1 /* (C) 1999-2001 Paul `Rusty' Russell
2 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 */
8
9 #include <linux/types.h>
10 #include <linux/timer.h>
11 #include <linux/module.h>
12 #include <linux/in.h>
13 #include <linux/tcp.h>
14 #include <linux/spinlock.h>
15 #include <linux/skbuff.h>
16 #include <linux/ipv6.h>
17 #include <net/ip6_checksum.h>
18 #include <asm/unaligned.h>
19
20 #include <net/tcp.h>
21
22 #include <linux/netfilter.h>
23 #include <linux/netfilter_ipv4.h>
24 #include <linux/netfilter_ipv6.h>
25 #include <net/netfilter/nf_conntrack.h>
26 #include <net/netfilter/nf_conntrack_l4proto.h>
27 #include <net/netfilter/nf_conntrack_ecache.h>
28 #include <net/netfilter/nf_log.h>
29 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
30 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
31
32 /* "Be conservative in what you do,
33 be liberal in what you accept from others."
34 If it's non-zero, we mark only out of window RST segments as INVALID. */
35 static int nf_ct_tcp_be_liberal __read_mostly = 0;
36
37 /* If it is set to zero, we disable picking up already established
38 connections. */
39 static int nf_ct_tcp_loose __read_mostly = 1;
40
41 /* Max number of the retransmitted packets without receiving an (acceptable)
42 ACK from the destination. If this number is reached, a shorter timer
43 will be started. */
44 static int nf_ct_tcp_max_retrans __read_mostly = 3;
45
46 /* FIXME: Examine ipfilter's timeouts and conntrack transitions more
47 closely. They're more complex. --RR */
48
49 static const char *const tcp_conntrack_names[] = {
50 "NONE",
51 "SYN_SENT",
52 "SYN_RECV",
53 "ESTABLISHED",
54 "FIN_WAIT",
55 "CLOSE_WAIT",
56 "LAST_ACK",
57 "TIME_WAIT",
58 "CLOSE",
59 "SYN_SENT2",
60 };
61
62 #define SECS * HZ
63 #define MINS * 60 SECS
64 #define HOURS * 60 MINS
65 #define DAYS * 24 HOURS
66
67 /* RFC1122 says the R2 limit should be at least 100 seconds.
68 Linux uses 15 packets as limit, which corresponds
69 to ~13-30min depending on RTO. */
70 static unsigned int nf_ct_tcp_timeout_max_retrans __read_mostly = 5 MINS;
71 static unsigned int nf_ct_tcp_timeout_unacknowledged __read_mostly = 5 MINS;
72
73 static unsigned int tcp_timeouts[TCP_CONNTRACK_MAX] __read_mostly = {
74 [TCP_CONNTRACK_SYN_SENT] = 2 MINS,
75 [TCP_CONNTRACK_SYN_RECV] = 60 SECS,
76 [TCP_CONNTRACK_ESTABLISHED] = 5 DAYS,
77 [TCP_CONNTRACK_FIN_WAIT] = 2 MINS,
78 [TCP_CONNTRACK_CLOSE_WAIT] = 60 SECS,
79 [TCP_CONNTRACK_LAST_ACK] = 30 SECS,
80 [TCP_CONNTRACK_TIME_WAIT] = 2 MINS,
81 [TCP_CONNTRACK_CLOSE] = 10 SECS,
82 [TCP_CONNTRACK_SYN_SENT2] = 2 MINS,
83 };
84
85 #define sNO TCP_CONNTRACK_NONE
86 #define sSS TCP_CONNTRACK_SYN_SENT
87 #define sSR TCP_CONNTRACK_SYN_RECV
88 #define sES TCP_CONNTRACK_ESTABLISHED
89 #define sFW TCP_CONNTRACK_FIN_WAIT
90 #define sCW TCP_CONNTRACK_CLOSE_WAIT
91 #define sLA TCP_CONNTRACK_LAST_ACK
92 #define sTW TCP_CONNTRACK_TIME_WAIT
93 #define sCL TCP_CONNTRACK_CLOSE
94 #define sS2 TCP_CONNTRACK_SYN_SENT2
95 #define sIV TCP_CONNTRACK_MAX
96 #define sIG TCP_CONNTRACK_IGNORE
97
98 /* What TCP flags are set from RST/SYN/FIN/ACK. */
99 enum tcp_bit_set {
100 TCP_SYN_SET,
101 TCP_SYNACK_SET,
102 TCP_FIN_SET,
103 TCP_ACK_SET,
104 TCP_RST_SET,
105 TCP_NONE_SET,
106 };
107
108 /*
109 * The TCP state transition table needs a few words...
110 *
111 * We are the man in the middle. All the packets go through us
112 * but might get lost in transit to the destination.
113 * It is assumed that the destinations can't receive segments
114 * we haven't seen.
115 *
116 * The checked segment is in window, but our windows are *not*
117 * equivalent with the ones of the sender/receiver. We always
118 * try to guess the state of the current sender.
119 *
120 * The meaning of the states are:
121 *
122 * NONE: initial state
123 * SYN_SENT: SYN-only packet seen
124 * SYN_SENT2: SYN-only packet seen from reply dir, simultaneous open
125 * SYN_RECV: SYN-ACK packet seen
126 * ESTABLISHED: ACK packet seen
127 * FIN_WAIT: FIN packet seen
128 * CLOSE_WAIT: ACK seen (after FIN)
129 * LAST_ACK: FIN seen (after FIN)
130 * TIME_WAIT: last ACK seen
131 * CLOSE: closed connection (RST)
132 *
133 * Packets marked as IGNORED (sIG):
134 * if they may be either invalid or valid
135 * and the receiver may send back a connection
136 * closing RST or a SYN/ACK.
137 *
138 * Packets marked as INVALID (sIV):
139 * if we regard them as truly invalid packets
140 */
141 static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
142 {
143 /* ORIGINAL */
144 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
145 /*syn*/ { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sS2 },
146 /*
147 * sNO -> sSS Initialize a new connection
148 * sSS -> sSS Retransmitted SYN
149 * sS2 -> sS2 Late retransmitted SYN
150 * sSR -> sIG
151 * sES -> sIG Error: SYNs in window outside the SYN_SENT state
152 * are errors. Receiver will reply with RST
153 * and close the connection.
154 * Or we are not in sync and hold a dead connection.
155 * sFW -> sIG
156 * sCW -> sIG
157 * sLA -> sIG
158 * sTW -> sSS Reopened connection (RFC 1122).
159 * sCL -> sSS
160 */
161 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
162 /*synack*/ { sIV, sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIG, sSR },
163 /*
164 * sNO -> sIV Too late and no reason to do anything
165 * sSS -> sIV Client can't send SYN and then SYN/ACK
166 * sS2 -> sSR SYN/ACK sent to SYN2 in simultaneous open
167 * sSR -> sIG
168 * sES -> sIG Error: SYNs in window outside the SYN_SENT state
169 * are errors. Receiver will reply with RST
170 * and close the connection.
171 * Or we are not in sync and hold a dead connection.
172 * sFW -> sIG
173 * sCW -> sIG
174 * sLA -> sIG
175 * sTW -> sIG
176 * sCL -> sIG
177 */
178 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
179 /*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
180 /*
181 * sNO -> sIV Too late and no reason to do anything...
182 * sSS -> sIV Client migth not send FIN in this state:
183 * we enforce waiting for a SYN/ACK reply first.
184 * sS2 -> sIV
185 * sSR -> sFW Close started.
186 * sES -> sFW
187 * sFW -> sLA FIN seen in both directions, waiting for
188 * the last ACK.
189 * Migth be a retransmitted FIN as well...
190 * sCW -> sLA
191 * sLA -> sLA Retransmitted FIN. Remain in the same state.
192 * sTW -> sTW
193 * sCL -> sCL
194 */
195 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
196 /*ack*/ { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV },
197 /*
198 * sNO -> sES Assumed.
199 * sSS -> sIV ACK is invalid: we haven't seen a SYN/ACK yet.
200 * sS2 -> sIV
201 * sSR -> sES Established state is reached.
202 * sES -> sES :-)
203 * sFW -> sCW Normal close request answered by ACK.
204 * sCW -> sCW
205 * sLA -> sTW Last ACK detected.
206 * sTW -> sTW Retransmitted last ACK. Remain in the same state.
207 * sCL -> sCL
208 */
209 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
210 /*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
211 /*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
212 },
213 {
214 /* REPLY */
215 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
216 /*syn*/ { sIV, sS2, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sS2 },
217 /*
218 * sNO -> sIV Never reached.
219 * sSS -> sS2 Simultaneous open
220 * sS2 -> sS2 Retransmitted simultaneous SYN
221 * sSR -> sIV Invalid SYN packets sent by the server
222 * sES -> sIV
223 * sFW -> sIV
224 * sCW -> sIV
225 * sLA -> sIV
226 * sTW -> sIV Reopened connection, but server may not do it.
227 * sCL -> sIV
228 */
229 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
230 /*synack*/ { sIV, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIG, sSR },
231 /*
232 * sSS -> sSR Standard open.
233 * sS2 -> sSR Simultaneous open
234 * sSR -> sIG Retransmitted SYN/ACK, ignore it.
235 * sES -> sIG Late retransmitted SYN/ACK?
236 * sFW -> sIG Might be SYN/ACK answering ignored SYN
237 * sCW -> sIG
238 * sLA -> sIG
239 * sTW -> sIG
240 * sCL -> sIG
241 */
242 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
243 /*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
244 /*
245 * sSS -> sIV Server might not send FIN in this state.
246 * sS2 -> sIV
247 * sSR -> sFW Close started.
248 * sES -> sFW
249 * sFW -> sLA FIN seen in both directions.
250 * sCW -> sLA
251 * sLA -> sLA Retransmitted FIN.
252 * sTW -> sTW
253 * sCL -> sCL
254 */
255 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
256 /*ack*/ { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIG },
257 /*
258 * sSS -> sIG Might be a half-open connection.
259 * sS2 -> sIG
260 * sSR -> sSR Might answer late resent SYN.
261 * sES -> sES :-)
262 * sFW -> sCW Normal close request answered by ACK.
263 * sCW -> sCW
264 * sLA -> sTW Last ACK detected.
265 * sTW -> sTW Retransmitted last ACK.
266 * sCL -> sCL
267 */
268 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
269 /*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
270 /*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
271 }
272 };
273
tcp_pkt_to_tuple(const struct sk_buff * skb,unsigned int dataoff,struct nf_conntrack_tuple * tuple)274 static bool tcp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
275 struct nf_conntrack_tuple *tuple)
276 {
277 const struct tcphdr *hp;
278 struct tcphdr _hdr;
279
280 /* Actually only need first 8 bytes. */
281 hp = skb_header_pointer(skb, dataoff, 8, &_hdr);
282 if (hp == NULL)
283 return false;
284
285 tuple->src.u.tcp.port = hp->source;
286 tuple->dst.u.tcp.port = hp->dest;
287
288 return true;
289 }
290
tcp_invert_tuple(struct nf_conntrack_tuple * tuple,const struct nf_conntrack_tuple * orig)291 static bool tcp_invert_tuple(struct nf_conntrack_tuple *tuple,
292 const struct nf_conntrack_tuple *orig)
293 {
294 tuple->src.u.tcp.port = orig->dst.u.tcp.port;
295 tuple->dst.u.tcp.port = orig->src.u.tcp.port;
296 return true;
297 }
298
299 /* Print out the per-protocol part of the tuple. */
tcp_print_tuple(struct seq_file * s,const struct nf_conntrack_tuple * tuple)300 static int tcp_print_tuple(struct seq_file *s,
301 const struct nf_conntrack_tuple *tuple)
302 {
303 return seq_printf(s, "sport=%hu dport=%hu ",
304 ntohs(tuple->src.u.tcp.port),
305 ntohs(tuple->dst.u.tcp.port));
306 }
307
308 /* Print out the private part of the conntrack. */
tcp_print_conntrack(struct seq_file * s,struct nf_conn * ct)309 static int tcp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
310 {
311 enum tcp_conntrack state;
312
313 spin_lock_bh(&ct->lock);
314 state = ct->proto.tcp.state;
315 spin_unlock_bh(&ct->lock);
316
317 return seq_printf(s, "%s ", tcp_conntrack_names[state]);
318 }
319
get_conntrack_index(const struct tcphdr * tcph)320 static unsigned int get_conntrack_index(const struct tcphdr *tcph)
321 {
322 if (tcph->rst) return TCP_RST_SET;
323 else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET);
324 else if (tcph->fin) return TCP_FIN_SET;
325 else if (tcph->ack) return TCP_ACK_SET;
326 else return TCP_NONE_SET;
327 }
328
329 /* TCP connection tracking based on 'Real Stateful TCP Packet Filtering
330 in IP Filter' by Guido van Rooij.
331
332 http://www.sane.nl/events/sane2000/papers.html
333 http://www.darkart.com/mirrors/www.obfuscation.org/ipf/
334
335 The boundaries and the conditions are changed according to RFC793:
336 the packet must intersect the window (i.e. segments may be
337 after the right or before the left edge) and thus receivers may ACK
338 segments after the right edge of the window.
339
340 td_maxend = max(sack + max(win,1)) seen in reply packets
341 td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets
342 td_maxwin += seq + len - sender.td_maxend
343 if seq + len > sender.td_maxend
344 td_end = max(seq + len) seen in sent packets
345
346 I. Upper bound for valid data: seq <= sender.td_maxend
347 II. Lower bound for valid data: seq + len >= sender.td_end - receiver.td_maxwin
348 III. Upper bound for valid (s)ack: sack <= receiver.td_end
349 IV. Lower bound for valid (s)ack: sack >= receiver.td_end - MAXACKWINDOW
350
351 where sack is the highest right edge of sack block found in the packet
352 or ack in the case of packet without SACK option.
353
354 The upper bound limit for a valid (s)ack is not ignored -
355 we doesn't have to deal with fragments.
356 */
357
segment_seq_plus_len(__u32 seq,size_t len,unsigned int dataoff,const struct tcphdr * tcph)358 static inline __u32 segment_seq_plus_len(__u32 seq,
359 size_t len,
360 unsigned int dataoff,
361 const struct tcphdr *tcph)
362 {
363 /* XXX Should I use payload length field in IP/IPv6 header ?
364 * - YK */
365 return (seq + len - dataoff - tcph->doff*4
366 + (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0));
367 }
368
369 /* Fixme: what about big packets? */
370 #define MAXACKWINCONST 66000
371 #define MAXACKWINDOW(sender) \
372 ((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin \
373 : MAXACKWINCONST)
374
375 /*
376 * Simplified tcp_parse_options routine from tcp_input.c
377 */
tcp_options(const struct sk_buff * skb,unsigned int dataoff,const struct tcphdr * tcph,struct ip_ct_tcp_state * state)378 static void tcp_options(const struct sk_buff *skb,
379 unsigned int dataoff,
380 const struct tcphdr *tcph,
381 struct ip_ct_tcp_state *state)
382 {
383 unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
384 const unsigned char *ptr;
385 int length = (tcph->doff*4) - sizeof(struct tcphdr);
386
387 if (!length)
388 return;
389
390 ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
391 length, buff);
392 BUG_ON(ptr == NULL);
393
394 state->td_scale =
395 state->flags = 0;
396
397 while (length > 0) {
398 int opcode=*ptr++;
399 int opsize;
400
401 switch (opcode) {
402 case TCPOPT_EOL:
403 return;
404 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
405 length--;
406 continue;
407 default:
408 opsize=*ptr++;
409 if (opsize < 2) /* "silly options" */
410 return;
411 if (opsize > length)
412 return; /* don't parse partial options */
413
414 if (opcode == TCPOPT_SACK_PERM
415 && opsize == TCPOLEN_SACK_PERM)
416 state->flags |= IP_CT_TCP_FLAG_SACK_PERM;
417 else if (opcode == TCPOPT_WINDOW
418 && opsize == TCPOLEN_WINDOW) {
419 state->td_scale = *(u_int8_t *)ptr;
420
421 if (state->td_scale > 14) {
422 /* See RFC1323 */
423 state->td_scale = 14;
424 }
425 state->flags |=
426 IP_CT_TCP_FLAG_WINDOW_SCALE;
427 }
428 ptr += opsize - 2;
429 length -= opsize;
430 }
431 }
432 }
433
tcp_sack(const struct sk_buff * skb,unsigned int dataoff,const struct tcphdr * tcph,__u32 * sack)434 static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
435 const struct tcphdr *tcph, __u32 *sack)
436 {
437 unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
438 const unsigned char *ptr;
439 int length = (tcph->doff*4) - sizeof(struct tcphdr);
440 __u32 tmp;
441
442 if (!length)
443 return;
444
445 ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
446 length, buff);
447 BUG_ON(ptr == NULL);
448
449 /* Fast path for timestamp-only option */
450 if (length == TCPOLEN_TSTAMP_ALIGNED
451 && *(__be32 *)ptr == htonl((TCPOPT_NOP << 24)
452 | (TCPOPT_NOP << 16)
453 | (TCPOPT_TIMESTAMP << 8)
454 | TCPOLEN_TIMESTAMP))
455 return;
456
457 while (length > 0) {
458 int opcode = *ptr++;
459 int opsize, i;
460
461 switch (opcode) {
462 case TCPOPT_EOL:
463 return;
464 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
465 length--;
466 continue;
467 default:
468 opsize = *ptr++;
469 if (opsize < 2) /* "silly options" */
470 return;
471 if (opsize > length)
472 return; /* don't parse partial options */
473
474 if (opcode == TCPOPT_SACK
475 && opsize >= (TCPOLEN_SACK_BASE
476 + TCPOLEN_SACK_PERBLOCK)
477 && !((opsize - TCPOLEN_SACK_BASE)
478 % TCPOLEN_SACK_PERBLOCK)) {
479 for (i = 0;
480 i < (opsize - TCPOLEN_SACK_BASE);
481 i += TCPOLEN_SACK_PERBLOCK) {
482 tmp = get_unaligned_be32((__be32 *)(ptr+i)+1);
483
484 if (after(tmp, *sack))
485 *sack = tmp;
486 }
487 return;
488 }
489 ptr += opsize - 2;
490 length -= opsize;
491 }
492 }
493 }
494
495 #ifdef CONFIG_NF_NAT_NEEDED
nat_offset(const struct nf_conn * ct,enum ip_conntrack_dir dir,u32 seq)496 static inline s16 nat_offset(const struct nf_conn *ct,
497 enum ip_conntrack_dir dir,
498 u32 seq)
499 {
500 typeof(nf_ct_nat_offset) get_offset = rcu_dereference(nf_ct_nat_offset);
501
502 return get_offset != NULL ? get_offset(ct, dir, seq) : 0;
503 }
504 #define NAT_OFFSET(pf, ct, dir, seq) \
505 (pf == NFPROTO_IPV4 ? nat_offset(ct, dir, seq) : 0)
506 #else
507 #define NAT_OFFSET(pf, ct, dir, seq) 0
508 #endif
509
tcp_in_window(const struct nf_conn * ct,struct ip_ct_tcp * state,enum ip_conntrack_dir dir,unsigned int index,const struct sk_buff * skb,unsigned int dataoff,const struct tcphdr * tcph,u_int8_t pf)510 static bool tcp_in_window(const struct nf_conn *ct,
511 struct ip_ct_tcp *state,
512 enum ip_conntrack_dir dir,
513 unsigned int index,
514 const struct sk_buff *skb,
515 unsigned int dataoff,
516 const struct tcphdr *tcph,
517 u_int8_t pf)
518 {
519 struct net *net = nf_ct_net(ct);
520 struct ip_ct_tcp_state *sender = &state->seen[dir];
521 struct ip_ct_tcp_state *receiver = &state->seen[!dir];
522 const struct nf_conntrack_tuple *tuple = &ct->tuplehash[dir].tuple;
523 __u32 seq, ack, sack, end, win, swin;
524 s16 receiver_offset;
525 bool res;
526
527 /*
528 * Get the required data from the packet.
529 */
530 seq = ntohl(tcph->seq);
531 ack = sack = ntohl(tcph->ack_seq);
532 win = ntohs(tcph->window);
533 end = segment_seq_plus_len(seq, skb->len, dataoff, tcph);
534
535 if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
536 tcp_sack(skb, dataoff, tcph, &sack);
537
538 /* Take into account NAT sequence number mangling */
539 receiver_offset = NAT_OFFSET(pf, ct, !dir, ack - 1);
540 ack -= receiver_offset;
541 sack -= receiver_offset;
542
543 pr_debug("tcp_in_window: START\n");
544 pr_debug("tcp_in_window: ");
545 nf_ct_dump_tuple(tuple);
546 pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
547 seq, ack, receiver_offset, sack, receiver_offset, win, end);
548 pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
549 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
550 sender->td_end, sender->td_maxend, sender->td_maxwin,
551 sender->td_scale,
552 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
553 receiver->td_scale);
554
555 if (sender->td_maxwin == 0) {
556 /*
557 * Initialize sender data.
558 */
559 if (tcph->syn) {
560 /*
561 * SYN-ACK in reply to a SYN
562 * or SYN from reply direction in simultaneous open.
563 */
564 sender->td_end =
565 sender->td_maxend = end;
566 sender->td_maxwin = (win == 0 ? 1 : win);
567
568 tcp_options(skb, dataoff, tcph, sender);
569 /*
570 * RFC 1323:
571 * Both sides must send the Window Scale option
572 * to enable window scaling in either direction.
573 */
574 if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE
575 && receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE))
576 sender->td_scale =
577 receiver->td_scale = 0;
578 if (!tcph->ack)
579 /* Simultaneous open */
580 return true;
581 } else {
582 /*
583 * We are in the middle of a connection,
584 * its history is lost for us.
585 * Let's try to use the data from the packet.
586 */
587 sender->td_end = end;
588 win <<= sender->td_scale;
589 sender->td_maxwin = (win == 0 ? 1 : win);
590 sender->td_maxend = end + sender->td_maxwin;
591 /*
592 * We haven't seen traffic in the other direction yet
593 * but we have to tweak window tracking to pass III
594 * and IV until that happens.
595 */
596 if (receiver->td_maxwin == 0)
597 receiver->td_end = receiver->td_maxend = sack;
598 }
599 } else if (((state->state == TCP_CONNTRACK_SYN_SENT
600 && dir == IP_CT_DIR_ORIGINAL)
601 || (state->state == TCP_CONNTRACK_SYN_RECV
602 && dir == IP_CT_DIR_REPLY))
603 && after(end, sender->td_end)) {
604 /*
605 * RFC 793: "if a TCP is reinitialized ... then it need
606 * not wait at all; it must only be sure to use sequence
607 * numbers larger than those recently used."
608 */
609 sender->td_end =
610 sender->td_maxend = end;
611 sender->td_maxwin = (win == 0 ? 1 : win);
612
613 tcp_options(skb, dataoff, tcph, sender);
614 }
615
616 if (!(tcph->ack)) {
617 /*
618 * If there is no ACK, just pretend it was set and OK.
619 */
620 ack = sack = receiver->td_end;
621 } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
622 (TCP_FLAG_ACK|TCP_FLAG_RST))
623 && (ack == 0)) {
624 /*
625 * Broken TCP stacks, that set ACK in RST packets as well
626 * with zero ack value.
627 */
628 ack = sack = receiver->td_end;
629 }
630
631 if (seq == end
632 && (!tcph->rst
633 || (seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)))
634 /*
635 * Packets contains no data: we assume it is valid
636 * and check the ack value only.
637 * However RST segments are always validated by their
638 * SEQ number, except when seq == 0 (reset sent answering
639 * SYN.
640 */
641 seq = end = sender->td_end;
642
643 pr_debug("tcp_in_window: ");
644 nf_ct_dump_tuple(tuple);
645 pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
646 seq, ack, receiver_offset, sack, receiver_offset, win, end);
647 pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
648 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
649 sender->td_end, sender->td_maxend, sender->td_maxwin,
650 sender->td_scale,
651 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
652 receiver->td_scale);
653
654 pr_debug("tcp_in_window: I=%i II=%i III=%i IV=%i\n",
655 before(seq, sender->td_maxend + 1),
656 after(end, sender->td_end - receiver->td_maxwin - 1),
657 before(sack, receiver->td_end + 1),
658 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1));
659
660 if (before(seq, sender->td_maxend + 1) &&
661 after(end, sender->td_end - receiver->td_maxwin - 1) &&
662 before(sack, receiver->td_end + 1) &&
663 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1)) {
664 /*
665 * Take into account window scaling (RFC 1323).
666 */
667 if (!tcph->syn)
668 win <<= sender->td_scale;
669
670 /*
671 * Update sender data.
672 */
673 swin = win + (sack - ack);
674 if (sender->td_maxwin < swin)
675 sender->td_maxwin = swin;
676 if (after(end, sender->td_end)) {
677 sender->td_end = end;
678 sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
679 }
680 if (tcph->ack) {
681 if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) {
682 sender->td_maxack = ack;
683 sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET;
684 } else if (after(ack, sender->td_maxack))
685 sender->td_maxack = ack;
686 }
687
688 /*
689 * Update receiver data.
690 */
691 if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
692 receiver->td_maxwin += end - sender->td_maxend;
693 if (after(sack + win, receiver->td_maxend - 1)) {
694 receiver->td_maxend = sack + win;
695 if (win == 0)
696 receiver->td_maxend++;
697 }
698 if (ack == receiver->td_end)
699 receiver->flags &= ~IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
700
701 /*
702 * Check retransmissions.
703 */
704 if (index == TCP_ACK_SET) {
705 if (state->last_dir == dir
706 && state->last_seq == seq
707 && state->last_ack == ack
708 && state->last_end == end
709 && state->last_win == win)
710 state->retrans++;
711 else {
712 state->last_dir = dir;
713 state->last_seq = seq;
714 state->last_ack = ack;
715 state->last_end = end;
716 state->last_win = win;
717 state->retrans = 0;
718 }
719 }
720 res = true;
721 } else {
722 res = false;
723 if (sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL ||
724 nf_ct_tcp_be_liberal)
725 res = true;
726 if (!res && LOG_INVALID(net, IPPROTO_TCP))
727 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
728 "nf_ct_tcp: %s ",
729 before(seq, sender->td_maxend + 1) ?
730 after(end, sender->td_end - receiver->td_maxwin - 1) ?
731 before(sack, receiver->td_end + 1) ?
732 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1) ? "BUG"
733 : "ACK is under the lower bound (possible overly delayed ACK)"
734 : "ACK is over the upper bound (ACKed data not seen yet)"
735 : "SEQ is under the lower bound (already ACKed data retransmitted)"
736 : "SEQ is over the upper bound (over the window of the receiver)");
737 }
738
739 pr_debug("tcp_in_window: res=%u sender end=%u maxend=%u maxwin=%u "
740 "receiver end=%u maxend=%u maxwin=%u\n",
741 res, sender->td_end, sender->td_maxend, sender->td_maxwin,
742 receiver->td_end, receiver->td_maxend, receiver->td_maxwin);
743
744 return res;
745 }
746
747 /* table of valid flag combinations - PUSH, ECE and CWR are always valid */
748 static const u8 tcp_valid_flags[(TCPHDR_FIN|TCPHDR_SYN|TCPHDR_RST|TCPHDR_ACK|
749 TCPHDR_URG) + 1] =
750 {
751 [TCPHDR_SYN] = 1,
752 [TCPHDR_SYN|TCPHDR_URG] = 1,
753 [TCPHDR_SYN|TCPHDR_ACK] = 1,
754 [TCPHDR_RST] = 1,
755 [TCPHDR_RST|TCPHDR_ACK] = 1,
756 [TCPHDR_FIN|TCPHDR_ACK] = 1,
757 [TCPHDR_FIN|TCPHDR_ACK|TCPHDR_URG] = 1,
758 [TCPHDR_ACK] = 1,
759 [TCPHDR_ACK|TCPHDR_URG] = 1,
760 };
761
762 /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c. */
tcp_error(struct net * net,struct nf_conn * tmpl,struct sk_buff * skb,unsigned int dataoff,enum ip_conntrack_info * ctinfo,u_int8_t pf,unsigned int hooknum)763 static int tcp_error(struct net *net, struct nf_conn *tmpl,
764 struct sk_buff *skb,
765 unsigned int dataoff,
766 enum ip_conntrack_info *ctinfo,
767 u_int8_t pf,
768 unsigned int hooknum)
769 {
770 const struct tcphdr *th;
771 struct tcphdr _tcph;
772 unsigned int tcplen = skb->len - dataoff;
773 u_int8_t tcpflags;
774
775 /* Smaller that minimal TCP header? */
776 th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
777 if (th == NULL) {
778 if (LOG_INVALID(net, IPPROTO_TCP))
779 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
780 "nf_ct_tcp: short packet ");
781 return -NF_ACCEPT;
782 }
783
784 /* Not whole TCP header or malformed packet */
785 if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
786 if (LOG_INVALID(net, IPPROTO_TCP))
787 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
788 "nf_ct_tcp: truncated/malformed packet ");
789 return -NF_ACCEPT;
790 }
791
792 /* Checksum invalid? Ignore.
793 * We skip checking packets on the outgoing path
794 * because the checksum is assumed to be correct.
795 */
796 /* FIXME: Source route IP option packets --RR */
797 if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
798 nf_checksum(skb, hooknum, dataoff, IPPROTO_TCP, pf)) {
799 if (LOG_INVALID(net, IPPROTO_TCP))
800 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
801 "nf_ct_tcp: bad TCP checksum ");
802 return -NF_ACCEPT;
803 }
804
805 /* Check TCP flags. */
806 tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
807 if (!tcp_valid_flags[tcpflags]) {
808 if (LOG_INVALID(net, IPPROTO_TCP))
809 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
810 "nf_ct_tcp: invalid TCP flag combination ");
811 return -NF_ACCEPT;
812 }
813
814 return NF_ACCEPT;
815 }
816
817 /* Returns verdict for packet, or -1 for invalid. */
tcp_packet(struct nf_conn * ct,const struct sk_buff * skb,unsigned int dataoff,enum ip_conntrack_info ctinfo,u_int8_t pf,unsigned int hooknum)818 static int tcp_packet(struct nf_conn *ct,
819 const struct sk_buff *skb,
820 unsigned int dataoff,
821 enum ip_conntrack_info ctinfo,
822 u_int8_t pf,
823 unsigned int hooknum)
824 {
825 struct net *net = nf_ct_net(ct);
826 struct nf_conntrack_tuple *tuple;
827 enum tcp_conntrack new_state, old_state;
828 enum ip_conntrack_dir dir;
829 const struct tcphdr *th;
830 struct tcphdr _tcph;
831 unsigned long timeout;
832 unsigned int index;
833
834 th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
835 BUG_ON(th == NULL);
836
837 spin_lock_bh(&ct->lock);
838 old_state = ct->proto.tcp.state;
839 dir = CTINFO2DIR(ctinfo);
840 index = get_conntrack_index(th);
841 new_state = tcp_conntracks[dir][index][old_state];
842 tuple = &ct->tuplehash[dir].tuple;
843
844 switch (new_state) {
845 case TCP_CONNTRACK_SYN_SENT:
846 if (old_state < TCP_CONNTRACK_TIME_WAIT)
847 break;
848 /* RFC 1122: "When a connection is closed actively,
849 * it MUST linger in TIME-WAIT state for a time 2xMSL
850 * (Maximum Segment Lifetime). However, it MAY accept
851 * a new SYN from the remote TCP to reopen the connection
852 * directly from TIME-WAIT state, if..."
853 * We ignore the conditions because we are in the
854 * TIME-WAIT state anyway.
855 *
856 * Handle aborted connections: we and the server
857 * think there is an existing connection but the client
858 * aborts it and starts a new one.
859 */
860 if (((ct->proto.tcp.seen[dir].flags
861 | ct->proto.tcp.seen[!dir].flags)
862 & IP_CT_TCP_FLAG_CLOSE_INIT)
863 || (ct->proto.tcp.last_dir == dir
864 && ct->proto.tcp.last_index == TCP_RST_SET)) {
865 /* Attempt to reopen a closed/aborted connection.
866 * Delete this connection and look up again. */
867 spin_unlock_bh(&ct->lock);
868
869 /* Only repeat if we can actually remove the timer.
870 * Destruction may already be in progress in process
871 * context and we must give it a chance to terminate.
872 */
873 if (nf_ct_kill(ct))
874 return -NF_REPEAT;
875 return NF_DROP;
876 }
877 /* Fall through */
878 case TCP_CONNTRACK_IGNORE:
879 /* Ignored packets:
880 *
881 * Our connection entry may be out of sync, so ignore
882 * packets which may signal the real connection between
883 * the client and the server.
884 *
885 * a) SYN in ORIGINAL
886 * b) SYN/ACK in REPLY
887 * c) ACK in reply direction after initial SYN in original.
888 *
889 * If the ignored packet is invalid, the receiver will send
890 * a RST we'll catch below.
891 */
892 if (index == TCP_SYNACK_SET
893 && ct->proto.tcp.last_index == TCP_SYN_SET
894 && ct->proto.tcp.last_dir != dir
895 && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
896 /* b) This SYN/ACK acknowledges a SYN that we earlier
897 * ignored as invalid. This means that the client and
898 * the server are both in sync, while the firewall is
899 * not. We get in sync from the previously annotated
900 * values.
901 */
902 old_state = TCP_CONNTRACK_SYN_SENT;
903 new_state = TCP_CONNTRACK_SYN_RECV;
904 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
905 ct->proto.tcp.last_end;
906 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
907 ct->proto.tcp.last_end;
908 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
909 ct->proto.tcp.last_win == 0 ?
910 1 : ct->proto.tcp.last_win;
911 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
912 ct->proto.tcp.last_wscale;
913 ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
914 ct->proto.tcp.last_flags;
915 memset(&ct->proto.tcp.seen[dir], 0,
916 sizeof(struct ip_ct_tcp_state));
917 break;
918 }
919 ct->proto.tcp.last_index = index;
920 ct->proto.tcp.last_dir = dir;
921 ct->proto.tcp.last_seq = ntohl(th->seq);
922 ct->proto.tcp.last_end =
923 segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
924 ct->proto.tcp.last_win = ntohs(th->window);
925
926 /* a) This is a SYN in ORIGINAL. The client and the server
927 * may be in sync but we are not. In that case, we annotate
928 * the TCP options and let the packet go through. If it is a
929 * valid SYN packet, the server will reply with a SYN/ACK, and
930 * then we'll get in sync. Otherwise, the server ignores it. */
931 if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
932 struct ip_ct_tcp_state seen = {};
933
934 ct->proto.tcp.last_flags =
935 ct->proto.tcp.last_wscale = 0;
936 tcp_options(skb, dataoff, th, &seen);
937 if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
938 ct->proto.tcp.last_flags |=
939 IP_CT_TCP_FLAG_WINDOW_SCALE;
940 ct->proto.tcp.last_wscale = seen.td_scale;
941 }
942 if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
943 ct->proto.tcp.last_flags |=
944 IP_CT_TCP_FLAG_SACK_PERM;
945 }
946 }
947 spin_unlock_bh(&ct->lock);
948 if (LOG_INVALID(net, IPPROTO_TCP))
949 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
950 "nf_ct_tcp: invalid packet ignored ");
951 return NF_ACCEPT;
952 case TCP_CONNTRACK_MAX:
953 /* Invalid packet */
954 pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
955 dir, get_conntrack_index(th), old_state);
956 spin_unlock_bh(&ct->lock);
957 if (LOG_INVALID(net, IPPROTO_TCP))
958 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
959 "nf_ct_tcp: invalid state ");
960 return -NF_ACCEPT;
961 case TCP_CONNTRACK_CLOSE:
962 if (index == TCP_RST_SET
963 && (ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET)
964 && before(ntohl(th->seq), ct->proto.tcp.seen[!dir].td_maxack)) {
965 /* Invalid RST */
966 spin_unlock_bh(&ct->lock);
967 if (LOG_INVALID(net, IPPROTO_TCP))
968 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
969 "nf_ct_tcp: invalid RST ");
970 return -NF_ACCEPT;
971 }
972 if (index == TCP_RST_SET
973 && ((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
974 && ct->proto.tcp.last_index == TCP_SYN_SET)
975 || (!test_bit(IPS_ASSURED_BIT, &ct->status)
976 && ct->proto.tcp.last_index == TCP_ACK_SET))
977 && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
978 /* RST sent to invalid SYN or ACK we had let through
979 * at a) and c) above:
980 *
981 * a) SYN was in window then
982 * c) we hold a half-open connection.
983 *
984 * Delete our connection entry.
985 * We skip window checking, because packet might ACK
986 * segments we ignored. */
987 goto in_window;
988 }
989 /* Just fall through */
990 default:
991 /* Keep compilers happy. */
992 break;
993 }
994
995 if (!tcp_in_window(ct, &ct->proto.tcp, dir, index,
996 skb, dataoff, th, pf)) {
997 spin_unlock_bh(&ct->lock);
998 return -NF_ACCEPT;
999 }
1000 in_window:
1001 /* From now on we have got in-window packets */
1002 ct->proto.tcp.last_index = index;
1003 ct->proto.tcp.last_dir = dir;
1004
1005 pr_debug("tcp_conntracks: ");
1006 nf_ct_dump_tuple(tuple);
1007 pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
1008 (th->syn ? 1 : 0), (th->ack ? 1 : 0),
1009 (th->fin ? 1 : 0), (th->rst ? 1 : 0),
1010 old_state, new_state);
1011
1012 ct->proto.tcp.state = new_state;
1013 if (old_state != new_state
1014 && new_state == TCP_CONNTRACK_FIN_WAIT)
1015 ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
1016
1017 if (ct->proto.tcp.retrans >= nf_ct_tcp_max_retrans &&
1018 tcp_timeouts[new_state] > nf_ct_tcp_timeout_max_retrans)
1019 timeout = nf_ct_tcp_timeout_max_retrans;
1020 else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
1021 IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
1022 tcp_timeouts[new_state] > nf_ct_tcp_timeout_unacknowledged)
1023 timeout = nf_ct_tcp_timeout_unacknowledged;
1024 else
1025 timeout = tcp_timeouts[new_state];
1026 spin_unlock_bh(&ct->lock);
1027
1028 if (new_state != old_state)
1029 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
1030
1031 if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
1032 /* If only reply is a RST, we can consider ourselves not to
1033 have an established connection: this is a fairly common
1034 problem case, so we can delete the conntrack
1035 immediately. --RR */
1036 if (th->rst) {
1037 nf_ct_kill_acct(ct, ctinfo, skb);
1038 return NF_ACCEPT;
1039 }
1040 } else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
1041 && (old_state == TCP_CONNTRACK_SYN_RECV
1042 || old_state == TCP_CONNTRACK_ESTABLISHED)
1043 && new_state == TCP_CONNTRACK_ESTABLISHED) {
1044 /* Set ASSURED if we see see valid ack in ESTABLISHED
1045 after SYN_RECV or a valid answer for a picked up
1046 connection. */
1047 set_bit(IPS_ASSURED_BIT, &ct->status);
1048 nf_conntrack_event_cache(IPCT_ASSURED, ct);
1049 }
1050 nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
1051
1052 return NF_ACCEPT;
1053 }
1054
1055 /* Called when a new connection for this protocol found. */
tcp_new(struct nf_conn * ct,const struct sk_buff * skb,unsigned int dataoff)1056 static bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
1057 unsigned int dataoff)
1058 {
1059 enum tcp_conntrack new_state;
1060 const struct tcphdr *th;
1061 struct tcphdr _tcph;
1062 const struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[0];
1063 const struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[1];
1064
1065 th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
1066 BUG_ON(th == NULL);
1067
1068 /* Don't need lock here: this conntrack not in circulation yet */
1069 new_state = tcp_conntracks[0][get_conntrack_index(th)][TCP_CONNTRACK_NONE];
1070
1071 /* Invalid: delete conntrack */
1072 if (new_state >= TCP_CONNTRACK_MAX) {
1073 pr_debug("nf_ct_tcp: invalid new deleting.\n");
1074 return false;
1075 }
1076
1077 if (new_state == TCP_CONNTRACK_SYN_SENT) {
1078 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
1079 /* SYN packet */
1080 ct->proto.tcp.seen[0].td_end =
1081 segment_seq_plus_len(ntohl(th->seq), skb->len,
1082 dataoff, th);
1083 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
1084 if (ct->proto.tcp.seen[0].td_maxwin == 0)
1085 ct->proto.tcp.seen[0].td_maxwin = 1;
1086 ct->proto.tcp.seen[0].td_maxend =
1087 ct->proto.tcp.seen[0].td_end;
1088
1089 tcp_options(skb, dataoff, th, &ct->proto.tcp.seen[0]);
1090 } else if (nf_ct_tcp_loose == 0) {
1091 /* Don't try to pick up connections. */
1092 return false;
1093 } else {
1094 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
1095 /*
1096 * We are in the middle of a connection,
1097 * its history is lost for us.
1098 * Let's try to use the data from the packet.
1099 */
1100 ct->proto.tcp.seen[0].td_end =
1101 segment_seq_plus_len(ntohl(th->seq), skb->len,
1102 dataoff, th);
1103 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
1104 if (ct->proto.tcp.seen[0].td_maxwin == 0)
1105 ct->proto.tcp.seen[0].td_maxwin = 1;
1106 ct->proto.tcp.seen[0].td_maxend =
1107 ct->proto.tcp.seen[0].td_end +
1108 ct->proto.tcp.seen[0].td_maxwin;
1109
1110 /* We assume SACK and liberal window checking to handle
1111 * window scaling */
1112 ct->proto.tcp.seen[0].flags =
1113 ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
1114 IP_CT_TCP_FLAG_BE_LIBERAL;
1115 }
1116
1117 /* tcp_packet will set them */
1118 ct->proto.tcp.last_index = TCP_NONE_SET;
1119
1120 pr_debug("tcp_new: sender end=%u maxend=%u maxwin=%u scale=%i "
1121 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
1122 sender->td_end, sender->td_maxend, sender->td_maxwin,
1123 sender->td_scale,
1124 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
1125 receiver->td_scale);
1126 return true;
1127 }
1128
1129 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1130
1131 #include <linux/netfilter/nfnetlink.h>
1132 #include <linux/netfilter/nfnetlink_conntrack.h>
1133
tcp_to_nlattr(struct sk_buff * skb,struct nlattr * nla,struct nf_conn * ct)1134 static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1135 struct nf_conn *ct)
1136 {
1137 struct nlattr *nest_parms;
1138 struct nf_ct_tcp_flags tmp = {};
1139
1140 spin_lock_bh(&ct->lock);
1141 nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP | NLA_F_NESTED);
1142 if (!nest_parms)
1143 goto nla_put_failure;
1144
1145 NLA_PUT_U8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state);
1146
1147 NLA_PUT_U8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1148 ct->proto.tcp.seen[0].td_scale);
1149
1150 NLA_PUT_U8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
1151 ct->proto.tcp.seen[1].td_scale);
1152
1153 tmp.flags = ct->proto.tcp.seen[0].flags;
1154 NLA_PUT(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1155 sizeof(struct nf_ct_tcp_flags), &tmp);
1156
1157 tmp.flags = ct->proto.tcp.seen[1].flags;
1158 NLA_PUT(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1159 sizeof(struct nf_ct_tcp_flags), &tmp);
1160 spin_unlock_bh(&ct->lock);
1161
1162 nla_nest_end(skb, nest_parms);
1163
1164 return 0;
1165
1166 nla_put_failure:
1167 spin_unlock_bh(&ct->lock);
1168 return -1;
1169 }
1170
1171 static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1172 [CTA_PROTOINFO_TCP_STATE] = { .type = NLA_U8 },
1173 [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1174 [CTA_PROTOINFO_TCP_WSCALE_REPLY] = { .type = NLA_U8 },
1175 [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL] = { .len = sizeof(struct nf_ct_tcp_flags) },
1176 [CTA_PROTOINFO_TCP_FLAGS_REPLY] = { .len = sizeof(struct nf_ct_tcp_flags) },
1177 };
1178
nlattr_to_tcp(struct nlattr * cda[],struct nf_conn * ct)1179 static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1180 {
1181 struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
1182 struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1183 int err;
1184
1185 /* updates could not contain anything about the private
1186 * protocol info, in that case skip the parsing */
1187 if (!pattr)
1188 return 0;
1189
1190 err = nla_parse_nested(tb, CTA_PROTOINFO_TCP_MAX, pattr, tcp_nla_policy);
1191 if (err < 0)
1192 return err;
1193
1194 if (tb[CTA_PROTOINFO_TCP_STATE] &&
1195 nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
1196 return -EINVAL;
1197
1198 spin_lock_bh(&ct->lock);
1199 if (tb[CTA_PROTOINFO_TCP_STATE])
1200 ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
1201
1202 if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1203 struct nf_ct_tcp_flags *attr =
1204 nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1205 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1206 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1207 }
1208
1209 if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1210 struct nf_ct_tcp_flags *attr =
1211 nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1212 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1213 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1214 }
1215
1216 if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1217 tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1218 ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1219 ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1220 ct->proto.tcp.seen[0].td_scale =
1221 nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1222 ct->proto.tcp.seen[1].td_scale =
1223 nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1224 }
1225 spin_unlock_bh(&ct->lock);
1226
1227 return 0;
1228 }
1229
tcp_nlattr_size(void)1230 static int tcp_nlattr_size(void)
1231 {
1232 return nla_total_size(0) /* CTA_PROTOINFO_TCP */
1233 + nla_policy_len(tcp_nla_policy, CTA_PROTOINFO_TCP_MAX + 1);
1234 }
1235
tcp_nlattr_tuple_size(void)1236 static int tcp_nlattr_tuple_size(void)
1237 {
1238 return nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
1239 }
1240 #endif
1241
1242 #ifdef CONFIG_SYSCTL
1243 static unsigned int tcp_sysctl_table_users;
1244 static struct ctl_table_header *tcp_sysctl_header;
1245 static struct ctl_table tcp_sysctl_table[] = {
1246 {
1247 .procname = "nf_conntrack_tcp_timeout_syn_sent",
1248 .data = &tcp_timeouts[TCP_CONNTRACK_SYN_SENT],
1249 .maxlen = sizeof(unsigned int),
1250 .mode = 0644,
1251 .proc_handler = proc_dointvec_jiffies,
1252 },
1253 {
1254 .procname = "nf_conntrack_tcp_timeout_syn_recv",
1255 .data = &tcp_timeouts[TCP_CONNTRACK_SYN_RECV],
1256 .maxlen = sizeof(unsigned int),
1257 .mode = 0644,
1258 .proc_handler = proc_dointvec_jiffies,
1259 },
1260 {
1261 .procname = "nf_conntrack_tcp_timeout_established",
1262 .data = &tcp_timeouts[TCP_CONNTRACK_ESTABLISHED],
1263 .maxlen = sizeof(unsigned int),
1264 .mode = 0644,
1265 .proc_handler = proc_dointvec_jiffies,
1266 },
1267 {
1268 .procname = "nf_conntrack_tcp_timeout_fin_wait",
1269 .data = &tcp_timeouts[TCP_CONNTRACK_FIN_WAIT],
1270 .maxlen = sizeof(unsigned int),
1271 .mode = 0644,
1272 .proc_handler = proc_dointvec_jiffies,
1273 },
1274 {
1275 .procname = "nf_conntrack_tcp_timeout_close_wait",
1276 .data = &tcp_timeouts[TCP_CONNTRACK_CLOSE_WAIT],
1277 .maxlen = sizeof(unsigned int),
1278 .mode = 0644,
1279 .proc_handler = proc_dointvec_jiffies,
1280 },
1281 {
1282 .procname = "nf_conntrack_tcp_timeout_last_ack",
1283 .data = &tcp_timeouts[TCP_CONNTRACK_LAST_ACK],
1284 .maxlen = sizeof(unsigned int),
1285 .mode = 0644,
1286 .proc_handler = proc_dointvec_jiffies,
1287 },
1288 {
1289 .procname = "nf_conntrack_tcp_timeout_time_wait",
1290 .data = &tcp_timeouts[TCP_CONNTRACK_TIME_WAIT],
1291 .maxlen = sizeof(unsigned int),
1292 .mode = 0644,
1293 .proc_handler = proc_dointvec_jiffies,
1294 },
1295 {
1296 .procname = "nf_conntrack_tcp_timeout_close",
1297 .data = &tcp_timeouts[TCP_CONNTRACK_CLOSE],
1298 .maxlen = sizeof(unsigned int),
1299 .mode = 0644,
1300 .proc_handler = proc_dointvec_jiffies,
1301 },
1302 {
1303 .procname = "nf_conntrack_tcp_timeout_max_retrans",
1304 .data = &nf_ct_tcp_timeout_max_retrans,
1305 .maxlen = sizeof(unsigned int),
1306 .mode = 0644,
1307 .proc_handler = proc_dointvec_jiffies,
1308 },
1309 {
1310 .procname = "nf_conntrack_tcp_timeout_unacknowledged",
1311 .data = &nf_ct_tcp_timeout_unacknowledged,
1312 .maxlen = sizeof(unsigned int),
1313 .mode = 0644,
1314 .proc_handler = proc_dointvec_jiffies,
1315 },
1316 {
1317 .procname = "nf_conntrack_tcp_loose",
1318 .data = &nf_ct_tcp_loose,
1319 .maxlen = sizeof(unsigned int),
1320 .mode = 0644,
1321 .proc_handler = proc_dointvec,
1322 },
1323 {
1324 .procname = "nf_conntrack_tcp_be_liberal",
1325 .data = &nf_ct_tcp_be_liberal,
1326 .maxlen = sizeof(unsigned int),
1327 .mode = 0644,
1328 .proc_handler = proc_dointvec,
1329 },
1330 {
1331 .procname = "nf_conntrack_tcp_max_retrans",
1332 .data = &nf_ct_tcp_max_retrans,
1333 .maxlen = sizeof(unsigned int),
1334 .mode = 0644,
1335 .proc_handler = proc_dointvec,
1336 },
1337 { }
1338 };
1339
1340 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
1341 static struct ctl_table tcp_compat_sysctl_table[] = {
1342 {
1343 .procname = "ip_conntrack_tcp_timeout_syn_sent",
1344 .data = &tcp_timeouts[TCP_CONNTRACK_SYN_SENT],
1345 .maxlen = sizeof(unsigned int),
1346 .mode = 0644,
1347 .proc_handler = proc_dointvec_jiffies,
1348 },
1349 {
1350 .procname = "ip_conntrack_tcp_timeout_syn_sent2",
1351 .data = &tcp_timeouts[TCP_CONNTRACK_SYN_SENT2],
1352 .maxlen = sizeof(unsigned int),
1353 .mode = 0644,
1354 .proc_handler = proc_dointvec_jiffies,
1355 },
1356 {
1357 .procname = "ip_conntrack_tcp_timeout_syn_recv",
1358 .data = &tcp_timeouts[TCP_CONNTRACK_SYN_RECV],
1359 .maxlen = sizeof(unsigned int),
1360 .mode = 0644,
1361 .proc_handler = proc_dointvec_jiffies,
1362 },
1363 {
1364 .procname = "ip_conntrack_tcp_timeout_established",
1365 .data = &tcp_timeouts[TCP_CONNTRACK_ESTABLISHED],
1366 .maxlen = sizeof(unsigned int),
1367 .mode = 0644,
1368 .proc_handler = proc_dointvec_jiffies,
1369 },
1370 {
1371 .procname = "ip_conntrack_tcp_timeout_fin_wait",
1372 .data = &tcp_timeouts[TCP_CONNTRACK_FIN_WAIT],
1373 .maxlen = sizeof(unsigned int),
1374 .mode = 0644,
1375 .proc_handler = proc_dointvec_jiffies,
1376 },
1377 {
1378 .procname = "ip_conntrack_tcp_timeout_close_wait",
1379 .data = &tcp_timeouts[TCP_CONNTRACK_CLOSE_WAIT],
1380 .maxlen = sizeof(unsigned int),
1381 .mode = 0644,
1382 .proc_handler = proc_dointvec_jiffies,
1383 },
1384 {
1385 .procname = "ip_conntrack_tcp_timeout_last_ack",
1386 .data = &tcp_timeouts[TCP_CONNTRACK_LAST_ACK],
1387 .maxlen = sizeof(unsigned int),
1388 .mode = 0644,
1389 .proc_handler = proc_dointvec_jiffies,
1390 },
1391 {
1392 .procname = "ip_conntrack_tcp_timeout_time_wait",
1393 .data = &tcp_timeouts[TCP_CONNTRACK_TIME_WAIT],
1394 .maxlen = sizeof(unsigned int),
1395 .mode = 0644,
1396 .proc_handler = proc_dointvec_jiffies,
1397 },
1398 {
1399 .procname = "ip_conntrack_tcp_timeout_close",
1400 .data = &tcp_timeouts[TCP_CONNTRACK_CLOSE],
1401 .maxlen = sizeof(unsigned int),
1402 .mode = 0644,
1403 .proc_handler = proc_dointvec_jiffies,
1404 },
1405 {
1406 .procname = "ip_conntrack_tcp_timeout_max_retrans",
1407 .data = &nf_ct_tcp_timeout_max_retrans,
1408 .maxlen = sizeof(unsigned int),
1409 .mode = 0644,
1410 .proc_handler = proc_dointvec_jiffies,
1411 },
1412 {
1413 .procname = "ip_conntrack_tcp_loose",
1414 .data = &nf_ct_tcp_loose,
1415 .maxlen = sizeof(unsigned int),
1416 .mode = 0644,
1417 .proc_handler = proc_dointvec,
1418 },
1419 {
1420 .procname = "ip_conntrack_tcp_be_liberal",
1421 .data = &nf_ct_tcp_be_liberal,
1422 .maxlen = sizeof(unsigned int),
1423 .mode = 0644,
1424 .proc_handler = proc_dointvec,
1425 },
1426 {
1427 .procname = "ip_conntrack_tcp_max_retrans",
1428 .data = &nf_ct_tcp_max_retrans,
1429 .maxlen = sizeof(unsigned int),
1430 .mode = 0644,
1431 .proc_handler = proc_dointvec,
1432 },
1433 { }
1434 };
1435 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
1436 #endif /* CONFIG_SYSCTL */
1437
1438 struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp4 __read_mostly =
1439 {
1440 .l3proto = PF_INET,
1441 .l4proto = IPPROTO_TCP,
1442 .name = "tcp",
1443 .pkt_to_tuple = tcp_pkt_to_tuple,
1444 .invert_tuple = tcp_invert_tuple,
1445 .print_tuple = tcp_print_tuple,
1446 .print_conntrack = tcp_print_conntrack,
1447 .packet = tcp_packet,
1448 .new = tcp_new,
1449 .error = tcp_error,
1450 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1451 .to_nlattr = tcp_to_nlattr,
1452 .nlattr_size = tcp_nlattr_size,
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 .nla_policy = nf_ct_port_nla_policy,
1458 #endif
1459 #ifdef CONFIG_SYSCTL
1460 .ctl_table_users = &tcp_sysctl_table_users,
1461 .ctl_table_header = &tcp_sysctl_header,
1462 .ctl_table = tcp_sysctl_table,
1463 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
1464 .ctl_compat_table = tcp_compat_sysctl_table,
1465 #endif
1466 #endif
1467 };
1468 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_tcp4);
1469
1470 struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp6 __read_mostly =
1471 {
1472 .l3proto = PF_INET6,
1473 .l4proto = IPPROTO_TCP,
1474 .name = "tcp",
1475 .pkt_to_tuple = tcp_pkt_to_tuple,
1476 .invert_tuple = tcp_invert_tuple,
1477 .print_tuple = tcp_print_tuple,
1478 .print_conntrack = tcp_print_conntrack,
1479 .packet = tcp_packet,
1480 .new = tcp_new,
1481 .error = tcp_error,
1482 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1483 .to_nlattr = tcp_to_nlattr,
1484 .nlattr_size = tcp_nlattr_size,
1485 .from_nlattr = nlattr_to_tcp,
1486 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
1487 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
1488 .nlattr_tuple_size = tcp_nlattr_tuple_size,
1489 .nla_policy = nf_ct_port_nla_policy,
1490 #endif
1491 #ifdef CONFIG_SYSCTL
1492 .ctl_table_users = &tcp_sysctl_table_users,
1493 .ctl_table_header = &tcp_sysctl_header,
1494 .ctl_table = tcp_sysctl_table,
1495 #endif
1496 };
1497 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_tcp6);
1498