ipv6: lock socket in ip6_datagram_connect()

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>

3 files changed, 28 insertions, 9 deletions

diff --git a/include/net/ip.h b/include/net/ip.h
index 0750a186ea63..d5fe9f2ab699 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -161,6 +161,7 @@ static inline __u8 get_rtconn_flags(struct ipcm_cookie* ipc, struct sock* sk)
 }
 
 /* datagram.c */
+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);
 
 void ip4_datagram_release_cb(struct sock *sk);
diff --git a/net/ipv4/datagram.c b/net/ipv4/datagram.c
index 90c0e8386116..574fad9cca05 100644
--- a/net/ipv4/datagram.c
+++ b/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)) {
@@ -82,9 +80,19 @@ 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);
 
 /* Because UDP xmit path can manipulate sk_dst_cache without holding
diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index 62d908e64eeb..b10a88986a98 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -40,7 +40,7 @@ static bool 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);
@@ -56,7 +56,7 @@ 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;
         }
 
@@ -98,9 +98,9 @@ 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)
@@ -204,6 +204,16 @@ out:
         fl6_sock_release(flowlabel);
         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;
+}
 EXPORT_SYMBOL_GPL(ip6_datagram_connect);
 
 int ip6_datagram_connect_v6_only(struct sock *sk, struct sockaddr *uaddr,