net: nexthop: Add NHA_OP_FLAGS

JIRA: https://issues.redhat.com/browse/RHEL-59118

commit a207eab
Author: Petr Machata <petrm@nvidia.com>
Date:   Wed Mar 6 13:49:16 2024 +0100

    net: nexthop: Add NHA_OP_FLAGS

    In order to add per-nexthop statistics, but still not increase netlink
    message size for consumers that do not care about them, there needs to be a
    toggle through which the user indicates their desire to get the statistics.
    To that end, add a new attribute, NHA_OP_FLAGS. The idea is to be able to
    use the attribute for carrying of arbitrary operation-specific flags, i.e.
    not make it specific for get / dump.

    Add the new attribute to get and dump policies, but do not actually allow
    any flags yet -- those will come later as the flags themselves are defined.
    Add the necessary parsing code.

    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>

Signed-off-by: Ivan Vecera <ivecera@redhat.com>

Author: ivecera

include/uapi/linux/nexthop.h

@@ -60,6 +60,9 @@ enum {
 	/* nested; nexthop bucket attributes */
 	NHA_RES_BUCKET,
 
+	/* u32; operation-specific flags */
+	NHA_OP_FLAGS,
+
 	__NHA_MAX,
 };
 

net/ipv4/nexthop.c

@@ -41,6 +41,7 @@ static const struct nla_policy rtm_nh_policy_new[] = {
 
 static const struct nla_policy rtm_nh_policy_get[] = {
 	[NHA_ID]		= { .type = NLA_U32 },
+	[NHA_OP_FLAGS]		= NLA_POLICY_MASK(NLA_U32, 0),
 };
 
 static const struct nla_policy rtm_nh_policy_del[] = {
@@ -52,6 +53,7 @@ static const struct nla_policy rtm_nh_policy_dump[] = {
 	[NHA_GROUPS]		= { .type = NLA_FLAG },
 	[NHA_MASTER]		= { .type = NLA_U32 },
 	[NHA_FDB]		= { .type = NLA_FLAG },
+	[NHA_OP_FLAGS]		= NLA_POLICY_MASK(NLA_U32, 0),
 };
 
 static const struct nla_policy rtm_nh_res_policy_new[] = {
@@ -2969,7 +2971,7 @@ static int rtm_new_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
 }
 
 static int nh_valid_get_del_req(const struct nlmsghdr *nlh,
-				struct nlattr **tb, u32 *id,
+				struct nlattr **tb, u32 *id, u32 *op_flags,
 				struct netlink_ext_ack *extack)
 {
 	struct nhmsg *nhm = nlmsg_data(nlh);
@@ -2990,6 +2992,11 @@ static int nh_valid_get_del_req(const struct nlmsghdr *nlh,
 		return -EINVAL;
 	}
 
+	if (tb[NHA_OP_FLAGS])
+		*op_flags = nla_get_u32(tb[NHA_OP_FLAGS]);
+	else
+		*op_flags = 0;
+
 	return 0;
 }
 
@@ -3005,6 +3012,7 @@ static int rtm_del_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
 		.portid = NETLINK_CB(skb).portid,
 	};
 	struct nexthop *nh;
+	u32 op_flags;
 	int err;
 	u32 id;
 
@@ -3013,7 +3021,7 @@ static int rtm_del_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (err < 0)
 		return err;
 
-	err = nh_valid_get_del_req(nlh, tb, &id, extack);
+	err = nh_valid_get_del_req(nlh, tb, &id, &op_flags, extack);
 	if (err)
 		return err;
 
@@ -3034,6 +3042,7 @@ static int rtm_get_nexthop(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 	struct nlattr *tb[NHA_MAX + 1];
 	struct sk_buff *skb = NULL;
 	struct nexthop *nh;
+	u32 op_flags;
 	int err;
 	u32 id;
 
@@ -3042,7 +3051,7 @@ static int rtm_get_nexthop(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 	if (err < 0)
 		return err;
 
-	err = nh_valid_get_del_req(nlh, tb, &id, extack);
+	err = nh_valid_get_del_req(nlh, tb, &id, &op_flags, extack);
 	if (err)
 		return err;
 
@@ -3078,6 +3087,7 @@ struct nh_dump_filter {
 	bool group_filter;
 	bool fdb_filter;
 	u32 res_bucket_nh_id;
+	u32 op_flags;
 };
 
 static bool nh_dump_filtered(struct nexthop *nh,
@@ -3149,6 +3159,11 @@ static int __nh_valid_dump_req(const struct nlmsghdr *nlh, struct nlattr **tb,
 		return -EINVAL;
 	}
 
+	if (tb[NHA_OP_FLAGS])
+		filter->op_flags = nla_get_u32(tb[NHA_OP_FLAGS]);
+	else
+		filter->op_flags = 0;
+
 	return 0;
 }
 
@@ -3478,14 +3493,15 @@ static int nh_valid_get_bucket_req(const struct nlmsghdr *nlh,
 				   struct netlink_ext_ack *extack)
 {
 	struct nlattr *tb[NHA_MAX + 1];
+	u32 op_flags;
 	int err;
 
 	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, &op_flags, extack);
 	if (err)
 		return err;