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 rfc6928 */ 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_syn_retries; 244 extern int sysctl_tcp_synack_retries; 245 extern int sysctl_tcp_retries1; 246 extern int sysctl_tcp_retries2; 247 extern int sysctl_tcp_orphan_retries; 248 extern int sysctl_tcp_syncookies; 249 extern int sysctl_tcp_fastopen; 250 extern int sysctl_tcp_retrans_collapse; 251 extern int sysctl_tcp_stdurg; 252 extern int sysctl_tcp_rfc1337; 253 extern int sysctl_tcp_abort_on_overflow; 254 extern int sysctl_tcp_max_orphans; 255 extern int sysctl_tcp_fack; 256 extern int sysctl_tcp_reordering; 257 extern int sysctl_tcp_max_reordering; 258 extern int sysctl_tcp_dsack; 259 extern long sysctl_tcp_mem[3]; 260 extern int sysctl_tcp_wmem[3]; 261 extern int sysctl_tcp_rmem[3]; 262 extern int sysctl_tcp_app_win; 263 extern int sysctl_tcp_adv_win_scale; 264 extern int sysctl_tcp_tw_reuse; 265 extern int sysctl_tcp_frto; 266 extern int sysctl_tcp_low_latency; 267 extern int sysctl_tcp_nometrics_save; 268 extern int sysctl_tcp_moderate_rcvbuf; 269 extern int sysctl_tcp_tso_win_divisor; 270 extern int sysctl_tcp_workaround_signed_windows; 271 extern int sysctl_tcp_slow_start_after_idle; 272 extern int sysctl_tcp_thin_linear_timeouts; 273 extern int sysctl_tcp_thin_dupack; 274 extern int sysctl_tcp_early_retrans; 275 extern int sysctl_tcp_limit_output_bytes; 276 extern int sysctl_tcp_challenge_ack_limit; 277 extern unsigned int sysctl_tcp_notsent_lowat; 278 extern int sysctl_tcp_min_tso_segs; 279 extern int sysctl_tcp_min_rtt_wlen; 280 extern int sysctl_tcp_autocorking; 281 extern int sysctl_tcp_invalid_ratelimit; 282 extern int sysctl_tcp_pacing_ss_ratio; 283 extern int sysctl_tcp_pacing_ca_ratio; 284 285 extern atomic_long_t tcp_memory_allocated; 286 extern struct percpu_counter tcp_sockets_allocated; 287 extern int tcp_memory_pressure; 288 289 /* optimized version of sk_under_memory_pressure() for TCP sockets */ 290 static inline bool tcp_under_memory_pressure(const struct sock *sk) 291 { 292 if (mem_cgroup_sockets_enabled && sk->sk_memcg && 293 mem_cgroup_under_socket_pressure(sk->sk_memcg)) 294 return true; 295 296 return tcp_memory_pressure; 297 } 298 /* 299 * The next routines deal with comparing 32 bit unsigned ints 300 * and worry about wraparound (automatic with unsigned arithmetic). 301 */ 302 303 static inline bool before(__u32 seq1, __u32 seq2) 304 { 305 return (__s32)(seq1-seq2) < 0; 306 } 307 #define after(seq2, seq1) before(seq1, seq2) 308 309 /* is s2<=s1<=s3 ? */ 310 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) 311 { 312 return seq3 - seq2 >= seq1 - seq2; 313 } 314 315 static inline bool tcp_out_of_memory(struct sock *sk) 316 { 317 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 318 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2)) 319 return true; 320 return false; 321 } 322 323 void sk_forced_mem_schedule(struct sock *sk, int size); 324 325 static inline bool tcp_too_many_orphans(struct sock *sk, int shift) 326 { 327 struct percpu_counter *ocp = sk->sk_prot->orphan_count; 328 int orphans = percpu_counter_read_positive(ocp); 329 330 if (orphans << shift > sysctl_tcp_max_orphans) { 331 orphans = percpu_counter_sum_positive(ocp); 332 if (orphans << shift > sysctl_tcp_max_orphans) 333 return true; 334 } 335 return false; 336 } 337 338 bool tcp_check_oom(struct sock *sk, int shift); 339 340 341 extern struct proto tcp_prot; 342 343 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 344 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field) 345 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 346 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val) 347 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 348 349 void tcp_tasklet_init(void); 350 351 void tcp_v4_err(struct sk_buff *skb, u32); 352 353 void tcp_shutdown(struct sock *sk, int how); 354 355 void tcp_v4_early_demux(struct sk_buff *skb); 356 int tcp_v4_rcv(struct sk_buff *skb); 357 358 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 359 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size); 360 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, 361 int flags); 362 void tcp_release_cb(struct sock *sk); 363 void tcp_wfree(struct sk_buff *skb); 364 void tcp_write_timer_handler(struct sock *sk); 365 void tcp_delack_timer_handler(struct sock *sk); 366 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 367 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb); 368 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 369 const struct tcphdr *th, unsigned int len); 370 void tcp_rcv_space_adjust(struct sock *sk); 371 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 372 void tcp_twsk_destructor(struct sock *sk); 373 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 374 struct pipe_inode_info *pipe, size_t len, 375 unsigned int flags); 376 377 static inline void tcp_dec_quickack_mode(struct sock *sk, 378 const unsigned int pkts) 379 { 380 struct inet_connection_sock *icsk = inet_csk(sk); 381 382 if (icsk->icsk_ack.quick) { 383 if (pkts >= icsk->icsk_ack.quick) { 384 icsk->icsk_ack.quick = 0; 385 /* Leaving quickack mode we deflate ATO. */ 386 icsk->icsk_ack.ato = TCP_ATO_MIN; 387 } else 388 icsk->icsk_ack.quick -= pkts; 389 } 390 } 391 392 #define TCP_ECN_OK 1 393 #define TCP_ECN_QUEUE_CWR 2 394 #define TCP_ECN_DEMAND_CWR 4 395 #define TCP_ECN_SEEN 8 396 397 enum tcp_tw_status { 398 TCP_TW_SUCCESS = 0, 399 TCP_TW_RST = 1, 400 TCP_TW_ACK = 2, 401 TCP_TW_SYN = 3 402 }; 403 404 405 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 406 struct sk_buff *skb, 407 const struct tcphdr *th); 408 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 409 struct request_sock *req, bool fastopen); 410 int tcp_child_process(struct sock *parent, struct sock *child, 411 struct sk_buff *skb); 412 void tcp_enter_loss(struct sock *sk); 413 void tcp_clear_retrans(struct tcp_sock *tp); 414 void tcp_update_metrics(struct sock *sk); 415 void tcp_init_metrics(struct sock *sk); 416 void tcp_metrics_init(void); 417 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, 418 bool paws_check, bool timestamps); 419 bool tcp_remember_stamp(struct sock *sk); 420 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw); 421 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst); 422 void tcp_disable_fack(struct tcp_sock *tp); 423 void tcp_close(struct sock *sk, long timeout); 424 void tcp_init_sock(struct sock *sk); 425 unsigned int tcp_poll(struct file *file, struct socket *sock, 426 struct poll_table_struct *wait); 427 int tcp_getsockopt(struct sock *sk, int level, int optname, 428 char __user *optval, int __user *optlen); 429 int tcp_setsockopt(struct sock *sk, int level, int optname, 430 char __user *optval, unsigned int optlen); 431 int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 432 char __user *optval, int __user *optlen); 433 int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 434 char __user *optval, unsigned int optlen); 435 void tcp_set_keepalive(struct sock *sk, int val); 436 void tcp_syn_ack_timeout(const struct request_sock *req); 437 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, 438 int flags, int *addr_len); 439 void tcp_parse_options(const struct sk_buff *skb, 440 struct tcp_options_received *opt_rx, 441 int estab, struct tcp_fastopen_cookie *foc); 442 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); 443 444 /* 445 * TCP v4 functions exported for the inet6 API 446 */ 447 448 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 449 void tcp_v4_mtu_reduced(struct sock *sk); 450 void tcp_req_err(struct sock *sk, u32 seq); 451 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 452 struct sock *tcp_create_openreq_child(const struct sock *sk, 453 struct request_sock *req, 454 struct sk_buff *skb); 455 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst); 456 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 457 struct request_sock *req, 458 struct dst_entry *dst, 459 struct request_sock *req_unhash, 460 bool *own_req); 461 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 462 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); 463 int tcp_connect(struct sock *sk); 464 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 465 struct request_sock *req, 466 struct tcp_fastopen_cookie *foc, 467 bool attach_req); 468 int tcp_disconnect(struct sock *sk, int flags); 469 470 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 471 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 472 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); 473 474 /* From syncookies.c */ 475 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, 476 struct request_sock *req, 477 struct dst_entry *dst); 478 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th, 479 u32 cookie); 480 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb); 481 #ifdef CONFIG_SYN_COOKIES 482 483 /* Syncookies use a monotonic timer which increments every 60 seconds. 484 * This counter is used both as a hash input and partially encoded into 485 * the cookie value. A cookie is only validated further if the delta 486 * between the current counter value and the encoded one is less than this, 487 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if 488 * the counter advances immediately after a cookie is generated). 489 */ 490 #define MAX_SYNCOOKIE_AGE 2 491 #define TCP_SYNCOOKIE_PERIOD (60 * HZ) 492 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD) 493 494 /* syncookies: remember time of last synqueue overflow 495 * But do not dirty this field too often (once per second is enough) 496 * It is racy as we do not hold a lock, but race is very minor. 497 */ 498 static inline void tcp_synq_overflow(const struct sock *sk) 499 { 500 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 501 unsigned long now = jiffies; 502 503 if (time_after(now, last_overflow + HZ)) 504 tcp_sk(sk)->rx_opt.ts_recent_stamp = now; 505 } 506 507 /* syncookies: no recent synqueue overflow on this listening socket? */ 508 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 509 { 510 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 511 512 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID); 513 } 514 515 static inline u32 tcp_cookie_time(void) 516 { 517 u64 val = get_jiffies_64(); 518 519 do_div(val, TCP_SYNCOOKIE_PERIOD); 520 return val; 521 } 522 523 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, 524 u16 *mssp); 525 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss); 526 __u32 cookie_init_timestamp(struct request_sock *req); 527 bool cookie_timestamp_decode(struct tcp_options_received *opt); 528 bool cookie_ecn_ok(const struct tcp_options_received *opt, 529 const struct net *net, const struct dst_entry *dst); 530 531 /* From net/ipv6/syncookies.c */ 532 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th, 533 u32 cookie); 534 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 535 536 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph, 537 const struct tcphdr *th, u16 *mssp); 538 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss); 539 #endif 540 /* tcp_output.c */ 541 542 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 543 int nonagle); 544 bool tcp_may_send_now(struct sock *sk); 545 int __tcp_retransmit_skb(struct sock *, struct sk_buff *); 546 int tcp_retransmit_skb(struct sock *, struct sk_buff *); 547 void tcp_retransmit_timer(struct sock *sk); 548 void tcp_xmit_retransmit_queue(struct sock *); 549 void tcp_simple_retransmit(struct sock *); 550 int tcp_trim_head(struct sock *, struct sk_buff *, u32); 551 int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t); 552 553 void tcp_send_probe0(struct sock *); 554 void tcp_send_partial(struct sock *); 555 int tcp_write_wakeup(struct sock *, int mib); 556 void tcp_send_fin(struct sock *sk); 557 void tcp_send_active_reset(struct sock *sk, gfp_t priority); 558 int tcp_send_synack(struct sock *); 559 void tcp_push_one(struct sock *, unsigned int mss_now); 560 void tcp_send_ack(struct sock *sk); 561 void tcp_send_delayed_ack(struct sock *sk); 562 void tcp_send_loss_probe(struct sock *sk); 563 bool tcp_schedule_loss_probe(struct sock *sk); 564 565 /* tcp_input.c */ 566 void tcp_resume_early_retransmit(struct sock *sk); 567 void tcp_rearm_rto(struct sock *sk); 568 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req); 569 void tcp_reset(struct sock *sk); 570 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb); 571 572 /* tcp_timer.c */ 573 void tcp_init_xmit_timers(struct sock *); 574 static inline void tcp_clear_xmit_timers(struct sock *sk) 575 { 576 inet_csk_clear_xmit_timers(sk); 577 } 578 579 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 580 unsigned int tcp_current_mss(struct sock *sk); 581 582 /* Bound MSS / TSO packet size with the half of the window */ 583 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 584 { 585 int cutoff; 586 587 /* When peer uses tiny windows, there is no use in packetizing 588 * to sub-MSS pieces for the sake of SWS or making sure there 589 * are enough packets in the pipe for fast recovery. 590 * 591 * On the other hand, for extremely large MSS devices, handling 592 * smaller than MSS windows in this way does make sense. 593 */ 594 if (tp->max_window >= 512) 595 cutoff = (tp->max_window >> 1); 596 else 597 cutoff = tp->max_window; 598 599 if (cutoff && pktsize > cutoff) 600 return max_t(int, cutoff, 68U - tp->tcp_header_len); 601 else 602 return pktsize; 603 } 604 605 /* tcp.c */ 606 void tcp_get_info(struct sock *, struct tcp_info *); 607 608 /* Read 'sendfile()'-style from a TCP socket */ 609 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *, 610 unsigned int, size_t); 611 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 612 sk_read_actor_t recv_actor); 613 614 void tcp_initialize_rcv_mss(struct sock *sk); 615 616 int tcp_mtu_to_mss(struct sock *sk, int pmtu); 617 int tcp_mss_to_mtu(struct sock *sk, int mss); 618 void tcp_mtup_init(struct sock *sk); 619 void tcp_init_buffer_space(struct sock *sk); 620 621 static inline void tcp_bound_rto(const struct sock *sk) 622 { 623 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 624 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 625 } 626 627 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 628 { 629 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us); 630 } 631 632 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 633 { 634 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 635 ntohl(TCP_FLAG_ACK) | 636 snd_wnd); 637 } 638 639 static inline void tcp_fast_path_on(struct tcp_sock *tp) 640 { 641 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 642 } 643 644 static inline void tcp_fast_path_check(struct sock *sk) 645 { 646 struct tcp_sock *tp = tcp_sk(sk); 647 648 if (skb_queue_empty(&tp->out_of_order_queue) && 649 tp->rcv_wnd && 650 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 651 !tp->urg_data) 652 tcp_fast_path_on(tp); 653 } 654 655 /* Compute the actual rto_min value */ 656 static inline u32 tcp_rto_min(struct sock *sk) 657 { 658 const struct dst_entry *dst = __sk_dst_get(sk); 659 u32 rto_min = TCP_RTO_MIN; 660 661 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 662 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 663 return rto_min; 664 } 665 666 static inline u32 tcp_rto_min_us(struct sock *sk) 667 { 668 return jiffies_to_usecs(tcp_rto_min(sk)); 669 } 670 671 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst) 672 { 673 return dst_metric_locked(dst, RTAX_CC_ALGO); 674 } 675 676 /* Minimum RTT in usec. ~0 means not available. */ 677 static inline u32 tcp_min_rtt(const struct tcp_sock *tp) 678 { 679 return tp->rtt_min[0].rtt; 680 } 681 682 /* Compute the actual receive window we are currently advertising. 683 * Rcv_nxt can be after the window if our peer push more data 684 * than the offered window. 685 */ 686 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 687 { 688 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 689 690 if (win < 0) 691 win = 0; 692 return (u32) win; 693 } 694 695 /* Choose a new window, without checks for shrinking, and without 696 * scaling applied to the result. The caller does these things 697 * if necessary. This is a "raw" window selection. 698 */ 699 u32 __tcp_select_window(struct sock *sk); 700 701 void tcp_send_window_probe(struct sock *sk); 702 703 /* TCP timestamps are only 32-bits, this causes a slight 704 * complication on 64-bit systems since we store a snapshot 705 * of jiffies in the buffer control blocks below. We decided 706 * to use only the low 32-bits of jiffies and hide the ugly 707 * casts with the following macro. 708 */ 709 #define tcp_time_stamp ((__u32)(jiffies)) 710 711 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) 712 { 713 return skb->skb_mstamp.stamp_jiffies; 714 } 715 716 717 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 718 719 #define TCPHDR_FIN 0x01 720 #define TCPHDR_SYN 0x02 721 #define TCPHDR_RST 0x04 722 #define TCPHDR_PSH 0x08 723 #define TCPHDR_ACK 0x10 724 #define TCPHDR_URG 0x20 725 #define TCPHDR_ECE 0x40 726 #define TCPHDR_CWR 0x80 727 728 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) 729 730 /* This is what the send packet queuing engine uses to pass 731 * TCP per-packet control information to the transmission code. 732 * We also store the host-order sequence numbers in here too. 733 * This is 44 bytes if IPV6 is enabled. 734 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 735 */ 736 struct tcp_skb_cb { 737 __u32 seq; /* Starting sequence number */ 738 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 739 union { 740 /* Note : tcp_tw_isn is used in input path only 741 * (isn chosen by tcp_timewait_state_process()) 742 * 743 * tcp_gso_segs/size are used in write queue only, 744 * cf tcp_skb_pcount()/tcp_skb_mss() 745 */ 746 __u32 tcp_tw_isn; 747 struct { 748 u16 tcp_gso_segs; 749 u16 tcp_gso_size; 750 }; 751 }; 752 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 753 754 __u8 sacked; /* State flags for SACK/FACK. */ 755 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 756 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 757 #define TCPCB_LOST 0x04 /* SKB is lost */ 758 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 759 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */ 760 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 761 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \ 762 TCPCB_REPAIRED) 763 764 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 765 /* 1 byte hole */ 766 __u32 ack_seq; /* Sequence number ACK'd */ 767 union { 768 struct inet_skb_parm h4; 769 #if IS_ENABLED(CONFIG_IPV6) 770 struct inet6_skb_parm h6; 771 #endif 772 } header; /* For incoming frames */ 773 }; 774 775 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 776 777 778 #if IS_ENABLED(CONFIG_IPV6) 779 /* This is the variant of inet6_iif() that must be used by TCP, 780 * as TCP moves IP6CB into a different location in skb->cb[] 781 */ 782 static inline int tcp_v6_iif(const struct sk_buff *skb) 783 { 784 return TCP_SKB_CB(skb)->header.h6.iif; 785 } 786 #endif 787 788 /* Due to TSO, an SKB can be composed of multiple actual 789 * packets. To keep these tracked properly, we use this. 790 */ 791 static inline int tcp_skb_pcount(const struct sk_buff *skb) 792 { 793 return TCP_SKB_CB(skb)->tcp_gso_segs; 794 } 795 796 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 797 { 798 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 799 } 800 801 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 802 { 803 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 804 } 805 806 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ 807 static inline int tcp_skb_mss(const struct sk_buff *skb) 808 { 809 return TCP_SKB_CB(skb)->tcp_gso_size; 810 } 811 812 /* Events passed to congestion control interface */ 813 enum tcp_ca_event { 814 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 815 CA_EVENT_CWND_RESTART, /* congestion window restart */ 816 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 817 CA_EVENT_LOSS, /* loss timeout */ 818 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 819 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 820 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */ 821 CA_EVENT_NON_DELAYED_ACK, 822 }; 823 824 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 825 enum tcp_ca_ack_event_flags { 826 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 827 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 828 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 829 }; 830 831 /* 832 * Interface for adding new TCP congestion control handlers 833 */ 834 #define TCP_CA_NAME_MAX 16 835 #define TCP_CA_MAX 128 836 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 837 838 #define TCP_CA_UNSPEC 0 839 840 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 841 #define TCP_CONG_NON_RESTRICTED 0x1 842 /* Requires ECN/ECT set on all packets */ 843 #define TCP_CONG_NEEDS_ECN 0x2 844 845 union tcp_cc_info; 846 847 struct tcp_congestion_ops { 848 struct list_head list; 849 u32 key; 850 u32 flags; 851 852 /* initialize private data (optional) */ 853 void (*init)(struct sock *sk); 854 /* cleanup private data (optional) */ 855 void (*release)(struct sock *sk); 856 857 /* return slow start threshold (required) */ 858 u32 (*ssthresh)(struct sock *sk); 859 /* do new cwnd calculation (required) */ 860 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 861 /* call before changing ca_state (optional) */ 862 void (*set_state)(struct sock *sk, u8 new_state); 863 /* call when cwnd event occurs (optional) */ 864 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 865 /* call when ack arrives (optional) */ 866 void (*in_ack_event)(struct sock *sk, u32 flags); 867 /* new value of cwnd after loss (optional) */ 868 u32 (*undo_cwnd)(struct sock *sk); 869 /* hook for packet ack accounting (optional) */ 870 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us); 871 /* get info for inet_diag (optional) */ 872 size_t (*get_info)(struct sock *sk, u32 ext, int *attr, 873 union tcp_cc_info *info); 874 875 char name[TCP_CA_NAME_MAX]; 876 struct module *owner; 877 }; 878 879 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 880 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 881 882 void tcp_assign_congestion_control(struct sock *sk); 883 void tcp_init_congestion_control(struct sock *sk); 884 void tcp_cleanup_congestion_control(struct sock *sk); 885 int tcp_set_default_congestion_control(const char *name); 886 void tcp_get_default_congestion_control(char *name); 887 void tcp_get_available_congestion_control(char *buf, size_t len); 888 void tcp_get_allowed_congestion_control(char *buf, size_t len); 889 int tcp_set_allowed_congestion_control(char *allowed); 890 int tcp_set_congestion_control(struct sock *sk, const char *name); 891 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); 892 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); 893 894 u32 tcp_reno_ssthresh(struct sock *sk); 895 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 896 extern struct tcp_congestion_ops tcp_reno; 897 898 struct tcp_congestion_ops *tcp_ca_find_key(u32 key); 899 u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca); 900 #ifdef CONFIG_INET 901 char *tcp_ca_get_name_by_key(u32 key, char *buffer); 902 #else 903 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) 904 { 905 return NULL; 906 } 907 #endif 908 909 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 910 { 911 const struct inet_connection_sock *icsk = inet_csk(sk); 912 913 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 914 } 915 916 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 917 { 918 struct inet_connection_sock *icsk = inet_csk(sk); 919 920 if (icsk->icsk_ca_ops->set_state) 921 icsk->icsk_ca_ops->set_state(sk, ca_state); 922 icsk->icsk_ca_state = ca_state; 923 } 924 925 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 926 { 927 const struct inet_connection_sock *icsk = inet_csk(sk); 928 929 if (icsk->icsk_ca_ops->cwnd_event) 930 icsk->icsk_ca_ops->cwnd_event(sk, event); 931 } 932 933 /* These functions determine how the current flow behaves in respect of SACK 934 * handling. SACK is negotiated with the peer, and therefore it can vary 935 * between different flows. 936 * 937 * tcp_is_sack - SACK enabled 938 * tcp_is_reno - No SACK 939 * tcp_is_fack - FACK enabled, implies SACK enabled 940 */ 941 static inline int tcp_is_sack(const struct tcp_sock *tp) 942 { 943 return tp->rx_opt.sack_ok; 944 } 945 946 static inline bool tcp_is_reno(const struct tcp_sock *tp) 947 { 948 return !tcp_is_sack(tp); 949 } 950 951 static inline bool tcp_is_fack(const struct tcp_sock *tp) 952 { 953 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED; 954 } 955 956 static inline void tcp_enable_fack(struct tcp_sock *tp) 957 { 958 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED; 959 } 960 961 /* TCP early-retransmit (ER) is similar to but more conservative than 962 * the thin-dupack feature. Enable ER only if thin-dupack is disabled. 963 */ 964 static inline void tcp_enable_early_retrans(struct tcp_sock *tp) 965 { 966 tp->do_early_retrans = sysctl_tcp_early_retrans && 967 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack && 968 sysctl_tcp_reordering == 3; 969 } 970 971 static inline void tcp_disable_early_retrans(struct tcp_sock *tp) 972 { 973 tp->do_early_retrans = 0; 974 } 975 976 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 977 { 978 return tp->sacked_out + tp->lost_out; 979 } 980 981 /* This determines how many packets are "in the network" to the best 982 * of our knowledge. In many cases it is conservative, but where 983 * detailed information is available from the receiver (via SACK 984 * blocks etc.) we can make more aggressive calculations. 985 * 986 * Use this for decisions involving congestion control, use just 987 * tp->packets_out to determine if the send queue is empty or not. 988 * 989 * Read this equation as: 990 * 991 * "Packets sent once on transmission queue" MINUS 992 * "Packets left network, but not honestly ACKed yet" PLUS 993 * "Packets fast retransmitted" 994 */ 995 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 996 { 997 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 998 } 999 1000 #define TCP_INFINITE_SSTHRESH 0x7fffffff 1001 1002 static inline bool tcp_in_slow_start(const struct tcp_sock *tp) 1003 { 1004 return tp->snd_cwnd < tp->snd_ssthresh; 1005 } 1006 1007 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 1008 { 1009 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 1010 } 1011 1012 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 1013 { 1014 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 1015 (1 << inet_csk(sk)->icsk_ca_state); 1016 } 1017 1018 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 1019 * The exception is cwnd reduction phase, when cwnd is decreasing towards 1020 * ssthresh. 1021 */ 1022 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 1023 { 1024 const struct tcp_sock *tp = tcp_sk(sk); 1025 1026 if (tcp_in_cwnd_reduction(sk)) 1027 return tp->snd_ssthresh; 1028 else 1029 return max(tp->snd_ssthresh, 1030 ((tp->snd_cwnd >> 1) + 1031 (tp->snd_cwnd >> 2))); 1032 } 1033 1034 /* Use define here intentionally to get WARN_ON location shown at the caller */ 1035 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 1036 1037 void tcp_enter_cwr(struct sock *sk); 1038 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 1039 1040 /* The maximum number of MSS of available cwnd for which TSO defers 1041 * sending if not using sysctl_tcp_tso_win_divisor. 1042 */ 1043 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 1044 { 1045 return 3; 1046 } 1047 1048 /* Slow start with delack produces 3 packets of burst, so that 1049 * it is safe "de facto". This will be the default - same as 1050 * the default reordering threshold - but if reordering increases, 1051 * we must be able to allow cwnd to burst at least this much in order 1052 * to not pull it back when holes are filled. 1053 */ 1054 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp) 1055 { 1056 return tp->reordering; 1057 } 1058 1059 /* Returns end sequence number of the receiver's advertised window */ 1060 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 1061 { 1062 return tp->snd_una + tp->snd_wnd; 1063 } 1064 1065 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 1066 * flexible approach. The RFC suggests cwnd should not be raised unless 1067 * it was fully used previously. And that's exactly what we do in 1068 * congestion avoidance mode. But in slow start we allow cwnd to grow 1069 * as long as the application has used half the cwnd. 1070 * Example : 1071 * cwnd is 10 (IW10), but application sends 9 frames. 1072 * We allow cwnd to reach 18 when all frames are ACKed. 1073 * This check is safe because it's as aggressive as slow start which already 1074 * risks 100% overshoot. The advantage is that we discourage application to 1075 * either send more filler packets or data to artificially blow up the cwnd 1076 * usage, and allow application-limited process to probe bw more aggressively. 1077 */ 1078 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1079 { 1080 const struct tcp_sock *tp = tcp_sk(sk); 1081 1082 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1083 if (tcp_in_slow_start(tp)) 1084 return tp->snd_cwnd < 2 * tp->max_packets_out; 1085 1086 return tp->is_cwnd_limited; 1087 } 1088 1089 /* Something is really bad, we could not queue an additional packet, 1090 * because qdisc is full or receiver sent a 0 window. 1091 * We do not want to add fuel to the fire, or abort too early, 1092 * so make sure the timer we arm now is at least 200ms in the future, 1093 * regardless of current icsk_rto value (as it could be ~2ms) 1094 */ 1095 static inline unsigned long tcp_probe0_base(const struct sock *sk) 1096 { 1097 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); 1098 } 1099 1100 /* Variant of inet_csk_rto_backoff() used for zero window probes */ 1101 static inline unsigned long tcp_probe0_when(const struct sock *sk, 1102 unsigned long max_when) 1103 { 1104 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff; 1105 1106 return (unsigned long)min_t(u64, when, max_when); 1107 } 1108 1109 static inline void tcp_check_probe_timer(struct sock *sk) 1110 { 1111 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) 1112 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1113 tcp_probe0_base(sk), TCP_RTO_MAX); 1114 } 1115 1116 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1117 { 1118 tp->snd_wl1 = seq; 1119 } 1120 1121 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1122 { 1123 tp->snd_wl1 = seq; 1124 } 1125 1126 /* 1127 * Calculate(/check) TCP checksum 1128 */ 1129 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1130 __be32 daddr, __wsum base) 1131 { 1132 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1133 } 1134 1135 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1136 { 1137 return __skb_checksum_complete(skb); 1138 } 1139 1140 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1141 { 1142 return !skb_csum_unnecessary(skb) && 1143 __tcp_checksum_complete(skb); 1144 } 1145 1146 /* Prequeue for VJ style copy to user, combined with checksumming. */ 1147 1148 static inline void tcp_prequeue_init(struct tcp_sock *tp) 1149 { 1150 tp->ucopy.task = NULL; 1151 tp->ucopy.len = 0; 1152 tp->ucopy.memory = 0; 1153 skb_queue_head_init(&tp->ucopy.prequeue); 1154 } 1155 1156 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb); 1157 1158 #undef STATE_TRACE 1159 1160 #ifdef STATE_TRACE 1161 static const char *statename[]={ 1162 "Unused","Established","Syn Sent","Syn Recv", 1163 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1164 "Close Wait","Last ACK","Listen","Closing" 1165 }; 1166 #endif 1167 void tcp_set_state(struct sock *sk, int state); 1168 1169 void tcp_done(struct sock *sk); 1170 1171 int tcp_abort(struct sock *sk, int err); 1172 1173 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1174 { 1175 rx_opt->dsack = 0; 1176 rx_opt->num_sacks = 0; 1177 } 1178 1179 u32 tcp_default_init_rwnd(u32 mss); 1180 void tcp_cwnd_restart(struct sock *sk, s32 delta); 1181 1182 static inline void tcp_slow_start_after_idle_check(struct sock *sk) 1183 { 1184 struct tcp_sock *tp = tcp_sk(sk); 1185 s32 delta; 1186 1187 if (!sysctl_tcp_slow_start_after_idle || tp->packets_out) 1188 return; 1189 delta = tcp_time_stamp - tp->lsndtime; 1190 if (delta > inet_csk(sk)->icsk_rto) 1191 tcp_cwnd_restart(sk, delta); 1192 } 1193 1194 /* Determine a window scaling and initial window to offer. */ 1195 void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd, 1196 __u32 *window_clamp, int wscale_ok, 1197 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1198 1199 static inline int tcp_win_from_space(int space) 1200 { 1201 return sysctl_tcp_adv_win_scale<=0 ? 1202 (space>>(-sysctl_tcp_adv_win_scale)) : 1203 space - (space>>sysctl_tcp_adv_win_scale); 1204 } 1205 1206 /* Note: caller must be prepared to deal with negative returns */ 1207 static inline int tcp_space(const struct sock *sk) 1208 { 1209 return tcp_win_from_space(sk->sk_rcvbuf - 1210 atomic_read(&sk->sk_rmem_alloc)); 1211 } 1212 1213 static inline int tcp_full_space(const struct sock *sk) 1214 { 1215 return tcp_win_from_space(sk->sk_rcvbuf); 1216 } 1217 1218 extern void tcp_openreq_init_rwin(struct request_sock *req, 1219 const struct sock *sk_listener, 1220 const struct dst_entry *dst); 1221 1222 void tcp_enter_memory_pressure(struct sock *sk); 1223 1224 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1225 { 1226 struct net *net = sock_net((struct sock *)tp); 1227 1228 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl; 1229 } 1230 1231 static inline int keepalive_time_when(const struct tcp_sock *tp) 1232 { 1233 struct net *net = sock_net((struct sock *)tp); 1234 1235 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time; 1236 } 1237 1238 static inline int keepalive_probes(const struct tcp_sock *tp) 1239 { 1240 struct net *net = sock_net((struct sock *)tp); 1241 1242 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes; 1243 } 1244 1245 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1246 { 1247 const struct inet_connection_sock *icsk = &tp->inet_conn; 1248 1249 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime, 1250 tcp_time_stamp - tp->rcv_tstamp); 1251 } 1252 1253 static inline int tcp_fin_time(const struct sock *sk) 1254 { 1255 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout; 1256 const int rto = inet_csk(sk)->icsk_rto; 1257 1258 if (fin_timeout < (rto << 2) - (rto >> 1)) 1259 fin_timeout = (rto << 2) - (rto >> 1); 1260 1261 return fin_timeout; 1262 } 1263 1264 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1265 int paws_win) 1266 { 1267 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1268 return true; 1269 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1270 return true; 1271 /* 1272 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1273 * then following tcp messages have valid values. Ignore 0 value, 1274 * or else 'negative' tsval might forbid us to accept their packets. 1275 */ 1276 if (!rx_opt->ts_recent) 1277 return true; 1278 return false; 1279 } 1280 1281 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1282 int rst) 1283 { 1284 if (tcp_paws_check(rx_opt, 0)) 1285 return false; 1286 1287 /* RST segments are not recommended to carry timestamp, 1288 and, if they do, it is recommended to ignore PAWS because 1289 "their cleanup function should take precedence over timestamps." 1290 Certainly, it is mistake. It is necessary to understand the reasons 1291 of this constraint to relax it: if peer reboots, clock may go 1292 out-of-sync and half-open connections will not be reset. 1293 Actually, the problem would be not existing if all 1294 the implementations followed draft about maintaining clock 1295 via reboots. Linux-2.2 DOES NOT! 1296 1297 However, we can relax time bounds for RST segments to MSL. 1298 */ 1299 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1300 return false; 1301 return true; 1302 } 1303 1304 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, 1305 int mib_idx, u32 *last_oow_ack_time); 1306 1307 static inline void tcp_mib_init(struct net *net) 1308 { 1309 /* See RFC 2012 */ 1310 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1); 1311 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1312 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1313 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1); 1314 } 1315 1316 /* from STCP */ 1317 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1318 { 1319 tp->lost_skb_hint = NULL; 1320 } 1321 1322 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1323 { 1324 tcp_clear_retrans_hints_partial(tp); 1325 tp->retransmit_skb_hint = NULL; 1326 } 1327 1328 /* MD5 Signature */ 1329 struct crypto_hash; 1330 1331 union tcp_md5_addr { 1332 struct in_addr a4; 1333 #if IS_ENABLED(CONFIG_IPV6) 1334 struct in6_addr a6; 1335 #endif 1336 }; 1337 1338 /* - key database */ 1339 struct tcp_md5sig_key { 1340 struct hlist_node node; 1341 u8 keylen; 1342 u8 family; /* AF_INET or AF_INET6 */ 1343 union tcp_md5_addr addr; 1344 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1345 struct rcu_head rcu; 1346 }; 1347 1348 /* - sock block */ 1349 struct tcp_md5sig_info { 1350 struct hlist_head head; 1351 struct rcu_head rcu; 1352 }; 1353 1354 /* - pseudo header */ 1355 struct tcp4_pseudohdr { 1356 __be32 saddr; 1357 __be32 daddr; 1358 __u8 pad; 1359 __u8 protocol; 1360 __be16 len; 1361 }; 1362 1363 struct tcp6_pseudohdr { 1364 struct in6_addr saddr; 1365 struct in6_addr daddr; 1366 __be32 len; 1367 __be32 protocol; /* including padding */ 1368 }; 1369 1370 union tcp_md5sum_block { 1371 struct tcp4_pseudohdr ip4; 1372 #if IS_ENABLED(CONFIG_IPV6) 1373 struct tcp6_pseudohdr ip6; 1374 #endif 1375 }; 1376 1377 /* - pool: digest algorithm, hash description and scratch buffer */ 1378 struct tcp_md5sig_pool { 1379 struct hash_desc md5_desc; 1380 union tcp_md5sum_block md5_blk; 1381 }; 1382 1383 /* - functions */ 1384 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1385 const struct sock *sk, const struct sk_buff *skb); 1386 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1387 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp); 1388 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1389 int family); 1390 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 1391 const struct sock *addr_sk); 1392 1393 #ifdef CONFIG_TCP_MD5SIG 1394 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1395 const union tcp_md5_addr *addr, 1396 int family); 1397 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1398 #else 1399 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1400 const union tcp_md5_addr *addr, 1401 int family) 1402 { 1403 return NULL; 1404 } 1405 #define tcp_twsk_md5_key(twsk) NULL 1406 #endif 1407 1408 bool tcp_alloc_md5sig_pool(void); 1409 1410 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1411 static inline void tcp_put_md5sig_pool(void) 1412 { 1413 local_bh_enable(); 1414 } 1415 1416 int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *); 1417 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1418 unsigned int header_len); 1419 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1420 const struct tcp_md5sig_key *key); 1421 1422 /* From tcp_fastopen.c */ 1423 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1424 struct tcp_fastopen_cookie *cookie, int *syn_loss, 1425 unsigned long *last_syn_loss); 1426 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1427 struct tcp_fastopen_cookie *cookie, bool syn_lost, 1428 u16 try_exp); 1429 struct tcp_fastopen_request { 1430 /* Fast Open cookie. Size 0 means a cookie request */ 1431 struct tcp_fastopen_cookie cookie; 1432 struct msghdr *data; /* data in MSG_FASTOPEN */ 1433 size_t size; 1434 int copied; /* queued in tcp_connect() */ 1435 }; 1436 void tcp_free_fastopen_req(struct tcp_sock *tp); 1437 1438 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; 1439 int tcp_fastopen_reset_cipher(void *key, unsigned int len); 1440 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1441 struct request_sock *req, 1442 struct tcp_fastopen_cookie *foc, 1443 struct dst_entry *dst); 1444 void tcp_fastopen_init_key_once(bool publish); 1445 #define TCP_FASTOPEN_KEY_LENGTH 16 1446 1447 /* Fastopen key context */ 1448 struct tcp_fastopen_context { 1449 struct crypto_cipher *tfm; 1450 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1451 struct rcu_head rcu; 1452 }; 1453 1454 /* write queue abstraction */ 1455 static inline void tcp_write_queue_purge(struct sock *sk) 1456 { 1457 struct sk_buff *skb; 1458 1459 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) 1460 sk_wmem_free_skb(sk, skb); 1461 sk_mem_reclaim(sk); 1462 tcp_clear_all_retrans_hints(tcp_sk(sk)); 1463 } 1464 1465 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1466 { 1467 return skb_peek(&sk->sk_write_queue); 1468 } 1469 1470 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1471 { 1472 return skb_peek_tail(&sk->sk_write_queue); 1473 } 1474 1475 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk, 1476 const struct sk_buff *skb) 1477 { 1478 return skb_queue_next(&sk->sk_write_queue, skb); 1479 } 1480 1481 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk, 1482 const struct sk_buff *skb) 1483 { 1484 return skb_queue_prev(&sk->sk_write_queue, skb); 1485 } 1486 1487 #define tcp_for_write_queue(skb, sk) \ 1488 skb_queue_walk(&(sk)->sk_write_queue, skb) 1489 1490 #define tcp_for_write_queue_from(skb, sk) \ 1491 skb_queue_walk_from(&(sk)->sk_write_queue, skb) 1492 1493 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1494 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1495 1496 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1497 { 1498 return sk->sk_send_head; 1499 } 1500 1501 static inline bool tcp_skb_is_last(const struct sock *sk, 1502 const struct sk_buff *skb) 1503 { 1504 return skb_queue_is_last(&sk->sk_write_queue, skb); 1505 } 1506 1507 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb) 1508 { 1509 if (tcp_skb_is_last(sk, skb)) 1510 sk->sk_send_head = NULL; 1511 else 1512 sk->sk_send_head = tcp_write_queue_next(sk, skb); 1513 } 1514 1515 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1516 { 1517 if (sk->sk_send_head == skb_unlinked) 1518 sk->sk_send_head = NULL; 1519 } 1520 1521 static inline void tcp_init_send_head(struct sock *sk) 1522 { 1523 sk->sk_send_head = NULL; 1524 } 1525 1526 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1527 { 1528 __skb_queue_tail(&sk->sk_write_queue, skb); 1529 } 1530 1531 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1532 { 1533 __tcp_add_write_queue_tail(sk, skb); 1534 1535 /* Queue it, remembering where we must start sending. */ 1536 if (sk->sk_send_head == NULL) { 1537 sk->sk_send_head = skb; 1538 1539 if (tcp_sk(sk)->highest_sack == NULL) 1540 tcp_sk(sk)->highest_sack = skb; 1541 } 1542 } 1543 1544 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb) 1545 { 1546 __skb_queue_head(&sk->sk_write_queue, skb); 1547 } 1548 1549 /* Insert buff after skb on the write queue of sk. */ 1550 static inline void tcp_insert_write_queue_after(struct sk_buff *skb, 1551 struct sk_buff *buff, 1552 struct sock *sk) 1553 { 1554 __skb_queue_after(&sk->sk_write_queue, skb, buff); 1555 } 1556 1557 /* Insert new before skb on the write queue of sk. */ 1558 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1559 struct sk_buff *skb, 1560 struct sock *sk) 1561 { 1562 __skb_queue_before(&sk->sk_write_queue, skb, new); 1563 1564 if (sk->sk_send_head == skb) 1565 sk->sk_send_head = new; 1566 } 1567 1568 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1569 { 1570 __skb_unlink(skb, &sk->sk_write_queue); 1571 } 1572 1573 static inline bool tcp_write_queue_empty(struct sock *sk) 1574 { 1575 return skb_queue_empty(&sk->sk_write_queue); 1576 } 1577 1578 static inline void tcp_push_pending_frames(struct sock *sk) 1579 { 1580 if (tcp_send_head(sk)) { 1581 struct tcp_sock *tp = tcp_sk(sk); 1582 1583 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1584 } 1585 } 1586 1587 /* Start sequence of the skb just after the highest skb with SACKed 1588 * bit, valid only if sacked_out > 0 or when the caller has ensured 1589 * validity by itself. 1590 */ 1591 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1592 { 1593 if (!tp->sacked_out) 1594 return tp->snd_una; 1595 1596 if (tp->highest_sack == NULL) 1597 return tp->snd_nxt; 1598 1599 return TCP_SKB_CB(tp->highest_sack)->seq; 1600 } 1601 1602 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1603 { 1604 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL : 1605 tcp_write_queue_next(sk, skb); 1606 } 1607 1608 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1609 { 1610 return tcp_sk(sk)->highest_sack; 1611 } 1612 1613 static inline void tcp_highest_sack_reset(struct sock *sk) 1614 { 1615 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk); 1616 } 1617 1618 /* Called when old skb is about to be deleted (to be combined with new skb) */ 1619 static inline void tcp_highest_sack_combine(struct sock *sk, 1620 struct sk_buff *old, 1621 struct sk_buff *new) 1622 { 1623 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack)) 1624 tcp_sk(sk)->highest_sack = new; 1625 } 1626 1627 /* This helper checks if socket has IP_TRANSPARENT set */ 1628 static inline bool inet_sk_transparent(const struct sock *sk) 1629 { 1630 switch (sk->sk_state) { 1631 case TCP_TIME_WAIT: 1632 return inet_twsk(sk)->tw_transparent; 1633 case TCP_NEW_SYN_RECV: 1634 return inet_rsk(inet_reqsk(sk))->no_srccheck; 1635 } 1636 return inet_sk(sk)->transparent; 1637 } 1638 1639 /* Determines whether this is a thin stream (which may suffer from 1640 * increased latency). Used to trigger latency-reducing mechanisms. 1641 */ 1642 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1643 { 1644 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1645 } 1646 1647 /* /proc */ 1648 enum tcp_seq_states { 1649 TCP_SEQ_STATE_LISTENING, 1650 TCP_SEQ_STATE_ESTABLISHED, 1651 }; 1652 1653 int tcp_seq_open(struct inode *inode, struct file *file); 1654 1655 struct tcp_seq_afinfo { 1656 char *name; 1657 sa_family_t family; 1658 const struct file_operations *seq_fops; 1659 struct seq_operations seq_ops; 1660 }; 1661 1662 struct tcp_iter_state { 1663 struct seq_net_private p; 1664 sa_family_t family; 1665 enum tcp_seq_states state; 1666 struct sock *syn_wait_sk; 1667 int bucket, offset, sbucket, num; 1668 loff_t last_pos; 1669 }; 1670 1671 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1672 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1673 1674 extern struct request_sock_ops tcp_request_sock_ops; 1675 extern struct request_sock_ops tcp6_request_sock_ops; 1676 1677 void tcp_v4_destroy_sock(struct sock *sk); 1678 1679 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 1680 netdev_features_t features); 1681 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb); 1682 int tcp_gro_complete(struct sk_buff *skb); 1683 1684 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 1685 1686 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 1687 { 1688 return tp->notsent_lowat ?: sysctl_tcp_notsent_lowat; 1689 } 1690 1691 static inline bool tcp_stream_memory_free(const struct sock *sk) 1692 { 1693 const struct tcp_sock *tp = tcp_sk(sk); 1694 u32 notsent_bytes = tp->write_seq - tp->snd_nxt; 1695 1696 return notsent_bytes < tcp_notsent_lowat(tp); 1697 } 1698 1699 #ifdef CONFIG_PROC_FS 1700 int tcp4_proc_init(void); 1701 void tcp4_proc_exit(void); 1702 #endif 1703 1704 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req); 1705 int tcp_conn_request(struct request_sock_ops *rsk_ops, 1706 const struct tcp_request_sock_ops *af_ops, 1707 struct sock *sk, struct sk_buff *skb); 1708 1709 /* TCP af-specific functions */ 1710 struct tcp_sock_af_ops { 1711 #ifdef CONFIG_TCP_MD5SIG 1712 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk, 1713 const struct sock *addr_sk); 1714 int (*calc_md5_hash)(char *location, 1715 const struct tcp_md5sig_key *md5, 1716 const struct sock *sk, 1717 const struct sk_buff *skb); 1718 int (*md5_parse)(struct sock *sk, 1719 char __user *optval, 1720 int optlen); 1721 #endif 1722 }; 1723 1724 struct tcp_request_sock_ops { 1725 u16 mss_clamp; 1726 #ifdef CONFIG_TCP_MD5SIG 1727 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk, 1728 const struct sock *addr_sk); 1729 int (*calc_md5_hash) (char *location, 1730 const struct tcp_md5sig_key *md5, 1731 const struct sock *sk, 1732 const struct sk_buff *skb); 1733 #endif 1734 void (*init_req)(struct request_sock *req, 1735 const struct sock *sk_listener, 1736 struct sk_buff *skb); 1737 #ifdef CONFIG_SYN_COOKIES 1738 __u32 (*cookie_init_seq)(const struct sk_buff *skb, 1739 __u16 *mss); 1740 #endif 1741 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl, 1742 const struct request_sock *req, 1743 bool *strict); 1744 __u32 (*init_seq)(const struct sk_buff *skb); 1745 int (*send_synack)(const struct sock *sk, struct dst_entry *dst, 1746 struct flowi *fl, struct request_sock *req, 1747 struct tcp_fastopen_cookie *foc, 1748 bool attach_req); 1749 }; 1750 1751 #ifdef CONFIG_SYN_COOKIES 1752 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1753 const struct sock *sk, struct sk_buff *skb, 1754 __u16 *mss) 1755 { 1756 tcp_synq_overflow(sk); 1757 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); 1758 return ops->cookie_init_seq(skb, mss); 1759 } 1760 #else 1761 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1762 const struct sock *sk, struct sk_buff *skb, 1763 __u16 *mss) 1764 { 1765 return 0; 1766 } 1767 #endif 1768 1769 int tcpv4_offload_init(void); 1770 1771 void tcp_v4_init(void); 1772 void tcp_init(void); 1773 1774 /* tcp_recovery.c */ 1775 1776 /* Flags to enable various loss recovery features. See below */ 1777 extern int sysctl_tcp_recovery; 1778 1779 /* Use TCP RACK to detect (some) tail and retransmit losses */ 1780 #define TCP_RACK_LOST_RETRANS 0x1 1781 1782 extern int tcp_rack_mark_lost(struct sock *sk); 1783 1784 extern void tcp_rack_advance(struct tcp_sock *tp, 1785 const struct skb_mstamp *xmit_time, u8 sacked); 1786 1787 /* 1788 * Save and compile IPv4 options, return a pointer to it 1789 */ 1790 static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb) 1791 { 1792 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; 1793 struct ip_options_rcu *dopt = NULL; 1794 1795 if (opt->optlen) { 1796 int opt_size = sizeof(*dopt) + opt->optlen; 1797 1798 dopt = kmalloc(opt_size, GFP_ATOMIC); 1799 if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) { 1800 kfree(dopt); 1801 dopt = NULL; 1802 } 1803 } 1804 return dopt; 1805 } 1806 1807 /* locally generated TCP pure ACKs have skb->truesize == 2 1808 * (check tcp_send_ack() in net/ipv4/tcp_output.c ) 1809 * This is much faster than dissecting the packet to find out. 1810 * (Think of GRE encapsulations, IPv4, IPv6, ...) 1811 */ 1812 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb) 1813 { 1814 return skb->truesize == 2; 1815 } 1816 1817 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb) 1818 { 1819 skb->truesize = 2; 1820 } 1821 1822 #endif /* _TCP_H */ 1823