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>
8 #include <linux/types.h>
9 #include <linux/timer.h>
10 #include <linux/module.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>
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>
34 /* FIXME: Examine ipfilter's timeouts and conntrack transitions more
35 closely. They're more complex. --RR */
37 static const char *const tcp_conntrack_names[] = {
51 #define MINS * 60 SECS
52 #define HOURS * 60 MINS
53 #define DAYS * 24 HOURS
55 static const unsigned int tcp_timeouts[TCP_CONNTRACK_TIMEOUT_MAX] = {
56 [TCP_CONNTRACK_SYN_SENT] = 2 MINS,
57 [TCP_CONNTRACK_SYN_RECV] = 60 SECS,
58 [TCP_CONNTRACK_ESTABLISHED] = 5 DAYS,
59 [TCP_CONNTRACK_FIN_WAIT] = 2 MINS,
60 [TCP_CONNTRACK_CLOSE_WAIT] = 60 SECS,
61 [TCP_CONNTRACK_LAST_ACK] = 30 SECS,
62 [TCP_CONNTRACK_TIME_WAIT] = 2 MINS,
63 [TCP_CONNTRACK_CLOSE] = 10 SECS,
64 [TCP_CONNTRACK_SYN_SENT2] = 2 MINS,
65 /* RFC1122 says the R2 limit should be at least 100 seconds.
66 Linux uses 15 packets as limit, which corresponds
67 to ~13-30min depending on RTO. */
68 [TCP_CONNTRACK_RETRANS] = 5 MINS,
69 [TCP_CONNTRACK_UNACK] = 5 MINS,
72 #define sNO TCP_CONNTRACK_NONE
73 #define sSS TCP_CONNTRACK_SYN_SENT
74 #define sSR TCP_CONNTRACK_SYN_RECV
75 #define sES TCP_CONNTRACK_ESTABLISHED
76 #define sFW TCP_CONNTRACK_FIN_WAIT
77 #define sCW TCP_CONNTRACK_CLOSE_WAIT
78 #define sLA TCP_CONNTRACK_LAST_ACK
79 #define sTW TCP_CONNTRACK_TIME_WAIT
80 #define sCL TCP_CONNTRACK_CLOSE
81 #define sS2 TCP_CONNTRACK_SYN_SENT2
82 #define sIV TCP_CONNTRACK_MAX
83 #define sIG TCP_CONNTRACK_IGNORE
85 /* What TCP flags are set from RST/SYN/FIN/ACK. */
96 * The TCP state transition table needs a few words...
98 * We are the man in the middle. All the packets go through us
99 * but might get lost in transit to the destination.
100 * It is assumed that the destinations can't receive segments
103 * The checked segment is in window, but our windows are *not*
104 * equivalent with the ones of the sender/receiver. We always
105 * try to guess the state of the current sender.
107 * The meaning of the states are:
109 * NONE: initial state
110 * SYN_SENT: SYN-only packet seen
111 * SYN_SENT2: SYN-only packet seen from reply dir, simultaneous open
112 * SYN_RECV: SYN-ACK packet seen
113 * ESTABLISHED: ACK packet seen
114 * FIN_WAIT: FIN packet seen
115 * CLOSE_WAIT: ACK seen (after FIN)
116 * LAST_ACK: FIN seen (after FIN)
117 * TIME_WAIT: last ACK seen
118 * CLOSE: closed connection (RST)
120 * Packets marked as IGNORED (sIG):
121 * if they may be either invalid or valid
122 * and the receiver may send back a connection
123 * closing RST or a SYN/ACK.
125 * Packets marked as INVALID (sIV):
126 * if we regard them as truly invalid packets
128 static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
131 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
132 /*syn*/ { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sS2 },
134 * sNO -> sSS Initialize a new connection
135 * sSS -> sSS Retransmitted SYN
136 * sS2 -> sS2 Late retransmitted SYN
138 * sES -> sIG Error: SYNs in window outside the SYN_SENT state
139 * are errors. Receiver will reply with RST
140 * and close the connection.
141 * Or we are not in sync and hold a dead connection.
145 * sTW -> sSS Reopened connection (RFC 1122).
148 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
149 /*synack*/ { sIV, sIV, sSR, sIV, sIV, sIV, sIV, sIV, sIV, sSR },
151 * sNO -> sIV Too late and no reason to do anything
152 * sSS -> sIV Client can't send SYN and then SYN/ACK
153 * sS2 -> sSR SYN/ACK sent to SYN2 in simultaneous open
154 * sSR -> sSR Late retransmitted SYN/ACK in simultaneous open
155 * sES -> sIV Invalid SYN/ACK packets sent by the client
162 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
163 /*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
165 * sNO -> sIV Too late and no reason to do anything...
166 * sSS -> sIV Client migth not send FIN in this state:
167 * we enforce waiting for a SYN/ACK reply first.
169 * sSR -> sFW Close started.
171 * sFW -> sLA FIN seen in both directions, waiting for
173 * Migth be a retransmitted FIN as well...
175 * sLA -> sLA Retransmitted FIN. Remain in the same state.
179 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
180 /*ack*/ { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV },
182 * sNO -> sES Assumed.
183 * sSS -> sIV ACK is invalid: we haven't seen a SYN/ACK yet.
185 * sSR -> sES Established state is reached.
187 * sFW -> sCW Normal close request answered by ACK.
189 * sLA -> sTW Last ACK detected (RFC5961 challenged)
190 * sTW -> sTW Retransmitted last ACK. Remain in the same state.
193 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
194 /*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
195 /*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
199 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
200 /*syn*/ { sIV, sS2, sIV, sIV, sIV, sIV, sIV, sSS, sIV, sS2 },
202 * sNO -> sIV Never reached.
203 * sSS -> sS2 Simultaneous open
204 * sS2 -> sS2 Retransmitted simultaneous SYN
205 * sSR -> sIV Invalid SYN packets sent by the server
210 * sTW -> sSS Reopened connection, but server may have switched role
213 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
214 /*synack*/ { sIV, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIG, sSR },
216 * sSS -> sSR Standard open.
217 * sS2 -> sSR Simultaneous open
218 * sSR -> sIG Retransmitted SYN/ACK, ignore it.
219 * sES -> sIG Late retransmitted SYN/ACK?
220 * sFW -> sIG Might be SYN/ACK answering ignored SYN
226 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
227 /*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
229 * sSS -> sIV Server might not send FIN in this state.
231 * sSR -> sFW Close started.
233 * sFW -> sLA FIN seen in both directions.
235 * sLA -> sLA Retransmitted FIN.
239 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
240 /*ack*/ { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIG },
242 * sSS -> sIG Might be a half-open connection.
244 * sSR -> sSR Might answer late resent SYN.
246 * sFW -> sCW Normal close request answered by ACK.
248 * sLA -> sTW Last ACK detected (RFC5961 challenged)
249 * sTW -> sTW Retransmitted last ACK.
252 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
253 /*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
254 /*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
258 #ifdef CONFIG_NF_CONNTRACK_PROCFS
259 /* Print out the private part of the conntrack. */
260 static void tcp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
262 if (test_bit(IPS_OFFLOAD_BIT, &ct->status))
265 seq_printf(s, "%s ", tcp_conntrack_names[ct->proto.tcp.state]);
269 static unsigned int get_conntrack_index(const struct tcphdr *tcph)
271 if (tcph->rst) return TCP_RST_SET;
272 else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET);
273 else if (tcph->fin) return TCP_FIN_SET;
274 else if (tcph->ack) return TCP_ACK_SET;
275 else return TCP_NONE_SET;
278 /* TCP connection tracking based on 'Real Stateful TCP Packet Filtering
279 in IP Filter' by Guido van Rooij.
281 http://www.sane.nl/events/sane2000/papers.html
282 http://www.darkart.com/mirrors/www.obfuscation.org/ipf/
284 The boundaries and the conditions are changed according to RFC793:
285 the packet must intersect the window (i.e. segments may be
286 after the right or before the left edge) and thus receivers may ACK
287 segments after the right edge of the window.
289 td_maxend = max(sack + max(win,1)) seen in reply packets
290 td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets
291 td_maxwin += seq + len - sender.td_maxend
292 if seq + len > sender.td_maxend
293 td_end = max(seq + len) seen in sent packets
295 I. Upper bound for valid data: seq <= sender.td_maxend
296 II. Lower bound for valid data: seq + len >= sender.td_end - receiver.td_maxwin
297 III. Upper bound for valid (s)ack: sack <= receiver.td_end
298 IV. Lower bound for valid (s)ack: sack >= receiver.td_end - MAXACKWINDOW
300 where sack is the highest right edge of sack block found in the packet
301 or ack in the case of packet without SACK option.
303 The upper bound limit for a valid (s)ack is not ignored -
304 we doesn't have to deal with fragments.
307 static inline __u32 segment_seq_plus_len(__u32 seq,
309 unsigned int dataoff,
310 const struct tcphdr *tcph)
312 /* XXX Should I use payload length field in IP/IPv6 header ?
314 return (seq + len - dataoff - tcph->doff*4
315 + (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0));
318 /* Fixme: what about big packets? */
319 #define MAXACKWINCONST 66000
320 #define MAXACKWINDOW(sender) \
321 ((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin \
325 * Simplified tcp_parse_options routine from tcp_input.c
327 static void tcp_options(const struct sk_buff *skb,
328 unsigned int dataoff,
329 const struct tcphdr *tcph,
330 struct ip_ct_tcp_state *state)
332 unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
333 const unsigned char *ptr;
334 int length = (tcph->doff*4) - sizeof(struct tcphdr);
339 ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
354 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
361 if (opsize < 2) /* "silly options" */
364 return; /* don't parse partial options */
366 if (opcode == TCPOPT_SACK_PERM
367 && opsize == TCPOLEN_SACK_PERM)
368 state->flags |= IP_CT_TCP_FLAG_SACK_PERM;
369 else if (opcode == TCPOPT_WINDOW
370 && opsize == TCPOLEN_WINDOW) {
371 state->td_scale = *(u_int8_t *)ptr;
373 if (state->td_scale > TCP_MAX_WSCALE)
374 state->td_scale = TCP_MAX_WSCALE;
377 IP_CT_TCP_FLAG_WINDOW_SCALE;
385 static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
386 const struct tcphdr *tcph, __u32 *sack)
388 unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
389 const unsigned char *ptr;
390 int length = (tcph->doff*4) - sizeof(struct tcphdr);
396 ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
401 /* Fast path for timestamp-only option */
402 if (length == TCPOLEN_TSTAMP_ALIGNED
403 && *(__be32 *)ptr == htonl((TCPOPT_NOP << 24)
405 | (TCPOPT_TIMESTAMP << 8)
406 | TCPOLEN_TIMESTAMP))
416 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
423 if (opsize < 2) /* "silly options" */
426 return; /* don't parse partial options */
428 if (opcode == TCPOPT_SACK
429 && opsize >= (TCPOLEN_SACK_BASE
430 + TCPOLEN_SACK_PERBLOCK)
431 && !((opsize - TCPOLEN_SACK_BASE)
432 % TCPOLEN_SACK_PERBLOCK)) {
434 i < (opsize - TCPOLEN_SACK_BASE);
435 i += TCPOLEN_SACK_PERBLOCK) {
436 tmp = get_unaligned_be32((__be32 *)(ptr+i)+1);
438 if (after(tmp, *sack))
449 static bool tcp_in_window(const struct nf_conn *ct,
450 struct ip_ct_tcp *state,
451 enum ip_conntrack_dir dir,
453 const struct sk_buff *skb,
454 unsigned int dataoff,
455 const struct tcphdr *tcph)
457 struct net *net = nf_ct_net(ct);
458 struct nf_tcp_net *tn = nf_tcp_pernet(net);
459 struct ip_ct_tcp_state *sender = &state->seen[dir];
460 struct ip_ct_tcp_state *receiver = &state->seen[!dir];
461 const struct nf_conntrack_tuple *tuple = &ct->tuplehash[dir].tuple;
462 __u32 seq, ack, sack, end, win, swin;
465 bool res, in_recv_win;
468 * Get the required data from the packet.
470 seq = ntohl(tcph->seq);
471 ack = sack = ntohl(tcph->ack_seq);
472 win_raw = ntohs(tcph->window);
474 end = segment_seq_plus_len(seq, skb->len, dataoff, tcph);
476 if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
477 tcp_sack(skb, dataoff, tcph, &sack);
479 /* Take into account NAT sequence number mangling */
480 receiver_offset = nf_ct_seq_offset(ct, !dir, ack - 1);
481 ack -= receiver_offset;
482 sack -= receiver_offset;
484 pr_debug("tcp_in_window: START\n");
485 pr_debug("tcp_in_window: ");
486 nf_ct_dump_tuple(tuple);
487 pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
488 seq, ack, receiver_offset, sack, receiver_offset, win, end);
489 pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
490 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
491 sender->td_end, sender->td_maxend, sender->td_maxwin,
493 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
496 if (sender->td_maxwin == 0) {
498 * Initialize sender data.
502 * SYN-ACK in reply to a SYN
503 * or SYN from reply direction in simultaneous open.
506 sender->td_maxend = end;
507 sender->td_maxwin = (win == 0 ? 1 : win);
509 tcp_options(skb, dataoff, tcph, sender);
512 * Both sides must send the Window Scale option
513 * to enable window scaling in either direction.
515 if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE
516 && receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE))
518 receiver->td_scale = 0;
520 /* Simultaneous open */
524 * We are in the middle of a connection,
525 * its history is lost for us.
526 * Let's try to use the data from the packet.
528 sender->td_end = end;
529 swin = win << sender->td_scale;
530 sender->td_maxwin = (swin == 0 ? 1 : swin);
531 sender->td_maxend = end + sender->td_maxwin;
532 if (receiver->td_maxwin == 0) {
533 /* We haven't seen traffic in the other
534 * direction yet but we have to tweak window
535 * tracking to pass III and IV until that
538 receiver->td_end = receiver->td_maxend = sack;
539 } else if (sack == receiver->td_end + 1) {
540 /* Likely a reply to a keepalive.
547 } else if (((state->state == TCP_CONNTRACK_SYN_SENT
548 && dir == IP_CT_DIR_ORIGINAL)
549 || (state->state == TCP_CONNTRACK_SYN_RECV
550 && dir == IP_CT_DIR_REPLY))
551 && after(end, sender->td_end)) {
553 * RFC 793: "if a TCP is reinitialized ... then it need
554 * not wait at all; it must only be sure to use sequence
555 * numbers larger than those recently used."
558 sender->td_maxend = end;
559 sender->td_maxwin = (win == 0 ? 1 : win);
561 tcp_options(skb, dataoff, tcph, sender);
566 * If there is no ACK, just pretend it was set and OK.
568 ack = sack = receiver->td_end;
569 } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
570 (TCP_FLAG_ACK|TCP_FLAG_RST))
573 * Broken TCP stacks, that set ACK in RST packets as well
574 * with zero ack value.
576 ack = sack = receiver->td_end;
579 if (tcph->rst && seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)
581 * RST sent answering SYN.
583 seq = end = sender->td_end;
585 pr_debug("tcp_in_window: ");
586 nf_ct_dump_tuple(tuple);
587 pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
588 seq, ack, receiver_offset, sack, receiver_offset, win, end);
589 pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
590 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
591 sender->td_end, sender->td_maxend, sender->td_maxwin,
593 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
596 /* Is the ending sequence in the receive window (if available)? */
597 in_recv_win = !receiver->td_maxwin ||
598 after(end, sender->td_end - receiver->td_maxwin - 1);
600 pr_debug("tcp_in_window: I=%i II=%i III=%i IV=%i\n",
601 before(seq, sender->td_maxend + 1),
602 (in_recv_win ? 1 : 0),
603 before(sack, receiver->td_end + 1),
604 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1));
606 if (before(seq, sender->td_maxend + 1) &&
608 before(sack, receiver->td_end + 1) &&
609 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1)) {
611 * Take into account window scaling (RFC 1323).
614 win <<= sender->td_scale;
617 * Update sender data.
619 swin = win + (sack - ack);
620 if (sender->td_maxwin < swin)
621 sender->td_maxwin = swin;
622 if (after(end, sender->td_end)) {
623 sender->td_end = end;
624 sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
627 if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) {
628 sender->td_maxack = ack;
629 sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET;
630 } else if (after(ack, sender->td_maxack))
631 sender->td_maxack = ack;
635 * Update receiver data.
637 if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
638 receiver->td_maxwin += end - sender->td_maxend;
639 if (after(sack + win, receiver->td_maxend - 1)) {
640 receiver->td_maxend = sack + win;
642 receiver->td_maxend++;
644 if (ack == receiver->td_end)
645 receiver->flags &= ~IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
648 * Check retransmissions.
650 if (index == TCP_ACK_SET) {
651 if (state->last_dir == dir
652 && state->last_seq == seq
653 && state->last_ack == ack
654 && state->last_end == end
655 && state->last_win == win_raw)
658 state->last_dir = dir;
659 state->last_seq = seq;
660 state->last_ack = ack;
661 state->last_end = end;
662 state->last_win = win_raw;
669 if (sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL ||
673 nf_ct_l4proto_log_invalid(skb, ct,
675 before(seq, sender->td_maxend + 1) ?
677 before(sack, receiver->td_end + 1) ?
678 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1) ? "BUG"
679 : "ACK is under the lower bound (possible overly delayed ACK)"
680 : "ACK is over the upper bound (ACKed data not seen yet)"
681 : "SEQ is under the lower bound (already ACKed data retransmitted)"
682 : "SEQ is over the upper bound (over the window of the receiver)");
686 pr_debug("tcp_in_window: res=%u sender end=%u maxend=%u maxwin=%u "
687 "receiver end=%u maxend=%u maxwin=%u\n",
688 res, sender->td_end, sender->td_maxend, sender->td_maxwin,
689 receiver->td_end, receiver->td_maxend, receiver->td_maxwin);
694 /* table of valid flag combinations - PUSH, ECE and CWR are always valid */
695 static const u8 tcp_valid_flags[(TCPHDR_FIN|TCPHDR_SYN|TCPHDR_RST|TCPHDR_ACK|
699 [TCPHDR_SYN|TCPHDR_URG] = 1,
700 [TCPHDR_SYN|TCPHDR_ACK] = 1,
702 [TCPHDR_RST|TCPHDR_ACK] = 1,
703 [TCPHDR_FIN|TCPHDR_ACK] = 1,
704 [TCPHDR_FIN|TCPHDR_ACK|TCPHDR_URG] = 1,
706 [TCPHDR_ACK|TCPHDR_URG] = 1,
709 static void tcp_error_log(const struct sk_buff *skb,
710 const struct nf_hook_state *state,
713 nf_l4proto_log_invalid(skb, state->net, state->pf, IPPROTO_TCP, "%s", msg);
716 /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c. */
717 static bool tcp_error(const struct tcphdr *th,
719 unsigned int dataoff,
720 const struct nf_hook_state *state)
722 unsigned int tcplen = skb->len - dataoff;
725 /* Not whole TCP header or malformed packet */
726 if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
727 tcp_error_log(skb, state, "truncated packet");
731 /* Checksum invalid? Ignore.
732 * We skip checking packets on the outgoing path
733 * because the checksum is assumed to be correct.
735 /* FIXME: Source route IP option packets --RR */
736 if (state->net->ct.sysctl_checksum &&
737 state->hook == NF_INET_PRE_ROUTING &&
738 nf_checksum(skb, state->hook, dataoff, IPPROTO_TCP, state->pf)) {
739 tcp_error_log(skb, state, "bad checksum");
743 /* Check TCP flags. */
744 tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
745 if (!tcp_valid_flags[tcpflags]) {
746 tcp_error_log(skb, state, "invalid tcp flag combination");
753 static noinline bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
754 unsigned int dataoff,
755 const struct tcphdr *th)
757 enum tcp_conntrack new_state;
758 struct net *net = nf_ct_net(ct);
759 const struct nf_tcp_net *tn = nf_tcp_pernet(net);
760 const struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[0];
761 const struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[1];
763 /* Don't need lock here: this conntrack not in circulation yet */
764 new_state = tcp_conntracks[0][get_conntrack_index(th)][TCP_CONNTRACK_NONE];
766 /* Invalid: delete conntrack */
767 if (new_state >= TCP_CONNTRACK_MAX) {
768 pr_debug("nf_ct_tcp: invalid new deleting.\n");
772 if (new_state == TCP_CONNTRACK_SYN_SENT) {
773 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
775 ct->proto.tcp.seen[0].td_end =
776 segment_seq_plus_len(ntohl(th->seq), skb->len,
778 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
779 if (ct->proto.tcp.seen[0].td_maxwin == 0)
780 ct->proto.tcp.seen[0].td_maxwin = 1;
781 ct->proto.tcp.seen[0].td_maxend =
782 ct->proto.tcp.seen[0].td_end;
784 tcp_options(skb, dataoff, th, &ct->proto.tcp.seen[0]);
785 } else if (tn->tcp_loose == 0) {
786 /* Don't try to pick up connections. */
789 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
791 * We are in the middle of a connection,
792 * its history is lost for us.
793 * Let's try to use the data from the packet.
795 ct->proto.tcp.seen[0].td_end =
796 segment_seq_plus_len(ntohl(th->seq), skb->len,
798 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
799 if (ct->proto.tcp.seen[0].td_maxwin == 0)
800 ct->proto.tcp.seen[0].td_maxwin = 1;
801 ct->proto.tcp.seen[0].td_maxend =
802 ct->proto.tcp.seen[0].td_end +
803 ct->proto.tcp.seen[0].td_maxwin;
805 /* We assume SACK and liberal window checking to handle
807 ct->proto.tcp.seen[0].flags =
808 ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
809 IP_CT_TCP_FLAG_BE_LIBERAL;
812 /* tcp_packet will set them */
813 ct->proto.tcp.last_index = TCP_NONE_SET;
815 pr_debug("%s: sender end=%u maxend=%u maxwin=%u scale=%i "
816 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
818 sender->td_end, sender->td_maxend, sender->td_maxwin,
820 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
825 /* Returns verdict for packet, or -1 for invalid. */
826 int nf_conntrack_tcp_packet(struct nf_conn *ct,
828 unsigned int dataoff,
829 enum ip_conntrack_info ctinfo,
830 const struct nf_hook_state *state)
832 struct net *net = nf_ct_net(ct);
833 struct nf_tcp_net *tn = nf_tcp_pernet(net);
834 struct nf_conntrack_tuple *tuple;
835 enum tcp_conntrack new_state, old_state;
836 unsigned int index, *timeouts;
837 enum ip_conntrack_dir dir;
838 const struct tcphdr *th;
840 unsigned long timeout;
842 th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
846 if (tcp_error(th, skb, dataoff, state))
849 if (!nf_ct_is_confirmed(ct) && !tcp_new(ct, skb, dataoff, th))
852 spin_lock_bh(&ct->lock);
853 old_state = ct->proto.tcp.state;
854 dir = CTINFO2DIR(ctinfo);
855 index = get_conntrack_index(th);
856 new_state = tcp_conntracks[dir][index][old_state];
857 tuple = &ct->tuplehash[dir].tuple;
860 case TCP_CONNTRACK_SYN_SENT:
861 if (old_state < TCP_CONNTRACK_TIME_WAIT)
863 /* RFC 1122: "When a connection is closed actively,
864 * it MUST linger in TIME-WAIT state for a time 2xMSL
865 * (Maximum Segment Lifetime). However, it MAY accept
866 * a new SYN from the remote TCP to reopen the connection
867 * directly from TIME-WAIT state, if..."
868 * We ignore the conditions because we are in the
869 * TIME-WAIT state anyway.
871 * Handle aborted connections: we and the server
872 * think there is an existing connection but the client
873 * aborts it and starts a new one.
875 if (((ct->proto.tcp.seen[dir].flags
876 | ct->proto.tcp.seen[!dir].flags)
877 & IP_CT_TCP_FLAG_CLOSE_INIT)
878 || (ct->proto.tcp.last_dir == dir
879 && ct->proto.tcp.last_index == TCP_RST_SET)) {
880 /* Attempt to reopen a closed/aborted connection.
881 * Delete this connection and look up again. */
882 spin_unlock_bh(&ct->lock);
884 /* Only repeat if we can actually remove the timer.
885 * Destruction may already be in progress in process
886 * context and we must give it a chance to terminate.
893 case TCP_CONNTRACK_IGNORE:
896 * Our connection entry may be out of sync, so ignore
897 * packets which may signal the real connection between
898 * the client and the server.
901 * b) SYN/ACK in REPLY
902 * c) ACK in reply direction after initial SYN in original.
904 * If the ignored packet is invalid, the receiver will send
905 * a RST we'll catch below.
907 if (index == TCP_SYNACK_SET
908 && ct->proto.tcp.last_index == TCP_SYN_SET
909 && ct->proto.tcp.last_dir != dir
910 && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
911 /* b) This SYN/ACK acknowledges a SYN that we earlier
912 * ignored as invalid. This means that the client and
913 * the server are both in sync, while the firewall is
914 * not. We get in sync from the previously annotated
917 old_state = TCP_CONNTRACK_SYN_SENT;
918 new_state = TCP_CONNTRACK_SYN_RECV;
919 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
920 ct->proto.tcp.last_end;
921 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
922 ct->proto.tcp.last_end;
923 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
924 ct->proto.tcp.last_win == 0 ?
925 1 : ct->proto.tcp.last_win;
926 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
927 ct->proto.tcp.last_wscale;
928 ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
929 ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
930 ct->proto.tcp.last_flags;
931 memset(&ct->proto.tcp.seen[dir], 0,
932 sizeof(struct ip_ct_tcp_state));
935 ct->proto.tcp.last_index = index;
936 ct->proto.tcp.last_dir = dir;
937 ct->proto.tcp.last_seq = ntohl(th->seq);
938 ct->proto.tcp.last_end =
939 segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
940 ct->proto.tcp.last_win = ntohs(th->window);
942 /* a) This is a SYN in ORIGINAL. The client and the server
943 * may be in sync but we are not. In that case, we annotate
944 * the TCP options and let the packet go through. If it is a
945 * valid SYN packet, the server will reply with a SYN/ACK, and
946 * then we'll get in sync. Otherwise, the server potentially
947 * responds with a challenge ACK if implementing RFC5961.
949 if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
950 struct ip_ct_tcp_state seen = {};
952 ct->proto.tcp.last_flags =
953 ct->proto.tcp.last_wscale = 0;
954 tcp_options(skb, dataoff, th, &seen);
955 if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
956 ct->proto.tcp.last_flags |=
957 IP_CT_TCP_FLAG_WINDOW_SCALE;
958 ct->proto.tcp.last_wscale = seen.td_scale;
960 if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
961 ct->proto.tcp.last_flags |=
962 IP_CT_TCP_FLAG_SACK_PERM;
964 /* Mark the potential for RFC5961 challenge ACK,
965 * this pose a special problem for LAST_ACK state
966 * as ACK is intrepretated as ACKing last FIN.
968 if (old_state == TCP_CONNTRACK_LAST_ACK)
969 ct->proto.tcp.last_flags |=
970 IP_CT_EXP_CHALLENGE_ACK;
972 spin_unlock_bh(&ct->lock);
973 nf_ct_l4proto_log_invalid(skb, ct,
974 "packet (index %d) in dir %d ignored, state %s",
976 tcp_conntrack_names[old_state]);
978 case TCP_CONNTRACK_MAX:
979 /* Special case for SYN proxy: when the SYN to the server or
980 * the SYN/ACK from the server is lost, the client may transmit
981 * a keep-alive packet while in SYN_SENT state. This needs to
982 * be associated with the original conntrack entry in order to
983 * generate a new SYN with the correct sequence number.
985 if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
986 index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
987 ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
988 ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
989 pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
990 spin_unlock_bh(&ct->lock);
995 pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
996 dir, get_conntrack_index(th), old_state);
997 spin_unlock_bh(&ct->lock);
998 nf_ct_l4proto_log_invalid(skb, ct, "invalid state");
1000 case TCP_CONNTRACK_TIME_WAIT:
1001 /* RFC5961 compliance cause stack to send "challenge-ACK"
1002 * e.g. in response to spurious SYNs. Conntrack MUST
1003 * not believe this ACK is acking last FIN.
1005 if (old_state == TCP_CONNTRACK_LAST_ACK &&
1006 index == TCP_ACK_SET &&
1007 ct->proto.tcp.last_dir != dir &&
1008 ct->proto.tcp.last_index == TCP_SYN_SET &&
1009 (ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
1010 /* Detected RFC5961 challenge ACK */
1011 ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1012 spin_unlock_bh(&ct->lock);
1013 nf_ct_l4proto_log_invalid(skb, ct, "challenge-ack ignored");
1014 return NF_ACCEPT; /* Don't change state */
1017 case TCP_CONNTRACK_SYN_SENT2:
1018 /* tcp_conntracks table is not smart enough to handle
1019 * simultaneous open.
1021 ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN;
1023 case TCP_CONNTRACK_SYN_RECV:
1024 if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET &&
1025 ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN)
1026 new_state = TCP_CONNTRACK_ESTABLISHED;
1028 case TCP_CONNTRACK_CLOSE:
1029 if (index != TCP_RST_SET)
1032 if (ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) {
1033 u32 seq = ntohl(th->seq);
1035 if (before(seq, ct->proto.tcp.seen[!dir].td_maxack)) {
1037 spin_unlock_bh(&ct->lock);
1038 nf_ct_l4proto_log_invalid(skb, ct, "invalid rst");
1042 if (!nf_conntrack_tcp_established(ct) ||
1043 seq == ct->proto.tcp.seen[!dir].td_maxack)
1046 /* Check if rst is part of train, such as
1047 * foo:80 > bar:4379: P, 235946583:235946602(19) ack 42
1048 * foo:80 > bar:4379: R, 235946602:235946602(0) ack 42
1050 if (ct->proto.tcp.last_index == TCP_ACK_SET &&
1051 ct->proto.tcp.last_dir == dir &&
1052 seq == ct->proto.tcp.last_end)
1055 /* ... RST sequence number doesn't match exactly, keep
1056 * established state to allow a possible challenge ACK.
1058 new_state = old_state;
1060 if (((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
1061 && ct->proto.tcp.last_index == TCP_SYN_SET)
1062 || (!test_bit(IPS_ASSURED_BIT, &ct->status)
1063 && ct->proto.tcp.last_index == TCP_ACK_SET))
1064 && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1065 /* RST sent to invalid SYN or ACK we had let through
1066 * at a) and c) above:
1068 * a) SYN was in window then
1069 * c) we hold a half-open connection.
1071 * Delete our connection entry.
1072 * We skip window checking, because packet might ACK
1073 * segments we ignored. */
1078 /* Keep compilers happy. */
1082 if (!tcp_in_window(ct, &ct->proto.tcp, dir, index,
1083 skb, dataoff, th)) {
1084 spin_unlock_bh(&ct->lock);
1088 /* From now on we have got in-window packets */
1089 ct->proto.tcp.last_index = index;
1090 ct->proto.tcp.last_dir = dir;
1092 pr_debug("tcp_conntracks: ");
1093 nf_ct_dump_tuple(tuple);
1094 pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
1095 (th->syn ? 1 : 0), (th->ack ? 1 : 0),
1096 (th->fin ? 1 : 0), (th->rst ? 1 : 0),
1097 old_state, new_state);
1099 ct->proto.tcp.state = new_state;
1100 if (old_state != new_state
1101 && new_state == TCP_CONNTRACK_FIN_WAIT)
1102 ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
1104 timeouts = nf_ct_timeout_lookup(ct);
1106 timeouts = tn->timeouts;
1108 if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
1109 timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1110 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1111 else if (unlikely(index == TCP_RST_SET))
1112 timeout = timeouts[TCP_CONNTRACK_CLOSE];
1113 else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
1114 IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
1115 timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
1116 timeout = timeouts[TCP_CONNTRACK_UNACK];
1117 else if (ct->proto.tcp.last_win == 0 &&
1118 timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1119 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1121 timeout = timeouts[new_state];
1122 spin_unlock_bh(&ct->lock);
1124 if (new_state != old_state)
1125 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
1127 if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
1128 /* If only reply is a RST, we can consider ourselves not to
1129 have an established connection: this is a fairly common
1130 problem case, so we can delete the conntrack
1131 immediately. --RR */
1133 nf_ct_kill_acct(ct, ctinfo, skb);
1136 /* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
1137 * pickup with loose=1. Avoid large ESTABLISHED timeout.
1139 if (new_state == TCP_CONNTRACK_ESTABLISHED &&
1140 timeout > timeouts[TCP_CONNTRACK_UNACK])
1141 timeout = timeouts[TCP_CONNTRACK_UNACK];
1142 } else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
1143 && (old_state == TCP_CONNTRACK_SYN_RECV
1144 || old_state == TCP_CONNTRACK_ESTABLISHED)
1145 && new_state == TCP_CONNTRACK_ESTABLISHED) {
1146 /* Set ASSURED if we see valid ack in ESTABLISHED
1147 after SYN_RECV or a valid answer for a picked up
1149 set_bit(IPS_ASSURED_BIT, &ct->status);
1150 nf_conntrack_event_cache(IPCT_ASSURED, ct);
1152 nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
1157 static bool tcp_can_early_drop(const struct nf_conn *ct)
1159 switch (ct->proto.tcp.state) {
1160 case TCP_CONNTRACK_FIN_WAIT:
1161 case TCP_CONNTRACK_LAST_ACK:
1162 case TCP_CONNTRACK_TIME_WAIT:
1163 case TCP_CONNTRACK_CLOSE:
1164 case TCP_CONNTRACK_CLOSE_WAIT:
1173 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1175 #include <linux/netfilter/nfnetlink.h>
1176 #include <linux/netfilter/nfnetlink_conntrack.h>
1178 static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1179 struct nf_conn *ct, bool destroy)
1181 struct nlattr *nest_parms;
1182 struct nf_ct_tcp_flags tmp = {};
1184 spin_lock_bh(&ct->lock);
1185 nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP);
1187 goto nla_put_failure;
1189 if (nla_put_u8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state))
1190 goto nla_put_failure;
1195 if (nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1196 ct->proto.tcp.seen[0].td_scale) ||
1197 nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
1198 ct->proto.tcp.seen[1].td_scale))
1199 goto nla_put_failure;
1201 tmp.flags = ct->proto.tcp.seen[0].flags;
1202 if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1203 sizeof(struct nf_ct_tcp_flags), &tmp))
1204 goto nla_put_failure;
1206 tmp.flags = ct->proto.tcp.seen[1].flags;
1207 if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1208 sizeof(struct nf_ct_tcp_flags), &tmp))
1209 goto nla_put_failure;
1211 spin_unlock_bh(&ct->lock);
1212 nla_nest_end(skb, nest_parms);
1217 spin_unlock_bh(&ct->lock);
1221 static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1222 [CTA_PROTOINFO_TCP_STATE] = { .type = NLA_U8 },
1223 [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1224 [CTA_PROTOINFO_TCP_WSCALE_REPLY] = { .type = NLA_U8 },
1225 [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL] = { .len = sizeof(struct nf_ct_tcp_flags) },
1226 [CTA_PROTOINFO_TCP_FLAGS_REPLY] = { .len = sizeof(struct nf_ct_tcp_flags) },
1229 #define TCP_NLATTR_SIZE ( \
1230 NLA_ALIGN(NLA_HDRLEN + 1) + \
1231 NLA_ALIGN(NLA_HDRLEN + 1) + \
1232 NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)) + \
1233 NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)))
1235 static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1237 struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
1238 struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1241 /* updates could not contain anything about the private
1242 * protocol info, in that case skip the parsing */
1246 err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_TCP_MAX, pattr,
1247 tcp_nla_policy, NULL);
1251 if (tb[CTA_PROTOINFO_TCP_STATE] &&
1252 nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
1255 spin_lock_bh(&ct->lock);
1256 if (tb[CTA_PROTOINFO_TCP_STATE])
1257 ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
1259 if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1260 struct nf_ct_tcp_flags *attr =
1261 nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1262 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1263 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1266 if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1267 struct nf_ct_tcp_flags *attr =
1268 nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1269 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1270 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1273 if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1274 tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1275 ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1276 ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1277 ct->proto.tcp.seen[0].td_scale =
1278 nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1279 ct->proto.tcp.seen[1].td_scale =
1280 nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1282 spin_unlock_bh(&ct->lock);
1287 static unsigned int tcp_nlattr_tuple_size(void)
1289 static unsigned int size __read_mostly;
1292 size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
1298 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1300 #include <linux/netfilter/nfnetlink.h>
1301 #include <linux/netfilter/nfnetlink_cttimeout.h>
1303 static int tcp_timeout_nlattr_to_obj(struct nlattr *tb[],
1304 struct net *net, void *data)
1306 struct nf_tcp_net *tn = nf_tcp_pernet(net);
1307 unsigned int *timeouts = data;
1311 timeouts = tn->timeouts;
1312 /* set default TCP timeouts. */
1313 for (i=0; i<TCP_CONNTRACK_TIMEOUT_MAX; i++)
1314 timeouts[i] = tn->timeouts[i];
1316 if (tb[CTA_TIMEOUT_TCP_SYN_SENT]) {
1317 timeouts[TCP_CONNTRACK_SYN_SENT] =
1318 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT]))*HZ;
1321 if (tb[CTA_TIMEOUT_TCP_SYN_RECV]) {
1322 timeouts[TCP_CONNTRACK_SYN_RECV] =
1323 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_RECV]))*HZ;
1325 if (tb[CTA_TIMEOUT_TCP_ESTABLISHED]) {
1326 timeouts[TCP_CONNTRACK_ESTABLISHED] =
1327 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_ESTABLISHED]))*HZ;
1329 if (tb[CTA_TIMEOUT_TCP_FIN_WAIT]) {
1330 timeouts[TCP_CONNTRACK_FIN_WAIT] =
1331 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_FIN_WAIT]))*HZ;
1333 if (tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]) {
1334 timeouts[TCP_CONNTRACK_CLOSE_WAIT] =
1335 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]))*HZ;
1337 if (tb[CTA_TIMEOUT_TCP_LAST_ACK]) {
1338 timeouts[TCP_CONNTRACK_LAST_ACK] =
1339 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_LAST_ACK]))*HZ;
1341 if (tb[CTA_TIMEOUT_TCP_TIME_WAIT]) {
1342 timeouts[TCP_CONNTRACK_TIME_WAIT] =
1343 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_TIME_WAIT]))*HZ;
1345 if (tb[CTA_TIMEOUT_TCP_CLOSE]) {
1346 timeouts[TCP_CONNTRACK_CLOSE] =
1347 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE]))*HZ;
1349 if (tb[CTA_TIMEOUT_TCP_SYN_SENT2]) {
1350 timeouts[TCP_CONNTRACK_SYN_SENT2] =
1351 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT2]))*HZ;
1353 if (tb[CTA_TIMEOUT_TCP_RETRANS]) {
1354 timeouts[TCP_CONNTRACK_RETRANS] =
1355 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_RETRANS]))*HZ;
1357 if (tb[CTA_TIMEOUT_TCP_UNACK]) {
1358 timeouts[TCP_CONNTRACK_UNACK] =
1359 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_UNACK]))*HZ;
1362 timeouts[CTA_TIMEOUT_TCP_UNSPEC] = timeouts[CTA_TIMEOUT_TCP_SYN_SENT];
1367 tcp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
1369 const unsigned int *timeouts = data;
1371 if (nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT,
1372 htonl(timeouts[TCP_CONNTRACK_SYN_SENT] / HZ)) ||
1373 nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_RECV,
1374 htonl(timeouts[TCP_CONNTRACK_SYN_RECV] / HZ)) ||
1375 nla_put_be32(skb, CTA_TIMEOUT_TCP_ESTABLISHED,
1376 htonl(timeouts[TCP_CONNTRACK_ESTABLISHED] / HZ)) ||
1377 nla_put_be32(skb, CTA_TIMEOUT_TCP_FIN_WAIT,
1378 htonl(timeouts[TCP_CONNTRACK_FIN_WAIT] / HZ)) ||
1379 nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE_WAIT,
1380 htonl(timeouts[TCP_CONNTRACK_CLOSE_WAIT] / HZ)) ||
1381 nla_put_be32(skb, CTA_TIMEOUT_TCP_LAST_ACK,
1382 htonl(timeouts[TCP_CONNTRACK_LAST_ACK] / HZ)) ||
1383 nla_put_be32(skb, CTA_TIMEOUT_TCP_TIME_WAIT,
1384 htonl(timeouts[TCP_CONNTRACK_TIME_WAIT] / HZ)) ||
1385 nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE,
1386 htonl(timeouts[TCP_CONNTRACK_CLOSE] / HZ)) ||
1387 nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT2,
1388 htonl(timeouts[TCP_CONNTRACK_SYN_SENT2] / HZ)) ||
1389 nla_put_be32(skb, CTA_TIMEOUT_TCP_RETRANS,
1390 htonl(timeouts[TCP_CONNTRACK_RETRANS] / HZ)) ||
1391 nla_put_be32(skb, CTA_TIMEOUT_TCP_UNACK,
1392 htonl(timeouts[TCP_CONNTRACK_UNACK] / HZ)))
1393 goto nla_put_failure;
1400 static const struct nla_policy tcp_timeout_nla_policy[CTA_TIMEOUT_TCP_MAX+1] = {
1401 [CTA_TIMEOUT_TCP_SYN_SENT] = { .type = NLA_U32 },
1402 [CTA_TIMEOUT_TCP_SYN_RECV] = { .type = NLA_U32 },
1403 [CTA_TIMEOUT_TCP_ESTABLISHED] = { .type = NLA_U32 },
1404 [CTA_TIMEOUT_TCP_FIN_WAIT] = { .type = NLA_U32 },
1405 [CTA_TIMEOUT_TCP_CLOSE_WAIT] = { .type = NLA_U32 },
1406 [CTA_TIMEOUT_TCP_LAST_ACK] = { .type = NLA_U32 },
1407 [CTA_TIMEOUT_TCP_TIME_WAIT] = { .type = NLA_U32 },
1408 [CTA_TIMEOUT_TCP_CLOSE] = { .type = NLA_U32 },
1409 [CTA_TIMEOUT_TCP_SYN_SENT2] = { .type = NLA_U32 },
1410 [CTA_TIMEOUT_TCP_RETRANS] = { .type = NLA_U32 },
1411 [CTA_TIMEOUT_TCP_UNACK] = { .type = NLA_U32 },
1413 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1415 void nf_conntrack_tcp_init_net(struct net *net)
1417 struct nf_tcp_net *tn = nf_tcp_pernet(net);
1420 for (i = 0; i < TCP_CONNTRACK_TIMEOUT_MAX; i++)
1421 tn->timeouts[i] = tcp_timeouts[i];
1423 /* timeouts[0] is unused, make it same as SYN_SENT so
1424 * ->timeouts[0] contains 'new' timeout, like udp or icmp.
1426 tn->timeouts[0] = tcp_timeouts[TCP_CONNTRACK_SYN_SENT];
1428 /* If it is set to zero, we disable picking up already established
1433 /* "Be conservative in what you do,
1434 * be liberal in what you accept from others."
1435 * If it's non-zero, we mark only out of window RST segments as INVALID.
1437 tn->tcp_be_liberal = 0;
1439 /* Max number of the retransmitted packets without receiving an (acceptable)
1440 * ACK from the destination. If this number is reached, a shorter timer
1443 tn->tcp_max_retrans = 3;
1446 const struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp =
1448 .l4proto = IPPROTO_TCP,
1449 #ifdef CONFIG_NF_CONNTRACK_PROCFS
1450 .print_conntrack = tcp_print_conntrack,
1452 .can_early_drop = tcp_can_early_drop,
1453 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1454 .to_nlattr = tcp_to_nlattr,
1455 .from_nlattr = nlattr_to_tcp,
1456 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
1457 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
1458 .nlattr_tuple_size = tcp_nlattr_tuple_size,
1459 .nlattr_size = TCP_NLATTR_SIZE,
1460 .nla_policy = nf_ct_port_nla_policy,
1462 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1464 .nlattr_to_obj = tcp_timeout_nlattr_to_obj,
1465 .obj_to_nlattr = tcp_timeout_obj_to_nlattr,
1466 .nlattr_max = CTA_TIMEOUT_TCP_MAX,
1467 .obj_size = sizeof(unsigned int) *
1468 TCP_CONNTRACK_TIMEOUT_MAX,
1469 .nla_policy = tcp_timeout_nla_policy,
1471 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */