1 /* 2 * INET An implementation of the TCP/IP protocol suite for the LINUX 3 * operating system. INET is implemented using the BSD Socket 4 * interface as the means of communication with the user level. 5 * 6 * Definitions for the TCP module. 7 * 8 * Version: @(#)tcp.h 1.0.5 05/23/93 9 * 10 * Authors: Ross Biro 11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 12 * 13 * This program is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU General Public License 15 * as published by the Free Software Foundation; either version 16 * 2 of the License, or (at your option) any later version. 17 */ 18 #ifndef _TCP_H 19 #define _TCP_H 20 21 #define FASTRETRANS_DEBUG 1 22 23 #include <linux/list.h> 24 #include <linux/tcp.h> 25 #include <linux/bug.h> 26 #include <linux/slab.h> 27 #include <linux/cache.h> 28 #include <linux/percpu.h> 29 #include <linux/skbuff.h> 30 #include <linux/cryptohash.h> 31 #include <linux/kref.h> 32 #include <linux/ktime.h> 33 34 #include <net/inet_connection_sock.h> 35 #include <net/inet_timewait_sock.h> 36 #include <net/inet_hashtables.h> 37 #include <net/checksum.h> 38 #include <net/request_sock.h> 39 #include <net/sock.h> 40 #include <net/snmp.h> 41 #include <net/ip.h> 42 #include <net/tcp_states.h> 43 #include <net/inet_ecn.h> 44 #include <net/dst.h> 45 46 #include <linux/seq_file.h> 47 #include <linux/memcontrol.h> 48 49 extern struct inet_hashinfo tcp_hashinfo; 50 51 extern struct percpu_counter tcp_orphan_count; 52 void tcp_time_wait(struct sock *sk, int state, int timeo); 53 54 #define MAX_TCP_HEADER (128 + MAX_HEADER) 55 #define MAX_TCP_OPTION_SPACE 40 56 57 /* 58 * Never offer a window over 32767 without using window scaling. Some 59 * poor stacks do signed 16bit maths! 60 */ 61 #define MAX_TCP_WINDOW 32767U 62 63 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */ 64 #define TCP_MIN_MSS 88U 65 66 /* The least MTU to use for probing */ 67 #define TCP_BASE_MSS 1024 68 69 /* probing interval, default to 10 minutes as per RFC4821 */ 70 #define TCP_PROBE_INTERVAL 600 71 72 /* Specify interval when tcp mtu probing will stop */ 73 #define TCP_PROBE_THRESHOLD 8 74 75 /* After receiving this amount of duplicate ACKs fast retransmit starts. */ 76 #define TCP_FASTRETRANS_THRESH 3 77 78 /* Maximal number of ACKs sent quickly to accelerate slow-start. */ 79 #define TCP_MAX_QUICKACKS 16U 80 81 /* urg_data states */ 82 #define TCP_URG_VALID 0x0100 83 #define TCP_URG_NOTYET 0x0200 84 #define TCP_URG_READ 0x0400 85 86 #define TCP_RETR1 3 /* 87 * This is how many retries it does before it 88 * tries to figure out if the gateway is 89 * down. Minimal RFC value is 3; it corresponds 90 * to ~3sec-8min depending on RTO. 91 */ 92 93 #define TCP_RETR2 15 /* 94 * This should take at least 95 * 90 minutes to time out. 96 * RFC1122 says that the limit is 100 sec. 97 * 15 is ~13-30min depending on RTO. 98 */ 99 100 #define TCP_SYN_RETRIES 6 /* This is how many retries are done 101 * when active opening a connection. 102 * RFC1122 says the minimum retry MUST 103 * be at least 180secs. Nevertheless 104 * this value is corresponding to 105 * 63secs of retransmission with the 106 * current initial RTO. 107 */ 108 109 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done 110 * when passive opening a connection. 111 * This is corresponding to 31secs of 112 * retransmission with the current 113 * initial RTO. 114 */ 115 116 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT 117 * state, about 60 seconds */ 118 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN 119 /* BSD style FIN_WAIT2 deadlock breaker. 120 * It used to be 3min, new value is 60sec, 121 * to combine FIN-WAIT-2 timeout with 122 * TIME-WAIT timer. 123 */ 124 125 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ 126 #if HZ >= 100 127 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */ 128 #define TCP_ATO_MIN ((unsigned)(HZ/25)) 129 #else 130 #define TCP_DELACK_MIN 4U 131 #define TCP_ATO_MIN 4U 132 #endif 133 #define TCP_RTO_MAX ((unsigned)(120*HZ)) 134 #define TCP_RTO_MIN ((unsigned)(HZ/5)) 135 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */ 136 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now 137 * used as a fallback RTO for the 138 * initial data transmission if no 139 * valid RTT sample has been acquired, 140 * most likely due to retrans in 3WHS. 141 */ 142 143 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes 144 * for local resources. 145 */ 146 147 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ 148 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ 149 #define TCP_KEEPALIVE_INTVL (75*HZ) 150 151 #define MAX_TCP_KEEPIDLE 32767 152 #define MAX_TCP_KEEPINTVL 32767 153 #define MAX_TCP_KEEPCNT 127 154 #define MAX_TCP_SYNCNT 127 155 156 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */ 157 158 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24) 159 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated 160 * after this time. It should be equal 161 * (or greater than) TCP_TIMEWAIT_LEN 162 * to provide reliability equal to one 163 * provided by timewait state. 164 */ 165 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host 166 * timestamps. It must be less than 167 * minimal timewait lifetime. 168 */ 169 /* 170 * TCP option 171 */ 172 173 #define TCPOPT_NOP 1 /* Padding */ 174 #define TCPOPT_EOL 0 /* End of options */ 175 #define TCPOPT_MSS 2 /* Segment size negotiating */ 176 #define TCPOPT_WINDOW 3 /* Window scaling */ 177 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ 178 #define TCPOPT_SACK 5 /* SACK Block */ 179 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ 180 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */ 181 #define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */ 182 #define TCPOPT_EXP 254 /* Experimental */ 183 /* Magic number to be after the option value for sharing TCP 184 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt 185 */ 186 #define TCPOPT_FASTOPEN_MAGIC 0xF989 187 188 /* 189 * TCP option lengths 190 */ 191 192 #define TCPOLEN_MSS 4 193 #define TCPOLEN_WINDOW 3 194 #define TCPOLEN_SACK_PERM 2 195 #define TCPOLEN_TIMESTAMP 10 196 #define TCPOLEN_MD5SIG 18 197 #define TCPOLEN_FASTOPEN_BASE 2 198 #define TCPOLEN_EXP_FASTOPEN_BASE 4 199 200 /* But this is what stacks really send out. */ 201 #define TCPOLEN_TSTAMP_ALIGNED 12 202 #define TCPOLEN_WSCALE_ALIGNED 4 203 #define TCPOLEN_SACKPERM_ALIGNED 4 204 #define TCPOLEN_SACK_BASE 2 205 #define TCPOLEN_SACK_BASE_ALIGNED 4 206 #define TCPOLEN_SACK_PERBLOCK 8 207 #define TCPOLEN_MD5SIG_ALIGNED 20 208 #define TCPOLEN_MSS_ALIGNED 4 209 210 /* Flags in tp->nonagle */ 211 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */ 212 #define TCP_NAGLE_CORK 2 /* Socket is corked */ 213 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */ 214 215 /* TCP thin-stream limits */ 216 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */ 217 218 /* TCP initial congestion window as per rfc6928 */ 219 #define TCP_INIT_CWND 10 220 221 /* Bit Flags for sysctl_tcp_fastopen */ 222 #define TFO_CLIENT_ENABLE 1 223 #define TFO_SERVER_ENABLE 2 224 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */ 225 226 /* Accept SYN data w/o any cookie option */ 227 #define TFO_SERVER_COOKIE_NOT_REQD 0x200 228 229 /* Force enable TFO on all listeners, i.e., not requiring the 230 * TCP_FASTOPEN socket option. 231 */ 232 #define TFO_SERVER_WO_SOCKOPT1 0x400 233 234 extern struct inet_timewait_death_row tcp_death_row; 235 236 /* sysctl variables for tcp */ 237 extern int sysctl_tcp_timestamps; 238 extern int sysctl_tcp_window_scaling; 239 extern int sysctl_tcp_sack; 240 extern int sysctl_tcp_fastopen; 241 extern int sysctl_tcp_retrans_collapse; 242 extern int sysctl_tcp_stdurg; 243 extern int sysctl_tcp_rfc1337; 244 extern int sysctl_tcp_abort_on_overflow; 245 extern int sysctl_tcp_max_orphans; 246 extern int sysctl_tcp_fack; 247 extern int sysctl_tcp_reordering; 248 extern int sysctl_tcp_max_reordering; 249 extern int sysctl_tcp_dsack; 250 extern long sysctl_tcp_mem[3]; 251 extern int sysctl_tcp_wmem[3]; 252 extern int sysctl_tcp_rmem[3]; 253 extern int sysctl_tcp_app_win; 254 extern int sysctl_tcp_adv_win_scale; 255 extern int sysctl_tcp_tw_reuse; 256 extern int sysctl_tcp_frto; 257 extern int sysctl_tcp_low_latency; 258 extern int sysctl_tcp_nometrics_save; 259 extern int sysctl_tcp_moderate_rcvbuf; 260 extern int sysctl_tcp_tso_win_divisor; 261 extern int sysctl_tcp_workaround_signed_windows; 262 extern int sysctl_tcp_slow_start_after_idle; 263 extern int sysctl_tcp_thin_linear_timeouts; 264 extern int sysctl_tcp_thin_dupack; 265 extern int sysctl_tcp_early_retrans; 266 extern int sysctl_tcp_limit_output_bytes; 267 extern int sysctl_tcp_challenge_ack_limit; 268 extern int sysctl_tcp_min_tso_segs; 269 extern int sysctl_tcp_min_rtt_wlen; 270 extern int sysctl_tcp_autocorking; 271 extern int sysctl_tcp_invalid_ratelimit; 272 extern int sysctl_tcp_pacing_ss_ratio; 273 extern int sysctl_tcp_pacing_ca_ratio; 274 275 extern atomic_long_t tcp_memory_allocated; 276 extern struct percpu_counter tcp_sockets_allocated; 277 extern int tcp_memory_pressure; 278 279 /* optimized version of sk_under_memory_pressure() for TCP sockets */ 280 static inline bool tcp_under_memory_pressure(const struct sock *sk) 281 { 282 if (mem_cgroup_sockets_enabled && sk->sk_memcg && 283 mem_cgroup_under_socket_pressure(sk->sk_memcg)) 284 return true; 285 286 return tcp_memory_pressure; 287 } 288 /* 289 * The next routines deal with comparing 32 bit unsigned ints 290 * and worry about wraparound (automatic with unsigned arithmetic). 291 */ 292 293 static inline bool before(__u32 seq1, __u32 seq2) 294 { 295 return (__s32)(seq1-seq2) < 0; 296 } 297 #define after(seq2, seq1) before(seq1, seq2) 298 299 /* is s2<=s1<=s3 ? */ 300 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) 301 { 302 return seq3 - seq2 >= seq1 - seq2; 303 } 304 305 static inline bool tcp_out_of_memory(struct sock *sk) 306 { 307 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 308 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2)) 309 return true; 310 return false; 311 } 312 313 void sk_forced_mem_schedule(struct sock *sk, int size); 314 315 static inline bool tcp_too_many_orphans(struct sock *sk, int shift) 316 { 317 struct percpu_counter *ocp = sk->sk_prot->orphan_count; 318 int orphans = percpu_counter_read_positive(ocp); 319 320 if (orphans << shift > sysctl_tcp_max_orphans) { 321 orphans = percpu_counter_sum_positive(ocp); 322 if (orphans << shift > sysctl_tcp_max_orphans) 323 return true; 324 } 325 return false; 326 } 327 328 bool tcp_check_oom(struct sock *sk, int shift); 329 330 331 extern struct proto tcp_prot; 332 333 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 334 #define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field) 335 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 336 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 337 338 void tcp_tasklet_init(void); 339 340 void tcp_v4_err(struct sk_buff *skb, u32); 341 342 void tcp_shutdown(struct sock *sk, int how); 343 344 void tcp_v4_early_demux(struct sk_buff *skb); 345 int tcp_v4_rcv(struct sk_buff *skb); 346 347 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 348 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size); 349 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, 350 int flags); 351 void tcp_release_cb(struct sock *sk); 352 void tcp_wfree(struct sk_buff *skb); 353 void tcp_write_timer_handler(struct sock *sk); 354 void tcp_delack_timer_handler(struct sock *sk); 355 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 356 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb); 357 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 358 const struct tcphdr *th, unsigned int len); 359 void tcp_rcv_space_adjust(struct sock *sk); 360 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 361 void tcp_twsk_destructor(struct sock *sk); 362 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 363 struct pipe_inode_info *pipe, size_t len, 364 unsigned int flags); 365 366 static inline void tcp_dec_quickack_mode(struct sock *sk, 367 const unsigned int pkts) 368 { 369 struct inet_connection_sock *icsk = inet_csk(sk); 370 371 if (icsk->icsk_ack.quick) { 372 if (pkts >= icsk->icsk_ack.quick) { 373 icsk->icsk_ack.quick = 0; 374 /* Leaving quickack mode we deflate ATO. */ 375 icsk->icsk_ack.ato = TCP_ATO_MIN; 376 } else 377 icsk->icsk_ack.quick -= pkts; 378 } 379 } 380 381 #define TCP_ECN_OK 1 382 #define TCP_ECN_QUEUE_CWR 2 383 #define TCP_ECN_DEMAND_CWR 4 384 #define TCP_ECN_SEEN 8 385 386 enum tcp_tw_status { 387 TCP_TW_SUCCESS = 0, 388 TCP_TW_RST = 1, 389 TCP_TW_ACK = 2, 390 TCP_TW_SYN = 3 391 }; 392 393 394 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 395 struct sk_buff *skb, 396 const struct tcphdr *th); 397 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 398 struct request_sock *req, bool fastopen); 399 int tcp_child_process(struct sock *parent, struct sock *child, 400 struct sk_buff *skb); 401 void tcp_enter_loss(struct sock *sk); 402 void tcp_clear_retrans(struct tcp_sock *tp); 403 void tcp_update_metrics(struct sock *sk); 404 void tcp_init_metrics(struct sock *sk); 405 void tcp_metrics_init(void); 406 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, 407 bool paws_check, bool timestamps); 408 bool tcp_remember_stamp(struct sock *sk); 409 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw); 410 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst); 411 void tcp_disable_fack(struct tcp_sock *tp); 412 void tcp_close(struct sock *sk, long timeout); 413 void tcp_init_sock(struct sock *sk); 414 unsigned int tcp_poll(struct file *file, struct socket *sock, 415 struct poll_table_struct *wait); 416 int tcp_getsockopt(struct sock *sk, int level, int optname, 417 char __user *optval, int __user *optlen); 418 int tcp_setsockopt(struct sock *sk, int level, int optname, 419 char __user *optval, unsigned int optlen); 420 int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 421 char __user *optval, int __user *optlen); 422 int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 423 char __user *optval, unsigned int optlen); 424 void tcp_set_keepalive(struct sock *sk, int val); 425 void tcp_syn_ack_timeout(const struct request_sock *req); 426 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, 427 int flags, int *addr_len); 428 void tcp_parse_options(const struct sk_buff *skb, 429 struct tcp_options_received *opt_rx, 430 int estab, struct tcp_fastopen_cookie *foc); 431 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); 432 433 /* 434 * TCP v4 functions exported for the inet6 API 435 */ 436 437 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 438 void tcp_v4_mtu_reduced(struct sock *sk); 439 void tcp_req_err(struct sock *sk, u32 seq, bool abort); 440 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 441 struct sock *tcp_create_openreq_child(const struct sock *sk, 442 struct request_sock *req, 443 struct sk_buff *skb); 444 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst); 445 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 446 struct request_sock *req, 447 struct dst_entry *dst, 448 struct request_sock *req_unhash, 449 bool *own_req); 450 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 451 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); 452 int tcp_connect(struct sock *sk); 453 enum tcp_synack_type { 454 TCP_SYNACK_NORMAL, 455 TCP_SYNACK_FASTOPEN, 456 TCP_SYNACK_COOKIE, 457 }; 458 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 459 struct request_sock *req, 460 struct tcp_fastopen_cookie *foc, 461 enum tcp_synack_type synack_type); 462 int tcp_disconnect(struct sock *sk, int flags); 463 464 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 465 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 466 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); 467 468 /* From syncookies.c */ 469 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, 470 struct request_sock *req, 471 struct dst_entry *dst); 472 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th, 473 u32 cookie); 474 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb); 475 #ifdef CONFIG_SYN_COOKIES 476 477 /* Syncookies use a monotonic timer which increments every 60 seconds. 478 * This counter is used both as a hash input and partially encoded into 479 * the cookie value. A cookie is only validated further if the delta 480 * between the current counter value and the encoded one is less than this, 481 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if 482 * the counter advances immediately after a cookie is generated). 483 */ 484 #define MAX_SYNCOOKIE_AGE 2 485 #define TCP_SYNCOOKIE_PERIOD (60 * HZ) 486 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD) 487 488 /* syncookies: remember time of last synqueue overflow 489 * But do not dirty this field too often (once per second is enough) 490 * It is racy as we do not hold a lock, but race is very minor. 491 */ 492 static inline void tcp_synq_overflow(const struct sock *sk) 493 { 494 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 495 unsigned long now = jiffies; 496 497 if (time_after(now, last_overflow + HZ)) 498 tcp_sk(sk)->rx_opt.ts_recent_stamp = now; 499 } 500 501 /* syncookies: no recent synqueue overflow on this listening socket? */ 502 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 503 { 504 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 505 506 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID); 507 } 508 509 static inline u32 tcp_cookie_time(void) 510 { 511 u64 val = get_jiffies_64(); 512 513 do_div(val, TCP_SYNCOOKIE_PERIOD); 514 return val; 515 } 516 517 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, 518 u16 *mssp); 519 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss); 520 __u32 cookie_init_timestamp(struct request_sock *req); 521 bool cookie_timestamp_decode(struct tcp_options_received *opt); 522 bool cookie_ecn_ok(const struct tcp_options_received *opt, 523 const struct net *net, const struct dst_entry *dst); 524 525 /* From net/ipv6/syncookies.c */ 526 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th, 527 u32 cookie); 528 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 529 530 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph, 531 const struct tcphdr *th, u16 *mssp); 532 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss); 533 #endif 534 /* tcp_output.c */ 535 536 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 537 int nonagle); 538 bool tcp_may_send_now(struct sock *sk); 539 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 540 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 541 void tcp_retransmit_timer(struct sock *sk); 542 void tcp_xmit_retransmit_queue(struct sock *); 543 void tcp_simple_retransmit(struct sock *); 544 int tcp_trim_head(struct sock *, struct sk_buff *, u32); 545 int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t); 546 547 void tcp_send_probe0(struct sock *); 548 void tcp_send_partial(struct sock *); 549 int tcp_write_wakeup(struct sock *, int mib); 550 void tcp_send_fin(struct sock *sk); 551 void tcp_send_active_reset(struct sock *sk, gfp_t priority); 552 int tcp_send_synack(struct sock *); 553 void tcp_push_one(struct sock *, unsigned int mss_now); 554 void tcp_send_ack(struct sock *sk); 555 void tcp_send_delayed_ack(struct sock *sk); 556 void tcp_send_loss_probe(struct sock *sk); 557 bool tcp_schedule_loss_probe(struct sock *sk); 558 void tcp_skb_collapse_tstamp(struct sk_buff *skb, 559 const struct sk_buff *next_skb); 560 561 /* tcp_input.c */ 562 void tcp_resume_early_retransmit(struct sock *sk); 563 void tcp_rearm_rto(struct sock *sk); 564 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req); 565 void tcp_reset(struct sock *sk); 566 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb); 567 void tcp_fin(struct sock *sk); 568 569 /* tcp_timer.c */ 570 void tcp_init_xmit_timers(struct sock *); 571 static inline void tcp_clear_xmit_timers(struct sock *sk) 572 { 573 inet_csk_clear_xmit_timers(sk); 574 } 575 576 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 577 unsigned int tcp_current_mss(struct sock *sk); 578 579 /* Bound MSS / TSO packet size with the half of the window */ 580 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 581 { 582 int cutoff; 583 584 /* When peer uses tiny windows, there is no use in packetizing 585 * to sub-MSS pieces for the sake of SWS or making sure there 586 * are enough packets in the pipe for fast recovery. 587 * 588 * On the other hand, for extremely large MSS devices, handling 589 * smaller than MSS windows in this way does make sense. 590 */ 591 if (tp->max_window > TCP_MSS_DEFAULT) 592 cutoff = (tp->max_window >> 1); 593 else 594 cutoff = tp->max_window; 595 596 if (cutoff && pktsize > cutoff) 597 return max_t(int, cutoff, 68U - tp->tcp_header_len); 598 else 599 return pktsize; 600 } 601 602 /* tcp.c */ 603 void tcp_get_info(struct sock *, struct tcp_info *); 604 605 /* Read 'sendfile()'-style from a TCP socket */ 606 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 607 sk_read_actor_t recv_actor); 608 609 void tcp_initialize_rcv_mss(struct sock *sk); 610 611 int tcp_mtu_to_mss(struct sock *sk, int pmtu); 612 int tcp_mss_to_mtu(struct sock *sk, int mss); 613 void tcp_mtup_init(struct sock *sk); 614 void tcp_init_buffer_space(struct sock *sk); 615 616 static inline void tcp_bound_rto(const struct sock *sk) 617 { 618 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 619 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 620 } 621 622 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 623 { 624 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us); 625 } 626 627 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 628 { 629 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 630 ntohl(TCP_FLAG_ACK) | 631 snd_wnd); 632 } 633 634 static inline void tcp_fast_path_on(struct tcp_sock *tp) 635 { 636 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 637 } 638 639 static inline void tcp_fast_path_check(struct sock *sk) 640 { 641 struct tcp_sock *tp = tcp_sk(sk); 642 643 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) && 644 tp->rcv_wnd && 645 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 646 !tp->urg_data) 647 tcp_fast_path_on(tp); 648 } 649 650 /* Compute the actual rto_min value */ 651 static inline u32 tcp_rto_min(struct sock *sk) 652 { 653 const struct dst_entry *dst = __sk_dst_get(sk); 654 u32 rto_min = TCP_RTO_MIN; 655 656 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 657 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 658 return rto_min; 659 } 660 661 static inline u32 tcp_rto_min_us(struct sock *sk) 662 { 663 return jiffies_to_usecs(tcp_rto_min(sk)); 664 } 665 666 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst) 667 { 668 return dst_metric_locked(dst, RTAX_CC_ALGO); 669 } 670 671 /* Minimum RTT in usec. ~0 means not available. */ 672 static inline u32 tcp_min_rtt(const struct tcp_sock *tp) 673 { 674 return tp->rtt_min[0].rtt; 675 } 676 677 /* Compute the actual receive window we are currently advertising. 678 * Rcv_nxt can be after the window if our peer push more data 679 * than the offered window. 680 */ 681 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 682 { 683 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 684 685 if (win < 0) 686 win = 0; 687 return (u32) win; 688 } 689 690 /* Choose a new window, without checks for shrinking, and without 691 * scaling applied to the result. The caller does these things 692 * if necessary. This is a "raw" window selection. 693 */ 694 u32 __tcp_select_window(struct sock *sk); 695 696 void tcp_send_window_probe(struct sock *sk); 697 698 /* TCP timestamps are only 32-bits, this causes a slight 699 * complication on 64-bit systems since we store a snapshot 700 * of jiffies in the buffer control blocks below. We decided 701 * to use only the low 32-bits of jiffies and hide the ugly 702 * casts with the following macro. 703 */ 704 #define tcp_time_stamp ((__u32)(jiffies)) 705 706 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) 707 { 708 return skb->skb_mstamp.stamp_jiffies; 709 } 710 711 712 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 713 714 #define TCPHDR_FIN 0x01 715 #define TCPHDR_SYN 0x02 716 #define TCPHDR_RST 0x04 717 #define TCPHDR_PSH 0x08 718 #define TCPHDR_ACK 0x10 719 #define TCPHDR_URG 0x20 720 #define TCPHDR_ECE 0x40 721 #define TCPHDR_CWR 0x80 722 723 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) 724 725 /* This is what the send packet queuing engine uses to pass 726 * TCP per-packet control information to the transmission code. 727 * We also store the host-order sequence numbers in here too. 728 * This is 44 bytes if IPV6 is enabled. 729 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 730 */ 731 struct tcp_skb_cb { 732 __u32 seq; /* Starting sequence number */ 733 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 734 union { 735 /* Note : tcp_tw_isn is used in input path only 736 * (isn chosen by tcp_timewait_state_process()) 737 * 738 * tcp_gso_segs/size are used in write queue only, 739 * cf tcp_skb_pcount()/tcp_skb_mss() 740 */ 741 __u32 tcp_tw_isn; 742 struct { 743 u16 tcp_gso_segs; 744 u16 tcp_gso_size; 745 }; 746 }; 747 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 748 749 __u8 sacked; /* State flags for SACK/FACK. */ 750 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 751 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 752 #define TCPCB_LOST 0x04 /* SKB is lost */ 753 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 754 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */ 755 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 756 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \ 757 TCPCB_REPAIRED) 758 759 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 760 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */ 761 eor:1, /* Is skb MSG_EOR marked? */ 762 unused:6; 763 __u32 ack_seq; /* Sequence number ACK'd */ 764 union { 765 struct { 766 /* There is space for up to 20 bytes */ 767 __u32 in_flight;/* Bytes in flight when packet sent */ 768 } tx; /* only used for outgoing skbs */ 769 union { 770 struct inet_skb_parm h4; 771 #if IS_ENABLED(CONFIG_IPV6) 772 struct inet6_skb_parm h6; 773 #endif 774 } header; /* For incoming skbs */ 775 }; 776 }; 777 778 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 779 780 781 #if IS_ENABLED(CONFIG_IPV6) 782 /* This is the variant of inet6_iif() that must be used by TCP, 783 * as TCP moves IP6CB into a different location in skb->cb[] 784 */ 785 static inline int tcp_v6_iif(const struct sk_buff *skb) 786 { 787 bool l3_slave = skb_l3mdev_slave(TCP_SKB_CB(skb)->header.h6.flags); 788 789 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif; 790 } 791 #endif 792 793 /* Due to TSO, an SKB can be composed of multiple actual 794 * packets. To keep these tracked properly, we use this. 795 */ 796 static inline int tcp_skb_pcount(const struct sk_buff *skb) 797 { 798 return TCP_SKB_CB(skb)->tcp_gso_segs; 799 } 800 801 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 802 { 803 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 804 } 805 806 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 807 { 808 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 809 } 810 811 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ 812 static inline int tcp_skb_mss(const struct sk_buff *skb) 813 { 814 return TCP_SKB_CB(skb)->tcp_gso_size; 815 } 816 817 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb) 818 { 819 return likely(!TCP_SKB_CB(skb)->eor); 820 } 821 822 /* Events passed to congestion control interface */ 823 enum tcp_ca_event { 824 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 825 CA_EVENT_CWND_RESTART, /* congestion window restart */ 826 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 827 CA_EVENT_LOSS, /* loss timeout */ 828 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 829 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 830 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */ 831 CA_EVENT_NON_DELAYED_ACK, 832 }; 833 834 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 835 enum tcp_ca_ack_event_flags { 836 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 837 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 838 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 839 }; 840 841 /* 842 * Interface for adding new TCP congestion control handlers 843 */ 844 #define TCP_CA_NAME_MAX 16 845 #define TCP_CA_MAX 128 846 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 847 848 #define TCP_CA_UNSPEC 0 849 850 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 851 #define TCP_CONG_NON_RESTRICTED 0x1 852 /* Requires ECN/ECT set on all packets */ 853 #define TCP_CONG_NEEDS_ECN 0x2 854 855 union tcp_cc_info; 856 857 struct ack_sample { 858 u32 pkts_acked; 859 s32 rtt_us; 860 u32 in_flight; 861 }; 862 863 struct tcp_congestion_ops { 864 struct list_head list; 865 u32 key; 866 u32 flags; 867 868 /* initialize private data (optional) */ 869 void (*init)(struct sock *sk); 870 /* cleanup private data (optional) */ 871 void (*release)(struct sock *sk); 872 873 /* return slow start threshold (required) */ 874 u32 (*ssthresh)(struct sock *sk); 875 /* do new cwnd calculation (required) */ 876 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 877 /* call before changing ca_state (optional) */ 878 void (*set_state)(struct sock *sk, u8 new_state); 879 /* call when cwnd event occurs (optional) */ 880 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 881 /* call when ack arrives (optional) */ 882 void (*in_ack_event)(struct sock *sk, u32 flags); 883 /* new value of cwnd after loss (optional) */ 884 u32 (*undo_cwnd)(struct sock *sk); 885 /* hook for packet ack accounting (optional) */ 886 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample); 887 /* get info for inet_diag (optional) */ 888 size_t (*get_info)(struct sock *sk, u32 ext, int *attr, 889 union tcp_cc_info *info); 890 891 char name[TCP_CA_NAME_MAX]; 892 struct module *owner; 893 }; 894 895 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 896 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 897 898 void tcp_assign_congestion_control(struct sock *sk); 899 void tcp_init_congestion_control(struct sock *sk); 900 void tcp_cleanup_congestion_control(struct sock *sk); 901 int tcp_set_default_congestion_control(const char *name); 902 void tcp_get_default_congestion_control(char *name); 903 void tcp_get_available_congestion_control(char *buf, size_t len); 904 void tcp_get_allowed_congestion_control(char *buf, size_t len); 905 int tcp_set_allowed_congestion_control(char *allowed); 906 int tcp_set_congestion_control(struct sock *sk, const char *name); 907 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); 908 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); 909 910 u32 tcp_reno_ssthresh(struct sock *sk); 911 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 912 extern struct tcp_congestion_ops tcp_reno; 913 914 struct tcp_congestion_ops *tcp_ca_find_key(u32 key); 915 u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca); 916 #ifdef CONFIG_INET 917 char *tcp_ca_get_name_by_key(u32 key, char *buffer); 918 #else 919 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) 920 { 921 return NULL; 922 } 923 #endif 924 925 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 926 { 927 const struct inet_connection_sock *icsk = inet_csk(sk); 928 929 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 930 } 931 932 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 933 { 934 struct inet_connection_sock *icsk = inet_csk(sk); 935 936 if (icsk->icsk_ca_ops->set_state) 937 icsk->icsk_ca_ops->set_state(sk, ca_state); 938 icsk->icsk_ca_state = ca_state; 939 } 940 941 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 942 { 943 const struct inet_connection_sock *icsk = inet_csk(sk); 944 945 if (icsk->icsk_ca_ops->cwnd_event) 946 icsk->icsk_ca_ops->cwnd_event(sk, event); 947 } 948 949 /* These functions determine how the current flow behaves in respect of SACK 950 * handling. SACK is negotiated with the peer, and therefore it can vary 951 * between different flows. 952 * 953 * tcp_is_sack - SACK enabled 954 * tcp_is_reno - No SACK 955 * tcp_is_fack - FACK enabled, implies SACK enabled 956 */ 957 static inline int tcp_is_sack(const struct tcp_sock *tp) 958 { 959 return tp->rx_opt.sack_ok; 960 } 961 962 static inline bool tcp_is_reno(const struct tcp_sock *tp) 963 { 964 return !tcp_is_sack(tp); 965 } 966 967 static inline bool tcp_is_fack(const struct tcp_sock *tp) 968 { 969 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED; 970 } 971 972 static inline void tcp_enable_fack(struct tcp_sock *tp) 973 { 974 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED; 975 } 976 977 /* TCP early-retransmit (ER) is similar to but more conservative than 978 * the thin-dupack feature. Enable ER only if thin-dupack is disabled. 979 */ 980 static inline void tcp_enable_early_retrans(struct tcp_sock *tp) 981 { 982 struct net *net = sock_net((struct sock *)tp); 983 984 tp->do_early_retrans = sysctl_tcp_early_retrans && 985 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack && 986 net->ipv4.sysctl_tcp_reordering == 3; 987 } 988 989 static inline void tcp_disable_early_retrans(struct tcp_sock *tp) 990 { 991 tp->do_early_retrans = 0; 992 } 993 994 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 995 { 996 return tp->sacked_out + tp->lost_out; 997 } 998 999 /* This determines how many packets are "in the network" to the best 1000 * of our knowledge. In many cases it is conservative, but where 1001 * detailed information is available from the receiver (via SACK 1002 * blocks etc.) we can make more aggressive calculations. 1003 * 1004 * Use this for decisions involving congestion control, use just 1005 * tp->packets_out to determine if the send queue is empty or not. 1006 * 1007 * Read this equation as: 1008 * 1009 * "Packets sent once on transmission queue" MINUS 1010 * "Packets left network, but not honestly ACKed yet" PLUS 1011 * "Packets fast retransmitted" 1012 */ 1013 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 1014 { 1015 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 1016 } 1017 1018 #define TCP_INFINITE_SSTHRESH 0x7fffffff 1019 1020 static inline bool tcp_in_slow_start(const struct tcp_sock *tp) 1021 { 1022 return tp->snd_cwnd < tp->snd_ssthresh; 1023 } 1024 1025 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 1026 { 1027 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 1028 } 1029 1030 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 1031 { 1032 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 1033 (1 << inet_csk(sk)->icsk_ca_state); 1034 } 1035 1036 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 1037 * The exception is cwnd reduction phase, when cwnd is decreasing towards 1038 * ssthresh. 1039 */ 1040 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 1041 { 1042 const struct tcp_sock *tp = tcp_sk(sk); 1043 1044 if (tcp_in_cwnd_reduction(sk)) 1045 return tp->snd_ssthresh; 1046 else 1047 return max(tp->snd_ssthresh, 1048 ((tp->snd_cwnd >> 1) + 1049 (tp->snd_cwnd >> 2))); 1050 } 1051 1052 /* Use define here intentionally to get WARN_ON location shown at the caller */ 1053 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 1054 1055 void tcp_enter_cwr(struct sock *sk); 1056 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 1057 1058 /* The maximum number of MSS of available cwnd for which TSO defers 1059 * sending if not using sysctl_tcp_tso_win_divisor. 1060 */ 1061 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 1062 { 1063 return 3; 1064 } 1065 1066 /* Returns end sequence number of the receiver's advertised window */ 1067 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 1068 { 1069 return tp->snd_una + tp->snd_wnd; 1070 } 1071 1072 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 1073 * flexible approach. The RFC suggests cwnd should not be raised unless 1074 * it was fully used previously. And that's exactly what we do in 1075 * congestion avoidance mode. But in slow start we allow cwnd to grow 1076 * as long as the application has used half the cwnd. 1077 * Example : 1078 * cwnd is 10 (IW10), but application sends 9 frames. 1079 * We allow cwnd to reach 18 when all frames are ACKed. 1080 * This check is safe because it's as aggressive as slow start which already 1081 * risks 100% overshoot. The advantage is that we discourage application to 1082 * either send more filler packets or data to artificially blow up the cwnd 1083 * usage, and allow application-limited process to probe bw more aggressively. 1084 */ 1085 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1086 { 1087 const struct tcp_sock *tp = tcp_sk(sk); 1088 1089 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1090 if (tcp_in_slow_start(tp)) 1091 return tp->snd_cwnd < 2 * tp->max_packets_out; 1092 1093 return tp->is_cwnd_limited; 1094 } 1095 1096 /* Something is really bad, we could not queue an additional packet, 1097 * because qdisc is full or receiver sent a 0 window. 1098 * We do not want to add fuel to the fire, or abort too early, 1099 * so make sure the timer we arm now is at least 200ms in the future, 1100 * regardless of current icsk_rto value (as it could be ~2ms) 1101 */ 1102 static inline unsigned long tcp_probe0_base(const struct sock *sk) 1103 { 1104 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); 1105 } 1106 1107 /* Variant of inet_csk_rto_backoff() used for zero window probes */ 1108 static inline unsigned long tcp_probe0_when(const struct sock *sk, 1109 unsigned long max_when) 1110 { 1111 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff; 1112 1113 return (unsigned long)min_t(u64, when, max_when); 1114 } 1115 1116 static inline void tcp_check_probe_timer(struct sock *sk) 1117 { 1118 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) 1119 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1120 tcp_probe0_base(sk), TCP_RTO_MAX); 1121 } 1122 1123 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1124 { 1125 tp->snd_wl1 = seq; 1126 } 1127 1128 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1129 { 1130 tp->snd_wl1 = seq; 1131 } 1132 1133 /* 1134 * Calculate(/check) TCP checksum 1135 */ 1136 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1137 __be32 daddr, __wsum base) 1138 { 1139 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1140 } 1141 1142 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1143 { 1144 return __skb_checksum_complete(skb); 1145 } 1146 1147 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1148 { 1149 return !skb_csum_unnecessary(skb) && 1150 __tcp_checksum_complete(skb); 1151 } 1152 1153 /* Prequeue for VJ style copy to user, combined with checksumming. */ 1154 1155 static inline void tcp_prequeue_init(struct tcp_sock *tp) 1156 { 1157 tp->ucopy.task = NULL; 1158 tp->ucopy.len = 0; 1159 tp->ucopy.memory = 0; 1160 skb_queue_head_init(&tp->ucopy.prequeue); 1161 } 1162 1163 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb); 1164 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb); 1165 1166 #undef STATE_TRACE 1167 1168 #ifdef STATE_TRACE 1169 static const char *statename[]={ 1170 "Unused","Established","Syn Sent","Syn Recv", 1171 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1172 "Close Wait","Last ACK","Listen","Closing" 1173 }; 1174 #endif 1175 void tcp_set_state(struct sock *sk, int state); 1176 1177 void tcp_done(struct sock *sk); 1178 1179 int tcp_abort(struct sock *sk, int err); 1180 1181 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1182 { 1183 rx_opt->dsack = 0; 1184 rx_opt->num_sacks = 0; 1185 } 1186 1187 u32 tcp_default_init_rwnd(u32 mss); 1188 void tcp_cwnd_restart(struct sock *sk, s32 delta); 1189 1190 static inline void tcp_slow_start_after_idle_check(struct sock *sk) 1191 { 1192 struct tcp_sock *tp = tcp_sk(sk); 1193 s32 delta; 1194 1195 if (!sysctl_tcp_slow_start_after_idle || tp->packets_out) 1196 return; 1197 delta = tcp_time_stamp - tp->lsndtime; 1198 if (delta > inet_csk(sk)->icsk_rto) 1199 tcp_cwnd_restart(sk, delta); 1200 } 1201 1202 /* Determine a window scaling and initial window to offer. */ 1203 void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd, 1204 __u32 *window_clamp, int wscale_ok, 1205 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1206 1207 static inline int tcp_win_from_space(int space) 1208 { 1209 return sysctl_tcp_adv_win_scale<=0 ? 1210 (space>>(-sysctl_tcp_adv_win_scale)) : 1211 space - (space>>sysctl_tcp_adv_win_scale); 1212 } 1213 1214 /* Note: caller must be prepared to deal with negative returns */ 1215 static inline int tcp_space(const struct sock *sk) 1216 { 1217 return tcp_win_from_space(sk->sk_rcvbuf - 1218 atomic_read(&sk->sk_rmem_alloc)); 1219 } 1220 1221 static inline int tcp_full_space(const struct sock *sk) 1222 { 1223 return tcp_win_from_space(sk->sk_rcvbuf); 1224 } 1225 1226 extern void tcp_openreq_init_rwin(struct request_sock *req, 1227 const struct sock *sk_listener, 1228 const struct dst_entry *dst); 1229 1230 void tcp_enter_memory_pressure(struct sock *sk); 1231 1232 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1233 { 1234 struct net *net = sock_net((struct sock *)tp); 1235 1236 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl; 1237 } 1238 1239 static inline int keepalive_time_when(const struct tcp_sock *tp) 1240 { 1241 struct net *net = sock_net((struct sock *)tp); 1242 1243 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time; 1244 } 1245 1246 static inline int keepalive_probes(const struct tcp_sock *tp) 1247 { 1248 struct net *net = sock_net((struct sock *)tp); 1249 1250 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes; 1251 } 1252 1253 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1254 { 1255 const struct inet_connection_sock *icsk = &tp->inet_conn; 1256 1257 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime, 1258 tcp_time_stamp - tp->rcv_tstamp); 1259 } 1260 1261 static inline int tcp_fin_time(const struct sock *sk) 1262 { 1263 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout; 1264 const int rto = inet_csk(sk)->icsk_rto; 1265 1266 if (fin_timeout < (rto << 2) - (rto >> 1)) 1267 fin_timeout = (rto << 2) - (rto >> 1); 1268 1269 return fin_timeout; 1270 } 1271 1272 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1273 int paws_win) 1274 { 1275 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1276 return true; 1277 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1278 return true; 1279 /* 1280 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1281 * then following tcp messages have valid values. Ignore 0 value, 1282 * or else 'negative' tsval might forbid us to accept their packets. 1283 */ 1284 if (!rx_opt->ts_recent) 1285 return true; 1286 return false; 1287 } 1288 1289 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1290 int rst) 1291 { 1292 if (tcp_paws_check(rx_opt, 0)) 1293 return false; 1294 1295 /* RST segments are not recommended to carry timestamp, 1296 and, if they do, it is recommended to ignore PAWS because 1297 "their cleanup function should take precedence over timestamps." 1298 Certainly, it is mistake. It is necessary to understand the reasons 1299 of this constraint to relax it: if peer reboots, clock may go 1300 out-of-sync and half-open connections will not be reset. 1301 Actually, the problem would be not existing if all 1302 the implementations followed draft about maintaining clock 1303 via reboots. Linux-2.2 DOES NOT! 1304 1305 However, we can relax time bounds for RST segments to MSL. 1306 */ 1307 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1308 return false; 1309 return true; 1310 } 1311 1312 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, 1313 int mib_idx, u32 *last_oow_ack_time); 1314 1315 static inline void tcp_mib_init(struct net *net) 1316 { 1317 /* See RFC 2012 */ 1318 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1); 1319 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1320 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1321 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1); 1322 } 1323 1324 /* from STCP */ 1325 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1326 { 1327 tp->lost_skb_hint = NULL; 1328 } 1329 1330 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1331 { 1332 tcp_clear_retrans_hints_partial(tp); 1333 tp->retransmit_skb_hint = NULL; 1334 } 1335 1336 union tcp_md5_addr { 1337 struct in_addr a4; 1338 #if IS_ENABLED(CONFIG_IPV6) 1339 struct in6_addr a6; 1340 #endif 1341 }; 1342 1343 /* - key database */ 1344 struct tcp_md5sig_key { 1345 struct hlist_node node; 1346 u8 keylen; 1347 u8 family; /* AF_INET or AF_INET6 */ 1348 union tcp_md5_addr addr; 1349 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1350 struct rcu_head rcu; 1351 }; 1352 1353 /* - sock block */ 1354 struct tcp_md5sig_info { 1355 struct hlist_head head; 1356 struct rcu_head rcu; 1357 }; 1358 1359 /* - pseudo header */ 1360 struct tcp4_pseudohdr { 1361 __be32 saddr; 1362 __be32 daddr; 1363 __u8 pad; 1364 __u8 protocol; 1365 __be16 len; 1366 }; 1367 1368 struct tcp6_pseudohdr { 1369 struct in6_addr saddr; 1370 struct in6_addr daddr; 1371 __be32 len; 1372 __be32 protocol; /* including padding */ 1373 }; 1374 1375 union tcp_md5sum_block { 1376 struct tcp4_pseudohdr ip4; 1377 #if IS_ENABLED(CONFIG_IPV6) 1378 struct tcp6_pseudohdr ip6; 1379 #endif 1380 }; 1381 1382 /* - pool: digest algorithm, hash description and scratch buffer */ 1383 struct tcp_md5sig_pool { 1384 struct ahash_request *md5_req; 1385 void *scratch; 1386 }; 1387 1388 /* - functions */ 1389 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1390 const struct sock *sk, const struct sk_buff *skb); 1391 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1392 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp); 1393 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1394 int family); 1395 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 1396 const struct sock *addr_sk); 1397 1398 #ifdef CONFIG_TCP_MD5SIG 1399 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1400 const union tcp_md5_addr *addr, 1401 int family); 1402 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1403 #else 1404 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1405 const union tcp_md5_addr *addr, 1406 int family) 1407 { 1408 return NULL; 1409 } 1410 #define tcp_twsk_md5_key(twsk) NULL 1411 #endif 1412 1413 bool tcp_alloc_md5sig_pool(void); 1414 1415 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1416 static inline void tcp_put_md5sig_pool(void) 1417 { 1418 local_bh_enable(); 1419 } 1420 1421 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1422 unsigned int header_len); 1423 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1424 const struct tcp_md5sig_key *key); 1425 1426 /* From tcp_fastopen.c */ 1427 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1428 struct tcp_fastopen_cookie *cookie, int *syn_loss, 1429 unsigned long *last_syn_loss); 1430 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1431 struct tcp_fastopen_cookie *cookie, bool syn_lost, 1432 u16 try_exp); 1433 struct tcp_fastopen_request { 1434 /* Fast Open cookie. Size 0 means a cookie request */ 1435 struct tcp_fastopen_cookie cookie; 1436 struct msghdr *data; /* data in MSG_FASTOPEN */ 1437 size_t size; 1438 int copied; /* queued in tcp_connect() */ 1439 }; 1440 void tcp_free_fastopen_req(struct tcp_sock *tp); 1441 1442 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; 1443 int tcp_fastopen_reset_cipher(void *key, unsigned int len); 1444 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb); 1445 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1446 struct request_sock *req, 1447 struct tcp_fastopen_cookie *foc, 1448 struct dst_entry *dst); 1449 void tcp_fastopen_init_key_once(bool publish); 1450 #define TCP_FASTOPEN_KEY_LENGTH 16 1451 1452 /* Fastopen key context */ 1453 struct tcp_fastopen_context { 1454 struct crypto_cipher *tfm; 1455 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1456 struct rcu_head rcu; 1457 }; 1458 1459 /* write queue abstraction */ 1460 static inline void tcp_write_queue_purge(struct sock *sk) 1461 { 1462 struct sk_buff *skb; 1463 1464 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) 1465 sk_wmem_free_skb(sk, skb); 1466 sk_mem_reclaim(sk); 1467 tcp_clear_all_retrans_hints(tcp_sk(sk)); 1468 } 1469 1470 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1471 { 1472 return skb_peek(&sk->sk_write_queue); 1473 } 1474 1475 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1476 { 1477 return skb_peek_tail(&sk->sk_write_queue); 1478 } 1479 1480 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk, 1481 const struct sk_buff *skb) 1482 { 1483 return skb_queue_next(&sk->sk_write_queue, skb); 1484 } 1485 1486 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk, 1487 const struct sk_buff *skb) 1488 { 1489 return skb_queue_prev(&sk->sk_write_queue, skb); 1490 } 1491 1492 #define tcp_for_write_queue(skb, sk) \ 1493 skb_queue_walk(&(sk)->sk_write_queue, skb) 1494 1495 #define tcp_for_write_queue_from(skb, sk) \ 1496 skb_queue_walk_from(&(sk)->sk_write_queue, skb) 1497 1498 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1499 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1500 1501 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1502 { 1503 return sk->sk_send_head; 1504 } 1505 1506 static inline bool tcp_skb_is_last(const struct sock *sk, 1507 const struct sk_buff *skb) 1508 { 1509 return skb_queue_is_last(&sk->sk_write_queue, skb); 1510 } 1511 1512 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb) 1513 { 1514 if (tcp_skb_is_last(sk, skb)) 1515 sk->sk_send_head = NULL; 1516 else 1517 sk->sk_send_head = tcp_write_queue_next(sk, skb); 1518 } 1519 1520 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1521 { 1522 if (sk->sk_send_head == skb_unlinked) 1523 sk->sk_send_head = NULL; 1524 if (tcp_sk(sk)->highest_sack == skb_unlinked) 1525 tcp_sk(sk)->highest_sack = NULL; 1526 } 1527 1528 static inline void tcp_init_send_head(struct sock *sk) 1529 { 1530 sk->sk_send_head = NULL; 1531 } 1532 1533 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1534 { 1535 __skb_queue_tail(&sk->sk_write_queue, skb); 1536 } 1537 1538 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1539 { 1540 __tcp_add_write_queue_tail(sk, skb); 1541 1542 /* Queue it, remembering where we must start sending. */ 1543 if (sk->sk_send_head == NULL) { 1544 sk->sk_send_head = skb; 1545 1546 if (tcp_sk(sk)->highest_sack == NULL) 1547 tcp_sk(sk)->highest_sack = skb; 1548 } 1549 } 1550 1551 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb) 1552 { 1553 __skb_queue_head(&sk->sk_write_queue, skb); 1554 } 1555 1556 /* Insert buff after skb on the write queue of sk. */ 1557 static inline void tcp_insert_write_queue_after(struct sk_buff *skb, 1558 struct sk_buff *buff, 1559 struct sock *sk) 1560 { 1561 __skb_queue_after(&sk->sk_write_queue, skb, buff); 1562 } 1563 1564 /* Insert new before skb on the write queue of sk. */ 1565 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1566 struct sk_buff *skb, 1567 struct sock *sk) 1568 { 1569 __skb_queue_before(&sk->sk_write_queue, skb, new); 1570 1571 if (sk->sk_send_head == skb) 1572 sk->sk_send_head = new; 1573 } 1574 1575 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1576 { 1577 __skb_unlink(skb, &sk->sk_write_queue); 1578 } 1579 1580 static inline bool tcp_write_queue_empty(struct sock *sk) 1581 { 1582 return skb_queue_empty(&sk->sk_write_queue); 1583 } 1584 1585 static inline void tcp_push_pending_frames(struct sock *sk) 1586 { 1587 if (tcp_send_head(sk)) { 1588 struct tcp_sock *tp = tcp_sk(sk); 1589 1590 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1591 } 1592 } 1593 1594 /* Start sequence of the skb just after the highest skb with SACKed 1595 * bit, valid only if sacked_out > 0 or when the caller has ensured 1596 * validity by itself. 1597 */ 1598 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1599 { 1600 if (!tp->sacked_out) 1601 return tp->snd_una; 1602 1603 if (tp->highest_sack == NULL) 1604 return tp->snd_nxt; 1605 1606 return TCP_SKB_CB(tp->highest_sack)->seq; 1607 } 1608 1609 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1610 { 1611 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL : 1612 tcp_write_queue_next(sk, skb); 1613 } 1614 1615 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1616 { 1617 return tcp_sk(sk)->highest_sack; 1618 } 1619 1620 static inline void tcp_highest_sack_reset(struct sock *sk) 1621 { 1622 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk); 1623 } 1624 1625 /* Called when old skb is about to be deleted (to be combined with new skb) */ 1626 static inline void tcp_highest_sack_combine(struct sock *sk, 1627 struct sk_buff *old, 1628 struct sk_buff *new) 1629 { 1630 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack)) 1631 tcp_sk(sk)->highest_sack = new; 1632 } 1633 1634 /* This helper checks if socket has IP_TRANSPARENT set */ 1635 static inline bool inet_sk_transparent(const struct sock *sk) 1636 { 1637 switch (sk->sk_state) { 1638 case TCP_TIME_WAIT: 1639 return inet_twsk(sk)->tw_transparent; 1640 case TCP_NEW_SYN_RECV: 1641 return inet_rsk(inet_reqsk(sk))->no_srccheck; 1642 } 1643 return inet_sk(sk)->transparent; 1644 } 1645 1646 /* Determines whether this is a thin stream (which may suffer from 1647 * increased latency). Used to trigger latency-reducing mechanisms. 1648 */ 1649 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1650 { 1651 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1652 } 1653 1654 /* /proc */ 1655 enum tcp_seq_states { 1656 TCP_SEQ_STATE_LISTENING, 1657 TCP_SEQ_STATE_ESTABLISHED, 1658 }; 1659 1660 int tcp_seq_open(struct inode *inode, struct file *file); 1661 1662 struct tcp_seq_afinfo { 1663 char *name; 1664 sa_family_t family; 1665 const struct file_operations *seq_fops; 1666 struct seq_operations seq_ops; 1667 }; 1668 1669 struct tcp_iter_state { 1670 struct seq_net_private p; 1671 sa_family_t family; 1672 enum tcp_seq_states state; 1673 struct sock *syn_wait_sk; 1674 int bucket, offset, sbucket, num; 1675 loff_t last_pos; 1676 }; 1677 1678 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1679 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1680 1681 extern struct request_sock_ops tcp_request_sock_ops; 1682 extern struct request_sock_ops tcp6_request_sock_ops; 1683 1684 void tcp_v4_destroy_sock(struct sock *sk); 1685 1686 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 1687 netdev_features_t features); 1688 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb); 1689 int tcp_gro_complete(struct sk_buff *skb); 1690 1691 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 1692 1693 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 1694 { 1695 struct net *net = sock_net((struct sock *)tp); 1696 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat; 1697 } 1698 1699 static inline bool tcp_stream_memory_free(const struct sock *sk) 1700 { 1701 const struct tcp_sock *tp = tcp_sk(sk); 1702 u32 notsent_bytes = tp->write_seq - tp->snd_nxt; 1703 1704 return notsent_bytes < tcp_notsent_lowat(tp); 1705 } 1706 1707 #ifdef CONFIG_PROC_FS 1708 int tcp4_proc_init(void); 1709 void tcp4_proc_exit(void); 1710 #endif 1711 1712 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req); 1713 int tcp_conn_request(struct request_sock_ops *rsk_ops, 1714 const struct tcp_request_sock_ops *af_ops, 1715 struct sock *sk, struct sk_buff *skb); 1716 1717 /* TCP af-specific functions */ 1718 struct tcp_sock_af_ops { 1719 #ifdef CONFIG_TCP_MD5SIG 1720 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk, 1721 const struct sock *addr_sk); 1722 int (*calc_md5_hash)(char *location, 1723 const struct tcp_md5sig_key *md5, 1724 const struct sock *sk, 1725 const struct sk_buff *skb); 1726 int (*md5_parse)(struct sock *sk, 1727 char __user *optval, 1728 int optlen); 1729 #endif 1730 }; 1731 1732 struct tcp_request_sock_ops { 1733 u16 mss_clamp; 1734 #ifdef CONFIG_TCP_MD5SIG 1735 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk, 1736 const struct sock *addr_sk); 1737 int (*calc_md5_hash) (char *location, 1738 const struct tcp_md5sig_key *md5, 1739 const struct sock *sk, 1740 const struct sk_buff *skb); 1741 #endif 1742 void (*init_req)(struct request_sock *req, 1743 const struct sock *sk_listener, 1744 struct sk_buff *skb); 1745 #ifdef CONFIG_SYN_COOKIES 1746 __u32 (*cookie_init_seq)(const struct sk_buff *skb, 1747 __u16 *mss); 1748 #endif 1749 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl, 1750 const struct request_sock *req, 1751 bool *strict); 1752 __u32 (*init_seq)(const struct sk_buff *skb); 1753 int (*send_synack)(const struct sock *sk, struct dst_entry *dst, 1754 struct flowi *fl, struct request_sock *req, 1755 struct tcp_fastopen_cookie *foc, 1756 enum tcp_synack_type synack_type); 1757 }; 1758 1759 #ifdef CONFIG_SYN_COOKIES 1760 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1761 const struct sock *sk, struct sk_buff *skb, 1762 __u16 *mss) 1763 { 1764 tcp_synq_overflow(sk); 1765 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); 1766 return ops->cookie_init_seq(skb, mss); 1767 } 1768 #else 1769 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1770 const struct sock *sk, struct sk_buff *skb, 1771 __u16 *mss) 1772 { 1773 return 0; 1774 } 1775 #endif 1776 1777 int tcpv4_offload_init(void); 1778 1779 void tcp_v4_init(void); 1780 void tcp_init(void); 1781 1782 /* tcp_recovery.c */ 1783 1784 /* Flags to enable various loss recovery features. See below */ 1785 extern int sysctl_tcp_recovery; 1786 1787 /* Use TCP RACK to detect (some) tail and retransmit losses */ 1788 #define TCP_RACK_LOST_RETRANS 0x1 1789 1790 extern int tcp_rack_mark_lost(struct sock *sk); 1791 1792 extern void tcp_rack_advance(struct tcp_sock *tp, 1793 const struct skb_mstamp *xmit_time, u8 sacked); 1794 1795 /* 1796 * Save and compile IPv4 options, return a pointer to it 1797 */ 1798 static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb) 1799 { 1800 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; 1801 struct ip_options_rcu *dopt = NULL; 1802 1803 if (opt->optlen) { 1804 int opt_size = sizeof(*dopt) + opt->optlen; 1805 1806 dopt = kmalloc(opt_size, GFP_ATOMIC); 1807 if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) { 1808 kfree(dopt); 1809 dopt = NULL; 1810 } 1811 } 1812 return dopt; 1813 } 1814 1815 /* locally generated TCP pure ACKs have skb->truesize == 2 1816 * (check tcp_send_ack() in net/ipv4/tcp_output.c ) 1817 * This is much faster than dissecting the packet to find out. 1818 * (Think of GRE encapsulations, IPv4, IPv6, ...) 1819 */ 1820 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb) 1821 { 1822 return skb->truesize == 2; 1823 } 1824 1825 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb) 1826 { 1827 skb->truesize = 2; 1828 } 1829 1830 static inline int tcp_inq(struct sock *sk) 1831 { 1832 struct tcp_sock *tp = tcp_sk(sk); 1833 int answ; 1834 1835 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { 1836 answ = 0; 1837 } else if (sock_flag(sk, SOCK_URGINLINE) || 1838 !tp->urg_data || 1839 before(tp->urg_seq, tp->copied_seq) || 1840 !before(tp->urg_seq, tp->rcv_nxt)) { 1841 1842 answ = tp->rcv_nxt - tp->copied_seq; 1843 1844 /* Subtract 1, if FIN was received */ 1845 if (answ && sock_flag(sk, SOCK_DONE)) 1846 answ--; 1847 } else { 1848 answ = tp->urg_seq - tp->copied_seq; 1849 } 1850 1851 return answ; 1852 } 1853 1854 int tcp_peek_len(struct socket *sock); 1855 1856 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb) 1857 { 1858 u16 segs_in; 1859 1860 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs); 1861 tp->segs_in += segs_in; 1862 if (skb->len > tcp_hdrlen(skb)) 1863 tp->data_segs_in += segs_in; 1864 } 1865 1866 /* 1867 * TCP listen path runs lockless. 1868 * We forced "struct sock" to be const qualified to make sure 1869 * we don't modify one of its field by mistake. 1870 * Here, we increment sk_drops which is an atomic_t, so we can safely 1871 * make sock writable again. 1872 */ 1873 static inline void tcp_listendrop(const struct sock *sk) 1874 { 1875 atomic_inc(&((struct sock *)sk)->sk_drops); 1876 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 1877 } 1878 1879 #endif /* _TCP_H */ 1880