1 /* 2 * INET An implementation of the TCP/IP protocol suite for the LINUX 3 * operating system. INET is implemented using the BSD Socket 4 * interface as the means of communication with the user level. 5 * 6 * Definitions for the TCP module. 7 * 8 * Version: @(#)tcp.h 1.0.5 05/23/93 9 * 10 * Authors: Ross Biro 11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 12 * 13 * This program is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU General Public License 15 * as published by the Free Software Foundation; either version 16 * 2 of the License, or (at your option) any later version. 17 */ 18 #ifndef _TCP_H 19 #define _TCP_H 20 21 #define FASTRETRANS_DEBUG 1 22 23 #include <linux/list.h> 24 #include <linux/tcp.h> 25 #include <linux/bug.h> 26 #include <linux/slab.h> 27 #include <linux/cache.h> 28 #include <linux/percpu.h> 29 #include <linux/skbuff.h> 30 #include <linux/cryptohash.h> 31 #include <linux/kref.h> 32 #include <linux/ktime.h> 33 34 #include <net/inet_connection_sock.h> 35 #include <net/inet_timewait_sock.h> 36 #include <net/inet_hashtables.h> 37 #include <net/checksum.h> 38 #include <net/request_sock.h> 39 #include <net/sock.h> 40 #include <net/snmp.h> 41 #include <net/ip.h> 42 #include <net/tcp_states.h> 43 #include <net/inet_ecn.h> 44 #include <net/dst.h> 45 46 #include <linux/seq_file.h> 47 #include <linux/memcontrol.h> 48 #include <linux/bpf-cgroup.h> 49 50 extern struct inet_hashinfo tcp_hashinfo; 51 52 extern struct percpu_counter tcp_orphan_count; 53 void tcp_time_wait(struct sock *sk, int state, int timeo); 54 55 #define MAX_TCP_HEADER (128 + MAX_HEADER) 56 #define MAX_TCP_OPTION_SPACE 40 57 58 /* 59 * Never offer a window over 32767 without using window scaling. Some 60 * poor stacks do signed 16bit maths! 61 */ 62 #define MAX_TCP_WINDOW 32767U 63 64 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */ 65 #define TCP_MIN_MSS 88U 66 67 /* The least MTU to use for probing */ 68 #define TCP_BASE_MSS 1024 69 70 /* probing interval, default to 10 minutes as per RFC4821 */ 71 #define TCP_PROBE_INTERVAL 600 72 73 /* Specify interval when tcp mtu probing will stop */ 74 #define TCP_PROBE_THRESHOLD 8 75 76 /* After receiving this amount of duplicate ACKs fast retransmit starts. */ 77 #define TCP_FASTRETRANS_THRESH 3 78 79 /* Maximal number of ACKs sent quickly to accelerate slow-start. */ 80 #define TCP_MAX_QUICKACKS 16U 81 82 /* Maximal number of window scale according to RFC1323 */ 83 #define TCP_MAX_WSCALE 14U 84 85 /* urg_data states */ 86 #define TCP_URG_VALID 0x0100 87 #define TCP_URG_NOTYET 0x0200 88 #define TCP_URG_READ 0x0400 89 90 #define TCP_RETR1 3 /* 91 * This is how many retries it does before it 92 * tries to figure out if the gateway is 93 * down. Minimal RFC value is 3; it corresponds 94 * to ~3sec-8min depending on RTO. 95 */ 96 97 #define TCP_RETR2 15 /* 98 * This should take at least 99 * 90 minutes to time out. 100 * RFC1122 says that the limit is 100 sec. 101 * 15 is ~13-30min depending on RTO. 102 */ 103 104 #define TCP_SYN_RETRIES 6 /* This is how many retries are done 105 * when active opening a connection. 106 * RFC1122 says the minimum retry MUST 107 * be at least 180secs. Nevertheless 108 * this value is corresponding to 109 * 63secs of retransmission with the 110 * current initial RTO. 111 */ 112 113 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done 114 * when passive opening a connection. 115 * This is corresponding to 31secs of 116 * retransmission with the current 117 * initial RTO. 118 */ 119 120 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT 121 * state, about 60 seconds */ 122 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN 123 /* BSD style FIN_WAIT2 deadlock breaker. 124 * It used to be 3min, new value is 60sec, 125 * to combine FIN-WAIT-2 timeout with 126 * TIME-WAIT timer. 127 */ 128 129 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ 130 #if HZ >= 100 131 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */ 132 #define TCP_ATO_MIN ((unsigned)(HZ/25)) 133 #else 134 #define TCP_DELACK_MIN 4U 135 #define TCP_ATO_MIN 4U 136 #endif 137 #define TCP_RTO_MAX ((unsigned)(120*HZ)) 138 #define TCP_RTO_MIN ((unsigned)(HZ/5)) 139 #define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */ 140 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */ 141 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now 142 * used as a fallback RTO for the 143 * initial data transmission if no 144 * valid RTT sample has been acquired, 145 * most likely due to retrans in 3WHS. 146 */ 147 148 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes 149 * for local resources. 150 */ 151 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ 152 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ 153 #define TCP_KEEPALIVE_INTVL (75*HZ) 154 155 #define MAX_TCP_KEEPIDLE 32767 156 #define MAX_TCP_KEEPINTVL 32767 157 #define MAX_TCP_KEEPCNT 127 158 #define MAX_TCP_SYNCNT 127 159 160 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */ 161 162 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24) 163 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated 164 * after this time. It should be equal 165 * (or greater than) TCP_TIMEWAIT_LEN 166 * to provide reliability equal to one 167 * provided by timewait state. 168 */ 169 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host 170 * timestamps. It must be less than 171 * minimal timewait lifetime. 172 */ 173 /* 174 * TCP option 175 */ 176 177 #define TCPOPT_NOP 1 /* Padding */ 178 #define TCPOPT_EOL 0 /* End of options */ 179 #define TCPOPT_MSS 2 /* Segment size negotiating */ 180 #define TCPOPT_WINDOW 3 /* Window scaling */ 181 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ 182 #define TCPOPT_SACK 5 /* SACK Block */ 183 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ 184 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */ 185 #define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */ 186 #define TCPOPT_EXP 254 /* Experimental */ 187 /* Magic number to be after the option value for sharing TCP 188 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt 189 */ 190 #define TCPOPT_FASTOPEN_MAGIC 0xF989 191 #define TCPOPT_SMC_MAGIC 0xE2D4C3D9 192 193 /* 194 * TCP option lengths 195 */ 196 197 #define TCPOLEN_MSS 4 198 #define TCPOLEN_WINDOW 3 199 #define TCPOLEN_SACK_PERM 2 200 #define TCPOLEN_TIMESTAMP 10 201 #define TCPOLEN_MD5SIG 18 202 #define TCPOLEN_FASTOPEN_BASE 2 203 #define TCPOLEN_EXP_FASTOPEN_BASE 4 204 #define TCPOLEN_EXP_SMC_BASE 6 205 206 /* But this is what stacks really send out. */ 207 #define TCPOLEN_TSTAMP_ALIGNED 12 208 #define TCPOLEN_WSCALE_ALIGNED 4 209 #define TCPOLEN_SACKPERM_ALIGNED 4 210 #define TCPOLEN_SACK_BASE 2 211 #define TCPOLEN_SACK_BASE_ALIGNED 4 212 #define TCPOLEN_SACK_PERBLOCK 8 213 #define TCPOLEN_MD5SIG_ALIGNED 20 214 #define TCPOLEN_MSS_ALIGNED 4 215 #define TCPOLEN_EXP_SMC_BASE_ALIGNED 8 216 217 /* Flags in tp->nonagle */ 218 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */ 219 #define TCP_NAGLE_CORK 2 /* Socket is corked */ 220 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */ 221 222 /* TCP thin-stream limits */ 223 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */ 224 225 /* TCP initial congestion window as per rfc6928 */ 226 #define TCP_INIT_CWND 10 227 228 /* Bit Flags for sysctl_tcp_fastopen */ 229 #define TFO_CLIENT_ENABLE 1 230 #define TFO_SERVER_ENABLE 2 231 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */ 232 233 /* Accept SYN data w/o any cookie option */ 234 #define TFO_SERVER_COOKIE_NOT_REQD 0x200 235 236 /* Force enable TFO on all listeners, i.e., not requiring the 237 * TCP_FASTOPEN socket option. 238 */ 239 #define TFO_SERVER_WO_SOCKOPT1 0x400 240 241 242 /* sysctl variables for tcp */ 243 extern int sysctl_tcp_max_orphans; 244 extern long sysctl_tcp_mem[3]; 245 246 #define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */ 247 #define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */ 248 249 extern atomic_long_t tcp_memory_allocated; 250 extern struct percpu_counter tcp_sockets_allocated; 251 extern unsigned long tcp_memory_pressure; 252 253 /* optimized version of sk_under_memory_pressure() for TCP sockets */ 254 static inline bool tcp_under_memory_pressure(const struct sock *sk) 255 { 256 if (mem_cgroup_sockets_enabled && sk->sk_memcg && 257 mem_cgroup_under_socket_pressure(sk->sk_memcg)) 258 return true; 259 260 return tcp_memory_pressure; 261 } 262 /* 263 * The next routines deal with comparing 32 bit unsigned ints 264 * and worry about wraparound (automatic with unsigned arithmetic). 265 */ 266 267 static inline bool before(__u32 seq1, __u32 seq2) 268 { 269 return (__s32)(seq1-seq2) < 0; 270 } 271 #define after(seq2, seq1) before(seq1, seq2) 272 273 /* is s2<=s1<=s3 ? */ 274 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) 275 { 276 return seq3 - seq2 >= seq1 - seq2; 277 } 278 279 static inline bool tcp_out_of_memory(struct sock *sk) 280 { 281 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 282 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2)) 283 return true; 284 return false; 285 } 286 287 void sk_forced_mem_schedule(struct sock *sk, int size); 288 289 static inline bool tcp_too_many_orphans(struct sock *sk, int shift) 290 { 291 struct percpu_counter *ocp = sk->sk_prot->orphan_count; 292 int orphans = percpu_counter_read_positive(ocp); 293 294 if (orphans << shift > sysctl_tcp_max_orphans) { 295 orphans = percpu_counter_sum_positive(ocp); 296 if (orphans << shift > sysctl_tcp_max_orphans) 297 return true; 298 } 299 return false; 300 } 301 302 bool tcp_check_oom(struct sock *sk, int shift); 303 304 305 extern struct proto tcp_prot; 306 307 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 308 #define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field) 309 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 310 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 311 312 void tcp_tasklet_init(void); 313 314 void tcp_v4_err(struct sk_buff *skb, u32); 315 316 void tcp_shutdown(struct sock *sk, int how); 317 318 int tcp_v4_early_demux(struct sk_buff *skb); 319 int tcp_v4_rcv(struct sk_buff *skb); 320 321 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 322 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size); 323 int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size); 324 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, 325 int flags); 326 int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset, 327 size_t size, int flags); 328 ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset, 329 size_t size, int flags); 330 void tcp_release_cb(struct sock *sk); 331 void tcp_wfree(struct sk_buff *skb); 332 void tcp_write_timer_handler(struct sock *sk); 333 void tcp_delack_timer_handler(struct sock *sk); 334 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 335 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb); 336 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 337 const struct tcphdr *th); 338 void tcp_rcv_space_adjust(struct sock *sk); 339 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 340 void tcp_twsk_destructor(struct sock *sk); 341 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 342 struct pipe_inode_info *pipe, size_t len, 343 unsigned int flags); 344 345 static inline void tcp_dec_quickack_mode(struct sock *sk, 346 const unsigned int pkts) 347 { 348 struct inet_connection_sock *icsk = inet_csk(sk); 349 350 if (icsk->icsk_ack.quick) { 351 if (pkts >= icsk->icsk_ack.quick) { 352 icsk->icsk_ack.quick = 0; 353 /* Leaving quickack mode we deflate ATO. */ 354 icsk->icsk_ack.ato = TCP_ATO_MIN; 355 } else 356 icsk->icsk_ack.quick -= pkts; 357 } 358 } 359 360 #define TCP_ECN_OK 1 361 #define TCP_ECN_QUEUE_CWR 2 362 #define TCP_ECN_DEMAND_CWR 4 363 #define TCP_ECN_SEEN 8 364 365 enum tcp_tw_status { 366 TCP_TW_SUCCESS = 0, 367 TCP_TW_RST = 1, 368 TCP_TW_ACK = 2, 369 TCP_TW_SYN = 3 370 }; 371 372 373 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 374 struct sk_buff *skb, 375 const struct tcphdr *th); 376 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 377 struct request_sock *req, bool fastopen); 378 int tcp_child_process(struct sock *parent, struct sock *child, 379 struct sk_buff *skb); 380 void tcp_enter_loss(struct sock *sk); 381 void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int flag); 382 void tcp_clear_retrans(struct tcp_sock *tp); 383 void tcp_update_metrics(struct sock *sk); 384 void tcp_init_metrics(struct sock *sk); 385 void tcp_metrics_init(void); 386 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst); 387 void tcp_close(struct sock *sk, long timeout); 388 void tcp_init_sock(struct sock *sk); 389 void tcp_init_transfer(struct sock *sk, int bpf_op); 390 unsigned int tcp_poll(struct file *file, struct socket *sock, 391 struct poll_table_struct *wait); 392 int tcp_getsockopt(struct sock *sk, int level, int optname, 393 char __user *optval, int __user *optlen); 394 int tcp_setsockopt(struct sock *sk, int level, int optname, 395 char __user *optval, unsigned int optlen); 396 int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 397 char __user *optval, int __user *optlen); 398 int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 399 char __user *optval, unsigned int optlen); 400 void tcp_set_keepalive(struct sock *sk, int val); 401 void tcp_syn_ack_timeout(const struct request_sock *req); 402 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, 403 int flags, int *addr_len); 404 void tcp_parse_options(const struct net *net, const struct sk_buff *skb, 405 struct tcp_options_received *opt_rx, 406 int estab, struct tcp_fastopen_cookie *foc); 407 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); 408 409 /* 410 * TCP v4 functions exported for the inet6 API 411 */ 412 413 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 414 void tcp_v4_mtu_reduced(struct sock *sk); 415 void tcp_req_err(struct sock *sk, u32 seq, bool abort); 416 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 417 struct sock *tcp_create_openreq_child(const struct sock *sk, 418 struct request_sock *req, 419 struct sk_buff *skb); 420 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst); 421 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 422 struct request_sock *req, 423 struct dst_entry *dst, 424 struct request_sock *req_unhash, 425 bool *own_req); 426 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 427 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); 428 int tcp_connect(struct sock *sk); 429 enum tcp_synack_type { 430 TCP_SYNACK_NORMAL, 431 TCP_SYNACK_FASTOPEN, 432 TCP_SYNACK_COOKIE, 433 }; 434 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 435 struct request_sock *req, 436 struct tcp_fastopen_cookie *foc, 437 enum tcp_synack_type synack_type); 438 int tcp_disconnect(struct sock *sk, int flags); 439 440 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 441 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 442 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); 443 444 /* From syncookies.c */ 445 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, 446 struct request_sock *req, 447 struct dst_entry *dst, u32 tsoff); 448 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th, 449 u32 cookie); 450 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb); 451 #ifdef CONFIG_SYN_COOKIES 452 453 /* Syncookies use a monotonic timer which increments every 60 seconds. 454 * This counter is used both as a hash input and partially encoded into 455 * the cookie value. A cookie is only validated further if the delta 456 * between the current counter value and the encoded one is less than this, 457 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if 458 * the counter advances immediately after a cookie is generated). 459 */ 460 #define MAX_SYNCOOKIE_AGE 2 461 #define TCP_SYNCOOKIE_PERIOD (60 * HZ) 462 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD) 463 464 /* syncookies: remember time of last synqueue overflow 465 * But do not dirty this field too often (once per second is enough) 466 * It is racy as we do not hold a lock, but race is very minor. 467 */ 468 static inline void tcp_synq_overflow(const struct sock *sk) 469 { 470 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 471 unsigned long now = jiffies; 472 473 if (time_after(now, last_overflow + HZ)) 474 tcp_sk(sk)->rx_opt.ts_recent_stamp = now; 475 } 476 477 /* syncookies: no recent synqueue overflow on this listening socket? */ 478 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 479 { 480 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 481 482 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID); 483 } 484 485 static inline u32 tcp_cookie_time(void) 486 { 487 u64 val = get_jiffies_64(); 488 489 do_div(val, TCP_SYNCOOKIE_PERIOD); 490 return val; 491 } 492 493 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, 494 u16 *mssp); 495 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss); 496 u64 cookie_init_timestamp(struct request_sock *req); 497 bool cookie_timestamp_decode(const struct net *net, 498 struct tcp_options_received *opt); 499 bool cookie_ecn_ok(const struct tcp_options_received *opt, 500 const struct net *net, const struct dst_entry *dst); 501 502 /* From net/ipv6/syncookies.c */ 503 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th, 504 u32 cookie); 505 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 506 507 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph, 508 const struct tcphdr *th, u16 *mssp); 509 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss); 510 #endif 511 /* tcp_output.c */ 512 513 u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, 514 int min_tso_segs); 515 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 516 int nonagle); 517 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 518 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 519 void tcp_retransmit_timer(struct sock *sk); 520 void tcp_xmit_retransmit_queue(struct sock *); 521 void tcp_simple_retransmit(struct sock *); 522 void tcp_enter_recovery(struct sock *sk, bool ece_ack); 523 int tcp_trim_head(struct sock *, struct sk_buff *, u32); 524 enum tcp_queue { 525 TCP_FRAG_IN_WRITE_QUEUE, 526 TCP_FRAG_IN_RTX_QUEUE, 527 }; 528 int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, 529 struct sk_buff *skb, u32 len, 530 unsigned int mss_now, gfp_t gfp); 531 532 void tcp_send_probe0(struct sock *); 533 void tcp_send_partial(struct sock *); 534 int tcp_write_wakeup(struct sock *, int mib); 535 void tcp_send_fin(struct sock *sk); 536 void tcp_send_active_reset(struct sock *sk, gfp_t priority); 537 int tcp_send_synack(struct sock *); 538 void tcp_push_one(struct sock *, unsigned int mss_now); 539 void tcp_send_ack(struct sock *sk); 540 void tcp_send_delayed_ack(struct sock *sk); 541 void tcp_send_loss_probe(struct sock *sk); 542 bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto); 543 void tcp_skb_collapse_tstamp(struct sk_buff *skb, 544 const struct sk_buff *next_skb); 545 546 /* tcp_input.c */ 547 void tcp_rearm_rto(struct sock *sk); 548 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req); 549 void tcp_reset(struct sock *sk); 550 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb); 551 void tcp_fin(struct sock *sk); 552 553 /* tcp_timer.c */ 554 void tcp_init_xmit_timers(struct sock *); 555 static inline void tcp_clear_xmit_timers(struct sock *sk) 556 { 557 hrtimer_cancel(&tcp_sk(sk)->pacing_timer); 558 inet_csk_clear_xmit_timers(sk); 559 } 560 561 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 562 unsigned int tcp_current_mss(struct sock *sk); 563 564 /* Bound MSS / TSO packet size with the half of the window */ 565 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 566 { 567 int cutoff; 568 569 /* When peer uses tiny windows, there is no use in packetizing 570 * to sub-MSS pieces for the sake of SWS or making sure there 571 * are enough packets in the pipe for fast recovery. 572 * 573 * On the other hand, for extremely large MSS devices, handling 574 * smaller than MSS windows in this way does make sense. 575 */ 576 if (tp->max_window > TCP_MSS_DEFAULT) 577 cutoff = (tp->max_window >> 1); 578 else 579 cutoff = tp->max_window; 580 581 if (cutoff && pktsize > cutoff) 582 return max_t(int, cutoff, 68U - tp->tcp_header_len); 583 else 584 return pktsize; 585 } 586 587 /* tcp.c */ 588 void tcp_get_info(struct sock *, struct tcp_info *); 589 590 /* Read 'sendfile()'-style from a TCP socket */ 591 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 592 sk_read_actor_t recv_actor); 593 594 void tcp_initialize_rcv_mss(struct sock *sk); 595 596 int tcp_mtu_to_mss(struct sock *sk, int pmtu); 597 int tcp_mss_to_mtu(struct sock *sk, int mss); 598 void tcp_mtup_init(struct sock *sk); 599 void tcp_init_buffer_space(struct sock *sk); 600 601 static inline void tcp_bound_rto(const struct sock *sk) 602 { 603 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 604 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 605 } 606 607 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 608 { 609 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us); 610 } 611 612 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 613 { 614 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 615 ntohl(TCP_FLAG_ACK) | 616 snd_wnd); 617 } 618 619 static inline void tcp_fast_path_on(struct tcp_sock *tp) 620 { 621 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 622 } 623 624 static inline void tcp_fast_path_check(struct sock *sk) 625 { 626 struct tcp_sock *tp = tcp_sk(sk); 627 628 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) && 629 tp->rcv_wnd && 630 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 631 !tp->urg_data) 632 tcp_fast_path_on(tp); 633 } 634 635 /* Compute the actual rto_min value */ 636 static inline u32 tcp_rto_min(struct sock *sk) 637 { 638 const struct dst_entry *dst = __sk_dst_get(sk); 639 u32 rto_min = TCP_RTO_MIN; 640 641 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 642 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 643 return rto_min; 644 } 645 646 static inline u32 tcp_rto_min_us(struct sock *sk) 647 { 648 return jiffies_to_usecs(tcp_rto_min(sk)); 649 } 650 651 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst) 652 { 653 return dst_metric_locked(dst, RTAX_CC_ALGO); 654 } 655 656 /* Minimum RTT in usec. ~0 means not available. */ 657 static inline u32 tcp_min_rtt(const struct tcp_sock *tp) 658 { 659 return minmax_get(&tp->rtt_min); 660 } 661 662 /* Compute the actual receive window we are currently advertising. 663 * Rcv_nxt can be after the window if our peer push more data 664 * than the offered window. 665 */ 666 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 667 { 668 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 669 670 if (win < 0) 671 win = 0; 672 return (u32) win; 673 } 674 675 /* Choose a new window, without checks for shrinking, and without 676 * scaling applied to the result. The caller does these things 677 * if necessary. This is a "raw" window selection. 678 */ 679 u32 __tcp_select_window(struct sock *sk); 680 681 void tcp_send_window_probe(struct sock *sk); 682 683 /* TCP uses 32bit jiffies to save some space. 684 * Note that this is different from tcp_time_stamp, which 685 * historically has been the same until linux-4.13. 686 */ 687 #define tcp_jiffies32 ((u32)jiffies) 688 689 /* 690 * Deliver a 32bit value for TCP timestamp option (RFC 7323) 691 * It is no longer tied to jiffies, but to 1 ms clock. 692 * Note: double check if you want to use tcp_jiffies32 instead of this. 693 */ 694 #define TCP_TS_HZ 1000 695 696 static inline u64 tcp_clock_ns(void) 697 { 698 return local_clock(); 699 } 700 701 static inline u64 tcp_clock_us(void) 702 { 703 return div_u64(tcp_clock_ns(), NSEC_PER_USEC); 704 } 705 706 /* This should only be used in contexts where tp->tcp_mstamp is up to date */ 707 static inline u32 tcp_time_stamp(const struct tcp_sock *tp) 708 { 709 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ); 710 } 711 712 /* Could use tcp_clock_us() / 1000, but this version uses a single divide */ 713 static inline u32 tcp_time_stamp_raw(void) 714 { 715 return div_u64(tcp_clock_ns(), NSEC_PER_SEC / TCP_TS_HZ); 716 } 717 718 719 /* Refresh 1us clock of a TCP socket, 720 * ensuring monotically increasing values. 721 */ 722 static inline void tcp_mstamp_refresh(struct tcp_sock *tp) 723 { 724 u64 val = tcp_clock_us(); 725 726 if (val > tp->tcp_mstamp) 727 tp->tcp_mstamp = val; 728 } 729 730 static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0) 731 { 732 return max_t(s64, t1 - t0, 0); 733 } 734 735 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) 736 { 737 return div_u64(skb->skb_mstamp, USEC_PER_SEC / TCP_TS_HZ); 738 } 739 740 741 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 742 743 #define TCPHDR_FIN 0x01 744 #define TCPHDR_SYN 0x02 745 #define TCPHDR_RST 0x04 746 #define TCPHDR_PSH 0x08 747 #define TCPHDR_ACK 0x10 748 #define TCPHDR_URG 0x20 749 #define TCPHDR_ECE 0x40 750 #define TCPHDR_CWR 0x80 751 752 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) 753 754 /* This is what the send packet queuing engine uses to pass 755 * TCP per-packet control information to the transmission code. 756 * We also store the host-order sequence numbers in here too. 757 * This is 44 bytes if IPV6 is enabled. 758 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 759 */ 760 struct tcp_skb_cb { 761 __u32 seq; /* Starting sequence number */ 762 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 763 union { 764 /* Note : tcp_tw_isn is used in input path only 765 * (isn chosen by tcp_timewait_state_process()) 766 * 767 * tcp_gso_segs/size are used in write queue only, 768 * cf tcp_skb_pcount()/tcp_skb_mss() 769 */ 770 __u32 tcp_tw_isn; 771 struct { 772 u16 tcp_gso_segs; 773 u16 tcp_gso_size; 774 }; 775 }; 776 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 777 778 __u8 sacked; /* State flags for SACK. */ 779 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 780 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 781 #define TCPCB_LOST 0x04 /* SKB is lost */ 782 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 783 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */ 784 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 785 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \ 786 TCPCB_REPAIRED) 787 788 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 789 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */ 790 eor:1, /* Is skb MSG_EOR marked? */ 791 has_rxtstamp:1, /* SKB has a RX timestamp */ 792 unused:5; 793 __u32 ack_seq; /* Sequence number ACK'd */ 794 union { 795 struct { 796 /* There is space for up to 24 bytes */ 797 __u32 in_flight:30,/* Bytes in flight at transmit */ 798 is_app_limited:1, /* cwnd not fully used? */ 799 unused:1; 800 /* pkts S/ACKed so far upon tx of skb, incl retrans: */ 801 __u32 delivered; 802 /* start of send pipeline phase */ 803 u64 first_tx_mstamp; 804 /* when we reached the "delivered" count */ 805 u64 delivered_mstamp; 806 } tx; /* only used for outgoing skbs */ 807 union { 808 struct inet_skb_parm h4; 809 #if IS_ENABLED(CONFIG_IPV6) 810 struct inet6_skb_parm h6; 811 #endif 812 } header; /* For incoming skbs */ 813 struct { 814 __u32 key; 815 __u32 flags; 816 struct bpf_map *map; 817 void *data_end; 818 } bpf; 819 }; 820 }; 821 822 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 823 824 825 #if IS_ENABLED(CONFIG_IPV6) 826 /* This is the variant of inet6_iif() that must be used by TCP, 827 * as TCP moves IP6CB into a different location in skb->cb[] 828 */ 829 static inline int tcp_v6_iif(const struct sk_buff *skb) 830 { 831 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags); 832 833 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif; 834 } 835 836 /* TCP_SKB_CB reference means this can not be used from early demux */ 837 static inline int tcp_v6_sdif(const struct sk_buff *skb) 838 { 839 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 840 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags)) 841 return TCP_SKB_CB(skb)->header.h6.iif; 842 #endif 843 return 0; 844 } 845 #endif 846 847 static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb) 848 { 849 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 850 if (!net->ipv4.sysctl_tcp_l3mdev_accept && 851 skb && ipv4_l3mdev_skb(IPCB(skb)->flags)) 852 return true; 853 #endif 854 return false; 855 } 856 857 /* TCP_SKB_CB reference means this can not be used from early demux */ 858 static inline int tcp_v4_sdif(struct sk_buff *skb) 859 { 860 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 861 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags)) 862 return TCP_SKB_CB(skb)->header.h4.iif; 863 #endif 864 return 0; 865 } 866 867 /* Due to TSO, an SKB can be composed of multiple actual 868 * packets. To keep these tracked properly, we use this. 869 */ 870 static inline int tcp_skb_pcount(const struct sk_buff *skb) 871 { 872 return TCP_SKB_CB(skb)->tcp_gso_segs; 873 } 874 875 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 876 { 877 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 878 } 879 880 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 881 { 882 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 883 } 884 885 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ 886 static inline int tcp_skb_mss(const struct sk_buff *skb) 887 { 888 return TCP_SKB_CB(skb)->tcp_gso_size; 889 } 890 891 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb) 892 { 893 return likely(!TCP_SKB_CB(skb)->eor); 894 } 895 896 /* Events passed to congestion control interface */ 897 enum tcp_ca_event { 898 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 899 CA_EVENT_CWND_RESTART, /* congestion window restart */ 900 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 901 CA_EVENT_LOSS, /* loss timeout */ 902 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 903 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 904 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */ 905 CA_EVENT_NON_DELAYED_ACK, 906 }; 907 908 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 909 enum tcp_ca_ack_event_flags { 910 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 911 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 912 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 913 }; 914 915 /* 916 * Interface for adding new TCP congestion control handlers 917 */ 918 #define TCP_CA_NAME_MAX 16 919 #define TCP_CA_MAX 128 920 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 921 922 #define TCP_CA_UNSPEC 0 923 924 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 925 #define TCP_CONG_NON_RESTRICTED 0x1 926 /* Requires ECN/ECT set on all packets */ 927 #define TCP_CONG_NEEDS_ECN 0x2 928 929 union tcp_cc_info; 930 931 struct ack_sample { 932 u32 pkts_acked; 933 s32 rtt_us; 934 u32 in_flight; 935 }; 936 937 /* A rate sample measures the number of (original/retransmitted) data 938 * packets delivered "delivered" over an interval of time "interval_us". 939 * The tcp_rate.c code fills in the rate sample, and congestion 940 * control modules that define a cong_control function to run at the end 941 * of ACK processing can optionally chose to consult this sample when 942 * setting cwnd and pacing rate. 943 * A sample is invalid if "delivered" or "interval_us" is negative. 944 */ 945 struct rate_sample { 946 u64 prior_mstamp; /* starting timestamp for interval */ 947 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */ 948 s32 delivered; /* number of packets delivered over interval */ 949 long interval_us; /* time for tp->delivered to incr "delivered" */ 950 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */ 951 int losses; /* number of packets marked lost upon ACK */ 952 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */ 953 u32 prior_in_flight; /* in flight before this ACK */ 954 bool is_app_limited; /* is sample from packet with bubble in pipe? */ 955 bool is_retrans; /* is sample from retransmission? */ 956 }; 957 958 struct tcp_congestion_ops { 959 struct list_head list; 960 u32 key; 961 u32 flags; 962 963 /* initialize private data (optional) */ 964 void (*init)(struct sock *sk); 965 /* cleanup private data (optional) */ 966 void (*release)(struct sock *sk); 967 968 /* return slow start threshold (required) */ 969 u32 (*ssthresh)(struct sock *sk); 970 /* do new cwnd calculation (required) */ 971 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 972 /* call before changing ca_state (optional) */ 973 void (*set_state)(struct sock *sk, u8 new_state); 974 /* call when cwnd event occurs (optional) */ 975 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 976 /* call when ack arrives (optional) */ 977 void (*in_ack_event)(struct sock *sk, u32 flags); 978 /* new value of cwnd after loss (required) */ 979 u32 (*undo_cwnd)(struct sock *sk); 980 /* hook for packet ack accounting (optional) */ 981 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample); 982 /* suggest number of segments for each skb to transmit (optional) */ 983 u32 (*tso_segs_goal)(struct sock *sk); 984 /* returns the multiplier used in tcp_sndbuf_expand (optional) */ 985 u32 (*sndbuf_expand)(struct sock *sk); 986 /* call when packets are delivered to update cwnd and pacing rate, 987 * after all the ca_state processing. (optional) 988 */ 989 void (*cong_control)(struct sock *sk, const struct rate_sample *rs); 990 /* get info for inet_diag (optional) */ 991 size_t (*get_info)(struct sock *sk, u32 ext, int *attr, 992 union tcp_cc_info *info); 993 994 char name[TCP_CA_NAME_MAX]; 995 struct module *owner; 996 }; 997 998 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 999 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 1000 1001 void tcp_assign_congestion_control(struct sock *sk); 1002 void tcp_init_congestion_control(struct sock *sk); 1003 void tcp_cleanup_congestion_control(struct sock *sk); 1004 int tcp_set_default_congestion_control(struct net *net, const char *name); 1005 void tcp_get_default_congestion_control(struct net *net, char *name); 1006 void tcp_get_available_congestion_control(char *buf, size_t len); 1007 void tcp_get_allowed_congestion_control(char *buf, size_t len); 1008 int tcp_set_allowed_congestion_control(char *allowed); 1009 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, bool reinit); 1010 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); 1011 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); 1012 1013 u32 tcp_reno_ssthresh(struct sock *sk); 1014 u32 tcp_reno_undo_cwnd(struct sock *sk); 1015 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 1016 extern struct tcp_congestion_ops tcp_reno; 1017 1018 struct tcp_congestion_ops *tcp_ca_find_key(u32 key); 1019 u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca); 1020 #ifdef CONFIG_INET 1021 char *tcp_ca_get_name_by_key(u32 key, char *buffer); 1022 #else 1023 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) 1024 { 1025 return NULL; 1026 } 1027 #endif 1028 1029 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 1030 { 1031 const struct inet_connection_sock *icsk = inet_csk(sk); 1032 1033 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 1034 } 1035 1036 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 1037 { 1038 struct inet_connection_sock *icsk = inet_csk(sk); 1039 1040 if (icsk->icsk_ca_ops->set_state) 1041 icsk->icsk_ca_ops->set_state(sk, ca_state); 1042 icsk->icsk_ca_state = ca_state; 1043 } 1044 1045 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 1046 { 1047 const struct inet_connection_sock *icsk = inet_csk(sk); 1048 1049 if (icsk->icsk_ca_ops->cwnd_event) 1050 icsk->icsk_ca_ops->cwnd_event(sk, event); 1051 } 1052 1053 /* From tcp_rate.c */ 1054 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb); 1055 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb, 1056 struct rate_sample *rs); 1057 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost, 1058 bool is_sack_reneg, struct rate_sample *rs); 1059 void tcp_rate_check_app_limited(struct sock *sk); 1060 1061 /* These functions determine how the current flow behaves in respect of SACK 1062 * handling. SACK is negotiated with the peer, and therefore it can vary 1063 * between different flows. 1064 * 1065 * tcp_is_sack - SACK enabled 1066 * tcp_is_reno - No SACK 1067 */ 1068 static inline int tcp_is_sack(const struct tcp_sock *tp) 1069 { 1070 return tp->rx_opt.sack_ok; 1071 } 1072 1073 static inline bool tcp_is_reno(const struct tcp_sock *tp) 1074 { 1075 return !tcp_is_sack(tp); 1076 } 1077 1078 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 1079 { 1080 return tp->sacked_out + tp->lost_out; 1081 } 1082 1083 /* This determines how many packets are "in the network" to the best 1084 * of our knowledge. In many cases it is conservative, but where 1085 * detailed information is available from the receiver (via SACK 1086 * blocks etc.) we can make more aggressive calculations. 1087 * 1088 * Use this for decisions involving congestion control, use just 1089 * tp->packets_out to determine if the send queue is empty or not. 1090 * 1091 * Read this equation as: 1092 * 1093 * "Packets sent once on transmission queue" MINUS 1094 * "Packets left network, but not honestly ACKed yet" PLUS 1095 * "Packets fast retransmitted" 1096 */ 1097 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 1098 { 1099 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 1100 } 1101 1102 #define TCP_INFINITE_SSTHRESH 0x7fffffff 1103 1104 static inline bool tcp_in_slow_start(const struct tcp_sock *tp) 1105 { 1106 return tp->snd_cwnd < tp->snd_ssthresh; 1107 } 1108 1109 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 1110 { 1111 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 1112 } 1113 1114 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 1115 { 1116 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 1117 (1 << inet_csk(sk)->icsk_ca_state); 1118 } 1119 1120 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 1121 * The exception is cwnd reduction phase, when cwnd is decreasing towards 1122 * ssthresh. 1123 */ 1124 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 1125 { 1126 const struct tcp_sock *tp = tcp_sk(sk); 1127 1128 if (tcp_in_cwnd_reduction(sk)) 1129 return tp->snd_ssthresh; 1130 else 1131 return max(tp->snd_ssthresh, 1132 ((tp->snd_cwnd >> 1) + 1133 (tp->snd_cwnd >> 2))); 1134 } 1135 1136 /* Use define here intentionally to get WARN_ON location shown at the caller */ 1137 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 1138 1139 void tcp_enter_cwr(struct sock *sk); 1140 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 1141 1142 /* The maximum number of MSS of available cwnd for which TSO defers 1143 * sending if not using sysctl_tcp_tso_win_divisor. 1144 */ 1145 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 1146 { 1147 return 3; 1148 } 1149 1150 /* Returns end sequence number of the receiver's advertised window */ 1151 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 1152 { 1153 return tp->snd_una + tp->snd_wnd; 1154 } 1155 1156 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 1157 * flexible approach. The RFC suggests cwnd should not be raised unless 1158 * it was fully used previously. And that's exactly what we do in 1159 * congestion avoidance mode. But in slow start we allow cwnd to grow 1160 * as long as the application has used half the cwnd. 1161 * Example : 1162 * cwnd is 10 (IW10), but application sends 9 frames. 1163 * We allow cwnd to reach 18 when all frames are ACKed. 1164 * This check is safe because it's as aggressive as slow start which already 1165 * risks 100% overshoot. The advantage is that we discourage application to 1166 * either send more filler packets or data to artificially blow up the cwnd 1167 * usage, and allow application-limited process to probe bw more aggressively. 1168 */ 1169 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1170 { 1171 const struct tcp_sock *tp = tcp_sk(sk); 1172 1173 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1174 if (tcp_in_slow_start(tp)) 1175 return tp->snd_cwnd < 2 * tp->max_packets_out; 1176 1177 return tp->is_cwnd_limited; 1178 } 1179 1180 /* Something is really bad, we could not queue an additional packet, 1181 * because qdisc is full or receiver sent a 0 window. 1182 * We do not want to add fuel to the fire, or abort too early, 1183 * so make sure the timer we arm now is at least 200ms in the future, 1184 * regardless of current icsk_rto value (as it could be ~2ms) 1185 */ 1186 static inline unsigned long tcp_probe0_base(const struct sock *sk) 1187 { 1188 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); 1189 } 1190 1191 /* Variant of inet_csk_rto_backoff() used for zero window probes */ 1192 static inline unsigned long tcp_probe0_when(const struct sock *sk, 1193 unsigned long max_when) 1194 { 1195 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff; 1196 1197 return (unsigned long)min_t(u64, when, max_when); 1198 } 1199 1200 static inline void tcp_check_probe_timer(struct sock *sk) 1201 { 1202 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) 1203 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1204 tcp_probe0_base(sk), TCP_RTO_MAX); 1205 } 1206 1207 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1208 { 1209 tp->snd_wl1 = seq; 1210 } 1211 1212 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1213 { 1214 tp->snd_wl1 = seq; 1215 } 1216 1217 /* 1218 * Calculate(/check) TCP checksum 1219 */ 1220 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1221 __be32 daddr, __wsum base) 1222 { 1223 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1224 } 1225 1226 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1227 { 1228 return __skb_checksum_complete(skb); 1229 } 1230 1231 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1232 { 1233 return !skb_csum_unnecessary(skb) && 1234 __tcp_checksum_complete(skb); 1235 } 1236 1237 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb); 1238 int tcp_filter(struct sock *sk, struct sk_buff *skb); 1239 1240 #undef STATE_TRACE 1241 1242 #ifdef STATE_TRACE 1243 static const char *statename[]={ 1244 "Unused","Established","Syn Sent","Syn Recv", 1245 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1246 "Close Wait","Last ACK","Listen","Closing" 1247 }; 1248 #endif 1249 void tcp_set_state(struct sock *sk, int state); 1250 1251 void tcp_done(struct sock *sk); 1252 1253 int tcp_abort(struct sock *sk, int err); 1254 1255 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1256 { 1257 rx_opt->dsack = 0; 1258 rx_opt->num_sacks = 0; 1259 } 1260 1261 u32 tcp_default_init_rwnd(u32 mss); 1262 void tcp_cwnd_restart(struct sock *sk, s32 delta); 1263 1264 static inline void tcp_slow_start_after_idle_check(struct sock *sk) 1265 { 1266 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1267 struct tcp_sock *tp = tcp_sk(sk); 1268 s32 delta; 1269 1270 if (!sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle || tp->packets_out || 1271 ca_ops->cong_control) 1272 return; 1273 delta = tcp_jiffies32 - tp->lsndtime; 1274 if (delta > inet_csk(sk)->icsk_rto) 1275 tcp_cwnd_restart(sk, delta); 1276 } 1277 1278 /* Determine a window scaling and initial window to offer. */ 1279 void tcp_select_initial_window(const struct sock *sk, int __space, 1280 __u32 mss, __u32 *rcv_wnd, 1281 __u32 *window_clamp, int wscale_ok, 1282 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1283 1284 static inline int tcp_win_from_space(const struct sock *sk, int space) 1285 { 1286 int tcp_adv_win_scale = sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale; 1287 1288 return tcp_adv_win_scale <= 0 ? 1289 (space>>(-tcp_adv_win_scale)) : 1290 space - (space>>tcp_adv_win_scale); 1291 } 1292 1293 /* Note: caller must be prepared to deal with negative returns */ 1294 static inline int tcp_space(const struct sock *sk) 1295 { 1296 return tcp_win_from_space(sk, sk->sk_rcvbuf - 1297 atomic_read(&sk->sk_rmem_alloc)); 1298 } 1299 1300 static inline int tcp_full_space(const struct sock *sk) 1301 { 1302 return tcp_win_from_space(sk, sk->sk_rcvbuf); 1303 } 1304 1305 extern void tcp_openreq_init_rwin(struct request_sock *req, 1306 const struct sock *sk_listener, 1307 const struct dst_entry *dst); 1308 1309 void tcp_enter_memory_pressure(struct sock *sk); 1310 void tcp_leave_memory_pressure(struct sock *sk); 1311 1312 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1313 { 1314 struct net *net = sock_net((struct sock *)tp); 1315 1316 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl; 1317 } 1318 1319 static inline int keepalive_time_when(const struct tcp_sock *tp) 1320 { 1321 struct net *net = sock_net((struct sock *)tp); 1322 1323 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time; 1324 } 1325 1326 static inline int keepalive_probes(const struct tcp_sock *tp) 1327 { 1328 struct net *net = sock_net((struct sock *)tp); 1329 1330 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes; 1331 } 1332 1333 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1334 { 1335 const struct inet_connection_sock *icsk = &tp->inet_conn; 1336 1337 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime, 1338 tcp_jiffies32 - tp->rcv_tstamp); 1339 } 1340 1341 static inline int tcp_fin_time(const struct sock *sk) 1342 { 1343 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout; 1344 const int rto = inet_csk(sk)->icsk_rto; 1345 1346 if (fin_timeout < (rto << 2) - (rto >> 1)) 1347 fin_timeout = (rto << 2) - (rto >> 1); 1348 1349 return fin_timeout; 1350 } 1351 1352 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1353 int paws_win) 1354 { 1355 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1356 return true; 1357 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1358 return true; 1359 /* 1360 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1361 * then following tcp messages have valid values. Ignore 0 value, 1362 * or else 'negative' tsval might forbid us to accept their packets. 1363 */ 1364 if (!rx_opt->ts_recent) 1365 return true; 1366 return false; 1367 } 1368 1369 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1370 int rst) 1371 { 1372 if (tcp_paws_check(rx_opt, 0)) 1373 return false; 1374 1375 /* RST segments are not recommended to carry timestamp, 1376 and, if they do, it is recommended to ignore PAWS because 1377 "their cleanup function should take precedence over timestamps." 1378 Certainly, it is mistake. It is necessary to understand the reasons 1379 of this constraint to relax it: if peer reboots, clock may go 1380 out-of-sync and half-open connections will not be reset. 1381 Actually, the problem would be not existing if all 1382 the implementations followed draft about maintaining clock 1383 via reboots. Linux-2.2 DOES NOT! 1384 1385 However, we can relax time bounds for RST segments to MSL. 1386 */ 1387 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1388 return false; 1389 return true; 1390 } 1391 1392 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, 1393 int mib_idx, u32 *last_oow_ack_time); 1394 1395 static inline void tcp_mib_init(struct net *net) 1396 { 1397 /* See RFC 2012 */ 1398 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1); 1399 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1400 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1401 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1); 1402 } 1403 1404 /* from STCP */ 1405 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1406 { 1407 tp->lost_skb_hint = NULL; 1408 } 1409 1410 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1411 { 1412 tcp_clear_retrans_hints_partial(tp); 1413 tp->retransmit_skb_hint = NULL; 1414 } 1415 1416 union tcp_md5_addr { 1417 struct in_addr a4; 1418 #if IS_ENABLED(CONFIG_IPV6) 1419 struct in6_addr a6; 1420 #endif 1421 }; 1422 1423 /* - key database */ 1424 struct tcp_md5sig_key { 1425 struct hlist_node node; 1426 u8 keylen; 1427 u8 family; /* AF_INET or AF_INET6 */ 1428 union tcp_md5_addr addr; 1429 u8 prefixlen; 1430 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1431 struct rcu_head rcu; 1432 }; 1433 1434 /* - sock block */ 1435 struct tcp_md5sig_info { 1436 struct hlist_head head; 1437 struct rcu_head rcu; 1438 }; 1439 1440 /* - pseudo header */ 1441 struct tcp4_pseudohdr { 1442 __be32 saddr; 1443 __be32 daddr; 1444 __u8 pad; 1445 __u8 protocol; 1446 __be16 len; 1447 }; 1448 1449 struct tcp6_pseudohdr { 1450 struct in6_addr saddr; 1451 struct in6_addr daddr; 1452 __be32 len; 1453 __be32 protocol; /* including padding */ 1454 }; 1455 1456 union tcp_md5sum_block { 1457 struct tcp4_pseudohdr ip4; 1458 #if IS_ENABLED(CONFIG_IPV6) 1459 struct tcp6_pseudohdr ip6; 1460 #endif 1461 }; 1462 1463 /* - pool: digest algorithm, hash description and scratch buffer */ 1464 struct tcp_md5sig_pool { 1465 struct ahash_request *md5_req; 1466 void *scratch; 1467 }; 1468 1469 /* - functions */ 1470 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1471 const struct sock *sk, const struct sk_buff *skb); 1472 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1473 int family, u8 prefixlen, const u8 *newkey, u8 newkeylen, 1474 gfp_t gfp); 1475 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1476 int family, u8 prefixlen); 1477 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 1478 const struct sock *addr_sk); 1479 1480 #ifdef CONFIG_TCP_MD5SIG 1481 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1482 const union tcp_md5_addr *addr, 1483 int family); 1484 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1485 #else 1486 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1487 const union tcp_md5_addr *addr, 1488 int family) 1489 { 1490 return NULL; 1491 } 1492 #define tcp_twsk_md5_key(twsk) NULL 1493 #endif 1494 1495 bool tcp_alloc_md5sig_pool(void); 1496 1497 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1498 static inline void tcp_put_md5sig_pool(void) 1499 { 1500 local_bh_enable(); 1501 } 1502 1503 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1504 unsigned int header_len); 1505 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1506 const struct tcp_md5sig_key *key); 1507 1508 /* From tcp_fastopen.c */ 1509 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1510 struct tcp_fastopen_cookie *cookie, int *syn_loss, 1511 unsigned long *last_syn_loss); 1512 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1513 struct tcp_fastopen_cookie *cookie, bool syn_lost, 1514 u16 try_exp); 1515 struct tcp_fastopen_request { 1516 /* Fast Open cookie. Size 0 means a cookie request */ 1517 struct tcp_fastopen_cookie cookie; 1518 struct msghdr *data; /* data in MSG_FASTOPEN */ 1519 size_t size; 1520 int copied; /* queued in tcp_connect() */ 1521 }; 1522 void tcp_free_fastopen_req(struct tcp_sock *tp); 1523 void tcp_fastopen_destroy_cipher(struct sock *sk); 1524 void tcp_fastopen_ctx_destroy(struct net *net); 1525 int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk, 1526 void *key, unsigned int len); 1527 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb); 1528 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1529 struct request_sock *req, 1530 struct tcp_fastopen_cookie *foc, 1531 const struct dst_entry *dst); 1532 void tcp_fastopen_init_key_once(struct net *net); 1533 bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss, 1534 struct tcp_fastopen_cookie *cookie); 1535 bool tcp_fastopen_defer_connect(struct sock *sk, int *err); 1536 #define TCP_FASTOPEN_KEY_LENGTH 16 1537 1538 /* Fastopen key context */ 1539 struct tcp_fastopen_context { 1540 struct crypto_cipher *tfm; 1541 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1542 struct rcu_head rcu; 1543 }; 1544 1545 extern unsigned int sysctl_tcp_fastopen_blackhole_timeout; 1546 void tcp_fastopen_active_disable(struct sock *sk); 1547 bool tcp_fastopen_active_should_disable(struct sock *sk); 1548 void tcp_fastopen_active_disable_ofo_check(struct sock *sk); 1549 void tcp_fastopen_active_timeout_reset(void); 1550 1551 /* Latencies incurred by various limits for a sender. They are 1552 * chronograph-like stats that are mutually exclusive. 1553 */ 1554 enum tcp_chrono { 1555 TCP_CHRONO_UNSPEC, 1556 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */ 1557 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */ 1558 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */ 1559 __TCP_CHRONO_MAX, 1560 }; 1561 1562 void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type); 1563 void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type); 1564 1565 /* This helper is needed, because skb->tcp_tsorted_anchor uses 1566 * the same memory storage than skb->destructor/_skb_refdst 1567 */ 1568 static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb) 1569 { 1570 skb->destructor = NULL; 1571 skb->_skb_refdst = 0UL; 1572 } 1573 1574 #define tcp_skb_tsorted_save(skb) { \ 1575 unsigned long _save = skb->_skb_refdst; \ 1576 skb->_skb_refdst = 0UL; 1577 1578 #define tcp_skb_tsorted_restore(skb) \ 1579 skb->_skb_refdst = _save; \ 1580 } 1581 1582 void tcp_write_queue_purge(struct sock *sk); 1583 1584 static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk) 1585 { 1586 return skb_rb_first(&sk->tcp_rtx_queue); 1587 } 1588 1589 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1590 { 1591 return skb_peek(&sk->sk_write_queue); 1592 } 1593 1594 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1595 { 1596 return skb_peek_tail(&sk->sk_write_queue); 1597 } 1598 1599 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1600 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1601 1602 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1603 { 1604 return skb_peek(&sk->sk_write_queue); 1605 } 1606 1607 static inline bool tcp_skb_is_last(const struct sock *sk, 1608 const struct sk_buff *skb) 1609 { 1610 return skb_queue_is_last(&sk->sk_write_queue, skb); 1611 } 1612 1613 static inline bool tcp_write_queue_empty(const struct sock *sk) 1614 { 1615 return skb_queue_empty(&sk->sk_write_queue); 1616 } 1617 1618 static inline bool tcp_rtx_queue_empty(const struct sock *sk) 1619 { 1620 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue); 1621 } 1622 1623 static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk) 1624 { 1625 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk); 1626 } 1627 1628 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1629 { 1630 if (tcp_write_queue_empty(sk)) 1631 tcp_chrono_stop(sk, TCP_CHRONO_BUSY); 1632 } 1633 1634 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1635 { 1636 __skb_queue_tail(&sk->sk_write_queue, skb); 1637 } 1638 1639 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1640 { 1641 __tcp_add_write_queue_tail(sk, skb); 1642 1643 /* Queue it, remembering where we must start sending. */ 1644 if (sk->sk_write_queue.next == skb) 1645 tcp_chrono_start(sk, TCP_CHRONO_BUSY); 1646 } 1647 1648 /* Insert new before skb on the write queue of sk. */ 1649 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1650 struct sk_buff *skb, 1651 struct sock *sk) 1652 { 1653 __skb_queue_before(&sk->sk_write_queue, skb, new); 1654 } 1655 1656 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1657 { 1658 tcp_skb_tsorted_anchor_cleanup(skb); 1659 __skb_unlink(skb, &sk->sk_write_queue); 1660 } 1661 1662 void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb); 1663 1664 static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk) 1665 { 1666 tcp_skb_tsorted_anchor_cleanup(skb); 1667 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue); 1668 } 1669 1670 static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk) 1671 { 1672 list_del(&skb->tcp_tsorted_anchor); 1673 tcp_rtx_queue_unlink(skb, sk); 1674 sk_wmem_free_skb(sk, skb); 1675 } 1676 1677 static inline void tcp_push_pending_frames(struct sock *sk) 1678 { 1679 if (tcp_send_head(sk)) { 1680 struct tcp_sock *tp = tcp_sk(sk); 1681 1682 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1683 } 1684 } 1685 1686 /* Start sequence of the skb just after the highest skb with SACKed 1687 * bit, valid only if sacked_out > 0 or when the caller has ensured 1688 * validity by itself. 1689 */ 1690 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1691 { 1692 if (!tp->sacked_out) 1693 return tp->snd_una; 1694 1695 if (tp->highest_sack == NULL) 1696 return tp->snd_nxt; 1697 1698 return TCP_SKB_CB(tp->highest_sack)->seq; 1699 } 1700 1701 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1702 { 1703 tcp_sk(sk)->highest_sack = skb_rb_next(skb); 1704 } 1705 1706 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1707 { 1708 return tcp_sk(sk)->highest_sack; 1709 } 1710 1711 static inline void tcp_highest_sack_reset(struct sock *sk) 1712 { 1713 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk); 1714 } 1715 1716 /* Called when old skb is about to be deleted and replaced by new skb */ 1717 static inline void tcp_highest_sack_replace(struct sock *sk, 1718 struct sk_buff *old, 1719 struct sk_buff *new) 1720 { 1721 if (old == tcp_highest_sack(sk)) 1722 tcp_sk(sk)->highest_sack = new; 1723 } 1724 1725 /* This helper checks if socket has IP_TRANSPARENT set */ 1726 static inline bool inet_sk_transparent(const struct sock *sk) 1727 { 1728 switch (sk->sk_state) { 1729 case TCP_TIME_WAIT: 1730 return inet_twsk(sk)->tw_transparent; 1731 case TCP_NEW_SYN_RECV: 1732 return inet_rsk(inet_reqsk(sk))->no_srccheck; 1733 } 1734 return inet_sk(sk)->transparent; 1735 } 1736 1737 /* Determines whether this is a thin stream (which may suffer from 1738 * increased latency). Used to trigger latency-reducing mechanisms. 1739 */ 1740 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1741 { 1742 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1743 } 1744 1745 /* /proc */ 1746 enum tcp_seq_states { 1747 TCP_SEQ_STATE_LISTENING, 1748 TCP_SEQ_STATE_ESTABLISHED, 1749 }; 1750 1751 int tcp_seq_open(struct inode *inode, struct file *file); 1752 1753 struct tcp_seq_afinfo { 1754 char *name; 1755 sa_family_t family; 1756 const struct file_operations *seq_fops; 1757 struct seq_operations seq_ops; 1758 }; 1759 1760 struct tcp_iter_state { 1761 struct seq_net_private p; 1762 sa_family_t family; 1763 enum tcp_seq_states state; 1764 struct sock *syn_wait_sk; 1765 int bucket, offset, sbucket, num; 1766 loff_t last_pos; 1767 }; 1768 1769 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1770 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1771 1772 extern struct request_sock_ops tcp_request_sock_ops; 1773 extern struct request_sock_ops tcp6_request_sock_ops; 1774 1775 void tcp_v4_destroy_sock(struct sock *sk); 1776 1777 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 1778 netdev_features_t features); 1779 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb); 1780 int tcp_gro_complete(struct sk_buff *skb); 1781 1782 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 1783 1784 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 1785 { 1786 struct net *net = sock_net((struct sock *)tp); 1787 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat; 1788 } 1789 1790 static inline bool tcp_stream_memory_free(const struct sock *sk) 1791 { 1792 const struct tcp_sock *tp = tcp_sk(sk); 1793 u32 notsent_bytes = tp->write_seq - tp->snd_nxt; 1794 1795 return notsent_bytes < tcp_notsent_lowat(tp); 1796 } 1797 1798 #ifdef CONFIG_PROC_FS 1799 int tcp4_proc_init(void); 1800 void tcp4_proc_exit(void); 1801 #endif 1802 1803 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req); 1804 int tcp_conn_request(struct request_sock_ops *rsk_ops, 1805 const struct tcp_request_sock_ops *af_ops, 1806 struct sock *sk, struct sk_buff *skb); 1807 1808 /* TCP af-specific functions */ 1809 struct tcp_sock_af_ops { 1810 #ifdef CONFIG_TCP_MD5SIG 1811 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk, 1812 const struct sock *addr_sk); 1813 int (*calc_md5_hash)(char *location, 1814 const struct tcp_md5sig_key *md5, 1815 const struct sock *sk, 1816 const struct sk_buff *skb); 1817 int (*md5_parse)(struct sock *sk, 1818 int optname, 1819 char __user *optval, 1820 int optlen); 1821 #endif 1822 }; 1823 1824 struct tcp_request_sock_ops { 1825 u16 mss_clamp; 1826 #ifdef CONFIG_TCP_MD5SIG 1827 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk, 1828 const struct sock *addr_sk); 1829 int (*calc_md5_hash) (char *location, 1830 const struct tcp_md5sig_key *md5, 1831 const struct sock *sk, 1832 const struct sk_buff *skb); 1833 #endif 1834 void (*init_req)(struct request_sock *req, 1835 const struct sock *sk_listener, 1836 struct sk_buff *skb); 1837 #ifdef CONFIG_SYN_COOKIES 1838 __u32 (*cookie_init_seq)(const struct sk_buff *skb, 1839 __u16 *mss); 1840 #endif 1841 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl, 1842 const struct request_sock *req); 1843 u32 (*init_seq)(const struct sk_buff *skb); 1844 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb); 1845 int (*send_synack)(const struct sock *sk, struct dst_entry *dst, 1846 struct flowi *fl, struct request_sock *req, 1847 struct tcp_fastopen_cookie *foc, 1848 enum tcp_synack_type synack_type); 1849 }; 1850 1851 #ifdef CONFIG_SYN_COOKIES 1852 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1853 const struct sock *sk, struct sk_buff *skb, 1854 __u16 *mss) 1855 { 1856 tcp_synq_overflow(sk); 1857 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); 1858 return ops->cookie_init_seq(skb, mss); 1859 } 1860 #else 1861 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1862 const struct sock *sk, struct sk_buff *skb, 1863 __u16 *mss) 1864 { 1865 return 0; 1866 } 1867 #endif 1868 1869 int tcpv4_offload_init(void); 1870 1871 void tcp_v4_init(void); 1872 void tcp_init(void); 1873 1874 /* tcp_recovery.c */ 1875 extern void tcp_rack_mark_lost(struct sock *sk); 1876 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq, 1877 u64 xmit_time); 1878 extern void tcp_rack_reo_timeout(struct sock *sk); 1879 extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs); 1880 1881 /* At how many usecs into the future should the RTO fire? */ 1882 static inline s64 tcp_rto_delta_us(const struct sock *sk) 1883 { 1884 const struct sk_buff *skb = tcp_rtx_queue_head(sk); 1885 u32 rto = inet_csk(sk)->icsk_rto; 1886 u64 rto_time_stamp_us = skb->skb_mstamp + jiffies_to_usecs(rto); 1887 1888 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp; 1889 } 1890 1891 /* 1892 * Save and compile IPv4 options, return a pointer to it 1893 */ 1894 static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net, 1895 struct sk_buff *skb) 1896 { 1897 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; 1898 struct ip_options_rcu *dopt = NULL; 1899 1900 if (opt->optlen) { 1901 int opt_size = sizeof(*dopt) + opt->optlen; 1902 1903 dopt = kmalloc(opt_size, GFP_ATOMIC); 1904 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) { 1905 kfree(dopt); 1906 dopt = NULL; 1907 } 1908 } 1909 return dopt; 1910 } 1911 1912 /* locally generated TCP pure ACKs have skb->truesize == 2 1913 * (check tcp_send_ack() in net/ipv4/tcp_output.c ) 1914 * This is much faster than dissecting the packet to find out. 1915 * (Think of GRE encapsulations, IPv4, IPv6, ...) 1916 */ 1917 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb) 1918 { 1919 return skb->truesize == 2; 1920 } 1921 1922 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb) 1923 { 1924 skb->truesize = 2; 1925 } 1926 1927 static inline int tcp_inq(struct sock *sk) 1928 { 1929 struct tcp_sock *tp = tcp_sk(sk); 1930 int answ; 1931 1932 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { 1933 answ = 0; 1934 } else if (sock_flag(sk, SOCK_URGINLINE) || 1935 !tp->urg_data || 1936 before(tp->urg_seq, tp->copied_seq) || 1937 !before(tp->urg_seq, tp->rcv_nxt)) { 1938 1939 answ = tp->rcv_nxt - tp->copied_seq; 1940 1941 /* Subtract 1, if FIN was received */ 1942 if (answ && sock_flag(sk, SOCK_DONE)) 1943 answ--; 1944 } else { 1945 answ = tp->urg_seq - tp->copied_seq; 1946 } 1947 1948 return answ; 1949 } 1950 1951 int tcp_peek_len(struct socket *sock); 1952 1953 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb) 1954 { 1955 u16 segs_in; 1956 1957 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs); 1958 tp->segs_in += segs_in; 1959 if (skb->len > tcp_hdrlen(skb)) 1960 tp->data_segs_in += segs_in; 1961 } 1962 1963 /* 1964 * TCP listen path runs lockless. 1965 * We forced "struct sock" to be const qualified to make sure 1966 * we don't modify one of its field by mistake. 1967 * Here, we increment sk_drops which is an atomic_t, so we can safely 1968 * make sock writable again. 1969 */ 1970 static inline void tcp_listendrop(const struct sock *sk) 1971 { 1972 atomic_inc(&((struct sock *)sk)->sk_drops); 1973 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 1974 } 1975 1976 enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer); 1977 1978 /* 1979 * Interface for adding Upper Level Protocols over TCP 1980 */ 1981 1982 #define TCP_ULP_NAME_MAX 16 1983 #define TCP_ULP_MAX 128 1984 #define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX) 1985 1986 struct tcp_ulp_ops { 1987 struct list_head list; 1988 1989 /* initialize ulp */ 1990 int (*init)(struct sock *sk); 1991 /* cleanup ulp */ 1992 void (*release)(struct sock *sk); 1993 1994 char name[TCP_ULP_NAME_MAX]; 1995 struct module *owner; 1996 }; 1997 int tcp_register_ulp(struct tcp_ulp_ops *type); 1998 void tcp_unregister_ulp(struct tcp_ulp_ops *type); 1999 int tcp_set_ulp(struct sock *sk, const char *name); 2000 void tcp_get_available_ulp(char *buf, size_t len); 2001 void tcp_cleanup_ulp(struct sock *sk); 2002 2003 /* Call BPF_SOCK_OPS program that returns an int. If the return value 2004 * is < 0, then the BPF op failed (for example if the loaded BPF 2005 * program does not support the chosen operation or there is no BPF 2006 * program loaded). 2007 */ 2008 #ifdef CONFIG_BPF 2009 static inline int tcp_call_bpf(struct sock *sk, int op) 2010 { 2011 struct bpf_sock_ops_kern sock_ops; 2012 int ret; 2013 2014 if (sk_fullsock(sk)) 2015 sock_owned_by_me(sk); 2016 2017 memset(&sock_ops, 0, sizeof(sock_ops)); 2018 sock_ops.sk = sk; 2019 sock_ops.op = op; 2020 2021 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops); 2022 if (ret == 0) 2023 ret = sock_ops.reply; 2024 else 2025 ret = -1; 2026 return ret; 2027 } 2028 #else 2029 static inline int tcp_call_bpf(struct sock *sk, int op) 2030 { 2031 return -EPERM; 2032 } 2033 #endif 2034 2035 static inline u32 tcp_timeout_init(struct sock *sk) 2036 { 2037 int timeout; 2038 2039 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT); 2040 2041 if (timeout <= 0) 2042 timeout = TCP_TIMEOUT_INIT; 2043 return timeout; 2044 } 2045 2046 static inline u32 tcp_rwnd_init_bpf(struct sock *sk) 2047 { 2048 int rwnd; 2049 2050 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT); 2051 2052 if (rwnd < 0) 2053 rwnd = 0; 2054 return rwnd; 2055 } 2056 2057 static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk) 2058 { 2059 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN) == 1); 2060 } 2061 2062 #if IS_ENABLED(CONFIG_SMC) 2063 extern struct static_key_false tcp_have_smc; 2064 #endif 2065 #endif /* _TCP_H */ 2066