netfilter: implement NFPROTO_UNSPEC as a wildcard for extensions

When a match or target is looked up using xt_find_{match,target},
Xtables will also search the NFPROTO_UNSPEC module list. This allows
for protocol-independent extensions (like xt_time) to be reused from
other components (e.g. arptables, ebtables).

Extensions that take different codepaths depending on match->family
or target->family of course cannot use NFPROTO_UNSPEC within the
registration structure (e.g. xt_pkttype).

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 9 insertions, 17 deletions

diff --git a/net/netfilter/xt_u32.c b/net/netfilter/xt_u32.c
index ed9f83406112..a6b971dc5d38 100644
--- a/net/netfilter/xt_u32.c
+++ b/net/netfilter/xt_u32.c
@@ -99,31 +99,23 @@ u32_mt(const struct sk_buff *skb, const struct net_device *in,
 	return ret ^ data->invert;
 }
 
-static struct xt_match u32_mt_reg[] __read_mostly = {
-	{
-		.name       = "u32",
-		.family     = NFPROTO_IPV4,
-		.match      = u32_mt,
-		.matchsize  = sizeof(struct xt_u32),
-		.me         = THIS_MODULE,
-	},
-	{
-		.name       = "u32",
-		.family     = NFPROTO_IPV6,
-		.match      = u32_mt,
-		.matchsize  = sizeof(struct xt_u32),
-		.me         = THIS_MODULE,
-	},
+static struct xt_match xt_u32_mt_reg __read_mostly = {
+	.name       = "u32",
+	.revision   = 0,
+	.family     = NFPROTO_UNSPEC,
+	.match      = u32_mt,
+	.matchsize  = sizeof(struct xt_u32),
+	.me         = THIS_MODULE,
 };
 
 static int __init u32_mt_init(void)
 {
-	return xt_register_matches(u32_mt_reg, ARRAY_SIZE(u32_mt_reg));
+	return xt_register_match(&xt_u32_mt_reg);
 }
 
 static void __exit u32_mt_exit(void)
 {
-	xt_unregister_matches(u32_mt_reg, ARRAY_SIZE(u32_mt_reg));
+	xt_unregister_match(&xt_u32_mt_reg);
 }
 
 module_init(u32_mt_init);