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[4/6] netfilter: tproxy: properly refcount tcp listeners

Message ID 1471541348-1538-5-git-send-email-pablo@netfilter.org
State Accepted
Delegated to: Pablo Neira
Headers show

Commit Message

Pablo Neira Ayuso Aug. 18, 2016, 5:29 p.m. UTC 
From: Eric Dumazet <edumazet@google.com>

inet_lookup_listener() and inet6_lookup_listener() no longer
take a reference on the found listener.

This minimal patch adds back the refcounting, but we might do
this differently in net-next later.

Fixes: 3b24d854cb35 ("tcp/dccp: do not touch listener sk_refcnt under synflood")
Reported-and-tested-by: Denys Fedoryshchenko <nuclearcat@nuclearcat.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/xt_TPROXY.c | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox

Patch

diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
index 7f4414d..663c4c3 100644
--- a/net/netfilter/xt_TPROXY.c
+++ b/net/netfilter/xt_TPROXY.c
@@ -127,6 +127,8 @@  nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, void *hp,
 						    daddr, dport,
 						    in->ifindex);
 
+			if (sk && !atomic_inc_not_zero(&sk->sk_refcnt))
+				sk = NULL;
 			/* NOTE: we return listeners even if bound to
 			 * 0.0.0.0, those are filtered out in
 			 * xt_socket, since xt_TPROXY needs 0 bound
@@ -195,6 +197,8 @@  nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff, void *hp,
 						   daddr, ntohs(dport),
 						   in->ifindex);
 
+			if (sk && !atomic_inc_not_zero(&sk->sk_refcnt))
+				sk = NULL;
 			/* NOTE: we return listeners even if bound to
 			 * 0.0.0.0, those are filtered out in
 			 * xt_socket, since xt_TPROXY needs 0 bound