1 /* 2 * INET An implementation of the TCP/IP protocol suite for the LINUX 3 * operating system. INET is implemented using the BSD Socket 4 * interface as the means of communication with the user level. 5 * 6 * Definitions for the TCP module. 7 * 8 * Version: @(#)tcp.h 1.0.5 05/23/93 9 * 10 * Authors: Ross Biro 11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 12 * 13 * This program is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU General Public License 15 * as published by the Free Software Foundation; either version 16 * 2 of the License, or (at your option) any later version. 17 */ 18 #ifndef _TCP_H 19 #define _TCP_H 20 21 #define FASTRETRANS_DEBUG 1 22 23 #include <linux/list.h> 24 #include <linux/tcp.h> 25 #include <linux/bug.h> 26 #include <linux/slab.h> 27 #include <linux/cache.h> 28 #include <linux/percpu.h> 29 #include <linux/skbuff.h> 30 #include <linux/cryptohash.h> 31 #include <linux/kref.h> 32 #include <linux/ktime.h> 33 34 #include <net/inet_connection_sock.h> 35 #include <net/inet_timewait_sock.h> 36 #include <net/inet_hashtables.h> 37 #include <net/checksum.h> 38 #include <net/request_sock.h> 39 #include <net/sock.h> 40 #include <net/snmp.h> 41 #include <net/ip.h> 42 #include <net/tcp_states.h> 43 #include <net/inet_ecn.h> 44 #include <net/dst.h> 45 46 #include <linux/seq_file.h> 47 #include <linux/memcontrol.h> 48 49 extern struct inet_hashinfo tcp_hashinfo; 50 51 extern struct percpu_counter tcp_orphan_count; 52 void tcp_time_wait(struct sock *sk, int state, int timeo); 53 54 #define MAX_TCP_HEADER (128 + MAX_HEADER) 55 #define MAX_TCP_OPTION_SPACE 40 56 57 /* 58 * Never offer a window over 32767 without using window scaling. Some 59 * poor stacks do signed 16bit maths! 60 */ 61 #define MAX_TCP_WINDOW 32767U 62 63 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */ 64 #define TCP_MIN_MSS 88U 65 66 /* The least MTU to use for probing */ 67 #define TCP_BASE_MSS 1024 68 69 /* probing interval, default to 10 minutes as per RFC4821 */ 70 #define TCP_PROBE_INTERVAL 600 71 72 /* Specify interval when tcp mtu probing will stop */ 73 #define TCP_PROBE_THRESHOLD 8 74 75 /* After receiving this amount of duplicate ACKs fast retransmit starts. */ 76 #define TCP_FASTRETRANS_THRESH 3 77 78 /* Maximal number of ACKs sent quickly to accelerate slow-start. */ 79 #define TCP_MAX_QUICKACKS 16U 80 81 /* urg_data states */ 82 #define TCP_URG_VALID 0x0100 83 #define TCP_URG_NOTYET 0x0200 84 #define TCP_URG_READ 0x0400 85 86 #define TCP_RETR1 3 /* 87 * This is how many retries it does before it 88 * tries to figure out if the gateway is 89 * down. Minimal RFC value is 3; it corresponds 90 * to ~3sec-8min depending on RTO. 91 */ 92 93 #define TCP_RETR2 15 /* 94 * This should take at least 95 * 90 minutes to time out. 96 * RFC1122 says that the limit is 100 sec. 97 * 15 is ~13-30min depending on RTO. 98 */ 99 100 #define TCP_SYN_RETRIES 6 /* This is how many retries are done 101 * when active opening a connection. 102 * RFC1122 says the minimum retry MUST 103 * be at least 180secs. Nevertheless 104 * this value is corresponding to 105 * 63secs of retransmission with the 106 * current initial RTO. 107 */ 108 109 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done 110 * when passive opening a connection. 111 * This is corresponding to 31secs of 112 * retransmission with the current 113 * initial RTO. 114 */ 115 116 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT 117 * state, about 60 seconds */ 118 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN 119 /* BSD style FIN_WAIT2 deadlock breaker. 120 * It used to be 3min, new value is 60sec, 121 * to combine FIN-WAIT-2 timeout with 122 * TIME-WAIT timer. 123 */ 124 125 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ 126 #if HZ >= 100 127 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */ 128 #define TCP_ATO_MIN ((unsigned)(HZ/25)) 129 #else 130 #define TCP_DELACK_MIN 4U 131 #define TCP_ATO_MIN 4U 132 #endif 133 #define TCP_RTO_MAX ((unsigned)(120*HZ)) 134 #define TCP_RTO_MIN ((unsigned)(HZ/5)) 135 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */ 136 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now 137 * used as a fallback RTO for the 138 * initial data transmission if no 139 * valid RTT sample has been acquired, 140 * most likely due to retrans in 3WHS. 141 */ 142 143 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes 144 * for local resources. 145 */ 146 #define TCP_REO_TIMEOUT_MIN (2000) /* Min RACK reordering timeout in usec */ 147 148 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ 149 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ 150 #define TCP_KEEPALIVE_INTVL (75*HZ) 151 152 #define MAX_TCP_KEEPIDLE 32767 153 #define MAX_TCP_KEEPINTVL 32767 154 #define MAX_TCP_KEEPCNT 127 155 #define MAX_TCP_SYNCNT 127 156 157 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */ 158 159 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24) 160 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated 161 * after this time. It should be equal 162 * (or greater than) TCP_TIMEWAIT_LEN 163 * to provide reliability equal to one 164 * provided by timewait state. 165 */ 166 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host 167 * timestamps. It must be less than 168 * minimal timewait lifetime. 169 */ 170 /* 171 * TCP option 172 */ 173 174 #define TCPOPT_NOP 1 /* Padding */ 175 #define TCPOPT_EOL 0 /* End of options */ 176 #define TCPOPT_MSS 2 /* Segment size negotiating */ 177 #define TCPOPT_WINDOW 3 /* Window scaling */ 178 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ 179 #define TCPOPT_SACK 5 /* SACK Block */ 180 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ 181 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */ 182 #define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */ 183 #define TCPOPT_EXP 254 /* Experimental */ 184 /* Magic number to be after the option value for sharing TCP 185 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt 186 */ 187 #define TCPOPT_FASTOPEN_MAGIC 0xF989 188 189 /* 190 * TCP option lengths 191 */ 192 193 #define TCPOLEN_MSS 4 194 #define TCPOLEN_WINDOW 3 195 #define TCPOLEN_SACK_PERM 2 196 #define TCPOLEN_TIMESTAMP 10 197 #define TCPOLEN_MD5SIG 18 198 #define TCPOLEN_FASTOPEN_BASE 2 199 #define TCPOLEN_EXP_FASTOPEN_BASE 4 200 201 /* But this is what stacks really send out. */ 202 #define TCPOLEN_TSTAMP_ALIGNED 12 203 #define TCPOLEN_WSCALE_ALIGNED 4 204 #define TCPOLEN_SACKPERM_ALIGNED 4 205 #define TCPOLEN_SACK_BASE 2 206 #define TCPOLEN_SACK_BASE_ALIGNED 4 207 #define TCPOLEN_SACK_PERBLOCK 8 208 #define TCPOLEN_MD5SIG_ALIGNED 20 209 #define TCPOLEN_MSS_ALIGNED 4 210 211 /* Flags in tp->nonagle */ 212 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */ 213 #define TCP_NAGLE_CORK 2 /* Socket is corked */ 214 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */ 215 216 /* TCP thin-stream limits */ 217 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */ 218 219 /* TCP initial congestion window as per rfc6928 */ 220 #define TCP_INIT_CWND 10 221 222 /* Bit Flags for sysctl_tcp_fastopen */ 223 #define TFO_CLIENT_ENABLE 1 224 #define TFO_SERVER_ENABLE 2 225 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */ 226 227 /* Accept SYN data w/o any cookie option */ 228 #define TFO_SERVER_COOKIE_NOT_REQD 0x200 229 230 /* Force enable TFO on all listeners, i.e., not requiring the 231 * TCP_FASTOPEN socket option. 232 */ 233 #define TFO_SERVER_WO_SOCKOPT1 0x400 234 235 236 /* sysctl variables for tcp */ 237 extern int sysctl_tcp_timestamps; 238 extern int sysctl_tcp_window_scaling; 239 extern int sysctl_tcp_sack; 240 extern int sysctl_tcp_fastopen; 241 extern int sysctl_tcp_retrans_collapse; 242 extern int sysctl_tcp_stdurg; 243 extern int sysctl_tcp_rfc1337; 244 extern int sysctl_tcp_abort_on_overflow; 245 extern int sysctl_tcp_max_orphans; 246 extern int sysctl_tcp_fack; 247 extern int sysctl_tcp_reordering; 248 extern int sysctl_tcp_max_reordering; 249 extern int sysctl_tcp_dsack; 250 extern long sysctl_tcp_mem[3]; 251 extern int sysctl_tcp_wmem[3]; 252 extern int sysctl_tcp_rmem[3]; 253 extern int sysctl_tcp_app_win; 254 extern int sysctl_tcp_adv_win_scale; 255 extern int sysctl_tcp_frto; 256 extern int sysctl_tcp_low_latency; 257 extern int sysctl_tcp_nometrics_save; 258 extern int sysctl_tcp_moderate_rcvbuf; 259 extern int sysctl_tcp_tso_win_divisor; 260 extern int sysctl_tcp_workaround_signed_windows; 261 extern int sysctl_tcp_slow_start_after_idle; 262 extern int sysctl_tcp_thin_linear_timeouts; 263 extern int sysctl_tcp_thin_dupack; 264 extern int sysctl_tcp_early_retrans; 265 extern int sysctl_tcp_recovery; 266 #define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */ 267 268 extern int sysctl_tcp_limit_output_bytes; 269 extern int sysctl_tcp_challenge_ack_limit; 270 extern int sysctl_tcp_min_tso_segs; 271 extern int sysctl_tcp_min_rtt_wlen; 272 extern int sysctl_tcp_autocorking; 273 extern int sysctl_tcp_invalid_ratelimit; 274 extern int sysctl_tcp_pacing_ss_ratio; 275 extern int sysctl_tcp_pacing_ca_ratio; 276 277 extern atomic_long_t tcp_memory_allocated; 278 extern struct percpu_counter tcp_sockets_allocated; 279 extern int tcp_memory_pressure; 280 281 /* optimized version of sk_under_memory_pressure() for TCP sockets */ 282 static inline bool tcp_under_memory_pressure(const struct sock *sk) 283 { 284 if (mem_cgroup_sockets_enabled && sk->sk_memcg && 285 mem_cgroup_under_socket_pressure(sk->sk_memcg)) 286 return true; 287 288 return tcp_memory_pressure; 289 } 290 /* 291 * The next routines deal with comparing 32 bit unsigned ints 292 * and worry about wraparound (automatic with unsigned arithmetic). 293 */ 294 295 static inline bool before(__u32 seq1, __u32 seq2) 296 { 297 return (__s32)(seq1-seq2) < 0; 298 } 299 #define after(seq2, seq1) before(seq1, seq2) 300 301 /* is s2<=s1<=s3 ? */ 302 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) 303 { 304 return seq3 - seq2 >= seq1 - seq2; 305 } 306 307 static inline bool tcp_out_of_memory(struct sock *sk) 308 { 309 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 310 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2)) 311 return true; 312 return false; 313 } 314 315 void sk_forced_mem_schedule(struct sock *sk, int size); 316 317 static inline bool tcp_too_many_orphans(struct sock *sk, int shift) 318 { 319 struct percpu_counter *ocp = sk->sk_prot->orphan_count; 320 int orphans = percpu_counter_read_positive(ocp); 321 322 if (orphans << shift > sysctl_tcp_max_orphans) { 323 orphans = percpu_counter_sum_positive(ocp); 324 if (orphans << shift > sysctl_tcp_max_orphans) 325 return true; 326 } 327 return false; 328 } 329 330 bool tcp_check_oom(struct sock *sk, int shift); 331 332 333 extern struct proto tcp_prot; 334 335 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 336 #define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field) 337 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 338 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 339 340 void tcp_tasklet_init(void); 341 342 void tcp_v4_err(struct sk_buff *skb, u32); 343 344 void tcp_shutdown(struct sock *sk, int how); 345 346 void tcp_v4_early_demux(struct sk_buff *skb); 347 int tcp_v4_rcv(struct sk_buff *skb); 348 349 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 350 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size); 351 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, 352 int flags); 353 void tcp_release_cb(struct sock *sk); 354 void tcp_wfree(struct sk_buff *skb); 355 void tcp_write_timer_handler(struct sock *sk); 356 void tcp_delack_timer_handler(struct sock *sk); 357 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 358 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb); 359 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 360 const struct tcphdr *th, unsigned int len); 361 void tcp_rcv_space_adjust(struct sock *sk); 362 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 363 void tcp_twsk_destructor(struct sock *sk); 364 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 365 struct pipe_inode_info *pipe, size_t len, 366 unsigned int flags); 367 368 static inline void tcp_dec_quickack_mode(struct sock *sk, 369 const unsigned int pkts) 370 { 371 struct inet_connection_sock *icsk = inet_csk(sk); 372 373 if (icsk->icsk_ack.quick) { 374 if (pkts >= icsk->icsk_ack.quick) { 375 icsk->icsk_ack.quick = 0; 376 /* Leaving quickack mode we deflate ATO. */ 377 icsk->icsk_ack.ato = TCP_ATO_MIN; 378 } else 379 icsk->icsk_ack.quick -= pkts; 380 } 381 } 382 383 #define TCP_ECN_OK 1 384 #define TCP_ECN_QUEUE_CWR 2 385 #define TCP_ECN_DEMAND_CWR 4 386 #define TCP_ECN_SEEN 8 387 388 enum tcp_tw_status { 389 TCP_TW_SUCCESS = 0, 390 TCP_TW_RST = 1, 391 TCP_TW_ACK = 2, 392 TCP_TW_SYN = 3 393 }; 394 395 396 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 397 struct sk_buff *skb, 398 const struct tcphdr *th); 399 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 400 struct request_sock *req, bool fastopen); 401 int tcp_child_process(struct sock *parent, struct sock *child, 402 struct sk_buff *skb); 403 void tcp_enter_loss(struct sock *sk); 404 void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int flag); 405 void tcp_clear_retrans(struct tcp_sock *tp); 406 void tcp_update_metrics(struct sock *sk); 407 void tcp_init_metrics(struct sock *sk); 408 void tcp_metrics_init(void); 409 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, 410 bool paws_check, bool timestamps); 411 bool tcp_remember_stamp(struct sock *sk); 412 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw); 413 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst); 414 void tcp_disable_fack(struct tcp_sock *tp); 415 void tcp_close(struct sock *sk, long timeout); 416 void tcp_init_sock(struct sock *sk); 417 unsigned int tcp_poll(struct file *file, struct socket *sock, 418 struct poll_table_struct *wait); 419 int tcp_getsockopt(struct sock *sk, int level, int optname, 420 char __user *optval, int __user *optlen); 421 int tcp_setsockopt(struct sock *sk, int level, int optname, 422 char __user *optval, unsigned int optlen); 423 int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 424 char __user *optval, int __user *optlen); 425 int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 426 char __user *optval, unsigned int optlen); 427 void tcp_set_keepalive(struct sock *sk, int val); 428 void tcp_syn_ack_timeout(const struct request_sock *req); 429 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, 430 int flags, int *addr_len); 431 void tcp_parse_options(const struct sk_buff *skb, 432 struct tcp_options_received *opt_rx, 433 int estab, struct tcp_fastopen_cookie *foc); 434 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); 435 436 /* 437 * TCP v4 functions exported for the inet6 API 438 */ 439 440 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 441 void tcp_v4_mtu_reduced(struct sock *sk); 442 void tcp_req_err(struct sock *sk, u32 seq, bool abort); 443 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 444 struct sock *tcp_create_openreq_child(const struct sock *sk, 445 struct request_sock *req, 446 struct sk_buff *skb); 447 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst); 448 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 449 struct request_sock *req, 450 struct dst_entry *dst, 451 struct request_sock *req_unhash, 452 bool *own_req); 453 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 454 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); 455 int tcp_connect(struct sock *sk); 456 enum tcp_synack_type { 457 TCP_SYNACK_NORMAL, 458 TCP_SYNACK_FASTOPEN, 459 TCP_SYNACK_COOKIE, 460 }; 461 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 462 struct request_sock *req, 463 struct tcp_fastopen_cookie *foc, 464 enum tcp_synack_type synack_type); 465 int tcp_disconnect(struct sock *sk, int flags); 466 467 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 468 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 469 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); 470 471 /* From syncookies.c */ 472 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, 473 struct request_sock *req, 474 struct dst_entry *dst); 475 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th, 476 u32 cookie); 477 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb); 478 #ifdef CONFIG_SYN_COOKIES 479 480 /* Syncookies use a monotonic timer which increments every 60 seconds. 481 * This counter is used both as a hash input and partially encoded into 482 * the cookie value. A cookie is only validated further if the delta 483 * between the current counter value and the encoded one is less than this, 484 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if 485 * the counter advances immediately after a cookie is generated). 486 */ 487 #define MAX_SYNCOOKIE_AGE 2 488 #define TCP_SYNCOOKIE_PERIOD (60 * HZ) 489 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD) 490 491 /* syncookies: remember time of last synqueue overflow 492 * But do not dirty this field too often (once per second is enough) 493 * It is racy as we do not hold a lock, but race is very minor. 494 */ 495 static inline void tcp_synq_overflow(const struct sock *sk) 496 { 497 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 498 unsigned long now = jiffies; 499 500 if (time_after(now, last_overflow + HZ)) 501 tcp_sk(sk)->rx_opt.ts_recent_stamp = now; 502 } 503 504 /* syncookies: no recent synqueue overflow on this listening socket? */ 505 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 506 { 507 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 508 509 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID); 510 } 511 512 static inline u32 tcp_cookie_time(void) 513 { 514 u64 val = get_jiffies_64(); 515 516 do_div(val, TCP_SYNCOOKIE_PERIOD); 517 return val; 518 } 519 520 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, 521 u16 *mssp); 522 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss); 523 __u32 cookie_init_timestamp(struct request_sock *req); 524 bool cookie_timestamp_decode(struct tcp_options_received *opt); 525 bool cookie_ecn_ok(const struct tcp_options_received *opt, 526 const struct net *net, const struct dst_entry *dst); 527 528 /* From net/ipv6/syncookies.c */ 529 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th, 530 u32 cookie); 531 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 532 533 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph, 534 const struct tcphdr *th, u16 *mssp); 535 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss); 536 #endif 537 /* tcp_output.c */ 538 539 u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, 540 int min_tso_segs); 541 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 542 int nonagle); 543 bool tcp_may_send_now(struct sock *sk); 544 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 545 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 546 void tcp_retransmit_timer(struct sock *sk); 547 void tcp_xmit_retransmit_queue(struct sock *); 548 void tcp_simple_retransmit(struct sock *); 549 void tcp_enter_recovery(struct sock *sk, bool ece_ack); 550 int tcp_trim_head(struct sock *, struct sk_buff *, u32); 551 int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t); 552 553 void tcp_send_probe0(struct sock *); 554 void tcp_send_partial(struct sock *); 555 int tcp_write_wakeup(struct sock *, int mib); 556 void tcp_send_fin(struct sock *sk); 557 void tcp_send_active_reset(struct sock *sk, gfp_t priority); 558 int tcp_send_synack(struct sock *); 559 void tcp_push_one(struct sock *, unsigned int mss_now); 560 void tcp_send_ack(struct sock *sk); 561 void tcp_send_delayed_ack(struct sock *sk); 562 void tcp_send_loss_probe(struct sock *sk); 563 bool tcp_schedule_loss_probe(struct sock *sk); 564 void tcp_skb_collapse_tstamp(struct sk_buff *skb, 565 const struct sk_buff *next_skb); 566 567 /* tcp_input.c */ 568 void tcp_rearm_rto(struct sock *sk); 569 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req); 570 void tcp_reset(struct sock *sk); 571 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb); 572 void tcp_fin(struct sock *sk); 573 574 /* tcp_timer.c */ 575 void tcp_init_xmit_timers(struct sock *); 576 static inline void tcp_clear_xmit_timers(struct sock *sk) 577 { 578 inet_csk_clear_xmit_timers(sk); 579 } 580 581 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 582 unsigned int tcp_current_mss(struct sock *sk); 583 584 /* Bound MSS / TSO packet size with the half of the window */ 585 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 586 { 587 int cutoff; 588 589 /* When peer uses tiny windows, there is no use in packetizing 590 * to sub-MSS pieces for the sake of SWS or making sure there 591 * are enough packets in the pipe for fast recovery. 592 * 593 * On the other hand, for extremely large MSS devices, handling 594 * smaller than MSS windows in this way does make sense. 595 */ 596 if (tp->max_window > TCP_MSS_DEFAULT) 597 cutoff = (tp->max_window >> 1); 598 else 599 cutoff = tp->max_window; 600 601 if (cutoff && pktsize > cutoff) 602 return max_t(int, cutoff, 68U - tp->tcp_header_len); 603 else 604 return pktsize; 605 } 606 607 /* tcp.c */ 608 void tcp_get_info(struct sock *, struct tcp_info *); 609 610 /* Read 'sendfile()'-style from a TCP socket */ 611 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 612 sk_read_actor_t recv_actor); 613 614 void tcp_initialize_rcv_mss(struct sock *sk); 615 616 int tcp_mtu_to_mss(struct sock *sk, int pmtu); 617 int tcp_mss_to_mtu(struct sock *sk, int mss); 618 void tcp_mtup_init(struct sock *sk); 619 void tcp_init_buffer_space(struct sock *sk); 620 621 static inline void tcp_bound_rto(const struct sock *sk) 622 { 623 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 624 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 625 } 626 627 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 628 { 629 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us); 630 } 631 632 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 633 { 634 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 635 ntohl(TCP_FLAG_ACK) | 636 snd_wnd); 637 } 638 639 static inline void tcp_fast_path_on(struct tcp_sock *tp) 640 { 641 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 642 } 643 644 static inline void tcp_fast_path_check(struct sock *sk) 645 { 646 struct tcp_sock *tp = tcp_sk(sk); 647 648 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) && 649 tp->rcv_wnd && 650 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 651 !tp->urg_data) 652 tcp_fast_path_on(tp); 653 } 654 655 /* Compute the actual rto_min value */ 656 static inline u32 tcp_rto_min(struct sock *sk) 657 { 658 const struct dst_entry *dst = __sk_dst_get(sk); 659 u32 rto_min = TCP_RTO_MIN; 660 661 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 662 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 663 return rto_min; 664 } 665 666 static inline u32 tcp_rto_min_us(struct sock *sk) 667 { 668 return jiffies_to_usecs(tcp_rto_min(sk)); 669 } 670 671 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst) 672 { 673 return dst_metric_locked(dst, RTAX_CC_ALGO); 674 } 675 676 /* Minimum RTT in usec. ~0 means not available. */ 677 static inline u32 tcp_min_rtt(const struct tcp_sock *tp) 678 { 679 return minmax_get(&tp->rtt_min); 680 } 681 682 /* Compute the actual receive window we are currently advertising. 683 * Rcv_nxt can be after the window if our peer push more data 684 * than the offered window. 685 */ 686 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 687 { 688 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 689 690 if (win < 0) 691 win = 0; 692 return (u32) win; 693 } 694 695 /* Choose a new window, without checks for shrinking, and without 696 * scaling applied to the result. The caller does these things 697 * if necessary. This is a "raw" window selection. 698 */ 699 u32 __tcp_select_window(struct sock *sk); 700 701 void tcp_send_window_probe(struct sock *sk); 702 703 /* TCP timestamps are only 32-bits, this causes a slight 704 * complication on 64-bit systems since we store a snapshot 705 * of jiffies in the buffer control blocks below. We decided 706 * to use only the low 32-bits of jiffies and hide the ugly 707 * casts with the following macro. 708 */ 709 #define tcp_time_stamp ((__u32)(jiffies)) 710 711 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) 712 { 713 return skb->skb_mstamp.stamp_jiffies; 714 } 715 716 717 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 718 719 #define TCPHDR_FIN 0x01 720 #define TCPHDR_SYN 0x02 721 #define TCPHDR_RST 0x04 722 #define TCPHDR_PSH 0x08 723 #define TCPHDR_ACK 0x10 724 #define TCPHDR_URG 0x20 725 #define TCPHDR_ECE 0x40 726 #define TCPHDR_CWR 0x80 727 728 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) 729 730 /* This is what the send packet queuing engine uses to pass 731 * TCP per-packet control information to the transmission code. 732 * We also store the host-order sequence numbers in here too. 733 * This is 44 bytes if IPV6 is enabled. 734 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 735 */ 736 struct tcp_skb_cb { 737 __u32 seq; /* Starting sequence number */ 738 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 739 union { 740 /* Note : tcp_tw_isn is used in input path only 741 * (isn chosen by tcp_timewait_state_process()) 742 * 743 * tcp_gso_segs/size are used in write queue only, 744 * cf tcp_skb_pcount()/tcp_skb_mss() 745 */ 746 __u32 tcp_tw_isn; 747 struct { 748 u16 tcp_gso_segs; 749 u16 tcp_gso_size; 750 }; 751 }; 752 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 753 754 __u8 sacked; /* State flags for SACK/FACK. */ 755 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 756 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 757 #define TCPCB_LOST 0x04 /* SKB is lost */ 758 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 759 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */ 760 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 761 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \ 762 TCPCB_REPAIRED) 763 764 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 765 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */ 766 eor:1, /* Is skb MSG_EOR marked? */ 767 unused:6; 768 __u32 ack_seq; /* Sequence number ACK'd */ 769 union { 770 struct { 771 /* There is space for up to 24 bytes */ 772 __u32 in_flight:30,/* Bytes in flight at transmit */ 773 is_app_limited:1, /* cwnd not fully used? */ 774 unused:1; 775 /* pkts S/ACKed so far upon tx of skb, incl retrans: */ 776 __u32 delivered; 777 /* start of send pipeline phase */ 778 struct skb_mstamp first_tx_mstamp; 779 /* when we reached the "delivered" count */ 780 struct skb_mstamp delivered_mstamp; 781 } tx; /* only used for outgoing skbs */ 782 union { 783 struct inet_skb_parm h4; 784 #if IS_ENABLED(CONFIG_IPV6) 785 struct inet6_skb_parm h6; 786 #endif 787 } header; /* For incoming skbs */ 788 }; 789 }; 790 791 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 792 793 794 #if IS_ENABLED(CONFIG_IPV6) 795 /* This is the variant of inet6_iif() that must be used by TCP, 796 * as TCP moves IP6CB into a different location in skb->cb[] 797 */ 798 static inline int tcp_v6_iif(const struct sk_buff *skb) 799 { 800 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags); 801 802 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif; 803 } 804 #endif 805 806 /* TCP_SKB_CB reference means this can not be used from early demux */ 807 static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb) 808 { 809 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 810 if (!net->ipv4.sysctl_tcp_l3mdev_accept && 811 skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags)) 812 return true; 813 #endif 814 return false; 815 } 816 817 /* Due to TSO, an SKB can be composed of multiple actual 818 * packets. To keep these tracked properly, we use this. 819 */ 820 static inline int tcp_skb_pcount(const struct sk_buff *skb) 821 { 822 return TCP_SKB_CB(skb)->tcp_gso_segs; 823 } 824 825 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 826 { 827 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 828 } 829 830 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 831 { 832 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 833 } 834 835 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ 836 static inline int tcp_skb_mss(const struct sk_buff *skb) 837 { 838 return TCP_SKB_CB(skb)->tcp_gso_size; 839 } 840 841 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb) 842 { 843 return likely(!TCP_SKB_CB(skb)->eor); 844 } 845 846 /* Events passed to congestion control interface */ 847 enum tcp_ca_event { 848 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 849 CA_EVENT_CWND_RESTART, /* congestion window restart */ 850 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 851 CA_EVENT_LOSS, /* loss timeout */ 852 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 853 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 854 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */ 855 CA_EVENT_NON_DELAYED_ACK, 856 }; 857 858 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 859 enum tcp_ca_ack_event_flags { 860 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 861 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 862 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 863 }; 864 865 /* 866 * Interface for adding new TCP congestion control handlers 867 */ 868 #define TCP_CA_NAME_MAX 16 869 #define TCP_CA_MAX 128 870 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 871 872 #define TCP_CA_UNSPEC 0 873 874 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 875 #define TCP_CONG_NON_RESTRICTED 0x1 876 /* Requires ECN/ECT set on all packets */ 877 #define TCP_CONG_NEEDS_ECN 0x2 878 879 union tcp_cc_info; 880 881 struct ack_sample { 882 u32 pkts_acked; 883 s32 rtt_us; 884 u32 in_flight; 885 }; 886 887 /* A rate sample measures the number of (original/retransmitted) data 888 * packets delivered "delivered" over an interval of time "interval_us". 889 * The tcp_rate.c code fills in the rate sample, and congestion 890 * control modules that define a cong_control function to run at the end 891 * of ACK processing can optionally chose to consult this sample when 892 * setting cwnd and pacing rate. 893 * A sample is invalid if "delivered" or "interval_us" is negative. 894 */ 895 struct rate_sample { 896 struct skb_mstamp prior_mstamp; /* starting timestamp for interval */ 897 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */ 898 s32 delivered; /* number of packets delivered over interval */ 899 long interval_us; /* time for tp->delivered to incr "delivered" */ 900 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */ 901 int losses; /* number of packets marked lost upon ACK */ 902 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */ 903 u32 prior_in_flight; /* in flight before this ACK */ 904 bool is_app_limited; /* is sample from packet with bubble in pipe? */ 905 bool is_retrans; /* is sample from retransmission? */ 906 }; 907 908 struct tcp_congestion_ops { 909 struct list_head list; 910 u32 key; 911 u32 flags; 912 913 /* initialize private data (optional) */ 914 void (*init)(struct sock *sk); 915 /* cleanup private data (optional) */ 916 void (*release)(struct sock *sk); 917 918 /* return slow start threshold (required) */ 919 u32 (*ssthresh)(struct sock *sk); 920 /* do new cwnd calculation (required) */ 921 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 922 /* call before changing ca_state (optional) */ 923 void (*set_state)(struct sock *sk, u8 new_state); 924 /* call when cwnd event occurs (optional) */ 925 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 926 /* call when ack arrives (optional) */ 927 void (*in_ack_event)(struct sock *sk, u32 flags); 928 /* new value of cwnd after loss (optional) */ 929 u32 (*undo_cwnd)(struct sock *sk); 930 /* hook for packet ack accounting (optional) */ 931 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample); 932 /* suggest number of segments for each skb to transmit (optional) */ 933 u32 (*tso_segs_goal)(struct sock *sk); 934 /* returns the multiplier used in tcp_sndbuf_expand (optional) */ 935 u32 (*sndbuf_expand)(struct sock *sk); 936 /* call when packets are delivered to update cwnd and pacing rate, 937 * after all the ca_state processing. (optional) 938 */ 939 void (*cong_control)(struct sock *sk, const struct rate_sample *rs); 940 /* get info for inet_diag (optional) */ 941 size_t (*get_info)(struct sock *sk, u32 ext, int *attr, 942 union tcp_cc_info *info); 943 944 char name[TCP_CA_NAME_MAX]; 945 struct module *owner; 946 }; 947 948 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 949 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 950 951 void tcp_assign_congestion_control(struct sock *sk); 952 void tcp_init_congestion_control(struct sock *sk); 953 void tcp_cleanup_congestion_control(struct sock *sk); 954 int tcp_set_default_congestion_control(const char *name); 955 void tcp_get_default_congestion_control(char *name); 956 void tcp_get_available_congestion_control(char *buf, size_t len); 957 void tcp_get_allowed_congestion_control(char *buf, size_t len); 958 int tcp_set_allowed_congestion_control(char *allowed); 959 int tcp_set_congestion_control(struct sock *sk, const char *name); 960 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); 961 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); 962 963 u32 tcp_reno_ssthresh(struct sock *sk); 964 u32 tcp_reno_undo_cwnd(struct sock *sk); 965 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 966 extern struct tcp_congestion_ops tcp_reno; 967 968 struct tcp_congestion_ops *tcp_ca_find_key(u32 key); 969 u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca); 970 #ifdef CONFIG_INET 971 char *tcp_ca_get_name_by_key(u32 key, char *buffer); 972 #else 973 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) 974 { 975 return NULL; 976 } 977 #endif 978 979 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 980 { 981 const struct inet_connection_sock *icsk = inet_csk(sk); 982 983 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 984 } 985 986 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 987 { 988 struct inet_connection_sock *icsk = inet_csk(sk); 989 990 if (icsk->icsk_ca_ops->set_state) 991 icsk->icsk_ca_ops->set_state(sk, ca_state); 992 icsk->icsk_ca_state = ca_state; 993 } 994 995 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 996 { 997 const struct inet_connection_sock *icsk = inet_csk(sk); 998 999 if (icsk->icsk_ca_ops->cwnd_event) 1000 icsk->icsk_ca_ops->cwnd_event(sk, event); 1001 } 1002 1003 /* From tcp_rate.c */ 1004 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb); 1005 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb, 1006 struct rate_sample *rs); 1007 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost, 1008 struct skb_mstamp *now, struct rate_sample *rs); 1009 void tcp_rate_check_app_limited(struct sock *sk); 1010 1011 /* These functions determine how the current flow behaves in respect of SACK 1012 * handling. SACK is negotiated with the peer, and therefore it can vary 1013 * between different flows. 1014 * 1015 * tcp_is_sack - SACK enabled 1016 * tcp_is_reno - No SACK 1017 * tcp_is_fack - FACK enabled, implies SACK enabled 1018 */ 1019 static inline int tcp_is_sack(const struct tcp_sock *tp) 1020 { 1021 return tp->rx_opt.sack_ok; 1022 } 1023 1024 static inline bool tcp_is_reno(const struct tcp_sock *tp) 1025 { 1026 return !tcp_is_sack(tp); 1027 } 1028 1029 static inline bool tcp_is_fack(const struct tcp_sock *tp) 1030 { 1031 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED; 1032 } 1033 1034 static inline void tcp_enable_fack(struct tcp_sock *tp) 1035 { 1036 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED; 1037 } 1038 1039 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 1040 { 1041 return tp->sacked_out + tp->lost_out; 1042 } 1043 1044 /* This determines how many packets are "in the network" to the best 1045 * of our knowledge. In many cases it is conservative, but where 1046 * detailed information is available from the receiver (via SACK 1047 * blocks etc.) we can make more aggressive calculations. 1048 * 1049 * Use this for decisions involving congestion control, use just 1050 * tp->packets_out to determine if the send queue is empty or not. 1051 * 1052 * Read this equation as: 1053 * 1054 * "Packets sent once on transmission queue" MINUS 1055 * "Packets left network, but not honestly ACKed yet" PLUS 1056 * "Packets fast retransmitted" 1057 */ 1058 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 1059 { 1060 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 1061 } 1062 1063 #define TCP_INFINITE_SSTHRESH 0x7fffffff 1064 1065 static inline bool tcp_in_slow_start(const struct tcp_sock *tp) 1066 { 1067 return tp->snd_cwnd < tp->snd_ssthresh; 1068 } 1069 1070 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 1071 { 1072 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 1073 } 1074 1075 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 1076 { 1077 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 1078 (1 << inet_csk(sk)->icsk_ca_state); 1079 } 1080 1081 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 1082 * The exception is cwnd reduction phase, when cwnd is decreasing towards 1083 * ssthresh. 1084 */ 1085 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 1086 { 1087 const struct tcp_sock *tp = tcp_sk(sk); 1088 1089 if (tcp_in_cwnd_reduction(sk)) 1090 return tp->snd_ssthresh; 1091 else 1092 return max(tp->snd_ssthresh, 1093 ((tp->snd_cwnd >> 1) + 1094 (tp->snd_cwnd >> 2))); 1095 } 1096 1097 /* Use define here intentionally to get WARN_ON location shown at the caller */ 1098 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 1099 1100 void tcp_enter_cwr(struct sock *sk); 1101 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 1102 1103 /* The maximum number of MSS of available cwnd for which TSO defers 1104 * sending if not using sysctl_tcp_tso_win_divisor. 1105 */ 1106 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 1107 { 1108 return 3; 1109 } 1110 1111 /* Returns end sequence number of the receiver's advertised window */ 1112 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 1113 { 1114 return tp->snd_una + tp->snd_wnd; 1115 } 1116 1117 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 1118 * flexible approach. The RFC suggests cwnd should not be raised unless 1119 * it was fully used previously. And that's exactly what we do in 1120 * congestion avoidance mode. But in slow start we allow cwnd to grow 1121 * as long as the application has used half the cwnd. 1122 * Example : 1123 * cwnd is 10 (IW10), but application sends 9 frames. 1124 * We allow cwnd to reach 18 when all frames are ACKed. 1125 * This check is safe because it's as aggressive as slow start which already 1126 * risks 100% overshoot. The advantage is that we discourage application to 1127 * either send more filler packets or data to artificially blow up the cwnd 1128 * usage, and allow application-limited process to probe bw more aggressively. 1129 */ 1130 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1131 { 1132 const struct tcp_sock *tp = tcp_sk(sk); 1133 1134 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1135 if (tcp_in_slow_start(tp)) 1136 return tp->snd_cwnd < 2 * tp->max_packets_out; 1137 1138 return tp->is_cwnd_limited; 1139 } 1140 1141 /* Something is really bad, we could not queue an additional packet, 1142 * because qdisc is full or receiver sent a 0 window. 1143 * We do not want to add fuel to the fire, or abort too early, 1144 * so make sure the timer we arm now is at least 200ms in the future, 1145 * regardless of current icsk_rto value (as it could be ~2ms) 1146 */ 1147 static inline unsigned long tcp_probe0_base(const struct sock *sk) 1148 { 1149 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); 1150 } 1151 1152 /* Variant of inet_csk_rto_backoff() used for zero window probes */ 1153 static inline unsigned long tcp_probe0_when(const struct sock *sk, 1154 unsigned long max_when) 1155 { 1156 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff; 1157 1158 return (unsigned long)min_t(u64, when, max_when); 1159 } 1160 1161 static inline void tcp_check_probe_timer(struct sock *sk) 1162 { 1163 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) 1164 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1165 tcp_probe0_base(sk), TCP_RTO_MAX); 1166 } 1167 1168 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1169 { 1170 tp->snd_wl1 = seq; 1171 } 1172 1173 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1174 { 1175 tp->snd_wl1 = seq; 1176 } 1177 1178 /* 1179 * Calculate(/check) TCP checksum 1180 */ 1181 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1182 __be32 daddr, __wsum base) 1183 { 1184 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1185 } 1186 1187 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1188 { 1189 return __skb_checksum_complete(skb); 1190 } 1191 1192 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1193 { 1194 return !skb_csum_unnecessary(skb) && 1195 __tcp_checksum_complete(skb); 1196 } 1197 1198 /* Prequeue for VJ style copy to user, combined with checksumming. */ 1199 1200 static inline void tcp_prequeue_init(struct tcp_sock *tp) 1201 { 1202 tp->ucopy.task = NULL; 1203 tp->ucopy.len = 0; 1204 tp->ucopy.memory = 0; 1205 skb_queue_head_init(&tp->ucopy.prequeue); 1206 } 1207 1208 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb); 1209 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb); 1210 int tcp_filter(struct sock *sk, struct sk_buff *skb); 1211 1212 #undef STATE_TRACE 1213 1214 #ifdef STATE_TRACE 1215 static const char *statename[]={ 1216 "Unused","Established","Syn Sent","Syn Recv", 1217 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1218 "Close Wait","Last ACK","Listen","Closing" 1219 }; 1220 #endif 1221 void tcp_set_state(struct sock *sk, int state); 1222 1223 void tcp_done(struct sock *sk); 1224 1225 int tcp_abort(struct sock *sk, int err); 1226 1227 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1228 { 1229 rx_opt->dsack = 0; 1230 rx_opt->num_sacks = 0; 1231 } 1232 1233 u32 tcp_default_init_rwnd(u32 mss); 1234 void tcp_cwnd_restart(struct sock *sk, s32 delta); 1235 1236 static inline void tcp_slow_start_after_idle_check(struct sock *sk) 1237 { 1238 struct tcp_sock *tp = tcp_sk(sk); 1239 s32 delta; 1240 1241 if (!sysctl_tcp_slow_start_after_idle || tp->packets_out) 1242 return; 1243 delta = tcp_time_stamp - tp->lsndtime; 1244 if (delta > inet_csk(sk)->icsk_rto) 1245 tcp_cwnd_restart(sk, delta); 1246 } 1247 1248 /* Determine a window scaling and initial window to offer. */ 1249 void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd, 1250 __u32 *window_clamp, int wscale_ok, 1251 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1252 1253 static inline int tcp_win_from_space(int space) 1254 { 1255 return sysctl_tcp_adv_win_scale<=0 ? 1256 (space>>(-sysctl_tcp_adv_win_scale)) : 1257 space - (space>>sysctl_tcp_adv_win_scale); 1258 } 1259 1260 /* Note: caller must be prepared to deal with negative returns */ 1261 static inline int tcp_space(const struct sock *sk) 1262 { 1263 return tcp_win_from_space(sk->sk_rcvbuf - 1264 atomic_read(&sk->sk_rmem_alloc)); 1265 } 1266 1267 static inline int tcp_full_space(const struct sock *sk) 1268 { 1269 return tcp_win_from_space(sk->sk_rcvbuf); 1270 } 1271 1272 extern void tcp_openreq_init_rwin(struct request_sock *req, 1273 const struct sock *sk_listener, 1274 const struct dst_entry *dst); 1275 1276 void tcp_enter_memory_pressure(struct sock *sk); 1277 1278 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1279 { 1280 struct net *net = sock_net((struct sock *)tp); 1281 1282 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl; 1283 } 1284 1285 static inline int keepalive_time_when(const struct tcp_sock *tp) 1286 { 1287 struct net *net = sock_net((struct sock *)tp); 1288 1289 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time; 1290 } 1291 1292 static inline int keepalive_probes(const struct tcp_sock *tp) 1293 { 1294 struct net *net = sock_net((struct sock *)tp); 1295 1296 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes; 1297 } 1298 1299 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1300 { 1301 const struct inet_connection_sock *icsk = &tp->inet_conn; 1302 1303 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime, 1304 tcp_time_stamp - tp->rcv_tstamp); 1305 } 1306 1307 static inline int tcp_fin_time(const struct sock *sk) 1308 { 1309 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout; 1310 const int rto = inet_csk(sk)->icsk_rto; 1311 1312 if (fin_timeout < (rto << 2) - (rto >> 1)) 1313 fin_timeout = (rto << 2) - (rto >> 1); 1314 1315 return fin_timeout; 1316 } 1317 1318 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1319 int paws_win) 1320 { 1321 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1322 return true; 1323 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1324 return true; 1325 /* 1326 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1327 * then following tcp messages have valid values. Ignore 0 value, 1328 * or else 'negative' tsval might forbid us to accept their packets. 1329 */ 1330 if (!rx_opt->ts_recent) 1331 return true; 1332 return false; 1333 } 1334 1335 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1336 int rst) 1337 { 1338 if (tcp_paws_check(rx_opt, 0)) 1339 return false; 1340 1341 /* RST segments are not recommended to carry timestamp, 1342 and, if they do, it is recommended to ignore PAWS because 1343 "their cleanup function should take precedence over timestamps." 1344 Certainly, it is mistake. It is necessary to understand the reasons 1345 of this constraint to relax it: if peer reboots, clock may go 1346 out-of-sync and half-open connections will not be reset. 1347 Actually, the problem would be not existing if all 1348 the implementations followed draft about maintaining clock 1349 via reboots. Linux-2.2 DOES NOT! 1350 1351 However, we can relax time bounds for RST segments to MSL. 1352 */ 1353 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1354 return false; 1355 return true; 1356 } 1357 1358 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, 1359 int mib_idx, u32 *last_oow_ack_time); 1360 1361 static inline void tcp_mib_init(struct net *net) 1362 { 1363 /* See RFC 2012 */ 1364 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1); 1365 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1366 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1367 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1); 1368 } 1369 1370 /* from STCP */ 1371 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1372 { 1373 tp->lost_skb_hint = NULL; 1374 } 1375 1376 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1377 { 1378 tcp_clear_retrans_hints_partial(tp); 1379 tp->retransmit_skb_hint = NULL; 1380 } 1381 1382 union tcp_md5_addr { 1383 struct in_addr a4; 1384 #if IS_ENABLED(CONFIG_IPV6) 1385 struct in6_addr a6; 1386 #endif 1387 }; 1388 1389 /* - key database */ 1390 struct tcp_md5sig_key { 1391 struct hlist_node node; 1392 u8 keylen; 1393 u8 family; /* AF_INET or AF_INET6 */ 1394 union tcp_md5_addr addr; 1395 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1396 struct rcu_head rcu; 1397 }; 1398 1399 /* - sock block */ 1400 struct tcp_md5sig_info { 1401 struct hlist_head head; 1402 struct rcu_head rcu; 1403 }; 1404 1405 /* - pseudo header */ 1406 struct tcp4_pseudohdr { 1407 __be32 saddr; 1408 __be32 daddr; 1409 __u8 pad; 1410 __u8 protocol; 1411 __be16 len; 1412 }; 1413 1414 struct tcp6_pseudohdr { 1415 struct in6_addr saddr; 1416 struct in6_addr daddr; 1417 __be32 len; 1418 __be32 protocol; /* including padding */ 1419 }; 1420 1421 union tcp_md5sum_block { 1422 struct tcp4_pseudohdr ip4; 1423 #if IS_ENABLED(CONFIG_IPV6) 1424 struct tcp6_pseudohdr ip6; 1425 #endif 1426 }; 1427 1428 /* - pool: digest algorithm, hash description and scratch buffer */ 1429 struct tcp_md5sig_pool { 1430 struct ahash_request *md5_req; 1431 void *scratch; 1432 }; 1433 1434 /* - functions */ 1435 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1436 const struct sock *sk, const struct sk_buff *skb); 1437 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1438 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp); 1439 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1440 int family); 1441 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 1442 const struct sock *addr_sk); 1443 1444 #ifdef CONFIG_TCP_MD5SIG 1445 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1446 const union tcp_md5_addr *addr, 1447 int family); 1448 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1449 #else 1450 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1451 const union tcp_md5_addr *addr, 1452 int family) 1453 { 1454 return NULL; 1455 } 1456 #define tcp_twsk_md5_key(twsk) NULL 1457 #endif 1458 1459 bool tcp_alloc_md5sig_pool(void); 1460 1461 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1462 static inline void tcp_put_md5sig_pool(void) 1463 { 1464 local_bh_enable(); 1465 } 1466 1467 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1468 unsigned int header_len); 1469 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1470 const struct tcp_md5sig_key *key); 1471 1472 /* From tcp_fastopen.c */ 1473 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1474 struct tcp_fastopen_cookie *cookie, int *syn_loss, 1475 unsigned long *last_syn_loss); 1476 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1477 struct tcp_fastopen_cookie *cookie, bool syn_lost, 1478 u16 try_exp); 1479 struct tcp_fastopen_request { 1480 /* Fast Open cookie. Size 0 means a cookie request */ 1481 struct tcp_fastopen_cookie cookie; 1482 struct msghdr *data; /* data in MSG_FASTOPEN */ 1483 size_t size; 1484 int copied; /* queued in tcp_connect() */ 1485 }; 1486 void tcp_free_fastopen_req(struct tcp_sock *tp); 1487 1488 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; 1489 int tcp_fastopen_reset_cipher(void *key, unsigned int len); 1490 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb); 1491 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1492 struct request_sock *req, 1493 struct tcp_fastopen_cookie *foc, 1494 struct dst_entry *dst); 1495 void tcp_fastopen_init_key_once(bool publish); 1496 bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss, 1497 struct tcp_fastopen_cookie *cookie); 1498 bool tcp_fastopen_defer_connect(struct sock *sk, int *err); 1499 #define TCP_FASTOPEN_KEY_LENGTH 16 1500 1501 /* Fastopen key context */ 1502 struct tcp_fastopen_context { 1503 struct crypto_cipher *tfm; 1504 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1505 struct rcu_head rcu; 1506 }; 1507 1508 /* Latencies incurred by various limits for a sender. They are 1509 * chronograph-like stats that are mutually exclusive. 1510 */ 1511 enum tcp_chrono { 1512 TCP_CHRONO_UNSPEC, 1513 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */ 1514 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */ 1515 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */ 1516 __TCP_CHRONO_MAX, 1517 }; 1518 1519 void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type); 1520 void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type); 1521 1522 /* write queue abstraction */ 1523 static inline void tcp_write_queue_purge(struct sock *sk) 1524 { 1525 struct sk_buff *skb; 1526 1527 tcp_chrono_stop(sk, TCP_CHRONO_BUSY); 1528 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) 1529 sk_wmem_free_skb(sk, skb); 1530 sk_mem_reclaim(sk); 1531 tcp_clear_all_retrans_hints(tcp_sk(sk)); 1532 } 1533 1534 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1535 { 1536 return skb_peek(&sk->sk_write_queue); 1537 } 1538 1539 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1540 { 1541 return skb_peek_tail(&sk->sk_write_queue); 1542 } 1543 1544 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk, 1545 const struct sk_buff *skb) 1546 { 1547 return skb_queue_next(&sk->sk_write_queue, skb); 1548 } 1549 1550 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk, 1551 const struct sk_buff *skb) 1552 { 1553 return skb_queue_prev(&sk->sk_write_queue, skb); 1554 } 1555 1556 #define tcp_for_write_queue(skb, sk) \ 1557 skb_queue_walk(&(sk)->sk_write_queue, skb) 1558 1559 #define tcp_for_write_queue_from(skb, sk) \ 1560 skb_queue_walk_from(&(sk)->sk_write_queue, skb) 1561 1562 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1563 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1564 1565 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1566 { 1567 return sk->sk_send_head; 1568 } 1569 1570 static inline bool tcp_skb_is_last(const struct sock *sk, 1571 const struct sk_buff *skb) 1572 { 1573 return skb_queue_is_last(&sk->sk_write_queue, skb); 1574 } 1575 1576 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb) 1577 { 1578 if (tcp_skb_is_last(sk, skb)) 1579 sk->sk_send_head = NULL; 1580 else 1581 sk->sk_send_head = tcp_write_queue_next(sk, skb); 1582 } 1583 1584 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1585 { 1586 if (sk->sk_send_head == skb_unlinked) { 1587 sk->sk_send_head = NULL; 1588 tcp_chrono_stop(sk, TCP_CHRONO_BUSY); 1589 } 1590 if (tcp_sk(sk)->highest_sack == skb_unlinked) 1591 tcp_sk(sk)->highest_sack = NULL; 1592 } 1593 1594 static inline void tcp_init_send_head(struct sock *sk) 1595 { 1596 sk->sk_send_head = NULL; 1597 } 1598 1599 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1600 { 1601 __skb_queue_tail(&sk->sk_write_queue, skb); 1602 } 1603 1604 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1605 { 1606 __tcp_add_write_queue_tail(sk, skb); 1607 1608 /* Queue it, remembering where we must start sending. */ 1609 if (sk->sk_send_head == NULL) { 1610 sk->sk_send_head = skb; 1611 tcp_chrono_start(sk, TCP_CHRONO_BUSY); 1612 1613 if (tcp_sk(sk)->highest_sack == NULL) 1614 tcp_sk(sk)->highest_sack = skb; 1615 } 1616 } 1617 1618 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb) 1619 { 1620 __skb_queue_head(&sk->sk_write_queue, skb); 1621 } 1622 1623 /* Insert buff after skb on the write queue of sk. */ 1624 static inline void tcp_insert_write_queue_after(struct sk_buff *skb, 1625 struct sk_buff *buff, 1626 struct sock *sk) 1627 { 1628 __skb_queue_after(&sk->sk_write_queue, skb, buff); 1629 } 1630 1631 /* Insert new before skb on the write queue of sk. */ 1632 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1633 struct sk_buff *skb, 1634 struct sock *sk) 1635 { 1636 __skb_queue_before(&sk->sk_write_queue, skb, new); 1637 1638 if (sk->sk_send_head == skb) 1639 sk->sk_send_head = new; 1640 } 1641 1642 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1643 { 1644 __skb_unlink(skb, &sk->sk_write_queue); 1645 } 1646 1647 static inline bool tcp_write_queue_empty(struct sock *sk) 1648 { 1649 return skb_queue_empty(&sk->sk_write_queue); 1650 } 1651 1652 static inline void tcp_push_pending_frames(struct sock *sk) 1653 { 1654 if (tcp_send_head(sk)) { 1655 struct tcp_sock *tp = tcp_sk(sk); 1656 1657 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1658 } 1659 } 1660 1661 /* Start sequence of the skb just after the highest skb with SACKed 1662 * bit, valid only if sacked_out > 0 or when the caller has ensured 1663 * validity by itself. 1664 */ 1665 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1666 { 1667 if (!tp->sacked_out) 1668 return tp->snd_una; 1669 1670 if (tp->highest_sack == NULL) 1671 return tp->snd_nxt; 1672 1673 return TCP_SKB_CB(tp->highest_sack)->seq; 1674 } 1675 1676 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1677 { 1678 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL : 1679 tcp_write_queue_next(sk, skb); 1680 } 1681 1682 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1683 { 1684 return tcp_sk(sk)->highest_sack; 1685 } 1686 1687 static inline void tcp_highest_sack_reset(struct sock *sk) 1688 { 1689 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk); 1690 } 1691 1692 /* Called when old skb is about to be deleted (to be combined with new skb) */ 1693 static inline void tcp_highest_sack_combine(struct sock *sk, 1694 struct sk_buff *old, 1695 struct sk_buff *new) 1696 { 1697 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack)) 1698 tcp_sk(sk)->highest_sack = new; 1699 } 1700 1701 /* This helper checks if socket has IP_TRANSPARENT set */ 1702 static inline bool inet_sk_transparent(const struct sock *sk) 1703 { 1704 switch (sk->sk_state) { 1705 case TCP_TIME_WAIT: 1706 return inet_twsk(sk)->tw_transparent; 1707 case TCP_NEW_SYN_RECV: 1708 return inet_rsk(inet_reqsk(sk))->no_srccheck; 1709 } 1710 return inet_sk(sk)->transparent; 1711 } 1712 1713 /* Determines whether this is a thin stream (which may suffer from 1714 * increased latency). Used to trigger latency-reducing mechanisms. 1715 */ 1716 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1717 { 1718 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1719 } 1720 1721 /* /proc */ 1722 enum tcp_seq_states { 1723 TCP_SEQ_STATE_LISTENING, 1724 TCP_SEQ_STATE_ESTABLISHED, 1725 }; 1726 1727 int tcp_seq_open(struct inode *inode, struct file *file); 1728 1729 struct tcp_seq_afinfo { 1730 char *name; 1731 sa_family_t family; 1732 const struct file_operations *seq_fops; 1733 struct seq_operations seq_ops; 1734 }; 1735 1736 struct tcp_iter_state { 1737 struct seq_net_private p; 1738 sa_family_t family; 1739 enum tcp_seq_states state; 1740 struct sock *syn_wait_sk; 1741 int bucket, offset, sbucket, num; 1742 loff_t last_pos; 1743 }; 1744 1745 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1746 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1747 1748 extern struct request_sock_ops tcp_request_sock_ops; 1749 extern struct request_sock_ops tcp6_request_sock_ops; 1750 1751 void tcp_v4_destroy_sock(struct sock *sk); 1752 1753 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 1754 netdev_features_t features); 1755 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb); 1756 int tcp_gro_complete(struct sk_buff *skb); 1757 1758 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 1759 1760 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 1761 { 1762 struct net *net = sock_net((struct sock *)tp); 1763 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat; 1764 } 1765 1766 static inline bool tcp_stream_memory_free(const struct sock *sk) 1767 { 1768 const struct tcp_sock *tp = tcp_sk(sk); 1769 u32 notsent_bytes = tp->write_seq - tp->snd_nxt; 1770 1771 return notsent_bytes < tcp_notsent_lowat(tp); 1772 } 1773 1774 #ifdef CONFIG_PROC_FS 1775 int tcp4_proc_init(void); 1776 void tcp4_proc_exit(void); 1777 #endif 1778 1779 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req); 1780 int tcp_conn_request(struct request_sock_ops *rsk_ops, 1781 const struct tcp_request_sock_ops *af_ops, 1782 struct sock *sk, struct sk_buff *skb); 1783 1784 /* TCP af-specific functions */ 1785 struct tcp_sock_af_ops { 1786 #ifdef CONFIG_TCP_MD5SIG 1787 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk, 1788 const struct sock *addr_sk); 1789 int (*calc_md5_hash)(char *location, 1790 const struct tcp_md5sig_key *md5, 1791 const struct sock *sk, 1792 const struct sk_buff *skb); 1793 int (*md5_parse)(struct sock *sk, 1794 char __user *optval, 1795 int optlen); 1796 #endif 1797 }; 1798 1799 struct tcp_request_sock_ops { 1800 u16 mss_clamp; 1801 #ifdef CONFIG_TCP_MD5SIG 1802 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk, 1803 const struct sock *addr_sk); 1804 int (*calc_md5_hash) (char *location, 1805 const struct tcp_md5sig_key *md5, 1806 const struct sock *sk, 1807 const struct sk_buff *skb); 1808 #endif 1809 void (*init_req)(struct request_sock *req, 1810 const struct sock *sk_listener, 1811 struct sk_buff *skb); 1812 #ifdef CONFIG_SYN_COOKIES 1813 __u32 (*cookie_init_seq)(const struct sk_buff *skb, 1814 __u16 *mss); 1815 #endif 1816 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl, 1817 const struct request_sock *req, 1818 bool *strict); 1819 __u32 (*init_seq)(const struct sk_buff *skb, u32 *tsoff); 1820 int (*send_synack)(const struct sock *sk, struct dst_entry *dst, 1821 struct flowi *fl, struct request_sock *req, 1822 struct tcp_fastopen_cookie *foc, 1823 enum tcp_synack_type synack_type); 1824 }; 1825 1826 #ifdef CONFIG_SYN_COOKIES 1827 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1828 const struct sock *sk, struct sk_buff *skb, 1829 __u16 *mss) 1830 { 1831 tcp_synq_overflow(sk); 1832 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); 1833 return ops->cookie_init_seq(skb, mss); 1834 } 1835 #else 1836 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1837 const struct sock *sk, struct sk_buff *skb, 1838 __u16 *mss) 1839 { 1840 return 0; 1841 } 1842 #endif 1843 1844 int tcpv4_offload_init(void); 1845 1846 void tcp_v4_init(void); 1847 void tcp_init(void); 1848 1849 /* tcp_recovery.c */ 1850 extern void tcp_rack_mark_lost(struct sock *sk, const struct skb_mstamp *now); 1851 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq, 1852 const struct skb_mstamp *xmit_time, 1853 const struct skb_mstamp *ack_time); 1854 extern void tcp_rack_reo_timeout(struct sock *sk); 1855 1856 /* 1857 * Save and compile IPv4 options, return a pointer to it 1858 */ 1859 static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb) 1860 { 1861 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; 1862 struct ip_options_rcu *dopt = NULL; 1863 1864 if (opt->optlen) { 1865 int opt_size = sizeof(*dopt) + opt->optlen; 1866 1867 dopt = kmalloc(opt_size, GFP_ATOMIC); 1868 if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) { 1869 kfree(dopt); 1870 dopt = NULL; 1871 } 1872 } 1873 return dopt; 1874 } 1875 1876 /* locally generated TCP pure ACKs have skb->truesize == 2 1877 * (check tcp_send_ack() in net/ipv4/tcp_output.c ) 1878 * This is much faster than dissecting the packet to find out. 1879 * (Think of GRE encapsulations, IPv4, IPv6, ...) 1880 */ 1881 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb) 1882 { 1883 return skb->truesize == 2; 1884 } 1885 1886 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb) 1887 { 1888 skb->truesize = 2; 1889 } 1890 1891 static inline int tcp_inq(struct sock *sk) 1892 { 1893 struct tcp_sock *tp = tcp_sk(sk); 1894 int answ; 1895 1896 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { 1897 answ = 0; 1898 } else if (sock_flag(sk, SOCK_URGINLINE) || 1899 !tp->urg_data || 1900 before(tp->urg_seq, tp->copied_seq) || 1901 !before(tp->urg_seq, tp->rcv_nxt)) { 1902 1903 answ = tp->rcv_nxt - tp->copied_seq; 1904 1905 /* Subtract 1, if FIN was received */ 1906 if (answ && sock_flag(sk, SOCK_DONE)) 1907 answ--; 1908 } else { 1909 answ = tp->urg_seq - tp->copied_seq; 1910 } 1911 1912 return answ; 1913 } 1914 1915 int tcp_peek_len(struct socket *sock); 1916 1917 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb) 1918 { 1919 u16 segs_in; 1920 1921 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs); 1922 tp->segs_in += segs_in; 1923 if (skb->len > tcp_hdrlen(skb)) 1924 tp->data_segs_in += segs_in; 1925 } 1926 1927 /* 1928 * TCP listen path runs lockless. 1929 * We forced "struct sock" to be const qualified to make sure 1930 * we don't modify one of its field by mistake. 1931 * Here, we increment sk_drops which is an atomic_t, so we can safely 1932 * make sock writable again. 1933 */ 1934 static inline void tcp_listendrop(const struct sock *sk) 1935 { 1936 atomic_inc(&((struct sock *)sk)->sk_drops); 1937 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 1938 } 1939 1940 #endif /* _TCP_H */ 1941