[PATCH 4.20 51/76] ipv4: Return error for RTA_VIA attribute

Greg Kroah-Hartman
2019-03-08T12:55:51Z

From: David Ahern <dsahern@gmail.com>

[ Upstream commit b6e9e5df4ecf100f6a10ab2ade8e46d47a4b9779 ]

IPv4 currently does not support nexthops outside of the AF_INET family.
Specifically, it does not handle RTA_VIA attribute. If it is passed
in a route add request, the actual route added only uses the device
which is clearly not what the user intended:

$ ip ro add 172.16.1.0/24 via inet6 2001:db8:1::1 dev eth0
$ ip ro ls
...
172.16.1.0/24 dev eth0

Catch this and fail the route add:
$ ip ro add 172.16.1.0/24 via inet6 2001:db8:1::1 dev eth0
Error: IPv4 does not support RTA_VIA attribute.

Fixes: 03c0566542f4c ("mpls: Netlink commands to add, remove, and dump routes")
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/fib_frontend.c | 4 ++++
1 file changed, 4 insertions(+)

--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -710,6 +710,10 @@ static int rtm_to_fib_config(struct net
case RTA_GATEWAY:
cfg->fc_gw = nla_get_be32(attr);
break;
+ case RTA_VIA:
+ NL_SET_ERR_MSG(extack, "IPv4 does not support RTA_VIA attribute");
+ err = -EINVAL;
+ goto errout;
case RTA_PRIORITY:
cfg->fc_priority = nla_get_u32(attr);
break;