1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* (C) 1999-2001 Paul `Rusty' Russell |
3 | * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> |
4 | * (C) 2002-2013 Jozsef Kadlecsik <kadlec@netfilter.org> |
5 | * (C) 2006-2012 Patrick McHardy <kaber@trash.net> |
6 | */ |
7 | |
8 | #include <linux/types.h> |
9 | #include <linux/timer.h> |
10 | #include <linux/module.h> |
11 | #include <linux/in.h> |
12 | #include <linux/tcp.h> |
13 | #include <linux/spinlock.h> |
14 | #include <linux/skbuff.h> |
15 | #include <linux/ipv6.h> |
16 | #include <net/ip6_checksum.h> |
17 | #include <asm/unaligned.h> |
18 | |
19 | #include <net/tcp.h> |
20 | |
21 | #include <linux/netfilter.h> |
22 | #include <linux/netfilter_ipv4.h> |
23 | #include <linux/netfilter_ipv6.h> |
24 | #include <net/netfilter/nf_conntrack.h> |
25 | #include <net/netfilter/nf_conntrack_l4proto.h> |
26 | #include <net/netfilter/nf_conntrack_ecache.h> |
27 | #include <net/netfilter/nf_conntrack_seqadj.h> |
28 | #include <net/netfilter/nf_conntrack_synproxy.h> |
29 | #include <net/netfilter/nf_conntrack_timeout.h> |
30 | #include <net/netfilter/nf_log.h> |
31 | #include <net/netfilter/ipv4/nf_conntrack_ipv4.h> |
32 | #include <net/netfilter/ipv6/nf_conntrack_ipv6.h> |
33 | |
34 | /* FIXME: Examine ipfilter's timeouts and conntrack transitions more |
35 | closely. They're more complex. --RR */ |
36 | |
37 | static const char *const tcp_conntrack_names[] = { |
38 | "NONE" , |
39 | "SYN_SENT" , |
40 | "SYN_RECV" , |
41 | "ESTABLISHED" , |
42 | "FIN_WAIT" , |
43 | "CLOSE_WAIT" , |
44 | "LAST_ACK" , |
45 | "TIME_WAIT" , |
46 | "CLOSE" , |
47 | "SYN_SENT2" , |
48 | }; |
49 | |
50 | enum nf_ct_tcp_action { |
51 | NFCT_TCP_IGNORE, |
52 | NFCT_TCP_INVALID, |
53 | NFCT_TCP_ACCEPT, |
54 | }; |
55 | |
56 | #define SECS * HZ |
57 | #define MINS * 60 SECS |
58 | #define HOURS * 60 MINS |
59 | #define DAYS * 24 HOURS |
60 | |
61 | static const unsigned int tcp_timeouts[TCP_CONNTRACK_TIMEOUT_MAX] = { |
62 | [TCP_CONNTRACK_SYN_SENT] = 2 MINS, |
63 | [TCP_CONNTRACK_SYN_RECV] = 60 SECS, |
64 | [TCP_CONNTRACK_ESTABLISHED] = 5 DAYS, |
65 | [TCP_CONNTRACK_FIN_WAIT] = 2 MINS, |
66 | [TCP_CONNTRACK_CLOSE_WAIT] = 60 SECS, |
67 | [TCP_CONNTRACK_LAST_ACK] = 30 SECS, |
68 | [TCP_CONNTRACK_TIME_WAIT] = 2 MINS, |
69 | [TCP_CONNTRACK_CLOSE] = 10 SECS, |
70 | [TCP_CONNTRACK_SYN_SENT2] = 2 MINS, |
71 | /* RFC1122 says the R2 limit should be at least 100 seconds. |
72 | Linux uses 15 packets as limit, which corresponds |
73 | to ~13-30min depending on RTO. */ |
74 | [TCP_CONNTRACK_RETRANS] = 5 MINS, |
75 | [TCP_CONNTRACK_UNACK] = 5 MINS, |
76 | }; |
77 | |
78 | #define sNO TCP_CONNTRACK_NONE |
79 | #define sSS TCP_CONNTRACK_SYN_SENT |
80 | #define sSR TCP_CONNTRACK_SYN_RECV |
81 | #define sES TCP_CONNTRACK_ESTABLISHED |
82 | #define sFW TCP_CONNTRACK_FIN_WAIT |
83 | #define sCW TCP_CONNTRACK_CLOSE_WAIT |
84 | #define sLA TCP_CONNTRACK_LAST_ACK |
85 | #define sTW TCP_CONNTRACK_TIME_WAIT |
86 | #define sCL TCP_CONNTRACK_CLOSE |
87 | #define sS2 TCP_CONNTRACK_SYN_SENT2 |
88 | #define sIV TCP_CONNTRACK_MAX |
89 | #define sIG TCP_CONNTRACK_IGNORE |
90 | |
91 | /* What TCP flags are set from RST/SYN/FIN/ACK. */ |
92 | enum tcp_bit_set { |
93 | TCP_SYN_SET, |
94 | TCP_SYNACK_SET, |
95 | TCP_FIN_SET, |
96 | TCP_ACK_SET, |
97 | TCP_RST_SET, |
98 | TCP_NONE_SET, |
99 | }; |
100 | |
101 | /* |
102 | * The TCP state transition table needs a few words... |
103 | * |
104 | * We are the man in the middle. All the packets go through us |
105 | * but might get lost in transit to the destination. |
106 | * It is assumed that the destinations can't receive segments |
107 | * we haven't seen. |
108 | * |
109 | * The checked segment is in window, but our windows are *not* |
110 | * equivalent with the ones of the sender/receiver. We always |
111 | * try to guess the state of the current sender. |
112 | * |
113 | * The meaning of the states are: |
114 | * |
115 | * NONE: initial state |
116 | * SYN_SENT: SYN-only packet seen |
117 | * SYN_SENT2: SYN-only packet seen from reply dir, simultaneous open |
118 | * SYN_RECV: SYN-ACK packet seen |
119 | * ESTABLISHED: ACK packet seen |
120 | * FIN_WAIT: FIN packet seen |
121 | * CLOSE_WAIT: ACK seen (after FIN) |
122 | * LAST_ACK: FIN seen (after FIN) |
123 | * TIME_WAIT: last ACK seen |
124 | * CLOSE: closed connection (RST) |
125 | * |
126 | * Packets marked as IGNORED (sIG): |
127 | * if they may be either invalid or valid |
128 | * and the receiver may send back a connection |
129 | * closing RST or a SYN/ACK. |
130 | * |
131 | * Packets marked as INVALID (sIV): |
132 | * if we regard them as truly invalid packets |
133 | */ |
134 | static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = { |
135 | { |
136 | /* ORIGINAL */ |
137 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */ |
138 | /*syn*/ { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sS2 }, |
139 | /* |
140 | * sNO -> sSS Initialize a new connection |
141 | * sSS -> sSS Retransmitted SYN |
142 | * sS2 -> sS2 Late retransmitted SYN |
143 | * sSR -> sIG |
144 | * sES -> sIG Error: SYNs in window outside the SYN_SENT state |
145 | * are errors. Receiver will reply with RST |
146 | * and close the connection. |
147 | * Or we are not in sync and hold a dead connection. |
148 | * sFW -> sIG |
149 | * sCW -> sIG |
150 | * sLA -> sIG |
151 | * sTW -> sSS Reopened connection (RFC 1122). |
152 | * sCL -> sSS |
153 | */ |
154 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */ |
155 | /*synack*/ { sIV, sIV, sSR, sIV, sIV, sIV, sIV, sIV, sIV, sSR }, |
156 | /* |
157 | * sNO -> sIV Too late and no reason to do anything |
158 | * sSS -> sIV Client can't send SYN and then SYN/ACK |
159 | * sS2 -> sSR SYN/ACK sent to SYN2 in simultaneous open |
160 | * sSR -> sSR Late retransmitted SYN/ACK in simultaneous open |
161 | * sES -> sIV Invalid SYN/ACK packets sent by the client |
162 | * sFW -> sIV |
163 | * sCW -> sIV |
164 | * sLA -> sIV |
165 | * sTW -> sIV |
166 | * sCL -> sIV |
167 | */ |
168 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */ |
169 | /*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV }, |
170 | /* |
171 | * sNO -> sIV Too late and no reason to do anything... |
172 | * sSS -> sIV Client migth not send FIN in this state: |
173 | * we enforce waiting for a SYN/ACK reply first. |
174 | * sS2 -> sIV |
175 | * sSR -> sFW Close started. |
176 | * sES -> sFW |
177 | * sFW -> sLA FIN seen in both directions, waiting for |
178 | * the last ACK. |
179 | * Migth be a retransmitted FIN as well... |
180 | * sCW -> sLA |
181 | * sLA -> sLA Retransmitted FIN. Remain in the same state. |
182 | * sTW -> sTW |
183 | * sCL -> sCL |
184 | */ |
185 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */ |
186 | /*ack*/ { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV }, |
187 | /* |
188 | * sNO -> sES Assumed. |
189 | * sSS -> sIV ACK is invalid: we haven't seen a SYN/ACK yet. |
190 | * sS2 -> sIV |
191 | * sSR -> sES Established state is reached. |
192 | * sES -> sES :-) |
193 | * sFW -> sCW Normal close request answered by ACK. |
194 | * sCW -> sCW |
195 | * sLA -> sTW Last ACK detected (RFC5961 challenged) |
196 | * sTW -> sTW Retransmitted last ACK. Remain in the same state. |
197 | * sCL -> sCL |
198 | */ |
199 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */ |
200 | /*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL }, |
201 | /*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV } |
202 | }, |
203 | { |
204 | /* REPLY */ |
205 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */ |
206 | /*syn*/ { sIV, sS2, sIV, sIV, sIV, sIV, sIV, sSS, sIV, sS2 }, |
207 | /* |
208 | * sNO -> sIV Never reached. |
209 | * sSS -> sS2 Simultaneous open |
210 | * sS2 -> sS2 Retransmitted simultaneous SYN |
211 | * sSR -> sIV Invalid SYN packets sent by the server |
212 | * sES -> sIV |
213 | * sFW -> sIV |
214 | * sCW -> sIV |
215 | * sLA -> sIV |
216 | * sTW -> sSS Reopened connection, but server may have switched role |
217 | * sCL -> sIV |
218 | */ |
219 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */ |
220 | /*synack*/ { sIV, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIG, sSR }, |
221 | /* |
222 | * sSS -> sSR Standard open. |
223 | * sS2 -> sSR Simultaneous open |
224 | * sSR -> sIG Retransmitted SYN/ACK, ignore it. |
225 | * sES -> sIG Late retransmitted SYN/ACK? |
226 | * sFW -> sIG Might be SYN/ACK answering ignored SYN |
227 | * sCW -> sIG |
228 | * sLA -> sIG |
229 | * sTW -> sIG |
230 | * sCL -> sIG |
231 | */ |
232 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */ |
233 | /*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV }, |
234 | /* |
235 | * sSS -> sIV Server might not send FIN in this state. |
236 | * sS2 -> sIV |
237 | * sSR -> sFW Close started. |
238 | * sES -> sFW |
239 | * sFW -> sLA FIN seen in both directions. |
240 | * sCW -> sLA |
241 | * sLA -> sLA Retransmitted FIN. |
242 | * sTW -> sTW |
243 | * sCL -> sCL |
244 | */ |
245 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */ |
246 | /*ack*/ { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIG }, |
247 | /* |
248 | * sSS -> sIG Might be a half-open connection. |
249 | * sS2 -> sIG |
250 | * sSR -> sSR Might answer late resent SYN. |
251 | * sES -> sES :-) |
252 | * sFW -> sCW Normal close request answered by ACK. |
253 | * sCW -> sCW |
254 | * sLA -> sTW Last ACK detected (RFC5961 challenged) |
255 | * sTW -> sTW Retransmitted last ACK. |
256 | * sCL -> sCL |
257 | */ |
258 | /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */ |
259 | /*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL }, |
260 | /*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV } |
261 | } |
262 | }; |
263 | |
264 | #ifdef CONFIG_NF_CONNTRACK_PROCFS |
265 | /* Print out the private part of the conntrack. */ |
266 | static void tcp_print_conntrack(struct seq_file *s, struct nf_conn *ct) |
267 | { |
268 | if (test_bit(IPS_OFFLOAD_BIT, &ct->status)) |
269 | return; |
270 | |
271 | seq_printf(m: s, fmt: "%s " , tcp_conntrack_names[ct->proto.tcp.state]); |
272 | } |
273 | #endif |
274 | |
275 | static unsigned int get_conntrack_index(const struct tcphdr *tcph) |
276 | { |
277 | if (tcph->rst) return TCP_RST_SET; |
278 | else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET); |
279 | else if (tcph->fin) return TCP_FIN_SET; |
280 | else if (tcph->ack) return TCP_ACK_SET; |
281 | else return TCP_NONE_SET; |
282 | } |
283 | |
284 | /* TCP connection tracking based on 'Real Stateful TCP Packet Filtering |
285 | in IP Filter' by Guido van Rooij. |
286 | |
287 | http://www.sane.nl/events/sane2000/papers.html |
288 | http://www.darkart.com/mirrors/www.obfuscation.org/ipf/ |
289 | |
290 | The boundaries and the conditions are changed according to RFC793: |
291 | the packet must intersect the window (i.e. segments may be |
292 | after the right or before the left edge) and thus receivers may ACK |
293 | segments after the right edge of the window. |
294 | |
295 | td_maxend = max(sack + max(win,1)) seen in reply packets |
296 | td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets |
297 | td_maxwin += seq + len - sender.td_maxend |
298 | if seq + len > sender.td_maxend |
299 | td_end = max(seq + len) seen in sent packets |
300 | |
301 | I. Upper bound for valid data: seq <= sender.td_maxend |
302 | II. Lower bound for valid data: seq + len >= sender.td_end - receiver.td_maxwin |
303 | III. Upper bound for valid (s)ack: sack <= receiver.td_end |
304 | IV. Lower bound for valid (s)ack: sack >= receiver.td_end - MAXACKWINDOW |
305 | |
306 | where sack is the highest right edge of sack block found in the packet |
307 | or ack in the case of packet without SACK option. |
308 | |
309 | The upper bound limit for a valid (s)ack is not ignored - |
310 | we doesn't have to deal with fragments. |
311 | */ |
312 | |
313 | static inline __u32 segment_seq_plus_len(__u32 seq, |
314 | size_t len, |
315 | unsigned int dataoff, |
316 | const struct tcphdr *tcph) |
317 | { |
318 | /* XXX Should I use payload length field in IP/IPv6 header ? |
319 | * - YK */ |
320 | return (seq + len - dataoff - tcph->doff*4 |
321 | + (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0)); |
322 | } |
323 | |
324 | /* Fixme: what about big packets? */ |
325 | #define MAXACKWINCONST 66000 |
326 | #define MAXACKWINDOW(sender) \ |
327 | ((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin \ |
328 | : MAXACKWINCONST) |
329 | |
330 | /* |
331 | * Simplified tcp_parse_options routine from tcp_input.c |
332 | */ |
333 | static void tcp_options(const struct sk_buff *skb, |
334 | unsigned int dataoff, |
335 | const struct tcphdr *tcph, |
336 | struct ip_ct_tcp_state *state) |
337 | { |
338 | unsigned char buff[(15 * 4) - sizeof(struct tcphdr)]; |
339 | const unsigned char *ptr; |
340 | int length = (tcph->doff*4) - sizeof(struct tcphdr); |
341 | |
342 | if (!length) |
343 | return; |
344 | |
345 | ptr = skb_header_pointer(skb, offset: dataoff + sizeof(struct tcphdr), |
346 | len: length, buffer: buff); |
347 | if (!ptr) |
348 | return; |
349 | |
350 | state->td_scale = 0; |
351 | state->flags &= IP_CT_TCP_FLAG_BE_LIBERAL; |
352 | |
353 | while (length > 0) { |
354 | int opcode=*ptr++; |
355 | int opsize; |
356 | |
357 | switch (opcode) { |
358 | case TCPOPT_EOL: |
359 | return; |
360 | case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */ |
361 | length--; |
362 | continue; |
363 | default: |
364 | if (length < 2) |
365 | return; |
366 | opsize=*ptr++; |
367 | if (opsize < 2) /* "silly options" */ |
368 | return; |
369 | if (opsize > length) |
370 | return; /* don't parse partial options */ |
371 | |
372 | if (opcode == TCPOPT_SACK_PERM |
373 | && opsize == TCPOLEN_SACK_PERM) |
374 | state->flags |= IP_CT_TCP_FLAG_SACK_PERM; |
375 | else if (opcode == TCPOPT_WINDOW |
376 | && opsize == TCPOLEN_WINDOW) { |
377 | state->td_scale = *(u_int8_t *)ptr; |
378 | |
379 | if (state->td_scale > TCP_MAX_WSCALE) |
380 | state->td_scale = TCP_MAX_WSCALE; |
381 | |
382 | state->flags |= |
383 | IP_CT_TCP_FLAG_WINDOW_SCALE; |
384 | } |
385 | ptr += opsize - 2; |
386 | length -= opsize; |
387 | } |
388 | } |
389 | } |
390 | |
391 | static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff, |
392 | const struct tcphdr *tcph, __u32 *sack) |
393 | { |
394 | unsigned char buff[(15 * 4) - sizeof(struct tcphdr)]; |
395 | const unsigned char *ptr; |
396 | int length = (tcph->doff*4) - sizeof(struct tcphdr); |
397 | __u32 tmp; |
398 | |
399 | if (!length) |
400 | return; |
401 | |
402 | ptr = skb_header_pointer(skb, offset: dataoff + sizeof(struct tcphdr), |
403 | len: length, buffer: buff); |
404 | if (!ptr) |
405 | return; |
406 | |
407 | /* Fast path for timestamp-only option */ |
408 | if (length == TCPOLEN_TSTAMP_ALIGNED |
409 | && *(__be32 *)ptr == htonl((TCPOPT_NOP << 24) |
410 | | (TCPOPT_NOP << 16) |
411 | | (TCPOPT_TIMESTAMP << 8) |
412 | | TCPOLEN_TIMESTAMP)) |
413 | return; |
414 | |
415 | while (length > 0) { |
416 | int opcode = *ptr++; |
417 | int opsize, i; |
418 | |
419 | switch (opcode) { |
420 | case TCPOPT_EOL: |
421 | return; |
422 | case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */ |
423 | length--; |
424 | continue; |
425 | default: |
426 | if (length < 2) |
427 | return; |
428 | opsize = *ptr++; |
429 | if (opsize < 2) /* "silly options" */ |
430 | return; |
431 | if (opsize > length) |
432 | return; /* don't parse partial options */ |
433 | |
434 | if (opcode == TCPOPT_SACK |
435 | && opsize >= (TCPOLEN_SACK_BASE |
436 | + TCPOLEN_SACK_PERBLOCK) |
437 | && !((opsize - TCPOLEN_SACK_BASE) |
438 | % TCPOLEN_SACK_PERBLOCK)) { |
439 | for (i = 0; |
440 | i < (opsize - TCPOLEN_SACK_BASE); |
441 | i += TCPOLEN_SACK_PERBLOCK) { |
442 | tmp = get_unaligned_be32(p: (__be32 *)(ptr+i)+1); |
443 | |
444 | if (after(tmp, *sack)) |
445 | *sack = tmp; |
446 | } |
447 | return; |
448 | } |
449 | ptr += opsize - 2; |
450 | length -= opsize; |
451 | } |
452 | } |
453 | } |
454 | |
455 | static void tcp_init_sender(struct ip_ct_tcp_state *sender, |
456 | struct ip_ct_tcp_state *receiver, |
457 | const struct sk_buff *skb, |
458 | unsigned int dataoff, |
459 | const struct tcphdr *tcph, |
460 | u32 end, u32 win, |
461 | enum ip_conntrack_dir dir) |
462 | { |
463 | /* SYN-ACK in reply to a SYN |
464 | * or SYN from reply direction in simultaneous open. |
465 | */ |
466 | sender->td_end = |
467 | sender->td_maxend = end; |
468 | sender->td_maxwin = (win == 0 ? 1 : win); |
469 | |
470 | tcp_options(skb, dataoff, tcph, state: sender); |
471 | /* RFC 1323: |
472 | * Both sides must send the Window Scale option |
473 | * to enable window scaling in either direction. |
474 | */ |
475 | if (dir == IP_CT_DIR_REPLY && |
476 | !(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE && |
477 | receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE)) { |
478 | sender->td_scale = 0; |
479 | receiver->td_scale = 0; |
480 | } |
481 | } |
482 | |
483 | __printf(6, 7) |
484 | static enum nf_ct_tcp_action nf_tcp_log_invalid(const struct sk_buff *skb, |
485 | const struct nf_conn *ct, |
486 | const struct nf_hook_state *state, |
487 | const struct ip_ct_tcp_state *sender, |
488 | enum nf_ct_tcp_action ret, |
489 | const char *fmt, ...) |
490 | { |
491 | const struct nf_tcp_net *tn = nf_tcp_pernet(net: nf_ct_net(ct)); |
492 | struct va_format vaf; |
493 | va_list args; |
494 | bool be_liberal; |
495 | |
496 | be_liberal = sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL || tn->tcp_be_liberal; |
497 | if (be_liberal) |
498 | return NFCT_TCP_ACCEPT; |
499 | |
500 | va_start(args, fmt); |
501 | vaf.fmt = fmt; |
502 | vaf.va = &args; |
503 | nf_ct_l4proto_log_invalid(skb, ct, state, fmt: "%pV" , &vaf); |
504 | va_end(args); |
505 | |
506 | return ret; |
507 | } |
508 | |
509 | static enum nf_ct_tcp_action |
510 | tcp_in_window(struct nf_conn *ct, enum ip_conntrack_dir dir, |
511 | unsigned int index, const struct sk_buff *skb, |
512 | unsigned int dataoff, const struct tcphdr *tcph, |
513 | const struct nf_hook_state *hook_state) |
514 | { |
515 | struct ip_ct_tcp *state = &ct->proto.tcp; |
516 | struct ip_ct_tcp_state *sender = &state->seen[dir]; |
517 | struct ip_ct_tcp_state *receiver = &state->seen[!dir]; |
518 | __u32 seq, ack, sack, end, win, swin; |
519 | bool in_recv_win, seq_ok; |
520 | s32 receiver_offset; |
521 | u16 win_raw; |
522 | |
523 | /* |
524 | * Get the required data from the packet. |
525 | */ |
526 | seq = ntohl(tcph->seq); |
527 | ack = sack = ntohl(tcph->ack_seq); |
528 | win_raw = ntohs(tcph->window); |
529 | win = win_raw; |
530 | end = segment_seq_plus_len(seq, len: skb->len, dataoff, tcph); |
531 | |
532 | if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM) |
533 | tcp_sack(skb, dataoff, tcph, sack: &sack); |
534 | |
535 | /* Take into account NAT sequence number mangling */ |
536 | receiver_offset = nf_ct_seq_offset(ct, !dir, seq: ack - 1); |
537 | ack -= receiver_offset; |
538 | sack -= receiver_offset; |
539 | |
540 | if (sender->td_maxwin == 0) { |
541 | /* |
542 | * Initialize sender data. |
543 | */ |
544 | if (tcph->syn) { |
545 | tcp_init_sender(sender, receiver, |
546 | skb, dataoff, tcph, |
547 | end, win, dir); |
548 | if (!tcph->ack) |
549 | /* Simultaneous open */ |
550 | return NFCT_TCP_ACCEPT; |
551 | } else { |
552 | /* |
553 | * We are in the middle of a connection, |
554 | * its history is lost for us. |
555 | * Let's try to use the data from the packet. |
556 | */ |
557 | sender->td_end = end; |
558 | swin = win << sender->td_scale; |
559 | sender->td_maxwin = (swin == 0 ? 1 : swin); |
560 | sender->td_maxend = end + sender->td_maxwin; |
561 | if (receiver->td_maxwin == 0) { |
562 | /* We haven't seen traffic in the other |
563 | * direction yet but we have to tweak window |
564 | * tracking to pass III and IV until that |
565 | * happens. |
566 | */ |
567 | receiver->td_end = receiver->td_maxend = sack; |
568 | } else if (sack == receiver->td_end + 1) { |
569 | /* Likely a reply to a keepalive. |
570 | * Needed for III. |
571 | */ |
572 | receiver->td_end++; |
573 | } |
574 | |
575 | } |
576 | } else if (tcph->syn && |
577 | after(end, sender->td_end) && |
578 | (state->state == TCP_CONNTRACK_SYN_SENT || |
579 | state->state == TCP_CONNTRACK_SYN_RECV)) { |
580 | /* |
581 | * RFC 793: "if a TCP is reinitialized ... then it need |
582 | * not wait at all; it must only be sure to use sequence |
583 | * numbers larger than those recently used." |
584 | * |
585 | * Re-init state for this direction, just like for the first |
586 | * syn(-ack) reply, it might differ in seq, ack or tcp options. |
587 | */ |
588 | tcp_init_sender(sender, receiver, |
589 | skb, dataoff, tcph, |
590 | end, win, dir); |
591 | |
592 | if (dir == IP_CT_DIR_REPLY && !tcph->ack) |
593 | return NFCT_TCP_ACCEPT; |
594 | } |
595 | |
596 | if (!(tcph->ack)) { |
597 | /* |
598 | * If there is no ACK, just pretend it was set and OK. |
599 | */ |
600 | ack = sack = receiver->td_end; |
601 | } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) == |
602 | (TCP_FLAG_ACK|TCP_FLAG_RST)) |
603 | && (ack == 0)) { |
604 | /* |
605 | * Broken TCP stacks, that set ACK in RST packets as well |
606 | * with zero ack value. |
607 | */ |
608 | ack = sack = receiver->td_end; |
609 | } |
610 | |
611 | if (tcph->rst && seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT) |
612 | /* |
613 | * RST sent answering SYN. |
614 | */ |
615 | seq = end = sender->td_end; |
616 | |
617 | seq_ok = before(seq1: seq, seq2: sender->td_maxend + 1); |
618 | if (!seq_ok) { |
619 | u32 overshot = end - sender->td_maxend + 1; |
620 | bool ack_ok; |
621 | |
622 | ack_ok = after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1); |
623 | in_recv_win = receiver->td_maxwin && |
624 | after(end, sender->td_end - receiver->td_maxwin - 1); |
625 | |
626 | if (in_recv_win && |
627 | ack_ok && |
628 | overshot <= receiver->td_maxwin && |
629 | before(seq1: sack, seq2: receiver->td_end + 1)) { |
630 | /* Work around TCPs that send more bytes than allowed by |
631 | * the receive window. |
632 | * |
633 | * If the (marked as invalid) packet is allowed to pass by |
634 | * the ruleset and the peer acks this data, then its possible |
635 | * all future packets will trigger 'ACK is over upper bound' check. |
636 | * |
637 | * Thus if only the sequence check fails then do update td_end so |
638 | * possible ACK for this data can update internal state. |
639 | */ |
640 | sender->td_end = end; |
641 | sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED; |
642 | |
643 | return nf_tcp_log_invalid(skb, ct, state: hook_state, sender, ret: NFCT_TCP_IGNORE, |
644 | fmt: "%u bytes more than expected" , overshot); |
645 | } |
646 | |
647 | return nf_tcp_log_invalid(skb, ct, state: hook_state, sender, ret: NFCT_TCP_INVALID, |
648 | fmt: "SEQ is over upper bound %u (over the window of the receiver)" , |
649 | sender->td_maxend + 1); |
650 | } |
651 | |
652 | if (!before(seq1: sack, seq2: receiver->td_end + 1)) |
653 | return nf_tcp_log_invalid(skb, ct, state: hook_state, sender, ret: NFCT_TCP_INVALID, |
654 | fmt: "ACK is over upper bound %u (ACKed data not seen yet)" , |
655 | receiver->td_end + 1); |
656 | |
657 | /* Is the ending sequence in the receive window (if available)? */ |
658 | in_recv_win = !receiver->td_maxwin || |
659 | after(end, sender->td_end - receiver->td_maxwin - 1); |
660 | if (!in_recv_win) |
661 | return nf_tcp_log_invalid(skb, ct, state: hook_state, sender, ret: NFCT_TCP_IGNORE, |
662 | fmt: "SEQ is under lower bound %u (already ACKed data retransmitted)" , |
663 | sender->td_end - receiver->td_maxwin - 1); |
664 | if (!after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1)) |
665 | return nf_tcp_log_invalid(skb, ct, state: hook_state, sender, ret: NFCT_TCP_IGNORE, |
666 | fmt: "ignored ACK under lower bound %u (possible overly delayed)" , |
667 | receiver->td_end - MAXACKWINDOW(sender) - 1); |
668 | |
669 | /* Take into account window scaling (RFC 1323). */ |
670 | if (!tcph->syn) |
671 | win <<= sender->td_scale; |
672 | |
673 | /* Update sender data. */ |
674 | swin = win + (sack - ack); |
675 | if (sender->td_maxwin < swin) |
676 | sender->td_maxwin = swin; |
677 | if (after(end, sender->td_end)) { |
678 | sender->td_end = end; |
679 | sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED; |
680 | } |
681 | if (tcph->ack) { |
682 | if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) { |
683 | sender->td_maxack = ack; |
684 | sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET; |
685 | } else if (after(ack, sender->td_maxack)) { |
686 | sender->td_maxack = ack; |
687 | } |
688 | } |
689 | |
690 | /* Update receiver data. */ |
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 | /* Check retransmissions. */ |
702 | if (index == TCP_ACK_SET) { |
703 | if (state->last_dir == dir && |
704 | state->last_seq == seq && |
705 | state->last_ack == ack && |
706 | state->last_end == end && |
707 | state->last_win == win_raw) { |
708 | state->retrans++; |
709 | } else { |
710 | state->last_dir = dir; |
711 | state->last_seq = seq; |
712 | state->last_ack = ack; |
713 | state->last_end = end; |
714 | state->last_win = win_raw; |
715 | state->retrans = 0; |
716 | } |
717 | } |
718 | |
719 | return NFCT_TCP_ACCEPT; |
720 | } |
721 | |
722 | static void __cold nf_tcp_handle_invalid(struct nf_conn *ct, |
723 | enum ip_conntrack_dir dir, |
724 | int index, |
725 | const struct sk_buff *skb, |
726 | const struct nf_hook_state *hook_state) |
727 | { |
728 | const unsigned int *timeouts; |
729 | const struct nf_tcp_net *tn; |
730 | unsigned int timeout; |
731 | u32 expires; |
732 | |
733 | if (!test_bit(IPS_ASSURED_BIT, &ct->status) || |
734 | test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status)) |
735 | return; |
736 | |
737 | /* We don't want to have connections hanging around in ESTABLISHED |
738 | * state for long time 'just because' conntrack deemed a FIN/RST |
739 | * out-of-window. |
740 | * |
741 | * Shrink the timeout just like when there is unacked data. |
742 | * This speeds up eviction of 'dead' connections where the |
743 | * connection and conntracks internal state are out of sync. |
744 | */ |
745 | switch (index) { |
746 | case TCP_RST_SET: |
747 | case TCP_FIN_SET: |
748 | break; |
749 | default: |
750 | return; |
751 | } |
752 | |
753 | if (ct->proto.tcp.last_dir != dir && |
754 | (ct->proto.tcp.last_index == TCP_FIN_SET || |
755 | ct->proto.tcp.last_index == TCP_RST_SET)) { |
756 | expires = nf_ct_expires(ct); |
757 | if (expires < 120 * HZ) |
758 | return; |
759 | |
760 | tn = nf_tcp_pernet(net: nf_ct_net(ct)); |
761 | timeouts = nf_ct_timeout_lookup(ct); |
762 | if (!timeouts) |
763 | timeouts = tn->timeouts; |
764 | |
765 | timeout = READ_ONCE(timeouts[TCP_CONNTRACK_UNACK]); |
766 | if (expires > timeout) { |
767 | nf_ct_l4proto_log_invalid(skb, ct, state: hook_state, |
768 | fmt: "packet (index %d, dir %d) response for index %d lower timeout to %u" , |
769 | index, dir, ct->proto.tcp.last_index, timeout); |
770 | |
771 | WRITE_ONCE(ct->timeout, timeout + nfct_time_stamp); |
772 | } |
773 | } else { |
774 | ct->proto.tcp.last_index = index; |
775 | ct->proto.tcp.last_dir = dir; |
776 | } |
777 | } |
778 | |
779 | /* table of valid flag combinations - PUSH, ECE and CWR are always valid */ |
780 | static const u8 tcp_valid_flags[(TCPHDR_FIN|TCPHDR_SYN|TCPHDR_RST|TCPHDR_ACK| |
781 | TCPHDR_URG) + 1] = |
782 | { |
783 | [TCPHDR_SYN] = 1, |
784 | [TCPHDR_SYN|TCPHDR_URG] = 1, |
785 | [TCPHDR_SYN|TCPHDR_ACK] = 1, |
786 | [TCPHDR_RST] = 1, |
787 | [TCPHDR_RST|TCPHDR_ACK] = 1, |
788 | [TCPHDR_FIN|TCPHDR_ACK] = 1, |
789 | [TCPHDR_FIN|TCPHDR_ACK|TCPHDR_URG] = 1, |
790 | [TCPHDR_ACK] = 1, |
791 | [TCPHDR_ACK|TCPHDR_URG] = 1, |
792 | }; |
793 | |
794 | static void tcp_error_log(const struct sk_buff *skb, |
795 | const struct nf_hook_state *state, |
796 | const char *msg) |
797 | { |
798 | nf_l4proto_log_invalid(skb, state, IPPROTO_TCP, fmt: "%s" , msg); |
799 | } |
800 | |
801 | /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c. */ |
802 | static bool tcp_error(const struct tcphdr *th, |
803 | struct sk_buff *skb, |
804 | unsigned int dataoff, |
805 | const struct nf_hook_state *state) |
806 | { |
807 | unsigned int tcplen = skb->len - dataoff; |
808 | u8 tcpflags; |
809 | |
810 | /* Not whole TCP header or malformed packet */ |
811 | if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) { |
812 | tcp_error_log(skb, state, msg: "truncated packet" ); |
813 | return true; |
814 | } |
815 | |
816 | /* Checksum invalid? Ignore. |
817 | * We skip checking packets on the outgoing path |
818 | * because the checksum is assumed to be correct. |
819 | */ |
820 | /* FIXME: Source route IP option packets --RR */ |
821 | if (state->net->ct.sysctl_checksum && |
822 | state->hook == NF_INET_PRE_ROUTING && |
823 | nf_checksum(skb, hook: state->hook, dataoff, IPPROTO_TCP, family: state->pf)) { |
824 | tcp_error_log(skb, state, msg: "bad checksum" ); |
825 | return true; |
826 | } |
827 | |
828 | /* Check TCP flags. */ |
829 | tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH)); |
830 | if (!tcp_valid_flags[tcpflags]) { |
831 | tcp_error_log(skb, state, msg: "invalid tcp flag combination" ); |
832 | return true; |
833 | } |
834 | |
835 | return false; |
836 | } |
837 | |
838 | static noinline bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb, |
839 | unsigned int dataoff, |
840 | const struct tcphdr *th, |
841 | const struct nf_hook_state *state) |
842 | { |
843 | enum tcp_conntrack new_state; |
844 | struct net *net = nf_ct_net(ct); |
845 | const struct nf_tcp_net *tn = nf_tcp_pernet(net); |
846 | |
847 | /* Don't need lock here: this conntrack not in circulation yet */ |
848 | new_state = tcp_conntracks[0][get_conntrack_index(tcph: th)][TCP_CONNTRACK_NONE]; |
849 | |
850 | /* Invalid: delete conntrack */ |
851 | if (new_state >= TCP_CONNTRACK_MAX) { |
852 | tcp_error_log(skb, state, msg: "invalid new" ); |
853 | return false; |
854 | } |
855 | |
856 | if (new_state == TCP_CONNTRACK_SYN_SENT) { |
857 | memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp)); |
858 | /* SYN packet */ |
859 | ct->proto.tcp.seen[0].td_end = |
860 | segment_seq_plus_len(ntohl(th->seq), len: skb->len, |
861 | dataoff, tcph: th); |
862 | ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window); |
863 | if (ct->proto.tcp.seen[0].td_maxwin == 0) |
864 | ct->proto.tcp.seen[0].td_maxwin = 1; |
865 | ct->proto.tcp.seen[0].td_maxend = |
866 | ct->proto.tcp.seen[0].td_end; |
867 | |
868 | tcp_options(skb, dataoff, tcph: th, state: &ct->proto.tcp.seen[0]); |
869 | } else if (tn->tcp_loose == 0) { |
870 | /* Don't try to pick up connections. */ |
871 | return false; |
872 | } else { |
873 | memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp)); |
874 | /* |
875 | * We are in the middle of a connection, |
876 | * its history is lost for us. |
877 | * Let's try to use the data from the packet. |
878 | */ |
879 | ct->proto.tcp.seen[0].td_end = |
880 | segment_seq_plus_len(ntohl(th->seq), len: skb->len, |
881 | dataoff, tcph: th); |
882 | ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window); |
883 | if (ct->proto.tcp.seen[0].td_maxwin == 0) |
884 | ct->proto.tcp.seen[0].td_maxwin = 1; |
885 | ct->proto.tcp.seen[0].td_maxend = |
886 | ct->proto.tcp.seen[0].td_end + |
887 | ct->proto.tcp.seen[0].td_maxwin; |
888 | |
889 | /* We assume SACK and liberal window checking to handle |
890 | * window scaling */ |
891 | ct->proto.tcp.seen[0].flags = |
892 | ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM | |
893 | IP_CT_TCP_FLAG_BE_LIBERAL; |
894 | } |
895 | |
896 | /* tcp_packet will set them */ |
897 | ct->proto.tcp.last_index = TCP_NONE_SET; |
898 | return true; |
899 | } |
900 | |
901 | static bool tcp_can_early_drop(const struct nf_conn *ct) |
902 | { |
903 | switch (ct->proto.tcp.state) { |
904 | case TCP_CONNTRACK_FIN_WAIT: |
905 | case TCP_CONNTRACK_LAST_ACK: |
906 | case TCP_CONNTRACK_TIME_WAIT: |
907 | case TCP_CONNTRACK_CLOSE: |
908 | case TCP_CONNTRACK_CLOSE_WAIT: |
909 | return true; |
910 | default: |
911 | break; |
912 | } |
913 | |
914 | return false; |
915 | } |
916 | |
917 | void nf_conntrack_tcp_set_closing(struct nf_conn *ct) |
918 | { |
919 | enum tcp_conntrack old_state; |
920 | const unsigned int *timeouts; |
921 | u32 timeout; |
922 | |
923 | if (!nf_ct_is_confirmed(ct)) |
924 | return; |
925 | |
926 | spin_lock_bh(lock: &ct->lock); |
927 | old_state = ct->proto.tcp.state; |
928 | ct->proto.tcp.state = TCP_CONNTRACK_CLOSE; |
929 | |
930 | if (old_state == TCP_CONNTRACK_CLOSE || |
931 | test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status)) { |
932 | spin_unlock_bh(lock: &ct->lock); |
933 | return; |
934 | } |
935 | |
936 | timeouts = nf_ct_timeout_lookup(ct); |
937 | if (!timeouts) { |
938 | const struct nf_tcp_net *tn; |
939 | |
940 | tn = nf_tcp_pernet(net: nf_ct_net(ct)); |
941 | timeouts = tn->timeouts; |
942 | } |
943 | |
944 | timeout = timeouts[TCP_CONNTRACK_CLOSE]; |
945 | WRITE_ONCE(ct->timeout, timeout + nfct_time_stamp); |
946 | |
947 | spin_unlock_bh(lock: &ct->lock); |
948 | |
949 | nf_conntrack_event_cache(event: IPCT_PROTOINFO, ct); |
950 | } |
951 | |
952 | static void nf_ct_tcp_state_reset(struct ip_ct_tcp_state *state) |
953 | { |
954 | state->td_end = 0; |
955 | state->td_maxend = 0; |
956 | state->td_maxwin = 0; |
957 | state->td_maxack = 0; |
958 | state->td_scale = 0; |
959 | state->flags &= IP_CT_TCP_FLAG_BE_LIBERAL; |
960 | } |
961 | |
962 | /* Returns verdict for packet, or -1 for invalid. */ |
963 | int nf_conntrack_tcp_packet(struct nf_conn *ct, |
964 | struct sk_buff *skb, |
965 | unsigned int dataoff, |
966 | enum ip_conntrack_info ctinfo, |
967 | const struct nf_hook_state *state) |
968 | { |
969 | struct net *net = nf_ct_net(ct); |
970 | struct nf_tcp_net *tn = nf_tcp_pernet(net); |
971 | enum tcp_conntrack new_state, old_state; |
972 | unsigned int index, *timeouts; |
973 | enum nf_ct_tcp_action res; |
974 | enum ip_conntrack_dir dir; |
975 | const struct tcphdr *th; |
976 | struct tcphdr _tcph; |
977 | unsigned long timeout; |
978 | |
979 | th = skb_header_pointer(skb, offset: dataoff, len: sizeof(_tcph), buffer: &_tcph); |
980 | if (th == NULL) |
981 | return -NF_ACCEPT; |
982 | |
983 | if (tcp_error(th, skb, dataoff, state)) |
984 | return -NF_ACCEPT; |
985 | |
986 | if (!nf_ct_is_confirmed(ct) && !tcp_new(ct, skb, dataoff, th, state)) |
987 | return -NF_ACCEPT; |
988 | |
989 | spin_lock_bh(lock: &ct->lock); |
990 | old_state = ct->proto.tcp.state; |
991 | dir = CTINFO2DIR(ctinfo); |
992 | index = get_conntrack_index(tcph: th); |
993 | new_state = tcp_conntracks[dir][index][old_state]; |
994 | |
995 | switch (new_state) { |
996 | case TCP_CONNTRACK_SYN_SENT: |
997 | if (old_state < TCP_CONNTRACK_TIME_WAIT) |
998 | break; |
999 | /* RFC 1122: "When a connection is closed actively, |
1000 | * it MUST linger in TIME-WAIT state for a time 2xMSL |
1001 | * (Maximum Segment Lifetime). However, it MAY accept |
1002 | * a new SYN from the remote TCP to reopen the connection |
1003 | * directly from TIME-WAIT state, if..." |
1004 | * We ignore the conditions because we are in the |
1005 | * TIME-WAIT state anyway. |
1006 | * |
1007 | * Handle aborted connections: we and the server |
1008 | * think there is an existing connection but the client |
1009 | * aborts it and starts a new one. |
1010 | */ |
1011 | if (((ct->proto.tcp.seen[dir].flags |
1012 | | ct->proto.tcp.seen[!dir].flags) |
1013 | & IP_CT_TCP_FLAG_CLOSE_INIT) |
1014 | || (ct->proto.tcp.last_dir == dir |
1015 | && ct->proto.tcp.last_index == TCP_RST_SET)) { |
1016 | /* Attempt to reopen a closed/aborted connection. |
1017 | * Delete this connection and look up again. */ |
1018 | spin_unlock_bh(lock: &ct->lock); |
1019 | |
1020 | /* Only repeat if we can actually remove the timer. |
1021 | * Destruction may already be in progress in process |
1022 | * context and we must give it a chance to terminate. |
1023 | */ |
1024 | if (nf_ct_kill(ct)) |
1025 | return -NF_REPEAT; |
1026 | return NF_DROP; |
1027 | } |
1028 | fallthrough; |
1029 | case TCP_CONNTRACK_IGNORE: |
1030 | /* Ignored packets: |
1031 | * |
1032 | * Our connection entry may be out of sync, so ignore |
1033 | * packets which may signal the real connection between |
1034 | * the client and the server. |
1035 | * |
1036 | * a) SYN in ORIGINAL |
1037 | * b) SYN/ACK in REPLY |
1038 | * c) ACK in reply direction after initial SYN in original. |
1039 | * |
1040 | * If the ignored packet is invalid, the receiver will send |
1041 | * a RST we'll catch below. |
1042 | */ |
1043 | if (index == TCP_SYNACK_SET |
1044 | && ct->proto.tcp.last_index == TCP_SYN_SET |
1045 | && ct->proto.tcp.last_dir != dir |
1046 | && ntohl(th->ack_seq) == ct->proto.tcp.last_end) { |
1047 | /* b) This SYN/ACK acknowledges a SYN that we earlier |
1048 | * ignored as invalid. This means that the client and |
1049 | * the server are both in sync, while the firewall is |
1050 | * not. We get in sync from the previously annotated |
1051 | * values. |
1052 | */ |
1053 | old_state = TCP_CONNTRACK_SYN_SENT; |
1054 | new_state = TCP_CONNTRACK_SYN_RECV; |
1055 | ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end = |
1056 | ct->proto.tcp.last_end; |
1057 | ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend = |
1058 | ct->proto.tcp.last_end; |
1059 | ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin = |
1060 | ct->proto.tcp.last_win == 0 ? |
1061 | 1 : ct->proto.tcp.last_win; |
1062 | ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale = |
1063 | ct->proto.tcp.last_wscale; |
1064 | ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK; |
1065 | ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags = |
1066 | ct->proto.tcp.last_flags; |
1067 | nf_ct_tcp_state_reset(state: &ct->proto.tcp.seen[dir]); |
1068 | break; |
1069 | } |
1070 | ct->proto.tcp.last_index = index; |
1071 | ct->proto.tcp.last_dir = dir; |
1072 | ct->proto.tcp.last_seq = ntohl(th->seq); |
1073 | ct->proto.tcp.last_end = |
1074 | segment_seq_plus_len(ntohl(th->seq), len: skb->len, dataoff, tcph: th); |
1075 | ct->proto.tcp.last_win = ntohs(th->window); |
1076 | |
1077 | /* a) This is a SYN in ORIGINAL. The client and the server |
1078 | * may be in sync but we are not. In that case, we annotate |
1079 | * the TCP options and let the packet go through. If it is a |
1080 | * valid SYN packet, the server will reply with a SYN/ACK, and |
1081 | * then we'll get in sync. Otherwise, the server potentially |
1082 | * responds with a challenge ACK if implementing RFC5961. |
1083 | */ |
1084 | if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) { |
1085 | struct ip_ct_tcp_state seen = {}; |
1086 | |
1087 | ct->proto.tcp.last_flags = |
1088 | ct->proto.tcp.last_wscale = 0; |
1089 | tcp_options(skb, dataoff, tcph: th, state: &seen); |
1090 | if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) { |
1091 | ct->proto.tcp.last_flags |= |
1092 | IP_CT_TCP_FLAG_WINDOW_SCALE; |
1093 | ct->proto.tcp.last_wscale = seen.td_scale; |
1094 | } |
1095 | if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) { |
1096 | ct->proto.tcp.last_flags |= |
1097 | IP_CT_TCP_FLAG_SACK_PERM; |
1098 | } |
1099 | /* Mark the potential for RFC5961 challenge ACK, |
1100 | * this pose a special problem for LAST_ACK state |
1101 | * as ACK is intrepretated as ACKing last FIN. |
1102 | */ |
1103 | if (old_state == TCP_CONNTRACK_LAST_ACK) |
1104 | ct->proto.tcp.last_flags |= |
1105 | IP_CT_EXP_CHALLENGE_ACK; |
1106 | } |
1107 | |
1108 | /* possible challenge ack reply to syn */ |
1109 | if (old_state == TCP_CONNTRACK_SYN_SENT && |
1110 | index == TCP_ACK_SET && |
1111 | dir == IP_CT_DIR_REPLY) |
1112 | ct->proto.tcp.last_ack = ntohl(th->ack_seq); |
1113 | |
1114 | spin_unlock_bh(lock: &ct->lock); |
1115 | nf_ct_l4proto_log_invalid(skb, ct, state, |
1116 | fmt: "packet (index %d) in dir %d ignored, state %s" , |
1117 | index, dir, |
1118 | tcp_conntrack_names[old_state]); |
1119 | return NF_ACCEPT; |
1120 | case TCP_CONNTRACK_MAX: |
1121 | /* Special case for SYN proxy: when the SYN to the server or |
1122 | * the SYN/ACK from the server is lost, the client may transmit |
1123 | * a keep-alive packet while in SYN_SENT state. This needs to |
1124 | * be associated with the original conntrack entry in order to |
1125 | * generate a new SYN with the correct sequence number. |
1126 | */ |
1127 | if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT && |
1128 | index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL && |
1129 | ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL && |
1130 | ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) { |
1131 | pr_debug("nf_ct_tcp: SYN proxy client keep alive\n" ); |
1132 | spin_unlock_bh(lock: &ct->lock); |
1133 | return NF_ACCEPT; |
1134 | } |
1135 | |
1136 | /* Invalid packet */ |
1137 | spin_unlock_bh(lock: &ct->lock); |
1138 | nf_ct_l4proto_log_invalid(skb, ct, state, |
1139 | fmt: "packet (index %d) in dir %d invalid, state %s" , |
1140 | index, dir, |
1141 | tcp_conntrack_names[old_state]); |
1142 | return -NF_ACCEPT; |
1143 | case TCP_CONNTRACK_TIME_WAIT: |
1144 | /* RFC5961 compliance cause stack to send "challenge-ACK" |
1145 | * e.g. in response to spurious SYNs. Conntrack MUST |
1146 | * not believe this ACK is acking last FIN. |
1147 | */ |
1148 | if (old_state == TCP_CONNTRACK_LAST_ACK && |
1149 | index == TCP_ACK_SET && |
1150 | ct->proto.tcp.last_dir != dir && |
1151 | ct->proto.tcp.last_index == TCP_SYN_SET && |
1152 | (ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) { |
1153 | /* Detected RFC5961 challenge ACK */ |
1154 | ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK; |
1155 | spin_unlock_bh(lock: &ct->lock); |
1156 | nf_ct_l4proto_log_invalid(skb, ct, state, fmt: "challenge-ack ignored" ); |
1157 | return NF_ACCEPT; /* Don't change state */ |
1158 | } |
1159 | break; |
1160 | case TCP_CONNTRACK_SYN_SENT2: |
1161 | /* tcp_conntracks table is not smart enough to handle |
1162 | * simultaneous open. |
1163 | */ |
1164 | ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN; |
1165 | break; |
1166 | case TCP_CONNTRACK_SYN_RECV: |
1167 | if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET && |
1168 | ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN) |
1169 | new_state = TCP_CONNTRACK_ESTABLISHED; |
1170 | break; |
1171 | case TCP_CONNTRACK_CLOSE: |
1172 | if (index != TCP_RST_SET) |
1173 | break; |
1174 | |
1175 | /* If we are closing, tuple might have been re-used already. |
1176 | * last_index, last_ack, and all other ct fields used for |
1177 | * sequence/window validation are outdated in that case. |
1178 | * |
1179 | * As the conntrack can already be expired by GC under pressure, |
1180 | * just skip validation checks. |
1181 | */ |
1182 | if (tcp_can_early_drop(ct)) |
1183 | goto in_window; |
1184 | |
1185 | /* td_maxack might be outdated if we let a SYN through earlier */ |
1186 | if ((ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) && |
1187 | ct->proto.tcp.last_index != TCP_SYN_SET) { |
1188 | u32 seq = ntohl(th->seq); |
1189 | |
1190 | /* If we are not in established state and SEQ=0 this is most |
1191 | * likely an answer to a SYN we let go through above (last_index |
1192 | * can be updated due to out-of-order ACKs). |
1193 | */ |
1194 | if (seq == 0 && !nf_conntrack_tcp_established(ct)) |
1195 | break; |
1196 | |
1197 | if (before(seq1: seq, seq2: ct->proto.tcp.seen[!dir].td_maxack) && |
1198 | !tn->tcp_ignore_invalid_rst) { |
1199 | /* Invalid RST */ |
1200 | spin_unlock_bh(lock: &ct->lock); |
1201 | nf_ct_l4proto_log_invalid(skb, ct, state, fmt: "invalid rst" ); |
1202 | return -NF_ACCEPT; |
1203 | } |
1204 | |
1205 | if (!nf_conntrack_tcp_established(ct) || |
1206 | seq == ct->proto.tcp.seen[!dir].td_maxack) |
1207 | break; |
1208 | |
1209 | /* Check if rst is part of train, such as |
1210 | * foo:80 > bar:4379: P, 235946583:235946602(19) ack 42 |
1211 | * foo:80 > bar:4379: R, 235946602:235946602(0) ack 42 |
1212 | */ |
1213 | if (ct->proto.tcp.last_index == TCP_ACK_SET && |
1214 | ct->proto.tcp.last_dir == dir && |
1215 | seq == ct->proto.tcp.last_end) |
1216 | break; |
1217 | |
1218 | /* ... RST sequence number doesn't match exactly, keep |
1219 | * established state to allow a possible challenge ACK. |
1220 | */ |
1221 | new_state = old_state; |
1222 | } |
1223 | if (((test_bit(IPS_SEEN_REPLY_BIT, &ct->status) |
1224 | && ct->proto.tcp.last_index == TCP_SYN_SET) |
1225 | || (!test_bit(IPS_ASSURED_BIT, &ct->status) |
1226 | && ct->proto.tcp.last_index == TCP_ACK_SET)) |
1227 | && ntohl(th->ack_seq) == ct->proto.tcp.last_end) { |
1228 | /* RST sent to invalid SYN or ACK we had let through |
1229 | * at a) and c) above: |
1230 | * |
1231 | * a) SYN was in window then |
1232 | * c) we hold a half-open connection. |
1233 | * |
1234 | * Delete our connection entry. |
1235 | * We skip window checking, because packet might ACK |
1236 | * segments we ignored. */ |
1237 | goto in_window; |
1238 | } |
1239 | |
1240 | /* Reset in response to a challenge-ack we let through earlier */ |
1241 | if (old_state == TCP_CONNTRACK_SYN_SENT && |
1242 | ct->proto.tcp.last_index == TCP_ACK_SET && |
1243 | ct->proto.tcp.last_dir == IP_CT_DIR_REPLY && |
1244 | ntohl(th->seq) == ct->proto.tcp.last_ack) |
1245 | goto in_window; |
1246 | |
1247 | break; |
1248 | default: |
1249 | /* Keep compilers happy. */ |
1250 | break; |
1251 | } |
1252 | |
1253 | res = tcp_in_window(ct, dir, index, |
1254 | skb, dataoff, tcph: th, hook_state: state); |
1255 | switch (res) { |
1256 | case NFCT_TCP_IGNORE: |
1257 | spin_unlock_bh(lock: &ct->lock); |
1258 | return NF_ACCEPT; |
1259 | case NFCT_TCP_INVALID: |
1260 | nf_tcp_handle_invalid(ct, dir, index, skb, hook_state: state); |
1261 | spin_unlock_bh(lock: &ct->lock); |
1262 | return -NF_ACCEPT; |
1263 | case NFCT_TCP_ACCEPT: |
1264 | break; |
1265 | } |
1266 | in_window: |
1267 | /* From now on we have got in-window packets */ |
1268 | ct->proto.tcp.last_index = index; |
1269 | ct->proto.tcp.last_dir = dir; |
1270 | |
1271 | ct->proto.tcp.state = new_state; |
1272 | if (old_state != new_state |
1273 | && new_state == TCP_CONNTRACK_FIN_WAIT) |
1274 | ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT; |
1275 | |
1276 | timeouts = nf_ct_timeout_lookup(ct); |
1277 | if (!timeouts) |
1278 | timeouts = tn->timeouts; |
1279 | |
1280 | if (ct->proto.tcp.retrans >= tn->tcp_max_retrans && |
1281 | timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS]) |
1282 | timeout = timeouts[TCP_CONNTRACK_RETRANS]; |
1283 | else if (unlikely(index == TCP_RST_SET)) |
1284 | timeout = timeouts[TCP_CONNTRACK_CLOSE]; |
1285 | else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) & |
1286 | IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED && |
1287 | timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK]) |
1288 | timeout = timeouts[TCP_CONNTRACK_UNACK]; |
1289 | else if (ct->proto.tcp.last_win == 0 && |
1290 | timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS]) |
1291 | timeout = timeouts[TCP_CONNTRACK_RETRANS]; |
1292 | else |
1293 | timeout = timeouts[new_state]; |
1294 | spin_unlock_bh(lock: &ct->lock); |
1295 | |
1296 | if (new_state != old_state) |
1297 | nf_conntrack_event_cache(event: IPCT_PROTOINFO, ct); |
1298 | |
1299 | if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { |
1300 | /* If only reply is a RST, we can consider ourselves not to |
1301 | have an established connection: this is a fairly common |
1302 | problem case, so we can delete the conntrack |
1303 | immediately. --RR */ |
1304 | if (th->rst) { |
1305 | nf_ct_kill_acct(ct, ctinfo, skb); |
1306 | return NF_ACCEPT; |
1307 | } |
1308 | |
1309 | if (index == TCP_SYN_SET && old_state == TCP_CONNTRACK_SYN_SENT) { |
1310 | /* do not renew timeout on SYN retransmit. |
1311 | * |
1312 | * Else port reuse by client or NAT middlebox can keep |
1313 | * entry alive indefinitely (including nat info). |
1314 | */ |
1315 | return NF_ACCEPT; |
1316 | } |
1317 | |
1318 | /* ESTABLISHED without SEEN_REPLY, i.e. mid-connection |
1319 | * pickup with loose=1. Avoid large ESTABLISHED timeout. |
1320 | */ |
1321 | if (new_state == TCP_CONNTRACK_ESTABLISHED && |
1322 | timeout > timeouts[TCP_CONNTRACK_UNACK]) |
1323 | timeout = timeouts[TCP_CONNTRACK_UNACK]; |
1324 | } else if (!test_bit(IPS_ASSURED_BIT, &ct->status) |
1325 | && (old_state == TCP_CONNTRACK_SYN_RECV |
1326 | || old_state == TCP_CONNTRACK_ESTABLISHED) |
1327 | && new_state == TCP_CONNTRACK_ESTABLISHED) { |
1328 | /* Set ASSURED if we see valid ack in ESTABLISHED |
1329 | after SYN_RECV or a valid answer for a picked up |
1330 | connection. */ |
1331 | set_bit(nr: IPS_ASSURED_BIT, addr: &ct->status); |
1332 | nf_conntrack_event_cache(event: IPCT_ASSURED, ct); |
1333 | } |
1334 | nf_ct_refresh_acct(ct, ctinfo, skb, extra_jiffies: timeout); |
1335 | |
1336 | return NF_ACCEPT; |
1337 | } |
1338 | |
1339 | #if IS_ENABLED(CONFIG_NF_CT_NETLINK) |
1340 | |
1341 | #include <linux/netfilter/nfnetlink.h> |
1342 | #include <linux/netfilter/nfnetlink_conntrack.h> |
1343 | |
1344 | static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla, |
1345 | struct nf_conn *ct, bool destroy) |
1346 | { |
1347 | struct nlattr *nest_parms; |
1348 | struct nf_ct_tcp_flags tmp = {}; |
1349 | |
1350 | spin_lock_bh(lock: &ct->lock); |
1351 | nest_parms = nla_nest_start(skb, attrtype: CTA_PROTOINFO_TCP); |
1352 | if (!nest_parms) |
1353 | goto nla_put_failure; |
1354 | |
1355 | if (nla_put_u8(skb, attrtype: CTA_PROTOINFO_TCP_STATE, value: ct->proto.tcp.state)) |
1356 | goto nla_put_failure; |
1357 | |
1358 | if (destroy) |
1359 | goto skip_state; |
1360 | |
1361 | if (nla_put_u8(skb, attrtype: CTA_PROTOINFO_TCP_WSCALE_ORIGINAL, |
1362 | value: ct->proto.tcp.seen[0].td_scale) || |
1363 | nla_put_u8(skb, attrtype: CTA_PROTOINFO_TCP_WSCALE_REPLY, |
1364 | value: ct->proto.tcp.seen[1].td_scale)) |
1365 | goto nla_put_failure; |
1366 | |
1367 | tmp.flags = ct->proto.tcp.seen[0].flags; |
1368 | if (nla_put(skb, attrtype: CTA_PROTOINFO_TCP_FLAGS_ORIGINAL, |
1369 | attrlen: sizeof(struct nf_ct_tcp_flags), data: &tmp)) |
1370 | goto nla_put_failure; |
1371 | |
1372 | tmp.flags = ct->proto.tcp.seen[1].flags; |
1373 | if (nla_put(skb, attrtype: CTA_PROTOINFO_TCP_FLAGS_REPLY, |
1374 | attrlen: sizeof(struct nf_ct_tcp_flags), data: &tmp)) |
1375 | goto nla_put_failure; |
1376 | skip_state: |
1377 | spin_unlock_bh(lock: &ct->lock); |
1378 | nla_nest_end(skb, start: nest_parms); |
1379 | |
1380 | return 0; |
1381 | |
1382 | nla_put_failure: |
1383 | spin_unlock_bh(lock: &ct->lock); |
1384 | return -1; |
1385 | } |
1386 | |
1387 | static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = { |
1388 | [CTA_PROTOINFO_TCP_STATE] = { .type = NLA_U8 }, |
1389 | [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 }, |
1390 | [CTA_PROTOINFO_TCP_WSCALE_REPLY] = { .type = NLA_U8 }, |
1391 | [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL] = { .len = sizeof(struct nf_ct_tcp_flags) }, |
1392 | [CTA_PROTOINFO_TCP_FLAGS_REPLY] = { .len = sizeof(struct nf_ct_tcp_flags) }, |
1393 | }; |
1394 | |
1395 | #define TCP_NLATTR_SIZE ( \ |
1396 | NLA_ALIGN(NLA_HDRLEN + 1) + \ |
1397 | NLA_ALIGN(NLA_HDRLEN + 1) + \ |
1398 | NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)) + \ |
1399 | NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags))) |
1400 | |
1401 | static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct) |
1402 | { |
1403 | struct nlattr *pattr = cda[CTA_PROTOINFO_TCP]; |
1404 | struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1]; |
1405 | int err; |
1406 | |
1407 | /* updates could not contain anything about the private |
1408 | * protocol info, in that case skip the parsing */ |
1409 | if (!pattr) |
1410 | return 0; |
1411 | |
1412 | err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_TCP_MAX, nla: pattr, |
1413 | policy: tcp_nla_policy, NULL); |
1414 | if (err < 0) |
1415 | return err; |
1416 | |
1417 | if (tb[CTA_PROTOINFO_TCP_STATE] && |
1418 | nla_get_u8(nla: tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX) |
1419 | return -EINVAL; |
1420 | |
1421 | spin_lock_bh(lock: &ct->lock); |
1422 | if (tb[CTA_PROTOINFO_TCP_STATE]) |
1423 | ct->proto.tcp.state = nla_get_u8(nla: tb[CTA_PROTOINFO_TCP_STATE]); |
1424 | |
1425 | if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) { |
1426 | struct nf_ct_tcp_flags *attr = |
1427 | nla_data(nla: tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]); |
1428 | ct->proto.tcp.seen[0].flags &= ~attr->mask; |
1429 | ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask; |
1430 | } |
1431 | |
1432 | if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) { |
1433 | struct nf_ct_tcp_flags *attr = |
1434 | nla_data(nla: tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]); |
1435 | ct->proto.tcp.seen[1].flags &= ~attr->mask; |
1436 | ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask; |
1437 | } |
1438 | |
1439 | if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] && |
1440 | tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] && |
1441 | ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE && |
1442 | ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) { |
1443 | ct->proto.tcp.seen[0].td_scale = |
1444 | nla_get_u8(nla: tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]); |
1445 | ct->proto.tcp.seen[1].td_scale = |
1446 | nla_get_u8(nla: tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]); |
1447 | } |
1448 | spin_unlock_bh(lock: &ct->lock); |
1449 | |
1450 | return 0; |
1451 | } |
1452 | |
1453 | static unsigned int tcp_nlattr_tuple_size(void) |
1454 | { |
1455 | static unsigned int size __read_mostly; |
1456 | |
1457 | if (!size) |
1458 | size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1); |
1459 | |
1460 | return size; |
1461 | } |
1462 | #endif |
1463 | |
1464 | #ifdef CONFIG_NF_CONNTRACK_TIMEOUT |
1465 | |
1466 | #include <linux/netfilter/nfnetlink.h> |
1467 | #include <linux/netfilter/nfnetlink_cttimeout.h> |
1468 | |
1469 | static int tcp_timeout_nlattr_to_obj(struct nlattr *tb[], |
1470 | struct net *net, void *data) |
1471 | { |
1472 | struct nf_tcp_net *tn = nf_tcp_pernet(net); |
1473 | unsigned int *timeouts = data; |
1474 | int i; |
1475 | |
1476 | if (!timeouts) |
1477 | timeouts = tn->timeouts; |
1478 | /* set default TCP timeouts. */ |
1479 | for (i=0; i<TCP_CONNTRACK_TIMEOUT_MAX; i++) |
1480 | timeouts[i] = tn->timeouts[i]; |
1481 | |
1482 | if (tb[CTA_TIMEOUT_TCP_SYN_SENT]) { |
1483 | timeouts[TCP_CONNTRACK_SYN_SENT] = |
1484 | ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT]))*HZ; |
1485 | } |
1486 | |
1487 | if (tb[CTA_TIMEOUT_TCP_SYN_RECV]) { |
1488 | timeouts[TCP_CONNTRACK_SYN_RECV] = |
1489 | ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_RECV]))*HZ; |
1490 | } |
1491 | if (tb[CTA_TIMEOUT_TCP_ESTABLISHED]) { |
1492 | timeouts[TCP_CONNTRACK_ESTABLISHED] = |
1493 | ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_ESTABLISHED]))*HZ; |
1494 | } |
1495 | if (tb[CTA_TIMEOUT_TCP_FIN_WAIT]) { |
1496 | timeouts[TCP_CONNTRACK_FIN_WAIT] = |
1497 | ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_FIN_WAIT]))*HZ; |
1498 | } |
1499 | if (tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]) { |
1500 | timeouts[TCP_CONNTRACK_CLOSE_WAIT] = |
1501 | ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]))*HZ; |
1502 | } |
1503 | if (tb[CTA_TIMEOUT_TCP_LAST_ACK]) { |
1504 | timeouts[TCP_CONNTRACK_LAST_ACK] = |
1505 | ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_LAST_ACK]))*HZ; |
1506 | } |
1507 | if (tb[CTA_TIMEOUT_TCP_TIME_WAIT]) { |
1508 | timeouts[TCP_CONNTRACK_TIME_WAIT] = |
1509 | ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_TIME_WAIT]))*HZ; |
1510 | } |
1511 | if (tb[CTA_TIMEOUT_TCP_CLOSE]) { |
1512 | timeouts[TCP_CONNTRACK_CLOSE] = |
1513 | ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE]))*HZ; |
1514 | } |
1515 | if (tb[CTA_TIMEOUT_TCP_SYN_SENT2]) { |
1516 | timeouts[TCP_CONNTRACK_SYN_SENT2] = |
1517 | ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT2]))*HZ; |
1518 | } |
1519 | if (tb[CTA_TIMEOUT_TCP_RETRANS]) { |
1520 | timeouts[TCP_CONNTRACK_RETRANS] = |
1521 | ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_RETRANS]))*HZ; |
1522 | } |
1523 | if (tb[CTA_TIMEOUT_TCP_UNACK]) { |
1524 | timeouts[TCP_CONNTRACK_UNACK] = |
1525 | ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_UNACK]))*HZ; |
1526 | } |
1527 | |
1528 | timeouts[CTA_TIMEOUT_TCP_UNSPEC] = timeouts[CTA_TIMEOUT_TCP_SYN_SENT]; |
1529 | return 0; |
1530 | } |
1531 | |
1532 | static int |
1533 | tcp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data) |
1534 | { |
1535 | const unsigned int *timeouts = data; |
1536 | |
1537 | if (nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_SYN_SENT, |
1538 | htonl(timeouts[TCP_CONNTRACK_SYN_SENT] / HZ)) || |
1539 | nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_SYN_RECV, |
1540 | htonl(timeouts[TCP_CONNTRACK_SYN_RECV] / HZ)) || |
1541 | nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_ESTABLISHED, |
1542 | htonl(timeouts[TCP_CONNTRACK_ESTABLISHED] / HZ)) || |
1543 | nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_FIN_WAIT, |
1544 | htonl(timeouts[TCP_CONNTRACK_FIN_WAIT] / HZ)) || |
1545 | nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_CLOSE_WAIT, |
1546 | htonl(timeouts[TCP_CONNTRACK_CLOSE_WAIT] / HZ)) || |
1547 | nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_LAST_ACK, |
1548 | htonl(timeouts[TCP_CONNTRACK_LAST_ACK] / HZ)) || |
1549 | nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_TIME_WAIT, |
1550 | htonl(timeouts[TCP_CONNTRACK_TIME_WAIT] / HZ)) || |
1551 | nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_CLOSE, |
1552 | htonl(timeouts[TCP_CONNTRACK_CLOSE] / HZ)) || |
1553 | nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_SYN_SENT2, |
1554 | htonl(timeouts[TCP_CONNTRACK_SYN_SENT2] / HZ)) || |
1555 | nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_RETRANS, |
1556 | htonl(timeouts[TCP_CONNTRACK_RETRANS] / HZ)) || |
1557 | nla_put_be32(skb, attrtype: CTA_TIMEOUT_TCP_UNACK, |
1558 | htonl(timeouts[TCP_CONNTRACK_UNACK] / HZ))) |
1559 | goto nla_put_failure; |
1560 | return 0; |
1561 | |
1562 | nla_put_failure: |
1563 | return -ENOSPC; |
1564 | } |
1565 | |
1566 | static const struct nla_policy tcp_timeout_nla_policy[CTA_TIMEOUT_TCP_MAX+1] = { |
1567 | [CTA_TIMEOUT_TCP_SYN_SENT] = { .type = NLA_U32 }, |
1568 | [CTA_TIMEOUT_TCP_SYN_RECV] = { .type = NLA_U32 }, |
1569 | [CTA_TIMEOUT_TCP_ESTABLISHED] = { .type = NLA_U32 }, |
1570 | [CTA_TIMEOUT_TCP_FIN_WAIT] = { .type = NLA_U32 }, |
1571 | [CTA_TIMEOUT_TCP_CLOSE_WAIT] = { .type = NLA_U32 }, |
1572 | [CTA_TIMEOUT_TCP_LAST_ACK] = { .type = NLA_U32 }, |
1573 | [CTA_TIMEOUT_TCP_TIME_WAIT] = { .type = NLA_U32 }, |
1574 | [CTA_TIMEOUT_TCP_CLOSE] = { .type = NLA_U32 }, |
1575 | [CTA_TIMEOUT_TCP_SYN_SENT2] = { .type = NLA_U32 }, |
1576 | [CTA_TIMEOUT_TCP_RETRANS] = { .type = NLA_U32 }, |
1577 | [CTA_TIMEOUT_TCP_UNACK] = { .type = NLA_U32 }, |
1578 | }; |
1579 | #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ |
1580 | |
1581 | void nf_conntrack_tcp_init_net(struct net *net) |
1582 | { |
1583 | struct nf_tcp_net *tn = nf_tcp_pernet(net); |
1584 | int i; |
1585 | |
1586 | for (i = 0; i < TCP_CONNTRACK_TIMEOUT_MAX; i++) |
1587 | tn->timeouts[i] = tcp_timeouts[i]; |
1588 | |
1589 | /* timeouts[0] is unused, make it same as SYN_SENT so |
1590 | * ->timeouts[0] contains 'new' timeout, like udp or icmp. |
1591 | */ |
1592 | tn->timeouts[0] = tcp_timeouts[TCP_CONNTRACK_SYN_SENT]; |
1593 | |
1594 | /* If it is set to zero, we disable picking up already established |
1595 | * connections. |
1596 | */ |
1597 | tn->tcp_loose = 1; |
1598 | |
1599 | /* "Be conservative in what you do, |
1600 | * be liberal in what you accept from others." |
1601 | * If it's non-zero, we mark only out of window RST segments as INVALID. |
1602 | */ |
1603 | tn->tcp_be_liberal = 0; |
1604 | |
1605 | /* If it's non-zero, we turn off RST sequence number check */ |
1606 | tn->tcp_ignore_invalid_rst = 0; |
1607 | |
1608 | /* Max number of the retransmitted packets without receiving an (acceptable) |
1609 | * ACK from the destination. If this number is reached, a shorter timer |
1610 | * will be started. |
1611 | */ |
1612 | tn->tcp_max_retrans = 3; |
1613 | |
1614 | #if IS_ENABLED(CONFIG_NF_FLOW_TABLE) |
1615 | tn->offload_timeout = 30 * HZ; |
1616 | #endif |
1617 | } |
1618 | |
1619 | const struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp = |
1620 | { |
1621 | .l4proto = IPPROTO_TCP, |
1622 | #ifdef CONFIG_NF_CONNTRACK_PROCFS |
1623 | .print_conntrack = tcp_print_conntrack, |
1624 | #endif |
1625 | .can_early_drop = tcp_can_early_drop, |
1626 | #if IS_ENABLED(CONFIG_NF_CT_NETLINK) |
1627 | .to_nlattr = tcp_to_nlattr, |
1628 | .from_nlattr = nlattr_to_tcp, |
1629 | .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr, |
1630 | .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple, |
1631 | .nlattr_tuple_size = tcp_nlattr_tuple_size, |
1632 | .nlattr_size = TCP_NLATTR_SIZE, |
1633 | .nla_policy = nf_ct_port_nla_policy, |
1634 | #endif |
1635 | #ifdef CONFIG_NF_CONNTRACK_TIMEOUT |
1636 | .ctnl_timeout = { |
1637 | .nlattr_to_obj = tcp_timeout_nlattr_to_obj, |
1638 | .obj_to_nlattr = tcp_timeout_obj_to_nlattr, |
1639 | .nlattr_max = CTA_TIMEOUT_TCP_MAX, |
1640 | .obj_size = sizeof(unsigned int) * |
1641 | TCP_CONNTRACK_TIMEOUT_MAX, |
1642 | .nla_policy = tcp_timeout_nla_policy, |
1643 | }, |
1644 | #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ |
1645 | }; |
1646 | |