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 > TCP_MSS_DEFAULT) 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 __u32 in_flight;/* Bytes in flight when packet sent */ 771 } tx; /* only used for outgoing skbs */ 772 union { 773 struct inet_skb_parm h4; 774 #if IS_ENABLED(CONFIG_IPV6) 775 struct inet6_skb_parm h6; 776 #endif 777 } header; /* For incoming skbs */ 778 }; 779 }; 780 781 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 782 783 784 #if IS_ENABLED(CONFIG_IPV6) 785 /* This is the variant of inet6_iif() that must be used by TCP, 786 * as TCP moves IP6CB into a different location in skb->cb[] 787 */ 788 static inline int tcp_v6_iif(const struct sk_buff *skb) 789 { 790 bool l3_slave = skb_l3mdev_slave(TCP_SKB_CB(skb)->header.h6.flags); 791 792 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif; 793 } 794 #endif 795 796 /* Due to TSO, an SKB can be composed of multiple actual 797 * packets. To keep these tracked properly, we use this. 798 */ 799 static inline int tcp_skb_pcount(const struct sk_buff *skb) 800 { 801 return TCP_SKB_CB(skb)->tcp_gso_segs; 802 } 803 804 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 805 { 806 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 807 } 808 809 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 810 { 811 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 812 } 813 814 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ 815 static inline int tcp_skb_mss(const struct sk_buff *skb) 816 { 817 return TCP_SKB_CB(skb)->tcp_gso_size; 818 } 819 820 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb) 821 { 822 return likely(!TCP_SKB_CB(skb)->eor); 823 } 824 825 /* Events passed to congestion control interface */ 826 enum tcp_ca_event { 827 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 828 CA_EVENT_CWND_RESTART, /* congestion window restart */ 829 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 830 CA_EVENT_LOSS, /* loss timeout */ 831 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 832 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 833 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */ 834 CA_EVENT_NON_DELAYED_ACK, 835 }; 836 837 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 838 enum tcp_ca_ack_event_flags { 839 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 840 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 841 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 842 }; 843 844 /* 845 * Interface for adding new TCP congestion control handlers 846 */ 847 #define TCP_CA_NAME_MAX 16 848 #define TCP_CA_MAX 128 849 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 850 851 #define TCP_CA_UNSPEC 0 852 853 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 854 #define TCP_CONG_NON_RESTRICTED 0x1 855 /* Requires ECN/ECT set on all packets */ 856 #define TCP_CONG_NEEDS_ECN 0x2 857 858 union tcp_cc_info; 859 860 struct ack_sample { 861 u32 pkts_acked; 862 s32 rtt_us; 863 u32 in_flight; 864 }; 865 866 struct tcp_congestion_ops { 867 struct list_head list; 868 u32 key; 869 u32 flags; 870 871 /* initialize private data (optional) */ 872 void (*init)(struct sock *sk); 873 /* cleanup private data (optional) */ 874 void (*release)(struct sock *sk); 875 876 /* return slow start threshold (required) */ 877 u32 (*ssthresh)(struct sock *sk); 878 /* do new cwnd calculation (required) */ 879 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 880 /* call before changing ca_state (optional) */ 881 void (*set_state)(struct sock *sk, u8 new_state); 882 /* call when cwnd event occurs (optional) */ 883 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 884 /* call when ack arrives (optional) */ 885 void (*in_ack_event)(struct sock *sk, u32 flags); 886 /* new value of cwnd after loss (optional) */ 887 u32 (*undo_cwnd)(struct sock *sk); 888 /* hook for packet ack accounting (optional) */ 889 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample); 890 /* get info for inet_diag (optional) */ 891 size_t (*get_info)(struct sock *sk, u32 ext, int *attr, 892 union tcp_cc_info *info); 893 894 char name[TCP_CA_NAME_MAX]; 895 struct module *owner; 896 }; 897 898 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 899 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 900 901 void tcp_assign_congestion_control(struct sock *sk); 902 void tcp_init_congestion_control(struct sock *sk); 903 void tcp_cleanup_congestion_control(struct sock *sk); 904 int tcp_set_default_congestion_control(const char *name); 905 void tcp_get_default_congestion_control(char *name); 906 void tcp_get_available_congestion_control(char *buf, size_t len); 907 void tcp_get_allowed_congestion_control(char *buf, size_t len); 908 int tcp_set_allowed_congestion_control(char *allowed); 909 int tcp_set_congestion_control(struct sock *sk, const char *name); 910 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); 911 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); 912 913 u32 tcp_reno_ssthresh(struct sock *sk); 914 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 915 extern struct tcp_congestion_ops tcp_reno; 916 917 struct tcp_congestion_ops *tcp_ca_find_key(u32 key); 918 u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca); 919 #ifdef CONFIG_INET 920 char *tcp_ca_get_name_by_key(u32 key, char *buffer); 921 #else 922 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) 923 { 924 return NULL; 925 } 926 #endif 927 928 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 929 { 930 const struct inet_connection_sock *icsk = inet_csk(sk); 931 932 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 933 } 934 935 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 936 { 937 struct inet_connection_sock *icsk = inet_csk(sk); 938 939 if (icsk->icsk_ca_ops->set_state) 940 icsk->icsk_ca_ops->set_state(sk, ca_state); 941 icsk->icsk_ca_state = ca_state; 942 } 943 944 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 945 { 946 const struct inet_connection_sock *icsk = inet_csk(sk); 947 948 if (icsk->icsk_ca_ops->cwnd_event) 949 icsk->icsk_ca_ops->cwnd_event(sk, event); 950 } 951 952 /* These functions determine how the current flow behaves in respect of SACK 953 * handling. SACK is negotiated with the peer, and therefore it can vary 954 * between different flows. 955 * 956 * tcp_is_sack - SACK enabled 957 * tcp_is_reno - No SACK 958 * tcp_is_fack - FACK enabled, implies SACK enabled 959 */ 960 static inline int tcp_is_sack(const struct tcp_sock *tp) 961 { 962 return tp->rx_opt.sack_ok; 963 } 964 965 static inline bool tcp_is_reno(const struct tcp_sock *tp) 966 { 967 return !tcp_is_sack(tp); 968 } 969 970 static inline bool tcp_is_fack(const struct tcp_sock *tp) 971 { 972 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED; 973 } 974 975 static inline void tcp_enable_fack(struct tcp_sock *tp) 976 { 977 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED; 978 } 979 980 /* TCP early-retransmit (ER) is similar to but more conservative than 981 * the thin-dupack feature. Enable ER only if thin-dupack is disabled. 982 */ 983 static inline void tcp_enable_early_retrans(struct tcp_sock *tp) 984 { 985 struct net *net = sock_net((struct sock *)tp); 986 987 tp->do_early_retrans = sysctl_tcp_early_retrans && 988 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack && 989 net->ipv4.sysctl_tcp_reordering == 3; 990 } 991 992 static inline void tcp_disable_early_retrans(struct tcp_sock *tp) 993 { 994 tp->do_early_retrans = 0; 995 } 996 997 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 998 { 999 return tp->sacked_out + tp->lost_out; 1000 } 1001 1002 /* This determines how many packets are "in the network" to the best 1003 * of our knowledge. In many cases it is conservative, but where 1004 * detailed information is available from the receiver (via SACK 1005 * blocks etc.) we can make more aggressive calculations. 1006 * 1007 * Use this for decisions involving congestion control, use just 1008 * tp->packets_out to determine if the send queue is empty or not. 1009 * 1010 * Read this equation as: 1011 * 1012 * "Packets sent once on transmission queue" MINUS 1013 * "Packets left network, but not honestly ACKed yet" PLUS 1014 * "Packets fast retransmitted" 1015 */ 1016 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 1017 { 1018 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 1019 } 1020 1021 #define TCP_INFINITE_SSTHRESH 0x7fffffff 1022 1023 static inline bool tcp_in_slow_start(const struct tcp_sock *tp) 1024 { 1025 return tp->snd_cwnd < tp->snd_ssthresh; 1026 } 1027 1028 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 1029 { 1030 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 1031 } 1032 1033 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 1034 { 1035 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 1036 (1 << inet_csk(sk)->icsk_ca_state); 1037 } 1038 1039 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 1040 * The exception is cwnd reduction phase, when cwnd is decreasing towards 1041 * ssthresh. 1042 */ 1043 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 1044 { 1045 const struct tcp_sock *tp = tcp_sk(sk); 1046 1047 if (tcp_in_cwnd_reduction(sk)) 1048 return tp->snd_ssthresh; 1049 else 1050 return max(tp->snd_ssthresh, 1051 ((tp->snd_cwnd >> 1) + 1052 (tp->snd_cwnd >> 2))); 1053 } 1054 1055 /* Use define here intentionally to get WARN_ON location shown at the caller */ 1056 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 1057 1058 void tcp_enter_cwr(struct sock *sk); 1059 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 1060 1061 /* The maximum number of MSS of available cwnd for which TSO defers 1062 * sending if not using sysctl_tcp_tso_win_divisor. 1063 */ 1064 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 1065 { 1066 return 3; 1067 } 1068 1069 /* Returns end sequence number of the receiver's advertised window */ 1070 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 1071 { 1072 return tp->snd_una + tp->snd_wnd; 1073 } 1074 1075 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 1076 * flexible approach. The RFC suggests cwnd should not be raised unless 1077 * it was fully used previously. And that's exactly what we do in 1078 * congestion avoidance mode. But in slow start we allow cwnd to grow 1079 * as long as the application has used half the cwnd. 1080 * Example : 1081 * cwnd is 10 (IW10), but application sends 9 frames. 1082 * We allow cwnd to reach 18 when all frames are ACKed. 1083 * This check is safe because it's as aggressive as slow start which already 1084 * risks 100% overshoot. The advantage is that we discourage application to 1085 * either send more filler packets or data to artificially blow up the cwnd 1086 * usage, and allow application-limited process to probe bw more aggressively. 1087 */ 1088 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1089 { 1090 const struct tcp_sock *tp = tcp_sk(sk); 1091 1092 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1093 if (tcp_in_slow_start(tp)) 1094 return tp->snd_cwnd < 2 * tp->max_packets_out; 1095 1096 return tp->is_cwnd_limited; 1097 } 1098 1099 /* Something is really bad, we could not queue an additional packet, 1100 * because qdisc is full or receiver sent a 0 window. 1101 * We do not want to add fuel to the fire, or abort too early, 1102 * so make sure the timer we arm now is at least 200ms in the future, 1103 * regardless of current icsk_rto value (as it could be ~2ms) 1104 */ 1105 static inline unsigned long tcp_probe0_base(const struct sock *sk) 1106 { 1107 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); 1108 } 1109 1110 /* Variant of inet_csk_rto_backoff() used for zero window probes */ 1111 static inline unsigned long tcp_probe0_when(const struct sock *sk, 1112 unsigned long max_when) 1113 { 1114 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff; 1115 1116 return (unsigned long)min_t(u64, when, max_when); 1117 } 1118 1119 static inline void tcp_check_probe_timer(struct sock *sk) 1120 { 1121 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) 1122 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1123 tcp_probe0_base(sk), TCP_RTO_MAX); 1124 } 1125 1126 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1127 { 1128 tp->snd_wl1 = seq; 1129 } 1130 1131 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1132 { 1133 tp->snd_wl1 = seq; 1134 } 1135 1136 /* 1137 * Calculate(/check) TCP checksum 1138 */ 1139 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1140 __be32 daddr, __wsum base) 1141 { 1142 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1143 } 1144 1145 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1146 { 1147 return __skb_checksum_complete(skb); 1148 } 1149 1150 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1151 { 1152 return !skb_csum_unnecessary(skb) && 1153 __tcp_checksum_complete(skb); 1154 } 1155 1156 /* Prequeue for VJ style copy to user, combined with checksumming. */ 1157 1158 static inline void tcp_prequeue_init(struct tcp_sock *tp) 1159 { 1160 tp->ucopy.task = NULL; 1161 tp->ucopy.len = 0; 1162 tp->ucopy.memory = 0; 1163 skb_queue_head_init(&tp->ucopy.prequeue); 1164 } 1165 1166 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb); 1167 1168 #undef STATE_TRACE 1169 1170 #ifdef STATE_TRACE 1171 static const char *statename[]={ 1172 "Unused","Established","Syn Sent","Syn Recv", 1173 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1174 "Close Wait","Last ACK","Listen","Closing" 1175 }; 1176 #endif 1177 void tcp_set_state(struct sock *sk, int state); 1178 1179 void tcp_done(struct sock *sk); 1180 1181 int tcp_abort(struct sock *sk, int err); 1182 1183 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1184 { 1185 rx_opt->dsack = 0; 1186 rx_opt->num_sacks = 0; 1187 } 1188 1189 u32 tcp_default_init_rwnd(u32 mss); 1190 void tcp_cwnd_restart(struct sock *sk, s32 delta); 1191 1192 static inline void tcp_slow_start_after_idle_check(struct sock *sk) 1193 { 1194 struct tcp_sock *tp = tcp_sk(sk); 1195 s32 delta; 1196 1197 if (!sysctl_tcp_slow_start_after_idle || tp->packets_out) 1198 return; 1199 delta = tcp_time_stamp - tp->lsndtime; 1200 if (delta > inet_csk(sk)->icsk_rto) 1201 tcp_cwnd_restart(sk, delta); 1202 } 1203 1204 /* Determine a window scaling and initial window to offer. */ 1205 void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd, 1206 __u32 *window_clamp, int wscale_ok, 1207 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1208 1209 static inline int tcp_win_from_space(int space) 1210 { 1211 return sysctl_tcp_adv_win_scale<=0 ? 1212 (space>>(-sysctl_tcp_adv_win_scale)) : 1213 space - (space>>sysctl_tcp_adv_win_scale); 1214 } 1215 1216 /* Note: caller must be prepared to deal with negative returns */ 1217 static inline int tcp_space(const struct sock *sk) 1218 { 1219 return tcp_win_from_space(sk->sk_rcvbuf - 1220 atomic_read(&sk->sk_rmem_alloc)); 1221 } 1222 1223 static inline int tcp_full_space(const struct sock *sk) 1224 { 1225 return tcp_win_from_space(sk->sk_rcvbuf); 1226 } 1227 1228 extern void tcp_openreq_init_rwin(struct request_sock *req, 1229 const struct sock *sk_listener, 1230 const struct dst_entry *dst); 1231 1232 void tcp_enter_memory_pressure(struct sock *sk); 1233 1234 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1235 { 1236 struct net *net = sock_net((struct sock *)tp); 1237 1238 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl; 1239 } 1240 1241 static inline int keepalive_time_when(const struct tcp_sock *tp) 1242 { 1243 struct net *net = sock_net((struct sock *)tp); 1244 1245 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time; 1246 } 1247 1248 static inline int keepalive_probes(const struct tcp_sock *tp) 1249 { 1250 struct net *net = sock_net((struct sock *)tp); 1251 1252 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes; 1253 } 1254 1255 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1256 { 1257 const struct inet_connection_sock *icsk = &tp->inet_conn; 1258 1259 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime, 1260 tcp_time_stamp - tp->rcv_tstamp); 1261 } 1262 1263 static inline int tcp_fin_time(const struct sock *sk) 1264 { 1265 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout; 1266 const int rto = inet_csk(sk)->icsk_rto; 1267 1268 if (fin_timeout < (rto << 2) - (rto >> 1)) 1269 fin_timeout = (rto << 2) - (rto >> 1); 1270 1271 return fin_timeout; 1272 } 1273 1274 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1275 int paws_win) 1276 { 1277 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1278 return true; 1279 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1280 return true; 1281 /* 1282 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1283 * then following tcp messages have valid values. Ignore 0 value, 1284 * or else 'negative' tsval might forbid us to accept their packets. 1285 */ 1286 if (!rx_opt->ts_recent) 1287 return true; 1288 return false; 1289 } 1290 1291 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1292 int rst) 1293 { 1294 if (tcp_paws_check(rx_opt, 0)) 1295 return false; 1296 1297 /* RST segments are not recommended to carry timestamp, 1298 and, if they do, it is recommended to ignore PAWS because 1299 "their cleanup function should take precedence over timestamps." 1300 Certainly, it is mistake. It is necessary to understand the reasons 1301 of this constraint to relax it: if peer reboots, clock may go 1302 out-of-sync and half-open connections will not be reset. 1303 Actually, the problem would be not existing if all 1304 the implementations followed draft about maintaining clock 1305 via reboots. Linux-2.2 DOES NOT! 1306 1307 However, we can relax time bounds for RST segments to MSL. 1308 */ 1309 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1310 return false; 1311 return true; 1312 } 1313 1314 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, 1315 int mib_idx, u32 *last_oow_ack_time); 1316 1317 static inline void tcp_mib_init(struct net *net) 1318 { 1319 /* See RFC 2012 */ 1320 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1); 1321 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1322 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1323 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1); 1324 } 1325 1326 /* from STCP */ 1327 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1328 { 1329 tp->lost_skb_hint = NULL; 1330 } 1331 1332 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1333 { 1334 tcp_clear_retrans_hints_partial(tp); 1335 tp->retransmit_skb_hint = NULL; 1336 } 1337 1338 union tcp_md5_addr { 1339 struct in_addr a4; 1340 #if IS_ENABLED(CONFIG_IPV6) 1341 struct in6_addr a6; 1342 #endif 1343 }; 1344 1345 /* - key database */ 1346 struct tcp_md5sig_key { 1347 struct hlist_node node; 1348 u8 keylen; 1349 u8 family; /* AF_INET or AF_INET6 */ 1350 union tcp_md5_addr addr; 1351 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1352 struct rcu_head rcu; 1353 }; 1354 1355 /* - sock block */ 1356 struct tcp_md5sig_info { 1357 struct hlist_head head; 1358 struct rcu_head rcu; 1359 }; 1360 1361 /* - pseudo header */ 1362 struct tcp4_pseudohdr { 1363 __be32 saddr; 1364 __be32 daddr; 1365 __u8 pad; 1366 __u8 protocol; 1367 __be16 len; 1368 }; 1369 1370 struct tcp6_pseudohdr { 1371 struct in6_addr saddr; 1372 struct in6_addr daddr; 1373 __be32 len; 1374 __be32 protocol; /* including padding */ 1375 }; 1376 1377 union tcp_md5sum_block { 1378 struct tcp4_pseudohdr ip4; 1379 #if IS_ENABLED(CONFIG_IPV6) 1380 struct tcp6_pseudohdr ip6; 1381 #endif 1382 }; 1383 1384 /* - pool: digest algorithm, hash description and scratch buffer */ 1385 struct tcp_md5sig_pool { 1386 struct ahash_request *md5_req; 1387 void *scratch; 1388 }; 1389 1390 /* - functions */ 1391 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1392 const struct sock *sk, const struct sk_buff *skb); 1393 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1394 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp); 1395 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1396 int family); 1397 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 1398 const struct sock *addr_sk); 1399 1400 #ifdef CONFIG_TCP_MD5SIG 1401 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1402 const union tcp_md5_addr *addr, 1403 int family); 1404 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1405 #else 1406 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1407 const union tcp_md5_addr *addr, 1408 int family) 1409 { 1410 return NULL; 1411 } 1412 #define tcp_twsk_md5_key(twsk) NULL 1413 #endif 1414 1415 bool tcp_alloc_md5sig_pool(void); 1416 1417 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1418 static inline void tcp_put_md5sig_pool(void) 1419 { 1420 local_bh_enable(); 1421 } 1422 1423 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1424 unsigned int header_len); 1425 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1426 const struct tcp_md5sig_key *key); 1427 1428 /* From tcp_fastopen.c */ 1429 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1430 struct tcp_fastopen_cookie *cookie, int *syn_loss, 1431 unsigned long *last_syn_loss); 1432 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1433 struct tcp_fastopen_cookie *cookie, bool syn_lost, 1434 u16 try_exp); 1435 struct tcp_fastopen_request { 1436 /* Fast Open cookie. Size 0 means a cookie request */ 1437 struct tcp_fastopen_cookie cookie; 1438 struct msghdr *data; /* data in MSG_FASTOPEN */ 1439 size_t size; 1440 int copied; /* queued in tcp_connect() */ 1441 }; 1442 void tcp_free_fastopen_req(struct tcp_sock *tp); 1443 1444 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; 1445 int tcp_fastopen_reset_cipher(void *key, unsigned int len); 1446 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb); 1447 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1448 struct request_sock *req, 1449 struct tcp_fastopen_cookie *foc, 1450 struct dst_entry *dst); 1451 void tcp_fastopen_init_key_once(bool publish); 1452 #define TCP_FASTOPEN_KEY_LENGTH 16 1453 1454 /* Fastopen key context */ 1455 struct tcp_fastopen_context { 1456 struct crypto_cipher *tfm; 1457 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1458 struct rcu_head rcu; 1459 }; 1460 1461 /* write queue abstraction */ 1462 static inline void tcp_write_queue_purge(struct sock *sk) 1463 { 1464 struct sk_buff *skb; 1465 1466 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) 1467 sk_wmem_free_skb(sk, skb); 1468 sk_mem_reclaim(sk); 1469 tcp_clear_all_retrans_hints(tcp_sk(sk)); 1470 } 1471 1472 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1473 { 1474 return skb_peek(&sk->sk_write_queue); 1475 } 1476 1477 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1478 { 1479 return skb_peek_tail(&sk->sk_write_queue); 1480 } 1481 1482 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk, 1483 const struct sk_buff *skb) 1484 { 1485 return skb_queue_next(&sk->sk_write_queue, skb); 1486 } 1487 1488 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk, 1489 const struct sk_buff *skb) 1490 { 1491 return skb_queue_prev(&sk->sk_write_queue, skb); 1492 } 1493 1494 #define tcp_for_write_queue(skb, sk) \ 1495 skb_queue_walk(&(sk)->sk_write_queue, skb) 1496 1497 #define tcp_for_write_queue_from(skb, sk) \ 1498 skb_queue_walk_from(&(sk)->sk_write_queue, skb) 1499 1500 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1501 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1502 1503 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1504 { 1505 return sk->sk_send_head; 1506 } 1507 1508 static inline bool tcp_skb_is_last(const struct sock *sk, 1509 const struct sk_buff *skb) 1510 { 1511 return skb_queue_is_last(&sk->sk_write_queue, skb); 1512 } 1513 1514 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb) 1515 { 1516 if (tcp_skb_is_last(sk, skb)) 1517 sk->sk_send_head = NULL; 1518 else 1519 sk->sk_send_head = tcp_write_queue_next(sk, skb); 1520 } 1521 1522 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1523 { 1524 if (sk->sk_send_head == skb_unlinked) 1525 sk->sk_send_head = 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 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb) 1855 { 1856 u16 segs_in; 1857 1858 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs); 1859 tp->segs_in += segs_in; 1860 if (skb->len > tcp_hdrlen(skb)) 1861 tp->data_segs_in += segs_in; 1862 } 1863 1864 /* 1865 * TCP listen path runs lockless. 1866 * We forced "struct sock" to be const qualified to make sure 1867 * we don't modify one of its field by mistake. 1868 * Here, we increment sk_drops which is an atomic_t, so we can safely 1869 * make sock writable again. 1870 */ 1871 static inline void tcp_listendrop(const struct sock *sk) 1872 { 1873 atomic_inc(&((struct sock *)sk)->sk_drops); 1874 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 1875 } 1876 1877 #endif /* _TCP_H */ 1878