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netfilter: xt_rpfilter: skip locally generated broadcast/multicast, too

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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>
This commit is contained in:
Florian Westphal 2013-04-17 22:45:24 +00:00 committed by Pablo Neira Ayuso
parent 5add189a12
commit f83a7ea207
2 changed files with 14 additions and 2 deletions
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8
net/ipv4/netfilter/ipt_rpfilter.c
View File

@ -66,6 +66,12 @@ static bool rpfilter_lookup_reverse(struct flowi4 *fl4,
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)
{
const struct xt_rpfilter_info *info;
@ -76,7 +82,7 @@ static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par)
info = par->matchinfo;
invert = info->flags & XT_RPFILTER_INVERT;
if (par->in->flags & IFF_LOOPBACK)
if (rpfilter_is_local(skb))
return true ^ invert;
iph = ip_hdr(skb);

8
net/ipv6/netfilter/ip6t_rpfilter.c
View File

@ -71,6 +71,12 @@ static bool rpfilter_lookup_reverse6(const struct sk_buff *skb,
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 @@ static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par)
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);