genetlink: add struct genl_info to struct genl_dumpit_info

Netlink GET implementations must currently juggle struct genl_info
and struct netlink_callback, depending on whether they were called
from doit or dumpit.

Add genl_info to the dump state and populate the fields.
This way implementations can simply pass struct genl_info around.
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20230814214723.2924989-5-kuba@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/genetlink.h

@@ -250,11 +250,13 @@ struct genl_split_ops {
  * @family: generic netlink family - for internal genl code usage
  * @op: generic netlink ops - for internal genl code usage
  * @attrs: netlink attributes
+ * @info: struct genl_info describing the request
  */
 struct genl_dumpit_info {
 	const struct genl_family *family;
 	struct genl_split_ops op;
 	struct nlattr **attrs;
+	struct genl_info info;
 };
 
 static inline const struct genl_dumpit_info *
@@ -263,6 +265,12 @@ genl_dumpit_info(struct netlink_callback *cb)
 	return cb->data;
 }
 
+static inline const struct genl_info *
+genl_info_dump(struct netlink_callback *cb)
+{
+	return &genl_dumpit_info(cb)->info;
+}
+
 int genl_register_family(struct genl_family *family);
 int genl_unregister_family(const struct genl_family *family);
 void genl_notify(const struct genl_family *family, struct sk_buff *skb,

net/netlink/genetlink.c

@@ -847,6 +847,14 @@ static int genl_start(struct netlink_callback *cb)
 	info->family = ctx->family;
 	info->op = *ops;
 	info->attrs = attrs;
+	info->info.snd_seq	= cb->nlh->nlmsg_seq;
+	info->info.snd_portid	= NETLINK_CB(cb->skb).portid;
+	info->info.nlhdr	= cb->nlh;
+	info->info.genlhdr	= nlmsg_data(cb->nlh);
+	info->info.attrs	= attrs;
+	genl_info_net_set(&info->info, sock_net(cb->skb->sk));
+	info->info.extack	= cb->extack;
+	memset(&info->info.user_ptr, 0, sizeof(info->info.user_ptr));
 
 	cb->data = info;
 	if (ops->start) {
@@ -865,10 +873,12 @@ static int genl_start(struct netlink_callback *cb)
 
 static int genl_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 {
-	const struct genl_dumpit_info *info = genl_dumpit_info(cb);
+	struct genl_dumpit_info *info = cb->data;
 	const struct genl_split_ops *ops = &info->op;
 	int rc;
 
+	info->info.extack = cb->extack;
+
 	genl_op_lock(info->family);
 	rc = ops->dumpit(skb, cb);
 	genl_op_unlock(info->family);
@@ -877,10 +887,12 @@ static int genl_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 
 static int genl_done(struct netlink_callback *cb)
 {
-	const struct genl_dumpit_info *info = genl_dumpit_info(cb);
+	struct genl_dumpit_info *info = cb->data;
 	const struct genl_split_ops *ops = &info->op;
 	int rc = 0;
 
+	info->info.extack = cb->extack;
+
 	if (ops->done) {
 		genl_op_lock(info->family);
 		rc = ops->done(cb);