diff options
| author | hannes@stressinduktion.org <hannes@stressinduktion.org> | 2015-04-01 17:07:44 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-04-06 16:12:49 -0400 |
| commit | f60e5990d9c1424af9dbca60a23ba2a1c7c1ce90 (patch) | |
| tree | bba5ed057073e42c0113473e1cdbff0bc46ab875 /net | |
| parent | 576b7cd2f6ff1e90b3fc0a000d2fe74f8a50a4bb (diff) | |
| download | linux-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 'net')
| -rw-r--r-- | net/core/dev.c | 4 | ||||
| -rw-r--r-- | net/core/sock.c | 19 | ||||
| -rw-r--r-- | net/ipv6/ip6_output.c | 3 |
3 files changed, 24 insertions, 2 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 962ee9d71964..45109b70664e 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2848,7 +2848,9 @@ static void skb_update_prio(struct sk_buff *skb) #define skb_update_prio(skb) #endif -static DEFINE_PER_CPU(int, xmit_recursion); +DEFINE_PER_CPU(int, xmit_recursion); +EXPORT_SYMBOL(xmit_recursion); + #define RECURSION_LIMIT 10 /** diff --git a/net/core/sock.c b/net/core/sock.c index 78e89eb7eb70..71e3e5f1eaa0 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -653,6 +653,25 @@ static inline void sock_valbool_flag(struct sock *sk, int bit, int valbool) sock_reset_flag(sk, bit); } +bool sk_mc_loop(struct sock *sk) +{ + if (dev_recursion_level()) + return false; + if (!sk) + return true; + 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 true; +} +EXPORT_SYMBOL(sk_mc_loop); + /* * This is meant for all protocols to use and covers goings on * at the socket level. Everything here is generic. diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 7e80b61b51ff..36cf0ab685a0 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -542,7 +542,8 @@ int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) { struct sk_buff *frag; struct rt6_info *rt = (struct rt6_info *)skb_dst(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; struct ipv6hdr *tmp_hdr; struct frag_hdr *fh; unsigned int mtu, hlen, left, len; |