net: Propagate lookup failure in l3mdev_get_saddr to caller

Commands run in a vrf context are not failing as expected on a route lookup:
    root@kenny:~# ip ro ls table vrf-red
    unreachable default

    root@kenny:~# ping -I vrf-red -c1 -w1 10.100.1.254
    ping: Warning: source address might be selected on device other than vrf-red.
    PING 10.100.1.254 (10.100.1.254) from 0.0.0.0 vrf-red: 56(84) bytes of data.

    --- 10.100.1.254 ping statistics ---
    2 packets transmitted, 0 received, 100% packet loss, time 999ms

Since the vrf table does not have a route for 10.100.1.254 the ping
should have failed. The saddr lookup causes a full VRF table lookup.
Propogating a lookup failure to the user allows the command to fail as
expected:

    root@kenny:~# ping -I vrf-red -c1 -w1 10.100.1.254
    connect: No route to host

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

1 files changed, 5 insertions, 2 deletions

diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 63e5be0abd86..bc35f1842512 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -601,8 +601,11 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
                             (inet->hdrincl ? FLOWI_FLAG_KNOWN_NH : 0),
                            daddr, saddr, 0, 0);
 
-        if (!saddr && ipc.oif)
-                l3mdev_get_saddr(net, ipc.oif, &fl4);
+        if (!saddr && ipc.oif) {
+                err = l3mdev_get_saddr(net, ipc.oif, &fl4);
+                if (err < 0)
+                        goto done;
+        }
 
         if (!inet->hdrincl) {
                 rfv.msg = msg;