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  1. 23 Nov, 2009 3 commits
    • Joe Perches's avatar
      netfilter: net/ipv[46]/netfilter: Move && and || to end of previous line · 3666ed1c
      Joe Perches authored 
      
Compile tested only.
Signed-off-by: default avatarJoe Perches <joe@perches.com>
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
      3666ed1c
    • Florian Westphal's avatar
      netfilter: xtables: fix conntrack match v1 ipt-save output · 3a042929
      Florian Westphal authored 
      commit d6d3f08b
(netfilter: xtables: conntrack match revision 2) does break the
v1 conntrack match iptables-save output in a subtle way.

Problem is as follows:

    up = kmalloc(sizeof(*up), GFP_KERNEL);
[..]
   /*
    * The strategy here is to minimize the overhead of v1 matching,
    * by prebuilding a v2 struct and putting the pointer into the
    * v1 dataspace.
    */
    memcpy(up, info, offsetof(typeof(*info), state_mask));
[..]
    *(void **)info  = up;

As the v2 struct pointer is saved in the match data space,
it clobbers the first structure member (->origsrc_addr).

Because the _v1 match function grabs this pointer and does not actually
look at the v1 origsrc, run time functionality does not break.
But iptables -nvL (or iptables-save) cannot know that v1 origsrc_addr
has been overloaded in this way:

$ iptables -p tcp -A OUTPUT -m conntrack --ctorigsrc 10.0.0.1 -j ACCEPT
$ iptables-save
-A OUTPUT -p tcp ...
      3a042929
    • Pablo Neira Ayuso's avatar
      netfilter: nf_ct_tcp: improve out-of-sync situation in TCP tracking · c4832c7b
      Pablo Neira Ayuso authored 
      
Without this patch, if we receive a SYN packet from the client while
the firewall is out-of-sync, we let it go through. Then, if we see
the SYN/ACK reply coming from the server, we destroy the conntrack
entry and drop the packet to trigger a new retransmission. Then,
the retransmision from the client is used to start a new clean
session.

This patch improves the current handling. Basically, if we see an
unexpected SYN packet, we annotate the TCP options. Then, if we
see the reply SYN/ACK, this means that the firewall was indeed
out-of-sync. Therefore, we set a clean new session from the existing
entry based on the annotated values.

This patch adds two new 8-bits fields that fit in a 16-bits gap of
the ip_ct_tcp structure.

This patch is particularly useful for conntrackd since the
asynchronous nature of the state-synchronization allows to have
backup nodes that are not perfect copies of the master. This helps
to improve the recovery under some worst-case scenarios.

I have tested this by creating lots of conntrack entries in wrong
state:

for ((i=1024;i<65535;i++)); do conntrack -I -p tcp -s 192.168.2.101 -d 192.168.2.2 --sport $i --dport 80 -t 800 --state ESTABLISHED -u ASSURED,SEEN_REPLY; done

Then, I make some TCP connections:

$ echo GET / | nc 192.168.2.2 80

The events show the result:

 [UPDATE] tcp      6 60 SYN_RECV src=192.168.2.101 dst=192.168.2.2 sport=33220 dport=80 src=192.168.2.2 dst=192.168.2.101 sport=80 dport=33220 [ASSURED]
 [UPDATE] tcp      6 432000 ESTABLISHED src=192.168.2.101 dst=192.168.2.2 sport=33220 dport=80 src=192.168.2.2 dst=192.168.2.101 sport=80 dport=33220 [ASSURED]
 [UPDATE] tcp      6 120 FIN_WAIT src=192.168.2.101 dst=192.168.2.2 sport=33220 dport=80 src=192.168.2.2 dst=192.168.2.101 sport=80 dport=33220 [ASSURED]
 [UPDATE] tcp      6 30 LAST_ACK src=192.168.2.101 dst=192.168.2.2 sport=33220 dport=80 src=192.168.2.2 dst=192.168.2.101 sport=80 dport=33220 [ASSURED]
 [UPDATE] tcp      6 120 TIME_WAIT src=192.168.2.101 dst=192.168.2.2 sport=33220 dport=80 src=192.168.2.2 dst=192.168.2.101 sport=80 dport=33220 [ASSURED]

and tcpdump shows no retransmissions:

20:47:57.271951 IP 192.168.2.101.33221 > 192.168.2.2.www: S 435402517:435402517(0) win 5840 <mss 1460,sackOK,timestamp 4294961827 0,nop,wscale 6>
20:47:57.273538 IP 192.168.2.2.www > 192.168.2.101.33221: S 3509927945:3509927945(0) ack 435402518 win 5792 <mss 1460,sackOK,timestamp 235681024 4294961827,nop,wscale 4>
20:47:57.273608 IP 192.168.2.101.33221 > 192.168.2.2.www: . ack 3509927946 win 92 <nop,nop,timestamp 4294961827 235681024>
20:47:57.273693 IP 192.168.2.101.33221 > 192.168.2.2.www: P 435402518:435402524(6) ack 3509927946 win 92 <nop,nop,timestamp 4294961827 235681024>
20:47:57.275492 IP 192.168.2.2.www > 192.168.2.101.33221: . ack 435402524 win 362 <nop,nop,timestamp 235681024 4294961827>
20:47:57.276492 IP 192.168.2.2.www > 192.168.2.101.33221: P 3509927946:3509928082(136) ack 435402524 win 362 <nop,nop,timestamp 235681025 4294961827>
20:47:57.276515 IP 192.168.2.101.33221 > 192.168.2.2.www: . ack 3509928082 win 108 <nop,nop,timestamp 4294961828 235681025>
20:47:57.276521 IP 192.168.2.2.www > 192.168.2.101.33221: F 3509928082:3509928082(0) ack 435402524 win 362 <nop,nop,timestamp 235681025 4294961827>
20:47:57.277369 IP 192.168.2.101.33221 > 192.168.2.2.www: F 435402524:435402524(0) ack 3509928083 win 108 <nop,nop,timestamp 4294961828 235681025>
20:47:57.279491 IP 192.168.2.2.www > 192.168.2.101.33221: . ack 435402525 win 362 <nop,nop,timestamp 235681025 4294961828>

I also added a rule to log invalid packets, with no occurrences  :-) .
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
Acked-by: default avatarJozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
      c4832c7b
  3. 06 Nov, 2009 1 commit
  5. 05 Nov, 2009 2 commits
  7. 04 Nov, 2009 1 commit
  9. 29 Oct, 2009 33 commits
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