netfilter: Only allow sane values in nf_register_net_hook

This commit adds an upfront check for sane values to be passed when
registering a netfilter hook.  This will be used in a future patch for a
simplified hook list traversal.

Signed-off-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index c8faf8102394b6e70965d15dc2e3b95d3a7afcad..67b74287535dfbb7059b04a9e8d4b7b180b070c5 100644 (file)
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -89,6 +89,11 @@ int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
        struct nf_hook_entry *entry;
        struct nf_hook_ops *elem;
 
+       if (reg->pf == NFPROTO_NETDEV &&
+           (reg->hooknum != NF_NETDEV_INGRESS ||
+            !reg->dev || dev_net(reg->dev) != net))
+               return -EINVAL;
+
        entry = kmalloc(sizeof(*entry), GFP_KERNEL);
        if (!entry)
                return -ENOMEM;