diff options
| author | Pablo Neira Ayuso <pablo@netfilter.org> | 2016-05-01 00:28:40 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2016-05-05 16:39:50 +0200 |
| commit | 71d8c47fc653711c41bc3282e5b0e605b3727956 (patch) | |
| tree | 3bfe17c0f91a43e69c8d849563572905735abcf9 /include | |
| parent | ba76738c032ec0af3acbecd85c429c6a5c9e5e5e (diff) | |
netfilter: conntrack: introduce clash resolution on insertion race
This patch introduces nf_ct_resolve_clash() to resolve race condition on
conntrack insertions.
This is particularly a problem for connection-less protocols such as
UDP, with no initial handshake. Two or more packets may race to insert
the entry resulting in packet drops.
Another problematic scenario are packets enqueued to userspace via
NFQUEUE after the raw table, that make it easier to trigger this
race.
To resolve this, the idea is to reset the conntrack entry to the one
that won race. Packet and bytes counters are also merged.
The 'insert_failed' stats still accounts for this situation, after
this patch, the drop counter is bumped whenever we drop packets, so we
can watch for unresolved clashes.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/netfilter/nf_conntrack_l4proto.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/net/netfilter/nf_conntrack_l4proto.h b/include/net/netfilter/nf_conntrack_l4proto.h index 956d8a6ac069..1a5fb36f165f 100644 --- a/include/net/netfilter/nf_conntrack_l4proto.h +++ b/include/net/netfilter/nf_conntrack_l4proto.h @@ -23,6 +23,9 @@ struct nf_conntrack_l4proto { /* L4 Protocol number. */ u_int8_t l4proto; + /* Resolve clashes on insertion races. */ + bool allow_clash; + /* Try to fill in the third arg: dataoff is offset past network protocol hdr. Return true if possible. */ bool (*pkt_to_tuple)(const struct sk_buff *skb, unsigned int dataoff, |