ipv4: Lock socket and use cork flow in ip4_datagram_connect().

This is to make sure that an l2tp socket's inet cork flow is
fully filled in, when it's encapsulated in UDP.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 8 deletions

diff --git a/net/ipv4/datagram.c b/net/ipv4/datagram.c
index d5a2e6995bae..424fafbc8cb0 100644
--- a/net/ipv4/datagram.c
+++ b/net/ipv4/datagram.c
@@ -24,7 +24,7 @@ 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;
-        struct flowi4 fl4;
+        struct flowi4 *fl4;
         struct rtable *rt;
         __be32 saddr;
         int oif;
@@ -39,6 +39,8 @@ 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)) {
@@ -47,7 +49,8 @@ int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
                 if (!saddr)
                         saddr = inet->mc_addr;
         }
-        rt = ip_route_connect(&fl4, usin->sin_addr.s_addr, saddr,
+        fl4 = &inet->cork.fl.u.ip4;
+        rt = ip_route_connect(fl4, usin->sin_addr.s_addr, saddr,
                               RT_CONN_FLAGS(sk), oif,
                               sk->sk_protocol,
                               inet->inet_sport, usin->sin_port, sk, true);
@@ -55,26 +58,30 @@ int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
                 err = PTR_ERR(rt);
                 if (err == -ENETUNREACH)
                         IP_INC_STATS_BH(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
-                return err;
+                goto out;
         }
 
         if ((rt->rt_flags & RTCF_BROADCAST) && !sock_flag(sk, SOCK_BROADCAST)) {
                 ip_rt_put(rt);
-                return -EACCES;
+                err = -EACCES;
+                goto out;
         }
         if (!inet->inet_saddr)
-                inet->inet_saddr = fl4.saddr;   /* Update source address */
+                inet->inet_saddr = fl4->saddr;  /* Update source address */
         if (!inet->inet_rcv_saddr) {
-                inet->inet_rcv_saddr = fl4.saddr;
+                inet->inet_rcv_saddr = fl4->saddr;
                 if (sk->sk_prot->rehash)
                         sk->sk_prot->rehash(sk);
         }
-        inet->inet_daddr = fl4.daddr;
+        inet->inet_daddr = fl4->daddr;
         inet->inet_dport = usin->sin_port;
         sk->sk_state = TCP_ESTABLISHED;
         inet->inet_id = jiffies;
 
         sk_dst_set(sk, &rt->dst);
-        return 0;
+        err = 0;
+out:
+        release_sock(sk);
+        return err;
 }
 EXPORT_SYMBOL(ip4_datagram_connect);