netdev - [PATCH] IPv6: Allow the MTU of ipip6 tunnel to be set below 1280

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1380207108-20030-1-git-send-email-oghorbell@gmail.com>
Date:	Thu, 26 Sep 2013 15:51:48 +0100
From:	Oussama Ghorbel <oghorbell@...il.com>
To:	"David S. Miller" <davem@...emloft.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Oussama Ghorbel <oghorbell@...il.com>
Subject: [PATCH] IPv6: Allow the MTU of ipip6 tunnel to be set below 1280

The (inner) MTU of a ipip6 (IPv4-in-IPv6) tunnel cannot be set below 1280, which is the minimum MTU in IPv6.
However, there should be no IPv6 on the tunnel interface at all, so the IPv6 rules should not apply.
More info at https://bugzilla.kernel.org/show_bug.cgi?id=15530

This patch allows to check the minimum MTU for ipv6 tunnel according to these rules:
 -In case the tunnel is configured with ipip6 mode the minimum MTU is 68.
 -In case the tunnel is configured with ip6ip6 or any mode the minimum MTU is 1280.

Signed-off-by: Oussama Ghorbel <oghorbell@...il.com>
---
 net/ipv6/ip6_tunnel.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 1e55866..a66ead2 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -1423,8 +1423,14 @@ ip6_tnl_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 static int
 ip6_tnl_change_mtu(struct net_device *dev, int new_mtu)
 {
-	if (new_mtu < IPV6_MIN_MTU) {
-		return -EINVAL;
+	struct ip6_tnl *t = netdev_priv(dev);
+
+	if (t->parms.proto == IPPROTO_IPIP) {
+		if (new_mtu < 68)
+			return -EINVAL;
+	} else {
+		if (new_mtu < IPV6_MIN_MTU)
+			return -EINVAL;
 	}
 	dev->mtu = new_mtu;
 	return 0;
-- 
1.7.9.5

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html