1 /* (C) 1999-2001 Paul `Rusty' Russell
2 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
9 #include <linux/types.h>
10 #include <linux/timer.h>
11 #include <linux/module.h>
13 #include <linux/tcp.h>
14 #include <linux/spinlock.h>
15 #include <linux/skbuff.h>
16 #include <linux/ipv6.h>
17 #include <net/ip6_checksum.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_log.h>
29 /* Protects ct->proto.tcp */
30 static DEFINE_RWLOCK(tcp_lock);
32 /* "Be conservative in what you do,
33 be liberal in what you accept from others."
34 If it's non-zero, we mark only out of window RST segments as INVALID. */
35 static int nf_ct_tcp_be_liberal __read_mostly = 0;
37 /* If it is set to zero, we disable picking up already established
39 static int nf_ct_tcp_loose __read_mostly = 1;
41 /* Max number of the retransmitted packets without receiving an (acceptable)
42 ACK from the destination. If this number is reached, a shorter timer
44 static int nf_ct_tcp_max_retrans __read_mostly = 3;
46 /* FIXME: Examine ipfilter's timeouts and conntrack transitions more
47 closely. They're more complex. --RR */
49 static const char *const tcp_conntrack_names[] = {
63 #define MINS * 60 SECS
64 #define HOURS * 60 MINS
65 #define DAYS * 24 HOURS
67 /* RFC1122 says the R2 limit should be at least 100 seconds.
68 Linux uses 15 packets as limit, which corresponds
69 to ~13-30min depending on RTO. */
70 static unsigned int nf_ct_tcp_timeout_max_retrans __read_mostly = 5 MINS;
72 static unsigned int tcp_timeouts[TCP_CONNTRACK_MAX] __read_mostly = {
73 [TCP_CONNTRACK_SYN_SENT] = 2 MINS,
74 [TCP_CONNTRACK_SYN_RECV] = 60 SECS,
75 [TCP_CONNTRACK_ESTABLISHED] = 5 DAYS,
76 [TCP_CONNTRACK_FIN_WAIT] = 2 MINS,
77 [TCP_CONNTRACK_CLOSE_WAIT] = 60 SECS,
78 [TCP_CONNTRACK_LAST_ACK] = 30 SECS,
79 [TCP_CONNTRACK_TIME_WAIT] = 2 MINS,
80 [TCP_CONNTRACK_CLOSE] = 10 SECS,
83 #define sNO TCP_CONNTRACK_NONE
84 #define sSS TCP_CONNTRACK_SYN_SENT
85 #define sSR TCP_CONNTRACK_SYN_RECV
86 #define sES TCP_CONNTRACK_ESTABLISHED
87 #define sFW TCP_CONNTRACK_FIN_WAIT
88 #define sCW TCP_CONNTRACK_CLOSE_WAIT
89 #define sLA TCP_CONNTRACK_LAST_ACK
90 #define sTW TCP_CONNTRACK_TIME_WAIT
91 #define sCL TCP_CONNTRACK_CLOSE
92 #define sLI TCP_CONNTRACK_LISTEN
93 #define sIV TCP_CONNTRACK_MAX
94 #define sIG TCP_CONNTRACK_IGNORE
96 /* What TCP flags are set from RST/SYN/FIN/ACK. */
107 * The TCP state transition table needs a few words...
109 * We are the man in the middle. All the packets go through us
110 * but might get lost in transit to the destination.
111 * It is assumed that the destinations can't receive segments
114 * The checked segment is in window, but our windows are *not*
115 * equivalent with the ones of the sender/receiver. We always
116 * try to guess the state of the current sender.
118 * The meaning of the states are:
120 * NONE: initial state
121 * SYN_SENT: SYN-only packet seen
122 * SYN_RECV: SYN-ACK packet seen
123 * ESTABLISHED: ACK packet seen
124 * FIN_WAIT: FIN packet seen
125 * CLOSE_WAIT: ACK seen (after FIN)
126 * LAST_ACK: FIN seen (after FIN)
127 * TIME_WAIT: last ACK seen
128 * CLOSE: closed connection (RST)
130 * LISTEN state is not used.
132 * Packets marked as IGNORED (sIG):
133 * if they may be either invalid or valid
134 * and the receiver may send back a connection
135 * closing RST or a SYN/ACK.
137 * Packets marked as INVALID (sIV):
138 * if they are invalid
139 * or we do not support the request (simultaneous open)
141 static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
144 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */
145 /*syn*/ { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sIV },
147 * sNO -> sSS Initialize a new connection
148 * sSS -> sSS Retransmitted SYN
149 * sSR -> sIG Late retransmitted SYN?
150 * sES -> sIG Error: SYNs in window outside the SYN_SENT state
151 * are errors. Receiver will reply with RST
152 * and close the connection.
153 * Or we are not in sync and hold a dead connection.
157 * sTW -> sSS Reopened connection (RFC 1122).
160 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */
161 /*synack*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV },
163 * A SYN/ACK from the client is always invalid:
164 * - either it tries to set up a simultaneous open, which is
166 * - or the firewall has just been inserted between the two hosts
167 * during the session set-up. The SYN will be retransmitted
168 * by the true client (or it'll time out).
170 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */
171 /*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
173 * sNO -> sIV Too late and no reason to do anything...
174 * sSS -> sIV Client migth not send FIN in this state:
175 * we enforce waiting for a SYN/ACK reply first.
176 * sSR -> sFW Close started.
178 * sFW -> sLA FIN seen in both directions, waiting for
180 * Migth be a retransmitted FIN as well...
182 * sLA -> sLA Retransmitted FIN. Remain in the same state.
186 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */
187 /*ack*/ { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV },
189 * sNO -> sES Assumed.
190 * sSS -> sIV ACK is invalid: we haven't seen a SYN/ACK yet.
191 * sSR -> sES Established state is reached.
193 * sFW -> sCW Normal close request answered by ACK.
195 * sLA -> sTW Last ACK detected.
196 * sTW -> sTW Retransmitted last ACK. Remain in the same state.
199 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */
200 /*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sIV },
201 /*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
205 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */
206 /*syn*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV },
208 * sNO -> sIV Never reached.
209 * sSS -> sIV Simultaneous open, not supported
210 * sSR -> sIV Simultaneous open, not supported.
211 * sES -> sIV Server may not initiate a connection.
215 * sTW -> sIV Reopened connection, but server may not do it.
218 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */
219 /*synack*/ { sIV, sSR, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIV },
221 * sSS -> sSR Standard open.
222 * sSR -> sSR Retransmitted SYN/ACK.
223 * sES -> sIG Late retransmitted SYN/ACK?
224 * sFW -> sIG Might be SYN/ACK answering ignored SYN
230 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */
231 /*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
233 * sSS -> sIV Server might not send FIN in this state.
234 * sSR -> sFW Close started.
236 * sFW -> sLA FIN seen in both directions.
238 * sLA -> sLA Retransmitted FIN.
242 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */
243 /*ack*/ { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIV },
245 * sSS -> sIG Might be a half-open connection.
246 * sSR -> sSR Might answer late resent SYN.
248 * sFW -> sCW Normal close request answered by ACK.
250 * sLA -> sTW Last ACK detected.
251 * sTW -> sTW Retransmitted last ACK.
254 /* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */
255 /*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sIV },
256 /*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
260 static bool tcp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
261 struct nf_conntrack_tuple *tuple)
263 const struct tcphdr *hp;
266 /* Actually only need first 8 bytes. */
267 hp = skb_header_pointer(skb, dataoff, 8, &_hdr);
271 tuple->src.u.tcp.port = hp->source;
272 tuple->dst.u.tcp.port = hp->dest;
277 static bool tcp_invert_tuple(struct nf_conntrack_tuple *tuple,
278 const struct nf_conntrack_tuple *orig)
280 tuple->src.u.tcp.port = orig->dst.u.tcp.port;
281 tuple->dst.u.tcp.port = orig->src.u.tcp.port;
285 /* Print out the per-protocol part of the tuple. */
286 static int tcp_print_tuple(struct seq_file *s,
287 const struct nf_conntrack_tuple *tuple)
289 return seq_printf(s, "sport=%hu dport=%hu ",
290 ntohs(tuple->src.u.tcp.port),
291 ntohs(tuple->dst.u.tcp.port));
294 /* Print out the private part of the conntrack. */
295 static int tcp_print_conntrack(struct seq_file *s, const struct nf_conn *ct)
297 enum tcp_conntrack state;
299 read_lock_bh(&tcp_lock);
300 state = ct->proto.tcp.state;
301 read_unlock_bh(&tcp_lock);
303 return seq_printf(s, "%s ", tcp_conntrack_names[state]);
306 static unsigned int get_conntrack_index(const struct tcphdr *tcph)
308 if (tcph->rst) return TCP_RST_SET;
309 else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET);
310 else if (tcph->fin) return TCP_FIN_SET;
311 else if (tcph->ack) return TCP_ACK_SET;
312 else return TCP_NONE_SET;
315 /* TCP connection tracking based on 'Real Stateful TCP Packet Filtering
316 in IP Filter' by Guido van Rooij.
318 http://www.nluug.nl/events/sane2000/papers.html
319 http://www.iae.nl/users/guido/papers/tcp_filtering.ps.gz
321 The boundaries and the conditions are changed according to RFC793:
322 the packet must intersect the window (i.e. segments may be
323 after the right or before the left edge) and thus receivers may ACK
324 segments after the right edge of the window.
326 td_maxend = max(sack + max(win,1)) seen in reply packets
327 td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets
328 td_maxwin += seq + len - sender.td_maxend
329 if seq + len > sender.td_maxend
330 td_end = max(seq + len) seen in sent packets
332 I. Upper bound for valid data: seq <= sender.td_maxend
333 II. Lower bound for valid data: seq + len >= sender.td_end - receiver.td_maxwin
334 III. Upper bound for valid (s)ack: sack <= receiver.td_end
335 IV. Lower bound for valid (s)ack: sack >= receiver.td_end - MAXACKWINDOW
337 where sack is the highest right edge of sack block found in the packet
338 or ack in the case of packet without SACK option.
340 The upper bound limit for a valid (s)ack is not ignored -
341 we doesn't have to deal with fragments.
344 static inline __u32 segment_seq_plus_len(__u32 seq,
346 unsigned int dataoff,
347 const struct tcphdr *tcph)
349 /* XXX Should I use payload length field in IP/IPv6 header ?
351 return (seq + len - dataoff - tcph->doff*4
352 + (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0));
355 /* Fixme: what about big packets? */
356 #define MAXACKWINCONST 66000
357 #define MAXACKWINDOW(sender) \
358 ((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin \
362 * Simplified tcp_parse_options routine from tcp_input.c
364 static void tcp_options(const struct sk_buff *skb,
365 unsigned int dataoff,
366 const struct tcphdr *tcph,
367 struct ip_ct_tcp_state *state)
369 unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
370 const unsigned char *ptr;
371 int length = (tcph->doff*4) - sizeof(struct tcphdr);
376 ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
390 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
395 if (opsize < 2) /* "silly options" */
398 break; /* don't parse partial options */
400 if (opcode == TCPOPT_SACK_PERM
401 && opsize == TCPOLEN_SACK_PERM)
402 state->flags |= IP_CT_TCP_FLAG_SACK_PERM;
403 else if (opcode == TCPOPT_WINDOW
404 && opsize == TCPOLEN_WINDOW) {
405 state->td_scale = *(u_int8_t *)ptr;
407 if (state->td_scale > 14) {
409 state->td_scale = 14;
412 IP_CT_TCP_FLAG_WINDOW_SCALE;
420 static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
421 const struct tcphdr *tcph, __u32 *sack)
423 unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
424 const unsigned char *ptr;
425 int length = (tcph->doff*4) - sizeof(struct tcphdr);
431 ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
435 /* Fast path for timestamp-only option */
436 if (length == TCPOLEN_TSTAMP_ALIGNED*4
437 && *(__be32 *)ptr == htonl((TCPOPT_NOP << 24)
439 | (TCPOPT_TIMESTAMP << 8)
440 | TCPOLEN_TIMESTAMP))
450 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
455 if (opsize < 2) /* "silly options" */
458 break; /* don't parse partial options */
460 if (opcode == TCPOPT_SACK
461 && opsize >= (TCPOLEN_SACK_BASE
462 + TCPOLEN_SACK_PERBLOCK)
463 && !((opsize - TCPOLEN_SACK_BASE)
464 % TCPOLEN_SACK_PERBLOCK)) {
466 i < (opsize - TCPOLEN_SACK_BASE);
467 i += TCPOLEN_SACK_PERBLOCK) {
468 tmp = ntohl(*((__be32 *)(ptr+i)+1));
470 if (after(tmp, *sack))
481 static bool tcp_in_window(const struct nf_conn *ct,
482 struct ip_ct_tcp *state,
483 enum ip_conntrack_dir dir,
485 const struct sk_buff *skb,
486 unsigned int dataoff,
487 const struct tcphdr *tcph,
490 struct ip_ct_tcp_state *sender = &state->seen[dir];
491 struct ip_ct_tcp_state *receiver = &state->seen[!dir];
492 const struct nf_conntrack_tuple *tuple = &ct->tuplehash[dir].tuple;
493 __u32 seq, ack, sack, end, win, swin;
497 * Get the required data from the packet.
499 seq = ntohl(tcph->seq);
500 ack = sack = ntohl(tcph->ack_seq);
501 win = ntohs(tcph->window);
502 end = segment_seq_plus_len(seq, skb->len, dataoff, tcph);
504 if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
505 tcp_sack(skb, dataoff, tcph, &sack);
507 pr_debug("tcp_in_window: START\n");
508 pr_debug("tcp_in_window: ");
509 nf_ct_dump_tuple(tuple);
510 pr_debug("seq=%u ack=%u sack=%u win=%u end=%u\n",
511 seq, ack, sack, win, end);
512 pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
513 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
514 sender->td_end, sender->td_maxend, sender->td_maxwin,
516 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
519 if (sender->td_end == 0) {
521 * Initialize sender data.
523 if (tcph->syn && tcph->ack) {
525 * Outgoing SYN-ACK in reply to a SYN.
528 sender->td_maxend = end;
529 sender->td_maxwin = (win == 0 ? 1 : win);
531 tcp_options(skb, dataoff, tcph, sender);
534 * Both sides must send the Window Scale option
535 * to enable window scaling in either direction.
537 if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE
538 && receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE))
540 receiver->td_scale = 0;
543 * We are in the middle of a connection,
544 * its history is lost for us.
545 * Let's try to use the data from the packet.
547 sender->td_end = end;
548 sender->td_maxwin = (win == 0 ? 1 : win);
549 sender->td_maxend = end + sender->td_maxwin;
551 } else if (((state->state == TCP_CONNTRACK_SYN_SENT
552 && dir == IP_CT_DIR_ORIGINAL)
553 || (state->state == TCP_CONNTRACK_SYN_RECV
554 && dir == IP_CT_DIR_REPLY))
555 && after(end, sender->td_end)) {
557 * RFC 793: "if a TCP is reinitialized ... then it need
558 * not wait at all; it must only be sure to use sequence
559 * numbers larger than those recently used."
562 sender->td_maxend = end;
563 sender->td_maxwin = (win == 0 ? 1 : win);
565 tcp_options(skb, dataoff, tcph, sender);
570 * If there is no ACK, just pretend it was set and OK.
572 ack = sack = receiver->td_end;
573 } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
574 (TCP_FLAG_ACK|TCP_FLAG_RST))
577 * Broken TCP stacks, that set ACK in RST packets as well
578 * with zero ack value.
580 ack = sack = receiver->td_end;
585 || (seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)))
587 * Packets contains no data: we assume it is valid
588 * and check the ack value only.
589 * However RST segments are always validated by their
590 * SEQ number, except when seq == 0 (reset sent answering
593 seq = end = sender->td_end;
595 pr_debug("tcp_in_window: ");
596 nf_ct_dump_tuple(tuple);
597 pr_debug("seq=%u ack=%u sack =%u win=%u end=%u\n",
598 seq, ack, sack, win, end);
599 pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
600 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
601 sender->td_end, sender->td_maxend, sender->td_maxwin,
603 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
606 pr_debug("tcp_in_window: I=%i II=%i III=%i IV=%i\n",
607 before(seq, sender->td_maxend + 1),
608 after(end, sender->td_end - receiver->td_maxwin - 1),
609 before(sack, receiver->td_end + 1),
610 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1));
612 if (before(seq, sender->td_maxend + 1) &&
613 after(end, sender->td_end - receiver->td_maxwin - 1) &&
614 before(sack, receiver->td_end + 1) &&
615 after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1)) {
617 * Take into account window scaling (RFC 1323).
620 win <<= sender->td_scale;
623 * Update sender data.
625 swin = win + (sack - ack);
626 if (sender->td_maxwin < swin)
627 sender->td_maxwin = swin;
628 if (after(end, sender->td_end))
629 sender->td_end = end;
631 * Update receiver data.
633 if (after(end, sender->td_maxend))
634 receiver->td_maxwin += end - sender->td_maxend;
635 if (after(sack + win, receiver->td_maxend - 1)) {
636 receiver->td_maxend = sack + win;
638 receiver->td_maxend++;
642 * Check retransmissions.
644 if (index == TCP_ACK_SET) {
645 if (state->last_dir == dir
646 && state->last_seq == seq
647 && state->last_ack == ack
648 && state->last_end == end
649 && state->last_win == win)
652 state->last_dir = dir;
653 state->last_seq = seq;
654 state->last_ack = ack;
655 state->last_end = end;
656 state->last_win = win;
663 if (sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL ||
664 nf_ct_tcp_be_liberal)
666 if (!res && LOG_INVALID(IPPROTO_TCP))
667 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
669 before(seq, sender->td_maxend + 1) ?
670 after(end, sender->td_end - receiver->td_maxwin - 1) ?
671 before(sack, receiver->td_end + 1) ?
672 after(ack, receiver->td_end - MAXACKWINDOW(sender)) ? "BUG"
673 : "ACK is under the lower bound (possible overly delayed ACK)"
674 : "ACK is over the upper bound (ACKed data not seen yet)"
675 : "SEQ is under the lower bound (already ACKed data retransmitted)"
676 : "SEQ is over the upper bound (over the window of the receiver)");
679 pr_debug("tcp_in_window: res=%u sender end=%u maxend=%u maxwin=%u "
680 "receiver end=%u maxend=%u maxwin=%u\n",
681 res, sender->td_end, sender->td_maxend, sender->td_maxwin,
682 receiver->td_end, receiver->td_maxend, receiver->td_maxwin);
687 #ifdef CONFIG_NF_NAT_NEEDED
688 /* Update sender->td_end after NAT successfully mangled the packet */
689 /* Caller must linearize skb at tcp header. */
690 void nf_conntrack_tcp_update(const struct sk_buff *skb,
691 unsigned int dataoff,
695 const struct tcphdr *tcph = (const void *)skb->data + dataoff;
696 const struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[dir];
697 const struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[!dir];
700 end = segment_seq_plus_len(ntohl(tcph->seq), skb->len, dataoff, tcph);
702 write_lock_bh(&tcp_lock);
704 * We have to worry for the ack in the reply packet only...
706 if (after(end, ct->proto.tcp.seen[dir].td_end))
707 ct->proto.tcp.seen[dir].td_end = end;
708 ct->proto.tcp.last_end = end;
709 write_unlock_bh(&tcp_lock);
710 pr_debug("tcp_update: sender end=%u maxend=%u maxwin=%u scale=%i "
711 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
712 sender->td_end, sender->td_maxend, sender->td_maxwin,
714 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
717 EXPORT_SYMBOL_GPL(nf_conntrack_tcp_update);
729 /* table of valid flag combinations - PUSH, ECE and CWR are always valid */
730 static const u8 tcp_valid_flags[(TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG) + 1] =
738 [TH_FIN|TH_ACK|TH_URG] = 1,
743 /* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c. */
744 static int tcp_error(struct sk_buff *skb,
745 unsigned int dataoff,
746 enum ip_conntrack_info *ctinfo,
748 unsigned int hooknum)
750 const struct tcphdr *th;
752 unsigned int tcplen = skb->len - dataoff;
755 /* Smaller that minimal TCP header? */
756 th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
758 if (LOG_INVALID(IPPROTO_TCP))
759 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
760 "nf_ct_tcp: short packet ");
764 /* Not whole TCP header or malformed packet */
765 if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
766 if (LOG_INVALID(IPPROTO_TCP))
767 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
768 "nf_ct_tcp: truncated/malformed packet ");
772 /* Checksum invalid? Ignore.
773 * We skip checking packets on the outgoing path
774 * because the checksum is assumed to be correct.
776 /* FIXME: Source route IP option packets --RR */
777 if (nf_conntrack_checksum && hooknum == NF_INET_PRE_ROUTING &&
778 nf_checksum(skb, hooknum, dataoff, IPPROTO_TCP, pf)) {
779 if (LOG_INVALID(IPPROTO_TCP))
780 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
781 "nf_ct_tcp: bad TCP checksum ");
785 /* Check TCP flags. */
786 tcpflags = (((u_int8_t *)th)[13] & ~(TH_ECE|TH_CWR|TH_PUSH));
787 if (!tcp_valid_flags[tcpflags]) {
788 if (LOG_INVALID(IPPROTO_TCP))
789 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
790 "nf_ct_tcp: invalid TCP flag combination ");
797 /* Returns verdict for packet, or -1 for invalid. */
798 static int tcp_packet(struct nf_conn *ct,
799 const struct sk_buff *skb,
800 unsigned int dataoff,
801 enum ip_conntrack_info ctinfo,
803 unsigned int hooknum)
805 struct nf_conntrack_tuple *tuple;
806 enum tcp_conntrack new_state, old_state;
807 enum ip_conntrack_dir dir;
808 const struct tcphdr *th;
810 unsigned long timeout;
813 th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
816 write_lock_bh(&tcp_lock);
817 old_state = ct->proto.tcp.state;
818 dir = CTINFO2DIR(ctinfo);
819 index = get_conntrack_index(th);
820 new_state = tcp_conntracks[dir][index][old_state];
821 tuple = &ct->tuplehash[dir].tuple;
824 case TCP_CONNTRACK_SYN_SENT:
825 if (old_state < TCP_CONNTRACK_TIME_WAIT)
827 /* RFC 1122: "When a connection is closed actively,
828 * it MUST linger in TIME-WAIT state for a time 2xMSL
829 * (Maximum Segment Lifetime). However, it MAY accept
830 * a new SYN from the remote TCP to reopen the connection
831 * directly from TIME-WAIT state, if..."
832 * We ignore the conditions because we are in the
833 * TIME-WAIT state anyway.
835 * Handle aborted connections: we and the server
836 * think there is an existing connection but the client
837 * aborts it and starts a new one.
839 if (((ct->proto.tcp.seen[dir].flags
840 | ct->proto.tcp.seen[!dir].flags)
841 & IP_CT_TCP_FLAG_CLOSE_INIT)
842 || (ct->proto.tcp.last_dir == dir
843 && ct->proto.tcp.last_index == TCP_RST_SET)) {
844 /* Attempt to reopen a closed/aborted connection.
845 * Delete this connection and look up again. */
846 write_unlock_bh(&tcp_lock);
851 case TCP_CONNTRACK_IGNORE:
854 * Our connection entry may be out of sync, so ignore
855 * packets which may signal the real connection between
856 * the client and the server.
859 * b) SYN/ACK in REPLY
860 * c) ACK in reply direction after initial SYN in original.
862 * If the ignored packet is invalid, the receiver will send
863 * a RST we'll catch below.
865 if (index == TCP_SYNACK_SET
866 && ct->proto.tcp.last_index == TCP_SYN_SET
867 && ct->proto.tcp.last_dir != dir
868 && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
869 /* b) This SYN/ACK acknowledges a SYN that we earlier
870 * ignored as invalid. This means that the client and
871 * the server are both in sync, while the firewall is
872 * not. We kill this session and block the SYN/ACK so
873 * that the client cannot but retransmit its SYN and
874 * thus initiate a clean new session.
876 write_unlock_bh(&tcp_lock);
877 if (LOG_INVALID(IPPROTO_TCP))
878 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
879 "nf_ct_tcp: killing out of sync session ");
883 ct->proto.tcp.last_index = index;
884 ct->proto.tcp.last_dir = dir;
885 ct->proto.tcp.last_seq = ntohl(th->seq);
886 ct->proto.tcp.last_end =
887 segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
889 write_unlock_bh(&tcp_lock);
890 if (LOG_INVALID(IPPROTO_TCP))
891 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
892 "nf_ct_tcp: invalid packet ignored ");
894 case TCP_CONNTRACK_MAX:
896 pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
897 dir, get_conntrack_index(th), old_state);
898 write_unlock_bh(&tcp_lock);
899 if (LOG_INVALID(IPPROTO_TCP))
900 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
901 "nf_ct_tcp: invalid state ");
903 case TCP_CONNTRACK_CLOSE:
904 if (index == TCP_RST_SET
905 && ((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
906 && ct->proto.tcp.last_index == TCP_SYN_SET)
907 || (!test_bit(IPS_ASSURED_BIT, &ct->status)
908 && ct->proto.tcp.last_index == TCP_ACK_SET))
909 && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
910 /* RST sent to invalid SYN or ACK we had let through
911 * at a) and c) above:
913 * a) SYN was in window then
914 * c) we hold a half-open connection.
916 * Delete our connection entry.
917 * We skip window checking, because packet might ACK
918 * segments we ignored. */
921 /* Just fall through */
923 /* Keep compilers happy. */
927 if (!tcp_in_window(ct, &ct->proto.tcp, dir, index,
928 skb, dataoff, th, pf)) {
929 write_unlock_bh(&tcp_lock);
933 /* From now on we have got in-window packets */
934 ct->proto.tcp.last_index = index;
935 ct->proto.tcp.last_dir = dir;
937 pr_debug("tcp_conntracks: ");
938 nf_ct_dump_tuple(tuple);
939 pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
940 (th->syn ? 1 : 0), (th->ack ? 1 : 0),
941 (th->fin ? 1 : 0), (th->rst ? 1 : 0),
942 old_state, new_state);
944 ct->proto.tcp.state = new_state;
945 if (old_state != new_state
946 && new_state == TCP_CONNTRACK_FIN_WAIT)
947 ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
948 timeout = ct->proto.tcp.retrans >= nf_ct_tcp_max_retrans
949 && tcp_timeouts[new_state] > nf_ct_tcp_timeout_max_retrans
950 ? nf_ct_tcp_timeout_max_retrans : tcp_timeouts[new_state];
951 write_unlock_bh(&tcp_lock);
953 nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
954 if (new_state != old_state)
955 nf_conntrack_event_cache(IPCT_PROTOINFO, skb);
957 if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
958 /* If only reply is a RST, we can consider ourselves not to
959 have an established connection: this is a fairly common
960 problem case, so we can delete the conntrack
963 nf_ct_kill_acct(ct, ctinfo, skb);
966 } else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
967 && (old_state == TCP_CONNTRACK_SYN_RECV
968 || old_state == TCP_CONNTRACK_ESTABLISHED)
969 && new_state == TCP_CONNTRACK_ESTABLISHED) {
970 /* Set ASSURED if we see see valid ack in ESTABLISHED
971 after SYN_RECV or a valid answer for a picked up
973 set_bit(IPS_ASSURED_BIT, &ct->status);
974 nf_conntrack_event_cache(IPCT_STATUS, skb);
976 nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
981 /* Called when a new connection for this protocol found. */
982 static bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
983 unsigned int dataoff)
985 enum tcp_conntrack new_state;
986 const struct tcphdr *th;
988 const struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[0];
989 const struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[1];
991 th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
994 /* Don't need lock here: this conntrack not in circulation yet */
996 = tcp_conntracks[0][get_conntrack_index(th)]
997 [TCP_CONNTRACK_NONE];
999 /* Invalid: delete conntrack */
1000 if (new_state >= TCP_CONNTRACK_MAX) {
1001 pr_debug("nf_ct_tcp: invalid new deleting.\n");
1005 if (new_state == TCP_CONNTRACK_SYN_SENT) {
1007 ct->proto.tcp.seen[0].td_end =
1008 segment_seq_plus_len(ntohl(th->seq), skb->len,
1010 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
1011 if (ct->proto.tcp.seen[0].td_maxwin == 0)
1012 ct->proto.tcp.seen[0].td_maxwin = 1;
1013 ct->proto.tcp.seen[0].td_maxend =
1014 ct->proto.tcp.seen[0].td_end;
1016 tcp_options(skb, dataoff, th, &ct->proto.tcp.seen[0]);
1017 ct->proto.tcp.seen[1].flags = 0;
1018 } else if (nf_ct_tcp_loose == 0) {
1019 /* Don't try to pick up connections. */
1023 * We are in the middle of a connection,
1024 * its history is lost for us.
1025 * Let's try to use the data from the packet.
1027 ct->proto.tcp.seen[0].td_end =
1028 segment_seq_plus_len(ntohl(th->seq), skb->len,
1030 ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
1031 if (ct->proto.tcp.seen[0].td_maxwin == 0)
1032 ct->proto.tcp.seen[0].td_maxwin = 1;
1033 ct->proto.tcp.seen[0].td_maxend =
1034 ct->proto.tcp.seen[0].td_end +
1035 ct->proto.tcp.seen[0].td_maxwin;
1036 ct->proto.tcp.seen[0].td_scale = 0;
1038 /* We assume SACK and liberal window checking to handle
1040 ct->proto.tcp.seen[0].flags =
1041 ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
1042 IP_CT_TCP_FLAG_BE_LIBERAL;
1045 ct->proto.tcp.seen[1].td_end = 0;
1046 ct->proto.tcp.seen[1].td_maxend = 0;
1047 ct->proto.tcp.seen[1].td_maxwin = 1;
1048 ct->proto.tcp.seen[1].td_scale = 0;
1050 /* tcp_packet will set them */
1051 ct->proto.tcp.state = TCP_CONNTRACK_NONE;
1052 ct->proto.tcp.last_index = TCP_NONE_SET;
1054 pr_debug("tcp_new: sender end=%u maxend=%u maxwin=%u scale=%i "
1055 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
1056 sender->td_end, sender->td_maxend, sender->td_maxwin,
1058 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
1059 receiver->td_scale);
1063 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
1065 #include <linux/netfilter/nfnetlink.h>
1066 #include <linux/netfilter/nfnetlink_conntrack.h>
1068 static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
1069 const struct nf_conn *ct)
1071 struct nlattr *nest_parms;
1072 struct nf_ct_tcp_flags tmp = {};
1074 read_lock_bh(&tcp_lock);
1075 nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP | NLA_F_NESTED);
1077 goto nla_put_failure;
1079 NLA_PUT_U8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state);
1081 NLA_PUT_U8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
1082 ct->proto.tcp.seen[0].td_scale);
1084 NLA_PUT_U8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
1085 ct->proto.tcp.seen[1].td_scale);
1087 tmp.flags = ct->proto.tcp.seen[0].flags;
1088 NLA_PUT(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
1089 sizeof(struct nf_ct_tcp_flags), &tmp);
1091 tmp.flags = ct->proto.tcp.seen[1].flags;
1092 NLA_PUT(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
1093 sizeof(struct nf_ct_tcp_flags), &tmp);
1094 read_unlock_bh(&tcp_lock);
1096 nla_nest_end(skb, nest_parms);
1101 read_unlock_bh(&tcp_lock);
1105 static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
1106 [CTA_PROTOINFO_TCP_STATE] = { .type = NLA_U8 },
1107 [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
1108 [CTA_PROTOINFO_TCP_WSCALE_REPLY] = { .type = NLA_U8 },
1109 [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL] = { .len = sizeof(struct nf_ct_tcp_flags) },
1110 [CTA_PROTOINFO_TCP_FLAGS_REPLY] = { .len = sizeof(struct nf_ct_tcp_flags) },
1113 static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
1115 struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
1116 struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
1119 /* updates could not contain anything about the private
1120 * protocol info, in that case skip the parsing */
1124 err = nla_parse_nested(tb, CTA_PROTOINFO_TCP_MAX, pattr, tcp_nla_policy);
1128 if (tb[CTA_PROTOINFO_TCP_STATE] &&
1129 nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
1132 write_lock_bh(&tcp_lock);
1133 if (tb[CTA_PROTOINFO_TCP_STATE])
1134 ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
1136 if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
1137 struct nf_ct_tcp_flags *attr =
1138 nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
1139 ct->proto.tcp.seen[0].flags &= ~attr->mask;
1140 ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
1143 if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
1144 struct nf_ct_tcp_flags *attr =
1145 nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
1146 ct->proto.tcp.seen[1].flags &= ~attr->mask;
1147 ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
1150 if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
1151 tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
1152 ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
1153 ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
1154 ct->proto.tcp.seen[0].td_scale =
1155 nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
1156 ct->proto.tcp.seen[1].td_scale =
1157 nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
1159 write_unlock_bh(&tcp_lock);
1165 #ifdef CONFIG_SYSCTL
1166 static unsigned int tcp_sysctl_table_users;
1167 static struct ctl_table_header *tcp_sysctl_header;
1168 static struct ctl_table tcp_sysctl_table[] = {
1170 .procname = "nf_conntrack_tcp_timeout_syn_sent",
1171 .data = &tcp_timeouts[TCP_CONNTRACK_SYN_SENT],
1172 .maxlen = sizeof(unsigned int),
1174 .proc_handler = &proc_dointvec_jiffies,
1177 .procname = "nf_conntrack_tcp_timeout_syn_recv",
1178 .data = &tcp_timeouts[TCP_CONNTRACK_SYN_RECV],
1179 .maxlen = sizeof(unsigned int),
1181 .proc_handler = &proc_dointvec_jiffies,
1184 .procname = "nf_conntrack_tcp_timeout_established",
1185 .data = &tcp_timeouts[TCP_CONNTRACK_ESTABLISHED],
1186 .maxlen = sizeof(unsigned int),
1188 .proc_handler = &proc_dointvec_jiffies,
1191 .procname = "nf_conntrack_tcp_timeout_fin_wait",
1192 .data = &tcp_timeouts[TCP_CONNTRACK_FIN_WAIT],
1193 .maxlen = sizeof(unsigned int),
1195 .proc_handler = &proc_dointvec_jiffies,
1198 .procname = "nf_conntrack_tcp_timeout_close_wait",
1199 .data = &tcp_timeouts[TCP_CONNTRACK_CLOSE_WAIT],
1200 .maxlen = sizeof(unsigned int),
1202 .proc_handler = &proc_dointvec_jiffies,
1205 .procname = "nf_conntrack_tcp_timeout_last_ack",
1206 .data = &tcp_timeouts[TCP_CONNTRACK_LAST_ACK],
1207 .maxlen = sizeof(unsigned int),
1209 .proc_handler = &proc_dointvec_jiffies,
1212 .procname = "nf_conntrack_tcp_timeout_time_wait",
1213 .data = &tcp_timeouts[TCP_CONNTRACK_TIME_WAIT],
1214 .maxlen = sizeof(unsigned int),
1216 .proc_handler = &proc_dointvec_jiffies,
1219 .procname = "nf_conntrack_tcp_timeout_close",
1220 .data = &tcp_timeouts[TCP_CONNTRACK_CLOSE],
1221 .maxlen = sizeof(unsigned int),
1223 .proc_handler = &proc_dointvec_jiffies,
1226 .procname = "nf_conntrack_tcp_timeout_max_retrans",
1227 .data = &nf_ct_tcp_timeout_max_retrans,
1228 .maxlen = sizeof(unsigned int),
1230 .proc_handler = &proc_dointvec_jiffies,
1233 .ctl_name = NET_NF_CONNTRACK_TCP_LOOSE,
1234 .procname = "nf_conntrack_tcp_loose",
1235 .data = &nf_ct_tcp_loose,
1236 .maxlen = sizeof(unsigned int),
1238 .proc_handler = &proc_dointvec,
1241 .ctl_name = NET_NF_CONNTRACK_TCP_BE_LIBERAL,
1242 .procname = "nf_conntrack_tcp_be_liberal",
1243 .data = &nf_ct_tcp_be_liberal,
1244 .maxlen = sizeof(unsigned int),
1246 .proc_handler = &proc_dointvec,
1249 .ctl_name = NET_NF_CONNTRACK_TCP_MAX_RETRANS,
1250 .procname = "nf_conntrack_tcp_max_retrans",
1251 .data = &nf_ct_tcp_max_retrans,
1252 .maxlen = sizeof(unsigned int),
1254 .proc_handler = &proc_dointvec,
1261 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
1262 static struct ctl_table tcp_compat_sysctl_table[] = {
1264 .procname = "ip_conntrack_tcp_timeout_syn_sent",
1265 .data = &tcp_timeouts[TCP_CONNTRACK_SYN_SENT],
1266 .maxlen = sizeof(unsigned int),
1268 .proc_handler = &proc_dointvec_jiffies,
1271 .procname = "ip_conntrack_tcp_timeout_syn_recv",
1272 .data = &tcp_timeouts[TCP_CONNTRACK_SYN_RECV],
1273 .maxlen = sizeof(unsigned int),
1275 .proc_handler = &proc_dointvec_jiffies,
1278 .procname = "ip_conntrack_tcp_timeout_established",
1279 .data = &tcp_timeouts[TCP_CONNTRACK_ESTABLISHED],
1280 .maxlen = sizeof(unsigned int),
1282 .proc_handler = &proc_dointvec_jiffies,
1285 .procname = "ip_conntrack_tcp_timeout_fin_wait",
1286 .data = &tcp_timeouts[TCP_CONNTRACK_FIN_WAIT],
1287 .maxlen = sizeof(unsigned int),
1289 .proc_handler = &proc_dointvec_jiffies,
1292 .procname = "ip_conntrack_tcp_timeout_close_wait",
1293 .data = &tcp_timeouts[TCP_CONNTRACK_CLOSE_WAIT],
1294 .maxlen = sizeof(unsigned int),
1296 .proc_handler = &proc_dointvec_jiffies,
1299 .procname = "ip_conntrack_tcp_timeout_last_ack",
1300 .data = &tcp_timeouts[TCP_CONNTRACK_LAST_ACK],
1301 .maxlen = sizeof(unsigned int),
1303 .proc_handler = &proc_dointvec_jiffies,
1306 .procname = "ip_conntrack_tcp_timeout_time_wait",
1307 .data = &tcp_timeouts[TCP_CONNTRACK_TIME_WAIT],
1308 .maxlen = sizeof(unsigned int),
1310 .proc_handler = &proc_dointvec_jiffies,
1313 .procname = "ip_conntrack_tcp_timeout_close",
1314 .data = &tcp_timeouts[TCP_CONNTRACK_CLOSE],
1315 .maxlen = sizeof(unsigned int),
1317 .proc_handler = &proc_dointvec_jiffies,
1320 .procname = "ip_conntrack_tcp_timeout_max_retrans",
1321 .data = &nf_ct_tcp_timeout_max_retrans,
1322 .maxlen = sizeof(unsigned int),
1324 .proc_handler = &proc_dointvec_jiffies,
1327 .ctl_name = NET_IPV4_NF_CONNTRACK_TCP_LOOSE,
1328 .procname = "ip_conntrack_tcp_loose",
1329 .data = &nf_ct_tcp_loose,
1330 .maxlen = sizeof(unsigned int),
1332 .proc_handler = &proc_dointvec,
1335 .ctl_name = NET_IPV4_NF_CONNTRACK_TCP_BE_LIBERAL,
1336 .procname = "ip_conntrack_tcp_be_liberal",
1337 .data = &nf_ct_tcp_be_liberal,
1338 .maxlen = sizeof(unsigned int),
1340 .proc_handler = &proc_dointvec,
1343 .ctl_name = NET_IPV4_NF_CONNTRACK_TCP_MAX_RETRANS,
1344 .procname = "ip_conntrack_tcp_max_retrans",
1345 .data = &nf_ct_tcp_max_retrans,
1346 .maxlen = sizeof(unsigned int),
1348 .proc_handler = &proc_dointvec,
1354 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
1355 #endif /* CONFIG_SYSCTL */
1357 struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp4 __read_mostly =
1360 .l4proto = IPPROTO_TCP,
1362 .pkt_to_tuple = tcp_pkt_to_tuple,
1363 .invert_tuple = tcp_invert_tuple,
1364 .print_tuple = tcp_print_tuple,
1365 .print_conntrack = tcp_print_conntrack,
1366 .packet = tcp_packet,
1369 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
1370 .to_nlattr = tcp_to_nlattr,
1371 .from_nlattr = nlattr_to_tcp,
1372 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
1373 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
1374 .nla_policy = nf_ct_port_nla_policy,
1376 #ifdef CONFIG_SYSCTL
1377 .ctl_table_users = &tcp_sysctl_table_users,
1378 .ctl_table_header = &tcp_sysctl_header,
1379 .ctl_table = tcp_sysctl_table,
1380 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
1381 .ctl_compat_table = tcp_compat_sysctl_table,
1385 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_tcp4);
1387 struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp6 __read_mostly =
1389 .l3proto = PF_INET6,
1390 .l4proto = IPPROTO_TCP,
1392 .pkt_to_tuple = tcp_pkt_to_tuple,
1393 .invert_tuple = tcp_invert_tuple,
1394 .print_tuple = tcp_print_tuple,
1395 .print_conntrack = tcp_print_conntrack,
1396 .packet = tcp_packet,
1399 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
1400 .to_nlattr = tcp_to_nlattr,
1401 .from_nlattr = nlattr_to_tcp,
1402 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
1403 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
1404 .nla_policy = nf_ct_port_nla_policy,
1406 #ifdef CONFIG_SYSCTL
1407 .ctl_table_users = &tcp_sysctl_table_users,
1408 .ctl_table_header = &tcp_sysctl_header,
1409 .ctl_table = tcp_sysctl_table,
1412 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_tcp6);