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. SOCKOPT1/2 determine how to set max_qlen. 231 */ 232 #define TFO_SERVER_WO_SOCKOPT1 0x400 233 #define TFO_SERVER_WO_SOCKOPT2 0x800 234 235 extern struct inet_timewait_death_row tcp_death_row; 236 237 /* sysctl variables for tcp */ 238 extern int sysctl_tcp_timestamps; 239 extern int sysctl_tcp_window_scaling; 240 extern int sysctl_tcp_sack; 241 extern int sysctl_tcp_fastopen; 242 extern int sysctl_tcp_retrans_collapse; 243 extern int sysctl_tcp_stdurg; 244 extern int sysctl_tcp_rfc1337; 245 extern int sysctl_tcp_abort_on_overflow; 246 extern int sysctl_tcp_max_orphans; 247 extern int sysctl_tcp_fack; 248 extern int sysctl_tcp_reordering; 249 extern int sysctl_tcp_max_reordering; 250 extern int sysctl_tcp_dsack; 251 extern long sysctl_tcp_mem[3]; 252 extern int sysctl_tcp_wmem[3]; 253 extern int sysctl_tcp_rmem[3]; 254 extern int sysctl_tcp_app_win; 255 extern int sysctl_tcp_adv_win_scale; 256 extern int sysctl_tcp_tw_reuse; 257 extern int sysctl_tcp_frto; 258 extern int sysctl_tcp_low_latency; 259 extern int sysctl_tcp_nometrics_save; 260 extern int sysctl_tcp_moderate_rcvbuf; 261 extern int sysctl_tcp_tso_win_divisor; 262 extern int sysctl_tcp_workaround_signed_windows; 263 extern int sysctl_tcp_slow_start_after_idle; 264 extern int sysctl_tcp_thin_linear_timeouts; 265 extern int sysctl_tcp_thin_dupack; 266 extern int sysctl_tcp_early_retrans; 267 extern int sysctl_tcp_limit_output_bytes; 268 extern int sysctl_tcp_challenge_ack_limit; 269 extern int sysctl_tcp_min_tso_segs; 270 extern int sysctl_tcp_min_rtt_wlen; 271 extern int sysctl_tcp_autocorking; 272 extern int sysctl_tcp_invalid_ratelimit; 273 extern int sysctl_tcp_pacing_ss_ratio; 274 extern int sysctl_tcp_pacing_ca_ratio; 275 276 extern atomic_long_t tcp_memory_allocated; 277 extern struct percpu_counter tcp_sockets_allocated; 278 extern int tcp_memory_pressure; 279 280 /* optimized version of sk_under_memory_pressure() for TCP sockets */ 281 static inline bool tcp_under_memory_pressure(const struct sock *sk) 282 { 283 if (mem_cgroup_sockets_enabled && sk->sk_memcg && 284 mem_cgroup_under_socket_pressure(sk->sk_memcg)) 285 return true; 286 287 return tcp_memory_pressure; 288 } 289 /* 290 * The next routines deal with comparing 32 bit unsigned ints 291 * and worry about wraparound (automatic with unsigned arithmetic). 292 */ 293 294 static inline bool before(__u32 seq1, __u32 seq2) 295 { 296 return (__s32)(seq1-seq2) < 0; 297 } 298 #define after(seq2, seq1) before(seq1, seq2) 299 300 /* is s2<=s1<=s3 ? */ 301 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) 302 { 303 return seq3 - seq2 >= seq1 - seq2; 304 } 305 306 static inline bool tcp_out_of_memory(struct sock *sk) 307 { 308 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 309 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2)) 310 return true; 311 return false; 312 } 313 314 void sk_forced_mem_schedule(struct sock *sk, int size); 315 316 static inline bool tcp_too_many_orphans(struct sock *sk, int shift) 317 { 318 struct percpu_counter *ocp = sk->sk_prot->orphan_count; 319 int orphans = percpu_counter_read_positive(ocp); 320 321 if (orphans << shift > sysctl_tcp_max_orphans) { 322 orphans = percpu_counter_sum_positive(ocp); 323 if (orphans << shift > sysctl_tcp_max_orphans) 324 return true; 325 } 326 return false; 327 } 328 329 bool tcp_check_oom(struct sock *sk, int shift); 330 331 332 extern struct proto tcp_prot; 333 334 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 335 #define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field) 336 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 337 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 338 339 void tcp_tasklet_init(void); 340 341 void tcp_v4_err(struct sk_buff *skb, u32); 342 343 void tcp_shutdown(struct sock *sk, int how); 344 345 void tcp_v4_early_demux(struct sk_buff *skb); 346 int tcp_v4_rcv(struct sk_buff *skb); 347 348 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 349 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size); 350 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, 351 int flags); 352 void tcp_release_cb(struct sock *sk); 353 void tcp_wfree(struct sk_buff *skb); 354 void tcp_write_timer_handler(struct sock *sk); 355 void tcp_delack_timer_handler(struct sock *sk); 356 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 357 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb); 358 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 359 const struct tcphdr *th, unsigned int len); 360 void tcp_rcv_space_adjust(struct sock *sk); 361 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 362 void tcp_twsk_destructor(struct sock *sk); 363 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 364 struct pipe_inode_info *pipe, size_t len, 365 unsigned int flags); 366 367 static inline void tcp_dec_quickack_mode(struct sock *sk, 368 const unsigned int pkts) 369 { 370 struct inet_connection_sock *icsk = inet_csk(sk); 371 372 if (icsk->icsk_ack.quick) { 373 if (pkts >= icsk->icsk_ack.quick) { 374 icsk->icsk_ack.quick = 0; 375 /* Leaving quickack mode we deflate ATO. */ 376 icsk->icsk_ack.ato = TCP_ATO_MIN; 377 } else 378 icsk->icsk_ack.quick -= pkts; 379 } 380 } 381 382 #define TCP_ECN_OK 1 383 #define TCP_ECN_QUEUE_CWR 2 384 #define TCP_ECN_DEMAND_CWR 4 385 #define TCP_ECN_SEEN 8 386 387 enum tcp_tw_status { 388 TCP_TW_SUCCESS = 0, 389 TCP_TW_RST = 1, 390 TCP_TW_ACK = 2, 391 TCP_TW_SYN = 3 392 }; 393 394 395 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 396 struct sk_buff *skb, 397 const struct tcphdr *th); 398 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 399 struct request_sock *req, bool fastopen); 400 int tcp_child_process(struct sock *parent, struct sock *child, 401 struct sk_buff *skb); 402 void tcp_enter_loss(struct sock *sk); 403 void tcp_clear_retrans(struct tcp_sock *tp); 404 void tcp_update_metrics(struct sock *sk); 405 void tcp_init_metrics(struct sock *sk); 406 void tcp_metrics_init(void); 407 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, 408 bool paws_check, bool timestamps); 409 bool tcp_remember_stamp(struct sock *sk); 410 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw); 411 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst); 412 void tcp_disable_fack(struct tcp_sock *tp); 413 void tcp_close(struct sock *sk, long timeout); 414 void tcp_init_sock(struct sock *sk); 415 unsigned int tcp_poll(struct file *file, struct socket *sock, 416 struct poll_table_struct *wait); 417 int tcp_getsockopt(struct sock *sk, int level, int optname, 418 char __user *optval, int __user *optlen); 419 int tcp_setsockopt(struct sock *sk, int level, int optname, 420 char __user *optval, unsigned int optlen); 421 int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 422 char __user *optval, int __user *optlen); 423 int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 424 char __user *optval, unsigned int optlen); 425 void tcp_set_keepalive(struct sock *sk, int val); 426 void tcp_syn_ack_timeout(const struct request_sock *req); 427 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, 428 int flags, int *addr_len); 429 void tcp_parse_options(const struct sk_buff *skb, 430 struct tcp_options_received *opt_rx, 431 int estab, struct tcp_fastopen_cookie *foc); 432 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); 433 434 /* 435 * TCP v4 functions exported for the inet6 API 436 */ 437 438 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 439 void tcp_v4_mtu_reduced(struct sock *sk); 440 void tcp_req_err(struct sock *sk, u32 seq, bool abort); 441 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 442 struct sock *tcp_create_openreq_child(const struct sock *sk, 443 struct request_sock *req, 444 struct sk_buff *skb); 445 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst); 446 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 447 struct request_sock *req, 448 struct dst_entry *dst, 449 struct request_sock *req_unhash, 450 bool *own_req); 451 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 452 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); 453 int tcp_connect(struct sock *sk); 454 enum tcp_synack_type { 455 TCP_SYNACK_NORMAL, 456 TCP_SYNACK_FASTOPEN, 457 TCP_SYNACK_COOKIE, 458 }; 459 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 460 struct request_sock *req, 461 struct tcp_fastopen_cookie *foc, 462 enum tcp_synack_type synack_type); 463 int tcp_disconnect(struct sock *sk, int flags); 464 465 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 466 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 467 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); 468 469 /* From syncookies.c */ 470 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, 471 struct request_sock *req, 472 struct dst_entry *dst); 473 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th, 474 u32 cookie); 475 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb); 476 #ifdef CONFIG_SYN_COOKIES 477 478 /* Syncookies use a monotonic timer which increments every 60 seconds. 479 * This counter is used both as a hash input and partially encoded into 480 * the cookie value. A cookie is only validated further if the delta 481 * between the current counter value and the encoded one is less than this, 482 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if 483 * the counter advances immediately after a cookie is generated). 484 */ 485 #define MAX_SYNCOOKIE_AGE 2 486 #define TCP_SYNCOOKIE_PERIOD (60 * HZ) 487 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD) 488 489 /* syncookies: remember time of last synqueue overflow 490 * But do not dirty this field too often (once per second is enough) 491 * It is racy as we do not hold a lock, but race is very minor. 492 */ 493 static inline void tcp_synq_overflow(const struct sock *sk) 494 { 495 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 496 unsigned long now = jiffies; 497 498 if (time_after(now, last_overflow + HZ)) 499 tcp_sk(sk)->rx_opt.ts_recent_stamp = now; 500 } 501 502 /* syncookies: no recent synqueue overflow on this listening socket? */ 503 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 504 { 505 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 506 507 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID); 508 } 509 510 static inline u32 tcp_cookie_time(void) 511 { 512 u64 val = get_jiffies_64(); 513 514 do_div(val, TCP_SYNCOOKIE_PERIOD); 515 return val; 516 } 517 518 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, 519 u16 *mssp); 520 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss); 521 __u32 cookie_init_timestamp(struct request_sock *req); 522 bool cookie_timestamp_decode(struct tcp_options_received *opt); 523 bool cookie_ecn_ok(const struct tcp_options_received *opt, 524 const struct net *net, const struct dst_entry *dst); 525 526 /* From net/ipv6/syncookies.c */ 527 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th, 528 u32 cookie); 529 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 530 531 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph, 532 const struct tcphdr *th, u16 *mssp); 533 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss); 534 #endif 535 /* tcp_output.c */ 536 537 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 538 int nonagle); 539 bool tcp_may_send_now(struct sock *sk); 540 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 541 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 542 void tcp_retransmit_timer(struct sock *sk); 543 void tcp_xmit_retransmit_queue(struct sock *); 544 void tcp_simple_retransmit(struct sock *); 545 int tcp_trim_head(struct sock *, struct sk_buff *, u32); 546 int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t); 547 548 void tcp_send_probe0(struct sock *); 549 void tcp_send_partial(struct sock *); 550 int tcp_write_wakeup(struct sock *, int mib); 551 void tcp_send_fin(struct sock *sk); 552 void tcp_send_active_reset(struct sock *sk, gfp_t priority); 553 int tcp_send_synack(struct sock *); 554 void tcp_push_one(struct sock *, unsigned int mss_now); 555 void tcp_send_ack(struct sock *sk); 556 void tcp_send_delayed_ack(struct sock *sk); 557 void tcp_send_loss_probe(struct sock *sk); 558 bool tcp_schedule_loss_probe(struct sock *sk); 559 void tcp_skb_collapse_tstamp(struct sk_buff *skb, 560 const struct sk_buff *next_skb); 561 562 /* tcp_input.c */ 563 void tcp_resume_early_retransmit(struct sock *sk); 564 void tcp_rearm_rto(struct sock *sk); 565 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req); 566 void tcp_reset(struct sock *sk); 567 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb); 568 void tcp_fin(struct sock *sk); 569 570 /* tcp_timer.c */ 571 void tcp_init_xmit_timers(struct sock *); 572 static inline void tcp_clear_xmit_timers(struct sock *sk) 573 { 574 inet_csk_clear_xmit_timers(sk); 575 } 576 577 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 578 unsigned int tcp_current_mss(struct sock *sk); 579 580 /* Bound MSS / TSO packet size with the half of the window */ 581 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 582 { 583 int cutoff; 584 585 /* When peer uses tiny windows, there is no use in packetizing 586 * to sub-MSS pieces for the sake of SWS or making sure there 587 * are enough packets in the pipe for fast recovery. 588 * 589 * On the other hand, for extremely large MSS devices, handling 590 * smaller than MSS windows in this way does make sense. 591 */ 592 if (tp->max_window >= 512) 593 cutoff = (tp->max_window >> 1); 594 else 595 cutoff = tp->max_window; 596 597 if (cutoff && pktsize > cutoff) 598 return max_t(int, cutoff, 68U - tp->tcp_header_len); 599 else 600 return pktsize; 601 } 602 603 /* tcp.c */ 604 void tcp_get_info(struct sock *, struct tcp_info *); 605 606 /* Read 'sendfile()'-style from a TCP socket */ 607 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *, 608 unsigned int, size_t); 609 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 610 sk_read_actor_t recv_actor); 611 612 void tcp_initialize_rcv_mss(struct sock *sk); 613 614 int tcp_mtu_to_mss(struct sock *sk, int pmtu); 615 int tcp_mss_to_mtu(struct sock *sk, int mss); 616 void tcp_mtup_init(struct sock *sk); 617 void tcp_init_buffer_space(struct sock *sk); 618 619 static inline void tcp_bound_rto(const struct sock *sk) 620 { 621 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 622 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 623 } 624 625 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 626 { 627 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us); 628 } 629 630 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 631 { 632 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 633 ntohl(TCP_FLAG_ACK) | 634 snd_wnd); 635 } 636 637 static inline void tcp_fast_path_on(struct tcp_sock *tp) 638 { 639 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 640 } 641 642 static inline void tcp_fast_path_check(struct sock *sk) 643 { 644 struct tcp_sock *tp = tcp_sk(sk); 645 646 if (skb_queue_empty(&tp->out_of_order_queue) && 647 tp->rcv_wnd && 648 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 649 !tp->urg_data) 650 tcp_fast_path_on(tp); 651 } 652 653 /* Compute the actual rto_min value */ 654 static inline u32 tcp_rto_min(struct sock *sk) 655 { 656 const struct dst_entry *dst = __sk_dst_get(sk); 657 u32 rto_min = TCP_RTO_MIN; 658 659 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 660 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 661 return rto_min; 662 } 663 664 static inline u32 tcp_rto_min_us(struct sock *sk) 665 { 666 return jiffies_to_usecs(tcp_rto_min(sk)); 667 } 668 669 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst) 670 { 671 return dst_metric_locked(dst, RTAX_CC_ALGO); 672 } 673 674 /* Minimum RTT in usec. ~0 means not available. */ 675 static inline u32 tcp_min_rtt(const struct tcp_sock *tp) 676 { 677 return tp->rtt_min[0].rtt; 678 } 679 680 /* Compute the actual receive window we are currently advertising. 681 * Rcv_nxt can be after the window if our peer push more data 682 * than the offered window. 683 */ 684 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 685 { 686 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 687 688 if (win < 0) 689 win = 0; 690 return (u32) win; 691 } 692 693 /* Choose a new window, without checks for shrinking, and without 694 * scaling applied to the result. The caller does these things 695 * if necessary. This is a "raw" window selection. 696 */ 697 u32 __tcp_select_window(struct sock *sk); 698 699 void tcp_send_window_probe(struct sock *sk); 700 701 /* TCP timestamps are only 32-bits, this causes a slight 702 * complication on 64-bit systems since we store a snapshot 703 * of jiffies in the buffer control blocks below. We decided 704 * to use only the low 32-bits of jiffies and hide the ugly 705 * casts with the following macro. 706 */ 707 #define tcp_time_stamp ((__u32)(jiffies)) 708 709 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) 710 { 711 return skb->skb_mstamp.stamp_jiffies; 712 } 713 714 715 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 716 717 #define TCPHDR_FIN 0x01 718 #define TCPHDR_SYN 0x02 719 #define TCPHDR_RST 0x04 720 #define TCPHDR_PSH 0x08 721 #define TCPHDR_ACK 0x10 722 #define TCPHDR_URG 0x20 723 #define TCPHDR_ECE 0x40 724 #define TCPHDR_CWR 0x80 725 726 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) 727 728 /* This is what the send packet queuing engine uses to pass 729 * TCP per-packet control information to the transmission code. 730 * We also store the host-order sequence numbers in here too. 731 * This is 44 bytes if IPV6 is enabled. 732 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 733 */ 734 struct tcp_skb_cb { 735 __u32 seq; /* Starting sequence number */ 736 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 737 union { 738 /* Note : tcp_tw_isn is used in input path only 739 * (isn chosen by tcp_timewait_state_process()) 740 * 741 * tcp_gso_segs/size are used in write queue only, 742 * cf tcp_skb_pcount()/tcp_skb_mss() 743 */ 744 __u32 tcp_tw_isn; 745 struct { 746 u16 tcp_gso_segs; 747 u16 tcp_gso_size; 748 }; 749 }; 750 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 751 752 __u8 sacked; /* State flags for SACK/FACK. */ 753 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 754 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 755 #define TCPCB_LOST 0x04 /* SKB is lost */ 756 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 757 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */ 758 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 759 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \ 760 TCPCB_REPAIRED) 761 762 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 763 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */ 764 eor:1, /* Is skb MSG_EOR marked? */ 765 unused:6; 766 __u32 ack_seq; /* Sequence number ACK'd */ 767 union { 768 struct { 769 /* There is space for up to 20 bytes */ 770 } tx; /* only used for outgoing skbs */ 771 union { 772 struct inet_skb_parm h4; 773 #if IS_ENABLED(CONFIG_IPV6) 774 struct inet6_skb_parm h6; 775 #endif 776 } header; /* For incoming skbs */ 777 }; 778 }; 779 780 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 781 782 783 #if IS_ENABLED(CONFIG_IPV6) 784 /* This is the variant of inet6_iif() that must be used by TCP, 785 * as TCP moves IP6CB into a different location in skb->cb[] 786 */ 787 static inline int tcp_v6_iif(const struct sk_buff *skb) 788 { 789 bool l3_slave = skb_l3mdev_slave(TCP_SKB_CB(skb)->header.h6.flags); 790 791 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif; 792 } 793 #endif 794 795 /* Due to TSO, an SKB can be composed of multiple actual 796 * packets. To keep these tracked properly, we use this. 797 */ 798 static inline int tcp_skb_pcount(const struct sk_buff *skb) 799 { 800 return TCP_SKB_CB(skb)->tcp_gso_segs; 801 } 802 803 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 804 { 805 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 806 } 807 808 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 809 { 810 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 811 } 812 813 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ 814 static inline int tcp_skb_mss(const struct sk_buff *skb) 815 { 816 return TCP_SKB_CB(skb)->tcp_gso_size; 817 } 818 819 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb) 820 { 821 return likely(!TCP_SKB_CB(skb)->eor); 822 } 823 824 /* Events passed to congestion control interface */ 825 enum tcp_ca_event { 826 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 827 CA_EVENT_CWND_RESTART, /* congestion window restart */ 828 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 829 CA_EVENT_LOSS, /* loss timeout */ 830 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 831 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 832 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */ 833 CA_EVENT_NON_DELAYED_ACK, 834 }; 835 836 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 837 enum tcp_ca_ack_event_flags { 838 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 839 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 840 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 841 }; 842 843 /* 844 * Interface for adding new TCP congestion control handlers 845 */ 846 #define TCP_CA_NAME_MAX 16 847 #define TCP_CA_MAX 128 848 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 849 850 #define TCP_CA_UNSPEC 0 851 852 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 853 #define TCP_CONG_NON_RESTRICTED 0x1 854 /* Requires ECN/ECT set on all packets */ 855 #define TCP_CONG_NEEDS_ECN 0x2 856 857 union tcp_cc_info; 858 859 struct ack_sample { 860 u32 pkts_acked; 861 s32 rtt_us; 862 }; 863 864 struct tcp_congestion_ops { 865 struct list_head list; 866 u32 key; 867 u32 flags; 868 869 /* initialize private data (optional) */ 870 void (*init)(struct sock *sk); 871 /* cleanup private data (optional) */ 872 void (*release)(struct sock *sk); 873 874 /* return slow start threshold (required) */ 875 u32 (*ssthresh)(struct sock *sk); 876 /* do new cwnd calculation (required) */ 877 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 878 /* call before changing ca_state (optional) */ 879 void (*set_state)(struct sock *sk, u8 new_state); 880 /* call when cwnd event occurs (optional) */ 881 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 882 /* call when ack arrives (optional) */ 883 void (*in_ack_event)(struct sock *sk, u32 flags); 884 /* new value of cwnd after loss (optional) */ 885 u32 (*undo_cwnd)(struct sock *sk); 886 /* hook for packet ack accounting (optional) */ 887 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample); 888 /* get info for inet_diag (optional) */ 889 size_t (*get_info)(struct sock *sk, u32 ext, int *attr, 890 union tcp_cc_info *info); 891 892 char name[TCP_CA_NAME_MAX]; 893 struct module *owner; 894 }; 895 896 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 897 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 898 899 void tcp_assign_congestion_control(struct sock *sk); 900 void tcp_init_congestion_control(struct sock *sk); 901 void tcp_cleanup_congestion_control(struct sock *sk); 902 int tcp_set_default_congestion_control(const char *name); 903 void tcp_get_default_congestion_control(char *name); 904 void tcp_get_available_congestion_control(char *buf, size_t len); 905 void tcp_get_allowed_congestion_control(char *buf, size_t len); 906 int tcp_set_allowed_congestion_control(char *allowed); 907 int tcp_set_congestion_control(struct sock *sk, const char *name); 908 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); 909 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); 910 911 u32 tcp_reno_ssthresh(struct sock *sk); 912 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 913 extern struct tcp_congestion_ops tcp_reno; 914 915 struct tcp_congestion_ops *tcp_ca_find_key(u32 key); 916 u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca); 917 #ifdef CONFIG_INET 918 char *tcp_ca_get_name_by_key(u32 key, char *buffer); 919 #else 920 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) 921 { 922 return NULL; 923 } 924 #endif 925 926 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 927 { 928 const struct inet_connection_sock *icsk = inet_csk(sk); 929 930 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 931 } 932 933 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 934 { 935 struct inet_connection_sock *icsk = inet_csk(sk); 936 937 if (icsk->icsk_ca_ops->set_state) 938 icsk->icsk_ca_ops->set_state(sk, ca_state); 939 icsk->icsk_ca_state = ca_state; 940 } 941 942 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 943 { 944 const struct inet_connection_sock *icsk = inet_csk(sk); 945 946 if (icsk->icsk_ca_ops->cwnd_event) 947 icsk->icsk_ca_ops->cwnd_event(sk, event); 948 } 949 950 /* These functions determine how the current flow behaves in respect of SACK 951 * handling. SACK is negotiated with the peer, and therefore it can vary 952 * between different flows. 953 * 954 * tcp_is_sack - SACK enabled 955 * tcp_is_reno - No SACK 956 * tcp_is_fack - FACK enabled, implies SACK enabled 957 */ 958 static inline int tcp_is_sack(const struct tcp_sock *tp) 959 { 960 return tp->rx_opt.sack_ok; 961 } 962 963 static inline bool tcp_is_reno(const struct tcp_sock *tp) 964 { 965 return !tcp_is_sack(tp); 966 } 967 968 static inline bool tcp_is_fack(const struct tcp_sock *tp) 969 { 970 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED; 971 } 972 973 static inline void tcp_enable_fack(struct tcp_sock *tp) 974 { 975 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED; 976 } 977 978 /* TCP early-retransmit (ER) is similar to but more conservative than 979 * the thin-dupack feature. Enable ER only if thin-dupack is disabled. 980 */ 981 static inline void tcp_enable_early_retrans(struct tcp_sock *tp) 982 { 983 struct net *net = sock_net((struct sock *)tp); 984 985 tp->do_early_retrans = sysctl_tcp_early_retrans && 986 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack && 987 net->ipv4.sysctl_tcp_reordering == 3; 988 } 989 990 static inline void tcp_disable_early_retrans(struct tcp_sock *tp) 991 { 992 tp->do_early_retrans = 0; 993 } 994 995 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 996 { 997 return tp->sacked_out + tp->lost_out; 998 } 999 1000 /* This determines how many packets are "in the network" to the best 1001 * of our knowledge. In many cases it is conservative, but where 1002 * detailed information is available from the receiver (via SACK 1003 * blocks etc.) we can make more aggressive calculations. 1004 * 1005 * Use this for decisions involving congestion control, use just 1006 * tp->packets_out to determine if the send queue is empty or not. 1007 * 1008 * Read this equation as: 1009 * 1010 * "Packets sent once on transmission queue" MINUS 1011 * "Packets left network, but not honestly ACKed yet" PLUS 1012 * "Packets fast retransmitted" 1013 */ 1014 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 1015 { 1016 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 1017 } 1018 1019 #define TCP_INFINITE_SSTHRESH 0x7fffffff 1020 1021 static inline bool tcp_in_slow_start(const struct tcp_sock *tp) 1022 { 1023 return tp->snd_cwnd < tp->snd_ssthresh; 1024 } 1025 1026 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 1027 { 1028 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 1029 } 1030 1031 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 1032 { 1033 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 1034 (1 << inet_csk(sk)->icsk_ca_state); 1035 } 1036 1037 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 1038 * The exception is cwnd reduction phase, when cwnd is decreasing towards 1039 * ssthresh. 1040 */ 1041 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 1042 { 1043 const struct tcp_sock *tp = tcp_sk(sk); 1044 1045 if (tcp_in_cwnd_reduction(sk)) 1046 return tp->snd_ssthresh; 1047 else 1048 return max(tp->snd_ssthresh, 1049 ((tp->snd_cwnd >> 1) + 1050 (tp->snd_cwnd >> 2))); 1051 } 1052 1053 /* Use define here intentionally to get WARN_ON location shown at the caller */ 1054 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 1055 1056 void tcp_enter_cwr(struct sock *sk); 1057 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 1058 1059 /* The maximum number of MSS of available cwnd for which TSO defers 1060 * sending if not using sysctl_tcp_tso_win_divisor. 1061 */ 1062 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 1063 { 1064 return 3; 1065 } 1066 1067 /* Returns end sequence number of the receiver's advertised window */ 1068 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 1069 { 1070 return tp->snd_una + tp->snd_wnd; 1071 } 1072 1073 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 1074 * flexible approach. The RFC suggests cwnd should not be raised unless 1075 * it was fully used previously. And that's exactly what we do in 1076 * congestion avoidance mode. But in slow start we allow cwnd to grow 1077 * as long as the application has used half the cwnd. 1078 * Example : 1079 * cwnd is 10 (IW10), but application sends 9 frames. 1080 * We allow cwnd to reach 18 when all frames are ACKed. 1081 * This check is safe because it's as aggressive as slow start which already 1082 * risks 100% overshoot. The advantage is that we discourage application to 1083 * either send more filler packets or data to artificially blow up the cwnd 1084 * usage, and allow application-limited process to probe bw more aggressively. 1085 */ 1086 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1087 { 1088 const struct tcp_sock *tp = tcp_sk(sk); 1089 1090 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1091 if (tcp_in_slow_start(tp)) 1092 return tp->snd_cwnd < 2 * tp->max_packets_out; 1093 1094 return tp->is_cwnd_limited; 1095 } 1096 1097 /* Something is really bad, we could not queue an additional packet, 1098 * because qdisc is full or receiver sent a 0 window. 1099 * We do not want to add fuel to the fire, or abort too early, 1100 * so make sure the timer we arm now is at least 200ms in the future, 1101 * regardless of current icsk_rto value (as it could be ~2ms) 1102 */ 1103 static inline unsigned long tcp_probe0_base(const struct sock *sk) 1104 { 1105 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); 1106 } 1107 1108 /* Variant of inet_csk_rto_backoff() used for zero window probes */ 1109 static inline unsigned long tcp_probe0_when(const struct sock *sk, 1110 unsigned long max_when) 1111 { 1112 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff; 1113 1114 return (unsigned long)min_t(u64, when, max_when); 1115 } 1116 1117 static inline void tcp_check_probe_timer(struct sock *sk) 1118 { 1119 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) 1120 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1121 tcp_probe0_base(sk), TCP_RTO_MAX); 1122 } 1123 1124 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1125 { 1126 tp->snd_wl1 = seq; 1127 } 1128 1129 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1130 { 1131 tp->snd_wl1 = seq; 1132 } 1133 1134 /* 1135 * Calculate(/check) TCP checksum 1136 */ 1137 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1138 __be32 daddr, __wsum base) 1139 { 1140 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1141 } 1142 1143 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1144 { 1145 return __skb_checksum_complete(skb); 1146 } 1147 1148 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1149 { 1150 return !skb_csum_unnecessary(skb) && 1151 __tcp_checksum_complete(skb); 1152 } 1153 1154 /* Prequeue for VJ style copy to user, combined with checksumming. */ 1155 1156 static inline void tcp_prequeue_init(struct tcp_sock *tp) 1157 { 1158 tp->ucopy.task = NULL; 1159 tp->ucopy.len = 0; 1160 tp->ucopy.memory = 0; 1161 skb_queue_head_init(&tp->ucopy.prequeue); 1162 } 1163 1164 bool tcp_prequeue(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 union tcp_md5sum_block md5_blk; 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_header(struct tcp_md5sig_pool *, const struct tcphdr *); 1422 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1423 unsigned int header_len); 1424 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1425 const struct tcp_md5sig_key *key); 1426 1427 /* From tcp_fastopen.c */ 1428 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1429 struct tcp_fastopen_cookie *cookie, int *syn_loss, 1430 unsigned long *last_syn_loss); 1431 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1432 struct tcp_fastopen_cookie *cookie, bool syn_lost, 1433 u16 try_exp); 1434 struct tcp_fastopen_request { 1435 /* Fast Open cookie. Size 0 means a cookie request */ 1436 struct tcp_fastopen_cookie cookie; 1437 struct msghdr *data; /* data in MSG_FASTOPEN */ 1438 size_t size; 1439 int copied; /* queued in tcp_connect() */ 1440 }; 1441 void tcp_free_fastopen_req(struct tcp_sock *tp); 1442 1443 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; 1444 int tcp_fastopen_reset_cipher(void *key, unsigned int len); 1445 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb); 1446 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1447 struct request_sock *req, 1448 struct tcp_fastopen_cookie *foc, 1449 struct dst_entry *dst); 1450 void tcp_fastopen_init_key_once(bool publish); 1451 #define TCP_FASTOPEN_KEY_LENGTH 16 1452 1453 /* Fastopen key context */ 1454 struct tcp_fastopen_context { 1455 struct crypto_cipher *tfm; 1456 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1457 struct rcu_head rcu; 1458 }; 1459 1460 /* write queue abstraction */ 1461 static inline void tcp_write_queue_purge(struct sock *sk) 1462 { 1463 struct sk_buff *skb; 1464 1465 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) 1466 sk_wmem_free_skb(sk, skb); 1467 sk_mem_reclaim(sk); 1468 tcp_clear_all_retrans_hints(tcp_sk(sk)); 1469 } 1470 1471 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1472 { 1473 return skb_peek(&sk->sk_write_queue); 1474 } 1475 1476 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1477 { 1478 return skb_peek_tail(&sk->sk_write_queue); 1479 } 1480 1481 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk, 1482 const struct sk_buff *skb) 1483 { 1484 return skb_queue_next(&sk->sk_write_queue, skb); 1485 } 1486 1487 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk, 1488 const struct sk_buff *skb) 1489 { 1490 return skb_queue_prev(&sk->sk_write_queue, skb); 1491 } 1492 1493 #define tcp_for_write_queue(skb, sk) \ 1494 skb_queue_walk(&(sk)->sk_write_queue, skb) 1495 1496 #define tcp_for_write_queue_from(skb, sk) \ 1497 skb_queue_walk_from(&(sk)->sk_write_queue, skb) 1498 1499 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1500 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1501 1502 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1503 { 1504 return sk->sk_send_head; 1505 } 1506 1507 static inline bool tcp_skb_is_last(const struct sock *sk, 1508 const struct sk_buff *skb) 1509 { 1510 return skb_queue_is_last(&sk->sk_write_queue, skb); 1511 } 1512 1513 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb) 1514 { 1515 if (tcp_skb_is_last(sk, skb)) 1516 sk->sk_send_head = NULL; 1517 else 1518 sk->sk_send_head = tcp_write_queue_next(sk, skb); 1519 } 1520 1521 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1522 { 1523 if (sk->sk_send_head == skb_unlinked) 1524 sk->sk_send_head = NULL; 1525 } 1526 1527 static inline void tcp_init_send_head(struct sock *sk) 1528 { 1529 sk->sk_send_head = NULL; 1530 } 1531 1532 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1533 { 1534 __skb_queue_tail(&sk->sk_write_queue, skb); 1535 } 1536 1537 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1538 { 1539 __tcp_add_write_queue_tail(sk, skb); 1540 1541 /* Queue it, remembering where we must start sending. */ 1542 if (sk->sk_send_head == NULL) { 1543 sk->sk_send_head = skb; 1544 1545 if (tcp_sk(sk)->highest_sack == NULL) 1546 tcp_sk(sk)->highest_sack = skb; 1547 } 1548 } 1549 1550 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb) 1551 { 1552 __skb_queue_head(&sk->sk_write_queue, skb); 1553 } 1554 1555 /* Insert buff after skb on the write queue of sk. */ 1556 static inline void tcp_insert_write_queue_after(struct sk_buff *skb, 1557 struct sk_buff *buff, 1558 struct sock *sk) 1559 { 1560 __skb_queue_after(&sk->sk_write_queue, skb, buff); 1561 } 1562 1563 /* Insert new before skb on the write queue of sk. */ 1564 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1565 struct sk_buff *skb, 1566 struct sock *sk) 1567 { 1568 __skb_queue_before(&sk->sk_write_queue, skb, new); 1569 1570 if (sk->sk_send_head == skb) 1571 sk->sk_send_head = new; 1572 } 1573 1574 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1575 { 1576 __skb_unlink(skb, &sk->sk_write_queue); 1577 } 1578 1579 static inline bool tcp_write_queue_empty(struct sock *sk) 1580 { 1581 return skb_queue_empty(&sk->sk_write_queue); 1582 } 1583 1584 static inline void tcp_push_pending_frames(struct sock *sk) 1585 { 1586 if (tcp_send_head(sk)) { 1587 struct tcp_sock *tp = tcp_sk(sk); 1588 1589 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1590 } 1591 } 1592 1593 /* Start sequence of the skb just after the highest skb with SACKed 1594 * bit, valid only if sacked_out > 0 or when the caller has ensured 1595 * validity by itself. 1596 */ 1597 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1598 { 1599 if (!tp->sacked_out) 1600 return tp->snd_una; 1601 1602 if (tp->highest_sack == NULL) 1603 return tp->snd_nxt; 1604 1605 return TCP_SKB_CB(tp->highest_sack)->seq; 1606 } 1607 1608 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1609 { 1610 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL : 1611 tcp_write_queue_next(sk, skb); 1612 } 1613 1614 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1615 { 1616 return tcp_sk(sk)->highest_sack; 1617 } 1618 1619 static inline void tcp_highest_sack_reset(struct sock *sk) 1620 { 1621 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk); 1622 } 1623 1624 /* Called when old skb is about to be deleted (to be combined with new skb) */ 1625 static inline void tcp_highest_sack_combine(struct sock *sk, 1626 struct sk_buff *old, 1627 struct sk_buff *new) 1628 { 1629 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack)) 1630 tcp_sk(sk)->highest_sack = new; 1631 } 1632 1633 /* This helper checks if socket has IP_TRANSPARENT set */ 1634 static inline bool inet_sk_transparent(const struct sock *sk) 1635 { 1636 switch (sk->sk_state) { 1637 case TCP_TIME_WAIT: 1638 return inet_twsk(sk)->tw_transparent; 1639 case TCP_NEW_SYN_RECV: 1640 return inet_rsk(inet_reqsk(sk))->no_srccheck; 1641 } 1642 return inet_sk(sk)->transparent; 1643 } 1644 1645 /* Determines whether this is a thin stream (which may suffer from 1646 * increased latency). Used to trigger latency-reducing mechanisms. 1647 */ 1648 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1649 { 1650 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1651 } 1652 1653 /* /proc */ 1654 enum tcp_seq_states { 1655 TCP_SEQ_STATE_LISTENING, 1656 TCP_SEQ_STATE_ESTABLISHED, 1657 }; 1658 1659 int tcp_seq_open(struct inode *inode, struct file *file); 1660 1661 struct tcp_seq_afinfo { 1662 char *name; 1663 sa_family_t family; 1664 const struct file_operations *seq_fops; 1665 struct seq_operations seq_ops; 1666 }; 1667 1668 struct tcp_iter_state { 1669 struct seq_net_private p; 1670 sa_family_t family; 1671 enum tcp_seq_states state; 1672 struct sock *syn_wait_sk; 1673 int bucket, offset, sbucket, num; 1674 loff_t last_pos; 1675 }; 1676 1677 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1678 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1679 1680 extern struct request_sock_ops tcp_request_sock_ops; 1681 extern struct request_sock_ops tcp6_request_sock_ops; 1682 1683 void tcp_v4_destroy_sock(struct sock *sk); 1684 1685 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 1686 netdev_features_t features); 1687 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb); 1688 int tcp_gro_complete(struct sk_buff *skb); 1689 1690 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 1691 1692 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 1693 { 1694 struct net *net = sock_net((struct sock *)tp); 1695 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat; 1696 } 1697 1698 static inline bool tcp_stream_memory_free(const struct sock *sk) 1699 { 1700 const struct tcp_sock *tp = tcp_sk(sk); 1701 u32 notsent_bytes = tp->write_seq - tp->snd_nxt; 1702 1703 return notsent_bytes < tcp_notsent_lowat(tp); 1704 } 1705 1706 #ifdef CONFIG_PROC_FS 1707 int tcp4_proc_init(void); 1708 void tcp4_proc_exit(void); 1709 #endif 1710 1711 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req); 1712 int tcp_conn_request(struct request_sock_ops *rsk_ops, 1713 const struct tcp_request_sock_ops *af_ops, 1714 struct sock *sk, struct sk_buff *skb); 1715 1716 /* TCP af-specific functions */ 1717 struct tcp_sock_af_ops { 1718 #ifdef CONFIG_TCP_MD5SIG 1719 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk, 1720 const struct sock *addr_sk); 1721 int (*calc_md5_hash)(char *location, 1722 const struct tcp_md5sig_key *md5, 1723 const struct sock *sk, 1724 const struct sk_buff *skb); 1725 int (*md5_parse)(struct sock *sk, 1726 char __user *optval, 1727 int optlen); 1728 #endif 1729 }; 1730 1731 struct tcp_request_sock_ops { 1732 u16 mss_clamp; 1733 #ifdef CONFIG_TCP_MD5SIG 1734 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk, 1735 const struct sock *addr_sk); 1736 int (*calc_md5_hash) (char *location, 1737 const struct tcp_md5sig_key *md5, 1738 const struct sock *sk, 1739 const struct sk_buff *skb); 1740 #endif 1741 void (*init_req)(struct request_sock *req, 1742 const struct sock *sk_listener, 1743 struct sk_buff *skb); 1744 #ifdef CONFIG_SYN_COOKIES 1745 __u32 (*cookie_init_seq)(const struct sk_buff *skb, 1746 __u16 *mss); 1747 #endif 1748 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl, 1749 const struct request_sock *req, 1750 bool *strict); 1751 __u32 (*init_seq)(const struct sk_buff *skb); 1752 int (*send_synack)(const struct sock *sk, struct dst_entry *dst, 1753 struct flowi *fl, struct request_sock *req, 1754 struct tcp_fastopen_cookie *foc, 1755 enum tcp_synack_type synack_type); 1756 }; 1757 1758 #ifdef CONFIG_SYN_COOKIES 1759 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1760 const struct sock *sk, struct sk_buff *skb, 1761 __u16 *mss) 1762 { 1763 tcp_synq_overflow(sk); 1764 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); 1765 return ops->cookie_init_seq(skb, mss); 1766 } 1767 #else 1768 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1769 const struct sock *sk, struct sk_buff *skb, 1770 __u16 *mss) 1771 { 1772 return 0; 1773 } 1774 #endif 1775 1776 int tcpv4_offload_init(void); 1777 1778 void tcp_v4_init(void); 1779 void tcp_init(void); 1780 1781 /* tcp_recovery.c */ 1782 1783 /* Flags to enable various loss recovery features. See below */ 1784 extern int sysctl_tcp_recovery; 1785 1786 /* Use TCP RACK to detect (some) tail and retransmit losses */ 1787 #define TCP_RACK_LOST_RETRANS 0x1 1788 1789 extern int tcp_rack_mark_lost(struct sock *sk); 1790 1791 extern void tcp_rack_advance(struct tcp_sock *tp, 1792 const struct skb_mstamp *xmit_time, u8 sacked); 1793 1794 /* 1795 * Save and compile IPv4 options, return a pointer to it 1796 */ 1797 static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb) 1798 { 1799 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; 1800 struct ip_options_rcu *dopt = NULL; 1801 1802 if (opt->optlen) { 1803 int opt_size = sizeof(*dopt) + opt->optlen; 1804 1805 dopt = kmalloc(opt_size, GFP_ATOMIC); 1806 if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) { 1807 kfree(dopt); 1808 dopt = NULL; 1809 } 1810 } 1811 return dopt; 1812 } 1813 1814 /* locally generated TCP pure ACKs have skb->truesize == 2 1815 * (check tcp_send_ack() in net/ipv4/tcp_output.c ) 1816 * This is much faster than dissecting the packet to find out. 1817 * (Think of GRE encapsulations, IPv4, IPv6, ...) 1818 */ 1819 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb) 1820 { 1821 return skb->truesize == 2; 1822 } 1823 1824 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb) 1825 { 1826 skb->truesize = 2; 1827 } 1828 1829 static inline int tcp_inq(struct sock *sk) 1830 { 1831 struct tcp_sock *tp = tcp_sk(sk); 1832 int answ; 1833 1834 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { 1835 answ = 0; 1836 } else if (sock_flag(sk, SOCK_URGINLINE) || 1837 !tp->urg_data || 1838 before(tp->urg_seq, tp->copied_seq) || 1839 !before(tp->urg_seq, tp->rcv_nxt)) { 1840 1841 answ = tp->rcv_nxt - tp->copied_seq; 1842 1843 /* Subtract 1, if FIN was received */ 1844 if (answ && sock_flag(sk, SOCK_DONE)) 1845 answ--; 1846 } else { 1847 answ = tp->urg_seq - tp->copied_seq; 1848 } 1849 1850 return answ; 1851 } 1852 1853 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb) 1854 { 1855 u16 segs_in; 1856 1857 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs); 1858 tp->segs_in += segs_in; 1859 if (skb->len > tcp_hdrlen(skb)) 1860 tp->data_segs_in += segs_in; 1861 } 1862 1863 /* 1864 * TCP listen path runs lockless. 1865 * We forced "struct sock" to be const qualified to make sure 1866 * we don't modify one of its field by mistake. 1867 * Here, we increment sk_drops which is an atomic_t, so we can safely 1868 * make sock writable again. 1869 */ 1870 static inline void tcp_listendrop(const struct sock *sk) 1871 { 1872 atomic_inc(&((struct sock *)sk)->sk_drops); 1873 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 1874 } 1875 1876 #endif /* _TCP_H */ 1877