From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: [PATCH 2/2] netfilter: xt_rpfilter: skip locally generated broadcast/multicast, too Date: Fri, 19 Apr 2013 03:16:02 +0200 Message-ID: <1366334162-4958-3-git-send-email-pablo@netfilter.org> References: <1366334162-4958-1-git-send-email-pablo@netfilter.org> Cc: davem@davemloft.net, netdev@vger.kernel.org To: netfilter-devel@vger.kernel.org Return-path: In-Reply-To: <1366334162-4958-1-git-send-email-pablo@netfilter.org> Sender: netfilter-devel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Florian Westphal 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 Signed-off-by: Pablo Neira Ayuso --- net/ipv4/netfilter/ipt_rpfilter.c | 8 +++++++- net/ipv6/netfilter/ip6t_rpfilter.c | 8 +++++++- 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/net/ipv4/netfilter/ipt_rpfilter.c b/net/ipv4/netfilter/ipt_rpfilter.c index c301300..c49dcd0 100644 --- a/net/ipv4/netfilter/ipt_rpfilter.c +++ b/net/ipv4/netfilter/ipt_rpfilter.c @@ -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); 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 @@ 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); -- 1.7.10.4