1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * INET An implementation of the TCP/IP protocol suite for the LINUX 4 * operating system. INET is implemented using the BSD Socket 5 * interface as the means of communication with the user level. 6 * 7 * Definitions for the TCP module. 8 * 9 * Version: @(#)tcp.h 1.0.5 05/23/93 10 * 11 * Authors: Ross Biro 12 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 13 */ 14 #ifndef _TCP_H 15 #define _TCP_H 16 17 #define FASTRETRANS_DEBUG 1 18 19 #include <linux/list.h> 20 #include <linux/tcp.h> 21 #include <linux/bug.h> 22 #include <linux/slab.h> 23 #include <linux/cache.h> 24 #include <linux/percpu.h> 25 #include <linux/skbuff.h> 26 #include <linux/kref.h> 27 #include <linux/ktime.h> 28 #include <linux/indirect_call_wrapper.h> 29 30 #include <net/inet_connection_sock.h> 31 #include <net/inet_timewait_sock.h> 32 #include <net/inet_hashtables.h> 33 #include <net/checksum.h> 34 #include <net/request_sock.h> 35 #include <net/sock_reuseport.h> 36 #include <net/sock.h> 37 #include <net/snmp.h> 38 #include <net/ip.h> 39 #include <net/tcp_states.h> 40 #include <net/tcp_ao.h> 41 #include <net/inet_ecn.h> 42 #include <net/dst.h> 43 #include <net/mptcp.h> 44 45 #include <linux/seq_file.h> 46 #include <linux/memcontrol.h> 47 #include <linux/bpf-cgroup.h> 48 #include <linux/siphash.h> 49 50 extern struct inet_hashinfo tcp_hashinfo; 51 52 DECLARE_PER_CPU(unsigned int, tcp_orphan_count); 53 int tcp_orphan_count_sum(void); 54 55 DECLARE_PER_CPU(u32, tcp_tw_isn); 56 57 void tcp_time_wait(struct sock *sk, int state, int timeo); 58 59 #define MAX_TCP_HEADER L1_CACHE_ALIGN(128 + MAX_HEADER) 60 #define MAX_TCP_OPTION_SPACE 40 61 #define TCP_MIN_SND_MSS 48 62 #define TCP_MIN_GSO_SIZE (TCP_MIN_SND_MSS - MAX_TCP_OPTION_SPACE) 63 64 /* 65 * Never offer a window over 32767 without using window scaling. Some 66 * poor stacks do signed 16bit maths! 67 */ 68 #define MAX_TCP_WINDOW 32767U 69 70 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */ 71 #define TCP_MIN_MSS 88U 72 73 /* The initial MTU to use for probing */ 74 #define TCP_BASE_MSS 1024 75 76 /* probing interval, default to 10 minutes as per RFC4821 */ 77 #define TCP_PROBE_INTERVAL 600 78 79 /* Specify interval when tcp mtu probing will stop */ 80 #define TCP_PROBE_THRESHOLD 8 81 82 /* After receiving this amount of duplicate ACKs fast retransmit starts. */ 83 #define TCP_FASTRETRANS_THRESH 3 84 85 /* Maximal number of ACKs sent quickly to accelerate slow-start. */ 86 #define TCP_MAX_QUICKACKS 16U 87 88 /* Maximal number of window scale according to RFC1323 */ 89 #define TCP_MAX_WSCALE 14U 90 91 /* urg_data states */ 92 #define TCP_URG_VALID 0x0100 93 #define TCP_URG_NOTYET 0x0200 94 #define TCP_URG_READ 0x0400 95 96 #define TCP_RETR1 3 /* 97 * This is how many retries it does before it 98 * tries to figure out if the gateway is 99 * down. Minimal RFC value is 3; it corresponds 100 * to ~3sec-8min depending on RTO. 101 */ 102 103 #define TCP_RETR2 15 /* 104 * This should take at least 105 * 90 minutes to time out. 106 * RFC1122 says that the limit is 100 sec. 107 * 15 is ~13-30min depending on RTO. 108 */ 109 110 #define TCP_SYN_RETRIES 6 /* This is how many retries are done 111 * when active opening a connection. 112 * RFC1122 says the minimum retry MUST 113 * be at least 180secs. Nevertheless 114 * this value is corresponding to 115 * 63secs of retransmission with the 116 * current initial RTO. 117 */ 118 119 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done 120 * when passive opening a connection. 121 * This is corresponding to 31secs of 122 * retransmission with the current 123 * initial RTO. 124 */ 125 126 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT 127 * state, about 60 seconds */ 128 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN 129 /* BSD style FIN_WAIT2 deadlock breaker. 130 * It used to be 3min, new value is 60sec, 131 * to combine FIN-WAIT-2 timeout with 132 * TIME-WAIT timer. 133 */ 134 #define TCP_FIN_TIMEOUT_MAX (120 * HZ) /* max TCP_LINGER2 value (two minutes) */ 135 136 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ 137 static_assert((1 << ATO_BITS) > TCP_DELACK_MAX); 138 139 #if HZ >= 100 140 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */ 141 #define TCP_ATO_MIN ((unsigned)(HZ/25)) 142 #else 143 #define TCP_DELACK_MIN 4U 144 #define TCP_ATO_MIN 4U 145 #endif 146 #define TCP_RTO_MAX_SEC 120 147 #define TCP_RTO_MAX ((unsigned)(TCP_RTO_MAX_SEC * HZ)) 148 #define TCP_RTO_MIN ((unsigned)(HZ / 5)) 149 #define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */ 150 151 #define TCP_TIMEOUT_MIN_US (2*USEC_PER_MSEC) /* Min TCP timeout in microsecs */ 152 153 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */ 154 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now 155 * used as a fallback RTO for the 156 * initial data transmission if no 157 * valid RTT sample has been acquired, 158 * most likely due to retrans in 3WHS. 159 */ 160 161 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes 162 * for local resources. 163 */ 164 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ 165 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ 166 #define TCP_KEEPALIVE_INTVL (75*HZ) 167 168 #define MAX_TCP_KEEPIDLE 32767 169 #define MAX_TCP_KEEPINTVL 32767 170 #define MAX_TCP_KEEPCNT 127 171 #define MAX_TCP_SYNCNT 127 172 173 /* Ensure that TCP PAWS checks are relaxed after ~2147 seconds 174 * to avoid overflows. This assumes a clock smaller than 1 Mhz. 175 * Default clock is 1 Khz, tcp_usec_ts uses 1 Mhz. 176 */ 177 #define TCP_PAWS_WRAP (INT_MAX / USEC_PER_SEC) 178 179 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated 180 * after this time. It should be equal 181 * (or greater than) TCP_TIMEWAIT_LEN 182 * to provide reliability equal to one 183 * provided by timewait state. 184 */ 185 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host 186 * timestamps. It must be less than 187 * minimal timewait lifetime. 188 */ 189 /* 190 * TCP option 191 */ 192 193 #define TCPOPT_NOP 1 /* Padding */ 194 #define TCPOPT_EOL 0 /* End of options */ 195 #define TCPOPT_MSS 2 /* Segment size negotiating */ 196 #define TCPOPT_WINDOW 3 /* Window scaling */ 197 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ 198 #define TCPOPT_SACK 5 /* SACK Block */ 199 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ 200 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */ 201 #define TCPOPT_AO 29 /* Authentication Option (RFC5925) */ 202 #define TCPOPT_MPTCP 30 /* Multipath TCP (RFC6824) */ 203 #define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */ 204 #define TCPOPT_EXP 254 /* Experimental */ 205 /* Magic number to be after the option value for sharing TCP 206 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt 207 */ 208 #define TCPOPT_FASTOPEN_MAGIC 0xF989 209 #define TCPOPT_SMC_MAGIC 0xE2D4C3D9 210 211 /* 212 * TCP option lengths 213 */ 214 215 #define TCPOLEN_MSS 4 216 #define TCPOLEN_WINDOW 3 217 #define TCPOLEN_SACK_PERM 2 218 #define TCPOLEN_TIMESTAMP 10 219 #define TCPOLEN_MD5SIG 18 220 #define TCPOLEN_FASTOPEN_BASE 2 221 #define TCPOLEN_EXP_FASTOPEN_BASE 4 222 #define TCPOLEN_EXP_SMC_BASE 6 223 224 /* But this is what stacks really send out. */ 225 #define TCPOLEN_TSTAMP_ALIGNED 12 226 #define TCPOLEN_WSCALE_ALIGNED 4 227 #define TCPOLEN_SACKPERM_ALIGNED 4 228 #define TCPOLEN_SACK_BASE 2 229 #define TCPOLEN_SACK_BASE_ALIGNED 4 230 #define TCPOLEN_SACK_PERBLOCK 8 231 #define TCPOLEN_MD5SIG_ALIGNED 20 232 #define TCPOLEN_MSS_ALIGNED 4 233 #define TCPOLEN_EXP_SMC_BASE_ALIGNED 8 234 235 /* Flags in tp->nonagle */ 236 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */ 237 #define TCP_NAGLE_CORK 2 /* Socket is corked */ 238 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */ 239 240 /* TCP thin-stream limits */ 241 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */ 242 243 /* TCP initial congestion window as per rfc6928 */ 244 #define TCP_INIT_CWND 10 245 246 /* Bit Flags for sysctl_tcp_fastopen */ 247 #define TFO_CLIENT_ENABLE 1 248 #define TFO_SERVER_ENABLE 2 249 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */ 250 251 /* Accept SYN data w/o any cookie option */ 252 #define TFO_SERVER_COOKIE_NOT_REQD 0x200 253 254 /* Force enable TFO on all listeners, i.e., not requiring the 255 * TCP_FASTOPEN socket option. 256 */ 257 #define TFO_SERVER_WO_SOCKOPT1 0x400 258 259 260 /* sysctl variables for tcp */ 261 extern int sysctl_tcp_max_orphans; 262 extern long sysctl_tcp_mem[3]; 263 264 #define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */ 265 #define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */ 266 #define TCP_RACK_NO_DUPTHRESH 0x4 /* Do not use DUPACK threshold in RACK */ 267 268 extern atomic_long_t tcp_memory_allocated; 269 DECLARE_PER_CPU(int, tcp_memory_per_cpu_fw_alloc); 270 271 extern struct percpu_counter tcp_sockets_allocated; 272 extern unsigned long tcp_memory_pressure; 273 274 /* optimized version of sk_under_memory_pressure() for TCP sockets */ 275 static inline bool tcp_under_memory_pressure(const struct sock *sk) 276 { 277 if (mem_cgroup_sockets_enabled && sk->sk_memcg && 278 mem_cgroup_under_socket_pressure(sk->sk_memcg)) 279 return true; 280 281 return READ_ONCE(tcp_memory_pressure); 282 } 283 /* 284 * The next routines deal with comparing 32 bit unsigned ints 285 * and worry about wraparound (automatic with unsigned arithmetic). 286 */ 287 288 static inline bool before(__u32 seq1, __u32 seq2) 289 { 290 return (__s32)(seq1-seq2) < 0; 291 } 292 #define after(seq2, seq1) before(seq1, seq2) 293 294 /* is s2<=s1<=s3 ? */ 295 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) 296 { 297 return seq3 - seq2 >= seq1 - seq2; 298 } 299 300 static inline void tcp_wmem_free_skb(struct sock *sk, struct sk_buff *skb) 301 { 302 sk_wmem_queued_add(sk, -skb->truesize); 303 if (!skb_zcopy_pure(skb)) 304 sk_mem_uncharge(sk, skb->truesize); 305 else 306 sk_mem_uncharge(sk, SKB_TRUESIZE(skb_end_offset(skb))); 307 __kfree_skb(skb); 308 } 309 310 void sk_forced_mem_schedule(struct sock *sk, int size); 311 312 bool tcp_check_oom(const struct sock *sk, int shift); 313 314 315 extern struct proto tcp_prot; 316 317 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 318 #define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field) 319 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 320 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 321 322 void tcp_tasklet_init(void); 323 324 int tcp_v4_err(struct sk_buff *skb, u32); 325 326 void tcp_shutdown(struct sock *sk, int how); 327 328 int tcp_v4_early_demux(struct sk_buff *skb); 329 int tcp_v4_rcv(struct sk_buff *skb); 330 331 void tcp_remove_empty_skb(struct sock *sk); 332 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size); 333 int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size); 334 int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, int *copied, 335 size_t size, struct ubuf_info *uarg); 336 void tcp_splice_eof(struct socket *sock); 337 int tcp_send_mss(struct sock *sk, int *size_goal, int flags); 338 int tcp_wmem_schedule(struct sock *sk, int copy); 339 void tcp_push(struct sock *sk, int flags, int mss_now, int nonagle, 340 int size_goal); 341 void tcp_release_cb(struct sock *sk); 342 void tcp_wfree(struct sk_buff *skb); 343 void tcp_write_timer_handler(struct sock *sk); 344 void tcp_delack_timer_handler(struct sock *sk); 345 int tcp_ioctl(struct sock *sk, int cmd, int *karg); 346 enum skb_drop_reason tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb); 347 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb); 348 void tcp_rcv_space_adjust(struct sock *sk); 349 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 350 void tcp_twsk_destructor(struct sock *sk); 351 void tcp_twsk_purge(struct list_head *net_exit_list); 352 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 353 struct pipe_inode_info *pipe, size_t len, 354 unsigned int flags); 355 struct sk_buff *tcp_stream_alloc_skb(struct sock *sk, gfp_t gfp, 356 bool force_schedule); 357 358 static inline void tcp_dec_quickack_mode(struct sock *sk) 359 { 360 struct inet_connection_sock *icsk = inet_csk(sk); 361 362 if (icsk->icsk_ack.quick) { 363 /* How many ACKs S/ACKing new data have we sent? */ 364 const unsigned int pkts = inet_csk_ack_scheduled(sk) ? 1 : 0; 365 366 if (pkts >= icsk->icsk_ack.quick) { 367 icsk->icsk_ack.quick = 0; 368 /* Leaving quickack mode we deflate ATO. */ 369 icsk->icsk_ack.ato = TCP_ATO_MIN; 370 } else 371 icsk->icsk_ack.quick -= pkts; 372 } 373 } 374 375 #define TCP_ECN_OK 1 376 #define TCP_ECN_QUEUE_CWR 2 377 #define TCP_ECN_DEMAND_CWR 4 378 #define TCP_ECN_SEEN 8 379 380 enum tcp_tw_status { 381 TCP_TW_SUCCESS = 0, 382 TCP_TW_RST = 1, 383 TCP_TW_ACK = 2, 384 TCP_TW_SYN = 3 385 }; 386 387 388 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 389 struct sk_buff *skb, 390 const struct tcphdr *th, 391 u32 *tw_isn); 392 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 393 struct request_sock *req, bool fastopen, 394 bool *lost_race); 395 enum skb_drop_reason tcp_child_process(struct sock *parent, struct sock *child, 396 struct sk_buff *skb); 397 void tcp_enter_loss(struct sock *sk); 398 void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int newly_lost, int flag); 399 void tcp_clear_retrans(struct tcp_sock *tp); 400 void tcp_update_metrics(struct sock *sk); 401 void tcp_init_metrics(struct sock *sk); 402 void tcp_metrics_init(void); 403 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst); 404 void __tcp_close(struct sock *sk, long timeout); 405 void tcp_close(struct sock *sk, long timeout); 406 void tcp_init_sock(struct sock *sk); 407 void tcp_init_transfer(struct sock *sk, int bpf_op, struct sk_buff *skb); 408 __poll_t tcp_poll(struct file *file, struct socket *sock, 409 struct poll_table_struct *wait); 410 int do_tcp_getsockopt(struct sock *sk, int level, 411 int optname, sockptr_t optval, sockptr_t optlen); 412 int tcp_getsockopt(struct sock *sk, int level, int optname, 413 char __user *optval, int __user *optlen); 414 bool tcp_bpf_bypass_getsockopt(int level, int optname); 415 int do_tcp_setsockopt(struct sock *sk, int level, int optname, 416 sockptr_t optval, unsigned int optlen); 417 int tcp_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval, 418 unsigned int optlen); 419 void tcp_reset_keepalive_timer(struct sock *sk, unsigned long timeout); 420 void tcp_set_keepalive(struct sock *sk, int val); 421 void tcp_syn_ack_timeout(const struct request_sock *req); 422 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, 423 int flags, int *addr_len); 424 int tcp_set_rcvlowat(struct sock *sk, int val); 425 int tcp_set_window_clamp(struct sock *sk, int val); 426 void tcp_update_recv_tstamps(struct sk_buff *skb, 427 struct scm_timestamping_internal *tss); 428 void tcp_recv_timestamp(struct msghdr *msg, const struct sock *sk, 429 struct scm_timestamping_internal *tss); 430 void tcp_data_ready(struct sock *sk); 431 #ifdef CONFIG_MMU 432 int tcp_mmap(struct file *file, struct socket *sock, 433 struct vm_area_struct *vma); 434 #endif 435 void tcp_parse_options(const struct net *net, const struct sk_buff *skb, 436 struct tcp_options_received *opt_rx, 437 int estab, struct tcp_fastopen_cookie *foc); 438 439 /* 440 * BPF SKB-less helpers 441 */ 442 u16 tcp_v4_get_syncookie(struct sock *sk, struct iphdr *iph, 443 struct tcphdr *th, u32 *cookie); 444 u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph, 445 struct tcphdr *th, u32 *cookie); 446 u16 tcp_parse_mss_option(const struct tcphdr *th, u16 user_mss); 447 u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops, 448 const struct tcp_request_sock_ops *af_ops, 449 struct sock *sk, struct tcphdr *th); 450 /* 451 * TCP v4 functions exported for the inet6 API 452 */ 453 454 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 455 void tcp_v4_mtu_reduced(struct sock *sk); 456 void tcp_req_err(struct sock *sk, u32 seq, bool abort); 457 void tcp_ld_RTO_revert(struct sock *sk, u32 seq); 458 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 459 struct sock *tcp_create_openreq_child(const struct sock *sk, 460 struct request_sock *req, 461 struct sk_buff *skb); 462 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst); 463 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 464 struct request_sock *req, 465 struct dst_entry *dst, 466 struct request_sock *req_unhash, 467 bool *own_req); 468 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 469 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); 470 int tcp_connect(struct sock *sk); 471 enum tcp_synack_type { 472 TCP_SYNACK_NORMAL, 473 TCP_SYNACK_FASTOPEN, 474 TCP_SYNACK_COOKIE, 475 }; 476 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 477 struct request_sock *req, 478 struct tcp_fastopen_cookie *foc, 479 enum tcp_synack_type synack_type, 480 struct sk_buff *syn_skb); 481 int tcp_disconnect(struct sock *sk, int flags); 482 483 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 484 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 485 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); 486 487 /* From syncookies.c */ 488 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, 489 struct request_sock *req, 490 struct dst_entry *dst); 491 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th); 492 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb); 493 struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops, 494 struct sock *sk, struct sk_buff *skb, 495 struct tcp_options_received *tcp_opt, 496 int mss, u32 tsoff); 497 498 #if IS_ENABLED(CONFIG_BPF) 499 struct bpf_tcp_req_attrs { 500 u32 rcv_tsval; 501 u32 rcv_tsecr; 502 u16 mss; 503 u8 rcv_wscale; 504 u8 snd_wscale; 505 u8 ecn_ok; 506 u8 wscale_ok; 507 u8 sack_ok; 508 u8 tstamp_ok; 509 u8 usec_ts_ok; 510 u8 reserved[3]; 511 }; 512 #endif 513 514 #ifdef CONFIG_SYN_COOKIES 515 516 /* Syncookies use a monotonic timer which increments every 60 seconds. 517 * This counter is used both as a hash input and partially encoded into 518 * the cookie value. A cookie is only validated further if the delta 519 * between the current counter value and the encoded one is less than this, 520 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if 521 * the counter advances immediately after a cookie is generated). 522 */ 523 #define MAX_SYNCOOKIE_AGE 2 524 #define TCP_SYNCOOKIE_PERIOD (60 * HZ) 525 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD) 526 527 /* syncookies: remember time of last synqueue overflow 528 * But do not dirty this field too often (once per second is enough) 529 * It is racy as we do not hold a lock, but race is very minor. 530 */ 531 static inline void tcp_synq_overflow(const struct sock *sk) 532 { 533 unsigned int last_overflow; 534 unsigned int now = jiffies; 535 536 if (sk->sk_reuseport) { 537 struct sock_reuseport *reuse; 538 539 reuse = rcu_dereference(sk->sk_reuseport_cb); 540 if (likely(reuse)) { 541 last_overflow = READ_ONCE(reuse->synq_overflow_ts); 542 if (!time_between32(now, last_overflow, 543 last_overflow + HZ)) 544 WRITE_ONCE(reuse->synq_overflow_ts, now); 545 return; 546 } 547 } 548 549 last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp); 550 if (!time_between32(now, last_overflow, last_overflow + HZ)) 551 WRITE_ONCE(tcp_sk_rw(sk)->rx_opt.ts_recent_stamp, now); 552 } 553 554 /* syncookies: no recent synqueue overflow on this listening socket? */ 555 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 556 { 557 unsigned int last_overflow; 558 unsigned int now = jiffies; 559 560 if (sk->sk_reuseport) { 561 struct sock_reuseport *reuse; 562 563 reuse = rcu_dereference(sk->sk_reuseport_cb); 564 if (likely(reuse)) { 565 last_overflow = READ_ONCE(reuse->synq_overflow_ts); 566 return !time_between32(now, last_overflow - HZ, 567 last_overflow + 568 TCP_SYNCOOKIE_VALID); 569 } 570 } 571 572 last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp); 573 574 /* If last_overflow <= jiffies <= last_overflow + TCP_SYNCOOKIE_VALID, 575 * then we're under synflood. However, we have to use 576 * 'last_overflow - HZ' as lower bound. That's because a concurrent 577 * tcp_synq_overflow() could update .ts_recent_stamp after we read 578 * jiffies but before we store .ts_recent_stamp into last_overflow, 579 * which could lead to rejecting a valid syncookie. 580 */ 581 return !time_between32(now, last_overflow - HZ, 582 last_overflow + TCP_SYNCOOKIE_VALID); 583 } 584 585 static inline u32 tcp_cookie_time(void) 586 { 587 u64 val = get_jiffies_64(); 588 589 do_div(val, TCP_SYNCOOKIE_PERIOD); 590 return val; 591 } 592 593 /* Convert one nsec 64bit timestamp to ts (ms or usec resolution) */ 594 static inline u64 tcp_ns_to_ts(bool usec_ts, u64 val) 595 { 596 if (usec_ts) 597 return div_u64(val, NSEC_PER_USEC); 598 599 return div_u64(val, NSEC_PER_MSEC); 600 } 601 602 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, 603 u16 *mssp); 604 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss); 605 u64 cookie_init_timestamp(struct request_sock *req, u64 now); 606 bool cookie_timestamp_decode(const struct net *net, 607 struct tcp_options_received *opt); 608 609 static inline bool cookie_ecn_ok(const struct net *net, const struct dst_entry *dst) 610 { 611 return READ_ONCE(net->ipv4.sysctl_tcp_ecn) || 612 dst_feature(dst, RTAX_FEATURE_ECN); 613 } 614 615 #if IS_ENABLED(CONFIG_BPF) 616 static inline bool cookie_bpf_ok(struct sk_buff *skb) 617 { 618 return skb->sk; 619 } 620 621 struct request_sock *cookie_bpf_check(struct sock *sk, struct sk_buff *skb); 622 #else 623 static inline bool cookie_bpf_ok(struct sk_buff *skb) 624 { 625 return false; 626 } 627 628 static inline struct request_sock *cookie_bpf_check(struct net *net, struct sock *sk, 629 struct sk_buff *skb) 630 { 631 return NULL; 632 } 633 #endif 634 635 /* From net/ipv6/syncookies.c */ 636 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th); 637 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 638 639 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph, 640 const struct tcphdr *th, u16 *mssp); 641 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss); 642 #endif 643 /* tcp_output.c */ 644 645 void tcp_skb_entail(struct sock *sk, struct sk_buff *skb); 646 void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb); 647 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 648 int nonagle); 649 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 650 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 651 void tcp_retransmit_timer(struct sock *sk); 652 void tcp_xmit_retransmit_queue(struct sock *); 653 void tcp_simple_retransmit(struct sock *); 654 void tcp_enter_recovery(struct sock *sk, bool ece_ack); 655 int tcp_trim_head(struct sock *, struct sk_buff *, u32); 656 enum tcp_queue { 657 TCP_FRAG_IN_WRITE_QUEUE, 658 TCP_FRAG_IN_RTX_QUEUE, 659 }; 660 int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, 661 struct sk_buff *skb, u32 len, 662 unsigned int mss_now, gfp_t gfp); 663 664 void tcp_send_probe0(struct sock *); 665 int tcp_write_wakeup(struct sock *, int mib); 666 void tcp_send_fin(struct sock *sk); 667 void tcp_send_active_reset(struct sock *sk, gfp_t priority, 668 enum sk_rst_reason reason); 669 int tcp_send_synack(struct sock *); 670 void tcp_push_one(struct sock *, unsigned int mss_now); 671 void __tcp_send_ack(struct sock *sk, u32 rcv_nxt); 672 void tcp_send_ack(struct sock *sk); 673 void tcp_send_delayed_ack(struct sock *sk); 674 void tcp_send_loss_probe(struct sock *sk); 675 bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto); 676 void tcp_skb_collapse_tstamp(struct sk_buff *skb, 677 const struct sk_buff *next_skb); 678 679 /* tcp_input.c */ 680 void tcp_rearm_rto(struct sock *sk); 681 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req); 682 void tcp_done_with_error(struct sock *sk, int err); 683 void tcp_reset(struct sock *sk, struct sk_buff *skb); 684 void tcp_fin(struct sock *sk); 685 void tcp_check_space(struct sock *sk); 686 void tcp_sack_compress_send_ack(struct sock *sk); 687 688 /* tcp_timer.c */ 689 void tcp_init_xmit_timers(struct sock *); 690 static inline void tcp_clear_xmit_timers(struct sock *sk) 691 { 692 if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1) 693 __sock_put(sk); 694 695 if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1) 696 __sock_put(sk); 697 698 inet_csk_clear_xmit_timers(sk); 699 } 700 701 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 702 unsigned int tcp_current_mss(struct sock *sk); 703 u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when); 704 705 /* Bound MSS / TSO packet size with the half of the window */ 706 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 707 { 708 int cutoff; 709 710 /* When peer uses tiny windows, there is no use in packetizing 711 * to sub-MSS pieces for the sake of SWS or making sure there 712 * are enough packets in the pipe for fast recovery. 713 * 714 * On the other hand, for extremely large MSS devices, handling 715 * smaller than MSS windows in this way does make sense. 716 */ 717 if (tp->max_window > TCP_MSS_DEFAULT) 718 cutoff = (tp->max_window >> 1); 719 else 720 cutoff = tp->max_window; 721 722 if (cutoff && pktsize > cutoff) 723 return max_t(int, cutoff, 68U - tp->tcp_header_len); 724 else 725 return pktsize; 726 } 727 728 /* tcp.c */ 729 void tcp_get_info(struct sock *, struct tcp_info *); 730 731 /* Read 'sendfile()'-style from a TCP socket */ 732 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 733 sk_read_actor_t recv_actor); 734 int tcp_read_skb(struct sock *sk, skb_read_actor_t recv_actor); 735 struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off); 736 void tcp_read_done(struct sock *sk, size_t len); 737 738 void tcp_initialize_rcv_mss(struct sock *sk); 739 740 int tcp_mtu_to_mss(struct sock *sk, int pmtu); 741 int tcp_mss_to_mtu(struct sock *sk, int mss); 742 void tcp_mtup_init(struct sock *sk); 743 744 static inline unsigned int tcp_rto_max(const struct sock *sk) 745 { 746 return READ_ONCE(inet_csk(sk)->icsk_rto_max); 747 } 748 749 static inline void tcp_bound_rto(struct sock *sk) 750 { 751 inet_csk(sk)->icsk_rto = min(inet_csk(sk)->icsk_rto, tcp_rto_max(sk)); 752 } 753 754 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 755 { 756 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us); 757 } 758 759 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 760 { 761 /* mptcp hooks are only on the slow path */ 762 if (sk_is_mptcp((struct sock *)tp)) 763 return; 764 765 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 766 ntohl(TCP_FLAG_ACK) | 767 snd_wnd); 768 } 769 770 static inline void tcp_fast_path_on(struct tcp_sock *tp) 771 { 772 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 773 } 774 775 static inline void tcp_fast_path_check(struct sock *sk) 776 { 777 struct tcp_sock *tp = tcp_sk(sk); 778 779 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) && 780 tp->rcv_wnd && 781 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 782 !tp->urg_data) 783 tcp_fast_path_on(tp); 784 } 785 786 u32 tcp_delack_max(const struct sock *sk); 787 788 /* Compute the actual rto_min value */ 789 static inline u32 tcp_rto_min(const struct sock *sk) 790 { 791 const struct dst_entry *dst = __sk_dst_get(sk); 792 u32 rto_min = inet_csk(sk)->icsk_rto_min; 793 794 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 795 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 796 return rto_min; 797 } 798 799 static inline u32 tcp_rto_min_us(const struct sock *sk) 800 { 801 return jiffies_to_usecs(tcp_rto_min(sk)); 802 } 803 804 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst) 805 { 806 return dst_metric_locked(dst, RTAX_CC_ALGO); 807 } 808 809 /* Minimum RTT in usec. ~0 means not available. */ 810 static inline u32 tcp_min_rtt(const struct tcp_sock *tp) 811 { 812 return minmax_get(&tp->rtt_min); 813 } 814 815 /* Compute the actual receive window we are currently advertising. 816 * Rcv_nxt can be after the window if our peer push more data 817 * than the offered window. 818 */ 819 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 820 { 821 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 822 823 if (win < 0) 824 win = 0; 825 return (u32) win; 826 } 827 828 /* Choose a new window, without checks for shrinking, and without 829 * scaling applied to the result. The caller does these things 830 * if necessary. This is a "raw" window selection. 831 */ 832 u32 __tcp_select_window(struct sock *sk); 833 834 void tcp_send_window_probe(struct sock *sk); 835 836 /* TCP uses 32bit jiffies to save some space. 837 * Note that this is different from tcp_time_stamp, which 838 * historically has been the same until linux-4.13. 839 */ 840 #define tcp_jiffies32 ((u32)jiffies) 841 842 /* 843 * Deliver a 32bit value for TCP timestamp option (RFC 7323) 844 * It is no longer tied to jiffies, but to 1 ms clock. 845 * Note: double check if you want to use tcp_jiffies32 instead of this. 846 */ 847 #define TCP_TS_HZ 1000 848 849 static inline u64 tcp_clock_ns(void) 850 { 851 return ktime_get_ns(); 852 } 853 854 static inline u64 tcp_clock_us(void) 855 { 856 return div_u64(tcp_clock_ns(), NSEC_PER_USEC); 857 } 858 859 static inline u64 tcp_clock_ms(void) 860 { 861 return div_u64(tcp_clock_ns(), NSEC_PER_MSEC); 862 } 863 864 /* TCP Timestamp included in TS option (RFC 1323) can either use ms 865 * or usec resolution. Each socket carries a flag to select one or other 866 * resolution, as the route attribute could change anytime. 867 * Each flow must stick to initial resolution. 868 */ 869 static inline u32 tcp_clock_ts(bool usec_ts) 870 { 871 return usec_ts ? tcp_clock_us() : tcp_clock_ms(); 872 } 873 874 static inline u32 tcp_time_stamp_ms(const struct tcp_sock *tp) 875 { 876 return div_u64(tp->tcp_mstamp, USEC_PER_MSEC); 877 } 878 879 static inline u32 tcp_time_stamp_ts(const struct tcp_sock *tp) 880 { 881 if (tp->tcp_usec_ts) 882 return tp->tcp_mstamp; 883 return tcp_time_stamp_ms(tp); 884 } 885 886 void tcp_mstamp_refresh(struct tcp_sock *tp); 887 888 static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0) 889 { 890 return max_t(s64, t1 - t0, 0); 891 } 892 893 /* provide the departure time in us unit */ 894 static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb) 895 { 896 return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC); 897 } 898 899 /* Provide skb TSval in usec or ms unit */ 900 static inline u32 tcp_skb_timestamp_ts(bool usec_ts, const struct sk_buff *skb) 901 { 902 if (usec_ts) 903 return tcp_skb_timestamp_us(skb); 904 905 return div_u64(skb->skb_mstamp_ns, NSEC_PER_MSEC); 906 } 907 908 static inline u32 tcp_tw_tsval(const struct tcp_timewait_sock *tcptw) 909 { 910 return tcp_clock_ts(tcptw->tw_sk.tw_usec_ts) + tcptw->tw_ts_offset; 911 } 912 913 static inline u32 tcp_rsk_tsval(const struct tcp_request_sock *treq) 914 { 915 return tcp_clock_ts(treq->req_usec_ts) + treq->ts_off; 916 } 917 918 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 919 920 #define TCPHDR_FIN 0x01 921 #define TCPHDR_SYN 0x02 922 #define TCPHDR_RST 0x04 923 #define TCPHDR_PSH 0x08 924 #define TCPHDR_ACK 0x10 925 #define TCPHDR_URG 0x20 926 #define TCPHDR_ECE 0x40 927 #define TCPHDR_CWR 0x80 928 929 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) 930 931 /* State flags for sacked in struct tcp_skb_cb */ 932 enum tcp_skb_cb_sacked_flags { 933 TCPCB_SACKED_ACKED = (1 << 0), /* SKB ACK'd by a SACK block */ 934 TCPCB_SACKED_RETRANS = (1 << 1), /* SKB retransmitted */ 935 TCPCB_LOST = (1 << 2), /* SKB is lost */ 936 TCPCB_TAGBITS = (TCPCB_SACKED_ACKED | TCPCB_SACKED_RETRANS | 937 TCPCB_LOST), /* All tag bits */ 938 TCPCB_REPAIRED = (1 << 4), /* SKB repaired (no skb_mstamp_ns) */ 939 TCPCB_EVER_RETRANS = (1 << 7), /* Ever retransmitted frame */ 940 TCPCB_RETRANS = (TCPCB_SACKED_RETRANS | TCPCB_EVER_RETRANS | 941 TCPCB_REPAIRED), 942 }; 943 944 /* This is what the send packet queuing engine uses to pass 945 * TCP per-packet control information to the transmission code. 946 * We also store the host-order sequence numbers in here too. 947 * This is 44 bytes if IPV6 is enabled. 948 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 949 */ 950 struct tcp_skb_cb { 951 __u32 seq; /* Starting sequence number */ 952 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 953 union { 954 /* Note : 955 * tcp_gso_segs/size are used in write queue only, 956 * cf tcp_skb_pcount()/tcp_skb_mss() 957 */ 958 struct { 959 u16 tcp_gso_segs; 960 u16 tcp_gso_size; 961 }; 962 }; 963 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 964 965 __u8 sacked; /* State flags for SACK. */ 966 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 967 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */ 968 eor:1, /* Is skb MSG_EOR marked? */ 969 has_rxtstamp:1, /* SKB has a RX timestamp */ 970 unused:5; 971 __u32 ack_seq; /* Sequence number ACK'd */ 972 union { 973 struct { 974 #define TCPCB_DELIVERED_CE_MASK ((1U<<20) - 1) 975 /* There is space for up to 24 bytes */ 976 __u32 is_app_limited:1, /* cwnd not fully used? */ 977 delivered_ce:20, 978 unused:11; 979 /* pkts S/ACKed so far upon tx of skb, incl retrans: */ 980 __u32 delivered; 981 /* start of send pipeline phase */ 982 u64 first_tx_mstamp; 983 /* when we reached the "delivered" count */ 984 u64 delivered_mstamp; 985 } tx; /* only used for outgoing skbs */ 986 union { 987 struct inet_skb_parm h4; 988 #if IS_ENABLED(CONFIG_IPV6) 989 struct inet6_skb_parm h6; 990 #endif 991 } header; /* For incoming skbs */ 992 }; 993 }; 994 995 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 996 997 extern const struct inet_connection_sock_af_ops ipv4_specific; 998 999 #if IS_ENABLED(CONFIG_IPV6) 1000 /* This is the variant of inet6_iif() that must be used by TCP, 1001 * as TCP moves IP6CB into a different location in skb->cb[] 1002 */ 1003 static inline int tcp_v6_iif(const struct sk_buff *skb) 1004 { 1005 return TCP_SKB_CB(skb)->header.h6.iif; 1006 } 1007 1008 static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb) 1009 { 1010 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags); 1011 1012 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif; 1013 } 1014 1015 /* TCP_SKB_CB reference means this can not be used from early demux */ 1016 static inline int tcp_v6_sdif(const struct sk_buff *skb) 1017 { 1018 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 1019 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags)) 1020 return TCP_SKB_CB(skb)->header.h6.iif; 1021 #endif 1022 return 0; 1023 } 1024 1025 extern const struct inet_connection_sock_af_ops ipv6_specific; 1026 1027 INDIRECT_CALLABLE_DECLARE(void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb)); 1028 INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *skb)); 1029 void tcp_v6_early_demux(struct sk_buff *skb); 1030 1031 #endif 1032 1033 /* TCP_SKB_CB reference means this can not be used from early demux */ 1034 static inline int tcp_v4_sdif(struct sk_buff *skb) 1035 { 1036 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 1037 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags)) 1038 return TCP_SKB_CB(skb)->header.h4.iif; 1039 #endif 1040 return 0; 1041 } 1042 1043 /* Due to TSO, an SKB can be composed of multiple actual 1044 * packets. To keep these tracked properly, we use this. 1045 */ 1046 static inline int tcp_skb_pcount(const struct sk_buff *skb) 1047 { 1048 return TCP_SKB_CB(skb)->tcp_gso_segs; 1049 } 1050 1051 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 1052 { 1053 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 1054 } 1055 1056 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 1057 { 1058 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 1059 } 1060 1061 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ 1062 static inline int tcp_skb_mss(const struct sk_buff *skb) 1063 { 1064 return TCP_SKB_CB(skb)->tcp_gso_size; 1065 } 1066 1067 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb) 1068 { 1069 return likely(!TCP_SKB_CB(skb)->eor); 1070 } 1071 1072 static inline bool tcp_skb_can_collapse(const struct sk_buff *to, 1073 const struct sk_buff *from) 1074 { 1075 /* skb_cmp_decrypted() not needed, use tcp_write_collapse_fence() */ 1076 return likely(tcp_skb_can_collapse_to(to) && 1077 mptcp_skb_can_collapse(to, from) && 1078 skb_pure_zcopy_same(to, from) && 1079 skb_frags_readable(to) == skb_frags_readable(from)); 1080 } 1081 1082 static inline bool tcp_skb_can_collapse_rx(const struct sk_buff *to, 1083 const struct sk_buff *from) 1084 { 1085 return likely(mptcp_skb_can_collapse(to, from) && 1086 !skb_cmp_decrypted(to, from)); 1087 } 1088 1089 /* Events passed to congestion control interface */ 1090 enum tcp_ca_event { 1091 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 1092 CA_EVENT_CWND_RESTART, /* congestion window restart */ 1093 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 1094 CA_EVENT_LOSS, /* loss timeout */ 1095 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 1096 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 1097 }; 1098 1099 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 1100 enum tcp_ca_ack_event_flags { 1101 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 1102 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 1103 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 1104 }; 1105 1106 /* 1107 * Interface for adding new TCP congestion control handlers 1108 */ 1109 #define TCP_CA_NAME_MAX 16 1110 #define TCP_CA_MAX 128 1111 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 1112 1113 #define TCP_CA_UNSPEC 0 1114 1115 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 1116 #define TCP_CONG_NON_RESTRICTED 0x1 1117 /* Requires ECN/ECT set on all packets */ 1118 #define TCP_CONG_NEEDS_ECN 0x2 1119 #define TCP_CONG_MASK (TCP_CONG_NON_RESTRICTED | TCP_CONG_NEEDS_ECN) 1120 1121 union tcp_cc_info; 1122 1123 struct ack_sample { 1124 u32 pkts_acked; 1125 s32 rtt_us; 1126 u32 in_flight; 1127 }; 1128 1129 /* A rate sample measures the number of (original/retransmitted) data 1130 * packets delivered "delivered" over an interval of time "interval_us". 1131 * The tcp_rate.c code fills in the rate sample, and congestion 1132 * control modules that define a cong_control function to run at the end 1133 * of ACK processing can optionally chose to consult this sample when 1134 * setting cwnd and pacing rate. 1135 * A sample is invalid if "delivered" or "interval_us" is negative. 1136 */ 1137 struct rate_sample { 1138 u64 prior_mstamp; /* starting timestamp for interval */ 1139 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */ 1140 u32 prior_delivered_ce;/* tp->delivered_ce at "prior_mstamp" */ 1141 s32 delivered; /* number of packets delivered over interval */ 1142 s32 delivered_ce; /* number of packets delivered w/ CE marks*/ 1143 long interval_us; /* time for tp->delivered to incr "delivered" */ 1144 u32 snd_interval_us; /* snd interval for delivered packets */ 1145 u32 rcv_interval_us; /* rcv interval for delivered packets */ 1146 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */ 1147 int losses; /* number of packets marked lost upon ACK */ 1148 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */ 1149 u32 prior_in_flight; /* in flight before this ACK */ 1150 u32 last_end_seq; /* end_seq of most recently ACKed packet */ 1151 bool is_app_limited; /* is sample from packet with bubble in pipe? */ 1152 bool is_retrans; /* is sample from retransmission? */ 1153 bool is_ack_delayed; /* is this (likely) a delayed ACK? */ 1154 }; 1155 1156 struct tcp_congestion_ops { 1157 /* fast path fields are put first to fill one cache line */ 1158 1159 /* return slow start threshold (required) */ 1160 u32 (*ssthresh)(struct sock *sk); 1161 1162 /* do new cwnd calculation (required) */ 1163 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 1164 1165 /* call before changing ca_state (optional) */ 1166 void (*set_state)(struct sock *sk, u8 new_state); 1167 1168 /* call when cwnd event occurs (optional) */ 1169 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 1170 1171 /* call when ack arrives (optional) */ 1172 void (*in_ack_event)(struct sock *sk, u32 flags); 1173 1174 /* hook for packet ack accounting (optional) */ 1175 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample); 1176 1177 /* override sysctl_tcp_min_tso_segs */ 1178 u32 (*min_tso_segs)(struct sock *sk); 1179 1180 /* call when packets are delivered to update cwnd and pacing rate, 1181 * after all the ca_state processing. (optional) 1182 */ 1183 void (*cong_control)(struct sock *sk, u32 ack, int flag, const struct rate_sample *rs); 1184 1185 1186 /* new value of cwnd after loss (required) */ 1187 u32 (*undo_cwnd)(struct sock *sk); 1188 /* returns the multiplier used in tcp_sndbuf_expand (optional) */ 1189 u32 (*sndbuf_expand)(struct sock *sk); 1190 1191 /* control/slow paths put last */ 1192 /* get info for inet_diag (optional) */ 1193 size_t (*get_info)(struct sock *sk, u32 ext, int *attr, 1194 union tcp_cc_info *info); 1195 1196 char name[TCP_CA_NAME_MAX]; 1197 struct module *owner; 1198 struct list_head list; 1199 u32 key; 1200 u32 flags; 1201 1202 /* initialize private data (optional) */ 1203 void (*init)(struct sock *sk); 1204 /* cleanup private data (optional) */ 1205 void (*release)(struct sock *sk); 1206 } ____cacheline_aligned_in_smp; 1207 1208 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 1209 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 1210 int tcp_update_congestion_control(struct tcp_congestion_ops *type, 1211 struct tcp_congestion_ops *old_type); 1212 int tcp_validate_congestion_control(struct tcp_congestion_ops *ca); 1213 1214 void tcp_assign_congestion_control(struct sock *sk); 1215 void tcp_init_congestion_control(struct sock *sk); 1216 void tcp_cleanup_congestion_control(struct sock *sk); 1217 int tcp_set_default_congestion_control(struct net *net, const char *name); 1218 void tcp_get_default_congestion_control(struct net *net, char *name); 1219 void tcp_get_available_congestion_control(char *buf, size_t len); 1220 void tcp_get_allowed_congestion_control(char *buf, size_t len); 1221 int tcp_set_allowed_congestion_control(char *allowed); 1222 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, 1223 bool cap_net_admin); 1224 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); 1225 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); 1226 1227 u32 tcp_reno_ssthresh(struct sock *sk); 1228 u32 tcp_reno_undo_cwnd(struct sock *sk); 1229 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 1230 extern struct tcp_congestion_ops tcp_reno; 1231 1232 struct tcp_congestion_ops *tcp_ca_find(const char *name); 1233 struct tcp_congestion_ops *tcp_ca_find_key(u32 key); 1234 u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca); 1235 #ifdef CONFIG_INET 1236 char *tcp_ca_get_name_by_key(u32 key, char *buffer); 1237 #else 1238 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) 1239 { 1240 return NULL; 1241 } 1242 #endif 1243 1244 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 1245 { 1246 const struct inet_connection_sock *icsk = inet_csk(sk); 1247 1248 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 1249 } 1250 1251 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 1252 { 1253 const struct inet_connection_sock *icsk = inet_csk(sk); 1254 1255 if (icsk->icsk_ca_ops->cwnd_event) 1256 icsk->icsk_ca_ops->cwnd_event(sk, event); 1257 } 1258 1259 /* From tcp_cong.c */ 1260 void tcp_set_ca_state(struct sock *sk, const u8 ca_state); 1261 1262 /* From tcp_rate.c */ 1263 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb); 1264 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb, 1265 struct rate_sample *rs); 1266 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost, 1267 bool is_sack_reneg, struct rate_sample *rs); 1268 void tcp_rate_check_app_limited(struct sock *sk); 1269 1270 static inline bool tcp_skb_sent_after(u64 t1, u64 t2, u32 seq1, u32 seq2) 1271 { 1272 return t1 > t2 || (t1 == t2 && after(seq1, seq2)); 1273 } 1274 1275 /* These functions determine how the current flow behaves in respect of SACK 1276 * handling. SACK is negotiated with the peer, and therefore it can vary 1277 * between different flows. 1278 * 1279 * tcp_is_sack - SACK enabled 1280 * tcp_is_reno - No SACK 1281 */ 1282 static inline int tcp_is_sack(const struct tcp_sock *tp) 1283 { 1284 return likely(tp->rx_opt.sack_ok); 1285 } 1286 1287 static inline bool tcp_is_reno(const struct tcp_sock *tp) 1288 { 1289 return !tcp_is_sack(tp); 1290 } 1291 1292 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 1293 { 1294 return tp->sacked_out + tp->lost_out; 1295 } 1296 1297 /* This determines how many packets are "in the network" to the best 1298 * of our knowledge. In many cases it is conservative, but where 1299 * detailed information is available from the receiver (via SACK 1300 * blocks etc.) we can make more aggressive calculations. 1301 * 1302 * Use this for decisions involving congestion control, use just 1303 * tp->packets_out to determine if the send queue is empty or not. 1304 * 1305 * Read this equation as: 1306 * 1307 * "Packets sent once on transmission queue" MINUS 1308 * "Packets left network, but not honestly ACKed yet" PLUS 1309 * "Packets fast retransmitted" 1310 */ 1311 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 1312 { 1313 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 1314 } 1315 1316 #define TCP_INFINITE_SSTHRESH 0x7fffffff 1317 1318 static inline u32 tcp_snd_cwnd(const struct tcp_sock *tp) 1319 { 1320 return tp->snd_cwnd; 1321 } 1322 1323 static inline void tcp_snd_cwnd_set(struct tcp_sock *tp, u32 val) 1324 { 1325 WARN_ON_ONCE((int)val <= 0); 1326 tp->snd_cwnd = val; 1327 } 1328 1329 static inline bool tcp_in_slow_start(const struct tcp_sock *tp) 1330 { 1331 return tcp_snd_cwnd(tp) < tp->snd_ssthresh; 1332 } 1333 1334 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 1335 { 1336 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 1337 } 1338 1339 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 1340 { 1341 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 1342 (1 << inet_csk(sk)->icsk_ca_state); 1343 } 1344 1345 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 1346 * The exception is cwnd reduction phase, when cwnd is decreasing towards 1347 * ssthresh. 1348 */ 1349 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 1350 { 1351 const struct tcp_sock *tp = tcp_sk(sk); 1352 1353 if (tcp_in_cwnd_reduction(sk)) 1354 return tp->snd_ssthresh; 1355 else 1356 return max(tp->snd_ssthresh, 1357 ((tcp_snd_cwnd(tp) >> 1) + 1358 (tcp_snd_cwnd(tp) >> 2))); 1359 } 1360 1361 /* Use define here intentionally to get WARN_ON location shown at the caller */ 1362 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 1363 1364 void tcp_enter_cwr(struct sock *sk); 1365 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 1366 1367 /* The maximum number of MSS of available cwnd for which TSO defers 1368 * sending if not using sysctl_tcp_tso_win_divisor. 1369 */ 1370 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 1371 { 1372 return 3; 1373 } 1374 1375 /* Returns end sequence number of the receiver's advertised window */ 1376 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 1377 { 1378 return tp->snd_una + tp->snd_wnd; 1379 } 1380 1381 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 1382 * flexible approach. The RFC suggests cwnd should not be raised unless 1383 * it was fully used previously. And that's exactly what we do in 1384 * congestion avoidance mode. But in slow start we allow cwnd to grow 1385 * as long as the application has used half the cwnd. 1386 * Example : 1387 * cwnd is 10 (IW10), but application sends 9 frames. 1388 * We allow cwnd to reach 18 when all frames are ACKed. 1389 * This check is safe because it's as aggressive as slow start which already 1390 * risks 100% overshoot. The advantage is that we discourage application to 1391 * either send more filler packets or data to artificially blow up the cwnd 1392 * usage, and allow application-limited process to probe bw more aggressively. 1393 */ 1394 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1395 { 1396 const struct tcp_sock *tp = tcp_sk(sk); 1397 1398 if (tp->is_cwnd_limited) 1399 return true; 1400 1401 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1402 if (tcp_in_slow_start(tp)) 1403 return tcp_snd_cwnd(tp) < 2 * tp->max_packets_out; 1404 1405 return false; 1406 } 1407 1408 /* BBR congestion control needs pacing. 1409 * Same remark for SO_MAX_PACING_RATE. 1410 * sch_fq packet scheduler is efficiently handling pacing, 1411 * but is not always installed/used. 1412 * Return true if TCP stack should pace packets itself. 1413 */ 1414 static inline bool tcp_needs_internal_pacing(const struct sock *sk) 1415 { 1416 return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED; 1417 } 1418 1419 /* Estimates in how many jiffies next packet for this flow can be sent. 1420 * Scheduling a retransmit timer too early would be silly. 1421 */ 1422 static inline unsigned long tcp_pacing_delay(const struct sock *sk) 1423 { 1424 s64 delay = tcp_sk(sk)->tcp_wstamp_ns - tcp_sk(sk)->tcp_clock_cache; 1425 1426 return delay > 0 ? nsecs_to_jiffies(delay) : 0; 1427 } 1428 1429 static inline void tcp_reset_xmit_timer(struct sock *sk, 1430 const int what, 1431 unsigned long when, 1432 bool pace_delay) 1433 { 1434 if (pace_delay) 1435 when += tcp_pacing_delay(sk); 1436 inet_csk_reset_xmit_timer(sk, what, when, 1437 tcp_rto_max(sk)); 1438 } 1439 1440 /* Something is really bad, we could not queue an additional packet, 1441 * because qdisc is full or receiver sent a 0 window, or we are paced. 1442 * We do not want to add fuel to the fire, or abort too early, 1443 * so make sure the timer we arm now is at least 200ms in the future, 1444 * regardless of current icsk_rto value (as it could be ~2ms) 1445 */ 1446 static inline unsigned long tcp_probe0_base(const struct sock *sk) 1447 { 1448 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); 1449 } 1450 1451 /* Variant of inet_csk_rto_backoff() used for zero window probes */ 1452 static inline unsigned long tcp_probe0_when(const struct sock *sk, 1453 unsigned long max_when) 1454 { 1455 u8 backoff = min_t(u8, ilog2(TCP_RTO_MAX / TCP_RTO_MIN) + 1, 1456 inet_csk(sk)->icsk_backoff); 1457 u64 when = (u64)tcp_probe0_base(sk) << backoff; 1458 1459 return (unsigned long)min_t(u64, when, max_when); 1460 } 1461 1462 static inline void tcp_check_probe_timer(struct sock *sk) 1463 { 1464 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) 1465 tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1466 tcp_probe0_base(sk), true); 1467 } 1468 1469 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1470 { 1471 tp->snd_wl1 = seq; 1472 } 1473 1474 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1475 { 1476 tp->snd_wl1 = seq; 1477 } 1478 1479 /* 1480 * Calculate(/check) TCP checksum 1481 */ 1482 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1483 __be32 daddr, __wsum base) 1484 { 1485 return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_TCP, base); 1486 } 1487 1488 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1489 { 1490 return !skb_csum_unnecessary(skb) && 1491 __skb_checksum_complete(skb); 1492 } 1493 1494 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb, 1495 enum skb_drop_reason *reason); 1496 1497 1498 int tcp_filter(struct sock *sk, struct sk_buff *skb); 1499 void tcp_set_state(struct sock *sk, int state); 1500 void tcp_done(struct sock *sk); 1501 int tcp_abort(struct sock *sk, int err); 1502 1503 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1504 { 1505 rx_opt->dsack = 0; 1506 rx_opt->num_sacks = 0; 1507 } 1508 1509 void tcp_cwnd_restart(struct sock *sk, s32 delta); 1510 1511 static inline void tcp_slow_start_after_idle_check(struct sock *sk) 1512 { 1513 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1514 struct tcp_sock *tp = tcp_sk(sk); 1515 s32 delta; 1516 1517 if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) || 1518 tp->packets_out || ca_ops->cong_control) 1519 return; 1520 delta = tcp_jiffies32 - tp->lsndtime; 1521 if (delta > inet_csk(sk)->icsk_rto) 1522 tcp_cwnd_restart(sk, delta); 1523 } 1524 1525 /* Determine a window scaling and initial window to offer. */ 1526 void tcp_select_initial_window(const struct sock *sk, int __space, 1527 __u32 mss, __u32 *rcv_wnd, 1528 __u32 *window_clamp, int wscale_ok, 1529 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1530 1531 static inline int __tcp_win_from_space(u8 scaling_ratio, int space) 1532 { 1533 s64 scaled_space = (s64)space * scaling_ratio; 1534 1535 return scaled_space >> TCP_RMEM_TO_WIN_SCALE; 1536 } 1537 1538 static inline int tcp_win_from_space(const struct sock *sk, int space) 1539 { 1540 return __tcp_win_from_space(tcp_sk(sk)->scaling_ratio, space); 1541 } 1542 1543 /* inverse of __tcp_win_from_space() */ 1544 static inline int __tcp_space_from_win(u8 scaling_ratio, int win) 1545 { 1546 u64 val = (u64)win << TCP_RMEM_TO_WIN_SCALE; 1547 1548 do_div(val, scaling_ratio); 1549 return val; 1550 } 1551 1552 static inline int tcp_space_from_win(const struct sock *sk, int win) 1553 { 1554 return __tcp_space_from_win(tcp_sk(sk)->scaling_ratio, win); 1555 } 1556 1557 /* Assume a 50% default for skb->len/skb->truesize ratio. 1558 * This may be adjusted later in tcp_measure_rcv_mss(). 1559 */ 1560 #define TCP_DEFAULT_SCALING_RATIO (1 << (TCP_RMEM_TO_WIN_SCALE - 1)) 1561 1562 static inline void tcp_scaling_ratio_init(struct sock *sk) 1563 { 1564 tcp_sk(sk)->scaling_ratio = TCP_DEFAULT_SCALING_RATIO; 1565 } 1566 1567 /* Note: caller must be prepared to deal with negative returns */ 1568 static inline int tcp_space(const struct sock *sk) 1569 { 1570 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf) - 1571 READ_ONCE(sk->sk_backlog.len) - 1572 atomic_read(&sk->sk_rmem_alloc)); 1573 } 1574 1575 static inline int tcp_full_space(const struct sock *sk) 1576 { 1577 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf)); 1578 } 1579 1580 static inline void __tcp_adjust_rcv_ssthresh(struct sock *sk, u32 new_ssthresh) 1581 { 1582 int unused_mem = sk_unused_reserved_mem(sk); 1583 struct tcp_sock *tp = tcp_sk(sk); 1584 1585 tp->rcv_ssthresh = min(tp->rcv_ssthresh, new_ssthresh); 1586 if (unused_mem) 1587 tp->rcv_ssthresh = max_t(u32, tp->rcv_ssthresh, 1588 tcp_win_from_space(sk, unused_mem)); 1589 } 1590 1591 static inline void tcp_adjust_rcv_ssthresh(struct sock *sk) 1592 { 1593 __tcp_adjust_rcv_ssthresh(sk, 4U * tcp_sk(sk)->advmss); 1594 } 1595 1596 void tcp_cleanup_rbuf(struct sock *sk, int copied); 1597 void __tcp_cleanup_rbuf(struct sock *sk, int copied); 1598 1599 1600 /* We provision sk_rcvbuf around 200% of sk_rcvlowat. 1601 * If 87.5 % (7/8) of the space has been consumed, we want to override 1602 * SO_RCVLOWAT constraint, since we are receiving skbs with too small 1603 * len/truesize ratio. 1604 */ 1605 static inline bool tcp_rmem_pressure(const struct sock *sk) 1606 { 1607 int rcvbuf, threshold; 1608 1609 if (tcp_under_memory_pressure(sk)) 1610 return true; 1611 1612 rcvbuf = READ_ONCE(sk->sk_rcvbuf); 1613 threshold = rcvbuf - (rcvbuf >> 3); 1614 1615 return atomic_read(&sk->sk_rmem_alloc) > threshold; 1616 } 1617 1618 static inline bool tcp_epollin_ready(const struct sock *sk, int target) 1619 { 1620 const struct tcp_sock *tp = tcp_sk(sk); 1621 int avail = READ_ONCE(tp->rcv_nxt) - READ_ONCE(tp->copied_seq); 1622 1623 if (avail <= 0) 1624 return false; 1625 1626 return (avail >= target) || tcp_rmem_pressure(sk) || 1627 (tcp_receive_window(tp) <= inet_csk(sk)->icsk_ack.rcv_mss); 1628 } 1629 1630 extern void tcp_openreq_init_rwin(struct request_sock *req, 1631 const struct sock *sk_listener, 1632 const struct dst_entry *dst); 1633 1634 void tcp_enter_memory_pressure(struct sock *sk); 1635 void tcp_leave_memory_pressure(struct sock *sk); 1636 1637 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1638 { 1639 struct net *net = sock_net((struct sock *)tp); 1640 int val; 1641 1642 /* Paired with WRITE_ONCE() in tcp_sock_set_keepintvl() 1643 * and do_tcp_setsockopt(). 1644 */ 1645 val = READ_ONCE(tp->keepalive_intvl); 1646 1647 return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_intvl); 1648 } 1649 1650 static inline int keepalive_time_when(const struct tcp_sock *tp) 1651 { 1652 struct net *net = sock_net((struct sock *)tp); 1653 int val; 1654 1655 /* Paired with WRITE_ONCE() in tcp_sock_set_keepidle_locked() */ 1656 val = READ_ONCE(tp->keepalive_time); 1657 1658 return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_time); 1659 } 1660 1661 static inline int keepalive_probes(const struct tcp_sock *tp) 1662 { 1663 struct net *net = sock_net((struct sock *)tp); 1664 int val; 1665 1666 /* Paired with WRITE_ONCE() in tcp_sock_set_keepcnt() 1667 * and do_tcp_setsockopt(). 1668 */ 1669 val = READ_ONCE(tp->keepalive_probes); 1670 1671 return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_probes); 1672 } 1673 1674 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1675 { 1676 const struct inet_connection_sock *icsk = &tp->inet_conn; 1677 1678 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime, 1679 tcp_jiffies32 - tp->rcv_tstamp); 1680 } 1681 1682 static inline int tcp_fin_time(const struct sock *sk) 1683 { 1684 int fin_timeout = tcp_sk(sk)->linger2 ? : 1685 READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fin_timeout); 1686 const int rto = inet_csk(sk)->icsk_rto; 1687 1688 if (fin_timeout < (rto << 2) - (rto >> 1)) 1689 fin_timeout = (rto << 2) - (rto >> 1); 1690 1691 return fin_timeout; 1692 } 1693 1694 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1695 int paws_win) 1696 { 1697 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1698 return true; 1699 if (unlikely(!time_before32(ktime_get_seconds(), 1700 rx_opt->ts_recent_stamp + TCP_PAWS_WRAP))) 1701 return true; 1702 /* 1703 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1704 * then following tcp messages have valid values. Ignore 0 value, 1705 * or else 'negative' tsval might forbid us to accept their packets. 1706 */ 1707 if (!rx_opt->ts_recent) 1708 return true; 1709 return false; 1710 } 1711 1712 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1713 int rst) 1714 { 1715 if (tcp_paws_check(rx_opt, 0)) 1716 return false; 1717 1718 /* RST segments are not recommended to carry timestamp, 1719 and, if they do, it is recommended to ignore PAWS because 1720 "their cleanup function should take precedence over timestamps." 1721 Certainly, it is mistake. It is necessary to understand the reasons 1722 of this constraint to relax it: if peer reboots, clock may go 1723 out-of-sync and half-open connections will not be reset. 1724 Actually, the problem would be not existing if all 1725 the implementations followed draft about maintaining clock 1726 via reboots. Linux-2.2 DOES NOT! 1727 1728 However, we can relax time bounds for RST segments to MSL. 1729 */ 1730 if (rst && !time_before32(ktime_get_seconds(), 1731 rx_opt->ts_recent_stamp + TCP_PAWS_MSL)) 1732 return false; 1733 return true; 1734 } 1735 1736 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, 1737 int mib_idx, u32 *last_oow_ack_time); 1738 1739 static inline void tcp_mib_init(struct net *net) 1740 { 1741 /* See RFC 2012 */ 1742 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1); 1743 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1744 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1745 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1); 1746 } 1747 1748 /* from STCP */ 1749 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1750 { 1751 tp->lost_skb_hint = NULL; 1752 } 1753 1754 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1755 { 1756 tcp_clear_retrans_hints_partial(tp); 1757 tp->retransmit_skb_hint = NULL; 1758 } 1759 1760 #define tcp_md5_addr tcp_ao_addr 1761 1762 /* - key database */ 1763 struct tcp_md5sig_key { 1764 struct hlist_node node; 1765 u8 keylen; 1766 u8 family; /* AF_INET or AF_INET6 */ 1767 u8 prefixlen; 1768 u8 flags; 1769 union tcp_md5_addr addr; 1770 int l3index; /* set if key added with L3 scope */ 1771 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1772 struct rcu_head rcu; 1773 }; 1774 1775 /* - sock block */ 1776 struct tcp_md5sig_info { 1777 struct hlist_head head; 1778 struct rcu_head rcu; 1779 }; 1780 1781 /* - pseudo header */ 1782 struct tcp4_pseudohdr { 1783 __be32 saddr; 1784 __be32 daddr; 1785 __u8 pad; 1786 __u8 protocol; 1787 __be16 len; 1788 }; 1789 1790 struct tcp6_pseudohdr { 1791 struct in6_addr saddr; 1792 struct in6_addr daddr; 1793 __be32 len; 1794 __be32 protocol; /* including padding */ 1795 }; 1796 1797 union tcp_md5sum_block { 1798 struct tcp4_pseudohdr ip4; 1799 #if IS_ENABLED(CONFIG_IPV6) 1800 struct tcp6_pseudohdr ip6; 1801 #endif 1802 }; 1803 1804 /* 1805 * struct tcp_sigpool - per-CPU pool of ahash_requests 1806 * @scratch: per-CPU temporary area, that can be used between 1807 * tcp_sigpool_start() and tcp_sigpool_end() to perform 1808 * crypto request 1809 * @req: pre-allocated ahash request 1810 */ 1811 struct tcp_sigpool { 1812 void *scratch; 1813 struct ahash_request *req; 1814 }; 1815 1816 int tcp_sigpool_alloc_ahash(const char *alg, size_t scratch_size); 1817 void tcp_sigpool_get(unsigned int id); 1818 void tcp_sigpool_release(unsigned int id); 1819 int tcp_sigpool_hash_skb_data(struct tcp_sigpool *hp, 1820 const struct sk_buff *skb, 1821 unsigned int header_len); 1822 1823 /** 1824 * tcp_sigpool_start - disable bh and start using tcp_sigpool_ahash 1825 * @id: tcp_sigpool that was previously allocated by tcp_sigpool_alloc_ahash() 1826 * @c: returned tcp_sigpool for usage (uninitialized on failure) 1827 * 1828 * Returns: 0 on success, error otherwise. 1829 */ 1830 int tcp_sigpool_start(unsigned int id, struct tcp_sigpool *c); 1831 /** 1832 * tcp_sigpool_end - enable bh and stop using tcp_sigpool 1833 * @c: tcp_sigpool context that was returned by tcp_sigpool_start() 1834 */ 1835 void tcp_sigpool_end(struct tcp_sigpool *c); 1836 size_t tcp_sigpool_algo(unsigned int id, char *buf, size_t buf_len); 1837 /* - functions */ 1838 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1839 const struct sock *sk, const struct sk_buff *skb); 1840 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1841 int family, u8 prefixlen, int l3index, u8 flags, 1842 const u8 *newkey, u8 newkeylen); 1843 int tcp_md5_key_copy(struct sock *sk, const union tcp_md5_addr *addr, 1844 int family, u8 prefixlen, int l3index, 1845 struct tcp_md5sig_key *key); 1846 1847 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1848 int family, u8 prefixlen, int l3index, u8 flags); 1849 void tcp_clear_md5_list(struct sock *sk); 1850 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 1851 const struct sock *addr_sk); 1852 1853 #ifdef CONFIG_TCP_MD5SIG 1854 struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index, 1855 const union tcp_md5_addr *addr, 1856 int family, bool any_l3index); 1857 static inline struct tcp_md5sig_key * 1858 tcp_md5_do_lookup(const struct sock *sk, int l3index, 1859 const union tcp_md5_addr *addr, int family) 1860 { 1861 if (!static_branch_unlikely(&tcp_md5_needed.key)) 1862 return NULL; 1863 return __tcp_md5_do_lookup(sk, l3index, addr, family, false); 1864 } 1865 1866 static inline struct tcp_md5sig_key * 1867 tcp_md5_do_lookup_any_l3index(const struct sock *sk, 1868 const union tcp_md5_addr *addr, int family) 1869 { 1870 if (!static_branch_unlikely(&tcp_md5_needed.key)) 1871 return NULL; 1872 return __tcp_md5_do_lookup(sk, 0, addr, family, true); 1873 } 1874 1875 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1876 #else 1877 static inline struct tcp_md5sig_key * 1878 tcp_md5_do_lookup(const struct sock *sk, int l3index, 1879 const union tcp_md5_addr *addr, int family) 1880 { 1881 return NULL; 1882 } 1883 1884 static inline struct tcp_md5sig_key * 1885 tcp_md5_do_lookup_any_l3index(const struct sock *sk, 1886 const union tcp_md5_addr *addr, int family) 1887 { 1888 return NULL; 1889 } 1890 1891 #define tcp_twsk_md5_key(twsk) NULL 1892 #endif 1893 1894 int tcp_md5_alloc_sigpool(void); 1895 void tcp_md5_release_sigpool(void); 1896 void tcp_md5_add_sigpool(void); 1897 extern int tcp_md5_sigpool_id; 1898 1899 int tcp_md5_hash_key(struct tcp_sigpool *hp, 1900 const struct tcp_md5sig_key *key); 1901 1902 /* From tcp_fastopen.c */ 1903 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1904 struct tcp_fastopen_cookie *cookie); 1905 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1906 struct tcp_fastopen_cookie *cookie, bool syn_lost, 1907 u16 try_exp); 1908 struct tcp_fastopen_request { 1909 /* Fast Open cookie. Size 0 means a cookie request */ 1910 struct tcp_fastopen_cookie cookie; 1911 struct msghdr *data; /* data in MSG_FASTOPEN */ 1912 size_t size; 1913 int copied; /* queued in tcp_connect() */ 1914 struct ubuf_info *uarg; 1915 }; 1916 void tcp_free_fastopen_req(struct tcp_sock *tp); 1917 void tcp_fastopen_destroy_cipher(struct sock *sk); 1918 void tcp_fastopen_ctx_destroy(struct net *net); 1919 int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk, 1920 void *primary_key, void *backup_key); 1921 int tcp_fastopen_get_cipher(struct net *net, struct inet_connection_sock *icsk, 1922 u64 *key); 1923 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb); 1924 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1925 struct request_sock *req, 1926 struct tcp_fastopen_cookie *foc, 1927 const struct dst_entry *dst); 1928 void tcp_fastopen_init_key_once(struct net *net); 1929 bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss, 1930 struct tcp_fastopen_cookie *cookie); 1931 bool tcp_fastopen_defer_connect(struct sock *sk, int *err); 1932 #define TCP_FASTOPEN_KEY_LENGTH sizeof(siphash_key_t) 1933 #define TCP_FASTOPEN_KEY_MAX 2 1934 #define TCP_FASTOPEN_KEY_BUF_LENGTH \ 1935 (TCP_FASTOPEN_KEY_LENGTH * TCP_FASTOPEN_KEY_MAX) 1936 1937 /* Fastopen key context */ 1938 struct tcp_fastopen_context { 1939 siphash_key_t key[TCP_FASTOPEN_KEY_MAX]; 1940 int num; 1941 struct rcu_head rcu; 1942 }; 1943 1944 void tcp_fastopen_active_disable(struct sock *sk); 1945 bool tcp_fastopen_active_should_disable(struct sock *sk); 1946 void tcp_fastopen_active_disable_ofo_check(struct sock *sk); 1947 void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired); 1948 1949 /* Caller needs to wrap with rcu_read_(un)lock() */ 1950 static inline 1951 struct tcp_fastopen_context *tcp_fastopen_get_ctx(const struct sock *sk) 1952 { 1953 struct tcp_fastopen_context *ctx; 1954 1955 ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx); 1956 if (!ctx) 1957 ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx); 1958 return ctx; 1959 } 1960 1961 static inline 1962 bool tcp_fastopen_cookie_match(const struct tcp_fastopen_cookie *foc, 1963 const struct tcp_fastopen_cookie *orig) 1964 { 1965 if (orig->len == TCP_FASTOPEN_COOKIE_SIZE && 1966 orig->len == foc->len && 1967 !memcmp(orig->val, foc->val, foc->len)) 1968 return true; 1969 return false; 1970 } 1971 1972 static inline 1973 int tcp_fastopen_context_len(const struct tcp_fastopen_context *ctx) 1974 { 1975 return ctx->num; 1976 } 1977 1978 /* Latencies incurred by various limits for a sender. They are 1979 * chronograph-like stats that are mutually exclusive. 1980 */ 1981 enum tcp_chrono { 1982 TCP_CHRONO_UNSPEC, 1983 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */ 1984 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */ 1985 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */ 1986 __TCP_CHRONO_MAX, 1987 }; 1988 1989 void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type); 1990 void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type); 1991 1992 /* This helper is needed, because skb->tcp_tsorted_anchor uses 1993 * the same memory storage than skb->destructor/_skb_refdst 1994 */ 1995 static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb) 1996 { 1997 skb->destructor = NULL; 1998 skb->_skb_refdst = 0UL; 1999 } 2000 2001 #define tcp_skb_tsorted_save(skb) { \ 2002 unsigned long _save = skb->_skb_refdst; \ 2003 skb->_skb_refdst = 0UL; 2004 2005 #define tcp_skb_tsorted_restore(skb) \ 2006 skb->_skb_refdst = _save; \ 2007 } 2008 2009 void tcp_write_queue_purge(struct sock *sk); 2010 2011 static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk) 2012 { 2013 return skb_rb_first(&sk->tcp_rtx_queue); 2014 } 2015 2016 static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk) 2017 { 2018 return skb_rb_last(&sk->tcp_rtx_queue); 2019 } 2020 2021 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 2022 { 2023 return skb_peek_tail(&sk->sk_write_queue); 2024 } 2025 2026 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 2027 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 2028 2029 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 2030 { 2031 return skb_peek(&sk->sk_write_queue); 2032 } 2033 2034 static inline bool tcp_skb_is_last(const struct sock *sk, 2035 const struct sk_buff *skb) 2036 { 2037 return skb_queue_is_last(&sk->sk_write_queue, skb); 2038 } 2039 2040 /** 2041 * tcp_write_queue_empty - test if any payload (or FIN) is available in write queue 2042 * @sk: socket 2043 * 2044 * Since the write queue can have a temporary empty skb in it, 2045 * we must not use "return skb_queue_empty(&sk->sk_write_queue)" 2046 */ 2047 static inline bool tcp_write_queue_empty(const struct sock *sk) 2048 { 2049 const struct tcp_sock *tp = tcp_sk(sk); 2050 2051 return tp->write_seq == tp->snd_nxt; 2052 } 2053 2054 static inline bool tcp_rtx_queue_empty(const struct sock *sk) 2055 { 2056 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue); 2057 } 2058 2059 static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk) 2060 { 2061 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk); 2062 } 2063 2064 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 2065 { 2066 __skb_queue_tail(&sk->sk_write_queue, skb); 2067 2068 /* Queue it, remembering where we must start sending. */ 2069 if (sk->sk_write_queue.next == skb) 2070 tcp_chrono_start(sk, TCP_CHRONO_BUSY); 2071 } 2072 2073 /* Insert new before skb on the write queue of sk. */ 2074 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 2075 struct sk_buff *skb, 2076 struct sock *sk) 2077 { 2078 __skb_queue_before(&sk->sk_write_queue, skb, new); 2079 } 2080 2081 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 2082 { 2083 tcp_skb_tsorted_anchor_cleanup(skb); 2084 __skb_unlink(skb, &sk->sk_write_queue); 2085 } 2086 2087 void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb); 2088 2089 static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk) 2090 { 2091 tcp_skb_tsorted_anchor_cleanup(skb); 2092 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue); 2093 } 2094 2095 static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk) 2096 { 2097 list_del(&skb->tcp_tsorted_anchor); 2098 tcp_rtx_queue_unlink(skb, sk); 2099 tcp_wmem_free_skb(sk, skb); 2100 } 2101 2102 static inline void tcp_write_collapse_fence(struct sock *sk) 2103 { 2104 struct sk_buff *skb = tcp_write_queue_tail(sk); 2105 2106 if (skb) 2107 TCP_SKB_CB(skb)->eor = 1; 2108 } 2109 2110 static inline void tcp_push_pending_frames(struct sock *sk) 2111 { 2112 if (tcp_send_head(sk)) { 2113 struct tcp_sock *tp = tcp_sk(sk); 2114 2115 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 2116 } 2117 } 2118 2119 /* Start sequence of the skb just after the highest skb with SACKed 2120 * bit, valid only if sacked_out > 0 or when the caller has ensured 2121 * validity by itself. 2122 */ 2123 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 2124 { 2125 if (!tp->sacked_out) 2126 return tp->snd_una; 2127 2128 if (tp->highest_sack == NULL) 2129 return tp->snd_nxt; 2130 2131 return TCP_SKB_CB(tp->highest_sack)->seq; 2132 } 2133 2134 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 2135 { 2136 tcp_sk(sk)->highest_sack = skb_rb_next(skb); 2137 } 2138 2139 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 2140 { 2141 return tcp_sk(sk)->highest_sack; 2142 } 2143 2144 static inline void tcp_highest_sack_reset(struct sock *sk) 2145 { 2146 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk); 2147 } 2148 2149 /* Called when old skb is about to be deleted and replaced by new skb */ 2150 static inline void tcp_highest_sack_replace(struct sock *sk, 2151 struct sk_buff *old, 2152 struct sk_buff *new) 2153 { 2154 if (old == tcp_highest_sack(sk)) 2155 tcp_sk(sk)->highest_sack = new; 2156 } 2157 2158 /* This helper checks if socket has IP_TRANSPARENT set */ 2159 static inline bool inet_sk_transparent(const struct sock *sk) 2160 { 2161 switch (sk->sk_state) { 2162 case TCP_TIME_WAIT: 2163 return inet_twsk(sk)->tw_transparent; 2164 case TCP_NEW_SYN_RECV: 2165 return inet_rsk(inet_reqsk(sk))->no_srccheck; 2166 } 2167 return inet_test_bit(TRANSPARENT, sk); 2168 } 2169 2170 /* Determines whether this is a thin stream (which may suffer from 2171 * increased latency). Used to trigger latency-reducing mechanisms. 2172 */ 2173 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 2174 { 2175 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 2176 } 2177 2178 /* /proc */ 2179 enum tcp_seq_states { 2180 TCP_SEQ_STATE_LISTENING, 2181 TCP_SEQ_STATE_ESTABLISHED, 2182 }; 2183 2184 void *tcp_seq_start(struct seq_file *seq, loff_t *pos); 2185 void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos); 2186 void tcp_seq_stop(struct seq_file *seq, void *v); 2187 2188 struct tcp_seq_afinfo { 2189 sa_family_t family; 2190 }; 2191 2192 struct tcp_iter_state { 2193 struct seq_net_private p; 2194 enum tcp_seq_states state; 2195 struct sock *syn_wait_sk; 2196 int bucket, offset, sbucket, num; 2197 loff_t last_pos; 2198 }; 2199 2200 extern struct request_sock_ops tcp_request_sock_ops; 2201 extern struct request_sock_ops tcp6_request_sock_ops; 2202 2203 void tcp_v4_destroy_sock(struct sock *sk); 2204 2205 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 2206 netdev_features_t features); 2207 struct tcphdr *tcp_gro_pull_header(struct sk_buff *skb); 2208 struct sk_buff *tcp_gro_lookup(struct list_head *head, struct tcphdr *th); 2209 struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb, 2210 struct tcphdr *th); 2211 INDIRECT_CALLABLE_DECLARE(int tcp4_gro_complete(struct sk_buff *skb, int thoff)); 2212 INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb)); 2213 INDIRECT_CALLABLE_DECLARE(int tcp6_gro_complete(struct sk_buff *skb, int thoff)); 2214 INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb)); 2215 #ifdef CONFIG_INET 2216 void tcp_gro_complete(struct sk_buff *skb); 2217 #else 2218 static inline void tcp_gro_complete(struct sk_buff *skb) { } 2219 #endif 2220 2221 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 2222 2223 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 2224 { 2225 struct net *net = sock_net((struct sock *)tp); 2226 u32 val; 2227 2228 val = READ_ONCE(tp->notsent_lowat); 2229 2230 return val ?: READ_ONCE(net->ipv4.sysctl_tcp_notsent_lowat); 2231 } 2232 2233 bool tcp_stream_memory_free(const struct sock *sk, int wake); 2234 2235 #ifdef CONFIG_PROC_FS 2236 int tcp4_proc_init(void); 2237 void tcp4_proc_exit(void); 2238 #endif 2239 2240 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req); 2241 int tcp_conn_request(struct request_sock_ops *rsk_ops, 2242 const struct tcp_request_sock_ops *af_ops, 2243 struct sock *sk, struct sk_buff *skb); 2244 2245 /* TCP af-specific functions */ 2246 struct tcp_sock_af_ops { 2247 #ifdef CONFIG_TCP_MD5SIG 2248 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk, 2249 const struct sock *addr_sk); 2250 int (*calc_md5_hash)(char *location, 2251 const struct tcp_md5sig_key *md5, 2252 const struct sock *sk, 2253 const struct sk_buff *skb); 2254 int (*md5_parse)(struct sock *sk, 2255 int optname, 2256 sockptr_t optval, 2257 int optlen); 2258 #endif 2259 #ifdef CONFIG_TCP_AO 2260 int (*ao_parse)(struct sock *sk, int optname, sockptr_t optval, int optlen); 2261 struct tcp_ao_key *(*ao_lookup)(const struct sock *sk, 2262 struct sock *addr_sk, 2263 int sndid, int rcvid); 2264 int (*ao_calc_key_sk)(struct tcp_ao_key *mkt, u8 *key, 2265 const struct sock *sk, 2266 __be32 sisn, __be32 disn, bool send); 2267 int (*calc_ao_hash)(char *location, struct tcp_ao_key *ao, 2268 const struct sock *sk, const struct sk_buff *skb, 2269 const u8 *tkey, int hash_offset, u32 sne); 2270 #endif 2271 }; 2272 2273 struct tcp_request_sock_ops { 2274 u16 mss_clamp; 2275 #ifdef CONFIG_TCP_MD5SIG 2276 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk, 2277 const struct sock *addr_sk); 2278 int (*calc_md5_hash) (char *location, 2279 const struct tcp_md5sig_key *md5, 2280 const struct sock *sk, 2281 const struct sk_buff *skb); 2282 #endif 2283 #ifdef CONFIG_TCP_AO 2284 struct tcp_ao_key *(*ao_lookup)(const struct sock *sk, 2285 struct request_sock *req, 2286 int sndid, int rcvid); 2287 int (*ao_calc_key)(struct tcp_ao_key *mkt, u8 *key, struct request_sock *sk); 2288 int (*ao_synack_hash)(char *ao_hash, struct tcp_ao_key *mkt, 2289 struct request_sock *req, const struct sk_buff *skb, 2290 int hash_offset, u32 sne); 2291 #endif 2292 #ifdef CONFIG_SYN_COOKIES 2293 __u32 (*cookie_init_seq)(const struct sk_buff *skb, 2294 __u16 *mss); 2295 #endif 2296 struct dst_entry *(*route_req)(const struct sock *sk, 2297 struct sk_buff *skb, 2298 struct flowi *fl, 2299 struct request_sock *req, 2300 u32 tw_isn); 2301 u32 (*init_seq)(const struct sk_buff *skb); 2302 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb); 2303 int (*send_synack)(const struct sock *sk, struct dst_entry *dst, 2304 struct flowi *fl, struct request_sock *req, 2305 struct tcp_fastopen_cookie *foc, 2306 enum tcp_synack_type synack_type, 2307 struct sk_buff *syn_skb); 2308 }; 2309 2310 extern const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops; 2311 #if IS_ENABLED(CONFIG_IPV6) 2312 extern const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops; 2313 #endif 2314 2315 #ifdef CONFIG_SYN_COOKIES 2316 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 2317 const struct sock *sk, struct sk_buff *skb, 2318 __u16 *mss) 2319 { 2320 tcp_synq_overflow(sk); 2321 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); 2322 return ops->cookie_init_seq(skb, mss); 2323 } 2324 #else 2325 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 2326 const struct sock *sk, struct sk_buff *skb, 2327 __u16 *mss) 2328 { 2329 return 0; 2330 } 2331 #endif 2332 2333 struct tcp_key { 2334 union { 2335 struct { 2336 struct tcp_ao_key *ao_key; 2337 char *traffic_key; 2338 u32 sne; 2339 u8 rcv_next; 2340 }; 2341 struct tcp_md5sig_key *md5_key; 2342 }; 2343 enum { 2344 TCP_KEY_NONE = 0, 2345 TCP_KEY_MD5, 2346 TCP_KEY_AO, 2347 } type; 2348 }; 2349 2350 static inline void tcp_get_current_key(const struct sock *sk, 2351 struct tcp_key *out) 2352 { 2353 #if defined(CONFIG_TCP_AO) || defined(CONFIG_TCP_MD5SIG) 2354 const struct tcp_sock *tp = tcp_sk(sk); 2355 #endif 2356 2357 #ifdef CONFIG_TCP_AO 2358 if (static_branch_unlikely(&tcp_ao_needed.key)) { 2359 struct tcp_ao_info *ao; 2360 2361 ao = rcu_dereference_protected(tp->ao_info, 2362 lockdep_sock_is_held(sk)); 2363 if (ao) { 2364 out->ao_key = READ_ONCE(ao->current_key); 2365 out->type = TCP_KEY_AO; 2366 return; 2367 } 2368 } 2369 #endif 2370 #ifdef CONFIG_TCP_MD5SIG 2371 if (static_branch_unlikely(&tcp_md5_needed.key) && 2372 rcu_access_pointer(tp->md5sig_info)) { 2373 out->md5_key = tp->af_specific->md5_lookup(sk, sk); 2374 if (out->md5_key) { 2375 out->type = TCP_KEY_MD5; 2376 return; 2377 } 2378 } 2379 #endif 2380 out->type = TCP_KEY_NONE; 2381 } 2382 2383 static inline bool tcp_key_is_md5(const struct tcp_key *key) 2384 { 2385 if (static_branch_tcp_md5()) 2386 return key->type == TCP_KEY_MD5; 2387 return false; 2388 } 2389 2390 static inline bool tcp_key_is_ao(const struct tcp_key *key) 2391 { 2392 if (static_branch_tcp_ao()) 2393 return key->type == TCP_KEY_AO; 2394 return false; 2395 } 2396 2397 int tcpv4_offload_init(void); 2398 2399 void tcp_v4_init(void); 2400 void tcp_init(void); 2401 2402 /* tcp_recovery.c */ 2403 void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb); 2404 void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced); 2405 extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb, 2406 u32 reo_wnd); 2407 extern bool tcp_rack_mark_lost(struct sock *sk); 2408 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq, 2409 u64 xmit_time); 2410 extern void tcp_rack_reo_timeout(struct sock *sk); 2411 extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs); 2412 2413 /* tcp_plb.c */ 2414 2415 /* 2416 * Scaling factor for fractions in PLB. For example, tcp_plb_update_state 2417 * expects cong_ratio which represents fraction of traffic that experienced 2418 * congestion over a single RTT. In order to avoid floating point operations, 2419 * this fraction should be mapped to (1 << TCP_PLB_SCALE) and passed in. 2420 */ 2421 #define TCP_PLB_SCALE 8 2422 2423 /* State for PLB (Protective Load Balancing) for a single TCP connection. */ 2424 struct tcp_plb_state { 2425 u8 consec_cong_rounds:5, /* consecutive congested rounds */ 2426 unused:3; 2427 u32 pause_until; /* jiffies32 when PLB can resume rerouting */ 2428 }; 2429 2430 static inline void tcp_plb_init(const struct sock *sk, 2431 struct tcp_plb_state *plb) 2432 { 2433 plb->consec_cong_rounds = 0; 2434 plb->pause_until = 0; 2435 } 2436 void tcp_plb_update_state(const struct sock *sk, struct tcp_plb_state *plb, 2437 const int cong_ratio); 2438 void tcp_plb_check_rehash(struct sock *sk, struct tcp_plb_state *plb); 2439 void tcp_plb_update_state_upon_rto(struct sock *sk, struct tcp_plb_state *plb); 2440 2441 static inline void tcp_warn_once(const struct sock *sk, bool cond, const char *str) 2442 { 2443 WARN_ONCE(cond, 2444 "%scwn:%u out:%u sacked:%u lost:%u retrans:%u tlp_high_seq:%u sk_state:%u ca_state:%u advmss:%u mss_cache:%u pmtu:%u\n", 2445 str, 2446 tcp_snd_cwnd(tcp_sk(sk)), 2447 tcp_sk(sk)->packets_out, tcp_sk(sk)->sacked_out, 2448 tcp_sk(sk)->lost_out, tcp_sk(sk)->retrans_out, 2449 tcp_sk(sk)->tlp_high_seq, sk->sk_state, 2450 inet_csk(sk)->icsk_ca_state, 2451 tcp_sk(sk)->advmss, tcp_sk(sk)->mss_cache, 2452 inet_csk(sk)->icsk_pmtu_cookie); 2453 } 2454 2455 /* At how many usecs into the future should the RTO fire? */ 2456 static inline s64 tcp_rto_delta_us(const struct sock *sk) 2457 { 2458 const struct sk_buff *skb = tcp_rtx_queue_head(sk); 2459 u32 rto = inet_csk(sk)->icsk_rto; 2460 2461 if (likely(skb)) { 2462 u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + jiffies_to_usecs(rto); 2463 2464 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp; 2465 } else { 2466 tcp_warn_once(sk, 1, "rtx queue empty: "); 2467 return jiffies_to_usecs(rto); 2468 } 2469 2470 } 2471 2472 /* 2473 * Save and compile IPv4 options, return a pointer to it 2474 */ 2475 static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net, 2476 struct sk_buff *skb) 2477 { 2478 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; 2479 struct ip_options_rcu *dopt = NULL; 2480 2481 if (opt->optlen) { 2482 int opt_size = sizeof(*dopt) + opt->optlen; 2483 2484 dopt = kmalloc(opt_size, GFP_ATOMIC); 2485 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) { 2486 kfree(dopt); 2487 dopt = NULL; 2488 } 2489 } 2490 return dopt; 2491 } 2492 2493 /* locally generated TCP pure ACKs have skb->truesize == 2 2494 * (check tcp_send_ack() in net/ipv4/tcp_output.c ) 2495 * This is much faster than dissecting the packet to find out. 2496 * (Think of GRE encapsulations, IPv4, IPv6, ...) 2497 */ 2498 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb) 2499 { 2500 return skb->truesize == 2; 2501 } 2502 2503 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb) 2504 { 2505 skb->truesize = 2; 2506 } 2507 2508 static inline int tcp_inq(struct sock *sk) 2509 { 2510 struct tcp_sock *tp = tcp_sk(sk); 2511 int answ; 2512 2513 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { 2514 answ = 0; 2515 } else if (sock_flag(sk, SOCK_URGINLINE) || 2516 !tp->urg_data || 2517 before(tp->urg_seq, tp->copied_seq) || 2518 !before(tp->urg_seq, tp->rcv_nxt)) { 2519 2520 answ = tp->rcv_nxt - tp->copied_seq; 2521 2522 /* Subtract 1, if FIN was received */ 2523 if (answ && sock_flag(sk, SOCK_DONE)) 2524 answ--; 2525 } else { 2526 answ = tp->urg_seq - tp->copied_seq; 2527 } 2528 2529 return answ; 2530 } 2531 2532 int tcp_peek_len(struct socket *sock); 2533 2534 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb) 2535 { 2536 u16 segs_in; 2537 2538 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs); 2539 2540 /* We update these fields while other threads might 2541 * read them from tcp_get_info() 2542 */ 2543 WRITE_ONCE(tp->segs_in, tp->segs_in + segs_in); 2544 if (skb->len > tcp_hdrlen(skb)) 2545 WRITE_ONCE(tp->data_segs_in, tp->data_segs_in + segs_in); 2546 } 2547 2548 /* 2549 * TCP listen path runs lockless. 2550 * We forced "struct sock" to be const qualified to make sure 2551 * we don't modify one of its field by mistake. 2552 * Here, we increment sk_drops which is an atomic_t, so we can safely 2553 * make sock writable again. 2554 */ 2555 static inline void tcp_listendrop(const struct sock *sk) 2556 { 2557 atomic_inc(&((struct sock *)sk)->sk_drops); 2558 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 2559 } 2560 2561 enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer); 2562 2563 /* 2564 * Interface for adding Upper Level Protocols over TCP 2565 */ 2566 2567 #define TCP_ULP_NAME_MAX 16 2568 #define TCP_ULP_MAX 128 2569 #define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX) 2570 2571 struct tcp_ulp_ops { 2572 struct list_head list; 2573 2574 /* initialize ulp */ 2575 int (*init)(struct sock *sk); 2576 /* update ulp */ 2577 void (*update)(struct sock *sk, struct proto *p, 2578 void (*write_space)(struct sock *sk)); 2579 /* cleanup ulp */ 2580 void (*release)(struct sock *sk); 2581 /* diagnostic */ 2582 int (*get_info)(struct sock *sk, struct sk_buff *skb); 2583 size_t (*get_info_size)(const struct sock *sk); 2584 /* clone ulp */ 2585 void (*clone)(const struct request_sock *req, struct sock *newsk, 2586 const gfp_t priority); 2587 2588 char name[TCP_ULP_NAME_MAX]; 2589 struct module *owner; 2590 }; 2591 int tcp_register_ulp(struct tcp_ulp_ops *type); 2592 void tcp_unregister_ulp(struct tcp_ulp_ops *type); 2593 int tcp_set_ulp(struct sock *sk, const char *name); 2594 void tcp_get_available_ulp(char *buf, size_t len); 2595 void tcp_cleanup_ulp(struct sock *sk); 2596 void tcp_update_ulp(struct sock *sk, struct proto *p, 2597 void (*write_space)(struct sock *sk)); 2598 2599 #define MODULE_ALIAS_TCP_ULP(name) \ 2600 __MODULE_INFO(alias, alias_userspace, name); \ 2601 __MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name) 2602 2603 #ifdef CONFIG_NET_SOCK_MSG 2604 struct sk_msg; 2605 struct sk_psock; 2606 2607 #ifdef CONFIG_BPF_SYSCALL 2608 int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore); 2609 void tcp_bpf_clone(const struct sock *sk, struct sock *newsk); 2610 #endif /* CONFIG_BPF_SYSCALL */ 2611 2612 #ifdef CONFIG_INET 2613 void tcp_eat_skb(struct sock *sk, struct sk_buff *skb); 2614 #else 2615 static inline void tcp_eat_skb(struct sock *sk, struct sk_buff *skb) 2616 { 2617 } 2618 #endif 2619 2620 int tcp_bpf_sendmsg_redir(struct sock *sk, bool ingress, 2621 struct sk_msg *msg, u32 bytes, int flags); 2622 #endif /* CONFIG_NET_SOCK_MSG */ 2623 2624 #if !defined(CONFIG_BPF_SYSCALL) || !defined(CONFIG_NET_SOCK_MSG) 2625 static inline void tcp_bpf_clone(const struct sock *sk, struct sock *newsk) 2626 { 2627 } 2628 #endif 2629 2630 #ifdef CONFIG_CGROUP_BPF 2631 static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops, 2632 struct sk_buff *skb, 2633 unsigned int end_offset) 2634 { 2635 skops->skb = skb; 2636 skops->skb_data_end = skb->data + end_offset; 2637 } 2638 #else 2639 static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops, 2640 struct sk_buff *skb, 2641 unsigned int end_offset) 2642 { 2643 } 2644 #endif 2645 2646 /* Call BPF_SOCK_OPS program that returns an int. If the return value 2647 * is < 0, then the BPF op failed (for example if the loaded BPF 2648 * program does not support the chosen operation or there is no BPF 2649 * program loaded). 2650 */ 2651 #ifdef CONFIG_BPF 2652 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args) 2653 { 2654 struct bpf_sock_ops_kern sock_ops; 2655 int ret; 2656 2657 memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); 2658 if (sk_fullsock(sk)) { 2659 sock_ops.is_fullsock = 1; 2660 sock_owned_by_me(sk); 2661 } 2662 2663 sock_ops.sk = sk; 2664 sock_ops.op = op; 2665 if (nargs > 0) 2666 memcpy(sock_ops.args, args, nargs * sizeof(*args)); 2667 2668 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops); 2669 if (ret == 0) 2670 ret = sock_ops.reply; 2671 else 2672 ret = -1; 2673 return ret; 2674 } 2675 2676 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2) 2677 { 2678 u32 args[2] = {arg1, arg2}; 2679 2680 return tcp_call_bpf(sk, op, 2, args); 2681 } 2682 2683 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2, 2684 u32 arg3) 2685 { 2686 u32 args[3] = {arg1, arg2, arg3}; 2687 2688 return tcp_call_bpf(sk, op, 3, args); 2689 } 2690 2691 #else 2692 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args) 2693 { 2694 return -EPERM; 2695 } 2696 2697 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2) 2698 { 2699 return -EPERM; 2700 } 2701 2702 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2, 2703 u32 arg3) 2704 { 2705 return -EPERM; 2706 } 2707 2708 #endif 2709 2710 static inline u32 tcp_timeout_init(struct sock *sk) 2711 { 2712 int timeout; 2713 2714 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL); 2715 2716 if (timeout <= 0) 2717 timeout = TCP_TIMEOUT_INIT; 2718 return min_t(int, timeout, TCP_RTO_MAX); 2719 } 2720 2721 static inline u32 tcp_rwnd_init_bpf(struct sock *sk) 2722 { 2723 int rwnd; 2724 2725 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL); 2726 2727 if (rwnd < 0) 2728 rwnd = 0; 2729 return rwnd; 2730 } 2731 2732 static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk) 2733 { 2734 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1); 2735 } 2736 2737 static inline void tcp_bpf_rtt(struct sock *sk, long mrtt, u32 srtt) 2738 { 2739 if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_RTT_CB_FLAG)) 2740 tcp_call_bpf_2arg(sk, BPF_SOCK_OPS_RTT_CB, mrtt, srtt); 2741 } 2742 2743 #if IS_ENABLED(CONFIG_SMC) 2744 extern struct static_key_false tcp_have_smc; 2745 #endif 2746 2747 #if IS_ENABLED(CONFIG_TLS_DEVICE) 2748 void clean_acked_data_enable(struct inet_connection_sock *icsk, 2749 void (*cad)(struct sock *sk, u32 ack_seq)); 2750 void clean_acked_data_disable(struct inet_connection_sock *icsk); 2751 void clean_acked_data_flush(void); 2752 #endif 2753 2754 DECLARE_STATIC_KEY_FALSE(tcp_tx_delay_enabled); 2755 static inline void tcp_add_tx_delay(struct sk_buff *skb, 2756 const struct tcp_sock *tp) 2757 { 2758 if (static_branch_unlikely(&tcp_tx_delay_enabled)) 2759 skb->skb_mstamp_ns += (u64)tp->tcp_tx_delay * NSEC_PER_USEC; 2760 } 2761 2762 /* Compute Earliest Departure Time for some control packets 2763 * like ACK or RST for TIME_WAIT or non ESTABLISHED sockets. 2764 */ 2765 static inline u64 tcp_transmit_time(const struct sock *sk) 2766 { 2767 if (static_branch_unlikely(&tcp_tx_delay_enabled)) { 2768 u32 delay = (sk->sk_state == TCP_TIME_WAIT) ? 2769 tcp_twsk(sk)->tw_tx_delay : tcp_sk(sk)->tcp_tx_delay; 2770 2771 return tcp_clock_ns() + (u64)delay * NSEC_PER_USEC; 2772 } 2773 return 0; 2774 } 2775 2776 static inline int tcp_parse_auth_options(const struct tcphdr *th, 2777 const u8 **md5_hash, const struct tcp_ao_hdr **aoh) 2778 { 2779 const u8 *md5_tmp, *ao_tmp; 2780 int ret; 2781 2782 ret = tcp_do_parse_auth_options(th, &md5_tmp, &ao_tmp); 2783 if (ret) 2784 return ret; 2785 2786 if (md5_hash) 2787 *md5_hash = md5_tmp; 2788 2789 if (aoh) { 2790 if (!ao_tmp) 2791 *aoh = NULL; 2792 else 2793 *aoh = (struct tcp_ao_hdr *)(ao_tmp - 2); 2794 } 2795 2796 return 0; 2797 } 2798 2799 static inline bool tcp_ao_required(struct sock *sk, const void *saddr, 2800 int family, int l3index, bool stat_inc) 2801 { 2802 #ifdef CONFIG_TCP_AO 2803 struct tcp_ao_info *ao_info; 2804 struct tcp_ao_key *ao_key; 2805 2806 if (!static_branch_unlikely(&tcp_ao_needed.key)) 2807 return false; 2808 2809 ao_info = rcu_dereference_check(tcp_sk(sk)->ao_info, 2810 lockdep_sock_is_held(sk)); 2811 if (!ao_info) 2812 return false; 2813 2814 ao_key = tcp_ao_do_lookup(sk, l3index, saddr, family, -1, -1); 2815 if (ao_info->ao_required || ao_key) { 2816 if (stat_inc) { 2817 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOREQUIRED); 2818 atomic64_inc(&ao_info->counters.ao_required); 2819 } 2820 return true; 2821 } 2822 #endif 2823 return false; 2824 } 2825 2826 enum skb_drop_reason tcp_inbound_hash(struct sock *sk, 2827 const struct request_sock *req, const struct sk_buff *skb, 2828 const void *saddr, const void *daddr, 2829 int family, int dif, int sdif); 2830 2831 #endif /* _TCP_H */ 2832