[net-next,v3,2/7] net: nexthop: Add NHA_OP_FLAGS

Commit Message

Petr Machata March 4, 2024, 8:51 p.m. UTC

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 <[e-mail]>
Reviewed-by: David Ahern <[e-mail]>
---

Notes:
    v2:
    - Change OP_FLAGS to u32, enforce through NLA_POLICY_MASK

 include/uapi/linux/nexthop.h |  3 +++
 net/ipv4/nexthop.c           | 24 ++++++++++++++++++++----
 2 files changed, 23 insertions(+), 4 deletions(-)

Comments

Ido Schimmel March 5, 2024, 8:39 a.m. UTC | #1

On Mon, Mar 04, 2024 at 09:51:15PM +0100, Petr Machata wrote:
> @@ -2992,6 +2994,11 @@ 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;
>  }

[...]

> @@ -3151,6 +3161,11 @@ 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_bitfield32(tb[NHA_OP_FLAGS]).value;

Shouldn't this be:

filter->op_flags = nla_get_u32(tb[NHA_OP_FLAGS]);

?

> +	else
> +		filter->op_flags = 0;
> +
>  	return 0;
>  }

Petr Machata March 5, 2024, 10:42 a.m. UTC | #2

Ido Schimmel <[e-mail]> writes:

> On Mon, Mar 04, 2024 at 09:51:15PM +0100, Petr Machata wrote:
>> @@ -2992,6 +2994,11 @@ 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;
>>  }
>
> [...]
>
>> @@ -3151,6 +3161,11 @@ 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_bitfield32(tb[NHA_OP_FLAGS]).value;
>
> Shouldn't this be:
>
> filter->op_flags = nla_get_u32(tb[NHA_OP_FLAGS]);

D'oh, of course. I'm 99% sure I changed both instances, so I don't know
what happened. Ghosts :-/

Patch

diff --git a/include/uapi/linux/nexthop.h b/include/uapi/linux/nexthop.h
index d8ffa8c9ca78..086444e2946c 100644
--- a/include/uapi/linux/nexthop.h
+++ b/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,
 };
 
diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index bcd4df2f1cad..816ae8ee3e06 100644
--- a/net/ipv4/nexthop.c
+++ b/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[] = {
@@ -2971,7 +2973,7 @@  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);
@@ -2992,6 +2994,11 @@  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;
 }
 
@@ -3007,6 +3014,7 @@  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;
 
@@ -3015,7 +3023,7 @@  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;
 
@@ -3036,6 +3044,7 @@  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;
 
@@ -3044,7 +3053,7 @@  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;
 
@@ -3080,6 +3089,7 @@  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,
@@ -3151,6 +3161,11 @@  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_bitfield32(tb[NHA_OP_FLAGS]).value;
+	else
+		filter->op_flags = 0;
+
 	return 0;
 }
 
@@ -3474,6 +3489,7 @@  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,
@@ -3481,7 +3497,7 @@  static int nh_valid_get_bucket_req(const 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;