[PATCH] extensions: libxt_cgroup: Add translation to nft

[Shivani Bhardwaj <shivanib134@gmail.com>]

Add translation for the network classifier cgroup to nftables.

Examples:

$ sudo iptables-translate -A input -m cgroup --cgroup 0x100001 -j DROP
nft add rule ip filter input meta cgroup 1048577 counter drop

$ sudo iptables-translate -A input -m cgroup ! --cgroup 0x100001 -j DROP
nft add rule ip filter input meta cgroup != 1048577 counter drop

Signed-off-by: Shivani Bhardwaj <shivanib134@gmail.com>
---
 extensions/libxt_cgroup.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/extensions/libxt_cgroup.c b/extensions/libxt_cgroup.c
index e304e33..dea1417 100644
--- a/extensions/libxt_cgroup.c
+++ b/extensions/libxt_cgroup.c
@@ -48,6 +48,17 @@ static void cgroup_save(const void *ip, const struct xt_entry_match *match)
 	printf("%s --cgroup %u", info->invert ? " !" : "", info->id);
 }
 
+static int cgroup_xlate(const struct xt_entry_match *match,
+			struct xt_buf *buf, int numeric)
+{
+	const struct xt_cgroup_info *info = (void *) match->data;
+
+	xt_buf_add(buf, "meta cgroup%s %u ",
+		   info->invert ? " !=" : "", info->id);
+
+	return 1;
+}
+
 static struct xtables_match cgroup_match = {
 	.family		= NFPROTO_UNSPEC,
 	.name		= "cgroup",
@@ -59,6 +70,7 @@ static struct xtables_match cgroup_match = {
 	.save		= cgroup_save,
 	.x6_parse	= cgroup_parse,
 	.x6_options	= cgroup_opts,
+	.xlate		= cgroup_xlate,
 };
 
 void _init(void)
-- 
1.9.1