[PATCH 3.16 022/306] netfilter: restart search if moved to other chain

Ben Hutchings
2017-02-15T23:19:08Z

From: Florian Westphal <fw@strlen.de>

commit 95a8d19f28e6b29377a880c6264391a62e07fccc upstream.

In case nf_conntrack_tuple_taken did not find a conflicting entry
check that all entries in this hash slot were tested and restart
in case an entry was moved to another chain.

Reported-by: Eric Dumazet <edumazet@google.com>
Fixes: ea781f197d6a ("netfilter: nf_conntrack: use SLAB_DESTROY_BY_RCU and get rid of call_rcu()")
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
[bwh: Backported to 3.16:
- Adjust context
- Use NF_CT_STAT_INC(), not the _ATOMIC variant, since we disable BHs]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/netfilter/nf_conntrack_core.c | 7 +++++++
1 file changed, 7 insertions(+)

--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -726,6 +726,7 @@ nf_conntrack_tuple_taken(const struct nf
* least once for the stats anyway.
*/
rcu_read_lock_bh();
+ begin:
hlist_nulls_for_each_entry_rcu(h, n, &net->ct.hash[hash], hnnode) {
ct = nf_ct_tuplehash_to_ctrack(h);
if (ct != ignored_conntrack &&
@@ -737,6 +738,12 @@ nf_conntrack_tuple_taken(const struct nf
}
NF_CT_STAT_INC(net, searched);
}
+
+ if (get_nulls_value(n) != hash) {
+ NF_CT_STAT_INC(net, search_restart);
+ goto begin;
+ }
+
rcu_read_unlock_bh();

return 0;