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Merge tag 'powerpc-5.11-6' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc...
[mirror_ubuntu-hirsute-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, "invalid packet ignored in "
986 "state %s ", tcp_conntrack_names[old_state]);
987 return NF_ACCEPT;
988 case TCP_CONNTRACK_MAX:
989 /* Special case for SYN proxy: when the SYN to the server or
990 * the SYN/ACK from the server is lost, the client may transmit
991 * a keep-alive packet while in SYN_SENT state. This needs to
992 * be associated with the original conntrack entry in order to
993 * generate a new SYN with the correct sequence number.
994 */
995 if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
996 index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
997 ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
998 ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
999 pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
1000 spin_unlock_bh(&ct->lock);
1001 return NF_ACCEPT;
1002 }
1003
1004 /* Invalid packet */
1005 pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
1006 dir, get_conntrack_index(th), old_state);
1007 spin_unlock_bh(&ct->lock);
1008 nf_ct_l4proto_log_invalid(skb, ct, "invalid state");
1009 return -NF_ACCEPT;
1010 case TCP_CONNTRACK_TIME_WAIT:
1011 /* RFC5961 compliance cause stack to send "challenge-ACK"
1012 * e.g. in response to spurious SYNs. Conntrack MUST
1013 * not believe this ACK is acking last FIN.
1014 */
1015 if (old_state == TCP_CONNTRACK_LAST_ACK &&
1016 index == TCP_ACK_SET &&
1017 ct->proto.tcp.last_dir != dir &&
1018 ct->proto.tcp.last_index == TCP_SYN_SET &&
1019 (ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
1020 /* Detected RFC5961 challenge ACK */
1021 ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1022 spin_unlock_bh(&ct->lock);
1023 nf_ct_l4proto_log_invalid(skb, ct, "challenge-ack ignored");
1024 return NF_ACCEPT; /* Don't change state */
1025 }
1026 break;
1027 case TCP_CONNTRACK_SYN_SENT2:
1028 /* tcp_conntracks table is not smart enough to handle
1029 * simultaneous open.
1030 */
1031 ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN;
1032 break;
1033 case TCP_CONNTRACK_SYN_RECV:
1034 if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET &&
1035 ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN)
1036 new_state = TCP_CONNTRACK_ESTABLISHED;
1037 break;
1038 case TCP_CONNTRACK_CLOSE:
1039 if (index != TCP_RST_SET)
1040 break;
1041
1042 if (ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) {
1043 u32 seq = ntohl(th->seq);
1044
1045 if (before(seq, ct->proto.tcp.seen[!dir].td_maxack)) {
1046 /* Invalid RST */
1047 spin_unlock_bh(&ct->lock);
1048 nf_ct_l4proto_log_invalid(skb, ct, "invalid rst");
1049 return -NF_ACCEPT;
1050 }
1051
1052 if (!nf_conntrack_tcp_established(ct) ||
1053 seq == ct->proto.tcp.seen[!dir].td_maxack)
1054 break;
1055
1056 /* Check if rst is part of train, such as
1057 * foo:80 > bar:4379: P, 235946583:235946602(19) ack 42
1058 * foo:80 > bar:4379: R, 235946602:235946602(0) ack 42
1059 */
1060 if (ct->proto.tcp.last_index == TCP_ACK_SET &&
1061 ct->proto.tcp.last_dir == dir &&
1062 seq == ct->proto.tcp.last_end)
1063 break;
1064
1065 /* ... RST sequence number doesn't match exactly, keep
1066 * established state to allow a possible challenge ACK.
1067 */
1068 new_state = old_state;
1069 }
1070 if (((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
1071 && ct->proto.tcp.last_index == TCP_SYN_SET)
1072 || (!test_bit(IPS_ASSURED_BIT, &ct->status)
1073 && ct->proto.tcp.last_index == TCP_ACK_SET))
1074 && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1075 /* RST sent to invalid SYN or ACK we had let through
1076 * at a) and c) above:
1077 *
1078 * a) SYN was in window then
1079 * c) we hold a half-open connection.
1080 *
1081 * Delete our connection entry.
1082 * We skip window checking, because packet might ACK
1083 * segments we ignored. */
1084 goto in_window;
1085 }
1086 break;
1087 default:
1088 /* Keep compilers happy. */
1089 break;
1090 }
1091
1092 if (!tcp_in_window(ct, &ct->proto.tcp, dir, index,
1093 skb, dataoff, th)) {
1094 spin_unlock_bh(&ct->lock);
1095 return -NF_ACCEPT;
1096 }
1097 in_window:
1098 /* From now on we have got in-window packets */
1099 ct->proto.tcp.last_index = index;
1100 ct->proto.tcp.last_dir = dir;
1101
1102 pr_debug("tcp_conntracks: ");
1103 nf_ct_dump_tuple(tuple);
1104 pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
1105 (th->syn ? 1 : 0), (th->ack ? 1 : 0),
1106 (th->fin ? 1 : 0), (th->rst ? 1 : 0),
1107 old_state, new_state);
1108
1109 ct->proto.tcp.state = new_state;
1110 if (old_state != new_state
1111 && new_state == TCP_CONNTRACK_FIN_WAIT)
1112 ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
1113
1114 timeouts = nf_ct_timeout_lookup(ct);
1115 if (!timeouts)
1116 timeouts = tn->timeouts;
1117
1118 if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
1119 timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1120 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1121 else if (unlikely(index == TCP_RST_SET))
1122 timeout = timeouts[TCP_CONNTRACK_CLOSE];
1123 else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
1124 IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
1125 timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
1126 timeout = timeouts[TCP_CONNTRACK_UNACK];
1127 else if (ct->proto.tcp.last_win == 0 &&
1128 timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1129 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1130 else
1131 timeout = timeouts[new_state];
1132 spin_unlock_bh(&ct->lock);
1133
1134 if (new_state != old_state)
1135 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
1136
1137 if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
1138 /* If only reply is a RST, we can consider ourselves not to
1139 have an established connection: this is a fairly common
1140 problem case, so we can delete the conntrack
1141 immediately. --RR */
1142 if (th->rst) {
1143 nf_ct_kill_acct(ct, ctinfo, skb);
1144 return NF_ACCEPT;
1145 }
1146 /* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
1147 * pickup with loose=1. Avoid large ESTABLISHED timeout.
1148 */
1149 if (new_state == TCP_CONNTRACK_ESTABLISHED &&
1150 timeout > timeouts[TCP_CONNTRACK_UNACK])
1151 timeout = timeouts[TCP_CONNTRACK_UNACK];
1152 } else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
1153 && (old_state == TCP_CONNTRACK_SYN_RECV
1154 || old_state == TCP_CONNTRACK_ESTABLISHED)
1155 && new_state == TCP_CONNTRACK_ESTABLISHED) {
1156 /* Set ASSURED if we see valid ack in ESTABLISHED
1157 after SYN_RECV or a valid answer for a picked up
1158 connection. */
1159 set_bit(IPS_ASSURED_BIT, &ct->status);
1160 nf_conntrack_event_cache(IPCT_ASSURED, ct);
1161 }
1162 nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
1163
1164 return NF_ACCEPT;
1165 }
1166
1167 static bool tcp_can_early_drop(const struct nf_conn *ct)
1168 {
1169 switch (ct->proto.tcp.state) {
1170 case TCP_CONNTRACK_FIN_WAIT:
1171 case TCP_CONNTRACK_LAST_ACK:
1172 case TCP_CONNTRACK_TIME_WAIT:
1173 case TCP_CONNTRACK_CLOSE:
1174 case TCP_CONNTRACK_CLOSE_WAIT:
1175 return true;
1176 default:
1177 break;
1178 }
1179
1180 return false;
1181 }
1182
1183 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1184
1185 #include <linux/netfilter/nfnetlink.h>
1186 #include <linux/netfilter/nfnetlink_conntrack.h>
1187
1188 static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1189 struct nf_conn *ct, bool destroy)
1190 {
1191 struct nlattr *nest_parms;
1192 struct nf_ct_tcp_flags tmp = {};
1193
1194 spin_lock_bh(&ct->lock);
1195 nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP);
1196 if (!nest_parms)
1197 goto nla_put_failure;
1198
1199 if (nla_put_u8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state))
1200 goto nla_put_failure;
1201
1202 if (destroy)
1203 goto skip_state;
1204
1205 if (nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1206 ct->proto.tcp.seen[0].td_scale) ||
1207 nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
1208 ct->proto.tcp.seen[1].td_scale))
1209 goto nla_put_failure;
1210
1211 tmp.flags = ct->proto.tcp.seen[0].flags;
1212 if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1213 sizeof(struct nf_ct_tcp_flags), &tmp))
1214 goto nla_put_failure;
1215
1216 tmp.flags = ct->proto.tcp.seen[1].flags;
1217 if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1218 sizeof(struct nf_ct_tcp_flags), &tmp))
1219 goto nla_put_failure;
1220 skip_state:
1221 spin_unlock_bh(&ct->lock);
1222 nla_nest_end(skb, nest_parms);
1223
1224 return 0;
1225
1226 nla_put_failure:
1227 spin_unlock_bh(&ct->lock);
1228 return -1;
1229 }
1230
1231 static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1232 [CTA_PROTOINFO_TCP_STATE] = { .type = NLA_U8 },
1233 [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1234 [CTA_PROTOINFO_TCP_WSCALE_REPLY] = { .type = NLA_U8 },
1235 [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL] = { .len = sizeof(struct nf_ct_tcp_flags) },
1236 [CTA_PROTOINFO_TCP_FLAGS_REPLY] = { .len = sizeof(struct nf_ct_tcp_flags) },
1237 };
1238
1239 #define TCP_NLATTR_SIZE ( \
1240 NLA_ALIGN(NLA_HDRLEN + 1) + \
1241 NLA_ALIGN(NLA_HDRLEN + 1) + \
1242 NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)) + \
1243 NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)))
1244
1245 static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1246 {
1247 struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
1248 struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1249 int err;
1250
1251 /* updates could not contain anything about the private
1252 * protocol info, in that case skip the parsing */
1253 if (!pattr)
1254 return 0;
1255
1256 err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_TCP_MAX, pattr,
1257 tcp_nla_policy, NULL);
1258 if (err < 0)
1259 return err;
1260
1261 if (tb[CTA_PROTOINFO_TCP_STATE] &&
1262 nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
1263 return -EINVAL;
1264
1265 spin_lock_bh(&ct->lock);
1266 if (tb[CTA_PROTOINFO_TCP_STATE])
1267 ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
1268
1269 if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1270 struct nf_ct_tcp_flags *attr =
1271 nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1272 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1273 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1274 }
1275
1276 if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1277 struct nf_ct_tcp_flags *attr =
1278 nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1279 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1280 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1281 }
1282
1283 if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1284 tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1285 ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1286 ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1287 ct->proto.tcp.seen[0].td_scale =
1288 nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1289 ct->proto.tcp.seen[1].td_scale =
1290 nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1291 }
1292 spin_unlock_bh(&ct->lock);
1293
1294 return 0;
1295 }
1296
1297 static unsigned int tcp_nlattr_tuple_size(void)
1298 {
1299 static unsigned int size __read_mostly;
1300
1301 if (!size)
1302 size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
1303
1304 return size;
1305 }
1306 #endif
1307
1308 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1309
1310 #include <linux/netfilter/nfnetlink.h>
1311 #include <linux/netfilter/nfnetlink_cttimeout.h>
1312
1313 static int tcp_timeout_nlattr_to_obj(struct nlattr *tb[],
1314 struct net *net, void *data)
1315 {
1316 struct nf_tcp_net *tn = nf_tcp_pernet(net);
1317 unsigned int *timeouts = data;
1318 int i;
1319
1320 if (!timeouts)
1321 timeouts = tn->timeouts;
1322 /* set default TCP timeouts. */
1323 for (i=0; i<TCP_CONNTRACK_TIMEOUT_MAX; i++)
1324 timeouts[i] = tn->timeouts[i];
1325
1326 if (tb[CTA_TIMEOUT_TCP_SYN_SENT]) {
1327 timeouts[TCP_CONNTRACK_SYN_SENT] =
1328 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT]))*HZ;
1329 }
1330
1331 if (tb[CTA_TIMEOUT_TCP_SYN_RECV]) {
1332 timeouts[TCP_CONNTRACK_SYN_RECV] =
1333 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_RECV]))*HZ;
1334 }
1335 if (tb[CTA_TIMEOUT_TCP_ESTABLISHED]) {
1336 timeouts[TCP_CONNTRACK_ESTABLISHED] =
1337 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_ESTABLISHED]))*HZ;
1338 }
1339 if (tb[CTA_TIMEOUT_TCP_FIN_WAIT]) {
1340 timeouts[TCP_CONNTRACK_FIN_WAIT] =
1341 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_FIN_WAIT]))*HZ;
1342 }
1343 if (tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]) {
1344 timeouts[TCP_CONNTRACK_CLOSE_WAIT] =
1345 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]))*HZ;
1346 }
1347 if (tb[CTA_TIMEOUT_TCP_LAST_ACK]) {
1348 timeouts[TCP_CONNTRACK_LAST_ACK] =
1349 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_LAST_ACK]))*HZ;
1350 }
1351 if (tb[CTA_TIMEOUT_TCP_TIME_WAIT]) {
1352 timeouts[TCP_CONNTRACK_TIME_WAIT] =
1353 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_TIME_WAIT]))*HZ;
1354 }
1355 if (tb[CTA_TIMEOUT_TCP_CLOSE]) {
1356 timeouts[TCP_CONNTRACK_CLOSE] =
1357 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE]))*HZ;
1358 }
1359 if (tb[CTA_TIMEOUT_TCP_SYN_SENT2]) {
1360 timeouts[TCP_CONNTRACK_SYN_SENT2] =
1361 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT2]))*HZ;
1362 }
1363 if (tb[CTA_TIMEOUT_TCP_RETRANS]) {
1364 timeouts[TCP_CONNTRACK_RETRANS] =
1365 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_RETRANS]))*HZ;
1366 }
1367 if (tb[CTA_TIMEOUT_TCP_UNACK]) {
1368 timeouts[TCP_CONNTRACK_UNACK] =
1369 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_UNACK]))*HZ;
1370 }
1371
1372 timeouts[CTA_TIMEOUT_TCP_UNSPEC] = timeouts[CTA_TIMEOUT_TCP_SYN_SENT];
1373 return 0;
1374 }
1375
1376 static int
1377 tcp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
1378 {
1379 const unsigned int *timeouts = data;
1380
1381 if (nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT,
1382 htonl(timeouts[TCP_CONNTRACK_SYN_SENT] / HZ)) ||
1383 nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_RECV,
1384 htonl(timeouts[TCP_CONNTRACK_SYN_RECV] / HZ)) ||
1385 nla_put_be32(skb, CTA_TIMEOUT_TCP_ESTABLISHED,
1386 htonl(timeouts[TCP_CONNTRACK_ESTABLISHED] / HZ)) ||
1387 nla_put_be32(skb, CTA_TIMEOUT_TCP_FIN_WAIT,
1388 htonl(timeouts[TCP_CONNTRACK_FIN_WAIT] / HZ)) ||
1389 nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE_WAIT,
1390 htonl(timeouts[TCP_CONNTRACK_CLOSE_WAIT] / HZ)) ||
1391 nla_put_be32(skb, CTA_TIMEOUT_TCP_LAST_ACK,
1392 htonl(timeouts[TCP_CONNTRACK_LAST_ACK] / HZ)) ||
1393 nla_put_be32(skb, CTA_TIMEOUT_TCP_TIME_WAIT,
1394 htonl(timeouts[TCP_CONNTRACK_TIME_WAIT] / HZ)) ||
1395 nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE,
1396 htonl(timeouts[TCP_CONNTRACK_CLOSE] / HZ)) ||
1397 nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT2,
1398 htonl(timeouts[TCP_CONNTRACK_SYN_SENT2] / HZ)) ||
1399 nla_put_be32(skb, CTA_TIMEOUT_TCP_RETRANS,
1400 htonl(timeouts[TCP_CONNTRACK_RETRANS] / HZ)) ||
1401 nla_put_be32(skb, CTA_TIMEOUT_TCP_UNACK,
1402 htonl(timeouts[TCP_CONNTRACK_UNACK] / HZ)))
1403 goto nla_put_failure;
1404 return 0;
1405
1406 nla_put_failure:
1407 return -ENOSPC;
1408 }
1409
1410 static const struct nla_policy tcp_timeout_nla_policy[CTA_TIMEOUT_TCP_MAX+1] = {
1411 [CTA_TIMEOUT_TCP_SYN_SENT] = { .type = NLA_U32 },
1412 [CTA_TIMEOUT_TCP_SYN_RECV] = { .type = NLA_U32 },
1413 [CTA_TIMEOUT_TCP_ESTABLISHED] = { .type = NLA_U32 },
1414 [CTA_TIMEOUT_TCP_FIN_WAIT] = { .type = NLA_U32 },
1415 [CTA_TIMEOUT_TCP_CLOSE_WAIT] = { .type = NLA_U32 },
1416 [CTA_TIMEOUT_TCP_LAST_ACK] = { .type = NLA_U32 },
1417 [CTA_TIMEOUT_TCP_TIME_WAIT] = { .type = NLA_U32 },
1418 [CTA_TIMEOUT_TCP_CLOSE] = { .type = NLA_U32 },
1419 [CTA_TIMEOUT_TCP_SYN_SENT2] = { .type = NLA_U32 },
1420 [CTA_TIMEOUT_TCP_RETRANS] = { .type = NLA_U32 },
1421 [CTA_TIMEOUT_TCP_UNACK] = { .type = NLA_U32 },
1422 };
1423 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1424
1425 void nf_conntrack_tcp_init_net(struct net *net)
1426 {
1427 struct nf_tcp_net *tn = nf_tcp_pernet(net);
1428 int i;
1429
1430 for (i = 0; i < TCP_CONNTRACK_TIMEOUT_MAX; i++)
1431 tn->timeouts[i] = tcp_timeouts[i];
1432
1433 /* timeouts[0] is unused, make it same as SYN_SENT so
1434 * ->timeouts[0] contains 'new' timeout, like udp or icmp.
1435 */
1436 tn->timeouts[0] = tcp_timeouts[TCP_CONNTRACK_SYN_SENT];
1437 tn->tcp_loose = nf_ct_tcp_loose;
1438 tn->tcp_be_liberal = nf_ct_tcp_be_liberal;
1439 tn->tcp_max_retrans = nf_ct_tcp_max_retrans;
1440 }
1441
1442 const struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp =
1443 {
1444 .l4proto = IPPROTO_TCP,
1445 #ifdef CONFIG_NF_CONNTRACK_PROCFS
1446 .print_conntrack = tcp_print_conntrack,
1447 #endif
1448 .can_early_drop = tcp_can_early_drop,
1449 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1450 .to_nlattr = tcp_to_nlattr,
1451 .from_nlattr = nlattr_to_tcp,
1452 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
1453 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
1454 .nlattr_tuple_size = tcp_nlattr_tuple_size,
1455 .nlattr_size = TCP_NLATTR_SIZE,
1456 .nla_policy = nf_ct_port_nla_policy,
1457 #endif
1458 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1459 .ctnl_timeout = {
1460 .nlattr_to_obj = tcp_timeout_nlattr_to_obj,
1461 .obj_to_nlattr = tcp_timeout_obj_to_nlattr,
1462 .nlattr_max = CTA_TIMEOUT_TCP_MAX,
1463 .obj_size = sizeof(unsigned int) *
1464 TCP_CONNTRACK_TIMEOUT_MAX,
1465 .nla_policy = tcp_timeout_nla_policy,
1466 },
1467 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1468 };
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