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| author | Jozsef Kadlecsik <kadlec@blackhole.kfki.hu> | 2012-08-31 09:55:54 +0000 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2012-09-09 22:13:49 +0200 |
| commit | 4a70bbfaef0361d27272629d1a250a937edcafe4 (patch) | |
| tree | 8389e2f3b55cfcec5770a9fd83b9a52c31e4128b | |
| parent | 64f509ce71b08d037998e93dd51180c19b2f464c (diff) | |
| download | linux-4a70bbfaef0361d27272629d1a250a937edcafe4.tar.gz linux-4a70bbfaef0361d27272629d1a250a937edcafe4.tar.bz2 linux-4a70bbfaef0361d27272629d1a250a937edcafe4.zip | |
netfilter: Validate the sequence number of dataless ACK packets as well
We spare nothing by not validating the sequence number of dataless
ACK packets and enabling it makes harder off-path attacks.
See: "Reflection scan: an Off-Path Attack on TCP" by Jan Wrobel,
http://arxiv.org/abs/1201.2074
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
| -rw-r--r-- | net/netfilter/nf_conntrack_proto_tcp.c | 10 |
1 files changed, 2 insertions, 8 deletions
diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c index aba98f942979..e046b3756aab 100644 --- a/net/netfilter/nf_conntrack_proto_tcp.c +++ b/net/netfilter/nf_conntrack_proto_tcp.c @@ -630,15 +630,9 @@ static bool tcp_in_window(const struct nf_conn *ct, ack = sack = receiver->td_end; } - if (seq == end - && (!tcph->rst - || (seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT))) + if (tcph->rst && seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT) /* - * Packets contains no data: we assume it is valid - * and check the ack value only. - * However RST segments are always validated by their - * SEQ number, except when seq == 0 (reset sent answering - * SYN. + * RST sent answering SYN. */ seq = end = sender->td_end; |