udp: Handle VRF device in sendmsg

For unconnected UDP sockets using a VRF device lookup source address
based on VRF table. This allows the UDP header to be properly setup
before showing up at the VRF device via the dst.

Signed-off-by: Shrijeet Mukherjee <shm@cumulusnetworks.com>
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 1b8c5ba7d5f732ea2220ada929049c5c7cfd5e83..c0a15e7f359fe54e4edcffca5d59acb418dad116 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1013,11 +1013,31 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 
        if (!rt) {
                struct net *net = sock_net(sk);
+               __u8 flow_flags = inet_sk_flowi_flags(sk);
 
                fl4 = &fl4_stack;
+
+               /* unconnected socket. If output device is enslaved to a VRF
+                * device lookup source address from VRF table. This mimics
+                * behavior of ip_route_connect{_init}.
+                */
+               if (netif_index_is_vrf(net, ipc.oif)) {
+                       flowi4_init_output(fl4, ipc.oif, sk->sk_mark, tos,
+                                          RT_SCOPE_UNIVERSE, sk->sk_protocol,
+                                          (flow_flags | FLOWI_FLAG_VRFSRC),
+                                          faddr, saddr, dport,
+                                          inet->inet_sport);
+
+                       rt = ip_route_output_flow(net, fl4, sk);
+                       if (!IS_ERR(rt)) {
+                               saddr = fl4->saddr;
+                               ip_rt_put(rt);
+                       }
+               }
+
                flowi4_init_output(fl4, ipc.oif, sk->sk_mark, tos,
                                   RT_SCOPE_UNIVERSE, sk->sk_protocol,
-                                  inet_sk_flowi_flags(sk),
+                                  flow_flags,
                                   faddr, saddr, dport, inet->inet_sport);
 
                security_sk_classify_flow(sk, flowi4_to_flowi(fl4));