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_BH(net, field) SNMP_INC_STATS_BH((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_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val) 338 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 339 340 void tcp_tasklet_init(void); 341 342 void tcp_v4_err(struct sk_buff *skb, u32); 343 344 void tcp_shutdown(struct sock *sk, int how); 345 346 void tcp_v4_early_demux(struct sk_buff *skb); 347 int tcp_v4_rcv(struct sk_buff *skb); 348 349 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 350 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size); 351 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, 352 int flags); 353 void tcp_release_cb(struct sock *sk); 354 void tcp_wfree(struct sk_buff *skb); 355 void tcp_write_timer_handler(struct sock *sk); 356 void tcp_delack_timer_handler(struct sock *sk); 357 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 358 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb); 359 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 360 const struct tcphdr *th, unsigned int len); 361 void tcp_rcv_space_adjust(struct sock *sk); 362 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 363 void tcp_twsk_destructor(struct sock *sk); 364 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 365 struct pipe_inode_info *pipe, size_t len, 366 unsigned int flags); 367 368 static inline void tcp_dec_quickack_mode(struct sock *sk, 369 const unsigned int pkts) 370 { 371 struct inet_connection_sock *icsk = inet_csk(sk); 372 373 if (icsk->icsk_ack.quick) { 374 if (pkts >= icsk->icsk_ack.quick) { 375 icsk->icsk_ack.quick = 0; 376 /* Leaving quickack mode we deflate ATO. */ 377 icsk->icsk_ack.ato = TCP_ATO_MIN; 378 } else 379 icsk->icsk_ack.quick -= pkts; 380 } 381 } 382 383 #define TCP_ECN_OK 1 384 #define TCP_ECN_QUEUE_CWR 2 385 #define TCP_ECN_DEMAND_CWR 4 386 #define TCP_ECN_SEEN 8 387 388 enum tcp_tw_status { 389 TCP_TW_SUCCESS = 0, 390 TCP_TW_RST = 1, 391 TCP_TW_ACK = 2, 392 TCP_TW_SYN = 3 393 }; 394 395 396 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 397 struct sk_buff *skb, 398 const struct tcphdr *th); 399 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 400 struct request_sock *req, bool fastopen); 401 int tcp_child_process(struct sock *parent, struct sock *child, 402 struct sk_buff *skb); 403 void tcp_enter_loss(struct sock *sk); 404 void tcp_clear_retrans(struct tcp_sock *tp); 405 void tcp_update_metrics(struct sock *sk); 406 void tcp_init_metrics(struct sock *sk); 407 void tcp_metrics_init(void); 408 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, 409 bool paws_check, bool timestamps); 410 bool tcp_remember_stamp(struct sock *sk); 411 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw); 412 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst); 413 void tcp_disable_fack(struct tcp_sock *tp); 414 void tcp_close(struct sock *sk, long timeout); 415 void tcp_init_sock(struct sock *sk); 416 unsigned int tcp_poll(struct file *file, struct socket *sock, 417 struct poll_table_struct *wait); 418 int tcp_getsockopt(struct sock *sk, int level, int optname, 419 char __user *optval, int __user *optlen); 420 int tcp_setsockopt(struct sock *sk, int level, int optname, 421 char __user *optval, unsigned int optlen); 422 int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 423 char __user *optval, int __user *optlen); 424 int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 425 char __user *optval, unsigned int optlen); 426 void tcp_set_keepalive(struct sock *sk, int val); 427 void tcp_syn_ack_timeout(const struct request_sock *req); 428 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, 429 int flags, int *addr_len); 430 void tcp_parse_options(const struct sk_buff *skb, 431 struct tcp_options_received *opt_rx, 432 int estab, struct tcp_fastopen_cookie *foc); 433 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); 434 435 /* 436 * TCP v4 functions exported for the inet6 API 437 */ 438 439 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 440 void tcp_v4_mtu_reduced(struct sock *sk); 441 void tcp_req_err(struct sock *sk, u32 seq, bool abort); 442 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 443 struct sock *tcp_create_openreq_child(const struct sock *sk, 444 struct request_sock *req, 445 struct sk_buff *skb); 446 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst); 447 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 448 struct request_sock *req, 449 struct dst_entry *dst, 450 struct request_sock *req_unhash, 451 bool *own_req); 452 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 453 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); 454 int tcp_connect(struct sock *sk); 455 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 456 struct request_sock *req, 457 struct tcp_fastopen_cookie *foc, 458 bool attach_req); 459 int tcp_disconnect(struct sock *sk, int flags); 460 461 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 462 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 463 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); 464 465 /* From syncookies.c */ 466 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, 467 struct request_sock *req, 468 struct dst_entry *dst); 469 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th, 470 u32 cookie); 471 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb); 472 #ifdef CONFIG_SYN_COOKIES 473 474 /* Syncookies use a monotonic timer which increments every 60 seconds. 475 * This counter is used both as a hash input and partially encoded into 476 * the cookie value. A cookie is only validated further if the delta 477 * between the current counter value and the encoded one is less than this, 478 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if 479 * the counter advances immediately after a cookie is generated). 480 */ 481 #define MAX_SYNCOOKIE_AGE 2 482 #define TCP_SYNCOOKIE_PERIOD (60 * HZ) 483 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD) 484 485 /* syncookies: remember time of last synqueue overflow 486 * But do not dirty this field too often (once per second is enough) 487 * It is racy as we do not hold a lock, but race is very minor. 488 */ 489 static inline void tcp_synq_overflow(const struct sock *sk) 490 { 491 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 492 unsigned long now = jiffies; 493 494 if (time_after(now, last_overflow + HZ)) 495 tcp_sk(sk)->rx_opt.ts_recent_stamp = now; 496 } 497 498 /* syncookies: no recent synqueue overflow on this listening socket? */ 499 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 500 { 501 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 502 503 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID); 504 } 505 506 static inline u32 tcp_cookie_time(void) 507 { 508 u64 val = get_jiffies_64(); 509 510 do_div(val, TCP_SYNCOOKIE_PERIOD); 511 return val; 512 } 513 514 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, 515 u16 *mssp); 516 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss); 517 __u32 cookie_init_timestamp(struct request_sock *req); 518 bool cookie_timestamp_decode(struct tcp_options_received *opt); 519 bool cookie_ecn_ok(const struct tcp_options_received *opt, 520 const struct net *net, const struct dst_entry *dst); 521 522 /* From net/ipv6/syncookies.c */ 523 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th, 524 u32 cookie); 525 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 526 527 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph, 528 const struct tcphdr *th, u16 *mssp); 529 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss); 530 #endif 531 /* tcp_output.c */ 532 533 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 534 int nonagle); 535 bool tcp_may_send_now(struct sock *sk); 536 int __tcp_retransmit_skb(struct sock *, struct sk_buff *); 537 int tcp_retransmit_skb(struct sock *, struct sk_buff *); 538 void tcp_retransmit_timer(struct sock *sk); 539 void tcp_xmit_retransmit_queue(struct sock *); 540 void tcp_simple_retransmit(struct sock *); 541 int tcp_trim_head(struct sock *, struct sk_buff *, u32); 542 int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t); 543 544 void tcp_send_probe0(struct sock *); 545 void tcp_send_partial(struct sock *); 546 int tcp_write_wakeup(struct sock *, int mib); 547 void tcp_send_fin(struct sock *sk); 548 void tcp_send_active_reset(struct sock *sk, gfp_t priority); 549 int tcp_send_synack(struct sock *); 550 void tcp_push_one(struct sock *, unsigned int mss_now); 551 void tcp_send_ack(struct sock *sk); 552 void tcp_send_delayed_ack(struct sock *sk); 553 void tcp_send_loss_probe(struct sock *sk); 554 bool tcp_schedule_loss_probe(struct sock *sk); 555 void tcp_skb_collapse_tstamp(struct sk_buff *skb, 556 const struct sk_buff *next_skb); 557 558 /* tcp_input.c */ 559 void tcp_resume_early_retransmit(struct sock *sk); 560 void tcp_rearm_rto(struct sock *sk); 561 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req); 562 void tcp_reset(struct sock *sk); 563 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb); 564 void tcp_fin(struct sock *sk); 565 566 /* tcp_timer.c */ 567 void tcp_init_xmit_timers(struct sock *); 568 static inline void tcp_clear_xmit_timers(struct sock *sk) 569 { 570 inet_csk_clear_xmit_timers(sk); 571 } 572 573 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 574 unsigned int tcp_current_mss(struct sock *sk); 575 576 /* Bound MSS / TSO packet size with the half of the window */ 577 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 578 { 579 int cutoff; 580 581 /* When peer uses tiny windows, there is no use in packetizing 582 * to sub-MSS pieces for the sake of SWS or making sure there 583 * are enough packets in the pipe for fast recovery. 584 * 585 * On the other hand, for extremely large MSS devices, handling 586 * smaller than MSS windows in this way does make sense. 587 */ 588 if (tp->max_window >= 512) 589 cutoff = (tp->max_window >> 1); 590 else 591 cutoff = tp->max_window; 592 593 if (cutoff && pktsize > cutoff) 594 return max_t(int, cutoff, 68U - tp->tcp_header_len); 595 else 596 return pktsize; 597 } 598 599 /* tcp.c */ 600 void tcp_get_info(struct sock *, struct tcp_info *); 601 602 /* Read 'sendfile()'-style from a TCP socket */ 603 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *, 604 unsigned int, size_t); 605 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 606 sk_read_actor_t recv_actor); 607 608 void tcp_initialize_rcv_mss(struct sock *sk); 609 610 int tcp_mtu_to_mss(struct sock *sk, int pmtu); 611 int tcp_mss_to_mtu(struct sock *sk, int mss); 612 void tcp_mtup_init(struct sock *sk); 613 void tcp_init_buffer_space(struct sock *sk); 614 615 static inline void tcp_bound_rto(const struct sock *sk) 616 { 617 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 618 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 619 } 620 621 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 622 { 623 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us); 624 } 625 626 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 627 { 628 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 629 ntohl(TCP_FLAG_ACK) | 630 snd_wnd); 631 } 632 633 static inline void tcp_fast_path_on(struct tcp_sock *tp) 634 { 635 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 636 } 637 638 static inline void tcp_fast_path_check(struct sock *sk) 639 { 640 struct tcp_sock *tp = tcp_sk(sk); 641 642 if (skb_queue_empty(&tp->out_of_order_queue) && 643 tp->rcv_wnd && 644 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 645 !tp->urg_data) 646 tcp_fast_path_on(tp); 647 } 648 649 /* Compute the actual rto_min value */ 650 static inline u32 tcp_rto_min(struct sock *sk) 651 { 652 const struct dst_entry *dst = __sk_dst_get(sk); 653 u32 rto_min = TCP_RTO_MIN; 654 655 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 656 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 657 return rto_min; 658 } 659 660 static inline u32 tcp_rto_min_us(struct sock *sk) 661 { 662 return jiffies_to_usecs(tcp_rto_min(sk)); 663 } 664 665 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst) 666 { 667 return dst_metric_locked(dst, RTAX_CC_ALGO); 668 } 669 670 /* Minimum RTT in usec. ~0 means not available. */ 671 static inline u32 tcp_min_rtt(const struct tcp_sock *tp) 672 { 673 return tp->rtt_min[0].rtt; 674 } 675 676 /* Compute the actual receive window we are currently advertising. 677 * Rcv_nxt can be after the window if our peer push more data 678 * than the offered window. 679 */ 680 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 681 { 682 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 683 684 if (win < 0) 685 win = 0; 686 return (u32) win; 687 } 688 689 /* Choose a new window, without checks for shrinking, and without 690 * scaling applied to the result. The caller does these things 691 * if necessary. This is a "raw" window selection. 692 */ 693 u32 __tcp_select_window(struct sock *sk); 694 695 void tcp_send_window_probe(struct sock *sk); 696 697 /* TCP timestamps are only 32-bits, this causes a slight 698 * complication on 64-bit systems since we store a snapshot 699 * of jiffies in the buffer control blocks below. We decided 700 * to use only the low 32-bits of jiffies and hide the ugly 701 * casts with the following macro. 702 */ 703 #define tcp_time_stamp ((__u32)(jiffies)) 704 705 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) 706 { 707 return skb->skb_mstamp.stamp_jiffies; 708 } 709 710 711 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 712 713 #define TCPHDR_FIN 0x01 714 #define TCPHDR_SYN 0x02 715 #define TCPHDR_RST 0x04 716 #define TCPHDR_PSH 0x08 717 #define TCPHDR_ACK 0x10 718 #define TCPHDR_URG 0x20 719 #define TCPHDR_ECE 0x40 720 #define TCPHDR_CWR 0x80 721 722 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) 723 724 /* This is what the send packet queuing engine uses to pass 725 * TCP per-packet control information to the transmission code. 726 * We also store the host-order sequence numbers in here too. 727 * This is 44 bytes if IPV6 is enabled. 728 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 729 */ 730 struct tcp_skb_cb { 731 __u32 seq; /* Starting sequence number */ 732 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 733 union { 734 /* Note : tcp_tw_isn is used in input path only 735 * (isn chosen by tcp_timewait_state_process()) 736 * 737 * tcp_gso_segs/size are used in write queue only, 738 * cf tcp_skb_pcount()/tcp_skb_mss() 739 */ 740 __u32 tcp_tw_isn; 741 struct { 742 u16 tcp_gso_segs; 743 u16 tcp_gso_size; 744 }; 745 }; 746 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 747 748 __u8 sacked; /* State flags for SACK/FACK. */ 749 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 750 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 751 #define TCPCB_LOST 0x04 /* SKB is lost */ 752 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 753 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */ 754 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 755 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \ 756 TCPCB_REPAIRED) 757 758 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 759 /* 1 byte hole */ 760 __u32 ack_seq; /* Sequence number ACK'd */ 761 union { 762 struct inet_skb_parm h4; 763 #if IS_ENABLED(CONFIG_IPV6) 764 struct inet6_skb_parm h6; 765 #endif 766 } header; /* For incoming frames */ 767 }; 768 769 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 770 771 772 #if IS_ENABLED(CONFIG_IPV6) 773 /* This is the variant of inet6_iif() that must be used by TCP, 774 * as TCP moves IP6CB into a different location in skb->cb[] 775 */ 776 static inline int tcp_v6_iif(const struct sk_buff *skb) 777 { 778 return TCP_SKB_CB(skb)->header.h6.iif; 779 } 780 #endif 781 782 /* Due to TSO, an SKB can be composed of multiple actual 783 * packets. To keep these tracked properly, we use this. 784 */ 785 static inline int tcp_skb_pcount(const struct sk_buff *skb) 786 { 787 return TCP_SKB_CB(skb)->tcp_gso_segs; 788 } 789 790 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 791 { 792 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 793 } 794 795 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 796 { 797 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 798 } 799 800 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ 801 static inline int tcp_skb_mss(const struct sk_buff *skb) 802 { 803 return TCP_SKB_CB(skb)->tcp_gso_size; 804 } 805 806 /* Events passed to congestion control interface */ 807 enum tcp_ca_event { 808 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 809 CA_EVENT_CWND_RESTART, /* congestion window restart */ 810 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 811 CA_EVENT_LOSS, /* loss timeout */ 812 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 813 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 814 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */ 815 CA_EVENT_NON_DELAYED_ACK, 816 }; 817 818 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 819 enum tcp_ca_ack_event_flags { 820 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 821 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 822 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 823 }; 824 825 /* 826 * Interface for adding new TCP congestion control handlers 827 */ 828 #define TCP_CA_NAME_MAX 16 829 #define TCP_CA_MAX 128 830 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 831 832 #define TCP_CA_UNSPEC 0 833 834 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 835 #define TCP_CONG_NON_RESTRICTED 0x1 836 /* Requires ECN/ECT set on all packets */ 837 #define TCP_CONG_NEEDS_ECN 0x2 838 839 union tcp_cc_info; 840 841 struct tcp_congestion_ops { 842 struct list_head list; 843 u32 key; 844 u32 flags; 845 846 /* initialize private data (optional) */ 847 void (*init)(struct sock *sk); 848 /* cleanup private data (optional) */ 849 void (*release)(struct sock *sk); 850 851 /* return slow start threshold (required) */ 852 u32 (*ssthresh)(struct sock *sk); 853 /* do new cwnd calculation (required) */ 854 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 855 /* call before changing ca_state (optional) */ 856 void (*set_state)(struct sock *sk, u8 new_state); 857 /* call when cwnd event occurs (optional) */ 858 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 859 /* call when ack arrives (optional) */ 860 void (*in_ack_event)(struct sock *sk, u32 flags); 861 /* new value of cwnd after loss (optional) */ 862 u32 (*undo_cwnd)(struct sock *sk); 863 /* hook for packet ack accounting (optional) */ 864 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us); 865 /* get info for inet_diag (optional) */ 866 size_t (*get_info)(struct sock *sk, u32 ext, int *attr, 867 union tcp_cc_info *info); 868 869 char name[TCP_CA_NAME_MAX]; 870 struct module *owner; 871 }; 872 873 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 874 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 875 876 void tcp_assign_congestion_control(struct sock *sk); 877 void tcp_init_congestion_control(struct sock *sk); 878 void tcp_cleanup_congestion_control(struct sock *sk); 879 int tcp_set_default_congestion_control(const char *name); 880 void tcp_get_default_congestion_control(char *name); 881 void tcp_get_available_congestion_control(char *buf, size_t len); 882 void tcp_get_allowed_congestion_control(char *buf, size_t len); 883 int tcp_set_allowed_congestion_control(char *allowed); 884 int tcp_set_congestion_control(struct sock *sk, const char *name); 885 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); 886 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); 887 888 u32 tcp_reno_ssthresh(struct sock *sk); 889 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 890 extern struct tcp_congestion_ops tcp_reno; 891 892 struct tcp_congestion_ops *tcp_ca_find_key(u32 key); 893 u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca); 894 #ifdef CONFIG_INET 895 char *tcp_ca_get_name_by_key(u32 key, char *buffer); 896 #else 897 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) 898 { 899 return NULL; 900 } 901 #endif 902 903 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 904 { 905 const struct inet_connection_sock *icsk = inet_csk(sk); 906 907 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 908 } 909 910 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 911 { 912 struct inet_connection_sock *icsk = inet_csk(sk); 913 914 if (icsk->icsk_ca_ops->set_state) 915 icsk->icsk_ca_ops->set_state(sk, ca_state); 916 icsk->icsk_ca_state = ca_state; 917 } 918 919 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 920 { 921 const struct inet_connection_sock *icsk = inet_csk(sk); 922 923 if (icsk->icsk_ca_ops->cwnd_event) 924 icsk->icsk_ca_ops->cwnd_event(sk, event); 925 } 926 927 /* These functions determine how the current flow behaves in respect of SACK 928 * handling. SACK is negotiated with the peer, and therefore it can vary 929 * between different flows. 930 * 931 * tcp_is_sack - SACK enabled 932 * tcp_is_reno - No SACK 933 * tcp_is_fack - FACK enabled, implies SACK enabled 934 */ 935 static inline int tcp_is_sack(const struct tcp_sock *tp) 936 { 937 return tp->rx_opt.sack_ok; 938 } 939 940 static inline bool tcp_is_reno(const struct tcp_sock *tp) 941 { 942 return !tcp_is_sack(tp); 943 } 944 945 static inline bool tcp_is_fack(const struct tcp_sock *tp) 946 { 947 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED; 948 } 949 950 static inline void tcp_enable_fack(struct tcp_sock *tp) 951 { 952 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED; 953 } 954 955 /* TCP early-retransmit (ER) is similar to but more conservative than 956 * the thin-dupack feature. Enable ER only if thin-dupack is disabled. 957 */ 958 static inline void tcp_enable_early_retrans(struct tcp_sock *tp) 959 { 960 struct net *net = sock_net((struct sock *)tp); 961 962 tp->do_early_retrans = sysctl_tcp_early_retrans && 963 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack && 964 net->ipv4.sysctl_tcp_reordering == 3; 965 } 966 967 static inline void tcp_disable_early_retrans(struct tcp_sock *tp) 968 { 969 tp->do_early_retrans = 0; 970 } 971 972 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 973 { 974 return tp->sacked_out + tp->lost_out; 975 } 976 977 /* This determines how many packets are "in the network" to the best 978 * of our knowledge. In many cases it is conservative, but where 979 * detailed information is available from the receiver (via SACK 980 * blocks etc.) we can make more aggressive calculations. 981 * 982 * Use this for decisions involving congestion control, use just 983 * tp->packets_out to determine if the send queue is empty or not. 984 * 985 * Read this equation as: 986 * 987 * "Packets sent once on transmission queue" MINUS 988 * "Packets left network, but not honestly ACKed yet" PLUS 989 * "Packets fast retransmitted" 990 */ 991 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 992 { 993 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 994 } 995 996 #define TCP_INFINITE_SSTHRESH 0x7fffffff 997 998 static inline bool tcp_in_slow_start(const struct tcp_sock *tp) 999 { 1000 return tp->snd_cwnd < tp->snd_ssthresh; 1001 } 1002 1003 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 1004 { 1005 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 1006 } 1007 1008 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 1009 { 1010 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 1011 (1 << inet_csk(sk)->icsk_ca_state); 1012 } 1013 1014 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 1015 * The exception is cwnd reduction phase, when cwnd is decreasing towards 1016 * ssthresh. 1017 */ 1018 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 1019 { 1020 const struct tcp_sock *tp = tcp_sk(sk); 1021 1022 if (tcp_in_cwnd_reduction(sk)) 1023 return tp->snd_ssthresh; 1024 else 1025 return max(tp->snd_ssthresh, 1026 ((tp->snd_cwnd >> 1) + 1027 (tp->snd_cwnd >> 2))); 1028 } 1029 1030 /* Use define here intentionally to get WARN_ON location shown at the caller */ 1031 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 1032 1033 void tcp_enter_cwr(struct sock *sk); 1034 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 1035 1036 /* The maximum number of MSS of available cwnd for which TSO defers 1037 * sending if not using sysctl_tcp_tso_win_divisor. 1038 */ 1039 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 1040 { 1041 return 3; 1042 } 1043 1044 /* Slow start with delack produces 3 packets of burst, so that 1045 * it is safe "de facto". This will be the default - same as 1046 * the default reordering threshold - but if reordering increases, 1047 * we must be able to allow cwnd to burst at least this much in order 1048 * to not pull it back when holes are filled. 1049 */ 1050 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp) 1051 { 1052 return tp->reordering; 1053 } 1054 1055 /* Returns end sequence number of the receiver's advertised window */ 1056 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 1057 { 1058 return tp->snd_una + tp->snd_wnd; 1059 } 1060 1061 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 1062 * flexible approach. The RFC suggests cwnd should not be raised unless 1063 * it was fully used previously. And that's exactly what we do in 1064 * congestion avoidance mode. But in slow start we allow cwnd to grow 1065 * as long as the application has used half the cwnd. 1066 * Example : 1067 * cwnd is 10 (IW10), but application sends 9 frames. 1068 * We allow cwnd to reach 18 when all frames are ACKed. 1069 * This check is safe because it's as aggressive as slow start which already 1070 * risks 100% overshoot. The advantage is that we discourage application to 1071 * either send more filler packets or data to artificially blow up the cwnd 1072 * usage, and allow application-limited process to probe bw more aggressively. 1073 */ 1074 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1075 { 1076 const struct tcp_sock *tp = tcp_sk(sk); 1077 1078 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1079 if (tcp_in_slow_start(tp)) 1080 return tp->snd_cwnd < 2 * tp->max_packets_out; 1081 1082 return tp->is_cwnd_limited; 1083 } 1084 1085 /* Something is really bad, we could not queue an additional packet, 1086 * because qdisc is full or receiver sent a 0 window. 1087 * We do not want to add fuel to the fire, or abort too early, 1088 * so make sure the timer we arm now is at least 200ms in the future, 1089 * regardless of current icsk_rto value (as it could be ~2ms) 1090 */ 1091 static inline unsigned long tcp_probe0_base(const struct sock *sk) 1092 { 1093 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); 1094 } 1095 1096 /* Variant of inet_csk_rto_backoff() used for zero window probes */ 1097 static inline unsigned long tcp_probe0_when(const struct sock *sk, 1098 unsigned long max_when) 1099 { 1100 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff; 1101 1102 return (unsigned long)min_t(u64, when, max_when); 1103 } 1104 1105 static inline void tcp_check_probe_timer(struct sock *sk) 1106 { 1107 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) 1108 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1109 tcp_probe0_base(sk), TCP_RTO_MAX); 1110 } 1111 1112 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1113 { 1114 tp->snd_wl1 = seq; 1115 } 1116 1117 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1118 { 1119 tp->snd_wl1 = seq; 1120 } 1121 1122 /* 1123 * Calculate(/check) TCP checksum 1124 */ 1125 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1126 __be32 daddr, __wsum base) 1127 { 1128 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1129 } 1130 1131 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1132 { 1133 return __skb_checksum_complete(skb); 1134 } 1135 1136 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1137 { 1138 return !skb_csum_unnecessary(skb) && 1139 __tcp_checksum_complete(skb); 1140 } 1141 1142 /* Prequeue for VJ style copy to user, combined with checksumming. */ 1143 1144 static inline void tcp_prequeue_init(struct tcp_sock *tp) 1145 { 1146 tp->ucopy.task = NULL; 1147 tp->ucopy.len = 0; 1148 tp->ucopy.memory = 0; 1149 skb_queue_head_init(&tp->ucopy.prequeue); 1150 } 1151 1152 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb); 1153 1154 #undef STATE_TRACE 1155 1156 #ifdef STATE_TRACE 1157 static const char *statename[]={ 1158 "Unused","Established","Syn Sent","Syn Recv", 1159 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1160 "Close Wait","Last ACK","Listen","Closing" 1161 }; 1162 #endif 1163 void tcp_set_state(struct sock *sk, int state); 1164 1165 void tcp_done(struct sock *sk); 1166 1167 int tcp_abort(struct sock *sk, int err); 1168 1169 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1170 { 1171 rx_opt->dsack = 0; 1172 rx_opt->num_sacks = 0; 1173 } 1174 1175 u32 tcp_default_init_rwnd(u32 mss); 1176 void tcp_cwnd_restart(struct sock *sk, s32 delta); 1177 1178 static inline void tcp_slow_start_after_idle_check(struct sock *sk) 1179 { 1180 struct tcp_sock *tp = tcp_sk(sk); 1181 s32 delta; 1182 1183 if (!sysctl_tcp_slow_start_after_idle || tp->packets_out) 1184 return; 1185 delta = tcp_time_stamp - tp->lsndtime; 1186 if (delta > inet_csk(sk)->icsk_rto) 1187 tcp_cwnd_restart(sk, delta); 1188 } 1189 1190 /* Determine a window scaling and initial window to offer. */ 1191 void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd, 1192 __u32 *window_clamp, int wscale_ok, 1193 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1194 1195 static inline int tcp_win_from_space(int space) 1196 { 1197 return sysctl_tcp_adv_win_scale<=0 ? 1198 (space>>(-sysctl_tcp_adv_win_scale)) : 1199 space - (space>>sysctl_tcp_adv_win_scale); 1200 } 1201 1202 /* Note: caller must be prepared to deal with negative returns */ 1203 static inline int tcp_space(const struct sock *sk) 1204 { 1205 return tcp_win_from_space(sk->sk_rcvbuf - 1206 atomic_read(&sk->sk_rmem_alloc)); 1207 } 1208 1209 static inline int tcp_full_space(const struct sock *sk) 1210 { 1211 return tcp_win_from_space(sk->sk_rcvbuf); 1212 } 1213 1214 extern void tcp_openreq_init_rwin(struct request_sock *req, 1215 const struct sock *sk_listener, 1216 const struct dst_entry *dst); 1217 1218 void tcp_enter_memory_pressure(struct sock *sk); 1219 1220 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1221 { 1222 struct net *net = sock_net((struct sock *)tp); 1223 1224 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl; 1225 } 1226 1227 static inline int keepalive_time_when(const struct tcp_sock *tp) 1228 { 1229 struct net *net = sock_net((struct sock *)tp); 1230 1231 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time; 1232 } 1233 1234 static inline int keepalive_probes(const struct tcp_sock *tp) 1235 { 1236 struct net *net = sock_net((struct sock *)tp); 1237 1238 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes; 1239 } 1240 1241 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1242 { 1243 const struct inet_connection_sock *icsk = &tp->inet_conn; 1244 1245 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime, 1246 tcp_time_stamp - tp->rcv_tstamp); 1247 } 1248 1249 static inline int tcp_fin_time(const struct sock *sk) 1250 { 1251 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout; 1252 const int rto = inet_csk(sk)->icsk_rto; 1253 1254 if (fin_timeout < (rto << 2) - (rto >> 1)) 1255 fin_timeout = (rto << 2) - (rto >> 1); 1256 1257 return fin_timeout; 1258 } 1259 1260 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1261 int paws_win) 1262 { 1263 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1264 return true; 1265 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1266 return true; 1267 /* 1268 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1269 * then following tcp messages have valid values. Ignore 0 value, 1270 * or else 'negative' tsval might forbid us to accept their packets. 1271 */ 1272 if (!rx_opt->ts_recent) 1273 return true; 1274 return false; 1275 } 1276 1277 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1278 int rst) 1279 { 1280 if (tcp_paws_check(rx_opt, 0)) 1281 return false; 1282 1283 /* RST segments are not recommended to carry timestamp, 1284 and, if they do, it is recommended to ignore PAWS because 1285 "their cleanup function should take precedence over timestamps." 1286 Certainly, it is mistake. It is necessary to understand the reasons 1287 of this constraint to relax it: if peer reboots, clock may go 1288 out-of-sync and half-open connections will not be reset. 1289 Actually, the problem would be not existing if all 1290 the implementations followed draft about maintaining clock 1291 via reboots. Linux-2.2 DOES NOT! 1292 1293 However, we can relax time bounds for RST segments to MSL. 1294 */ 1295 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1296 return false; 1297 return true; 1298 } 1299 1300 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, 1301 int mib_idx, u32 *last_oow_ack_time); 1302 1303 static inline void tcp_mib_init(struct net *net) 1304 { 1305 /* See RFC 2012 */ 1306 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1); 1307 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1308 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1309 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1); 1310 } 1311 1312 /* from STCP */ 1313 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1314 { 1315 tp->lost_skb_hint = NULL; 1316 } 1317 1318 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1319 { 1320 tcp_clear_retrans_hints_partial(tp); 1321 tp->retransmit_skb_hint = NULL; 1322 } 1323 1324 union tcp_md5_addr { 1325 struct in_addr a4; 1326 #if IS_ENABLED(CONFIG_IPV6) 1327 struct in6_addr a6; 1328 #endif 1329 }; 1330 1331 /* - key database */ 1332 struct tcp_md5sig_key { 1333 struct hlist_node node; 1334 u8 keylen; 1335 u8 family; /* AF_INET or AF_INET6 */ 1336 union tcp_md5_addr addr; 1337 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1338 struct rcu_head rcu; 1339 }; 1340 1341 /* - sock block */ 1342 struct tcp_md5sig_info { 1343 struct hlist_head head; 1344 struct rcu_head rcu; 1345 }; 1346 1347 /* - pseudo header */ 1348 struct tcp4_pseudohdr { 1349 __be32 saddr; 1350 __be32 daddr; 1351 __u8 pad; 1352 __u8 protocol; 1353 __be16 len; 1354 }; 1355 1356 struct tcp6_pseudohdr { 1357 struct in6_addr saddr; 1358 struct in6_addr daddr; 1359 __be32 len; 1360 __be32 protocol; /* including padding */ 1361 }; 1362 1363 union tcp_md5sum_block { 1364 struct tcp4_pseudohdr ip4; 1365 #if IS_ENABLED(CONFIG_IPV6) 1366 struct tcp6_pseudohdr ip6; 1367 #endif 1368 }; 1369 1370 /* - pool: digest algorithm, hash description and scratch buffer */ 1371 struct tcp_md5sig_pool { 1372 struct ahash_request *md5_req; 1373 union tcp_md5sum_block md5_blk; 1374 }; 1375 1376 /* - functions */ 1377 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1378 const struct sock *sk, const struct sk_buff *skb); 1379 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1380 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp); 1381 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1382 int family); 1383 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 1384 const struct sock *addr_sk); 1385 1386 #ifdef CONFIG_TCP_MD5SIG 1387 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1388 const union tcp_md5_addr *addr, 1389 int family); 1390 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1391 #else 1392 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1393 const union tcp_md5_addr *addr, 1394 int family) 1395 { 1396 return NULL; 1397 } 1398 #define tcp_twsk_md5_key(twsk) NULL 1399 #endif 1400 1401 bool tcp_alloc_md5sig_pool(void); 1402 1403 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1404 static inline void tcp_put_md5sig_pool(void) 1405 { 1406 local_bh_enable(); 1407 } 1408 1409 int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *); 1410 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1411 unsigned int header_len); 1412 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1413 const struct tcp_md5sig_key *key); 1414 1415 /* From tcp_fastopen.c */ 1416 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1417 struct tcp_fastopen_cookie *cookie, int *syn_loss, 1418 unsigned long *last_syn_loss); 1419 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1420 struct tcp_fastopen_cookie *cookie, bool syn_lost, 1421 u16 try_exp); 1422 struct tcp_fastopen_request { 1423 /* Fast Open cookie. Size 0 means a cookie request */ 1424 struct tcp_fastopen_cookie cookie; 1425 struct msghdr *data; /* data in MSG_FASTOPEN */ 1426 size_t size; 1427 int copied; /* queued in tcp_connect() */ 1428 }; 1429 void tcp_free_fastopen_req(struct tcp_sock *tp); 1430 1431 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; 1432 int tcp_fastopen_reset_cipher(void *key, unsigned int len); 1433 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb); 1434 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1435 struct request_sock *req, 1436 struct tcp_fastopen_cookie *foc, 1437 struct dst_entry *dst); 1438 void tcp_fastopen_init_key_once(bool publish); 1439 #define TCP_FASTOPEN_KEY_LENGTH 16 1440 1441 /* Fastopen key context */ 1442 struct tcp_fastopen_context { 1443 struct crypto_cipher *tfm; 1444 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1445 struct rcu_head rcu; 1446 }; 1447 1448 /* write queue abstraction */ 1449 static inline void tcp_write_queue_purge(struct sock *sk) 1450 { 1451 struct sk_buff *skb; 1452 1453 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) 1454 sk_wmem_free_skb(sk, skb); 1455 sk_mem_reclaim(sk); 1456 tcp_clear_all_retrans_hints(tcp_sk(sk)); 1457 } 1458 1459 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1460 { 1461 return skb_peek(&sk->sk_write_queue); 1462 } 1463 1464 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1465 { 1466 return skb_peek_tail(&sk->sk_write_queue); 1467 } 1468 1469 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk, 1470 const struct sk_buff *skb) 1471 { 1472 return skb_queue_next(&sk->sk_write_queue, skb); 1473 } 1474 1475 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk, 1476 const struct sk_buff *skb) 1477 { 1478 return skb_queue_prev(&sk->sk_write_queue, skb); 1479 } 1480 1481 #define tcp_for_write_queue(skb, sk) \ 1482 skb_queue_walk(&(sk)->sk_write_queue, skb) 1483 1484 #define tcp_for_write_queue_from(skb, sk) \ 1485 skb_queue_walk_from(&(sk)->sk_write_queue, skb) 1486 1487 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1488 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1489 1490 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1491 { 1492 return sk->sk_send_head; 1493 } 1494 1495 static inline bool tcp_skb_is_last(const struct sock *sk, 1496 const struct sk_buff *skb) 1497 { 1498 return skb_queue_is_last(&sk->sk_write_queue, skb); 1499 } 1500 1501 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb) 1502 { 1503 if (tcp_skb_is_last(sk, skb)) 1504 sk->sk_send_head = NULL; 1505 else 1506 sk->sk_send_head = tcp_write_queue_next(sk, skb); 1507 } 1508 1509 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1510 { 1511 if (sk->sk_send_head == skb_unlinked) 1512 sk->sk_send_head = NULL; 1513 } 1514 1515 static inline void tcp_init_send_head(struct sock *sk) 1516 { 1517 sk->sk_send_head = NULL; 1518 } 1519 1520 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1521 { 1522 __skb_queue_tail(&sk->sk_write_queue, skb); 1523 } 1524 1525 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1526 { 1527 __tcp_add_write_queue_tail(sk, skb); 1528 1529 /* Queue it, remembering where we must start sending. */ 1530 if (sk->sk_send_head == NULL) { 1531 sk->sk_send_head = skb; 1532 1533 if (tcp_sk(sk)->highest_sack == NULL) 1534 tcp_sk(sk)->highest_sack = skb; 1535 } 1536 } 1537 1538 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb) 1539 { 1540 __skb_queue_head(&sk->sk_write_queue, skb); 1541 } 1542 1543 /* Insert buff after skb on the write queue of sk. */ 1544 static inline void tcp_insert_write_queue_after(struct sk_buff *skb, 1545 struct sk_buff *buff, 1546 struct sock *sk) 1547 { 1548 __skb_queue_after(&sk->sk_write_queue, skb, buff); 1549 } 1550 1551 /* Insert new before skb on the write queue of sk. */ 1552 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1553 struct sk_buff *skb, 1554 struct sock *sk) 1555 { 1556 __skb_queue_before(&sk->sk_write_queue, skb, new); 1557 1558 if (sk->sk_send_head == skb) 1559 sk->sk_send_head = new; 1560 } 1561 1562 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1563 { 1564 __skb_unlink(skb, &sk->sk_write_queue); 1565 } 1566 1567 static inline bool tcp_write_queue_empty(struct sock *sk) 1568 { 1569 return skb_queue_empty(&sk->sk_write_queue); 1570 } 1571 1572 static inline void tcp_push_pending_frames(struct sock *sk) 1573 { 1574 if (tcp_send_head(sk)) { 1575 struct tcp_sock *tp = tcp_sk(sk); 1576 1577 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1578 } 1579 } 1580 1581 /* Start sequence of the skb just after the highest skb with SACKed 1582 * bit, valid only if sacked_out > 0 or when the caller has ensured 1583 * validity by itself. 1584 */ 1585 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1586 { 1587 if (!tp->sacked_out) 1588 return tp->snd_una; 1589 1590 if (tp->highest_sack == NULL) 1591 return tp->snd_nxt; 1592 1593 return TCP_SKB_CB(tp->highest_sack)->seq; 1594 } 1595 1596 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1597 { 1598 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL : 1599 tcp_write_queue_next(sk, skb); 1600 } 1601 1602 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1603 { 1604 return tcp_sk(sk)->highest_sack; 1605 } 1606 1607 static inline void tcp_highest_sack_reset(struct sock *sk) 1608 { 1609 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk); 1610 } 1611 1612 /* Called when old skb is about to be deleted (to be combined with new skb) */ 1613 static inline void tcp_highest_sack_combine(struct sock *sk, 1614 struct sk_buff *old, 1615 struct sk_buff *new) 1616 { 1617 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack)) 1618 tcp_sk(sk)->highest_sack = new; 1619 } 1620 1621 /* This helper checks if socket has IP_TRANSPARENT set */ 1622 static inline bool inet_sk_transparent(const struct sock *sk) 1623 { 1624 switch (sk->sk_state) { 1625 case TCP_TIME_WAIT: 1626 return inet_twsk(sk)->tw_transparent; 1627 case TCP_NEW_SYN_RECV: 1628 return inet_rsk(inet_reqsk(sk))->no_srccheck; 1629 } 1630 return inet_sk(sk)->transparent; 1631 } 1632 1633 /* Determines whether this is a thin stream (which may suffer from 1634 * increased latency). Used to trigger latency-reducing mechanisms. 1635 */ 1636 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1637 { 1638 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1639 } 1640 1641 /* /proc */ 1642 enum tcp_seq_states { 1643 TCP_SEQ_STATE_LISTENING, 1644 TCP_SEQ_STATE_ESTABLISHED, 1645 }; 1646 1647 int tcp_seq_open(struct inode *inode, struct file *file); 1648 1649 struct tcp_seq_afinfo { 1650 char *name; 1651 sa_family_t family; 1652 const struct file_operations *seq_fops; 1653 struct seq_operations seq_ops; 1654 }; 1655 1656 struct tcp_iter_state { 1657 struct seq_net_private p; 1658 sa_family_t family; 1659 enum tcp_seq_states state; 1660 struct sock *syn_wait_sk; 1661 int bucket, offset, sbucket, num; 1662 loff_t last_pos; 1663 }; 1664 1665 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1666 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1667 1668 extern struct request_sock_ops tcp_request_sock_ops; 1669 extern struct request_sock_ops tcp6_request_sock_ops; 1670 1671 void tcp_v4_destroy_sock(struct sock *sk); 1672 1673 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 1674 netdev_features_t features); 1675 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb); 1676 int tcp_gro_complete(struct sk_buff *skb); 1677 1678 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 1679 1680 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 1681 { 1682 struct net *net = sock_net((struct sock *)tp); 1683 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat; 1684 } 1685 1686 static inline bool tcp_stream_memory_free(const struct sock *sk) 1687 { 1688 const struct tcp_sock *tp = tcp_sk(sk); 1689 u32 notsent_bytes = tp->write_seq - tp->snd_nxt; 1690 1691 return notsent_bytes < tcp_notsent_lowat(tp); 1692 } 1693 1694 #ifdef CONFIG_PROC_FS 1695 int tcp4_proc_init(void); 1696 void tcp4_proc_exit(void); 1697 #endif 1698 1699 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req); 1700 int tcp_conn_request(struct request_sock_ops *rsk_ops, 1701 const struct tcp_request_sock_ops *af_ops, 1702 struct sock *sk, struct sk_buff *skb); 1703 1704 /* TCP af-specific functions */ 1705 struct tcp_sock_af_ops { 1706 #ifdef CONFIG_TCP_MD5SIG 1707 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk, 1708 const struct sock *addr_sk); 1709 int (*calc_md5_hash)(char *location, 1710 const struct tcp_md5sig_key *md5, 1711 const struct sock *sk, 1712 const struct sk_buff *skb); 1713 int (*md5_parse)(struct sock *sk, 1714 char __user *optval, 1715 int optlen); 1716 #endif 1717 }; 1718 1719 struct tcp_request_sock_ops { 1720 u16 mss_clamp; 1721 #ifdef CONFIG_TCP_MD5SIG 1722 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk, 1723 const struct sock *addr_sk); 1724 int (*calc_md5_hash) (char *location, 1725 const struct tcp_md5sig_key *md5, 1726 const struct sock *sk, 1727 const struct sk_buff *skb); 1728 #endif 1729 void (*init_req)(struct request_sock *req, 1730 const struct sock *sk_listener, 1731 struct sk_buff *skb); 1732 #ifdef CONFIG_SYN_COOKIES 1733 __u32 (*cookie_init_seq)(const struct sk_buff *skb, 1734 __u16 *mss); 1735 #endif 1736 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl, 1737 const struct request_sock *req, 1738 bool *strict); 1739 __u32 (*init_seq)(const struct sk_buff *skb); 1740 int (*send_synack)(const struct sock *sk, struct dst_entry *dst, 1741 struct flowi *fl, struct request_sock *req, 1742 struct tcp_fastopen_cookie *foc, 1743 bool attach_req); 1744 }; 1745 1746 #ifdef CONFIG_SYN_COOKIES 1747 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1748 const struct sock *sk, struct sk_buff *skb, 1749 __u16 *mss) 1750 { 1751 tcp_synq_overflow(sk); 1752 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); 1753 return ops->cookie_init_seq(skb, mss); 1754 } 1755 #else 1756 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1757 const struct sock *sk, struct sk_buff *skb, 1758 __u16 *mss) 1759 { 1760 return 0; 1761 } 1762 #endif 1763 1764 int tcpv4_offload_init(void); 1765 1766 void tcp_v4_init(void); 1767 void tcp_init(void); 1768 1769 /* tcp_recovery.c */ 1770 1771 /* Flags to enable various loss recovery features. See below */ 1772 extern int sysctl_tcp_recovery; 1773 1774 /* Use TCP RACK to detect (some) tail and retransmit losses */ 1775 #define TCP_RACK_LOST_RETRANS 0x1 1776 1777 extern int tcp_rack_mark_lost(struct sock *sk); 1778 1779 extern void tcp_rack_advance(struct tcp_sock *tp, 1780 const struct skb_mstamp *xmit_time, u8 sacked); 1781 1782 /* 1783 * Save and compile IPv4 options, return a pointer to it 1784 */ 1785 static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb) 1786 { 1787 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; 1788 struct ip_options_rcu *dopt = NULL; 1789 1790 if (opt->optlen) { 1791 int opt_size = sizeof(*dopt) + opt->optlen; 1792 1793 dopt = kmalloc(opt_size, GFP_ATOMIC); 1794 if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) { 1795 kfree(dopt); 1796 dopt = NULL; 1797 } 1798 } 1799 return dopt; 1800 } 1801 1802 /* locally generated TCP pure ACKs have skb->truesize == 2 1803 * (check tcp_send_ack() in net/ipv4/tcp_output.c ) 1804 * This is much faster than dissecting the packet to find out. 1805 * (Think of GRE encapsulations, IPv4, IPv6, ...) 1806 */ 1807 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb) 1808 { 1809 return skb->truesize == 2; 1810 } 1811 1812 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb) 1813 { 1814 skb->truesize = 2; 1815 } 1816 1817 static inline int tcp_inq(struct sock *sk) 1818 { 1819 struct tcp_sock *tp = tcp_sk(sk); 1820 int answ; 1821 1822 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { 1823 answ = 0; 1824 } else if (sock_flag(sk, SOCK_URGINLINE) || 1825 !tp->urg_data || 1826 before(tp->urg_seq, tp->copied_seq) || 1827 !before(tp->urg_seq, tp->rcv_nxt)) { 1828 1829 answ = tp->rcv_nxt - tp->copied_seq; 1830 1831 /* Subtract 1, if FIN was received */ 1832 if (answ && sock_flag(sk, SOCK_DONE)) 1833 answ--; 1834 } else { 1835 answ = tp->urg_seq - tp->copied_seq; 1836 } 1837 1838 return answ; 1839 } 1840 1841 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb) 1842 { 1843 u16 segs_in; 1844 1845 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs); 1846 tp->segs_in += segs_in; 1847 if (skb->len > tcp_hdrlen(skb)) 1848 tp->data_segs_in += segs_in; 1849 } 1850 1851 #endif /* _TCP_H */ 1852