// SPDX-License-Identifier: GPL-2.0-only
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/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
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* (C) 2002-2013 Jozsef Kadlecsik <kadlec@netfilter.org>
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* (C) 2006-2012 Patrick McHardy <kaber@trash.net>
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*/
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#include <linux/types.h>
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#include <linux/timer.h>
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#include <linux/module.h>
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#include <linux/in.h>
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#include <linux/tcp.h>
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#include <linux/spinlock.h>
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#include <linux/skbuff.h>
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#include <linux/ipv6.h>
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#include <net/ip6_checksum.h>
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#include <asm/unaligned.h>
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#include <net/tcp.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/netfilter_ipv6.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_l4proto.h>
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#include <net/netfilter/nf_conntrack_ecache.h>
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#include <net/netfilter/nf_conntrack_seqadj.h>
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#include <net/netfilter/nf_conntrack_synproxy.h>
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#include <net/netfilter/nf_conntrack_timeout.h>
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#include <net/netfilter/nf_log.h>
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#include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
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#include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
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/* "Be conservative in what you do,
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be liberal in what you accept from others."
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If it's non-zero, we mark only out of window RST segments as INVALID. */
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static int nf_ct_tcp_be_liberal __read_mostly = 0;
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/* If it is set to zero, we disable picking up already established
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connections. */
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static int nf_ct_tcp_loose __read_mostly = 1;
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/* Max number of the retransmitted packets without receiving an (acceptable)
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ACK from the destination. If this number is reached, a shorter timer
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will be started. */
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static int nf_ct_tcp_max_retrans __read_mostly = 3;
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/* FIXME: Examine ipfilter's timeouts and conntrack transitions more
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closely. They're more complex. --RR */
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static const char *const tcp_conntrack_names[] = {
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"NONE",
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"SYN_SENT",
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"SYN_RECV",
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"ESTABLISHED",
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"FIN_WAIT",
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"CLOSE_WAIT",
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"LAST_ACK",
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"TIME_WAIT",
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"CLOSE",
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"SYN_SENT2",
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};
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#define SECS * HZ
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#define MINS * 60 SECS
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#define HOURS * 60 MINS
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#define DAYS * 24 HOURS
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static const unsigned int tcp_timeouts[TCP_CONNTRACK_TIMEOUT_MAX] = {
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[TCP_CONNTRACK_SYN_SENT] = 2 MINS,
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[TCP_CONNTRACK_SYN_RECV] = 60 SECS,
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[TCP_CONNTRACK_ESTABLISHED] = 5 DAYS,
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[TCP_CONNTRACK_FIN_WAIT] = 2 MINS,
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[TCP_CONNTRACK_CLOSE_WAIT] = 60 SECS,
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[TCP_CONNTRACK_LAST_ACK] = 30 SECS,
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[TCP_CONNTRACK_TIME_WAIT] = 2 MINS,
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[TCP_CONNTRACK_CLOSE] = 10 SECS,
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[TCP_CONNTRACK_SYN_SENT2] = 2 MINS,
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/* RFC1122 says the R2 limit should be at least 100 seconds.
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Linux uses 15 packets as limit, which corresponds
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to ~13-30min depending on RTO. */
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[TCP_CONNTRACK_RETRANS] = 5 MINS,
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[TCP_CONNTRACK_UNACK] = 5 MINS,
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};
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#define sNO TCP_CONNTRACK_NONE
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#define sSS TCP_CONNTRACK_SYN_SENT
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#define sSR TCP_CONNTRACK_SYN_RECV
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#define sES TCP_CONNTRACK_ESTABLISHED
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#define sFW TCP_CONNTRACK_FIN_WAIT
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#define sCW TCP_CONNTRACK_CLOSE_WAIT
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#define sLA TCP_CONNTRACK_LAST_ACK
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#define sTW TCP_CONNTRACK_TIME_WAIT
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#define sCL TCP_CONNTRACK_CLOSE
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#define sS2 TCP_CONNTRACK_SYN_SENT2
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#define sIV TCP_CONNTRACK_MAX
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#define sIG TCP_CONNTRACK_IGNORE
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/* What TCP flags are set from RST/SYN/FIN/ACK. */
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enum tcp_bit_set {
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TCP_SYN_SET,
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TCP_SYNACK_SET,
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TCP_FIN_SET,
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TCP_ACK_SET,
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TCP_RST_SET,
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TCP_NONE_SET,
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};
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/*
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* The TCP state transition table needs a few words...
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*
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* We are the man in the middle. All the packets go through us
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* but might get lost in transit to the destination.
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* It is assumed that the destinations can't receive segments
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* we haven't seen.
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*
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* The checked segment is in window, but our windows are *not*
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* equivalent with the ones of the sender/receiver. We always
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* try to guess the state of the current sender.
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*
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* The meaning of the states are:
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*
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* NONE: initial state
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* SYN_SENT: SYN-only packet seen
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* SYN_SENT2: SYN-only packet seen from reply dir, simultaneous open
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* SYN_RECV: SYN-ACK packet seen
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* ESTABLISHED: ACK packet seen
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* FIN_WAIT: FIN packet seen
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* CLOSE_WAIT: ACK seen (after FIN)
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* LAST_ACK: FIN seen (after FIN)
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* TIME_WAIT: last ACK seen
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* CLOSE: closed connection (RST)
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*
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* Packets marked as IGNORED (sIG):
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* if they may be either invalid or valid
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* and the receiver may send back a connection
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* closing RST or a SYN/ACK.
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*
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* Packets marked as INVALID (sIV):
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* if we regard them as truly invalid packets
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*/
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static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
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{
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/* ORIGINAL */
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/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
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/*syn*/ { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sS2 },
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/*
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* sNO -> sSS Initialize a new connection
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* sSS -> sSS Retransmitted SYN
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* sS2 -> sS2 Late retransmitted SYN
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* sSR -> sIG
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* sES -> sIG Error: SYNs in window outside the SYN_SENT state
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* are errors. Receiver will reply with RST
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* and close the connection.
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* Or we are not in sync and hold a dead connection.
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* sFW -> sIG
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* sCW -> sIG
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* sLA -> sIG
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* sTW -> sSS Reopened connection (RFC 1122).
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* sCL -> sSS
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*/
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/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
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/*synack*/ { sIV, sIV, sSR, sIV, sIV, sIV, sIV, sIV, sIV, sSR },
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/*
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* sNO -> sIV Too late and no reason to do anything
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* sSS -> sIV Client can't send SYN and then SYN/ACK
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* sS2 -> sSR SYN/ACK sent to SYN2 in simultaneous open
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* sSR -> sSR Late retransmitted SYN/ACK in simultaneous open
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* sES -> sIV Invalid SYN/ACK packets sent by the client
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* sFW -> sIV
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* sCW -> sIV
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* sLA -> sIV
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* sTW -> sIV
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* sCL -> sIV
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*/
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/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
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/*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
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/*
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* sNO -> sIV Too late and no reason to do anything...
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* sSS -> sIV Client migth not send FIN in this state:
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* we enforce waiting for a SYN/ACK reply first.
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* sS2 -> sIV
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* sSR -> sFW Close started.
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* sES -> sFW
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* sFW -> sLA FIN seen in both directions, waiting for
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* the last ACK.
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* Migth be a retransmitted FIN as well...
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* sCW -> sLA
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* sLA -> sLA Retransmitted FIN. Remain in the same state.
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* sTW -> sTW
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* sCL -> sCL
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*/
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/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
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/*ack*/ { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV },
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/*
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* sNO -> sES Assumed.
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* sSS -> sIV ACK is invalid: we haven't seen a SYN/ACK yet.
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* sS2 -> sIV
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* sSR -> sES Established state is reached.
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* sES -> sES :-)
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* sFW -> sCW Normal close request answered by ACK.
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* sCW -> sCW
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* sLA -> sTW Last ACK detected (RFC5961 challenged)
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* sTW -> sTW Retransmitted last ACK. Remain in the same state.
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* sCL -> sCL
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*/
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/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
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/*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
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/*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
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},
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{
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/* REPLY */
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/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
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/*syn*/ { sIV, sS2, sIV, sIV, sIV, sIV, sIV, sSS, sIV, sS2 },
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/*
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* sNO -> sIV Never reached.
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* sSS -> sS2 Simultaneous open
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* sS2 -> sS2 Retransmitted simultaneous SYN
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* sSR -> sIV Invalid SYN packets sent by the server
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* sES -> sIV
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* sFW -> sIV
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* sCW -> sIV
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* sLA -> sIV
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* sTW -> sSS Reopened connection, but server may have switched role
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* sCL -> sIV
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*/
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/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
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/*synack*/ { sIV, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIG, sSR },
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/*
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* sSS -> sSR Standard open.
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* sS2 -> sSR Simultaneous open
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* sSR -> sIG Retransmitted SYN/ACK, ignore it.
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* sES -> sIG Late retransmitted SYN/ACK?
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* sFW -> sIG Might be SYN/ACK answering ignored SYN
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* sCW -> sIG
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* sLA -> sIG
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* sTW -> sIG
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* sCL -> sIG
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*/
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/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
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/*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
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/*
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* sSS -> sIV Server might not send FIN in this state.
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* sS2 -> sIV
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* sSR -> sFW Close started.
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* sES -> sFW
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* sFW -> sLA FIN seen in both directions.
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* sCW -> sLA
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* sLA -> sLA Retransmitted FIN.
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* sTW -> sTW
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* sCL -> sCL
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*/
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/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
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/*ack*/ { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIG },
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/*
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* sSS -> sIG Might be a half-open connection.
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* sS2 -> sIG
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* sSR -> sSR Might answer late resent SYN.
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* sES -> sES :-)
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* sFW -> sCW Normal close request answered by ACK.
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* sCW -> sCW
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* sLA -> sTW Last ACK detected (RFC5961 challenged)
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* sTW -> sTW Retransmitted last ACK.
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* sCL -> sCL
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*/
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/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
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/*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL },
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/*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }
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}
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};
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#ifdef CONFIG_NF_CONNTRACK_PROCFS
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/* Print out the private part of the conntrack. */
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static void tcp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
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{
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if (test_bit(IPS_OFFLOAD_BIT, &ct->status))
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return;
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seq_printf(s, "%s ", tcp_conntrack_names[ct->proto.tcp.state]);
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}
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#endif
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static unsigned int get_conntrack_index(const struct tcphdr *tcph)
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{
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if (tcph->rst) return TCP_RST_SET;
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else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET);
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else if (tcph->fin) return TCP_FIN_SET;
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else if (tcph->ack) return TCP_ACK_SET;
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else return TCP_NONE_SET;
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}
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/* TCP connection tracking based on 'Real Stateful TCP Packet Filtering
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in IP Filter' by Guido van Rooij.
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http://www.sane.nl/events/sane2000/papers.html
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http://www.darkart.com/mirrors/www.obfuscation.org/ipf/
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The boundaries and the conditions are changed according to RFC793:
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the packet must intersect the window (i.e. segments may be
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after the right or before the left edge) and thus receivers may ACK
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segments after the right edge of the window.
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td_maxend = max(sack + max(win,1)) seen in reply packets
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td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets
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td_maxwin += seq + len - sender.td_maxend
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if seq + len > sender.td_maxend
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td_end = max(seq + len) seen in sent packets
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I. Upper bound for valid data: seq <= sender.td_maxend
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II. Lower bound for valid data: seq + len >= sender.td_end - receiver.td_maxwin
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III. Upper bound for valid (s)ack: sack <= receiver.td_end
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IV. Lower bound for valid (s)ack: sack >= receiver.td_end - MAXACKWINDOW
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where sack is the highest right edge of sack block found in the packet
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or ack in the case of packet without SACK option.
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The upper bound limit for a valid (s)ack is not ignored -
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we doesn't have to deal with fragments.
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*/
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static inline __u32 segment_seq_plus_len(__u32 seq,
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size_t len,
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unsigned int dataoff,
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const struct tcphdr *tcph)
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{
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/* XXX Should I use payload length field in IP/IPv6 header ?
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* - YK */
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return (seq + len - dataoff - tcph->doff*4
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+ (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0));
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}
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/* Fixme: what about big packets? */
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#define MAXACKWINCONST 66000
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#define MAXACKWINDOW(sender) \
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((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin \
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: MAXACKWINCONST)
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/*
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* Simplified tcp_parse_options routine from tcp_input.c
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*/
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static void tcp_options(const struct sk_buff *skb,
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unsigned int dataoff,
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const struct tcphdr *tcph,
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struct ip_ct_tcp_state *state)
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{
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unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
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const unsigned char *ptr;
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int length = (tcph->doff*4) - sizeof(struct tcphdr);
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if (!length)
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return;
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ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
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length, buff);
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BUG_ON(ptr == NULL);
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state->td_scale = 0;
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state->flags &= IP_CT_TCP_FLAG_BE_LIBERAL;
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while (length > 0) {
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int opcode=*ptr++;
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int opsize;
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switch (opcode) {
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case TCPOPT_EOL:
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return;
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case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
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length--;
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continue;
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default:
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if (length < 2)
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return;
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opsize=*ptr++;
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if (opsize < 2) /* "silly options" */
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return;
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if (opsize > length)
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return; /* don't parse partial options */
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if (opcode == TCPOPT_SACK_PERM
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&& opsize == TCPOLEN_SACK_PERM)
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state->flags |= IP_CT_TCP_FLAG_SACK_PERM;
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else if (opcode == TCPOPT_WINDOW
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&& opsize == TCPOLEN_WINDOW) {
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state->td_scale = *(u_int8_t *)ptr;
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if (state->td_scale > TCP_MAX_WSCALE)
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state->td_scale = TCP_MAX_WSCALE;
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state->flags |=
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IP_CT_TCP_FLAG_WINDOW_SCALE;
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}
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ptr += opsize - 2;
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length -= opsize;
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}
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}
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}
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static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
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const struct tcphdr *tcph, __u32 *sack)
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{
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unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
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const unsigned char *ptr;
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int length = (tcph->doff*4) - sizeof(struct tcphdr);
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__u32 tmp;
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if (!length)
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return;
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ptr = skb_header_pointer(skb, dataoff + sizeof(struct tcphdr),
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length, buff);
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BUG_ON(ptr == NULL);
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/* Fast path for timestamp-only option */
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if (length == TCPOLEN_TSTAMP_ALIGNED
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&& *(__be32 *)ptr == htonl((TCPOPT_NOP << 24)
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| (TCPOPT_NOP << 16)
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| (TCPOPT_TIMESTAMP << 8)
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| TCPOLEN_TIMESTAMP))
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return;
|
|
while (length > 0) {
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int opcode = *ptr++;
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int opsize, i;
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switch (opcode) {
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case TCPOPT_EOL:
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return;
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case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
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length--;
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continue;
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default:
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if (length < 2)
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return;
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opsize = *ptr++;
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if (opsize < 2) /* "silly options" */
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return;
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if (opsize > length)
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return; /* don't parse partial options */
|
|
if (opcode == TCPOPT_SACK
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&& opsize >= (TCPOLEN_SACK_BASE
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+ TCPOLEN_SACK_PERBLOCK)
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&& !((opsize - TCPOLEN_SACK_BASE)
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% TCPOLEN_SACK_PERBLOCK)) {
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for (i = 0;
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i < (opsize - TCPOLEN_SACK_BASE);
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i += TCPOLEN_SACK_PERBLOCK) {
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tmp = get_unaligned_be32((__be32 *)(ptr+i)+1);
|
|
if (after(tmp, *sack))
|
*sack = tmp;
|
}
|
return;
|
}
|
ptr += opsize - 2;
|
length -= opsize;
|
}
|
}
|
}
|
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static bool tcp_in_window(const struct nf_conn *ct,
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struct ip_ct_tcp *state,
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enum ip_conntrack_dir dir,
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unsigned int index,
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const struct sk_buff *skb,
|
unsigned int dataoff,
|
const struct tcphdr *tcph)
|
{
|
struct net *net = nf_ct_net(ct);
|
struct nf_tcp_net *tn = nf_tcp_pernet(net);
|
struct ip_ct_tcp_state *sender = &state->seen[dir];
|
struct ip_ct_tcp_state *receiver = &state->seen[!dir];
|
const struct nf_conntrack_tuple *tuple = &ct->tuplehash[dir].tuple;
|
__u32 seq, ack, sack, end, win, swin;
|
u16 win_raw;
|
s32 receiver_offset;
|
bool res, in_recv_win;
|
|
/*
|
* Get the required data from the packet.
|
*/
|
seq = ntohl(tcph->seq);
|
ack = sack = ntohl(tcph->ack_seq);
|
win_raw = ntohs(tcph->window);
|
win = win_raw;
|
end = segment_seq_plus_len(seq, skb->len, dataoff, tcph);
|
|
if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM)
|
tcp_sack(skb, dataoff, tcph, &sack);
|
|
/* Take into account NAT sequence number mangling */
|
receiver_offset = nf_ct_seq_offset(ct, !dir, ack - 1);
|
ack -= receiver_offset;
|
sack -= receiver_offset;
|
|
pr_debug("tcp_in_window: START\n");
|
pr_debug("tcp_in_window: ");
|
nf_ct_dump_tuple(tuple);
|
pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
|
seq, ack, receiver_offset, sack, receiver_offset, win, end);
|
pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
|
"receiver end=%u maxend=%u maxwin=%u scale=%i\n",
|
sender->td_end, sender->td_maxend, sender->td_maxwin,
|
sender->td_scale,
|
receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
|
receiver->td_scale);
|
|
if (sender->td_maxwin == 0) {
|
/*
|
* Initialize sender data.
|
*/
|
if (tcph->syn) {
|
/*
|
* SYN-ACK in reply to a SYN
|
* or SYN from reply direction in simultaneous open.
|
*/
|
sender->td_end =
|
sender->td_maxend = end;
|
sender->td_maxwin = (win == 0 ? 1 : win);
|
|
tcp_options(skb, dataoff, tcph, sender);
|
/*
|
* RFC 1323:
|
* Both sides must send the Window Scale option
|
* to enable window scaling in either direction.
|
*/
|
if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE
|
&& receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE))
|
sender->td_scale =
|
receiver->td_scale = 0;
|
if (!tcph->ack)
|
/* Simultaneous open */
|
return true;
|
} else {
|
/*
|
* We are in the middle of a connection,
|
* its history is lost for us.
|
* Let's try to use the data from the packet.
|
*/
|
sender->td_end = end;
|
swin = win << sender->td_scale;
|
sender->td_maxwin = (swin == 0 ? 1 : swin);
|
sender->td_maxend = end + sender->td_maxwin;
|
if (receiver->td_maxwin == 0) {
|
/* We haven't seen traffic in the other
|
* direction yet but we have to tweak window
|
* tracking to pass III and IV until that
|
* happens.
|
*/
|
receiver->td_end = receiver->td_maxend = sack;
|
} else if (sack == receiver->td_end + 1) {
|
/* Likely a reply to a keepalive.
|
* Needed for III.
|
*/
|
receiver->td_end++;
|
}
|
|
}
|
} else if (((state->state == TCP_CONNTRACK_SYN_SENT
|
&& dir == IP_CT_DIR_ORIGINAL)
|
|| (state->state == TCP_CONNTRACK_SYN_RECV
|
&& dir == IP_CT_DIR_REPLY))
|
&& after(end, sender->td_end)) {
|
/*
|
* RFC 793: "if a TCP is reinitialized ... then it need
|
* not wait at all; it must only be sure to use sequence
|
* numbers larger than those recently used."
|
*/
|
sender->td_end =
|
sender->td_maxend = end;
|
sender->td_maxwin = (win == 0 ? 1 : win);
|
|
tcp_options(skb, dataoff, tcph, sender);
|
}
|
|
if (!(tcph->ack)) {
|
/*
|
* If there is no ACK, just pretend it was set and OK.
|
*/
|
ack = sack = receiver->td_end;
|
} else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) ==
|
(TCP_FLAG_ACK|TCP_FLAG_RST))
|
&& (ack == 0)) {
|
/*
|
* Broken TCP stacks, that set ACK in RST packets as well
|
* with zero ack value.
|
*/
|
ack = sack = receiver->td_end;
|
}
|
|
if (tcph->rst && seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT)
|
/*
|
* RST sent answering SYN.
|
*/
|
seq = end = sender->td_end;
|
|
pr_debug("tcp_in_window: ");
|
nf_ct_dump_tuple(tuple);
|
pr_debug("seq=%u ack=%u+(%d) sack=%u+(%d) win=%u end=%u\n",
|
seq, ack, receiver_offset, sack, receiver_offset, win, end);
|
pr_debug("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i "
|
"receiver end=%u maxend=%u maxwin=%u scale=%i\n",
|
sender->td_end, sender->td_maxend, sender->td_maxwin,
|
sender->td_scale,
|
receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
|
receiver->td_scale);
|
|
/* Is the ending sequence in the receive window (if available)? */
|
in_recv_win = !receiver->td_maxwin ||
|
after(end, sender->td_end - receiver->td_maxwin - 1);
|
|
pr_debug("tcp_in_window: I=%i II=%i III=%i IV=%i\n",
|
before(seq, sender->td_maxend + 1),
|
(in_recv_win ? 1 : 0),
|
before(sack, receiver->td_end + 1),
|
after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1));
|
|
if (before(seq, sender->td_maxend + 1) &&
|
in_recv_win &&
|
before(sack, receiver->td_end + 1) &&
|
after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1)) {
|
/*
|
* Take into account window scaling (RFC 1323).
|
*/
|
if (!tcph->syn)
|
win <<= sender->td_scale;
|
|
/*
|
* Update sender data.
|
*/
|
swin = win + (sack - ack);
|
if (sender->td_maxwin < swin)
|
sender->td_maxwin = swin;
|
if (after(end, sender->td_end)) {
|
sender->td_end = end;
|
sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
|
}
|
if (tcph->ack) {
|
if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) {
|
sender->td_maxack = ack;
|
sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET;
|
} else if (after(ack, sender->td_maxack))
|
sender->td_maxack = ack;
|
}
|
|
/*
|
* Update receiver data.
|
*/
|
if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
|
receiver->td_maxwin += end - sender->td_maxend;
|
if (after(sack + win, receiver->td_maxend - 1)) {
|
receiver->td_maxend = sack + win;
|
if (win == 0)
|
receiver->td_maxend++;
|
}
|
if (ack == receiver->td_end)
|
receiver->flags &= ~IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
|
|
/*
|
* Check retransmissions.
|
*/
|
if (index == TCP_ACK_SET) {
|
if (state->last_dir == dir
|
&& state->last_seq == seq
|
&& state->last_ack == ack
|
&& state->last_end == end
|
&& state->last_win == win_raw)
|
state->retrans++;
|
else {
|
state->last_dir = dir;
|
state->last_seq = seq;
|
state->last_ack = ack;
|
state->last_end = end;
|
state->last_win = win_raw;
|
state->retrans = 0;
|
}
|
}
|
res = true;
|
} else {
|
res = false;
|
if (sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL ||
|
tn->tcp_be_liberal)
|
res = true;
|
if (!res) {
|
nf_ct_l4proto_log_invalid(skb, ct,
|
"%s",
|
before(seq, sender->td_maxend + 1) ?
|
in_recv_win ?
|
before(sack, receiver->td_end + 1) ?
|
after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1) ? "BUG"
|
: "ACK is under the lower bound (possible overly delayed ACK)"
|
: "ACK is over the upper bound (ACKed data not seen yet)"
|
: "SEQ is under the lower bound (already ACKed data retransmitted)"
|
: "SEQ is over the upper bound (over the window of the receiver)");
|
}
|
}
|
|
pr_debug("tcp_in_window: res=%u sender end=%u maxend=%u maxwin=%u "
|
"receiver end=%u maxend=%u maxwin=%u\n",
|
res, sender->td_end, sender->td_maxend, sender->td_maxwin,
|
receiver->td_end, receiver->td_maxend, receiver->td_maxwin);
|
|
return res;
|
}
|
|
/* table of valid flag combinations - PUSH, ECE and CWR are always valid */
|
static const u8 tcp_valid_flags[(TCPHDR_FIN|TCPHDR_SYN|TCPHDR_RST|TCPHDR_ACK|
|
TCPHDR_URG) + 1] =
|
{
|
[TCPHDR_SYN] = 1,
|
[TCPHDR_SYN|TCPHDR_URG] = 1,
|
[TCPHDR_SYN|TCPHDR_ACK] = 1,
|
[TCPHDR_RST] = 1,
|
[TCPHDR_RST|TCPHDR_ACK] = 1,
|
[TCPHDR_FIN|TCPHDR_ACK] = 1,
|
[TCPHDR_FIN|TCPHDR_ACK|TCPHDR_URG] = 1,
|
[TCPHDR_ACK] = 1,
|
[TCPHDR_ACK|TCPHDR_URG] = 1,
|
};
|
|
static void tcp_error_log(const struct sk_buff *skb,
|
const struct nf_hook_state *state,
|
const char *msg)
|
{
|
nf_l4proto_log_invalid(skb, state->net, state->pf, IPPROTO_TCP, "%s", msg);
|
}
|
|
/* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c. */
|
static bool tcp_error(const struct tcphdr *th,
|
struct sk_buff *skb,
|
unsigned int dataoff,
|
const struct nf_hook_state *state)
|
{
|
unsigned int tcplen = skb->len - dataoff;
|
u8 tcpflags;
|
|
/* Not whole TCP header or malformed packet */
|
if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
|
tcp_error_log(skb, state, "truncated packet");
|
return true;
|
}
|
|
/* Checksum invalid? Ignore.
|
* We skip checking packets on the outgoing path
|
* because the checksum is assumed to be correct.
|
*/
|
/* FIXME: Source route IP option packets --RR */
|
if (state->net->ct.sysctl_checksum &&
|
state->hook == NF_INET_PRE_ROUTING &&
|
nf_checksum(skb, state->hook, dataoff, IPPROTO_TCP, state->pf)) {
|
tcp_error_log(skb, state, "bad checksum");
|
return true;
|
}
|
|
/* Check TCP flags. */
|
tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
|
if (!tcp_valid_flags[tcpflags]) {
|
tcp_error_log(skb, state, "invalid tcp flag combination");
|
return true;
|
}
|
|
return false;
|
}
|
|
static noinline bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
|
unsigned int dataoff,
|
const struct tcphdr *th)
|
{
|
enum tcp_conntrack new_state;
|
struct net *net = nf_ct_net(ct);
|
const struct nf_tcp_net *tn = nf_tcp_pernet(net);
|
const struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[0];
|
const struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[1];
|
|
/* Don't need lock here: this conntrack not in circulation yet */
|
new_state = tcp_conntracks[0][get_conntrack_index(th)][TCP_CONNTRACK_NONE];
|
|
/* Invalid: delete conntrack */
|
if (new_state >= TCP_CONNTRACK_MAX) {
|
pr_debug("nf_ct_tcp: invalid new deleting.\n");
|
return false;
|
}
|
|
if (new_state == TCP_CONNTRACK_SYN_SENT) {
|
memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
|
/* SYN packet */
|
ct->proto.tcp.seen[0].td_end =
|
segment_seq_plus_len(ntohl(th->seq), skb->len,
|
dataoff, th);
|
ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
|
if (ct->proto.tcp.seen[0].td_maxwin == 0)
|
ct->proto.tcp.seen[0].td_maxwin = 1;
|
ct->proto.tcp.seen[0].td_maxend =
|
ct->proto.tcp.seen[0].td_end;
|
|
tcp_options(skb, dataoff, th, &ct->proto.tcp.seen[0]);
|
} else if (tn->tcp_loose == 0) {
|
/* Don't try to pick up connections. */
|
return false;
|
} else {
|
memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
|
/*
|
* We are in the middle of a connection,
|
* its history is lost for us.
|
* Let's try to use the data from the packet.
|
*/
|
ct->proto.tcp.seen[0].td_end =
|
segment_seq_plus_len(ntohl(th->seq), skb->len,
|
dataoff, th);
|
ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
|
if (ct->proto.tcp.seen[0].td_maxwin == 0)
|
ct->proto.tcp.seen[0].td_maxwin = 1;
|
ct->proto.tcp.seen[0].td_maxend =
|
ct->proto.tcp.seen[0].td_end +
|
ct->proto.tcp.seen[0].td_maxwin;
|
|
/* We assume SACK and liberal window checking to handle
|
* window scaling */
|
ct->proto.tcp.seen[0].flags =
|
ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
|
IP_CT_TCP_FLAG_BE_LIBERAL;
|
}
|
|
/* tcp_packet will set them */
|
ct->proto.tcp.last_index = TCP_NONE_SET;
|
|
pr_debug("%s: sender end=%u maxend=%u maxwin=%u scale=%i "
|
"receiver end=%u maxend=%u maxwin=%u scale=%i\n",
|
__func__,
|
sender->td_end, sender->td_maxend, sender->td_maxwin,
|
sender->td_scale,
|
receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
|
receiver->td_scale);
|
return true;
|
}
|
|
static bool nf_conntrack_tcp_established(const struct nf_conn *ct)
|
{
|
return ct->proto.tcp.state == TCP_CONNTRACK_ESTABLISHED &&
|
test_bit(IPS_ASSURED_BIT, &ct->status);
|
}
|
|
static void nf_ct_tcp_state_reset(struct ip_ct_tcp_state *state)
|
{
|
state->td_end = 0;
|
state->td_maxend = 0;
|
state->td_maxwin = 0;
|
state->td_maxack = 0;
|
state->td_scale = 0;
|
state->flags &= IP_CT_TCP_FLAG_BE_LIBERAL;
|
}
|
|
/* Returns verdict for packet, or -1 for invalid. */
|
int nf_conntrack_tcp_packet(struct nf_conn *ct,
|
struct sk_buff *skb,
|
unsigned int dataoff,
|
enum ip_conntrack_info ctinfo,
|
const struct nf_hook_state *state)
|
{
|
struct net *net = nf_ct_net(ct);
|
struct nf_tcp_net *tn = nf_tcp_pernet(net);
|
struct nf_conntrack_tuple *tuple;
|
enum tcp_conntrack new_state, old_state;
|
unsigned int index, *timeouts;
|
enum ip_conntrack_dir dir;
|
const struct tcphdr *th;
|
struct tcphdr _tcph;
|
unsigned long timeout;
|
|
th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
|
if (th == NULL)
|
return -NF_ACCEPT;
|
|
if (tcp_error(th, skb, dataoff, state))
|
return -NF_ACCEPT;
|
|
if (!nf_ct_is_confirmed(ct) && !tcp_new(ct, skb, dataoff, th))
|
return -NF_ACCEPT;
|
|
spin_lock_bh(&ct->lock);
|
old_state = ct->proto.tcp.state;
|
dir = CTINFO2DIR(ctinfo);
|
index = get_conntrack_index(th);
|
new_state = tcp_conntracks[dir][index][old_state];
|
tuple = &ct->tuplehash[dir].tuple;
|
|
switch (new_state) {
|
case TCP_CONNTRACK_SYN_SENT:
|
if (old_state < TCP_CONNTRACK_TIME_WAIT)
|
break;
|
/* RFC 1122: "When a connection is closed actively,
|
* it MUST linger in TIME-WAIT state for a time 2xMSL
|
* (Maximum Segment Lifetime). However, it MAY accept
|
* a new SYN from the remote TCP to reopen the connection
|
* directly from TIME-WAIT state, if..."
|
* We ignore the conditions because we are in the
|
* TIME-WAIT state anyway.
|
*
|
* Handle aborted connections: we and the server
|
* think there is an existing connection but the client
|
* aborts it and starts a new one.
|
*/
|
if (((ct->proto.tcp.seen[dir].flags
|
| ct->proto.tcp.seen[!dir].flags)
|
& IP_CT_TCP_FLAG_CLOSE_INIT)
|
|| (ct->proto.tcp.last_dir == dir
|
&& ct->proto.tcp.last_index == TCP_RST_SET)) {
|
/* Attempt to reopen a closed/aborted connection.
|
* Delete this connection and look up again. */
|
spin_unlock_bh(&ct->lock);
|
|
/* Only repeat if we can actually remove the timer.
|
* Destruction may already be in progress in process
|
* context and we must give it a chance to terminate.
|
*/
|
if (nf_ct_kill(ct))
|
return -NF_REPEAT;
|
return NF_DROP;
|
}
|
fallthrough;
|
case TCP_CONNTRACK_IGNORE:
|
/* Ignored packets:
|
*
|
* Our connection entry may be out of sync, so ignore
|
* packets which may signal the real connection between
|
* the client and the server.
|
*
|
* a) SYN in ORIGINAL
|
* b) SYN/ACK in REPLY
|
* c) ACK in reply direction after initial SYN in original.
|
*
|
* If the ignored packet is invalid, the receiver will send
|
* a RST we'll catch below.
|
*/
|
if (index == TCP_SYNACK_SET
|
&& ct->proto.tcp.last_index == TCP_SYN_SET
|
&& ct->proto.tcp.last_dir != dir
|
&& ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
|
/* b) This SYN/ACK acknowledges a SYN that we earlier
|
* ignored as invalid. This means that the client and
|
* the server are both in sync, while the firewall is
|
* not. We get in sync from the previously annotated
|
* values.
|
*/
|
old_state = TCP_CONNTRACK_SYN_SENT;
|
new_state = TCP_CONNTRACK_SYN_RECV;
|
ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
|
ct->proto.tcp.last_end;
|
ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
|
ct->proto.tcp.last_end;
|
ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
|
ct->proto.tcp.last_win == 0 ?
|
1 : ct->proto.tcp.last_win;
|
ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
|
ct->proto.tcp.last_wscale;
|
ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
|
ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
|
ct->proto.tcp.last_flags;
|
nf_ct_tcp_state_reset(&ct->proto.tcp.seen[dir]);
|
break;
|
}
|
ct->proto.tcp.last_index = index;
|
ct->proto.tcp.last_dir = dir;
|
ct->proto.tcp.last_seq = ntohl(th->seq);
|
ct->proto.tcp.last_end =
|
segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
|
ct->proto.tcp.last_win = ntohs(th->window);
|
|
/* a) This is a SYN in ORIGINAL. The client and the server
|
* may be in sync but we are not. In that case, we annotate
|
* the TCP options and let the packet go through. If it is a
|
* valid SYN packet, the server will reply with a SYN/ACK, and
|
* then we'll get in sync. Otherwise, the server potentially
|
* responds with a challenge ACK if implementing RFC5961.
|
*/
|
if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
|
struct ip_ct_tcp_state seen = {};
|
|
ct->proto.tcp.last_flags =
|
ct->proto.tcp.last_wscale = 0;
|
tcp_options(skb, dataoff, th, &seen);
|
if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
|
ct->proto.tcp.last_flags |=
|
IP_CT_TCP_FLAG_WINDOW_SCALE;
|
ct->proto.tcp.last_wscale = seen.td_scale;
|
}
|
if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
|
ct->proto.tcp.last_flags |=
|
IP_CT_TCP_FLAG_SACK_PERM;
|
}
|
/* Mark the potential for RFC5961 challenge ACK,
|
* this pose a special problem for LAST_ACK state
|
* as ACK is intrepretated as ACKing last FIN.
|
*/
|
if (old_state == TCP_CONNTRACK_LAST_ACK)
|
ct->proto.tcp.last_flags |=
|
IP_CT_EXP_CHALLENGE_ACK;
|
}
|
spin_unlock_bh(&ct->lock);
|
nf_ct_l4proto_log_invalid(skb, ct, "invalid packet ignored in "
|
"state %s ", tcp_conntrack_names[old_state]);
|
return NF_ACCEPT;
|
case TCP_CONNTRACK_MAX:
|
/* Special case for SYN proxy: when the SYN to the server or
|
* the SYN/ACK from the server is lost, the client may transmit
|
* a keep-alive packet while in SYN_SENT state. This needs to
|
* be associated with the original conntrack entry in order to
|
* generate a new SYN with the correct sequence number.
|
*/
|
if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
|
index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
|
ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
|
ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
|
pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
|
spin_unlock_bh(&ct->lock);
|
return NF_ACCEPT;
|
}
|
|
/* Invalid packet */
|
pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
|
dir, get_conntrack_index(th), old_state);
|
spin_unlock_bh(&ct->lock);
|
nf_ct_l4proto_log_invalid(skb, ct, "invalid state");
|
return -NF_ACCEPT;
|
case TCP_CONNTRACK_TIME_WAIT:
|
/* RFC5961 compliance cause stack to send "challenge-ACK"
|
* e.g. in response to spurious SYNs. Conntrack MUST
|
* not believe this ACK is acking last FIN.
|
*/
|
if (old_state == TCP_CONNTRACK_LAST_ACK &&
|
index == TCP_ACK_SET &&
|
ct->proto.tcp.last_dir != dir &&
|
ct->proto.tcp.last_index == TCP_SYN_SET &&
|
(ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
|
/* Detected RFC5961 challenge ACK */
|
ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
|
spin_unlock_bh(&ct->lock);
|
nf_ct_l4proto_log_invalid(skb, ct, "challenge-ack ignored");
|
return NF_ACCEPT; /* Don't change state */
|
}
|
break;
|
case TCP_CONNTRACK_SYN_SENT2:
|
/* tcp_conntracks table is not smart enough to handle
|
* simultaneous open.
|
*/
|
ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN;
|
break;
|
case TCP_CONNTRACK_SYN_RECV:
|
if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET &&
|
ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN)
|
new_state = TCP_CONNTRACK_ESTABLISHED;
|
break;
|
case TCP_CONNTRACK_CLOSE:
|
if (index != TCP_RST_SET)
|
break;
|
|
if (ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) {
|
u32 seq = ntohl(th->seq);
|
|
if (before(seq, ct->proto.tcp.seen[!dir].td_maxack)) {
|
/* Invalid RST */
|
spin_unlock_bh(&ct->lock);
|
nf_ct_l4proto_log_invalid(skb, ct, "invalid rst");
|
return -NF_ACCEPT;
|
}
|
|
if (!nf_conntrack_tcp_established(ct) ||
|
seq == ct->proto.tcp.seen[!dir].td_maxack)
|
break;
|
|
/* Check if rst is part of train, such as
|
* foo:80 > bar:4379: P, 235946583:235946602(19) ack 42
|
* foo:80 > bar:4379: R, 235946602:235946602(0) ack 42
|
*/
|
if (ct->proto.tcp.last_index == TCP_ACK_SET &&
|
ct->proto.tcp.last_dir == dir &&
|
seq == ct->proto.tcp.last_end)
|
break;
|
|
/* ... RST sequence number doesn't match exactly, keep
|
* established state to allow a possible challenge ACK.
|
*/
|
new_state = old_state;
|
}
|
if (((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
|
&& ct->proto.tcp.last_index == TCP_SYN_SET)
|
|| (!test_bit(IPS_ASSURED_BIT, &ct->status)
|
&& ct->proto.tcp.last_index == TCP_ACK_SET))
|
&& ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
|
/* RST sent to invalid SYN or ACK we had let through
|
* at a) and c) above:
|
*
|
* a) SYN was in window then
|
* c) we hold a half-open connection.
|
*
|
* Delete our connection entry.
|
* We skip window checking, because packet might ACK
|
* segments we ignored. */
|
goto in_window;
|
}
|
break;
|
default:
|
/* Keep compilers happy. */
|
break;
|
}
|
|
if (!tcp_in_window(ct, &ct->proto.tcp, dir, index,
|
skb, dataoff, th)) {
|
spin_unlock_bh(&ct->lock);
|
return -NF_ACCEPT;
|
}
|
in_window:
|
/* From now on we have got in-window packets */
|
ct->proto.tcp.last_index = index;
|
ct->proto.tcp.last_dir = dir;
|
|
pr_debug("tcp_conntracks: ");
|
nf_ct_dump_tuple(tuple);
|
pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
|
(th->syn ? 1 : 0), (th->ack ? 1 : 0),
|
(th->fin ? 1 : 0), (th->rst ? 1 : 0),
|
old_state, new_state);
|
|
ct->proto.tcp.state = new_state;
|
if (old_state != new_state
|
&& new_state == TCP_CONNTRACK_FIN_WAIT)
|
ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
|
|
timeouts = nf_ct_timeout_lookup(ct);
|
if (!timeouts)
|
timeouts = tn->timeouts;
|
|
if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
|
timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
|
timeout = timeouts[TCP_CONNTRACK_RETRANS];
|
else if (unlikely(index == TCP_RST_SET))
|
timeout = timeouts[TCP_CONNTRACK_CLOSE];
|
else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
|
IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
|
timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
|
timeout = timeouts[TCP_CONNTRACK_UNACK];
|
else if (ct->proto.tcp.last_win == 0 &&
|
timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
|
timeout = timeouts[TCP_CONNTRACK_RETRANS];
|
else
|
timeout = timeouts[new_state];
|
spin_unlock_bh(&ct->lock);
|
|
if (new_state != old_state)
|
nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
|
|
if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
|
/* If only reply is a RST, we can consider ourselves not to
|
have an established connection: this is a fairly common
|
problem case, so we can delete the conntrack
|
immediately. --RR */
|
if (th->rst) {
|
nf_ct_kill_acct(ct, ctinfo, skb);
|
return NF_ACCEPT;
|
}
|
/* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
|
* pickup with loose=1. Avoid large ESTABLISHED timeout.
|
*/
|
if (new_state == TCP_CONNTRACK_ESTABLISHED &&
|
timeout > timeouts[TCP_CONNTRACK_UNACK])
|
timeout = timeouts[TCP_CONNTRACK_UNACK];
|
} else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
|
&& (old_state == TCP_CONNTRACK_SYN_RECV
|
|| old_state == TCP_CONNTRACK_ESTABLISHED)
|
&& new_state == TCP_CONNTRACK_ESTABLISHED) {
|
/* Set ASSURED if we see valid ack in ESTABLISHED
|
after SYN_RECV or a valid answer for a picked up
|
connection. */
|
set_bit(IPS_ASSURED_BIT, &ct->status);
|
nf_conntrack_event_cache(IPCT_ASSURED, ct);
|
}
|
nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
|
|
return NF_ACCEPT;
|
}
|
|
static bool tcp_can_early_drop(const struct nf_conn *ct)
|
{
|
switch (ct->proto.tcp.state) {
|
case TCP_CONNTRACK_FIN_WAIT:
|
case TCP_CONNTRACK_LAST_ACK:
|
case TCP_CONNTRACK_TIME_WAIT:
|
case TCP_CONNTRACK_CLOSE:
|
case TCP_CONNTRACK_CLOSE_WAIT:
|
return true;
|
default:
|
break;
|
}
|
|
return false;
|
}
|
|
#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
|
|
#include <linux/netfilter/nfnetlink.h>
|
#include <linux/netfilter/nfnetlink_conntrack.h>
|
|
static int tcp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
|
struct nf_conn *ct)
|
{
|
struct nlattr *nest_parms;
|
struct nf_ct_tcp_flags tmp = {};
|
|
spin_lock_bh(&ct->lock);
|
nest_parms = nla_nest_start(skb, CTA_PROTOINFO_TCP);
|
if (!nest_parms)
|
goto nla_put_failure;
|
|
if (nla_put_u8(skb, CTA_PROTOINFO_TCP_STATE, ct->proto.tcp.state) ||
|
nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
|
ct->proto.tcp.seen[0].td_scale) ||
|
nla_put_u8(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY,
|
ct->proto.tcp.seen[1].td_scale))
|
goto nla_put_failure;
|
|
tmp.flags = ct->proto.tcp.seen[0].flags;
|
if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
|
sizeof(struct nf_ct_tcp_flags), &tmp))
|
goto nla_put_failure;
|
|
tmp.flags = ct->proto.tcp.seen[1].flags;
|
if (nla_put(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
|
sizeof(struct nf_ct_tcp_flags), &tmp))
|
goto nla_put_failure;
|
spin_unlock_bh(&ct->lock);
|
|
nla_nest_end(skb, nest_parms);
|
|
return 0;
|
|
nla_put_failure:
|
spin_unlock_bh(&ct->lock);
|
return -1;
|
}
|
|
static const struct nla_policy tcp_nla_policy[CTA_PROTOINFO_TCP_MAX+1] = {
|
[CTA_PROTOINFO_TCP_STATE] = { .type = NLA_U8 },
|
[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] = { .type = NLA_U8 },
|
[CTA_PROTOINFO_TCP_WSCALE_REPLY] = { .type = NLA_U8 },
|
[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL] = { .len = sizeof(struct nf_ct_tcp_flags) },
|
[CTA_PROTOINFO_TCP_FLAGS_REPLY] = { .len = sizeof(struct nf_ct_tcp_flags) },
|
};
|
|
#define TCP_NLATTR_SIZE ( \
|
NLA_ALIGN(NLA_HDRLEN + 1) + \
|
NLA_ALIGN(NLA_HDRLEN + 1) + \
|
NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)) + \
|
NLA_ALIGN(NLA_HDRLEN + sizeof(struct nf_ct_tcp_flags)))
|
|
static int nlattr_to_tcp(struct nlattr *cda[], struct nf_conn *ct)
|
{
|
struct nlattr *pattr = cda[CTA_PROTOINFO_TCP];
|
struct nlattr *tb[CTA_PROTOINFO_TCP_MAX+1];
|
int err;
|
|
/* updates could not contain anything about the private
|
* protocol info, in that case skip the parsing */
|
if (!pattr)
|
return 0;
|
|
err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_TCP_MAX, pattr,
|
tcp_nla_policy, NULL);
|
if (err < 0)
|
return err;
|
|
if (tb[CTA_PROTOINFO_TCP_STATE] &&
|
nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]) >= TCP_CONNTRACK_MAX)
|
return -EINVAL;
|
|
spin_lock_bh(&ct->lock);
|
if (tb[CTA_PROTOINFO_TCP_STATE])
|
ct->proto.tcp.state = nla_get_u8(tb[CTA_PROTOINFO_TCP_STATE]);
|
|
if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]) {
|
struct nf_ct_tcp_flags *attr =
|
nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL]);
|
ct->proto.tcp.seen[0].flags &= ~attr->mask;
|
ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
|
}
|
|
if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]) {
|
struct nf_ct_tcp_flags *attr =
|
nla_data(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY]);
|
ct->proto.tcp.seen[1].flags &= ~attr->mask;
|
ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
|
}
|
|
if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL] &&
|
tb[CTA_PROTOINFO_TCP_WSCALE_REPLY] &&
|
ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
|
ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
|
ct->proto.tcp.seen[0].td_scale =
|
nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL]);
|
ct->proto.tcp.seen[1].td_scale =
|
nla_get_u8(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY]);
|
}
|
spin_unlock_bh(&ct->lock);
|
|
return 0;
|
}
|
|
static unsigned int tcp_nlattr_tuple_size(void)
|
{
|
static unsigned int size __read_mostly;
|
|
if (!size)
|
size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
|
|
return size;
|
}
|
#endif
|
|
#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
|
|
#include <linux/netfilter/nfnetlink.h>
|
#include <linux/netfilter/nfnetlink_cttimeout.h>
|
|
static int tcp_timeout_nlattr_to_obj(struct nlattr *tb[],
|
struct net *net, void *data)
|
{
|
struct nf_tcp_net *tn = nf_tcp_pernet(net);
|
unsigned int *timeouts = data;
|
int i;
|
|
if (!timeouts)
|
timeouts = tn->timeouts;
|
/* set default TCP timeouts. */
|
for (i=0; i<TCP_CONNTRACK_TIMEOUT_MAX; i++)
|
timeouts[i] = tn->timeouts[i];
|
|
if (tb[CTA_TIMEOUT_TCP_SYN_SENT]) {
|
timeouts[TCP_CONNTRACK_SYN_SENT] =
|
ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT]))*HZ;
|
}
|
|
if (tb[CTA_TIMEOUT_TCP_SYN_RECV]) {
|
timeouts[TCP_CONNTRACK_SYN_RECV] =
|
ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_RECV]))*HZ;
|
}
|
if (tb[CTA_TIMEOUT_TCP_ESTABLISHED]) {
|
timeouts[TCP_CONNTRACK_ESTABLISHED] =
|
ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_ESTABLISHED]))*HZ;
|
}
|
if (tb[CTA_TIMEOUT_TCP_FIN_WAIT]) {
|
timeouts[TCP_CONNTRACK_FIN_WAIT] =
|
ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_FIN_WAIT]))*HZ;
|
}
|
if (tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]) {
|
timeouts[TCP_CONNTRACK_CLOSE_WAIT] =
|
ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE_WAIT]))*HZ;
|
}
|
if (tb[CTA_TIMEOUT_TCP_LAST_ACK]) {
|
timeouts[TCP_CONNTRACK_LAST_ACK] =
|
ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_LAST_ACK]))*HZ;
|
}
|
if (tb[CTA_TIMEOUT_TCP_TIME_WAIT]) {
|
timeouts[TCP_CONNTRACK_TIME_WAIT] =
|
ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_TIME_WAIT]))*HZ;
|
}
|
if (tb[CTA_TIMEOUT_TCP_CLOSE]) {
|
timeouts[TCP_CONNTRACK_CLOSE] =
|
ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_CLOSE]))*HZ;
|
}
|
if (tb[CTA_TIMEOUT_TCP_SYN_SENT2]) {
|
timeouts[TCP_CONNTRACK_SYN_SENT2] =
|
ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_SYN_SENT2]))*HZ;
|
}
|
if (tb[CTA_TIMEOUT_TCP_RETRANS]) {
|
timeouts[TCP_CONNTRACK_RETRANS] =
|
ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_RETRANS]))*HZ;
|
}
|
if (tb[CTA_TIMEOUT_TCP_UNACK]) {
|
timeouts[TCP_CONNTRACK_UNACK] =
|
ntohl(nla_get_be32(tb[CTA_TIMEOUT_TCP_UNACK]))*HZ;
|
}
|
|
timeouts[CTA_TIMEOUT_TCP_UNSPEC] = timeouts[CTA_TIMEOUT_TCP_SYN_SENT];
|
return 0;
|
}
|
|
static int
|
tcp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
|
{
|
const unsigned int *timeouts = data;
|
|
if (nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT,
|
htonl(timeouts[TCP_CONNTRACK_SYN_SENT] / HZ)) ||
|
nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_RECV,
|
htonl(timeouts[TCP_CONNTRACK_SYN_RECV] / HZ)) ||
|
nla_put_be32(skb, CTA_TIMEOUT_TCP_ESTABLISHED,
|
htonl(timeouts[TCP_CONNTRACK_ESTABLISHED] / HZ)) ||
|
nla_put_be32(skb, CTA_TIMEOUT_TCP_FIN_WAIT,
|
htonl(timeouts[TCP_CONNTRACK_FIN_WAIT] / HZ)) ||
|
nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE_WAIT,
|
htonl(timeouts[TCP_CONNTRACK_CLOSE_WAIT] / HZ)) ||
|
nla_put_be32(skb, CTA_TIMEOUT_TCP_LAST_ACK,
|
htonl(timeouts[TCP_CONNTRACK_LAST_ACK] / HZ)) ||
|
nla_put_be32(skb, CTA_TIMEOUT_TCP_TIME_WAIT,
|
htonl(timeouts[TCP_CONNTRACK_TIME_WAIT] / HZ)) ||
|
nla_put_be32(skb, CTA_TIMEOUT_TCP_CLOSE,
|
htonl(timeouts[TCP_CONNTRACK_CLOSE] / HZ)) ||
|
nla_put_be32(skb, CTA_TIMEOUT_TCP_SYN_SENT2,
|
htonl(timeouts[TCP_CONNTRACK_SYN_SENT2] / HZ)) ||
|
nla_put_be32(skb, CTA_TIMEOUT_TCP_RETRANS,
|
htonl(timeouts[TCP_CONNTRACK_RETRANS] / HZ)) ||
|
nla_put_be32(skb, CTA_TIMEOUT_TCP_UNACK,
|
htonl(timeouts[TCP_CONNTRACK_UNACK] / HZ)))
|
goto nla_put_failure;
|
return 0;
|
|
nla_put_failure:
|
return -ENOSPC;
|
}
|
|
static const struct nla_policy tcp_timeout_nla_policy[CTA_TIMEOUT_TCP_MAX+1] = {
|
[CTA_TIMEOUT_TCP_SYN_SENT] = { .type = NLA_U32 },
|
[CTA_TIMEOUT_TCP_SYN_RECV] = { .type = NLA_U32 },
|
[CTA_TIMEOUT_TCP_ESTABLISHED] = { .type = NLA_U32 },
|
[CTA_TIMEOUT_TCP_FIN_WAIT] = { .type = NLA_U32 },
|
[CTA_TIMEOUT_TCP_CLOSE_WAIT] = { .type = NLA_U32 },
|
[CTA_TIMEOUT_TCP_LAST_ACK] = { .type = NLA_U32 },
|
[CTA_TIMEOUT_TCP_TIME_WAIT] = { .type = NLA_U32 },
|
[CTA_TIMEOUT_TCP_CLOSE] = { .type = NLA_U32 },
|
[CTA_TIMEOUT_TCP_SYN_SENT2] = { .type = NLA_U32 },
|
[CTA_TIMEOUT_TCP_RETRANS] = { .type = NLA_U32 },
|
[CTA_TIMEOUT_TCP_UNACK] = { .type = NLA_U32 },
|
};
|
#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
|
|
void nf_conntrack_tcp_init_net(struct net *net)
|
{
|
struct nf_tcp_net *tn = nf_tcp_pernet(net);
|
int i;
|
|
for (i = 0; i < TCP_CONNTRACK_TIMEOUT_MAX; i++)
|
tn->timeouts[i] = tcp_timeouts[i];
|
|
/* timeouts[0] is unused, make it same as SYN_SENT so
|
* ->timeouts[0] contains 'new' timeout, like udp or icmp.
|
*/
|
tn->timeouts[0] = tcp_timeouts[TCP_CONNTRACK_SYN_SENT];
|
tn->tcp_loose = nf_ct_tcp_loose;
|
tn->tcp_be_liberal = nf_ct_tcp_be_liberal;
|
tn->tcp_max_retrans = nf_ct_tcp_max_retrans;
|
}
|
|
const struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp =
|
{
|
.l4proto = IPPROTO_TCP,
|
#ifdef CONFIG_NF_CONNTRACK_PROCFS
|
.print_conntrack = tcp_print_conntrack,
|
#endif
|
.can_early_drop = tcp_can_early_drop,
|
#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
|
.to_nlattr = tcp_to_nlattr,
|
.from_nlattr = nlattr_to_tcp,
|
.tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
|
.nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
|
.nlattr_tuple_size = tcp_nlattr_tuple_size,
|
.nlattr_size = TCP_NLATTR_SIZE,
|
.nla_policy = nf_ct_port_nla_policy,
|
#endif
|
#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
|
.ctnl_timeout = {
|
.nlattr_to_obj = tcp_timeout_nlattr_to_obj,
|
.obj_to_nlattr = tcp_timeout_obj_to_nlattr,
|
.nlattr_max = CTA_TIMEOUT_TCP_MAX,
|
.obj_size = sizeof(unsigned int) *
|
TCP_CONNTRACK_TIMEOUT_MAX,
|
.nla_policy = tcp_timeout_nla_policy,
|
},
|
#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
|
};
|
