1 /*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * Definitions for the TCP protocol.
7 *
8 * Version: @(#)tcp.h 1.0.2 04/28/93
9 *
10 * Author: Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version
15 * 2 of the License, or (at your option) any later version.
16 */
17 #ifndef _LINUX_TCP_H
18 #define _LINUX_TCP_H
19
20
21 #include <linux/skbuff.h>
22 #include <linux/win_minmax.h>
23 #include <net/sock.h>
24 #include <net/inet_connection_sock.h>
25 #include <net/inet_timewait_sock.h>
26 #include <uapi/linux/tcp.h>
27
tcp_hdr(const struct sk_buff * skb)28 static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
29 {
30 return (struct tcphdr *)skb_transport_header(skb);
31 }
32
__tcp_hdrlen(const struct tcphdr * th)33 static inline unsigned int __tcp_hdrlen(const struct tcphdr *th)
34 {
35 return th->doff * 4;
36 }
37
tcp_hdrlen(const struct sk_buff * skb)38 static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
39 {
40 return __tcp_hdrlen(tcp_hdr(skb));
41 }
42
inner_tcp_hdr(const struct sk_buff * skb)43 static inline struct tcphdr *inner_tcp_hdr(const struct sk_buff *skb)
44 {
45 return (struct tcphdr *)skb_inner_transport_header(skb);
46 }
47
inner_tcp_hdrlen(const struct sk_buff * skb)48 static inline unsigned int inner_tcp_hdrlen(const struct sk_buff *skb)
49 {
50 return inner_tcp_hdr(skb)->doff * 4;
51 }
52
tcp_optlen(const struct sk_buff * skb)53 static inline unsigned int tcp_optlen(const struct sk_buff *skb)
54 {
55 return (tcp_hdr(skb)->doff - 5) * 4;
56 }
57
58 /* TCP Fast Open */
59 #define TCP_FASTOPEN_COOKIE_MIN 4 /* Min Fast Open Cookie size in bytes */
60 #define TCP_FASTOPEN_COOKIE_MAX 16 /* Max Fast Open Cookie size in bytes */
61 #define TCP_FASTOPEN_COOKIE_SIZE 8 /* the size employed by this impl. */
62
63 /* TCP Fast Open Cookie as stored in memory */
64 struct tcp_fastopen_cookie {
65 union {
66 u8 val[TCP_FASTOPEN_COOKIE_MAX];
67 #if IS_ENABLED(CONFIG_IPV6)
68 struct in6_addr addr;
69 #endif
70 };
71 s8 len;
72 bool exp; /* In RFC6994 experimental option format */
73 };
74
75 /* This defines a selective acknowledgement block. */
76 struct tcp_sack_block_wire {
77 __be32 start_seq;
78 __be32 end_seq;
79 };
80
81 struct tcp_sack_block {
82 u32 start_seq;
83 u32 end_seq;
84 };
85
86 /*These are used to set the sack_ok field in struct tcp_options_received */
87 #define TCP_SACK_SEEN (1 << 0) /*1 = peer is SACK capable, */
88 #define TCP_DSACK_SEEN (1 << 2) /*1 = DSACK was received from peer*/
89
90 struct tcp_options_received {
91 /* PAWS/RTTM data */
92 int ts_recent_stamp;/* Time we stored ts_recent (for aging) */
93 u32 ts_recent; /* Time stamp to echo next */
94 u32 rcv_tsval; /* Time stamp value */
95 u32 rcv_tsecr; /* Time stamp echo reply */
96 u16 saw_tstamp : 1, /* Saw TIMESTAMP on last packet */
97 tstamp_ok : 1, /* TIMESTAMP seen on SYN packet */
98 dsack : 1, /* D-SACK is scheduled */
99 wscale_ok : 1, /* Wscale seen on SYN packet */
100 sack_ok : 3, /* SACK seen on SYN packet */
101 smc_ok : 1, /* SMC seen on SYN packet */
102 snd_wscale : 4, /* Window scaling received from sender */
103 rcv_wscale : 4; /* Window scaling to send to receiver */
104 u8 num_sacks; /* Number of SACK blocks */
105 u16 user_mss; /* mss requested by user in ioctl */
106 u16 mss_clamp; /* Maximal mss, negotiated at connection setup */
107 };
108
tcp_clear_options(struct tcp_options_received * rx_opt)109 static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
110 {
111 rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
112 rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
113 #if IS_ENABLED(CONFIG_SMC)
114 rx_opt->smc_ok = 0;
115 #endif
116 }
117
118 /* This is the max number of SACKS that we'll generate and process. It's safe
119 * to increase this, although since:
120 * size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
121 * only four options will fit in a standard TCP header */
122 #define TCP_NUM_SACKS 4
123
124 struct tcp_request_sock_ops;
125
126 struct tcp_request_sock {
127 struct inet_request_sock req;
128 const struct tcp_request_sock_ops *af_specific;
129 u64 snt_synack; /* first SYNACK sent time */
130 bool tfo_listener;
131 u32 txhash;
132 u32 rcv_isn;
133 u32 snt_isn;
134 u32 ts_off;
135 u32 last_oow_ack_time; /* last SYNACK */
136 u32 rcv_nxt; /* the ack # by SYNACK. For
137 * FastOpen it's the seq#
138 * after data-in-SYN.
139 */
140 };
141
tcp_rsk(const struct request_sock * req)142 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
143 {
144 return (struct tcp_request_sock *)req;
145 }
146
147 struct tcp_sock {
148 /* inet_connection_sock has to be the first member of tcp_sock */
149 struct inet_connection_sock inet_conn;
150 u16 tcp_header_len; /* Bytes of tcp header to send */
151 u16 gso_segs; /* Max number of segs per GSO packet */
152
153 /*
154 * Header prediction flags
155 * 0x5?10 << 16 + snd_wnd in net byte order
156 */
157 __be32 pred_flags;
158
159 /*
160 * RFC793 variables by their proper names. This means you can
161 * read the code and the spec side by side (and laugh ...)
162 * See RFC793 and RFC1122. The RFC writes these in capitals.
163 */
164 u64 bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived
165 * sum(delta(rcv_nxt)), or how many bytes
166 * were acked.
167 */
168 u32 segs_in; /* RFC4898 tcpEStatsPerfSegsIn
169 * total number of segments in.
170 */
171 u32 data_segs_in; /* RFC4898 tcpEStatsPerfDataSegsIn
172 * total number of data segments in.
173 */
174 u32 rcv_nxt; /* What we want to receive next */
175 u32 copied_seq; /* Head of yet unread data */
176 u32 rcv_wup; /* rcv_nxt on last window update sent */
177 u32 snd_nxt; /* Next sequence we send */
178 u32 segs_out; /* RFC4898 tcpEStatsPerfSegsOut
179 * The total number of segments sent.
180 */
181 u32 data_segs_out; /* RFC4898 tcpEStatsPerfDataSegsOut
182 * total number of data segments sent.
183 */
184 u64 bytes_sent; /* RFC4898 tcpEStatsPerfHCDataOctetsOut
185 * total number of data bytes sent.
186 */
187 u64 bytes_acked; /* RFC4898 tcpEStatsAppHCThruOctetsAcked
188 * sum(delta(snd_una)), or how many bytes
189 * were acked.
190 */
191 u32 dsack_dups; /* RFC4898 tcpEStatsStackDSACKDups
192 * total number of DSACK blocks received
193 */
194 u32 snd_una; /* First byte we want an ack for */
195 u32 snd_sml; /* Last byte of the most recently transmitted small packet */
196 u32 rcv_tstamp; /* timestamp of last received ACK (for keepalives) */
197 u32 lsndtime; /* timestamp of last sent data packet (for restart window) */
198 u32 last_oow_ack_time; /* timestamp of last out-of-window ACK */
199 u32 compressed_ack_rcv_nxt;
200
201 u32 tsoffset; /* timestamp offset */
202
203 struct list_head tsq_node; /* anchor in tsq_tasklet.head list */
204 struct list_head tsorted_sent_queue; /* time-sorted sent but un-SACKed skbs */
205
206 u32 snd_wl1; /* Sequence for window update */
207 u32 snd_wnd; /* The window we expect to receive */
208 u32 max_window; /* Maximal window ever seen from peer */
209 u32 mss_cache; /* Cached effective mss, not including SACKS */
210
211 u32 window_clamp; /* Maximal window to advertise */
212 u32 rcv_ssthresh; /* Current window clamp */
213
214 /* Information of the most recently (s)acked skb */
215 struct tcp_rack {
216 u64 mstamp; /* (Re)sent time of the skb */
217 u32 rtt_us; /* Associated RTT */
218 u32 end_seq; /* Ending TCP sequence of the skb */
219 u32 last_delivered; /* tp->delivered at last reo_wnd adj */
220 u8 reo_wnd_steps; /* Allowed reordering window */
221 #define TCP_RACK_RECOVERY_THRESH 16
222 u8 reo_wnd_persist:5, /* No. of recovery since last adj */
223 dsack_seen:1, /* Whether DSACK seen after last adj */
224 advanced:1; /* mstamp advanced since last lost marking */
225 } rack;
226 u16 advmss; /* Advertised MSS */
227 u8 compressed_ack;
228 u8 tlp_retrans:1, /* TLP is a retransmission */
229 unused_1:7;
230 u32 chrono_start; /* Start time in jiffies of a TCP chrono */
231 u32 chrono_stat[3]; /* Time in jiffies for chrono_stat stats */
232 u8 chrono_type:2, /* current chronograph type */
233 rate_app_limited:1, /* rate_{delivered,interval_us} limited? */
234 fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */
235 fastopen_no_cookie:1, /* Allow send/recv SYN+data without a cookie */
236 is_sack_reneg:1, /* in recovery from loss with SACK reneg? */
237 unused:2;
238 u8 nonagle : 4,/* Disable Nagle algorithm? */
239 thin_lto : 1,/* Use linear timeouts for thin streams */
240 recvmsg_inq : 1,/* Indicate # of bytes in queue upon recvmsg */
241 repair : 1,
242 frto : 1;/* F-RTO (RFC5682) activated in CA_Loss */
243 u8 repair_queue;
244 u8 syn_data:1, /* SYN includes data */
245 syn_fastopen:1, /* SYN includes Fast Open option */
246 syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */
247 syn_fastopen_ch:1, /* Active TFO re-enabling probe */
248 syn_data_acked:1,/* data in SYN is acked by SYN-ACK */
249 save_syn:1, /* Save headers of SYN packet */
250 is_cwnd_limited:1,/* forward progress limited by snd_cwnd? */
251 syn_smc:1; /* SYN includes SMC */
252 u32 tlp_high_seq; /* snd_nxt at the time of TLP */
253
254 /* RTT measurement */
255 u64 tcp_mstamp; /* most recent packet received/sent */
256 u32 srtt_us; /* smoothed round trip time << 3 in usecs */
257 u32 mdev_us; /* medium deviation */
258 u32 mdev_max_us; /* maximal mdev for the last rtt period */
259 u32 rttvar_us; /* smoothed mdev_max */
260 u32 rtt_seq; /* sequence number to update rttvar */
261 struct minmax rtt_min;
262
263 u32 packets_out; /* Packets which are "in flight" */
264 u32 retrans_out; /* Retransmitted packets out */
265 u32 max_packets_out; /* max packets_out in last window */
266 u32 cwnd_usage_seq; /* right edge of cwnd usage tracking flight */
267
268 u16 urg_data; /* Saved octet of OOB data and control flags */
269 u8 ecn_flags; /* ECN status bits. */
270 u8 keepalive_probes; /* num of allowed keep alive probes */
271 u32 reordering; /* Packet reordering metric. */
272 u32 reord_seen; /* number of data packet reordering events */
273 u32 snd_up; /* Urgent pointer */
274
275 /*
276 * Options received (usually on last packet, some only on SYN packets).
277 */
278 struct tcp_options_received rx_opt;
279
280 /*
281 * Slow start and congestion control (see also Nagle, and Karn & Partridge)
282 */
283 u32 snd_ssthresh; /* Slow start size threshold */
284 u32 snd_cwnd; /* Sending congestion window */
285 u32 snd_cwnd_cnt; /* Linear increase counter */
286 u32 snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
287 u32 snd_cwnd_used;
288 u32 snd_cwnd_stamp;
289 u32 prior_cwnd; /* cwnd right before starting loss recovery */
290 u32 prr_delivered; /* Number of newly delivered packets to
291 * receiver in Recovery. */
292 u32 prr_out; /* Total number of pkts sent during Recovery. */
293 u32 delivered; /* Total data packets delivered incl. rexmits */
294 u32 delivered_ce; /* Like the above but only ECE marked packets */
295 u32 lost; /* Total data packets lost incl. rexmits */
296 u32 app_limited; /* limited until "delivered" reaches this val */
297 u64 first_tx_mstamp; /* start of window send phase */
298 u64 delivered_mstamp; /* time we reached "delivered" */
299 u32 rate_delivered; /* saved rate sample: packets delivered */
300 u32 rate_interval_us; /* saved rate sample: time elapsed */
301
302 u32 rcv_wnd; /* Current receiver window */
303 u32 write_seq; /* Tail(+1) of data held in tcp send buffer */
304 u32 notsent_lowat; /* TCP_NOTSENT_LOWAT */
305 u32 pushed_seq; /* Last pushed seq, required to talk to windows */
306 u32 lost_out; /* Lost packets */
307 u32 sacked_out; /* SACK'd packets */
308
309 struct hrtimer pacing_timer;
310 struct hrtimer compressed_ack_timer;
311
312 /* from STCP, retrans queue hinting */
313 struct sk_buff* lost_skb_hint;
314 struct sk_buff *retransmit_skb_hint;
315
316 /* OOO segments go in this rbtree. Socket lock must be held. */
317 struct rb_root out_of_order_queue;
318 struct sk_buff *ooo_last_skb; /* cache rb_last(out_of_order_queue) */
319
320 /* SACKs data, these 2 need to be together (see tcp_options_write) */
321 struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
322 struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
323
324 struct tcp_sack_block recv_sack_cache[4];
325
326 struct sk_buff *highest_sack; /* skb just after the highest
327 * skb with SACKed bit set
328 * (validity guaranteed only if
329 * sacked_out > 0)
330 */
331
332 int lost_cnt_hint;
333
334 u32 prior_ssthresh; /* ssthresh saved at recovery start */
335 u32 high_seq; /* snd_nxt at onset of congestion */
336
337 u32 retrans_stamp; /* Timestamp of the last retransmit,
338 * also used in SYN-SENT to remember stamp of
339 * the first SYN. */
340 u32 undo_marker; /* snd_una upon a new recovery episode. */
341 int undo_retrans; /* number of undoable retransmissions. */
342 u64 bytes_retrans; /* RFC4898 tcpEStatsPerfOctetsRetrans
343 * Total data bytes retransmitted
344 */
345 u32 total_retrans; /* Total retransmits for entire connection */
346
347 u32 urg_seq; /* Seq of received urgent pointer */
348 unsigned int keepalive_time; /* time before keep alive takes place */
349 unsigned int keepalive_intvl; /* time interval between keep alive probes */
350
351 int linger2;
352
353
354 /* Sock_ops bpf program related variables */
355 #ifdef CONFIG_BPF
356 u8 bpf_sock_ops_cb_flags; /* Control calling BPF programs
357 * values defined in uapi/linux/tcp.h
358 */
359 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) (TP->bpf_sock_ops_cb_flags & ARG)
360 #else
361 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) 0
362 #endif
363
364 /* Receiver side RTT estimation */
365 u32 rcv_rtt_last_tsecr;
366 struct {
367 u32 rtt_us;
368 u32 seq;
369 u64 time;
370 } rcv_rtt_est;
371
372 /* Receiver queue space */
373 struct {
374 u32 space;
375 u32 seq;
376 u64 time;
377 } rcvq_space;
378
379 /* TCP-specific MTU probe information. */
380 struct {
381 u32 probe_seq_start;
382 u32 probe_seq_end;
383 } mtu_probe;
384 u32 mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
385 * while socket was owned by user.
386 */
387
388 #ifdef CONFIG_TCP_MD5SIG
389 /* TCP AF-Specific parts; only used by MD5 Signature support so far */
390 const struct tcp_sock_af_ops *af_specific;
391
392 /* TCP MD5 Signature Option information */
393 struct tcp_md5sig_info __rcu *md5sig_info;
394 #endif
395
396 /* TCP fastopen related information */
397 struct tcp_fastopen_request *fastopen_req;
398 /* fastopen_rsk points to request_sock that resulted in this big
399 * socket. Used to retransmit SYNACKs etc.
400 */
401 struct request_sock *fastopen_rsk;
402 u32 *saved_syn;
403 };
404
405 enum tsq_enum {
406 TSQ_THROTTLED,
407 TSQ_QUEUED,
408 TCP_TSQ_DEFERRED, /* tcp_tasklet_func() found socket was owned */
409 TCP_WRITE_TIMER_DEFERRED, /* tcp_write_timer() found socket was owned */
410 TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
411 TCP_MTU_REDUCED_DEFERRED, /* tcp_v{4|6}_err() could not call
412 * tcp_v{4|6}_mtu_reduced()
413 */
414 };
415
416 enum tsq_flags {
417 TSQF_THROTTLED = (1UL << TSQ_THROTTLED),
418 TSQF_QUEUED = (1UL << TSQ_QUEUED),
419 TCPF_TSQ_DEFERRED = (1UL << TCP_TSQ_DEFERRED),
420 TCPF_WRITE_TIMER_DEFERRED = (1UL << TCP_WRITE_TIMER_DEFERRED),
421 TCPF_DELACK_TIMER_DEFERRED = (1UL << TCP_DELACK_TIMER_DEFERRED),
422 TCPF_MTU_REDUCED_DEFERRED = (1UL << TCP_MTU_REDUCED_DEFERRED),
423 };
424
tcp_sk(const struct sock * sk)425 static inline struct tcp_sock *tcp_sk(const struct sock *sk)
426 {
427 return (struct tcp_sock *)sk;
428 }
429
430 struct tcp_timewait_sock {
431 struct inet_timewait_sock tw_sk;
432 #define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt
433 #define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt
434 u32 tw_rcv_wnd;
435 u32 tw_ts_offset;
436 u32 tw_ts_recent;
437
438 /* The time we sent the last out-of-window ACK: */
439 u32 tw_last_oow_ack_time;
440
441 int tw_ts_recent_stamp;
442 #ifdef CONFIG_TCP_MD5SIG
443 struct tcp_md5sig_key *tw_md5_key;
444 #endif
445 };
446
tcp_twsk(const struct sock * sk)447 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
448 {
449 return (struct tcp_timewait_sock *)sk;
450 }
451
tcp_passive_fastopen(const struct sock * sk)452 static inline bool tcp_passive_fastopen(const struct sock *sk)
453 {
454 return (sk->sk_state == TCP_SYN_RECV &&
455 tcp_sk(sk)->fastopen_rsk != NULL);
456 }
457
fastopen_queue_tune(struct sock * sk,int backlog)458 static inline void fastopen_queue_tune(struct sock *sk, int backlog)
459 {
460 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
461 int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn);
462
463 WRITE_ONCE(queue->fastopenq.max_qlen, min_t(unsigned int, backlog, somaxconn));
464 }
465
tcp_move_syn(struct tcp_sock * tp,struct request_sock * req)466 static inline void tcp_move_syn(struct tcp_sock *tp,
467 struct request_sock *req)
468 {
469 tp->saved_syn = req->saved_syn;
470 req->saved_syn = NULL;
471 }
472
tcp_saved_syn_free(struct tcp_sock * tp)473 static inline void tcp_saved_syn_free(struct tcp_sock *tp)
474 {
475 kfree(tp->saved_syn);
476 tp->saved_syn = NULL;
477 }
478
479 struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk);
480
tcp_mss_clamp(const struct tcp_sock * tp,u16 mss)481 static inline u16 tcp_mss_clamp(const struct tcp_sock *tp, u16 mss)
482 {
483 /* We use READ_ONCE() here because socket might not be locked.
484 * This happens for listeners.
485 */
486 u16 user_mss = READ_ONCE(tp->rx_opt.user_mss);
487
488 return (user_mss && user_mss < mss) ? user_mss : mss;
489 }
490
491 int tcp_skb_shift(struct sk_buff *to, struct sk_buff *from, int pcount,
492 int shiftlen);
493
494 #endif /* _LINUX_TCP_H */
495