Eric Lee / smarc-ti-linux-kernel

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Commit c317428644c0af137d80069ab178cd797da3be45

Authored by Pablo Neira Ayuso
Committed by Patrick McHardy
1 parent 3db7e93d33

netfilter: nf_conntrack: set conntrack templates again if we return NF_REPEAT 

The TCP tracking code has a special case that allows to return
NF_REPEAT if we receive a new SYN packet while in TIME_WAIT state.

In this situation, the TCP tracking code destroys the existing
conntrack to start a new clean session.

[DESTROY] tcp      6 src=192.168.0.2 dst=192.168.1.2 sport=38925 dport=8000 src=192.168.1.2 dst=192.168.1.100 sport=8000 dport=38925 [ASSURED]
    [NEW] tcp      6 120 SYN_SENT src=192.168.0.2 dst=192.168.1.2 sport=38925 dport=8000 [UNREPLIED] src=192.168.1.2 dst=192.168.1.100 sport=8000 dport=38925

However, this is a problem for the iptables' CT target event filtering
which will not work in this case since the conntrack template will not
be there for the new session. To fix this, we reassign the conntrack
template to the packet if we return NF_REPEAT.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>

Showing 1 changed file with 9 additions and 2 deletions Side-by-side Diff

net/netfilter/nf_conntrack_core.c
Diff comments   View file @ c317428
... ... @@ -942,8 +942,15 @@
942 942 if (set_reply && !test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status))
943 943 nf_conntrack_event_cache(IPCT_REPLY, ct);
944 944 out:
945   - if (tmpl)
946   - nf_ct_put(tmpl);
  945 + if (tmpl) {
  946 + /* Special case: we have to repeat this hook, assign the
  947 + * template again to this packet. We assume that this packet
  948 + * has no conntrack assigned. This is used by nf_ct_tcp. */
  949 + if (ret == NF_REPEAT)
  950 + skb->nfct = (struct nf_conntrack *)tmpl;
  951 + else
  952 + nf_ct_put(tmpl);
  953 + }
947 954  
948 955 return ret;
949 956 }