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9fb9cbb1 YK |
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 | * Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>: | |
9 | * - Real stateful connection tracking | |
10 | * - Modified state transitions table | |
11 | * - Window scaling support added | |
12 | * - SACK support added | |
13 | * | |
14 | * Willy Tarreau: | |
15 | * - State table bugfixes | |
16 | * - More robust state changes | |
17 | * - Tuning timer parameters | |
18 | * | |
19 | * 27 Oct 2004: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp> | |
20 | * - genelized Layer 3 protocol part. | |
21 | * | |
22 | * Derived from net/ipv4/netfilter/ip_conntrack_proto_tcp.c | |
23 | * | |
24 | * version 2.2 | |
25 | */ | |
26 | ||
9fb9cbb1 YK |
27 | #include <linux/types.h> |
28 | #include <linux/sched.h> | |
29 | #include <linux/timer.h> | |
30 | #include <linux/netfilter.h> | |
31 | #include <linux/module.h> | |
32 | #include <linux/in.h> | |
33 | #include <linux/tcp.h> | |
34 | #include <linux/spinlock.h> | |
35 | #include <linux/skbuff.h> | |
36 | #include <linux/ipv6.h> | |
37 | #include <net/ip6_checksum.h> | |
38 | ||
39 | #include <net/tcp.h> | |
40 | ||
41 | #include <linux/netfilter.h> | |
42 | #include <linux/netfilter_ipv4.h> | |
43 | #include <linux/netfilter_ipv6.h> | |
44 | #include <net/netfilter/nf_conntrack.h> | |
45 | #include <net/netfilter/nf_conntrack_protocol.h> | |
f6180121 | 46 | #include <net/netfilter/nf_conntrack_ecache.h> |
9fb9cbb1 YK |
47 | |
48 | #if 0 | |
49 | #define DEBUGP printk | |
50 | #define DEBUGP_VARS | |
51 | #else | |
52 | #define DEBUGP(format, args...) | |
53 | #endif | |
54 | ||
55 | /* Protects conntrack->proto.tcp */ | |
56 | static DEFINE_RWLOCK(tcp_lock); | |
57 | ||
58 | /* "Be conservative in what you do, | |
59 | be liberal in what you accept from others." | |
60 | If it's non-zero, we mark only out of window RST segments as INVALID. */ | |
94aec08e | 61 | int nf_ct_tcp_be_liberal __read_mostly = 0; |
9fb9cbb1 YK |
62 | |
63 | /* When connection is picked up from the middle, how many packets are required | |
64 | to pass in each direction when we assume we are in sync - if any side uses | |
65 | window scaling, we lost the game. | |
66 | If it is set to zero, we disable picking up already established | |
67 | connections. */ | |
94aec08e | 68 | int nf_ct_tcp_loose __read_mostly = 3; |
9fb9cbb1 YK |
69 | |
70 | /* Max number of the retransmitted packets without receiving an (acceptable) | |
71 | ACK from the destination. If this number is reached, a shorter timer | |
72 | will be started. */ | |
94aec08e | 73 | int nf_ct_tcp_max_retrans __read_mostly = 3; |
9fb9cbb1 YK |
74 | |
75 | /* FIXME: Examine ipfilter's timeouts and conntrack transitions more | |
76 | closely. They're more complex. --RR */ | |
77 | ||
78 | static const char *tcp_conntrack_names[] = { | |
79 | "NONE", | |
80 | "SYN_SENT", | |
81 | "SYN_RECV", | |
82 | "ESTABLISHED", | |
83 | "FIN_WAIT", | |
84 | "CLOSE_WAIT", | |
85 | "LAST_ACK", | |
86 | "TIME_WAIT", | |
87 | "CLOSE", | |
88 | "LISTEN" | |
89 | }; | |
90 | ||
91 | #define SECS * HZ | |
92 | #define MINS * 60 SECS | |
93 | #define HOURS * 60 MINS | |
94 | #define DAYS * 24 HOURS | |
95 | ||
94aec08e BH |
96 | unsigned int nf_ct_tcp_timeout_syn_sent __read_mostly = 2 MINS; |
97 | unsigned int nf_ct_tcp_timeout_syn_recv __read_mostly = 60 SECS; | |
98 | unsigned int nf_ct_tcp_timeout_established __read_mostly = 5 DAYS; | |
99 | unsigned int nf_ct_tcp_timeout_fin_wait __read_mostly = 2 MINS; | |
100 | unsigned int nf_ct_tcp_timeout_close_wait __read_mostly = 60 SECS; | |
101 | unsigned int nf_ct_tcp_timeout_last_ack __read_mostly = 30 SECS; | |
102 | unsigned int nf_ct_tcp_timeout_time_wait __read_mostly = 2 MINS; | |
103 | unsigned int nf_ct_tcp_timeout_close __read_mostly = 10 SECS; | |
9fb9cbb1 YK |
104 | |
105 | /* RFC1122 says the R2 limit should be at least 100 seconds. | |
106 | Linux uses 15 packets as limit, which corresponds | |
107 | to ~13-30min depending on RTO. */ | |
94aec08e | 108 | unsigned int nf_ct_tcp_timeout_max_retrans __read_mostly = 5 MINS; |
9fb9cbb1 | 109 | |
babbdb1a | 110 | static unsigned int * tcp_timeouts[] |
9fb9cbb1 YK |
111 | = { NULL, /* TCP_CONNTRACK_NONE */ |
112 | &nf_ct_tcp_timeout_syn_sent, /* TCP_CONNTRACK_SYN_SENT, */ | |
113 | &nf_ct_tcp_timeout_syn_recv, /* TCP_CONNTRACK_SYN_RECV, */ | |
114 | &nf_ct_tcp_timeout_established, /* TCP_CONNTRACK_ESTABLISHED, */ | |
115 | &nf_ct_tcp_timeout_fin_wait, /* TCP_CONNTRACK_FIN_WAIT, */ | |
116 | &nf_ct_tcp_timeout_close_wait, /* TCP_CONNTRACK_CLOSE_WAIT, */ | |
117 | &nf_ct_tcp_timeout_last_ack, /* TCP_CONNTRACK_LAST_ACK, */ | |
118 | &nf_ct_tcp_timeout_time_wait, /* TCP_CONNTRACK_TIME_WAIT, */ | |
119 | &nf_ct_tcp_timeout_close, /* TCP_CONNTRACK_CLOSE, */ | |
120 | NULL, /* TCP_CONNTRACK_LISTEN */ | |
121 | }; | |
122 | ||
123 | #define sNO TCP_CONNTRACK_NONE | |
124 | #define sSS TCP_CONNTRACK_SYN_SENT | |
125 | #define sSR TCP_CONNTRACK_SYN_RECV | |
126 | #define sES TCP_CONNTRACK_ESTABLISHED | |
127 | #define sFW TCP_CONNTRACK_FIN_WAIT | |
128 | #define sCW TCP_CONNTRACK_CLOSE_WAIT | |
129 | #define sLA TCP_CONNTRACK_LAST_ACK | |
130 | #define sTW TCP_CONNTRACK_TIME_WAIT | |
131 | #define sCL TCP_CONNTRACK_CLOSE | |
132 | #define sLI TCP_CONNTRACK_LISTEN | |
133 | #define sIV TCP_CONNTRACK_MAX | |
134 | #define sIG TCP_CONNTRACK_IGNORE | |
135 | ||
136 | /* What TCP flags are set from RST/SYN/FIN/ACK. */ | |
137 | enum tcp_bit_set { | |
138 | TCP_SYN_SET, | |
139 | TCP_SYNACK_SET, | |
140 | TCP_FIN_SET, | |
141 | TCP_ACK_SET, | |
142 | TCP_RST_SET, | |
143 | TCP_NONE_SET, | |
144 | }; | |
145 | ||
146 | /* | |
147 | * The TCP state transition table needs a few words... | |
148 | * | |
149 | * We are the man in the middle. All the packets go through us | |
150 | * but might get lost in transit to the destination. | |
151 | * It is assumed that the destinations can't receive segments | |
152 | * we haven't seen. | |
153 | * | |
154 | * The checked segment is in window, but our windows are *not* | |
155 | * equivalent with the ones of the sender/receiver. We always | |
156 | * try to guess the state of the current sender. | |
157 | * | |
158 | * The meaning of the states are: | |
159 | * | |
160 | * NONE: initial state | |
161 | * SYN_SENT: SYN-only packet seen | |
162 | * SYN_RECV: SYN-ACK packet seen | |
163 | * ESTABLISHED: ACK packet seen | |
164 | * FIN_WAIT: FIN packet seen | |
165 | * CLOSE_WAIT: ACK seen (after FIN) | |
166 | * LAST_ACK: FIN seen (after FIN) | |
167 | * TIME_WAIT: last ACK seen | |
168 | * CLOSE: closed connection | |
169 | * | |
170 | * LISTEN state is not used. | |
171 | * | |
172 | * Packets marked as IGNORED (sIG): | |
173 | * if they may be either invalid or valid | |
174 | * and the receiver may send back a connection | |
175 | * closing RST or a SYN/ACK. | |
176 | * | |
177 | * Packets marked as INVALID (sIV): | |
178 | * if they are invalid | |
179 | * or we do not support the request (simultaneous open) | |
180 | */ | |
181 | static enum tcp_conntrack tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = { | |
182 | { | |
183 | /* ORIGINAL */ | |
184 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ | |
185 | /*syn*/ { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sIV }, | |
186 | /* | |
187 | * sNO -> sSS Initialize a new connection | |
188 | * sSS -> sSS Retransmitted SYN | |
189 | * sSR -> sIG Late retransmitted SYN? | |
190 | * sES -> sIG Error: SYNs in window outside the SYN_SENT state | |
191 | * are errors. Receiver will reply with RST | |
192 | * and close the connection. | |
193 | * Or we are not in sync and hold a dead connection. | |
194 | * sFW -> sIG | |
195 | * sCW -> sIG | |
196 | * sLA -> sIG | |
197 | * sTW -> sSS Reopened connection (RFC 1122). | |
198 | * sCL -> sSS | |
199 | */ | |
200 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ | |
201 | /*synack*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }, | |
202 | /* | |
203 | * A SYN/ACK from the client is always invalid: | |
204 | * - either it tries to set up a simultaneous open, which is | |
205 | * not supported; | |
206 | * - or the firewall has just been inserted between the two hosts | |
207 | * during the session set-up. The SYN will be retransmitted | |
208 | * by the true client (or it'll time out). | |
209 | */ | |
210 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ | |
211 | /*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV }, | |
212 | /* | |
213 | * sNO -> sIV Too late and no reason to do anything... | |
214 | * sSS -> sIV Client migth not send FIN in this state: | |
215 | * we enforce waiting for a SYN/ACK reply first. | |
216 | * sSR -> sFW Close started. | |
217 | * sES -> sFW | |
218 | * sFW -> sLA FIN seen in both directions, waiting for | |
219 | * the last ACK. | |
220 | * Migth be a retransmitted FIN as well... | |
221 | * sCW -> sLA | |
222 | * sLA -> sLA Retransmitted FIN. Remain in the same state. | |
223 | * sTW -> sTW | |
224 | * sCL -> sCL | |
225 | */ | |
226 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ | |
227 | /*ack*/ { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV }, | |
228 | /* | |
229 | * sNO -> sES Assumed. | |
230 | * sSS -> sIV ACK is invalid: we haven't seen a SYN/ACK yet. | |
231 | * sSR -> sES Established state is reached. | |
232 | * sES -> sES :-) | |
233 | * sFW -> sCW Normal close request answered by ACK. | |
234 | * sCW -> sCW | |
235 | * sLA -> sTW Last ACK detected. | |
236 | * sTW -> sTW Retransmitted last ACK. Remain in the same state. | |
237 | * sCL -> sCL | |
238 | */ | |
239 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ | |
240 | /*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sIV }, | |
241 | /*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV } | |
242 | }, | |
243 | { | |
244 | /* REPLY */ | |
245 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ | |
246 | /*syn*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }, | |
247 | /* | |
248 | * sNO -> sIV Never reached. | |
249 | * sSS -> sIV Simultaneous open, not supported | |
250 | * sSR -> sIV Simultaneous open, not supported. | |
251 | * sES -> sIV Server may not initiate a connection. | |
252 | * sFW -> sIV | |
253 | * sCW -> sIV | |
254 | * sLA -> sIV | |
255 | * sTW -> sIV Reopened connection, but server may not do it. | |
256 | * sCL -> sIV | |
257 | */ | |
258 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ | |
259 | /*synack*/ { sIV, sSR, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIV }, | |
260 | /* | |
261 | * sSS -> sSR Standard open. | |
262 | * sSR -> sSR Retransmitted SYN/ACK. | |
263 | * sES -> sIG Late retransmitted SYN/ACK? | |
264 | * sFW -> sIG Might be SYN/ACK answering ignored SYN | |
265 | * sCW -> sIG | |
266 | * sLA -> sIG | |
267 | * sTW -> sIG | |
268 | * sCL -> sIG | |
269 | */ | |
270 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ | |
271 | /*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV }, | |
272 | /* | |
273 | * sSS -> sIV Server might not send FIN in this state. | |
274 | * sSR -> sFW Close started. | |
275 | * sES -> sFW | |
276 | * sFW -> sLA FIN seen in both directions. | |
277 | * sCW -> sLA | |
278 | * sLA -> sLA Retransmitted FIN. | |
279 | * sTW -> sTW | |
280 | * sCL -> sCL | |
281 | */ | |
282 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ | |
73f30602 | 283 | /*ack*/ { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIV }, |
9fb9cbb1 | 284 | /* |
73f30602 | 285 | * sSS -> sIG Might be a half-open connection. |
9fb9cbb1 YK |
286 | * sSR -> sSR Might answer late resent SYN. |
287 | * sES -> sES :-) | |
288 | * sFW -> sCW Normal close request answered by ACK. | |
289 | * sCW -> sCW | |
290 | * sLA -> sTW Last ACK detected. | |
291 | * sTW -> sTW Retransmitted last ACK. | |
292 | * sCL -> sCL | |
293 | */ | |
294 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ | |
295 | /*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sIV }, | |
296 | /*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV } | |
297 | } | |
298 | }; | |
299 | ||
300 | static int tcp_pkt_to_tuple(const struct sk_buff *skb, | |
301 | unsigned int dataoff, | |
302 | struct nf_conntrack_tuple *tuple) | |
303 | { | |
304 | struct tcphdr _hdr, *hp; | |
305 | ||
306 | /* Actually only need first 8 bytes. */ | |
307 | hp = skb_header_pointer(skb, dataoff, 8, &_hdr); | |
308 | if (hp == NULL) | |
309 | return 0; | |
310 | ||
311 | tuple->src.u.tcp.port = hp->source; | |
312 | tuple->dst.u.tcp.port = hp->dest; | |
313 | ||
314 | return 1; | |
315 | } | |
316 | ||
317 | static int tcp_invert_tuple(struct nf_conntrack_tuple *tuple, | |
318 | const struct nf_conntrack_tuple *orig) | |
319 | { | |
320 | tuple->src.u.tcp.port = orig->dst.u.tcp.port; | |
321 | tuple->dst.u.tcp.port = orig->src.u.tcp.port; | |
322 | return 1; | |
323 | } | |
324 | ||
325 | /* Print out the per-protocol part of the tuple. */ | |
326 | static int tcp_print_tuple(struct seq_file *s, | |
327 | const struct nf_conntrack_tuple *tuple) | |
328 | { | |
329 | return seq_printf(s, "sport=%hu dport=%hu ", | |
330 | ntohs(tuple->src.u.tcp.port), | |
331 | ntohs(tuple->dst.u.tcp.port)); | |
332 | } | |
333 | ||
334 | /* Print out the private part of the conntrack. */ | |
335 | static int tcp_print_conntrack(struct seq_file *s, | |
336 | const struct nf_conn *conntrack) | |
337 | { | |
338 | enum tcp_conntrack state; | |
339 | ||
340 | read_lock_bh(&tcp_lock); | |
341 | state = conntrack->proto.tcp.state; | |
342 | read_unlock_bh(&tcp_lock); | |
343 | ||
344 | return seq_printf(s, "%s ", tcp_conntrack_names[state]); | |
345 | } | |
346 | ||
347 | static unsigned int get_conntrack_index(const struct tcphdr *tcph) | |
348 | { | |
349 | if (tcph->rst) return TCP_RST_SET; | |
350 | else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET); | |
351 | else if (tcph->fin) return TCP_FIN_SET; | |
352 | else if (tcph->ack) return TCP_ACK_SET; | |
353 | else return TCP_NONE_SET; | |
354 | } | |
355 | ||
356 | /* TCP connection tracking based on 'Real Stateful TCP Packet Filtering | |
357 | in IP Filter' by Guido van Rooij. | |
358 | ||
359 | http://www.nluug.nl/events/sane2000/papers.html | |
360 | http://www.iae.nl/users/guido/papers/tcp_filtering.ps.gz | |
361 | ||
362 | The boundaries and the conditions are changed according to RFC793: | |
363 | the packet must intersect the window (i.e. segments may be | |
364 | after the right or before the left edge) and thus receivers may ACK | |
365 | segments after the right edge of the window. | |
366 | ||
367 | td_maxend = max(sack + max(win,1)) seen in reply packets | |
368 | td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets | |
369 | td_maxwin += seq + len - sender.td_maxend | |
370 | if seq + len > sender.td_maxend | |
371 | td_end = max(seq + len) seen in sent packets | |
372 | ||
373 | I. Upper bound for valid data: seq <= sender.td_maxend | |
374 | II. Lower bound for valid data: seq + len >= sender.td_end - receiver.td_maxwin | |
375 | III. Upper bound for valid ack: sack <= receiver.td_end | |
376 | IV. Lower bound for valid ack: ack >= receiver.td_end - MAXACKWINDOW | |
377 | ||
378 | where sack is the highest right edge of sack block found in the packet. | |
379 | ||
380 | The upper bound limit for a valid ack is not ignored - | |
381 | we doesn't have to deal with fragments. | |
382 | */ | |
383 | ||
384 | static inline __u32 segment_seq_plus_len(__u32 seq, | |
385 | size_t len, | |
386 | unsigned int dataoff, | |
387 | struct tcphdr *tcph) | |
388 | { | |
389 | /* XXX Should I use payload length field in IP/IPv6 header ? | |
390 | * - YK */ | |
391 | return (seq + len - dataoff - tcph->doff*4 | |
392 | + (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0)); | |
393 | } | |
394 | ||
395 | /* Fixme: what about big packets? */ | |
396 | #define MAXACKWINCONST 66000 | |
397 | #define MAXACKWINDOW(sender) \ | |
398 | ((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin \ | |
399 | : MAXACKWINCONST) | |
400 | ||
401 | /* | |
402 | * Simplified tcp_parse_options routine from tcp_input.c | |
403 | */ | |
404 | static void tcp_options(const struct sk_buff *skb, | |
405 | unsigned int dataoff, | |
406 | struct tcphdr *tcph, | |
407 | struct ip_ct_tcp_state *state) | |
408 | { | |
409 | unsigned char buff[(15 * 4) - sizeof(struct tcphdr)]; | |
410 | unsigned char *ptr; | |
411 | int length = (tcph->doff*4) - sizeof(struct tcphdr); | |
412 | ||
413 | if (!length) | |
414 | return; | |
415 | ||
416 | ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr), | |
417 | length, buff); | |
418 | BUG_ON(ptr == NULL); | |
419 | ||
420 | state->td_scale = | |
421 | state->flags = 0; | |
422 | ||
423 | while (length > 0) { | |
424 | int opcode=*ptr++; | |
425 | int opsize; | |
426 | ||
427 | switch (opcode) { | |
428 | case TCPOPT_EOL: | |
429 | return; | |
430 | case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */ | |
431 | length--; | |
432 | continue; | |
433 | default: | |
434 | opsize=*ptr++; | |
435 | if (opsize < 2) /* "silly options" */ | |
436 | return; | |
437 | if (opsize > length) | |
438 | break; /* don't parse partial options */ | |
439 | ||
440 | if (opcode == TCPOPT_SACK_PERM | |
441 | && opsize == TCPOLEN_SACK_PERM) | |
442 | state->flags |= IP_CT_TCP_FLAG_SACK_PERM; | |
443 | else if (opcode == TCPOPT_WINDOW | |
444 | && opsize == TCPOLEN_WINDOW) { | |
445 | state->td_scale = *(u_int8_t *)ptr; | |
446 | ||
447 | if (state->td_scale > 14) { | |
448 | /* See RFC1323 */ | |
449 | state->td_scale = 14; | |
450 | } | |
451 | state->flags |= | |
452 | IP_CT_TCP_FLAG_WINDOW_SCALE; | |
453 | } | |
454 | ptr += opsize - 2; | |
455 | length -= opsize; | |
456 | } | |
457 | } | |
458 | } | |
459 | ||
460 | static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff, | |
461 | struct tcphdr *tcph, __u32 *sack) | |
462 | { | |
463 | unsigned char buff[(15 * 4) - sizeof(struct tcphdr)]; | |
464 | unsigned char *ptr; | |
465 | int length = (tcph->doff*4) - sizeof(struct tcphdr); | |
466 | __u32 tmp; | |
467 | ||
468 | if (!length) | |
469 | return; | |
470 | ||
471 | ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr), | |
472 | length, buff); | |
473 | BUG_ON(ptr == NULL); | |
474 | ||
475 | /* Fast path for timestamp-only option */ | |
476 | if (length == TCPOLEN_TSTAMP_ALIGNED*4 | |
477 | && *(__u32 *)ptr == | |
478 | __constant_ntohl((TCPOPT_NOP << 24) | |
479 | | (TCPOPT_NOP << 16) | |
480 | | (TCPOPT_TIMESTAMP << 8) | |
481 | | TCPOLEN_TIMESTAMP)) | |
482 | return; | |
483 | ||
484 | while (length > 0) { | |
485 | int opcode = *ptr++; | |
486 | int opsize, i; | |
487 | ||
488 | switch (opcode) { | |
489 | case TCPOPT_EOL: | |
490 | return; | |
491 | case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */ | |
492 | length--; | |
493 | continue; | |
494 | default: | |
495 | opsize = *ptr++; | |
496 | if (opsize < 2) /* "silly options" */ | |
497 | return; | |
498 | if (opsize > length) | |
499 | break; /* don't parse partial options */ | |
500 | ||
501 | if (opcode == TCPOPT_SACK | |
502 | && opsize >= (TCPOLEN_SACK_BASE | |
503 | + TCPOLEN_SACK_PERBLOCK) | |
504 | && !((opsize - TCPOLEN_SACK_BASE) | |
505 | % TCPOLEN_SACK_PERBLOCK)) { | |
506 | for (i = 0; | |
507 | i < (opsize - TCPOLEN_SACK_BASE); | |
508 | i += TCPOLEN_SACK_PERBLOCK) { | |
509 | memcpy(&tmp, (__u32 *)(ptr + i) + 1, | |
510 | sizeof(__u32)); | |
511 | tmp = ntohl(tmp); | |
512 | ||
513 | if (after(tmp, *sack)) | |
514 | *sack = tmp; | |
515 | } | |
516 | return; | |
517 | } | |
518 | ptr += opsize - 2; | |
519 | length -= opsize; | |
520 | } | |
521 | } | |
522 | } | |
523 | ||
524 | static int tcp_in_window(struct ip_ct_tcp *state, | |
525 | enum ip_conntrack_dir dir, | |
526 | unsigned int index, | |
527 | const struct sk_buff *skb, | |
528 | unsigned int dataoff, | |
529 | struct tcphdr *tcph, | |
530 | int pf) | |
531 | { | |
532 | struct ip_ct_tcp_state *sender = &state->seen[dir]; | |
533 | struct ip_ct_tcp_state *receiver = &state->seen[!dir]; | |
534 | __u32 seq, ack, sack, end, win, swin; | |
535 | int res; | |
536 | ||
537 | /* | |
538 | * Get the required data from the packet. | |
539 | */ | |
540 | seq = ntohl(tcph->seq); | |
541 | ack = sack = ntohl(tcph->ack_seq); | |
542 | win = ntohs(tcph->window); | |
543 | end = segment_seq_plus_len(seq, skb->len, dataoff, tcph); | |
544 | ||
545 | if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM) | |
546 | tcp_sack(skb, dataoff, tcph, &sack); | |
547 | ||
548 | DEBUGP("tcp_in_window: START\n"); | |
549 | DEBUGP("tcp_in_window: src=%u.%u.%u.%u:%hu dst=%u.%u.%u.%u:%hu " | |
550 | "seq=%u ack=%u sack=%u win=%u end=%u\n", | |
551 | NIPQUAD(iph->saddr), ntohs(tcph->source), | |
552 | NIPQUAD(iph->daddr), ntohs(tcph->dest), | |
553 | seq, ack, sack, win, end); | |
554 | DEBUGP("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i " | |
555 | "receiver end=%u maxend=%u maxwin=%u scale=%i\n", | |
556 | sender->td_end, sender->td_maxend, sender->td_maxwin, | |
557 | sender->td_scale, | |
558 | receiver->td_end, receiver->td_maxend, receiver->td_maxwin, | |
559 | receiver->td_scale); | |
560 | ||
561 | if (sender->td_end == 0) { | |
562 | /* | |
563 | * Initialize sender data. | |
564 | */ | |
565 | if (tcph->syn && tcph->ack) { | |
566 | /* | |
567 | * Outgoing SYN-ACK in reply to a SYN. | |
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 | * RFC 1323: | |
576 | * Both sides must send the Window Scale option | |
577 | * to enable window scaling in either direction. | |
578 | */ | |
579 | if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE | |
580 | && receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE)) | |
581 | sender->td_scale = | |
582 | receiver->td_scale = 0; | |
583 | } else { | |
584 | /* | |
585 | * We are in the middle of a connection, | |
586 | * its history is lost for us. | |
587 | * Let's try to use the data from the packet. | |
588 | */ | |
589 | sender->td_end = end; | |
590 | sender->td_maxwin = (win == 0 ? 1 : win); | |
591 | sender->td_maxend = end + sender->td_maxwin; | |
592 | } | |
593 | } else if (((state->state == TCP_CONNTRACK_SYN_SENT | |
594 | && dir == IP_CT_DIR_ORIGINAL) | |
595 | || (state->state == TCP_CONNTRACK_SYN_RECV | |
596 | && dir == IP_CT_DIR_REPLY)) | |
597 | && after(end, sender->td_end)) { | |
598 | /* | |
599 | * RFC 793: "if a TCP is reinitialized ... then it need | |
600 | * not wait at all; it must only be sure to use sequence | |
601 | * numbers larger than those recently used." | |
602 | */ | |
603 | sender->td_end = | |
604 | sender->td_maxend = end; | |
605 | sender->td_maxwin = (win == 0 ? 1 : win); | |
606 | ||
607 | tcp_options(skb, dataoff, tcph, sender); | |
608 | } | |
609 | ||
610 | if (!(tcph->ack)) { | |
611 | /* | |
612 | * If there is no ACK, just pretend it was set and OK. | |
613 | */ | |
614 | ack = sack = receiver->td_end; | |
615 | } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) == | |
616 | (TCP_FLAG_ACK|TCP_FLAG_RST)) | |
617 | && (ack == 0)) { | |
618 | /* | |
619 | * Broken TCP stacks, that set ACK in RST packets as well | |
620 | * with zero ack value. | |
621 | */ | |
622 | ack = sack = receiver->td_end; | |
623 | } | |
624 | ||
625 | if (seq == end | |
626 | && (!tcph->rst | |
627 | || (seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT))) | |
628 | /* | |
629 | * Packets contains no data: we assume it is valid | |
630 | * and check the ack value only. | |
631 | * However RST segments are always validated by their | |
632 | * SEQ number, except when seq == 0 (reset sent answering | |
633 | * SYN. | |
634 | */ | |
635 | seq = end = sender->td_end; | |
636 | ||
637 | DEBUGP("tcp_in_window: src=%u.%u.%u.%u:%hu dst=%u.%u.%u.%u:%hu " | |
638 | "seq=%u ack=%u sack =%u win=%u end=%u\n", | |
639 | NIPQUAD(iph->saddr), ntohs(tcph->source), | |
640 | NIPQUAD(iph->daddr), ntohs(tcph->dest), | |
641 | seq, ack, sack, win, end); | |
642 | DEBUGP("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i " | |
643 | "receiver end=%u maxend=%u maxwin=%u scale=%i\n", | |
644 | sender->td_end, sender->td_maxend, sender->td_maxwin, | |
645 | sender->td_scale, | |
646 | receiver->td_end, receiver->td_maxend, receiver->td_maxwin, | |
647 | receiver->td_scale); | |
648 | ||
649 | DEBUGP("tcp_in_window: I=%i II=%i III=%i IV=%i\n", | |
650 | before(seq, sender->td_maxend + 1), | |
651 | after(end, sender->td_end - receiver->td_maxwin - 1), | |
652 | before(sack, receiver->td_end + 1), | |
653 | after(ack, receiver->td_end - MAXACKWINDOW(sender))); | |
654 | ||
655 | if (sender->loose || receiver->loose || | |
656 | (before(seq, sender->td_maxend + 1) && | |
657 | after(end, sender->td_end - receiver->td_maxwin - 1) && | |
658 | before(sack, receiver->td_end + 1) && | |
659 | after(ack, receiver->td_end - MAXACKWINDOW(sender)))) { | |
660 | /* | |
661 | * Take into account window scaling (RFC 1323). | |
662 | */ | |
663 | if (!tcph->syn) | |
664 | win <<= sender->td_scale; | |
665 | ||
666 | /* | |
667 | * Update sender data. | |
668 | */ | |
669 | swin = win + (sack - ack); | |
670 | if (sender->td_maxwin < swin) | |
671 | sender->td_maxwin = swin; | |
672 | if (after(end, sender->td_end)) | |
673 | sender->td_end = end; | |
674 | /* | |
675 | * Update receiver data. | |
676 | */ | |
677 | if (after(end, sender->td_maxend)) | |
678 | receiver->td_maxwin += end - sender->td_maxend; | |
679 | if (after(sack + win, receiver->td_maxend - 1)) { | |
680 | receiver->td_maxend = sack + win; | |
681 | if (win == 0) | |
682 | receiver->td_maxend++; | |
683 | } | |
684 | ||
685 | /* | |
686 | * Check retransmissions. | |
687 | */ | |
688 | if (index == TCP_ACK_SET) { | |
689 | if (state->last_dir == dir | |
690 | && state->last_seq == seq | |
691 | && state->last_ack == ack | |
c1fe3ca5 GH |
692 | && state->last_end == end |
693 | && state->last_win == win) | |
9fb9cbb1 YK |
694 | state->retrans++; |
695 | else { | |
696 | state->last_dir = dir; | |
697 | state->last_seq = seq; | |
698 | state->last_ack = ack; | |
699 | state->last_end = end; | |
c1fe3ca5 | 700 | state->last_win = win; |
9fb9cbb1 YK |
701 | state->retrans = 0; |
702 | } | |
703 | } | |
704 | /* | |
705 | * Close the window of disabled window tracking :-) | |
706 | */ | |
707 | if (sender->loose) | |
708 | sender->loose--; | |
709 | ||
710 | res = 1; | |
711 | } else { | |
712 | if (LOG_INVALID(IPPROTO_TCP)) | |
713 | nf_log_packet(pf, 0, skb, NULL, NULL, NULL, | |
714 | "nf_ct_tcp: %s ", | |
715 | before(seq, sender->td_maxend + 1) ? | |
716 | after(end, sender->td_end - receiver->td_maxwin - 1) ? | |
717 | before(sack, receiver->td_end + 1) ? | |
718 | after(ack, receiver->td_end - MAXACKWINDOW(sender)) ? "BUG" | |
719 | : "ACK is under the lower bound (possible overly delayed ACK)" | |
720 | : "ACK is over the upper bound (ACKed data not seen yet)" | |
721 | : "SEQ is under the lower bound (already ACKed data retransmitted)" | |
722 | : "SEQ is over the upper bound (over the window of the receiver)"); | |
723 | ||
724 | res = nf_ct_tcp_be_liberal; | |
725 | } | |
726 | ||
727 | DEBUGP("tcp_in_window: res=%i sender end=%u maxend=%u maxwin=%u " | |
728 | "receiver end=%u maxend=%u maxwin=%u\n", | |
729 | res, sender->td_end, sender->td_maxend, sender->td_maxwin, | |
730 | receiver->td_end, receiver->td_maxend, receiver->td_maxwin); | |
731 | ||
732 | return res; | |
733 | } | |
734 | ||
735 | #ifdef CONFIG_IP_NF_NAT_NEEDED | |
736 | /* Update sender->td_end after NAT successfully mangled the packet */ | |
737 | /* Caller must linearize skb at tcp header. */ | |
738 | void nf_conntrack_tcp_update(struct sk_buff *skb, | |
739 | unsigned int dataoff, | |
740 | struct nf_conn *conntrack, | |
741 | int dir) | |
742 | { | |
743 | struct tcphdr *tcph = (void *)skb->data + dataoff; | |
744 | __u32 end; | |
745 | #ifdef DEBUGP_VARS | |
746 | struct ip_ct_tcp_state *sender = &conntrack->proto.tcp.seen[dir]; | |
747 | struct ip_ct_tcp_state *receiver = &conntrack->proto.tcp.seen[!dir]; | |
748 | #endif | |
749 | ||
750 | end = segment_seq_plus_len(ntohl(tcph->seq), skb->len, dataoff, tcph); | |
751 | ||
752 | write_lock_bh(&tcp_lock); | |
753 | /* | |
754 | * We have to worry for the ack in the reply packet only... | |
755 | */ | |
756 | if (after(end, conntrack->proto.tcp.seen[dir].td_end)) | |
757 | conntrack->proto.tcp.seen[dir].td_end = end; | |
758 | conntrack->proto.tcp.last_end = end; | |
759 | write_unlock_bh(&tcp_lock); | |
760 | DEBUGP("tcp_update: sender end=%u maxend=%u maxwin=%u scale=%i " | |
761 | "receiver end=%u maxend=%u maxwin=%u scale=%i\n", | |
762 | sender->td_end, sender->td_maxend, sender->td_maxwin, | |
763 | sender->td_scale, | |
764 | receiver->td_end, receiver->td_maxend, receiver->td_maxwin, | |
765 | receiver->td_scale); | |
766 | } | |
767 | ||
768 | #endif | |
769 | ||
770 | #define TH_FIN 0x01 | |
771 | #define TH_SYN 0x02 | |
772 | #define TH_RST 0x04 | |
773 | #define TH_PUSH 0x08 | |
774 | #define TH_ACK 0x10 | |
775 | #define TH_URG 0x20 | |
776 | #define TH_ECE 0x40 | |
777 | #define TH_CWR 0x80 | |
778 | ||
779 | /* table of valid flag combinations - ECE and CWR are always valid */ | |
780 | static u8 tcp_valid_flags[(TH_FIN|TH_SYN|TH_RST|TH_PUSH|TH_ACK|TH_URG) + 1] = | |
781 | { | |
782 | [TH_SYN] = 1, | |
783 | [TH_SYN|TH_ACK] = 1, | |
a2d7222f | 784 | [TH_SYN|TH_PUSH] = 1, |
9fb9cbb1 YK |
785 | [TH_SYN|TH_ACK|TH_PUSH] = 1, |
786 | [TH_RST] = 1, | |
787 | [TH_RST|TH_ACK] = 1, | |
788 | [TH_RST|TH_ACK|TH_PUSH] = 1, | |
789 | [TH_FIN|TH_ACK] = 1, | |
790 | [TH_ACK] = 1, | |
791 | [TH_ACK|TH_PUSH] = 1, | |
792 | [TH_ACK|TH_URG] = 1, | |
793 | [TH_ACK|TH_URG|TH_PUSH] = 1, | |
794 | [TH_FIN|TH_ACK|TH_PUSH] = 1, | |
795 | [TH_FIN|TH_ACK|TH_URG] = 1, | |
796 | [TH_FIN|TH_ACK|TH_URG|TH_PUSH] = 1, | |
797 | }; | |
798 | ||
799 | /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c. */ | |
800 | static int tcp_error(struct sk_buff *skb, | |
801 | unsigned int dataoff, | |
802 | enum ip_conntrack_info *ctinfo, | |
803 | int pf, | |
96f6bf82 | 804 | unsigned int hooknum) |
9fb9cbb1 YK |
805 | { |
806 | struct tcphdr _tcph, *th; | |
807 | unsigned int tcplen = skb->len - dataoff; | |
808 | u_int8_t tcpflags; | |
809 | ||
810 | /* Smaller that minimal TCP header? */ | |
811 | th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph); | |
812 | if (th == NULL) { | |
813 | if (LOG_INVALID(IPPROTO_TCP)) | |
814 | nf_log_packet(pf, 0, skb, NULL, NULL, NULL, | |
815 | "nf_ct_tcp: short packet "); | |
816 | return -NF_ACCEPT; | |
817 | } | |
818 | ||
819 | /* Not whole TCP header or malformed packet */ | |
820 | if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) { | |
821 | if (LOG_INVALID(IPPROTO_TCP)) | |
822 | nf_log_packet(pf, 0, skb, NULL, NULL, NULL, | |
823 | "nf_ct_tcp: truncated/malformed packet "); | |
824 | return -NF_ACCEPT; | |
825 | } | |
826 | ||
827 | /* Checksum invalid? Ignore. | |
828 | * We skip checking packets on the outgoing path | |
84fa7933 | 829 | * because the checksum is assumed to be correct. |
9fb9cbb1 YK |
830 | */ |
831 | /* FIXME: Source route IP option packets --RR */ | |
39a27a35 PM |
832 | if (nf_conntrack_checksum && |
833 | ((pf == PF_INET && hooknum == NF_IP_PRE_ROUTING) || | |
834 | (pf == PF_INET6 && hooknum == NF_IP6_PRE_ROUTING)) && | |
96f6bf82 | 835 | nf_checksum(skb, hooknum, dataoff, IPPROTO_TCP, pf)) { |
9fb9cbb1 YK |
836 | if (LOG_INVALID(IPPROTO_TCP)) |
837 | nf_log_packet(pf, 0, skb, NULL, NULL, NULL, | |
838 | "nf_ct_tcp: bad TCP checksum "); | |
839 | return -NF_ACCEPT; | |
840 | } | |
841 | ||
842 | /* Check TCP flags. */ | |
843 | tcpflags = (((u_int8_t *)th)[13] & ~(TH_ECE|TH_CWR)); | |
844 | if (!tcp_valid_flags[tcpflags]) { | |
845 | if (LOG_INVALID(IPPROTO_TCP)) | |
846 | nf_log_packet(pf, 0, skb, NULL, NULL, NULL, | |
847 | "nf_ct_tcp: invalid TCP flag combination "); | |
848 | return -NF_ACCEPT; | |
849 | } | |
850 | ||
851 | return NF_ACCEPT; | |
852 | } | |
853 | ||
9fb9cbb1 YK |
854 | /* Returns verdict for packet, or -1 for invalid. */ |
855 | static int tcp_packet(struct nf_conn *conntrack, | |
856 | const struct sk_buff *skb, | |
857 | unsigned int dataoff, | |
858 | enum ip_conntrack_info ctinfo, | |
859 | int pf, | |
860 | unsigned int hooknum) | |
861 | { | |
862 | enum tcp_conntrack new_state, old_state; | |
863 | enum ip_conntrack_dir dir; | |
864 | struct tcphdr *th, _tcph; | |
865 | unsigned long timeout; | |
866 | unsigned int index; | |
867 | ||
868 | th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph); | |
869 | BUG_ON(th == NULL); | |
870 | ||
871 | write_lock_bh(&tcp_lock); | |
872 | old_state = conntrack->proto.tcp.state; | |
873 | dir = CTINFO2DIR(ctinfo); | |
874 | index = get_conntrack_index(th); | |
875 | new_state = tcp_conntracks[dir][index][old_state]; | |
876 | ||
877 | switch (new_state) { | |
878 | case TCP_CONNTRACK_IGNORE: | |
73f30602 JK |
879 | /* Ignored packets: |
880 | * | |
881 | * a) SYN in ORIGINAL | |
882 | * b) SYN/ACK in REPLY | |
883 | * c) ACK in reply direction after initial SYN in original. | |
884 | */ | |
9fb9cbb1 YK |
885 | if (index == TCP_SYNACK_SET |
886 | && conntrack->proto.tcp.last_index == TCP_SYN_SET | |
887 | && conntrack->proto.tcp.last_dir != dir | |
888 | && ntohl(th->ack_seq) == | |
889 | conntrack->proto.tcp.last_end) { | |
890 | /* This SYN/ACK acknowledges a SYN that we earlier | |
891 | * ignored as invalid. This means that the client and | |
892 | * the server are both in sync, while the firewall is | |
893 | * not. We kill this session and block the SYN/ACK so | |
894 | * that the client cannot but retransmit its SYN and | |
895 | * thus initiate a clean new session. | |
896 | */ | |
897 | write_unlock_bh(&tcp_lock); | |
898 | if (LOG_INVALID(IPPROTO_TCP)) | |
899 | nf_log_packet(pf, 0, skb, NULL, NULL, NULL, | |
900 | "nf_ct_tcp: killing out of sync session "); | |
901 | if (del_timer(&conntrack->timeout)) | |
902 | conntrack->timeout.function((unsigned long) | |
903 | conntrack); | |
904 | return -NF_DROP; | |
905 | } | |
906 | conntrack->proto.tcp.last_index = index; | |
907 | conntrack->proto.tcp.last_dir = dir; | |
908 | conntrack->proto.tcp.last_seq = ntohl(th->seq); | |
909 | conntrack->proto.tcp.last_end = | |
910 | segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th); | |
911 | ||
912 | write_unlock_bh(&tcp_lock); | |
913 | if (LOG_INVALID(IPPROTO_TCP)) | |
914 | nf_log_packet(pf, 0, skb, NULL, NULL, NULL, | |
915 | "nf_ct_tcp: invalid packed ignored "); | |
916 | return NF_ACCEPT; | |
917 | case TCP_CONNTRACK_MAX: | |
918 | /* Invalid packet */ | |
919 | DEBUGP("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n", | |
920 | dir, get_conntrack_index(th), | |
921 | old_state); | |
922 | write_unlock_bh(&tcp_lock); | |
923 | if (LOG_INVALID(IPPROTO_TCP)) | |
924 | nf_log_packet(pf, 0, skb, NULL, NULL, NULL, | |
925 | "nf_ct_tcp: invalid state "); | |
926 | return -NF_ACCEPT; | |
927 | case TCP_CONNTRACK_SYN_SENT: | |
928 | if (old_state < TCP_CONNTRACK_TIME_WAIT) | |
929 | break; | |
930 | if ((conntrack->proto.tcp.seen[dir].flags & | |
931 | IP_CT_TCP_FLAG_CLOSE_INIT) | |
932 | || after(ntohl(th->seq), | |
933 | conntrack->proto.tcp.seen[dir].td_end)) { | |
934 | /* Attempt to reopen a closed connection. | |
935 | * Delete this connection and look up again. */ | |
936 | write_unlock_bh(&tcp_lock); | |
937 | if (del_timer(&conntrack->timeout)) | |
938 | conntrack->timeout.function((unsigned long) | |
939 | conntrack); | |
940 | return -NF_REPEAT; | |
3746a2b1 KK |
941 | } else { |
942 | write_unlock_bh(&tcp_lock); | |
943 | if (LOG_INVALID(IPPROTO_TCP)) | |
944 | nf_log_packet(pf, 0, skb, NULL, NULL, | |
945 | NULL, "nf_ct_tcp: invalid SYN"); | |
946 | return -NF_ACCEPT; | |
9fb9cbb1 YK |
947 | } |
948 | case TCP_CONNTRACK_CLOSE: | |
949 | if (index == TCP_RST_SET | |
73f30602 JK |
950 | && ((test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status) |
951 | && conntrack->proto.tcp.last_index == TCP_SYN_SET) | |
952 | || (!test_bit(IPS_ASSURED_BIT, &conntrack->status) | |
953 | && conntrack->proto.tcp.last_index == TCP_ACK_SET)) | |
9fb9cbb1 | 954 | && ntohl(th->ack_seq) == conntrack->proto.tcp.last_end) { |
93b1fae4 | 955 | /* RST sent to invalid SYN or ACK we had let through |
73f30602 JK |
956 | * at a) and c) above: |
957 | * | |
958 | * a) SYN was in window then | |
959 | * c) we hold a half-open connection. | |
960 | * | |
961 | * Delete our connection entry. | |
9fb9cbb1 | 962 | * We skip window checking, because packet might ACK |
73f30602 | 963 | * segments we ignored. */ |
9fb9cbb1 YK |
964 | goto in_window; |
965 | } | |
93b1fae4 | 966 | /* Just fall through */ |
9fb9cbb1 YK |
967 | default: |
968 | /* Keep compilers happy. */ | |
969 | break; | |
970 | } | |
971 | ||
972 | if (!tcp_in_window(&conntrack->proto.tcp, dir, index, | |
973 | skb, dataoff, th, pf)) { | |
974 | write_unlock_bh(&tcp_lock); | |
975 | return -NF_ACCEPT; | |
976 | } | |
977 | in_window: | |
978 | /* From now on we have got in-window packets */ | |
979 | conntrack->proto.tcp.last_index = index; | |
980 | ||
981 | DEBUGP("tcp_conntracks: src=%u.%u.%u.%u:%hu dst=%u.%u.%u.%u:%hu " | |
982 | "syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n", | |
983 | NIPQUAD(iph->saddr), ntohs(th->source), | |
984 | NIPQUAD(iph->daddr), ntohs(th->dest), | |
985 | (th->syn ? 1 : 0), (th->ack ? 1 : 0), | |
986 | (th->fin ? 1 : 0), (th->rst ? 1 : 0), | |
987 | old_state, new_state); | |
988 | ||
989 | conntrack->proto.tcp.state = new_state; | |
990 | if (old_state != new_state | |
991 | && (new_state == TCP_CONNTRACK_FIN_WAIT | |
992 | || new_state == TCP_CONNTRACK_CLOSE)) | |
993 | conntrack->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT; | |
994 | timeout = conntrack->proto.tcp.retrans >= nf_ct_tcp_max_retrans | |
995 | && *tcp_timeouts[new_state] > nf_ct_tcp_timeout_max_retrans | |
996 | ? nf_ct_tcp_timeout_max_retrans : *tcp_timeouts[new_state]; | |
997 | write_unlock_bh(&tcp_lock); | |
998 | ||
999 | nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb); | |
1000 | if (new_state != old_state) | |
1001 | nf_conntrack_event_cache(IPCT_PROTOINFO, skb); | |
1002 | ||
1003 | if (!test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) { | |
1004 | /* If only reply is a RST, we can consider ourselves not to | |
1005 | have an established connection: this is a fairly common | |
1006 | problem case, so we can delete the conntrack | |
1007 | immediately. --RR */ | |
1008 | if (th->rst) { | |
1009 | if (del_timer(&conntrack->timeout)) | |
1010 | conntrack->timeout.function((unsigned long) | |
1011 | conntrack); | |
1012 | return NF_ACCEPT; | |
1013 | } | |
1014 | } else if (!test_bit(IPS_ASSURED_BIT, &conntrack->status) | |
1015 | && (old_state == TCP_CONNTRACK_SYN_RECV | |
1016 | || old_state == TCP_CONNTRACK_ESTABLISHED) | |
1017 | && new_state == TCP_CONNTRACK_ESTABLISHED) { | |
1018 | /* Set ASSURED if we see see valid ack in ESTABLISHED | |
1019 | after SYN_RECV or a valid answer for a picked up | |
1020 | connection. */ | |
1021 | set_bit(IPS_ASSURED_BIT, &conntrack->status); | |
1022 | nf_conntrack_event_cache(IPCT_STATUS, skb); | |
1023 | } | |
1024 | nf_ct_refresh_acct(conntrack, ctinfo, skb, timeout); | |
1025 | ||
1026 | return NF_ACCEPT; | |
1027 | } | |
1028 | ||
1029 | /* Called when a new connection for this protocol found. */ | |
1030 | static int tcp_new(struct nf_conn *conntrack, | |
1031 | const struct sk_buff *skb, | |
1032 | unsigned int dataoff) | |
1033 | { | |
1034 | enum tcp_conntrack new_state; | |
1035 | struct tcphdr *th, _tcph; | |
1036 | #ifdef DEBUGP_VARS | |
1037 | struct ip_ct_tcp_state *sender = &conntrack->proto.tcp.seen[0]; | |
1038 | struct ip_ct_tcp_state *receiver = &conntrack->proto.tcp.seen[1]; | |
1039 | #endif | |
1040 | ||
1041 | th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph); | |
1042 | BUG_ON(th == NULL); | |
1043 | ||
1044 | /* Don't need lock here: this conntrack not in circulation yet */ | |
1045 | new_state | |
1046 | = tcp_conntracks[0][get_conntrack_index(th)] | |
1047 | [TCP_CONNTRACK_NONE]; | |
1048 | ||
1049 | /* Invalid: delete conntrack */ | |
1050 | if (new_state >= TCP_CONNTRACK_MAX) { | |
1051 | DEBUGP("nf_ct_tcp: invalid new deleting.\n"); | |
1052 | return 0; | |
1053 | } | |
1054 | ||
1055 | if (new_state == TCP_CONNTRACK_SYN_SENT) { | |
1056 | /* SYN packet */ | |
1057 | conntrack->proto.tcp.seen[0].td_end = | |
1058 | segment_seq_plus_len(ntohl(th->seq), skb->len, | |
1059 | dataoff, th); | |
1060 | conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window); | |
1061 | if (conntrack->proto.tcp.seen[0].td_maxwin == 0) | |
1062 | conntrack->proto.tcp.seen[0].td_maxwin = 1; | |
1063 | conntrack->proto.tcp.seen[0].td_maxend = | |
1064 | conntrack->proto.tcp.seen[0].td_end; | |
1065 | ||
1066 | tcp_options(skb, dataoff, th, &conntrack->proto.tcp.seen[0]); | |
1067 | conntrack->proto.tcp.seen[1].flags = 0; | |
1068 | conntrack->proto.tcp.seen[0].loose = | |
1069 | conntrack->proto.tcp.seen[1].loose = 0; | |
1070 | } else if (nf_ct_tcp_loose == 0) { | |
1071 | /* Don't try to pick up connections. */ | |
1072 | return 0; | |
1073 | } else { | |
1074 | /* | |
1075 | * We are in the middle of a connection, | |
1076 | * its history is lost for us. | |
1077 | * Let's try to use the data from the packet. | |
1078 | */ | |
1079 | conntrack->proto.tcp.seen[0].td_end = | |
1080 | segment_seq_plus_len(ntohl(th->seq), skb->len, | |
1081 | dataoff, th); | |
1082 | conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window); | |
1083 | if (conntrack->proto.tcp.seen[0].td_maxwin == 0) | |
1084 | conntrack->proto.tcp.seen[0].td_maxwin = 1; | |
1085 | conntrack->proto.tcp.seen[0].td_maxend = | |
1086 | conntrack->proto.tcp.seen[0].td_end + | |
1087 | conntrack->proto.tcp.seen[0].td_maxwin; | |
1088 | conntrack->proto.tcp.seen[0].td_scale = 0; | |
1089 | ||
1090 | /* We assume SACK. Should we assume window scaling too? */ | |
1091 | conntrack->proto.tcp.seen[0].flags = | |
1092 | conntrack->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM; | |
1093 | conntrack->proto.tcp.seen[0].loose = | |
1094 | conntrack->proto.tcp.seen[1].loose = nf_ct_tcp_loose; | |
1095 | } | |
1096 | ||
1097 | conntrack->proto.tcp.seen[1].td_end = 0; | |
1098 | conntrack->proto.tcp.seen[1].td_maxend = 0; | |
1099 | conntrack->proto.tcp.seen[1].td_maxwin = 1; | |
1100 | conntrack->proto.tcp.seen[1].td_scale = 0; | |
1101 | ||
1102 | /* tcp_packet will set them */ | |
1103 | conntrack->proto.tcp.state = TCP_CONNTRACK_NONE; | |
1104 | conntrack->proto.tcp.last_index = TCP_NONE_SET; | |
1105 | ||
1106 | DEBUGP("tcp_new: sender end=%u maxend=%u maxwin=%u scale=%i " | |
1107 | "receiver end=%u maxend=%u maxwin=%u scale=%i\n", | |
1108 | sender->td_end, sender->td_maxend, sender->td_maxwin, | |
1109 | sender->td_scale, | |
1110 | receiver->td_end, receiver->td_maxend, receiver->td_maxwin, | |
1111 | receiver->td_scale); | |
1112 | return 1; | |
1113 | } | |
c1d10adb PNA |
1114 | |
1115 | #if defined(CONFIG_NF_CT_NETLINK) || \ | |
1116 | defined(CONFIG_NF_CT_NETLINK_MODULE) | |
1117 | ||
1118 | #include <linux/netfilter/nfnetlink.h> | |
1119 | #include <linux/netfilter/nfnetlink_conntrack.h> | |
1120 | ||
1121 | static int tcp_to_nfattr(struct sk_buff *skb, struct nfattr *nfa, | |
1122 | const struct nf_conn *ct) | |
1123 | { | |
1124 | struct nfattr *nest_parms; | |
1125 | ||
1126 | read_lock_bh(&tcp_lock); | |
1127 | nest_parms = NFA_NEST(skb, CTA_PROTOINFO_TCP); | |
1128 | NFA_PUT(skb, CTA_PROTOINFO_TCP_STATE, sizeof(u_int8_t), | |
1129 | &ct->proto.tcp.state); | |
1130 | read_unlock_bh(&tcp_lock); | |
1131 | ||
1132 | NFA_NEST_END(skb, nest_parms); | |
1133 | ||
1134 | return 0; | |
1135 | ||
1136 | nfattr_failure: | |
1137 | read_unlock_bh(&tcp_lock); | |
1138 | return -1; | |
1139 | } | |
1140 | ||
1141 | static const size_t cta_min_tcp[CTA_PROTOINFO_TCP_MAX] = { | |
1142 | [CTA_PROTOINFO_TCP_STATE-1] = sizeof(u_int8_t), | |
1143 | }; | |
1144 | ||
1145 | static int nfattr_to_tcp(struct nfattr *cda[], struct nf_conn *ct) | |
1146 | { | |
1147 | struct nfattr *attr = cda[CTA_PROTOINFO_TCP-1]; | |
1148 | struct nfattr *tb[CTA_PROTOINFO_TCP_MAX]; | |
1149 | ||
1150 | /* updates could not contain anything about the private | |
1151 | * protocol info, in that case skip the parsing */ | |
1152 | if (!attr) | |
1153 | return 0; | |
1154 | ||
1155 | nfattr_parse_nested(tb, CTA_PROTOINFO_TCP_MAX, attr); | |
1156 | ||
1157 | if (nfattr_bad_size(tb, CTA_PROTOINFO_TCP_MAX, cta_min_tcp)) | |
1158 | return -EINVAL; | |
1159 | ||
1160 | if (!tb[CTA_PROTOINFO_TCP_STATE-1]) | |
1161 | return -EINVAL; | |
1162 | ||
1163 | write_lock_bh(&tcp_lock); | |
1164 | ct->proto.tcp.state = | |
1165 | *(u_int8_t *)NFA_DATA(tb[CTA_PROTOINFO_TCP_STATE-1]); | |
1166 | write_unlock_bh(&tcp_lock); | |
1167 | ||
1168 | return 0; | |
1169 | } | |
1170 | #endif | |
9fb9cbb1 YK |
1171 | |
1172 | struct nf_conntrack_protocol nf_conntrack_protocol_tcp4 = | |
1173 | { | |
1174 | .l3proto = PF_INET, | |
1175 | .proto = IPPROTO_TCP, | |
1176 | .name = "tcp", | |
1177 | .pkt_to_tuple = tcp_pkt_to_tuple, | |
1178 | .invert_tuple = tcp_invert_tuple, | |
1179 | .print_tuple = tcp_print_tuple, | |
1180 | .print_conntrack = tcp_print_conntrack, | |
1181 | .packet = tcp_packet, | |
1182 | .new = tcp_new, | |
96f6bf82 | 1183 | .error = tcp_error, |
c1d10adb PNA |
1184 | #if defined(CONFIG_NF_CT_NETLINK) || \ |
1185 | defined(CONFIG_NF_CT_NETLINK_MODULE) | |
1186 | .to_nfattr = tcp_to_nfattr, | |
1187 | .from_nfattr = nfattr_to_tcp, | |
1188 | .tuple_to_nfattr = nf_ct_port_tuple_to_nfattr, | |
1189 | .nfattr_to_tuple = nf_ct_port_nfattr_to_tuple, | |
1190 | #endif | |
9fb9cbb1 YK |
1191 | }; |
1192 | ||
1193 | struct nf_conntrack_protocol nf_conntrack_protocol_tcp6 = | |
1194 | { | |
1195 | .l3proto = PF_INET6, | |
1196 | .proto = IPPROTO_TCP, | |
1197 | .name = "tcp", | |
1198 | .pkt_to_tuple = tcp_pkt_to_tuple, | |
1199 | .invert_tuple = tcp_invert_tuple, | |
1200 | .print_tuple = tcp_print_tuple, | |
1201 | .print_conntrack = tcp_print_conntrack, | |
1202 | .packet = tcp_packet, | |
1203 | .new = tcp_new, | |
96f6bf82 | 1204 | .error = tcp_error, |
c1d10adb PNA |
1205 | #if defined(CONFIG_NF_CT_NETLINK) || \ |
1206 | defined(CONFIG_NF_CT_NETLINK_MODULE) | |
1207 | .to_nfattr = tcp_to_nfattr, | |
1208 | .from_nfattr = nfattr_to_tcp, | |
1209 | .tuple_to_nfattr = nf_ct_port_tuple_to_nfattr, | |
1210 | .nfattr_to_tuple = nf_ct_port_nfattr_to_tuple, | |
1211 | #endif | |
9fb9cbb1 YK |
1212 | }; |
1213 | ||
1214 | EXPORT_SYMBOL(nf_conntrack_protocol_tcp4); | |
1215 | EXPORT_SYMBOL(nf_conntrack_protocol_tcp6); |