netfilter: x_tables: allow to use cgroup match for LOCAL_IN nf hooks

This simple modification allows iptables to work with INPUT chain
in combination with cgroup module. It could be useful for counting
ingress traffic per cgroup with nfacct netfilter module. There
were no problems to count the egress traffic that way formerly.

It's possible to get classified sk_buff after PREROUTING, due to
socket lookup being done in early_demux (tcp_v4_early_demux). Also
it works for udp as well.

Trivial usage example, assuming we're in the same shell every step
and we have enough permissions:

1) Classic net_cls cgroup initialization:

  mkdir /sys/fs/cgroup/net_cls
  mount -t cgroup -o net_cls net_cls /sys/fs/cgroup/net_cls

2) Set up cgroup for interesting application:

  mkdir /sys/fs/cgroup/net_cls/wget
  echo 1 > /sys/fs/cgroup/net_cls/wget/net_cls.classid
  echo $BASHPID > /sys/fs/cgroup/net_cls/wget/cgroup.procs

3) Create kernel counters:

  nfacct add wget-cgroup-in
  iptables -A INPUT -m cgroup ! --cgroup 1 -m nfacct --nfacct-name wget-cgroup-in

  nfacct add wget-cgroup-out
  iptables -A OUTPUT -m cgroup ! --cgroup 1 -m nfacct --nfacct-name wget-cgroup-out

4) Network usage:

  wget https://www.kernel.org/pub/linux/kernel/v3.x/testing/linux-3.14-rc6.tar.xz

5) Check results:

  nfacct list

Cgroup approach is being used for the DataUsage (counting & blocking
traffic) feature for Samsung's modification of the Tizen OS.

Signed-off-by: Alexey Perevalov <a.perevalov@samsung.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/xt_cgroup.c b/net/netfilter/xt_cgroup.c
index 9a8e77e7f8d42d4e3c7dd02d9c80b4a54311f5b0..f4e833005320fa7da4c0deb41bba272e8c54bd8e 100644 (file)
--- a/net/netfilter/xt_cgroup.c
+++ b/net/netfilter/xt_cgroup.c
@@ -54,7 +54,8 @@ static struct xt_match cgroup_mt_reg __read_mostly = {
        .matchsize  = sizeof(struct xt_cgroup_info),
        .me         = THIS_MODULE,
        .hooks      = (1 << NF_INET_LOCAL_OUT) |
-                     (1 << NF_INET_POST_ROUTING),
+                     (1 << NF_INET_POST_ROUTING) |
+                     (1 << NF_INET_LOCAL_IN),
 };
 
 static int __init cgroup_mt_init(void)