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/crypto.h> 31 #include <linux/cryptohash.h> 32 #include <linux/kref.h> 33 #include <linux/ktime.h> 34 35 #include <net/inet_connection_sock.h> 36 #include <net/inet_timewait_sock.h> 37 #include <net/inet_hashtables.h> 38 #include <net/checksum.h> 39 #include <net/request_sock.h> 40 #include <net/sock.h> 41 #include <net/snmp.h> 42 #include <net/ip.h> 43 #include <net/tcp_states.h> 44 #include <net/inet_ecn.h> 45 #include <net/dst.h> 46 47 #include <linux/seq_file.h> 48 #include <linux/memcontrol.h> 49 50 extern struct inet_hashinfo tcp_hashinfo; 51 52 extern struct percpu_counter tcp_orphan_count; 53 void tcp_time_wait(struct sock *sk, int state, int timeo); 54 55 #define MAX_TCP_HEADER (128 + MAX_HEADER) 56 #define MAX_TCP_OPTION_SPACE 40 57 58 /* 59 * Never offer a window over 32767 without using window scaling. Some 60 * poor stacks do signed 16bit maths! 61 */ 62 #define MAX_TCP_WINDOW 32767U 63 64 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */ 65 #define TCP_MIN_MSS 88U 66 67 /* The least MTU to use for probing */ 68 #define TCP_BASE_MSS 512 69 70 /* After receiving this amount of duplicate ACKs fast retransmit starts. */ 71 #define TCP_FASTRETRANS_THRESH 3 72 73 /* Maximal reordering. */ 74 #define TCP_MAX_REORDERING 127 75 76 /* Maximal number of ACKs sent quickly to accelerate slow-start. */ 77 #define TCP_MAX_QUICKACKS 16U 78 79 /* urg_data states */ 80 #define TCP_URG_VALID 0x0100 81 #define TCP_URG_NOTYET 0x0200 82 #define TCP_URG_READ 0x0400 83 84 #define TCP_RETR1 3 /* 85 * This is how many retries it does before it 86 * tries to figure out if the gateway is 87 * down. Minimal RFC value is 3; it corresponds 88 * to ~3sec-8min depending on RTO. 89 */ 90 91 #define TCP_RETR2 15 /* 92 * This should take at least 93 * 90 minutes to time out. 94 * RFC1122 says that the limit is 100 sec. 95 * 15 is ~13-30min depending on RTO. 96 */ 97 98 #define TCP_SYN_RETRIES 6 /* This is how many retries are done 99 * when active opening a connection. 100 * RFC1122 says the minimum retry MUST 101 * be at least 180secs. Nevertheless 102 * this value is corresponding to 103 * 63secs of retransmission with the 104 * current initial RTO. 105 */ 106 107 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done 108 * when passive opening a connection. 109 * This is corresponding to 31secs of 110 * retransmission with the current 111 * initial RTO. 112 */ 113 114 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT 115 * state, about 60 seconds */ 116 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN 117 /* BSD style FIN_WAIT2 deadlock breaker. 118 * It used to be 3min, new value is 60sec, 119 * to combine FIN-WAIT-2 timeout with 120 * TIME-WAIT timer. 121 */ 122 123 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ 124 #if HZ >= 100 125 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */ 126 #define TCP_ATO_MIN ((unsigned)(HZ/25)) 127 #else 128 #define TCP_DELACK_MIN 4U 129 #define TCP_ATO_MIN 4U 130 #endif 131 #define TCP_RTO_MAX ((unsigned)(120*HZ)) 132 #define TCP_RTO_MIN ((unsigned)(HZ/5)) 133 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */ 134 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now 135 * used as a fallback RTO for the 136 * initial data transmission if no 137 * valid RTT sample has been acquired, 138 * most likely due to retrans in 3WHS. 139 */ 140 141 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes 142 * for local resources. 143 */ 144 145 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ 146 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ 147 #define TCP_KEEPALIVE_INTVL (75*HZ) 148 149 #define MAX_TCP_KEEPIDLE 32767 150 #define MAX_TCP_KEEPINTVL 32767 151 #define MAX_TCP_KEEPCNT 127 152 #define MAX_TCP_SYNCNT 127 153 154 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */ 155 156 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24) 157 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated 158 * after this time. It should be equal 159 * (or greater than) TCP_TIMEWAIT_LEN 160 * to provide reliability equal to one 161 * provided by timewait state. 162 */ 163 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host 164 * timestamps. It must be less than 165 * minimal timewait lifetime. 166 */ 167 /* 168 * TCP option 169 */ 170 171 #define TCPOPT_NOP 1 /* Padding */ 172 #define TCPOPT_EOL 0 /* End of options */ 173 #define TCPOPT_MSS 2 /* Segment size negotiating */ 174 #define TCPOPT_WINDOW 3 /* Window scaling */ 175 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ 176 #define TCPOPT_SACK 5 /* SACK Block */ 177 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ 178 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */ 179 #define TCPOPT_EXP 254 /* Experimental */ 180 /* Magic number to be after the option value for sharing TCP 181 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt 182 */ 183 #define TCPOPT_FASTOPEN_MAGIC 0xF989 184 185 /* 186 * TCP option lengths 187 */ 188 189 #define TCPOLEN_MSS 4 190 #define TCPOLEN_WINDOW 3 191 #define TCPOLEN_SACK_PERM 2 192 #define TCPOLEN_TIMESTAMP 10 193 #define TCPOLEN_MD5SIG 18 194 #define TCPOLEN_EXP_FASTOPEN_BASE 4 195 196 /* But this is what stacks really send out. */ 197 #define TCPOLEN_TSTAMP_ALIGNED 12 198 #define TCPOLEN_WSCALE_ALIGNED 4 199 #define TCPOLEN_SACKPERM_ALIGNED 4 200 #define TCPOLEN_SACK_BASE 2 201 #define TCPOLEN_SACK_BASE_ALIGNED 4 202 #define TCPOLEN_SACK_PERBLOCK 8 203 #define TCPOLEN_MD5SIG_ALIGNED 20 204 #define TCPOLEN_MSS_ALIGNED 4 205 206 /* Flags in tp->nonagle */ 207 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */ 208 #define TCP_NAGLE_CORK 2 /* Socket is corked */ 209 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */ 210 211 /* TCP thin-stream limits */ 212 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */ 213 214 /* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */ 215 #define TCP_INIT_CWND 10 216 217 /* Bit Flags for sysctl_tcp_fastopen */ 218 #define TFO_CLIENT_ENABLE 1 219 #define TFO_SERVER_ENABLE 2 220 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */ 221 222 /* Accept SYN data w/o any cookie option */ 223 #define TFO_SERVER_COOKIE_NOT_REQD 0x200 224 225 /* Force enable TFO on all listeners, i.e., not requiring the 226 * TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen. 227 */ 228 #define TFO_SERVER_WO_SOCKOPT1 0x400 229 #define TFO_SERVER_WO_SOCKOPT2 0x800 230 231 extern struct inet_timewait_death_row tcp_death_row; 232 233 /* sysctl variables for tcp */ 234 extern int sysctl_tcp_timestamps; 235 extern int sysctl_tcp_window_scaling; 236 extern int sysctl_tcp_sack; 237 extern int sysctl_tcp_fin_timeout; 238 extern int sysctl_tcp_keepalive_time; 239 extern int sysctl_tcp_keepalive_probes; 240 extern int sysctl_tcp_keepalive_intvl; 241 extern int sysctl_tcp_syn_retries; 242 extern int sysctl_tcp_synack_retries; 243 extern int sysctl_tcp_retries1; 244 extern int sysctl_tcp_retries2; 245 extern int sysctl_tcp_orphan_retries; 246 extern int sysctl_tcp_syncookies; 247 extern int sysctl_tcp_fastopen; 248 extern int sysctl_tcp_retrans_collapse; 249 extern int sysctl_tcp_stdurg; 250 extern int sysctl_tcp_rfc1337; 251 extern int sysctl_tcp_abort_on_overflow; 252 extern int sysctl_tcp_max_orphans; 253 extern int sysctl_tcp_fack; 254 extern int sysctl_tcp_reordering; 255 extern int sysctl_tcp_dsack; 256 extern long sysctl_tcp_mem[3]; 257 extern int sysctl_tcp_wmem[3]; 258 extern int sysctl_tcp_rmem[3]; 259 extern int sysctl_tcp_app_win; 260 extern int sysctl_tcp_adv_win_scale; 261 extern int sysctl_tcp_tw_reuse; 262 extern int sysctl_tcp_frto; 263 extern int sysctl_tcp_low_latency; 264 extern int sysctl_tcp_nometrics_save; 265 extern int sysctl_tcp_moderate_rcvbuf; 266 extern int sysctl_tcp_tso_win_divisor; 267 extern int sysctl_tcp_mtu_probing; 268 extern int sysctl_tcp_base_mss; 269 extern int sysctl_tcp_workaround_signed_windows; 270 extern int sysctl_tcp_slow_start_after_idle; 271 extern int sysctl_tcp_thin_linear_timeouts; 272 extern int sysctl_tcp_thin_dupack; 273 extern int sysctl_tcp_early_retrans; 274 extern int sysctl_tcp_limit_output_bytes; 275 extern int sysctl_tcp_challenge_ack_limit; 276 extern unsigned int sysctl_tcp_notsent_lowat; 277 extern int sysctl_tcp_min_tso_segs; 278 extern int sysctl_tcp_autocorking; 279 280 extern atomic_long_t tcp_memory_allocated; 281 extern struct percpu_counter tcp_sockets_allocated; 282 extern int tcp_memory_pressure; 283 284 /* 285 * The next routines deal with comparing 32 bit unsigned ints 286 * and worry about wraparound (automatic with unsigned arithmetic). 287 */ 288 289 static inline bool before(__u32 seq1, __u32 seq2) 290 { 291 return (__s32)(seq1-seq2) < 0; 292 } 293 #define after(seq2, seq1) before(seq1, seq2) 294 295 /* is s2<=s1<=s3 ? */ 296 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) 297 { 298 return seq3 - seq2 >= seq1 - seq2; 299 } 300 301 static inline bool tcp_out_of_memory(struct sock *sk) 302 { 303 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 304 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2)) 305 return true; 306 return false; 307 } 308 309 static inline bool tcp_too_many_orphans(struct sock *sk, int shift) 310 { 311 struct percpu_counter *ocp = sk->sk_prot->orphan_count; 312 int orphans = percpu_counter_read_positive(ocp); 313 314 if (orphans << shift > sysctl_tcp_max_orphans) { 315 orphans = percpu_counter_sum_positive(ocp); 316 if (orphans << shift > sysctl_tcp_max_orphans) 317 return true; 318 } 319 return false; 320 } 321 322 bool tcp_check_oom(struct sock *sk, int shift); 323 324 /* syncookies: remember time of last synqueue overflow */ 325 static inline void tcp_synq_overflow(struct sock *sk) 326 { 327 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies; 328 } 329 330 /* syncookies: no recent synqueue overflow on this listening socket? */ 331 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 332 { 333 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 334 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK); 335 } 336 337 extern struct proto tcp_prot; 338 339 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 340 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field) 341 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 342 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val) 343 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 344 345 void tcp_tasklet_init(void); 346 347 void tcp_v4_err(struct sk_buff *skb, u32); 348 349 void tcp_shutdown(struct sock *sk, int how); 350 351 void tcp_v4_early_demux(struct sk_buff *skb); 352 int tcp_v4_rcv(struct sk_buff *skb); 353 354 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 355 int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 356 size_t size); 357 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, 358 int flags); 359 void tcp_release_cb(struct sock *sk); 360 void tcp_wfree(struct sk_buff *skb); 361 void tcp_write_timer_handler(struct sock *sk); 362 void tcp_delack_timer_handler(struct sock *sk); 363 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 364 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb, 365 const struct tcphdr *th, unsigned int len); 366 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 367 const struct tcphdr *th, unsigned int len); 368 void tcp_rcv_space_adjust(struct sock *sk); 369 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 370 void tcp_twsk_destructor(struct sock *sk); 371 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 372 struct pipe_inode_info *pipe, size_t len, 373 unsigned int flags); 374 375 static inline void tcp_dec_quickack_mode(struct sock *sk, 376 const unsigned int pkts) 377 { 378 struct inet_connection_sock *icsk = inet_csk(sk); 379 380 if (icsk->icsk_ack.quick) { 381 if (pkts >= icsk->icsk_ack.quick) { 382 icsk->icsk_ack.quick = 0; 383 /* Leaving quickack mode we deflate ATO. */ 384 icsk->icsk_ack.ato = TCP_ATO_MIN; 385 } else 386 icsk->icsk_ack.quick -= pkts; 387 } 388 } 389 390 #define TCP_ECN_OK 1 391 #define TCP_ECN_QUEUE_CWR 2 392 #define TCP_ECN_DEMAND_CWR 4 393 #define TCP_ECN_SEEN 8 394 395 enum tcp_tw_status { 396 TCP_TW_SUCCESS = 0, 397 TCP_TW_RST = 1, 398 TCP_TW_ACK = 2, 399 TCP_TW_SYN = 3 400 }; 401 402 403 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 404 struct sk_buff *skb, 405 const struct tcphdr *th); 406 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 407 struct request_sock *req, struct request_sock **prev, 408 bool fastopen); 409 int tcp_child_process(struct sock *parent, struct sock *child, 410 struct sk_buff *skb); 411 void tcp_enter_loss(struct sock *sk); 412 void tcp_clear_retrans(struct tcp_sock *tp); 413 void tcp_update_metrics(struct sock *sk); 414 void tcp_init_metrics(struct sock *sk); 415 void tcp_metrics_init(void); 416 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, 417 bool paws_check, bool timestamps); 418 bool tcp_remember_stamp(struct sock *sk); 419 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw); 420 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst); 421 void tcp_disable_fack(struct tcp_sock *tp); 422 void tcp_close(struct sock *sk, long timeout); 423 void tcp_init_sock(struct sock *sk); 424 unsigned int tcp_poll(struct file *file, struct socket *sock, 425 struct poll_table_struct *wait); 426 int tcp_getsockopt(struct sock *sk, int level, int optname, 427 char __user *optval, int __user *optlen); 428 int tcp_setsockopt(struct sock *sk, int level, int optname, 429 char __user *optval, unsigned int optlen); 430 int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 431 char __user *optval, int __user *optlen); 432 int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 433 char __user *optval, unsigned int optlen); 434 void tcp_set_keepalive(struct sock *sk, int val); 435 void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req); 436 int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 437 size_t len, int nonblock, int flags, int *addr_len); 438 void tcp_parse_options(const struct sk_buff *skb, 439 struct tcp_options_received *opt_rx, 440 int estab, struct tcp_fastopen_cookie *foc); 441 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); 442 443 /* 444 * TCP v4 functions exported for the inet6 API 445 */ 446 447 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 448 void tcp_v4_mtu_reduced(struct sock *sk); 449 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 450 struct sock *tcp_create_openreq_child(struct sock *sk, 451 struct request_sock *req, 452 struct sk_buff *skb); 453 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb, 454 struct request_sock *req, 455 struct dst_entry *dst); 456 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 457 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); 458 int tcp_connect(struct sock *sk); 459 struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, 460 struct request_sock *req, 461 struct tcp_fastopen_cookie *foc); 462 int tcp_disconnect(struct sock *sk, int flags); 463 464 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 465 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 466 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); 467 468 /* From syncookies.c */ 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 2 482 483 static inline u32 tcp_cookie_time(void) 484 { 485 u64 val = get_jiffies_64(); 486 487 do_div(val, 60 * HZ); 488 return val; 489 } 490 491 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, 492 u16 *mssp); 493 __u32 cookie_v4_init_sequence(struct sock *sk, const struct sk_buff *skb, 494 __u16 *mss); 495 #endif 496 497 __u32 cookie_init_timestamp(struct request_sock *req); 498 bool cookie_check_timestamp(struct tcp_options_received *opt, struct net *net, 499 bool *ecn_ok); 500 501 /* From net/ipv6/syncookies.c */ 502 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th, 503 u32 cookie); 504 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 505 #ifdef CONFIG_SYN_COOKIES 506 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph, 507 const struct tcphdr *th, u16 *mssp); 508 __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb, 509 __u16 *mss); 510 #endif 511 /* tcp_output.c */ 512 513 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 514 int nonagle); 515 bool tcp_may_send_now(struct sock *sk); 516 int __tcp_retransmit_skb(struct sock *, struct sk_buff *); 517 int tcp_retransmit_skb(struct sock *, struct sk_buff *); 518 void tcp_retransmit_timer(struct sock *sk); 519 void tcp_xmit_retransmit_queue(struct sock *); 520 void tcp_simple_retransmit(struct sock *); 521 int tcp_trim_head(struct sock *, struct sk_buff *, u32); 522 int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t); 523 524 void tcp_send_probe0(struct sock *); 525 void tcp_send_partial(struct sock *); 526 int tcp_write_wakeup(struct sock *); 527 void tcp_send_fin(struct sock *sk); 528 void tcp_send_active_reset(struct sock *sk, gfp_t priority); 529 int tcp_send_synack(struct sock *); 530 bool tcp_syn_flood_action(struct sock *sk, const struct sk_buff *skb, 531 const char *proto); 532 void tcp_push_one(struct sock *, unsigned int mss_now); 533 void tcp_send_ack(struct sock *sk); 534 void tcp_send_delayed_ack(struct sock *sk); 535 void tcp_send_loss_probe(struct sock *sk); 536 bool tcp_schedule_loss_probe(struct sock *sk); 537 538 /* tcp_input.c */ 539 void tcp_resume_early_retransmit(struct sock *sk); 540 void tcp_rearm_rto(struct sock *sk); 541 void tcp_reset(struct sock *sk); 542 543 /* tcp_timer.c */ 544 void tcp_init_xmit_timers(struct sock *); 545 static inline void tcp_clear_xmit_timers(struct sock *sk) 546 { 547 inet_csk_clear_xmit_timers(sk); 548 } 549 550 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 551 unsigned int tcp_current_mss(struct sock *sk); 552 553 /* Bound MSS / TSO packet size with the half of the window */ 554 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 555 { 556 int cutoff; 557 558 /* When peer uses tiny windows, there is no use in packetizing 559 * to sub-MSS pieces for the sake of SWS or making sure there 560 * are enough packets in the pipe for fast recovery. 561 * 562 * On the other hand, for extremely large MSS devices, handling 563 * smaller than MSS windows in this way does make sense. 564 */ 565 if (tp->max_window >= 512) 566 cutoff = (tp->max_window >> 1); 567 else 568 cutoff = tp->max_window; 569 570 if (cutoff && pktsize > cutoff) 571 return max_t(int, cutoff, 68U - tp->tcp_header_len); 572 else 573 return pktsize; 574 } 575 576 /* tcp.c */ 577 void tcp_get_info(const struct sock *, struct tcp_info *); 578 579 /* Read 'sendfile()'-style from a TCP socket */ 580 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *, 581 unsigned int, size_t); 582 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 583 sk_read_actor_t recv_actor); 584 585 void tcp_initialize_rcv_mss(struct sock *sk); 586 587 int tcp_mtu_to_mss(struct sock *sk, int pmtu); 588 int tcp_mss_to_mtu(struct sock *sk, int mss); 589 void tcp_mtup_init(struct sock *sk); 590 void tcp_init_buffer_space(struct sock *sk); 591 592 static inline void tcp_bound_rto(const struct sock *sk) 593 { 594 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 595 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 596 } 597 598 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 599 { 600 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us); 601 } 602 603 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 604 { 605 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 606 ntohl(TCP_FLAG_ACK) | 607 snd_wnd); 608 } 609 610 static inline void tcp_fast_path_on(struct tcp_sock *tp) 611 { 612 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 613 } 614 615 static inline void tcp_fast_path_check(struct sock *sk) 616 { 617 struct tcp_sock *tp = tcp_sk(sk); 618 619 if (skb_queue_empty(&tp->out_of_order_queue) && 620 tp->rcv_wnd && 621 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 622 !tp->urg_data) 623 tcp_fast_path_on(tp); 624 } 625 626 /* Compute the actual rto_min value */ 627 static inline u32 tcp_rto_min(struct sock *sk) 628 { 629 const struct dst_entry *dst = __sk_dst_get(sk); 630 u32 rto_min = TCP_RTO_MIN; 631 632 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 633 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 634 return rto_min; 635 } 636 637 static inline u32 tcp_rto_min_us(struct sock *sk) 638 { 639 return jiffies_to_usecs(tcp_rto_min(sk)); 640 } 641 642 /* Compute the actual receive window we are currently advertising. 643 * Rcv_nxt can be after the window if our peer push more data 644 * than the offered window. 645 */ 646 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 647 { 648 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 649 650 if (win < 0) 651 win = 0; 652 return (u32) win; 653 } 654 655 /* Choose a new window, without checks for shrinking, and without 656 * scaling applied to the result. The caller does these things 657 * if necessary. This is a "raw" window selection. 658 */ 659 u32 __tcp_select_window(struct sock *sk); 660 661 void tcp_send_window_probe(struct sock *sk); 662 663 /* TCP timestamps are only 32-bits, this causes a slight 664 * complication on 64-bit systems since we store a snapshot 665 * of jiffies in the buffer control blocks below. We decided 666 * to use only the low 32-bits of jiffies and hide the ugly 667 * casts with the following macro. 668 */ 669 #define tcp_time_stamp ((__u32)(jiffies)) 670 671 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) 672 { 673 return skb->skb_mstamp.stamp_jiffies; 674 } 675 676 677 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 678 679 #define TCPHDR_FIN 0x01 680 #define TCPHDR_SYN 0x02 681 #define TCPHDR_RST 0x04 682 #define TCPHDR_PSH 0x08 683 #define TCPHDR_ACK 0x10 684 #define TCPHDR_URG 0x20 685 #define TCPHDR_ECE 0x40 686 #define TCPHDR_CWR 0x80 687 688 /* This is what the send packet queuing engine uses to pass 689 * TCP per-packet control information to the transmission code. 690 * We also store the host-order sequence numbers in here too. 691 * This is 44 bytes if IPV6 is enabled. 692 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 693 */ 694 struct tcp_skb_cb { 695 __u32 seq; /* Starting sequence number */ 696 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 697 union { 698 /* Note : tcp_tw_isn is used in input path only 699 * (isn chosen by tcp_timewait_state_process()) 700 * 701 * tcp_gso_segs is used in write queue only, 702 * cf tcp_skb_pcount() 703 */ 704 __u32 tcp_tw_isn; 705 __u32 tcp_gso_segs; 706 }; 707 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 708 709 __u8 sacked; /* State flags for SACK/FACK. */ 710 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 711 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 712 #define TCPCB_LOST 0x04 /* SKB is lost */ 713 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 714 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */ 715 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 716 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \ 717 TCPCB_REPAIRED) 718 719 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 720 /* 1 byte hole */ 721 __u32 ack_seq; /* Sequence number ACK'd */ 722 union { 723 struct inet_skb_parm h4; 724 #if IS_ENABLED(CONFIG_IPV6) 725 struct inet6_skb_parm h6; 726 #endif 727 } header; /* For incoming frames */ 728 }; 729 730 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 731 732 733 #if IS_ENABLED(CONFIG_IPV6) 734 /* This is the variant of inet6_iif() that must be used by TCP, 735 * as TCP moves IP6CB into a different location in skb->cb[] 736 */ 737 static inline int tcp_v6_iif(const struct sk_buff *skb) 738 { 739 return TCP_SKB_CB(skb)->header.h6.iif; 740 } 741 #endif 742 743 /* Due to TSO, an SKB can be composed of multiple actual 744 * packets. To keep these tracked properly, we use this. 745 */ 746 static inline int tcp_skb_pcount(const struct sk_buff *skb) 747 { 748 return TCP_SKB_CB(skb)->tcp_gso_segs; 749 } 750 751 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 752 { 753 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 754 } 755 756 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 757 { 758 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 759 } 760 761 /* This is valid iff tcp_skb_pcount() > 1. */ 762 static inline int tcp_skb_mss(const struct sk_buff *skb) 763 { 764 return skb_shinfo(skb)->gso_size; 765 } 766 767 /* Events passed to congestion control interface */ 768 enum tcp_ca_event { 769 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 770 CA_EVENT_CWND_RESTART, /* congestion window restart */ 771 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 772 CA_EVENT_LOSS, /* loss timeout */ 773 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 774 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 775 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */ 776 CA_EVENT_NON_DELAYED_ACK, 777 }; 778 779 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 780 enum tcp_ca_ack_event_flags { 781 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 782 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 783 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 784 }; 785 786 /* 787 * Interface for adding new TCP congestion control handlers 788 */ 789 #define TCP_CA_NAME_MAX 16 790 #define TCP_CA_MAX 128 791 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 792 793 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 794 #define TCP_CONG_NON_RESTRICTED 0x1 795 /* Requires ECN/ECT set on all packets */ 796 #define TCP_CONG_NEEDS_ECN 0x2 797 798 struct tcp_congestion_ops { 799 struct list_head list; 800 unsigned long flags; 801 802 /* initialize private data (optional) */ 803 void (*init)(struct sock *sk); 804 /* cleanup private data (optional) */ 805 void (*release)(struct sock *sk); 806 807 /* return slow start threshold (required) */ 808 u32 (*ssthresh)(struct sock *sk); 809 /* do new cwnd calculation (required) */ 810 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 811 /* call before changing ca_state (optional) */ 812 void (*set_state)(struct sock *sk, u8 new_state); 813 /* call when cwnd event occurs (optional) */ 814 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 815 /* call when ack arrives (optional) */ 816 void (*in_ack_event)(struct sock *sk, u32 flags); 817 /* new value of cwnd after loss (optional) */ 818 u32 (*undo_cwnd)(struct sock *sk); 819 /* hook for packet ack accounting (optional) */ 820 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us); 821 /* get info for inet_diag (optional) */ 822 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb); 823 824 char name[TCP_CA_NAME_MAX]; 825 struct module *owner; 826 }; 827 828 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 829 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 830 831 void tcp_assign_congestion_control(struct sock *sk); 832 void tcp_init_congestion_control(struct sock *sk); 833 void tcp_cleanup_congestion_control(struct sock *sk); 834 int tcp_set_default_congestion_control(const char *name); 835 void tcp_get_default_congestion_control(char *name); 836 void tcp_get_available_congestion_control(char *buf, size_t len); 837 void tcp_get_allowed_congestion_control(char *buf, size_t len); 838 int tcp_set_allowed_congestion_control(char *allowed); 839 int tcp_set_congestion_control(struct sock *sk, const char *name); 840 void tcp_slow_start(struct tcp_sock *tp, u32 acked); 841 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w); 842 843 u32 tcp_reno_ssthresh(struct sock *sk); 844 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 845 extern struct tcp_congestion_ops tcp_reno; 846 847 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 848 { 849 const struct inet_connection_sock *icsk = inet_csk(sk); 850 851 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 852 } 853 854 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 855 { 856 struct inet_connection_sock *icsk = inet_csk(sk); 857 858 if (icsk->icsk_ca_ops->set_state) 859 icsk->icsk_ca_ops->set_state(sk, ca_state); 860 icsk->icsk_ca_state = ca_state; 861 } 862 863 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 864 { 865 const struct inet_connection_sock *icsk = inet_csk(sk); 866 867 if (icsk->icsk_ca_ops->cwnd_event) 868 icsk->icsk_ca_ops->cwnd_event(sk, event); 869 } 870 871 /* These functions determine how the current flow behaves in respect of SACK 872 * handling. SACK is negotiated with the peer, and therefore it can vary 873 * between different flows. 874 * 875 * tcp_is_sack - SACK enabled 876 * tcp_is_reno - No SACK 877 * tcp_is_fack - FACK enabled, implies SACK enabled 878 */ 879 static inline int tcp_is_sack(const struct tcp_sock *tp) 880 { 881 return tp->rx_opt.sack_ok; 882 } 883 884 static inline bool tcp_is_reno(const struct tcp_sock *tp) 885 { 886 return !tcp_is_sack(tp); 887 } 888 889 static inline bool tcp_is_fack(const struct tcp_sock *tp) 890 { 891 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED; 892 } 893 894 static inline void tcp_enable_fack(struct tcp_sock *tp) 895 { 896 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED; 897 } 898 899 /* TCP early-retransmit (ER) is similar to but more conservative than 900 * the thin-dupack feature. Enable ER only if thin-dupack is disabled. 901 */ 902 static inline void tcp_enable_early_retrans(struct tcp_sock *tp) 903 { 904 tp->do_early_retrans = sysctl_tcp_early_retrans && 905 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack && 906 sysctl_tcp_reordering == 3; 907 } 908 909 static inline void tcp_disable_early_retrans(struct tcp_sock *tp) 910 { 911 tp->do_early_retrans = 0; 912 } 913 914 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 915 { 916 return tp->sacked_out + tp->lost_out; 917 } 918 919 /* This determines how many packets are "in the network" to the best 920 * of our knowledge. In many cases it is conservative, but where 921 * detailed information is available from the receiver (via SACK 922 * blocks etc.) we can make more aggressive calculations. 923 * 924 * Use this for decisions involving congestion control, use just 925 * tp->packets_out to determine if the send queue is empty or not. 926 * 927 * Read this equation as: 928 * 929 * "Packets sent once on transmission queue" MINUS 930 * "Packets left network, but not honestly ACKed yet" PLUS 931 * "Packets fast retransmitted" 932 */ 933 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 934 { 935 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 936 } 937 938 #define TCP_INFINITE_SSTHRESH 0x7fffffff 939 940 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 941 { 942 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 943 } 944 945 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 946 { 947 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 948 (1 << inet_csk(sk)->icsk_ca_state); 949 } 950 951 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 952 * The exception is cwnd reduction phase, when cwnd is decreasing towards 953 * ssthresh. 954 */ 955 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 956 { 957 const struct tcp_sock *tp = tcp_sk(sk); 958 959 if (tcp_in_cwnd_reduction(sk)) 960 return tp->snd_ssthresh; 961 else 962 return max(tp->snd_ssthresh, 963 ((tp->snd_cwnd >> 1) + 964 (tp->snd_cwnd >> 2))); 965 } 966 967 /* Use define here intentionally to get WARN_ON location shown at the caller */ 968 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 969 970 void tcp_enter_cwr(struct sock *sk); 971 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 972 973 /* The maximum number of MSS of available cwnd for which TSO defers 974 * sending if not using sysctl_tcp_tso_win_divisor. 975 */ 976 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 977 { 978 return 3; 979 } 980 981 /* Slow start with delack produces 3 packets of burst, so that 982 * it is safe "de facto". This will be the default - same as 983 * the default reordering threshold - but if reordering increases, 984 * we must be able to allow cwnd to burst at least this much in order 985 * to not pull it back when holes are filled. 986 */ 987 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp) 988 { 989 return tp->reordering; 990 } 991 992 /* Returns end sequence number of the receiver's advertised window */ 993 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 994 { 995 return tp->snd_una + tp->snd_wnd; 996 } 997 998 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 999 * flexible approach. The RFC suggests cwnd should not be raised unless 1000 * it was fully used previously. And that's exactly what we do in 1001 * congestion avoidance mode. But in slow start we allow cwnd to grow 1002 * as long as the application has used half the cwnd. 1003 * Example : 1004 * cwnd is 10 (IW10), but application sends 9 frames. 1005 * We allow cwnd to reach 18 when all frames are ACKed. 1006 * This check is safe because it's as aggressive as slow start which already 1007 * risks 100% overshoot. The advantage is that we discourage application to 1008 * either send more filler packets or data to artificially blow up the cwnd 1009 * usage, and allow application-limited process to probe bw more aggressively. 1010 */ 1011 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1012 { 1013 const struct tcp_sock *tp = tcp_sk(sk); 1014 1015 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1016 if (tp->snd_cwnd <= tp->snd_ssthresh) 1017 return tp->snd_cwnd < 2 * tp->max_packets_out; 1018 1019 return tp->is_cwnd_limited; 1020 } 1021 1022 static inline void tcp_check_probe_timer(struct sock *sk) 1023 { 1024 const struct tcp_sock *tp = tcp_sk(sk); 1025 const struct inet_connection_sock *icsk = inet_csk(sk); 1026 1027 if (!tp->packets_out && !icsk->icsk_pending) 1028 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1029 icsk->icsk_rto, TCP_RTO_MAX); 1030 } 1031 1032 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1033 { 1034 tp->snd_wl1 = seq; 1035 } 1036 1037 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1038 { 1039 tp->snd_wl1 = seq; 1040 } 1041 1042 /* 1043 * Calculate(/check) TCP checksum 1044 */ 1045 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1046 __be32 daddr, __wsum base) 1047 { 1048 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1049 } 1050 1051 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1052 { 1053 return __skb_checksum_complete(skb); 1054 } 1055 1056 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1057 { 1058 return !skb_csum_unnecessary(skb) && 1059 __tcp_checksum_complete(skb); 1060 } 1061 1062 /* Prequeue for VJ style copy to user, combined with checksumming. */ 1063 1064 static inline void tcp_prequeue_init(struct tcp_sock *tp) 1065 { 1066 tp->ucopy.task = NULL; 1067 tp->ucopy.len = 0; 1068 tp->ucopy.memory = 0; 1069 skb_queue_head_init(&tp->ucopy.prequeue); 1070 } 1071 1072 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb); 1073 1074 #undef STATE_TRACE 1075 1076 #ifdef STATE_TRACE 1077 static const char *statename[]={ 1078 "Unused","Established","Syn Sent","Syn Recv", 1079 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1080 "Close Wait","Last ACK","Listen","Closing" 1081 }; 1082 #endif 1083 void tcp_set_state(struct sock *sk, int state); 1084 1085 void tcp_done(struct sock *sk); 1086 1087 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1088 { 1089 rx_opt->dsack = 0; 1090 rx_opt->num_sacks = 0; 1091 } 1092 1093 u32 tcp_default_init_rwnd(u32 mss); 1094 1095 /* Determine a window scaling and initial window to offer. */ 1096 void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd, 1097 __u32 *window_clamp, int wscale_ok, 1098 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1099 1100 static inline int tcp_win_from_space(int space) 1101 { 1102 return sysctl_tcp_adv_win_scale<=0 ? 1103 (space>>(-sysctl_tcp_adv_win_scale)) : 1104 space - (space>>sysctl_tcp_adv_win_scale); 1105 } 1106 1107 /* Note: caller must be prepared to deal with negative returns */ 1108 static inline int tcp_space(const struct sock *sk) 1109 { 1110 return tcp_win_from_space(sk->sk_rcvbuf - 1111 atomic_read(&sk->sk_rmem_alloc)); 1112 } 1113 1114 static inline int tcp_full_space(const struct sock *sk) 1115 { 1116 return tcp_win_from_space(sk->sk_rcvbuf); 1117 } 1118 1119 static inline void tcp_openreq_init(struct request_sock *req, 1120 struct tcp_options_received *rx_opt, 1121 struct sk_buff *skb, struct sock *sk) 1122 { 1123 struct inet_request_sock *ireq = inet_rsk(req); 1124 1125 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */ 1126 req->cookie_ts = 0; 1127 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq; 1128 tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1; 1129 tcp_rsk(req)->snt_synack = tcp_time_stamp; 1130 req->mss = rx_opt->mss_clamp; 1131 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0; 1132 ireq->tstamp_ok = rx_opt->tstamp_ok; 1133 ireq->sack_ok = rx_opt->sack_ok; 1134 ireq->snd_wscale = rx_opt->snd_wscale; 1135 ireq->wscale_ok = rx_opt->wscale_ok; 1136 ireq->acked = 0; 1137 ireq->ecn_ok = 0; 1138 ireq->ir_rmt_port = tcp_hdr(skb)->source; 1139 ireq->ir_num = ntohs(tcp_hdr(skb)->dest); 1140 ireq->ir_mark = inet_request_mark(sk, skb); 1141 } 1142 1143 extern void tcp_openreq_init_rwin(struct request_sock *req, 1144 struct sock *sk, struct dst_entry *dst); 1145 1146 void tcp_enter_memory_pressure(struct sock *sk); 1147 1148 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1149 { 1150 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl; 1151 } 1152 1153 static inline int keepalive_time_when(const struct tcp_sock *tp) 1154 { 1155 return tp->keepalive_time ? : sysctl_tcp_keepalive_time; 1156 } 1157 1158 static inline int keepalive_probes(const struct tcp_sock *tp) 1159 { 1160 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes; 1161 } 1162 1163 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1164 { 1165 const struct inet_connection_sock *icsk = &tp->inet_conn; 1166 1167 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime, 1168 tcp_time_stamp - tp->rcv_tstamp); 1169 } 1170 1171 static inline int tcp_fin_time(const struct sock *sk) 1172 { 1173 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout; 1174 const int rto = inet_csk(sk)->icsk_rto; 1175 1176 if (fin_timeout < (rto << 2) - (rto >> 1)) 1177 fin_timeout = (rto << 2) - (rto >> 1); 1178 1179 return fin_timeout; 1180 } 1181 1182 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1183 int paws_win) 1184 { 1185 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1186 return true; 1187 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1188 return true; 1189 /* 1190 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1191 * then following tcp messages have valid values. Ignore 0 value, 1192 * or else 'negative' tsval might forbid us to accept their packets. 1193 */ 1194 if (!rx_opt->ts_recent) 1195 return true; 1196 return false; 1197 } 1198 1199 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1200 int rst) 1201 { 1202 if (tcp_paws_check(rx_opt, 0)) 1203 return false; 1204 1205 /* RST segments are not recommended to carry timestamp, 1206 and, if they do, it is recommended to ignore PAWS because 1207 "their cleanup function should take precedence over timestamps." 1208 Certainly, it is mistake. It is necessary to understand the reasons 1209 of this constraint to relax it: if peer reboots, clock may go 1210 out-of-sync and half-open connections will not be reset. 1211 Actually, the problem would be not existing if all 1212 the implementations followed draft about maintaining clock 1213 via reboots. Linux-2.2 DOES NOT! 1214 1215 However, we can relax time bounds for RST segments to MSL. 1216 */ 1217 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1218 return false; 1219 return true; 1220 } 1221 1222 static inline void tcp_mib_init(struct net *net) 1223 { 1224 /* See RFC 2012 */ 1225 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1); 1226 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1227 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1228 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1); 1229 } 1230 1231 /* from STCP */ 1232 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1233 { 1234 tp->lost_skb_hint = NULL; 1235 } 1236 1237 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1238 { 1239 tcp_clear_retrans_hints_partial(tp); 1240 tp->retransmit_skb_hint = NULL; 1241 } 1242 1243 /* MD5 Signature */ 1244 struct crypto_hash; 1245 1246 union tcp_md5_addr { 1247 struct in_addr a4; 1248 #if IS_ENABLED(CONFIG_IPV6) 1249 struct in6_addr a6; 1250 #endif 1251 }; 1252 1253 /* - key database */ 1254 struct tcp_md5sig_key { 1255 struct hlist_node node; 1256 u8 keylen; 1257 u8 family; /* AF_INET or AF_INET6 */ 1258 union tcp_md5_addr addr; 1259 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1260 struct rcu_head rcu; 1261 }; 1262 1263 /* - sock block */ 1264 struct tcp_md5sig_info { 1265 struct hlist_head head; 1266 struct rcu_head rcu; 1267 }; 1268 1269 /* - pseudo header */ 1270 struct tcp4_pseudohdr { 1271 __be32 saddr; 1272 __be32 daddr; 1273 __u8 pad; 1274 __u8 protocol; 1275 __be16 len; 1276 }; 1277 1278 struct tcp6_pseudohdr { 1279 struct in6_addr saddr; 1280 struct in6_addr daddr; 1281 __be32 len; 1282 __be32 protocol; /* including padding */ 1283 }; 1284 1285 union tcp_md5sum_block { 1286 struct tcp4_pseudohdr ip4; 1287 #if IS_ENABLED(CONFIG_IPV6) 1288 struct tcp6_pseudohdr ip6; 1289 #endif 1290 }; 1291 1292 /* - pool: digest algorithm, hash description and scratch buffer */ 1293 struct tcp_md5sig_pool { 1294 struct hash_desc md5_desc; 1295 union tcp_md5sum_block md5_blk; 1296 }; 1297 1298 /* - functions */ 1299 int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key, 1300 const struct sock *sk, const struct request_sock *req, 1301 const struct sk_buff *skb); 1302 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1303 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp); 1304 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1305 int family); 1306 struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk, 1307 struct sock *addr_sk); 1308 1309 #ifdef CONFIG_TCP_MD5SIG 1310 struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk, 1311 const union tcp_md5_addr *addr, 1312 int family); 1313 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1314 #else 1315 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk, 1316 const union tcp_md5_addr *addr, 1317 int family) 1318 { 1319 return NULL; 1320 } 1321 #define tcp_twsk_md5_key(twsk) NULL 1322 #endif 1323 1324 bool tcp_alloc_md5sig_pool(void); 1325 1326 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1327 static inline void tcp_put_md5sig_pool(void) 1328 { 1329 local_bh_enable(); 1330 } 1331 1332 int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *); 1333 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1334 unsigned int header_len); 1335 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1336 const struct tcp_md5sig_key *key); 1337 1338 /* From tcp_fastopen.c */ 1339 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1340 struct tcp_fastopen_cookie *cookie, int *syn_loss, 1341 unsigned long *last_syn_loss); 1342 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1343 struct tcp_fastopen_cookie *cookie, bool syn_lost); 1344 struct tcp_fastopen_request { 1345 /* Fast Open cookie. Size 0 means a cookie request */ 1346 struct tcp_fastopen_cookie cookie; 1347 struct msghdr *data; /* data in MSG_FASTOPEN */ 1348 size_t size; 1349 int copied; /* queued in tcp_connect() */ 1350 }; 1351 void tcp_free_fastopen_req(struct tcp_sock *tp); 1352 1353 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; 1354 int tcp_fastopen_reset_cipher(void *key, unsigned int len); 1355 bool tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1356 struct request_sock *req, 1357 struct tcp_fastopen_cookie *foc, 1358 struct dst_entry *dst); 1359 void tcp_fastopen_init_key_once(bool publish); 1360 #define TCP_FASTOPEN_KEY_LENGTH 16 1361 1362 /* Fastopen key context */ 1363 struct tcp_fastopen_context { 1364 struct crypto_cipher *tfm; 1365 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1366 struct rcu_head rcu; 1367 }; 1368 1369 /* write queue abstraction */ 1370 static inline void tcp_write_queue_purge(struct sock *sk) 1371 { 1372 struct sk_buff *skb; 1373 1374 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) 1375 sk_wmem_free_skb(sk, skb); 1376 sk_mem_reclaim(sk); 1377 tcp_clear_all_retrans_hints(tcp_sk(sk)); 1378 } 1379 1380 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1381 { 1382 return skb_peek(&sk->sk_write_queue); 1383 } 1384 1385 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1386 { 1387 return skb_peek_tail(&sk->sk_write_queue); 1388 } 1389 1390 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk, 1391 const struct sk_buff *skb) 1392 { 1393 return skb_queue_next(&sk->sk_write_queue, skb); 1394 } 1395 1396 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk, 1397 const struct sk_buff *skb) 1398 { 1399 return skb_queue_prev(&sk->sk_write_queue, skb); 1400 } 1401 1402 #define tcp_for_write_queue(skb, sk) \ 1403 skb_queue_walk(&(sk)->sk_write_queue, skb) 1404 1405 #define tcp_for_write_queue_from(skb, sk) \ 1406 skb_queue_walk_from(&(sk)->sk_write_queue, skb) 1407 1408 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1409 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1410 1411 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1412 { 1413 return sk->sk_send_head; 1414 } 1415 1416 static inline bool tcp_skb_is_last(const struct sock *sk, 1417 const struct sk_buff *skb) 1418 { 1419 return skb_queue_is_last(&sk->sk_write_queue, skb); 1420 } 1421 1422 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb) 1423 { 1424 if (tcp_skb_is_last(sk, skb)) 1425 sk->sk_send_head = NULL; 1426 else 1427 sk->sk_send_head = tcp_write_queue_next(sk, skb); 1428 } 1429 1430 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1431 { 1432 if (sk->sk_send_head == skb_unlinked) 1433 sk->sk_send_head = NULL; 1434 } 1435 1436 static inline void tcp_init_send_head(struct sock *sk) 1437 { 1438 sk->sk_send_head = NULL; 1439 } 1440 1441 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1442 { 1443 __skb_queue_tail(&sk->sk_write_queue, skb); 1444 } 1445 1446 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1447 { 1448 __tcp_add_write_queue_tail(sk, skb); 1449 1450 /* Queue it, remembering where we must start sending. */ 1451 if (sk->sk_send_head == NULL) { 1452 sk->sk_send_head = skb; 1453 1454 if (tcp_sk(sk)->highest_sack == NULL) 1455 tcp_sk(sk)->highest_sack = skb; 1456 } 1457 } 1458 1459 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb) 1460 { 1461 __skb_queue_head(&sk->sk_write_queue, skb); 1462 } 1463 1464 /* Insert buff after skb on the write queue of sk. */ 1465 static inline void tcp_insert_write_queue_after(struct sk_buff *skb, 1466 struct sk_buff *buff, 1467 struct sock *sk) 1468 { 1469 __skb_queue_after(&sk->sk_write_queue, skb, buff); 1470 } 1471 1472 /* Insert new before skb on the write queue of sk. */ 1473 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1474 struct sk_buff *skb, 1475 struct sock *sk) 1476 { 1477 __skb_queue_before(&sk->sk_write_queue, skb, new); 1478 1479 if (sk->sk_send_head == skb) 1480 sk->sk_send_head = new; 1481 } 1482 1483 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1484 { 1485 __skb_unlink(skb, &sk->sk_write_queue); 1486 } 1487 1488 static inline bool tcp_write_queue_empty(struct sock *sk) 1489 { 1490 return skb_queue_empty(&sk->sk_write_queue); 1491 } 1492 1493 static inline void tcp_push_pending_frames(struct sock *sk) 1494 { 1495 if (tcp_send_head(sk)) { 1496 struct tcp_sock *tp = tcp_sk(sk); 1497 1498 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1499 } 1500 } 1501 1502 /* Start sequence of the skb just after the highest skb with SACKed 1503 * bit, valid only if sacked_out > 0 or when the caller has ensured 1504 * validity by itself. 1505 */ 1506 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1507 { 1508 if (!tp->sacked_out) 1509 return tp->snd_una; 1510 1511 if (tp->highest_sack == NULL) 1512 return tp->snd_nxt; 1513 1514 return TCP_SKB_CB(tp->highest_sack)->seq; 1515 } 1516 1517 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1518 { 1519 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL : 1520 tcp_write_queue_next(sk, skb); 1521 } 1522 1523 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1524 { 1525 return tcp_sk(sk)->highest_sack; 1526 } 1527 1528 static inline void tcp_highest_sack_reset(struct sock *sk) 1529 { 1530 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk); 1531 } 1532 1533 /* Called when old skb is about to be deleted (to be combined with new skb) */ 1534 static inline void tcp_highest_sack_combine(struct sock *sk, 1535 struct sk_buff *old, 1536 struct sk_buff *new) 1537 { 1538 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack)) 1539 tcp_sk(sk)->highest_sack = new; 1540 } 1541 1542 /* Determines whether this is a thin stream (which may suffer from 1543 * increased latency). Used to trigger latency-reducing mechanisms. 1544 */ 1545 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1546 { 1547 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1548 } 1549 1550 /* /proc */ 1551 enum tcp_seq_states { 1552 TCP_SEQ_STATE_LISTENING, 1553 TCP_SEQ_STATE_OPENREQ, 1554 TCP_SEQ_STATE_ESTABLISHED, 1555 }; 1556 1557 int tcp_seq_open(struct inode *inode, struct file *file); 1558 1559 struct tcp_seq_afinfo { 1560 char *name; 1561 sa_family_t family; 1562 const struct file_operations *seq_fops; 1563 struct seq_operations seq_ops; 1564 }; 1565 1566 struct tcp_iter_state { 1567 struct seq_net_private p; 1568 sa_family_t family; 1569 enum tcp_seq_states state; 1570 struct sock *syn_wait_sk; 1571 int bucket, offset, sbucket, num; 1572 kuid_t uid; 1573 loff_t last_pos; 1574 }; 1575 1576 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1577 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1578 1579 extern struct request_sock_ops tcp_request_sock_ops; 1580 extern struct request_sock_ops tcp6_request_sock_ops; 1581 1582 void tcp_v4_destroy_sock(struct sock *sk); 1583 1584 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 1585 netdev_features_t features); 1586 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb); 1587 int tcp_gro_complete(struct sk_buff *skb); 1588 1589 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 1590 1591 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 1592 { 1593 return tp->notsent_lowat ?: sysctl_tcp_notsent_lowat; 1594 } 1595 1596 static inline bool tcp_stream_memory_free(const struct sock *sk) 1597 { 1598 const struct tcp_sock *tp = tcp_sk(sk); 1599 u32 notsent_bytes = tp->write_seq - tp->snd_nxt; 1600 1601 return notsent_bytes < tcp_notsent_lowat(tp); 1602 } 1603 1604 #ifdef CONFIG_PROC_FS 1605 int tcp4_proc_init(void); 1606 void tcp4_proc_exit(void); 1607 #endif 1608 1609 int tcp_rtx_synack(struct sock *sk, struct request_sock *req); 1610 int tcp_conn_request(struct request_sock_ops *rsk_ops, 1611 const struct tcp_request_sock_ops *af_ops, 1612 struct sock *sk, struct sk_buff *skb); 1613 1614 /* TCP af-specific functions */ 1615 struct tcp_sock_af_ops { 1616 #ifdef CONFIG_TCP_MD5SIG 1617 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk, 1618 struct sock *addr_sk); 1619 int (*calc_md5_hash) (char *location, 1620 struct tcp_md5sig_key *md5, 1621 const struct sock *sk, 1622 const struct request_sock *req, 1623 const struct sk_buff *skb); 1624 int (*md5_parse) (struct sock *sk, 1625 char __user *optval, 1626 int optlen); 1627 #endif 1628 }; 1629 1630 struct tcp_request_sock_ops { 1631 u16 mss_clamp; 1632 #ifdef CONFIG_TCP_MD5SIG 1633 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk, 1634 struct request_sock *req); 1635 int (*calc_md5_hash) (char *location, 1636 struct tcp_md5sig_key *md5, 1637 const struct sock *sk, 1638 const struct request_sock *req, 1639 const struct sk_buff *skb); 1640 #endif 1641 void (*init_req)(struct request_sock *req, struct sock *sk, 1642 struct sk_buff *skb); 1643 #ifdef CONFIG_SYN_COOKIES 1644 __u32 (*cookie_init_seq)(struct sock *sk, const struct sk_buff *skb, 1645 __u16 *mss); 1646 #endif 1647 struct dst_entry *(*route_req)(struct sock *sk, struct flowi *fl, 1648 const struct request_sock *req, 1649 bool *strict); 1650 __u32 (*init_seq)(const struct sk_buff *skb); 1651 int (*send_synack)(struct sock *sk, struct dst_entry *dst, 1652 struct flowi *fl, struct request_sock *req, 1653 u16 queue_mapping, struct tcp_fastopen_cookie *foc); 1654 void (*queue_hash_add)(struct sock *sk, struct request_sock *req, 1655 const unsigned long timeout); 1656 }; 1657 1658 #ifdef CONFIG_SYN_COOKIES 1659 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1660 struct sock *sk, struct sk_buff *skb, 1661 __u16 *mss) 1662 { 1663 return ops->cookie_init_seq(sk, skb, mss); 1664 } 1665 #else 1666 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1667 struct sock *sk, struct sk_buff *skb, 1668 __u16 *mss) 1669 { 1670 return 0; 1671 } 1672 #endif 1673 1674 int tcpv4_offload_init(void); 1675 1676 void tcp_v4_init(void); 1677 void tcp_init(void); 1678 1679 /* 1680 * Save and compile IPv4 options, return a pointer to it 1681 */ 1682 static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb) 1683 { 1684 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; 1685 struct ip_options_rcu *dopt = NULL; 1686 1687 if (opt->optlen) { 1688 int opt_size = sizeof(*dopt) + opt->optlen; 1689 1690 dopt = kmalloc(opt_size, GFP_ATOMIC); 1691 if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) { 1692 kfree(dopt); 1693 dopt = NULL; 1694 } 1695 } 1696 return dopt; 1697 } 1698 1699 #endif /* _TCP_H */ 1700