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 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 extern 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 /* Offer an initial receive window of 10 mss. */ 65 #define TCP_DEFAULT_INIT_RCVWND 10 66 67 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */ 68 #define TCP_MIN_MSS 88U 69 70 /* The least MTU to use for probing */ 71 #define TCP_BASE_MSS 512 72 73 /* After receiving this amount of duplicate ACKs fast retransmit starts. */ 74 #define TCP_FASTRETRANS_THRESH 3 75 76 /* Maximal reordering. */ 77 #define TCP_MAX_REORDERING 127 78 79 /* Maximal number of ACKs sent quickly to accelerate slow-start. */ 80 #define TCP_MAX_QUICKACKS 16U 81 82 /* urg_data states */ 83 #define TCP_URG_VALID 0x0100 84 #define TCP_URG_NOTYET 0x0200 85 #define TCP_URG_READ 0x0400 86 87 #define TCP_RETR1 3 /* 88 * This is how many retries it does before it 89 * tries to figure out if the gateway is 90 * down. Minimal RFC value is 3; it corresponds 91 * to ~3sec-8min depending on RTO. 92 */ 93 94 #define TCP_RETR2 15 /* 95 * This should take at least 96 * 90 minutes to time out. 97 * RFC1122 says that the limit is 100 sec. 98 * 15 is ~13-30min depending on RTO. 99 */ 100 101 #define TCP_SYN_RETRIES 5 /* number of times to retry active opening a 102 * connection: ~180sec is RFC minimum */ 103 104 #define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a 105 * connection: ~180sec is RFC minimum */ 106 107 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT 108 * state, about 60 seconds */ 109 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN 110 /* BSD style FIN_WAIT2 deadlock breaker. 111 * It used to be 3min, new value is 60sec, 112 * to combine FIN-WAIT-2 timeout with 113 * TIME-WAIT timer. 114 */ 115 116 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ 117 #if HZ >= 100 118 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */ 119 #define TCP_ATO_MIN ((unsigned)(HZ/25)) 120 #else 121 #define TCP_DELACK_MIN 4U 122 #define TCP_ATO_MIN 4U 123 #endif 124 #define TCP_RTO_MAX ((unsigned)(120*HZ)) 125 #define TCP_RTO_MIN ((unsigned)(HZ/5)) 126 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */ 127 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now 128 * used as a fallback RTO for the 129 * initial data transmission if no 130 * valid RTT sample has been acquired, 131 * most likely due to retrans in 3WHS. 132 */ 133 134 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes 135 * for local resources. 136 */ 137 138 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ 139 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ 140 #define TCP_KEEPALIVE_INTVL (75*HZ) 141 142 #define MAX_TCP_KEEPIDLE 32767 143 #define MAX_TCP_KEEPINTVL 32767 144 #define MAX_TCP_KEEPCNT 127 145 #define MAX_TCP_SYNCNT 127 146 147 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */ 148 149 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24) 150 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated 151 * after this time. It should be equal 152 * (or greater than) TCP_TIMEWAIT_LEN 153 * to provide reliability equal to one 154 * provided by timewait state. 155 */ 156 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host 157 * timestamps. It must be less than 158 * minimal timewait lifetime. 159 */ 160 /* 161 * TCP option 162 */ 163 164 #define TCPOPT_NOP 1 /* Padding */ 165 #define TCPOPT_EOL 0 /* End of options */ 166 #define TCPOPT_MSS 2 /* Segment size negotiating */ 167 #define TCPOPT_WINDOW 3 /* Window scaling */ 168 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ 169 #define TCPOPT_SACK 5 /* SACK Block */ 170 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ 171 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */ 172 #define TCPOPT_COOKIE 253 /* Cookie extension (experimental) */ 173 174 /* 175 * TCP option lengths 176 */ 177 178 #define TCPOLEN_MSS 4 179 #define TCPOLEN_WINDOW 3 180 #define TCPOLEN_SACK_PERM 2 181 #define TCPOLEN_TIMESTAMP 10 182 #define TCPOLEN_MD5SIG 18 183 #define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */ 184 #define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */ 185 #define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN) 186 #define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX) 187 188 /* But this is what stacks really send out. */ 189 #define TCPOLEN_TSTAMP_ALIGNED 12 190 #define TCPOLEN_WSCALE_ALIGNED 4 191 #define TCPOLEN_SACKPERM_ALIGNED 4 192 #define TCPOLEN_SACK_BASE 2 193 #define TCPOLEN_SACK_BASE_ALIGNED 4 194 #define TCPOLEN_SACK_PERBLOCK 8 195 #define TCPOLEN_MD5SIG_ALIGNED 20 196 #define TCPOLEN_MSS_ALIGNED 4 197 198 /* Flags in tp->nonagle */ 199 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */ 200 #define TCP_NAGLE_CORK 2 /* Socket is corked */ 201 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */ 202 203 /* TCP thin-stream limits */ 204 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */ 205 206 /* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */ 207 #define TCP_INIT_CWND 10 208 209 extern struct inet_timewait_death_row tcp_death_row; 210 211 /* sysctl variables for tcp */ 212 extern int sysctl_tcp_timestamps; 213 extern int sysctl_tcp_window_scaling; 214 extern int sysctl_tcp_sack; 215 extern int sysctl_tcp_fin_timeout; 216 extern int sysctl_tcp_keepalive_time; 217 extern int sysctl_tcp_keepalive_probes; 218 extern int sysctl_tcp_keepalive_intvl; 219 extern int sysctl_tcp_syn_retries; 220 extern int sysctl_tcp_synack_retries; 221 extern int sysctl_tcp_retries1; 222 extern int sysctl_tcp_retries2; 223 extern int sysctl_tcp_orphan_retries; 224 extern int sysctl_tcp_syncookies; 225 extern int sysctl_tcp_retrans_collapse; 226 extern int sysctl_tcp_stdurg; 227 extern int sysctl_tcp_rfc1337; 228 extern int sysctl_tcp_abort_on_overflow; 229 extern int sysctl_tcp_max_orphans; 230 extern int sysctl_tcp_fack; 231 extern int sysctl_tcp_reordering; 232 extern int sysctl_tcp_ecn; 233 extern int sysctl_tcp_dsack; 234 extern int sysctl_tcp_wmem[3]; 235 extern int sysctl_tcp_rmem[3]; 236 extern int sysctl_tcp_app_win; 237 extern int sysctl_tcp_adv_win_scale; 238 extern int sysctl_tcp_tw_reuse; 239 extern int sysctl_tcp_frto; 240 extern int sysctl_tcp_frto_response; 241 extern int sysctl_tcp_low_latency; 242 extern int sysctl_tcp_dma_copybreak; 243 extern int sysctl_tcp_nometrics_save; 244 extern int sysctl_tcp_moderate_rcvbuf; 245 extern int sysctl_tcp_tso_win_divisor; 246 extern int sysctl_tcp_abc; 247 extern int sysctl_tcp_mtu_probing; 248 extern int sysctl_tcp_base_mss; 249 extern int sysctl_tcp_workaround_signed_windows; 250 extern int sysctl_tcp_slow_start_after_idle; 251 extern int sysctl_tcp_max_ssthresh; 252 extern int sysctl_tcp_cookie_size; 253 extern int sysctl_tcp_thin_linear_timeouts; 254 extern int sysctl_tcp_thin_dupack; 255 extern int sysctl_tcp_early_retrans; 256 257 extern atomic_long_t tcp_memory_allocated; 258 extern struct percpu_counter tcp_sockets_allocated; 259 extern int tcp_memory_pressure; 260 261 /* 262 * The next routines deal with comparing 32 bit unsigned ints 263 * and worry about wraparound (automatic with unsigned arithmetic). 264 */ 265 266 static inline bool before(__u32 seq1, __u32 seq2) 267 { 268 return (__s32)(seq1-seq2) < 0; 269 } 270 #define after(seq2, seq1) before(seq1, seq2) 271 272 /* is s2<=s1<=s3 ? */ 273 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) 274 { 275 return seq3 - seq2 >= seq1 - seq2; 276 } 277 278 static inline bool tcp_out_of_memory(struct sock *sk) 279 { 280 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 281 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2)) 282 return true; 283 return false; 284 } 285 286 static inline bool tcp_too_many_orphans(struct sock *sk, int shift) 287 { 288 struct percpu_counter *ocp = sk->sk_prot->orphan_count; 289 int orphans = percpu_counter_read_positive(ocp); 290 291 if (orphans << shift > sysctl_tcp_max_orphans) { 292 orphans = percpu_counter_sum_positive(ocp); 293 if (orphans << shift > sysctl_tcp_max_orphans) 294 return true; 295 } 296 return false; 297 } 298 299 extern bool tcp_check_oom(struct sock *sk, int shift); 300 301 /* syncookies: remember time of last synqueue overflow */ 302 static inline void tcp_synq_overflow(struct sock *sk) 303 { 304 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies; 305 } 306 307 /* syncookies: no recent synqueue overflow on this listening socket? */ 308 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 309 { 310 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 311 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK); 312 } 313 314 extern struct proto tcp_prot; 315 316 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 317 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field) 318 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 319 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val) 320 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 321 322 extern void tcp_init_mem(struct net *net); 323 324 extern void tcp_v4_err(struct sk_buff *skb, u32); 325 326 extern void tcp_shutdown (struct sock *sk, int how); 327 328 extern int tcp_v4_rcv(struct sk_buff *skb); 329 330 extern struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it); 331 extern void *tcp_v4_tw_get_peer(struct sock *sk); 332 extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 333 extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 334 size_t size); 335 extern int tcp_sendpage(struct sock *sk, struct page *page, int offset, 336 size_t size, int flags); 337 extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 338 extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb, 339 const struct tcphdr *th, unsigned int len); 340 extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 341 const struct tcphdr *th, unsigned int len); 342 extern void tcp_rcv_space_adjust(struct sock *sk); 343 extern void tcp_cleanup_rbuf(struct sock *sk, int copied); 344 extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 345 extern void tcp_twsk_destructor(struct sock *sk); 346 extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 347 struct pipe_inode_info *pipe, size_t len, 348 unsigned int flags); 349 350 static inline void tcp_dec_quickack_mode(struct sock *sk, 351 const unsigned int pkts) 352 { 353 struct inet_connection_sock *icsk = inet_csk(sk); 354 355 if (icsk->icsk_ack.quick) { 356 if (pkts >= icsk->icsk_ack.quick) { 357 icsk->icsk_ack.quick = 0; 358 /* Leaving quickack mode we deflate ATO. */ 359 icsk->icsk_ack.ato = TCP_ATO_MIN; 360 } else 361 icsk->icsk_ack.quick -= pkts; 362 } 363 } 364 365 #define TCP_ECN_OK 1 366 #define TCP_ECN_QUEUE_CWR 2 367 #define TCP_ECN_DEMAND_CWR 4 368 #define TCP_ECN_SEEN 8 369 370 enum tcp_tw_status { 371 TCP_TW_SUCCESS = 0, 372 TCP_TW_RST = 1, 373 TCP_TW_ACK = 2, 374 TCP_TW_SYN = 3 375 }; 376 377 378 extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 379 struct sk_buff *skb, 380 const struct tcphdr *th); 381 extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb, 382 struct request_sock *req, 383 struct request_sock **prev); 384 extern int tcp_child_process(struct sock *parent, struct sock *child, 385 struct sk_buff *skb); 386 extern bool tcp_use_frto(struct sock *sk); 387 extern void tcp_enter_frto(struct sock *sk); 388 extern void tcp_enter_loss(struct sock *sk, int how); 389 extern void tcp_clear_retrans(struct tcp_sock *tp); 390 extern void tcp_update_metrics(struct sock *sk); 391 extern void tcp_close(struct sock *sk, long timeout); 392 extern void tcp_init_sock(struct sock *sk); 393 extern unsigned int tcp_poll(struct file * file, struct socket *sock, 394 struct poll_table_struct *wait); 395 extern int tcp_getsockopt(struct sock *sk, int level, int optname, 396 char __user *optval, int __user *optlen); 397 extern int tcp_setsockopt(struct sock *sk, int level, int optname, 398 char __user *optval, unsigned int optlen); 399 extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 400 char __user *optval, int __user *optlen); 401 extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 402 char __user *optval, unsigned int optlen); 403 extern void tcp_set_keepalive(struct sock *sk, int val); 404 extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req); 405 extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 406 size_t len, int nonblock, int flags, int *addr_len); 407 extern void tcp_parse_options(const struct sk_buff *skb, 408 struct tcp_options_received *opt_rx, const u8 **hvpp, 409 int estab); 410 extern const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); 411 412 /* 413 * TCP v4 functions exported for the inet6 API 414 */ 415 416 extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 417 extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 418 extern struct sock * tcp_create_openreq_child(struct sock *sk, 419 struct request_sock *req, 420 struct sk_buff *skb); 421 extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb, 422 struct request_sock *req, 423 struct dst_entry *dst); 424 extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 425 extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, 426 int addr_len); 427 extern int tcp_connect(struct sock *sk); 428 extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst, 429 struct request_sock *req, 430 struct request_values *rvp); 431 extern int tcp_disconnect(struct sock *sk, int flags); 432 433 void tcp_connect_init(struct sock *sk); 434 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 435 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 436 437 /* From syncookies.c */ 438 extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS]; 439 extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, 440 struct ip_options *opt); 441 #ifdef CONFIG_SYN_COOKIES 442 extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, 443 __u16 *mss); 444 #else 445 static inline __u32 cookie_v4_init_sequence(struct sock *sk, 446 struct sk_buff *skb, 447 __u16 *mss) 448 { 449 return 0; 450 } 451 #endif 452 453 extern __u32 cookie_init_timestamp(struct request_sock *req); 454 extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *); 455 456 /* From net/ipv6/syncookies.c */ 457 extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 458 #ifdef CONFIG_SYN_COOKIES 459 extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb, 460 __u16 *mss); 461 #else 462 static inline __u32 cookie_v6_init_sequence(struct sock *sk, 463 struct sk_buff *skb, 464 __u16 *mss) 465 { 466 return 0; 467 } 468 #endif 469 /* tcp_output.c */ 470 471 extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 472 int nonagle); 473 extern bool tcp_may_send_now(struct sock *sk); 474 extern int tcp_retransmit_skb(struct sock *, struct sk_buff *); 475 extern void tcp_retransmit_timer(struct sock *sk); 476 extern void tcp_xmit_retransmit_queue(struct sock *); 477 extern void tcp_simple_retransmit(struct sock *); 478 extern int tcp_trim_head(struct sock *, struct sk_buff *, u32); 479 extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int); 480 481 extern void tcp_send_probe0(struct sock *); 482 extern void tcp_send_partial(struct sock *); 483 extern int tcp_write_wakeup(struct sock *); 484 extern void tcp_send_fin(struct sock *sk); 485 extern void tcp_send_active_reset(struct sock *sk, gfp_t priority); 486 extern int tcp_send_synack(struct sock *); 487 extern bool tcp_syn_flood_action(struct sock *sk, 488 const struct sk_buff *skb, 489 const char *proto); 490 extern void tcp_push_one(struct sock *, unsigned int mss_now); 491 extern void tcp_send_ack(struct sock *sk); 492 extern void tcp_send_delayed_ack(struct sock *sk); 493 494 /* tcp_input.c */ 495 extern void tcp_cwnd_application_limited(struct sock *sk); 496 extern void tcp_resume_early_retransmit(struct sock *sk); 497 extern void tcp_rearm_rto(struct sock *sk); 498 499 /* tcp_timer.c */ 500 extern void tcp_init_xmit_timers(struct sock *); 501 static inline void tcp_clear_xmit_timers(struct sock *sk) 502 { 503 inet_csk_clear_xmit_timers(sk); 504 } 505 506 extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 507 extern unsigned int tcp_current_mss(struct sock *sk); 508 509 /* Bound MSS / TSO packet size with the half of the window */ 510 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 511 { 512 int cutoff; 513 514 /* When peer uses tiny windows, there is no use in packetizing 515 * to sub-MSS pieces for the sake of SWS or making sure there 516 * are enough packets in the pipe for fast recovery. 517 * 518 * On the other hand, for extremely large MSS devices, handling 519 * smaller than MSS windows in this way does make sense. 520 */ 521 if (tp->max_window >= 512) 522 cutoff = (tp->max_window >> 1); 523 else 524 cutoff = tp->max_window; 525 526 if (cutoff && pktsize > cutoff) 527 return max_t(int, cutoff, 68U - tp->tcp_header_len); 528 else 529 return pktsize; 530 } 531 532 /* tcp.c */ 533 extern void tcp_get_info(const struct sock *, struct tcp_info *); 534 535 /* Read 'sendfile()'-style from a TCP socket */ 536 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *, 537 unsigned int, size_t); 538 extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 539 sk_read_actor_t recv_actor); 540 541 extern void tcp_initialize_rcv_mss(struct sock *sk); 542 543 extern int tcp_mtu_to_mss(struct sock *sk, int pmtu); 544 extern int tcp_mss_to_mtu(struct sock *sk, int mss); 545 extern void tcp_mtup_init(struct sock *sk); 546 extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt); 547 548 static inline void tcp_bound_rto(const struct sock *sk) 549 { 550 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 551 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 552 } 553 554 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 555 { 556 return (tp->srtt >> 3) + tp->rttvar; 557 } 558 559 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 560 { 561 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 562 ntohl(TCP_FLAG_ACK) | 563 snd_wnd); 564 } 565 566 static inline void tcp_fast_path_on(struct tcp_sock *tp) 567 { 568 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 569 } 570 571 static inline void tcp_fast_path_check(struct sock *sk) 572 { 573 struct tcp_sock *tp = tcp_sk(sk); 574 575 if (skb_queue_empty(&tp->out_of_order_queue) && 576 tp->rcv_wnd && 577 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 578 !tp->urg_data) 579 tcp_fast_path_on(tp); 580 } 581 582 /* Compute the actual rto_min value */ 583 static inline u32 tcp_rto_min(struct sock *sk) 584 { 585 const struct dst_entry *dst = __sk_dst_get(sk); 586 u32 rto_min = TCP_RTO_MIN; 587 588 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 589 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 590 return rto_min; 591 } 592 593 /* Compute the actual receive window we are currently advertising. 594 * Rcv_nxt can be after the window if our peer push more data 595 * than the offered window. 596 */ 597 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 598 { 599 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 600 601 if (win < 0) 602 win = 0; 603 return (u32) win; 604 } 605 606 /* Choose a new window, without checks for shrinking, and without 607 * scaling applied to the result. The caller does these things 608 * if necessary. This is a "raw" window selection. 609 */ 610 extern u32 __tcp_select_window(struct sock *sk); 611 612 void tcp_send_window_probe(struct sock *sk); 613 614 /* TCP timestamps are only 32-bits, this causes a slight 615 * complication on 64-bit systems since we store a snapshot 616 * of jiffies in the buffer control blocks below. We decided 617 * to use only the low 32-bits of jiffies and hide the ugly 618 * casts with the following macro. 619 */ 620 #define tcp_time_stamp ((__u32)(jiffies)) 621 622 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 623 624 #define TCPHDR_FIN 0x01 625 #define TCPHDR_SYN 0x02 626 #define TCPHDR_RST 0x04 627 #define TCPHDR_PSH 0x08 628 #define TCPHDR_ACK 0x10 629 #define TCPHDR_URG 0x20 630 #define TCPHDR_ECE 0x40 631 #define TCPHDR_CWR 0x80 632 633 /* This is what the send packet queuing engine uses to pass 634 * TCP per-packet control information to the transmission code. 635 * We also store the host-order sequence numbers in here too. 636 * This is 44 bytes if IPV6 is enabled. 637 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 638 */ 639 struct tcp_skb_cb { 640 union { 641 struct inet_skb_parm h4; 642 #if IS_ENABLED(CONFIG_IPV6) 643 struct inet6_skb_parm h6; 644 #endif 645 } header; /* For incoming frames */ 646 __u32 seq; /* Starting sequence number */ 647 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 648 __u32 when; /* used to compute rtt's */ 649 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 650 651 __u8 sacked; /* State flags for SACK/FACK. */ 652 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 653 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 654 #define TCPCB_LOST 0x04 /* SKB is lost */ 655 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 656 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 657 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS) 658 659 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 660 /* 1 byte hole */ 661 __u32 ack_seq; /* Sequence number ACK'd */ 662 }; 663 664 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 665 666 /* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set 667 * 668 * If we receive a SYN packet with these bits set, it means a network is 669 * playing bad games with TOS bits. In order to avoid possible false congestion 670 * notifications, we disable TCP ECN negociation. 671 */ 672 static inline void 673 TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb) 674 { 675 const struct tcphdr *th = tcp_hdr(skb); 676 677 if (sysctl_tcp_ecn && th->ece && th->cwr && 678 INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield)) 679 inet_rsk(req)->ecn_ok = 1; 680 } 681 682 /* Due to TSO, an SKB can be composed of multiple actual 683 * packets. To keep these tracked properly, we use this. 684 */ 685 static inline int tcp_skb_pcount(const struct sk_buff *skb) 686 { 687 return skb_shinfo(skb)->gso_segs; 688 } 689 690 /* This is valid iff tcp_skb_pcount() > 1. */ 691 static inline int tcp_skb_mss(const struct sk_buff *skb) 692 { 693 return skb_shinfo(skb)->gso_size; 694 } 695 696 /* Events passed to congestion control interface */ 697 enum tcp_ca_event { 698 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 699 CA_EVENT_CWND_RESTART, /* congestion window restart */ 700 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 701 CA_EVENT_FRTO, /* fast recovery timeout */ 702 CA_EVENT_LOSS, /* loss timeout */ 703 CA_EVENT_FAST_ACK, /* in sequence ack */ 704 CA_EVENT_SLOW_ACK, /* other ack */ 705 }; 706 707 /* 708 * Interface for adding new TCP congestion control handlers 709 */ 710 #define TCP_CA_NAME_MAX 16 711 #define TCP_CA_MAX 128 712 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 713 714 #define TCP_CONG_NON_RESTRICTED 0x1 715 #define TCP_CONG_RTT_STAMP 0x2 716 717 struct tcp_congestion_ops { 718 struct list_head list; 719 unsigned long flags; 720 721 /* initialize private data (optional) */ 722 void (*init)(struct sock *sk); 723 /* cleanup private data (optional) */ 724 void (*release)(struct sock *sk); 725 726 /* return slow start threshold (required) */ 727 u32 (*ssthresh)(struct sock *sk); 728 /* lower bound for congestion window (optional) */ 729 u32 (*min_cwnd)(const struct sock *sk); 730 /* do new cwnd calculation (required) */ 731 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight); 732 /* call before changing ca_state (optional) */ 733 void (*set_state)(struct sock *sk, u8 new_state); 734 /* call when cwnd event occurs (optional) */ 735 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 736 /* new value of cwnd after loss (optional) */ 737 u32 (*undo_cwnd)(struct sock *sk); 738 /* hook for packet ack accounting (optional) */ 739 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us); 740 /* get info for inet_diag (optional) */ 741 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb); 742 743 char name[TCP_CA_NAME_MAX]; 744 struct module *owner; 745 }; 746 747 extern int tcp_register_congestion_control(struct tcp_congestion_ops *type); 748 extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 749 750 extern void tcp_init_congestion_control(struct sock *sk); 751 extern void tcp_cleanup_congestion_control(struct sock *sk); 752 extern int tcp_set_default_congestion_control(const char *name); 753 extern void tcp_get_default_congestion_control(char *name); 754 extern void tcp_get_available_congestion_control(char *buf, size_t len); 755 extern void tcp_get_allowed_congestion_control(char *buf, size_t len); 756 extern int tcp_set_allowed_congestion_control(char *allowed); 757 extern int tcp_set_congestion_control(struct sock *sk, const char *name); 758 extern void tcp_slow_start(struct tcp_sock *tp); 759 extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w); 760 761 extern struct tcp_congestion_ops tcp_init_congestion_ops; 762 extern u32 tcp_reno_ssthresh(struct sock *sk); 763 extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight); 764 extern u32 tcp_reno_min_cwnd(const struct sock *sk); 765 extern struct tcp_congestion_ops tcp_reno; 766 767 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 768 { 769 struct inet_connection_sock *icsk = inet_csk(sk); 770 771 if (icsk->icsk_ca_ops->set_state) 772 icsk->icsk_ca_ops->set_state(sk, ca_state); 773 icsk->icsk_ca_state = ca_state; 774 } 775 776 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 777 { 778 const struct inet_connection_sock *icsk = inet_csk(sk); 779 780 if (icsk->icsk_ca_ops->cwnd_event) 781 icsk->icsk_ca_ops->cwnd_event(sk, event); 782 } 783 784 /* These functions determine how the current flow behaves in respect of SACK 785 * handling. SACK is negotiated with the peer, and therefore it can vary 786 * between different flows. 787 * 788 * tcp_is_sack - SACK enabled 789 * tcp_is_reno - No SACK 790 * tcp_is_fack - FACK enabled, implies SACK enabled 791 */ 792 static inline int tcp_is_sack(const struct tcp_sock *tp) 793 { 794 return tp->rx_opt.sack_ok; 795 } 796 797 static inline bool tcp_is_reno(const struct tcp_sock *tp) 798 { 799 return !tcp_is_sack(tp); 800 } 801 802 static inline bool tcp_is_fack(const struct tcp_sock *tp) 803 { 804 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED; 805 } 806 807 static inline void tcp_enable_fack(struct tcp_sock *tp) 808 { 809 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED; 810 } 811 812 /* TCP early-retransmit (ER) is similar to but more conservative than 813 * the thin-dupack feature. Enable ER only if thin-dupack is disabled. 814 */ 815 static inline void tcp_enable_early_retrans(struct tcp_sock *tp) 816 { 817 tp->do_early_retrans = sysctl_tcp_early_retrans && 818 !sysctl_tcp_thin_dupack && sysctl_tcp_reordering == 3; 819 tp->early_retrans_delayed = 0; 820 } 821 822 static inline void tcp_disable_early_retrans(struct tcp_sock *tp) 823 { 824 tp->do_early_retrans = 0; 825 } 826 827 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 828 { 829 return tp->sacked_out + tp->lost_out; 830 } 831 832 /* This determines how many packets are "in the network" to the best 833 * of our knowledge. In many cases it is conservative, but where 834 * detailed information is available from the receiver (via SACK 835 * blocks etc.) we can make more aggressive calculations. 836 * 837 * Use this for decisions involving congestion control, use just 838 * tp->packets_out to determine if the send queue is empty or not. 839 * 840 * Read this equation as: 841 * 842 * "Packets sent once on transmission queue" MINUS 843 * "Packets left network, but not honestly ACKed yet" PLUS 844 * "Packets fast retransmitted" 845 */ 846 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 847 { 848 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 849 } 850 851 #define TCP_INFINITE_SSTHRESH 0x7fffffff 852 853 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 854 { 855 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 856 } 857 858 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 859 * The exception is rate halving phase, when cwnd is decreasing towards 860 * ssthresh. 861 */ 862 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 863 { 864 const struct tcp_sock *tp = tcp_sk(sk); 865 866 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery)) 867 return tp->snd_ssthresh; 868 else 869 return max(tp->snd_ssthresh, 870 ((tp->snd_cwnd >> 1) + 871 (tp->snd_cwnd >> 2))); 872 } 873 874 /* Use define here intentionally to get WARN_ON location shown at the caller */ 875 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 876 877 extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh); 878 extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 879 880 /* The maximum number of MSS of available cwnd for which TSO defers 881 * sending if not using sysctl_tcp_tso_win_divisor. 882 */ 883 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 884 { 885 return 3; 886 } 887 888 /* Slow start with delack produces 3 packets of burst, so that 889 * it is safe "de facto". This will be the default - same as 890 * the default reordering threshold - but if reordering increases, 891 * we must be able to allow cwnd to burst at least this much in order 892 * to not pull it back when holes are filled. 893 */ 894 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp) 895 { 896 return tp->reordering; 897 } 898 899 /* Returns end sequence number of the receiver's advertised window */ 900 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 901 { 902 return tp->snd_una + tp->snd_wnd; 903 } 904 extern bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight); 905 906 static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss, 907 const struct sk_buff *skb) 908 { 909 if (skb->len < mss) 910 tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 911 } 912 913 static inline void tcp_check_probe_timer(struct sock *sk) 914 { 915 const struct tcp_sock *tp = tcp_sk(sk); 916 const struct inet_connection_sock *icsk = inet_csk(sk); 917 918 if (!tp->packets_out && !icsk->icsk_pending) 919 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 920 icsk->icsk_rto, TCP_RTO_MAX); 921 } 922 923 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 924 { 925 tp->snd_wl1 = seq; 926 } 927 928 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 929 { 930 tp->snd_wl1 = seq; 931 } 932 933 /* 934 * Calculate(/check) TCP checksum 935 */ 936 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 937 __be32 daddr, __wsum base) 938 { 939 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 940 } 941 942 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 943 { 944 return __skb_checksum_complete(skb); 945 } 946 947 static inline bool tcp_checksum_complete(struct sk_buff *skb) 948 { 949 return !skb_csum_unnecessary(skb) && 950 __tcp_checksum_complete(skb); 951 } 952 953 /* Prequeue for VJ style copy to user, combined with checksumming. */ 954 955 static inline void tcp_prequeue_init(struct tcp_sock *tp) 956 { 957 tp->ucopy.task = NULL; 958 tp->ucopy.len = 0; 959 tp->ucopy.memory = 0; 960 skb_queue_head_init(&tp->ucopy.prequeue); 961 #ifdef CONFIG_NET_DMA 962 tp->ucopy.dma_chan = NULL; 963 tp->ucopy.wakeup = 0; 964 tp->ucopy.pinned_list = NULL; 965 tp->ucopy.dma_cookie = 0; 966 #endif 967 } 968 969 /* Packet is added to VJ-style prequeue for processing in process 970 * context, if a reader task is waiting. Apparently, this exciting 971 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93) 972 * failed somewhere. Latency? Burstiness? Well, at least now we will 973 * see, why it failed. 8)8) --ANK 974 * 975 * NOTE: is this not too big to inline? 976 */ 977 static inline bool tcp_prequeue(struct sock *sk, struct sk_buff *skb) 978 { 979 struct tcp_sock *tp = tcp_sk(sk); 980 981 if (sysctl_tcp_low_latency || !tp->ucopy.task) 982 return false; 983 984 __skb_queue_tail(&tp->ucopy.prequeue, skb); 985 tp->ucopy.memory += skb->truesize; 986 if (tp->ucopy.memory > sk->sk_rcvbuf) { 987 struct sk_buff *skb1; 988 989 BUG_ON(sock_owned_by_user(sk)); 990 991 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) { 992 sk_backlog_rcv(sk, skb1); 993 NET_INC_STATS_BH(sock_net(sk), 994 LINUX_MIB_TCPPREQUEUEDROPPED); 995 } 996 997 tp->ucopy.memory = 0; 998 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) { 999 wake_up_interruptible_sync_poll(sk_sleep(sk), 1000 POLLIN | POLLRDNORM | POLLRDBAND); 1001 if (!inet_csk_ack_scheduled(sk)) 1002 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 1003 (3 * tcp_rto_min(sk)) / 4, 1004 TCP_RTO_MAX); 1005 } 1006 return true; 1007 } 1008 1009 1010 #undef STATE_TRACE 1011 1012 #ifdef STATE_TRACE 1013 static const char *statename[]={ 1014 "Unused","Established","Syn Sent","Syn Recv", 1015 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1016 "Close Wait","Last ACK","Listen","Closing" 1017 }; 1018 #endif 1019 extern void tcp_set_state(struct sock *sk, int state); 1020 1021 extern void tcp_done(struct sock *sk); 1022 1023 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1024 { 1025 rx_opt->dsack = 0; 1026 rx_opt->num_sacks = 0; 1027 } 1028 1029 /* Determine a window scaling and initial window to offer. */ 1030 extern void tcp_select_initial_window(int __space, __u32 mss, 1031 __u32 *rcv_wnd, __u32 *window_clamp, 1032 int wscale_ok, __u8 *rcv_wscale, 1033 __u32 init_rcv_wnd); 1034 1035 static inline int tcp_win_from_space(int space) 1036 { 1037 return sysctl_tcp_adv_win_scale<=0 ? 1038 (space>>(-sysctl_tcp_adv_win_scale)) : 1039 space - (space>>sysctl_tcp_adv_win_scale); 1040 } 1041 1042 /* Note: caller must be prepared to deal with negative returns */ 1043 static inline int tcp_space(const struct sock *sk) 1044 { 1045 return tcp_win_from_space(sk->sk_rcvbuf - 1046 atomic_read(&sk->sk_rmem_alloc)); 1047 } 1048 1049 static inline int tcp_full_space(const struct sock *sk) 1050 { 1051 return tcp_win_from_space(sk->sk_rcvbuf); 1052 } 1053 1054 static inline void tcp_openreq_init(struct request_sock *req, 1055 struct tcp_options_received *rx_opt, 1056 struct sk_buff *skb) 1057 { 1058 struct inet_request_sock *ireq = inet_rsk(req); 1059 1060 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */ 1061 req->cookie_ts = 0; 1062 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq; 1063 req->mss = rx_opt->mss_clamp; 1064 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0; 1065 ireq->tstamp_ok = rx_opt->tstamp_ok; 1066 ireq->sack_ok = rx_opt->sack_ok; 1067 ireq->snd_wscale = rx_opt->snd_wscale; 1068 ireq->wscale_ok = rx_opt->wscale_ok; 1069 ireq->acked = 0; 1070 ireq->ecn_ok = 0; 1071 ireq->rmt_port = tcp_hdr(skb)->source; 1072 ireq->loc_port = tcp_hdr(skb)->dest; 1073 } 1074 1075 extern void tcp_enter_memory_pressure(struct sock *sk); 1076 1077 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1078 { 1079 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl; 1080 } 1081 1082 static inline int keepalive_time_when(const struct tcp_sock *tp) 1083 { 1084 return tp->keepalive_time ? : sysctl_tcp_keepalive_time; 1085 } 1086 1087 static inline int keepalive_probes(const struct tcp_sock *tp) 1088 { 1089 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes; 1090 } 1091 1092 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1093 { 1094 const struct inet_connection_sock *icsk = &tp->inet_conn; 1095 1096 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime, 1097 tcp_time_stamp - tp->rcv_tstamp); 1098 } 1099 1100 static inline int tcp_fin_time(const struct sock *sk) 1101 { 1102 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout; 1103 const int rto = inet_csk(sk)->icsk_rto; 1104 1105 if (fin_timeout < (rto << 2) - (rto >> 1)) 1106 fin_timeout = (rto << 2) - (rto >> 1); 1107 1108 return fin_timeout; 1109 } 1110 1111 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1112 int paws_win) 1113 { 1114 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1115 return true; 1116 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1117 return true; 1118 /* 1119 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1120 * then following tcp messages have valid values. Ignore 0 value, 1121 * or else 'negative' tsval might forbid us to accept their packets. 1122 */ 1123 if (!rx_opt->ts_recent) 1124 return true; 1125 return false; 1126 } 1127 1128 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1129 int rst) 1130 { 1131 if (tcp_paws_check(rx_opt, 0)) 1132 return false; 1133 1134 /* RST segments are not recommended to carry timestamp, 1135 and, if they do, it is recommended to ignore PAWS because 1136 "their cleanup function should take precedence over timestamps." 1137 Certainly, it is mistake. It is necessary to understand the reasons 1138 of this constraint to relax it: if peer reboots, clock may go 1139 out-of-sync and half-open connections will not be reset. 1140 Actually, the problem would be not existing if all 1141 the implementations followed draft about maintaining clock 1142 via reboots. Linux-2.2 DOES NOT! 1143 1144 However, we can relax time bounds for RST segments to MSL. 1145 */ 1146 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1147 return false; 1148 return true; 1149 } 1150 1151 static inline void tcp_mib_init(struct net *net) 1152 { 1153 /* See RFC 2012 */ 1154 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1); 1155 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1156 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1157 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1); 1158 } 1159 1160 /* from STCP */ 1161 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1162 { 1163 tp->lost_skb_hint = NULL; 1164 tp->scoreboard_skb_hint = NULL; 1165 } 1166 1167 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1168 { 1169 tcp_clear_retrans_hints_partial(tp); 1170 tp->retransmit_skb_hint = NULL; 1171 } 1172 1173 /* MD5 Signature */ 1174 struct crypto_hash; 1175 1176 union tcp_md5_addr { 1177 struct in_addr a4; 1178 #if IS_ENABLED(CONFIG_IPV6) 1179 struct in6_addr a6; 1180 #endif 1181 }; 1182 1183 /* - key database */ 1184 struct tcp_md5sig_key { 1185 struct hlist_node node; 1186 u8 keylen; 1187 u8 family; /* AF_INET or AF_INET6 */ 1188 union tcp_md5_addr addr; 1189 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1190 struct rcu_head rcu; 1191 }; 1192 1193 /* - sock block */ 1194 struct tcp_md5sig_info { 1195 struct hlist_head head; 1196 struct rcu_head rcu; 1197 }; 1198 1199 /* - pseudo header */ 1200 struct tcp4_pseudohdr { 1201 __be32 saddr; 1202 __be32 daddr; 1203 __u8 pad; 1204 __u8 protocol; 1205 __be16 len; 1206 }; 1207 1208 struct tcp6_pseudohdr { 1209 struct in6_addr saddr; 1210 struct in6_addr daddr; 1211 __be32 len; 1212 __be32 protocol; /* including padding */ 1213 }; 1214 1215 union tcp_md5sum_block { 1216 struct tcp4_pseudohdr ip4; 1217 #if IS_ENABLED(CONFIG_IPV6) 1218 struct tcp6_pseudohdr ip6; 1219 #endif 1220 }; 1221 1222 /* - pool: digest algorithm, hash description and scratch buffer */ 1223 struct tcp_md5sig_pool { 1224 struct hash_desc md5_desc; 1225 union tcp_md5sum_block md5_blk; 1226 }; 1227 1228 /* - functions */ 1229 extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key, 1230 const struct sock *sk, 1231 const struct request_sock *req, 1232 const struct sk_buff *skb); 1233 extern int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1234 int family, const u8 *newkey, 1235 u8 newkeylen, gfp_t gfp); 1236 extern int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1237 int family); 1238 extern struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk, 1239 struct sock *addr_sk); 1240 1241 #ifdef CONFIG_TCP_MD5SIG 1242 extern struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk, 1243 const union tcp_md5_addr *addr, int family); 1244 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1245 #else 1246 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk, 1247 const union tcp_md5_addr *addr, 1248 int family) 1249 { 1250 return NULL; 1251 } 1252 #define tcp_twsk_md5_key(twsk) NULL 1253 #endif 1254 1255 extern struct tcp_md5sig_pool __percpu *tcp_alloc_md5sig_pool(struct sock *); 1256 extern void tcp_free_md5sig_pool(void); 1257 1258 extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1259 extern void tcp_put_md5sig_pool(void); 1260 1261 extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *); 1262 extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1263 unsigned int header_len); 1264 extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1265 const struct tcp_md5sig_key *key); 1266 1267 /* write queue abstraction */ 1268 static inline void tcp_write_queue_purge(struct sock *sk) 1269 { 1270 struct sk_buff *skb; 1271 1272 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) 1273 sk_wmem_free_skb(sk, skb); 1274 sk_mem_reclaim(sk); 1275 tcp_clear_all_retrans_hints(tcp_sk(sk)); 1276 } 1277 1278 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1279 { 1280 return skb_peek(&sk->sk_write_queue); 1281 } 1282 1283 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1284 { 1285 return skb_peek_tail(&sk->sk_write_queue); 1286 } 1287 1288 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk, 1289 const struct sk_buff *skb) 1290 { 1291 return skb_queue_next(&sk->sk_write_queue, skb); 1292 } 1293 1294 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk, 1295 const struct sk_buff *skb) 1296 { 1297 return skb_queue_prev(&sk->sk_write_queue, skb); 1298 } 1299 1300 #define tcp_for_write_queue(skb, sk) \ 1301 skb_queue_walk(&(sk)->sk_write_queue, skb) 1302 1303 #define tcp_for_write_queue_from(skb, sk) \ 1304 skb_queue_walk_from(&(sk)->sk_write_queue, skb) 1305 1306 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1307 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1308 1309 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1310 { 1311 return sk->sk_send_head; 1312 } 1313 1314 static inline bool tcp_skb_is_last(const struct sock *sk, 1315 const struct sk_buff *skb) 1316 { 1317 return skb_queue_is_last(&sk->sk_write_queue, skb); 1318 } 1319 1320 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb) 1321 { 1322 if (tcp_skb_is_last(sk, skb)) 1323 sk->sk_send_head = NULL; 1324 else 1325 sk->sk_send_head = tcp_write_queue_next(sk, skb); 1326 } 1327 1328 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1329 { 1330 if (sk->sk_send_head == skb_unlinked) 1331 sk->sk_send_head = NULL; 1332 } 1333 1334 static inline void tcp_init_send_head(struct sock *sk) 1335 { 1336 sk->sk_send_head = NULL; 1337 } 1338 1339 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1340 { 1341 __skb_queue_tail(&sk->sk_write_queue, skb); 1342 } 1343 1344 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1345 { 1346 __tcp_add_write_queue_tail(sk, skb); 1347 1348 /* Queue it, remembering where we must start sending. */ 1349 if (sk->sk_send_head == NULL) { 1350 sk->sk_send_head = skb; 1351 1352 if (tcp_sk(sk)->highest_sack == NULL) 1353 tcp_sk(sk)->highest_sack = skb; 1354 } 1355 } 1356 1357 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb) 1358 { 1359 __skb_queue_head(&sk->sk_write_queue, skb); 1360 } 1361 1362 /* Insert buff after skb on the write queue of sk. */ 1363 static inline void tcp_insert_write_queue_after(struct sk_buff *skb, 1364 struct sk_buff *buff, 1365 struct sock *sk) 1366 { 1367 __skb_queue_after(&sk->sk_write_queue, skb, buff); 1368 } 1369 1370 /* Insert new before skb on the write queue of sk. */ 1371 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1372 struct sk_buff *skb, 1373 struct sock *sk) 1374 { 1375 __skb_queue_before(&sk->sk_write_queue, skb, new); 1376 1377 if (sk->sk_send_head == skb) 1378 sk->sk_send_head = new; 1379 } 1380 1381 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1382 { 1383 __skb_unlink(skb, &sk->sk_write_queue); 1384 } 1385 1386 static inline bool tcp_write_queue_empty(struct sock *sk) 1387 { 1388 return skb_queue_empty(&sk->sk_write_queue); 1389 } 1390 1391 static inline void tcp_push_pending_frames(struct sock *sk) 1392 { 1393 if (tcp_send_head(sk)) { 1394 struct tcp_sock *tp = tcp_sk(sk); 1395 1396 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1397 } 1398 } 1399 1400 /* Start sequence of the skb just after the highest skb with SACKed 1401 * bit, valid only if sacked_out > 0 or when the caller has ensured 1402 * validity by itself. 1403 */ 1404 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1405 { 1406 if (!tp->sacked_out) 1407 return tp->snd_una; 1408 1409 if (tp->highest_sack == NULL) 1410 return tp->snd_nxt; 1411 1412 return TCP_SKB_CB(tp->highest_sack)->seq; 1413 } 1414 1415 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1416 { 1417 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL : 1418 tcp_write_queue_next(sk, skb); 1419 } 1420 1421 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1422 { 1423 return tcp_sk(sk)->highest_sack; 1424 } 1425 1426 static inline void tcp_highest_sack_reset(struct sock *sk) 1427 { 1428 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk); 1429 } 1430 1431 /* Called when old skb is about to be deleted (to be combined with new skb) */ 1432 static inline void tcp_highest_sack_combine(struct sock *sk, 1433 struct sk_buff *old, 1434 struct sk_buff *new) 1435 { 1436 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack)) 1437 tcp_sk(sk)->highest_sack = new; 1438 } 1439 1440 /* Determines whether this is a thin stream (which may suffer from 1441 * increased latency). Used to trigger latency-reducing mechanisms. 1442 */ 1443 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1444 { 1445 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1446 } 1447 1448 /* /proc */ 1449 enum tcp_seq_states { 1450 TCP_SEQ_STATE_LISTENING, 1451 TCP_SEQ_STATE_OPENREQ, 1452 TCP_SEQ_STATE_ESTABLISHED, 1453 TCP_SEQ_STATE_TIME_WAIT, 1454 }; 1455 1456 int tcp_seq_open(struct inode *inode, struct file *file); 1457 1458 struct tcp_seq_afinfo { 1459 char *name; 1460 sa_family_t family; 1461 const struct file_operations *seq_fops; 1462 struct seq_operations seq_ops; 1463 }; 1464 1465 struct tcp_iter_state { 1466 struct seq_net_private p; 1467 sa_family_t family; 1468 enum tcp_seq_states state; 1469 struct sock *syn_wait_sk; 1470 int bucket, offset, sbucket, num, uid; 1471 loff_t last_pos; 1472 }; 1473 1474 extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1475 extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1476 1477 extern struct request_sock_ops tcp_request_sock_ops; 1478 extern struct request_sock_ops tcp6_request_sock_ops; 1479 1480 extern void tcp_v4_destroy_sock(struct sock *sk); 1481 1482 extern int tcp_v4_gso_send_check(struct sk_buff *skb); 1483 extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb, 1484 netdev_features_t features); 1485 extern struct sk_buff **tcp_gro_receive(struct sk_buff **head, 1486 struct sk_buff *skb); 1487 extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head, 1488 struct sk_buff *skb); 1489 extern int tcp_gro_complete(struct sk_buff *skb); 1490 extern int tcp4_gro_complete(struct sk_buff *skb); 1491 1492 #ifdef CONFIG_PROC_FS 1493 extern int tcp4_proc_init(void); 1494 extern void tcp4_proc_exit(void); 1495 #endif 1496 1497 /* TCP af-specific functions */ 1498 struct tcp_sock_af_ops { 1499 #ifdef CONFIG_TCP_MD5SIG 1500 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk, 1501 struct sock *addr_sk); 1502 int (*calc_md5_hash) (char *location, 1503 struct tcp_md5sig_key *md5, 1504 const struct sock *sk, 1505 const struct request_sock *req, 1506 const struct sk_buff *skb); 1507 int (*md5_parse) (struct sock *sk, 1508 char __user *optval, 1509 int optlen); 1510 #endif 1511 }; 1512 1513 struct tcp_request_sock_ops { 1514 #ifdef CONFIG_TCP_MD5SIG 1515 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk, 1516 struct request_sock *req); 1517 int (*calc_md5_hash) (char *location, 1518 struct tcp_md5sig_key *md5, 1519 const struct sock *sk, 1520 const struct request_sock *req, 1521 const struct sk_buff *skb); 1522 #endif 1523 }; 1524 1525 /* Using SHA1 for now, define some constants. 1526 */ 1527 #define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS) 1528 #define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4) 1529 #define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS) 1530 1531 extern int tcp_cookie_generator(u32 *bakery); 1532 1533 /** 1534 * struct tcp_cookie_values - each socket needs extra space for the 1535 * cookies, together with (optional) space for any SYN data. 1536 * 1537 * A tcp_sock contains a pointer to the current value, and this is 1538 * cloned to the tcp_timewait_sock. 1539 * 1540 * @cookie_pair: variable data from the option exchange. 1541 * 1542 * @cookie_desired: user specified tcpct_cookie_desired. Zero 1543 * indicates default (sysctl_tcp_cookie_size). 1544 * After cookie sent, remembers size of cookie. 1545 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX. 1546 * 1547 * @s_data_desired: user specified tcpct_s_data_desired. When the 1548 * constant payload is specified (@s_data_constant), 1549 * holds its length instead. 1550 * Range 0 to TCP_MSS_DESIRED. 1551 * 1552 * @s_data_payload: constant data that is to be included in the 1553 * payload of SYN or SYNACK segments when the 1554 * cookie option is present. 1555 */ 1556 struct tcp_cookie_values { 1557 struct kref kref; 1558 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE]; 1559 u8 cookie_pair_size; 1560 u8 cookie_desired; 1561 u16 s_data_desired:11, 1562 s_data_constant:1, 1563 s_data_in:1, 1564 s_data_out:1, 1565 s_data_unused:2; 1566 u8 s_data_payload[0]; 1567 }; 1568 1569 static inline void tcp_cookie_values_release(struct kref *kref) 1570 { 1571 kfree(container_of(kref, struct tcp_cookie_values, kref)); 1572 } 1573 1574 /* The length of constant payload data. Note that s_data_desired is 1575 * overloaded, depending on s_data_constant: either the length of constant 1576 * data (returned here) or the limit on variable data. 1577 */ 1578 static inline int tcp_s_data_size(const struct tcp_sock *tp) 1579 { 1580 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant) 1581 ? tp->cookie_values->s_data_desired 1582 : 0; 1583 } 1584 1585 /** 1586 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace. 1587 * 1588 * As tcp_request_sock has already been extended in other places, the 1589 * only remaining method is to pass stack values along as function 1590 * parameters. These parameters are not needed after sending SYNACK. 1591 * 1592 * @cookie_bakery: cryptographic secret and message workspace. 1593 * 1594 * @cookie_plus: bytes in authenticator/cookie option, copied from 1595 * struct tcp_options_received (above). 1596 */ 1597 struct tcp_extend_values { 1598 struct request_values rv; 1599 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS]; 1600 u8 cookie_plus:6, 1601 cookie_out_never:1, 1602 cookie_in_always:1; 1603 }; 1604 1605 static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp) 1606 { 1607 return (struct tcp_extend_values *)rvp; 1608 } 1609 1610 extern void tcp_v4_init(void); 1611 extern void tcp_init(void); 1612 1613 #endif /* _TCP_H */ 1614