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_reuseport.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 #include <linux/bpf-cgroup.h> 50 51 extern struct inet_hashinfo tcp_hashinfo; 52 53 extern struct percpu_counter tcp_orphan_count; 54 void tcp_time_wait(struct sock *sk, int state, int timeo); 55 56 #define MAX_TCP_HEADER (128 + MAX_HEADER) 57 #define MAX_TCP_OPTION_SPACE 40 58 59 /* 60 * Never offer a window over 32767 without using window scaling. Some 61 * poor stacks do signed 16bit maths! 62 */ 63 #define MAX_TCP_WINDOW 32767U 64 65 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */ 66 #define TCP_MIN_MSS 88U 67 68 /* The least MTU to use for probing */ 69 #define TCP_BASE_MSS 1024 70 71 /* probing interval, default to 10 minutes as per RFC4821 */ 72 #define TCP_PROBE_INTERVAL 600 73 74 /* Specify interval when tcp mtu probing will stop */ 75 #define TCP_PROBE_THRESHOLD 8 76 77 /* After receiving this amount of duplicate ACKs fast retransmit starts. */ 78 #define TCP_FASTRETRANS_THRESH 3 79 80 /* Maximal number of ACKs sent quickly to accelerate slow-start. */ 81 #define TCP_MAX_QUICKACKS 16U 82 83 /* Maximal number of window scale according to RFC1323 */ 84 #define TCP_MAX_WSCALE 14U 85 86 /* urg_data states */ 87 #define TCP_URG_VALID 0x0100 88 #define TCP_URG_NOTYET 0x0200 89 #define TCP_URG_READ 0x0400 90 91 #define TCP_RETR1 3 /* 92 * This is how many retries it does before it 93 * tries to figure out if the gateway is 94 * down. Minimal RFC value is 3; it corresponds 95 * to ~3sec-8min depending on RTO. 96 */ 97 98 #define TCP_RETR2 15 /* 99 * This should take at least 100 * 90 minutes to time out. 101 * RFC1122 says that the limit is 100 sec. 102 * 15 is ~13-30min depending on RTO. 103 */ 104 105 #define TCP_SYN_RETRIES 6 /* This is how many retries are done 106 * when active opening a connection. 107 * RFC1122 says the minimum retry MUST 108 * be at least 180secs. Nevertheless 109 * this value is corresponding to 110 * 63secs of retransmission with the 111 * current initial RTO. 112 */ 113 114 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done 115 * when passive opening a connection. 116 * This is corresponding to 31secs of 117 * retransmission with the current 118 * initial RTO. 119 */ 120 121 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT 122 * state, about 60 seconds */ 123 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN 124 /* BSD style FIN_WAIT2 deadlock breaker. 125 * It used to be 3min, new value is 60sec, 126 * to combine FIN-WAIT-2 timeout with 127 * TIME-WAIT timer. 128 */ 129 130 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ 131 #if HZ >= 100 132 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */ 133 #define TCP_ATO_MIN ((unsigned)(HZ/25)) 134 #else 135 #define TCP_DELACK_MIN 4U 136 #define TCP_ATO_MIN 4U 137 #endif 138 #define TCP_RTO_MAX ((unsigned)(120*HZ)) 139 #define TCP_RTO_MIN ((unsigned)(HZ/5)) 140 #define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */ 141 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */ 142 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now 143 * used as a fallback RTO for the 144 * initial data transmission if no 145 * valid RTT sample has been acquired, 146 * most likely due to retrans in 3WHS. 147 */ 148 149 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes 150 * for local resources. 151 */ 152 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ 153 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ 154 #define TCP_KEEPALIVE_INTVL (75*HZ) 155 156 #define MAX_TCP_KEEPIDLE 32767 157 #define MAX_TCP_KEEPINTVL 32767 158 #define MAX_TCP_KEEPCNT 127 159 #define MAX_TCP_SYNCNT 127 160 161 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */ 162 163 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24) 164 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated 165 * after this time. It should be equal 166 * (or greater than) TCP_TIMEWAIT_LEN 167 * to provide reliability equal to one 168 * provided by timewait state. 169 */ 170 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host 171 * timestamps. It must be less than 172 * minimal timewait lifetime. 173 */ 174 /* 175 * TCP option 176 */ 177 178 #define TCPOPT_NOP 1 /* Padding */ 179 #define TCPOPT_EOL 0 /* End of options */ 180 #define TCPOPT_MSS 2 /* Segment size negotiating */ 181 #define TCPOPT_WINDOW 3 /* Window scaling */ 182 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ 183 #define TCPOPT_SACK 5 /* SACK Block */ 184 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ 185 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */ 186 #define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */ 187 #define TCPOPT_EXP 254 /* Experimental */ 188 /* Magic number to be after the option value for sharing TCP 189 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt 190 */ 191 #define TCPOPT_FASTOPEN_MAGIC 0xF989 192 #define TCPOPT_SMC_MAGIC 0xE2D4C3D9 193 194 /* 195 * TCP option lengths 196 */ 197 198 #define TCPOLEN_MSS 4 199 #define TCPOLEN_WINDOW 3 200 #define TCPOLEN_SACK_PERM 2 201 #define TCPOLEN_TIMESTAMP 10 202 #define TCPOLEN_MD5SIG 18 203 #define TCPOLEN_FASTOPEN_BASE 2 204 #define TCPOLEN_EXP_FASTOPEN_BASE 4 205 #define TCPOLEN_EXP_SMC_BASE 6 206 207 /* But this is what stacks really send out. */ 208 #define TCPOLEN_TSTAMP_ALIGNED 12 209 #define TCPOLEN_WSCALE_ALIGNED 4 210 #define TCPOLEN_SACKPERM_ALIGNED 4 211 #define TCPOLEN_SACK_BASE 2 212 #define TCPOLEN_SACK_BASE_ALIGNED 4 213 #define TCPOLEN_SACK_PERBLOCK 8 214 #define TCPOLEN_MD5SIG_ALIGNED 20 215 #define TCPOLEN_MSS_ALIGNED 4 216 #define TCPOLEN_EXP_SMC_BASE_ALIGNED 8 217 218 /* Flags in tp->nonagle */ 219 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */ 220 #define TCP_NAGLE_CORK 2 /* Socket is corked */ 221 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */ 222 223 /* TCP thin-stream limits */ 224 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */ 225 226 /* TCP initial congestion window as per rfc6928 */ 227 #define TCP_INIT_CWND 10 228 229 /* Bit Flags for sysctl_tcp_fastopen */ 230 #define TFO_CLIENT_ENABLE 1 231 #define TFO_SERVER_ENABLE 2 232 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */ 233 234 /* Accept SYN data w/o any cookie option */ 235 #define TFO_SERVER_COOKIE_NOT_REQD 0x200 236 237 /* Force enable TFO on all listeners, i.e., not requiring the 238 * TCP_FASTOPEN socket option. 239 */ 240 #define TFO_SERVER_WO_SOCKOPT1 0x400 241 242 243 /* sysctl variables for tcp */ 244 extern int sysctl_tcp_max_orphans; 245 extern long sysctl_tcp_mem[3]; 246 247 #define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */ 248 #define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */ 249 #define TCP_RACK_NO_DUPTHRESH 0x4 /* Do not use DUPACK threshold in RACK */ 250 251 extern atomic_long_t tcp_memory_allocated; 252 extern struct percpu_counter tcp_sockets_allocated; 253 extern unsigned long tcp_memory_pressure; 254 255 /* optimized version of sk_under_memory_pressure() for TCP sockets */ 256 static inline bool tcp_under_memory_pressure(const struct sock *sk) 257 { 258 if (mem_cgroup_sockets_enabled && sk->sk_memcg && 259 mem_cgroup_under_socket_pressure(sk->sk_memcg)) 260 return true; 261 262 return tcp_memory_pressure; 263 } 264 /* 265 * The next routines deal with comparing 32 bit unsigned ints 266 * and worry about wraparound (automatic with unsigned arithmetic). 267 */ 268 269 static inline bool before(__u32 seq1, __u32 seq2) 270 { 271 return (__s32)(seq1-seq2) < 0; 272 } 273 #define after(seq2, seq1) before(seq1, seq2) 274 275 /* is s2<=s1<=s3 ? */ 276 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) 277 { 278 return seq3 - seq2 >= seq1 - seq2; 279 } 280 281 static inline bool tcp_out_of_memory(struct sock *sk) 282 { 283 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 284 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2)) 285 return true; 286 return false; 287 } 288 289 void sk_forced_mem_schedule(struct sock *sk, int size); 290 291 static inline bool tcp_too_many_orphans(struct sock *sk, int shift) 292 { 293 struct percpu_counter *ocp = sk->sk_prot->orphan_count; 294 int orphans = percpu_counter_read_positive(ocp); 295 296 if (orphans << shift > sysctl_tcp_max_orphans) { 297 orphans = percpu_counter_sum_positive(ocp); 298 if (orphans << shift > sysctl_tcp_max_orphans) 299 return true; 300 } 301 return false; 302 } 303 304 bool tcp_check_oom(struct sock *sk, int shift); 305 306 307 extern struct proto tcp_prot; 308 309 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 310 #define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field) 311 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 312 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 313 314 void tcp_tasklet_init(void); 315 316 int tcp_v4_err(struct sk_buff *skb, u32); 317 318 void tcp_shutdown(struct sock *sk, int how); 319 320 int tcp_v4_early_demux(struct sk_buff *skb); 321 int tcp_v4_rcv(struct sk_buff *skb); 322 323 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 324 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size); 325 int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size); 326 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, 327 int flags); 328 int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset, 329 size_t size, int flags); 330 ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset, 331 size_t size, int flags); 332 void tcp_release_cb(struct sock *sk); 333 void tcp_wfree(struct sk_buff *skb); 334 void tcp_write_timer_handler(struct sock *sk); 335 void tcp_delack_timer_handler(struct sock *sk); 336 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 337 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb); 338 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb); 339 void tcp_rcv_space_adjust(struct sock *sk); 340 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 341 void tcp_twsk_destructor(struct sock *sk); 342 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 343 struct pipe_inode_info *pipe, size_t len, 344 unsigned int flags); 345 346 void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks); 347 static inline void tcp_dec_quickack_mode(struct sock *sk, 348 const unsigned int pkts) 349 { 350 struct inet_connection_sock *icsk = inet_csk(sk); 351 352 if (icsk->icsk_ack.quick) { 353 if (pkts >= icsk->icsk_ack.quick) { 354 icsk->icsk_ack.quick = 0; 355 /* Leaving quickack mode we deflate ATO. */ 356 icsk->icsk_ack.ato = TCP_ATO_MIN; 357 } else 358 icsk->icsk_ack.quick -= pkts; 359 } 360 } 361 362 #define TCP_ECN_OK 1 363 #define TCP_ECN_QUEUE_CWR 2 364 #define TCP_ECN_DEMAND_CWR 4 365 #define TCP_ECN_SEEN 8 366 367 enum tcp_tw_status { 368 TCP_TW_SUCCESS = 0, 369 TCP_TW_RST = 1, 370 TCP_TW_ACK = 2, 371 TCP_TW_SYN = 3 372 }; 373 374 375 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 376 struct sk_buff *skb, 377 const struct tcphdr *th); 378 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 379 struct request_sock *req, bool fastopen, 380 bool *lost_race); 381 int tcp_child_process(struct sock *parent, struct sock *child, 382 struct sk_buff *skb); 383 void tcp_enter_loss(struct sock *sk); 384 void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int flag); 385 void tcp_clear_retrans(struct tcp_sock *tp); 386 void tcp_update_metrics(struct sock *sk); 387 void tcp_init_metrics(struct sock *sk); 388 void tcp_metrics_init(void); 389 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst); 390 void tcp_close(struct sock *sk, long timeout); 391 void tcp_init_sock(struct sock *sk); 392 void tcp_init_transfer(struct sock *sk, int bpf_op); 393 __poll_t tcp_poll(struct file *file, struct socket *sock, 394 struct poll_table_struct *wait); 395 int tcp_getsockopt(struct sock *sk, int level, int optname, 396 char __user *optval, int __user *optlen); 397 int tcp_setsockopt(struct sock *sk, int level, int optname, 398 char __user *optval, unsigned int optlen); 399 int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 400 char __user *optval, int __user *optlen); 401 int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 402 char __user *optval, unsigned int optlen); 403 void tcp_set_keepalive(struct sock *sk, int val); 404 void tcp_syn_ack_timeout(const struct request_sock *req); 405 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, 406 int flags, int *addr_len); 407 int tcp_set_rcvlowat(struct sock *sk, int val); 408 void tcp_data_ready(struct sock *sk); 409 #ifdef CONFIG_MMU 410 int tcp_mmap(struct file *file, struct socket *sock, 411 struct vm_area_struct *vma); 412 #endif 413 void tcp_parse_options(const struct net *net, const struct sk_buff *skb, 414 struct tcp_options_received *opt_rx, 415 int estab, struct tcp_fastopen_cookie *foc); 416 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); 417 418 /* 419 * TCP v4 functions exported for the inet6 API 420 */ 421 422 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 423 void tcp_v4_mtu_reduced(struct sock *sk); 424 void tcp_req_err(struct sock *sk, u32 seq, bool abort); 425 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 426 struct sock *tcp_create_openreq_child(const struct sock *sk, 427 struct request_sock *req, 428 struct sk_buff *skb); 429 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst); 430 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 431 struct request_sock *req, 432 struct dst_entry *dst, 433 struct request_sock *req_unhash, 434 bool *own_req); 435 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 436 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); 437 int tcp_connect(struct sock *sk); 438 enum tcp_synack_type { 439 TCP_SYNACK_NORMAL, 440 TCP_SYNACK_FASTOPEN, 441 TCP_SYNACK_COOKIE, 442 }; 443 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 444 struct request_sock *req, 445 struct tcp_fastopen_cookie *foc, 446 enum tcp_synack_type synack_type); 447 int tcp_disconnect(struct sock *sk, int flags); 448 449 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 450 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 451 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); 452 453 /* From syncookies.c */ 454 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, 455 struct request_sock *req, 456 struct dst_entry *dst, u32 tsoff); 457 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th, 458 u32 cookie); 459 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb); 460 #ifdef CONFIG_SYN_COOKIES 461 462 /* Syncookies use a monotonic timer which increments every 60 seconds. 463 * This counter is used both as a hash input and partially encoded into 464 * the cookie value. A cookie is only validated further if the delta 465 * between the current counter value and the encoded one is less than this, 466 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if 467 * the counter advances immediately after a cookie is generated). 468 */ 469 #define MAX_SYNCOOKIE_AGE 2 470 #define TCP_SYNCOOKIE_PERIOD (60 * HZ) 471 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD) 472 473 /* syncookies: remember time of last synqueue overflow 474 * But do not dirty this field too often (once per second is enough) 475 * It is racy as we do not hold a lock, but race is very minor. 476 */ 477 static inline void tcp_synq_overflow(const struct sock *sk) 478 { 479 unsigned int last_overflow; 480 unsigned int now = jiffies; 481 482 if (sk->sk_reuseport) { 483 struct sock_reuseport *reuse; 484 485 reuse = rcu_dereference(sk->sk_reuseport_cb); 486 if (likely(reuse)) { 487 last_overflow = READ_ONCE(reuse->synq_overflow_ts); 488 if (time_after32(now, last_overflow + HZ)) 489 WRITE_ONCE(reuse->synq_overflow_ts, now); 490 return; 491 } 492 } 493 494 last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 495 if (time_after32(now, last_overflow + HZ)) 496 tcp_sk(sk)->rx_opt.ts_recent_stamp = now; 497 } 498 499 /* syncookies: no recent synqueue overflow on this listening socket? */ 500 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 501 { 502 unsigned int last_overflow; 503 unsigned int now = jiffies; 504 505 if (sk->sk_reuseport) { 506 struct sock_reuseport *reuse; 507 508 reuse = rcu_dereference(sk->sk_reuseport_cb); 509 if (likely(reuse)) { 510 last_overflow = READ_ONCE(reuse->synq_overflow_ts); 511 return time_after32(now, last_overflow + 512 TCP_SYNCOOKIE_VALID); 513 } 514 } 515 516 last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 517 return time_after32(now, last_overflow + TCP_SYNCOOKIE_VALID); 518 } 519 520 static inline u32 tcp_cookie_time(void) 521 { 522 u64 val = get_jiffies_64(); 523 524 do_div(val, TCP_SYNCOOKIE_PERIOD); 525 return val; 526 } 527 528 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, 529 u16 *mssp); 530 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss); 531 u64 cookie_init_timestamp(struct request_sock *req); 532 bool cookie_timestamp_decode(const struct net *net, 533 struct tcp_options_received *opt); 534 bool cookie_ecn_ok(const struct tcp_options_received *opt, 535 const struct net *net, const struct dst_entry *dst); 536 537 /* From net/ipv6/syncookies.c */ 538 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th, 539 u32 cookie); 540 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 541 542 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph, 543 const struct tcphdr *th, u16 *mssp); 544 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss); 545 #endif 546 /* tcp_output.c */ 547 548 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 549 int nonagle); 550 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 551 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 552 void tcp_retransmit_timer(struct sock *sk); 553 void tcp_xmit_retransmit_queue(struct sock *); 554 void tcp_simple_retransmit(struct sock *); 555 void tcp_enter_recovery(struct sock *sk, bool ece_ack); 556 int tcp_trim_head(struct sock *, struct sk_buff *, u32); 557 enum tcp_queue { 558 TCP_FRAG_IN_WRITE_QUEUE, 559 TCP_FRAG_IN_RTX_QUEUE, 560 }; 561 int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, 562 struct sk_buff *skb, u32 len, 563 unsigned int mss_now, gfp_t gfp); 564 565 void tcp_send_probe0(struct sock *); 566 void tcp_send_partial(struct sock *); 567 int tcp_write_wakeup(struct sock *, int mib); 568 void tcp_send_fin(struct sock *sk); 569 void tcp_send_active_reset(struct sock *sk, gfp_t priority); 570 int tcp_send_synack(struct sock *); 571 void tcp_push_one(struct sock *, unsigned int mss_now); 572 void __tcp_send_ack(struct sock *sk, u32 rcv_nxt); 573 void tcp_send_ack(struct sock *sk); 574 void tcp_send_delayed_ack(struct sock *sk); 575 void tcp_send_loss_probe(struct sock *sk); 576 bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto); 577 void tcp_skb_collapse_tstamp(struct sk_buff *skb, 578 const struct sk_buff *next_skb); 579 580 /* tcp_input.c */ 581 void tcp_rearm_rto(struct sock *sk); 582 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req); 583 void tcp_reset(struct sock *sk); 584 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb); 585 void tcp_fin(struct sock *sk); 586 587 /* tcp_timer.c */ 588 void tcp_init_xmit_timers(struct sock *); 589 static inline void tcp_clear_xmit_timers(struct sock *sk) 590 { 591 if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1) 592 __sock_put(sk); 593 594 if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1) 595 __sock_put(sk); 596 597 inet_csk_clear_xmit_timers(sk); 598 } 599 600 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 601 unsigned int tcp_current_mss(struct sock *sk); 602 603 /* Bound MSS / TSO packet size with the half of the window */ 604 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 605 { 606 int cutoff; 607 608 /* When peer uses tiny windows, there is no use in packetizing 609 * to sub-MSS pieces for the sake of SWS or making sure there 610 * are enough packets in the pipe for fast recovery. 611 * 612 * On the other hand, for extremely large MSS devices, handling 613 * smaller than MSS windows in this way does make sense. 614 */ 615 if (tp->max_window > TCP_MSS_DEFAULT) 616 cutoff = (tp->max_window >> 1); 617 else 618 cutoff = tp->max_window; 619 620 if (cutoff && pktsize > cutoff) 621 return max_t(int, cutoff, 68U - tp->tcp_header_len); 622 else 623 return pktsize; 624 } 625 626 /* tcp.c */ 627 void tcp_get_info(struct sock *, struct tcp_info *); 628 629 /* Read 'sendfile()'-style from a TCP socket */ 630 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 631 sk_read_actor_t recv_actor); 632 633 void tcp_initialize_rcv_mss(struct sock *sk); 634 635 int tcp_mtu_to_mss(struct sock *sk, int pmtu); 636 int tcp_mss_to_mtu(struct sock *sk, int mss); 637 void tcp_mtup_init(struct sock *sk); 638 void tcp_init_buffer_space(struct sock *sk); 639 640 static inline void tcp_bound_rto(const struct sock *sk) 641 { 642 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 643 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 644 } 645 646 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 647 { 648 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us); 649 } 650 651 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 652 { 653 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 654 ntohl(TCP_FLAG_ACK) | 655 snd_wnd); 656 } 657 658 static inline void tcp_fast_path_on(struct tcp_sock *tp) 659 { 660 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 661 } 662 663 static inline void tcp_fast_path_check(struct sock *sk) 664 { 665 struct tcp_sock *tp = tcp_sk(sk); 666 667 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) && 668 tp->rcv_wnd && 669 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 670 !tp->urg_data) 671 tcp_fast_path_on(tp); 672 } 673 674 /* Compute the actual rto_min value */ 675 static inline u32 tcp_rto_min(struct sock *sk) 676 { 677 const struct dst_entry *dst = __sk_dst_get(sk); 678 u32 rto_min = TCP_RTO_MIN; 679 680 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 681 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 682 return rto_min; 683 } 684 685 static inline u32 tcp_rto_min_us(struct sock *sk) 686 { 687 return jiffies_to_usecs(tcp_rto_min(sk)); 688 } 689 690 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst) 691 { 692 return dst_metric_locked(dst, RTAX_CC_ALGO); 693 } 694 695 /* Minimum RTT in usec. ~0 means not available. */ 696 static inline u32 tcp_min_rtt(const struct tcp_sock *tp) 697 { 698 return minmax_get(&tp->rtt_min); 699 } 700 701 /* Compute the actual receive window we are currently advertising. 702 * Rcv_nxt can be after the window if our peer push more data 703 * than the offered window. 704 */ 705 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 706 { 707 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 708 709 if (win < 0) 710 win = 0; 711 return (u32) win; 712 } 713 714 /* Choose a new window, without checks for shrinking, and without 715 * scaling applied to the result. The caller does these things 716 * if necessary. This is a "raw" window selection. 717 */ 718 u32 __tcp_select_window(struct sock *sk); 719 720 void tcp_send_window_probe(struct sock *sk); 721 722 /* TCP uses 32bit jiffies to save some space. 723 * Note that this is different from tcp_time_stamp, which 724 * historically has been the same until linux-4.13. 725 */ 726 #define tcp_jiffies32 ((u32)jiffies) 727 728 /* 729 * Deliver a 32bit value for TCP timestamp option (RFC 7323) 730 * It is no longer tied to jiffies, but to 1 ms clock. 731 * Note: double check if you want to use tcp_jiffies32 instead of this. 732 */ 733 #define TCP_TS_HZ 1000 734 735 static inline u64 tcp_clock_ns(void) 736 { 737 return ktime_get_ns(); 738 } 739 740 static inline u64 tcp_clock_us(void) 741 { 742 return div_u64(tcp_clock_ns(), NSEC_PER_USEC); 743 } 744 745 /* This should only be used in contexts where tp->tcp_mstamp is up to date */ 746 static inline u32 tcp_time_stamp(const struct tcp_sock *tp) 747 { 748 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ); 749 } 750 751 /* Could use tcp_clock_us() / 1000, but this version uses a single divide */ 752 static inline u32 tcp_time_stamp_raw(void) 753 { 754 return div_u64(tcp_clock_ns(), NSEC_PER_SEC / TCP_TS_HZ); 755 } 756 757 void tcp_mstamp_refresh(struct tcp_sock *tp); 758 759 static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0) 760 { 761 return max_t(s64, t1 - t0, 0); 762 } 763 764 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) 765 { 766 return div_u64(skb->skb_mstamp_ns, NSEC_PER_SEC / TCP_TS_HZ); 767 } 768 769 /* provide the departure time in us unit */ 770 static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb) 771 { 772 return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC); 773 } 774 775 776 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 777 778 #define TCPHDR_FIN 0x01 779 #define TCPHDR_SYN 0x02 780 #define TCPHDR_RST 0x04 781 #define TCPHDR_PSH 0x08 782 #define TCPHDR_ACK 0x10 783 #define TCPHDR_URG 0x20 784 #define TCPHDR_ECE 0x40 785 #define TCPHDR_CWR 0x80 786 787 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) 788 789 /* This is what the send packet queuing engine uses to pass 790 * TCP per-packet control information to the transmission code. 791 * We also store the host-order sequence numbers in here too. 792 * This is 44 bytes if IPV6 is enabled. 793 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 794 */ 795 struct tcp_skb_cb { 796 __u32 seq; /* Starting sequence number */ 797 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 798 union { 799 /* Note : tcp_tw_isn is used in input path only 800 * (isn chosen by tcp_timewait_state_process()) 801 * 802 * tcp_gso_segs/size are used in write queue only, 803 * cf tcp_skb_pcount()/tcp_skb_mss() 804 */ 805 __u32 tcp_tw_isn; 806 struct { 807 u16 tcp_gso_segs; 808 u16 tcp_gso_size; 809 }; 810 }; 811 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 812 813 __u8 sacked; /* State flags for SACK. */ 814 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 815 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 816 #define TCPCB_LOST 0x04 /* SKB is lost */ 817 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 818 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp_ns) */ 819 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 820 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \ 821 TCPCB_REPAIRED) 822 823 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 824 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */ 825 eor:1, /* Is skb MSG_EOR marked? */ 826 has_rxtstamp:1, /* SKB has a RX timestamp */ 827 unused:5; 828 __u32 ack_seq; /* Sequence number ACK'd */ 829 union { 830 struct { 831 /* There is space for up to 24 bytes */ 832 __u32 in_flight:30,/* Bytes in flight at transmit */ 833 is_app_limited:1, /* cwnd not fully used? */ 834 unused:1; 835 /* pkts S/ACKed so far upon tx of skb, incl retrans: */ 836 __u32 delivered; 837 /* start of send pipeline phase */ 838 u64 first_tx_mstamp; 839 /* when we reached the "delivered" count */ 840 u64 delivered_mstamp; 841 } tx; /* only used for outgoing skbs */ 842 union { 843 struct inet_skb_parm h4; 844 #if IS_ENABLED(CONFIG_IPV6) 845 struct inet6_skb_parm h6; 846 #endif 847 } header; /* For incoming skbs */ 848 struct { 849 __u32 flags; 850 struct sock *sk_redir; 851 void *data_end; 852 } bpf; 853 }; 854 }; 855 856 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 857 858 static inline void bpf_compute_data_end_sk_skb(struct sk_buff *skb) 859 { 860 TCP_SKB_CB(skb)->bpf.data_end = skb->data + skb_headlen(skb); 861 } 862 863 static inline bool tcp_skb_bpf_ingress(const struct sk_buff *skb) 864 { 865 return TCP_SKB_CB(skb)->bpf.flags & BPF_F_INGRESS; 866 } 867 868 static inline struct sock *tcp_skb_bpf_redirect_fetch(struct sk_buff *skb) 869 { 870 return TCP_SKB_CB(skb)->bpf.sk_redir; 871 } 872 873 static inline void tcp_skb_bpf_redirect_clear(struct sk_buff *skb) 874 { 875 TCP_SKB_CB(skb)->bpf.sk_redir = NULL; 876 } 877 878 #if IS_ENABLED(CONFIG_IPV6) 879 /* This is the variant of inet6_iif() that must be used by TCP, 880 * as TCP moves IP6CB into a different location in skb->cb[] 881 */ 882 static inline int tcp_v6_iif(const struct sk_buff *skb) 883 { 884 return TCP_SKB_CB(skb)->header.h6.iif; 885 } 886 887 static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb) 888 { 889 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags); 890 891 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif; 892 } 893 894 /* TCP_SKB_CB reference means this can not be used from early demux */ 895 static inline int tcp_v6_sdif(const struct sk_buff *skb) 896 { 897 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 898 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags)) 899 return TCP_SKB_CB(skb)->header.h6.iif; 900 #endif 901 return 0; 902 } 903 #endif 904 905 static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb) 906 { 907 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 908 if (!net->ipv4.sysctl_tcp_l3mdev_accept && 909 skb && ipv4_l3mdev_skb(IPCB(skb)->flags)) 910 return true; 911 #endif 912 return false; 913 } 914 915 /* TCP_SKB_CB reference means this can not be used from early demux */ 916 static inline int tcp_v4_sdif(struct sk_buff *skb) 917 { 918 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 919 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags)) 920 return TCP_SKB_CB(skb)->header.h4.iif; 921 #endif 922 return 0; 923 } 924 925 /* Due to TSO, an SKB can be composed of multiple actual 926 * packets. To keep these tracked properly, we use this. 927 */ 928 static inline int tcp_skb_pcount(const struct sk_buff *skb) 929 { 930 return TCP_SKB_CB(skb)->tcp_gso_segs; 931 } 932 933 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 934 { 935 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 936 } 937 938 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 939 { 940 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 941 } 942 943 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ 944 static inline int tcp_skb_mss(const struct sk_buff *skb) 945 { 946 return TCP_SKB_CB(skb)->tcp_gso_size; 947 } 948 949 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb) 950 { 951 return likely(!TCP_SKB_CB(skb)->eor); 952 } 953 954 /* Events passed to congestion control interface */ 955 enum tcp_ca_event { 956 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 957 CA_EVENT_CWND_RESTART, /* congestion window restart */ 958 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 959 CA_EVENT_LOSS, /* loss timeout */ 960 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 961 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 962 }; 963 964 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 965 enum tcp_ca_ack_event_flags { 966 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 967 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 968 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 969 }; 970 971 /* 972 * Interface for adding new TCP congestion control handlers 973 */ 974 #define TCP_CA_NAME_MAX 16 975 #define TCP_CA_MAX 128 976 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 977 978 #define TCP_CA_UNSPEC 0 979 980 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 981 #define TCP_CONG_NON_RESTRICTED 0x1 982 /* Requires ECN/ECT set on all packets */ 983 #define TCP_CONG_NEEDS_ECN 0x2 984 985 union tcp_cc_info; 986 987 struct ack_sample { 988 u32 pkts_acked; 989 s32 rtt_us; 990 u32 in_flight; 991 }; 992 993 /* A rate sample measures the number of (original/retransmitted) data 994 * packets delivered "delivered" over an interval of time "interval_us". 995 * The tcp_rate.c code fills in the rate sample, and congestion 996 * control modules that define a cong_control function to run at the end 997 * of ACK processing can optionally chose to consult this sample when 998 * setting cwnd and pacing rate. 999 * A sample is invalid if "delivered" or "interval_us" is negative. 1000 */ 1001 struct rate_sample { 1002 u64 prior_mstamp; /* starting timestamp for interval */ 1003 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */ 1004 s32 delivered; /* number of packets delivered over interval */ 1005 long interval_us; /* time for tp->delivered to incr "delivered" */ 1006 u32 snd_interval_us; /* snd interval for delivered packets */ 1007 u32 rcv_interval_us; /* rcv interval for delivered packets */ 1008 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */ 1009 int losses; /* number of packets marked lost upon ACK */ 1010 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */ 1011 u32 prior_in_flight; /* in flight before this ACK */ 1012 bool is_app_limited; /* is sample from packet with bubble in pipe? */ 1013 bool is_retrans; /* is sample from retransmission? */ 1014 bool is_ack_delayed; /* is this (likely) a delayed ACK? */ 1015 }; 1016 1017 struct tcp_congestion_ops { 1018 struct list_head list; 1019 u32 key; 1020 u32 flags; 1021 1022 /* initialize private data (optional) */ 1023 void (*init)(struct sock *sk); 1024 /* cleanup private data (optional) */ 1025 void (*release)(struct sock *sk); 1026 1027 /* return slow start threshold (required) */ 1028 u32 (*ssthresh)(struct sock *sk); 1029 /* do new cwnd calculation (required) */ 1030 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 1031 /* call before changing ca_state (optional) */ 1032 void (*set_state)(struct sock *sk, u8 new_state); 1033 /* call when cwnd event occurs (optional) */ 1034 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 1035 /* call when ack arrives (optional) */ 1036 void (*in_ack_event)(struct sock *sk, u32 flags); 1037 /* new value of cwnd after loss (required) */ 1038 u32 (*undo_cwnd)(struct sock *sk); 1039 /* hook for packet ack accounting (optional) */ 1040 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample); 1041 /* override sysctl_tcp_min_tso_segs */ 1042 u32 (*min_tso_segs)(struct sock *sk); 1043 /* returns the multiplier used in tcp_sndbuf_expand (optional) */ 1044 u32 (*sndbuf_expand)(struct sock *sk); 1045 /* call when packets are delivered to update cwnd and pacing rate, 1046 * after all the ca_state processing. (optional) 1047 */ 1048 void (*cong_control)(struct sock *sk, const struct rate_sample *rs); 1049 /* get info for inet_diag (optional) */ 1050 size_t (*get_info)(struct sock *sk, u32 ext, int *attr, 1051 union tcp_cc_info *info); 1052 1053 char name[TCP_CA_NAME_MAX]; 1054 struct module *owner; 1055 }; 1056 1057 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 1058 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 1059 1060 void tcp_assign_congestion_control(struct sock *sk); 1061 void tcp_init_congestion_control(struct sock *sk); 1062 void tcp_cleanup_congestion_control(struct sock *sk); 1063 int tcp_set_default_congestion_control(struct net *net, const char *name); 1064 void tcp_get_default_congestion_control(struct net *net, char *name); 1065 void tcp_get_available_congestion_control(char *buf, size_t len); 1066 void tcp_get_allowed_congestion_control(char *buf, size_t len); 1067 int tcp_set_allowed_congestion_control(char *allowed); 1068 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, bool reinit); 1069 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); 1070 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); 1071 1072 u32 tcp_reno_ssthresh(struct sock *sk); 1073 u32 tcp_reno_undo_cwnd(struct sock *sk); 1074 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 1075 extern struct tcp_congestion_ops tcp_reno; 1076 1077 struct tcp_congestion_ops *tcp_ca_find_key(u32 key); 1078 u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca); 1079 #ifdef CONFIG_INET 1080 char *tcp_ca_get_name_by_key(u32 key, char *buffer); 1081 #else 1082 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) 1083 { 1084 return NULL; 1085 } 1086 #endif 1087 1088 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 1089 { 1090 const struct inet_connection_sock *icsk = inet_csk(sk); 1091 1092 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 1093 } 1094 1095 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 1096 { 1097 struct inet_connection_sock *icsk = inet_csk(sk); 1098 1099 if (icsk->icsk_ca_ops->set_state) 1100 icsk->icsk_ca_ops->set_state(sk, ca_state); 1101 icsk->icsk_ca_state = ca_state; 1102 } 1103 1104 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 1105 { 1106 const struct inet_connection_sock *icsk = inet_csk(sk); 1107 1108 if (icsk->icsk_ca_ops->cwnd_event) 1109 icsk->icsk_ca_ops->cwnd_event(sk, event); 1110 } 1111 1112 /* From tcp_rate.c */ 1113 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb); 1114 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb, 1115 struct rate_sample *rs); 1116 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost, 1117 bool is_sack_reneg, struct rate_sample *rs); 1118 void tcp_rate_check_app_limited(struct sock *sk); 1119 1120 /* These functions determine how the current flow behaves in respect of SACK 1121 * handling. SACK is negotiated with the peer, and therefore it can vary 1122 * between different flows. 1123 * 1124 * tcp_is_sack - SACK enabled 1125 * tcp_is_reno - No SACK 1126 */ 1127 static inline int tcp_is_sack(const struct tcp_sock *tp) 1128 { 1129 return likely(tp->rx_opt.sack_ok); 1130 } 1131 1132 static inline bool tcp_is_reno(const struct tcp_sock *tp) 1133 { 1134 return !tcp_is_sack(tp); 1135 } 1136 1137 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 1138 { 1139 return tp->sacked_out + tp->lost_out; 1140 } 1141 1142 /* This determines how many packets are "in the network" to the best 1143 * of our knowledge. In many cases it is conservative, but where 1144 * detailed information is available from the receiver (via SACK 1145 * blocks etc.) we can make more aggressive calculations. 1146 * 1147 * Use this for decisions involving congestion control, use just 1148 * tp->packets_out to determine if the send queue is empty or not. 1149 * 1150 * Read this equation as: 1151 * 1152 * "Packets sent once on transmission queue" MINUS 1153 * "Packets left network, but not honestly ACKed yet" PLUS 1154 * "Packets fast retransmitted" 1155 */ 1156 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 1157 { 1158 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 1159 } 1160 1161 #define TCP_INFINITE_SSTHRESH 0x7fffffff 1162 1163 static inline bool tcp_in_slow_start(const struct tcp_sock *tp) 1164 { 1165 return tp->snd_cwnd < tp->snd_ssthresh; 1166 } 1167 1168 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 1169 { 1170 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 1171 } 1172 1173 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 1174 { 1175 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 1176 (1 << inet_csk(sk)->icsk_ca_state); 1177 } 1178 1179 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 1180 * The exception is cwnd reduction phase, when cwnd is decreasing towards 1181 * ssthresh. 1182 */ 1183 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 1184 { 1185 const struct tcp_sock *tp = tcp_sk(sk); 1186 1187 if (tcp_in_cwnd_reduction(sk)) 1188 return tp->snd_ssthresh; 1189 else 1190 return max(tp->snd_ssthresh, 1191 ((tp->snd_cwnd >> 1) + 1192 (tp->snd_cwnd >> 2))); 1193 } 1194 1195 /* Use define here intentionally to get WARN_ON location shown at the caller */ 1196 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 1197 1198 void tcp_enter_cwr(struct sock *sk); 1199 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 1200 1201 /* The maximum number of MSS of available cwnd for which TSO defers 1202 * sending if not using sysctl_tcp_tso_win_divisor. 1203 */ 1204 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 1205 { 1206 return 3; 1207 } 1208 1209 /* Returns end sequence number of the receiver's advertised window */ 1210 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 1211 { 1212 return tp->snd_una + tp->snd_wnd; 1213 } 1214 1215 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 1216 * flexible approach. The RFC suggests cwnd should not be raised unless 1217 * it was fully used previously. And that's exactly what we do in 1218 * congestion avoidance mode. But in slow start we allow cwnd to grow 1219 * as long as the application has used half the cwnd. 1220 * Example : 1221 * cwnd is 10 (IW10), but application sends 9 frames. 1222 * We allow cwnd to reach 18 when all frames are ACKed. 1223 * This check is safe because it's as aggressive as slow start which already 1224 * risks 100% overshoot. The advantage is that we discourage application to 1225 * either send more filler packets or data to artificially blow up the cwnd 1226 * usage, and allow application-limited process to probe bw more aggressively. 1227 */ 1228 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1229 { 1230 const struct tcp_sock *tp = tcp_sk(sk); 1231 1232 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1233 if (tcp_in_slow_start(tp)) 1234 return tp->snd_cwnd < 2 * tp->max_packets_out; 1235 1236 return tp->is_cwnd_limited; 1237 } 1238 1239 /* BBR congestion control needs pacing. 1240 * Same remark for SO_MAX_PACING_RATE. 1241 * sch_fq packet scheduler is efficiently handling pacing, 1242 * but is not always installed/used. 1243 * Return true if TCP stack should pace packets itself. 1244 */ 1245 static inline bool tcp_needs_internal_pacing(const struct sock *sk) 1246 { 1247 return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED; 1248 } 1249 1250 /* Return in jiffies the delay before one skb is sent. 1251 * If @skb is NULL, we look at EDT for next packet being sent on the socket. 1252 */ 1253 static inline unsigned long tcp_pacing_delay(const struct sock *sk, 1254 const struct sk_buff *skb) 1255 { 1256 s64 pacing_delay = skb ? skb->tstamp : tcp_sk(sk)->tcp_wstamp_ns; 1257 1258 pacing_delay -= tcp_sk(sk)->tcp_clock_cache; 1259 1260 return pacing_delay > 0 ? nsecs_to_jiffies(pacing_delay) : 0; 1261 } 1262 1263 static inline void tcp_reset_xmit_timer(struct sock *sk, 1264 const int what, 1265 unsigned long when, 1266 const unsigned long max_when, 1267 const struct sk_buff *skb) 1268 { 1269 inet_csk_reset_xmit_timer(sk, what, when + tcp_pacing_delay(sk, skb), 1270 max_when); 1271 } 1272 1273 /* Something is really bad, we could not queue an additional packet, 1274 * because qdisc is full or receiver sent a 0 window, or we are paced. 1275 * We do not want to add fuel to the fire, or abort too early, 1276 * so make sure the timer we arm now is at least 200ms in the future, 1277 * regardless of current icsk_rto value (as it could be ~2ms) 1278 */ 1279 static inline unsigned long tcp_probe0_base(const struct sock *sk) 1280 { 1281 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); 1282 } 1283 1284 /* Variant of inet_csk_rto_backoff() used for zero window probes */ 1285 static inline unsigned long tcp_probe0_when(const struct sock *sk, 1286 unsigned long max_when) 1287 { 1288 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff; 1289 1290 return (unsigned long)min_t(u64, when, max_when); 1291 } 1292 1293 static inline void tcp_check_probe_timer(struct sock *sk) 1294 { 1295 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) 1296 tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1297 tcp_probe0_base(sk), TCP_RTO_MAX, 1298 NULL); 1299 } 1300 1301 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1302 { 1303 tp->snd_wl1 = seq; 1304 } 1305 1306 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1307 { 1308 tp->snd_wl1 = seq; 1309 } 1310 1311 /* 1312 * Calculate(/check) TCP checksum 1313 */ 1314 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1315 __be32 daddr, __wsum base) 1316 { 1317 return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_TCP, base); 1318 } 1319 1320 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1321 { 1322 return !skb_csum_unnecessary(skb) && 1323 __skb_checksum_complete(skb); 1324 } 1325 1326 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb); 1327 int tcp_filter(struct sock *sk, struct sk_buff *skb); 1328 void tcp_set_state(struct sock *sk, int state); 1329 void tcp_done(struct sock *sk); 1330 int tcp_abort(struct sock *sk, int err); 1331 1332 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1333 { 1334 rx_opt->dsack = 0; 1335 rx_opt->num_sacks = 0; 1336 } 1337 1338 u32 tcp_default_init_rwnd(u32 mss); 1339 void tcp_cwnd_restart(struct sock *sk, s32 delta); 1340 1341 static inline void tcp_slow_start_after_idle_check(struct sock *sk) 1342 { 1343 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1344 struct tcp_sock *tp = tcp_sk(sk); 1345 s32 delta; 1346 1347 if (!sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle || tp->packets_out || 1348 ca_ops->cong_control) 1349 return; 1350 delta = tcp_jiffies32 - tp->lsndtime; 1351 if (delta > inet_csk(sk)->icsk_rto) 1352 tcp_cwnd_restart(sk, delta); 1353 } 1354 1355 /* Determine a window scaling and initial window to offer. */ 1356 void tcp_select_initial_window(const struct sock *sk, int __space, 1357 __u32 mss, __u32 *rcv_wnd, 1358 __u32 *window_clamp, int wscale_ok, 1359 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1360 1361 static inline int tcp_win_from_space(const struct sock *sk, int space) 1362 { 1363 int tcp_adv_win_scale = sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale; 1364 1365 return tcp_adv_win_scale <= 0 ? 1366 (space>>(-tcp_adv_win_scale)) : 1367 space - (space>>tcp_adv_win_scale); 1368 } 1369 1370 /* Note: caller must be prepared to deal with negative returns */ 1371 static inline int tcp_space(const struct sock *sk) 1372 { 1373 return tcp_win_from_space(sk, sk->sk_rcvbuf - sk->sk_backlog.len - 1374 atomic_read(&sk->sk_rmem_alloc)); 1375 } 1376 1377 static inline int tcp_full_space(const struct sock *sk) 1378 { 1379 return tcp_win_from_space(sk, sk->sk_rcvbuf); 1380 } 1381 1382 extern void tcp_openreq_init_rwin(struct request_sock *req, 1383 const struct sock *sk_listener, 1384 const struct dst_entry *dst); 1385 1386 void tcp_enter_memory_pressure(struct sock *sk); 1387 void tcp_leave_memory_pressure(struct sock *sk); 1388 1389 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1390 { 1391 struct net *net = sock_net((struct sock *)tp); 1392 1393 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl; 1394 } 1395 1396 static inline int keepalive_time_when(const struct tcp_sock *tp) 1397 { 1398 struct net *net = sock_net((struct sock *)tp); 1399 1400 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time; 1401 } 1402 1403 static inline int keepalive_probes(const struct tcp_sock *tp) 1404 { 1405 struct net *net = sock_net((struct sock *)tp); 1406 1407 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes; 1408 } 1409 1410 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1411 { 1412 const struct inet_connection_sock *icsk = &tp->inet_conn; 1413 1414 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime, 1415 tcp_jiffies32 - tp->rcv_tstamp); 1416 } 1417 1418 static inline int tcp_fin_time(const struct sock *sk) 1419 { 1420 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout; 1421 const int rto = inet_csk(sk)->icsk_rto; 1422 1423 if (fin_timeout < (rto << 2) - (rto >> 1)) 1424 fin_timeout = (rto << 2) - (rto >> 1); 1425 1426 return fin_timeout; 1427 } 1428 1429 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1430 int paws_win) 1431 { 1432 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1433 return true; 1434 if (unlikely(!time_before32(ktime_get_seconds(), 1435 rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))) 1436 return true; 1437 /* 1438 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1439 * then following tcp messages have valid values. Ignore 0 value, 1440 * or else 'negative' tsval might forbid us to accept their packets. 1441 */ 1442 if (!rx_opt->ts_recent) 1443 return true; 1444 return false; 1445 } 1446 1447 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1448 int rst) 1449 { 1450 if (tcp_paws_check(rx_opt, 0)) 1451 return false; 1452 1453 /* RST segments are not recommended to carry timestamp, 1454 and, if they do, it is recommended to ignore PAWS because 1455 "their cleanup function should take precedence over timestamps." 1456 Certainly, it is mistake. It is necessary to understand the reasons 1457 of this constraint to relax it: if peer reboots, clock may go 1458 out-of-sync and half-open connections will not be reset. 1459 Actually, the problem would be not existing if all 1460 the implementations followed draft about maintaining clock 1461 via reboots. Linux-2.2 DOES NOT! 1462 1463 However, we can relax time bounds for RST segments to MSL. 1464 */ 1465 if (rst && !time_before32(ktime_get_seconds(), 1466 rx_opt->ts_recent_stamp + TCP_PAWS_MSL)) 1467 return false; 1468 return true; 1469 } 1470 1471 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, 1472 int mib_idx, u32 *last_oow_ack_time); 1473 1474 static inline void tcp_mib_init(struct net *net) 1475 { 1476 /* See RFC 2012 */ 1477 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1); 1478 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1479 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1480 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1); 1481 } 1482 1483 /* from STCP */ 1484 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1485 { 1486 tp->lost_skb_hint = NULL; 1487 } 1488 1489 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1490 { 1491 tcp_clear_retrans_hints_partial(tp); 1492 tp->retransmit_skb_hint = NULL; 1493 } 1494 1495 union tcp_md5_addr { 1496 struct in_addr a4; 1497 #if IS_ENABLED(CONFIG_IPV6) 1498 struct in6_addr a6; 1499 #endif 1500 }; 1501 1502 /* - key database */ 1503 struct tcp_md5sig_key { 1504 struct hlist_node node; 1505 u8 keylen; 1506 u8 family; /* AF_INET or AF_INET6 */ 1507 union tcp_md5_addr addr; 1508 u8 prefixlen; 1509 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1510 struct rcu_head rcu; 1511 }; 1512 1513 /* - sock block */ 1514 struct tcp_md5sig_info { 1515 struct hlist_head head; 1516 struct rcu_head rcu; 1517 }; 1518 1519 /* - pseudo header */ 1520 struct tcp4_pseudohdr { 1521 __be32 saddr; 1522 __be32 daddr; 1523 __u8 pad; 1524 __u8 protocol; 1525 __be16 len; 1526 }; 1527 1528 struct tcp6_pseudohdr { 1529 struct in6_addr saddr; 1530 struct in6_addr daddr; 1531 __be32 len; 1532 __be32 protocol; /* including padding */ 1533 }; 1534 1535 union tcp_md5sum_block { 1536 struct tcp4_pseudohdr ip4; 1537 #if IS_ENABLED(CONFIG_IPV6) 1538 struct tcp6_pseudohdr ip6; 1539 #endif 1540 }; 1541 1542 /* - pool: digest algorithm, hash description and scratch buffer */ 1543 struct tcp_md5sig_pool { 1544 struct ahash_request *md5_req; 1545 void *scratch; 1546 }; 1547 1548 /* - functions */ 1549 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1550 const struct sock *sk, const struct sk_buff *skb); 1551 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1552 int family, u8 prefixlen, const u8 *newkey, u8 newkeylen, 1553 gfp_t gfp); 1554 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1555 int family, u8 prefixlen); 1556 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 1557 const struct sock *addr_sk); 1558 1559 #ifdef CONFIG_TCP_MD5SIG 1560 #include <linux/jump_label.h> 1561 extern struct static_key_false tcp_md5_needed; 1562 struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, 1563 const union tcp_md5_addr *addr, 1564 int family); 1565 static inline struct tcp_md5sig_key * 1566 tcp_md5_do_lookup(const struct sock *sk, 1567 const union tcp_md5_addr *addr, 1568 int family) 1569 { 1570 if (!static_branch_unlikely(&tcp_md5_needed)) 1571 return NULL; 1572 return __tcp_md5_do_lookup(sk, addr, family); 1573 } 1574 1575 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1576 #else 1577 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1578 const union tcp_md5_addr *addr, 1579 int family) 1580 { 1581 return NULL; 1582 } 1583 #define tcp_twsk_md5_key(twsk) NULL 1584 #endif 1585 1586 bool tcp_alloc_md5sig_pool(void); 1587 1588 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1589 static inline void tcp_put_md5sig_pool(void) 1590 { 1591 local_bh_enable(); 1592 } 1593 1594 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1595 unsigned int header_len); 1596 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1597 const struct tcp_md5sig_key *key); 1598 1599 /* From tcp_fastopen.c */ 1600 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1601 struct tcp_fastopen_cookie *cookie); 1602 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1603 struct tcp_fastopen_cookie *cookie, bool syn_lost, 1604 u16 try_exp); 1605 struct tcp_fastopen_request { 1606 /* Fast Open cookie. Size 0 means a cookie request */ 1607 struct tcp_fastopen_cookie cookie; 1608 struct msghdr *data; /* data in MSG_FASTOPEN */ 1609 size_t size; 1610 int copied; /* queued in tcp_connect() */ 1611 struct ubuf_info *uarg; 1612 }; 1613 void tcp_free_fastopen_req(struct tcp_sock *tp); 1614 void tcp_fastopen_destroy_cipher(struct sock *sk); 1615 void tcp_fastopen_ctx_destroy(struct net *net); 1616 int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk, 1617 void *key, unsigned int len); 1618 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb); 1619 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1620 struct request_sock *req, 1621 struct tcp_fastopen_cookie *foc, 1622 const struct dst_entry *dst); 1623 void tcp_fastopen_init_key_once(struct net *net); 1624 bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss, 1625 struct tcp_fastopen_cookie *cookie); 1626 bool tcp_fastopen_defer_connect(struct sock *sk, int *err); 1627 #define TCP_FASTOPEN_KEY_LENGTH 16 1628 1629 /* Fastopen key context */ 1630 struct tcp_fastopen_context { 1631 struct crypto_cipher *tfm; 1632 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1633 struct rcu_head rcu; 1634 }; 1635 1636 extern unsigned int sysctl_tcp_fastopen_blackhole_timeout; 1637 void tcp_fastopen_active_disable(struct sock *sk); 1638 bool tcp_fastopen_active_should_disable(struct sock *sk); 1639 void tcp_fastopen_active_disable_ofo_check(struct sock *sk); 1640 void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired); 1641 1642 /* Latencies incurred by various limits for a sender. They are 1643 * chronograph-like stats that are mutually exclusive. 1644 */ 1645 enum tcp_chrono { 1646 TCP_CHRONO_UNSPEC, 1647 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */ 1648 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */ 1649 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */ 1650 __TCP_CHRONO_MAX, 1651 }; 1652 1653 void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type); 1654 void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type); 1655 1656 /* This helper is needed, because skb->tcp_tsorted_anchor uses 1657 * the same memory storage than skb->destructor/_skb_refdst 1658 */ 1659 static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb) 1660 { 1661 skb->destructor = NULL; 1662 skb->_skb_refdst = 0UL; 1663 } 1664 1665 #define tcp_skb_tsorted_save(skb) { \ 1666 unsigned long _save = skb->_skb_refdst; \ 1667 skb->_skb_refdst = 0UL; 1668 1669 #define tcp_skb_tsorted_restore(skb) \ 1670 skb->_skb_refdst = _save; \ 1671 } 1672 1673 void tcp_write_queue_purge(struct sock *sk); 1674 1675 static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk) 1676 { 1677 return skb_rb_first(&sk->tcp_rtx_queue); 1678 } 1679 1680 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1681 { 1682 return skb_peek(&sk->sk_write_queue); 1683 } 1684 1685 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1686 { 1687 return skb_peek_tail(&sk->sk_write_queue); 1688 } 1689 1690 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1691 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1692 1693 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1694 { 1695 return skb_peek(&sk->sk_write_queue); 1696 } 1697 1698 static inline bool tcp_skb_is_last(const struct sock *sk, 1699 const struct sk_buff *skb) 1700 { 1701 return skb_queue_is_last(&sk->sk_write_queue, skb); 1702 } 1703 1704 static inline bool tcp_write_queue_empty(const struct sock *sk) 1705 { 1706 return skb_queue_empty(&sk->sk_write_queue); 1707 } 1708 1709 static inline bool tcp_rtx_queue_empty(const struct sock *sk) 1710 { 1711 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue); 1712 } 1713 1714 static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk) 1715 { 1716 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk); 1717 } 1718 1719 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1720 { 1721 __skb_queue_tail(&sk->sk_write_queue, skb); 1722 1723 /* Queue it, remembering where we must start sending. */ 1724 if (sk->sk_write_queue.next == skb) 1725 tcp_chrono_start(sk, TCP_CHRONO_BUSY); 1726 } 1727 1728 /* Insert new before skb on the write queue of sk. */ 1729 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1730 struct sk_buff *skb, 1731 struct sock *sk) 1732 { 1733 __skb_queue_before(&sk->sk_write_queue, skb, new); 1734 } 1735 1736 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1737 { 1738 tcp_skb_tsorted_anchor_cleanup(skb); 1739 __skb_unlink(skb, &sk->sk_write_queue); 1740 } 1741 1742 void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb); 1743 1744 static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk) 1745 { 1746 tcp_skb_tsorted_anchor_cleanup(skb); 1747 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue); 1748 } 1749 1750 static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk) 1751 { 1752 list_del(&skb->tcp_tsorted_anchor); 1753 tcp_rtx_queue_unlink(skb, sk); 1754 sk_wmem_free_skb(sk, skb); 1755 } 1756 1757 static inline void tcp_push_pending_frames(struct sock *sk) 1758 { 1759 if (tcp_send_head(sk)) { 1760 struct tcp_sock *tp = tcp_sk(sk); 1761 1762 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1763 } 1764 } 1765 1766 /* Start sequence of the skb just after the highest skb with SACKed 1767 * bit, valid only if sacked_out > 0 or when the caller has ensured 1768 * validity by itself. 1769 */ 1770 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1771 { 1772 if (!tp->sacked_out) 1773 return tp->snd_una; 1774 1775 if (tp->highest_sack == NULL) 1776 return tp->snd_nxt; 1777 1778 return TCP_SKB_CB(tp->highest_sack)->seq; 1779 } 1780 1781 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1782 { 1783 tcp_sk(sk)->highest_sack = skb_rb_next(skb); 1784 } 1785 1786 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1787 { 1788 return tcp_sk(sk)->highest_sack; 1789 } 1790 1791 static inline void tcp_highest_sack_reset(struct sock *sk) 1792 { 1793 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk); 1794 } 1795 1796 /* Called when old skb is about to be deleted and replaced by new skb */ 1797 static inline void tcp_highest_sack_replace(struct sock *sk, 1798 struct sk_buff *old, 1799 struct sk_buff *new) 1800 { 1801 if (old == tcp_highest_sack(sk)) 1802 tcp_sk(sk)->highest_sack = new; 1803 } 1804 1805 /* This helper checks if socket has IP_TRANSPARENT set */ 1806 static inline bool inet_sk_transparent(const struct sock *sk) 1807 { 1808 switch (sk->sk_state) { 1809 case TCP_TIME_WAIT: 1810 return inet_twsk(sk)->tw_transparent; 1811 case TCP_NEW_SYN_RECV: 1812 return inet_rsk(inet_reqsk(sk))->no_srccheck; 1813 } 1814 return inet_sk(sk)->transparent; 1815 } 1816 1817 /* Determines whether this is a thin stream (which may suffer from 1818 * increased latency). Used to trigger latency-reducing mechanisms. 1819 */ 1820 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1821 { 1822 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1823 } 1824 1825 /* /proc */ 1826 enum tcp_seq_states { 1827 TCP_SEQ_STATE_LISTENING, 1828 TCP_SEQ_STATE_ESTABLISHED, 1829 }; 1830 1831 void *tcp_seq_start(struct seq_file *seq, loff_t *pos); 1832 void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos); 1833 void tcp_seq_stop(struct seq_file *seq, void *v); 1834 1835 struct tcp_seq_afinfo { 1836 sa_family_t family; 1837 }; 1838 1839 struct tcp_iter_state { 1840 struct seq_net_private p; 1841 enum tcp_seq_states state; 1842 struct sock *syn_wait_sk; 1843 int bucket, offset, sbucket, num; 1844 loff_t last_pos; 1845 }; 1846 1847 extern struct request_sock_ops tcp_request_sock_ops; 1848 extern struct request_sock_ops tcp6_request_sock_ops; 1849 1850 void tcp_v4_destroy_sock(struct sock *sk); 1851 1852 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 1853 netdev_features_t features); 1854 struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb); 1855 int tcp_gro_complete(struct sk_buff *skb); 1856 1857 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 1858 1859 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 1860 { 1861 struct net *net = sock_net((struct sock *)tp); 1862 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat; 1863 } 1864 1865 /* @wake is one when sk_stream_write_space() calls us. 1866 * This sends EPOLLOUT only if notsent_bytes is half the limit. 1867 * This mimics the strategy used in sock_def_write_space(). 1868 */ 1869 static inline bool tcp_stream_memory_free(const struct sock *sk, int wake) 1870 { 1871 const struct tcp_sock *tp = tcp_sk(sk); 1872 u32 notsent_bytes = tp->write_seq - tp->snd_nxt; 1873 1874 return (notsent_bytes << wake) < tcp_notsent_lowat(tp); 1875 } 1876 1877 #ifdef CONFIG_PROC_FS 1878 int tcp4_proc_init(void); 1879 void tcp4_proc_exit(void); 1880 #endif 1881 1882 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req); 1883 int tcp_conn_request(struct request_sock_ops *rsk_ops, 1884 const struct tcp_request_sock_ops *af_ops, 1885 struct sock *sk, struct sk_buff *skb); 1886 1887 /* TCP af-specific functions */ 1888 struct tcp_sock_af_ops { 1889 #ifdef CONFIG_TCP_MD5SIG 1890 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk, 1891 const struct sock *addr_sk); 1892 int (*calc_md5_hash)(char *location, 1893 const struct tcp_md5sig_key *md5, 1894 const struct sock *sk, 1895 const struct sk_buff *skb); 1896 int (*md5_parse)(struct sock *sk, 1897 int optname, 1898 char __user *optval, 1899 int optlen); 1900 #endif 1901 }; 1902 1903 struct tcp_request_sock_ops { 1904 u16 mss_clamp; 1905 #ifdef CONFIG_TCP_MD5SIG 1906 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk, 1907 const struct sock *addr_sk); 1908 int (*calc_md5_hash) (char *location, 1909 const struct tcp_md5sig_key *md5, 1910 const struct sock *sk, 1911 const struct sk_buff *skb); 1912 #endif 1913 void (*init_req)(struct request_sock *req, 1914 const struct sock *sk_listener, 1915 struct sk_buff *skb); 1916 #ifdef CONFIG_SYN_COOKIES 1917 __u32 (*cookie_init_seq)(const struct sk_buff *skb, 1918 __u16 *mss); 1919 #endif 1920 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl, 1921 const struct request_sock *req); 1922 u32 (*init_seq)(const struct sk_buff *skb); 1923 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb); 1924 int (*send_synack)(const struct sock *sk, struct dst_entry *dst, 1925 struct flowi *fl, struct request_sock *req, 1926 struct tcp_fastopen_cookie *foc, 1927 enum tcp_synack_type synack_type); 1928 }; 1929 1930 #ifdef CONFIG_SYN_COOKIES 1931 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1932 const struct sock *sk, struct sk_buff *skb, 1933 __u16 *mss) 1934 { 1935 tcp_synq_overflow(sk); 1936 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); 1937 return ops->cookie_init_seq(skb, mss); 1938 } 1939 #else 1940 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1941 const struct sock *sk, struct sk_buff *skb, 1942 __u16 *mss) 1943 { 1944 return 0; 1945 } 1946 #endif 1947 1948 int tcpv4_offload_init(void); 1949 1950 void tcp_v4_init(void); 1951 void tcp_init(void); 1952 1953 /* tcp_recovery.c */ 1954 void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb); 1955 void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced); 1956 extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb, 1957 u32 reo_wnd); 1958 extern void tcp_rack_mark_lost(struct sock *sk); 1959 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq, 1960 u64 xmit_time); 1961 extern void tcp_rack_reo_timeout(struct sock *sk); 1962 extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs); 1963 1964 /* At how many usecs into the future should the RTO fire? */ 1965 static inline s64 tcp_rto_delta_us(const struct sock *sk) 1966 { 1967 const struct sk_buff *skb = tcp_rtx_queue_head(sk); 1968 u32 rto = inet_csk(sk)->icsk_rto; 1969 u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + jiffies_to_usecs(rto); 1970 1971 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp; 1972 } 1973 1974 /* 1975 * Save and compile IPv4 options, return a pointer to it 1976 */ 1977 static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net, 1978 struct sk_buff *skb) 1979 { 1980 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; 1981 struct ip_options_rcu *dopt = NULL; 1982 1983 if (opt->optlen) { 1984 int opt_size = sizeof(*dopt) + opt->optlen; 1985 1986 dopt = kmalloc(opt_size, GFP_ATOMIC); 1987 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) { 1988 kfree(dopt); 1989 dopt = NULL; 1990 } 1991 } 1992 return dopt; 1993 } 1994 1995 /* locally generated TCP pure ACKs have skb->truesize == 2 1996 * (check tcp_send_ack() in net/ipv4/tcp_output.c ) 1997 * This is much faster than dissecting the packet to find out. 1998 * (Think of GRE encapsulations, IPv4, IPv6, ...) 1999 */ 2000 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb) 2001 { 2002 return skb->truesize == 2; 2003 } 2004 2005 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb) 2006 { 2007 skb->truesize = 2; 2008 } 2009 2010 static inline int tcp_inq(struct sock *sk) 2011 { 2012 struct tcp_sock *tp = tcp_sk(sk); 2013 int answ; 2014 2015 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { 2016 answ = 0; 2017 } else if (sock_flag(sk, SOCK_URGINLINE) || 2018 !tp->urg_data || 2019 before(tp->urg_seq, tp->copied_seq) || 2020 !before(tp->urg_seq, tp->rcv_nxt)) { 2021 2022 answ = tp->rcv_nxt - tp->copied_seq; 2023 2024 /* Subtract 1, if FIN was received */ 2025 if (answ && sock_flag(sk, SOCK_DONE)) 2026 answ--; 2027 } else { 2028 answ = tp->urg_seq - tp->copied_seq; 2029 } 2030 2031 return answ; 2032 } 2033 2034 int tcp_peek_len(struct socket *sock); 2035 2036 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb) 2037 { 2038 u16 segs_in; 2039 2040 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs); 2041 tp->segs_in += segs_in; 2042 if (skb->len > tcp_hdrlen(skb)) 2043 tp->data_segs_in += segs_in; 2044 } 2045 2046 /* 2047 * TCP listen path runs lockless. 2048 * We forced "struct sock" to be const qualified to make sure 2049 * we don't modify one of its field by mistake. 2050 * Here, we increment sk_drops which is an atomic_t, so we can safely 2051 * make sock writable again. 2052 */ 2053 static inline void tcp_listendrop(const struct sock *sk) 2054 { 2055 atomic_inc(&((struct sock *)sk)->sk_drops); 2056 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 2057 } 2058 2059 enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer); 2060 2061 /* 2062 * Interface for adding Upper Level Protocols over TCP 2063 */ 2064 2065 #define TCP_ULP_NAME_MAX 16 2066 #define TCP_ULP_MAX 128 2067 #define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX) 2068 2069 struct tcp_ulp_ops { 2070 struct list_head list; 2071 2072 /* initialize ulp */ 2073 int (*init)(struct sock *sk); 2074 /* cleanup ulp */ 2075 void (*release)(struct sock *sk); 2076 2077 char name[TCP_ULP_NAME_MAX]; 2078 struct module *owner; 2079 }; 2080 int tcp_register_ulp(struct tcp_ulp_ops *type); 2081 void tcp_unregister_ulp(struct tcp_ulp_ops *type); 2082 int tcp_set_ulp(struct sock *sk, const char *name); 2083 void tcp_get_available_ulp(char *buf, size_t len); 2084 void tcp_cleanup_ulp(struct sock *sk); 2085 2086 #define MODULE_ALIAS_TCP_ULP(name) \ 2087 __MODULE_INFO(alias, alias_userspace, name); \ 2088 __MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name) 2089 2090 struct sk_msg; 2091 struct sk_psock; 2092 2093 int tcp_bpf_init(struct sock *sk); 2094 void tcp_bpf_reinit(struct sock *sk); 2095 int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg, u32 bytes, 2096 int flags); 2097 int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, 2098 int nonblock, int flags, int *addr_len); 2099 int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock, 2100 struct msghdr *msg, int len, int flags); 2101 2102 /* Call BPF_SOCK_OPS program that returns an int. If the return value 2103 * is < 0, then the BPF op failed (for example if the loaded BPF 2104 * program does not support the chosen operation or there is no BPF 2105 * program loaded). 2106 */ 2107 #ifdef CONFIG_BPF 2108 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args) 2109 { 2110 struct bpf_sock_ops_kern sock_ops; 2111 int ret; 2112 2113 memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); 2114 if (sk_fullsock(sk)) { 2115 sock_ops.is_fullsock = 1; 2116 sock_owned_by_me(sk); 2117 } 2118 2119 sock_ops.sk = sk; 2120 sock_ops.op = op; 2121 if (nargs > 0) 2122 memcpy(sock_ops.args, args, nargs * sizeof(*args)); 2123 2124 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops); 2125 if (ret == 0) 2126 ret = sock_ops.reply; 2127 else 2128 ret = -1; 2129 return ret; 2130 } 2131 2132 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2) 2133 { 2134 u32 args[2] = {arg1, arg2}; 2135 2136 return tcp_call_bpf(sk, op, 2, args); 2137 } 2138 2139 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2, 2140 u32 arg3) 2141 { 2142 u32 args[3] = {arg1, arg2, arg3}; 2143 2144 return tcp_call_bpf(sk, op, 3, args); 2145 } 2146 2147 #else 2148 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args) 2149 { 2150 return -EPERM; 2151 } 2152 2153 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2) 2154 { 2155 return -EPERM; 2156 } 2157 2158 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2, 2159 u32 arg3) 2160 { 2161 return -EPERM; 2162 } 2163 2164 #endif 2165 2166 static inline u32 tcp_timeout_init(struct sock *sk) 2167 { 2168 int timeout; 2169 2170 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL); 2171 2172 if (timeout <= 0) 2173 timeout = TCP_TIMEOUT_INIT; 2174 return timeout; 2175 } 2176 2177 static inline u32 tcp_rwnd_init_bpf(struct sock *sk) 2178 { 2179 int rwnd; 2180 2181 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL); 2182 2183 if (rwnd < 0) 2184 rwnd = 0; 2185 return rwnd; 2186 } 2187 2188 static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk) 2189 { 2190 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1); 2191 } 2192 2193 #if IS_ENABLED(CONFIG_SMC) 2194 extern struct static_key_false tcp_have_smc; 2195 #endif 2196 2197 #if IS_ENABLED(CONFIG_TLS_DEVICE) 2198 void clean_acked_data_enable(struct inet_connection_sock *icsk, 2199 void (*cad)(struct sock *sk, u32 ack_seq)); 2200 void clean_acked_data_disable(struct inet_connection_sock *icsk); 2201 void clean_acked_data_flush(void); 2202 #endif 2203 2204 #endif /* _TCP_H */ 2205