From bc92470413f3af152db0d8f90ef3eb13f8cc417a Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Wed, 26 Aug 2020 00:52:44 +0200 Subject: netfilter: conntrack: add clash resolution stat counter There is a misconception about what "insert_failed" means. We increment this even when a clash got resolved, so it might not indicate a problem. Add a dedicated counter for clash resolution and only increment insert_failed if a clash cannot be resolved. For the old /proc interface, export this in place of an older stat that got removed a while back. For ctnetlink, export this with a new attribute. Also correct an outdated comment that implies we add a duplicate tuple -- we only add the (unique) reply direction. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_core.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'net/netfilter/nf_conntrack_core.c') diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index a111bcf1b93c..93e77ca0efad 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -859,7 +859,6 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct) out: nf_conntrack_double_unlock(hash, reply_hash); - NF_CT_STAT_INC(net, insert_failed); local_bh_enable(); return -EEXIST; } @@ -934,7 +933,7 @@ static int __nf_ct_resolve_clash(struct sk_buff *skb, nf_conntrack_put(&loser_ct->ct_general); nf_ct_set(skb, ct, ctinfo); - NF_CT_STAT_INC(net, insert_failed); + NF_CT_STAT_INC(net, clash_resolve); return NF_ACCEPT; } @@ -998,6 +997,8 @@ static int nf_ct_resolve_clash_harder(struct sk_buff *skb, u32 repl_idx) hlist_nulls_add_head_rcu(&loser_ct->tuplehash[IP_CT_DIR_REPLY].hnnode, &nf_conntrack_hash[repl_idx]); + + NF_CT_STAT_INC(net, clash_resolve); return NF_ACCEPT; } @@ -1027,10 +1028,10 @@ static int nf_ct_resolve_clash_harder(struct sk_buff *skb, u32 repl_idx) * * Failing that, the new, unconfirmed conntrack is still added to the table * provided that the collision only occurs in the ORIGINAL direction. - * The new entry will be added after the existing one in the hash list, + * The new entry will be added only in the non-clashing REPLY direction, * so packets in the ORIGINAL direction will continue to match the existing * entry. The new entry will also have a fixed timeout so it expires -- - * due to the collision, it will not see bidirectional traffic. + * due to the collision, it will only see reply traffic. * * Returns NF_DROP if the clash could not be resolved. */ -- cgit v1.2.3