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authorhannes@stressinduktion.org <hannes@stressinduktion.org>2015-04-01 18:07:44 +0300
committerDavid S. Miller <davem@davemloft.net>2015-04-06 23:12:49 +0300
commitf60e5990d9c1424af9dbca60a23ba2a1c7c1ce90 (patch)
treebba5ed057073e42c0113473e1cdbff0bc46ab875 /include/linux/netdevice.h
parent576b7cd2f6ff1e90b3fc0a000d2fe74f8a50a4bb (diff)
downloadlinux-f60e5990d9c1424af9dbca60a23ba2a1c7c1ce90.tar.xz
ipv6: protect skb->sk accesses from recursive dereference inside the stack
We should not consult skb->sk for output decisions in xmit recursion levels > 0 in the stack. Otherwise local socket settings could influence the result of e.g. tunnel encapsulation process. ipv6 does not conform with this in three places: 1) ip6_fragment: we do consult ipv6_npinfo for frag_size 2) sk_mc_loop in ipv6 uses skb->sk and checks if we should loop the packet back to the local socket 3) ip6_skb_dst_mtu could query the settings from the user socket and force a wrong MTU Furthermore: In sk_mc_loop we could potentially land in WARN_ON(1) if we use a PF_PACKET socket ontop of an IPv6-backed vxlan device. Reuse xmit_recursion as we are currently only interested in protecting tunnel devices. Cc: Jiri Pirko <jiri@resnulli.us> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/netdevice.h')
-rw-r--r--include/linux/netdevice.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index dcf6ec27739b..278738873703 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2185,6 +2185,12 @@ void netdev_freemem(struct net_device *dev);
void synchronize_net(void);
int init_dummy_netdev(struct net_device *dev);
+DECLARE_PER_CPU(int, xmit_recursion);
+static inline int dev_recursion_level(void)
+{
+ return this_cpu_read(xmit_recursion);
+}
+
struct net_device *dev_get_by_index(struct net *net, int ifindex);
struct net_device *__dev_get_by_index(struct net *net, int ifindex);
struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex);