ipv6: lock socket in ip6_datagram_connect()

[ Upstream commit 03645a11 ]

ip6_datagram_connect() is doing a lot of socket changes without
socket being locked.

This looks wrong, at least for udp_lib_rehash() which could corrupt
lists because of concurrent udp_sk(sk)->udp_portaddr_hash accesses.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

include/net/ip.h

@@ -138,6 +138,7 @@ static inline struct sk_buff *ip_finish_skb(struct sock *sk, struct flowi4 *fl4)
 }
 
 /* datagram.c */
+int __ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
 extern int		ip4_datagram_connect(struct sock *sk, 
 					     struct sockaddr *uaddr, int addr_len);
 

net/ipv4/datagram.c

@@ -20,7 +20,7 @@
 #include <net/route.h>
 #include <net/tcp_states.h>
 
-int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
+int __ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 {
 	struct inet_sock *inet = inet_sk(sk);
 	struct sockaddr_in *usin = (struct sockaddr_in *) uaddr;
@@ -39,8 +39,6 @@ int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 
 	sk_dst_reset(sk);
 
-	lock_sock(sk);
-
 	oif = sk->sk_bound_dev_if;
 	saddr = inet->inet_saddr;
 	if (ipv4_is_multicast(usin->sin_addr.s_addr)) {
@@ -81,7 +79,17 @@ int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 	sk_dst_set(sk, &rt->dst);
 	err = 0;
 out:
-	release_sock(sk);
 	return err;
 }
+EXPORT_SYMBOL(__ip4_datagram_connect);
+
+int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
+{
+	int res;
+
+	lock_sock(sk);
+	res = __ip4_datagram_connect(sk, uaddr, addr_len);
+	release_sock(sk);
+	return res;
+}
 EXPORT_SYMBOL(ip4_datagram_connect);

net/ipv6/datagram.c

@@ -38,7 +38,7 @@ static inline int ipv6_mapped_addr_any(const struct in6_addr *a)
 	return (ipv6_addr_v4mapped(a) && (a->s6_addr32[3] == 0));
 }
 
-int ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
+static int __ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 {
 	struct sockaddr_in6	*usin = (struct sockaddr_in6 *) uaddr;
 	struct inet_sock      	*inet = inet_sk(sk);
@@ -54,7 +54,7 @@ int ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 	if (usin->sin6_family == AF_INET) {
 		if (__ipv6_only_sock(sk))
 			return -EAFNOSUPPORT;
-		err = ip4_datagram_connect(sk, uaddr, addr_len);
+		err = __ip4_datagram_connect(sk, uaddr, addr_len);
 		goto ipv4_connected;
 	}
 
@@ -97,9 +97,9 @@ int ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 		sin.sin_addr.s_addr = daddr->s6_addr32[3];
 		sin.sin_port = usin->sin6_port;
 
-		err = ip4_datagram_connect(sk,
-					   (struct sockaddr*) &sin,
-					   sizeof(sin));
+		err = __ip4_datagram_connect(sk,
+					     (struct sockaddr *) &sin,
+					     sizeof(sin));
 
 ipv4_connected:
 		if (err)
@@ -203,6 +203,16 @@ int ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 	return err;
 }
 
+int ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
+{
+	int res;
+
+	lock_sock(sk);
+	res = __ip6_datagram_connect(sk, uaddr, addr_len);
+	release_sock(sk);
+	return res;
+}
+
 void ipv6_icmp_error(struct sock *sk, struct sk_buff *skb, int err,
 		     __be16 port, u32 info, u8 *payload)
 {