diff options
| author | Jozsef Kadlecsik <kadlec@blackhole.kfki.hu> | 2009-11-06 00:43:42 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-12-08 10:22:33 -0800 |
| commit | 325786e848323cd6c3e658886448ceafda09bf86 (patch) | |
| tree | c140e36b879670c86bcd95a7100b7cf1b5f3f39f /net/ipv4/netfilter/nf_nat_helper.c | |
| parent | 636addb566d468fe7159e678d4c0d195dc77707d (diff) | |
netfilter: nf_nat: fix NAT issue in 2.6.30.4+
commit f9dd09c7f7199685601d75882447a6598be8a3e0 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'net/ipv4/netfilter/nf_nat_helper.c')
| -rw-r--r-- | net/ipv4/netfilter/nf_nat_helper.c | 34 |
1 files changed, 23 insertions, 11 deletions
diff --git a/net/ipv4/netfilter/nf_nat_helper.c b/net/ipv4/netfilter/nf_nat_helper.c index 09172a65d9b6..f9520fa3aba9 100644 --- a/net/ipv4/netfilter/nf_nat_helper.c +++ b/net/ipv4/netfilter/nf_nat_helper.c @@ -73,6 +73,28 @@ adjust_tcp_sequence(u32 seq, DUMP_OFFSET(this_way); } +/* Get the offset value, for conntrack */ +s16 nf_nat_get_offset(const struct nf_conn *ct, + enum ip_conntrack_dir dir, + u32 seq) +{ + struct nf_conn_nat *nat = nfct_nat(ct); + struct nf_nat_seq *this_way; + s16 offset; + + if (!nat) + return 0; + + this_way = &nat->seq[dir]; + spin_lock_bh(&nf_nat_seqofs_lock); + offset = after(seq, this_way->correction_pos) + ? this_way->offset_after : this_way->offset_before; + spin_unlock_bh(&nf_nat_seqofs_lock); + + return offset; +} +EXPORT_SYMBOL_GPL(nf_nat_get_offset); + /* Frobs data inside this packet, which is linear. */ static void mangle_contents(struct sk_buff *skb, unsigned int dataoff, @@ -189,11 +211,6 @@ nf_nat_mangle_tcp_packet(struct sk_buff *skb, adjust_tcp_sequence(ntohl(tcph->seq), (int)rep_len - (int)match_len, ct, ctinfo); - /* Tell TCP window tracking about seq change */ - nf_conntrack_tcp_update(skb, ip_hdrlen(skb), - ct, CTINFO2DIR(ctinfo), - (int)rep_len - (int)match_len); - nf_conntrack_event_cache(IPCT_NATSEQADJ, ct); } return 1; @@ -415,12 +432,7 @@ nf_nat_seq_adjust(struct sk_buff *skb, tcph->seq = newseq; tcph->ack_seq = newack; - if (!nf_nat_sack_adjust(skb, tcph, ct, ctinfo)) - return 0; - - nf_conntrack_tcp_update(skb, ip_hdrlen(skb), ct, dir, seqoff); - - return 1; + return nf_nat_sack_adjust(skb, tcph, ct, ctinfo); } /* Setup NAT on this expected conntrack so it follows master. */ |