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, 6 insertions, 25 deletions

diff --git a/net/netfilter/xt_string.c b/net/netfilter/xt_string.c
index 501697183774..18d8884e7370 100644
--- a/net/netfilter/xt_string.c
+++ b/net/netfilter/xt_string.c
@@ -81,11 +81,11 @@ static void string_mt_destroy(const struct xt_match *match, void *matchinfo)
 	textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config);
 }
 
-static struct xt_match string_mt_reg[] __read_mostly = {
+static struct xt_match xt_string_mt_reg[] __read_mostly = {
 	{
 		.name 		= "string",
 		.revision	= 0,
-		.family		= NFPROTO_IPV4,
+		.family		= NFPROTO_UNSPEC,
 		.checkentry	= string_mt_check,
 		.match 		= string_mt,
 		.destroy 	= string_mt_destroy,
@@ -95,27 +95,7 @@ static struct xt_match string_mt_reg[] __read_mostly = {
 	{
 		.name 		= "string",
 		.revision	= 1,
-		.family		= NFPROTO_IPV4,
-		.checkentry	= string_mt_check,
-		.match 		= string_mt,
-		.destroy 	= string_mt_destroy,
-		.matchsize	= sizeof(struct xt_string_info),
-		.me 		= THIS_MODULE
-	},
-	{
-		.name 		= "string",
-		.revision	= 0,
-		.family		= NFPROTO_IPV6,
-		.checkentry	= string_mt_check,
-		.match 		= string_mt,
-		.destroy 	= string_mt_destroy,
-		.matchsize	= sizeof(struct xt_string_info),
-		.me 		= THIS_MODULE
-	},
-	{
-		.name 		= "string",
-		.revision	= 1,
-		.family		= NFPROTO_IPV6,
+		.family		= NFPROTO_UNSPEC,
 		.checkentry	= string_mt_check,
 		.match 		= string_mt,
 		.destroy 	= string_mt_destroy,
@@ -126,12 +106,13 @@ static struct xt_match string_mt_reg[] __read_mostly = {
 
 static int __init string_mt_init(void)
 {
-	return xt_register_matches(string_mt_reg, ARRAY_SIZE(string_mt_reg));
+	return xt_register_matches(xt_string_mt_reg,
+				   ARRAY_SIZE(xt_string_mt_reg));
 }
 
 static void __exit string_mt_exit(void)
 {
-	xt_unregister_matches(string_mt_reg, ARRAY_SIZE(string_mt_reg));
+	xt_unregister_matches(xt_string_mt_reg, ARRAY_SIZE(xt_string_mt_reg));
 }
 
 module_init(string_mt_init);