include/linux/tcp.h

   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 protocol.
   8  *
   9  * Version:     @(#)tcp.h       1.0.2   04/28/93
  10  *
  11  * Author:      Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  */
  13 #ifndef _LINUX_TCP_H
  14 #define _LINUX_TCP_H
  15
  16
  17 #include <linux/skbuff.h>
  18 #include <linux/win_minmax.h>
  19 #include <net/sock.h>
  20 #include <net/inet_connection_sock.h>
  21 #include <net/inet_timewait_sock.h>
  22 #include <uapi/linux/tcp.h>
  23
  24 static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
  25 {
  26         return (struct tcphdr *)skb_transport_header(skb);
  27 }
  28
  29 static inline unsigned int __tcp_hdrlen(const struct tcphdr *th)
  30 {
  31         return th->doff * 4;
  32 }
  33
  34 static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
  35 {
  36         return __tcp_hdrlen(tcp_hdr(skb));
  37 }
  38
  39 static inline struct tcphdr *inner_tcp_hdr(const struct sk_buff *skb)
  40 {
  41         return (struct tcphdr *)skb_inner_transport_header(skb);
  42 }
  43
  44 static inline unsigned int inner_tcp_hdrlen(const struct sk_buff *skb)
  45 {
  46         return inner_tcp_hdr(skb)->doff * 4;
  47 }
  48
  49 /**
  50  * skb_tcp_all_headers - Returns size of all headers for a TCP packet
  51  * @skb: buffer
  52  *
  53  * Used in TX path, for a packet known to be a TCP one.
  54  *
  55  * if (skb_is_gso(skb)) {
  56  *         int hlen = skb_tcp_all_headers(skb);
  57  *         ...
  58  */
  59 static inline int skb_tcp_all_headers(const struct sk_buff *skb)
  60 {
  61         return skb_transport_offset(skb) + tcp_hdrlen(skb);
  62 }
  63
  64 /**
  65  * skb_inner_tcp_all_headers - Returns size of all headers for an encap TCP packet
  66  * @skb: buffer
  67  *
  68  * Used in TX path, for a packet known to be a TCP one.
  69  *
  70  * if (skb_is_gso(skb) && skb->encapsulation) {
  71  *         int hlen = skb_inner_tcp_all_headers(skb);
  72  *         ...
  73  */
  74 static inline int skb_inner_tcp_all_headers(const struct sk_buff *skb)
  75 {
  76         return skb_inner_transport_offset(skb) + inner_tcp_hdrlen(skb);
  77 }
  78
  79 static inline unsigned int tcp_optlen(const struct sk_buff *skb)
  80 {
  81         return (tcp_hdr(skb)->doff - 5) * 4;
  82 }
  83
  84 /* TCP Fast Open */
  85 #define TCP_FASTOPEN_COOKIE_MIN 4       /* Min Fast Open Cookie size in bytes */
  86 #define TCP_FASTOPEN_COOKIE_MAX 16      /* Max Fast Open Cookie size in bytes */
  87 #define TCP_FASTOPEN_COOKIE_SIZE 8      /* the size employed by this impl. */
  88
  89 /* TCP Fast Open Cookie as stored in memory */
  90 struct tcp_fastopen_cookie {
  91         __le64  val[DIV_ROUND_UP(TCP_FASTOPEN_COOKIE_MAX, sizeof(u64))];
  92         s8      len;
  93         bool    exp;    /* In RFC6994 experimental option format */
  94 };
  95
  96 /* This defines a selective acknowledgement block. */
  97 struct tcp_sack_block_wire {
  98         __be32  start_seq;
  99         __be32  end_seq;
 100 };
 101
 102 struct tcp_sack_block {
 103         u32     start_seq;
 104         u32     end_seq;
 105 };
 106
 107 /*These are used to set the sack_ok field in struct tcp_options_received */
 108 #define TCP_SACK_SEEN     (1 << 0)   /*1 = peer is SACK capable, */
 109 #define TCP_DSACK_SEEN    (1 << 2)   /*1 = DSACK was received from peer*/
 110
 111 struct tcp_options_received {
 112 /*      PAWS/RTTM data  */
 113         int     ts_recent_stamp;/* Time we stored ts_recent (for aging) */
 114         u32     ts_recent;      /* Time stamp to echo next              */
 115         u32     rcv_tsval;      /* Time stamp value                     */
 116         u32     rcv_tsecr;      /* Time stamp echo reply                */
 117         u16     saw_tstamp : 1, /* Saw TIMESTAMP on last packet         */
 118                 tstamp_ok : 1,  /* TIMESTAMP seen on SYN packet         */
 119                 dsack : 1,      /* D-SACK is scheduled                  */
 120                 wscale_ok : 1,  /* Wscale seen on SYN packet            */
 121                 sack_ok : 3,    /* SACK seen on SYN packet              */
 122                 smc_ok : 1,     /* SMC seen on SYN packet               */
 123                 snd_wscale : 4, /* Window scaling received from sender  */
 124                 rcv_wscale : 4; /* Window scaling to send to receiver   */
 125         u8      saw_unknown:1,  /* Received unknown option              */
 126                 unused:7;
 127         u8      num_sacks;      /* Number of SACK blocks                */
 128         u16     user_mss;       /* mss requested by user in ioctl       */
 129         u16     mss_clamp;      /* Maximal mss, negotiated at connection setup */
 130 };
 131
 132 static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
 133 {
 134         rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
 135         rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
 136 #if IS_ENABLED(CONFIG_SMC)
 137         rx_opt->smc_ok = 0;
 138 #endif
 139 }
 140
 141 /* This is the max number of SACKS that we'll generate and process. It's safe
 142  * to increase this, although since:
 143  *   size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
 144  * only four options will fit in a standard TCP header */
 145 #define TCP_NUM_SACKS 4
 146
 147 struct tcp_request_sock_ops;
 148
 149 struct tcp_request_sock {
 150         struct inet_request_sock        req;
 151         const struct tcp_request_sock_ops *af_specific;
 152         u64                             snt_synack; /* first SYNACK sent time */
 153         bool                            tfo_listener;
 154         bool                            is_mptcp;
 155         bool                            req_usec_ts;
 156 #if IS_ENABLED(CONFIG_MPTCP)
 157         bool                            drop_req;
 158 #endif
 159         u32                             txhash;
 160         u32                             rcv_isn;
 161         u32                             snt_isn;
 162         u32                             ts_off;
 163         u32                             last_oow_ack_time; /* last SYNACK */
 164         u32                             rcv_nxt; /* the ack # by SYNACK. For
 165                                                   * FastOpen it's the seq#
 166                                                   * after data-in-SYN.
 167                                                   */
 168         u8                              syn_tos;
 169 #ifdef CONFIG_TCP_AO
 170         u8                              ao_keyid;
 171         u8                              ao_rcv_next;
 172         bool                            used_tcp_ao;
 173 #endif
 174 };
 175
 176 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
 177 {
 178         return (struct tcp_request_sock *)req;
 179 }
 180
 181 static inline bool tcp_rsk_used_ao(const struct request_sock *req)
 182 {
 183 #ifndef CONFIG_TCP_AO
 184         return false;
 185 #else
 186         return tcp_rsk(req)->used_tcp_ao;
 187 #endif
 188 }
 189
 190 #define TCP_RMEM_TO_WIN_SCALE 8
 191
 192 struct tcp_sock {
 193         /* inet_connection_sock has to be the first member of tcp_sock */
 194         struct inet_connection_sock     inet_conn;
 195         u16     tcp_header_len; /* Bytes of tcp header to send          */
 196         u16     gso_segs;       /* Max number of segs per GSO packet    */
 197
 198 /*
 199  *      Header prediction flags
 200  *      0x5?10 << 16 + snd_wnd in net byte order
 201  */
 202         __be32  pred_flags;
 203
 204 /*
 205  *      RFC793 variables by their proper names. This means you can
 206  *      read the code and the spec side by side (and laugh ...)
 207  *      See RFC793 and RFC1122. The RFC writes these in capitals.
 208  */
 209         u64     bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived
 210                                  * sum(delta(rcv_nxt)), or how many bytes
 211                                  * were acked.
 212                                  */
 213         u32     segs_in;        /* RFC4898 tcpEStatsPerfSegsIn
 214                                  * total number of segments in.
 215                                  */
 216         u32     data_segs_in;   /* RFC4898 tcpEStatsPerfDataSegsIn
 217                                  * total number of data segments in.
 218                                  */
 219         u32     rcv_nxt;        /* What we want to receive next         */
 220         u32     copied_seq;     /* Head of yet unread data              */
 221         u32     rcv_wup;        /* rcv_nxt on last window update sent   */
 222         u32     snd_nxt;        /* Next sequence we send                */
 223         u32     segs_out;       /* RFC4898 tcpEStatsPerfSegsOut
 224                                  * The total number of segments sent.
 225                                  */
 226         u32     data_segs_out;  /* RFC4898 tcpEStatsPerfDataSegsOut
 227                                  * total number of data segments sent.
 228                                  */
 229         u64     bytes_sent;     /* RFC4898 tcpEStatsPerfHCDataOctetsOut
 230                                  * total number of data bytes sent.
 231                                  */
 232         u64     bytes_acked;    /* RFC4898 tcpEStatsAppHCThruOctetsAcked
 233                                  * sum(delta(snd_una)), or how many bytes
 234                                  * were acked.
 235                                  */
 236         u32     dsack_dups;     /* RFC4898 tcpEStatsStackDSACKDups
 237                                  * total number of DSACK blocks received
 238                                  */
 239         u32     snd_una;        /* First byte we want an ack for        */
 240         u32     snd_sml;        /* Last byte of the most recently transmitted small packet */
 241         u32     rcv_tstamp;     /* timestamp of last received ACK (for keepalives) */
 242         u32     lsndtime;       /* timestamp of last sent data packet (for restart window) */
 243         u32     last_oow_ack_time;  /* timestamp of last out-of-window ACK */
 244         u32     compressed_ack_rcv_nxt;
 245
 246         u32     tsoffset;       /* timestamp offset */
 247
 248         struct list_head tsq_node; /* anchor in tsq_tasklet.head list */
 249         struct list_head tsorted_sent_queue; /* time-sorted sent but un-SACKed skbs */
 250
 251         u32     snd_wl1;        /* Sequence for window update           */
 252         u32     snd_wnd;        /* The window we expect to receive      */
 253         u32     max_window;     /* Maximal window ever seen from peer   */
 254         u32     mss_cache;      /* Cached effective mss, not including SACKS */
 255
 256         u32     window_clamp;   /* Maximal window to advertise          */
 257         u32     rcv_ssthresh;   /* Current window clamp                 */
 258         u8      scaling_ratio;  /* see tcp_win_from_space() */
 259         /* Information of the most recently (s)acked skb */
 260         struct tcp_rack {
 261                 u64 mstamp; /* (Re)sent time of the skb */
 262                 u32 rtt_us;  /* Associated RTT */
 263                 u32 end_seq; /* Ending TCP sequence of the skb */
 264                 u32 last_delivered; /* tp->delivered at last reo_wnd adj */
 265                 u8 reo_wnd_steps;   /* Allowed reordering window */
 266 #define TCP_RACK_RECOVERY_THRESH 16
 267                 u8 reo_wnd_persist:5, /* No. of recovery since last adj */
 268                    dsack_seen:1, /* Whether DSACK seen after last adj */
 269                    advanced:1;   /* mstamp advanced since last lost marking */
 270         } rack;
 271         u16     advmss;         /* Advertised MSS                       */
 272         u8      compressed_ack;
 273         u8      dup_ack_counter:2,
 274                 tlp_retrans:1,  /* TLP is a retransmission */
 275                 tcp_usec_ts:1, /* TSval values in usec */
 276                 unused:4;
 277         u32     chrono_start;   /* Start time in jiffies of a TCP chrono */
 278         u32     chrono_stat[3]; /* Time in jiffies for chrono_stat stats */
 279         u8      chrono_type:2,  /* current chronograph type */
 280                 rate_app_limited:1,  /* rate_{delivered,interval_us} limited? */
 281                 fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */
 282                 fastopen_no_cookie:1, /* Allow send/recv SYN+data without a cookie */
 283                 is_sack_reneg:1,    /* in recovery from loss with SACK reneg? */
 284                 fastopen_client_fail:2; /* reason why fastopen failed */
 285         u8      nonagle     : 4,/* Disable Nagle algorithm?             */
 286                 thin_lto    : 1,/* Use linear timeouts for thin streams */
 287                 recvmsg_inq : 1,/* Indicate # of bytes in queue upon recvmsg */
 288                 repair      : 1,
 289                 frto        : 1;/* F-RTO (RFC5682) activated in CA_Loss */
 290         u8      repair_queue;
 291         u8      save_syn:2,     /* Save headers of SYN packet */
 292                 syn_data:1,     /* SYN includes data */
 293                 syn_fastopen:1, /* SYN includes Fast Open option */
 294                 syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */
 295                 syn_fastopen_ch:1, /* Active TFO re-enabling probe */
 296                 syn_data_acked:1,/* data in SYN is acked by SYN-ACK */
 297                 is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */
 298         u32     tlp_high_seq;   /* snd_nxt at the time of TLP */
 299
 300         u32     tcp_tx_delay;   /* delay (in usec) added to TX packets */
 301         u64     tcp_wstamp_ns;  /* departure time for next sent data packet */
 302         u64     tcp_clock_cache; /* cache last tcp_clock_ns() (see tcp_mstamp_refresh()) */
 303
 304 /* RTT measurement */
 305         u64     tcp_mstamp;     /* most recent packet received/sent */
 306         u32     srtt_us;        /* smoothed round trip time << 3 in usecs */
 307         u32     mdev_us;        /* medium deviation                     */
 308         u32     mdev_max_us;    /* maximal mdev for the last rtt period */
 309         u32     rttvar_us;      /* smoothed mdev_max                    */
 310         u32     rtt_seq;        /* sequence number to update rttvar     */
 311         struct  minmax rtt_min;
 312
 313         u32     packets_out;    /* Packets which are "in flight"        */
 314         u32     retrans_out;    /* Retransmitted packets out            */
 315         u32     max_packets_out;  /* max packets_out in last window */
 316         u32     cwnd_usage_seq;  /* right edge of cwnd usage tracking flight */
 317
 318         u16     urg_data;       /* Saved octet of OOB data and control flags */
 319         u8      ecn_flags;      /* ECN status bits.                     */
 320         u8      keepalive_probes; /* num of allowed keep alive probes   */
 321         u32     reordering;     /* Packet reordering metric.            */
 322         u32     reord_seen;     /* number of data packet reordering events */
 323         u32     snd_up;         /* Urgent pointer               */
 324
 325 /*
 326  *      Options received (usually on last packet, some only on SYN packets).
 327  */
 328         struct tcp_options_received rx_opt;
 329
 330 /*
 331  *      Slow start and congestion control (see also Nagle, and Karn & Partridge)
 332  */
 333         u32     snd_ssthresh;   /* Slow start size threshold            */
 334         u32     snd_cwnd;       /* Sending congestion window            */
 335         u32     snd_cwnd_cnt;   /* Linear increase counter              */
 336         u32     snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
 337         u32     snd_cwnd_used;
 338         u32     snd_cwnd_stamp;
 339         u32     prior_cwnd;     /* cwnd right before starting loss recovery */
 340         u32     prr_delivered;  /* Number of newly delivered packets to
 341                                  * receiver in Recovery. */
 342         u32     prr_out;        /* Total number of pkts sent during Recovery. */
 343         u32     delivered;      /* Total data packets delivered incl. rexmits */
 344         u32     delivered_ce;   /* Like the above but only ECE marked packets */
 345         u32     lost;           /* Total data packets lost incl. rexmits */
 346         u32     app_limited;    /* limited until "delivered" reaches this val */
 347         u64     first_tx_mstamp;  /* start of window send phase */
 348         u64     delivered_mstamp; /* time we reached "delivered" */
 349         u32     rate_delivered;    /* saved rate sample: packets delivered */
 350         u32     rate_interval_us;  /* saved rate sample: time elapsed */
 351
 352         u32     rcv_wnd;        /* Current receiver window              */
 353         u32     write_seq;      /* Tail(+1) of data held in tcp send buffer */
 354         u32     notsent_lowat;  /* TCP_NOTSENT_LOWAT */
 355         u32     pushed_seq;     /* Last pushed seq, required to talk to windows */
 356         u32     lost_out;       /* Lost packets                 */
 357         u32     sacked_out;     /* SACK'd packets                       */
 358
 359         struct hrtimer  pacing_timer;
 360         struct hrtimer  compressed_ack_timer;
 361
 362         /* from STCP, retrans queue hinting */
 363         struct sk_buff* lost_skb_hint;
 364         struct sk_buff *retransmit_skb_hint;
 365
 366         /* OOO segments go in this rbtree. Socket lock must be held. */
 367         struct rb_root  out_of_order_queue;
 368         struct sk_buff  *ooo_last_skb; /* cache rb_last(out_of_order_queue) */
 369
 370         /* SACKs data, these 2 need to be together (see tcp_options_write) */
 371         struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
 372         struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
 373
 374         struct tcp_sack_block recv_sack_cache[4];
 375
 376         struct sk_buff *highest_sack;   /* skb just after the highest
 377                                          * skb with SACKed bit set
 378                                          * (validity guaranteed only if
 379                                          * sacked_out > 0)
 380                                          */
 381
 382         int     lost_cnt_hint;
 383
 384         u32     prior_ssthresh; /* ssthresh saved at recovery start     */
 385         u32     high_seq;       /* snd_nxt at onset of congestion       */
 386
 387         u32     retrans_stamp;  /* Timestamp of the last retransmit,
 388                                  * also used in SYN-SENT to remember stamp of
 389                                  * the first SYN. */
 390         u32     undo_marker;    /* snd_una upon a new recovery episode. */
 391         int     undo_retrans;   /* number of undoable retransmissions. */
 392         u64     bytes_retrans;  /* RFC4898 tcpEStatsPerfOctetsRetrans
 393                                  * Total data bytes retransmitted
 394                                  */
 395         u32     total_retrans;  /* Total retransmits for entire connection */
 396         u32     rto_stamp;      /* Start time (ms) of last CA_Loss recovery */
 397         u16     total_rto;      /* Total number of RTO timeouts, including
 398                                  * SYN/SYN-ACK and recurring timeouts.
 399                                  */
 400         u16     total_rto_recoveries;   /* Total number of RTO recoveries,
 401                                          * including any unfinished recovery.
 402                                          */
 403         u32     total_rto_time; /* ms spent in (completed) RTO recoveries. */
 404
 405         u32     urg_seq;        /* Seq of received urgent pointer */
 406         unsigned int            keepalive_time;   /* time before keep alive takes place */
 407         unsigned int            keepalive_intvl;  /* time interval between keep alive probes */
 408
 409         int                     linger2;
 410
 411
 412 /* Sock_ops bpf program related variables */
 413 #ifdef CONFIG_BPF
 414         u8      bpf_sock_ops_cb_flags;  /* Control calling BPF programs
 415                                          * values defined in uapi/linux/tcp.h
 416                                          */
 417         u8      bpf_chg_cc_inprogress:1; /* In the middle of
 418                                           * bpf_setsockopt(TCP_CONGESTION),
 419                                           * it is to avoid the bpf_tcp_cc->init()
 420                                           * to recur itself by calling
 421                                           * bpf_setsockopt(TCP_CONGESTION, "itself").
 422                                           */
 423 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) (TP->bpf_sock_ops_cb_flags & ARG)
 424 #else
 425 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) 0
 426 #endif
 427
 428         u16 timeout_rehash;     /* Timeout-triggered rehash attempts */
 429
 430         u32 rcv_ooopack; /* Received out-of-order packets, for tcpinfo */
 431
 432 /* Receiver side RTT estimation */
 433         u32 rcv_rtt_last_tsecr;
 434         struct {
 435                 u32     rtt_us;
 436                 u32     seq;
 437                 u64     time;
 438         } rcv_rtt_est;
 439
 440 /* Receiver queue space */
 441         struct {
 442                 u32     space;
 443                 u32     seq;
 444                 u64     time;
 445         } rcvq_space;
 446
 447 /* TCP-specific MTU probe information. */
 448         struct {
 449                 u32               probe_seq_start;
 450                 u32               probe_seq_end;
 451         } mtu_probe;
 452         u32     plb_rehash;     /* PLB-triggered rehash attempts */
 453         u32     mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
 454                            * while socket was owned by user.
 455                            */
 456 #if IS_ENABLED(CONFIG_MPTCP)
 457         bool    is_mptcp;
 458 #endif
 459 #if IS_ENABLED(CONFIG_SMC)
 460         bool    (*smc_hs_congested)(const struct sock *sk);
 461         bool    syn_smc;        /* SYN includes SMC */
 462 #endif
 463
 464 #if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
 465 /* TCP AF-Specific parts; only used by TCP-AO/MD5 Signature support so far */
 466         const struct tcp_sock_af_ops    *af_specific;
 467
 468 #ifdef CONFIG_TCP_MD5SIG
 469 /* TCP MD5 Signature Option information */
 470         struct tcp_md5sig_info  __rcu *md5sig_info;
 471 #endif
 472 #ifdef CONFIG_TCP_AO
 473         struct tcp_ao_info      __rcu *ao_info;
 474 #endif
 475 #endif
 476
 477 /* TCP fastopen related information */
 478         struct tcp_fastopen_request *fastopen_req;
 479         /* fastopen_rsk points to request_sock that resulted in this big
 480          * socket. Used to retransmit SYNACKs etc.
 481          */
 482         struct request_sock __rcu *fastopen_rsk;
 483         struct saved_syn *saved_syn;
 484 };
 485
 486 enum tsq_enum {
 487         TSQ_THROTTLED,
 488         TSQ_QUEUED,
 489         TCP_TSQ_DEFERRED,          /* tcp_tasklet_func() found socket was owned */
 490         TCP_WRITE_TIMER_DEFERRED,  /* tcp_write_timer() found socket was owned */
 491         TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
 492         TCP_MTU_REDUCED_DEFERRED,  /* tcp_v{4|6}_err() could not call
 493                                     * tcp_v{4|6}_mtu_reduced()
 494                                     */
 495         TCP_ACK_DEFERRED,          /* TX pure ack is deferred */
 496 };
 497
 498 enum tsq_flags {
 499         TSQF_THROTTLED                  = BIT(TSQ_THROTTLED),
 500         TSQF_QUEUED                     = BIT(TSQ_QUEUED),
 501         TCPF_TSQ_DEFERRED               = BIT(TCP_TSQ_DEFERRED),
 502         TCPF_WRITE_TIMER_DEFERRED       = BIT(TCP_WRITE_TIMER_DEFERRED),
 503         TCPF_DELACK_TIMER_DEFERRED      = BIT(TCP_DELACK_TIMER_DEFERRED),
 504         TCPF_MTU_REDUCED_DEFERRED       = BIT(TCP_MTU_REDUCED_DEFERRED),
 505         TCPF_ACK_DEFERRED               = BIT(TCP_ACK_DEFERRED),
 506 };
 507
 508 #define tcp_sk(ptr) container_of_const(ptr, struct tcp_sock, inet_conn.icsk_inet.sk)
 509
 510 /* Variant of tcp_sk() upgrading a const sock to a read/write tcp socket.
 511  * Used in context of (lockless) tcp listeners.
 512  */
 513 #define tcp_sk_rw(ptr) container_of(ptr, struct tcp_sock, inet_conn.icsk_inet.sk)
 514
 515 struct tcp_timewait_sock {
 516         struct inet_timewait_sock tw_sk;
 517 #define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt
 518 #define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt
 519         u32                       tw_rcv_wnd;
 520         u32                       tw_ts_offset;
 521         u32                       tw_ts_recent;
 522
 523         /* The time we sent the last out-of-window ACK: */
 524         u32                       tw_last_oow_ack_time;
 525
 526         int                       tw_ts_recent_stamp;
 527         u32                       tw_tx_delay;
 528 #ifdef CONFIG_TCP_MD5SIG
 529         struct tcp_md5sig_key     *tw_md5_key;
 530 #endif
 531 #ifdef CONFIG_TCP_AO
 532         struct tcp_ao_info      __rcu *ao_info;
 533 #endif
 534 };
 535
 536 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
 537 {
 538         return (struct tcp_timewait_sock *)sk;
 539 }
 540
 541 static inline bool tcp_passive_fastopen(const struct sock *sk)
 542 {
 543         return sk->sk_state == TCP_SYN_RECV &&
 544                rcu_access_pointer(tcp_sk(sk)->fastopen_rsk) != NULL;
 545 }
 546
 547 static inline void fastopen_queue_tune(struct sock *sk, int backlog)
 548 {
 549         struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
 550         int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn);
 551
 552         WRITE_ONCE(queue->fastopenq.max_qlen, min_t(unsigned int, backlog, somaxconn));
 553 }
 554
 555 static inline void tcp_move_syn(struct tcp_sock *tp,
 556                                 struct request_sock *req)
 557 {
 558         tp->saved_syn = req->saved_syn;
 559         req->saved_syn = NULL;
 560 }
 561
 562 static inline void tcp_saved_syn_free(struct tcp_sock *tp)
 563 {
 564         kfree(tp->saved_syn);
 565         tp->saved_syn = NULL;
 566 }
 567
 568 static inline u32 tcp_saved_syn_len(const struct saved_syn *saved_syn)
 569 {
 570         return saved_syn->mac_hdrlen + saved_syn->network_hdrlen +
 571                 saved_syn->tcp_hdrlen;
 572 }
 573
 574 struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk,
 575                                                const struct sk_buff *orig_skb,
 576                                                const struct sk_buff *ack_skb);
 577
 578 static inline u16 tcp_mss_clamp(const struct tcp_sock *tp, u16 mss)
 579 {
 580         /* We use READ_ONCE() here because socket might not be locked.
 581          * This happens for listeners.
 582          */
 583         u16 user_mss = READ_ONCE(tp->rx_opt.user_mss);
 584
 585         return (user_mss && user_mss < mss) ? user_mss : mss;
 586 }
 587
 588 int tcp_skb_shift(struct sk_buff *to, struct sk_buff *from, int pcount,
 589                   int shiftlen);
 590
 591 void __tcp_sock_set_cork(struct sock *sk, bool on);
 592 void tcp_sock_set_cork(struct sock *sk, bool on);
 593 int tcp_sock_set_keepcnt(struct sock *sk, int val);
 594 int tcp_sock_set_keepidle_locked(struct sock *sk, int val);
 595 int tcp_sock_set_keepidle(struct sock *sk, int val);
 596 int tcp_sock_set_keepintvl(struct sock *sk, int val);
 597 void __tcp_sock_set_nodelay(struct sock *sk, bool on);
 598 void tcp_sock_set_nodelay(struct sock *sk);
 599 void tcp_sock_set_quickack(struct sock *sk, int val);
 600 int tcp_sock_set_syncnt(struct sock *sk, int val);
 601 int tcp_sock_set_user_timeout(struct sock *sk, int val);
 602
 603 static inline bool dst_tcp_usec_ts(const struct dst_entry *dst)
 604 {
 605         return dst_feature(dst, RTAX_FEATURE_TCP_USEC_TS);
 606 }
 607
 608 #endif  /* _LINUX_TCP_H */