On Mon,  6 May 2024 03:16:18 +0200 Antonio Quartulli wrote:

 int ovpn_nl_new_iface_doit(struct sk_buff *skb, struct genl_info *info)
 {
-	return -ENOTSUPP;
+	const char *ifname = OVPN_DEFAULT_IFNAME;
+	enum ovpn_mode mode = OVPN_MODE_P2P;
+	struct net_device *dev;
+	struct sk_buff *msg;
+	void *hdr;
+
+	if (info->attrs[OVPN_A_IFNAME])
+		ifname = nla_data(info->attrs[OVPN_A_IFNAME]);
+
+	if (info->attrs[OVPN_A_MODE]) {
+		mode = nla_get_u32(info->attrs[OVPN_A_MODE]);
+		pr_debug("ovpn: setting device (%s) mode: %u\n", ifname, mode);
+	}
+
+	dev = ovpn_iface_create(ifname, mode, genl_info_net(info));
+	if (IS_ERR(dev)) {
+		pr_err("ovpn: error while creating interface %s: %ld\n", ifname,
+		       PTR_ERR(dev));

Better to send the error to the caller with NL_SET_ERR_MSG_MOD()

+		return PTR_ERR(dev);
+	}
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	hdr = genlmsg_put(msg, info->snd_portid, info->snd_seq, &ovpn_nl_family,
+			  0, OVPN_CMD_NEW_IFACE);

genlmsg_iput() will save you a lot of typing

+	if (!hdr) {
+		netdev_err(dev, "%s: cannot create message header\n", __func__);
+		return -EMSGSIZE;
+	}
+
+	if (nla_put(msg, OVPN_A_IFNAME, strlen(dev->name) + 1, dev->name)) {

nla_put_string() ?

+		netdev_err(dev, "%s: cannot add ifname to reply\n", __func__);

Probably not worth it, can't happen given the message size

+		genlmsg_cancel(msg, hdr);
+		nlmsg_free(msg);
+		return -EMSGSIZE;
+	}
+
+	genlmsg_end(msg, hdr);
+
+	return genlmsg_reply(msg, info);
 }
 
 int ovpn_nl_del_iface_doit(struct sk_buff *skb, struct genl_info *info)
 {
-	return -ENOTSUPP;
+	struct ovpn_struct *ovpn = info->user_ptr[0];
+
+	rtnl_lock();
+	ovpn_iface_destruct(ovpn);
+	dev_put(ovpn->dev);
+	rtnl_unlock();
+
+	synchronize_net();

Why? 🤔️