netdev - [PATCH net 5/6] ip6_tunnel: better validate user provided tunnel names

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Message-Id: <20180405133931.207634-6-edumazet@google.com>
Date:   Thu,  5 Apr 2018 06:39:30 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH net 5/6] ip6_tunnel: better validate user provided tunnel names

Use valid_name() to make sure user does not provide illegal
device name.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv6/ip6_tunnel.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index df4c29f7d59f030729b1158b809a10f4115d4bbf..da66aaac51cecbf933827c8842e61a8cbb4d274f 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -297,13 +297,16 @@ static struct ip6_tnl *ip6_tnl_create(struct net *net, struct __ip6_tnl_parm *p)
 	struct net_device *dev;
 	struct ip6_tnl *t;
 	char name[IFNAMSIZ];
-	int err = -ENOMEM;
+	int err = -E2BIG;
 
-	if (p->name[0])
+	if (p->name[0]) {
+		if (!dev_valid_name(p->name))
+			goto failed;
 		strlcpy(name, p->name, IFNAMSIZ);
-	else
+	} else {
 		sprintf(name, "ip6tnl%%d");
-
+	}
+	err = -ENOMEM;
 	dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN,
 			   ip6_tnl_dev_setup);
 	if (!dev)
-- 
2.17.0.484.g0c8726318c-goog