[NETFILTER]: xt_tables: add centralized error checking

Introduce new functions for common match/target checks (private data
size, valid hooks, valid tables and valid protocols) to get more consistent
error reporting and to avoid each module duplicating them.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 4 deletions

diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h
index 6500d4e59d46..b9c37e1e6730 100644
--- a/include/linux/netfilter/x_tables.h
+++ b/include/linux/netfilter/x_tables.h
@@ -92,8 +92,6 @@ struct xt_match
 
         const char name[XT_FUNCTION_MAXNAMELEN-1];
 
-        u_int8_t revision;
-
         /* Return true or false: return FALSE and set *hotdrop = 1 to
            force immediate packet drop. */
         /* Arguments changed since 2.6.9, as this must now handle
@@ -120,6 +118,12 @@ struct xt_match
 
         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
         struct module *me;
+
+        char *table;
+        unsigned int matchsize;
+        unsigned int hooks;
+        unsigned short proto;
+        u_int8_t revision;
 };
 
 /* Registration hooks for targets. */
@@ -129,8 +133,6 @@ struct xt_target
 
         const char name[XT_FUNCTION_MAXNAMELEN-1];
 
-        u_int8_t revision;
-
         /* Returns verdict. Argument order changed since 2.6.9, as this
            must now handle non-linear skbs, using skb_copy_bits and
            skb_ip_make_writable. */
@@ -156,6 +158,12 @@ struct xt_target
 
         /* Set this to THIS_MODULE if you are a module, otherwise NULL */
         struct module *me;
+
+        char *table;
+        unsigned int targetsize;
+        unsigned int hooks;
+        unsigned short proto;
+        u_int8_t revision;
 };
 
 /* Furniture shopping... */
@@ -207,6 +215,13 @@ extern void xt_unregister_target(int af, struct xt_target *target);
 extern int xt_register_match(int af, struct xt_match *target);
 extern void xt_unregister_match(int af, struct xt_match *target);
 
+extern int xt_check_match(const struct xt_match *match, unsigned short family,
+                          unsigned int size, const char *table, unsigned int hook,
+                          unsigned short proto, int inv_proto);
+extern int xt_check_target(const struct xt_target *target, unsigned short family,
+                           unsigned int size, const char *table, unsigned int hook,
+                           unsigned short proto, int inv_proto);
+
 extern int xt_register_table(struct xt_table *table,
                              struct xt_table_info *bootstrap,
                              struct xt_table_info *newinfo);