net: nexthop: Adjust netlink policy parsing for a new attribute

A following patch will introduce a new attribute, op-specific flags to
adjust the behavior of an operation. Different operations will recognize
different flags.

- To make the differentiation possible, stop sharing the policies for get
  and del operations.

- To allow querying for presence of the attribute, have all the attribute
  arrays sized to NHA_MAX, regardless of what is permitted by policy, and
  pass the corresponding value to nlmsg_parse() as well.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/nexthop.c

@@ -43,6 +43,10 @@ static const struct nla_policy rtm_nh_policy_get[] = {
 	[NHA_ID]		= { .type = NLA_U32 },
 };
 
+static const struct nla_policy rtm_nh_policy_del[] = {
+	[NHA_ID]		= { .type = NLA_U32 },
+};
+
 static const struct nla_policy rtm_nh_policy_dump[] = {
 	[NHA_OIF]		= { .type = NLA_U32 },
 	[NHA_GROUPS]		= { .type = NLA_FLAG },
@@ -2966,9 +2970,9 @@ static int rtm_new_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
 	return err;
 }
 
-static int __nh_valid_get_del_req(const struct nlmsghdr *nlh,
-				  struct nlattr **tb, u32 *id,
-				  struct netlink_ext_ack *extack)
+static int nh_valid_get_del_req(const struct nlmsghdr *nlh,
+				struct nlattr **tb, u32 *id,
+				struct netlink_ext_ack *extack)
 {
 	struct nhmsg *nhm = nlmsg_data(nlh);
 
@@ -2991,26 +2995,12 @@ static int __nh_valid_get_del_req(const struct nlmsghdr *nlh,
 	return 0;
 }
 
-static int nh_valid_get_del_req(const struct nlmsghdr *nlh, u32 *id,
-				struct netlink_ext_ack *extack)
-{
-	struct nlattr *tb[ARRAY_SIZE(rtm_nh_policy_get)];
-	int err;
-
-	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb,
-			  ARRAY_SIZE(rtm_nh_policy_get) - 1,
-			  rtm_nh_policy_get, extack);
-	if (err < 0)
-		return err;
-
-	return __nh_valid_get_del_req(nlh, tb, id, extack);
-}
-
 /* rtnl */
 static int rtm_del_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
 			   struct netlink_ext_ack *extack)
 {
 	struct net *net = sock_net(skb->sk);
+	struct nlattr *tb[NHA_MAX + 1];
 	struct nl_info nlinfo = {
 		.nlh = nlh,
 		.nl_net = net,
@@ -3020,7 +3010,12 @@ static int rtm_del_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
 	int err;
 	u32 id;
 
-	err = nh_valid_get_del_req(nlh, &id, extack);
+	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb, NHA_MAX,
+			  rtm_nh_policy_del, extack);
+	if (err < 0)
+		return err;
+
+	err = nh_valid_get_del_req(nlh, tb, &id, extack);
 	if (err)
 		return err;
 
@@ -3038,12 +3033,18 @@ static int rtm_get_nexthop(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 			   struct netlink_ext_ack *extack)
 {
 	struct net *net = sock_net(in_skb->sk);
+	struct nlattr *tb[NHA_MAX + 1];
 	struct sk_buff *skb = NULL;
 	struct nexthop *nh;
 	int err;
 	u32 id;
 
-	err = nh_valid_get_del_req(nlh, &id, extack);
+	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb, NHA_MAX,
+			  rtm_nh_policy_get, extack);
+	if (err < 0)
+		return err;
+
+	err = nh_valid_get_del_req(nlh, tb, &id, extack);
 	if (err)
 		return err;
 
@@ -3157,11 +3158,10 @@ static int nh_valid_dump_req(const struct nlmsghdr *nlh,
 			     struct nh_dump_filter *filter,
 			     struct netlink_callback *cb)
 {
-	struct nlattr *tb[ARRAY_SIZE(rtm_nh_policy_dump)];
+	struct nlattr *tb[NHA_MAX + 1];
 	int err;
 
-	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb,
-			  ARRAY_SIZE(rtm_nh_policy_dump) - 1,
+	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb, NHA_MAX,
 			  rtm_nh_policy_dump, cb->extack);
 	if (err < 0)
 		return err;
@@ -3300,11 +3300,10 @@ static int nh_valid_dump_bucket_req(const struct nlmsghdr *nlh,
 				    struct netlink_callback *cb)
 {
 	struct nlattr *res_tb[ARRAY_SIZE(rtm_nh_res_bucket_policy_dump)];
-	struct nlattr *tb[ARRAY_SIZE(rtm_nh_policy_dump_bucket)];
+	struct nlattr *tb[NHA_MAX + 1];
 	int err;
 
-	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb,
-			  ARRAY_SIZE(rtm_nh_policy_dump_bucket) - 1,
+	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb, NHA_MAX,
 			  rtm_nh_policy_dump_bucket, NULL);
 	if (err < 0)
 		return err;
@@ -3474,16 +3473,15 @@ static int nh_valid_get_bucket_req(const struct nlmsghdr *nlh,
 				   u32 *id, u16 *bucket_index,
 				   struct netlink_ext_ack *extack)
 {
-	struct nlattr *tb[ARRAY_SIZE(rtm_nh_policy_get_bucket)];
+	struct nlattr *tb[NHA_MAX + 1];
 	int err;
 
-	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb,
-			  ARRAY_SIZE(rtm_nh_policy_get_bucket) - 1,
+	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb, NHA_MAX,
 			  rtm_nh_policy_get_bucket, extack);
 	if (err < 0)
 		return err;
 
-	err = __nh_valid_get_del_req(nlh, tb, id, extack);
+	err = nh_valid_get_del_req(nlh, tb, id, extack);
 	if (err)
 		return err;