netfilter: xt_hashlimit: use _ALL macro to reject unknown flag bits

David Miller says:
     The canonical way to validate if the set bits are in a valid
     range is to have a "_ALL" macro, and test:
     if (val & ~XT_HASHLIMIT_ALL)
         goto err;"

make it so.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/linux/netfilter/xt_hashlimit.h

@@ -22,10 +22,12 @@ enum {
 	XT_HASHLIMIT_HASH_SPT = 1 << 3,
 	XT_HASHLIMIT_INVERT   = 1 << 4,
 	XT_HASHLIMIT_BYTES    = 1 << 5,
+};
 #ifdef __KERNEL__
-	XT_HASHLIMIT_MAX      = 1 << 6,
+#define XT_HASHLIMIT_ALL (XT_HASHLIMIT_HASH_DIP | XT_HASHLIMIT_HASH_DPT | \
+			  XT_HASHLIMIT_HASH_SIP | XT_HASHLIMIT_HASH_SPT | \
+			  XT_HASHLIMIT_INVERT | XT_HASHLIMIT_BYTES)
 #endif
-};
 
 struct hashlimit_cfg {
 	__u32 mode;	  /* bitmask of XT_HASHLIMIT_HASH_* */

net/netfilter/xt_hashlimit.c

@@ -647,7 +647,7 @@ static int hashlimit_mt_check(const struct xt_mtchk_param *par)
 			return -EINVAL;
 	}
 
-	if (info->cfg.mode >= XT_HASHLIMIT_MAX) {
+	if (info->cfg.mode & ~XT_HASHLIMIT_ALL) {
 		pr_info("Unknown mode mask %X, kernel too old?\n",
 						info->cfg.mode);
 		return -EINVAL;