nexthop: Specialize rtm_nh_policy

This policy is currently only used for creation of new next hops and new
next hop groups. Rename it accordingly and remove the two attributes that
are not valid in that context: NHA_GROUPS and NHA_MASTER.

For consistency with other policies, do not mention policy array size in
the declarator, and replace NHA_MAX for ARRAY_SIZE as appropriate.

Note that with this commit, NHA_MAX and __NHA_MAX are not used anymore.
Leave them in purely as a user API.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/ipv4/nexthop.c

@@ -22,7 +22,7 @@ static void remove_nexthop(struct net *net, struct nexthop *nh,
 #define NH_DEV_HASHBITS  8
 #define NH_DEV_HASHSIZE (1U << NH_DEV_HASHBITS)
 
-static const struct nla_policy rtm_nh_policy[NHA_MAX + 1] = {
+static const struct nla_policy rtm_nh_policy_new[] = {
 	[NHA_ID]		= { .type = NLA_U32 },
 	[NHA_GROUP]		= { .type = NLA_BINARY },
 	[NHA_GROUP_TYPE]	= { .type = NLA_U16 },
@@ -31,8 +31,6 @@ static const struct nla_policy rtm_nh_policy[NHA_MAX + 1] = {
 	[NHA_GATEWAY]		= { .type = NLA_BINARY },
 	[NHA_ENCAP_TYPE]	= { .type = NLA_U16 },
 	[NHA_ENCAP]		= { .type = NLA_NESTED },
-	[NHA_GROUPS]		= { .type = NLA_FLAG },
-	[NHA_MASTER]		= { .type = NLA_U32 },
 	[NHA_FDB]		= { .type = NLA_FLAG },
 };
 
@@ -576,7 +574,8 @@ static int nh_check_attr_fdb_group(struct nexthop *nh, u8 *nh_family,
 	return 0;
 }
 
-static int nh_check_attr_group(struct net *net, struct nlattr *tb[],
+static int nh_check_attr_group(struct net *net,
+			       struct nlattr *tb[], size_t tb_size,
 			       struct netlink_ext_ack *extack)
 {
 	unsigned int len = nla_len(tb[NHA_GROUP]);
@@ -635,7 +634,7 @@ static int nh_check_attr_group(struct net *net, struct nlattr *tb[],
 			return -EINVAL;
 		}
 	}
-	for (i = NHA_GROUP_TYPE + 1; i < __NHA_MAX; ++i) {
+	for (i = NHA_GROUP_TYPE + 1; i < tb_size; ++i) {
 		if (!tb[i])
 			continue;
 		if (i == NHA_FDB)
@@ -1654,11 +1653,12 @@ static int rtm_to_nh_config(struct net *net, struct sk_buff *skb,
 			    struct netlink_ext_ack *extack)
 {
 	struct nhmsg *nhm = nlmsg_data(nlh);
-	struct nlattr *tb[NHA_MAX + 1];
+	struct nlattr *tb[ARRAY_SIZE(rtm_nh_policy_new)];
 	int err;
 
-	err = nlmsg_parse(nlh, sizeof(*nhm), tb, NHA_MAX, rtm_nh_policy,
-			  extack);
+	err = nlmsg_parse(nlh, sizeof(*nhm), tb,
+			  ARRAY_SIZE(rtm_nh_policy_new) - 1,
+			  rtm_nh_policy_new, extack);
 	if (err < 0)
 		return err;
 
@@ -1685,11 +1685,6 @@ static int rtm_to_nh_config(struct net *net, struct sk_buff *skb,
 		goto out;
 	}
 
-	if (tb[NHA_GROUPS] || tb[NHA_MASTER]) {
-		NL_SET_ERR_MSG(extack, "Invalid attributes in request");
-		goto out;
-	}
-
 	memset(cfg, 0, sizeof(*cfg));
 	cfg->nlflags = nlh->nlmsg_flags;
 	cfg->nlinfo.portid = NETLINK_CB(skb).portid;
@@ -1731,7 +1726,7 @@ static int rtm_to_nh_config(struct net *net, struct sk_buff *skb,
 			NL_SET_ERR_MSG(extack, "Invalid group type");
 			goto out;
 		}
-		err = nh_check_attr_group(net, tb, extack);
+		err = nh_check_attr_group(net, tb, ARRAY_SIZE(tb), extack);
 
 		/* no other attributes should be set */
 		goto out;