Commit f83a7ea2 authored by Florian Westphal's avatar Florian Westphal Committed by Pablo Neira Ayuso

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: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 5add189a
...@@ -66,6 +66,12 @@ static bool rpfilter_lookup_reverse(struct flowi4 *fl4, ...@@ -66,6 +66,12 @@ static bool rpfilter_lookup_reverse(struct flowi4 *fl4,
return dev_match; return dev_match;
} }
static bool rpfilter_is_local(const struct sk_buff *skb)
{
const struct rtable *rt = skb_rtable(skb);
return rt && (rt->rt_flags & RTCF_LOCAL);
}
static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par) static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par)
{ {
const struct xt_rpfilter_info *info; const struct xt_rpfilter_info *info;
...@@ -76,7 +82,7 @@ static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par) ...@@ -76,7 +82,7 @@ static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par)
info = par->matchinfo; info = par->matchinfo;
invert = info->flags & XT_RPFILTER_INVERT; invert = info->flags & XT_RPFILTER_INVERT;
if (par->in->flags & IFF_LOOPBACK) if (rpfilter_is_local(skb))
return true ^ invert; return true ^ invert;
iph = ip_hdr(skb); iph = ip_hdr(skb);
......
...@@ -71,6 +71,12 @@ static bool rpfilter_lookup_reverse6(const struct sk_buff *skb, ...@@ -71,6 +71,12 @@ static bool rpfilter_lookup_reverse6(const struct sk_buff *skb,
return ret; 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) static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par)
{ {
const struct xt_rpfilter_info *info = par->matchinfo; const struct xt_rpfilter_info *info = par->matchinfo;
...@@ -78,7 +84,7 @@ static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par) ...@@ -78,7 +84,7 @@ static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par)
struct ipv6hdr *iph; struct ipv6hdr *iph;
bool invert = info->flags & XT_RPFILTER_INVERT; bool invert = info->flags & XT_RPFILTER_INVERT;
if (par->in->flags & IFF_LOOPBACK) if (rpfilter_is_local(skb))
return true ^ invert; return true ^ invert;
iph = ipv6_hdr(skb); iph = ipv6_hdr(skb);
......
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