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authorPatrick McHardy <kaber@trash.net>2009-06-29 14:07:56 +0200
committerPatrick McHardy <kaber@trash.net>2009-06-29 14:07:56 +0200
commita3a9f79e361e864f0e9d75ebe2a0cb43d17c4272 (patch)
treee38bb7cc051cf197a813d553713e3071d375a1b9 /net/ipv4
parent308ff823ebd749a94d3b6ac26b95bc0eb114c39e (diff)
netfilter: tcp conntrack: fix unacknowledged data detection with NAT
When NAT helpers change the TCP packet size, the highest seen sequence number needs to be corrected. This is currently only done upwards, when the packet size is reduced the sequence number is unchanged. This causes TCP conntrack to falsely detect unacknowledged data and decrease the timeout. Fix by updating the highest seen sequence number in both directions after packet mangling. Tested-by: Krzysztof Piotr Oledzki <ole@ans.pl> Signed-off-by: Patrick McHardy <kaber@trash.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/netfilter/nf_nat_helper.c17
1 files changed, 11 insertions, 6 deletions
diff --git a/net/ipv4/netfilter/nf_nat_helper.c b/net/ipv4/netfilter/nf_nat_helper.c
index 155c008626c..09172a65d9b 100644
--- a/net/ipv4/netfilter/nf_nat_helper.c
+++ b/net/ipv4/netfilter/nf_nat_helper.c
@@ -191,7 +191,8 @@ nf_nat_mangle_tcp_packet(struct sk_buff *skb,
ct, ctinfo);
/* Tell TCP window tracking about seq change */
nf_conntrack_tcp_update(skb, ip_hdrlen(skb),
- ct, CTINFO2DIR(ctinfo));
+ ct, CTINFO2DIR(ctinfo),
+ (int)rep_len - (int)match_len);
nf_conntrack_event_cache(IPCT_NATSEQADJ, ct);
}
@@ -377,6 +378,7 @@ nf_nat_seq_adjust(struct sk_buff *skb,
struct tcphdr *tcph;
int dir;
__be32 newseq, newack;
+ s16 seqoff, ackoff;
struct nf_conn_nat *nat = nfct_nat(ct);
struct nf_nat_seq *this_way, *other_way;
@@ -390,15 +392,18 @@ nf_nat_seq_adjust(struct sk_buff *skb,
tcph = (void *)skb->data + ip_hdrlen(skb);
if (after(ntohl(tcph->seq), this_way->correction_pos))
- newseq = htonl(ntohl(tcph->seq) + this_way->offset_after);
+ seqoff = this_way->offset_after;
else
- newseq = htonl(ntohl(tcph->seq) + this_way->offset_before);
+ seqoff = this_way->offset_before;
if (after(ntohl(tcph->ack_seq) - other_way->offset_before,
other_way->correction_pos))
- newack = htonl(ntohl(tcph->ack_seq) - other_way->offset_after);
+ ackoff = other_way->offset_after;
else
- newack = htonl(ntohl(tcph->ack_seq) - other_way->offset_before);
+ ackoff = other_way->offset_before;
+
+ newseq = htonl(ntohl(tcph->seq) + seqoff);
+ newack = htonl(ntohl(tcph->ack_seq) - ackoff);
inet_proto_csum_replace4(&tcph->check, skb, tcph->seq, newseq, 0);
inet_proto_csum_replace4(&tcph->check, skb, tcph->ack_seq, newack, 0);
@@ -413,7 +418,7 @@ nf_nat_seq_adjust(struct sk_buff *skb,
if (!nf_nat_sack_adjust(skb, tcph, ct, ctinfo))
return 0;
- nf_conntrack_tcp_update(skb, ip_hdrlen(skb), ct, dir);
+ nf_conntrack_tcp_update(skb, ip_hdrlen(skb), ct, dir, seqoff);
return 1;
}