Merge tag 'printk-for-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/printk...
[linux-2.6-microblaze.git] / net / netfilter / nf_conntrack_proto_tcp.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /* (C) 1999-2001 Paul `Rusty' Russell
3  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
4  * (C) 2002-2013 Jozsef Kadlecsik <kadlec@netfilter.org>
5  * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
6  */
7
8 #include <linux/types.h>
9 #include <linux/timer.h>
10 #include <linux/module.h>
11 #include <linux/in.h>
12 #include <linux/tcp.h>
13 #include <linux/spinlock.h>
14 #include <linux/skbuff.h>
15 #include <linux/ipv6.h>
16 #include <net/ip6_checksum.h>
17 #include <asm/unaligned.h>
18
19 #include <net/tcp.h>
20
21 #include <linux/netfilter.h>
22 #include <linux/netfilter_ipv4.h>
23 #include <linux/netfilter_ipv6.h>
24 #include <net/netfilter/nf_conntrack.h>
25 #include <net/netfilter/nf_conntrack_l4proto.h>
26 #include <net/netfilter/nf_conntrack_ecache.h>
27 #include <net/netfilter/nf_conntrack_seqadj.h>
28 #include <net/netfilter/nf_conntrack_synproxy.h>
29 #include <net/netfilter/nf_conntrack_timeout.h>
30 #include <net/netfilter/nf_log.h>
31 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
32 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
33
34 /* "Be conservative in what you do,
35     be liberal in what you accept from others."
36     If it's non-zero, we mark only out of window RST segments as INVALID. */
37 static int nf_ct_tcp_be_liberal __read_mostly = 0;
38
39 /* If it is set to zero, we disable picking up already established
40    connections. */
41 static int nf_ct_tcp_loose __read_mostly = 1;
42
43 /* Max number of the retransmitted packets without receiving an (acceptable)
44    ACK from the destination. If this number is reached, a shorter timer
45    will be started. */
46 static int nf_ct_tcp_max_retrans __read_mostly = 3;
47
48   /* FIXME: Examine ipfilter's timeouts and conntrack transitions more
49      closely.  They're more complex. --RR */
50
51 static const char *const tcp_conntrack_names[] = {
52         "NONE",
53         "SYN_SENT",
54         "SYN_RECV",
55         "ESTABLISHED",
56         "FIN_WAIT",
57         "CLOSE_WAIT",
58         "LAST_ACK",
59         "TIME_WAIT",
60         "CLOSE",
61         "SYN_SENT2",
62 };
63
64 #define SECS * HZ
65 #define MINS * 60 SECS
66 #define HOURS * 60 MINS
67 #define DAYS * 24 HOURS
68
69 static const unsigned int tcp_timeouts[TCP_CONNTRACK_TIMEOUT_MAX] = {
70         [TCP_CONNTRACK_SYN_SENT]        = 2 MINS,
71         [TCP_CONNTRACK_SYN_RECV]        = 60 SECS,
72         [TCP_CONNTRACK_ESTABLISHED]     = 5 DAYS,
73         [TCP_CONNTRACK_FIN_WAIT]        = 2 MINS,
74         [TCP_CONNTRACK_CLOSE_WAIT]      = 60 SECS,
75         [TCP_CONNTRACK_LAST_ACK]        = 30 SECS,
76         [TCP_CONNTRACK_TIME_WAIT]       = 2 MINS,
77         [TCP_CONNTRACK_CLOSE]           = 10 SECS,
78         [TCP_CONNTRACK_SYN_SENT2]       = 2 MINS,
79 /* RFC1122 says the R2 limit should be at least 100 seconds.
80    Linux uses 15 packets as limit, which corresponds
81    to ~13-30min depending on RTO. */
82         [TCP_CONNTRACK_RETRANS]         = 5 MINS,
83         [TCP_CONNTRACK_UNACK]           = 5 MINS,
84 };
85
86 #define sNO TCP_CONNTRACK_NONE
87 #define sSS TCP_CONNTRACK_SYN_SENT
88 #define sSR TCP_CONNTRACK_SYN_RECV
89 #define sES TCP_CONNTRACK_ESTABLISHED
90 #define sFW TCP_CONNTRACK_FIN_WAIT
91 #define sCW TCP_CONNTRACK_CLOSE_WAIT
92 #define sLA TCP_CONNTRACK_LAST_ACK
93 #define sTW TCP_CONNTRACK_TIME_WAIT
94 #define sCL TCP_CONNTRACK_CLOSE
95 #define sS2 TCP_CONNTRACK_SYN_SENT2
96 #define sIV TCP_CONNTRACK_MAX
97 #define sIG TCP_CONNTRACK_IGNORE
98
99 /* What TCP flags are set from RST/SYN/FIN/ACK. */
100 enum tcp_bit_set {
101         TCP_SYN_SET,
102         TCP_SYNACK_SET,
103         TCP_FIN_SET,
104         TCP_ACK_SET,
105         TCP_RST_SET,
106         TCP_NONE_SET,
107 };
108
109 /*
110  * The TCP state transition table needs a few words...
111  *
112  * We are the man in the middle. All the packets go through us
113  * but might get lost in transit to the destination.
114  * It is assumed that the destinations can't receive segments
115  * we haven't seen.
116  *
117  * The checked segment is in window, but our windows are *not*
118  * equivalent with the ones of the sender/receiver. We always
119  * try to guess the state of the current sender.
120  *
121  * The meaning of the states are:
122  *
123  * NONE:        initial state
124  * SYN_SENT:    SYN-only packet seen
125  * SYN_SENT2:   SYN-only packet seen from reply dir, simultaneous open
126  * SYN_RECV:    SYN-ACK packet seen
127  * ESTABLISHED: ACK packet seen
128  * FIN_WAIT:    FIN packet seen
129  * CLOSE_WAIT:  ACK seen (after FIN)
130  * LAST_ACK:    FIN seen (after FIN)
131  * TIME_WAIT:   last ACK seen
132  * CLOSE:       closed connection (RST)
133  *
134  * Packets marked as IGNORED (sIG):
135  *      if they may be either invalid or valid
136  *      and the receiver may send back a connection
137  *      closing RST or a SYN/ACK.
138  *
139  * Packets marked as INVALID (sIV):
140  *      if we regard them as truly invalid packets
141  */
142 static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
143         {
144 /* ORIGINAL */
145 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
146 /*syn*/    { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sS2 },
147 /*
148  *      sNO -> sSS      Initialize a new connection
149  *      sSS -> sSS      Retransmitted SYN
150  *      sS2 -> sS2      Late retransmitted SYN
151  *      sSR -> sIG
152  *      sES -> sIG      Error: SYNs in window outside the SYN_SENT state
153  *                      are errors. Receiver will reply with RST
154  *                      and close the connection.
155  *                      Or we are not in sync and hold a dead connection.
156  *      sFW -> sIG
157  *      sCW -> sIG
158  *      sLA -> sIG
159  *      sTW -> sSS      Reopened connection (RFC 1122).
160  *      sCL -> sSS
161  */
162 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
163 /*synack*/ { sIV, sIV, sSR, sIV, sIV, sIV, sIV, sIV, sIV, sSR },
164 /*
165  *      sNO -> sIV      Too late and no reason to do anything
166  *      sSS -> sIV      Client can't send SYN and then SYN/ACK
167  *      sS2 -> sSR      SYN/ACK sent to SYN2 in simultaneous open
168  *      sSR -> sSR      Late retransmitted SYN/ACK in simultaneous open
169  *      sES -> sIV      Invalid SYN/ACK packets sent by the client
170  *      sFW -> sIV
171  *      sCW -> sIV
172  *      sLA -> sIV
173  *      sTW -> sIV
174  *      sCL -> sIV
175  */
176 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
177 /*fin*/    { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
178 /*
179  *      sNO -> sIV      Too late and no reason to do anything...
180  *      sSS -> sIV      Client migth not send FIN in this state:
181  *                      we enforce waiting for a SYN/ACK reply first.
182  *      sS2 -> sIV
183  *      sSR -> sFW      Close started.
184  *      sES -> sFW
185  *      sFW -> sLA      FIN seen in both directions, waiting for
186  *                      the last ACK.
187  *                      Migth be a retransmitted FIN as well...
188  *      sCW -> sLA
189  *      sLA -> sLA      Retransmitted FIN. Remain in the same state.
190  *      sTW -> sTW
191  *      sCL -> sCL
192  */
193 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
194 /*ack*/    { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV },
195 /*
196  *      sNO -> sES      Assumed.
197  *      sSS -> sIV      ACK is invalid: we haven't seen a SYN/ACK yet.
198  *      sS2 -> sIV
199  *      sSR -> sES      Established state is reached.
200  *      sES -> sES      :-)
201  *      sFW -> sCW      Normal close request answered by ACK.
202  *      sCW -> sCW
203  *      sLA -> sTW      Last ACK detected (RFC5961 challenged)
204  *      sTW -> sTW      Retransmitted last ACK. Remain in the same state.
205  *      sCL -> sCL
206  */
207 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
208 /*rst*/    { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
209 /*none*/   { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
210         },
211         {
212 /* REPLY */
213 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
214 /*syn*/    { sIV, sS2, sIV, sIV, sIV, sIV, sIV, sSS, sIV, sS2 },
215 /*
216  *      sNO -> sIV      Never reached.
217  *      sSS -> sS2      Simultaneous open
218  *      sS2 -> sS2      Retransmitted simultaneous SYN
219  *      sSR -> sIV      Invalid SYN packets sent by the server
220  *      sES -> sIV
221  *      sFW -> sIV
222  *      sCW -> sIV
223  *      sLA -> sIV
224  *      sTW -> sSS      Reopened connection, but server may have switched role
225  *      sCL -> sIV
226  */
227 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
228 /*synack*/ { sIV, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIG, sSR },
229 /*
230  *      sSS -> sSR      Standard open.
231  *      sS2 -> sSR      Simultaneous open
232  *      sSR -> sIG      Retransmitted SYN/ACK, ignore it.
233  *      sES -> sIG      Late retransmitted SYN/ACK?
234  *      sFW -> sIG      Might be SYN/ACK answering ignored SYN
235  *      sCW -> sIG
236  *      sLA -> sIG
237  *      sTW -> sIG
238  *      sCL -> sIG
239  */
240 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
241 /*fin*/    { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
242 /*
243  *      sSS -> sIV      Server might not send FIN in this state.
244  *      sS2 -> sIV
245  *      sSR -> sFW      Close started.
246  *      sES -> sFW
247  *      sFW -> sLA      FIN seen in both directions.
248  *      sCW -> sLA
249  *      sLA -> sLA      Retransmitted FIN.
250  *      sTW -> sTW
251  *      sCL -> sCL
252  */
253 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
254 /*ack*/    { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIG },
255 /*
256  *      sSS -> sIG      Might be a half-open connection.
257  *      sS2 -> sIG
258  *      sSR -> sSR      Might answer late resent SYN.
259  *      sES -> sES      :-)
260  *      sFW -> sCW      Normal close request answered by ACK.
261  *      sCW -> sCW
262  *      sLA -> sTW      Last ACK detected (RFC5961 challenged)
263  *      sTW -> sTW      Retransmitted last ACK.
264  *      sCL -> sCL
265  */
266 /*           sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2   */
267 /*rst*/    { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
268 /*none*/   { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
269         }
270 };
271
272 #ifdef CONFIG_NF_CONNTRACK_PROCFS
273 /* Print out the private part of the conntrack. */
274 static void tcp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
275 {
276         if (test_bit(IPS_OFFLOAD_BIT, &ct->status))
277                 return;
278
279         seq_printf(s, "%s ", tcp_conntrack_names[ct->proto.tcp.state]);
280 }
281 #endif
282
283 static unsigned int get_conntrack_index(const struct tcphdr *tcph)
284 {
285         if (tcph->rst) return TCP_RST_SET;
286         else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET);
287         else if (tcph->fin) return TCP_FIN_SET;
288         else if (tcph->ack) return TCP_ACK_SET;
289         else return TCP_NONE_SET;
290 }
291
292 /* TCP connection tracking based on 'Real Stateful TCP Packet Filtering
293    in IP Filter' by Guido van Rooij.
294
295    http://www.sane.nl/events/sane2000/papers.html
296    http://www.darkart.com/mirrors/www.obfuscation.org/ipf/
297
298    The boundaries and the conditions are changed according to RFC793:
299    the packet must intersect the window (i.e. segments may be
300    after the right or before the left edge) and thus receivers may ACK
301    segments after the right edge of the window.
302
303         td_maxend = max(sack + max(win,1)) seen in reply packets
304         td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets
305         td_maxwin += seq + len - sender.td_maxend
306                         if seq + len > sender.td_maxend
307         td_end    = max(seq + len) seen in sent packets
308
309    I.   Upper bound for valid data:     seq <= sender.td_maxend
310    II.  Lower bound for valid data:     seq + len >= sender.td_end - receiver.td_maxwin
311    III. Upper bound for valid (s)ack:   sack <= receiver.td_end
312    IV.  Lower bound for valid (s)ack:   sack >= receiver.td_end - MAXACKWINDOW
313
314    where sack is the highest right edge of sack block found in the packet
315    or ack in the case of packet without SACK option.
316
317    The upper bound limit for a valid (s)ack is not ignored -
318    we doesn't have to deal with fragments.
319 */
320
321 static inline __u32 segment_seq_plus_len(__u32 seq,
322                                          size_t len,
323                                          unsigned int dataoff,
324                                          const struct tcphdr *tcph)
325 {
326         /* XXX Should I use payload length field in IP/IPv6 header ?
327          * - YK */
328         return (seq + len - dataoff - tcph->doff*4
329                 + (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0));
330 }
331
332 /* Fixme: what about big packets? */
333 #define MAXACKWINCONST                  66000
334 #define MAXACKWINDOW(sender)                                            \
335         ((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin     \
336                                               : MAXACKWINCONST)
337
338 /*
339  * Simplified tcp_parse_options routine from tcp_input.c
340  */
341 static void tcp_options(const struct sk_buff *skb,
342                         unsigned int dataoff,
343                         const struct tcphdr *tcph,
344                         struct ip_ct_tcp_state *state)
345 {
346         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
347         const unsigned char *ptr;
348         int length = (tcph->doff*4) - sizeof(struct tcphdr);
349
350         if (!length)
351                 return;
352
353         ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
354                                  length, buff);
355         BUG_ON(ptr == NULL);
356
357         state->td_scale =
358         state->flags = 0;
359
360         while (length > 0) {
361                 int opcode=*ptr++;
362                 int opsize;
363
364                 switch (opcode) {
365                 case TCPOPT_EOL:
366                         return;
367                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
368                         length--;
369                         continue;
370                 default:
371                         if (length < 2)
372                                 return;
373                         opsize=*ptr++;
374                         if (opsize < 2) /* "silly options" */
375                                 return;
376                         if (opsize > length)
377                                 return; /* don't parse partial options */
378
379                         if (opcode == TCPOPT_SACK_PERM
380                             && opsize == TCPOLEN_SACK_PERM)
381                                 state->flags |= IP_CT_TCP_FLAG_SACK_PERM;
382                         else if (opcode == TCPOPT_WINDOW
383                                  && opsize == TCPOLEN_WINDOW) {
384                                 state->td_scale = *(u_int8_t *)ptr;
385
386                                 if (state->td_scale > TCP_MAX_WSCALE)
387                                         state->td_scale = TCP_MAX_WSCALE;
388
389                                 state->flags |=
390                                         IP_CT_TCP_FLAG_WINDOW_SCALE;
391                         }
392                         ptr += opsize - 2;
393                         length -= opsize;
394                 }
395         }
396 }
397
398 static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
399                      const struct tcphdr *tcph, __u32 *sack)
400 {
401         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
402         const unsigned char *ptr;
403         int length = (tcph->doff*4) - sizeof(struct tcphdr);
404         __u32 tmp;
405
406         if (!length)
407                 return;
408
409         ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
410                                  length, buff);
411         BUG_ON(ptr == NULL);
412
413         /* Fast path for timestamp-only option */
414         if (length == TCPOLEN_TSTAMP_ALIGNED
415             && *(__be32 *)ptr == htonl((TCPOPT_NOP << 24)
416                                        | (TCPOPT_NOP << 16)
417                                        | (TCPOPT_TIMESTAMP << 8)
418                                        | TCPOLEN_TIMESTAMP))
419                 return;
420
421         while (length > 0) {
422                 int opcode = *ptr++;
423                 int opsize, i;
424
425                 switch (opcode) {
426                 case TCPOPT_EOL:
427                         return;
428                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
429                         length--;
430                         continue;
431                 default:
432                         if (length < 2)
433                                 return;
434                         opsize = *ptr++;
435                         if (opsize < 2) /* "silly options" */
436                                 return;
437                         if (opsize > length)
438                                 return; /* don't parse partial options */
439
440                         if (opcode == TCPOPT_SACK
441                             && opsize >= (TCPOLEN_SACK_BASE
442                                           + TCPOLEN_SACK_PERBLOCK)
443                             && !((opsize - TCPOLEN_SACK_BASE)
444                                  % TCPOLEN_SACK_PERBLOCK)) {
445                                 for (i = 0;
446                                      i < (opsize - TCPOLEN_SACK_BASE);
447                                      i += TCPOLEN_SACK_PERBLOCK) {
448                                         tmp = get_unaligned_be32((__be32 *)(ptr+i)+1);
449
450                                         if (after(tmp, *sack))
451                                                 *sack = tmp;
452                                 }
453                                 return;
454                         }
455                         ptr += opsize - 2;
456                         length -= opsize;
457                 }
458         }
459 }
460
461 static bool tcp_in_window(const struct nf_conn *ct,
462                           struct ip_ct_tcp *state,
463                           enum ip_conntrack_dir dir,
464                           unsigned int index,
465                           const struct sk_buff *skb,
466                           unsigned int dataoff,
467                           const struct tcphdr *tcph)
468 {
469         struct net *net = nf_ct_net(ct);
470         struct nf_tcp_net *tn = nf_tcp_pernet(net);
471         struct ip_ct_tcp_state *sender = &state->seen[dir];
472         struct ip_ct_tcp_state *receiver = &state->seen[!dir];
473         const struct nf_conntrack_tuple *tuple = &ct->tuplehash[dir].tuple;
474         __u32 seq, ack, sack, end, win, swin;
475         u16 win_raw;
476         s32 receiver_offset;
477         bool res, in_recv_win;
478
479         /*
480          * Get the required data from the packet.
481          */
482         seq = ntohl(tcph->seq);
483         ack = sack = ntohl(tcph->ack_seq);
484         win_raw = ntohs(tcph->window);
485         win = win_raw;
486         end = segment_seq_plus_len(seq, skb->len, dataoff, tcph);
487
488         if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
489                 tcp_sack(skb, dataoff, tcph, &sack);
490
491         /* Take into account NAT sequence number mangling */
492         receiver_offset = nf_ct_seq_offset(ct, !dir, ack - 1);
493         ack -= receiver_offset;
494         sack -= receiver_offset;
495
496         pr_debug("tcp_in_window: START\n");
497         pr_debug("tcp_in_window: ");
498         nf_ct_dump_tuple(tuple);
499         pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
500                  seq, ack, receiver_offset, sack, receiver_offset, win, end);
501         pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
502                  "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
503                  sender->td_end, sender->td_maxend, sender->td_maxwin,
504                  sender->td_scale,
505                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
506                  receiver->td_scale);
507
508         if (sender->td_maxwin == 0) {
509                 /*
510                  * Initialize sender data.
511                  */
512                 if (tcph->syn) {
513                         /*
514                          * SYN-ACK in reply to a SYN
515                          * or SYN from reply direction in simultaneous open.
516                          */
517                         sender->td_end =
518                         sender->td_maxend = end;
519                         sender->td_maxwin = (win == 0 ? 1 : win);
520
521                         tcp_options(skb, dataoff, tcph, sender);
522                         /*
523                          * RFC 1323:
524                          * Both sides must send the Window Scale option
525                          * to enable window scaling in either direction.
526                          */
527                         if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE
528                               && receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE))
529                                 sender->td_scale =
530                                 receiver->td_scale = 0;
531                         if (!tcph->ack)
532                                 /* Simultaneous open */
533                                 return true;
534                 } else {
535                         /*
536                          * We are in the middle of a connection,
537                          * its history is lost for us.
538                          * Let's try to use the data from the packet.
539                          */
540                         sender->td_end = end;
541                         swin = win << sender->td_scale;
542                         sender->td_maxwin = (swin == 0 ? 1 : swin);
543                         sender->td_maxend = end + sender->td_maxwin;
544                         if (receiver->td_maxwin == 0) {
545                                 /* We haven't seen traffic in the other
546                                  * direction yet but we have to tweak window
547                                  * tracking to pass III and IV until that
548                                  * happens.
549                                  */
550                                 receiver->td_end = receiver->td_maxend = sack;
551                         } else if (sack == receiver->td_end + 1) {
552                                 /* Likely a reply to a keepalive.
553                                  * Needed for III.
554                                  */
555                                 receiver->td_end++;
556                         }
557
558                 }
559         } else if (((state->state == TCP_CONNTRACK_SYN_SENT
560                      && dir == IP_CT_DIR_ORIGINAL)
561                    || (state->state == TCP_CONNTRACK_SYN_RECV
562                      && dir == IP_CT_DIR_REPLY))
563                    && after(end, sender->td_end)) {
564                 /*
565                  * RFC 793: "if a TCP is reinitialized ... then it need
566                  * not wait at all; it must only be sure to use sequence
567                  * numbers larger than those recently used."
568                  */
569                 sender->td_end =
570                 sender->td_maxend = end;
571                 sender->td_maxwin = (win == 0 ? 1 : win);
572
573                 tcp_options(skb, dataoff, tcph, sender);
574         }
575
576         if (!(tcph->ack)) {
577                 /*
578                  * If there is no ACK, just pretend it was set and OK.
579                  */
580                 ack = sack = receiver->td_end;
581         } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
582                     (TCP_FLAG_ACK|TCP_FLAG_RST))
583                    && (ack == 0)) {
584                 /*
585                  * Broken TCP stacks, that set ACK in RST packets as well
586                  * with zero ack value.
587                  */
588                 ack = sack = receiver->td_end;
589         }
590
591         if (tcph->rst && seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)
592                 /*
593                  * RST sent answering SYN.
594                  */
595                 seq = end = sender->td_end;
596
597         pr_debug("tcp_in_window: ");
598         nf_ct_dump_tuple(tuple);
599         pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
600                  seq, ack, receiver_offset, sack, receiver_offset, win, end);
601         pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
602                  "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
603                  sender->td_end, sender->td_maxend, sender->td_maxwin,
604                  sender->td_scale,
605                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
606                  receiver->td_scale);
607
608         /* Is the ending sequence in the receive window (if available)? */
609         in_recv_win = !receiver->td_maxwin ||
610                       after(end, sender->td_end - receiver->td_maxwin - 1);
611
612         pr_debug("tcp_in_window: I=%i II=%i III=%i IV=%i\n",
613                  before(seq, sender->td_maxend + 1),
614                  (in_recv_win ? 1 : 0),
615                  before(sack, receiver->td_end + 1),
616                  after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1));
617
618         if (before(seq, sender->td_maxend + 1) &&
619             in_recv_win &&
620             before(sack, receiver->td_end + 1) &&
621             after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1)) {
622                 /*
623                  * Take into account window scaling (RFC 1323).
624                  */
625                 if (!tcph->syn)
626                         win <<= sender->td_scale;
627
628                 /*
629                  * Update sender data.
630                  */
631                 swin = win + (sack - ack);
632                 if (sender->td_maxwin < swin)
633                         sender->td_maxwin = swin;
634                 if (after(end, sender->td_end)) {
635                         sender->td_end = end;
636                         sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
637                 }
638                 if (tcph->ack) {
639                         if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) {
640                                 sender->td_maxack = ack;
641                                 sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET;
642                         } else if (after(ack, sender->td_maxack))
643                                 sender->td_maxack = ack;
644                 }
645
646                 /*
647                  * Update receiver data.
648                  */
649                 if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
650                         receiver->td_maxwin += end - sender->td_maxend;
651                 if (after(sack + win, receiver->td_maxend - 1)) {
652                         receiver->td_maxend = sack + win;
653                         if (win == 0)
654                                 receiver->td_maxend++;
655                 }
656                 if (ack == receiver->td_end)
657                         receiver->flags &= ~IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
658
659                 /*
660                  * Check retransmissions.
661                  */
662                 if (index == TCP_ACK_SET) {
663                         if (state->last_dir == dir
664                             && state->last_seq == seq
665                             && state->last_ack == ack
666                             && state->last_end == end
667                             && state->last_win == win_raw)
668                                 state->retrans++;
669                         else {
670                                 state->last_dir = dir;
671                                 state->last_seq = seq;
672                                 state->last_ack = ack;
673                                 state->last_end = end;
674                                 state->last_win = win_raw;
675                                 state->retrans = 0;
676                         }
677                 }
678                 res = true;
679         } else {
680                 res = false;
681                 if (sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL ||
682                     tn->tcp_be_liberal)
683                         res = true;
684                 if (!res) {
685                         nf_ct_l4proto_log_invalid(skb, ct,
686                         "%s",
687                         before(seq, sender->td_maxend + 1) ?
688                         in_recv_win ?
689                         before(sack, receiver->td_end + 1) ?
690                         after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1) ? "BUG"
691                         : "ACK is under the lower bound (possible overly delayed ACK)"
692                         : "ACK is over the upper bound (ACKed data not seen yet)"
693                         : "SEQ is under the lower bound (already ACKed data retransmitted)"
694                         : "SEQ is over the upper bound (over the window of the receiver)");
695                 }
696         }
697
698         pr_debug("tcp_in_window: res=%u sender end=%u maxend=%u maxwin=%u "
699                  "receiver end=%u maxend=%u maxwin=%u\n",
700                  res, sender->td_end, sender->td_maxend, sender->td_maxwin,
701                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin);
702
703         return res;
704 }
705
706 /* table of valid flag combinations - PUSH, ECE and CWR are always valid */
707 static const u8 tcp_valid_flags[(TCPHDR_FIN|TCPHDR_SYN|TCPHDR_RST|TCPHDR_ACK|
708                                  TCPHDR_URG) + 1] =
709 {
710         [TCPHDR_SYN]                            = 1,
711         [TCPHDR_SYN|TCPHDR_URG]                 = 1,
712         [TCPHDR_SYN|TCPHDR_ACK]                 = 1,
713         [TCPHDR_RST]                            = 1,
714         [TCPHDR_RST|TCPHDR_ACK]                 = 1,
715         [TCPHDR_FIN|TCPHDR_ACK]                 = 1,
716         [TCPHDR_FIN|TCPHDR_ACK|TCPHDR_URG]      = 1,
717         [TCPHDR_ACK]                            = 1,
718         [TCPHDR_ACK|TCPHDR_URG]                 = 1,
719 };
720
721 static void tcp_error_log(const struct sk_buff *skb,
722                           const struct nf_hook_state *state,
723                           const char *msg)
724 {
725         nf_l4proto_log_invalid(skb, state->net, state->pf, IPPROTO_TCP, "%s", msg);
726 }
727
728 /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c.  */
729 static bool tcp_error(const struct tcphdr *th,
730                       struct sk_buff *skb,
731                       unsigned int dataoff,
732                       const struct nf_hook_state *state)
733 {
734         unsigned int tcplen = skb->len - dataoff;
735         u8 tcpflags;
736
737         /* Not whole TCP header or malformed packet */
738         if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
739                 tcp_error_log(skb, state, "truncated packet");
740                 return true;
741         }
742
743         /* Checksum invalid? Ignore.
744          * We skip checking packets on the outgoing path
745          * because the checksum is assumed to be correct.
746          */
747         /* FIXME: Source route IP option packets --RR */
748         if (state->net->ct.sysctl_checksum &&
749             state->hook == NF_INET_PRE_ROUTING &&
750             nf_checksum(skb, state->hook, dataoff, IPPROTO_TCP, state->pf)) {
751                 tcp_error_log(skb, state, "bad checksum");
752                 return true;
753         }
754
755         /* Check TCP flags. */
756         tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
757         if (!tcp_valid_flags[tcpflags]) {
758                 tcp_error_log(skb, state, "invalid tcp flag combination");
759                 return true;
760         }
761
762         return false;
763 }
764
765 static noinline bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
766                              unsigned int dataoff,
767                              const struct tcphdr *th)
768 {
769         enum tcp_conntrack new_state;
770         struct net *net = nf_ct_net(ct);
771         const struct nf_tcp_net *tn = nf_tcp_pernet(net);
772         const struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[0];
773         const struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[1];
774
775         /* Don't need lock here: this conntrack not in circulation yet */
776         new_state = tcp_conntracks[0][get_conntrack_index(th)][TCP_CONNTRACK_NONE];
777
778         /* Invalid: delete conntrack */
779         if (new_state >= TCP_CONNTRACK_MAX) {
780                 pr_debug("nf_ct_tcp: invalid new deleting.\n");
781                 return false;
782         }
783
784         if (new_state == TCP_CONNTRACK_SYN_SENT) {
785                 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
786                 /* SYN packet */
787                 ct->proto.tcp.seen[0].td_end =
788                         segment_seq_plus_len(ntohl(th->seq), skb->len,
789                                              dataoff, th);
790                 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
791                 if (ct->proto.tcp.seen[0].td_maxwin == 0)
792                         ct->proto.tcp.seen[0].td_maxwin = 1;
793                 ct->proto.tcp.seen[0].td_maxend =
794                         ct->proto.tcp.seen[0].td_end;
795
796                 tcp_options(skb, dataoff, th, &ct->proto.tcp.seen[0]);
797         } else if (tn->tcp_loose == 0) {
798                 /* Don't try to pick up connections. */
799                 return false;
800         } else {
801                 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
802                 /*
803                  * We are in the middle of a connection,
804                  * its history is lost for us.
805                  * Let's try to use the data from the packet.
806                  */
807                 ct->proto.tcp.seen[0].td_end =
808                         segment_seq_plus_len(ntohl(th->seq), skb->len,
809                                              dataoff, th);
810                 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
811                 if (ct->proto.tcp.seen[0].td_maxwin == 0)
812                         ct->proto.tcp.seen[0].td_maxwin = 1;
813                 ct->proto.tcp.seen[0].td_maxend =
814                         ct->proto.tcp.seen[0].td_end +
815                         ct->proto.tcp.seen[0].td_maxwin;
816
817                 /* We assume SACK and liberal window checking to handle
818                  * window scaling */
819                 ct->proto.tcp.seen[0].flags =
820                 ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
821                                               IP_CT_TCP_FLAG_BE_LIBERAL;
822         }
823
824         /* tcp_packet will set them */
825         ct->proto.tcp.last_index = TCP_NONE_SET;
826
827         pr_debug("%s: sender end=%u maxend=%u maxwin=%u scale=%i "
828                  "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
829                  __func__,
830                  sender->td_end, sender->td_maxend, sender->td_maxwin,
831                  sender->td_scale,
832                  receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
833                  receiver->td_scale);
834         return true;
835 }
836
837 /* Returns verdict for packet, or -1 for invalid. */
838 int nf_conntrack_tcp_packet(struct nf_conn *ct,
839                             struct sk_buff *skb,
840                             unsigned int dataoff,
841                             enum ip_conntrack_info ctinfo,
842                             const struct nf_hook_state *state)
843 {
844         struct net *net = nf_ct_net(ct);
845         struct nf_tcp_net *tn = nf_tcp_pernet(net);
846         struct nf_conntrack_tuple *tuple;
847         enum tcp_conntrack new_state, old_state;
848         unsigned int index, *timeouts;
849         enum ip_conntrack_dir dir;
850         const struct tcphdr *th;
851         struct tcphdr _tcph;
852         unsigned long timeout;
853
854         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
855         if (th == NULL)
856                 return -NF_ACCEPT;
857
858         if (tcp_error(th, skb, dataoff, state))
859                 return -NF_ACCEPT;
860
861         if (!nf_ct_is_confirmed(ct) && !tcp_new(ct, skb, dataoff, th))
862                 return -NF_ACCEPT;
863
864         spin_lock_bh(&ct->lock);
865         old_state = ct->proto.tcp.state;
866         dir = CTINFO2DIR(ctinfo);
867         index = get_conntrack_index(th);
868         new_state = tcp_conntracks[dir][index][old_state];
869         tuple = &ct->tuplehash[dir].tuple;
870
871         switch (new_state) {
872         case TCP_CONNTRACK_SYN_SENT:
873                 if (old_state < TCP_CONNTRACK_TIME_WAIT)
874                         break;
875                 /* RFC 1122: "When a connection is closed actively,
876                  * it MUST linger in TIME-WAIT state for a time 2xMSL
877                  * (Maximum Segment Lifetime). However, it MAY accept
878                  * a new SYN from the remote TCP to reopen the connection
879                  * directly from TIME-WAIT state, if..."
880                  * We ignore the conditions because we are in the
881                  * TIME-WAIT state anyway.
882                  *
883                  * Handle aborted connections: we and the server
884                  * think there is an existing connection but the client
885                  * aborts it and starts a new one.
886                  */
887                 if (((ct->proto.tcp.seen[dir].flags
888                       | ct->proto.tcp.seen[!dir].flags)
889                      & IP_CT_TCP_FLAG_CLOSE_INIT)
890                     || (ct->proto.tcp.last_dir == dir
891                         && ct->proto.tcp.last_index == TCP_RST_SET)) {
892                         /* Attempt to reopen a closed/aborted connection.
893                          * Delete this connection and look up again. */
894                         spin_unlock_bh(&ct->lock);
895
896                         /* Only repeat if we can actually remove the timer.
897                          * Destruction may already be in progress in process
898                          * context and we must give it a chance to terminate.
899                          */
900                         if (nf_ct_kill(ct))
901                                 return -NF_REPEAT;
902                         return NF_DROP;
903                 }
904                 fallthrough;
905         case TCP_CONNTRACK_IGNORE:
906                 /* Ignored packets:
907                  *
908                  * Our connection entry may be out of sync, so ignore
909                  * packets which may signal the real connection between
910                  * the client and the server.
911                  *
912                  * a) SYN in ORIGINAL
913                  * b) SYN/ACK in REPLY
914                  * c) ACK in reply direction after initial SYN in original.
915                  *
916                  * If the ignored packet is invalid, the receiver will send
917                  * a RST we'll catch below.
918                  */
919                 if (index == TCP_SYNACK_SET
920                     && ct->proto.tcp.last_index == TCP_SYN_SET
921                     && ct->proto.tcp.last_dir != dir
922                     && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
923                         /* b) This SYN/ACK acknowledges a SYN that we earlier
924                          * ignored as invalid. This means that the client and
925                          * the server are both in sync, while the firewall is
926                          * not. We get in sync from the previously annotated
927                          * values.
928                          */
929                         old_state = TCP_CONNTRACK_SYN_SENT;
930                         new_state = TCP_CONNTRACK_SYN_RECV;
931                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
932                                 ct->proto.tcp.last_end;
933                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
934                                 ct->proto.tcp.last_end;
935                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
936                                 ct->proto.tcp.last_win == 0 ?
937                                         1 : ct->proto.tcp.last_win;
938                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
939                                 ct->proto.tcp.last_wscale;
940                         ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
941                         ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
942                                 ct->proto.tcp.last_flags;
943                         memset(&ct->proto.tcp.seen[dir], 0,
944                                sizeof(struct ip_ct_tcp_state));
945                         break;
946                 }
947                 ct->proto.tcp.last_index = index;
948                 ct->proto.tcp.last_dir = dir;
949                 ct->proto.tcp.last_seq = ntohl(th->seq);
950                 ct->proto.tcp.last_end =
951                     segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
952                 ct->proto.tcp.last_win = ntohs(th->window);
953
954                 /* a) This is a SYN in ORIGINAL. The client and the server
955                  * may be in sync but we are not. In that case, we annotate
956                  * the TCP options and let the packet go through. If it is a
957                  * valid SYN packet, the server will reply with a SYN/ACK, and
958                  * then we'll get in sync. Otherwise, the server potentially
959                  * responds with a challenge ACK if implementing RFC5961.
960                  */
961                 if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
962                         struct ip_ct_tcp_state seen = {};
963
964                         ct->proto.tcp.last_flags =
965                         ct->proto.tcp.last_wscale = 0;
966                         tcp_options(skb, dataoff, th, &seen);
967                         if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
968                                 ct->proto.tcp.last_flags |=
969                                         IP_CT_TCP_FLAG_WINDOW_SCALE;
970                                 ct->proto.tcp.last_wscale = seen.td_scale;
971                         }
972                         if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
973                                 ct->proto.tcp.last_flags |=
974                                         IP_CT_TCP_FLAG_SACK_PERM;
975                         }
976                         /* Mark the potential for RFC5961 challenge ACK,
977                          * this pose a special problem for LAST_ACK state
978                          * as ACK is intrepretated as ACKing last FIN.
979                          */
980                         if (old_state == TCP_CONNTRACK_LAST_ACK)
981                                 ct->proto.tcp.last_flags |=
982                                         IP_CT_EXP_CHALLENGE_ACK;
983                 }
984                 spin_unlock_bh(&ct->lock);
985                 nf_ct_l4proto_log_invalid(skb, ct,
986                                           "packet (index %d) in dir %d ignored, state %s",
987                                           index, dir,
988                                           tcp_conntrack_names[old_state]);
989                 return NF_ACCEPT;
990         case TCP_CONNTRACK_MAX:
991                 /* Special case for SYN proxy: when the SYN to the server or
992                  * the SYN/ACK from the server is lost, the client may transmit
993                  * a keep-alive packet while in SYN_SENT state. This needs to
994                  * be associated with the original conntrack entry in order to
995                  * generate a new SYN with the correct sequence number.
996                  */
997                 if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
998                     index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
999                     ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
1000                     ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
1001                         pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
1002                         spin_unlock_bh(&ct->lock);
1003                         return NF_ACCEPT;
1004                 }
1005
1006                 /* Invalid packet */
1007                 pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
1008                          dir, get_conntrack_index(th), old_state);
1009                 spin_unlock_bh(&ct->lock);
1010                 nf_ct_l4proto_log_invalid(skb, ct, "invalid state");
1011                 return -NF_ACCEPT;
1012         case TCP_CONNTRACK_TIME_WAIT:
1013                 /* RFC5961 compliance cause stack to send "challenge-ACK"
1014                  * e.g. in response to spurious SYNs.  Conntrack MUST
1015                  * not believe this ACK is acking last FIN.
1016                  */
1017                 if (old_state == TCP_CONNTRACK_LAST_ACK &&
1018                     index == TCP_ACK_SET &&
1019                     ct->proto.tcp.last_dir != dir &&
1020                     ct->proto.tcp.last_index == TCP_SYN_SET &&
1021                     (ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
1022                         /* Detected RFC5961 challenge ACK */
1023                         ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1024                         spin_unlock_bh(&ct->lock);
1025                         nf_ct_l4proto_log_invalid(skb, ct, "challenge-ack ignored");
1026                         return NF_ACCEPT; /* Don't change state */
1027                 }
1028                 break;
1029         case TCP_CONNTRACK_SYN_SENT2:
1030                 /* tcp_conntracks table is not smart enough to handle
1031                  * simultaneous open.
1032                  */
1033                 ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN;
1034                 break;
1035         case TCP_CONNTRACK_SYN_RECV:
1036                 if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET &&
1037                     ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN)
1038                         new_state = TCP_CONNTRACK_ESTABLISHED;
1039                 break;
1040         case TCP_CONNTRACK_CLOSE:
1041                 if (index != TCP_RST_SET)
1042                         break;
1043
1044                 if (ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) {
1045                         u32 seq = ntohl(th->seq);
1046
1047                         if (before(seq, ct->proto.tcp.seen[!dir].td_maxack)) {
1048                                 /* Invalid RST  */
1049                                 spin_unlock_bh(&ct->lock);
1050                                 nf_ct_l4proto_log_invalid(skb, ct, "invalid rst");
1051                                 return -NF_ACCEPT;
1052                         }
1053
1054                         if (!nf_conntrack_tcp_established(ct) ||
1055                             seq == ct->proto.tcp.seen[!dir].td_maxack)
1056                                 break;
1057
1058                         /* Check if rst is part of train, such as
1059                          *   foo:80 > bar:4379: P, 235946583:235946602(19) ack 42
1060                          *   foo:80 > bar:4379: R, 235946602:235946602(0)  ack 42
1061                          */
1062                         if (ct->proto.tcp.last_index == TCP_ACK_SET &&
1063                             ct->proto.tcp.last_dir == dir &&
1064                             seq == ct->proto.tcp.last_end)
1065                                 break;
1066
1067                         /* ... RST sequence number doesn't match exactly, keep
1068                          * established state to allow a possible challenge ACK.
1069                          */
1070                         new_state = old_state;
1071                 }
1072                 if (((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
1073                          && ct->proto.tcp.last_index == TCP_SYN_SET)
1074                         || (!test_bit(IPS_ASSURED_BIT, &ct->status)
1075                             && ct->proto.tcp.last_index == TCP_ACK_SET))
1076                     && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1077                         /* RST sent to invalid SYN or ACK we had let through
1078                          * at a) and c) above:
1079                          *
1080                          * a) SYN was in window then
1081                          * c) we hold a half-open connection.
1082                          *
1083                          * Delete our connection entry.
1084                          * We skip window checking, because packet might ACK
1085                          * segments we ignored. */
1086                         goto in_window;
1087                 }
1088                 break;
1089         default:
1090                 /* Keep compilers happy. */
1091                 break;
1092         }
1093
1094         if (!tcp_in_window(ct, &ct->proto.tcp, dir, index,
1095                            skb, dataoff, th)) {
1096                 spin_unlock_bh(&ct->lock);
1097                 return -NF_ACCEPT;
1098         }
1099      in_window:
1100         /* From now on we have got in-window packets */
1101         ct->proto.tcp.last_index = index;
1102         ct->proto.tcp.last_dir = dir;
1103
1104         pr_debug("tcp_conntracks: ");
1105         nf_ct_dump_tuple(tuple);
1106         pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
1107                  (th->syn ? 1 : 0), (th->ack ? 1 : 0),
1108                  (th->fin ? 1 : 0), (th->rst ? 1 : 0),
1109                  old_state, new_state);
1110
1111         ct->proto.tcp.state = new_state;
1112         if (old_state != new_state
1113             && new_state == TCP_CONNTRACK_FIN_WAIT)
1114                 ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
1115
1116         timeouts = nf_ct_timeout_lookup(ct);
1117         if (!timeouts)
1118                 timeouts = tn->timeouts;
1119
1120         if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
1121             timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1122                 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1123         else if (unlikely(index == TCP_RST_SET))
1124                 timeout = timeouts[TCP_CONNTRACK_CLOSE];
1125         else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
1126                  IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
1127                  timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
1128                 timeout = timeouts[TCP_CONNTRACK_UNACK];
1129         else if (ct->proto.tcp.last_win == 0 &&
1130                  timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1131                 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1132         else
1133                 timeout = timeouts[new_state];
1134         spin_unlock_bh(&ct->lock);
1135
1136         if (new_state != old_state)
1137                 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
1138
1139         if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
1140                 /* If only reply is a RST, we can consider ourselves not to
1141                    have an established connection: this is a fairly common
1142                    problem case, so we can delete the conntrack
1143                    immediately.  --RR */
1144                 if (th->rst) {
1145                         nf_ct_kill_acct(ct, ctinfo, skb);
1146                         return NF_ACCEPT;
1147                 }
1148                 /* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
1149                  * pickup with loose=1. Avoid large ESTABLISHED timeout.
1150                  */
1151                 if (new_state == TCP_CONNTRACK_ESTABLISHED &&
1152                     timeout > timeouts[TCP_CONNTRACK_UNACK])
1153                         timeout = timeouts[TCP_CONNTRACK_UNACK];
1154         } else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
1155                    && (old_state == TCP_CONNTRACK_SYN_RECV
1156                        || old_state == TCP_CONNTRACK_ESTABLISHED)
1157                    && new_state == TCP_CONNTRACK_ESTABLISHED) {
1158                 /* Set ASSURED if we see valid ack in ESTABLISHED
1159                    after SYN_RECV or a valid answer for a picked up
1160                    connection. */
1161                 set_bit(IPS_ASSURED_BIT, &ct->status);
1162                 nf_conntrack_event_cache(IPCT_ASSURED, ct);
1163         }
1164         nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
1165
1166         return NF_ACCEPT;
1167 }
1168
1169 static bool tcp_can_early_drop(const struct nf_conn *ct)
1170 {
1171         switch (ct->proto.tcp.state) {
1172         case TCP_CONNTRACK_FIN_WAIT:
1173         case TCP_CONNTRACK_LAST_ACK:
1174         case TCP_CONNTRACK_TIME_WAIT:
1175         case TCP_CONNTRACK_CLOSE:
1176         case TCP_CONNTRACK_CLOSE_WAIT:
1177                 return true;
1178         default:
1179                 break;
1180         }
1181
1182         return false;
1183 }
1184
1185 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1186
1187 #include <linux/netfilter/nfnetlink.h>
1188 #include <linux/netfilter/nfnetlink_conntrack.h>
1189
1190 static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1191                          struct nf_conn *ct, bool destroy)
1192 {
1193         struct nlattr *nest_parms;
1194         struct nf_ct_tcp_flags tmp = {};
1195
1196         spin_lock_bh(&ct->lock);
1197         nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP);
1198         if (!nest_parms)
1199                 goto nla_put_failure;
1200
1201         if (nla_put_u8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state))
1202                 goto nla_put_failure;
1203
1204         if (destroy)
1205                 goto skip_state;
1206
1207         if (nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1208                        ct->proto.tcp.seen[0].td_scale) ||
1209             nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
1210                        ct->proto.tcp.seen[1].td_scale))
1211                 goto nla_put_failure;
1212
1213         tmp.flags = ct->proto.tcp.seen[0].flags;
1214         if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1215                     sizeof(struct nf_ct_tcp_flags), &tmp))
1216                 goto nla_put_failure;
1217
1218         tmp.flags = ct->proto.tcp.seen[1].flags;
1219         if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1220                     sizeof(struct nf_ct_tcp_flags), &tmp))
1221                 goto nla_put_failure;
1222 skip_state:
1223         spin_unlock_bh(&ct->lock);
1224         nla_nest_end(skb, nest_parms);
1225
1226         return 0;
1227
1228 nla_put_failure:
1229         spin_unlock_bh(&ct->lock);
1230         return -1;
1231 }
1232
1233 static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1234         [CTA_PROTOINFO_TCP_STATE]           = { .type = NLA_U8 },
1235         [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1236         [CTA_PROTOINFO_TCP_WSCALE_REPLY]    = { .type = NLA_U8 },
1237         [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]  = { .len = sizeof(struct nf_ct_tcp_flags) },
1238         [CTA_PROTOINFO_TCP_FLAGS_REPLY]     = { .len = sizeof(struct nf_ct_tcp_flags) },
1239 };
1240
1241 #define TCP_NLATTR_SIZE ( \
1242         NLA_ALIGN(NLA_HDRLEN + 1) + \
1243         NLA_ALIGN(NLA_HDRLEN + 1) + \
1244         NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)) + \
1245         NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)))
1246
1247 static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1248 {
1249         struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
1250         struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1251         int err;
1252
1253         /* updates could not contain anything about the private
1254          * protocol info, in that case skip the parsing */
1255         if (!pattr)
1256                 return 0;
1257
1258         err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_TCP_MAX, pattr,
1259                                           tcp_nla_policy, NULL);
1260         if (err < 0)
1261                 return err;
1262
1263         if (tb[CTA_PROTOINFO_TCP_STATE] &&
1264             nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
1265                 return -EINVAL;
1266
1267         spin_lock_bh(&ct->lock);
1268         if (tb[CTA_PROTOINFO_TCP_STATE])
1269                 ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
1270
1271         if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1272                 struct nf_ct_tcp_flags *attr =
1273                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1274                 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1275                 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1276         }
1277
1278         if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1279                 struct nf_ct_tcp_flags *attr =
1280                         nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1281                 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1282                 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1283         }
1284
1285         if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1286             tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1287             ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1288             ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1289                 ct->proto.tcp.seen[0].td_scale =
1290                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1291                 ct->proto.tcp.seen[1].td_scale =
1292                         nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1293         }
1294         spin_unlock_bh(&ct->lock);
1295
1296         return 0;
1297 }
1298
1299 static unsigned int tcp_nlattr_tuple_size(void)
1300 {
1301         static unsigned int size __read_mostly;
1302
1303         if (!size)
1304                 size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
1305
1306         return size;
1307 }
1308 #endif
1309
1310 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1311
1312 #include <linux/netfilter/nfnetlink.h>
1313 #include <linux/netfilter/nfnetlink_cttimeout.h>
1314
1315 static int tcp_timeout_nlattr_to_obj(struct nlattr *tb[],
1316                                      struct net *net, void *data)
1317 {
1318         struct nf_tcp_net *tn = nf_tcp_pernet(net);
1319         unsigned int *timeouts = data;
1320         int i;
1321
1322         if (!timeouts)
1323                 timeouts = tn->timeouts;
1324         /* set default TCP timeouts. */
1325         for (i=0; i<TCP_CONNTRACK_TIMEOUT_MAX; i++)
1326                 timeouts[i] = tn->timeouts[i];
1327
1328         if (tb[CTA_TIMEOUT_TCP_SYN_SENT]) {
1329                 timeouts[TCP_CONNTRACK_SYN_SENT] =
1330                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT]))*HZ;
1331         }
1332
1333         if (tb[CTA_TIMEOUT_TCP_SYN_RECV]) {
1334                 timeouts[TCP_CONNTRACK_SYN_RECV] =
1335                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_RECV]))*HZ;
1336         }
1337         if (tb[CTA_TIMEOUT_TCP_ESTABLISHED]) {
1338                 timeouts[TCP_CONNTRACK_ESTABLISHED] =
1339                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_ESTABLISHED]))*HZ;
1340         }
1341         if (tb[CTA_TIMEOUT_TCP_FIN_WAIT]) {
1342                 timeouts[TCP_CONNTRACK_FIN_WAIT] =
1343                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_FIN_WAIT]))*HZ;
1344         }
1345         if (tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]) {
1346                 timeouts[TCP_CONNTRACK_CLOSE_WAIT] =
1347                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]))*HZ;
1348         }
1349         if (tb[CTA_TIMEOUT_TCP_LAST_ACK]) {
1350                 timeouts[TCP_CONNTRACK_LAST_ACK] =
1351                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_LAST_ACK]))*HZ;
1352         }
1353         if (tb[CTA_TIMEOUT_TCP_TIME_WAIT]) {
1354                 timeouts[TCP_CONNTRACK_TIME_WAIT] =
1355                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_TIME_WAIT]))*HZ;
1356         }
1357         if (tb[CTA_TIMEOUT_TCP_CLOSE]) {
1358                 timeouts[TCP_CONNTRACK_CLOSE] =
1359                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE]))*HZ;
1360         }
1361         if (tb[CTA_TIMEOUT_TCP_SYN_SENT2]) {
1362                 timeouts[TCP_CONNTRACK_SYN_SENT2] =
1363                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT2]))*HZ;
1364         }
1365         if (tb[CTA_TIMEOUT_TCP_RETRANS]) {
1366                 timeouts[TCP_CONNTRACK_RETRANS] =
1367                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_RETRANS]))*HZ;
1368         }
1369         if (tb[CTA_TIMEOUT_TCP_UNACK]) {
1370                 timeouts[TCP_CONNTRACK_UNACK] =
1371                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_UNACK]))*HZ;
1372         }
1373
1374         timeouts[CTA_TIMEOUT_TCP_UNSPEC] = timeouts[CTA_TIMEOUT_TCP_SYN_SENT];
1375         return 0;
1376 }
1377
1378 static int
1379 tcp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
1380 {
1381         const unsigned int *timeouts = data;
1382
1383         if (nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT,
1384                         htonl(timeouts[TCP_CONNTRACK_SYN_SENT] / HZ)) ||
1385             nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_RECV,
1386                          htonl(timeouts[TCP_CONNTRACK_SYN_RECV] / HZ)) ||
1387             nla_put_be32(skb, CTA_TIMEOUT_TCP_ESTABLISHED,
1388                          htonl(timeouts[TCP_CONNTRACK_ESTABLISHED] / HZ)) ||
1389             nla_put_be32(skb, CTA_TIMEOUT_TCP_FIN_WAIT,
1390                          htonl(timeouts[TCP_CONNTRACK_FIN_WAIT] / HZ)) ||
1391             nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE_WAIT,
1392                          htonl(timeouts[TCP_CONNTRACK_CLOSE_WAIT] / HZ)) ||
1393             nla_put_be32(skb, CTA_TIMEOUT_TCP_LAST_ACK,
1394                          htonl(timeouts[TCP_CONNTRACK_LAST_ACK] / HZ)) ||
1395             nla_put_be32(skb, CTA_TIMEOUT_TCP_TIME_WAIT,
1396                          htonl(timeouts[TCP_CONNTRACK_TIME_WAIT] / HZ)) ||
1397             nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE,
1398                          htonl(timeouts[TCP_CONNTRACK_CLOSE] / HZ)) ||
1399             nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT2,
1400                          htonl(timeouts[TCP_CONNTRACK_SYN_SENT2] / HZ)) ||
1401             nla_put_be32(skb, CTA_TIMEOUT_TCP_RETRANS,
1402                          htonl(timeouts[TCP_CONNTRACK_RETRANS] / HZ)) ||
1403             nla_put_be32(skb, CTA_TIMEOUT_TCP_UNACK,
1404                          htonl(timeouts[TCP_CONNTRACK_UNACK] / HZ)))
1405                 goto nla_put_failure;
1406         return 0;
1407
1408 nla_put_failure:
1409         return -ENOSPC;
1410 }
1411
1412 static const struct nla_policy tcp_timeout_nla_policy[CTA_TIMEOUT_TCP_MAX+1] = {
1413         [CTA_TIMEOUT_TCP_SYN_SENT]      = { .type = NLA_U32 },
1414         [CTA_TIMEOUT_TCP_SYN_RECV]      = { .type = NLA_U32 },
1415         [CTA_TIMEOUT_TCP_ESTABLISHED]   = { .type = NLA_U32 },
1416         [CTA_TIMEOUT_TCP_FIN_WAIT]      = { .type = NLA_U32 },
1417         [CTA_TIMEOUT_TCP_CLOSE_WAIT]    = { .type = NLA_U32 },
1418         [CTA_TIMEOUT_TCP_LAST_ACK]      = { .type = NLA_U32 },
1419         [CTA_TIMEOUT_TCP_TIME_WAIT]     = { .type = NLA_U32 },
1420         [CTA_TIMEOUT_TCP_CLOSE]         = { .type = NLA_U32 },
1421         [CTA_TIMEOUT_TCP_SYN_SENT2]     = { .type = NLA_U32 },
1422         [CTA_TIMEOUT_TCP_RETRANS]       = { .type = NLA_U32 },
1423         [CTA_TIMEOUT_TCP_UNACK]         = { .type = NLA_U32 },
1424 };
1425 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1426
1427 void nf_conntrack_tcp_init_net(struct net *net)
1428 {
1429         struct nf_tcp_net *tn = nf_tcp_pernet(net);
1430         int i;
1431
1432         for (i = 0; i < TCP_CONNTRACK_TIMEOUT_MAX; i++)
1433                 tn->timeouts[i] = tcp_timeouts[i];
1434
1435         /* timeouts[0] is unused, make it same as SYN_SENT so
1436          * ->timeouts[0] contains 'new' timeout, like udp or icmp.
1437          */
1438         tn->timeouts[0] = tcp_timeouts[TCP_CONNTRACK_SYN_SENT];
1439         tn->tcp_loose = nf_ct_tcp_loose;
1440         tn->tcp_be_liberal = nf_ct_tcp_be_liberal;
1441         tn->tcp_max_retrans = nf_ct_tcp_max_retrans;
1442 }
1443
1444 const struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp =
1445 {
1446         .l4proto                = IPPROTO_TCP,
1447 #ifdef CONFIG_NF_CONNTRACK_PROCFS
1448         .print_conntrack        = tcp_print_conntrack,
1449 #endif
1450         .can_early_drop         = tcp_can_early_drop,
1451 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1452         .to_nlattr              = tcp_to_nlattr,
1453         .from_nlattr            = nlattr_to_tcp,
1454         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
1455         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
1456         .nlattr_tuple_size      = tcp_nlattr_tuple_size,
1457         .nlattr_size            = TCP_NLATTR_SIZE,
1458         .nla_policy             = nf_ct_port_nla_policy,
1459 #endif
1460 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1461         .ctnl_timeout           = {
1462                 .nlattr_to_obj  = tcp_timeout_nlattr_to_obj,
1463                 .obj_to_nlattr  = tcp_timeout_obj_to_nlattr,
1464                 .nlattr_max     = CTA_TIMEOUT_TCP_MAX,
1465                 .obj_size       = sizeof(unsigned int) *
1466                                         TCP_CONNTRACK_TIMEOUT_MAX,
1467                 .nla_policy     = tcp_timeout_nla_policy,
1468         },
1469 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1470 };