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authorStefano Brivio <sbrivio@redhat.com>2018-03-15 17:16:28 +0100
committerSteffen Klassert <steffen.klassert@secunet.com>2018-03-19 08:45:50 +0100
commit24fc79798b8ddfd46f2dd363a8d29072c083b977 (patch)
tree8c037f94e733a5a9d1f312c59b7c2c0a1697ac39 /net/ipv4/ip_tunnel.c
parentvti4: Don't count header length twice on tunnel setup (diff)
downloadlinux-dev-24fc79798b8ddfd46f2dd363a8d29072c083b977.tar.xz
linux-dev-24fc79798b8ddfd46f2dd363a8d29072c083b977.zip
ip_tunnel: Clamp MTU to bounds on new link
Otherwise, it's possible to specify invalid MTU values directly on creation of a link (via 'ip link add'). This is already prevented on subsequent MTU changes by commit b96f9afee4eb ("ipv4/6: use core net MTU range checking"). Fixes: c54419321455 ("GRE: Refactor GRE tunneling code.") Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Acked-by: Sabrina Dubroca <sd@queasysnail.net> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Diffstat (limited to 'net/ipv4/ip_tunnel.c')
-rw-r--r--net/ipv4/ip_tunnel.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 6d21068f9b55..7c76dd17b6b9 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -1108,8 +1108,14 @@ int ip_tunnel_newlink(struct net_device *dev, struct nlattr *tb[],
eth_hw_addr_random(dev);
mtu = ip_tunnel_bind_dev(dev);
- if (!tb[IFLA_MTU])
+ if (tb[IFLA_MTU]) {
+ unsigned int max = 0xfff8 - dev->hard_header_len - nt->hlen;
+
+ dev->mtu = clamp(dev->mtu, (unsigned int)ETH_MIN_MTU,
+ (unsigned int)(max - sizeof(struct iphdr)));
+ } else {
dev->mtu = mtu;
+ }
ip_tunnel_add(itn, nt);
out: