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),
353 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
360 if (opsize < 2) /* "silly options" */
363 return; /* don't parse partial options */
365 if (opcode == TCPOPT_SACK_PERM
366 && opsize == TCPOLEN_SACK_PERM)
367 state->flags |= IP_CT_TCP_FLAG_SACK_PERM;
368 else if (opcode == TCPOPT_WINDOW
369 && opsize == TCPOLEN_WINDOW) {
370 state->td_scale = *(u_int8_t *)ptr;
372 if (state->td_scale > TCP_MAX_WSCALE)
373 state->td_scale = TCP_MAX_WSCALE;
376 IP_CT_TCP_FLAG_WINDOW_SCALE;
384 static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
385 const struct tcphdr *tcph, __u32 *sack)
387 unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
388 const unsigned char *ptr;
389 int length = (tcph->doff*4) - sizeof(struct tcphdr);
395 ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
399 /* Fast path for timestamp-only option */
400 if (length == TCPOLEN_TSTAMP_ALIGNED
401 && *(__be32 *)ptr == htonl((TCPOPT_NOP << 24)
403 | (TCPOPT_TIMESTAMP << 8)
404 | TCPOLEN_TIMESTAMP))
414 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
421 if (opsize < 2) /* "silly options" */
424 return; /* don't parse partial options */
426 if (opcode == TCPOPT_SACK
427 && opsize >= (TCPOLEN_SACK_BASE
428 + TCPOLEN_SACK_PERBLOCK)
429 && !((opsize - TCPOLEN_SACK_BASE)
430 % TCPOLEN_SACK_PERBLOCK)) {
432 i < (opsize - TCPOLEN_SACK_BASE);
433 i += TCPOLEN_SACK_PERBLOCK) {
434 tmp = get_unaligned_be32((__be32 *)(ptr+i)+1);
436 if (after(tmp, *sack))
447 static bool tcp_in_window(const struct nf_conn *ct,
448 struct ip_ct_tcp *state,
449 enum ip_conntrack_dir dir,
451 const struct sk_buff *skb,
452 unsigned int dataoff,
453 const struct tcphdr *tcph)
455 struct net *net = nf_ct_net(ct);
456 struct nf_tcp_net *tn = nf_tcp_pernet(net);
457 struct ip_ct_tcp_state *sender = &state->seen[dir];
458 struct ip_ct_tcp_state *receiver = &state->seen[!dir];
459 const struct nf_conntrack_tuple *tuple = &ct->tuplehash[dir].tuple;
460 __u32 seq, ack, sack, end, win, swin;
463 bool res, in_recv_win;
466 * Get the required data from the packet.
468 seq = ntohl(tcph->seq);
469 ack = sack = ntohl(tcph->ack_seq);
470 win_raw = ntohs(tcph->window);
472 end = segment_seq_plus_len(seq, skb->len, dataoff, tcph);
474 if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
475 tcp_sack(skb, dataoff, tcph, &sack);
477 /* Take into account NAT sequence number mangling */
478 receiver_offset = nf_ct_seq_offset(ct, !dir, ack - 1);
479 ack -= receiver_offset;
480 sack -= receiver_offset;
482 pr_debug("tcp_in_window: START\n");
483 pr_debug("tcp_in_window: ");
484 nf_ct_dump_tuple(tuple);
485 pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
486 seq, ack, receiver_offset, sack, receiver_offset, win, end);
487 pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
488 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
489 sender->td_end, sender->td_maxend, sender->td_maxwin,
491 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
494 if (sender->td_maxwin == 0) {
496 * Initialize sender data.
500 * SYN-ACK in reply to a SYN
501 * or SYN from reply direction in simultaneous open.
504 sender->td_maxend = end;
505 sender->td_maxwin = (win == 0 ? 1 : win);
507 tcp_options(skb, dataoff, tcph, sender);
510 * Both sides must send the Window Scale option
511 * to enable window scaling in either direction.
513 if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE
514 && receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE))
516 receiver->td_scale = 0;
518 /* Simultaneous open */
522 * We are in the middle of a connection,
523 * its history is lost for us.
524 * Let's try to use the data from the packet.
526 sender->td_end = end;
527 swin = win << sender->td_scale;
528 sender->td_maxwin = (swin == 0 ? 1 : swin);
529 sender->td_maxend = end + sender->td_maxwin;
530 if (receiver->td_maxwin == 0) {
531 /* We haven't seen traffic in the other
532 * direction yet but we have to tweak window
533 * tracking to pass III and IV until that
536 receiver->td_end = receiver->td_maxend = sack;
537 } else if (sack == receiver->td_end + 1) {
538 /* Likely a reply to a keepalive.
545 } else if (((state->state == TCP_CONNTRACK_SYN_SENT
546 && dir == IP_CT_DIR_ORIGINAL)
547 || (state->state == TCP_CONNTRACK_SYN_RECV
548 && dir == IP_CT_DIR_REPLY))
549 && after(end, sender->td_end)) {
551 * RFC 793: "if a TCP is reinitialized ... then it need
552 * not wait at all; it must only be sure to use sequence
553 * numbers larger than those recently used."
556 sender->td_maxend = end;
557 sender->td_maxwin = (win == 0 ? 1 : win);
559 tcp_options(skb, dataoff, tcph, sender);
564 * If there is no ACK, just pretend it was set and OK.
566 ack = sack = receiver->td_end;
567 } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
568 (TCP_FLAG_ACK|TCP_FLAG_RST))
571 * Broken TCP stacks, that set ACK in RST packets as well
572 * with zero ack value.
574 ack = sack = receiver->td_end;
577 if (tcph->rst && seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)
579 * RST sent answering SYN.
581 seq = end = sender->td_end;
583 pr_debug("tcp_in_window: ");
584 nf_ct_dump_tuple(tuple);
585 pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
586 seq, ack, receiver_offset, sack, receiver_offset, win, end);
587 pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
588 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
589 sender->td_end, sender->td_maxend, sender->td_maxwin,
591 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
594 /* Is the ending sequence in the receive window (if available)? */
595 in_recv_win = !receiver->td_maxwin ||
596 after(end, sender->td_end - receiver->td_maxwin - 1);
598 pr_debug("tcp_in_window: I=%i II=%i III=%i IV=%i\n",
599 before(seq, sender->td_maxend + 1),
600 (in_recv_win ? 1 : 0),
601 before(sack, receiver->td_end + 1),
602 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1));
604 if (before(seq, sender->td_maxend + 1) &&
606 before(sack, receiver->td_end + 1) &&
607 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1)) {
609 * Take into account window scaling (RFC 1323).
612 win <<= sender->td_scale;
615 * Update sender data.
617 swin = win + (sack - ack);
618 if (sender->td_maxwin < swin)
619 sender->td_maxwin = swin;
620 if (after(end, sender->td_end)) {
621 sender->td_end = end;
622 sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
625 if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) {
626 sender->td_maxack = ack;
627 sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET;
628 } else if (after(ack, sender->td_maxack))
629 sender->td_maxack = ack;
633 * Update receiver data.
635 if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
636 receiver->td_maxwin += end - sender->td_maxend;
637 if (after(sack + win, receiver->td_maxend - 1)) {
638 receiver->td_maxend = sack + win;
640 receiver->td_maxend++;
642 if (ack == receiver->td_end)
643 receiver->flags &= ~IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
646 * Check retransmissions.
648 if (index == TCP_ACK_SET) {
649 if (state->last_dir == dir
650 && state->last_seq == seq
651 && state->last_ack == ack
652 && state->last_end == end
653 && state->last_win == win_raw)
656 state->last_dir = dir;
657 state->last_seq = seq;
658 state->last_ack = ack;
659 state->last_end = end;
660 state->last_win = win_raw;
667 if (sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL ||
671 nf_ct_l4proto_log_invalid(skb, ct,
673 before(seq, sender->td_maxend + 1) ?
675 before(sack, receiver->td_end + 1) ?
676 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1) ? "BUG"
677 : "ACK is under the lower bound (possible overly delayed ACK)"
678 : "ACK is over the upper bound (ACKed data not seen yet)"
679 : "SEQ is under the lower bound (already ACKed data retransmitted)"
680 : "SEQ is over the upper bound (over the window of the receiver)");
684 pr_debug("tcp_in_window: res=%u sender end=%u maxend=%u maxwin=%u "
685 "receiver end=%u maxend=%u maxwin=%u\n",
686 res, sender->td_end, sender->td_maxend, sender->td_maxwin,
687 receiver->td_end, receiver->td_maxend, receiver->td_maxwin);
692 /* table of valid flag combinations - PUSH, ECE and CWR are always valid */
693 static const u8 tcp_valid_flags[(TCPHDR_FIN|TCPHDR_SYN|TCPHDR_RST|TCPHDR_ACK|
697 [TCPHDR_SYN|TCPHDR_URG] = 1,
698 [TCPHDR_SYN|TCPHDR_ACK] = 1,
700 [TCPHDR_RST|TCPHDR_ACK] = 1,
701 [TCPHDR_FIN|TCPHDR_ACK] = 1,
702 [TCPHDR_FIN|TCPHDR_ACK|TCPHDR_URG] = 1,
704 [TCPHDR_ACK|TCPHDR_URG] = 1,
707 static void tcp_error_log(const struct sk_buff *skb,
708 const struct nf_hook_state *state,
711 nf_l4proto_log_invalid(skb, state->net, state->pf, IPPROTO_TCP, "%s", msg);
714 /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c. */
715 static bool tcp_error(const struct tcphdr *th,
717 unsigned int dataoff,
718 const struct nf_hook_state *state)
720 unsigned int tcplen = skb->len - dataoff;
723 /* Not whole TCP header or malformed packet */
724 if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
725 tcp_error_log(skb, state, "truncated packet");
729 /* Checksum invalid? Ignore.
730 * We skip checking packets on the outgoing path
731 * because the checksum is assumed to be correct.
733 /* FIXME: Source route IP option packets --RR */
734 if (state->net->ct.sysctl_checksum &&
735 state->hook == NF_INET_PRE_ROUTING &&
736 nf_checksum(skb, state->hook, dataoff, IPPROTO_TCP, state->pf)) {
737 tcp_error_log(skb, state, "bad checksum");
741 /* Check TCP flags. */
742 tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
743 if (!tcp_valid_flags[tcpflags]) {
744 tcp_error_log(skb, state, "invalid tcp flag combination");
751 static noinline bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
752 unsigned int dataoff,
753 const struct tcphdr *th)
755 enum tcp_conntrack new_state;
756 struct net *net = nf_ct_net(ct);
757 const struct nf_tcp_net *tn = nf_tcp_pernet(net);
758 const struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[0];
759 const struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[1];
761 /* Don't need lock here: this conntrack not in circulation yet */
762 new_state = tcp_conntracks[0][get_conntrack_index(th)][TCP_CONNTRACK_NONE];
764 /* Invalid: delete conntrack */
765 if (new_state >= TCP_CONNTRACK_MAX) {
766 pr_debug("nf_ct_tcp: invalid new deleting.\n");
770 if (new_state == TCP_CONNTRACK_SYN_SENT) {
771 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
773 ct->proto.tcp.seen[0].td_end =
774 segment_seq_plus_len(ntohl(th->seq), skb->len,
776 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
777 if (ct->proto.tcp.seen[0].td_maxwin == 0)
778 ct->proto.tcp.seen[0].td_maxwin = 1;
779 ct->proto.tcp.seen[0].td_maxend =
780 ct->proto.tcp.seen[0].td_end;
782 tcp_options(skb, dataoff, th, &ct->proto.tcp.seen[0]);
783 } else if (tn->tcp_loose == 0) {
784 /* Don't try to pick up connections. */
787 memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
789 * We are in the middle of a connection,
790 * its history is lost for us.
791 * Let's try to use the data from the packet.
793 ct->proto.tcp.seen[0].td_end =
794 segment_seq_plus_len(ntohl(th->seq), skb->len,
796 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
797 if (ct->proto.tcp.seen[0].td_maxwin == 0)
798 ct->proto.tcp.seen[0].td_maxwin = 1;
799 ct->proto.tcp.seen[0].td_maxend =
800 ct->proto.tcp.seen[0].td_end +
801 ct->proto.tcp.seen[0].td_maxwin;
803 /* We assume SACK and liberal window checking to handle
805 ct->proto.tcp.seen[0].flags =
806 ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
807 IP_CT_TCP_FLAG_BE_LIBERAL;
810 /* tcp_packet will set them */
811 ct->proto.tcp.last_index = TCP_NONE_SET;
813 pr_debug("%s: sender end=%u maxend=%u maxwin=%u scale=%i "
814 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
816 sender->td_end, sender->td_maxend, sender->td_maxwin,
818 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
823 /* Returns verdict for packet, or -1 for invalid. */
824 int nf_conntrack_tcp_packet(struct nf_conn *ct,
826 unsigned int dataoff,
827 enum ip_conntrack_info ctinfo,
828 const struct nf_hook_state *state)
830 struct net *net = nf_ct_net(ct);
831 struct nf_tcp_net *tn = nf_tcp_pernet(net);
832 struct nf_conntrack_tuple *tuple;
833 enum tcp_conntrack new_state, old_state;
834 unsigned int index, *timeouts;
835 enum ip_conntrack_dir dir;
836 const struct tcphdr *th;
838 unsigned long timeout;
840 th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
844 if (tcp_error(th, skb, dataoff, state))
847 if (!nf_ct_is_confirmed(ct) && !tcp_new(ct, skb, dataoff, th))
850 spin_lock_bh(&ct->lock);
851 old_state = ct->proto.tcp.state;
852 dir = CTINFO2DIR(ctinfo);
853 index = get_conntrack_index(th);
854 new_state = tcp_conntracks[dir][index][old_state];
855 tuple = &ct->tuplehash[dir].tuple;
858 case TCP_CONNTRACK_SYN_SENT:
859 if (old_state < TCP_CONNTRACK_TIME_WAIT)
861 /* RFC 1122: "When a connection is closed actively,
862 * it MUST linger in TIME-WAIT state for a time 2xMSL
863 * (Maximum Segment Lifetime). However, it MAY accept
864 * a new SYN from the remote TCP to reopen the connection
865 * directly from TIME-WAIT state, if..."
866 * We ignore the conditions because we are in the
867 * TIME-WAIT state anyway.
869 * Handle aborted connections: we and the server
870 * think there is an existing connection but the client
871 * aborts it and starts a new one.
873 if (((ct->proto.tcp.seen[dir].flags
874 | ct->proto.tcp.seen[!dir].flags)
875 & IP_CT_TCP_FLAG_CLOSE_INIT)
876 || (ct->proto.tcp.last_dir == dir
877 && ct->proto.tcp.last_index == TCP_RST_SET)) {
878 /* Attempt to reopen a closed/aborted connection.
879 * Delete this connection and look up again. */
880 spin_unlock_bh(&ct->lock);
882 /* Only repeat if we can actually remove the timer.
883 * Destruction may already be in progress in process
884 * context and we must give it a chance to terminate.
891 case TCP_CONNTRACK_IGNORE:
894 * Our connection entry may be out of sync, so ignore
895 * packets which may signal the real connection between
896 * the client and the server.
899 * b) SYN/ACK in REPLY
900 * c) ACK in reply direction after initial SYN in original.
902 * If the ignored packet is invalid, the receiver will send
903 * a RST we'll catch below.
905 if (index == TCP_SYNACK_SET
906 && ct->proto.tcp.last_index == TCP_SYN_SET
907 && ct->proto.tcp.last_dir != dir
908 && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
909 /* b) This SYN/ACK acknowledges a SYN that we earlier
910 * ignored as invalid. This means that the client and
911 * the server are both in sync, while the firewall is
912 * not. We get in sync from the previously annotated
915 old_state = TCP_CONNTRACK_SYN_SENT;
916 new_state = TCP_CONNTRACK_SYN_RECV;
917 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
918 ct->proto.tcp.last_end;
919 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
920 ct->proto.tcp.last_end;
921 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
922 ct->proto.tcp.last_win == 0 ?
923 1 : ct->proto.tcp.last_win;
924 ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
925 ct->proto.tcp.last_wscale;
926 ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
927 ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
928 ct->proto.tcp.last_flags;
929 memset(&ct->proto.tcp.seen[dir], 0,
930 sizeof(struct ip_ct_tcp_state));
933 ct->proto.tcp.last_index = index;
934 ct->proto.tcp.last_dir = dir;
935 ct->proto.tcp.last_seq = ntohl(th->seq);
936 ct->proto.tcp.last_end =
937 segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
938 ct->proto.tcp.last_win = ntohs(th->window);
940 /* a) This is a SYN in ORIGINAL. The client and the server
941 * may be in sync but we are not. In that case, we annotate
942 * the TCP options and let the packet go through. If it is a
943 * valid SYN packet, the server will reply with a SYN/ACK, and
944 * then we'll get in sync. Otherwise, the server potentially
945 * responds with a challenge ACK if implementing RFC5961.
947 if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
948 struct ip_ct_tcp_state seen = {};
950 ct->proto.tcp.last_flags =
951 ct->proto.tcp.last_wscale = 0;
952 tcp_options(skb, dataoff, th, &seen);
953 if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
954 ct->proto.tcp.last_flags |=
955 IP_CT_TCP_FLAG_WINDOW_SCALE;
956 ct->proto.tcp.last_wscale = seen.td_scale;
958 if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
959 ct->proto.tcp.last_flags |=
960 IP_CT_TCP_FLAG_SACK_PERM;
962 /* Mark the potential for RFC5961 challenge ACK,
963 * this pose a special problem for LAST_ACK state
964 * as ACK is intrepretated as ACKing last FIN.
966 if (old_state == TCP_CONNTRACK_LAST_ACK)
967 ct->proto.tcp.last_flags |=
968 IP_CT_EXP_CHALLENGE_ACK;
970 spin_unlock_bh(&ct->lock);
971 nf_ct_l4proto_log_invalid(skb, ct,
972 "packet (index %d) in dir %d ignored, state %s",
974 tcp_conntrack_names[old_state]);
976 case TCP_CONNTRACK_MAX:
977 /* Special case for SYN proxy: when the SYN to the server or
978 * the SYN/ACK from the server is lost, the client may transmit
979 * a keep-alive packet while in SYN_SENT state. This needs to
980 * be associated with the original conntrack entry in order to
981 * generate a new SYN with the correct sequence number.
983 if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
984 index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
985 ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
986 ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
987 pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
988 spin_unlock_bh(&ct->lock);
993 pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
994 dir, get_conntrack_index(th), old_state);
995 spin_unlock_bh(&ct->lock);
996 nf_ct_l4proto_log_invalid(skb, ct, "invalid state");
998 case TCP_CONNTRACK_TIME_WAIT:
999 /* RFC5961 compliance cause stack to send "challenge-ACK"
1000 * e.g. in response to spurious SYNs. Conntrack MUST
1001 * not believe this ACK is acking last FIN.
1003 if (old_state == TCP_CONNTRACK_LAST_ACK &&
1004 index == TCP_ACK_SET &&
1005 ct->proto.tcp.last_dir != dir &&
1006 ct->proto.tcp.last_index == TCP_SYN_SET &&
1007 (ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
1008 /* Detected RFC5961 challenge ACK */
1009 ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
1010 spin_unlock_bh(&ct->lock);
1011 nf_ct_l4proto_log_invalid(skb, ct, "challenge-ack ignored");
1012 return NF_ACCEPT; /* Don't change state */
1015 case TCP_CONNTRACK_SYN_SENT2:
1016 /* tcp_conntracks table is not smart enough to handle
1017 * simultaneous open.
1019 ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN;
1021 case TCP_CONNTRACK_SYN_RECV:
1022 if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET &&
1023 ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN)
1024 new_state = TCP_CONNTRACK_ESTABLISHED;
1026 case TCP_CONNTRACK_CLOSE:
1027 if (index != TCP_RST_SET)
1030 if (ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) {
1031 u32 seq = ntohl(th->seq);
1033 if (before(seq, ct->proto.tcp.seen[!dir].td_maxack)) {
1035 spin_unlock_bh(&ct->lock);
1036 nf_ct_l4proto_log_invalid(skb, ct, "invalid rst");
1040 if (!nf_conntrack_tcp_established(ct) ||
1041 seq == ct->proto.tcp.seen[!dir].td_maxack)
1044 /* Check if rst is part of train, such as
1045 * foo:80 > bar:4379: P, 235946583:235946602(19) ack 42
1046 * foo:80 > bar:4379: R, 235946602:235946602(0) ack 42
1048 if (ct->proto.tcp.last_index == TCP_ACK_SET &&
1049 ct->proto.tcp.last_dir == dir &&
1050 seq == ct->proto.tcp.last_end)
1053 /* ... RST sequence number doesn't match exactly, keep
1054 * established state to allow a possible challenge ACK.
1056 new_state = old_state;
1058 if (((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
1059 && ct->proto.tcp.last_index == TCP_SYN_SET)
1060 || (!test_bit(IPS_ASSURED_BIT, &ct->status)
1061 && ct->proto.tcp.last_index == TCP_ACK_SET))
1062 && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
1063 /* RST sent to invalid SYN or ACK we had let through
1064 * at a) and c) above:
1066 * a) SYN was in window then
1067 * c) we hold a half-open connection.
1069 * Delete our connection entry.
1070 * We skip window checking, because packet might ACK
1071 * segments we ignored. */
1076 /* Keep compilers happy. */
1080 if (!tcp_in_window(ct, &ct->proto.tcp, dir, index,
1081 skb, dataoff, th)) {
1082 spin_unlock_bh(&ct->lock);
1086 /* From now on we have got in-window packets */
1087 ct->proto.tcp.last_index = index;
1088 ct->proto.tcp.last_dir = dir;
1090 pr_debug("tcp_conntracks: ");
1091 nf_ct_dump_tuple(tuple);
1092 pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
1093 (th->syn ? 1 : 0), (th->ack ? 1 : 0),
1094 (th->fin ? 1 : 0), (th->rst ? 1 : 0),
1095 old_state, new_state);
1097 ct->proto.tcp.state = new_state;
1098 if (old_state != new_state
1099 && new_state == TCP_CONNTRACK_FIN_WAIT)
1100 ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
1102 timeouts = nf_ct_timeout_lookup(ct);
1104 timeouts = tn->timeouts;
1106 if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
1107 timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1108 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1109 else if (unlikely(index == TCP_RST_SET))
1110 timeout = timeouts[TCP_CONNTRACK_CLOSE];
1111 else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
1112 IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
1113 timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
1114 timeout = timeouts[TCP_CONNTRACK_UNACK];
1115 else if (ct->proto.tcp.last_win == 0 &&
1116 timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
1117 timeout = timeouts[TCP_CONNTRACK_RETRANS];
1119 timeout = timeouts[new_state];
1120 spin_unlock_bh(&ct->lock);
1122 if (new_state != old_state)
1123 nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
1125 if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
1126 /* If only reply is a RST, we can consider ourselves not to
1127 have an established connection: this is a fairly common
1128 problem case, so we can delete the conntrack
1129 immediately. --RR */
1131 nf_ct_kill_acct(ct, ctinfo, skb);
1134 /* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
1135 * pickup with loose=1. Avoid large ESTABLISHED timeout.
1137 if (new_state == TCP_CONNTRACK_ESTABLISHED &&
1138 timeout > timeouts[TCP_CONNTRACK_UNACK])
1139 timeout = timeouts[TCP_CONNTRACK_UNACK];
1140 } else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
1141 && (old_state == TCP_CONNTRACK_SYN_RECV
1142 || old_state == TCP_CONNTRACK_ESTABLISHED)
1143 && new_state == TCP_CONNTRACK_ESTABLISHED) {
1144 /* Set ASSURED if we see valid ack in ESTABLISHED
1145 after SYN_RECV or a valid answer for a picked up
1147 set_bit(IPS_ASSURED_BIT, &ct->status);
1148 nf_conntrack_event_cache(IPCT_ASSURED, ct);
1150 nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
1155 static bool tcp_can_early_drop(const struct nf_conn *ct)
1157 switch (ct->proto.tcp.state) {
1158 case TCP_CONNTRACK_FIN_WAIT:
1159 case TCP_CONNTRACK_LAST_ACK:
1160 case TCP_CONNTRACK_TIME_WAIT:
1161 case TCP_CONNTRACK_CLOSE:
1162 case TCP_CONNTRACK_CLOSE_WAIT:
1171 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
1173 #include <linux/netfilter/nfnetlink.h>
1174 #include <linux/netfilter/nfnetlink_conntrack.h>
1176 static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1177 struct nf_conn *ct, bool destroy)
1179 struct nlattr *nest_parms;
1180 struct nf_ct_tcp_flags tmp = {};
1182 spin_lock_bh(&ct->lock);
1183 nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP);
1185 goto nla_put_failure;
1187 if (nla_put_u8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state))
1188 goto nla_put_failure;
1193 if (nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1194 ct->proto.tcp.seen[0].td_scale) ||
1195 nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
1196 ct->proto.tcp.seen[1].td_scale))
1197 goto nla_put_failure;
1199 tmp.flags = ct->proto.tcp.seen[0].flags;
1200 if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1201 sizeof(struct nf_ct_tcp_flags), &tmp))
1202 goto nla_put_failure;
1204 tmp.flags = ct->proto.tcp.seen[1].flags;
1205 if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1206 sizeof(struct nf_ct_tcp_flags), &tmp))
1207 goto nla_put_failure;
1209 spin_unlock_bh(&ct->lock);
1210 nla_nest_end(skb, nest_parms);
1215 spin_unlock_bh(&ct->lock);
1219 static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1220 [CTA_PROTOINFO_TCP_STATE] = { .type = NLA_U8 },
1221 [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1222 [CTA_PROTOINFO_TCP_WSCALE_REPLY] = { .type = NLA_U8 },
1223 [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL] = { .len = sizeof(struct nf_ct_tcp_flags) },
1224 [CTA_PROTOINFO_TCP_FLAGS_REPLY] = { .len = sizeof(struct nf_ct_tcp_flags) },
1227 #define TCP_NLATTR_SIZE ( \
1228 NLA_ALIGN(NLA_HDRLEN + 1) + \
1229 NLA_ALIGN(NLA_HDRLEN + 1) + \
1230 NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)) + \
1231 NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)))
1233 static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1235 struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
1236 struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1239 /* updates could not contain anything about the private
1240 * protocol info, in that case skip the parsing */
1244 err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_TCP_MAX, pattr,
1245 tcp_nla_policy, NULL);
1249 if (tb[CTA_PROTOINFO_TCP_STATE] &&
1250 nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
1253 spin_lock_bh(&ct->lock);
1254 if (tb[CTA_PROTOINFO_TCP_STATE])
1255 ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
1257 if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1258 struct nf_ct_tcp_flags *attr =
1259 nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1260 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1261 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1264 if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1265 struct nf_ct_tcp_flags *attr =
1266 nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1267 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1268 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1271 if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1272 tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1273 ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1274 ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1275 ct->proto.tcp.seen[0].td_scale =
1276 nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1277 ct->proto.tcp.seen[1].td_scale =
1278 nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1280 spin_unlock_bh(&ct->lock);
1285 static unsigned int tcp_nlattr_tuple_size(void)
1287 static unsigned int size __read_mostly;
1290 size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
1296 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
1298 #include <linux/netfilter/nfnetlink.h>
1299 #include <linux/netfilter/nfnetlink_cttimeout.h>
1301 static int tcp_timeout_nlattr_to_obj(struct nlattr *tb[],
1302 struct net *net, void *data)
1304 struct nf_tcp_net *tn = nf_tcp_pernet(net);
1305 unsigned int *timeouts = data;
1309 timeouts = tn->timeouts;
1310 /* set default TCP timeouts. */
1311 for (i=0; i<TCP_CONNTRACK_TIMEOUT_MAX; i++)
1312 timeouts[i] = tn->timeouts[i];
1314 if (tb[CTA_TIMEOUT_TCP_SYN_SENT]) {
1315 timeouts[TCP_CONNTRACK_SYN_SENT] =
1316 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT]))*HZ;
1319 if (tb[CTA_TIMEOUT_TCP_SYN_RECV]) {
1320 timeouts[TCP_CONNTRACK_SYN_RECV] =
1321 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_RECV]))*HZ;
1323 if (tb[CTA_TIMEOUT_TCP_ESTABLISHED]) {
1324 timeouts[TCP_CONNTRACK_ESTABLISHED] =
1325 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_ESTABLISHED]))*HZ;
1327 if (tb[CTA_TIMEOUT_TCP_FIN_WAIT]) {
1328 timeouts[TCP_CONNTRACK_FIN_WAIT] =
1329 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_FIN_WAIT]))*HZ;
1331 if (tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]) {
1332 timeouts[TCP_CONNTRACK_CLOSE_WAIT] =
1333 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]))*HZ;
1335 if (tb[CTA_TIMEOUT_TCP_LAST_ACK]) {
1336 timeouts[TCP_CONNTRACK_LAST_ACK] =
1337 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_LAST_ACK]))*HZ;
1339 if (tb[CTA_TIMEOUT_TCP_TIME_WAIT]) {
1340 timeouts[TCP_CONNTRACK_TIME_WAIT] =
1341 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_TIME_WAIT]))*HZ;
1343 if (tb[CTA_TIMEOUT_TCP_CLOSE]) {
1344 timeouts[TCP_CONNTRACK_CLOSE] =
1345 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE]))*HZ;
1347 if (tb[CTA_TIMEOUT_TCP_SYN_SENT2]) {
1348 timeouts[TCP_CONNTRACK_SYN_SENT2] =
1349 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT2]))*HZ;
1351 if (tb[CTA_TIMEOUT_TCP_RETRANS]) {
1352 timeouts[TCP_CONNTRACK_RETRANS] =
1353 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_RETRANS]))*HZ;
1355 if (tb[CTA_TIMEOUT_TCP_UNACK]) {
1356 timeouts[TCP_CONNTRACK_UNACK] =
1357 ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_UNACK]))*HZ;
1360 timeouts[CTA_TIMEOUT_TCP_UNSPEC] = timeouts[CTA_TIMEOUT_TCP_SYN_SENT];
1365 tcp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
1367 const unsigned int *timeouts = data;
1369 if (nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT,
1370 htonl(timeouts[TCP_CONNTRACK_SYN_SENT] / HZ)) ||
1371 nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_RECV,
1372 htonl(timeouts[TCP_CONNTRACK_SYN_RECV] / HZ)) ||
1373 nla_put_be32(skb, CTA_TIMEOUT_TCP_ESTABLISHED,
1374 htonl(timeouts[TCP_CONNTRACK_ESTABLISHED] / HZ)) ||
1375 nla_put_be32(skb, CTA_TIMEOUT_TCP_FIN_WAIT,
1376 htonl(timeouts[TCP_CONNTRACK_FIN_WAIT] / HZ)) ||
1377 nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE_WAIT,
1378 htonl(timeouts[TCP_CONNTRACK_CLOSE_WAIT] / HZ)) ||
1379 nla_put_be32(skb, CTA_TIMEOUT_TCP_LAST_ACK,
1380 htonl(timeouts[TCP_CONNTRACK_LAST_ACK] / HZ)) ||
1381 nla_put_be32(skb, CTA_TIMEOUT_TCP_TIME_WAIT,
1382 htonl(timeouts[TCP_CONNTRACK_TIME_WAIT] / HZ)) ||
1383 nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE,
1384 htonl(timeouts[TCP_CONNTRACK_CLOSE] / HZ)) ||
1385 nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT2,
1386 htonl(timeouts[TCP_CONNTRACK_SYN_SENT2] / HZ)) ||
1387 nla_put_be32(skb, CTA_TIMEOUT_TCP_RETRANS,
1388 htonl(timeouts[TCP_CONNTRACK_RETRANS] / HZ)) ||
1389 nla_put_be32(skb, CTA_TIMEOUT_TCP_UNACK,
1390 htonl(timeouts[TCP_CONNTRACK_UNACK] / HZ)))
1391 goto nla_put_failure;
1398 static const struct nla_policy tcp_timeout_nla_policy[CTA_TIMEOUT_TCP_MAX+1] = {
1399 [CTA_TIMEOUT_TCP_SYN_SENT] = { .type = NLA_U32 },
1400 [CTA_TIMEOUT_TCP_SYN_RECV] = { .type = NLA_U32 },
1401 [CTA_TIMEOUT_TCP_ESTABLISHED] = { .type = NLA_U32 },
1402 [CTA_TIMEOUT_TCP_FIN_WAIT] = { .type = NLA_U32 },
1403 [CTA_TIMEOUT_TCP_CLOSE_WAIT] = { .type = NLA_U32 },
1404 [CTA_TIMEOUT_TCP_LAST_ACK] = { .type = NLA_U32 },
1405 [CTA_TIMEOUT_TCP_TIME_WAIT] = { .type = NLA_U32 },
1406 [CTA_TIMEOUT_TCP_CLOSE] = { .type = NLA_U32 },
1407 [CTA_TIMEOUT_TCP_SYN_SENT2] = { .type = NLA_U32 },
1408 [CTA_TIMEOUT_TCP_RETRANS] = { .type = NLA_U32 },
1409 [CTA_TIMEOUT_TCP_UNACK] = { .type = NLA_U32 },
1411 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
1413 void nf_conntrack_tcp_init_net(struct net *net)
1415 struct nf_tcp_net *tn = nf_tcp_pernet(net);
1418 for (i = 0; i < TCP_CONNTRACK_TIMEOUT_MAX; i++)
1419 tn->timeouts[i] = tcp_timeouts[i];
1421 /* timeouts[0] is unused, make it same as SYN_SENT so
1422 * ->timeouts[0] contains 'new' timeout, like udp or icmp.
1424 tn->timeouts[0] = tcp_timeouts[TCP_CONNTRACK_SYN_SENT];
1426 /* If it is set to zero, we disable picking up already established
1431 /* "Be conservative in what you do,
1432 * be liberal in what you accept from others."
1433 * If it's non-zero, we mark only out of window RST segments as INVALID.
1435 tn->tcp_be_liberal = 0;
1437 /* Max number of the retransmitted packets without receiving an (acceptable)
1438 * ACK from the destination. If this number is reached, a shorter timer
1441 tn->tcp_max_retrans = 3;
1444 const struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp =
1446 .l4proto = IPPROTO_TCP,
1447 #ifdef CONFIG_NF_CONNTRACK_PROCFS
1448 .print_conntrack = tcp_print_conntrack,
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,
1460 #ifdef CONFIG_NF_CONNTRACK_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,
1469 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */