From 3e86638e9a0be8bcf7db007909d8307b8b9f8e3b Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Mon, 2 May 2016 18:40:14 +0200 Subject: [PATCH] netfilter: conntrack: consider ct netns in early_drop logic When iterating, skip conntrack entries living in a different netns. We could ignore netns and kill some other non-assured one, but it has two problems: - a netns can kill non-assured conntracks in other namespace - we would start to 'over-subscribe' the affected/overlimit netns. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_core.c | 43 ++++++++++++++++++------------- 1 file changed, 25 insertions(+), 18 deletions(-) diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 4c906e73e872..e3787cf33427 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -764,18 +764,20 @@ static noinline int early_drop(struct net *net, unsigned int _hash) { /* Use oldest entry, which is roughly LRU */ struct nf_conntrack_tuple_hash *h; - struct nf_conn *ct = NULL, *tmp; + struct nf_conn *tmp; struct hlist_nulls_node *n; - unsigned int i = 0, cnt = 0; - int dropped = 0; - unsigned int hash, sequence; + unsigned int i, hash, sequence; + struct nf_conn *ct = NULL; spinlock_t *lockp; + bool ret = false; + + i = 0; local_bh_disable(); restart: sequence = read_seqcount_begin(&nf_conntrack_generation); - hash = scale_hash(_hash); - for (; i < nf_conntrack_htable_size; i++) { + for (; i < NF_CT_EVICTION_RANGE; i++) { + hash = scale_hash(_hash++); lockp = &nf_conntrack_locks[hash % CONNTRACK_LOCKS]; nf_conntrack_lock(lockp); if (read_seqcount_retry(&nf_conntrack_generation, sequence)) { @@ -785,35 +787,40 @@ static noinline int early_drop(struct net *net, unsigned int _hash) hlist_nulls_for_each_entry_rcu(h, n, &nf_conntrack_hash[hash], hnnode) { tmp = nf_ct_tuplehash_to_ctrack(h); - if (!test_bit(IPS_ASSURED_BIT, &tmp->status) && - !nf_ct_is_dying(tmp) && - atomic_inc_not_zero(&tmp->ct_general.use)) { + + if (test_bit(IPS_ASSURED_BIT, &tmp->status) || + !net_eq(nf_ct_net(tmp), net) || + nf_ct_is_dying(tmp)) + continue; + + if (atomic_inc_not_zero(&tmp->ct_general.use)) { ct = tmp; break; } - cnt++; } - hash = (hash + 1) % nf_conntrack_htable_size; spin_unlock(lockp); - - if (ct || cnt >= NF_CT_EVICTION_RANGE) + if (ct) break; - } + local_bh_enable(); if (!ct) - return dropped; + return false; - if (del_timer(&ct->timeout)) { + /* kill only if in same netns -- might have moved due to + * SLAB_DESTROY_BY_RCU rules + */ + if (net_eq(nf_ct_net(ct), net) && del_timer(&ct->timeout)) { if (nf_ct_delete(ct, 0, 0)) { - dropped = 1; NF_CT_STAT_INC_ATOMIC(net, early_drop); + ret = true; } } + nf_ct_put(ct); - return dropped; + return ret; } static struct nf_conn * -- GitLab