tproxy: fix hash locking issue when using port redirection in __inet_inherit_port()
When __inet_inherit_port() is called on a tproxy connection the wrong locks are
held for the inet_bind_bucket it is added to. __inet_inherit_port() made an
implicit assumption that the listener's port number (and thus its bind bucket).
Unfortunately, if you're using the TPROXY target to redirect skbs to a
transparent proxy that assumption is not true anymore and things break.
This patch adds code to __inet_inherit_port() so that it can handle this case
by looking up or creating a new bind bucket for the child socket and updates
callers of __inet_inherit_port() to gracefully handle __inet_inherit_port()
failing.
Reported by and original patch from Stephen Buck <stephen.buck@exinda.com>.
See http://marc.info/?t=128169268200001&r=1&w=2 for the original discussion.
Signed-off-by: KOVACS Krisztian <hidden@balabit.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index fb7ad5a..1b344f3 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -101,19 +101,43 @@
}
EXPORT_SYMBOL(inet_put_port);
-void __inet_inherit_port(struct sock *sk, struct sock *child)
+int __inet_inherit_port(struct sock *sk, struct sock *child)
{
struct inet_hashinfo *table = sk->sk_prot->h.hashinfo;
- const int bhash = inet_bhashfn(sock_net(sk), inet_sk(child)->inet_num,
+ unsigned short port = inet_sk(child)->inet_num;
+ const int bhash = inet_bhashfn(sock_net(sk), port,
table->bhash_size);
struct inet_bind_hashbucket *head = &table->bhash[bhash];
struct inet_bind_bucket *tb;
spin_lock(&head->lock);
tb = inet_csk(sk)->icsk_bind_hash;
+ if (tb->port != port) {
+ /* NOTE: using tproxy and redirecting skbs to a proxy
+ * on a different listener port breaks the assumption
+ * that the listener socket's icsk_bind_hash is the same
+ * as that of the child socket. We have to look up or
+ * create a new bind bucket for the child here. */
+ struct hlist_node *node;
+ inet_bind_bucket_for_each(tb, node, &head->chain) {
+ if (net_eq(ib_net(tb), sock_net(sk)) &&
+ tb->port == port)
+ break;
+ }
+ if (!node) {
+ tb = inet_bind_bucket_create(table->bind_bucket_cachep,
+ sock_net(sk), head, port);
+ if (!tb) {
+ spin_unlock(&head->lock);
+ return -ENOMEM;
+ }
+ }
+ }
sk_add_bind_node(child, &tb->owners);
inet_csk(child)->icsk_bind_hash = tb;
spin_unlock(&head->lock);
+
+ return 0;
}
EXPORT_SYMBOL_GPL(__inet_inherit_port);
