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Merge tag 'trace-v5.12-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt...
[mirror_ubuntu-jammy-kernel.git] / net / netfilter / nf_conntrack_proto_tcp.c
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 /* "Be conservative in what you do,
35 be liberal in what you accept from others."
36 If it's non-zero, we mark only out of window RST segments as INVALID. */
37 static int nf_ct_tcp_be_liberal __read_mostly = 0;
38
39 /* If it is set to zero, we disable picking up already established
40 connections. */
41 static int nf_ct_tcp_loose __read_mostly = 1;
42
43 /* Max number of the retransmitted packets without receiving an (acceptable)
44 ACK from the destination. If this number is reached, a shorter timer
45 will be started. */
46 static int nf_ct_tcp_max_retrans __read_mostly = 3;
47
48 /* FIXME: Examine ipfilter's timeouts and conntrack transitions more
49 closely. They're more complex. --RR */
50
51 static const char *const tcp_conntrack_names[] = {
52 "NONE",
53 "SYN_SENT",
54 "SYN_RECV",
55 "ESTABLISHED",
56 "FIN_WAIT",
57 "CLOSE_WAIT",
58 "LAST_ACK",
59 "TIME_WAIT",
60 "CLOSE",
61 "SYN_SENT2",
62 };
63
64 #define SECS * HZ
65 #define MINS * 60 SECS
66 #define HOURS * 60 MINS
67 #define DAYS * 24 HOURS
68
69 static const unsigned int tcp_timeouts[TCP_CONNTRACK_TIMEOUT_MAX] = {
70 [TCP_CONNTRACK_SYN_SENT] = 2 MINS,
71 [TCP_CONNTRACK_SYN_RECV] = 60 SECS,
72 [TCP_CONNTRACK_ESTABLISHED] = 5 DAYS,
73 [TCP_CONNTRACK_FIN_WAIT] = 2 MINS,
74 [TCP_CONNTRACK_CLOSE_WAIT] = 60 SECS,
75 [TCP_CONNTRACK_LAST_ACK] = 30 SECS,
76 [TCP_CONNTRACK_TIME_WAIT] = 2 MINS,
77 [TCP_CONNTRACK_CLOSE] = 10 SECS,
78 [TCP_CONNTRACK_SYN_SENT2] = 2 MINS,
79 /* RFC1122 says the R2 limit should be at least 100 seconds.
80 Linux uses 15 packets as limit, which corresponds
81 to ~13-30min depending on RTO. */
82 [TCP_CONNTRACK_RETRANS] = 5 MINS,
83 [TCP_CONNTRACK_UNACK] = 5 MINS,
84 };
85
86 #define sNO TCP_CONNTRACK_NONE
87 #define sSS TCP_CONNTRACK_SYN_SENT
88 #define sSR TCP_CONNTRACK_SYN_RECV
89 #define sES TCP_CONNTRACK_ESTABLISHED
90 #define sFW TCP_CONNTRACK_FIN_WAIT
91 #define sCW TCP_CONNTRACK_CLOSE_WAIT
92 #define sLA TCP_CONNTRACK_LAST_ACK
93 #define sTW TCP_CONNTRACK_TIME_WAIT
94 #define sCL TCP_CONNTRACK_CLOSE
95 #define sS2 TCP_CONNTRACK_SYN_SENT2
96 #define sIV TCP_CONNTRACK_MAX
97 #define sIG TCP_CONNTRACK_IGNORE
98
99 /* What TCP flags are set from RST/SYN/FIN/ACK. */
100 enum tcp_bit_set {
101 TCP_SYN_SET,
102 TCP_SYNACK_SET,
103 TCP_FIN_SET,
104 TCP_ACK_SET,
105 TCP_RST_SET,
106 TCP_NONE_SET,
107 };
108
109 /*
110 * The TCP state transition table needs a few words...
111 *
112 * We are the man in the middle. All the packets go through us
113 * but might get lost in transit to the destination.
114 * It is assumed that the destinations can't receive segments
115 * we haven't seen.
116 *
117 * The checked segment is in window, but our windows are *not*
118 * equivalent with the ones of the sender/receiver. We always
119 * try to guess the state of the current sender.
120 *
121 * The meaning of the states are:
122 *
123 * NONE: initial state
124 * SYN_SENT: SYN-only packet seen
125 * SYN_SENT2: SYN-only packet seen from reply dir, simultaneous open
126 * SYN_RECV: SYN-ACK packet seen
127 * ESTABLISHED: ACK packet seen
128 * FIN_WAIT: FIN packet seen
129 * CLOSE_WAIT: ACK seen (after FIN)
130 * LAST_ACK: FIN seen (after FIN)
131 * TIME_WAIT: last ACK seen
132 * CLOSE: closed connection (RST)
133 *
134 * Packets marked as IGNORED (sIG):
135 * if they may be either invalid or valid
136 * and the receiver may send back a connection
137 * closing RST or a SYN/ACK.
138 *
139 * Packets marked as INVALID (sIV):
140 * if we regard them as truly invalid packets
141 */
142 static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
143 {
144 /* ORIGINAL */
145 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
146 /*syn*/ { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sS2 },
147 /*
148 * sNO -> sSS Initialize a new connection
149 * sSS -> sSS Retransmitted SYN
150 * sS2 -> sS2 Late retransmitted SYN
151 * sSR -> sIG
152 * sES -> sIG Error: SYNs in window outside the SYN_SENT state
153 * are errors. Receiver will reply with RST
154 * and close the connection.
155 * Or we are not in sync and hold a dead connection.
156 * sFW -> sIG
157 * sCW -> sIG
158 * sLA -> sIG
159 * sTW -> sSS Reopened connection (RFC 1122).
160 * sCL -> sSS
161 */
162 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
163 /*synack*/ { sIV, sIV, sSR, sIV, sIV, sIV, sIV, sIV, sIV, sSR },
164 /*
165 * sNO -> sIV Too late and no reason to do anything
166 * sSS -> sIV Client can't send SYN and then SYN/ACK
167 * sS2 -> sSR SYN/ACK sent to SYN2 in simultaneous open
168 * sSR -> sSR Late retransmitted SYN/ACK in simultaneous open
169 * sES -> sIV Invalid SYN/ACK packets sent by the client
170 * sFW -> sIV
171 * sCW -> sIV
172 * sLA -> sIV
173 * sTW -> sIV
174 * sCL -> sIV
175 */
176 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
177 /*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
178 /*
179 * sNO -> sIV Too late and no reason to do anything...
180 * sSS -> sIV Client migth not send FIN in this state:
181 * we enforce waiting for a SYN/ACK reply first.
182 * sS2 -> sIV
183 * sSR -> sFW Close started.
184 * sES -> sFW
185 * sFW -> sLA FIN seen in both directions, waiting for
186 * the last ACK.
187 * Migth be a retransmitted FIN as well...
188 * sCW -> sLA
189 * sLA -> sLA Retransmitted FIN. Remain in the same state.
190 * sTW -> sTW
191 * sCL -> sCL
192 */
193 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
194 /*ack*/ { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV },
195 /*
196 * sNO -> sES Assumed.
197 * sSS -> sIV ACK is invalid: we haven't seen a SYN/ACK yet.
198 * sS2 -> sIV
199 * sSR -> sES Established state is reached.
200 * sES -> sES :-)
201 * sFW -> sCW Normal close request answered by ACK.
202 * sCW -> sCW
203 * sLA -> sTW Last ACK detected (RFC5961 challenged)
204 * sTW -> sTW Retransmitted last ACK. Remain in the same state.
205 * sCL -> sCL
206 */
207 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
208 /*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
209 /*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
210 },
211 {
212 /* REPLY */
213 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
214 /*syn*/ { sIV, sS2, sIV, sIV, sIV, sIV, sIV, sSS, sIV, sS2 },
215 /*
216 * sNO -> sIV Never reached.
217 * sSS -> sS2 Simultaneous open
218 * sS2 -> sS2 Retransmitted simultaneous SYN
219 * sSR -> sIV Invalid SYN packets sent by the server
220 * sES -> sIV
221 * sFW -> sIV
222 * sCW -> sIV
223 * sLA -> sIV
224 * sTW -> sSS Reopened connection, but server may have switched role
225 * sCL -> sIV
226 */
227 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
228 /*synack*/ { sIV, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIG, sSR },
229 /*
230 * sSS -> sSR Standard open.
231 * sS2 -> sSR Simultaneous open
232 * sSR -> sIG Retransmitted SYN/ACK, ignore it.
233 * sES -> sIG Late retransmitted SYN/ACK?
234 * sFW -> sIG Might be SYN/ACK answering ignored SYN
235 * sCW -> sIG
236 * sLA -> sIG
237 * sTW -> sIG
238 * sCL -> sIG
239 */
240 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
241 /*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
242 /*
243 * sSS -> sIV Server might not send FIN in this state.
244 * sS2 -> sIV
245 * sSR -> sFW Close started.
246 * sES -> sFW
247 * sFW -> sLA FIN seen in both directions.
248 * sCW -> sLA
249 * sLA -> sLA Retransmitted FIN.
250 * sTW -> sTW
251 * sCL -> sCL
252 */
253 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
254 /*ack*/ { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIG },
255 /*
256 * sSS -> sIG Might be a half-open connection.
257 * sS2 -> sIG
258 * sSR -> sSR Might answer late resent SYN.
259 * sES -> sES :-)
260 * sFW -> sCW Normal close request answered by ACK.
261 * sCW -> sCW
262 * sLA -> sTW Last ACK detected (RFC5961 challenged)
263 * sTW -> sTW Retransmitted last ACK.
264 * sCL -> sCL
265 */
266 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
267 /*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
268 /*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
269 }
270 };
271
272 #ifdef CONFIG_NF_CONNTRACK_PROCFS
273 /* Print out the private part of the conntrack. */
274 static void tcp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
275 {
276 if (test_bit(IPS_OFFLOAD_BIT, &ct->status))
277 return;
278
279 seq_printf(s, "%s ", tcp_conntrack_names[ct->proto.tcp.state]);
280 }
281 #endif
282
283 static unsigned int get_conntrack_index(const struct tcphdr *tcph)
284 {
285 if (tcph->rst) return TCP_RST_SET;
286 else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET);
287 else if (tcph->fin) return TCP_FIN_SET;
288 else if (tcph->ack) return TCP_ACK_SET;
289 else return TCP_NONE_SET;
290 }
291
292 /* TCP connection tracking based on 'Real Stateful TCP Packet Filtering
293 in IP Filter' by Guido van Rooij.
294
295 http://www.sane.nl/events/sane2000/papers.html
296 http://www.darkart.com/mirrors/www.obfuscation.org/ipf/
297
298 The boundaries and the conditions are changed according to RFC793:
299 the packet must intersect the window (i.e. segments may be
300 after the right or before the left edge) and thus receivers may ACK
301 segments after the right edge of the window.
302
303 td_maxend = max(sack + max(win,1)) seen in reply packets
304 td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets
305 td_maxwin += seq + len - sender.td_maxend
306 if seq + len > sender.td_maxend
307 td_end = max(seq + len) seen in sent packets
308
309 I. Upper bound for valid data: seq <= sender.td_maxend
310 II. Lower bound for valid data: seq + len >= sender.td_end - receiver.td_maxwin
311 III. Upper bound for valid (s)ack: sack <= receiver.td_end
312 IV. Lower bound for valid (s)ack: sack >= receiver.td_end - MAXACKWINDOW
313
314 where sack is the highest right edge of sack block found in the packet
315 or ack in the case of packet without SACK option.
316
317 The upper bound limit for a valid (s)ack is not ignored -
318 we doesn't have to deal with fragments.
319 */
320
321 static inline __u32 segment_seq_plus_len(__u32 seq,
322 size_t len,
323 unsigned int dataoff,
324 const struct tcphdr *tcph)
325 {
326 /* XXX Should I use payload length field in IP/IPv6 header ?
327 * - YK */
328 return (seq + len - dataoff - tcph->doff*4
329 + (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0));
330 }
331
332 /* Fixme: what about big packets? */
333 #define MAXACKWINCONST 66000
334 #define MAXACKWINDOW(sender) \
335 ((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin \
336 : MAXACKWINCONST)
337
338 /*
339 * Simplified tcp_parse_options routine from tcp_input.c
340 */
341 static void tcp_options(const struct sk_buff *skb,
342 unsigned int dataoff,
343 const struct tcphdr *tcph,
344 struct ip_ct_tcp_state *state)
345 {
346 unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
347 const unsigned char *ptr;
348 int length = (tcph->doff*4) - sizeof(struct tcphdr);
349
350 if (!length)
351 return;
352
353 ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
354 length, buff);
355 BUG_ON(ptr == NULL);
356
357 state->td_scale =
358 state->flags = 0;
359
360 while (length > 0) {
361 int opcode=*ptr++;
362 int opsize;
363
364 switch (opcode) {
365 case TCPOPT_EOL:
366 return;
367 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
368 length--;
369 continue;
370 default:
371 if (length < 2)
372 return;
373 opsize=*ptr++;
374 if (opsize < 2) /* "silly options" */
375 return;
376 if (opsize > length)
377 return; /* don't parse partial options */
378
379 if (opcode == TCPOPT_SACK_PERM
380 && opsize == TCPOLEN_SACK_PERM)
381 state->flags |= IP_CT_TCP_FLAG_SACK_PERM;
382 else if (opcode == TCPOPT_WINDOW
383 && opsize == TCPOLEN_WINDOW) {
384 state->td_scale = *(u_int8_t *)ptr;
385
386 if (state->td_scale > TCP_MAX_WSCALE)
387 state->td_scale = TCP_MAX_WSCALE;
388
389 state->flags |=
390 IP_CT_TCP_FLAG_WINDOW_SCALE;
391 }
392 ptr += opsize - 2;
393 length -= opsize;
394 }
395 }
396 }
397
398 static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
399 const struct tcphdr *tcph, __u32 *sack)
400 {
401 unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
402 const unsigned char *ptr;
403 int length = (tcph->doff*4) - sizeof(struct tcphdr);
404 __u32 tmp;
405
406 if (!length)
407 return;
408
409 ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
410 length, buff);
411 BUG_ON(ptr == NULL);
412
413 /* Fast path for timestamp-only option */
414 if (length == TCPOLEN_TSTAMP_ALIGNED
415 && *(__be32 *)ptr == htonl((TCPOPT_NOP << 24)
416 | (TCPOPT_NOP << 16)
417 | (TCPOPT_TIMESTAMP << 8)
418 | TCPOLEN_TIMESTAMP))
419 return;
420
421 while (length > 0) {
422 int opcode = *ptr++;
423 int opsize, i;
424
425 switch (opcode) {
426 case TCPOPT_EOL:
427 return;
428 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
429 length--;
430 continue;
431 default:
432 if (length < 2)
433 return;
434 opsize = *ptr++;
435 if (opsize < 2) /* "silly options" */
436 return;
437 if (opsize > length)
438 return; /* don't parse partial options */
439
440 if (opcode == TCPOPT_SACK
441 && opsize >= (TCPOLEN_SACK_BASE
442 + TCPOLEN_SACK_PERBLOCK)
443 && !((opsize - TCPOLEN_SACK_BASE)
444 % TCPOLEN_SACK_PERBLOCK)) {
445 for (i = 0;
446 i < (opsize - TCPOLEN_SACK_BASE);
447 i += TCPOLEN_SACK_PERBLOCK) {
448 tmp = get_unaligned_be32((__be32 *)(ptr+i)+1);
449
450 if (after(tmp, *sack))
451 *sack = tmp;
452 }
453 return;
454 }
455 ptr += opsize - 2;
456 length -= opsize;
457 }
458 }
459 }
460
461 static bool tcp_in_window(const struct nf_conn *ct,
462 struct ip_ct_tcp *state,
463 enum ip_conntrack_dir dir,
464 unsigned int index,
465 const struct sk_buff *skb,
466 unsigned int dataoff,
467 const struct tcphdr *tcph)
468 {
469 struct net *net = nf_ct_net(ct);
470 struct nf_tcp_net *tn = nf_tcp_pernet(net);
471 struct ip_ct_tcp_state *sender = &state->seen[dir];
472 struct ip_ct_tcp_state *receiver = &state->seen[!dir];
473 const struct nf_conntrack_tuple *tuple = &ct->tuplehash[dir].tuple;
474 __u32 seq, ack, sack, end, win, swin;
475 u16 win_raw;
476 s32 receiver_offset;
477 bool res, in_recv_win;
478
479 /*
480 * Get the required data from the packet.
481 */
482 seq = ntohl(tcph->seq);
483 ack = sack = ntohl(tcph->ack_seq);
484 win_raw = ntohs(tcph->window);
485 win = win_raw;
486 end = segment_seq_plus_len(seq, skb->len, dataoff, tcph);
487
488 if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
489 tcp_sack(skb, dataoff, tcph, &sack);
490
491 /* Take into account NAT sequence number mangling */
492 receiver_offset = nf_ct_seq_offset(ct, !dir, ack - 1);
493 ack -= receiver_offset;
494 sack -= receiver_offset;
495
496 pr_debug("tcp_in_window: START\n");
497 pr_debug("tcp_in_window: ");
498 nf_ct_dump_tuple(tuple);
499 pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
500 seq, ack, receiver_offset, sack, receiver_offset, win, end);
501 pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
502 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
503 sender->td_end, sender->td_maxend, sender->td_maxwin,
504 sender->td_scale,
505 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
506 receiver->td_scale);
507
508 if (sender->td_maxwin == 0) {
509 /*
510 * Initialize sender data.
511 */
512 if (tcph->syn) {
513 /*
514 * SYN-ACK in reply to a SYN
515 * or SYN from reply direction in simultaneous open.
516 */
517 sender->td_end =
518 sender->td_maxend = end;
519 sender->td_maxwin = (win == 0 ? 1 : win);
520
521 tcp_options(skb, dataoff, tcph, sender);
522 /*
523 * RFC 1323:
524 * Both sides must send the Window Scale option
525 * to enable window scaling in either direction.
526 */
527 if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE
528 && receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE))
529 sender->td_scale =
530 receiver->td_scale = 0;
531 if (!tcph->ack)
532 /* Simultaneous open */
533 return true;
534 } else {
535 /*
536 * We are in the middle of a connection,
537 * its history is lost for us.
538 * Let's try to use the data from the packet.
539 */
540 sender->td_end = end;
541 swin = win << sender->td_scale;
542 sender->td_maxwin = (swin == 0 ? 1 : swin);
543 sender->td_maxend = end + sender->td_maxwin;
544 if (receiver->td_maxwin == 0) {
545 /* We haven't seen traffic in the other
546 * direction yet but we have to tweak window
547 * tracking to pass III and IV until that
548 * happens.
549 */
550 receiver->td_end = receiver->td_maxend = sack;
551 } else if (sack == receiver->td_end + 1) {
552 /* Likely a reply to a keepalive.
553 * Needed for III.
554 */
555 receiver->td_end++;
556 }
557
558 }
559 } else if (((state->state == TCP_CONNTRACK_SYN_SENT
560 && dir == IP_CT_DIR_ORIGINAL)
561 || (state->state == TCP_CONNTRACK_SYN_RECV
562 && dir == IP_CT_DIR_REPLY))
563 && after(end, sender->td_end)) {
564 /*
565 * RFC 793: "if a TCP is reinitialized ... then it need
566 * not wait at all; it must only be sure to use sequence
567 * numbers larger than those recently used."
568 */
569 sender->td_end =
570 sender->td_maxend = end;
571 sender->td_maxwin = (win == 0 ? 1 : win);
572
573 tcp_options(skb, dataoff, tcph, sender);
574 }
575
576 if (!(tcph->ack)) {
577 /*
578 * If there is no ACK, just pretend it was set and OK.
579 */
580 ack = sack = receiver->td_end;
581 } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
582 (TCP_FLAG_ACK|TCP_FLAG_RST))
583 && (ack == 0)) {
584 /*
585 * Broken TCP stacks, that set ACK in RST packets as well
586 * with zero ack value.
587 */
588 ack = sack = receiver->td_end;
589 }
590
591 if (tcph->rst && seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)
592 /*
593 * RST sent answering SYN.
594 */
595 seq = end = sender->td_end;
596
597 pr_debug("tcp_in_window: ");
598 nf_ct_dump_tuple(tuple);
599 pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
600 seq, ack, receiver_offset, sack, receiver_offset, win, end);
601 pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
602 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
603 sender->td_end, sender->td_maxend, sender->td_maxwin,
604 sender->td_scale,
605 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
606 receiver->td_scale);
607
608 /* Is the ending sequence in the receive window (if available)? */
609 in_recv_win = !receiver->td_maxwin ||
610 after(end, sender->td_end - receiver->td_maxwin - 1);
611
612 pr_debug("tcp_in_window: I=%i II=%i III=%i IV=%i\n",
613 before(seq, sender->td_maxend + 1),
614 (in_recv_win ? 1 : 0),
615 before(sack, receiver->td_end + 1),
616 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1));
617
618 if (before(seq, sender->td_maxend + 1) &&
619 in_recv_win &&
620 before(sack, receiver->td_end + 1) &&
621 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1)) {
622 /*
623 * Take into account window scaling (RFC 1323).
624 */
625 if (!tcph->syn)
626 win <<= sender->td_scale;
627
628 /*
629 * Update sender data.
630 */
631 swin = win + (sack - ack);
632 if (sender->td_maxwin < swin)
633 sender->td_maxwin = swin;
634 if (after(end, sender->td_end)) {
635 sender->td_end = end;
636 sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
637 }
638 if (tcph->ack) {
639 if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) {
640 sender->td_maxack = ack;
641 sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET;
642 } else if (after(ack, sender->td_maxack))
643 sender->td_maxack = ack;
644 }
645
646 /*
647 * Update receiver data.
648 */
649 if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
650 receiver->td_maxwin += end - sender->td_maxend;
651 if (after(sack + win, receiver->td_maxend - 1)) {
652 receiver->td_maxend = sack + win;
653 if (win == 0)
654 receiver->td_maxend++;
655 }
656 if (ack == receiver->td_end)
657 receiver->flags &= ~IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
658
659 /*
660 * Check retransmissions.
661 */
662 if (index == TCP_ACK_SET) {
663 if (state->last_dir == dir
664 && state->last_seq == seq
665 && state->last_ack == ack
666 && state->last_end == end
667 && state->last_win == win_raw)
668 state->retrans++;
669 else {
670 state->last_dir = dir;
671 state->last_seq = seq;
672 state->last_ack = ack;
673 state->last_end = end;
674 state->last_win = win_raw;
675 state->retrans = 0;
676 }
677 }
678 res = true;
679 } else {
680 res = false;
681 if (sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL ||
682 tn->tcp_be_liberal)
683 res = true;
684 if (!res) {
685 nf_ct_l4proto_log_invalid(skb, ct,
686 "%s",
687 before(seq, sender->td_maxend + 1) ?
688 in_recv_win ?
689 before(sack, receiver->td_end + 1) ?
690 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1) ? "BUG"
691 : "ACK is under the lower bound (possible overly delayed ACK)"
692 : "ACK is over the upper bound (ACKed data not seen yet)"
693 : "SEQ is under the lower bound (already ACKed data retransmitted)"
694 : "SEQ is over the upper bound (over the window of the receiver)");
695 }
696 }
697
698 pr_debug("tcp_in_window: res=%u sender end=%u maxend=%u maxwin=%u "
699 "receiver end=%u maxend=%u maxwin=%u\n",
700 res, sender->td_end, sender->td_maxend, sender->td_maxwin,
701 receiver->td_end, receiver->td_maxend, receiver->td_maxwin);
702
703 return res;
704 }
705
706 /* table of valid flag combinations - PUSH, ECE and CWR are always valid */
707 static const u8 tcp_valid_flags[(TCPHDR_FIN|TCPHDR_SYN|TCPHDR_RST|TCPHDR_ACK|
708 TCPHDR_URG) + 1] =
709 {
710 [TCPHDR_SYN] = 1,
711 [TCPHDR_SYN|TCPHDR_URG] = 1,
712 [TCPHDR_SYN|TCPHDR_ACK] = 1,
713 [TCPHDR_RST] = 1,
714 [TCPHDR_RST|TCPHDR_ACK] = 1,
715 [TCPHDR_FIN|TCPHDR_ACK] = 1,
716 [TCPHDR_FIN|TCPHDR_ACK|TCPHDR_URG] = 1,
717 [TCPHDR_ACK] = 1,
718 [TCPHDR_ACK|TCPHDR_URG] = 1,
719 };
720
721 static void tcp_error_log(const struct sk_buff *skb,
722 const struct nf_hook_state *state,
723 const char *msg)
724 {
725 nf_l4proto_log_invalid(skb, state->net, state->pf, IPPROTO_TCP, "%s", msg);
726 }
727
728 /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c. */
729 static bool tcp_error(const struct tcphdr *th,
730 struct sk_buff *skb,
731 unsigned int dataoff,
732 const struct nf_hook_state *state)
733 {
734 unsigned int tcplen = skb->len - dataoff;
735 u8 tcpflags;
736
737 /* Not whole TCP header or malformed packet */
738 if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
739 tcp_error_log(skb, state, "truncated packet");
740 return true;
741 }
742
743 /* Checksum invalid? Ignore.
744 * We skip checking packets on the outgoing path
745 * because the checksum is assumed to be correct.
746 */
747 /* FIXME: Source route IP option packets --RR */
748 if (state->net->ct.sysctl_checksum &&
749 state->hook == NF_INET_PRE_ROUTING &&
750 nf_checksum(skb, state->hook, dataoff, IPPROTO_TCP, state->pf)) {
751 tcp_error_log(skb, state, "bad checksum");
752 return true;
753 }
754
755 /* Check TCP flags. */
756 tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
757 if (!tcp_valid_flags[tcpflags]) {
758 tcp_error_log(skb, state, "invalid tcp flag combination");
759 return true;
760 }
761
762 return false;
763 }
764
765 static noinline bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
766 unsigned int dataoff,
767 const struct tcphdr *th)
768 {
769 enum tcp_conntrack new_state;
770 struct net *net = nf_ct_net(ct);
771 const struct nf_tcp_net *tn = nf_tcp_pernet(net);
772 const struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[0];
773 const struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[1];
774
775 /* Don't need lock here: this conntrack not in circulation yet */
776 new_state = tcp_conntracks[0][get_conntrack_index(th)][TCP_CONNTRACK_NONE];
777
778 /* Invalid: delete conntrack */
779 if (new_state >= TCP_CONNTRACK_MAX) {
780 pr_debug("nf_ct_tcp: invalid new deleting.\n");
781 return false;
782 }
783
784 if (new_state == TCP_CONNTRACK_SYN_SENT) {
785 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
786 /* SYN packet */
787 ct->proto.tcp.seen[0].td_end =
788 segment_seq_plus_len(ntohl(th->seq), skb->len,
789 dataoff, th);
790 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
791 if (ct->proto.tcp.seen[0].td_maxwin == 0)
792 ct->proto.tcp.seen[0].td_maxwin = 1;
793 ct->proto.tcp.seen[0].td_maxend =
794 ct->proto.tcp.seen[0].td_end;
795
796 tcp_options(skb, dataoff, th, &ct->proto.tcp.seen[0]);
797 } else if (tn->tcp_loose == 0) {
798 /* Don't try to pick up connections. */
799 return false;
800 } else {
801 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
802 /*
803 * We are in the middle of a connection,
804 * its history is lost for us.
805 * Let's try to use the data from the packet.
806 */
807 ct->proto.tcp.seen[0].td_end =
808 segment_seq_plus_len(ntohl(th->seq), skb->len,
809 dataoff, th);
810 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
811 if (ct->proto.tcp.seen[0].td_maxwin == 0)
812 ct->proto.tcp.seen[0].td_maxwin = 1;
813 ct->proto.tcp.seen[0].td_maxend =
814 ct->proto.tcp.seen[0].td_end +
815 ct->proto.tcp.seen[0].td_maxwin;
816
817 /* We assume SACK and liberal window checking to handle
818 * window scaling */
819 ct->proto.tcp.seen[0].flags =
820 ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
821 IP_CT_TCP_FLAG_BE_LIBERAL;
822 }
823
824 /* tcp_packet will set them */
825 ct->proto.tcp.last_index = TCP_NONE_SET;
826
827 pr_debug("%s: sender end=%u maxend=%u maxwin=%u scale=%i "
828 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
829 __func__,
830 sender->td_end, sender->td_maxend, sender->td_maxwin,
831 sender->td_scale,
832 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
833 receiver->td_scale);
834 return true;
835 }
836
837 /* Returns verdict for packet, or -1 for invalid. */
838 int nf_conntrack_tcp_packet(struct nf_conn *ct,
839 struct sk_buff *skb,
840 unsigned int dataoff,
841 enum ip_conntrack_info ctinfo,
842 const struct nf_hook_state *state)
843 {
844 struct net *net = nf_ct_net(ct);
845 struct nf_tcp_net *tn = nf_tcp_pernet(net);
846 struct nf_conntrack_tuple *tuple;
847 enum tcp_conntrack new_state, old_state;
848 unsigned int index, *timeouts;
849 enum ip_conntrack_dir dir;
850 const struct tcphdr *th;
851 struct tcphdr _tcph;
852 unsigned long timeout;
853
854 th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
855 if (th == NULL)
856 return -NF_ACCEPT;
857
858 if (tcp_error(th, skb, dataoff, state))
859 return -NF_ACCEPT;
860
861 if (!nf_ct_is_confirmed(ct) && !tcp_new(ct, skb, dataoff, th))
862 return -NF_ACCEPT;
863
864 spin_lock_bh(&ct->lock);
865 old_state = ct->proto.tcp.state;
866 dir = CTINFO2DIR(ctinfo);
867 index = get_conntrack_index(th);
868 new_state = tcp_conntracks[dir][index][old_state];
869 tuple = &ct->tuplehash[dir].tuple;
870
871 switch (new_state) {
872 case TCP_CONNTRACK_SYN_SENT:
873 if (old_state < TCP_CONNTRACK_TIME_WAIT)
874 break;
875 /* RFC 1122: "When a connection is closed actively,
876 * it MUST linger in TIME-WAIT state for a time 2xMSL
877 * (Maximum Segment Lifetime). However, it MAY accept
878 * a new SYN from the remote TCP to reopen the connection
879 * directly from TIME-WAIT state, if..."
880 * We ignore the conditions because we are in the
881 * TIME-WAIT state anyway.
882 *
883 * Handle aborted connections: we and the server
884 * think there is an existing connection but the client
885 * aborts it and starts a new one.
886 */
887 if (((ct->proto.tcp.seen[dir].flags
888 | ct->proto.tcp.seen[!dir].flags)
889 & IP_CT_TCP_FLAG_CLOSE_INIT)
890 || (ct->proto.tcp.last_dir == dir
891 && ct->proto.tcp.last_index == TCP_RST_SET)) {
892 /* Attempt to reopen a closed/aborted connection.
893 * Delete this connection and look up again. */
894 spin_unlock_bh(&ct->lock);
895
896 /* Only repeat if we can actually remove the timer.
897 * Destruction may already be in progress in process
898 * context and we must give it a chance to terminate.
899 */
900 if (nf_ct_kill(ct))
901 return -NF_REPEAT;
902 return NF_DROP;
903 }
904 fallthrough;
905 case TCP_CONNTRACK_IGNORE:
906 /* Ignored packets:
907 *
908 * Our connection entry may be out of sync, so ignore
909 * packets which may signal the real connection between
910 * the client and the server.
911 *
912 * a) SYN in ORIGINAL
913 * b) SYN/ACK in REPLY
914 * c) ACK in reply direction after initial SYN in original.
915 *
916 * If the ignored packet is invalid, the receiver will send
917 * a RST we'll catch below.
918 */
919 if (index == TCP_SYNACK_SET
920 && ct->proto.tcp.last_index == TCP_SYN_SET
921 && ct->proto.tcp.last_dir != dir
922 && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
923 /* b) This SYN/ACK acknowledges a SYN that we earlier
924 * ignored as invalid. This means that the client and
925 * the server are both in sync, while the firewall is
926 * not. We get in sync from the previously annotated
927 * values.
928 */
929 old_state = TCP_CONNTRACK_SYN_SENT;
930 new_state = TCP_CONNTRACK_SYN_RECV;
931 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
932 ct->proto.tcp.last_end;
933 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
934 ct->proto.tcp.last_end;
935 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
936 ct->proto.tcp.last_win == 0 ?
937 1 : ct->proto.tcp.last_win;
938 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
939 ct->proto.tcp.last_wscale;
940 ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
941 ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
942 ct->proto.tcp.last_flags;
943 memset(&ct->proto.tcp.seen[dir], 0,
944 sizeof(struct ip_ct_tcp_state));
945 break;
946 }
947 ct->proto.tcp.last_index = index;
948 ct->proto.tcp.last_dir = dir;
949 ct->proto.tcp.last_seq = ntohl(th->seq);
950 ct->proto.tcp.last_end =
951 segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
952 ct->proto.tcp.last_win = ntohs(th->window);
953
954 /* a) This is a SYN in ORIGINAL. The client and the server
955 * may be in sync but we are not. In that case, we annotate
956 * the TCP options and let the packet go through. If it is a
957 * valid SYN packet, the server will reply with a SYN/ACK, and
958 * then we'll get in sync. Otherwise, the server potentially
959 * responds with a challenge ACK if implementing RFC5961.
960 */
961 if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
962 struct ip_ct_tcp_state seen = {};
963
964 ct->proto.tcp.last_flags =
965 ct->proto.tcp.last_wscale = 0;
966 tcp_options(skb, dataoff, th, &seen);
967 if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
968 ct->proto.tcp.last_flags |=
969 IP_CT_TCP_FLAG_WINDOW_SCALE;
970 ct->proto.tcp.last_wscale = seen.td_scale;
971 }
972 if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
973 ct->proto.tcp.last_flags |=
974 IP_CT_TCP_FLAG_SACK_PERM;
975 }
976 /* Mark the potential for RFC5961 challenge ACK,
977 * this pose a special problem for LAST_ACK state
978 * as ACK is intrepretated as ACKing last FIN.
979 */
980 if (old_state == TCP_CONNTRACK_LAST_ACK)
981 ct->proto.tcp.last_flags |=
982 IP_CT_EXP_CHALLENGE_ACK;
983 }
984 spin_unlock_bh(&ct->lock);
985 nf_ct_l4proto_log_invalid(skb, ct,
986 "packet (index %d) in dir %d ignored, state %s",
987 index, dir,
988 tcp_conntrack_names[old_state]);
989 return NF_ACCEPT;
990 case TCP_CONNTRACK_MAX:
991 /* Special case for SYN proxy: when the SYN to the server or
992 * the SYN/ACK from the server is lost, the client may transmit
993 * a keep-alive packet while in SYN_SENT state. This needs to
994 * be associated with the original conntrack entry in order to
995 * generate a new SYN with the correct sequence number.
996 */
997 if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
998 index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
999 ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
1000 ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
1001 pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
1002 spin_unlock_bh(&ct->lock);
1003 return NF_ACCEPT;
1004 }
1005
1006 /* Invalid packet */
1007 pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
1008 dir, get_conntrack_index(th), old_state);
1009 spin_unlock_bh(&ct->lock);
1010 nf_ct_l4proto_log_invalid(skb, ct, "invalid state");
1011 return -NF_ACCEPT;
1012 case TCP_CONNTRACK_TIME_WAIT:
1013 /* RFC5961 compliance cause stack to send "challenge-ACK"
1014 * e.g. in response to spurious SYNs. Conntrack MUST
1015 * not believe this ACK is acking last FIN.
1016 */
1017 if (old_state == TCP_CONNTRACK_LAST_ACK &&
1018 index == TCP_ACK_SET &&
1019 ct->proto.tcp.last_dir != dir &&
1020 ct->proto.tcp.last_index == TCP_SYN_SET &&
1021 (ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
1022 /* Detected RFC5961 challenge ACK */
1023 ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1024 spin_unlock_bh(&ct->lock);
1025 nf_ct_l4proto_log_invalid(skb, ct, "challenge-ack ignored");
1026 return NF_ACCEPT; /* Don't change state */
1027 }
1028 break;
1029 case TCP_CONNTRACK_SYN_SENT2:
1030 /* tcp_conntracks table is not smart enough to handle
1031 * simultaneous open.
1032 */
1033 ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN;
1034 break;
1035 case TCP_CONNTRACK_SYN_RECV:
1036 if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET &&
1037 ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN)
1038 new_state = TCP_CONNTRACK_ESTABLISHED;
1039 break;
1040 case TCP_CONNTRACK_CLOSE:
1041 if (index != TCP_RST_SET)
1042 break;
1043
1044 if (ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) {
1045 u32 seq = ntohl(th->seq);
1046
1047 if (before(seq, ct->proto.tcp.seen[!dir].td_maxack)) {
1048 /* Invalid RST */
1049 spin_unlock_bh(&ct->lock);
1050 nf_ct_l4proto_log_invalid(skb, ct, "invalid rst");
1051 return -NF_ACCEPT;
1052 }
1053
1054 if (!nf_conntrack_tcp_established(ct) ||
1055 seq == ct->proto.tcp.seen[!dir].td_maxack)
1056 break;
1057
1058 /* Check if rst is part of train, such as
1059 * foo:80 > bar:4379: P, 235946583:235946602(19) ack 42
1060 * foo:80 > bar:4379: R, 235946602:235946602(0) ack 42
1061 */
1062 if (ct->proto.tcp.last_index == TCP_ACK_SET &&
1063 ct->proto.tcp.last_dir == dir &&
1064 seq == ct->proto.tcp.last_end)
1065 break;
1066
1067 /* ... RST sequence number doesn't match exactly, keep
1068 * established state to allow a possible challenge ACK.
1069 */
1070 new_state = old_state;
1071 }
1072 if (((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
1073 && ct->proto.tcp.last_index == TCP_SYN_SET)
1074 || (!test_bit(IPS_ASSURED_BIT, &ct->status)
1075 && ct->proto.tcp.last_index == TCP_ACK_SET))
1076 && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1077 /* RST sent to invalid SYN or ACK we had let through
1078 * at a) and c) above:
1079 *
1080 * a) SYN was in window then
1081 * c) we hold a half-open connection.
1082 *
1083 * Delete our connection entry.
1084 * We skip window checking, because packet might ACK
1085 * segments we ignored. */
1086 goto in_window;
1087 }
1088 break;
1089 default:
1090 /* Keep compilers happy. */
1091 break;
1092 }
1093
1094 if (!tcp_in_window(ct, &ct->proto.tcp, dir, index,
1095 skb, dataoff, th)) {
1096 spin_unlock_bh(&ct->lock);
1097 return -NF_ACCEPT;
1098 }
1099 in_window:
1100 /* From now on we have got in-window packets */
1101 ct->proto.tcp.last_index = index;
1102 ct->proto.tcp.last_dir = dir;
1103
1104 pr_debug("tcp_conntracks: ");
1105 nf_ct_dump_tuple(tuple);
1106 pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
1107 (th->syn ? 1 : 0), (th->ack ? 1 : 0),
1108 (th->fin ? 1 : 0), (th->rst ? 1 : 0),
1109 old_state, new_state);
1110
1111 ct->proto.tcp.state = new_state;
1112 if (old_state != new_state
1113 && new_state == TCP_CONNTRACK_FIN_WAIT)
1114 ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
1115
1116 timeouts = nf_ct_timeout_lookup(ct);
1117 if (!timeouts)
1118 timeouts = tn->timeouts;
1119
1120 if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
1121 timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1122 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1123 else if (unlikely(index == TCP_RST_SET))
1124 timeout = timeouts[TCP_CONNTRACK_CLOSE];
1125 else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
1126 IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
1127 timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
1128 timeout = timeouts[TCP_CONNTRACK_UNACK];
1129 else if (ct->proto.tcp.last_win == 0 &&
1130 timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1131 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1132 else
1133 timeout = timeouts[new_state];
1134 spin_unlock_bh(&ct->lock);
1135
1136 if (new_state != old_state)
1137 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
1138
1139 if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
1140 /* If only reply is a RST, we can consider ourselves not to
1141 have an established connection: this is a fairly common
1142 problem case, so we can delete the conntrack
1143 immediately. --RR */
1144 if (th->rst) {
1145 nf_ct_kill_acct(ct, ctinfo, skb);
1146 return NF_ACCEPT;
1147 }
1148 /* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
1149 * pickup with loose=1. Avoid large ESTABLISHED timeout.
1150 */
1151 if (new_state == TCP_CONNTRACK_ESTABLISHED &&
1152 timeout > timeouts[TCP_CONNTRACK_UNACK])
1153 timeout = timeouts[TCP_CONNTRACK_UNACK];
1154 } else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
1155 && (old_state == TCP_CONNTRACK_SYN_RECV
1156 || old_state == TCP_CONNTRACK_ESTABLISHED)
1157 && new_state == TCP_CONNTRACK_ESTABLISHED) {
1158 /* Set ASSURED if we see valid ack in ESTABLISHED
1159 after SYN_RECV or a valid answer for a picked up
1160 connection. */
1161 set_bit(IPS_ASSURED_BIT, &ct->status);
1162 nf_conntrack_event_cache(IPCT_ASSURED, ct);
1163 }
1164 nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
1165
1166 return NF_ACCEPT;
1167 }
1168
1169 static bool tcp_can_early_drop(const struct nf_conn *ct)
1170 {
1171 switch (ct->proto.tcp.state) {
1172 case TCP_CONNTRACK_FIN_WAIT:
1173 case TCP_CONNTRACK_LAST_ACK:
1174 case TCP_CONNTRACK_TIME_WAIT:
1175 case TCP_CONNTRACK_CLOSE:
1176 case TCP_CONNTRACK_CLOSE_WAIT:
1177 return true;
1178 default:
1179 break;
1180 }
1181
1182 return false;
1183 }
1184
1185 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1186
1187 #include <linux/netfilter/nfnetlink.h>
1188 #include <linux/netfilter/nfnetlink_conntrack.h>
1189
1190 static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1191 struct nf_conn *ct, bool destroy)
1192 {
1193 struct nlattr *nest_parms;
1194 struct nf_ct_tcp_flags tmp = {};
1195
1196 spin_lock_bh(&ct->lock);
1197 nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP);
1198 if (!nest_parms)
1199 goto nla_put_failure;
1200
1201 if (nla_put_u8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state))
1202 goto nla_put_failure;
1203
1204 if (destroy)
1205 goto skip_state;
1206
1207 if (nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1208 ct->proto.tcp.seen[0].td_scale) ||
1209 nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
1210 ct->proto.tcp.seen[1].td_scale))
1211 goto nla_put_failure;
1212
1213 tmp.flags = ct->proto.tcp.seen[0].flags;
1214 if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1215 sizeof(struct nf_ct_tcp_flags), &tmp))
1216 goto nla_put_failure;
1217
1218 tmp.flags = ct->proto.tcp.seen[1].flags;
1219 if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1220 sizeof(struct nf_ct_tcp_flags), &tmp))
1221 goto nla_put_failure;
1222 skip_state:
1223 spin_unlock_bh(&ct->lock);
1224 nla_nest_end(skb, nest_parms);
1225
1226 return 0;
1227
1228 nla_put_failure:
1229 spin_unlock_bh(&ct->lock);
1230 return -1;
1231 }
1232
1233 static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1234 [CTA_PROTOINFO_TCP_STATE] = { .type = NLA_U8 },
1235 [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1236 [CTA_PROTOINFO_TCP_WSCALE_REPLY] = { .type = NLA_U8 },
1237 [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL] = { .len = sizeof(struct nf_ct_tcp_flags) },
1238 [CTA_PROTOINFO_TCP_FLAGS_REPLY] = { .len = sizeof(struct nf_ct_tcp_flags) },
1239 };
1240
1241 #define TCP_NLATTR_SIZE ( \
1242 NLA_ALIGN(NLA_HDRLEN + 1) + \
1243 NLA_ALIGN(NLA_HDRLEN + 1) + \
1244 NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)) + \
1245 NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)))
1246
1247 static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1248 {
1249 struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
1250 struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1251 int err;
1252
1253 /* updates could not contain anything about the private
1254 * protocol info, in that case skip the parsing */
1255 if (!pattr)
1256 return 0;
1257
1258 err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_TCP_MAX, pattr,
1259 tcp_nla_policy, NULL);
1260 if (err < 0)
1261 return err;
1262
1263 if (tb[CTA_PROTOINFO_TCP_STATE] &&
1264 nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
1265 return -EINVAL;
1266
1267 spin_lock_bh(&ct->lock);
1268 if (tb[CTA_PROTOINFO_TCP_STATE])
1269 ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
1270
1271 if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1272 struct nf_ct_tcp_flags *attr =
1273 nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1274 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1275 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1276 }
1277
1278 if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1279 struct nf_ct_tcp_flags *attr =
1280 nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1281 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1282 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1283 }
1284
1285 if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1286 tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1287 ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1288 ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1289 ct->proto.tcp.seen[0].td_scale =
1290 nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1291 ct->proto.tcp.seen[1].td_scale =
1292 nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1293 }
1294 spin_unlock_bh(&ct->lock);
1295
1296 return 0;
1297 }
1298
1299 static unsigned int tcp_nlattr_tuple_size(void)
1300 {
1301 static unsigned int size __read_mostly;
1302
1303 if (!size)
1304 size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
1305
1306 return size;
1307 }
1308 #endif
1309
1310 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1311
1312 #include <linux/netfilter/nfnetlink.h>
1313 #include <linux/netfilter/nfnetlink_cttimeout.h>
1314
1315 static int tcp_timeout_nlattr_to_obj(struct nlattr *tb[],
1316 struct net *net, void *data)
1317 {
1318 struct nf_tcp_net *tn = nf_tcp_pernet(net);
1319 unsigned int *timeouts = data;
1320 int i;
1321
1322 if (!timeouts)
1323 timeouts = tn->timeouts;
1324 /* set default TCP timeouts. */
1325 for (i=0; i<TCP_CONNTRACK_TIMEOUT_MAX; i++)
1326 timeouts[i] = tn->timeouts[i];
1327
1328 if (tb[CTA_TIMEOUT_TCP_SYN_SENT]) {
1329 timeouts[TCP_CONNTRACK_SYN_SENT] =
1330 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT]))*HZ;
1331 }
1332
1333 if (tb[CTA_TIMEOUT_TCP_SYN_RECV]) {
1334 timeouts[TCP_CONNTRACK_SYN_RECV] =
1335 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_RECV]))*HZ;
1336 }
1337 if (tb[CTA_TIMEOUT_TCP_ESTABLISHED]) {
1338 timeouts[TCP_CONNTRACK_ESTABLISHED] =
1339 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_ESTABLISHED]))*HZ;
1340 }
1341 if (tb[CTA_TIMEOUT_TCP_FIN_WAIT]) {
1342 timeouts[TCP_CONNTRACK_FIN_WAIT] =
1343 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_FIN_WAIT]))*HZ;
1344 }
1345 if (tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]) {
1346 timeouts[TCP_CONNTRACK_CLOSE_WAIT] =
1347 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]))*HZ;
1348 }
1349 if (tb[CTA_TIMEOUT_TCP_LAST_ACK]) {
1350 timeouts[TCP_CONNTRACK_LAST_ACK] =
1351 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_LAST_ACK]))*HZ;
1352 }
1353 if (tb[CTA_TIMEOUT_TCP_TIME_WAIT]) {
1354 timeouts[TCP_CONNTRACK_TIME_WAIT] =
1355 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_TIME_WAIT]))*HZ;
1356 }
1357 if (tb[CTA_TIMEOUT_TCP_CLOSE]) {
1358 timeouts[TCP_CONNTRACK_CLOSE] =
1359 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE]))*HZ;
1360 }
1361 if (tb[CTA_TIMEOUT_TCP_SYN_SENT2]) {
1362 timeouts[TCP_CONNTRACK_SYN_SENT2] =
1363 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT2]))*HZ;
1364 }
1365 if (tb[CTA_TIMEOUT_TCP_RETRANS]) {
1366 timeouts[TCP_CONNTRACK_RETRANS] =
1367 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_RETRANS]))*HZ;
1368 }
1369 if (tb[CTA_TIMEOUT_TCP_UNACK]) {
1370 timeouts[TCP_CONNTRACK_UNACK] =
1371 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_UNACK]))*HZ;
1372 }
1373
1374 timeouts[CTA_TIMEOUT_TCP_UNSPEC] = timeouts[CTA_TIMEOUT_TCP_SYN_SENT];
1375 return 0;
1376 }
1377
1378 static int
1379 tcp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
1380 {
1381 const unsigned int *timeouts = data;
1382
1383 if (nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT,
1384 htonl(timeouts[TCP_CONNTRACK_SYN_SENT] / HZ)) ||
1385 nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_RECV,
1386 htonl(timeouts[TCP_CONNTRACK_SYN_RECV] / HZ)) ||
1387 nla_put_be32(skb, CTA_TIMEOUT_TCP_ESTABLISHED,
1388 htonl(timeouts[TCP_CONNTRACK_ESTABLISHED] / HZ)) ||
1389 nla_put_be32(skb, CTA_TIMEOUT_TCP_FIN_WAIT,
1390 htonl(timeouts[TCP_CONNTRACK_FIN_WAIT] / HZ)) ||
1391 nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE_WAIT,
1392 htonl(timeouts[TCP_CONNTRACK_CLOSE_WAIT] / HZ)) ||
1393 nla_put_be32(skb, CTA_TIMEOUT_TCP_LAST_ACK,
1394 htonl(timeouts[TCP_CONNTRACK_LAST_ACK] / HZ)) ||
1395 nla_put_be32(skb, CTA_TIMEOUT_TCP_TIME_WAIT,
1396 htonl(timeouts[TCP_CONNTRACK_TIME_WAIT] / HZ)) ||
1397 nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE,
1398 htonl(timeouts[TCP_CONNTRACK_CLOSE] / HZ)) ||
1399 nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT2,
1400 htonl(timeouts[TCP_CONNTRACK_SYN_SENT2] / HZ)) ||
1401 nla_put_be32(skb, CTA_TIMEOUT_TCP_RETRANS,
1402 htonl(timeouts[TCP_CONNTRACK_RETRANS] / HZ)) ||
1403 nla_put_be32(skb, CTA_TIMEOUT_TCP_UNACK,
1404 htonl(timeouts[TCP_CONNTRACK_UNACK] / HZ)))
1405 goto nla_put_failure;
1406 return 0;
1407
1408 nla_put_failure:
1409 return -ENOSPC;
1410 }
1411
1412 static const struct nla_policy tcp_timeout_nla_policy[CTA_TIMEOUT_TCP_MAX+1] = {
1413 [CTA_TIMEOUT_TCP_SYN_SENT] = { .type = NLA_U32 },
1414 [CTA_TIMEOUT_TCP_SYN_RECV] = { .type = NLA_U32 },
1415 [CTA_TIMEOUT_TCP_ESTABLISHED] = { .type = NLA_U32 },
1416 [CTA_TIMEOUT_TCP_FIN_WAIT] = { .type = NLA_U32 },
1417 [CTA_TIMEOUT_TCP_CLOSE_WAIT] = { .type = NLA_U32 },
1418 [CTA_TIMEOUT_TCP_LAST_ACK] = { .type = NLA_U32 },
1419 [CTA_TIMEOUT_TCP_TIME_WAIT] = { .type = NLA_U32 },
1420 [CTA_TIMEOUT_TCP_CLOSE] = { .type = NLA_U32 },
1421 [CTA_TIMEOUT_TCP_SYN_SENT2] = { .type = NLA_U32 },
1422 [CTA_TIMEOUT_TCP_RETRANS] = { .type = NLA_U32 },
1423 [CTA_TIMEOUT_TCP_UNACK] = { .type = NLA_U32 },
1424 };
1425 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1426
1427 void nf_conntrack_tcp_init_net(struct net *net)
1428 {
1429 struct nf_tcp_net *tn = nf_tcp_pernet(net);
1430 int i;
1431
1432 for (i = 0; i < TCP_CONNTRACK_TIMEOUT_MAX; i++)
1433 tn->timeouts[i] = tcp_timeouts[i];
1434
1435 /* timeouts[0] is unused, make it same as SYN_SENT so
1436 * ->timeouts[0] contains 'new' timeout, like udp or icmp.
1437 */
1438 tn->timeouts[0] = tcp_timeouts[TCP_CONNTRACK_SYN_SENT];
1439 tn->tcp_loose = nf_ct_tcp_loose;
1440 tn->tcp_be_liberal = nf_ct_tcp_be_liberal;
1441 tn->tcp_max_retrans = nf_ct_tcp_max_retrans;
1442 }
1443
1444 const struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp =
1445 {
1446 .l4proto = IPPROTO_TCP,
1447 #ifdef CONFIG_NF_CONNTRACK_PROCFS
1448 .print_conntrack = tcp_print_conntrack,
1449 #endif
1450 .can_early_drop = tcp_can_early_drop,
1451 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1452 .to_nlattr = tcp_to_nlattr,
1453 .from_nlattr = nlattr_to_tcp,
1454 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
1455 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
1456 .nlattr_tuple_size = tcp_nlattr_tuple_size,
1457 .nlattr_size = TCP_NLATTR_SIZE,
1458 .nla_policy = nf_ct_port_nla_policy,
1459 #endif
1460 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1461 .ctnl_timeout = {
1462 .nlattr_to_obj = tcp_timeout_nlattr_to_obj,
1463 .obj_to_nlattr = tcp_timeout_obj_to_nlattr,
1464 .nlattr_max = CTA_TIMEOUT_TCP_MAX,
1465 .obj_size = sizeof(unsigned int) *
1466 TCP_CONNTRACK_TIMEOUT_MAX,
1467 .nla_policy = tcp_timeout_nla_policy,
1468 },
1469 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1470 };
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