genetlink: switch control commands to per-op policies

In preparation for adding a new attribute to CTRL_CMD_GETPOLICY
split the policies for getpolicy and getfamily apart.

This will cause a slight user-visible change in that dumping
the policies will switch from per family to per op, but
supposedly sniffer-type applications (which are the main use
case for policy dumping thus far) should support both, anyway.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netlink/genetlink.c

@@ -1016,7 +1016,7 @@ ctrl_build_mcgrp_msg(const struct genl_family *family,
 	return skb;
 }
 
-static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
+static const struct nla_policy ctrl_policy_family[] = {
 	[CTRL_ATTR_FAMILY_ID]	= { .type = NLA_U16 },
 	[CTRL_ATTR_FAMILY_NAME]	= { .type = NLA_NUL_STRING,
 				    .len = GENL_NAMSIZ - 1 },
@@ -1115,6 +1115,12 @@ struct ctrl_dump_policy_ctx {
 	u16 fam_id;
 };
 
+static const struct nla_policy ctrl_policy_policy[] = {
+	[CTRL_ATTR_FAMILY_ID]	= { .type = NLA_U16 },
+	[CTRL_ATTR_FAMILY_NAME]	= { .type = NLA_NUL_STRING,
+				    .len = GENL_NAMSIZ - 1 },
+};
+
 static int ctrl_dumppolicy_start(struct netlink_callback *cb)
 {
 	const struct genl_dumpit_info *info = genl_dumpit_info(cb);
@@ -1196,11 +1202,15 @@ static const struct genl_ops genl_ctrl_ops[] = {
 	{
 		.cmd		= CTRL_CMD_GETFAMILY,
 		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
+		.policy		= ctrl_policy_family,
+		.maxattr	= ARRAY_SIZE(ctrl_policy_family) - 1,
 		.doit		= ctrl_getfamily,
 		.dumpit		= ctrl_dumpfamily,
 	},
 	{
 		.cmd		= CTRL_CMD_GETPOLICY,
+		.policy		= ctrl_policy_policy,
+		.maxattr	= ARRAY_SIZE(ctrl_policy_policy) - 1,
 		.start		= ctrl_dumppolicy_start,
 		.dumpit		= ctrl_dumppolicy,
 		.done		= ctrl_dumppolicy_done,
@@ -1220,8 +1230,6 @@ static struct genl_family genl_ctrl __ro_after_init = {
 	.id = GENL_ID_CTRL,
 	.name = "nlctrl",
 	.version = 0x2,
-	.maxattr = CTRL_ATTR_MAX,
-	.policy = ctrl_policy,
 	.netnsok = true,
 };