netfilter: xt_physdev: Fix spurious error message in physdev_mt_check

Simplify the check in physdev_mt_check() to emit an error message
only when passed an invalid chain (ie, NF_INET_LOCAL_OUT).
This avoids cluttering up the log with errors against valid rules.

For large/heavily modified rulesets, current behavior can quickly
overwhelm the ring buffer, because this function gets called on
every change, regardless of the rule that was changed.
Signed-off-by: Todd Seidelmann <tseidelmann@linode.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/xt_physdev.c

@@ -101,11 +101,9 @@ static int physdev_mt_check(const struct xt_mtchk_param *par)
 	if (info->bitmask & (XT_PHYSDEV_OP_OUT | XT_PHYSDEV_OP_ISOUT) &&
 	    (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) ||
 	     info->invert & XT_PHYSDEV_OP_BRIDGED) &&
-	    par->hook_mask & ((1 << NF_INET_LOCAL_OUT) |
-	    (1 << NF_INET_FORWARD) | (1 << NF_INET_POST_ROUTING))) {
+	    par->hook_mask & (1 << NF_INET_LOCAL_OUT)) {
 		pr_info_ratelimited("--physdev-out and --physdev-is-out only supported in the FORWARD and POSTROUTING chains with bridged traffic\n");
-		if (par->hook_mask & (1 << NF_INET_LOCAL_OUT))
-			return -EINVAL;
+		return -EINVAL;
 	}
 
 	if (!brnf_probed) {