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authorhannes@stressinduktion.org <hannes@stressinduktion.org>2015-04-01 17:07:44 +0200
committerDavid S. Miller <davem@davemloft.net>2015-04-06 16:12:49 -0400
commitf60e5990d9c1424af9dbca60a23ba2a1c7c1ce90 (patch)
treebba5ed057073e42c0113473e1cdbff0bc46ab875 /include
parent576b7cd2f6ff1e90b3fc0a000d2fe74f8a50a4bb (diff)
downloadlinux-f60e5990d9c1424af9dbca60a23ba2a1c7c1ce90.tar.bz2
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')
-rw-r--r--include/linux/netdevice.h6
-rw-r--r--include/net/ip.h16
-rw-r--r--include/net/ip6_route.h3
-rw-r--r--include/net/sock.h2
4 files changed, 10 insertions, 17 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);
diff --git a/include/net/ip.h b/include/net/ip.h
index 025c61c0dffb..6cc1eafb153a 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -453,22 +453,6 @@ static __inline__ void inet_reset_saddr(struct sock *sk)
#endif
-static inline int sk_mc_loop(struct sock *sk)
-{
- if (!sk)
- return 1;
- switch (sk->sk_family) {
- case AF_INET:
- return inet_sk(sk)->mc_loop;
-#if IS_ENABLED(CONFIG_IPV6)
- case AF_INET6:
- return inet6_sk(sk)->mc_loop;
-#endif
- }
- WARN_ON(1);
- return 1;
-}
-
bool ip_call_ra_chain(struct sk_buff *skb);
/*
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 1d09b46c1e48..eda131d179d9 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -174,7 +174,8 @@ int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *));
static inline int ip6_skb_dst_mtu(struct sk_buff *skb)
{
- struct ipv6_pinfo *np = skb->sk ? inet6_sk(skb->sk) : NULL;
+ struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ?
+ inet6_sk(skb->sk) : NULL;
return (np && np->pmtudisc >= IPV6_PMTUDISC_PROBE) ?
skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb));
diff --git a/include/net/sock.h b/include/net/sock.h
index ab186b1d31ff..e4079c28e6b8 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1762,6 +1762,8 @@ struct dst_entry *__sk_dst_check(struct sock *sk, u32 cookie);
struct dst_entry *sk_dst_check(struct sock *sk, u32 cookie);
+bool sk_mc_loop(struct sock *sk);
+
static inline bool sk_can_gso(const struct sock *sk)
{
return net_gso_ok(sk->sk_route_caps, sk->sk_gso_type);