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/crypto.h> 31 #include <linux/cryptohash.h> 32 #include <linux/kref.h> 33 #include <linux/ktime.h> 34 35 #include <net/inet_connection_sock.h> 36 #include <net/inet_timewait_sock.h> 37 #include <net/inet_hashtables.h> 38 #include <net/checksum.h> 39 #include <net/request_sock.h> 40 #include <net/sock.h> 41 #include <net/snmp.h> 42 #include <net/ip.h> 43 #include <net/tcp_states.h> 44 #include <net/inet_ecn.h> 45 #include <net/dst.h> 46 47 #include <linux/seq_file.h> 48 #include <linux/memcontrol.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 /* urg_data states */ 83 #define TCP_URG_VALID 0x0100 84 #define TCP_URG_NOTYET 0x0200 85 #define TCP_URG_READ 0x0400 86 87 #define TCP_RETR1 3 /* 88 * This is how many retries it does before it 89 * tries to figure out if the gateway is 90 * down. Minimal RFC value is 3; it corresponds 91 * to ~3sec-8min depending on RTO. 92 */ 93 94 #define TCP_RETR2 15 /* 95 * This should take at least 96 * 90 minutes to time out. 97 * RFC1122 says that the limit is 100 sec. 98 * 15 is ~13-30min depending on RTO. 99 */ 100 101 #define TCP_SYN_RETRIES 6 /* This is how many retries are done 102 * when active opening a connection. 103 * RFC1122 says the minimum retry MUST 104 * be at least 180secs. Nevertheless 105 * this value is corresponding to 106 * 63secs of retransmission with the 107 * current initial RTO. 108 */ 109 110 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done 111 * when passive opening a connection. 112 * This is corresponding to 31secs of 113 * retransmission with the current 114 * initial RTO. 115 */ 116 117 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT 118 * state, about 60 seconds */ 119 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN 120 /* BSD style FIN_WAIT2 deadlock breaker. 121 * It used to be 3min, new value is 60sec, 122 * to combine FIN-WAIT-2 timeout with 123 * TIME-WAIT timer. 124 */ 125 126 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ 127 #if HZ >= 100 128 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */ 129 #define TCP_ATO_MIN ((unsigned)(HZ/25)) 130 #else 131 #define TCP_DELACK_MIN 4U 132 #define TCP_ATO_MIN 4U 133 #endif 134 #define TCP_RTO_MAX ((unsigned)(120*HZ)) 135 #define TCP_RTO_MIN ((unsigned)(HZ/5)) 136 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */ 137 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now 138 * used as a fallback RTO for the 139 * initial data transmission if no 140 * valid RTT sample has been acquired, 141 * most likely due to retrans in 3WHS. 142 */ 143 144 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes 145 * for local resources. 146 */ 147 148 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ 149 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ 150 #define TCP_KEEPALIVE_INTVL (75*HZ) 151 152 #define MAX_TCP_KEEPIDLE 32767 153 #define MAX_TCP_KEEPINTVL 32767 154 #define MAX_TCP_KEEPCNT 127 155 #define MAX_TCP_SYNCNT 127 156 157 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */ 158 159 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24) 160 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated 161 * after this time. It should be equal 162 * (or greater than) TCP_TIMEWAIT_LEN 163 * to provide reliability equal to one 164 * provided by timewait state. 165 */ 166 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host 167 * timestamps. It must be less than 168 * minimal timewait lifetime. 169 */ 170 /* 171 * TCP option 172 */ 173 174 #define TCPOPT_NOP 1 /* Padding */ 175 #define TCPOPT_EOL 0 /* End of options */ 176 #define TCPOPT_MSS 2 /* Segment size negotiating */ 177 #define TCPOPT_WINDOW 3 /* Window scaling */ 178 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ 179 #define TCPOPT_SACK 5 /* SACK Block */ 180 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ 181 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */ 182 #define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */ 183 #define TCPOPT_EXP 254 /* Experimental */ 184 /* Magic number to be after the option value for sharing TCP 185 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt 186 */ 187 #define TCPOPT_FASTOPEN_MAGIC 0xF989 188 189 /* 190 * TCP option lengths 191 */ 192 193 #define TCPOLEN_MSS 4 194 #define TCPOLEN_WINDOW 3 195 #define TCPOLEN_SACK_PERM 2 196 #define TCPOLEN_TIMESTAMP 10 197 #define TCPOLEN_MD5SIG 18 198 #define TCPOLEN_FASTOPEN_BASE 2 199 #define TCPOLEN_EXP_FASTOPEN_BASE 4 200 201 /* But this is what stacks really send out. */ 202 #define TCPOLEN_TSTAMP_ALIGNED 12 203 #define TCPOLEN_WSCALE_ALIGNED 4 204 #define TCPOLEN_SACKPERM_ALIGNED 4 205 #define TCPOLEN_SACK_BASE 2 206 #define TCPOLEN_SACK_BASE_ALIGNED 4 207 #define TCPOLEN_SACK_PERBLOCK 8 208 #define TCPOLEN_MD5SIG_ALIGNED 20 209 #define TCPOLEN_MSS_ALIGNED 4 210 211 /* Flags in tp->nonagle */ 212 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */ 213 #define TCP_NAGLE_CORK 2 /* Socket is corked */ 214 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */ 215 216 /* TCP thin-stream limits */ 217 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */ 218 219 /* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */ 220 #define TCP_INIT_CWND 10 221 222 /* Bit Flags for sysctl_tcp_fastopen */ 223 #define TFO_CLIENT_ENABLE 1 224 #define TFO_SERVER_ENABLE 2 225 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */ 226 227 /* Accept SYN data w/o any cookie option */ 228 #define TFO_SERVER_COOKIE_NOT_REQD 0x200 229 230 /* Force enable TFO on all listeners, i.e., not requiring the 231 * TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen. 232 */ 233 #define TFO_SERVER_WO_SOCKOPT1 0x400 234 #define TFO_SERVER_WO_SOCKOPT2 0x800 235 236 extern struct inet_timewait_death_row tcp_death_row; 237 238 /* sysctl variables for tcp */ 239 extern int sysctl_tcp_timestamps; 240 extern int sysctl_tcp_window_scaling; 241 extern int sysctl_tcp_sack; 242 extern int sysctl_tcp_fin_timeout; 243 extern int sysctl_tcp_keepalive_time; 244 extern int sysctl_tcp_keepalive_probes; 245 extern int sysctl_tcp_keepalive_intvl; 246 extern int sysctl_tcp_syn_retries; 247 extern int sysctl_tcp_synack_retries; 248 extern int sysctl_tcp_retries1; 249 extern int sysctl_tcp_retries2; 250 extern int sysctl_tcp_orphan_retries; 251 extern int sysctl_tcp_syncookies; 252 extern int sysctl_tcp_fastopen; 253 extern int sysctl_tcp_retrans_collapse; 254 extern int sysctl_tcp_stdurg; 255 extern int sysctl_tcp_rfc1337; 256 extern int sysctl_tcp_abort_on_overflow; 257 extern int sysctl_tcp_max_orphans; 258 extern int sysctl_tcp_fack; 259 extern int sysctl_tcp_reordering; 260 extern int sysctl_tcp_max_reordering; 261 extern int sysctl_tcp_dsack; 262 extern long sysctl_tcp_mem[3]; 263 extern int sysctl_tcp_wmem[3]; 264 extern int sysctl_tcp_rmem[3]; 265 extern int sysctl_tcp_app_win; 266 extern int sysctl_tcp_adv_win_scale; 267 extern int sysctl_tcp_tw_reuse; 268 extern int sysctl_tcp_frto; 269 extern int sysctl_tcp_low_latency; 270 extern int sysctl_tcp_nometrics_save; 271 extern int sysctl_tcp_moderate_rcvbuf; 272 extern int sysctl_tcp_tso_win_divisor; 273 extern int sysctl_tcp_workaround_signed_windows; 274 extern int sysctl_tcp_slow_start_after_idle; 275 extern int sysctl_tcp_thin_linear_timeouts; 276 extern int sysctl_tcp_thin_dupack; 277 extern int sysctl_tcp_early_retrans; 278 extern int sysctl_tcp_limit_output_bytes; 279 extern int sysctl_tcp_challenge_ack_limit; 280 extern unsigned int sysctl_tcp_notsent_lowat; 281 extern int sysctl_tcp_min_tso_segs; 282 extern int sysctl_tcp_autocorking; 283 extern int sysctl_tcp_invalid_ratelimit; 284 extern int sysctl_tcp_pacing_ss_ratio; 285 extern int sysctl_tcp_pacing_ca_ratio; 286 287 extern atomic_long_t tcp_memory_allocated; 288 extern struct percpu_counter tcp_sockets_allocated; 289 extern int tcp_memory_pressure; 290 291 /* optimized version of sk_under_memory_pressure() for TCP sockets */ 292 static inline bool tcp_under_memory_pressure(const struct sock *sk) 293 { 294 if (mem_cgroup_sockets_enabled && sk->sk_cgrp) 295 return !!sk->sk_cgrp->memory_pressure; 296 297 return tcp_memory_pressure; 298 } 299 /* 300 * The next routines deal with comparing 32 bit unsigned ints 301 * and worry about wraparound (automatic with unsigned arithmetic). 302 */ 303 304 static inline bool before(__u32 seq1, __u32 seq2) 305 { 306 return (__s32)(seq1-seq2) < 0; 307 } 308 #define after(seq2, seq1) before(seq1, seq2) 309 310 /* is s2<=s1<=s3 ? */ 311 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) 312 { 313 return seq3 - seq2 >= seq1 - seq2; 314 } 315 316 static inline bool tcp_out_of_memory(struct sock *sk) 317 { 318 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 319 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2)) 320 return true; 321 return false; 322 } 323 324 void sk_forced_mem_schedule(struct sock *sk, int size); 325 326 static inline bool tcp_too_many_orphans(struct sock *sk, int shift) 327 { 328 struct percpu_counter *ocp = sk->sk_prot->orphan_count; 329 int orphans = percpu_counter_read_positive(ocp); 330 331 if (orphans << shift > sysctl_tcp_max_orphans) { 332 orphans = percpu_counter_sum_positive(ocp); 333 if (orphans << shift > sysctl_tcp_max_orphans) 334 return true; 335 } 336 return false; 337 } 338 339 bool tcp_check_oom(struct sock *sk, int shift); 340 341 342 extern struct proto tcp_prot; 343 344 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 345 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field) 346 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 347 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val) 348 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 349 350 void tcp_tasklet_init(void); 351 352 void tcp_v4_err(struct sk_buff *skb, u32); 353 354 void tcp_shutdown(struct sock *sk, int how); 355 356 void tcp_v4_early_demux(struct sk_buff *skb); 357 int tcp_v4_rcv(struct sk_buff *skb); 358 359 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 360 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size); 361 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, 362 int flags); 363 void tcp_release_cb(struct sock *sk); 364 void tcp_wfree(struct sk_buff *skb); 365 void tcp_write_timer_handler(struct sock *sk); 366 void tcp_delack_timer_handler(struct sock *sk); 367 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 368 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb); 369 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 370 const struct tcphdr *th, unsigned int len); 371 void tcp_rcv_space_adjust(struct sock *sk); 372 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 373 void tcp_twsk_destructor(struct sock *sk); 374 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 375 struct pipe_inode_info *pipe, size_t len, 376 unsigned int flags); 377 378 static inline void tcp_dec_quickack_mode(struct sock *sk, 379 const unsigned int pkts) 380 { 381 struct inet_connection_sock *icsk = inet_csk(sk); 382 383 if (icsk->icsk_ack.quick) { 384 if (pkts >= icsk->icsk_ack.quick) { 385 icsk->icsk_ack.quick = 0; 386 /* Leaving quickack mode we deflate ATO. */ 387 icsk->icsk_ack.ato = TCP_ATO_MIN; 388 } else 389 icsk->icsk_ack.quick -= pkts; 390 } 391 } 392 393 #define TCP_ECN_OK 1 394 #define TCP_ECN_QUEUE_CWR 2 395 #define TCP_ECN_DEMAND_CWR 4 396 #define TCP_ECN_SEEN 8 397 398 enum tcp_tw_status { 399 TCP_TW_SUCCESS = 0, 400 TCP_TW_RST = 1, 401 TCP_TW_ACK = 2, 402 TCP_TW_SYN = 3 403 }; 404 405 406 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 407 struct sk_buff *skb, 408 const struct tcphdr *th); 409 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 410 struct request_sock *req, bool fastopen); 411 int tcp_child_process(struct sock *parent, struct sock *child, 412 struct sk_buff *skb); 413 void tcp_enter_loss(struct sock *sk); 414 void tcp_clear_retrans(struct tcp_sock *tp); 415 void tcp_update_metrics(struct sock *sk); 416 void tcp_init_metrics(struct sock *sk); 417 void tcp_metrics_init(void); 418 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, 419 bool paws_check, bool timestamps); 420 bool tcp_remember_stamp(struct sock *sk); 421 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw); 422 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst); 423 void tcp_disable_fack(struct tcp_sock *tp); 424 void tcp_close(struct sock *sk, long timeout); 425 void tcp_init_sock(struct sock *sk); 426 unsigned int tcp_poll(struct file *file, struct socket *sock, 427 struct poll_table_struct *wait); 428 int tcp_getsockopt(struct sock *sk, int level, int optname, 429 char __user *optval, int __user *optlen); 430 int tcp_setsockopt(struct sock *sk, int level, int optname, 431 char __user *optval, unsigned int optlen); 432 int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 433 char __user *optval, int __user *optlen); 434 int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 435 char __user *optval, unsigned int optlen); 436 void tcp_set_keepalive(struct sock *sk, int val); 437 void tcp_syn_ack_timeout(const struct request_sock *req); 438 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, 439 int flags, int *addr_len); 440 void tcp_parse_options(const struct sk_buff *skb, 441 struct tcp_options_received *opt_rx, 442 int estab, struct tcp_fastopen_cookie *foc); 443 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); 444 445 /* 446 * TCP v4 functions exported for the inet6 API 447 */ 448 449 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 450 void tcp_v4_mtu_reduced(struct sock *sk); 451 void tcp_req_err(struct sock *sk, u32 seq); 452 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 453 struct sock *tcp_create_openreq_child(const struct sock *sk, 454 struct request_sock *req, 455 struct sk_buff *skb); 456 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst); 457 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 458 struct request_sock *req, 459 struct dst_entry *dst); 460 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 461 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); 462 int tcp_connect(struct sock *sk); 463 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 464 struct request_sock *req, 465 struct tcp_fastopen_cookie *foc, 466 bool attach_req); 467 int tcp_disconnect(struct sock *sk, int flags); 468 469 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 470 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 471 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); 472 473 /* From syncookies.c */ 474 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, 475 struct request_sock *req, 476 struct dst_entry *dst); 477 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th, 478 u32 cookie); 479 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb); 480 #ifdef CONFIG_SYN_COOKIES 481 482 /* Syncookies use a monotonic timer which increments every 60 seconds. 483 * This counter is used both as a hash input and partially encoded into 484 * the cookie value. A cookie is only validated further if the delta 485 * between the current counter value and the encoded one is less than this, 486 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if 487 * the counter advances immediately after a cookie is generated). 488 */ 489 #define MAX_SYNCOOKIE_AGE 2 490 #define TCP_SYNCOOKIE_PERIOD (60 * HZ) 491 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD) 492 493 /* syncookies: remember time of last synqueue overflow 494 * But do not dirty this field too often (once per second is enough) 495 * It is racy as we do not hold a lock, but race is very minor. 496 */ 497 static inline void tcp_synq_overflow(const struct sock *sk) 498 { 499 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 500 unsigned long now = jiffies; 501 502 if (time_after(now, last_overflow + HZ)) 503 tcp_sk(sk)->rx_opt.ts_recent_stamp = now; 504 } 505 506 /* syncookies: no recent synqueue overflow on this listening socket? */ 507 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 508 { 509 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 510 511 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID); 512 } 513 514 static inline u32 tcp_cookie_time(void) 515 { 516 u64 val = get_jiffies_64(); 517 518 do_div(val, TCP_SYNCOOKIE_PERIOD); 519 return val; 520 } 521 522 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, 523 u16 *mssp); 524 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss); 525 __u32 cookie_init_timestamp(struct request_sock *req); 526 bool cookie_timestamp_decode(struct tcp_options_received *opt); 527 bool cookie_ecn_ok(const struct tcp_options_received *opt, 528 const struct net *net, const struct dst_entry *dst); 529 530 /* From net/ipv6/syncookies.c */ 531 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th, 532 u32 cookie); 533 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 534 535 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph, 536 const struct tcphdr *th, u16 *mssp); 537 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss); 538 #endif 539 /* tcp_output.c */ 540 541 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 542 int nonagle); 543 bool tcp_may_send_now(struct sock *sk); 544 int __tcp_retransmit_skb(struct sock *, struct sk_buff *); 545 int tcp_retransmit_skb(struct sock *, struct sk_buff *); 546 void tcp_retransmit_timer(struct sock *sk); 547 void tcp_xmit_retransmit_queue(struct sock *); 548 void tcp_simple_retransmit(struct sock *); 549 int tcp_trim_head(struct sock *, struct sk_buff *, u32); 550 int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t); 551 552 void tcp_send_probe0(struct sock *); 553 void tcp_send_partial(struct sock *); 554 int tcp_write_wakeup(struct sock *, int mib); 555 void tcp_send_fin(struct sock *sk); 556 void tcp_send_active_reset(struct sock *sk, gfp_t priority); 557 int tcp_send_synack(struct sock *); 558 void tcp_push_one(struct sock *, unsigned int mss_now); 559 void tcp_send_ack(struct sock *sk); 560 void tcp_send_delayed_ack(struct sock *sk); 561 void tcp_send_loss_probe(struct sock *sk); 562 bool tcp_schedule_loss_probe(struct sock *sk); 563 564 /* tcp_input.c */ 565 void tcp_resume_early_retransmit(struct sock *sk); 566 void tcp_rearm_rto(struct sock *sk); 567 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req); 568 void tcp_reset(struct sock *sk); 569 570 /* tcp_timer.c */ 571 void tcp_init_xmit_timers(struct sock *); 572 static inline void tcp_clear_xmit_timers(struct sock *sk) 573 { 574 inet_csk_clear_xmit_timers(sk); 575 } 576 577 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 578 unsigned int tcp_current_mss(struct sock *sk); 579 580 /* Bound MSS / TSO packet size with the half of the window */ 581 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 582 { 583 int cutoff; 584 585 /* When peer uses tiny windows, there is no use in packetizing 586 * to sub-MSS pieces for the sake of SWS or making sure there 587 * are enough packets in the pipe for fast recovery. 588 * 589 * On the other hand, for extremely large MSS devices, handling 590 * smaller than MSS windows in this way does make sense. 591 */ 592 if (tp->max_window >= 512) 593 cutoff = (tp->max_window >> 1); 594 else 595 cutoff = tp->max_window; 596 597 if (cutoff && pktsize > cutoff) 598 return max_t(int, cutoff, 68U - tp->tcp_header_len); 599 else 600 return pktsize; 601 } 602 603 /* tcp.c */ 604 void tcp_get_info(struct sock *, struct tcp_info *); 605 606 /* Read 'sendfile()'-style from a TCP socket */ 607 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *, 608 unsigned int, size_t); 609 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 610 sk_read_actor_t recv_actor); 611 612 void tcp_initialize_rcv_mss(struct sock *sk); 613 614 int tcp_mtu_to_mss(struct sock *sk, int pmtu); 615 int tcp_mss_to_mtu(struct sock *sk, int mss); 616 void tcp_mtup_init(struct sock *sk); 617 void tcp_init_buffer_space(struct sock *sk); 618 619 static inline void tcp_bound_rto(const struct sock *sk) 620 { 621 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 622 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 623 } 624 625 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 626 { 627 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us); 628 } 629 630 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 631 { 632 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 633 ntohl(TCP_FLAG_ACK) | 634 snd_wnd); 635 } 636 637 static inline void tcp_fast_path_on(struct tcp_sock *tp) 638 { 639 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 640 } 641 642 static inline void tcp_fast_path_check(struct sock *sk) 643 { 644 struct tcp_sock *tp = tcp_sk(sk); 645 646 if (skb_queue_empty(&tp->out_of_order_queue) && 647 tp->rcv_wnd && 648 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 649 !tp->urg_data) 650 tcp_fast_path_on(tp); 651 } 652 653 /* Compute the actual rto_min value */ 654 static inline u32 tcp_rto_min(struct sock *sk) 655 { 656 const struct dst_entry *dst = __sk_dst_get(sk); 657 u32 rto_min = TCP_RTO_MIN; 658 659 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 660 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 661 return rto_min; 662 } 663 664 static inline u32 tcp_rto_min_us(struct sock *sk) 665 { 666 return jiffies_to_usecs(tcp_rto_min(sk)); 667 } 668 669 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst) 670 { 671 return dst_metric_locked(dst, RTAX_CC_ALGO); 672 } 673 674 /* Compute the actual receive window we are currently advertising. 675 * Rcv_nxt can be after the window if our peer push more data 676 * than the offered window. 677 */ 678 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 679 { 680 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 681 682 if (win < 0) 683 win = 0; 684 return (u32) win; 685 } 686 687 /* Choose a new window, without checks for shrinking, and without 688 * scaling applied to the result. The caller does these things 689 * if necessary. This is a "raw" window selection. 690 */ 691 u32 __tcp_select_window(struct sock *sk); 692 693 void tcp_send_window_probe(struct sock *sk); 694 695 /* TCP timestamps are only 32-bits, this causes a slight 696 * complication on 64-bit systems since we store a snapshot 697 * of jiffies in the buffer control blocks below. We decided 698 * to use only the low 32-bits of jiffies and hide the ugly 699 * casts with the following macro. 700 */ 701 #define tcp_time_stamp ((__u32)(jiffies)) 702 703 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) 704 { 705 return skb->skb_mstamp.stamp_jiffies; 706 } 707 708 709 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 710 711 #define TCPHDR_FIN 0x01 712 #define TCPHDR_SYN 0x02 713 #define TCPHDR_RST 0x04 714 #define TCPHDR_PSH 0x08 715 #define TCPHDR_ACK 0x10 716 #define TCPHDR_URG 0x20 717 #define TCPHDR_ECE 0x40 718 #define TCPHDR_CWR 0x80 719 720 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) 721 722 /* This is what the send packet queuing engine uses to pass 723 * TCP per-packet control information to the transmission code. 724 * We also store the host-order sequence numbers in here too. 725 * This is 44 bytes if IPV6 is enabled. 726 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 727 */ 728 struct tcp_skb_cb { 729 __u32 seq; /* Starting sequence number */ 730 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 731 union { 732 /* Note : tcp_tw_isn is used in input path only 733 * (isn chosen by tcp_timewait_state_process()) 734 * 735 * tcp_gso_segs/size are used in write queue only, 736 * cf tcp_skb_pcount()/tcp_skb_mss() 737 */ 738 __u32 tcp_tw_isn; 739 struct { 740 u16 tcp_gso_segs; 741 u16 tcp_gso_size; 742 }; 743 }; 744 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 745 746 __u8 sacked; /* State flags for SACK/FACK. */ 747 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 748 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 749 #define TCPCB_LOST 0x04 /* SKB is lost */ 750 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 751 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */ 752 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 753 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \ 754 TCPCB_REPAIRED) 755 756 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 757 /* 1 byte hole */ 758 __u32 ack_seq; /* Sequence number ACK'd */ 759 union { 760 struct inet_skb_parm h4; 761 #if IS_ENABLED(CONFIG_IPV6) 762 struct inet6_skb_parm h6; 763 #endif 764 } header; /* For incoming frames */ 765 }; 766 767 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 768 769 770 #if IS_ENABLED(CONFIG_IPV6) 771 /* This is the variant of inet6_iif() that must be used by TCP, 772 * as TCP moves IP6CB into a different location in skb->cb[] 773 */ 774 static inline int tcp_v6_iif(const struct sk_buff *skb) 775 { 776 return TCP_SKB_CB(skb)->header.h6.iif; 777 } 778 #endif 779 780 /* Due to TSO, an SKB can be composed of multiple actual 781 * packets. To keep these tracked properly, we use this. 782 */ 783 static inline int tcp_skb_pcount(const struct sk_buff *skb) 784 { 785 return TCP_SKB_CB(skb)->tcp_gso_segs; 786 } 787 788 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 789 { 790 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 791 } 792 793 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 794 { 795 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 796 } 797 798 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ 799 static inline int tcp_skb_mss(const struct sk_buff *skb) 800 { 801 return TCP_SKB_CB(skb)->tcp_gso_size; 802 } 803 804 /* Events passed to congestion control interface */ 805 enum tcp_ca_event { 806 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 807 CA_EVENT_CWND_RESTART, /* congestion window restart */ 808 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 809 CA_EVENT_LOSS, /* loss timeout */ 810 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 811 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 812 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */ 813 CA_EVENT_NON_DELAYED_ACK, 814 }; 815 816 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 817 enum tcp_ca_ack_event_flags { 818 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 819 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 820 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 821 }; 822 823 /* 824 * Interface for adding new TCP congestion control handlers 825 */ 826 #define TCP_CA_NAME_MAX 16 827 #define TCP_CA_MAX 128 828 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 829 830 #define TCP_CA_UNSPEC 0 831 832 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 833 #define TCP_CONG_NON_RESTRICTED 0x1 834 /* Requires ECN/ECT set on all packets */ 835 #define TCP_CONG_NEEDS_ECN 0x2 836 837 union tcp_cc_info; 838 839 struct tcp_congestion_ops { 840 struct list_head list; 841 u32 key; 842 u32 flags; 843 844 /* initialize private data (optional) */ 845 void (*init)(struct sock *sk); 846 /* cleanup private data (optional) */ 847 void (*release)(struct sock *sk); 848 849 /* return slow start threshold (required) */ 850 u32 (*ssthresh)(struct sock *sk); 851 /* do new cwnd calculation (required) */ 852 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 853 /* call before changing ca_state (optional) */ 854 void (*set_state)(struct sock *sk, u8 new_state); 855 /* call when cwnd event occurs (optional) */ 856 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 857 /* call when ack arrives (optional) */ 858 void (*in_ack_event)(struct sock *sk, u32 flags); 859 /* new value of cwnd after loss (optional) */ 860 u32 (*undo_cwnd)(struct sock *sk); 861 /* hook for packet ack accounting (optional) */ 862 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us); 863 /* get info for inet_diag (optional) */ 864 size_t (*get_info)(struct sock *sk, u32 ext, int *attr, 865 union tcp_cc_info *info); 866 867 char name[TCP_CA_NAME_MAX]; 868 struct module *owner; 869 }; 870 871 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 872 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 873 874 void tcp_assign_congestion_control(struct sock *sk); 875 void tcp_init_congestion_control(struct sock *sk); 876 void tcp_cleanup_congestion_control(struct sock *sk); 877 int tcp_set_default_congestion_control(const char *name); 878 void tcp_get_default_congestion_control(char *name); 879 void tcp_get_available_congestion_control(char *buf, size_t len); 880 void tcp_get_allowed_congestion_control(char *buf, size_t len); 881 int tcp_set_allowed_congestion_control(char *allowed); 882 int tcp_set_congestion_control(struct sock *sk, const char *name); 883 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); 884 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); 885 886 u32 tcp_reno_ssthresh(struct sock *sk); 887 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 888 extern struct tcp_congestion_ops tcp_reno; 889 890 struct tcp_congestion_ops *tcp_ca_find_key(u32 key); 891 u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca); 892 #ifdef CONFIG_INET 893 char *tcp_ca_get_name_by_key(u32 key, char *buffer); 894 #else 895 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) 896 { 897 return NULL; 898 } 899 #endif 900 901 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 902 { 903 const struct inet_connection_sock *icsk = inet_csk(sk); 904 905 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 906 } 907 908 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 909 { 910 struct inet_connection_sock *icsk = inet_csk(sk); 911 912 if (icsk->icsk_ca_ops->set_state) 913 icsk->icsk_ca_ops->set_state(sk, ca_state); 914 icsk->icsk_ca_state = ca_state; 915 } 916 917 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 918 { 919 const struct inet_connection_sock *icsk = inet_csk(sk); 920 921 if (icsk->icsk_ca_ops->cwnd_event) 922 icsk->icsk_ca_ops->cwnd_event(sk, event); 923 } 924 925 /* These functions determine how the current flow behaves in respect of SACK 926 * handling. SACK is negotiated with the peer, and therefore it can vary 927 * between different flows. 928 * 929 * tcp_is_sack - SACK enabled 930 * tcp_is_reno - No SACK 931 * tcp_is_fack - FACK enabled, implies SACK enabled 932 */ 933 static inline int tcp_is_sack(const struct tcp_sock *tp) 934 { 935 return tp->rx_opt.sack_ok; 936 } 937 938 static inline bool tcp_is_reno(const struct tcp_sock *tp) 939 { 940 return !tcp_is_sack(tp); 941 } 942 943 static inline bool tcp_is_fack(const struct tcp_sock *tp) 944 { 945 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED; 946 } 947 948 static inline void tcp_enable_fack(struct tcp_sock *tp) 949 { 950 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED; 951 } 952 953 /* TCP early-retransmit (ER) is similar to but more conservative than 954 * the thin-dupack feature. Enable ER only if thin-dupack is disabled. 955 */ 956 static inline void tcp_enable_early_retrans(struct tcp_sock *tp) 957 { 958 tp->do_early_retrans = sysctl_tcp_early_retrans && 959 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack && 960 sysctl_tcp_reordering == 3; 961 } 962 963 static inline void tcp_disable_early_retrans(struct tcp_sock *tp) 964 { 965 tp->do_early_retrans = 0; 966 } 967 968 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 969 { 970 return tp->sacked_out + tp->lost_out; 971 } 972 973 /* This determines how many packets are "in the network" to the best 974 * of our knowledge. In many cases it is conservative, but where 975 * detailed information is available from the receiver (via SACK 976 * blocks etc.) we can make more aggressive calculations. 977 * 978 * Use this for decisions involving congestion control, use just 979 * tp->packets_out to determine if the send queue is empty or not. 980 * 981 * Read this equation as: 982 * 983 * "Packets sent once on transmission queue" MINUS 984 * "Packets left network, but not honestly ACKed yet" PLUS 985 * "Packets fast retransmitted" 986 */ 987 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 988 { 989 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 990 } 991 992 #define TCP_INFINITE_SSTHRESH 0x7fffffff 993 994 static inline bool tcp_in_slow_start(const struct tcp_sock *tp) 995 { 996 return tp->snd_cwnd < tp->snd_ssthresh; 997 } 998 999 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 1000 { 1001 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 1002 } 1003 1004 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 1005 { 1006 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 1007 (1 << inet_csk(sk)->icsk_ca_state); 1008 } 1009 1010 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 1011 * The exception is cwnd reduction phase, when cwnd is decreasing towards 1012 * ssthresh. 1013 */ 1014 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 1015 { 1016 const struct tcp_sock *tp = tcp_sk(sk); 1017 1018 if (tcp_in_cwnd_reduction(sk)) 1019 return tp->snd_ssthresh; 1020 else 1021 return max(tp->snd_ssthresh, 1022 ((tp->snd_cwnd >> 1) + 1023 (tp->snd_cwnd >> 2))); 1024 } 1025 1026 /* Use define here intentionally to get WARN_ON location shown at the caller */ 1027 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 1028 1029 void tcp_enter_cwr(struct sock *sk); 1030 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 1031 1032 /* The maximum number of MSS of available cwnd for which TSO defers 1033 * sending if not using sysctl_tcp_tso_win_divisor. 1034 */ 1035 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 1036 { 1037 return 3; 1038 } 1039 1040 /* Slow start with delack produces 3 packets of burst, so that 1041 * it is safe "de facto". This will be the default - same as 1042 * the default reordering threshold - but if reordering increases, 1043 * we must be able to allow cwnd to burst at least this much in order 1044 * to not pull it back when holes are filled. 1045 */ 1046 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp) 1047 { 1048 return tp->reordering; 1049 } 1050 1051 /* Returns end sequence number of the receiver's advertised window */ 1052 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 1053 { 1054 return tp->snd_una + tp->snd_wnd; 1055 } 1056 1057 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 1058 * flexible approach. The RFC suggests cwnd should not be raised unless 1059 * it was fully used previously. And that's exactly what we do in 1060 * congestion avoidance mode. But in slow start we allow cwnd to grow 1061 * as long as the application has used half the cwnd. 1062 * Example : 1063 * cwnd is 10 (IW10), but application sends 9 frames. 1064 * We allow cwnd to reach 18 when all frames are ACKed. 1065 * This check is safe because it's as aggressive as slow start which already 1066 * risks 100% overshoot. The advantage is that we discourage application to 1067 * either send more filler packets or data to artificially blow up the cwnd 1068 * usage, and allow application-limited process to probe bw more aggressively. 1069 */ 1070 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1071 { 1072 const struct tcp_sock *tp = tcp_sk(sk); 1073 1074 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1075 if (tcp_in_slow_start(tp)) 1076 return tp->snd_cwnd < 2 * tp->max_packets_out; 1077 1078 return tp->is_cwnd_limited; 1079 } 1080 1081 /* Something is really bad, we could not queue an additional packet, 1082 * because qdisc is full or receiver sent a 0 window. 1083 * We do not want to add fuel to the fire, or abort too early, 1084 * so make sure the timer we arm now is at least 200ms in the future, 1085 * regardless of current icsk_rto value (as it could be ~2ms) 1086 */ 1087 static inline unsigned long tcp_probe0_base(const struct sock *sk) 1088 { 1089 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); 1090 } 1091 1092 /* Variant of inet_csk_rto_backoff() used for zero window probes */ 1093 static inline unsigned long tcp_probe0_when(const struct sock *sk, 1094 unsigned long max_when) 1095 { 1096 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff; 1097 1098 return (unsigned long)min_t(u64, when, max_when); 1099 } 1100 1101 static inline void tcp_check_probe_timer(struct sock *sk) 1102 { 1103 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) 1104 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1105 tcp_probe0_base(sk), TCP_RTO_MAX); 1106 } 1107 1108 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1109 { 1110 tp->snd_wl1 = seq; 1111 } 1112 1113 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1114 { 1115 tp->snd_wl1 = seq; 1116 } 1117 1118 /* 1119 * Calculate(/check) TCP checksum 1120 */ 1121 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1122 __be32 daddr, __wsum base) 1123 { 1124 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1125 } 1126 1127 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1128 { 1129 return __skb_checksum_complete(skb); 1130 } 1131 1132 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1133 { 1134 return !skb_csum_unnecessary(skb) && 1135 __tcp_checksum_complete(skb); 1136 } 1137 1138 /* Prequeue for VJ style copy to user, combined with checksumming. */ 1139 1140 static inline void tcp_prequeue_init(struct tcp_sock *tp) 1141 { 1142 tp->ucopy.task = NULL; 1143 tp->ucopy.len = 0; 1144 tp->ucopy.memory = 0; 1145 skb_queue_head_init(&tp->ucopy.prequeue); 1146 } 1147 1148 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb); 1149 1150 #undef STATE_TRACE 1151 1152 #ifdef STATE_TRACE 1153 static const char *statename[]={ 1154 "Unused","Established","Syn Sent","Syn Recv", 1155 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1156 "Close Wait","Last ACK","Listen","Closing" 1157 }; 1158 #endif 1159 void tcp_set_state(struct sock *sk, int state); 1160 1161 void tcp_done(struct sock *sk); 1162 1163 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1164 { 1165 rx_opt->dsack = 0; 1166 rx_opt->num_sacks = 0; 1167 } 1168 1169 u32 tcp_default_init_rwnd(u32 mss); 1170 void tcp_cwnd_restart(struct sock *sk, s32 delta); 1171 1172 static inline void tcp_slow_start_after_idle_check(struct sock *sk) 1173 { 1174 struct tcp_sock *tp = tcp_sk(sk); 1175 s32 delta; 1176 1177 if (!sysctl_tcp_slow_start_after_idle || tp->packets_out) 1178 return; 1179 delta = tcp_time_stamp - tp->lsndtime; 1180 if (delta > inet_csk(sk)->icsk_rto) 1181 tcp_cwnd_restart(sk, delta); 1182 } 1183 1184 /* Determine a window scaling and initial window to offer. */ 1185 void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd, 1186 __u32 *window_clamp, int wscale_ok, 1187 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1188 1189 static inline int tcp_win_from_space(int space) 1190 { 1191 return sysctl_tcp_adv_win_scale<=0 ? 1192 (space>>(-sysctl_tcp_adv_win_scale)) : 1193 space - (space>>sysctl_tcp_adv_win_scale); 1194 } 1195 1196 /* Note: caller must be prepared to deal with negative returns */ 1197 static inline int tcp_space(const struct sock *sk) 1198 { 1199 return tcp_win_from_space(sk->sk_rcvbuf - 1200 atomic_read(&sk->sk_rmem_alloc)); 1201 } 1202 1203 static inline int tcp_full_space(const struct sock *sk) 1204 { 1205 return tcp_win_from_space(sk->sk_rcvbuf); 1206 } 1207 1208 extern void tcp_openreq_init_rwin(struct request_sock *req, 1209 const struct sock *sk_listener, 1210 const struct dst_entry *dst); 1211 1212 void tcp_enter_memory_pressure(struct sock *sk); 1213 1214 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1215 { 1216 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl; 1217 } 1218 1219 static inline int keepalive_time_when(const struct tcp_sock *tp) 1220 { 1221 return tp->keepalive_time ? : sysctl_tcp_keepalive_time; 1222 } 1223 1224 static inline int keepalive_probes(const struct tcp_sock *tp) 1225 { 1226 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes; 1227 } 1228 1229 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1230 { 1231 const struct inet_connection_sock *icsk = &tp->inet_conn; 1232 1233 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime, 1234 tcp_time_stamp - tp->rcv_tstamp); 1235 } 1236 1237 static inline int tcp_fin_time(const struct sock *sk) 1238 { 1239 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout; 1240 const int rto = inet_csk(sk)->icsk_rto; 1241 1242 if (fin_timeout < (rto << 2) - (rto >> 1)) 1243 fin_timeout = (rto << 2) - (rto >> 1); 1244 1245 return fin_timeout; 1246 } 1247 1248 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1249 int paws_win) 1250 { 1251 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1252 return true; 1253 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1254 return true; 1255 /* 1256 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1257 * then following tcp messages have valid values. Ignore 0 value, 1258 * or else 'negative' tsval might forbid us to accept their packets. 1259 */ 1260 if (!rx_opt->ts_recent) 1261 return true; 1262 return false; 1263 } 1264 1265 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1266 int rst) 1267 { 1268 if (tcp_paws_check(rx_opt, 0)) 1269 return false; 1270 1271 /* RST segments are not recommended to carry timestamp, 1272 and, if they do, it is recommended to ignore PAWS because 1273 "their cleanup function should take precedence over timestamps." 1274 Certainly, it is mistake. It is necessary to understand the reasons 1275 of this constraint to relax it: if peer reboots, clock may go 1276 out-of-sync and half-open connections will not be reset. 1277 Actually, the problem would be not existing if all 1278 the implementations followed draft about maintaining clock 1279 via reboots. Linux-2.2 DOES NOT! 1280 1281 However, we can relax time bounds for RST segments to MSL. 1282 */ 1283 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1284 return false; 1285 return true; 1286 } 1287 1288 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, 1289 int mib_idx, u32 *last_oow_ack_time); 1290 1291 static inline void tcp_mib_init(struct net *net) 1292 { 1293 /* See RFC 2012 */ 1294 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1); 1295 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1296 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1297 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1); 1298 } 1299 1300 /* from STCP */ 1301 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1302 { 1303 tp->lost_skb_hint = NULL; 1304 } 1305 1306 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1307 { 1308 tcp_clear_retrans_hints_partial(tp); 1309 tp->retransmit_skb_hint = NULL; 1310 } 1311 1312 /* MD5 Signature */ 1313 struct crypto_hash; 1314 1315 union tcp_md5_addr { 1316 struct in_addr a4; 1317 #if IS_ENABLED(CONFIG_IPV6) 1318 struct in6_addr a6; 1319 #endif 1320 }; 1321 1322 /* - key database */ 1323 struct tcp_md5sig_key { 1324 struct hlist_node node; 1325 u8 keylen; 1326 u8 family; /* AF_INET or AF_INET6 */ 1327 union tcp_md5_addr addr; 1328 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1329 struct rcu_head rcu; 1330 }; 1331 1332 /* - sock block */ 1333 struct tcp_md5sig_info { 1334 struct hlist_head head; 1335 struct rcu_head rcu; 1336 }; 1337 1338 /* - pseudo header */ 1339 struct tcp4_pseudohdr { 1340 __be32 saddr; 1341 __be32 daddr; 1342 __u8 pad; 1343 __u8 protocol; 1344 __be16 len; 1345 }; 1346 1347 struct tcp6_pseudohdr { 1348 struct in6_addr saddr; 1349 struct in6_addr daddr; 1350 __be32 len; 1351 __be32 protocol; /* including padding */ 1352 }; 1353 1354 union tcp_md5sum_block { 1355 struct tcp4_pseudohdr ip4; 1356 #if IS_ENABLED(CONFIG_IPV6) 1357 struct tcp6_pseudohdr ip6; 1358 #endif 1359 }; 1360 1361 /* - pool: digest algorithm, hash description and scratch buffer */ 1362 struct tcp_md5sig_pool { 1363 struct hash_desc md5_desc; 1364 union tcp_md5sum_block md5_blk; 1365 }; 1366 1367 /* - functions */ 1368 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1369 const struct sock *sk, const struct sk_buff *skb); 1370 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1371 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp); 1372 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1373 int family); 1374 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 1375 const struct sock *addr_sk); 1376 1377 #ifdef CONFIG_TCP_MD5SIG 1378 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1379 const union tcp_md5_addr *addr, 1380 int family); 1381 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1382 #else 1383 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1384 const union tcp_md5_addr *addr, 1385 int family) 1386 { 1387 return NULL; 1388 } 1389 #define tcp_twsk_md5_key(twsk) NULL 1390 #endif 1391 1392 bool tcp_alloc_md5sig_pool(void); 1393 1394 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1395 static inline void tcp_put_md5sig_pool(void) 1396 { 1397 local_bh_enable(); 1398 } 1399 1400 int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *); 1401 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1402 unsigned int header_len); 1403 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1404 const struct tcp_md5sig_key *key); 1405 1406 /* From tcp_fastopen.c */ 1407 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1408 struct tcp_fastopen_cookie *cookie, int *syn_loss, 1409 unsigned long *last_syn_loss); 1410 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1411 struct tcp_fastopen_cookie *cookie, bool syn_lost, 1412 u16 try_exp); 1413 struct tcp_fastopen_request { 1414 /* Fast Open cookie. Size 0 means a cookie request */ 1415 struct tcp_fastopen_cookie cookie; 1416 struct msghdr *data; /* data in MSG_FASTOPEN */ 1417 size_t size; 1418 int copied; /* queued in tcp_connect() */ 1419 }; 1420 void tcp_free_fastopen_req(struct tcp_sock *tp); 1421 1422 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; 1423 int tcp_fastopen_reset_cipher(void *key, unsigned int len); 1424 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1425 struct request_sock *req, 1426 struct tcp_fastopen_cookie *foc, 1427 struct dst_entry *dst); 1428 void tcp_fastopen_init_key_once(bool publish); 1429 #define TCP_FASTOPEN_KEY_LENGTH 16 1430 1431 /* Fastopen key context */ 1432 struct tcp_fastopen_context { 1433 struct crypto_cipher *tfm; 1434 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1435 struct rcu_head rcu; 1436 }; 1437 1438 /* write queue abstraction */ 1439 static inline void tcp_write_queue_purge(struct sock *sk) 1440 { 1441 struct sk_buff *skb; 1442 1443 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) 1444 sk_wmem_free_skb(sk, skb); 1445 sk_mem_reclaim(sk); 1446 tcp_clear_all_retrans_hints(tcp_sk(sk)); 1447 } 1448 1449 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1450 { 1451 return skb_peek(&sk->sk_write_queue); 1452 } 1453 1454 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1455 { 1456 return skb_peek_tail(&sk->sk_write_queue); 1457 } 1458 1459 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk, 1460 const struct sk_buff *skb) 1461 { 1462 return skb_queue_next(&sk->sk_write_queue, skb); 1463 } 1464 1465 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk, 1466 const struct sk_buff *skb) 1467 { 1468 return skb_queue_prev(&sk->sk_write_queue, skb); 1469 } 1470 1471 #define tcp_for_write_queue(skb, sk) \ 1472 skb_queue_walk(&(sk)->sk_write_queue, skb) 1473 1474 #define tcp_for_write_queue_from(skb, sk) \ 1475 skb_queue_walk_from(&(sk)->sk_write_queue, skb) 1476 1477 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1478 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1479 1480 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1481 { 1482 return sk->sk_send_head; 1483 } 1484 1485 static inline bool tcp_skb_is_last(const struct sock *sk, 1486 const struct sk_buff *skb) 1487 { 1488 return skb_queue_is_last(&sk->sk_write_queue, skb); 1489 } 1490 1491 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb) 1492 { 1493 if (tcp_skb_is_last(sk, skb)) 1494 sk->sk_send_head = NULL; 1495 else 1496 sk->sk_send_head = tcp_write_queue_next(sk, skb); 1497 } 1498 1499 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1500 { 1501 if (sk->sk_send_head == skb_unlinked) 1502 sk->sk_send_head = NULL; 1503 } 1504 1505 static inline void tcp_init_send_head(struct sock *sk) 1506 { 1507 sk->sk_send_head = NULL; 1508 } 1509 1510 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1511 { 1512 __skb_queue_tail(&sk->sk_write_queue, skb); 1513 } 1514 1515 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1516 { 1517 __tcp_add_write_queue_tail(sk, skb); 1518 1519 /* Queue it, remembering where we must start sending. */ 1520 if (sk->sk_send_head == NULL) { 1521 sk->sk_send_head = skb; 1522 1523 if (tcp_sk(sk)->highest_sack == NULL) 1524 tcp_sk(sk)->highest_sack = skb; 1525 } 1526 } 1527 1528 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb) 1529 { 1530 __skb_queue_head(&sk->sk_write_queue, skb); 1531 } 1532 1533 /* Insert buff after skb on the write queue of sk. */ 1534 static inline void tcp_insert_write_queue_after(struct sk_buff *skb, 1535 struct sk_buff *buff, 1536 struct sock *sk) 1537 { 1538 __skb_queue_after(&sk->sk_write_queue, skb, buff); 1539 } 1540 1541 /* Insert new before skb on the write queue of sk. */ 1542 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1543 struct sk_buff *skb, 1544 struct sock *sk) 1545 { 1546 __skb_queue_before(&sk->sk_write_queue, skb, new); 1547 1548 if (sk->sk_send_head == skb) 1549 sk->sk_send_head = new; 1550 } 1551 1552 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1553 { 1554 __skb_unlink(skb, &sk->sk_write_queue); 1555 } 1556 1557 static inline bool tcp_write_queue_empty(struct sock *sk) 1558 { 1559 return skb_queue_empty(&sk->sk_write_queue); 1560 } 1561 1562 static inline void tcp_push_pending_frames(struct sock *sk) 1563 { 1564 if (tcp_send_head(sk)) { 1565 struct tcp_sock *tp = tcp_sk(sk); 1566 1567 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1568 } 1569 } 1570 1571 /* Start sequence of the skb just after the highest skb with SACKed 1572 * bit, valid only if sacked_out > 0 or when the caller has ensured 1573 * validity by itself. 1574 */ 1575 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1576 { 1577 if (!tp->sacked_out) 1578 return tp->snd_una; 1579 1580 if (tp->highest_sack == NULL) 1581 return tp->snd_nxt; 1582 1583 return TCP_SKB_CB(tp->highest_sack)->seq; 1584 } 1585 1586 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1587 { 1588 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL : 1589 tcp_write_queue_next(sk, skb); 1590 } 1591 1592 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1593 { 1594 return tcp_sk(sk)->highest_sack; 1595 } 1596 1597 static inline void tcp_highest_sack_reset(struct sock *sk) 1598 { 1599 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk); 1600 } 1601 1602 /* Called when old skb is about to be deleted (to be combined with new skb) */ 1603 static inline void tcp_highest_sack_combine(struct sock *sk, 1604 struct sk_buff *old, 1605 struct sk_buff *new) 1606 { 1607 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack)) 1608 tcp_sk(sk)->highest_sack = new; 1609 } 1610 1611 /* Determines whether this is a thin stream (which may suffer from 1612 * increased latency). Used to trigger latency-reducing mechanisms. 1613 */ 1614 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1615 { 1616 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1617 } 1618 1619 /* /proc */ 1620 enum tcp_seq_states { 1621 TCP_SEQ_STATE_LISTENING, 1622 TCP_SEQ_STATE_ESTABLISHED, 1623 }; 1624 1625 int tcp_seq_open(struct inode *inode, struct file *file); 1626 1627 struct tcp_seq_afinfo { 1628 char *name; 1629 sa_family_t family; 1630 const struct file_operations *seq_fops; 1631 struct seq_operations seq_ops; 1632 }; 1633 1634 struct tcp_iter_state { 1635 struct seq_net_private p; 1636 sa_family_t family; 1637 enum tcp_seq_states state; 1638 struct sock *syn_wait_sk; 1639 int bucket, offset, sbucket, num; 1640 loff_t last_pos; 1641 }; 1642 1643 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1644 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1645 1646 extern struct request_sock_ops tcp_request_sock_ops; 1647 extern struct request_sock_ops tcp6_request_sock_ops; 1648 1649 void tcp_v4_destroy_sock(struct sock *sk); 1650 1651 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 1652 netdev_features_t features); 1653 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb); 1654 int tcp_gro_complete(struct sk_buff *skb); 1655 1656 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 1657 1658 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 1659 { 1660 return tp->notsent_lowat ?: sysctl_tcp_notsent_lowat; 1661 } 1662 1663 static inline bool tcp_stream_memory_free(const struct sock *sk) 1664 { 1665 const struct tcp_sock *tp = tcp_sk(sk); 1666 u32 notsent_bytes = tp->write_seq - tp->snd_nxt; 1667 1668 return notsent_bytes < tcp_notsent_lowat(tp); 1669 } 1670 1671 #ifdef CONFIG_PROC_FS 1672 int tcp4_proc_init(void); 1673 void tcp4_proc_exit(void); 1674 #endif 1675 1676 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req); 1677 int tcp_conn_request(struct request_sock_ops *rsk_ops, 1678 const struct tcp_request_sock_ops *af_ops, 1679 struct sock *sk, struct sk_buff *skb); 1680 1681 /* TCP af-specific functions */ 1682 struct tcp_sock_af_ops { 1683 #ifdef CONFIG_TCP_MD5SIG 1684 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk, 1685 const struct sock *addr_sk); 1686 int (*calc_md5_hash)(char *location, 1687 const struct tcp_md5sig_key *md5, 1688 const struct sock *sk, 1689 const struct sk_buff *skb); 1690 int (*md5_parse)(struct sock *sk, 1691 char __user *optval, 1692 int optlen); 1693 #endif 1694 }; 1695 1696 struct tcp_request_sock_ops { 1697 u16 mss_clamp; 1698 #ifdef CONFIG_TCP_MD5SIG 1699 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk, 1700 const struct sock *addr_sk); 1701 int (*calc_md5_hash) (char *location, 1702 const struct tcp_md5sig_key *md5, 1703 const struct sock *sk, 1704 const struct sk_buff *skb); 1705 #endif 1706 void (*init_req)(struct request_sock *req, 1707 const struct sock *sk_listener, 1708 struct sk_buff *skb); 1709 #ifdef CONFIG_SYN_COOKIES 1710 __u32 (*cookie_init_seq)(const struct sk_buff *skb, 1711 __u16 *mss); 1712 #endif 1713 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl, 1714 const struct request_sock *req, 1715 bool *strict); 1716 __u32 (*init_seq)(const struct sk_buff *skb); 1717 int (*send_synack)(const struct sock *sk, struct dst_entry *dst, 1718 struct flowi *fl, struct request_sock *req, 1719 u16 queue_mapping, struct tcp_fastopen_cookie *foc, 1720 bool attach_req); 1721 }; 1722 1723 #ifdef CONFIG_SYN_COOKIES 1724 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1725 const struct sock *sk, struct sk_buff *skb, 1726 __u16 *mss) 1727 { 1728 tcp_synq_overflow(sk); 1729 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); 1730 return ops->cookie_init_seq(skb, mss); 1731 } 1732 #else 1733 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1734 const struct sock *sk, struct sk_buff *skb, 1735 __u16 *mss) 1736 { 1737 return 0; 1738 } 1739 #endif 1740 1741 int tcpv4_offload_init(void); 1742 1743 void tcp_v4_init(void); 1744 void tcp_init(void); 1745 1746 /* 1747 * Save and compile IPv4 options, return a pointer to it 1748 */ 1749 static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb) 1750 { 1751 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; 1752 struct ip_options_rcu *dopt = NULL; 1753 1754 if (opt->optlen) { 1755 int opt_size = sizeof(*dopt) + opt->optlen; 1756 1757 dopt = kmalloc(opt_size, GFP_ATOMIC); 1758 if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) { 1759 kfree(dopt); 1760 dopt = NULL; 1761 } 1762 } 1763 return dopt; 1764 } 1765 1766 /* locally generated TCP pure ACKs have skb->truesize == 2 1767 * (check tcp_send_ack() in net/ipv4/tcp_output.c ) 1768 * This is much faster than dissecting the packet to find out. 1769 * (Think of GRE encapsulations, IPv4, IPv6, ...) 1770 */ 1771 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb) 1772 { 1773 return skb->truesize == 2; 1774 } 1775 1776 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb) 1777 { 1778 skb->truesize = 2; 1779 } 1780 1781 #endif /* _TCP_H */ 1782