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 return TCP_SKB_CB(skb)->header.h6.iif; 790 } 791 #endif 792 793 /* Due to TSO, an SKB can be composed of multiple actual 794 * packets. To keep these tracked properly, we use this. 795 */ 796 static inline int tcp_skb_pcount(const struct sk_buff *skb) 797 { 798 return TCP_SKB_CB(skb)->tcp_gso_segs; 799 } 800 801 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 802 { 803 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 804 } 805 806 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 807 { 808 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 809 } 810 811 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ 812 static inline int tcp_skb_mss(const struct sk_buff *skb) 813 { 814 return TCP_SKB_CB(skb)->tcp_gso_size; 815 } 816 817 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb) 818 { 819 return likely(!TCP_SKB_CB(skb)->eor); 820 } 821 822 /* Events passed to congestion control interface */ 823 enum tcp_ca_event { 824 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 825 CA_EVENT_CWND_RESTART, /* congestion window restart */ 826 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 827 CA_EVENT_LOSS, /* loss timeout */ 828 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 829 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 830 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */ 831 CA_EVENT_NON_DELAYED_ACK, 832 }; 833 834 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 835 enum tcp_ca_ack_event_flags { 836 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 837 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 838 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 839 }; 840 841 /* 842 * Interface for adding new TCP congestion control handlers 843 */ 844 #define TCP_CA_NAME_MAX 16 845 #define TCP_CA_MAX 128 846 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 847 848 #define TCP_CA_UNSPEC 0 849 850 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 851 #define TCP_CONG_NON_RESTRICTED 0x1 852 /* Requires ECN/ECT set on all packets */ 853 #define TCP_CONG_NEEDS_ECN 0x2 854 855 union tcp_cc_info; 856 857 struct tcp_congestion_ops { 858 struct list_head list; 859 u32 key; 860 u32 flags; 861 862 /* initialize private data (optional) */ 863 void (*init)(struct sock *sk); 864 /* cleanup private data (optional) */ 865 void (*release)(struct sock *sk); 866 867 /* return slow start threshold (required) */ 868 u32 (*ssthresh)(struct sock *sk); 869 /* do new cwnd calculation (required) */ 870 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 871 /* call before changing ca_state (optional) */ 872 void (*set_state)(struct sock *sk, u8 new_state); 873 /* call when cwnd event occurs (optional) */ 874 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 875 /* call when ack arrives (optional) */ 876 void (*in_ack_event)(struct sock *sk, u32 flags); 877 /* new value of cwnd after loss (optional) */ 878 u32 (*undo_cwnd)(struct sock *sk); 879 /* hook for packet ack accounting (optional) */ 880 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us); 881 /* get info for inet_diag (optional) */ 882 size_t (*get_info)(struct sock *sk, u32 ext, int *attr, 883 union tcp_cc_info *info); 884 885 char name[TCP_CA_NAME_MAX]; 886 struct module *owner; 887 }; 888 889 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 890 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 891 892 void tcp_assign_congestion_control(struct sock *sk); 893 void tcp_init_congestion_control(struct sock *sk); 894 void tcp_cleanup_congestion_control(struct sock *sk); 895 int tcp_set_default_congestion_control(const char *name); 896 void tcp_get_default_congestion_control(char *name); 897 void tcp_get_available_congestion_control(char *buf, size_t len); 898 void tcp_get_allowed_congestion_control(char *buf, size_t len); 899 int tcp_set_allowed_congestion_control(char *allowed); 900 int tcp_set_congestion_control(struct sock *sk, const char *name); 901 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); 902 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); 903 904 u32 tcp_reno_ssthresh(struct sock *sk); 905 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 906 extern struct tcp_congestion_ops tcp_reno; 907 908 struct tcp_congestion_ops *tcp_ca_find_key(u32 key); 909 u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca); 910 #ifdef CONFIG_INET 911 char *tcp_ca_get_name_by_key(u32 key, char *buffer); 912 #else 913 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) 914 { 915 return NULL; 916 } 917 #endif 918 919 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 920 { 921 const struct inet_connection_sock *icsk = inet_csk(sk); 922 923 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 924 } 925 926 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 927 { 928 struct inet_connection_sock *icsk = inet_csk(sk); 929 930 if (icsk->icsk_ca_ops->set_state) 931 icsk->icsk_ca_ops->set_state(sk, ca_state); 932 icsk->icsk_ca_state = ca_state; 933 } 934 935 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 936 { 937 const struct inet_connection_sock *icsk = inet_csk(sk); 938 939 if (icsk->icsk_ca_ops->cwnd_event) 940 icsk->icsk_ca_ops->cwnd_event(sk, event); 941 } 942 943 /* These functions determine how the current flow behaves in respect of SACK 944 * handling. SACK is negotiated with the peer, and therefore it can vary 945 * between different flows. 946 * 947 * tcp_is_sack - SACK enabled 948 * tcp_is_reno - No SACK 949 * tcp_is_fack - FACK enabled, implies SACK enabled 950 */ 951 static inline int tcp_is_sack(const struct tcp_sock *tp) 952 { 953 return tp->rx_opt.sack_ok; 954 } 955 956 static inline bool tcp_is_reno(const struct tcp_sock *tp) 957 { 958 return !tcp_is_sack(tp); 959 } 960 961 static inline bool tcp_is_fack(const struct tcp_sock *tp) 962 { 963 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED; 964 } 965 966 static inline void tcp_enable_fack(struct tcp_sock *tp) 967 { 968 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED; 969 } 970 971 /* TCP early-retransmit (ER) is similar to but more conservative than 972 * the thin-dupack feature. Enable ER only if thin-dupack is disabled. 973 */ 974 static inline void tcp_enable_early_retrans(struct tcp_sock *tp) 975 { 976 struct net *net = sock_net((struct sock *)tp); 977 978 tp->do_early_retrans = sysctl_tcp_early_retrans && 979 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack && 980 net->ipv4.sysctl_tcp_reordering == 3; 981 } 982 983 static inline void tcp_disable_early_retrans(struct tcp_sock *tp) 984 { 985 tp->do_early_retrans = 0; 986 } 987 988 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 989 { 990 return tp->sacked_out + tp->lost_out; 991 } 992 993 /* This determines how many packets are "in the network" to the best 994 * of our knowledge. In many cases it is conservative, but where 995 * detailed information is available from the receiver (via SACK 996 * blocks etc.) we can make more aggressive calculations. 997 * 998 * Use this for decisions involving congestion control, use just 999 * tp->packets_out to determine if the send queue is empty or not. 1000 * 1001 * Read this equation as: 1002 * 1003 * "Packets sent once on transmission queue" MINUS 1004 * "Packets left network, but not honestly ACKed yet" PLUS 1005 * "Packets fast retransmitted" 1006 */ 1007 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 1008 { 1009 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 1010 } 1011 1012 #define TCP_INFINITE_SSTHRESH 0x7fffffff 1013 1014 static inline bool tcp_in_slow_start(const struct tcp_sock *tp) 1015 { 1016 return tp->snd_cwnd < tp->snd_ssthresh; 1017 } 1018 1019 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 1020 { 1021 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 1022 } 1023 1024 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 1025 { 1026 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 1027 (1 << inet_csk(sk)->icsk_ca_state); 1028 } 1029 1030 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 1031 * The exception is cwnd reduction phase, when cwnd is decreasing towards 1032 * ssthresh. 1033 */ 1034 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 1035 { 1036 const struct tcp_sock *tp = tcp_sk(sk); 1037 1038 if (tcp_in_cwnd_reduction(sk)) 1039 return tp->snd_ssthresh; 1040 else 1041 return max(tp->snd_ssthresh, 1042 ((tp->snd_cwnd >> 1) + 1043 (tp->snd_cwnd >> 2))); 1044 } 1045 1046 /* Use define here intentionally to get WARN_ON location shown at the caller */ 1047 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 1048 1049 void tcp_enter_cwr(struct sock *sk); 1050 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 1051 1052 /* The maximum number of MSS of available cwnd for which TSO defers 1053 * sending if not using sysctl_tcp_tso_win_divisor. 1054 */ 1055 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 1056 { 1057 return 3; 1058 } 1059 1060 /* Returns end sequence number of the receiver's advertised window */ 1061 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 1062 { 1063 return tp->snd_una + tp->snd_wnd; 1064 } 1065 1066 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 1067 * flexible approach. The RFC suggests cwnd should not be raised unless 1068 * it was fully used previously. And that's exactly what we do in 1069 * congestion avoidance mode. But in slow start we allow cwnd to grow 1070 * as long as the application has used half the cwnd. 1071 * Example : 1072 * cwnd is 10 (IW10), but application sends 9 frames. 1073 * We allow cwnd to reach 18 when all frames are ACKed. 1074 * This check is safe because it's as aggressive as slow start which already 1075 * risks 100% overshoot. The advantage is that we discourage application to 1076 * either send more filler packets or data to artificially blow up the cwnd 1077 * usage, and allow application-limited process to probe bw more aggressively. 1078 */ 1079 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1080 { 1081 const struct tcp_sock *tp = tcp_sk(sk); 1082 1083 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1084 if (tcp_in_slow_start(tp)) 1085 return tp->snd_cwnd < 2 * tp->max_packets_out; 1086 1087 return tp->is_cwnd_limited; 1088 } 1089 1090 /* Something is really bad, we could not queue an additional packet, 1091 * because qdisc is full or receiver sent a 0 window. 1092 * We do not want to add fuel to the fire, or abort too early, 1093 * so make sure the timer we arm now is at least 200ms in the future, 1094 * regardless of current icsk_rto value (as it could be ~2ms) 1095 */ 1096 static inline unsigned long tcp_probe0_base(const struct sock *sk) 1097 { 1098 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); 1099 } 1100 1101 /* Variant of inet_csk_rto_backoff() used for zero window probes */ 1102 static inline unsigned long tcp_probe0_when(const struct sock *sk, 1103 unsigned long max_when) 1104 { 1105 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff; 1106 1107 return (unsigned long)min_t(u64, when, max_when); 1108 } 1109 1110 static inline void tcp_check_probe_timer(struct sock *sk) 1111 { 1112 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) 1113 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1114 tcp_probe0_base(sk), TCP_RTO_MAX); 1115 } 1116 1117 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1118 { 1119 tp->snd_wl1 = seq; 1120 } 1121 1122 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1123 { 1124 tp->snd_wl1 = seq; 1125 } 1126 1127 /* 1128 * Calculate(/check) TCP checksum 1129 */ 1130 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1131 __be32 daddr, __wsum base) 1132 { 1133 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1134 } 1135 1136 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1137 { 1138 return __skb_checksum_complete(skb); 1139 } 1140 1141 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1142 { 1143 return !skb_csum_unnecessary(skb) && 1144 __tcp_checksum_complete(skb); 1145 } 1146 1147 /* Prequeue for VJ style copy to user, combined with checksumming. */ 1148 1149 static inline void tcp_prequeue_init(struct tcp_sock *tp) 1150 { 1151 tp->ucopy.task = NULL; 1152 tp->ucopy.len = 0; 1153 tp->ucopy.memory = 0; 1154 skb_queue_head_init(&tp->ucopy.prequeue); 1155 } 1156 1157 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb); 1158 1159 #undef STATE_TRACE 1160 1161 #ifdef STATE_TRACE 1162 static const char *statename[]={ 1163 "Unused","Established","Syn Sent","Syn Recv", 1164 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1165 "Close Wait","Last ACK","Listen","Closing" 1166 }; 1167 #endif 1168 void tcp_set_state(struct sock *sk, int state); 1169 1170 void tcp_done(struct sock *sk); 1171 1172 int tcp_abort(struct sock *sk, int err); 1173 1174 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1175 { 1176 rx_opt->dsack = 0; 1177 rx_opt->num_sacks = 0; 1178 } 1179 1180 u32 tcp_default_init_rwnd(u32 mss); 1181 void tcp_cwnd_restart(struct sock *sk, s32 delta); 1182 1183 static inline void tcp_slow_start_after_idle_check(struct sock *sk) 1184 { 1185 struct tcp_sock *tp = tcp_sk(sk); 1186 s32 delta; 1187 1188 if (!sysctl_tcp_slow_start_after_idle || tp->packets_out) 1189 return; 1190 delta = tcp_time_stamp - tp->lsndtime; 1191 if (delta > inet_csk(sk)->icsk_rto) 1192 tcp_cwnd_restart(sk, delta); 1193 } 1194 1195 /* Determine a window scaling and initial window to offer. */ 1196 void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd, 1197 __u32 *window_clamp, int wscale_ok, 1198 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1199 1200 static inline int tcp_win_from_space(int space) 1201 { 1202 return sysctl_tcp_adv_win_scale<=0 ? 1203 (space>>(-sysctl_tcp_adv_win_scale)) : 1204 space - (space>>sysctl_tcp_adv_win_scale); 1205 } 1206 1207 /* Note: caller must be prepared to deal with negative returns */ 1208 static inline int tcp_space(const struct sock *sk) 1209 { 1210 return tcp_win_from_space(sk->sk_rcvbuf - 1211 atomic_read(&sk->sk_rmem_alloc)); 1212 } 1213 1214 static inline int tcp_full_space(const struct sock *sk) 1215 { 1216 return tcp_win_from_space(sk->sk_rcvbuf); 1217 } 1218 1219 extern void tcp_openreq_init_rwin(struct request_sock *req, 1220 const struct sock *sk_listener, 1221 const struct dst_entry *dst); 1222 1223 void tcp_enter_memory_pressure(struct sock *sk); 1224 1225 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1226 { 1227 struct net *net = sock_net((struct sock *)tp); 1228 1229 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl; 1230 } 1231 1232 static inline int keepalive_time_when(const struct tcp_sock *tp) 1233 { 1234 struct net *net = sock_net((struct sock *)tp); 1235 1236 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time; 1237 } 1238 1239 static inline int keepalive_probes(const struct tcp_sock *tp) 1240 { 1241 struct net *net = sock_net((struct sock *)tp); 1242 1243 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes; 1244 } 1245 1246 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1247 { 1248 const struct inet_connection_sock *icsk = &tp->inet_conn; 1249 1250 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime, 1251 tcp_time_stamp - tp->rcv_tstamp); 1252 } 1253 1254 static inline int tcp_fin_time(const struct sock *sk) 1255 { 1256 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout; 1257 const int rto = inet_csk(sk)->icsk_rto; 1258 1259 if (fin_timeout < (rto << 2) - (rto >> 1)) 1260 fin_timeout = (rto << 2) - (rto >> 1); 1261 1262 return fin_timeout; 1263 } 1264 1265 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1266 int paws_win) 1267 { 1268 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1269 return true; 1270 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1271 return true; 1272 /* 1273 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1274 * then following tcp messages have valid values. Ignore 0 value, 1275 * or else 'negative' tsval might forbid us to accept their packets. 1276 */ 1277 if (!rx_opt->ts_recent) 1278 return true; 1279 return false; 1280 } 1281 1282 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1283 int rst) 1284 { 1285 if (tcp_paws_check(rx_opt, 0)) 1286 return false; 1287 1288 /* RST segments are not recommended to carry timestamp, 1289 and, if they do, it is recommended to ignore PAWS because 1290 "their cleanup function should take precedence over timestamps." 1291 Certainly, it is mistake. It is necessary to understand the reasons 1292 of this constraint to relax it: if peer reboots, clock may go 1293 out-of-sync and half-open connections will not be reset. 1294 Actually, the problem would be not existing if all 1295 the implementations followed draft about maintaining clock 1296 via reboots. Linux-2.2 DOES NOT! 1297 1298 However, we can relax time bounds for RST segments to MSL. 1299 */ 1300 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1301 return false; 1302 return true; 1303 } 1304 1305 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, 1306 int mib_idx, u32 *last_oow_ack_time); 1307 1308 static inline void tcp_mib_init(struct net *net) 1309 { 1310 /* See RFC 2012 */ 1311 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1); 1312 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1313 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1314 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1); 1315 } 1316 1317 /* from STCP */ 1318 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1319 { 1320 tp->lost_skb_hint = NULL; 1321 } 1322 1323 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1324 { 1325 tcp_clear_retrans_hints_partial(tp); 1326 tp->retransmit_skb_hint = NULL; 1327 } 1328 1329 union tcp_md5_addr { 1330 struct in_addr a4; 1331 #if IS_ENABLED(CONFIG_IPV6) 1332 struct in6_addr a6; 1333 #endif 1334 }; 1335 1336 /* - key database */ 1337 struct tcp_md5sig_key { 1338 struct hlist_node node; 1339 u8 keylen; 1340 u8 family; /* AF_INET or AF_INET6 */ 1341 union tcp_md5_addr addr; 1342 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1343 struct rcu_head rcu; 1344 }; 1345 1346 /* - sock block */ 1347 struct tcp_md5sig_info { 1348 struct hlist_head head; 1349 struct rcu_head rcu; 1350 }; 1351 1352 /* - pseudo header */ 1353 struct tcp4_pseudohdr { 1354 __be32 saddr; 1355 __be32 daddr; 1356 __u8 pad; 1357 __u8 protocol; 1358 __be16 len; 1359 }; 1360 1361 struct tcp6_pseudohdr { 1362 struct in6_addr saddr; 1363 struct in6_addr daddr; 1364 __be32 len; 1365 __be32 protocol; /* including padding */ 1366 }; 1367 1368 union tcp_md5sum_block { 1369 struct tcp4_pseudohdr ip4; 1370 #if IS_ENABLED(CONFIG_IPV6) 1371 struct tcp6_pseudohdr ip6; 1372 #endif 1373 }; 1374 1375 /* - pool: digest algorithm, hash description and scratch buffer */ 1376 struct tcp_md5sig_pool { 1377 struct ahash_request *md5_req; 1378 union tcp_md5sum_block md5_blk; 1379 }; 1380 1381 /* - functions */ 1382 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1383 const struct sock *sk, const struct sk_buff *skb); 1384 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1385 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp); 1386 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1387 int family); 1388 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 1389 const struct sock *addr_sk); 1390 1391 #ifdef CONFIG_TCP_MD5SIG 1392 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1393 const union tcp_md5_addr *addr, 1394 int family); 1395 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1396 #else 1397 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1398 const union tcp_md5_addr *addr, 1399 int family) 1400 { 1401 return NULL; 1402 } 1403 #define tcp_twsk_md5_key(twsk) NULL 1404 #endif 1405 1406 bool tcp_alloc_md5sig_pool(void); 1407 1408 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1409 static inline void tcp_put_md5sig_pool(void) 1410 { 1411 local_bh_enable(); 1412 } 1413 1414 int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *); 1415 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1416 unsigned int header_len); 1417 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1418 const struct tcp_md5sig_key *key); 1419 1420 /* From tcp_fastopen.c */ 1421 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1422 struct tcp_fastopen_cookie *cookie, int *syn_loss, 1423 unsigned long *last_syn_loss); 1424 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1425 struct tcp_fastopen_cookie *cookie, bool syn_lost, 1426 u16 try_exp); 1427 struct tcp_fastopen_request { 1428 /* Fast Open cookie. Size 0 means a cookie request */ 1429 struct tcp_fastopen_cookie cookie; 1430 struct msghdr *data; /* data in MSG_FASTOPEN */ 1431 size_t size; 1432 int copied; /* queued in tcp_connect() */ 1433 }; 1434 void tcp_free_fastopen_req(struct tcp_sock *tp); 1435 1436 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; 1437 int tcp_fastopen_reset_cipher(void *key, unsigned int len); 1438 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb); 1439 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1440 struct request_sock *req, 1441 struct tcp_fastopen_cookie *foc, 1442 struct dst_entry *dst); 1443 void tcp_fastopen_init_key_once(bool publish); 1444 #define TCP_FASTOPEN_KEY_LENGTH 16 1445 1446 /* Fastopen key context */ 1447 struct tcp_fastopen_context { 1448 struct crypto_cipher *tfm; 1449 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1450 struct rcu_head rcu; 1451 }; 1452 1453 /* write queue abstraction */ 1454 static inline void tcp_write_queue_purge(struct sock *sk) 1455 { 1456 struct sk_buff *skb; 1457 1458 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) 1459 sk_wmem_free_skb(sk, skb); 1460 sk_mem_reclaim(sk); 1461 tcp_clear_all_retrans_hints(tcp_sk(sk)); 1462 } 1463 1464 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1465 { 1466 return skb_peek(&sk->sk_write_queue); 1467 } 1468 1469 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1470 { 1471 return skb_peek_tail(&sk->sk_write_queue); 1472 } 1473 1474 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk, 1475 const struct sk_buff *skb) 1476 { 1477 return skb_queue_next(&sk->sk_write_queue, skb); 1478 } 1479 1480 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk, 1481 const struct sk_buff *skb) 1482 { 1483 return skb_queue_prev(&sk->sk_write_queue, skb); 1484 } 1485 1486 #define tcp_for_write_queue(skb, sk) \ 1487 skb_queue_walk(&(sk)->sk_write_queue, skb) 1488 1489 #define tcp_for_write_queue_from(skb, sk) \ 1490 skb_queue_walk_from(&(sk)->sk_write_queue, skb) 1491 1492 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1493 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1494 1495 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1496 { 1497 return sk->sk_send_head; 1498 } 1499 1500 static inline bool tcp_skb_is_last(const struct sock *sk, 1501 const struct sk_buff *skb) 1502 { 1503 return skb_queue_is_last(&sk->sk_write_queue, skb); 1504 } 1505 1506 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb) 1507 { 1508 if (tcp_skb_is_last(sk, skb)) 1509 sk->sk_send_head = NULL; 1510 else 1511 sk->sk_send_head = tcp_write_queue_next(sk, skb); 1512 } 1513 1514 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1515 { 1516 if (sk->sk_send_head == skb_unlinked) 1517 sk->sk_send_head = NULL; 1518 } 1519 1520 static inline void tcp_init_send_head(struct sock *sk) 1521 { 1522 sk->sk_send_head = NULL; 1523 } 1524 1525 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1526 { 1527 __skb_queue_tail(&sk->sk_write_queue, skb); 1528 } 1529 1530 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1531 { 1532 __tcp_add_write_queue_tail(sk, skb); 1533 1534 /* Queue it, remembering where we must start sending. */ 1535 if (sk->sk_send_head == NULL) { 1536 sk->sk_send_head = skb; 1537 1538 if (tcp_sk(sk)->highest_sack == NULL) 1539 tcp_sk(sk)->highest_sack = skb; 1540 } 1541 } 1542 1543 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb) 1544 { 1545 __skb_queue_head(&sk->sk_write_queue, skb); 1546 } 1547 1548 /* Insert buff after skb on the write queue of sk. */ 1549 static inline void tcp_insert_write_queue_after(struct sk_buff *skb, 1550 struct sk_buff *buff, 1551 struct sock *sk) 1552 { 1553 __skb_queue_after(&sk->sk_write_queue, skb, buff); 1554 } 1555 1556 /* Insert new before skb on the write queue of sk. */ 1557 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1558 struct sk_buff *skb, 1559 struct sock *sk) 1560 { 1561 __skb_queue_before(&sk->sk_write_queue, skb, new); 1562 1563 if (sk->sk_send_head == skb) 1564 sk->sk_send_head = new; 1565 } 1566 1567 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1568 { 1569 __skb_unlink(skb, &sk->sk_write_queue); 1570 } 1571 1572 static inline bool tcp_write_queue_empty(struct sock *sk) 1573 { 1574 return skb_queue_empty(&sk->sk_write_queue); 1575 } 1576 1577 static inline void tcp_push_pending_frames(struct sock *sk) 1578 { 1579 if (tcp_send_head(sk)) { 1580 struct tcp_sock *tp = tcp_sk(sk); 1581 1582 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1583 } 1584 } 1585 1586 /* Start sequence of the skb just after the highest skb with SACKed 1587 * bit, valid only if sacked_out > 0 or when the caller has ensured 1588 * validity by itself. 1589 */ 1590 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1591 { 1592 if (!tp->sacked_out) 1593 return tp->snd_una; 1594 1595 if (tp->highest_sack == NULL) 1596 return tp->snd_nxt; 1597 1598 return TCP_SKB_CB(tp->highest_sack)->seq; 1599 } 1600 1601 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1602 { 1603 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL : 1604 tcp_write_queue_next(sk, skb); 1605 } 1606 1607 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1608 { 1609 return tcp_sk(sk)->highest_sack; 1610 } 1611 1612 static inline void tcp_highest_sack_reset(struct sock *sk) 1613 { 1614 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk); 1615 } 1616 1617 /* Called when old skb is about to be deleted (to be combined with new skb) */ 1618 static inline void tcp_highest_sack_combine(struct sock *sk, 1619 struct sk_buff *old, 1620 struct sk_buff *new) 1621 { 1622 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack)) 1623 tcp_sk(sk)->highest_sack = new; 1624 } 1625 1626 /* This helper checks if socket has IP_TRANSPARENT set */ 1627 static inline bool inet_sk_transparent(const struct sock *sk) 1628 { 1629 switch (sk->sk_state) { 1630 case TCP_TIME_WAIT: 1631 return inet_twsk(sk)->tw_transparent; 1632 case TCP_NEW_SYN_RECV: 1633 return inet_rsk(inet_reqsk(sk))->no_srccheck; 1634 } 1635 return inet_sk(sk)->transparent; 1636 } 1637 1638 /* Determines whether this is a thin stream (which may suffer from 1639 * increased latency). Used to trigger latency-reducing mechanisms. 1640 */ 1641 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1642 { 1643 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1644 } 1645 1646 /* /proc */ 1647 enum tcp_seq_states { 1648 TCP_SEQ_STATE_LISTENING, 1649 TCP_SEQ_STATE_ESTABLISHED, 1650 }; 1651 1652 int tcp_seq_open(struct inode *inode, struct file *file); 1653 1654 struct tcp_seq_afinfo { 1655 char *name; 1656 sa_family_t family; 1657 const struct file_operations *seq_fops; 1658 struct seq_operations seq_ops; 1659 }; 1660 1661 struct tcp_iter_state { 1662 struct seq_net_private p; 1663 sa_family_t family; 1664 enum tcp_seq_states state; 1665 struct sock *syn_wait_sk; 1666 int bucket, offset, sbucket, num; 1667 loff_t last_pos; 1668 }; 1669 1670 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1671 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1672 1673 extern struct request_sock_ops tcp_request_sock_ops; 1674 extern struct request_sock_ops tcp6_request_sock_ops; 1675 1676 void tcp_v4_destroy_sock(struct sock *sk); 1677 1678 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 1679 netdev_features_t features); 1680 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb); 1681 int tcp_gro_complete(struct sk_buff *skb); 1682 1683 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 1684 1685 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 1686 { 1687 struct net *net = sock_net((struct sock *)tp); 1688 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat; 1689 } 1690 1691 static inline bool tcp_stream_memory_free(const struct sock *sk) 1692 { 1693 const struct tcp_sock *tp = tcp_sk(sk); 1694 u32 notsent_bytes = tp->write_seq - tp->snd_nxt; 1695 1696 return notsent_bytes < tcp_notsent_lowat(tp); 1697 } 1698 1699 #ifdef CONFIG_PROC_FS 1700 int tcp4_proc_init(void); 1701 void tcp4_proc_exit(void); 1702 #endif 1703 1704 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req); 1705 int tcp_conn_request(struct request_sock_ops *rsk_ops, 1706 const struct tcp_request_sock_ops *af_ops, 1707 struct sock *sk, struct sk_buff *skb); 1708 1709 /* TCP af-specific functions */ 1710 struct tcp_sock_af_ops { 1711 #ifdef CONFIG_TCP_MD5SIG 1712 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk, 1713 const struct sock *addr_sk); 1714 int (*calc_md5_hash)(char *location, 1715 const struct tcp_md5sig_key *md5, 1716 const struct sock *sk, 1717 const struct sk_buff *skb); 1718 int (*md5_parse)(struct sock *sk, 1719 char __user *optval, 1720 int optlen); 1721 #endif 1722 }; 1723 1724 struct tcp_request_sock_ops { 1725 u16 mss_clamp; 1726 #ifdef CONFIG_TCP_MD5SIG 1727 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk, 1728 const struct sock *addr_sk); 1729 int (*calc_md5_hash) (char *location, 1730 const struct tcp_md5sig_key *md5, 1731 const struct sock *sk, 1732 const struct sk_buff *skb); 1733 #endif 1734 void (*init_req)(struct request_sock *req, 1735 const struct sock *sk_listener, 1736 struct sk_buff *skb); 1737 #ifdef CONFIG_SYN_COOKIES 1738 __u32 (*cookie_init_seq)(const struct sk_buff *skb, 1739 __u16 *mss); 1740 #endif 1741 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl, 1742 const struct request_sock *req, 1743 bool *strict); 1744 __u32 (*init_seq)(const struct sk_buff *skb); 1745 int (*send_synack)(const struct sock *sk, struct dst_entry *dst, 1746 struct flowi *fl, struct request_sock *req, 1747 struct tcp_fastopen_cookie *foc, 1748 enum tcp_synack_type synack_type); 1749 }; 1750 1751 #ifdef CONFIG_SYN_COOKIES 1752 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1753 const struct sock *sk, struct sk_buff *skb, 1754 __u16 *mss) 1755 { 1756 tcp_synq_overflow(sk); 1757 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); 1758 return ops->cookie_init_seq(skb, mss); 1759 } 1760 #else 1761 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1762 const struct sock *sk, struct sk_buff *skb, 1763 __u16 *mss) 1764 { 1765 return 0; 1766 } 1767 #endif 1768 1769 int tcpv4_offload_init(void); 1770 1771 void tcp_v4_init(void); 1772 void tcp_init(void); 1773 1774 /* tcp_recovery.c */ 1775 1776 /* Flags to enable various loss recovery features. See below */ 1777 extern int sysctl_tcp_recovery; 1778 1779 /* Use TCP RACK to detect (some) tail and retransmit losses */ 1780 #define TCP_RACK_LOST_RETRANS 0x1 1781 1782 extern int tcp_rack_mark_lost(struct sock *sk); 1783 1784 extern void tcp_rack_advance(struct tcp_sock *tp, 1785 const struct skb_mstamp *xmit_time, u8 sacked); 1786 1787 /* 1788 * Save and compile IPv4 options, return a pointer to it 1789 */ 1790 static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb) 1791 { 1792 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; 1793 struct ip_options_rcu *dopt = NULL; 1794 1795 if (opt->optlen) { 1796 int opt_size = sizeof(*dopt) + opt->optlen; 1797 1798 dopt = kmalloc(opt_size, GFP_ATOMIC); 1799 if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) { 1800 kfree(dopt); 1801 dopt = NULL; 1802 } 1803 } 1804 return dopt; 1805 } 1806 1807 /* locally generated TCP pure ACKs have skb->truesize == 2 1808 * (check tcp_send_ack() in net/ipv4/tcp_output.c ) 1809 * This is much faster than dissecting the packet to find out. 1810 * (Think of GRE encapsulations, IPv4, IPv6, ...) 1811 */ 1812 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb) 1813 { 1814 return skb->truesize == 2; 1815 } 1816 1817 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb) 1818 { 1819 skb->truesize = 2; 1820 } 1821 1822 static inline int tcp_inq(struct sock *sk) 1823 { 1824 struct tcp_sock *tp = tcp_sk(sk); 1825 int answ; 1826 1827 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { 1828 answ = 0; 1829 } else if (sock_flag(sk, SOCK_URGINLINE) || 1830 !tp->urg_data || 1831 before(tp->urg_seq, tp->copied_seq) || 1832 !before(tp->urg_seq, tp->rcv_nxt)) { 1833 1834 answ = tp->rcv_nxt - tp->copied_seq; 1835 1836 /* Subtract 1, if FIN was received */ 1837 if (answ && sock_flag(sk, SOCK_DONE)) 1838 answ--; 1839 } else { 1840 answ = tp->urg_seq - tp->copied_seq; 1841 } 1842 1843 return answ; 1844 } 1845 1846 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb) 1847 { 1848 u16 segs_in; 1849 1850 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs); 1851 tp->segs_in += segs_in; 1852 if (skb->len > tcp_hdrlen(skb)) 1853 tp->data_segs_in += segs_in; 1854 } 1855 1856 /* 1857 * TCP listen path runs lockless. 1858 * We forced "struct sock" to be const qualified to make sure 1859 * we don't modify one of its field by mistake. 1860 * Here, we increment sk_drops which is an atomic_t, so we can safely 1861 * make sock writable again. 1862 */ 1863 static inline void tcp_listendrop(const struct sock *sk) 1864 { 1865 atomic_inc(&((struct sock *)sk)->sk_drops); 1866 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 1867 } 1868 1869 #endif /* _TCP_H */ 1870