netdev - [PATCH net 1/3] ipv4: Return error for RTA

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Message-Id: <20190226170004.4535-2-dsahern@kernel.org>
Date:   Tue, 26 Feb 2019 09:00:02 -0800
From:   David Ahern <dsahern@...nel.org>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, David Ahern <dsahern@...il.com>
Subject: [PATCH net 1/3] ipv4: Return error for RTA_VIA attribute

From: David Ahern <dsahern@...il.com>

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@...il.com>
---
 net/ipv4/fib_frontend.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index fe4f6a624238..ed14ec245584 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -710,6 +710,10 @@ static int rtm_to_fib_config(struct net *net, struct sk_buff *skb,
 		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;
-- 
2.11.0