[PATCH net] net/ipv6: Reinstate ping/traceroute use with source address in VRF

[Mike Manning <mmanning@vyatta.att-mail.com>]

Since the commit 1893ff20275b ("net/ipv6: Add l3mdev check to
ipv6_chk_addr_and_flags"), traceroute using TCP SYN or ICMP ECHO option
and ping fail when specifying a source address typically on a loopback
/dummy interface in the same VRF, e.g.:

    # ip vrf exec vrfgreen ping 3000::1 -I 2222::2
    ping: bind icmp socket: Cannot assign requested address
    # ip vrf exec vrfgreen traceroute 3000::1 -s 2222::2 -T
    bind: Cannot assign requested address

IPv6 traceroute using default UDP and IPv4 ping & traceroute continue
to work inside a VRF using a source address.

The reason is that the source address is provided via bind without a
device given by these applications in this case. The call to
ipv6_check_addr() in rawv6_bind() returns false as the default VRF is
assumed if no dev was given, but the src addr is in a non-default VRF.

The solution is to check that the address exists in the L3 domain that
the dev is part of only if the dev has been specified.

Signed-off-by: Mike Manning <mmanning@vyatta.att-mail.com>
---
 net/ipv6/addrconf.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index f96d1de79509..3963306ec27f 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1908,6 +1908,7 @@ int ipv6_chk_addr_and_flags(struct net *net, const struct in6_addr *addr,
 			    int strict, u32 banned_flags)
 {
 	unsigned int hash = inet6_addr_hash(net, addr);
+	const struct net_device *orig_dev = dev;
 	const struct net_device *l3mdev;
 	struct inet6_ifaddr *ifp;
 	u32 ifp_flags;
@@ -1922,7 +1923,7 @@ int ipv6_chk_addr_and_flags(struct net *net, const struct in6_addr *addr,
 		if (!net_eq(dev_net(ifp->idev->dev), net))
 			continue;
 
-		if (l3mdev_master_dev_rcu(ifp->idev->dev) != l3mdev)
+		if (orig_dev && l3mdev_master_dev_rcu(ifp->idev->dev) != l3mdev)
 			continue;
 
 		/* Decouple optimistic from tentative for evaluation here.
-- 
2.11.0