net: shaper: implement introspection support

The netlink op is a simple wrapper around the device callback.

Extend the existing fetch_dev() helper adding an attribute argument
for the requested device. Reuse such helper in the newly implemented
operation.

Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Link: https://patch.msgid.link/66eb62f22b3a5ba06ca91d01ae77515e5f447e15.1728460186.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/shaper/shaper.c

@@ -601,22 +601,29 @@ int net_shaper_nl_post_dumpit(struct netlink_callback *cb)
 int net_shaper_nl_cap_pre_doit(const struct genl_split_ops *ops,
 			       struct sk_buff *skb, struct genl_info *info)
 {
-	return -EOPNOTSUPP;
+	return net_shaper_generic_pre(info, NET_SHAPER_A_CAPS_IFINDEX);
 }
 
 void net_shaper_nl_cap_post_doit(const struct genl_split_ops *ops,
 				 struct sk_buff *skb, struct genl_info *info)
 {
+	net_shaper_generic_post(info);
 }
 
 int net_shaper_nl_cap_pre_dumpit(struct netlink_callback *cb)
 {
-	return -EOPNOTSUPP;
+	struct net_shaper_nl_ctx *ctx = (struct net_shaper_nl_ctx *)cb->ctx;
+
+	return net_shaper_ctx_setup(genl_info_dump(cb),
+				    NET_SHAPER_A_CAPS_IFINDEX, ctx);
 }
 
 int net_shaper_nl_cap_post_dumpit(struct netlink_callback *cb)
 {
-	return -EOPNOTSUPP;
+	struct net_shaper_nl_ctx *ctx = (struct net_shaper_nl_ctx *)cb->ctx;
+
+	net_shaper_ctx_cleanup(ctx);
+	return 0;
 }
 
 int net_shaper_nl_get_doit(struct sk_buff *skb, struct genl_info *info)
@@ -1147,14 +1154,99 @@ int net_shaper_nl_group_doit(struct sk_buff *skb, struct genl_info *info)
 	goto free_leaves;
 }
 
+static int
+net_shaper_cap_fill_one(struct sk_buff *msg,
+			struct net_shaper_binding *binding,
+			enum net_shaper_scope scope, unsigned long flags,
+			const struct genl_info *info)
+{
+	unsigned long cur;
+	void *hdr;
+
+	hdr = genlmsg_iput(msg, info);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	if (net_shaper_fill_binding(msg, binding, NET_SHAPER_A_CAPS_IFINDEX) ||
+	    nla_put_u32(msg, NET_SHAPER_A_CAPS_SCOPE, scope))
+		goto nla_put_failure;
+
+	for (cur = NET_SHAPER_A_CAPS_SUPPORT_METRIC_BPS;
+	     cur <= NET_SHAPER_A_CAPS_MAX; ++cur) {
+		if (flags & BIT(cur) && nla_put_flag(msg, cur))
+			goto nla_put_failure;
+	}
+
+	genlmsg_end(msg, hdr);
+
+	return 0;
+
+nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	return -EMSGSIZE;
+}
+
 int net_shaper_nl_cap_get_doit(struct sk_buff *skb, struct genl_info *info)
 {
+	struct net_shaper_binding *binding;
+	const struct net_shaper_ops *ops;
+	enum net_shaper_scope scope;
+	unsigned long flags = 0;
+	struct sk_buff *msg;
+	int ret;
+
+	if (GENL_REQ_ATTR_CHECK(info, NET_SHAPER_A_CAPS_SCOPE))
+		return -EINVAL;
+
+	binding = net_shaper_binding_from_ctx(info->ctx);
+	scope = nla_get_u32(info->attrs[NET_SHAPER_A_CAPS_SCOPE]);
+	ops = net_shaper_ops(binding);
+	ops->capabilities(binding, scope, &flags);
+	if (!flags)
+		return -EOPNOTSUPP;
+
+	msg = genlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	ret = net_shaper_cap_fill_one(msg, binding, scope, flags, info);
+	if (ret)
+		goto free_msg;
+
+	ret =  genlmsg_reply(msg, info);
+	if (ret)
+		goto free_msg;
 	return 0;
+
+free_msg:
+	nlmsg_free(msg);
+	return ret;
 }
 
 int net_shaper_nl_cap_get_dumpit(struct sk_buff *skb,
 				 struct netlink_callback *cb)
 {
+	const struct genl_info *info = genl_info_dump(cb);
+	struct net_shaper_binding *binding;
+	const struct net_shaper_ops *ops;
+	enum net_shaper_scope scope;
+	int ret;
+
+	binding = net_shaper_binding_from_ctx(cb->ctx);
+	ops = net_shaper_ops(binding);
+	for (scope = 0; scope <= NET_SHAPER_SCOPE_MAX; ++scope) {
+		unsigned long flags = 0;
+
+		ops->capabilities(binding, scope, &flags);
+		if (!flags)
+			continue;
+
+		ret = net_shaper_cap_fill_one(skb, binding, scope, flags,
+					      info);
+		if (ret)
+			return ret;
+	}
+
 	return 0;
 }