1// SPDX-License-Identifier: GPL-2.0-only
2/* (C) 1999-2001 Paul `Rusty' Russell
3 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
4 * (C) 2002-2013 Jozsef Kadlecsik <kadlec@netfilter.org>
5 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
6 */
7
8#include <linux/types.h>
9#include <linux/timer.h>
10#include <linux/module.h>
11#include <linux/in.h>
12#include <linux/tcp.h>
13#include <linux/spinlock.h>
14#include <linux/skbuff.h>
15#include <linux/ipv6.h>
16#include <net/ip6_checksum.h>
17#include <asm/unaligned.h>
18
19#include <net/tcp.h>
20
21#include <linux/netfilter.h>
22#include <linux/netfilter_ipv4.h>
23#include <linux/netfilter_ipv6.h>
24#include <net/netfilter/nf_conntrack.h>
25#include <net/netfilter/nf_conntrack_l4proto.h>
26#include <net/netfilter/nf_conntrack_ecache.h>
27#include <net/netfilter/nf_conntrack_seqadj.h>
28#include <net/netfilter/nf_conntrack_synproxy.h>
29#include <net/netfilter/nf_conntrack_timeout.h>
30#include <net/netfilter/nf_log.h>
31#include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
32#include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
33
34 /* FIXME: Examine ipfilter's timeouts and conntrack transitions more
35 closely. They're more complex. --RR */
36
37static const char *const tcp_conntrack_names[] = {
38 "NONE",
39 "SYN_SENT",
40 "SYN_RECV",
41 "ESTABLISHED",
42 "FIN_WAIT",
43 "CLOSE_WAIT",
44 "LAST_ACK",
45 "TIME_WAIT",
46 "CLOSE",
47 "SYN_SENT2",
48};
49
50enum nf_ct_tcp_action {
51 NFCT_TCP_IGNORE,
52 NFCT_TCP_INVALID,
53 NFCT_TCP_ACCEPT,
54};
55
56#define SECS * HZ
57#define MINS * 60 SECS
58#define HOURS * 60 MINS
59#define DAYS * 24 HOURS
60
61static const unsigned int tcp_timeouts[TCP_CONNTRACK_TIMEOUT_MAX] = {
62 [TCP_CONNTRACK_SYN_SENT] = 2 MINS,
63 [TCP_CONNTRACK_SYN_RECV] = 60 SECS,
64 [TCP_CONNTRACK_ESTABLISHED] = 5 DAYS,
65 [TCP_CONNTRACK_FIN_WAIT] = 2 MINS,
66 [TCP_CONNTRACK_CLOSE_WAIT] = 60 SECS,
67 [TCP_CONNTRACK_LAST_ACK] = 30 SECS,
68 [TCP_CONNTRACK_TIME_WAIT] = 2 MINS,
69 [TCP_CONNTRACK_CLOSE] = 10 SECS,
70 [TCP_CONNTRACK_SYN_SENT2] = 2 MINS,
71/* RFC1122 says the R2 limit should be at least 100 seconds.
72 Linux uses 15 packets as limit, which corresponds
73 to ~13-30min depending on RTO. */
74 [TCP_CONNTRACK_RETRANS] = 5 MINS,
75 [TCP_CONNTRACK_UNACK] = 5 MINS,
76};
77
78#define sNO TCP_CONNTRACK_NONE
79#define sSS TCP_CONNTRACK_SYN_SENT
80#define sSR TCP_CONNTRACK_SYN_RECV
81#define sES TCP_CONNTRACK_ESTABLISHED
82#define sFW TCP_CONNTRACK_FIN_WAIT
83#define sCW TCP_CONNTRACK_CLOSE_WAIT
84#define sLA TCP_CONNTRACK_LAST_ACK
85#define sTW TCP_CONNTRACK_TIME_WAIT
86#define sCL TCP_CONNTRACK_CLOSE
87#define sS2 TCP_CONNTRACK_SYN_SENT2
88#define sIV TCP_CONNTRACK_MAX
89#define sIG TCP_CONNTRACK_IGNORE
90
91/* What TCP flags are set from RST/SYN/FIN/ACK. */
92enum tcp_bit_set {
93 TCP_SYN_SET,
94 TCP_SYNACK_SET,
95 TCP_FIN_SET,
96 TCP_ACK_SET,
97 TCP_RST_SET,
98 TCP_NONE_SET,
99};
100
101/*
102 * The TCP state transition table needs a few words...
103 *
104 * We are the man in the middle. All the packets go through us
105 * but might get lost in transit to the destination.
106 * It is assumed that the destinations can't receive segments
107 * we haven't seen.
108 *
109 * The checked segment is in window, but our windows are *not*
110 * equivalent with the ones of the sender/receiver. We always
111 * try to guess the state of the current sender.
112 *
113 * The meaning of the states are:
114 *
115 * NONE: initial state
116 * SYN_SENT: SYN-only packet seen
117 * SYN_SENT2: SYN-only packet seen from reply dir, simultaneous open
118 * SYN_RECV: SYN-ACK packet seen
119 * ESTABLISHED: ACK packet seen
120 * FIN_WAIT: FIN packet seen
121 * CLOSE_WAIT: ACK seen (after FIN)
122 * LAST_ACK: FIN seen (after FIN)
123 * TIME_WAIT: last ACK seen
124 * CLOSE: closed connection (RST)
125 *
126 * Packets marked as IGNORED (sIG):
127 * if they may be either invalid or valid
128 * and the receiver may send back a connection
129 * closing RST or a SYN/ACK.
130 *
131 * Packets marked as INVALID (sIV):
132 * if we regard them as truly invalid packets
133 */
134static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
135 {
136/* ORIGINAL */
137/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
138/*syn*/ { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sS2 },
139/*
140 * sNO -> sSS Initialize a new connection
141 * sSS -> sSS Retransmitted SYN
142 * sS2 -> sS2 Late retransmitted SYN
143 * sSR -> sIG
144 * sES -> sIG Error: SYNs in window outside the SYN_SENT state
145 * are errors. Receiver will reply with RST
146 * and close the connection.
147 * Or we are not in sync and hold a dead connection.
148 * sFW -> sIG
149 * sCW -> sIG
150 * sLA -> sIG
151 * sTW -> sSS Reopened connection (RFC 1122).
152 * sCL -> sSS
153 */
154/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
155/*synack*/ { sIV, sIV, sSR, sIV, sIV, sIV, sIV, sIV, sIV, sSR },
156/*
157 * sNO -> sIV Too late and no reason to do anything
158 * sSS -> sIV Client can't send SYN and then SYN/ACK
159 * sS2 -> sSR SYN/ACK sent to SYN2 in simultaneous open
160 * sSR -> sSR Late retransmitted SYN/ACK in simultaneous open
161 * sES -> sIV Invalid SYN/ACK packets sent by the client
162 * sFW -> sIV
163 * sCW -> sIV
164 * sLA -> sIV
165 * sTW -> sIV
166 * sCL -> sIV
167 */
168/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
169/*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
170/*
171 * sNO -> sIV Too late and no reason to do anything...
172 * sSS -> sIV Client migth not send FIN in this state:
173 * we enforce waiting for a SYN/ACK reply first.
174 * sS2 -> sIV
175 * sSR -> sFW Close started.
176 * sES -> sFW
177 * sFW -> sLA FIN seen in both directions, waiting for
178 * the last ACK.
179 * Migth be a retransmitted FIN as well...
180 * sCW -> sLA
181 * sLA -> sLA Retransmitted FIN. Remain in the same state.
182 * sTW -> sTW
183 * sCL -> sCL
184 */
185/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
186/*ack*/ { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV },
187/*
188 * sNO -> sES Assumed.
189 * sSS -> sIV ACK is invalid: we haven't seen a SYN/ACK yet.
190 * sS2 -> sIV
191 * sSR -> sES Established state is reached.
192 * sES -> sES :-)
193 * sFW -> sCW Normal close request answered by ACK.
194 * sCW -> sCW
195 * sLA -> sTW Last ACK detected (RFC5961 challenged)
196 * sTW -> sTW Retransmitted last ACK. Remain in the same state.
197 * sCL -> sCL
198 */
199/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
200/*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
201/*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
202 },
203 {
204/* REPLY */
205/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
206/*syn*/ { sIV, sS2, sIV, sIV, sIV, sIV, sIV, sSS, sIV, sS2 },
207/*
208 * sNO -> sIV Never reached.
209 * sSS -> sS2 Simultaneous open
210 * sS2 -> sS2 Retransmitted simultaneous SYN
211 * sSR -> sIV Invalid SYN packets sent by the server
212 * sES -> sIV
213 * sFW -> sIV
214 * sCW -> sIV
215 * sLA -> sIV
216 * sTW -> sSS Reopened connection, but server may have switched role
217 * sCL -> sIV
218 */
219/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
220/*synack*/ { sIV, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIG, sSR },
221/*
222 * sSS -> sSR Standard open.
223 * sS2 -> sSR Simultaneous open
224 * sSR -> sIG Retransmitted SYN/ACK, ignore it.
225 * sES -> sIG Late retransmitted SYN/ACK?
226 * sFW -> sIG Might be SYN/ACK answering ignored SYN
227 * sCW -> sIG
228 * sLA -> sIG
229 * sTW -> sIG
230 * sCL -> sIG
231 */
232/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
233/*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
234/*
235 * sSS -> sIV Server might not send FIN in this state.
236 * sS2 -> sIV
237 * sSR -> sFW Close started.
238 * sES -> sFW
239 * sFW -> sLA FIN seen in both directions.
240 * sCW -> sLA
241 * sLA -> sLA Retransmitted FIN.
242 * sTW -> sTW
243 * sCL -> sCL
244 */
245/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
246/*ack*/ { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIG },
247/*
248 * sSS -> sIG Might be a half-open connection.
249 * sS2 -> sIG
250 * sSR -> sSR Might answer late resent SYN.
251 * sES -> sES :-)
252 * sFW -> sCW Normal close request answered by ACK.
253 * sCW -> sCW
254 * sLA -> sTW Last ACK detected (RFC5961 challenged)
255 * sTW -> sTW Retransmitted last ACK.
256 * sCL -> sCL
257 */
258/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
259/*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
260/*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
261 }
262};
263
264#ifdef CONFIG_NF_CONNTRACK_PROCFS
265/* Print out the private part of the conntrack. */
266static void tcp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
267{
268 if (test_bit(IPS_OFFLOAD_BIT, &ct->status))
269 return;
270
271 seq_printf(m: s, fmt: "%s ", tcp_conntrack_names[ct->proto.tcp.state]);
272}
273#endif
274
275static unsigned int get_conntrack_index(const struct tcphdr *tcph)
276{
277 if (tcph->rst) return TCP_RST_SET;
278 else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET);
279 else if (tcph->fin) return TCP_FIN_SET;
280 else if (tcph->ack) return TCP_ACK_SET;
281 else return TCP_NONE_SET;
282}
283
284/* TCP connection tracking based on 'Real Stateful TCP Packet Filtering
285 in IP Filter' by Guido van Rooij.
286
287 http://www.sane.nl/events/sane2000/papers.html
288 http://www.darkart.com/mirrors/www.obfuscation.org/ipf/
289
290 The boundaries and the conditions are changed according to RFC793:
291 the packet must intersect the window (i.e. segments may be
292 after the right or before the left edge) and thus receivers may ACK
293 segments after the right edge of the window.
294
295 td_maxend = max(sack + max(win,1)) seen in reply packets
296 td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets
297 td_maxwin += seq + len - sender.td_maxend
298 if seq + len > sender.td_maxend
299 td_end = max(seq + len) seen in sent packets
300
301 I. Upper bound for valid data: seq <= sender.td_maxend
302 II. Lower bound for valid data: seq + len >= sender.td_end - receiver.td_maxwin
303 III. Upper bound for valid (s)ack: sack <= receiver.td_end
304 IV. Lower bound for valid (s)ack: sack >= receiver.td_end - MAXACKWINDOW
305
306 where sack is the highest right edge of sack block found in the packet
307 or ack in the case of packet without SACK option.
308
309 The upper bound limit for a valid (s)ack is not ignored -
310 we doesn't have to deal with fragments.
311*/
312
313static inline __u32 segment_seq_plus_len(__u32 seq,
314 size_t len,
315 unsigned int dataoff,
316 const struct tcphdr *tcph)
317{
318 /* XXX Should I use payload length field in IP/IPv6 header ?
319 * - YK */
320 return (seq + len - dataoff - tcph->doff*4
321 + (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0));
322}
323
324/* Fixme: what about big packets? */
325#define MAXACKWINCONST 66000
326#define MAXACKWINDOW(sender) \
327 ((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin \
328 : MAXACKWINCONST)
329
330/*
331 * Simplified tcp_parse_options routine from tcp_input.c
332 */
333static void tcp_options(const struct sk_buff *skb,
334 unsigned int dataoff,
335 const struct tcphdr *tcph,
336 struct ip_ct_tcp_state *state)
337{
338 unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
339 const unsigned char *ptr;
340 int length = (tcph->doff*4) - sizeof(struct tcphdr);
341
342 if (!length)
343 return;
344
345 ptr = skb_header_pointer(skb, offset: dataoff + sizeof(struct tcphdr),
346 len: length, buffer: buff);
347 if (!ptr)
348 return;
349
350 state->td_scale = 0;
351 state->flags &= IP_CT_TCP_FLAG_BE_LIBERAL;
352
353 while (length > 0) {
354 int opcode=*ptr++;
355 int opsize;
356
357 switch (opcode) {
358 case TCPOPT_EOL:
359 return;
360 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
361 length--;
362 continue;
363 default:
364 if (length < 2)
365 return;
366 opsize=*ptr++;
367 if (opsize < 2) /* "silly options" */
368 return;
369 if (opsize > length)
370 return; /* don't parse partial options */
371
372 if (opcode == TCPOPT_SACK_PERM
373 && opsize == TCPOLEN_SACK_PERM)
374 state->flags |= IP_CT_TCP_FLAG_SACK_PERM;
375 else if (opcode == TCPOPT_WINDOW
376 && opsize == TCPOLEN_WINDOW) {
377 state->td_scale = *(u_int8_t *)ptr;
378
379 if (state->td_scale > TCP_MAX_WSCALE)
380 state->td_scale = TCP_MAX_WSCALE;
381
382 state->flags |=
383 IP_CT_TCP_FLAG_WINDOW_SCALE;
384 }
385 ptr += opsize - 2;
386 length -= opsize;
387 }
388 }
389}
390
391static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
392 const struct tcphdr *tcph, __u32 *sack)
393{
394 unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
395 const unsigned char *ptr;
396 int length = (tcph->doff*4) - sizeof(struct tcphdr);
397 __u32 tmp;
398
399 if (!length)
400 return;
401
402 ptr = skb_header_pointer(skb, offset: dataoff + sizeof(struct tcphdr),
403 len: length, buffer: buff);
404 if (!ptr)
405 return;
406
407 /* Fast path for timestamp-only option */
408 if (length == TCPOLEN_TSTAMP_ALIGNED
409 && *(__be32 *)ptr == htonl((TCPOPT_NOP << 24)
410 | (TCPOPT_NOP << 16)
411 | (TCPOPT_TIMESTAMP << 8)
412 | TCPOLEN_TIMESTAMP))
413 return;
414
415 while (length > 0) {
416 int opcode = *ptr++;
417 int opsize, i;
418
419 switch (opcode) {
420 case TCPOPT_EOL:
421 return;
422 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
423 length--;
424 continue;
425 default:
426 if (length < 2)
427 return;
428 opsize = *ptr++;
429 if (opsize < 2) /* "silly options" */
430 return;
431 if (opsize > length)
432 return; /* don't parse partial options */
433
434 if (opcode == TCPOPT_SACK
435 && opsize >= (TCPOLEN_SACK_BASE
436 + TCPOLEN_SACK_PERBLOCK)
437 && !((opsize - TCPOLEN_SACK_BASE)
438 % TCPOLEN_SACK_PERBLOCK)) {
439 for (i = 0;
440 i < (opsize - TCPOLEN_SACK_BASE);
441 i += TCPOLEN_SACK_PERBLOCK) {
442 tmp = get_unaligned_be32(p: (__be32 *)(ptr+i)+1);
443
444 if (after(tmp, *sack))
445 *sack = tmp;
446 }
447 return;
448 }
449 ptr += opsize - 2;
450 length -= opsize;
451 }
452 }
453}
454
455static void tcp_init_sender(struct ip_ct_tcp_state *sender,
456 struct ip_ct_tcp_state *receiver,
457 const struct sk_buff *skb,
458 unsigned int dataoff,
459 const struct tcphdr *tcph,
460 u32 end, u32 win)
461{
462 /* SYN-ACK in reply to a SYN
463 * or SYN from reply direction in simultaneous open.
464 */
465 sender->td_end =
466 sender->td_maxend = end;
467 sender->td_maxwin = (win == 0 ? 1 : win);
468
469 tcp_options(skb, dataoff, tcph, state: sender);
470 /* RFC 1323:
471 * Both sides must send the Window Scale option
472 * to enable window scaling in either direction.
473 */
474 if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
475 receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE)) {
476 sender->td_scale = 0;
477 receiver->td_scale = 0;
478 }
479}
480
481__printf(6, 7)
482static enum nf_ct_tcp_action nf_tcp_log_invalid(const struct sk_buff *skb,
483 const struct nf_conn *ct,
484 const struct nf_hook_state *state,
485 const struct ip_ct_tcp_state *sender,
486 enum nf_ct_tcp_action ret,
487 const char *fmt, ...)
488{
489 const struct nf_tcp_net *tn = nf_tcp_pernet(net: nf_ct_net(ct));
490 struct va_format vaf;
491 va_list args;
492 bool be_liberal;
493
494 be_liberal = sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL || tn->tcp_be_liberal;
495 if (be_liberal)
496 return NFCT_TCP_ACCEPT;
497
498 va_start(args, fmt);
499 vaf.fmt = fmt;
500 vaf.va = &args;
501 nf_ct_l4proto_log_invalid(skb, ct, state, fmt: "%pV", &vaf);
502 va_end(args);
503
504 return ret;
505}
506
507static enum nf_ct_tcp_action
508tcp_in_window(struct nf_conn *ct, enum ip_conntrack_dir dir,
509 unsigned int index, const struct sk_buff *skb,
510 unsigned int dataoff, const struct tcphdr *tcph,
511 const struct nf_hook_state *hook_state)
512{
513 struct ip_ct_tcp *state = &ct->proto.tcp;
514 struct ip_ct_tcp_state *sender = &state->seen[dir];
515 struct ip_ct_tcp_state *receiver = &state->seen[!dir];
516 __u32 seq, ack, sack, end, win, swin;
517 bool in_recv_win, seq_ok;
518 s32 receiver_offset;
519 u16 win_raw;
520
521 /*
522 * Get the required data from the packet.
523 */
524 seq = ntohl(tcph->seq);
525 ack = sack = ntohl(tcph->ack_seq);
526 win_raw = ntohs(tcph->window);
527 win = win_raw;
528 end = segment_seq_plus_len(seq, len: skb->len, dataoff, tcph);
529
530 if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
531 tcp_sack(skb, dataoff, tcph, sack: &sack);
532
533 /* Take into account NAT sequence number mangling */
534 receiver_offset = nf_ct_seq_offset(ct, !dir, seq: ack - 1);
535 ack -= receiver_offset;
536 sack -= receiver_offset;
537
538 if (sender->td_maxwin == 0) {
539 /*
540 * Initialize sender data.
541 */
542 if (tcph->syn) {
543 tcp_init_sender(sender, receiver,
544 skb, dataoff, tcph,
545 end, win);
546 if (!tcph->ack)
547 /* Simultaneous open */
548 return NFCT_TCP_ACCEPT;
549 } else {
550 /*
551 * We are in the middle of a connection,
552 * its history is lost for us.
553 * Let's try to use the data from the packet.
554 */
555 sender->td_end = end;
556 swin = win << sender->td_scale;
557 sender->td_maxwin = (swin == 0 ? 1 : swin);
558 sender->td_maxend = end + sender->td_maxwin;
559 if (receiver->td_maxwin == 0) {
560 /* We haven't seen traffic in the other
561 * direction yet but we have to tweak window
562 * tracking to pass III and IV until that
563 * happens.
564 */
565 receiver->td_end = receiver->td_maxend = sack;
566 } else if (sack == receiver->td_end + 1) {
567 /* Likely a reply to a keepalive.
568 * Needed for III.
569 */
570 receiver->td_end++;
571 }
572
573 }
574 } else if (tcph->syn &&
575 after(end, sender->td_end) &&
576 (state->state == TCP_CONNTRACK_SYN_SENT ||
577 state->state == TCP_CONNTRACK_SYN_RECV)) {
578 /*
579 * RFC 793: "if a TCP is reinitialized ... then it need
580 * not wait at all; it must only be sure to use sequence
581 * numbers larger than those recently used."
582 *
583 * Re-init state for this direction, just like for the first
584 * syn(-ack) reply, it might differ in seq, ack or tcp options.
585 */
586 tcp_init_sender(sender, receiver,
587 skb, dataoff, tcph,
588 end, win);
589
590 if (dir == IP_CT_DIR_REPLY && !tcph->ack)
591 return NFCT_TCP_ACCEPT;
592 }
593
594 if (!(tcph->ack)) {
595 /*
596 * If there is no ACK, just pretend it was set and OK.
597 */
598 ack = sack = receiver->td_end;
599 } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
600 (TCP_FLAG_ACK|TCP_FLAG_RST))
601 && (ack == 0)) {
602 /*
603 * Broken TCP stacks, that set ACK in RST packets as well
604 * with zero ack value.
605 */
606 ack = sack = receiver->td_end;
607 }
608
609 if (tcph->rst && seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)
610 /*
611 * RST sent answering SYN.
612 */
613 seq = end = sender->td_end;
614
615 seq_ok = before(seq1: seq, seq2: sender->td_maxend + 1);
616 if (!seq_ok) {
617 u32 overshot = end - sender->td_maxend + 1;
618 bool ack_ok;
619
620 ack_ok = after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1);
621 in_recv_win = receiver->td_maxwin &&
622 after(end, sender->td_end - receiver->td_maxwin - 1);
623
624 if (in_recv_win &&
625 ack_ok &&
626 overshot <= receiver->td_maxwin &&
627 before(seq1: sack, seq2: receiver->td_end + 1)) {
628 /* Work around TCPs that send more bytes than allowed by
629 * the receive window.
630 *
631 * If the (marked as invalid) packet is allowed to pass by
632 * the ruleset and the peer acks this data, then its possible
633 * all future packets will trigger 'ACK is over upper bound' check.
634 *
635 * Thus if only the sequence check fails then do update td_end so
636 * possible ACK for this data can update internal state.
637 */
638 sender->td_end = end;
639 sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
640
641 return nf_tcp_log_invalid(skb, ct, state: hook_state, sender, ret: NFCT_TCP_IGNORE,
642 fmt: "%u bytes more than expected", overshot);
643 }
644
645 return nf_tcp_log_invalid(skb, ct, state: hook_state, sender, ret: NFCT_TCP_INVALID,
646 fmt: "SEQ is over upper bound %u (over the window of the receiver)",
647 sender->td_maxend + 1);
648 }
649
650 if (!before(seq1: sack, seq2: receiver->td_end + 1))
651 return nf_tcp_log_invalid(skb, ct, state: hook_state, sender, ret: NFCT_TCP_INVALID,
652 fmt: "ACK is over upper bound %u (ACKed data not seen yet)",
653 receiver->td_end + 1);
654
655 /* Is the ending sequence in the receive window (if available)? */
656 in_recv_win = !receiver->td_maxwin ||
657 after(end, sender->td_end - receiver->td_maxwin - 1);
658 if (!in_recv_win)
659 return nf_tcp_log_invalid(skb, ct, state: hook_state, sender, ret: NFCT_TCP_IGNORE,
660 fmt: "SEQ is under lower bound %u (already ACKed data retransmitted)",
661 sender->td_end - receiver->td_maxwin - 1);
662 if (!after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1))
663 return nf_tcp_log_invalid(skb, ct, state: hook_state, sender, ret: NFCT_TCP_IGNORE,
664 fmt: "ignored ACK under lower bound %u (possible overly delayed)",
665 receiver->td_end - MAXACKWINDOW(sender) - 1);
666
667 /* Take into account window scaling (RFC 1323). */
668 if (!tcph->syn)
669 win <<= sender->td_scale;
670
671 /* Update sender data. */
672 swin = win + (sack - ack);
673 if (sender->td_maxwin < swin)
674 sender->td_maxwin = swin;
675 if (after(end, sender->td_end)) {
676 sender->td_end = end;
677 sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
678 }
679 if (tcph->ack) {
680 if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) {
681 sender->td_maxack = ack;
682 sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET;
683 } else if (after(ack, sender->td_maxack)) {
684 sender->td_maxack = ack;
685 }
686 }
687
688 /* Update receiver data. */
689 if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
690 receiver->td_maxwin += end - sender->td_maxend;
691 if (after(sack + win, receiver->td_maxend - 1)) {
692 receiver->td_maxend = sack + win;
693 if (win == 0)
694 receiver->td_maxend++;
695 }
696 if (ack == receiver->td_end)
697 receiver->flags &= ~IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
698
699 /* Check retransmissions. */
700 if (index == TCP_ACK_SET) {
701 if (state->last_dir == dir &&
702 state->last_seq == seq &&
703 state->last_ack == ack &&
704 state->last_end == end &&
705 state->last_win == win_raw) {
706 state->retrans++;
707 } else {
708 state->last_dir = dir;
709 state->last_seq = seq;
710 state->last_ack = ack;
711 state->last_end = end;
712 state->last_win = win_raw;
713 state->retrans = 0;
714 }
715 }
716
717 return NFCT_TCP_ACCEPT;
718}
719
720static void __cold nf_tcp_handle_invalid(struct nf_conn *ct,
721 enum ip_conntrack_dir dir,
722 int index,
723 const struct sk_buff *skb,
724 const struct nf_hook_state *hook_state)
725{
726 const unsigned int *timeouts;
727 const struct nf_tcp_net *tn;
728 unsigned int timeout;
729 u32 expires;
730
731 if (!test_bit(IPS_ASSURED_BIT, &ct->status) ||
732 test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status))
733 return;
734
735 /* We don't want to have connections hanging around in ESTABLISHED
736 * state for long time 'just because' conntrack deemed a FIN/RST
737 * out-of-window.
738 *
739 * Shrink the timeout just like when there is unacked data.
740 * This speeds up eviction of 'dead' connections where the
741 * connection and conntracks internal state are out of sync.
742 */
743 switch (index) {
744 case TCP_RST_SET:
745 case TCP_FIN_SET:
746 break;
747 default:
748 return;
749 }
750
751 if (ct->proto.tcp.last_dir != dir &&
752 (ct->proto.tcp.last_index == TCP_FIN_SET ||
753 ct->proto.tcp.last_index == TCP_RST_SET)) {
754 expires = nf_ct_expires(ct);
755 if (expires < 120 * HZ)
756 return;
757
758 tn = nf_tcp_pernet(net: nf_ct_net(ct));
759 timeouts = nf_ct_timeout_lookup(ct);
760 if (!timeouts)
761 timeouts = tn->timeouts;
762
763 timeout = READ_ONCE(timeouts[TCP_CONNTRACK_UNACK]);
764 if (expires > timeout) {
765 nf_ct_l4proto_log_invalid(skb, ct, state: hook_state,
766 fmt: "packet (index %d, dir %d) response for index %d lower timeout to %u",
767 index, dir, ct->proto.tcp.last_index, timeout);
768
769 WRITE_ONCE(ct->timeout, timeout + nfct_time_stamp);
770 }
771 } else {
772 ct->proto.tcp.last_index = index;
773 ct->proto.tcp.last_dir = dir;
774 }
775}
776
777/* table of valid flag combinations - PUSH, ECE and CWR are always valid */
778static const u8 tcp_valid_flags[(TCPHDR_FIN|TCPHDR_SYN|TCPHDR_RST|TCPHDR_ACK|
779 TCPHDR_URG) + 1] =
780{
781 [TCPHDR_SYN] = 1,
782 [TCPHDR_SYN|TCPHDR_URG] = 1,
783 [TCPHDR_SYN|TCPHDR_ACK] = 1,
784 [TCPHDR_RST] = 1,
785 [TCPHDR_RST|TCPHDR_ACK] = 1,
786 [TCPHDR_FIN|TCPHDR_ACK] = 1,
787 [TCPHDR_FIN|TCPHDR_ACK|TCPHDR_URG] = 1,
788 [TCPHDR_ACK] = 1,
789 [TCPHDR_ACK|TCPHDR_URG] = 1,
790};
791
792static void tcp_error_log(const struct sk_buff *skb,
793 const struct nf_hook_state *state,
794 const char *msg)
795{
796 nf_l4proto_log_invalid(skb, state, IPPROTO_TCP, fmt: "%s", msg);
797}
798
799/* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c. */
800static bool tcp_error(const struct tcphdr *th,
801 struct sk_buff *skb,
802 unsigned int dataoff,
803 const struct nf_hook_state *state)
804{
805 unsigned int tcplen = skb->len - dataoff;
806 u8 tcpflags;
807
808 /* Not whole TCP header or malformed packet */
809 if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
810 tcp_error_log(skb, state, msg: "truncated packet");
811 return true;
812 }
813
814 /* Checksum invalid? Ignore.
815 * We skip checking packets on the outgoing path
816 * because the checksum is assumed to be correct.
817 */
818 /* FIXME: Source route IP option packets --RR */
819 if (state->net->ct.sysctl_checksum &&
820 state->hook == NF_INET_PRE_ROUTING &&
821 nf_checksum(skb, hook: state->hook, dataoff, IPPROTO_TCP, family: state->pf)) {
822 tcp_error_log(skb, state, msg: "bad checksum");
823 return true;
824 }
825
826 /* Check TCP flags. */
827 tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
828 if (!tcp_valid_flags[tcpflags]) {
829 tcp_error_log(skb, state, msg: "invalid tcp flag combination");
830 return true;
831 }
832
833 return false;
834}
835
836static noinline bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
837 unsigned int dataoff,
838 const struct tcphdr *th,
839 const struct nf_hook_state *state)
840{
841 enum tcp_conntrack new_state;
842 struct net *net = nf_ct_net(ct);
843 const struct nf_tcp_net *tn = nf_tcp_pernet(net);
844
845 /* Don't need lock here: this conntrack not in circulation yet */
846 new_state = tcp_conntracks[0][get_conntrack_index(tcph: th)][TCP_CONNTRACK_NONE];
847
848 /* Invalid: delete conntrack */
849 if (new_state >= TCP_CONNTRACK_MAX) {
850 tcp_error_log(skb, state, msg: "invalid new");
851 return false;
852 }
853
854 if (new_state == TCP_CONNTRACK_SYN_SENT) {
855 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
856 /* SYN packet */
857 ct->proto.tcp.seen[0].td_end =
858 segment_seq_plus_len(ntohl(th->seq), len: skb->len,
859 dataoff, tcph: th);
860 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
861 if (ct->proto.tcp.seen[0].td_maxwin == 0)
862 ct->proto.tcp.seen[0].td_maxwin = 1;
863 ct->proto.tcp.seen[0].td_maxend =
864 ct->proto.tcp.seen[0].td_end;
865
866 tcp_options(skb, dataoff, tcph: th, state: &ct->proto.tcp.seen[0]);
867 } else if (tn->tcp_loose == 0) {
868 /* Don't try to pick up connections. */
869 return false;
870 } else {
871 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
872 /*
873 * We are in the middle of a connection,
874 * its history is lost for us.
875 * Let's try to use the data from the packet.
876 */
877 ct->proto.tcp.seen[0].td_end =
878 segment_seq_plus_len(ntohl(th->seq), len: skb->len,
879 dataoff, tcph: th);
880 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
881 if (ct->proto.tcp.seen[0].td_maxwin == 0)
882 ct->proto.tcp.seen[0].td_maxwin = 1;
883 ct->proto.tcp.seen[0].td_maxend =
884 ct->proto.tcp.seen[0].td_end +
885 ct->proto.tcp.seen[0].td_maxwin;
886
887 /* We assume SACK and liberal window checking to handle
888 * window scaling */
889 ct->proto.tcp.seen[0].flags =
890 ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
891 IP_CT_TCP_FLAG_BE_LIBERAL;
892 }
893
894 /* tcp_packet will set them */
895 ct->proto.tcp.last_index = TCP_NONE_SET;
896 return true;
897}
898
899static bool tcp_can_early_drop(const struct nf_conn *ct)
900{
901 switch (ct->proto.tcp.state) {
902 case TCP_CONNTRACK_FIN_WAIT:
903 case TCP_CONNTRACK_LAST_ACK:
904 case TCP_CONNTRACK_TIME_WAIT:
905 case TCP_CONNTRACK_CLOSE:
906 case TCP_CONNTRACK_CLOSE_WAIT:
907 return true;
908 default:
909 break;
910 }
911
912 return false;
913}
914
915void nf_conntrack_tcp_set_closing(struct nf_conn *ct)
916{
917 enum tcp_conntrack old_state;
918 const unsigned int *timeouts;
919 u32 timeout;
920
921 if (!nf_ct_is_confirmed(ct))
922 return;
923
924 spin_lock_bh(lock: &ct->lock);
925 old_state = ct->proto.tcp.state;
926 ct->proto.tcp.state = TCP_CONNTRACK_CLOSE;
927
928 if (old_state == TCP_CONNTRACK_CLOSE ||
929 test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status)) {
930 spin_unlock_bh(lock: &ct->lock);
931 return;
932 }
933
934 timeouts = nf_ct_timeout_lookup(ct);
935 if (!timeouts) {
936 const struct nf_tcp_net *tn;
937
938 tn = nf_tcp_pernet(net: nf_ct_net(ct));
939 timeouts = tn->timeouts;
940 }
941
942 timeout = timeouts[TCP_CONNTRACK_CLOSE];
943 WRITE_ONCE(ct->timeout, timeout + nfct_time_stamp);
944
945 spin_unlock_bh(lock: &ct->lock);
946
947 nf_conntrack_event_cache(event: IPCT_PROTOINFO, ct);
948}
949
950static void nf_ct_tcp_state_reset(struct ip_ct_tcp_state *state)
951{
952 state->td_end = 0;
953 state->td_maxend = 0;
954 state->td_maxwin = 0;
955 state->td_maxack = 0;
956 state->td_scale = 0;
957 state->flags &= IP_CT_TCP_FLAG_BE_LIBERAL;
958}
959
960/* Returns verdict for packet, or -1 for invalid. */
961int nf_conntrack_tcp_packet(struct nf_conn *ct,
962 struct sk_buff *skb,
963 unsigned int dataoff,
964 enum ip_conntrack_info ctinfo,
965 const struct nf_hook_state *state)
966{
967 struct net *net = nf_ct_net(ct);
968 struct nf_tcp_net *tn = nf_tcp_pernet(net);
969 enum tcp_conntrack new_state, old_state;
970 unsigned int index, *timeouts;
971 enum nf_ct_tcp_action res;
972 enum ip_conntrack_dir dir;
973 const struct tcphdr *th;
974 struct tcphdr _tcph;
975 unsigned long timeout;
976
977 th = skb_header_pointer(skb, offset: dataoff, len: sizeof(_tcph), buffer: &_tcph);
978 if (th == NULL)
979 return -NF_ACCEPT;
980
981 if (tcp_error(th, skb, dataoff, state))
982 return -NF_ACCEPT;
983
984 if (!nf_ct_is_confirmed(ct) && !tcp_new(ct, skb, dataoff, th, state))
985 return -NF_ACCEPT;
986
987 spin_lock_bh(lock: &ct->lock);
988 old_state = ct->proto.tcp.state;
989 dir = CTINFO2DIR(ctinfo);
990 index = get_conntrack_index(tcph: th);
991 new_state = tcp_conntracks[dir][index][old_state];
992
993 switch (new_state) {
994 case TCP_CONNTRACK_SYN_SENT:
995 if (old_state < TCP_CONNTRACK_TIME_WAIT)
996 break;
997 /* RFC 1122: "When a connection is closed actively,
998 * it MUST linger in TIME-WAIT state for a time 2xMSL
999 * (Maximum Segment Lifetime). However, it MAY accept
1000 * a new SYN from the remote TCP to reopen the connection
1001 * directly from TIME-WAIT state, if..."
1002 * We ignore the conditions because we are in the
1003 * TIME-WAIT state anyway.
1004 *
1005 * Handle aborted connections: we and the server
1006 * think there is an existing connection but the client
1007 * aborts it and starts a new one.
1008 */
1009 if (((ct->proto.tcp.seen[dir].flags
1010 | ct->proto.tcp.seen[!dir].flags)
1011 & IP_CT_TCP_FLAG_CLOSE_INIT)
1012 || (ct->proto.tcp.last_dir == dir
1013 && ct->proto.tcp.last_index == TCP_RST_SET)) {
1014 /* Attempt to reopen a closed/aborted connection.
1015 * Delete this connection and look up again. */
1016 spin_unlock_bh(lock: &ct->lock);
1017
1018 /* Only repeat if we can actually remove the timer.
1019 * Destruction may already be in progress in process
1020 * context and we must give it a chance to terminate.
1021 */
1022 if (nf_ct_kill(ct))
1023 return -NF_REPEAT;
1024 return NF_DROP;
1025 }
1026 fallthrough;
1027 case TCP_CONNTRACK_IGNORE:
1028 /* Ignored packets:
1029 *
1030 * Our connection entry may be out of sync, so ignore
1031 * packets which may signal the real connection between
1032 * the client and the server.
1033 *
1034 * a) SYN in ORIGINAL
1035 * b) SYN/ACK in REPLY
1036 * c) ACK in reply direction after initial SYN in original.
1037 *
1038 * If the ignored packet is invalid, the receiver will send
1039 * a RST we'll catch below.
1040 */
1041 if (index == TCP_SYNACK_SET
1042 && ct->proto.tcp.last_index == TCP_SYN_SET
1043 && ct->proto.tcp.last_dir != dir
1044 && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1045 /* b) This SYN/ACK acknowledges a SYN that we earlier
1046 * ignored as invalid. This means that the client and
1047 * the server are both in sync, while the firewall is
1048 * not. We get in sync from the previously annotated
1049 * values.
1050 */
1051 old_state = TCP_CONNTRACK_SYN_SENT;
1052 new_state = TCP_CONNTRACK_SYN_RECV;
1053 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
1054 ct->proto.tcp.last_end;
1055 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
1056 ct->proto.tcp.last_end;
1057 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
1058 ct->proto.tcp.last_win == 0 ?
1059 1 : ct->proto.tcp.last_win;
1060 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
1061 ct->proto.tcp.last_wscale;
1062 ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1063 ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
1064 ct->proto.tcp.last_flags;
1065 nf_ct_tcp_state_reset(state: &ct->proto.tcp.seen[dir]);
1066 break;
1067 }
1068 ct->proto.tcp.last_index = index;
1069 ct->proto.tcp.last_dir = dir;
1070 ct->proto.tcp.last_seq = ntohl(th->seq);
1071 ct->proto.tcp.last_end =
1072 segment_seq_plus_len(ntohl(th->seq), len: skb->len, dataoff, tcph: th);
1073 ct->proto.tcp.last_win = ntohs(th->window);
1074
1075 /* a) This is a SYN in ORIGINAL. The client and the server
1076 * may be in sync but we are not. In that case, we annotate
1077 * the TCP options and let the packet go through. If it is a
1078 * valid SYN packet, the server will reply with a SYN/ACK, and
1079 * then we'll get in sync. Otherwise, the server potentially
1080 * responds with a challenge ACK if implementing RFC5961.
1081 */
1082 if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
1083 struct ip_ct_tcp_state seen = {};
1084
1085 ct->proto.tcp.last_flags =
1086 ct->proto.tcp.last_wscale = 0;
1087 tcp_options(skb, dataoff, tcph: th, state: &seen);
1088 if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1089 ct->proto.tcp.last_flags |=
1090 IP_CT_TCP_FLAG_WINDOW_SCALE;
1091 ct->proto.tcp.last_wscale = seen.td_scale;
1092 }
1093 if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
1094 ct->proto.tcp.last_flags |=
1095 IP_CT_TCP_FLAG_SACK_PERM;
1096 }
1097 /* Mark the potential for RFC5961 challenge ACK,
1098 * this pose a special problem for LAST_ACK state
1099 * as ACK is intrepretated as ACKing last FIN.
1100 */
1101 if (old_state == TCP_CONNTRACK_LAST_ACK)
1102 ct->proto.tcp.last_flags |=
1103 IP_CT_EXP_CHALLENGE_ACK;
1104 }
1105
1106 /* possible challenge ack reply to syn */
1107 if (old_state == TCP_CONNTRACK_SYN_SENT &&
1108 index == TCP_ACK_SET &&
1109 dir == IP_CT_DIR_REPLY)
1110 ct->proto.tcp.last_ack = ntohl(th->ack_seq);
1111
1112 spin_unlock_bh(lock: &ct->lock);
1113 nf_ct_l4proto_log_invalid(skb, ct, state,
1114 fmt: "packet (index %d) in dir %d ignored, state %s",
1115 index, dir,
1116 tcp_conntrack_names[old_state]);
1117 return NF_ACCEPT;
1118 case TCP_CONNTRACK_MAX:
1119 /* Special case for SYN proxy: when the SYN to the server or
1120 * the SYN/ACK from the server is lost, the client may transmit
1121 * a keep-alive packet while in SYN_SENT state. This needs to
1122 * be associated with the original conntrack entry in order to
1123 * generate a new SYN with the correct sequence number.
1124 */
1125 if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
1126 index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
1127 ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
1128 ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
1129 pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
1130 spin_unlock_bh(lock: &ct->lock);
1131 return NF_ACCEPT;
1132 }
1133
1134 /* Invalid packet */
1135 spin_unlock_bh(lock: &ct->lock);
1136 nf_ct_l4proto_log_invalid(skb, ct, state,
1137 fmt: "packet (index %d) in dir %d invalid, state %s",
1138 index, dir,
1139 tcp_conntrack_names[old_state]);
1140 return -NF_ACCEPT;
1141 case TCP_CONNTRACK_TIME_WAIT:
1142 /* RFC5961 compliance cause stack to send "challenge-ACK"
1143 * e.g. in response to spurious SYNs. Conntrack MUST
1144 * not believe this ACK is acking last FIN.
1145 */
1146 if (old_state == TCP_CONNTRACK_LAST_ACK &&
1147 index == TCP_ACK_SET &&
1148 ct->proto.tcp.last_dir != dir &&
1149 ct->proto.tcp.last_index == TCP_SYN_SET &&
1150 (ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
1151 /* Detected RFC5961 challenge ACK */
1152 ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1153 spin_unlock_bh(lock: &ct->lock);
1154 nf_ct_l4proto_log_invalid(skb, ct, state, fmt: "challenge-ack ignored");
1155 return NF_ACCEPT; /* Don't change state */
1156 }
1157 break;
1158 case TCP_CONNTRACK_SYN_SENT2:
1159 /* tcp_conntracks table is not smart enough to handle
1160 * simultaneous open.
1161 */
1162 ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN;
1163 break;
1164 case TCP_CONNTRACK_SYN_RECV:
1165 if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET &&
1166 ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN)
1167 new_state = TCP_CONNTRACK_ESTABLISHED;
1168 break;
1169 case TCP_CONNTRACK_CLOSE:
1170 if (index != TCP_RST_SET)
1171 break;
1172
1173 /* If we are closing, tuple might have been re-used already.
1174 * last_index, last_ack, and all other ct fields used for
1175 * sequence/window validation are outdated in that case.
1176 *
1177 * As the conntrack can already be expired by GC under pressure,
1178 * just skip validation checks.
1179 */
1180 if (tcp_can_early_drop(ct))
1181 goto in_window;
1182
1183 /* td_maxack might be outdated if we let a SYN through earlier */
1184 if ((ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) &&
1185 ct->proto.tcp.last_index != TCP_SYN_SET) {
1186 u32 seq = ntohl(th->seq);
1187
1188 /* If we are not in established state and SEQ=0 this is most
1189 * likely an answer to a SYN we let go through above (last_index
1190 * can be updated due to out-of-order ACKs).
1191 */
1192 if (seq == 0 && !nf_conntrack_tcp_established(ct))
1193 break;
1194
1195 if (before(seq1: seq, seq2: ct->proto.tcp.seen[!dir].td_maxack) &&
1196 !tn->tcp_ignore_invalid_rst) {
1197 /* Invalid RST */
1198 spin_unlock_bh(lock: &ct->lock);
1199 nf_ct_l4proto_log_invalid(skb, ct, state, fmt: "invalid rst");
1200 return -NF_ACCEPT;
1201 }
1202
1203 if (!nf_conntrack_tcp_established(ct) ||
1204 seq == ct->proto.tcp.seen[!dir].td_maxack)
1205 break;
1206
1207 /* Check if rst is part of train, such as
1208 * foo:80 > bar:4379: P, 235946583:235946602(19) ack 42
1209 * foo:80 > bar:4379: R, 235946602:235946602(0) ack 42
1210 */
1211 if (ct->proto.tcp.last_index == TCP_ACK_SET &&
1212 ct->proto.tcp.last_dir == dir &&
1213 seq == ct->proto.tcp.last_end)
1214 break;
1215
1216 /* ... RST sequence number doesn't match exactly, keep
1217 * established state to allow a possible challenge ACK.
1218 */
1219 new_state = old_state;
1220 }
1221 if (((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
1222 && ct->proto.tcp.last_index == TCP_SYN_SET)
1223 || (!test_bit(IPS_ASSURED_BIT, &ct->status)
1224 && ct->proto.tcp.last_index == TCP_ACK_SET))
1225 && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1226 /* RST sent to invalid SYN or ACK we had let through
1227 * at a) and c) above:
1228 *
1229 * a) SYN was in window then
1230 * c) we hold a half-open connection.
1231 *
1232 * Delete our connection entry.
1233 * We skip window checking, because packet might ACK
1234 * segments we ignored. */
1235 goto in_window;
1236 }
1237
1238 /* Reset in response to a challenge-ack we let through earlier */
1239 if (old_state == TCP_CONNTRACK_SYN_SENT &&
1240 ct->proto.tcp.last_index == TCP_ACK_SET &&
1241 ct->proto.tcp.last_dir == IP_CT_DIR_REPLY &&
1242 ntohl(th->seq) == ct->proto.tcp.last_ack)
1243 goto in_window;
1244
1245 break;
1246 default:
1247 /* Keep compilers happy. */
1248 break;
1249 }
1250
1251 res = tcp_in_window(ct, dir, index,
1252 skb, dataoff, tcph: th, hook_state: state);
1253 switch (res) {
1254 case NFCT_TCP_IGNORE:
1255 spin_unlock_bh(lock: &ct->lock);
1256 return NF_ACCEPT;
1257 case NFCT_TCP_INVALID:
1258 nf_tcp_handle_invalid(ct, dir, index, skb, hook_state: state);
1259 spin_unlock_bh(lock: &ct->lock);
1260 return -NF_ACCEPT;
1261 case NFCT_TCP_ACCEPT:
1262 break;
1263 }
1264 in_window:
1265 /* From now on we have got in-window packets */
1266 ct->proto.tcp.last_index = index;
1267 ct->proto.tcp.last_dir = dir;
1268
1269 ct->proto.tcp.state = new_state;
1270 if (old_state != new_state
1271 && new_state == TCP_CONNTRACK_FIN_WAIT)
1272 ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
1273
1274 timeouts = nf_ct_timeout_lookup(ct);
1275 if (!timeouts)
1276 timeouts = tn->timeouts;
1277
1278 if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
1279 timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1280 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1281 else if (unlikely(index == TCP_RST_SET))
1282 timeout = timeouts[TCP_CONNTRACK_CLOSE];
1283 else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
1284 IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
1285 timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
1286 timeout = timeouts[TCP_CONNTRACK_UNACK];
1287 else if (ct->proto.tcp.last_win == 0 &&
1288 timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1289 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1290 else
1291 timeout = timeouts[new_state];
1292 spin_unlock_bh(lock: &ct->lock);
1293
1294 if (new_state != old_state)
1295 nf_conntrack_event_cache(event: IPCT_PROTOINFO, ct);
1296
1297 if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
1298 /* If only reply is a RST, we can consider ourselves not to
1299 have an established connection: this is a fairly common
1300 problem case, so we can delete the conntrack
1301 immediately. --RR */
1302 if (th->rst) {
1303 nf_ct_kill_acct(ct, ctinfo, skb);
1304 return NF_ACCEPT;
1305 }
1306
1307 if (index == TCP_SYN_SET && old_state == TCP_CONNTRACK_SYN_SENT) {
1308 /* do not renew timeout on SYN retransmit.
1309 *
1310 * Else port reuse by client or NAT middlebox can keep
1311 * entry alive indefinitely (including nat info).
1312 */
1313 return NF_ACCEPT;
1314 }
1315
1316 /* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
1317 * pickup with loose=1. Avoid large ESTABLISHED timeout.
1318 */
1319 if (new_state == TCP_CONNTRACK_ESTABLISHED &&
1320 timeout > timeouts[TCP_CONNTRACK_UNACK])
1321 timeout = timeouts[TCP_CONNTRACK_UNACK];
1322 } else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
1323 && (old_state == TCP_CONNTRACK_SYN_RECV
1324 || old_state == TCP_CONNTRACK_ESTABLISHED)
1325 && new_state == TCP_CONNTRACK_ESTABLISHED) {
1326 /* Set ASSURED if we see valid ack in ESTABLISHED
1327 after SYN_RECV or a valid answer for a picked up
1328 connection. */
1329 set_bit(nr: IPS_ASSURED_BIT, addr: &ct->status);
1330 nf_conntrack_event_cache(event: IPCT_ASSURED, ct);
1331 }
1332 nf_ct_refresh_acct(ct, ctinfo, skb, extra_jiffies: timeout);
1333
1334 return NF_ACCEPT;
1335}
1336
1337#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1338
1339#include <linux/netfilter/nfnetlink.h>
1340#include <linux/netfilter/nfnetlink_conntrack.h>
1341
1342static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1343 struct nf_conn *ct, bool destroy)
1344{
1345 struct nlattr *nest_parms;
1346 struct nf_ct_tcp_flags tmp = {};
1347
1348 spin_lock_bh(lock: &ct->lock);
1349 nest_parms = nla_nest_start(skb, attrtype: CTA_PROTOINFO_TCP);
1350 if (!nest_parms)
1351 goto nla_put_failure;
1352
1353 if (nla_put_u8(skb, attrtype: CTA_PROTOINFO_TCP_STATE, value: ct->proto.tcp.state))
1354 goto nla_put_failure;
1355
1356 if (destroy)
1357 goto skip_state;
1358
1359 if (nla_put_u8(skb, attrtype: CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1360 value: ct->proto.tcp.seen[0].td_scale) ||
1361 nla_put_u8(skb, attrtype: CTA_PROTOINFO_TCP_WSCALE_REPLY,
1362 value: ct->proto.tcp.seen[1].td_scale))
1363 goto nla_put_failure;
1364
1365 tmp.flags = ct->proto.tcp.seen[0].flags;
1366 if (nla_put(skb, attrtype: CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1367 attrlen: sizeof(struct nf_ct_tcp_flags), data: &tmp))
1368 goto nla_put_failure;
1369
1370 tmp.flags = ct->proto.tcp.seen[1].flags;
1371 if (nla_put(skb, attrtype: CTA_PROTOINFO_TCP_FLAGS_REPLY,
1372 attrlen: sizeof(struct nf_ct_tcp_flags), data: &tmp))
1373 goto nla_put_failure;
1374skip_state:
1375 spin_unlock_bh(lock: &ct->lock);
1376 nla_nest_end(skb, start: nest_parms);
1377
1378 return 0;
1379
1380nla_put_failure:
1381 spin_unlock_bh(lock: &ct->lock);
1382 return -1;
1383}
1384
1385static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1386 [CTA_PROTOINFO_TCP_STATE] = { .type = NLA_U8 },
1387 [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1388 [CTA_PROTOINFO_TCP_WSCALE_REPLY] = { .type = NLA_U8 },
1389 [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL] = { .len = sizeof(struct nf_ct_tcp_flags) },
1390 [CTA_PROTOINFO_TCP_FLAGS_REPLY] = { .len = sizeof(struct nf_ct_tcp_flags) },
1391};
1392
1393#define TCP_NLATTR_SIZE ( \
1394 NLA_ALIGN(NLA_HDRLEN + 1) + \
1395 NLA_ALIGN(NLA_HDRLEN + 1) + \
1396 NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)) + \
1397 NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)))
1398
1399static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1400{
1401 struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
1402 struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1403 int err;
1404
1405 /* updates could not contain anything about the private
1406 * protocol info, in that case skip the parsing */
1407 if (!pattr)
1408 return 0;
1409
1410 err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_TCP_MAX, nla: pattr,
1411 policy: tcp_nla_policy, NULL);
1412 if (err < 0)
1413 return err;
1414
1415 if (tb[CTA_PROTOINFO_TCP_STATE] &&
1416 nla_get_u8(nla: tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
1417 return -EINVAL;
1418
1419 spin_lock_bh(lock: &ct->lock);
1420 if (tb[CTA_PROTOINFO_TCP_STATE])
1421 ct->proto.tcp.state = nla_get_u8(nla: tb[CTA_PROTOINFO_TCP_STATE]);
1422
1423 if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1424 struct nf_ct_tcp_flags *attr =
1425 nla_data(nla: tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1426 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1427 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1428 }
1429
1430 if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1431 struct nf_ct_tcp_flags *attr =
1432 nla_data(nla: tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1433 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1434 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1435 }
1436
1437 if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1438 tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1439 ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1440 ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1441 ct->proto.tcp.seen[0].td_scale =
1442 nla_get_u8(nla: tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1443 ct->proto.tcp.seen[1].td_scale =
1444 nla_get_u8(nla: tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1445 }
1446 spin_unlock_bh(lock: &ct->lock);
1447
1448 return 0;
1449}
1450
1451static unsigned int tcp_nlattr_tuple_size(void)
1452{
1453 static unsigned int size __read_mostly;
1454
1455 if (!size)
1456 size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
1457
1458 return size;
1459}
1460#endif
1461
1462#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1463
1464#include <linux/netfilter/nfnetlink.h>
1465#include <linux/netfilter/nfnetlink_cttimeout.h>
1466
1467static int tcp_timeout_nlattr_to_obj(struct nlattr *tb[],
1468 struct net *net, void *data)
1469{
1470 struct nf_tcp_net *tn = nf_tcp_pernet(net);
1471 unsigned int *timeouts = data;
1472 int i;
1473
1474 if (!timeouts)
1475 timeouts = tn->timeouts;
1476 /* set default TCP timeouts. */
1477 for (i=0; i<TCP_CONNTRACK_TIMEOUT_MAX; i++)
1478 timeouts[i] = tn->timeouts[i];
1479
1480 if (tb[CTA_TIMEOUT_TCP_SYN_SENT]) {
1481 timeouts[TCP_CONNTRACK_SYN_SENT] =
1482 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT]))*HZ;
1483 }
1484
1485 if (tb[CTA_TIMEOUT_TCP_SYN_RECV]) {
1486 timeouts[TCP_CONNTRACK_SYN_RECV] =
1487 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_RECV]))*HZ;
1488 }
1489 if (tb[CTA_TIMEOUT_TCP_ESTABLISHED]) {
1490 timeouts[TCP_CONNTRACK_ESTABLISHED] =
1491 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_ESTABLISHED]))*HZ;
1492 }
1493 if (tb[CTA_TIMEOUT_TCP_FIN_WAIT]) {
1494 timeouts[TCP_CONNTRACK_FIN_WAIT] =
1495 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_FIN_WAIT]))*HZ;
1496 }
1497 if (tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]) {
1498 timeouts[TCP_CONNTRACK_CLOSE_WAIT] =
1499 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]))*HZ;
1500 }
1501 if (tb[CTA_TIMEOUT_TCP_LAST_ACK]) {
1502 timeouts[TCP_CONNTRACK_LAST_ACK] =
1503 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_LAST_ACK]))*HZ;
1504 }
1505 if (tb[CTA_TIMEOUT_TCP_TIME_WAIT]) {
1506 timeouts[TCP_CONNTRACK_TIME_WAIT] =
1507 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_TIME_WAIT]))*HZ;
1508 }
1509 if (tb[CTA_TIMEOUT_TCP_CLOSE]) {
1510 timeouts[TCP_CONNTRACK_CLOSE] =
1511 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE]))*HZ;
1512 }
1513 if (tb[CTA_TIMEOUT_TCP_SYN_SENT2]) {
1514 timeouts[TCP_CONNTRACK_SYN_SENT2] =
1515 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT2]))*HZ;
1516 }
1517 if (tb[CTA_TIMEOUT_TCP_RETRANS]) {
1518 timeouts[TCP_CONNTRACK_RETRANS] =
1519 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_RETRANS]))*HZ;
1520 }
1521 if (tb[CTA_TIMEOUT_TCP_UNACK]) {
1522 timeouts[TCP_CONNTRACK_UNACK] =
1523 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_UNACK]))*HZ;
1524 }
1525
1526 timeouts[CTA_TIMEOUT_TCP_UNSPEC] = timeouts[CTA_TIMEOUT_TCP_SYN_SENT];
1527 return 0;
1528}
1529
1530static int
1531tcp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
1532{
1533 const unsigned int *timeouts = data;
1534
1535 if (nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_SYN_SENT,
1536 htonl(timeouts[TCP_CONNTRACK_SYN_SENT] / HZ)) ||
1537 nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_SYN_RECV,
1538 htonl(timeouts[TCP_CONNTRACK_SYN_RECV] / HZ)) ||
1539 nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_ESTABLISHED,
1540 htonl(timeouts[TCP_CONNTRACK_ESTABLISHED] / HZ)) ||
1541 nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_FIN_WAIT,
1542 htonl(timeouts[TCP_CONNTRACK_FIN_WAIT] / HZ)) ||
1543 nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_CLOSE_WAIT,
1544 htonl(timeouts[TCP_CONNTRACK_CLOSE_WAIT] / HZ)) ||
1545 nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_LAST_ACK,
1546 htonl(timeouts[TCP_CONNTRACK_LAST_ACK] / HZ)) ||
1547 nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_TIME_WAIT,
1548 htonl(timeouts[TCP_CONNTRACK_TIME_WAIT] / HZ)) ||
1549 nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_CLOSE,
1550 htonl(timeouts[TCP_CONNTRACK_CLOSE] / HZ)) ||
1551 nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_SYN_SENT2,
1552 htonl(timeouts[TCP_CONNTRACK_SYN_SENT2] / HZ)) ||
1553 nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_RETRANS,
1554 htonl(timeouts[TCP_CONNTRACK_RETRANS] / HZ)) ||
1555 nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_UNACK,
1556 htonl(timeouts[TCP_CONNTRACK_UNACK] / HZ)))
1557 goto nla_put_failure;
1558 return 0;
1559
1560nla_put_failure:
1561 return -ENOSPC;
1562}
1563
1564static const struct nla_policy tcp_timeout_nla_policy[CTA_TIMEOUT_TCP_MAX+1] = {
1565 [CTA_TIMEOUT_TCP_SYN_SENT] = { .type = NLA_U32 },
1566 [CTA_TIMEOUT_TCP_SYN_RECV] = { .type = NLA_U32 },
1567 [CTA_TIMEOUT_TCP_ESTABLISHED] = { .type = NLA_U32 },
1568 [CTA_TIMEOUT_TCP_FIN_WAIT] = { .type = NLA_U32 },
1569 [CTA_TIMEOUT_TCP_CLOSE_WAIT] = { .type = NLA_U32 },
1570 [CTA_TIMEOUT_TCP_LAST_ACK] = { .type = NLA_U32 },
1571 [CTA_TIMEOUT_TCP_TIME_WAIT] = { .type = NLA_U32 },
1572 [CTA_TIMEOUT_TCP_CLOSE] = { .type = NLA_U32 },
1573 [CTA_TIMEOUT_TCP_SYN_SENT2] = { .type = NLA_U32 },
1574 [CTA_TIMEOUT_TCP_RETRANS] = { .type = NLA_U32 },
1575 [CTA_TIMEOUT_TCP_UNACK] = { .type = NLA_U32 },
1576};
1577#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1578
1579void nf_conntrack_tcp_init_net(struct net *net)
1580{
1581 struct nf_tcp_net *tn = nf_tcp_pernet(net);
1582 int i;
1583
1584 for (i = 0; i < TCP_CONNTRACK_TIMEOUT_MAX; i++)
1585 tn->timeouts[i] = tcp_timeouts[i];
1586
1587 /* timeouts[0] is unused, make it same as SYN_SENT so
1588 * ->timeouts[0] contains 'new' timeout, like udp or icmp.
1589 */
1590 tn->timeouts[0] = tcp_timeouts[TCP_CONNTRACK_SYN_SENT];
1591
1592 /* If it is set to zero, we disable picking up already established
1593 * connections.
1594 */
1595 tn->tcp_loose = 1;
1596
1597 /* "Be conservative in what you do,
1598 * be liberal in what you accept from others."
1599 * If it's non-zero, we mark only out of window RST segments as INVALID.
1600 */
1601 tn->tcp_be_liberal = 0;
1602
1603 /* If it's non-zero, we turn off RST sequence number check */
1604 tn->tcp_ignore_invalid_rst = 0;
1605
1606 /* Max number of the retransmitted packets without receiving an (acceptable)
1607 * ACK from the destination. If this number is reached, a shorter timer
1608 * will be started.
1609 */
1610 tn->tcp_max_retrans = 3;
1611
1612#if IS_ENABLED(CONFIG_NF_FLOW_TABLE)
1613 tn->offload_timeout = 30 * HZ;
1614#endif
1615}
1616
1617const struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp =
1618{
1619 .l4proto = IPPROTO_TCP,
1620#ifdef CONFIG_NF_CONNTRACK_PROCFS
1621 .print_conntrack = tcp_print_conntrack,
1622#endif
1623 .can_early_drop = tcp_can_early_drop,
1624#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1625 .to_nlattr = tcp_to_nlattr,
1626 .from_nlattr = nlattr_to_tcp,
1627 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
1628 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
1629 .nlattr_tuple_size = tcp_nlattr_tuple_size,
1630 .nlattr_size = TCP_NLATTR_SIZE,
1631 .nla_policy = nf_ct_port_nla_policy,
1632#endif
1633#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1634 .ctnl_timeout = {
1635 .nlattr_to_obj = tcp_timeout_nlattr_to_obj,
1636 .obj_to_nlattr = tcp_timeout_obj_to_nlattr,
1637 .nlattr_max = CTA_TIMEOUT_TCP_MAX,
1638 .obj_size = sizeof(unsigned int) *
1639 TCP_CONNTRACK_TIMEOUT_MAX,
1640 .nla_policy = tcp_timeout_nla_policy,
1641 },
1642#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1643};
1644

source code of linux/net/netfilter/nf_conntrack_proto_tcp.c