netfilter: xt_rpfilter: skip locally generated broadcast/multicast, too
Alex Efros reported rpfilter module doesn't match following packets:
IN=br.qemu SRC=192.168.2.1 DST=192.168.2.255 [ .. ]
(netfilter bugzilla #814).
Problem is that network stack arranges for the locally generated broadcasts
to appear on the interface they were sent out, so the IFF_LOOPBACK check
doesn't trigger.
As -m rpfilter is restricted to PREROUTING, we can check for existing
rtable instead, it catches locally-generated broad/multicast case, too.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/ipv6/netfilter/ip6t_rpfilter.c b/net/ipv6/netfilter/ip6t_rpfilter.c
index 5060d54..e0983f3 100644
--- a/net/ipv6/netfilter/ip6t_rpfilter.c
+++ b/net/ipv6/netfilter/ip6t_rpfilter.c
@@ -71,6 +71,12 @@
return ret;
}
+static bool rpfilter_is_local(const struct sk_buff *skb)
+{
+ const struct rt6_info *rt = (const void *) skb_dst(skb);
+ return rt && (rt->rt6i_flags & RTF_LOCAL);
+}
+
static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_rpfilter_info *info = par->matchinfo;
@@ -78,7 +84,7 @@
struct ipv6hdr *iph;
bool invert = info->flags & XT_RPFILTER_INVERT;
- if (par->in->flags & IFF_LOOPBACK)
+ if (rpfilter_is_local(skb))
return true ^ invert;
iph = ipv6_hdr(skb);