netdev - [PATCH net] mpls: fix warning with multi-label encap

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Date:   Fri,  7 Jun 2019 11:49:41 +0100
From:   George Wilkie <gwilkie@...tta.att-mail.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org
Subject: [PATCH net] mpls: fix warning with multi-label encap

If you configure a route with multiple labels, e.g.
  ip route add 10.10.3.0/24 encap mpls 16/100 via 10.10.2.2 dev ens4
A warning is logged:
  kernel: [  130.561819] netlink: 'ip': attribute type 1 has an invalid
  length.

This happens because mpls_iptunnel_policy has set the type of
MPLS_IPTUNNEL_DST to fixed size NLA_U32.
Change it to a minimum size.
nla_get_labels() does the remaining validation.

Signed-off-by: George Wilkie <gwilkie@...tta.att-mail.com>
---
 net/mpls/mpls_iptunnel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mpls/mpls_iptunnel.c b/net/mpls/mpls_iptunnel.c
index 951b52d5835b..20c682143b01 100644
--- a/net/mpls/mpls_iptunnel.c
+++ b/net/mpls/mpls_iptunnel.c
@@ -28,7 +28,7 @@
 #include "internal.h"

 static const struct nla_policy mpls_iptunnel_policy[MPLS_IPTUNNEL_MAX + 1] = {
-	[MPLS_IPTUNNEL_DST]	= { .type = NLA_U32 },
+	[MPLS_IPTUNNEL_DST]	= { .len = sizeof(u32) },
 	[MPLS_IPTUNNEL_TTL]	= { .type = NLA_U8 },
 };

-- 
2.20.1