include/net/tcp.h

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This source file includes following definitions.
tcp_under_memory_pressure
before
between
tcp_out_of_memory
tcp_too_many_orphans
tcp_dec_quickack_mode
tcp_synq_overflow
tcp_synq_no_recent_overflow
tcp_cookie_time
tcp_clear_xmit_timers
tcp_bound_to_half_wnd
tcp_bound_rto
__tcp_set_rto
__tcp_fast_path_on
tcp_fast_path_on
tcp_fast_path_check
tcp_rto_min
tcp_rto_min_us
tcp_ca_dst_locked
tcp_min_rtt
tcp_receive_window
tcp_clock_ns
tcp_clock_us
tcp_time_stamp
tcp_time_stamp_raw
tcp_stamp_us_delta
tcp_skb_timestamp
tcp_skb_timestamp_us
bpf_compute_data_end_sk_skb
tcp_skb_bpf_ingress
tcp_skb_bpf_redirect_fetch
tcp_skb_bpf_redirect_clear
tcp_v6_iif
tcp_v6_iif_l3_slave
tcp_v6_sdif
inet_exact_dif_match
tcp_v4_sdif
tcp_skb_pcount
tcp_skb_pcount_set
tcp_skb_pcount_add
tcp_skb_mss
tcp_skb_can_collapse_to
tcp_ca_get_name_by_key
tcp_ca_needs_ecn
tcp_set_ca_state
tcp_ca_event
tcp_is_sack
tcp_is_reno
tcp_left_out
tcp_packets_in_flight
tcp_in_slow_start
tcp_in_initial_slowstart
tcp_in_cwnd_reduction
tcp_current_ssthresh
tcp_max_tso_deferred_mss
tcp_wnd_end
tcp_is_cwnd_limited
tcp_needs_internal_pacing
tcp_pacing_delay
tcp_reset_xmit_timer
tcp_probe0_base
tcp_probe0_when
tcp_check_probe_timer
tcp_init_wl
tcp_update_wl
tcp_v4_check
tcp_checksum_complete
tcp_sack_reset
tcp_slow_start_after_idle_check
tcp_win_from_space
tcp_space
tcp_full_space
tcp_rmem_pressure
keepalive_intvl_when
keepalive_time_when
keepalive_probes
keepalive_time_elapsed
tcp_fin_time
tcp_paws_check
tcp_paws_reject
tcp_mib_init
tcp_clear_retrans_hints_partial
tcp_clear_all_retrans_hints
tcp_md5_do_lookup
tcp_md5_do_lookup
tcp_put_md5sig_pool
tcp_fastopen_get_ctx
tcp_fastopen_cookie_match
tcp_fastopen_context_len
tcp_skb_tsorted_anchor_cleanup
tcp_rtx_queue_head
tcp_rtx_queue_tail
tcp_write_queue_head
tcp_write_queue_tail
tcp_send_head
tcp_skb_is_last
tcp_write_queue_empty
tcp_rtx_queue_empty
tcp_rtx_and_write_queues_empty
tcp_add_write_queue_tail
tcp_insert_write_queue_before
tcp_unlink_write_queue
tcp_rtx_queue_unlink
tcp_rtx_queue_unlink_and_free
tcp_push_pending_frames
tcp_highest_sack_seq
tcp_advance_highest_sack
tcp_highest_sack
tcp_highest_sack_reset
tcp_highest_sack_replace
inet_sk_transparent
tcp_stream_is_thin
tcp_notsent_lowat
tcp_stream_memory_free
cookie_init_sequence
cookie_init_sequence
tcp_rto_delta_us
tcp_v4_save_options
skb_is_tcp_pure_ack
skb_set_tcp_pure_ack
tcp_inq
tcp_segs_in
tcp_listendrop
tcp_call_bpf
tcp_call_bpf_2arg
tcp_call_bpf_3arg
tcp_call_bpf
tcp_call_bpf_2arg
tcp_call_bpf_3arg
tcp_timeout_init
tcp_rwnd_init_bpf
tcp_bpf_ca_needs_ecn
tcp_bpf_rtt
tcp_add_tx_delay
tcp_transmit_time
   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/cryptohash.h>
  27 #include <linux/kref.h>
  28 #include <linux/ktime.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/inet_ecn.h>
  41 #include <net/dst.h>
  42 
  43 #include <linux/seq_file.h>
  44 #include <linux/memcontrol.h>
  45 #include <linux/bpf-cgroup.h>
  46 #include <linux/siphash.h>
  47 
  48 extern struct inet_hashinfo tcp_hashinfo;
  49 
  50 extern struct percpu_counter tcp_orphan_count;
  51 void tcp_time_wait(struct sock *sk, int state, int timeo);
  52 
  53 #define MAX_TCP_HEADER  L1_CACHE_ALIGN(128 + MAX_HEADER)
  54 #define MAX_TCP_OPTION_SPACE 40
  55 #define TCP_MIN_SND_MSS         48
  56 #define TCP_MIN_GSO_SIZE        (TCP_MIN_SND_MSS - MAX_TCP_OPTION_SPACE)
  57 
  58 /*
  59  * Never offer a window over 32767 without using window scaling. Some
  60  * poor stacks do signed 16bit maths!
  61  */
  62 #define MAX_TCP_WINDOW          32767U
  63 
  64 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
  65 #define TCP_MIN_MSS             88U
  66 
  67 /* The initial MTU to use for probing */
  68 #define TCP_BASE_MSS            1024
  69 
  70 /* probing interval, default to 10 minutes as per RFC4821 */
  71 #define TCP_PROBE_INTERVAL      600
  72 
  73 /* Specify interval when tcp mtu probing will stop */
  74 #define TCP_PROBE_THRESHOLD     8
  75 
  76 /* After receiving this amount of duplicate ACKs fast retransmit starts. */
  77 #define TCP_FASTRETRANS_THRESH 3
  78 
  79 /* Maximal number of ACKs sent quickly to accelerate slow-start. */
  80 #define TCP_MAX_QUICKACKS       16U
  81 
  82 /* Maximal number of window scale according to RFC1323 */
  83 #define TCP_MAX_WSCALE          14U
  84 
  85 /* urg_data states */
  86 #define TCP_URG_VALID   0x0100
  87 #define TCP_URG_NOTYET  0x0200
  88 #define TCP_URG_READ    0x0400
  89 
  90 #define TCP_RETR1       3       /*
  91                                  * This is how many retries it does before it
  92                                  * tries to figure out if the gateway is
  93                                  * down. Minimal RFC value is 3; it corresponds
  94                                  * to ~3sec-8min depending on RTO.
  95                                  */
  96 
  97 #define TCP_RETR2       15      /*
  98                                  * This should take at least
  99                                  * 90 minutes to time out.
 100                                  * RFC1122 says that the limit is 100 sec.
 101                                  * 15 is ~13-30min depending on RTO.
 102                                  */
 103 
 104 #define TCP_SYN_RETRIES  6      /* This is how many retries are done
 105                                  * when active opening a connection.
 106                                  * RFC1122 says the minimum retry MUST
 107                                  * be at least 180secs.  Nevertheless
 108                                  * this value is corresponding to
 109                                  * 63secs of retransmission with the
 110                                  * current initial RTO.
 111                                  */
 112 
 113 #define TCP_SYNACK_RETRIES 5    /* This is how may retries are done
 114                                  * when passive opening a connection.
 115                                  * This is corresponding to 31secs of
 116                                  * retransmission with the current
 117                                  * initial RTO.
 118                                  */
 119 
 120 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
 121                                   * state, about 60 seconds     */
 122 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
 123                                  /* BSD style FIN_WAIT2 deadlock breaker.
 124                                   * It used to be 3min, new value is 60sec,
 125                                   * to combine FIN-WAIT-2 timeout with
 126                                   * TIME-WAIT timer.
 127                                   */
 128 
 129 #define TCP_DELACK_MAX  ((unsigned)(HZ/5))      /* maximal time to delay before sending an ACK */
 130 #if HZ >= 100
 131 #define TCP_DELACK_MIN  ((unsigned)(HZ/25))     /* minimal time to delay before sending an ACK */
 132 #define TCP_ATO_MIN     ((unsigned)(HZ/25))
 133 #else
 134 #define TCP_DELACK_MIN  4U
 135 #define TCP_ATO_MIN     4U
 136 #endif
 137 #define TCP_RTO_MAX     ((unsigned)(120*HZ))
 138 #define TCP_RTO_MIN     ((unsigned)(HZ/5))
 139 #define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */
 140 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ))     /* RFC6298 2.1 initial RTO value        */
 141 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
 142                                                  * used as a fallback RTO for the
 143                                                  * initial data transmission if no
 144                                                  * valid RTT sample has been acquired,
 145                                                  * most likely due to retrans in 3WHS.
 146                                                  */
 147 
 148 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
 149                                                          * for local resources.
 150                                                          */
 151 #define TCP_KEEPALIVE_TIME      (120*60*HZ)     /* two hours */
 152 #define TCP_KEEPALIVE_PROBES    9               /* Max of 9 keepalive probes    */
 153 #define TCP_KEEPALIVE_INTVL     (75*HZ)
 154 
 155 #define MAX_TCP_KEEPIDLE        32767
 156 #define MAX_TCP_KEEPINTVL       32767
 157 #define MAX_TCP_KEEPCNT         127
 158 #define MAX_TCP_SYNCNT          127
 159 
 160 #define TCP_SYNQ_INTERVAL       (HZ/5)  /* Period of SYNACK timer */
 161 
 162 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
 163 #define TCP_PAWS_MSL    60              /* Per-host timestamps are invalidated
 164                                          * after this time. It should be equal
 165                                          * (or greater than) TCP_TIMEWAIT_LEN
 166                                          * to provide reliability equal to one
 167                                          * provided by timewait state.
 168                                          */
 169 #define TCP_PAWS_WINDOW 1               /* Replay window for per-host
 170                                          * timestamps. It must be less than
 171                                          * minimal timewait lifetime.
 172                                          */
 173 /*
 174  *      TCP option
 175  */
 176 
 177 #define TCPOPT_NOP              1       /* Padding */
 178 #define TCPOPT_EOL              0       /* End of options */
 179 #define TCPOPT_MSS              2       /* Segment size negotiating */
 180 #define TCPOPT_WINDOW           3       /* Window scaling */
 181 #define TCPOPT_SACK_PERM        4       /* SACK Permitted */
 182 #define TCPOPT_SACK             5       /* SACK Block */
 183 #define TCPOPT_TIMESTAMP        8       /* Better RTT estimations/PAWS */
 184 #define TCPOPT_MD5SIG           19      /* MD5 Signature (RFC2385) */
 185 #define TCPOPT_FASTOPEN         34      /* Fast open (RFC7413) */
 186 #define TCPOPT_EXP              254     /* Experimental */
 187 /* Magic number to be after the option value for sharing TCP
 188  * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
 189  */
 190 #define TCPOPT_FASTOPEN_MAGIC   0xF989
 191 #define TCPOPT_SMC_MAGIC        0xE2D4C3D9
 192 
 193 /*
 194  *     TCP option lengths
 195  */
 196 
 197 #define TCPOLEN_MSS            4
 198 #define TCPOLEN_WINDOW         3
 199 #define TCPOLEN_SACK_PERM      2
 200 #define TCPOLEN_TIMESTAMP      10
 201 #define TCPOLEN_MD5SIG         18
 202 #define TCPOLEN_FASTOPEN_BASE  2
 203 #define TCPOLEN_EXP_FASTOPEN_BASE  4
 204 #define TCPOLEN_EXP_SMC_BASE   6
 205 
 206 /* But this is what stacks really send out. */
 207 #define TCPOLEN_TSTAMP_ALIGNED          12
 208 #define TCPOLEN_WSCALE_ALIGNED          4
 209 #define TCPOLEN_SACKPERM_ALIGNED        4
 210 #define TCPOLEN_SACK_BASE               2
 211 #define TCPOLEN_SACK_BASE_ALIGNED       4
 212 #define TCPOLEN_SACK_PERBLOCK           8
 213 #define TCPOLEN_MD5SIG_ALIGNED          20
 214 #define TCPOLEN_MSS_ALIGNED             4
 215 #define TCPOLEN_EXP_SMC_BASE_ALIGNED    8
 216 
 217 /* Flags in tp->nonagle */
 218 #define TCP_NAGLE_OFF           1       /* Nagle's algo is disabled */
 219 #define TCP_NAGLE_CORK          2       /* Socket is corked         */
 220 #define TCP_NAGLE_PUSH          4       /* Cork is overridden for already queued data */
 221 
 222 /* TCP thin-stream limits */
 223 #define TCP_THIN_LINEAR_RETRIES 6       /* After 6 linear retries, do exp. backoff */
 224 
 225 /* TCP initial congestion window as per rfc6928 */
 226 #define TCP_INIT_CWND           10
 227 
 228 /* Bit Flags for sysctl_tcp_fastopen */
 229 #define TFO_CLIENT_ENABLE       1
 230 #define TFO_SERVER_ENABLE       2
 231 #define TFO_CLIENT_NO_COOKIE    4       /* Data in SYN w/o cookie option */
 232 
 233 /* Accept SYN data w/o any cookie option */
 234 #define TFO_SERVER_COOKIE_NOT_REQD      0x200
 235 
 236 /* Force enable TFO on all listeners, i.e., not requiring the
 237  * TCP_FASTOPEN socket option.
 238  */
 239 #define TFO_SERVER_WO_SOCKOPT1  0x400
 240 
 241 
 242 /* sysctl variables for tcp */
 243 extern int sysctl_tcp_max_orphans;
 244 extern long sysctl_tcp_mem[3];
 245 
 246 #define TCP_RACK_LOSS_DETECTION  0x1 /* Use RACK to detect losses */
 247 #define TCP_RACK_STATIC_REO_WND  0x2 /* Use static RACK reo wnd */
 248 #define TCP_RACK_NO_DUPTHRESH    0x4 /* Do not use DUPACK threshold in RACK */
 249 
 250 extern atomic_long_t tcp_memory_allocated;
 251 extern struct percpu_counter tcp_sockets_allocated;
 252 extern unsigned long tcp_memory_pressure;
 253 
 254 /* optimized version of sk_under_memory_pressure() for TCP sockets */
 255 static inline bool tcp_under_memory_pressure(const struct sock *sk)
 256 {
 257         if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
 258             mem_cgroup_under_socket_pressure(sk->sk_memcg))
 259                 return true;
 260 
 261         return READ_ONCE(tcp_memory_pressure);
 262 }
 263 /*
 264  * The next routines deal with comparing 32 bit unsigned ints
 265  * and worry about wraparound (automatic with unsigned arithmetic).
 266  */
 267 
 268 static inline bool before(__u32 seq1, __u32 seq2)
 269 {
 270         return (__s32)(seq1-seq2) < 0;
 271 }
 272 #define after(seq2, seq1)       before(seq1, seq2)
 273 
 274 /* is s2<=s1<=s3 ? */
 275 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
 276 {
 277         return seq3 - seq2 >= seq1 - seq2;
 278 }
 279 
 280 static inline bool tcp_out_of_memory(struct sock *sk)
 281 {
 282         if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
 283             sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
 284                 return true;
 285         return false;
 286 }
 287 
 288 void sk_forced_mem_schedule(struct sock *sk, int size);
 289 
 290 static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
 291 {
 292         struct percpu_counter *ocp = sk->sk_prot->orphan_count;
 293         int orphans = percpu_counter_read_positive(ocp);
 294 
 295         if (orphans << shift > sysctl_tcp_max_orphans) {
 296                 orphans = percpu_counter_sum_positive(ocp);
 297                 if (orphans << shift > sysctl_tcp_max_orphans)
 298                         return true;
 299         }
 300         return false;
 301 }
 302 
 303 bool tcp_check_oom(struct sock *sk, int shift);
 304 
 305 
 306 extern struct proto tcp_prot;
 307 
 308 #define TCP_INC_STATS(net, field)       SNMP_INC_STATS((net)->mib.tcp_statistics, field)
 309 #define __TCP_INC_STATS(net, field)     __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
 310 #define TCP_DEC_STATS(net, field)       SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
 311 #define TCP_ADD_STATS(net, field, val)  SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
 312 
 313 void tcp_tasklet_init(void);
 314 
 315 int tcp_v4_err(struct sk_buff *skb, u32);
 316 
 317 void tcp_shutdown(struct sock *sk, int how);
 318 
 319 int tcp_v4_early_demux(struct sk_buff *skb);
 320 int tcp_v4_rcv(struct sk_buff *skb);
 321 
 322 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
 323 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
 324 int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size);
 325 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
 326                  int flags);
 327 int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset,
 328                         size_t size, int flags);
 329 ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
 330                  size_t size, int flags);
 331 void tcp_release_cb(struct sock *sk);
 332 void tcp_wfree(struct sk_buff *skb);
 333 void tcp_write_timer_handler(struct sock *sk);
 334 void tcp_delack_timer_handler(struct sock *sk);
 335 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 336 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
 337 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb);
 338 void tcp_rcv_space_adjust(struct sock *sk);
 339 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
 340 void tcp_twsk_destructor(struct sock *sk);
 341 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
 342                         struct pipe_inode_info *pipe, size_t len,
 343                         unsigned int flags);
 344 
 345 void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks);
 346 static inline void tcp_dec_quickack_mode(struct sock *sk,
 347                                          const unsigned int pkts)
 348 {
 349         struct inet_connection_sock *icsk = inet_csk(sk);
 350 
 351         if (icsk->icsk_ack.quick) {
 352                 if (pkts >= icsk->icsk_ack.quick) {
 353                         icsk->icsk_ack.quick = 0;
 354                         /* Leaving quickack mode we deflate ATO. */
 355                         icsk->icsk_ack.ato   = TCP_ATO_MIN;
 356                 } else
 357                         icsk->icsk_ack.quick -= pkts;
 358         }
 359 }
 360 
 361 #define TCP_ECN_OK              1
 362 #define TCP_ECN_QUEUE_CWR       2
 363 #define TCP_ECN_DEMAND_CWR      4
 364 #define TCP_ECN_SEEN            8
 365 
 366 enum tcp_tw_status {
 367         TCP_TW_SUCCESS = 0,
 368         TCP_TW_RST = 1,
 369         TCP_TW_ACK = 2,
 370         TCP_TW_SYN = 3
 371 };
 372 
 373 
 374 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
 375                                               struct sk_buff *skb,
 376                                               const struct tcphdr *th);
 377 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 378                            struct request_sock *req, bool fastopen,
 379                            bool *lost_race);
 380 int tcp_child_process(struct sock *parent, struct sock *child,
 381                       struct sk_buff *skb);
 382 void tcp_enter_loss(struct sock *sk);
 383 void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int flag);
 384 void tcp_clear_retrans(struct tcp_sock *tp);
 385 void tcp_update_metrics(struct sock *sk);
 386 void tcp_init_metrics(struct sock *sk);
 387 void tcp_metrics_init(void);
 388 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
 389 void tcp_close(struct sock *sk, long timeout);
 390 void tcp_init_sock(struct sock *sk);
 391 void tcp_init_transfer(struct sock *sk, int bpf_op);
 392 __poll_t tcp_poll(struct file *file, struct socket *sock,
 393                       struct poll_table_struct *wait);
 394 int tcp_getsockopt(struct sock *sk, int level, int optname,
 395                    char __user *optval, int __user *optlen);
 396 int tcp_setsockopt(struct sock *sk, int level, int optname,
 397                    char __user *optval, unsigned int optlen);
 398 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
 399                           char __user *optval, int __user *optlen);
 400 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
 401                           char __user *optval, unsigned int optlen);
 402 void tcp_set_keepalive(struct sock *sk, int val);
 403 void tcp_syn_ack_timeout(const struct request_sock *req);
 404 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
 405                 int flags, int *addr_len);
 406 int tcp_set_rcvlowat(struct sock *sk, int val);
 407 void tcp_data_ready(struct sock *sk);
 408 #ifdef CONFIG_MMU
 409 int tcp_mmap(struct file *file, struct socket *sock,
 410              struct vm_area_struct *vma);
 411 #endif
 412 void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
 413                        struct tcp_options_received *opt_rx,
 414                        int estab, struct tcp_fastopen_cookie *foc);
 415 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
 416 
 417 /*
 418  *      BPF SKB-less helpers
 419  */
 420 u16 tcp_v4_get_syncookie(struct sock *sk, struct iphdr *iph,
 421                          struct tcphdr *th, u32 *cookie);
 422 u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph,
 423                          struct tcphdr *th, u32 *cookie);
 424 u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops,
 425                           const struct tcp_request_sock_ops *af_ops,
 426                           struct sock *sk, struct tcphdr *th);
 427 /*
 428  *      TCP v4 functions exported for the inet6 API
 429  */
 430 
 431 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
 432 void tcp_v4_mtu_reduced(struct sock *sk);
 433 void tcp_req_err(struct sock *sk, u32 seq, bool abort);
 434 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
 435 struct sock *tcp_create_openreq_child(const struct sock *sk,
 436                                       struct request_sock *req,
 437                                       struct sk_buff *skb);
 438 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
 439 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
 440                                   struct request_sock *req,
 441                                   struct dst_entry *dst,
 442                                   struct request_sock *req_unhash,
 443                                   bool *own_req);
 444 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
 445 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
 446 int tcp_connect(struct sock *sk);
 447 enum tcp_synack_type {
 448         TCP_SYNACK_NORMAL,
 449         TCP_SYNACK_FASTOPEN,
 450         TCP_SYNACK_COOKIE,
 451 };
 452 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
 453                                 struct request_sock *req,
 454                                 struct tcp_fastopen_cookie *foc,
 455                                 enum tcp_synack_type synack_type);
 456 int tcp_disconnect(struct sock *sk, int flags);
 457 
 458 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
 459 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
 460 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
 461 
 462 /* From syncookies.c */
 463 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
 464                                  struct request_sock *req,
 465                                  struct dst_entry *dst, u32 tsoff);
 466 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
 467                       u32 cookie);
 468 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
 469 #ifdef CONFIG_SYN_COOKIES
 470 
 471 /* Syncookies use a monotonic timer which increments every 60 seconds.
 472  * This counter is used both as a hash input and partially encoded into
 473  * the cookie value.  A cookie is only validated further if the delta
 474  * between the current counter value and the encoded one is less than this,
 475  * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
 476  * the counter advances immediately after a cookie is generated).
 477  */
 478 #define MAX_SYNCOOKIE_AGE       2
 479 #define TCP_SYNCOOKIE_PERIOD    (60 * HZ)
 480 #define TCP_SYNCOOKIE_VALID     (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
 481 
 482 /* syncookies: remember time of last synqueue overflow
 483  * But do not dirty this field too often (once per second is enough)
 484  * It is racy as we do not hold a lock, but race is very minor.
 485  */
 486 static inline void tcp_synq_overflow(const struct sock *sk)
 487 {
 488         unsigned int last_overflow;
 489         unsigned int now = jiffies;
 490 
 491         if (sk->sk_reuseport) {
 492                 struct sock_reuseport *reuse;
 493 
 494                 reuse = rcu_dereference(sk->sk_reuseport_cb);
 495                 if (likely(reuse)) {
 496                         last_overflow = READ_ONCE(reuse->synq_overflow_ts);
 497                         if (!time_between32(now, last_overflow,
 498                                             last_overflow + HZ))
 499                                 WRITE_ONCE(reuse->synq_overflow_ts, now);
 500                         return;
 501                 }
 502         }
 503 
 504         last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
 505         if (!time_between32(now, last_overflow, last_overflow + HZ))
 506                 WRITE_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp, now);
 507 }
 508 
 509 /* syncookies: no recent synqueue overflow on this listening socket? */
 510 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
 511 {
 512         unsigned int last_overflow;
 513         unsigned int now = jiffies;
 514 
 515         if (sk->sk_reuseport) {
 516                 struct sock_reuseport *reuse;
 517 
 518                 reuse = rcu_dereference(sk->sk_reuseport_cb);
 519                 if (likely(reuse)) {
 520                         last_overflow = READ_ONCE(reuse->synq_overflow_ts);
 521                         return !time_between32(now, last_overflow - HZ,
 522                                                last_overflow +
 523                                                TCP_SYNCOOKIE_VALID);
 524                 }
 525         }
 526 
 527         last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
 528 
 529         /* If last_overflow <= jiffies <= last_overflow + TCP_SYNCOOKIE_VALID,
 530          * then we're under synflood. However, we have to use
 531          * 'last_overflow - HZ' as lower bound. That's because a concurrent
 532          * tcp_synq_overflow() could update .ts_recent_stamp after we read
 533          * jiffies but before we store .ts_recent_stamp into last_overflow,
 534          * which could lead to rejecting a valid syncookie.
 535          */
 536         return !time_between32(now, last_overflow - HZ,
 537                                last_overflow + TCP_SYNCOOKIE_VALID);
 538 }
 539 
 540 static inline u32 tcp_cookie_time(void)
 541 {
 542         u64 val = get_jiffies_64();
 543 
 544         do_div(val, TCP_SYNCOOKIE_PERIOD);
 545         return val;
 546 }
 547 
 548 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
 549                               u16 *mssp);
 550 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
 551 u64 cookie_init_timestamp(struct request_sock *req);
 552 bool cookie_timestamp_decode(const struct net *net,
 553                              struct tcp_options_received *opt);
 554 bool cookie_ecn_ok(const struct tcp_options_received *opt,
 555                    const struct net *net, const struct dst_entry *dst);
 556 
 557 /* From net/ipv6/syncookies.c */
 558 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
 559                       u32 cookie);
 560 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
 561 
 562 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
 563                               const struct tcphdr *th, u16 *mssp);
 564 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
 565 #endif
 566 /* tcp_output.c */
 567 
 568 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
 569                                int nonagle);
 570 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
 571 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
 572 void tcp_retransmit_timer(struct sock *sk);
 573 void tcp_xmit_retransmit_queue(struct sock *);
 574 void tcp_simple_retransmit(struct sock *);
 575 void tcp_enter_recovery(struct sock *sk, bool ece_ack);
 576 int tcp_trim_head(struct sock *, struct sk_buff *, u32);
 577 enum tcp_queue {
 578         TCP_FRAG_IN_WRITE_QUEUE,
 579         TCP_FRAG_IN_RTX_QUEUE,
 580 };
 581 int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
 582                  struct sk_buff *skb, u32 len,
 583                  unsigned int mss_now, gfp_t gfp);
 584 
 585 void tcp_send_probe0(struct sock *);
 586 void tcp_send_partial(struct sock *);
 587 int tcp_write_wakeup(struct sock *, int mib);
 588 void tcp_send_fin(struct sock *sk);
 589 void tcp_send_active_reset(struct sock *sk, gfp_t priority);
 590 int tcp_send_synack(struct sock *);
 591 void tcp_push_one(struct sock *, unsigned int mss_now);
 592 void __tcp_send_ack(struct sock *sk, u32 rcv_nxt);
 593 void tcp_send_ack(struct sock *sk);
 594 void tcp_send_delayed_ack(struct sock *sk);
 595 void tcp_send_loss_probe(struct sock *sk);
 596 bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto);
 597 void tcp_skb_collapse_tstamp(struct sk_buff *skb,
 598                              const struct sk_buff *next_skb);
 599 
 600 /* tcp_input.c */
 601 void tcp_rearm_rto(struct sock *sk);
 602 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
 603 void tcp_reset(struct sock *sk);
 604 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
 605 void tcp_fin(struct sock *sk);
 606 
 607 /* tcp_timer.c */
 608 void tcp_init_xmit_timers(struct sock *);
 609 static inline void tcp_clear_xmit_timers(struct sock *sk)
 610 {
 611         if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1)
 612                 __sock_put(sk);
 613 
 614         if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1)
 615                 __sock_put(sk);
 616 
 617         inet_csk_clear_xmit_timers(sk);
 618 }
 619 
 620 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
 621 unsigned int tcp_current_mss(struct sock *sk);
 622 
 623 /* Bound MSS / TSO packet size with the half of the window */
 624 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
 625 {
 626         int cutoff;
 627 
 628         /* When peer uses tiny windows, there is no use in packetizing
 629          * to sub-MSS pieces for the sake of SWS or making sure there
 630          * are enough packets in the pipe for fast recovery.
 631          *
 632          * On the other hand, for extremely large MSS devices, handling
 633          * smaller than MSS windows in this way does make sense.
 634          */
 635         if (tp->max_window > TCP_MSS_DEFAULT)
 636                 cutoff = (tp->max_window >> 1);
 637         else
 638                 cutoff = tp->max_window;
 639 
 640         if (cutoff && pktsize > cutoff)
 641                 return max_t(int, cutoff, 68U - tp->tcp_header_len);
 642         else
 643                 return pktsize;
 644 }
 645 
 646 /* tcp.c */
 647 void tcp_get_info(struct sock *, struct tcp_info *);
 648 
 649 /* Read 'sendfile()'-style from a TCP socket */
 650 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
 651                   sk_read_actor_t recv_actor);
 652 
 653 void tcp_initialize_rcv_mss(struct sock *sk);
 654 
 655 int tcp_mtu_to_mss(struct sock *sk, int pmtu);
 656 int tcp_mss_to_mtu(struct sock *sk, int mss);
 657 void tcp_mtup_init(struct sock *sk);
 658 void tcp_init_buffer_space(struct sock *sk);
 659 
 660 static inline void tcp_bound_rto(const struct sock *sk)
 661 {
 662         if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
 663                 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
 664 }
 665 
 666 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
 667 {
 668         return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
 669 }
 670 
 671 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
 672 {
 673         tp->pred_flags = htonl((tp->tcp_header_len << 26) |
 674                                ntohl(TCP_FLAG_ACK) |
 675                                snd_wnd);
 676 }
 677 
 678 static inline void tcp_fast_path_on(struct tcp_sock *tp)
 679 {
 680         __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
 681 }
 682 
 683 static inline void tcp_fast_path_check(struct sock *sk)
 684 {
 685         struct tcp_sock *tp = tcp_sk(sk);
 686 
 687         if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
 688             tp->rcv_wnd &&
 689             atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
 690             !tp->urg_data)
 691                 tcp_fast_path_on(tp);
 692 }
 693 
 694 /* Compute the actual rto_min value */
 695 static inline u32 tcp_rto_min(struct sock *sk)
 696 {
 697         const struct dst_entry *dst = __sk_dst_get(sk);
 698         u32 rto_min = TCP_RTO_MIN;
 699 
 700         if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
 701                 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
 702         return rto_min;
 703 }
 704 
 705 static inline u32 tcp_rto_min_us(struct sock *sk)
 706 {
 707         return jiffies_to_usecs(tcp_rto_min(sk));
 708 }
 709 
 710 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
 711 {
 712         return dst_metric_locked(dst, RTAX_CC_ALGO);
 713 }
 714 
 715 /* Minimum RTT in usec. ~0 means not available. */
 716 static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
 717 {
 718         return minmax_get(&tp->rtt_min);
 719 }
 720 
 721 /* Compute the actual receive window we are currently advertising.
 722  * Rcv_nxt can be after the window if our peer push more data
 723  * than the offered window.
 724  */
 725 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
 726 {
 727         s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
 728 
 729         if (win < 0)
 730                 win = 0;
 731         return (u32) win;
 732 }
 733 
 734 /* Choose a new window, without checks for shrinking, and without
 735  * scaling applied to the result.  The caller does these things
 736  * if necessary.  This is a "raw" window selection.
 737  */
 738 u32 __tcp_select_window(struct sock *sk);
 739 
 740 void tcp_send_window_probe(struct sock *sk);
 741 
 742 /* TCP uses 32bit jiffies to save some space.
 743  * Note that this is different from tcp_time_stamp, which
 744  * historically has been the same until linux-4.13.
 745  */
 746 #define tcp_jiffies32 ((u32)jiffies)
 747 
 748 /*
 749  * Deliver a 32bit value for TCP timestamp option (RFC 7323)
 750  * It is no longer tied to jiffies, but to 1 ms clock.
 751  * Note: double check if you want to use tcp_jiffies32 instead of this.
 752  */
 753 #define TCP_TS_HZ       1000
 754 
 755 static inline u64 tcp_clock_ns(void)
 756 {
 757         return ktime_get_ns();
 758 }
 759 
 760 static inline u64 tcp_clock_us(void)
 761 {
 762         return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
 763 }
 764 
 765 /* This should only be used in contexts where tp->tcp_mstamp is up to date */
 766 static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
 767 {
 768         return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ);
 769 }
 770 
 771 /* Could use tcp_clock_us() / 1000, but this version uses a single divide */
 772 static inline u32 tcp_time_stamp_raw(void)
 773 {
 774         return div_u64(tcp_clock_ns(), NSEC_PER_SEC / TCP_TS_HZ);
 775 }
 776 
 777 void tcp_mstamp_refresh(struct tcp_sock *tp);
 778 
 779 static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
 780 {
 781         return max_t(s64, t1 - t0, 0);
 782 }
 783 
 784 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
 785 {
 786         return div_u64(skb->skb_mstamp_ns, NSEC_PER_SEC / TCP_TS_HZ);
 787 }
 788 
 789 /* provide the departure time in us unit */
 790 static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb)
 791 {
 792         return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC);
 793 }
 794 
 795 
 796 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
 797 
 798 #define TCPHDR_FIN 0x01
 799 #define TCPHDR_SYN 0x02
 800 #define TCPHDR_RST 0x04
 801 #define TCPHDR_PSH 0x08
 802 #define TCPHDR_ACK 0x10
 803 #define TCPHDR_URG 0x20
 804 #define TCPHDR_ECE 0x40
 805 #define TCPHDR_CWR 0x80
 806 
 807 #define TCPHDR_SYN_ECN  (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
 808 
 809 /* This is what the send packet queuing engine uses to pass
 810  * TCP per-packet control information to the transmission code.
 811  * We also store the host-order sequence numbers in here too.
 812  * This is 44 bytes if IPV6 is enabled.
 813  * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
 814  */
 815 struct tcp_skb_cb {
 816         __u32           seq;            /* Starting sequence number     */
 817         __u32           end_seq;        /* SEQ + FIN + SYN + datalen    */
 818         union {
 819                 /* Note : tcp_tw_isn is used in input path only
 820                  *        (isn chosen by tcp_timewait_state_process())
 821                  *
 822                  *        tcp_gso_segs/size are used in write queue only,
 823                  *        cf tcp_skb_pcount()/tcp_skb_mss()
 824                  */
 825                 __u32           tcp_tw_isn;
 826                 struct {
 827                         u16     tcp_gso_segs;
 828                         u16     tcp_gso_size;
 829                 };
 830         };
 831         __u8            tcp_flags;      /* TCP header flags. (tcp[13])  */
 832 
 833         __u8            sacked;         /* State flags for SACK.        */
 834 #define TCPCB_SACKED_ACKED      0x01    /* SKB ACK'd by a SACK block    */
 835 #define TCPCB_SACKED_RETRANS    0x02    /* SKB retransmitted            */
 836 #define TCPCB_LOST              0x04    /* SKB is lost                  */
 837 #define TCPCB_TAGBITS           0x07    /* All tag bits                 */
 838 #define TCPCB_REPAIRED          0x10    /* SKB repaired (no skb_mstamp_ns)      */
 839 #define TCPCB_EVER_RETRANS      0x80    /* Ever retransmitted frame     */
 840 #define TCPCB_RETRANS           (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
 841                                 TCPCB_REPAIRED)
 842 
 843         __u8            ip_dsfield;     /* IPv4 tos or IPv6 dsfield     */
 844         __u8            txstamp_ack:1,  /* Record TX timestamp for ack? */
 845                         eor:1,          /* Is skb MSG_EOR marked? */
 846                         has_rxtstamp:1, /* SKB has a RX timestamp       */
 847                         unused:5;
 848         __u32           ack_seq;        /* Sequence number ACK'd        */
 849         union {
 850                 struct {
 851                         /* There is space for up to 24 bytes */
 852                         __u32 in_flight:30,/* Bytes in flight at transmit */
 853                               is_app_limited:1, /* cwnd not fully used? */
 854                               unused:1;
 855                         /* pkts S/ACKed so far upon tx of skb, incl retrans: */
 856                         __u32 delivered;
 857                         /* start of send pipeline phase */
 858                         u64 first_tx_mstamp;
 859                         /* when we reached the "delivered" count */
 860                         u64 delivered_mstamp;
 861                 } tx;   /* only used for outgoing skbs */
 862                 union {
 863                         struct inet_skb_parm    h4;
 864 #if IS_ENABLED(CONFIG_IPV6)
 865                         struct inet6_skb_parm   h6;
 866 #endif
 867                 } header;       /* For incoming skbs */
 868                 struct {
 869                         __u32 flags;
 870                         struct sock *sk_redir;
 871                         void *data_end;
 872                 } bpf;
 873         };
 874 };
 875 
 876 #define TCP_SKB_CB(__skb)       ((struct tcp_skb_cb *)&((__skb)->cb[0]))
 877 
 878 static inline void bpf_compute_data_end_sk_skb(struct sk_buff *skb)
 879 {
 880         TCP_SKB_CB(skb)->bpf.data_end = skb->data + skb_headlen(skb);
 881 }
 882 
 883 static inline bool tcp_skb_bpf_ingress(const struct sk_buff *skb)
 884 {
 885         return TCP_SKB_CB(skb)->bpf.flags & BPF_F_INGRESS;
 886 }
 887 
 888 static inline struct sock *tcp_skb_bpf_redirect_fetch(struct sk_buff *skb)
 889 {
 890         return TCP_SKB_CB(skb)->bpf.sk_redir;
 891 }
 892 
 893 static inline void tcp_skb_bpf_redirect_clear(struct sk_buff *skb)
 894 {
 895         TCP_SKB_CB(skb)->bpf.sk_redir = NULL;
 896 }
 897 
 898 #if IS_ENABLED(CONFIG_IPV6)
 899 /* This is the variant of inet6_iif() that must be used by TCP,
 900  * as TCP moves IP6CB into a different location in skb->cb[]
 901  */
 902 static inline int tcp_v6_iif(const struct sk_buff *skb)
 903 {
 904         return TCP_SKB_CB(skb)->header.h6.iif;
 905 }
 906 
 907 static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb)
 908 {
 909         bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
 910 
 911         return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
 912 }
 913 
 914 /* TCP_SKB_CB reference means this can not be used from early demux */
 915 static inline int tcp_v6_sdif(const struct sk_buff *skb)
 916 {
 917 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
 918         if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags))
 919                 return TCP_SKB_CB(skb)->header.h6.iif;
 920 #endif
 921         return 0;
 922 }
 923 #endif
 924 
 925 static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
 926 {
 927 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
 928         if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
 929             skb && ipv4_l3mdev_skb(IPCB(skb)->flags))
 930                 return true;
 931 #endif
 932         return false;
 933 }
 934 
 935 /* TCP_SKB_CB reference means this can not be used from early demux */
 936 static inline int tcp_v4_sdif(struct sk_buff *skb)
 937 {
 938 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
 939         if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
 940                 return TCP_SKB_CB(skb)->header.h4.iif;
 941 #endif
 942         return 0;
 943 }
 944 
 945 /* Due to TSO, an SKB can be composed of multiple actual
 946  * packets.  To keep these tracked properly, we use this.
 947  */
 948 static inline int tcp_skb_pcount(const struct sk_buff *skb)
 949 {
 950         return TCP_SKB_CB(skb)->tcp_gso_segs;
 951 }
 952 
 953 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
 954 {
 955         TCP_SKB_CB(skb)->tcp_gso_segs = segs;
 956 }
 957 
 958 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
 959 {
 960         TCP_SKB_CB(skb)->tcp_gso_segs += segs;
 961 }
 962 
 963 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
 964 static inline int tcp_skb_mss(const struct sk_buff *skb)
 965 {
 966         return TCP_SKB_CB(skb)->tcp_gso_size;
 967 }
 968 
 969 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
 970 {
 971         return likely(!TCP_SKB_CB(skb)->eor);
 972 }
 973 
 974 /* Events passed to congestion control interface */
 975 enum tcp_ca_event {
 976         CA_EVENT_TX_START,      /* first transmit when no packets in flight */
 977         CA_EVENT_CWND_RESTART,  /* congestion window restart */
 978         CA_EVENT_COMPLETE_CWR,  /* end of congestion recovery */
 979         CA_EVENT_LOSS,          /* loss timeout */
 980         CA_EVENT_ECN_NO_CE,     /* ECT set, but not CE marked */
 981         CA_EVENT_ECN_IS_CE,     /* received CE marked IP packet */
 982 };
 983 
 984 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */
 985 enum tcp_ca_ack_event_flags {
 986         CA_ACK_SLOWPATH         = (1 << 0),     /* In slow path processing */
 987         CA_ACK_WIN_UPDATE       = (1 << 1),     /* ACK updated window */
 988         CA_ACK_ECE              = (1 << 2),     /* ECE bit is set on ack */
 989 };
 990 
 991 /*
 992  * Interface for adding new TCP congestion control handlers
 993  */
 994 #define TCP_CA_NAME_MAX 16
 995 #define TCP_CA_MAX      128
 996 #define TCP_CA_BUF_MAX  (TCP_CA_NAME_MAX*TCP_CA_MAX)
 997 
 998 #define TCP_CA_UNSPEC   0
 999 
1000 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
1001 #define TCP_CONG_NON_RESTRICTED 0x1
1002 /* Requires ECN/ECT set on all packets */
1003 #define TCP_CONG_NEEDS_ECN      0x2
1004 
1005 union tcp_cc_info;
1006 
1007 struct ack_sample {
1008         u32 pkts_acked;
1009         s32 rtt_us;
1010         u32 in_flight;
1011 };
1012 
1013 /* A rate sample measures the number of (original/retransmitted) data
1014  * packets delivered "delivered" over an interval of time "interval_us".
1015  * The tcp_rate.c code fills in the rate sample, and congestion
1016  * control modules that define a cong_control function to run at the end
1017  * of ACK processing can optionally chose to consult this sample when
1018  * setting cwnd and pacing rate.
1019  * A sample is invalid if "delivered" or "interval_us" is negative.
1020  */
1021 struct rate_sample {
1022         u64  prior_mstamp; /* starting timestamp for interval */
1023         u32  prior_delivered;   /* tp->delivered at "prior_mstamp" */
1024         s32  delivered;         /* number of packets delivered over interval */
1025         long interval_us;       /* time for tp->delivered to incr "delivered" */
1026         u32 snd_interval_us;    /* snd interval for delivered packets */
1027         u32 rcv_interval_us;    /* rcv interval for delivered packets */
1028         long rtt_us;            /* RTT of last (S)ACKed packet (or -1) */
1029         int  losses;            /* number of packets marked lost upon ACK */
1030         u32  acked_sacked;      /* number of packets newly (S)ACKed upon ACK */
1031         u32  prior_in_flight;   /* in flight before this ACK */
1032         bool is_app_limited;    /* is sample from packet with bubble in pipe? */
1033         bool is_retrans;        /* is sample from retransmission? */
1034         bool is_ack_delayed;    /* is this (likely) a delayed ACK? */
1035 };
1036 
1037 struct tcp_congestion_ops {
1038         struct list_head        list;
1039         u32 key;
1040         u32 flags;
1041 
1042         /* initialize private data (optional) */
1043         void (*init)(struct sock *sk);
1044         /* cleanup private data  (optional) */
1045         void (*release)(struct sock *sk);
1046 
1047         /* return slow start threshold (required) */
1048         u32 (*ssthresh)(struct sock *sk);
1049         /* do new cwnd calculation (required) */
1050         void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
1051         /* call before changing ca_state (optional) */
1052         void (*set_state)(struct sock *sk, u8 new_state);
1053         /* call when cwnd event occurs (optional) */
1054         void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
1055         /* call when ack arrives (optional) */
1056         void (*in_ack_event)(struct sock *sk, u32 flags);
1057         /* new value of cwnd after loss (required) */
1058         u32  (*undo_cwnd)(struct sock *sk);
1059         /* hook for packet ack accounting (optional) */
1060         void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
1061         /* override sysctl_tcp_min_tso_segs */
1062         u32 (*min_tso_segs)(struct sock *sk);
1063         /* returns the multiplier used in tcp_sndbuf_expand (optional) */
1064         u32 (*sndbuf_expand)(struct sock *sk);
1065         /* call when packets are delivered to update cwnd and pacing rate,
1066          * after all the ca_state processing. (optional)
1067          */
1068         void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
1069         /* get info for inet_diag (optional) */
1070         size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
1071                            union tcp_cc_info *info);
1072 
1073         char            name[TCP_CA_NAME_MAX];
1074         struct module   *owner;
1075 };
1076 
1077 int tcp_register_congestion_control(struct tcp_congestion_ops *type);
1078 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
1079 
1080 void tcp_assign_congestion_control(struct sock *sk);
1081 void tcp_init_congestion_control(struct sock *sk);
1082 void tcp_cleanup_congestion_control(struct sock *sk);
1083 int tcp_set_default_congestion_control(struct net *net, const char *name);
1084 void tcp_get_default_congestion_control(struct net *net, char *name);
1085 void tcp_get_available_congestion_control(char *buf, size_t len);
1086 void tcp_get_allowed_congestion_control(char *buf, size_t len);
1087 int tcp_set_allowed_congestion_control(char *allowed);
1088 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
1089                                bool reinit, bool cap_net_admin);
1090 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
1091 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1092 
1093 u32 tcp_reno_ssthresh(struct sock *sk);
1094 u32 tcp_reno_undo_cwnd(struct sock *sk);
1095 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1096 extern struct tcp_congestion_ops tcp_reno;
1097 
1098 struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1099 u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca);
1100 #ifdef CONFIG_INET
1101 char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1102 #else
1103 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
1104 {
1105         return NULL;
1106 }
1107 #endif
1108 
1109 static inline bool tcp_ca_needs_ecn(const struct sock *sk)
1110 {
1111         const struct inet_connection_sock *icsk = inet_csk(sk);
1112 
1113         return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
1114 }
1115 
1116 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
1117 {
1118         struct inet_connection_sock *icsk = inet_csk(sk);
1119 
1120         if (icsk->icsk_ca_ops->set_state)
1121                 icsk->icsk_ca_ops->set_state(sk, ca_state);
1122         icsk->icsk_ca_state = ca_state;
1123 }
1124 
1125 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1126 {
1127         const struct inet_connection_sock *icsk = inet_csk(sk);
1128 
1129         if (icsk->icsk_ca_ops->cwnd_event)
1130                 icsk->icsk_ca_ops->cwnd_event(sk, event);
1131 }
1132 
1133 /* From tcp_rate.c */
1134 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1135 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1136                             struct rate_sample *rs);
1137 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1138                   bool is_sack_reneg, struct rate_sample *rs);
1139 void tcp_rate_check_app_limited(struct sock *sk);
1140 
1141 /* These functions determine how the current flow behaves in respect of SACK
1142  * handling. SACK is negotiated with the peer, and therefore it can vary
1143  * between different flows.
1144  *
1145  * tcp_is_sack - SACK enabled
1146  * tcp_is_reno - No SACK
1147  */
1148 static inline int tcp_is_sack(const struct tcp_sock *tp)
1149 {
1150         return likely(tp->rx_opt.sack_ok);
1151 }
1152 
1153 static inline bool tcp_is_reno(const struct tcp_sock *tp)
1154 {
1155         return !tcp_is_sack(tp);
1156 }
1157 
1158 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1159 {
1160         return tp->sacked_out + tp->lost_out;
1161 }
1162 
1163 /* This determines how many packets are "in the network" to the best
1164  * of our knowledge.  In many cases it is conservative, but where
1165  * detailed information is available from the receiver (via SACK
1166  * blocks etc.) we can make more aggressive calculations.
1167  *
1168  * Use this for decisions involving congestion control, use just
1169  * tp->packets_out to determine if the send queue is empty or not.
1170  *
1171  * Read this equation as:
1172  *
1173  *      "Packets sent once on transmission queue" MINUS
1174  *      "Packets left network, but not honestly ACKed yet" PLUS
1175  *      "Packets fast retransmitted"
1176  */
1177 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1178 {
1179         return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1180 }
1181 
1182 #define TCP_INFINITE_SSTHRESH   0x7fffffff
1183 
1184 static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1185 {
1186         return tp->snd_cwnd < tp->snd_ssthresh;
1187 }
1188 
1189 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1190 {
1191         return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1192 }
1193 
1194 static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1195 {
1196         return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1197                (1 << inet_csk(sk)->icsk_ca_state);
1198 }
1199 
1200 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1201  * The exception is cwnd reduction phase, when cwnd is decreasing towards
1202  * ssthresh.
1203  */
1204 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1205 {
1206         const struct tcp_sock *tp = tcp_sk(sk);
1207 
1208         if (tcp_in_cwnd_reduction(sk))
1209                 return tp->snd_ssthresh;
1210         else
1211                 return max(tp->snd_ssthresh,
1212                            ((tp->snd_cwnd >> 1) +
1213                             (tp->snd_cwnd >> 2)));
1214 }
1215 
1216 /* Use define here intentionally to get WARN_ON location shown at the caller */
1217 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1218 
1219 void tcp_enter_cwr(struct sock *sk);
1220 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1221 
1222 /* The maximum number of MSS of available cwnd for which TSO defers
1223  * sending if not using sysctl_tcp_tso_win_divisor.
1224  */
1225 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1226 {
1227         return 3;
1228 }
1229 
1230 /* Returns end sequence number of the receiver's advertised window */
1231 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1232 {
1233         return tp->snd_una + tp->snd_wnd;
1234 }
1235 
1236 /* We follow the spirit of RFC2861 to validate cwnd but implement a more
1237  * flexible approach. The RFC suggests cwnd should not be raised unless
1238  * it was fully used previously. And that's exactly what we do in
1239  * congestion avoidance mode. But in slow start we allow cwnd to grow
1240  * as long as the application has used half the cwnd.
1241  * Example :
1242  *    cwnd is 10 (IW10), but application sends 9 frames.
1243  *    We allow cwnd to reach 18 when all frames are ACKed.
1244  * This check is safe because it's as aggressive as slow start which already
1245  * risks 100% overshoot. The advantage is that we discourage application to
1246  * either send more filler packets or data to artificially blow up the cwnd
1247  * usage, and allow application-limited process to probe bw more aggressively.
1248  */
1249 static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1250 {
1251         const struct tcp_sock *tp = tcp_sk(sk);
1252 
1253         /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1254         if (tcp_in_slow_start(tp))
1255                 return tp->snd_cwnd < 2 * tp->max_packets_out;
1256 
1257         return tp->is_cwnd_limited;
1258 }
1259 
1260 /* BBR congestion control needs pacing.
1261  * Same remark for SO_MAX_PACING_RATE.
1262  * sch_fq packet scheduler is efficiently handling pacing,
1263  * but is not always installed/used.
1264  * Return true if TCP stack should pace packets itself.
1265  */
1266 static inline bool tcp_needs_internal_pacing(const struct sock *sk)
1267 {
1268         return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
1269 }
1270 
1271 /* Return in jiffies the delay before one skb is sent.
1272  * If @skb is NULL, we look at EDT for next packet being sent on the socket.
1273  */
1274 static inline unsigned long tcp_pacing_delay(const struct sock *sk,
1275                                              const struct sk_buff *skb)
1276 {
1277         s64 pacing_delay = skb ? skb->tstamp : tcp_sk(sk)->tcp_wstamp_ns;
1278 
1279         pacing_delay -= tcp_sk(sk)->tcp_clock_cache;
1280 
1281         return pacing_delay > 0 ? nsecs_to_jiffies(pacing_delay) : 0;
1282 }
1283 
1284 static inline void tcp_reset_xmit_timer(struct sock *sk,
1285                                         const int what,
1286                                         unsigned long when,
1287                                         const unsigned long max_when,
1288                                         const struct sk_buff *skb)
1289 {
1290         inet_csk_reset_xmit_timer(sk, what, when + tcp_pacing_delay(sk, skb),
1291                                   max_when);
1292 }
1293 
1294 /* Something is really bad, we could not queue an additional packet,
1295  * because qdisc is full or receiver sent a 0 window, or we are paced.
1296  * We do not want to add fuel to the fire, or abort too early,
1297  * so make sure the timer we arm now is at least 200ms in the future,
1298  * regardless of current icsk_rto value (as it could be ~2ms)
1299  */
1300 static inline unsigned long tcp_probe0_base(const struct sock *sk)
1301 {
1302         return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1303 }
1304 
1305 /* Variant of inet_csk_rto_backoff() used for zero window probes */
1306 static inline unsigned long tcp_probe0_when(const struct sock *sk,
1307                                             unsigned long max_when)
1308 {
1309         u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff;
1310 
1311         return (unsigned long)min_t(u64, when, max_when);
1312 }
1313 
1314 static inline void tcp_check_probe_timer(struct sock *sk)
1315 {
1316         if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1317                 tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1318                                      tcp_probe0_base(sk), TCP_RTO_MAX,
1319                                      NULL);
1320 }
1321 
1322 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1323 {
1324         tp->snd_wl1 = seq;
1325 }
1326 
1327 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1328 {
1329         tp->snd_wl1 = seq;
1330 }
1331 
1332 /*
1333  * Calculate(/check) TCP checksum
1334  */
1335 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1336                                    __be32 daddr, __wsum base)
1337 {
1338         return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_TCP, base);
1339 }
1340 
1341 static inline bool tcp_checksum_complete(struct sk_buff *skb)
1342 {
1343         return !skb_csum_unnecessary(skb) &&
1344                 __skb_checksum_complete(skb);
1345 }
1346 
1347 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb);
1348 int tcp_filter(struct sock *sk, struct sk_buff *skb);
1349 void tcp_set_state(struct sock *sk, int state);
1350 void tcp_done(struct sock *sk);
1351 int tcp_abort(struct sock *sk, int err);
1352 
1353 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1354 {
1355         rx_opt->dsack = 0;
1356         rx_opt->num_sacks = 0;
1357 }
1358 
1359 u32 tcp_default_init_rwnd(u32 mss);
1360 void tcp_cwnd_restart(struct sock *sk, s32 delta);
1361 
1362 static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1363 {
1364         const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1365         struct tcp_sock *tp = tcp_sk(sk);
1366         s32 delta;
1367 
1368         if (!sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle || tp->packets_out ||
1369             ca_ops->cong_control)
1370                 return;
1371         delta = tcp_jiffies32 - tp->lsndtime;
1372         if (delta > inet_csk(sk)->icsk_rto)
1373                 tcp_cwnd_restart(sk, delta);
1374 }
1375 
1376 /* Determine a window scaling and initial window to offer. */
1377 void tcp_select_initial_window(const struct sock *sk, int __space,
1378                                __u32 mss, __u32 *rcv_wnd,
1379                                __u32 *window_clamp, int wscale_ok,
1380                                __u8 *rcv_wscale, __u32 init_rcv_wnd);
1381 
1382 static inline int tcp_win_from_space(const struct sock *sk, int space)
1383 {
1384         int tcp_adv_win_scale = sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale;
1385 
1386         return tcp_adv_win_scale <= 0 ?
1387                 (space>>(-tcp_adv_win_scale)) :
1388                 space - (space>>tcp_adv_win_scale);
1389 }
1390 
1391 /* Note: caller must be prepared to deal with negative returns */
1392 static inline int tcp_space(const struct sock *sk)
1393 {
1394         return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf) -
1395                                   READ_ONCE(sk->sk_backlog.len) -
1396                                   atomic_read(&sk->sk_rmem_alloc));
1397 }
1398 
1399 static inline int tcp_full_space(const struct sock *sk)
1400 {
1401         return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1402 }
1403 
1404 /* We provision sk_rcvbuf around 200% of sk_rcvlowat.
1405  * If 87.5 % (7/8) of the space has been consumed, we want to override
1406  * SO_RCVLOWAT constraint, since we are receiving skbs with too small
1407  * len/truesize ratio.
1408  */
1409 static inline bool tcp_rmem_pressure(const struct sock *sk)
1410 {
1411         int rcvbuf = READ_ONCE(sk->sk_rcvbuf);
1412         int threshold = rcvbuf - (rcvbuf >> 3);
1413 
1414         return atomic_read(&sk->sk_rmem_alloc) > threshold;
1415 }
1416 
1417 extern void tcp_openreq_init_rwin(struct request_sock *req,
1418                                   const struct sock *sk_listener,
1419                                   const struct dst_entry *dst);
1420 
1421 void tcp_enter_memory_pressure(struct sock *sk);
1422 void tcp_leave_memory_pressure(struct sock *sk);
1423 
1424 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1425 {
1426         struct net *net = sock_net((struct sock *)tp);
1427 
1428         return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
1429 }
1430 
1431 static inline int keepalive_time_when(const struct tcp_sock *tp)
1432 {
1433         struct net *net = sock_net((struct sock *)tp);
1434 
1435         return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
1436 }
1437 
1438 static inline int keepalive_probes(const struct tcp_sock *tp)
1439 {
1440         struct net *net = sock_net((struct sock *)tp);
1441 
1442         return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
1443 }
1444 
1445 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1446 {
1447         const struct inet_connection_sock *icsk = &tp->inet_conn;
1448 
1449         return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
1450                           tcp_jiffies32 - tp->rcv_tstamp);
1451 }
1452 
1453 static inline int tcp_fin_time(const struct sock *sk)
1454 {
1455         int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
1456         const int rto = inet_csk(sk)->icsk_rto;
1457 
1458         if (fin_timeout < (rto << 2) - (rto >> 1))
1459                 fin_timeout = (rto << 2) - (rto >> 1);
1460 
1461         return fin_timeout;
1462 }
1463 
1464 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1465                                   int paws_win)
1466 {
1467         if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1468                 return true;
1469         if (unlikely(!time_before32(ktime_get_seconds(),
1470                                     rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)))
1471                 return true;
1472         /*
1473          * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1474          * then following tcp messages have valid values. Ignore 0 value,
1475          * or else 'negative' tsval might forbid us to accept their packets.
1476          */
1477         if (!rx_opt->ts_recent)
1478                 return true;
1479         return false;
1480 }
1481 
1482 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1483                                    int rst)
1484 {
1485         if (tcp_paws_check(rx_opt, 0))
1486                 return false;
1487 
1488         /* RST segments are not recommended to carry timestamp,
1489            and, if they do, it is recommended to ignore PAWS because
1490            "their cleanup function should take precedence over timestamps."
1491            Certainly, it is mistake. It is necessary to understand the reasons
1492            of this constraint to relax it: if peer reboots, clock may go
1493            out-of-sync and half-open connections will not be reset.
1494            Actually, the problem would be not existing if all
1495            the implementations followed draft about maintaining clock
1496            via reboots. Linux-2.2 DOES NOT!
1497 
1498            However, we can relax time bounds for RST segments to MSL.
1499          */
1500         if (rst && !time_before32(ktime_get_seconds(),
1501                                   rx_opt->ts_recent_stamp + TCP_PAWS_MSL))
1502                 return false;
1503         return true;
1504 }
1505 
1506 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1507                           int mib_idx, u32 *last_oow_ack_time);
1508 
1509 static inline void tcp_mib_init(struct net *net)
1510 {
1511         /* See RFC 2012 */
1512         TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1513         TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1514         TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1515         TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1516 }
1517 
1518 /* from STCP */
1519 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1520 {
1521         tp->lost_skb_hint = NULL;
1522 }
1523 
1524 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1525 {
1526         tcp_clear_retrans_hints_partial(tp);
1527         tp->retransmit_skb_hint = NULL;
1528 }
1529 
1530 union tcp_md5_addr {
1531         struct in_addr  a4;
1532 #if IS_ENABLED(CONFIG_IPV6)
1533         struct in6_addr a6;
1534 #endif
1535 };
1536 
1537 /* - key database */
1538 struct tcp_md5sig_key {
1539         struct hlist_node       node;
1540         u8                      keylen;
1541         u8                      family; /* AF_INET or AF_INET6 */
1542         union tcp_md5_addr      addr;
1543         u8                      prefixlen;
1544         u8                      key[TCP_MD5SIG_MAXKEYLEN];
1545         struct rcu_head         rcu;
1546 };
1547 
1548 /* - sock block */
1549 struct tcp_md5sig_info {
1550         struct hlist_head       head;
1551         struct rcu_head         rcu;
1552 };
1553 
1554 /* - pseudo header */
1555 struct tcp4_pseudohdr {
1556         __be32          saddr;
1557         __be32          daddr;
1558         __u8            pad;
1559         __u8            protocol;
1560         __be16          len;
1561 };
1562 
1563 struct tcp6_pseudohdr {
1564         struct in6_addr saddr;
1565         struct in6_addr daddr;
1566         __be32          len;
1567         __be32          protocol;       /* including padding */
1568 };
1569 
1570 union tcp_md5sum_block {
1571         struct tcp4_pseudohdr ip4;
1572 #if IS_ENABLED(CONFIG_IPV6)
1573         struct tcp6_pseudohdr ip6;
1574 #endif
1575 };
1576 
1577 /* - pool: digest algorithm, hash description and scratch buffer */
1578 struct tcp_md5sig_pool {
1579         struct ahash_request    *md5_req;
1580         void                    *scratch;
1581 };
1582 
1583 /* - functions */
1584 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1585                         const struct sock *sk, const struct sk_buff *skb);
1586 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1587                    int family, u8 prefixlen, const u8 *newkey, u8 newkeylen,
1588                    gfp_t gfp);
1589 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1590                    int family, u8 prefixlen);
1591 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1592                                          const struct sock *addr_sk);
1593 
1594 #ifdef CONFIG_TCP_MD5SIG
1595 #include <linux/jump_label.h>
1596 extern struct static_key_false tcp_md5_needed;
1597 struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk,
1598                                            const union tcp_md5_addr *addr,
1599                                            int family);
1600 static inline struct tcp_md5sig_key *
1601 tcp_md5_do_lookup(const struct sock *sk,
1602                   const union tcp_md5_addr *addr,
1603                   int family)
1604 {
1605         if (!static_branch_unlikely(&tcp_md5_needed))
1606                 return NULL;
1607         return __tcp_md5_do_lookup(sk, addr, family);
1608 }
1609 
1610 #define tcp_twsk_md5_key(twsk)  ((twsk)->tw_md5_key)
1611 #else
1612 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1613                                          const union tcp_md5_addr *addr,
1614                                          int family)
1615 {
1616         return NULL;
1617 }
1618 #define tcp_twsk_md5_key(twsk)  NULL
1619 #endif
1620 
1621 bool tcp_alloc_md5sig_pool(void);
1622 
1623 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1624 static inline void tcp_put_md5sig_pool(void)
1625 {
1626         local_bh_enable();
1627 }
1628 
1629 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1630                           unsigned int header_len);
1631 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1632                      const struct tcp_md5sig_key *key);
1633 
1634 /* From tcp_fastopen.c */
1635 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1636                             struct tcp_fastopen_cookie *cookie);
1637 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1638                             struct tcp_fastopen_cookie *cookie, bool syn_lost,
1639                             u16 try_exp);
1640 struct tcp_fastopen_request {
1641         /* Fast Open cookie. Size 0 means a cookie request */
1642         struct tcp_fastopen_cookie      cookie;
1643         struct msghdr                   *data;  /* data in MSG_FASTOPEN */
1644         size_t                          size;
1645         int                             copied; /* queued in tcp_connect() */
1646         struct ubuf_info                *uarg;
1647 };
1648 void tcp_free_fastopen_req(struct tcp_sock *tp);
1649 void tcp_fastopen_destroy_cipher(struct sock *sk);
1650 void tcp_fastopen_ctx_destroy(struct net *net);
1651 int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
1652                               void *primary_key, void *backup_key);
1653 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1654 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1655                               struct request_sock *req,
1656                               struct tcp_fastopen_cookie *foc,
1657                               const struct dst_entry *dst);
1658 void tcp_fastopen_init_key_once(struct net *net);
1659 bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
1660                              struct tcp_fastopen_cookie *cookie);
1661 bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1662 #define TCP_FASTOPEN_KEY_LENGTH sizeof(siphash_key_t)
1663 #define TCP_FASTOPEN_KEY_MAX 2
1664 #define TCP_FASTOPEN_KEY_BUF_LENGTH \
1665         (TCP_FASTOPEN_KEY_LENGTH * TCP_FASTOPEN_KEY_MAX)
1666 
1667 /* Fastopen key context */
1668 struct tcp_fastopen_context {
1669         siphash_key_t   key[TCP_FASTOPEN_KEY_MAX];
1670         int             num;
1671         struct rcu_head rcu;
1672 };
1673 
1674 extern unsigned int sysctl_tcp_fastopen_blackhole_timeout;
1675 void tcp_fastopen_active_disable(struct sock *sk);
1676 bool tcp_fastopen_active_should_disable(struct sock *sk);
1677 void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
1678 void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired);
1679 
1680 /* Caller needs to wrap with rcu_read_(un)lock() */
1681 static inline
1682 struct tcp_fastopen_context *tcp_fastopen_get_ctx(const struct sock *sk)
1683 {
1684         struct tcp_fastopen_context *ctx;
1685 
1686         ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx);
1687         if (!ctx)
1688                 ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx);
1689         return ctx;
1690 }
1691 
1692 static inline
1693 bool tcp_fastopen_cookie_match(const struct tcp_fastopen_cookie *foc,
1694                                const struct tcp_fastopen_cookie *orig)
1695 {
1696         if (orig->len == TCP_FASTOPEN_COOKIE_SIZE &&
1697             orig->len == foc->len &&
1698             !memcmp(orig->val, foc->val, foc->len))
1699                 return true;
1700         return false;
1701 }
1702 
1703 static inline
1704 int tcp_fastopen_context_len(const struct tcp_fastopen_context *ctx)
1705 {
1706         return ctx->num;
1707 }
1708 
1709 /* Latencies incurred by various limits for a sender. They are
1710  * chronograph-like stats that are mutually exclusive.
1711  */
1712 enum tcp_chrono {
1713         TCP_CHRONO_UNSPEC,
1714         TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1715         TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1716         TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1717         __TCP_CHRONO_MAX,
1718 };
1719 
1720 void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1721 void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1722 
1723 /* This helper is needed, because skb->tcp_tsorted_anchor uses
1724  * the same memory storage than skb->destructor/_skb_refdst
1725  */
1726 static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb)
1727 {
1728         skb->destructor = NULL;
1729         skb->_skb_refdst = 0UL;
1730 }
1731 
1732 #define tcp_skb_tsorted_save(skb) {             \
1733         unsigned long _save = skb->_skb_refdst; \
1734         skb->_skb_refdst = 0UL;
1735 
1736 #define tcp_skb_tsorted_restore(skb)            \
1737         skb->_skb_refdst = _save;               \
1738 }
1739 
1740 void tcp_write_queue_purge(struct sock *sk);
1741 
1742 static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk)
1743 {
1744         return skb_rb_first(&sk->tcp_rtx_queue);
1745 }
1746 
1747 static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk)
1748 {
1749         return skb_rb_last(&sk->tcp_rtx_queue);
1750 }
1751 
1752 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1753 {
1754         return skb_peek(&sk->sk_write_queue);
1755 }
1756 
1757 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1758 {
1759         return skb_peek_tail(&sk->sk_write_queue);
1760 }
1761 
1762 #define tcp_for_write_queue_from_safe(skb, tmp, sk)                     \
1763         skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1764 
1765 static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1766 {
1767         return skb_peek(&sk->sk_write_queue);
1768 }
1769 
1770 static inline bool tcp_skb_is_last(const struct sock *sk,
1771                                    const struct sk_buff *skb)
1772 {
1773         return skb_queue_is_last(&sk->sk_write_queue, skb);
1774 }
1775 
1776 static inline bool tcp_write_queue_empty(const struct sock *sk)
1777 {
1778         return skb_queue_empty(&sk->sk_write_queue);
1779 }
1780 
1781 static inline bool tcp_rtx_queue_empty(const struct sock *sk)
1782 {
1783         return RB_EMPTY_ROOT(&sk->tcp_rtx_queue);
1784 }
1785 
1786 static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk)
1787 {
1788         return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk);
1789 }
1790 
1791 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1792 {
1793         __skb_queue_tail(&sk->sk_write_queue, skb);
1794 
1795         /* Queue it, remembering where we must start sending. */
1796         if (sk->sk_write_queue.next == skb)
1797                 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
1798 }
1799 
1800 /* Insert new before skb on the write queue of sk.  */
1801 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1802                                                   struct sk_buff *skb,
1803                                                   struct sock *sk)
1804 {
1805         __skb_queue_before(&sk->sk_write_queue, skb, new);
1806 }
1807 
1808 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1809 {
1810         tcp_skb_tsorted_anchor_cleanup(skb);
1811         __skb_unlink(skb, &sk->sk_write_queue);
1812 }
1813 
1814 void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb);
1815 
1816 static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk)
1817 {
1818         tcp_skb_tsorted_anchor_cleanup(skb);
1819         rb_erase(&skb->rbnode, &sk->tcp_rtx_queue);
1820 }
1821 
1822 static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk)
1823 {
1824         list_del(&skb->tcp_tsorted_anchor);
1825         tcp_rtx_queue_unlink(skb, sk);
1826         sk_wmem_free_skb(sk, skb);
1827 }
1828 
1829 static inline void tcp_push_pending_frames(struct sock *sk)
1830 {
1831         if (tcp_send_head(sk)) {
1832                 struct tcp_sock *tp = tcp_sk(sk);
1833 
1834                 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1835         }
1836 }
1837 
1838 /* Start sequence of the skb just after the highest skb with SACKed
1839  * bit, valid only if sacked_out > 0 or when the caller has ensured
1840  * validity by itself.
1841  */
1842 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1843 {
1844         if (!tp->sacked_out)
1845                 return tp->snd_una;
1846 
1847         if (tp->highest_sack == NULL)
1848                 return tp->snd_nxt;
1849 
1850         return TCP_SKB_CB(tp->highest_sack)->seq;
1851 }
1852 
1853 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1854 {
1855         tcp_sk(sk)->highest_sack = skb_rb_next(skb);
1856 }
1857 
1858 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1859 {
1860         return tcp_sk(sk)->highest_sack;
1861 }
1862 
1863 static inline void tcp_highest_sack_reset(struct sock *sk)
1864 {
1865         tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk);
1866 }
1867 
1868 /* Called when old skb is about to be deleted and replaced by new skb */
1869 static inline void tcp_highest_sack_replace(struct sock *sk,
1870                                             struct sk_buff *old,
1871                                             struct sk_buff *new)
1872 {
1873         if (old == tcp_highest_sack(sk))
1874                 tcp_sk(sk)->highest_sack = new;
1875 }
1876 
1877 /* This helper checks if socket has IP_TRANSPARENT set */
1878 static inline bool inet_sk_transparent(const struct sock *sk)
1879 {
1880         switch (sk->sk_state) {
1881         case TCP_TIME_WAIT:
1882                 return inet_twsk(sk)->tw_transparent;
1883         case TCP_NEW_SYN_RECV:
1884                 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1885         }
1886         return inet_sk(sk)->transparent;
1887 }
1888 
1889 /* Determines whether this is a thin stream (which may suffer from
1890  * increased latency). Used to trigger latency-reducing mechanisms.
1891  */
1892 static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1893 {
1894         return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1895 }
1896 
1897 /* /proc */
1898 enum tcp_seq_states {
1899         TCP_SEQ_STATE_LISTENING,
1900         TCP_SEQ_STATE_ESTABLISHED,
1901 };
1902 
1903 void *tcp_seq_start(struct seq_file *seq, loff_t *pos);
1904 void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
1905 void tcp_seq_stop(struct seq_file *seq, void *v);
1906 
1907 struct tcp_seq_afinfo {
1908         sa_family_t                     family;
1909 };
1910 
1911 struct tcp_iter_state {
1912         struct seq_net_private  p;
1913         enum tcp_seq_states     state;
1914         struct sock             *syn_wait_sk;
1915         int                     bucket, offset, sbucket, num;
1916         loff_t                  last_pos;
1917 };
1918 
1919 extern struct request_sock_ops tcp_request_sock_ops;
1920 extern struct request_sock_ops tcp6_request_sock_ops;
1921 
1922 void tcp_v4_destroy_sock(struct sock *sk);
1923 
1924 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1925                                 netdev_features_t features);
1926 struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb);
1927 int tcp_gro_complete(struct sk_buff *skb);
1928 
1929 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1930 
1931 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1932 {
1933         struct net *net = sock_net((struct sock *)tp);
1934         return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat;
1935 }
1936 
1937 /* @wake is one when sk_stream_write_space() calls us.
1938  * This sends EPOLLOUT only if notsent_bytes is half the limit.
1939  * This mimics the strategy used in sock_def_write_space().
1940  */
1941 static inline bool tcp_stream_memory_free(const struct sock *sk, int wake)
1942 {
1943         const struct tcp_sock *tp = tcp_sk(sk);
1944         u32 notsent_bytes = READ_ONCE(tp->write_seq) -
1945                             READ_ONCE(tp->snd_nxt);
1946 
1947         return (notsent_bytes << wake) < tcp_notsent_lowat(tp);
1948 }
1949 
1950 #ifdef CONFIG_PROC_FS
1951 int tcp4_proc_init(void);
1952 void tcp4_proc_exit(void);
1953 #endif
1954 
1955 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
1956 int tcp_conn_request(struct request_sock_ops *rsk_ops,
1957                      const struct tcp_request_sock_ops *af_ops,
1958                      struct sock *sk, struct sk_buff *skb);
1959 
1960 /* TCP af-specific functions */
1961 struct tcp_sock_af_ops {
1962 #ifdef CONFIG_TCP_MD5SIG
1963         struct tcp_md5sig_key   *(*md5_lookup) (const struct sock *sk,
1964                                                 const struct sock *addr_sk);
1965         int             (*calc_md5_hash)(char *location,
1966                                          const struct tcp_md5sig_key *md5,
1967                                          const struct sock *sk,
1968                                          const struct sk_buff *skb);
1969         int             (*md5_parse)(struct sock *sk,
1970                                      int optname,
1971                                      char __user *optval,
1972                                      int optlen);
1973 #endif
1974 };
1975 
1976 struct tcp_request_sock_ops {
1977         u16 mss_clamp;
1978 #ifdef CONFIG_TCP_MD5SIG
1979         struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
1980                                                  const struct sock *addr_sk);
1981         int             (*calc_md5_hash) (char *location,
1982                                           const struct tcp_md5sig_key *md5,
1983                                           const struct sock *sk,
1984                                           const struct sk_buff *skb);
1985 #endif
1986         void (*init_req)(struct request_sock *req,
1987                          const struct sock *sk_listener,
1988                          struct sk_buff *skb);
1989 #ifdef CONFIG_SYN_COOKIES
1990         __u32 (*cookie_init_seq)(const struct sk_buff *skb,
1991                                  __u16 *mss);
1992 #endif
1993         struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl,
1994                                        const struct request_sock *req);
1995         u32 (*init_seq)(const struct sk_buff *skb);
1996         u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
1997         int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
1998                            struct flowi *fl, struct request_sock *req,
1999                            struct tcp_fastopen_cookie *foc,
2000                            enum tcp_synack_type synack_type);
2001 };
2002 
2003 #ifdef CONFIG_SYN_COOKIES
2004 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2005                                          const struct sock *sk, struct sk_buff *skb,
2006                                          __u16 *mss)
2007 {
2008         tcp_synq_overflow(sk);
2009         __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
2010         return ops->cookie_init_seq(skb, mss);
2011 }
2012 #else
2013 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2014                                          const struct sock *sk, struct sk_buff *skb,
2015                                          __u16 *mss)
2016 {
2017         return 0;
2018 }
2019 #endif
2020 
2021 int tcpv4_offload_init(void);
2022 
2023 void tcp_v4_init(void);
2024 void tcp_init(void);
2025 
2026 /* tcp_recovery.c */
2027 void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb);
2028 void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced);
2029 extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb,
2030                                 u32 reo_wnd);
2031 extern void tcp_rack_mark_lost(struct sock *sk);
2032 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
2033                              u64 xmit_time);
2034 extern void tcp_rack_reo_timeout(struct sock *sk);
2035 extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs);
2036 
2037 /* At how many usecs into the future should the RTO fire? */
2038 static inline s64 tcp_rto_delta_us(const struct sock *sk)
2039 {
2040         const struct sk_buff *skb = tcp_rtx_queue_head(sk);
2041         u32 rto = inet_csk(sk)->icsk_rto;
2042         u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + jiffies_to_usecs(rto);
2043 
2044         return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
2045 }
2046 
2047 /*
2048  * Save and compile IPv4 options, return a pointer to it
2049  */
2050 static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net,
2051                                                          struct sk_buff *skb)
2052 {
2053         const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
2054         struct ip_options_rcu *dopt = NULL;
2055 
2056         if (opt->optlen) {
2057                 int opt_size = sizeof(*dopt) + opt->optlen;
2058 
2059                 dopt = kmalloc(opt_size, GFP_ATOMIC);
2060                 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) {
2061                         kfree(dopt);
2062                         dopt = NULL;
2063                 }
2064         }
2065         return dopt;
2066 }
2067 
2068 /* locally generated TCP pure ACKs have skb->truesize == 2
2069  * (check tcp_send_ack() in net/ipv4/tcp_output.c )
2070  * This is much faster than dissecting the packet to find out.
2071  * (Think of GRE encapsulations, IPv4, IPv6, ...)
2072  */
2073 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
2074 {
2075         return skb->truesize == 2;
2076 }
2077 
2078 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
2079 {
2080         skb->truesize = 2;
2081 }
2082 
2083 static inline int tcp_inq(struct sock *sk)
2084 {
2085         struct tcp_sock *tp = tcp_sk(sk);
2086         int answ;
2087 
2088         if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
2089                 answ = 0;
2090         } else if (sock_flag(sk, SOCK_URGINLINE) ||
2091                    !tp->urg_data ||
2092                    before(tp->urg_seq, tp->copied_seq) ||
2093                    !before(tp->urg_seq, tp->rcv_nxt)) {
2094 
2095                 answ = tp->rcv_nxt - tp->copied_seq;
2096 
2097                 /* Subtract 1, if FIN was received */
2098                 if (answ && sock_flag(sk, SOCK_DONE))
2099                         answ--;
2100         } else {
2101                 answ = tp->urg_seq - tp->copied_seq;
2102         }
2103 
2104         return answ;
2105 }
2106 
2107 int tcp_peek_len(struct socket *sock);
2108 
2109 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
2110 {
2111         u16 segs_in;
2112 
2113         segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
2114         tp->segs_in += segs_in;
2115         if (skb->len > tcp_hdrlen(skb))
2116                 tp->data_segs_in += segs_in;
2117 }
2118 
2119 /*
2120  * TCP listen path runs lockless.
2121  * We forced "struct sock" to be const qualified to make sure
2122  * we don't modify one of its field by mistake.
2123  * Here, we increment sk_drops which is an atomic_t, so we can safely
2124  * make sock writable again.
2125  */
2126 static inline void tcp_listendrop(const struct sock *sk)
2127 {
2128         atomic_inc(&((struct sock *)sk)->sk_drops);
2129         __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2130 }
2131 
2132 enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
2133 
2134 /*
2135  * Interface for adding Upper Level Protocols over TCP
2136  */
2137 
2138 #define TCP_ULP_NAME_MAX        16
2139 #define TCP_ULP_MAX             128
2140 #define TCP_ULP_BUF_MAX         (TCP_ULP_NAME_MAX*TCP_ULP_MAX)
2141 
2142 struct tcp_ulp_ops {
2143         struct list_head        list;
2144 
2145         /* initialize ulp */
2146         int (*init)(struct sock *sk);
2147         /* update ulp */
2148         void (*update)(struct sock *sk, struct proto *p,
2149                        void (*write_space)(struct sock *sk));
2150         /* cleanup ulp */
2151         void (*release)(struct sock *sk);
2152         /* diagnostic */
2153         int (*get_info)(const struct sock *sk, struct sk_buff *skb);
2154         size_t (*get_info_size)(const struct sock *sk);
2155 
2156         char            name[TCP_ULP_NAME_MAX];
2157         struct module   *owner;
2158 };
2159 int tcp_register_ulp(struct tcp_ulp_ops *type);
2160 void tcp_unregister_ulp(struct tcp_ulp_ops *type);
2161 int tcp_set_ulp(struct sock *sk, const char *name);
2162 void tcp_get_available_ulp(char *buf, size_t len);
2163 void tcp_cleanup_ulp(struct sock *sk);
2164 void tcp_update_ulp(struct sock *sk, struct proto *p,
2165                     void (*write_space)(struct sock *sk));
2166 
2167 #define MODULE_ALIAS_TCP_ULP(name)                              \
2168         __MODULE_INFO(alias, alias_userspace, name);            \
2169         __MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name)
2170 
2171 struct sk_msg;
2172 struct sk_psock;
2173 
2174 int tcp_bpf_init(struct sock *sk);
2175 void tcp_bpf_reinit(struct sock *sk);
2176 int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg, u32 bytes,
2177                           int flags);
2178 int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
2179                     int nonblock, int flags, int *addr_len);
2180 int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock,
2181                       struct msghdr *msg, int len, int flags);
2182 
2183 /* Call BPF_SOCK_OPS program that returns an int. If the return value
2184  * is < 0, then the BPF op failed (for example if the loaded BPF
2185  * program does not support the chosen operation or there is no BPF
2186  * program loaded).
2187  */
2188 #ifdef CONFIG_BPF
2189 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2190 {
2191         struct bpf_sock_ops_kern sock_ops;
2192         int ret;
2193 
2194         memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
2195         if (sk_fullsock(sk)) {
2196                 sock_ops.is_fullsock = 1;
2197                 sock_owned_by_me(sk);
2198         }
2199 
2200         sock_ops.sk = sk;
2201         sock_ops.op = op;
2202         if (nargs > 0)
2203                 memcpy(sock_ops.args, args, nargs * sizeof(*args));
2204 
2205         ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
2206         if (ret == 0)
2207                 ret = sock_ops.reply;
2208         else
2209                 ret = -1;
2210         return ret;
2211 }
2212 
2213 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2214 {
2215         u32 args[2] = {arg1, arg2};
2216 
2217         return tcp_call_bpf(sk, op, 2, args);
2218 }
2219 
2220 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2221                                     u32 arg3)
2222 {
2223         u32 args[3] = {arg1, arg2, arg3};
2224 
2225         return tcp_call_bpf(sk, op, 3, args);
2226 }
2227 
2228 #else
2229 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2230 {
2231         return -EPERM;
2232 }
2233 
2234 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2235 {
2236         return -EPERM;
2237 }
2238 
2239 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2240                                     u32 arg3)
2241 {
2242         return -EPERM;
2243 }
2244 
2245 #endif
2246 
2247 static inline u32 tcp_timeout_init(struct sock *sk)
2248 {
2249         int timeout;
2250 
2251         timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL);
2252 
2253         if (timeout <= 0)
2254                 timeout = TCP_TIMEOUT_INIT;
2255         return timeout;
2256 }
2257 
2258 static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
2259 {
2260         int rwnd;
2261 
2262         rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL);
2263 
2264         if (rwnd < 0)
2265                 rwnd = 0;
2266         return rwnd;
2267 }
2268 
2269 static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
2270 {
2271         return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1);
2272 }
2273 
2274 static inline void tcp_bpf_rtt(struct sock *sk)
2275 {
2276         if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_RTT_CB_FLAG))
2277                 tcp_call_bpf(sk, BPF_SOCK_OPS_RTT_CB, 0, NULL);
2278 }
2279 
2280 #if IS_ENABLED(CONFIG_SMC)
2281 extern struct static_key_false tcp_have_smc;
2282 #endif
2283 
2284 #if IS_ENABLED(CONFIG_TLS_DEVICE)
2285 void clean_acked_data_enable(struct inet_connection_sock *icsk,
2286                              void (*cad)(struct sock *sk, u32 ack_seq));
2287 void clean_acked_data_disable(struct inet_connection_sock *icsk);
2288 void clean_acked_data_flush(void);
2289 #endif
2290 
2291 DECLARE_STATIC_KEY_FALSE(tcp_tx_delay_enabled);
2292 static inline void tcp_add_tx_delay(struct sk_buff *skb,
2293                                     const struct tcp_sock *tp)
2294 {
2295         if (static_branch_unlikely(&tcp_tx_delay_enabled))
2296                 skb->skb_mstamp_ns += (u64)tp->tcp_tx_delay * NSEC_PER_USEC;
2297 }
2298 
2299 /* Compute Earliest Departure Time for some control packets
2300  * like ACK or RST for TIME_WAIT or non ESTABLISHED sockets.
2301  */
2302 static inline u64 tcp_transmit_time(const struct sock *sk)
2303 {
2304         if (static_branch_unlikely(&tcp_tx_delay_enabled)) {
2305                 u32 delay = (sk->sk_state == TCP_TIME_WAIT) ?
2306                         tcp_twsk(sk)->tw_tx_delay : tcp_sk(sk)->tcp_tx_delay;
2307 
2308                 return tcp_clock_ns() + (u64)delay * NSEC_PER_USEC;
2309         }
2310         return 0;
2311 }
2312 
2313 #endif  /* _TCP_H */
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root/include/net/tcp.h

INCLUDED FROM

DEFINITIONS
