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/dmaengine.h> 31 #include <linux/crypto.h> 32 #include <linux/cryptohash.h> 33 #include <linux/kref.h> 34 #include <linux/ktime.h> 35 36 #include <net/inet_connection_sock.h> 37 #include <net/inet_timewait_sock.h> 38 #include <net/inet_hashtables.h> 39 #include <net/checksum.h> 40 #include <net/request_sock.h> 41 #include <net/sock.h> 42 #include <net/snmp.h> 43 #include <net/ip.h> 44 #include <net/tcp_states.h> 45 #include <net/inet_ecn.h> 46 #include <net/dst.h> 47 48 #include <linux/seq_file.h> 49 #include <linux/memcontrol.h> 50 51 extern struct inet_hashinfo tcp_hashinfo; 52 53 extern struct percpu_counter tcp_orphan_count; 54 void tcp_time_wait(struct sock *sk, int state, int timeo); 55 56 #define MAX_TCP_HEADER (128 + MAX_HEADER) 57 #define MAX_TCP_OPTION_SPACE 40 58 59 /* 60 * Never offer a window over 32767 without using window scaling. Some 61 * poor stacks do signed 16bit maths! 62 */ 63 #define MAX_TCP_WINDOW 32767U 64 65 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */ 66 #define TCP_MIN_MSS 88U 67 68 /* The least MTU to use for probing */ 69 #define TCP_BASE_MSS 512 70 71 /* After receiving this amount of duplicate ACKs fast retransmit starts. */ 72 #define TCP_FASTRETRANS_THRESH 3 73 74 /* Maximal reordering. */ 75 #define TCP_MAX_REORDERING 127 76 77 /* Maximal number of ACKs sent quickly to accelerate slow-start. */ 78 #define TCP_MAX_QUICKACKS 16U 79 80 /* urg_data states */ 81 #define TCP_URG_VALID 0x0100 82 #define TCP_URG_NOTYET 0x0200 83 #define TCP_URG_READ 0x0400 84 85 #define TCP_RETR1 3 /* 86 * This is how many retries it does before it 87 * tries to figure out if the gateway is 88 * down. Minimal RFC value is 3; it corresponds 89 * to ~3sec-8min depending on RTO. 90 */ 91 92 #define TCP_RETR2 15 /* 93 * This should take at least 94 * 90 minutes to time out. 95 * RFC1122 says that the limit is 100 sec. 96 * 15 is ~13-30min depending on RTO. 97 */ 98 99 #define TCP_SYN_RETRIES 6 /* This is how many retries are done 100 * when active opening a connection. 101 * RFC1122 says the minimum retry MUST 102 * be at least 180secs. Nevertheless 103 * this value is corresponding to 104 * 63secs of retransmission with the 105 * current initial RTO. 106 */ 107 108 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done 109 * when passive opening a connection. 110 * This is corresponding to 31secs of 111 * retransmission with the current 112 * initial RTO. 113 */ 114 115 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT 116 * state, about 60 seconds */ 117 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN 118 /* BSD style FIN_WAIT2 deadlock breaker. 119 * It used to be 3min, new value is 60sec, 120 * to combine FIN-WAIT-2 timeout with 121 * TIME-WAIT timer. 122 */ 123 124 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ 125 #if HZ >= 100 126 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */ 127 #define TCP_ATO_MIN ((unsigned)(HZ/25)) 128 #else 129 #define TCP_DELACK_MIN 4U 130 #define TCP_ATO_MIN 4U 131 #endif 132 #define TCP_RTO_MAX ((unsigned)(120*HZ)) 133 #define TCP_RTO_MIN ((unsigned)(HZ/5)) 134 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */ 135 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now 136 * used as a fallback RTO for the 137 * initial data transmission if no 138 * valid RTT sample has been acquired, 139 * most likely due to retrans in 3WHS. 140 */ 141 142 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes 143 * for local resources. 144 */ 145 146 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ 147 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ 148 #define TCP_KEEPALIVE_INTVL (75*HZ) 149 150 #define MAX_TCP_KEEPIDLE 32767 151 #define MAX_TCP_KEEPINTVL 32767 152 #define MAX_TCP_KEEPCNT 127 153 #define MAX_TCP_SYNCNT 127 154 155 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */ 156 157 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24) 158 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated 159 * after this time. It should be equal 160 * (or greater than) TCP_TIMEWAIT_LEN 161 * to provide reliability equal to one 162 * provided by timewait state. 163 */ 164 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host 165 * timestamps. It must be less than 166 * minimal timewait lifetime. 167 */ 168 /* 169 * TCP option 170 */ 171 172 #define TCPOPT_NOP 1 /* Padding */ 173 #define TCPOPT_EOL 0 /* End of options */ 174 #define TCPOPT_MSS 2 /* Segment size negotiating */ 175 #define TCPOPT_WINDOW 3 /* Window scaling */ 176 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ 177 #define TCPOPT_SACK 5 /* SACK Block */ 178 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ 179 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */ 180 #define TCPOPT_EXP 254 /* Experimental */ 181 /* Magic number to be after the option value for sharing TCP 182 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt 183 */ 184 #define TCPOPT_FASTOPEN_MAGIC 0xF989 185 186 /* 187 * TCP option lengths 188 */ 189 190 #define TCPOLEN_MSS 4 191 #define TCPOLEN_WINDOW 3 192 #define TCPOLEN_SACK_PERM 2 193 #define TCPOLEN_TIMESTAMP 10 194 #define TCPOLEN_MD5SIG 18 195 #define TCPOLEN_EXP_FASTOPEN_BASE 4 196 197 /* But this is what stacks really send out. */ 198 #define TCPOLEN_TSTAMP_ALIGNED 12 199 #define TCPOLEN_WSCALE_ALIGNED 4 200 #define TCPOLEN_SACKPERM_ALIGNED 4 201 #define TCPOLEN_SACK_BASE 2 202 #define TCPOLEN_SACK_BASE_ALIGNED 4 203 #define TCPOLEN_SACK_PERBLOCK 8 204 #define TCPOLEN_MD5SIG_ALIGNED 20 205 #define TCPOLEN_MSS_ALIGNED 4 206 207 /* Flags in tp->nonagle */ 208 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */ 209 #define TCP_NAGLE_CORK 2 /* Socket is corked */ 210 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */ 211 212 /* TCP thin-stream limits */ 213 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */ 214 215 /* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */ 216 #define TCP_INIT_CWND 10 217 218 /* Bit Flags for sysctl_tcp_fastopen */ 219 #define TFO_CLIENT_ENABLE 1 220 #define TFO_SERVER_ENABLE 2 221 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */ 222 223 /* Process SYN data but skip cookie validation */ 224 #define TFO_SERVER_COOKIE_NOT_CHKED 0x100 225 /* Accept SYN data w/o any cookie option */ 226 #define TFO_SERVER_COOKIE_NOT_REQD 0x200 227 228 /* Force enable TFO on all listeners, i.e., not requiring the 229 * TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen. 230 */ 231 #define TFO_SERVER_WO_SOCKOPT1 0x400 232 #define TFO_SERVER_WO_SOCKOPT2 0x800 233 /* Always create TFO child sockets on a TFO listener even when 234 * cookie/data not present. (For testing purpose!) 235 */ 236 #define TFO_SERVER_ALWAYS 0x1000 237 238 extern struct inet_timewait_death_row tcp_death_row; 239 240 /* sysctl variables for tcp */ 241 extern int sysctl_tcp_timestamps; 242 extern int sysctl_tcp_window_scaling; 243 extern int sysctl_tcp_sack; 244 extern int sysctl_tcp_fin_timeout; 245 extern int sysctl_tcp_keepalive_time; 246 extern int sysctl_tcp_keepalive_probes; 247 extern int sysctl_tcp_keepalive_intvl; 248 extern int sysctl_tcp_syn_retries; 249 extern int sysctl_tcp_synack_retries; 250 extern int sysctl_tcp_retries1; 251 extern int sysctl_tcp_retries2; 252 extern int sysctl_tcp_orphan_retries; 253 extern int sysctl_tcp_syncookies; 254 extern int sysctl_tcp_fastopen; 255 extern int sysctl_tcp_retrans_collapse; 256 extern int sysctl_tcp_stdurg; 257 extern int sysctl_tcp_rfc1337; 258 extern int sysctl_tcp_abort_on_overflow; 259 extern int sysctl_tcp_max_orphans; 260 extern int sysctl_tcp_fack; 261 extern int sysctl_tcp_reordering; 262 extern int sysctl_tcp_dsack; 263 extern long sysctl_tcp_mem[3]; 264 extern int sysctl_tcp_wmem[3]; 265 extern int sysctl_tcp_rmem[3]; 266 extern int sysctl_tcp_app_win; 267 extern int sysctl_tcp_adv_win_scale; 268 extern int sysctl_tcp_tw_reuse; 269 extern int sysctl_tcp_frto; 270 extern int sysctl_tcp_low_latency; 271 extern int sysctl_tcp_dma_copybreak; 272 extern int sysctl_tcp_nometrics_save; 273 extern int sysctl_tcp_moderate_rcvbuf; 274 extern int sysctl_tcp_tso_win_divisor; 275 extern int sysctl_tcp_mtu_probing; 276 extern int sysctl_tcp_base_mss; 277 extern int sysctl_tcp_workaround_signed_windows; 278 extern int sysctl_tcp_slow_start_after_idle; 279 extern int sysctl_tcp_thin_linear_timeouts; 280 extern int sysctl_tcp_thin_dupack; 281 extern int sysctl_tcp_early_retrans; 282 extern int sysctl_tcp_limit_output_bytes; 283 extern int sysctl_tcp_challenge_ack_limit; 284 extern unsigned int sysctl_tcp_notsent_lowat; 285 extern int sysctl_tcp_min_tso_segs; 286 extern int sysctl_tcp_autocorking; 287 288 extern atomic_long_t tcp_memory_allocated; 289 extern struct percpu_counter tcp_sockets_allocated; 290 extern int tcp_memory_pressure; 291 292 /* 293 * The next routines deal with comparing 32 bit unsigned ints 294 * and worry about wraparound (automatic with unsigned arithmetic). 295 */ 296 297 static inline bool before(__u32 seq1, __u32 seq2) 298 { 299 return (__s32)(seq1-seq2) < 0; 300 } 301 #define after(seq2, seq1) before(seq1, seq2) 302 303 /* is s2<=s1<=s3 ? */ 304 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) 305 { 306 return seq3 - seq2 >= seq1 - seq2; 307 } 308 309 static inline bool tcp_out_of_memory(struct sock *sk) 310 { 311 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 312 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2)) 313 return true; 314 return false; 315 } 316 317 static inline bool tcp_too_many_orphans(struct sock *sk, int shift) 318 { 319 struct percpu_counter *ocp = sk->sk_prot->orphan_count; 320 int orphans = percpu_counter_read_positive(ocp); 321 322 if (orphans << shift > sysctl_tcp_max_orphans) { 323 orphans = percpu_counter_sum_positive(ocp); 324 if (orphans << shift > sysctl_tcp_max_orphans) 325 return true; 326 } 327 return false; 328 } 329 330 bool tcp_check_oom(struct sock *sk, int shift); 331 332 /* syncookies: remember time of last synqueue overflow */ 333 static inline void tcp_synq_overflow(struct sock *sk) 334 { 335 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies; 336 } 337 338 /* syncookies: no recent synqueue overflow on this listening socket? */ 339 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 340 { 341 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 342 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK); 343 } 344 345 extern struct proto tcp_prot; 346 347 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 348 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field) 349 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 350 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val) 351 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 352 353 void tcp_tasklet_init(void); 354 355 void tcp_v4_err(struct sk_buff *skb, u32); 356 357 void tcp_shutdown(struct sock *sk, int how); 358 359 void tcp_v4_early_demux(struct sk_buff *skb); 360 int tcp_v4_rcv(struct sk_buff *skb); 361 362 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 363 int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 364 size_t size); 365 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, 366 int flags); 367 void tcp_release_cb(struct sock *sk); 368 void tcp_wfree(struct sk_buff *skb); 369 void tcp_write_timer_handler(struct sock *sk); 370 void tcp_delack_timer_handler(struct sock *sk); 371 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 372 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb, 373 const struct tcphdr *th, unsigned int len); 374 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 375 const struct tcphdr *th, unsigned int len); 376 void tcp_rcv_space_adjust(struct sock *sk); 377 void tcp_cleanup_rbuf(struct sock *sk, int copied); 378 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 379 void tcp_twsk_destructor(struct sock *sk); 380 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 381 struct pipe_inode_info *pipe, size_t len, 382 unsigned int flags); 383 384 static inline void tcp_dec_quickack_mode(struct sock *sk, 385 const unsigned int pkts) 386 { 387 struct inet_connection_sock *icsk = inet_csk(sk); 388 389 if (icsk->icsk_ack.quick) { 390 if (pkts >= icsk->icsk_ack.quick) { 391 icsk->icsk_ack.quick = 0; 392 /* Leaving quickack mode we deflate ATO. */ 393 icsk->icsk_ack.ato = TCP_ATO_MIN; 394 } else 395 icsk->icsk_ack.quick -= pkts; 396 } 397 } 398 399 #define TCP_ECN_OK 1 400 #define TCP_ECN_QUEUE_CWR 2 401 #define TCP_ECN_DEMAND_CWR 4 402 #define TCP_ECN_SEEN 8 403 404 enum tcp_tw_status { 405 TCP_TW_SUCCESS = 0, 406 TCP_TW_RST = 1, 407 TCP_TW_ACK = 2, 408 TCP_TW_SYN = 3 409 }; 410 411 412 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 413 struct sk_buff *skb, 414 const struct tcphdr *th); 415 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 416 struct request_sock *req, struct request_sock **prev, 417 bool fastopen); 418 int tcp_child_process(struct sock *parent, struct sock *child, 419 struct sk_buff *skb); 420 void tcp_enter_loss(struct sock *sk, int how); 421 void tcp_clear_retrans(struct tcp_sock *tp); 422 void tcp_update_metrics(struct sock *sk); 423 void tcp_init_metrics(struct sock *sk); 424 void tcp_metrics_init(void); 425 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, 426 bool paws_check); 427 bool tcp_remember_stamp(struct sock *sk); 428 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw); 429 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst); 430 void tcp_disable_fack(struct tcp_sock *tp); 431 void tcp_close(struct sock *sk, long timeout); 432 void tcp_init_sock(struct sock *sk); 433 unsigned int tcp_poll(struct file *file, struct socket *sock, 434 struct poll_table_struct *wait); 435 int tcp_getsockopt(struct sock *sk, int level, int optname, 436 char __user *optval, int __user *optlen); 437 int tcp_setsockopt(struct sock *sk, int level, int optname, 438 char __user *optval, unsigned int optlen); 439 int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 440 char __user *optval, int __user *optlen); 441 int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 442 char __user *optval, unsigned int optlen); 443 void tcp_set_keepalive(struct sock *sk, int val); 444 void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req); 445 int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 446 size_t len, int nonblock, int flags, int *addr_len); 447 void tcp_parse_options(const struct sk_buff *skb, 448 struct tcp_options_received *opt_rx, 449 int estab, struct tcp_fastopen_cookie *foc); 450 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); 451 452 /* 453 * TCP v4 functions exported for the inet6 API 454 */ 455 456 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 457 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 458 struct sock *tcp_create_openreq_child(struct sock *sk, 459 struct request_sock *req, 460 struct sk_buff *skb); 461 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb, 462 struct request_sock *req, 463 struct dst_entry *dst); 464 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 465 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); 466 int tcp_connect(struct sock *sk); 467 struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, 468 struct request_sock *req, 469 struct tcp_fastopen_cookie *foc); 470 int tcp_disconnect(struct sock *sk, int flags); 471 472 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 473 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 474 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); 475 476 /* From syncookies.c */ 477 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th, 478 u32 cookie); 479 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, 480 struct ip_options *opt); 481 #ifdef CONFIG_SYN_COOKIES 482 483 /* Syncookies use a monotonic timer which increments every 60 seconds. 484 * This counter is used both as a hash input and partially encoded into 485 * the cookie value. A cookie is only validated further if the delta 486 * between the current counter value and the encoded one is less than this, 487 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if 488 * the counter advances immediately after a cookie is generated). 489 */ 490 #define MAX_SYNCOOKIE_AGE 2 491 492 static inline u32 tcp_cookie_time(void) 493 { 494 u64 val = get_jiffies_64(); 495 496 do_div(val, 60 * HZ); 497 return val; 498 } 499 500 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, 501 u16 *mssp); 502 __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mss); 503 #else 504 static inline __u32 cookie_v4_init_sequence(struct sock *sk, 505 struct sk_buff *skb, 506 __u16 *mss) 507 { 508 return 0; 509 } 510 #endif 511 512 __u32 cookie_init_timestamp(struct request_sock *req); 513 bool cookie_check_timestamp(struct tcp_options_received *opt, struct net *net, 514 bool *ecn_ok); 515 516 /* From net/ipv6/syncookies.c */ 517 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th, 518 u32 cookie); 519 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 520 #ifdef CONFIG_SYN_COOKIES 521 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph, 522 const struct tcphdr *th, u16 *mssp); 523 __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb, 524 __u16 *mss); 525 #else 526 static inline __u32 cookie_v6_init_sequence(struct sock *sk, 527 struct sk_buff *skb, 528 __u16 *mss) 529 { 530 return 0; 531 } 532 #endif 533 /* tcp_output.c */ 534 535 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 536 int nonagle); 537 bool tcp_may_send_now(struct sock *sk); 538 int __tcp_retransmit_skb(struct sock *, struct sk_buff *); 539 int tcp_retransmit_skb(struct sock *, struct sk_buff *); 540 void tcp_retransmit_timer(struct sock *sk); 541 void tcp_xmit_retransmit_queue(struct sock *); 542 void tcp_simple_retransmit(struct sock *); 543 int tcp_trim_head(struct sock *, struct sk_buff *, u32); 544 int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int); 545 546 void tcp_send_probe0(struct sock *); 547 void tcp_send_partial(struct sock *); 548 int tcp_write_wakeup(struct sock *); 549 void tcp_send_fin(struct sock *sk); 550 void tcp_send_active_reset(struct sock *sk, gfp_t priority); 551 int tcp_send_synack(struct sock *); 552 bool tcp_syn_flood_action(struct sock *sk, const struct sk_buff *skb, 553 const char *proto); 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); 559 560 /* tcp_input.c */ 561 void tcp_cwnd_application_limited(struct sock *sk); 562 void tcp_resume_early_retransmit(struct sock *sk); 563 void tcp_rearm_rto(struct sock *sk); 564 void tcp_reset(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(const 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 /* Compute the actual receive window we are currently advertising. 666 * Rcv_nxt can be after the window if our peer push more data 667 * than the offered window. 668 */ 669 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 670 { 671 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 672 673 if (win < 0) 674 win = 0; 675 return (u32) win; 676 } 677 678 /* Choose a new window, without checks for shrinking, and without 679 * scaling applied to the result. The caller does these things 680 * if necessary. This is a "raw" window selection. 681 */ 682 u32 __tcp_select_window(struct sock *sk); 683 684 void tcp_send_window_probe(struct sock *sk); 685 686 /* TCP timestamps are only 32-bits, this causes a slight 687 * complication on 64-bit systems since we store a snapshot 688 * of jiffies in the buffer control blocks below. We decided 689 * to use only the low 32-bits of jiffies and hide the ugly 690 * casts with the following macro. 691 */ 692 #define tcp_time_stamp ((__u32)(jiffies)) 693 694 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 695 696 #define TCPHDR_FIN 0x01 697 #define TCPHDR_SYN 0x02 698 #define TCPHDR_RST 0x04 699 #define TCPHDR_PSH 0x08 700 #define TCPHDR_ACK 0x10 701 #define TCPHDR_URG 0x20 702 #define TCPHDR_ECE 0x40 703 #define TCPHDR_CWR 0x80 704 705 /* This is what the send packet queuing engine uses to pass 706 * TCP per-packet control information to the transmission code. 707 * We also store the host-order sequence numbers in here too. 708 * This is 44 bytes if IPV6 is enabled. 709 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 710 */ 711 struct tcp_skb_cb { 712 union { 713 struct inet_skb_parm h4; 714 #if IS_ENABLED(CONFIG_IPV6) 715 struct inet6_skb_parm h6; 716 #endif 717 } header; /* For incoming frames */ 718 __u32 seq; /* Starting sequence number */ 719 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 720 __u32 when; /* used to compute rtt's */ 721 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 722 723 __u8 sacked; /* State flags for SACK/FACK. */ 724 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 725 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 726 #define TCPCB_LOST 0x04 /* SKB is lost */ 727 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 728 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 729 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS) 730 731 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 732 /* 1 byte hole */ 733 __u32 ack_seq; /* Sequence number ACK'd */ 734 }; 735 736 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 737 738 /* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set 739 * 740 * If we receive a SYN packet with these bits set, it means a network is 741 * playing bad games with TOS bits. In order to avoid possible false congestion 742 * notifications, we disable TCP ECN negociation. 743 */ 744 static inline void 745 TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb, 746 struct net *net) 747 { 748 const struct tcphdr *th = tcp_hdr(skb); 749 750 if (net->ipv4.sysctl_tcp_ecn && th->ece && th->cwr && 751 INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield)) 752 inet_rsk(req)->ecn_ok = 1; 753 } 754 755 /* Due to TSO, an SKB can be composed of multiple actual 756 * packets. To keep these tracked properly, we use this. 757 */ 758 static inline int tcp_skb_pcount(const struct sk_buff *skb) 759 { 760 return skb_shinfo(skb)->gso_segs; 761 } 762 763 /* This is valid iff tcp_skb_pcount() > 1. */ 764 static inline int tcp_skb_mss(const struct sk_buff *skb) 765 { 766 return skb_shinfo(skb)->gso_size; 767 } 768 769 /* Events passed to congestion control interface */ 770 enum tcp_ca_event { 771 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 772 CA_EVENT_CWND_RESTART, /* congestion window restart */ 773 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 774 CA_EVENT_LOSS, /* loss timeout */ 775 CA_EVENT_FAST_ACK, /* in sequence ack */ 776 CA_EVENT_SLOW_ACK, /* other ack */ 777 }; 778 779 /* 780 * Interface for adding new TCP congestion control handlers 781 */ 782 #define TCP_CA_NAME_MAX 16 783 #define TCP_CA_MAX 128 784 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 785 786 #define TCP_CONG_NON_RESTRICTED 0x1 787 788 struct tcp_congestion_ops { 789 struct list_head list; 790 unsigned long flags; 791 792 /* initialize private data (optional) */ 793 void (*init)(struct sock *sk); 794 /* cleanup private data (optional) */ 795 void (*release)(struct sock *sk); 796 797 /* return slow start threshold (required) */ 798 u32 (*ssthresh)(struct sock *sk); 799 /* do new cwnd calculation (required) */ 800 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked, u32 in_flight); 801 /* call before changing ca_state (optional) */ 802 void (*set_state)(struct sock *sk, u8 new_state); 803 /* call when cwnd event occurs (optional) */ 804 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 805 /* new value of cwnd after loss (optional) */ 806 u32 (*undo_cwnd)(struct sock *sk); 807 /* hook for packet ack accounting (optional) */ 808 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us); 809 /* get info for inet_diag (optional) */ 810 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb); 811 812 char name[TCP_CA_NAME_MAX]; 813 struct module *owner; 814 }; 815 816 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 817 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 818 819 void tcp_init_congestion_control(struct sock *sk); 820 void tcp_cleanup_congestion_control(struct sock *sk); 821 int tcp_set_default_congestion_control(const char *name); 822 void tcp_get_default_congestion_control(char *name); 823 void tcp_get_available_congestion_control(char *buf, size_t len); 824 void tcp_get_allowed_congestion_control(char *buf, size_t len); 825 int tcp_set_allowed_congestion_control(char *allowed); 826 int tcp_set_congestion_control(struct sock *sk, const char *name); 827 int tcp_slow_start(struct tcp_sock *tp, u32 acked); 828 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w); 829 830 extern struct tcp_congestion_ops tcp_init_congestion_ops; 831 u32 tcp_reno_ssthresh(struct sock *sk); 832 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked, u32 in_flight); 833 extern struct tcp_congestion_ops tcp_reno; 834 835 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 836 { 837 struct inet_connection_sock *icsk = inet_csk(sk); 838 839 if (icsk->icsk_ca_ops->set_state) 840 icsk->icsk_ca_ops->set_state(sk, ca_state); 841 icsk->icsk_ca_state = ca_state; 842 } 843 844 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 845 { 846 const struct inet_connection_sock *icsk = inet_csk(sk); 847 848 if (icsk->icsk_ca_ops->cwnd_event) 849 icsk->icsk_ca_ops->cwnd_event(sk, event); 850 } 851 852 /* These functions determine how the current flow behaves in respect of SACK 853 * handling. SACK is negotiated with the peer, and therefore it can vary 854 * between different flows. 855 * 856 * tcp_is_sack - SACK enabled 857 * tcp_is_reno - No SACK 858 * tcp_is_fack - FACK enabled, implies SACK enabled 859 */ 860 static inline int tcp_is_sack(const struct tcp_sock *tp) 861 { 862 return tp->rx_opt.sack_ok; 863 } 864 865 static inline bool tcp_is_reno(const struct tcp_sock *tp) 866 { 867 return !tcp_is_sack(tp); 868 } 869 870 static inline bool tcp_is_fack(const struct tcp_sock *tp) 871 { 872 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED; 873 } 874 875 static inline void tcp_enable_fack(struct tcp_sock *tp) 876 { 877 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED; 878 } 879 880 /* TCP early-retransmit (ER) is similar to but more conservative than 881 * the thin-dupack feature. Enable ER only if thin-dupack is disabled. 882 */ 883 static inline void tcp_enable_early_retrans(struct tcp_sock *tp) 884 { 885 tp->do_early_retrans = sysctl_tcp_early_retrans && 886 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack && 887 sysctl_tcp_reordering == 3; 888 } 889 890 static inline void tcp_disable_early_retrans(struct tcp_sock *tp) 891 { 892 tp->do_early_retrans = 0; 893 } 894 895 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 896 { 897 return tp->sacked_out + tp->lost_out; 898 } 899 900 /* This determines how many packets are "in the network" to the best 901 * of our knowledge. In many cases it is conservative, but where 902 * detailed information is available from the receiver (via SACK 903 * blocks etc.) we can make more aggressive calculations. 904 * 905 * Use this for decisions involving congestion control, use just 906 * tp->packets_out to determine if the send queue is empty or not. 907 * 908 * Read this equation as: 909 * 910 * "Packets sent once on transmission queue" MINUS 911 * "Packets left network, but not honestly ACKed yet" PLUS 912 * "Packets fast retransmitted" 913 */ 914 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 915 { 916 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 917 } 918 919 #define TCP_INFINITE_SSTHRESH 0x7fffffff 920 921 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 922 { 923 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 924 } 925 926 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 927 { 928 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 929 (1 << inet_csk(sk)->icsk_ca_state); 930 } 931 932 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 933 * The exception is cwnd reduction phase, when cwnd is decreasing towards 934 * ssthresh. 935 */ 936 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 937 { 938 const struct tcp_sock *tp = tcp_sk(sk); 939 940 if (tcp_in_cwnd_reduction(sk)) 941 return tp->snd_ssthresh; 942 else 943 return max(tp->snd_ssthresh, 944 ((tp->snd_cwnd >> 1) + 945 (tp->snd_cwnd >> 2))); 946 } 947 948 /* Use define here intentionally to get WARN_ON location shown at the caller */ 949 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 950 951 void tcp_enter_cwr(struct sock *sk, const int set_ssthresh); 952 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 953 954 /* The maximum number of MSS of available cwnd for which TSO defers 955 * sending if not using sysctl_tcp_tso_win_divisor. 956 */ 957 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 958 { 959 return 3; 960 } 961 962 /* Slow start with delack produces 3 packets of burst, so that 963 * it is safe "de facto". This will be the default - same as 964 * the default reordering threshold - but if reordering increases, 965 * we must be able to allow cwnd to burst at least this much in order 966 * to not pull it back when holes are filled. 967 */ 968 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp) 969 { 970 return tp->reordering; 971 } 972 973 /* Returns end sequence number of the receiver's advertised window */ 974 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 975 { 976 return tp->snd_una + tp->snd_wnd; 977 } 978 bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight); 979 980 static inline void tcp_check_probe_timer(struct sock *sk) 981 { 982 const struct tcp_sock *tp = tcp_sk(sk); 983 const struct inet_connection_sock *icsk = inet_csk(sk); 984 985 if (!tp->packets_out && !icsk->icsk_pending) 986 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 987 icsk->icsk_rto, TCP_RTO_MAX); 988 } 989 990 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 991 { 992 tp->snd_wl1 = seq; 993 } 994 995 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 996 { 997 tp->snd_wl1 = seq; 998 } 999 1000 /* 1001 * Calculate(/check) TCP checksum 1002 */ 1003 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1004 __be32 daddr, __wsum base) 1005 { 1006 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1007 } 1008 1009 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1010 { 1011 return __skb_checksum_complete(skb); 1012 } 1013 1014 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1015 { 1016 return !skb_csum_unnecessary(skb) && 1017 __tcp_checksum_complete(skb); 1018 } 1019 1020 /* Prequeue for VJ style copy to user, combined with checksumming. */ 1021 1022 static inline void tcp_prequeue_init(struct tcp_sock *tp) 1023 { 1024 tp->ucopy.task = NULL; 1025 tp->ucopy.len = 0; 1026 tp->ucopy.memory = 0; 1027 skb_queue_head_init(&tp->ucopy.prequeue); 1028 #ifdef CONFIG_NET_DMA 1029 tp->ucopy.dma_chan = NULL; 1030 tp->ucopy.wakeup = 0; 1031 tp->ucopy.pinned_list = NULL; 1032 tp->ucopy.dma_cookie = 0; 1033 #endif 1034 } 1035 1036 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb); 1037 1038 #undef STATE_TRACE 1039 1040 #ifdef STATE_TRACE 1041 static const char *statename[]={ 1042 "Unused","Established","Syn Sent","Syn Recv", 1043 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1044 "Close Wait","Last ACK","Listen","Closing" 1045 }; 1046 #endif 1047 void tcp_set_state(struct sock *sk, int state); 1048 1049 void tcp_done(struct sock *sk); 1050 1051 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1052 { 1053 rx_opt->dsack = 0; 1054 rx_opt->num_sacks = 0; 1055 } 1056 1057 u32 tcp_default_init_rwnd(u32 mss); 1058 1059 /* Determine a window scaling and initial window to offer. */ 1060 void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd, 1061 __u32 *window_clamp, int wscale_ok, 1062 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1063 1064 static inline int tcp_win_from_space(int space) 1065 { 1066 return sysctl_tcp_adv_win_scale<=0 ? 1067 (space>>(-sysctl_tcp_adv_win_scale)) : 1068 space - (space>>sysctl_tcp_adv_win_scale); 1069 } 1070 1071 /* Note: caller must be prepared to deal with negative returns */ 1072 static inline int tcp_space(const struct sock *sk) 1073 { 1074 return tcp_win_from_space(sk->sk_rcvbuf - 1075 atomic_read(&sk->sk_rmem_alloc)); 1076 } 1077 1078 static inline int tcp_full_space(const struct sock *sk) 1079 { 1080 return tcp_win_from_space(sk->sk_rcvbuf); 1081 } 1082 1083 static inline void tcp_openreq_init(struct request_sock *req, 1084 struct tcp_options_received *rx_opt, 1085 struct sk_buff *skb) 1086 { 1087 struct inet_request_sock *ireq = inet_rsk(req); 1088 1089 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */ 1090 req->cookie_ts = 0; 1091 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq; 1092 tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1; 1093 tcp_rsk(req)->snt_synack = 0; 1094 req->mss = rx_opt->mss_clamp; 1095 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0; 1096 ireq->tstamp_ok = rx_opt->tstamp_ok; 1097 ireq->sack_ok = rx_opt->sack_ok; 1098 ireq->snd_wscale = rx_opt->snd_wscale; 1099 ireq->wscale_ok = rx_opt->wscale_ok; 1100 ireq->acked = 0; 1101 ireq->ecn_ok = 0; 1102 ireq->ir_rmt_port = tcp_hdr(skb)->source; 1103 ireq->ir_num = ntohs(tcp_hdr(skb)->dest); 1104 } 1105 1106 void tcp_enter_memory_pressure(struct sock *sk); 1107 1108 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1109 { 1110 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl; 1111 } 1112 1113 static inline int keepalive_time_when(const struct tcp_sock *tp) 1114 { 1115 return tp->keepalive_time ? : sysctl_tcp_keepalive_time; 1116 } 1117 1118 static inline int keepalive_probes(const struct tcp_sock *tp) 1119 { 1120 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes; 1121 } 1122 1123 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1124 { 1125 const struct inet_connection_sock *icsk = &tp->inet_conn; 1126 1127 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime, 1128 tcp_time_stamp - tp->rcv_tstamp); 1129 } 1130 1131 static inline int tcp_fin_time(const struct sock *sk) 1132 { 1133 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout; 1134 const int rto = inet_csk(sk)->icsk_rto; 1135 1136 if (fin_timeout < (rto << 2) - (rto >> 1)) 1137 fin_timeout = (rto << 2) - (rto >> 1); 1138 1139 return fin_timeout; 1140 } 1141 1142 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1143 int paws_win) 1144 { 1145 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1146 return true; 1147 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1148 return true; 1149 /* 1150 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1151 * then following tcp messages have valid values. Ignore 0 value, 1152 * or else 'negative' tsval might forbid us to accept their packets. 1153 */ 1154 if (!rx_opt->ts_recent) 1155 return true; 1156 return false; 1157 } 1158 1159 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1160 int rst) 1161 { 1162 if (tcp_paws_check(rx_opt, 0)) 1163 return false; 1164 1165 /* RST segments are not recommended to carry timestamp, 1166 and, if they do, it is recommended to ignore PAWS because 1167 "their cleanup function should take precedence over timestamps." 1168 Certainly, it is mistake. It is necessary to understand the reasons 1169 of this constraint to relax it: if peer reboots, clock may go 1170 out-of-sync and half-open connections will not be reset. 1171 Actually, the problem would be not existing if all 1172 the implementations followed draft about maintaining clock 1173 via reboots. Linux-2.2 DOES NOT! 1174 1175 However, we can relax time bounds for RST segments to MSL. 1176 */ 1177 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1178 return false; 1179 return true; 1180 } 1181 1182 static inline void tcp_mib_init(struct net *net) 1183 { 1184 /* See RFC 2012 */ 1185 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1); 1186 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1187 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1188 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1); 1189 } 1190 1191 /* from STCP */ 1192 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1193 { 1194 tp->lost_skb_hint = NULL; 1195 } 1196 1197 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1198 { 1199 tcp_clear_retrans_hints_partial(tp); 1200 tp->retransmit_skb_hint = NULL; 1201 } 1202 1203 /* MD5 Signature */ 1204 struct crypto_hash; 1205 1206 union tcp_md5_addr { 1207 struct in_addr a4; 1208 #if IS_ENABLED(CONFIG_IPV6) 1209 struct in6_addr a6; 1210 #endif 1211 }; 1212 1213 /* - key database */ 1214 struct tcp_md5sig_key { 1215 struct hlist_node node; 1216 u8 keylen; 1217 u8 family; /* AF_INET or AF_INET6 */ 1218 union tcp_md5_addr addr; 1219 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1220 struct rcu_head rcu; 1221 }; 1222 1223 /* - sock block */ 1224 struct tcp_md5sig_info { 1225 struct hlist_head head; 1226 struct rcu_head rcu; 1227 }; 1228 1229 /* - pseudo header */ 1230 struct tcp4_pseudohdr { 1231 __be32 saddr; 1232 __be32 daddr; 1233 __u8 pad; 1234 __u8 protocol; 1235 __be16 len; 1236 }; 1237 1238 struct tcp6_pseudohdr { 1239 struct in6_addr saddr; 1240 struct in6_addr daddr; 1241 __be32 len; 1242 __be32 protocol; /* including padding */ 1243 }; 1244 1245 union tcp_md5sum_block { 1246 struct tcp4_pseudohdr ip4; 1247 #if IS_ENABLED(CONFIG_IPV6) 1248 struct tcp6_pseudohdr ip6; 1249 #endif 1250 }; 1251 1252 /* - pool: digest algorithm, hash description and scratch buffer */ 1253 struct tcp_md5sig_pool { 1254 struct hash_desc md5_desc; 1255 union tcp_md5sum_block md5_blk; 1256 }; 1257 1258 /* - functions */ 1259 int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key, 1260 const struct sock *sk, const struct request_sock *req, 1261 const struct sk_buff *skb); 1262 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1263 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp); 1264 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1265 int family); 1266 struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk, 1267 struct sock *addr_sk); 1268 1269 #ifdef CONFIG_TCP_MD5SIG 1270 struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk, 1271 const union tcp_md5_addr *addr, 1272 int family); 1273 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1274 #else 1275 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk, 1276 const union tcp_md5_addr *addr, 1277 int family) 1278 { 1279 return NULL; 1280 } 1281 #define tcp_twsk_md5_key(twsk) NULL 1282 #endif 1283 1284 bool tcp_alloc_md5sig_pool(void); 1285 1286 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1287 static inline void tcp_put_md5sig_pool(void) 1288 { 1289 local_bh_enable(); 1290 } 1291 1292 int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *); 1293 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1294 unsigned int header_len); 1295 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1296 const struct tcp_md5sig_key *key); 1297 1298 /* From tcp_fastopen.c */ 1299 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1300 struct tcp_fastopen_cookie *cookie, int *syn_loss, 1301 unsigned long *last_syn_loss); 1302 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1303 struct tcp_fastopen_cookie *cookie, bool syn_lost); 1304 struct tcp_fastopen_request { 1305 /* Fast Open cookie. Size 0 means a cookie request */ 1306 struct tcp_fastopen_cookie cookie; 1307 struct msghdr *data; /* data in MSG_FASTOPEN */ 1308 size_t size; 1309 int copied; /* queued in tcp_connect() */ 1310 }; 1311 void tcp_free_fastopen_req(struct tcp_sock *tp); 1312 1313 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; 1314 int tcp_fastopen_reset_cipher(void *key, unsigned int len); 1315 void tcp_fastopen_cookie_gen(__be32 src, __be32 dst, 1316 struct tcp_fastopen_cookie *foc); 1317 void tcp_fastopen_init_key_once(bool publish); 1318 #define TCP_FASTOPEN_KEY_LENGTH 16 1319 1320 /* Fastopen key context */ 1321 struct tcp_fastopen_context { 1322 struct crypto_cipher *tfm; 1323 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1324 struct rcu_head rcu; 1325 }; 1326 1327 /* write queue abstraction */ 1328 static inline void tcp_write_queue_purge(struct sock *sk) 1329 { 1330 struct sk_buff *skb; 1331 1332 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) 1333 sk_wmem_free_skb(sk, skb); 1334 sk_mem_reclaim(sk); 1335 tcp_clear_all_retrans_hints(tcp_sk(sk)); 1336 } 1337 1338 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1339 { 1340 return skb_peek(&sk->sk_write_queue); 1341 } 1342 1343 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1344 { 1345 return skb_peek_tail(&sk->sk_write_queue); 1346 } 1347 1348 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk, 1349 const struct sk_buff *skb) 1350 { 1351 return skb_queue_next(&sk->sk_write_queue, skb); 1352 } 1353 1354 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk, 1355 const struct sk_buff *skb) 1356 { 1357 return skb_queue_prev(&sk->sk_write_queue, skb); 1358 } 1359 1360 #define tcp_for_write_queue(skb, sk) \ 1361 skb_queue_walk(&(sk)->sk_write_queue, skb) 1362 1363 #define tcp_for_write_queue_from(skb, sk) \ 1364 skb_queue_walk_from(&(sk)->sk_write_queue, skb) 1365 1366 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1367 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1368 1369 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1370 { 1371 return sk->sk_send_head; 1372 } 1373 1374 static inline bool tcp_skb_is_last(const struct sock *sk, 1375 const struct sk_buff *skb) 1376 { 1377 return skb_queue_is_last(&sk->sk_write_queue, skb); 1378 } 1379 1380 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb) 1381 { 1382 if (tcp_skb_is_last(sk, skb)) 1383 sk->sk_send_head = NULL; 1384 else 1385 sk->sk_send_head = tcp_write_queue_next(sk, skb); 1386 } 1387 1388 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1389 { 1390 if (sk->sk_send_head == skb_unlinked) 1391 sk->sk_send_head = NULL; 1392 } 1393 1394 static inline void tcp_init_send_head(struct sock *sk) 1395 { 1396 sk->sk_send_head = NULL; 1397 } 1398 1399 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1400 { 1401 __skb_queue_tail(&sk->sk_write_queue, skb); 1402 } 1403 1404 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1405 { 1406 __tcp_add_write_queue_tail(sk, skb); 1407 1408 /* Queue it, remembering where we must start sending. */ 1409 if (sk->sk_send_head == NULL) { 1410 sk->sk_send_head = skb; 1411 1412 if (tcp_sk(sk)->highest_sack == NULL) 1413 tcp_sk(sk)->highest_sack = skb; 1414 } 1415 } 1416 1417 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb) 1418 { 1419 __skb_queue_head(&sk->sk_write_queue, skb); 1420 } 1421 1422 /* Insert buff after skb on the write queue of sk. */ 1423 static inline void tcp_insert_write_queue_after(struct sk_buff *skb, 1424 struct sk_buff *buff, 1425 struct sock *sk) 1426 { 1427 __skb_queue_after(&sk->sk_write_queue, skb, buff); 1428 } 1429 1430 /* Insert new before skb on the write queue of sk. */ 1431 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1432 struct sk_buff *skb, 1433 struct sock *sk) 1434 { 1435 __skb_queue_before(&sk->sk_write_queue, skb, new); 1436 1437 if (sk->sk_send_head == skb) 1438 sk->sk_send_head = new; 1439 } 1440 1441 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1442 { 1443 __skb_unlink(skb, &sk->sk_write_queue); 1444 } 1445 1446 static inline bool tcp_write_queue_empty(struct sock *sk) 1447 { 1448 return skb_queue_empty(&sk->sk_write_queue); 1449 } 1450 1451 static inline void tcp_push_pending_frames(struct sock *sk) 1452 { 1453 if (tcp_send_head(sk)) { 1454 struct tcp_sock *tp = tcp_sk(sk); 1455 1456 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1457 } 1458 } 1459 1460 /* Start sequence of the skb just after the highest skb with SACKed 1461 * bit, valid only if sacked_out > 0 or when the caller has ensured 1462 * validity by itself. 1463 */ 1464 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1465 { 1466 if (!tp->sacked_out) 1467 return tp->snd_una; 1468 1469 if (tp->highest_sack == NULL) 1470 return tp->snd_nxt; 1471 1472 return TCP_SKB_CB(tp->highest_sack)->seq; 1473 } 1474 1475 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1476 { 1477 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL : 1478 tcp_write_queue_next(sk, skb); 1479 } 1480 1481 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1482 { 1483 return tcp_sk(sk)->highest_sack; 1484 } 1485 1486 static inline void tcp_highest_sack_reset(struct sock *sk) 1487 { 1488 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk); 1489 } 1490 1491 /* Called when old skb is about to be deleted (to be combined with new skb) */ 1492 static inline void tcp_highest_sack_combine(struct sock *sk, 1493 struct sk_buff *old, 1494 struct sk_buff *new) 1495 { 1496 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack)) 1497 tcp_sk(sk)->highest_sack = new; 1498 } 1499 1500 /* Determines whether this is a thin stream (which may suffer from 1501 * increased latency). Used to trigger latency-reducing mechanisms. 1502 */ 1503 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1504 { 1505 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1506 } 1507 1508 /* /proc */ 1509 enum tcp_seq_states { 1510 TCP_SEQ_STATE_LISTENING, 1511 TCP_SEQ_STATE_OPENREQ, 1512 TCP_SEQ_STATE_ESTABLISHED, 1513 }; 1514 1515 int tcp_seq_open(struct inode *inode, struct file *file); 1516 1517 struct tcp_seq_afinfo { 1518 char *name; 1519 sa_family_t family; 1520 const struct file_operations *seq_fops; 1521 struct seq_operations seq_ops; 1522 }; 1523 1524 struct tcp_iter_state { 1525 struct seq_net_private p; 1526 sa_family_t family; 1527 enum tcp_seq_states state; 1528 struct sock *syn_wait_sk; 1529 int bucket, offset, sbucket, num; 1530 kuid_t uid; 1531 loff_t last_pos; 1532 }; 1533 1534 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1535 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1536 1537 extern struct request_sock_ops tcp_request_sock_ops; 1538 extern struct request_sock_ops tcp6_request_sock_ops; 1539 1540 void tcp_v4_destroy_sock(struct sock *sk); 1541 1542 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 1543 netdev_features_t features); 1544 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb); 1545 int tcp_gro_complete(struct sk_buff *skb); 1546 1547 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 1548 1549 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 1550 { 1551 return tp->notsent_lowat ?: sysctl_tcp_notsent_lowat; 1552 } 1553 1554 static inline bool tcp_stream_memory_free(const struct sock *sk) 1555 { 1556 const struct tcp_sock *tp = tcp_sk(sk); 1557 u32 notsent_bytes = tp->write_seq - tp->snd_nxt; 1558 1559 return notsent_bytes < tcp_notsent_lowat(tp); 1560 } 1561 1562 #ifdef CONFIG_PROC_FS 1563 int tcp4_proc_init(void); 1564 void tcp4_proc_exit(void); 1565 #endif 1566 1567 /* TCP af-specific functions */ 1568 struct tcp_sock_af_ops { 1569 #ifdef CONFIG_TCP_MD5SIG 1570 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk, 1571 struct sock *addr_sk); 1572 int (*calc_md5_hash) (char *location, 1573 struct tcp_md5sig_key *md5, 1574 const struct sock *sk, 1575 const struct request_sock *req, 1576 const struct sk_buff *skb); 1577 int (*md5_parse) (struct sock *sk, 1578 char __user *optval, 1579 int optlen); 1580 #endif 1581 }; 1582 1583 struct tcp_request_sock_ops { 1584 #ifdef CONFIG_TCP_MD5SIG 1585 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk, 1586 struct request_sock *req); 1587 int (*calc_md5_hash) (char *location, 1588 struct tcp_md5sig_key *md5, 1589 const struct sock *sk, 1590 const struct request_sock *req, 1591 const struct sk_buff *skb); 1592 #endif 1593 }; 1594 1595 int tcpv4_offload_init(void); 1596 1597 void tcp_v4_init(void); 1598 void tcp_init(void); 1599 1600 #endif /* _TCP_H */ 1601