diff options
| author | Jozsef Kadlecsik <kadlec@blackhole.kfki.hu> | 2009-11-06 00:43:42 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-11-06 00:43:42 -0800 |
| commit | f9dd09c7f7199685601d75882447a6598be8a3e0 (patch) | |
| tree | 98ab4a75ec6c74cdb4aa807c491002ba33de56c5 /net/netfilter/nf_conntrack_core.c | |
| parent | f5209b4446d185cc95f46363f8043a743530c15a (diff) | |
netfilter: nf_nat: fix NAT issue in 2.6.30.4+
Vitezslav Samel discovered that since 2.6.30.4+ active FTP can not work
over NAT. The "cause" of the problem was a fix of unacknowledged data
detection with NAT (commit a3a9f79e361e864f0e9d75ebe2a0cb43d17c4272).
However, actually, that fix uncovered a long standing bug in TCP conntrack:
when NAT was enabled, we simply updated the max of the right edge of
the segments we have seen (td_end), by the offset NAT produced with
changing IP/port in the data. However, we did not update the other parameter
(td_maxend) which is affected by the NAT offset. Thus that could drift
away from the correct value and thus resulted breaking active FTP.
The patch below fixes the issue by *not* updating the conntrack parameters
from NAT, but instead taking into account the NAT offsets in conntrack in a
consistent way. (Updating from NAT would be more harder and expensive because
it'd need to re-calculate parameters we already calculated in conntrack.)
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/netfilter/nf_conntrack_core.c')
| -rw-r--r-- | net/netfilter/nf_conntrack_core.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 7c9ec3dee96e..0cdfb388a191 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -1350,6 +1350,11 @@ err_stat: return ret; } +s16 (*nf_ct_nat_offset)(const struct nf_conn *ct, + enum ip_conntrack_dir dir, + u32 seq); +EXPORT_SYMBOL_GPL(nf_ct_nat_offset); + int nf_conntrack_init(struct net *net) { int ret; @@ -1367,6 +1372,9 @@ int nf_conntrack_init(struct net *net) /* For use by REJECT target */ rcu_assign_pointer(ip_ct_attach, nf_conntrack_attach); rcu_assign_pointer(nf_ct_destroy, destroy_conntrack); + + /* Howto get NAT offsets */ + rcu_assign_pointer(nf_ct_nat_offset, NULL); } return 0; |