 37370baf26b0SMartin KaFai Lau bpf_module_put(icsk->icsk_ca_ops, icsk->icsk_ca_ops->owner); 373881164413SDaniel Borkmann icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst); 373981164413SDaniel Borkmann icsk->icsk_ca_ops = ca; 374081164413SDaniel Borkmann } 374181164413SDaniel Borkmann rcu_read_unlock(); 374281164413SDaniel Borkmann } 374381164413SDaniel Borkmann 374467edfef7SAndi Kleen /* Do all connect socket setups that can be done AF independent. */ 3745f7e56a76Sstephen hemminger static void tcp_connect_init(struct sock *sk) 37461da177e4SLinus Torvalds { 3747cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 37481da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 37491da177e4SLinus Torvalds __u8 rcv_wscale; 375013d3b1ebSLawrence Brakmo u32 rcv_wnd; 37511da177e4SLinus Torvalds 37521da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 37531da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 37541da177e4SLinus Torvalds */ 37555d2ed052SEric Dumazet tp->tcp_header_len = sizeof(struct tcphdr); 37563666f666SKuniyuki Iwashima if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_timestamps)) 37575d2ed052SEric Dumazet tp->tcp_header_len += TCPOLEN_TSTAMP_ALIGNED; 37581da177e4SLinus Torvalds 37591da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 37601da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 37611da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 37621da177e4SLinus Torvalds tp->max_window = 0; 37635d424d5aSJohn Heffner tcp_mtup_init(sk); 37641da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 37651da177e4SLinus Torvalds 376681164413SDaniel Borkmann tcp_ca_dst_init(sk, dst); 376781164413SDaniel Borkmann 37681da177e4SLinus Torvalds if (!tp->window_clamp) 37691da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 37703541f9e8SEric Dumazet tp->advmss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); 3771f5fff5dcSTom Quetchenbach 37721da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 37731da177e4SLinus Torvalds 3774e88c64f0SHagen Paul Pfeifer /* limit the window selection if the user enforce a smaller rx buffer */ 3775e88c64f0SHagen Paul Pfeifer if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && 3776e88c64f0SHagen Paul Pfeifer (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) 3777e88c64f0SHagen Paul Pfeifer tp->window_clamp = tcp_full_space(sk); 3778e88c64f0SHagen Paul Pfeifer 377913d3b1ebSLawrence Brakmo rcv_wnd = tcp_rwnd_init_bpf(sk); 378013d3b1ebSLawrence Brakmo if (rcv_wnd == 0) 378113d3b1ebSLawrence Brakmo rcv_wnd = dst_metric(dst, RTAX_INITRWND); 378213d3b1ebSLawrence Brakmo 3783ceef9ab6SEric Dumazet tcp_select_initial_window(sk, tcp_full_space(sk), 37841da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 37851da177e4SLinus Torvalds &tp->rcv_wnd, 37861da177e4SLinus Torvalds &tp->window_clamp, 37873666f666SKuniyuki Iwashima READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_window_scaling), 378831d12926Slaurent chavey &rcv_wscale, 378913d3b1ebSLawrence Brakmo rcv_wnd); 37901da177e4SLinus Torvalds 37911da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 37921da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 37931da177e4SLinus Torvalds 3794e13ec3daSEric Dumazet WRITE_ONCE(sk->sk_err, 0); 37951da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 37961da177e4SLinus Torvalds tp->snd_wnd = 0; 3797ee7537b6SHantzis Fotis tcp_init_wl(tp, 0); 37987f582b24SEric Dumazet tcp_write_queue_purge(sk); 37991da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 38001da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 380133f5f57eSIlpo Järvinen tp->snd_up = tp->write_seq; 3802e0d694d6SEric Dumazet WRITE_ONCE(tp->snd_nxt, tp->write_seq); 3803ee995283SPavel Emelyanov 3804ee995283SPavel Emelyanov if (likely(!tp->repair)) 38051da177e4SLinus Torvalds tp->rcv_nxt = 0; 3806c7781a6eSAndrew Vagin else 380770eabf0eSEric Dumazet tp->rcv_tstamp = tcp_jiffies32; 3808ee995283SPavel Emelyanov tp->rcv_wup = tp->rcv_nxt; 38097db48e98SEric Dumazet WRITE_ONCE(tp->copied_seq, tp->rcv_nxt); 38101da177e4SLinus Torvalds 38118550f328SLawrence Brakmo inet_csk(sk)->icsk_rto = tcp_timeout_init(sk); 3812463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_retransmits = 0; 38131da177e4SLinus Torvalds tcp_clear_retrans(tp); 38141da177e4SLinus Torvalds } 38151da177e4SLinus Torvalds 3816783237e8SYuchung Cheng static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) 3817783237e8SYuchung Cheng { 3818783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3819783237e8SYuchung Cheng struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); 3820783237e8SYuchung Cheng 3821783237e8SYuchung Cheng tcb->end_seq += skb->len; 3822f4a775d1SEric Dumazet __skb_header_release(skb); 3823ab4e846aSEric Dumazet sk_wmem_queued_add(sk, skb->truesize); 3824783237e8SYuchung Cheng sk_mem_charge(sk, skb->truesize); 38250f317464SEric Dumazet WRITE_ONCE(tp->write_seq, tcb->end_seq); 3826783237e8SYuchung Cheng tp->packets_out += tcp_skb_pcount(skb); 3827783237e8SYuchung Cheng } 3828783237e8SYuchung Cheng 3829783237e8SYuchung Cheng /* Build and send a SYN with data and (cached) Fast Open cookie. However, 3830783237e8SYuchung Cheng * queue a data-only packet after the regular SYN, such that regular SYNs 3831783237e8SYuchung Cheng * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges 3832783237e8SYuchung Cheng * only the SYN sequence, the data are retransmitted in the first ACK. 3833783237e8SYuchung Cheng * If cookie is not cached or other error occurs, falls back to send a 3834783237e8SYuchung Cheng * regular SYN with Fast Open cookie request option. 3835783237e8SYuchung Cheng */ 3836783237e8SYuchung Cheng static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) 3837783237e8SYuchung Cheng { 3838ed0c99dcSJakub Kicinski struct inet_connection_sock *icsk = inet_csk(sk); 3839783237e8SYuchung Cheng struct tcp_sock *tp = tcp_sk(sk); 3840783237e8SYuchung Cheng struct tcp_fastopen_request *fo = tp->fastopen_req; 3841fbf93406SEric Dumazet struct page_frag *pfrag = sk_page_frag(sk); 3842355a901eSEric Dumazet struct sk_buff *syn_data; 3843fbf93406SEric Dumazet int space, err = 0; 3844783237e8SYuchung Cheng 384567da22d2SYuchung Cheng tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ 3846065263f4SWei Wang if (!tcp_fastopen_cookie_check(sk, &tp->rx_opt.mss_clamp, &fo->cookie)) 3847783237e8SYuchung Cheng goto fallback; 3848783237e8SYuchung Cheng 3849783237e8SYuchung Cheng /* MSS for SYN-data is based on cached MSS and bounded by PMTU and 3850783237e8SYuchung Cheng * user-MSS. Reserve maximum option space for middleboxes that add 3851783237e8SYuchung Cheng * private TCP options. The cost is reduced data space in SYN :( 3852783237e8SYuchung Cheng */ 38533541f9e8SEric Dumazet tp->rx_opt.mss_clamp = tcp_mss_clamp(tp, tp->rx_opt.mss_clamp); 3854ed0c99dcSJakub Kicinski /* Sync mss_cache after updating the mss_clamp */ 3855ed0c99dcSJakub Kicinski tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); 38563541f9e8SEric Dumazet 3857ed0c99dcSJakub Kicinski space = __tcp_mtu_to_mss(sk, icsk->icsk_pmtu_cookie) - 3858783237e8SYuchung Cheng MAX_TCP_OPTION_SPACE; 3859783237e8SYuchung Cheng 3860f5ddcbbbSEric Dumazet space = min_t(size_t, space, fo->size); 3861f5ddcbbbSEric Dumazet 3862fbf93406SEric Dumazet if (space && 3863fbf93406SEric Dumazet !skb_page_frag_refill(min_t(size_t, space, PAGE_SIZE), 3864fbf93406SEric Dumazet pfrag, sk->sk_allocation)) 3865fbf93406SEric Dumazet goto fallback; 38665882efffSEric Dumazet syn_data = tcp_stream_alloc_skb(sk, sk->sk_allocation, false); 3867355a901eSEric Dumazet if (!syn_data) 3868783237e8SYuchung Cheng goto fallback; 3869355a901eSEric Dumazet memcpy(syn_data->cb, syn->cb, sizeof(syn->cb)); 387007e100f9SEric Dumazet if (space) { 3871fbf93406SEric Dumazet space = min_t(size_t, space, pfrag->size - pfrag->offset); 3872fbf93406SEric Dumazet space = tcp_wmem_schedule(sk, space); 3873fbf93406SEric Dumazet } 3874fbf93406SEric Dumazet if (space) { 3875fbf93406SEric Dumazet space = copy_page_from_iter(pfrag->page, pfrag->offset, 3876fbf93406SEric Dumazet space, &fo->data->msg_iter); 3877fbf93406SEric Dumazet if (unlikely(!space)) { 3878ba233b34SEric Dumazet tcp_skb_tsorted_anchor_cleanup(syn_data); 3879355a901eSEric Dumazet kfree_skb(syn_data); 3880783237e8SYuchung Cheng goto fallback; 3881783237e8SYuchung Cheng } 3882fbf93406SEric Dumazet skb_fill_page_desc(syn_data, 0, pfrag->page, 3883fbf93406SEric Dumazet pfrag->offset, space); 3884fbf93406SEric Dumazet page_ref_inc(pfrag->page); 3885fbf93406SEric Dumazet pfrag->offset += space; 3886fbf93406SEric Dumazet skb_len_add(syn_data, space); 3887f859a448SWillem de Bruijn skb_zcopy_set(syn_data, fo->uarg, NULL); 388807e100f9SEric Dumazet } 3889355a901eSEric Dumazet /* No more data pending in inet_wait_for_connect() */ 3890355a901eSEric Dumazet if (space == fo->size) 3891355a901eSEric Dumazet fo->data = NULL; 3892355a901eSEric Dumazet fo->copied = space; 3893783237e8SYuchung Cheng 3894355a901eSEric Dumazet tcp_connect_queue_skb(sk, syn_data); 38950f87230dSFrancis Yan if (syn_data->len) 38960f87230dSFrancis Yan tcp_chrono_start(sk, TCP_CHRONO_BUSY); 3897355a901eSEric Dumazet 3898355a901eSEric Dumazet err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation); 3899355a901eSEric Dumazet 3900a1ac9c8aSMartin KaFai Lau skb_set_delivery_time(syn, syn_data->skb_mstamp_ns, true); 3901355a901eSEric Dumazet 3902355a901eSEric Dumazet /* Now full SYN+DATA was cloned and sent (or not), 3903355a901eSEric Dumazet * remove the SYN from the original skb (syn_data) 3904355a901eSEric Dumazet * we keep in write queue in case of a retransmit, as we 3905355a901eSEric Dumazet * also have the SYN packet (with no data) in the same queue. 3906431a9124SEric Dumazet */ 3907355a901eSEric Dumazet TCP_SKB_CB(syn_data)->seq++; 3908355a901eSEric Dumazet TCP_SKB_CB(syn_data)->tcp_flags = TCPHDR_ACK | TCPHDR_PSH; 3909355a901eSEric Dumazet if (!err) { 391067da22d2SYuchung Cheng tp->syn_data = (fo->copied > 0); 391175c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, syn_data); 3912f19c29e3SYuchung Cheng NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT); 3913783237e8SYuchung Cheng goto done; 3914783237e8SYuchung Cheng } 3915783237e8SYuchung Cheng 391675c119afSEric Dumazet /* data was not sent, put it in write_queue */ 391775c119afSEric Dumazet __skb_queue_tail(&sk->sk_write_queue, syn_data); 3918b5b7db8dSEric Dumazet tp->packets_out -= tcp_skb_pcount(syn_data); 3919b5b7db8dSEric Dumazet 3920783237e8SYuchung Cheng fallback: 3921783237e8SYuchung Cheng /* Send a regular SYN with Fast Open cookie request option */ 3922783237e8SYuchung Cheng if (fo->cookie.len > 0) 3923783237e8SYuchung Cheng fo->cookie.len = 0; 3924783237e8SYuchung Cheng err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); 3925783237e8SYuchung Cheng if (err) 3926783237e8SYuchung Cheng tp->syn_fastopen = 0; 3927783237e8SYuchung Cheng done: 3928783237e8SYuchung Cheng fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ 3929783237e8SYuchung Cheng return err; 3930783237e8SYuchung Cheng } 3931783237e8SYuchung Cheng 393267edfef7SAndi Kleen /* Build a SYN and send it off. */ 39331da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 39341da177e4SLinus Torvalds { 39351da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 39361da177e4SLinus Torvalds struct sk_buff *buff; 3937ee586811SEric Paris int err; 39381da177e4SLinus Torvalds 3939de525be2SLawrence Brakmo tcp_call_bpf(sk, BPF_SOCK_OPS_TCP_CONNECT_CB, 0, NULL); 39408ba60924SEric Dumazet 39418ba60924SEric Dumazet if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 39428ba60924SEric Dumazet return -EHOSTUNREACH; /* Routing failure or similar. */ 39438ba60924SEric Dumazet 39441da177e4SLinus Torvalds tcp_connect_init(sk); 39451da177e4SLinus Torvalds 39462b916477SAndrey Vagin if (unlikely(tp->repair)) { 39472b916477SAndrey Vagin tcp_finish_connect(sk, NULL); 39482b916477SAndrey Vagin return 0; 39492b916477SAndrey Vagin } 39502b916477SAndrey Vagin 39515882efffSEric Dumazet buff = tcp_stream_alloc_skb(sk, sk->sk_allocation, true); 3952355a901eSEric Dumazet if (unlikely(!buff)) 39531da177e4SLinus Torvalds return -ENOBUFS; 39541da177e4SLinus Torvalds 3955a3433f35SChangli Gao tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); 39569a568de4SEric Dumazet tcp_mstamp_refresh(tp); 39579a568de4SEric Dumazet tp->retrans_stamp = tcp_time_stamp(tp); 3958783237e8SYuchung Cheng tcp_connect_queue_skb(sk, buff); 3959735d3831SFlorian Westphal tcp_ecn_send_syn(sk, buff); 396075c119afSEric Dumazet tcp_rbtree_insert(&sk->tcp_rtx_queue, buff); 39611da177e4SLinus Torvalds 3962783237e8SYuchung Cheng /* Send off SYN; include data in Fast Open. */ 3963783237e8SYuchung Cheng err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : 3964783237e8SYuchung Cheng tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); 3965ee586811SEric Paris if (err == -ECONNREFUSED) 3966ee586811SEric Paris return err; 3967bd37a088SWei Yongjun 3968bd37a088SWei Yongjun /* We change tp->snd_nxt after the tcp_transmit_skb() call 3969bd37a088SWei Yongjun * in order to make this packet get counted in tcpOutSegs. 3970bd37a088SWei Yongjun */ 3971e0d694d6SEric Dumazet WRITE_ONCE(tp->snd_nxt, tp->write_seq); 3972bd37a088SWei Yongjun tp->pushed_seq = tp->write_seq; 3973b5b7db8dSEric Dumazet buff = tcp_send_head(sk); 3974b5b7db8dSEric Dumazet if (unlikely(buff)) { 3975e0d694d6SEric Dumazet WRITE_ONCE(tp->snd_nxt, TCP_SKB_CB(buff)->seq); 3976b5b7db8dSEric Dumazet tp->pushed_seq = TCP_SKB_CB(buff)->seq; 3977b5b7db8dSEric Dumazet } 397881cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); 39791da177e4SLinus Torvalds 39801da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 39813f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 39823f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 39831da177e4SLinus Torvalds return 0; 39841da177e4SLinus Torvalds } 39854bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_connect); 39861da177e4SLinus Torvalds 39871da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 39881da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 39891da177e4SLinus Torvalds * for details. 39901da177e4SLinus Torvalds */ 39911da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 39921da177e4SLinus Torvalds { 3993463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 3994463c84b9SArnaldo Carvalho de Melo int ato = icsk->icsk_ack.ato; 39951da177e4SLinus Torvalds unsigned long timeout; 39961da177e4SLinus Torvalds 39971da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 3998463c84b9SArnaldo Carvalho de Melo const struct tcp_sock *tp = tcp_sk(sk); 39991da177e4SLinus Torvalds int max_ato = HZ / 2; 40001da177e4SLinus Torvalds 400131954cd8SWei Wang if (inet_csk_in_pingpong_mode(sk) || 4002056834d9SIlpo Järvinen (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) 40031da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 40041da177e4SLinus Torvalds 40051da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 40061da177e4SLinus Torvalds 40071da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 4008463c84b9SArnaldo Carvalho de Melo * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements 40091da177e4SLinus Torvalds * directly. 40101da177e4SLinus Torvalds */ 4011740b0f18SEric Dumazet if (tp->srtt_us) { 4012740b0f18SEric Dumazet int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3), 4013740b0f18SEric Dumazet TCP_DELACK_MIN); 40141da177e4SLinus Torvalds 40151da177e4SLinus Torvalds if (rtt < max_ato) 40161da177e4SLinus Torvalds max_ato = rtt; 40171da177e4SLinus Torvalds } 40181da177e4SLinus Torvalds 40191da177e4SLinus Torvalds ato = min(ato, max_ato); 40201da177e4SLinus Torvalds } 40211da177e4SLinus Torvalds 40222b8ee4f0SMartin KaFai Lau ato = min_t(u32, ato, inet_csk(sk)->icsk_delack_max); 40232b8ee4f0SMartin KaFai Lau 40241da177e4SLinus Torvalds /* Stay within the limit we were given */ 40251da177e4SLinus Torvalds timeout = jiffies + ato; 40261da177e4SLinus Torvalds 40271da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 4028463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 4029b6b6d653SEric Dumazet /* If delack timer is about to expire, send ACK now. */ 4030b6b6d653SEric Dumazet if (time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { 40311da177e4SLinus Torvalds tcp_send_ack(sk); 40321da177e4SLinus Torvalds return; 40331da177e4SLinus Torvalds } 40341da177e4SLinus Torvalds 4035463c84b9SArnaldo Carvalho de Melo if (!time_before(timeout, icsk->icsk_ack.timeout)) 4036463c84b9SArnaldo Carvalho de Melo timeout = icsk->icsk_ack.timeout; 40371da177e4SLinus Torvalds } 4038463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 4039463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.timeout = timeout; 4040463c84b9SArnaldo Carvalho de Melo sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 40411da177e4SLinus Torvalds } 40421da177e4SLinus Torvalds 40431da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 40442987babbSYuchung Cheng void __tcp_send_ack(struct sock *sk, u32 rcv_nxt) 40451da177e4SLinus Torvalds { 40461da177e4SLinus Torvalds struct sk_buff *buff; 40471da177e4SLinus Torvalds 4048058dc334SIlpo Järvinen /* If we have been reset, we may not send again. */ 4049058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 4050058dc334SIlpo Järvinen return; 4051058dc334SIlpo Järvinen 40521da177e4SLinus Torvalds /* We are not putting this on the write queue, so 40531da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 40541da177e4SLinus Torvalds * sock. 40551da177e4SLinus Torvalds */ 40567450aaf6SEric Dumazet buff = alloc_skb(MAX_TCP_HEADER, 40577450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 40587450aaf6SEric Dumazet if (unlikely(!buff)) { 4059a37c2134SEric Dumazet struct inet_connection_sock *icsk = inet_csk(sk); 4060a37c2134SEric Dumazet unsigned long delay; 4061a37c2134SEric Dumazet 4062a37c2134SEric Dumazet delay = TCP_DELACK_MAX << icsk->icsk_ack.retry; 4063a37c2134SEric Dumazet if (delay < TCP_RTO_MAX) 4064a37c2134SEric Dumazet icsk->icsk_ack.retry++; 4065463c84b9SArnaldo Carvalho de Melo inet_csk_schedule_ack(sk); 4066a37c2134SEric Dumazet icsk->icsk_ack.ato = TCP_ATO_MIN; 4067a37c2134SEric Dumazet inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, delay, TCP_RTO_MAX); 40681da177e4SLinus Torvalds return; 40691da177e4SLinus Torvalds } 40701da177e4SLinus Torvalds 40711da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 40721da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 4073a3433f35SChangli Gao tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); 40741da177e4SLinus Torvalds 407598781965SEric Dumazet /* We do not want pure acks influencing TCP Small Queues or fq/pacing 407698781965SEric Dumazet * too much. 407798781965SEric Dumazet * SKB_TRUESIZE(max(1 .. 66, MAX_TCP_HEADER)) is unfortunately ~784 407898781965SEric Dumazet */ 407998781965SEric Dumazet skb_set_tcp_pure_ack(buff); 408098781965SEric Dumazet 40811da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 40822987babbSYuchung Cheng __tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0, rcv_nxt); 40831da177e4SLinus Torvalds } 408427cde44aSYuchung Cheng EXPORT_SYMBOL_GPL(__tcp_send_ack); 40852987babbSYuchung Cheng 40862987babbSYuchung Cheng void tcp_send_ack(struct sock *sk) 40872987babbSYuchung Cheng { 40882987babbSYuchung Cheng __tcp_send_ack(sk, tcp_sk(sk)->rcv_nxt); 40891da177e4SLinus Torvalds } 40901da177e4SLinus Torvalds 40911da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 40921da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 40931da177e4SLinus Torvalds * 40941da177e4SLinus Torvalds * Question: what should we make while urgent mode? 40951da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 40961da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 40971da177e4SLinus Torvalds * 40981da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 40991da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 41001da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 41011da177e4SLinus Torvalds */ 4102e520af48SEric Dumazet static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib) 41031da177e4SLinus Torvalds { 41041da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 41051da177e4SLinus Torvalds struct sk_buff *skb; 41061da177e4SLinus Torvalds 41071da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 41087450aaf6SEric Dumazet skb = alloc_skb(MAX_TCP_HEADER, 41097450aaf6SEric Dumazet sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); 411051456b29SIan Morris if (!skb) 41111da177e4SLinus Torvalds return -1; 41121da177e4SLinus Torvalds 41131da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 41141da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 41151da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 41161da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 41171da177e4SLinus Torvalds * send it. 41181da177e4SLinus Torvalds */ 4119a3433f35SChangli Gao tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); 4120e2e8009fSRenato Westphal NET_INC_STATS(sock_net(sk), mib); 41217450aaf6SEric Dumazet return tcp_transmit_skb(sk, skb, 0, (__force gfp_t)0); 41221da177e4SLinus Torvalds } 41231da177e4SLinus Torvalds 4124385e2070SEric Dumazet /* Called from setsockopt( ... TCP_REPAIR ) */ 4125ee995283SPavel Emelyanov void tcp_send_window_probe(struct sock *sk) 4126ee995283SPavel Emelyanov { 4127ee995283SPavel Emelyanov if (sk->sk_state == TCP_ESTABLISHED) { 4128ee995283SPavel Emelyanov tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; 41299a568de4SEric Dumazet tcp_mstamp_refresh(tcp_sk(sk)); 4130e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE); 4131ee995283SPavel Emelyanov } 4132ee995283SPavel Emelyanov } 4133ee995283SPavel Emelyanov 413467edfef7SAndi Kleen /* Initiate keepalive or window probe from timer. */ 4135e520af48SEric Dumazet int tcp_write_wakeup(struct sock *sk, int mib) 41361da177e4SLinus Torvalds { 41371da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 41381da177e4SLinus Torvalds struct sk_buff *skb; 41391da177e4SLinus Torvalds 4140058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 4141058dc334SIlpo Järvinen return -1; 4142058dc334SIlpo Järvinen 414300db4124SIan Morris skb = tcp_send_head(sk); 414400db4124SIan Morris if (skb && before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { 41451da177e4SLinus Torvalds int err; 41460c54b85fSIlpo Järvinen unsigned int mss = tcp_current_mss(sk); 414790840defSIlpo Järvinen unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 41481da177e4SLinus Torvalds 41491da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 41501da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 41511da177e4SLinus Torvalds 41521da177e4SLinus Torvalds /* We are probing the opening of a window 41531da177e4SLinus Torvalds * but the window size is != 0 41541da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 41551da177e4SLinus Torvalds */ 41561da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 41571da177e4SLinus Torvalds skb->len > mss) { 41581da177e4SLinus Torvalds seg_size = min(seg_size, mss); 41594de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 416075c119afSEric Dumazet if (tcp_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE, 416175c119afSEric Dumazet skb, seg_size, mss, GFP_ATOMIC)) 41621da177e4SLinus Torvalds return -1; 41631da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 41645bbb432cSEric Dumazet tcp_set_skb_tso_segs(skb, mss); 41651da177e4SLinus Torvalds 41664de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 4167dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 416866f5fe62SIlpo Järvinen if (!err) 416966f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 41701da177e4SLinus Torvalds return err; 41711da177e4SLinus Torvalds } else { 417233f5f57eSIlpo Järvinen if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) 4173e520af48SEric Dumazet tcp_xmit_probe_skb(sk, 1, mib); 4174e520af48SEric Dumazet return tcp_xmit_probe_skb(sk, 0, mib); 41751da177e4SLinus Torvalds } 41761da177e4SLinus Torvalds } 41771da177e4SLinus Torvalds 41781da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 41791da177e4SLinus Torvalds * a partial packet else a zero probe. 41801da177e4SLinus Torvalds */ 41811da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 41821da177e4SLinus Torvalds { 4183463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 41841da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 4185c6214a97SNikolay Borisov struct net *net = sock_net(sk); 4186c1d5674fSYuchung Cheng unsigned long timeout; 41871da177e4SLinus Torvalds int err; 41881da177e4SLinus Torvalds 4189e520af48SEric Dumazet err = tcp_write_wakeup(sk, LINUX_MIB_TCPWINPROBE); 41901da177e4SLinus Torvalds 419175c119afSEric Dumazet if (tp->packets_out || tcp_write_queue_empty(sk)) { 41921da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 41936687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 0; 4194463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff = 0; 41959d9b1ee0SEnke Chen icsk->icsk_probes_tstamp = 0; 41961da177e4SLinus Torvalds return; 41971da177e4SLinus Torvalds } 41981da177e4SLinus Torvalds 4199c1d5674fSYuchung Cheng icsk->icsk_probes_out++; 42001da177e4SLinus Torvalds if (err <= 0) { 420139e24435SKuniyuki Iwashima if (icsk->icsk_backoff < READ_ONCE(net->ipv4.sysctl_tcp_retries2)) 4202463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff++; 4203c1d5674fSYuchung Cheng timeout = tcp_probe0_when(sk, TCP_RTO_MAX); 42041da177e4SLinus Torvalds } else { 42051da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 4206c1d5674fSYuchung Cheng * Let senders fight for local resources conservatively. 42071da177e4SLinus Torvalds */ 4208c1d5674fSYuchung Cheng timeout = TCP_RESOURCE_PROBE_INTERVAL; 42091da177e4SLinus Torvalds } 4210344db93aSEnke Chen 4211344db93aSEnke Chen timeout = tcp_clamp_probe0_to_user_timeout(sk, timeout); 42128dc242adSEric Dumazet tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, timeout, TCP_RTO_MAX); 42131da177e4SLinus Torvalds } 42145db92c99SOctavian Purdila 4215ea3bea3aSEric Dumazet int tcp_rtx_synack(const struct sock *sk, struct request_sock *req) 42165db92c99SOctavian Purdila { 42175db92c99SOctavian Purdila const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific; 42185db92c99SOctavian Purdila struct flowi fl; 42195db92c99SOctavian Purdila int res; 42205db92c99SOctavian Purdila 4221cb6cd2ceSAkhmat Karakotov /* Paired with WRITE_ONCE() in sock_setsockopt() */ 4222cb6cd2ceSAkhmat Karakotov if (READ_ONCE(sk->sk_txrehash) == SOCK_TXREHASH_ENABLED) 42235e526552SEric Dumazet WRITE_ONCE(tcp_rsk(req)->txhash, net_tx_rndhash()); 4224331fca43SMartin KaFai Lau res = af_ops->send_synack(sk, NULL, &fl, req, NULL, TCP_SYNACK_NORMAL, 4225331fca43SMartin KaFai Lau NULL); 42265db92c99SOctavian Purdila if (!res) { 42270a375c82SEric Dumazet TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); 42280a375c82SEric Dumazet NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); 4229e9d9da91SEric Dumazet if (unlikely(tcp_passive_fastopen(sk))) { 4230e9d9da91SEric Dumazet /* sk has const attribute because listeners are lockless. 4231e9d9da91SEric Dumazet * However in this case, we are dealing with a passive fastopen 4232e9d9da91SEric Dumazet * socket thus we can change total_retrans value. 4233e9d9da91SEric Dumazet */ 4234e9d9da91SEric Dumazet tcp_sk_rw(sk)->total_retrans++; 4235e9d9da91SEric Dumazet } 4236cf34ce3dSSong Liu trace_tcp_retransmit_synack(sk, req); 42375db92c99SOctavian Purdila } 42385db92c99SOctavian Purdila return res; 42395db92c99SOctavian Purdila } 42405db92c99SOctavian Purdila EXPORT_SYMBOL(tcp_rtx_synack); 4241