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(struct nf_conn *ct,
450 enum ip_conntrack_dir dir,
452 const struct sk_buff *skb,
453 unsigned int dataoff,
454 const struct tcphdr *tcph,
455 const struct nf_hook_state *hook_state)
457 struct ip_ct_tcp *state = &ct->proto.tcp;
458 struct net *net = nf_ct_net(ct);
459 struct nf_tcp_net *tn = nf_tcp_pernet(net);
460 struct ip_ct_tcp_state *sender = &state->seen[dir];
461 struct ip_ct_tcp_state *receiver = &state->seen[!dir];
462 const struct nf_conntrack_tuple *tuple = &ct->tuplehash[dir].tuple;
463 __u32 seq, ack, sack, end, win, swin;
466 bool res, in_recv_win;
469 * Get the required data from the packet.
471 seq = ntohl(tcph->seq);
472 ack = sack = ntohl(tcph->ack_seq);
473 win_raw = ntohs(tcph->window);
475 end = segment_seq_plus_len(seq, skb->len, dataoff, tcph);
477 if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
478 tcp_sack(skb, dataoff, tcph, &sack);
480 /* Take into account NAT sequence number mangling */
481 receiver_offset = nf_ct_seq_offset(ct, !dir, ack - 1);
482 ack -= receiver_offset;
483 sack -= receiver_offset;
485 pr_debug("tcp_in_window: START\n");
486 pr_debug("tcp_in_window: ");
487 nf_ct_dump_tuple(tuple);
488 pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
489 seq, ack, receiver_offset, sack, receiver_offset, win, end);
490 pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
491 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
492 sender->td_end, sender->td_maxend, sender->td_maxwin,
494 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
497 if (sender->td_maxwin == 0) {
499 * Initialize sender data.
503 * SYN-ACK in reply to a SYN
504 * or SYN from reply direction in simultaneous open.
507 sender->td_maxend = end;
508 sender->td_maxwin = (win == 0 ? 1 : win);
510 tcp_options(skb, dataoff, tcph, sender);
513 * Both sides must send the Window Scale option
514 * to enable window scaling in either direction.
516 if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE
517 && receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE))
519 receiver->td_scale = 0;
521 /* Simultaneous open */
525 * We are in the middle of a connection,
526 * its history is lost for us.
527 * Let's try to use the data from the packet.
529 sender->td_end = end;
530 swin = win << sender->td_scale;
531 sender->td_maxwin = (swin == 0 ? 1 : swin);
532 sender->td_maxend = end + sender->td_maxwin;
533 if (receiver->td_maxwin == 0) {
534 /* We haven't seen traffic in the other
535 * direction yet but we have to tweak window
536 * tracking to pass III and IV until that
539 receiver->td_end = receiver->td_maxend = sack;
540 } else if (sack == receiver->td_end + 1) {
541 /* Likely a reply to a keepalive.
548 } else if (((state->state == TCP_CONNTRACK_SYN_SENT
549 && dir == IP_CT_DIR_ORIGINAL)
550 || (state->state == TCP_CONNTRACK_SYN_RECV
551 && dir == IP_CT_DIR_REPLY))
552 && after(end, sender->td_end)) {
554 * RFC 793: "if a TCP is reinitialized ... then it need
555 * not wait at all; it must only be sure to use sequence
556 * numbers larger than those recently used."
559 sender->td_maxend = end;
560 sender->td_maxwin = (win == 0 ? 1 : win);
562 tcp_options(skb, dataoff, tcph, sender);
567 * If there is no ACK, just pretend it was set and OK.
569 ack = sack = receiver->td_end;
570 } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
571 (TCP_FLAG_ACK|TCP_FLAG_RST))
574 * Broken TCP stacks, that set ACK in RST packets as well
575 * with zero ack value.
577 ack = sack = receiver->td_end;
580 if (tcph->rst && seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)
582 * RST sent answering SYN.
584 seq = end = sender->td_end;
586 pr_debug("tcp_in_window: ");
587 nf_ct_dump_tuple(tuple);
588 pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
589 seq, ack, receiver_offset, sack, receiver_offset, win, end);
590 pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
591 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
592 sender->td_end, sender->td_maxend, sender->td_maxwin,
594 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
597 /* Is the ending sequence in the receive window (if available)? */
598 in_recv_win = !receiver->td_maxwin ||
599 after(end, sender->td_end - receiver->td_maxwin - 1);
601 pr_debug("tcp_in_window: I=%i II=%i III=%i IV=%i\n",
602 before(seq, sender->td_maxend + 1),
603 (in_recv_win ? 1 : 0),
604 before(sack, receiver->td_end + 1),
605 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1));
607 if (before(seq, sender->td_maxend + 1) &&
609 before(sack, receiver->td_end + 1) &&
610 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1)) {
612 * Take into account window scaling (RFC 1323).
615 win <<= sender->td_scale;
618 * Update sender data.
620 swin = win + (sack - ack);
621 if (sender->td_maxwin < swin)
622 sender->td_maxwin = swin;
623 if (after(end, sender->td_end)) {
624 sender->td_end = end;
625 sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
628 if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) {
629 sender->td_maxack = ack;
630 sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET;
631 } else if (after(ack, sender->td_maxack))
632 sender->td_maxack = ack;
636 * Update receiver data.
638 if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
639 receiver->td_maxwin += end - sender->td_maxend;
640 if (after(sack + win, receiver->td_maxend - 1)) {
641 receiver->td_maxend = sack + win;
643 receiver->td_maxend++;
645 if (ack == receiver->td_end)
646 receiver->flags &= ~IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
649 * Check retransmissions.
651 if (index == TCP_ACK_SET) {
652 if (state->last_dir == dir
653 && state->last_seq == seq
654 && state->last_ack == ack
655 && state->last_end == end
656 && state->last_win == win_raw)
659 state->last_dir = dir;
660 state->last_seq = seq;
661 state->last_ack = ack;
662 state->last_end = end;
663 state->last_win = win_raw;
670 if (sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL ||
674 nf_ct_l4proto_log_invalid(skb, ct, hook_state,
676 before(seq, sender->td_maxend + 1) ?
678 before(sack, receiver->td_end + 1) ?
679 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1) ? "BUG"
680 : "ACK is under the lower bound (possible overly delayed ACK)"
681 : "ACK is over the upper bound (ACKed data not seen yet)"
682 : "SEQ is under the lower bound (already ACKed data retransmitted)"
683 : "SEQ is over the upper bound (over the window of the receiver)");
687 pr_debug("tcp_in_window: res=%u sender end=%u maxend=%u maxwin=%u "
688 "receiver end=%u maxend=%u maxwin=%u\n",
689 res, sender->td_end, sender->td_maxend, sender->td_maxwin,
690 receiver->td_end, receiver->td_maxend, receiver->td_maxwin);
695 /* table of valid flag combinations - PUSH, ECE and CWR are always valid */
696 static const u8 tcp_valid_flags[(TCPHDR_FIN|TCPHDR_SYN|TCPHDR_RST|TCPHDR_ACK|
700 [TCPHDR_SYN|TCPHDR_URG] = 1,
701 [TCPHDR_SYN|TCPHDR_ACK] = 1,
703 [TCPHDR_RST|TCPHDR_ACK] = 1,
704 [TCPHDR_FIN|TCPHDR_ACK] = 1,
705 [TCPHDR_FIN|TCPHDR_ACK|TCPHDR_URG] = 1,
707 [TCPHDR_ACK|TCPHDR_URG] = 1,
710 static void tcp_error_log(const struct sk_buff *skb,
711 const struct nf_hook_state *state,
714 nf_l4proto_log_invalid(skb, state, IPPROTO_TCP, "%s", msg);
717 /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c. */
718 static bool tcp_error(const struct tcphdr *th,
720 unsigned int dataoff,
721 const struct nf_hook_state *state)
723 unsigned int tcplen = skb->len - dataoff;
726 /* Not whole TCP header or malformed packet */
727 if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
728 tcp_error_log(skb, state, "truncated packet");
732 /* Checksum invalid? Ignore.
733 * We skip checking packets on the outgoing path
734 * because the checksum is assumed to be correct.
736 /* FIXME: Source route IP option packets --RR */
737 if (state->net->ct.sysctl_checksum &&
738 state->hook == NF_INET_PRE_ROUTING &&
739 nf_checksum(skb, state->hook, dataoff, IPPROTO_TCP, state->pf)) {
740 tcp_error_log(skb, state, "bad checksum");
744 /* Check TCP flags. */
745 tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
746 if (!tcp_valid_flags[tcpflags]) {
747 tcp_error_log(skb, state, "invalid tcp flag combination");
754 static noinline bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
755 unsigned int dataoff,
756 const struct tcphdr *th)
758 enum tcp_conntrack new_state;
759 struct net *net = nf_ct_net(ct);
760 const struct nf_tcp_net *tn = nf_tcp_pernet(net);
761 const struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[0];
762 const struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[1];
764 /* Don't need lock here: this conntrack not in circulation yet */
765 new_state = tcp_conntracks[0][get_conntrack_index(th)][TCP_CONNTRACK_NONE];
767 /* Invalid: delete conntrack */
768 if (new_state >= TCP_CONNTRACK_MAX) {
769 pr_debug("nf_ct_tcp: invalid new deleting.\n");
773 if (new_state == TCP_CONNTRACK_SYN_SENT) {
774 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
776 ct->proto.tcp.seen[0].td_end =
777 segment_seq_plus_len(ntohl(th->seq), skb->len,
779 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
780 if (ct->proto.tcp.seen[0].td_maxwin == 0)
781 ct->proto.tcp.seen[0].td_maxwin = 1;
782 ct->proto.tcp.seen[0].td_maxend =
783 ct->proto.tcp.seen[0].td_end;
785 tcp_options(skb, dataoff, th, &ct->proto.tcp.seen[0]);
786 } else if (tn->tcp_loose == 0) {
787 /* Don't try to pick up connections. */
790 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
792 * We are in the middle of a connection,
793 * its history is lost for us.
794 * Let's try to use the data from the packet.
796 ct->proto.tcp.seen[0].td_end =
797 segment_seq_plus_len(ntohl(th->seq), skb->len,
799 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
800 if (ct->proto.tcp.seen[0].td_maxwin == 0)
801 ct->proto.tcp.seen[0].td_maxwin = 1;
802 ct->proto.tcp.seen[0].td_maxend =
803 ct->proto.tcp.seen[0].td_end +
804 ct->proto.tcp.seen[0].td_maxwin;
806 /* We assume SACK and liberal window checking to handle
808 ct->proto.tcp.seen[0].flags =
809 ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
810 IP_CT_TCP_FLAG_BE_LIBERAL;
813 /* tcp_packet will set them */
814 ct->proto.tcp.last_index = TCP_NONE_SET;
816 pr_debug("%s: sender end=%u maxend=%u maxwin=%u scale=%i "
817 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
819 sender->td_end, sender->td_maxend, sender->td_maxwin,
821 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
826 /* Returns verdict for packet, or -1 for invalid. */
827 int nf_conntrack_tcp_packet(struct nf_conn *ct,
829 unsigned int dataoff,
830 enum ip_conntrack_info ctinfo,
831 const struct nf_hook_state *state)
833 struct net *net = nf_ct_net(ct);
834 struct nf_tcp_net *tn = nf_tcp_pernet(net);
835 struct nf_conntrack_tuple *tuple;
836 enum tcp_conntrack new_state, old_state;
837 unsigned int index, *timeouts;
838 enum ip_conntrack_dir dir;
839 const struct tcphdr *th;
841 unsigned long timeout;
843 th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
847 if (tcp_error(th, skb, dataoff, state))
850 if (!nf_ct_is_confirmed(ct) && !tcp_new(ct, skb, dataoff, th))
853 spin_lock_bh(&ct->lock);
854 old_state = ct->proto.tcp.state;
855 dir = CTINFO2DIR(ctinfo);
856 index = get_conntrack_index(th);
857 new_state = tcp_conntracks[dir][index][old_state];
858 tuple = &ct->tuplehash[dir].tuple;
861 case TCP_CONNTRACK_SYN_SENT:
862 if (old_state < TCP_CONNTRACK_TIME_WAIT)
864 /* RFC 1122: "When a connection is closed actively,
865 * it MUST linger in TIME-WAIT state for a time 2xMSL
866 * (Maximum Segment Lifetime). However, it MAY accept
867 * a new SYN from the remote TCP to reopen the connection
868 * directly from TIME-WAIT state, if..."
869 * We ignore the conditions because we are in the
870 * TIME-WAIT state anyway.
872 * Handle aborted connections: we and the server
873 * think there is an existing connection but the client
874 * aborts it and starts a new one.
876 if (((ct->proto.tcp.seen[dir].flags
877 | ct->proto.tcp.seen[!dir].flags)
878 & IP_CT_TCP_FLAG_CLOSE_INIT)
879 || (ct->proto.tcp.last_dir == dir
880 && ct->proto.tcp.last_index == TCP_RST_SET)) {
881 /* Attempt to reopen a closed/aborted connection.
882 * Delete this connection and look up again. */
883 spin_unlock_bh(&ct->lock);
885 /* Only repeat if we can actually remove the timer.
886 * Destruction may already be in progress in process
887 * context and we must give it a chance to terminate.
894 case TCP_CONNTRACK_IGNORE:
897 * Our connection entry may be out of sync, so ignore
898 * packets which may signal the real connection between
899 * the client and the server.
902 * b) SYN/ACK in REPLY
903 * c) ACK in reply direction after initial SYN in original.
905 * If the ignored packet is invalid, the receiver will send
906 * a RST we'll catch below.
908 if (index == TCP_SYNACK_SET
909 && ct->proto.tcp.last_index == TCP_SYN_SET
910 && ct->proto.tcp.last_dir != dir
911 && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
912 /* b) This SYN/ACK acknowledges a SYN that we earlier
913 * ignored as invalid. This means that the client and
914 * the server are both in sync, while the firewall is
915 * not. We get in sync from the previously annotated
918 old_state = TCP_CONNTRACK_SYN_SENT;
919 new_state = TCP_CONNTRACK_SYN_RECV;
920 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
921 ct->proto.tcp.last_end;
922 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
923 ct->proto.tcp.last_end;
924 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
925 ct->proto.tcp.last_win == 0 ?
926 1 : ct->proto.tcp.last_win;
927 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
928 ct->proto.tcp.last_wscale;
929 ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
930 ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
931 ct->proto.tcp.last_flags;
932 memset(&ct->proto.tcp.seen[dir], 0,
933 sizeof(struct ip_ct_tcp_state));
936 ct->proto.tcp.last_index = index;
937 ct->proto.tcp.last_dir = dir;
938 ct->proto.tcp.last_seq = ntohl(th->seq);
939 ct->proto.tcp.last_end =
940 segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
941 ct->proto.tcp.last_win = ntohs(th->window);
943 /* a) This is a SYN in ORIGINAL. The client and the server
944 * may be in sync but we are not. In that case, we annotate
945 * the TCP options and let the packet go through. If it is a
946 * valid SYN packet, the server will reply with a SYN/ACK, and
947 * then we'll get in sync. Otherwise, the server potentially
948 * responds with a challenge ACK if implementing RFC5961.
950 if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
951 struct ip_ct_tcp_state seen = {};
953 ct->proto.tcp.last_flags =
954 ct->proto.tcp.last_wscale = 0;
955 tcp_options(skb, dataoff, th, &seen);
956 if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
957 ct->proto.tcp.last_flags |=
958 IP_CT_TCP_FLAG_WINDOW_SCALE;
959 ct->proto.tcp.last_wscale = seen.td_scale;
961 if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
962 ct->proto.tcp.last_flags |=
963 IP_CT_TCP_FLAG_SACK_PERM;
965 /* Mark the potential for RFC5961 challenge ACK,
966 * this pose a special problem for LAST_ACK state
967 * as ACK is intrepretated as ACKing last FIN.
969 if (old_state == TCP_CONNTRACK_LAST_ACK)
970 ct->proto.tcp.last_flags |=
971 IP_CT_EXP_CHALLENGE_ACK;
973 spin_unlock_bh(&ct->lock);
974 nf_ct_l4proto_log_invalid(skb, ct, state,
975 "packet (index %d) in dir %d ignored, state %s",
977 tcp_conntrack_names[old_state]);
979 case TCP_CONNTRACK_MAX:
980 /* Special case for SYN proxy: when the SYN to the server or
981 * the SYN/ACK from the server is lost, the client may transmit
982 * a keep-alive packet while in SYN_SENT state. This needs to
983 * be associated with the original conntrack entry in order to
984 * generate a new SYN with the correct sequence number.
986 if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
987 index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
988 ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
989 ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
990 pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
991 spin_unlock_bh(&ct->lock);
996 pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
997 dir, get_conntrack_index(th), old_state);
998 spin_unlock_bh(&ct->lock);
999 nf_ct_l4proto_log_invalid(skb, ct, state, "invalid state");
1001 case TCP_CONNTRACK_TIME_WAIT:
1002 /* RFC5961 compliance cause stack to send "challenge-ACK"
1003 * e.g. in response to spurious SYNs. Conntrack MUST
1004 * not believe this ACK is acking last FIN.
1006 if (old_state == TCP_CONNTRACK_LAST_ACK &&
1007 index == TCP_ACK_SET &&
1008 ct->proto.tcp.last_dir != dir &&
1009 ct->proto.tcp.last_index == TCP_SYN_SET &&
1010 (ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
1011 /* Detected RFC5961 challenge ACK */
1012 ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1013 spin_unlock_bh(&ct->lock);
1014 nf_ct_l4proto_log_invalid(skb, ct, state, "challenge-ack ignored");
1015 return NF_ACCEPT; /* Don't change state */
1018 case TCP_CONNTRACK_SYN_SENT2:
1019 /* tcp_conntracks table is not smart enough to handle
1020 * simultaneous open.
1022 ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN;
1024 case TCP_CONNTRACK_SYN_RECV:
1025 if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET &&
1026 ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN)
1027 new_state = TCP_CONNTRACK_ESTABLISHED;
1029 case TCP_CONNTRACK_CLOSE:
1030 if (index != TCP_RST_SET)
1033 if (ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) {
1034 u32 seq = ntohl(th->seq);
1036 if (before(seq, ct->proto.tcp.seen[!dir].td_maxack)) {
1038 spin_unlock_bh(&ct->lock);
1039 nf_ct_l4proto_log_invalid(skb, ct, state, "invalid rst");
1043 if (!nf_conntrack_tcp_established(ct) ||
1044 seq == ct->proto.tcp.seen[!dir].td_maxack)
1047 /* Check if rst is part of train, such as
1048 * foo:80 > bar:4379: P, 235946583:235946602(19) ack 42
1049 * foo:80 > bar:4379: R, 235946602:235946602(0) ack 42
1051 if (ct->proto.tcp.last_index == TCP_ACK_SET &&
1052 ct->proto.tcp.last_dir == dir &&
1053 seq == ct->proto.tcp.last_end)
1056 /* ... RST sequence number doesn't match exactly, keep
1057 * established state to allow a possible challenge ACK.
1059 new_state = old_state;
1061 if (((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
1062 && ct->proto.tcp.last_index == TCP_SYN_SET)
1063 || (!test_bit(IPS_ASSURED_BIT, &ct->status)
1064 && ct->proto.tcp.last_index == TCP_ACK_SET))
1065 && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1066 /* RST sent to invalid SYN or ACK we had let through
1067 * at a) and c) above:
1069 * a) SYN was in window then
1070 * c) we hold a half-open connection.
1072 * Delete our connection entry.
1073 * We skip window checking, because packet might ACK
1074 * segments we ignored. */
1079 /* Keep compilers happy. */
1083 if (!tcp_in_window(ct, dir, index,
1084 skb, dataoff, th, state)) {
1085 spin_unlock_bh(&ct->lock);
1089 /* From now on we have got in-window packets */
1090 ct->proto.tcp.last_index = index;
1091 ct->proto.tcp.last_dir = dir;
1093 pr_debug("tcp_conntracks: ");
1094 nf_ct_dump_tuple(tuple);
1095 pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
1096 (th->syn ? 1 : 0), (th->ack ? 1 : 0),
1097 (th->fin ? 1 : 0), (th->rst ? 1 : 0),
1098 old_state, new_state);
1100 ct->proto.tcp.state = new_state;
1101 if (old_state != new_state
1102 && new_state == TCP_CONNTRACK_FIN_WAIT)
1103 ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
1105 timeouts = nf_ct_timeout_lookup(ct);
1107 timeouts = tn->timeouts;
1109 if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
1110 timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1111 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1112 else if (unlikely(index == TCP_RST_SET))
1113 timeout = timeouts[TCP_CONNTRACK_CLOSE];
1114 else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
1115 IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
1116 timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
1117 timeout = timeouts[TCP_CONNTRACK_UNACK];
1118 else if (ct->proto.tcp.last_win == 0 &&
1119 timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1120 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1122 timeout = timeouts[new_state];
1123 spin_unlock_bh(&ct->lock);
1125 if (new_state != old_state)
1126 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
1128 if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
1129 /* If only reply is a RST, we can consider ourselves not to
1130 have an established connection: this is a fairly common
1131 problem case, so we can delete the conntrack
1132 immediately. --RR */
1134 nf_ct_kill_acct(ct, ctinfo, skb);
1137 /* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
1138 * pickup with loose=1. Avoid large ESTABLISHED timeout.
1140 if (new_state == TCP_CONNTRACK_ESTABLISHED &&
1141 timeout > timeouts[TCP_CONNTRACK_UNACK])
1142 timeout = timeouts[TCP_CONNTRACK_UNACK];
1143 } else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
1144 && (old_state == TCP_CONNTRACK_SYN_RECV
1145 || old_state == TCP_CONNTRACK_ESTABLISHED)
1146 && new_state == TCP_CONNTRACK_ESTABLISHED) {
1147 /* Set ASSURED if we see valid ack in ESTABLISHED
1148 after SYN_RECV or a valid answer for a picked up
1150 set_bit(IPS_ASSURED_BIT, &ct->status);
1151 nf_conntrack_event_cache(IPCT_ASSURED, ct);
1153 nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
1158 static bool tcp_can_early_drop(const struct nf_conn *ct)
1160 switch (ct->proto.tcp.state) {
1161 case TCP_CONNTRACK_FIN_WAIT:
1162 case TCP_CONNTRACK_LAST_ACK:
1163 case TCP_CONNTRACK_TIME_WAIT:
1164 case TCP_CONNTRACK_CLOSE:
1165 case TCP_CONNTRACK_CLOSE_WAIT:
1174 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1176 #include <linux/netfilter/nfnetlink.h>
1177 #include <linux/netfilter/nfnetlink_conntrack.h>
1179 static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1180 struct nf_conn *ct, bool destroy)
1182 struct nlattr *nest_parms;
1183 struct nf_ct_tcp_flags tmp = {};
1185 spin_lock_bh(&ct->lock);
1186 nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP);
1188 goto nla_put_failure;
1190 if (nla_put_u8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state))
1191 goto nla_put_failure;
1196 if (nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1197 ct->proto.tcp.seen[0].td_scale) ||
1198 nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
1199 ct->proto.tcp.seen[1].td_scale))
1200 goto nla_put_failure;
1202 tmp.flags = ct->proto.tcp.seen[0].flags;
1203 if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1204 sizeof(struct nf_ct_tcp_flags), &tmp))
1205 goto nla_put_failure;
1207 tmp.flags = ct->proto.tcp.seen[1].flags;
1208 if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1209 sizeof(struct nf_ct_tcp_flags), &tmp))
1210 goto nla_put_failure;
1212 spin_unlock_bh(&ct->lock);
1213 nla_nest_end(skb, nest_parms);
1218 spin_unlock_bh(&ct->lock);
1222 static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1223 [CTA_PROTOINFO_TCP_STATE] = { .type = NLA_U8 },
1224 [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1225 [CTA_PROTOINFO_TCP_WSCALE_REPLY] = { .type = NLA_U8 },
1226 [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL] = { .len = sizeof(struct nf_ct_tcp_flags) },
1227 [CTA_PROTOINFO_TCP_FLAGS_REPLY] = { .len = sizeof(struct nf_ct_tcp_flags) },
1230 #define TCP_NLATTR_SIZE ( \
1231 NLA_ALIGN(NLA_HDRLEN + 1) + \
1232 NLA_ALIGN(NLA_HDRLEN + 1) + \
1233 NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)) + \
1234 NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)))
1236 static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1238 struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
1239 struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1242 /* updates could not contain anything about the private
1243 * protocol info, in that case skip the parsing */
1247 err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_TCP_MAX, pattr,
1248 tcp_nla_policy, NULL);
1252 if (tb[CTA_PROTOINFO_TCP_STATE] &&
1253 nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
1256 spin_lock_bh(&ct->lock);
1257 if (tb[CTA_PROTOINFO_TCP_STATE])
1258 ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
1260 if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1261 struct nf_ct_tcp_flags *attr =
1262 nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1263 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1264 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1267 if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1268 struct nf_ct_tcp_flags *attr =
1269 nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1270 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1271 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1274 if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1275 tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1276 ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1277 ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1278 ct->proto.tcp.seen[0].td_scale =
1279 nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1280 ct->proto.tcp.seen[1].td_scale =
1281 nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1283 spin_unlock_bh(&ct->lock);
1288 static unsigned int tcp_nlattr_tuple_size(void)
1290 static unsigned int size __read_mostly;
1293 size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
1299 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1301 #include <linux/netfilter/nfnetlink.h>
1302 #include <linux/netfilter/nfnetlink_cttimeout.h>
1304 static int tcp_timeout_nlattr_to_obj(struct nlattr *tb[],
1305 struct net *net, void *data)
1307 struct nf_tcp_net *tn = nf_tcp_pernet(net);
1308 unsigned int *timeouts = data;
1312 timeouts = tn->timeouts;
1313 /* set default TCP timeouts. */
1314 for (i=0; i<TCP_CONNTRACK_TIMEOUT_MAX; i++)
1315 timeouts[i] = tn->timeouts[i];
1317 if (tb[CTA_TIMEOUT_TCP_SYN_SENT]) {
1318 timeouts[TCP_CONNTRACK_SYN_SENT] =
1319 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT]))*HZ;
1322 if (tb[CTA_TIMEOUT_TCP_SYN_RECV]) {
1323 timeouts[TCP_CONNTRACK_SYN_RECV] =
1324 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_RECV]))*HZ;
1326 if (tb[CTA_TIMEOUT_TCP_ESTABLISHED]) {
1327 timeouts[TCP_CONNTRACK_ESTABLISHED] =
1328 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_ESTABLISHED]))*HZ;
1330 if (tb[CTA_TIMEOUT_TCP_FIN_WAIT]) {
1331 timeouts[TCP_CONNTRACK_FIN_WAIT] =
1332 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_FIN_WAIT]))*HZ;
1334 if (tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]) {
1335 timeouts[TCP_CONNTRACK_CLOSE_WAIT] =
1336 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]))*HZ;
1338 if (tb[CTA_TIMEOUT_TCP_LAST_ACK]) {
1339 timeouts[TCP_CONNTRACK_LAST_ACK] =
1340 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_LAST_ACK]))*HZ;
1342 if (tb[CTA_TIMEOUT_TCP_TIME_WAIT]) {
1343 timeouts[TCP_CONNTRACK_TIME_WAIT] =
1344 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_TIME_WAIT]))*HZ;
1346 if (tb[CTA_TIMEOUT_TCP_CLOSE]) {
1347 timeouts[TCP_CONNTRACK_CLOSE] =
1348 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE]))*HZ;
1350 if (tb[CTA_TIMEOUT_TCP_SYN_SENT2]) {
1351 timeouts[TCP_CONNTRACK_SYN_SENT2] =
1352 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT2]))*HZ;
1354 if (tb[CTA_TIMEOUT_TCP_RETRANS]) {
1355 timeouts[TCP_CONNTRACK_RETRANS] =
1356 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_RETRANS]))*HZ;
1358 if (tb[CTA_TIMEOUT_TCP_UNACK]) {
1359 timeouts[TCP_CONNTRACK_UNACK] =
1360 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_UNACK]))*HZ;
1363 timeouts[CTA_TIMEOUT_TCP_UNSPEC] = timeouts[CTA_TIMEOUT_TCP_SYN_SENT];
1368 tcp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
1370 const unsigned int *timeouts = data;
1372 if (nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT,
1373 htonl(timeouts[TCP_CONNTRACK_SYN_SENT] / HZ)) ||
1374 nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_RECV,
1375 htonl(timeouts[TCP_CONNTRACK_SYN_RECV] / HZ)) ||
1376 nla_put_be32(skb, CTA_TIMEOUT_TCP_ESTABLISHED,
1377 htonl(timeouts[TCP_CONNTRACK_ESTABLISHED] / HZ)) ||
1378 nla_put_be32(skb, CTA_TIMEOUT_TCP_FIN_WAIT,
1379 htonl(timeouts[TCP_CONNTRACK_FIN_WAIT] / HZ)) ||
1380 nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE_WAIT,
1381 htonl(timeouts[TCP_CONNTRACK_CLOSE_WAIT] / HZ)) ||
1382 nla_put_be32(skb, CTA_TIMEOUT_TCP_LAST_ACK,
1383 htonl(timeouts[TCP_CONNTRACK_LAST_ACK] / HZ)) ||
1384 nla_put_be32(skb, CTA_TIMEOUT_TCP_TIME_WAIT,
1385 htonl(timeouts[TCP_CONNTRACK_TIME_WAIT] / HZ)) ||
1386 nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE,
1387 htonl(timeouts[TCP_CONNTRACK_CLOSE] / HZ)) ||
1388 nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT2,
1389 htonl(timeouts[TCP_CONNTRACK_SYN_SENT2] / HZ)) ||
1390 nla_put_be32(skb, CTA_TIMEOUT_TCP_RETRANS,
1391 htonl(timeouts[TCP_CONNTRACK_RETRANS] / HZ)) ||
1392 nla_put_be32(skb, CTA_TIMEOUT_TCP_UNACK,
1393 htonl(timeouts[TCP_CONNTRACK_UNACK] / HZ)))
1394 goto nla_put_failure;
1401 static const struct nla_policy tcp_timeout_nla_policy[CTA_TIMEOUT_TCP_MAX+1] = {
1402 [CTA_TIMEOUT_TCP_SYN_SENT] = { .type = NLA_U32 },
1403 [CTA_TIMEOUT_TCP_SYN_RECV] = { .type = NLA_U32 },
1404 [CTA_TIMEOUT_TCP_ESTABLISHED] = { .type = NLA_U32 },
1405 [CTA_TIMEOUT_TCP_FIN_WAIT] = { .type = NLA_U32 },
1406 [CTA_TIMEOUT_TCP_CLOSE_WAIT] = { .type = NLA_U32 },
1407 [CTA_TIMEOUT_TCP_LAST_ACK] = { .type = NLA_U32 },
1408 [CTA_TIMEOUT_TCP_TIME_WAIT] = { .type = NLA_U32 },
1409 [CTA_TIMEOUT_TCP_CLOSE] = { .type = NLA_U32 },
1410 [CTA_TIMEOUT_TCP_SYN_SENT2] = { .type = NLA_U32 },
1411 [CTA_TIMEOUT_TCP_RETRANS] = { .type = NLA_U32 },
1412 [CTA_TIMEOUT_TCP_UNACK] = { .type = NLA_U32 },
1414 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1416 void nf_conntrack_tcp_init_net(struct net *net)
1418 struct nf_tcp_net *tn = nf_tcp_pernet(net);
1421 for (i = 0; i < TCP_CONNTRACK_TIMEOUT_MAX; i++)
1422 tn->timeouts[i] = tcp_timeouts[i];
1424 /* timeouts[0] is unused, make it same as SYN_SENT so
1425 * ->timeouts[0] contains 'new' timeout, like udp or icmp.
1427 tn->timeouts[0] = tcp_timeouts[TCP_CONNTRACK_SYN_SENT];
1429 /* If it is set to zero, we disable picking up already established
1434 /* "Be conservative in what you do,
1435 * be liberal in what you accept from others."
1436 * If it's non-zero, we mark only out of window RST segments as INVALID.
1438 tn->tcp_be_liberal = 0;
1440 /* Max number of the retransmitted packets without receiving an (acceptable)
1441 * ACK from the destination. If this number is reached, a shorter timer
1444 tn->tcp_max_retrans = 3;
1446 #if IS_ENABLED(CONFIG_NF_FLOW_TABLE)
1447 tn->offload_timeout = 30 * HZ;
1448 tn->offload_pickup = 120 * HZ;
1452 const struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp =
1454 .l4proto = IPPROTO_TCP,
1455 #ifdef CONFIG_NF_CONNTRACK_PROCFS
1456 .print_conntrack = tcp_print_conntrack,
1458 .can_early_drop = tcp_can_early_drop,
1459 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1460 .to_nlattr = tcp_to_nlattr,
1461 .from_nlattr = nlattr_to_tcp,
1462 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
1463 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
1464 .nlattr_tuple_size = tcp_nlattr_tuple_size,
1465 .nlattr_size = TCP_NLATTR_SIZE,
1466 .nla_policy = nf_ct_port_nla_policy,
1468 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1470 .nlattr_to_obj = tcp_timeout_nlattr_to_obj,
1471 .obj_to_nlattr = tcp_timeout_obj_to_nlattr,
1472 .nlattr_max = CTA_TIMEOUT_TCP_MAX,
1473 .obj_size = sizeof(unsigned int) *
1474 TCP_CONNTRACK_TIMEOUT_MAX,
1475 .nla_policy = tcp_timeout_nla_policy,
1477 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */