netfilter: conntrack: split resolve_clash function

Followup patch will need a helper function with the 'clashing entries
refer to the identical tuple in both directions' resolution logic.

This patch will add another resolve_clash helper where loser_ct must
not be added to the dying list because it will be inserted into the
table.

Therefore this also moves the stat counters and dying-list insertion
of the losing ct.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 5fda5bd10160a73d667f9837736ed6f7725be981..3f069eb0f0fc78f23f1d9593aab8e2bdbe326a3b 100644 (file)
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -907,6 +907,39 @@ static void __nf_conntrack_insert_prepare(struct nf_conn *ct)
                tstamp->start = ktime_get_real_ns();
 }
 
+static int __nf_ct_resolve_clash(struct sk_buff *skb,
+                                struct nf_conntrack_tuple_hash *h)
+{
+       /* This is the conntrack entry already in hashes that won race. */
+       struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
+       enum ip_conntrack_info ctinfo;
+       struct nf_conn *loser_ct;
+
+       loser_ct = nf_ct_get(skb, &ctinfo);
+
+       if (nf_ct_is_dying(ct))
+               return NF_DROP;
+
+       if (!atomic_inc_not_zero(&ct->ct_general.use))
+               return NF_DROP;
+
+       if (((ct->status & IPS_NAT_DONE_MASK) == 0) ||
+           nf_ct_match(ct, loser_ct)) {
+               struct net *net = nf_ct_net(ct);
+
+               nf_ct_acct_merge(ct, ctinfo, loser_ct);
+               nf_ct_add_to_dying_list(loser_ct);
+               nf_conntrack_put(&loser_ct->ct_general);
+               nf_ct_set(skb, ct, ctinfo);
+
+               NF_CT_STAT_INC(net, insert_failed);
+               return NF_ACCEPT;
+       }
+
+       nf_ct_put(ct);
+       return NF_DROP;
+}
+
 /**
  * nf_ct_resolve_clash - attempt to handle clash without packet drop
  *
@@ -941,31 +974,23 @@ nf_ct_resolve_clash(struct sk_buff *skb, struct nf_conntrack_tuple_hash *h)
        enum ip_conntrack_info ctinfo;
        struct nf_conn *loser_ct;
        struct net *net;
+       int ret;
 
        loser_ct = nf_ct_get(skb, &ctinfo);
+       net = nf_ct_net(loser_ct);
 
        l4proto = nf_ct_l4proto_find(nf_ct_protonum(ct));
        if (!l4proto->allow_clash)
                goto drop;
 
-       if (nf_ct_is_dying(ct))
-               goto drop;
-
-       if (!atomic_inc_not_zero(&ct->ct_general.use))
-               goto drop;
-
-       if (((ct->status & IPS_NAT_DONE_MASK) == 0) ||
-           nf_ct_match(ct, loser_ct)) {
-               nf_ct_acct_merge(ct, ctinfo, loser_ct);
-               nf_conntrack_put(&loser_ct->ct_general);
-               nf_ct_set(skb, ct, ctinfo);
-               return NF_ACCEPT;
-       }
+       ret = __nf_ct_resolve_clash(skb, h);
+       if (ret == NF_ACCEPT)
+               return ret;
 
-       nf_ct_put(ct);
 drop:
-       net = nf_ct_net(loser_ct);
+       nf_ct_add_to_dying_list(loser_ct);
        NF_CT_STAT_INC(net, drop);
+       NF_CT_STAT_INC(net, insert_failed);
        return NF_DROP;
 }
 
@@ -1034,6 +1059,7 @@ __nf_conntrack_confirm(struct sk_buff *skb)
 
        if (unlikely(nf_ct_is_dying(ct))) {
                nf_ct_add_to_dying_list(ct);
+               NF_CT_STAT_INC(net, insert_failed);
                goto dying;
        }
 
@@ -1075,11 +1101,9 @@ __nf_conntrack_confirm(struct sk_buff *skb)
        return NF_ACCEPT;
 
 out:
-       nf_ct_add_to_dying_list(ct);
        ret = nf_ct_resolve_clash(skb, h);
 dying:
        nf_conntrack_double_unlock(hash, reply_hash);
-       NF_CT_STAT_INC(net, insert_failed);
        local_bh_enable();
        return ret;
 }