netdev - [PATCH net-next v6 23/25] ovpn: notify userspace when a peer is deleted

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Message-ID: <20240827120805.13681-24-antonio@openvpn.net>
Date: Tue, 27 Aug 2024 14:08:03 +0200
From: Antonio Quartulli <antonio@...nvpn.net>
To: netdev@...r.kernel.org
Cc: kuba@...nel.org,
	pabeni@...hat.com,
	ryazanov.s.a@...il.com,
	edumazet@...gle.com,
	andrew@...n.ch,
	sd@...asysnail.net,
	Antonio Quartulli <antonio@...nvpn.net>
Subject: [PATCH net-next v6 23/25] ovpn: notify userspace when a peer is deleted

Whenever a peer is deleted, send a notification to userspace so that it
can react accordingly.

This is most important when a peer is deleted due to ping timeout,
because it all happens in kernelspace and thus userspace has no direct
way to learn about it.

Signed-off-by: Antonio Quartulli <antonio@...nvpn.net>
---
 drivers/net/ovpn/netlink.c | 55 ++++++++++++++++++++++++++++++++++++++
 drivers/net/ovpn/netlink.h |  1 +
 drivers/net/ovpn/peer.c    |  1 +
 3 files changed, 57 insertions(+)

diff --git a/drivers/net/ovpn/netlink.c b/drivers/net/ovpn/netlink.c
index 7cbad5a92b25..1933887ef281 100644
--- a/drivers/net/ovpn/netlink.c
+++ b/drivers/net/ovpn/netlink.c
@@ -911,6 +911,61 @@ int ovpn_nl_del_key_doit(struct sk_buff *skb, struct genl_info *info)
 	return 0;
 }
 
+/**
+ * ovpn_nl_notify_del_peer - notify userspace about peer being deleted
+ * @peer: the peer being deleted
+ *
+ * Return: 0 on success or a negative error code otherwise
+ */
+int ovpn_nl_notify_del_peer(struct ovpn_peer *peer)
+{
+	struct sk_buff *msg;
+	struct nlattr *attr;
+	int ret = -EMSGSIZE;
+	void *hdr;
+
+	netdev_info(peer->ovpn->dev, "deleting peer with id %u, reason %d\n",
+		    peer->id, peer->delete_reason);
+
+	msg = nlmsg_new(100, GFP_ATOMIC);
+	if (!msg)
+		return -ENOMEM;
+
+	hdr = genlmsg_put(msg, 0, 0, &ovpn_nl_family, 0, OVPN_CMD_DEL_PEER);
+	if (!hdr) {
+		ret = -ENOBUFS;
+		goto err_free_msg;
+	}
+
+	if (nla_put_u32(msg, OVPN_A_IFINDEX, peer->ovpn->dev->ifindex))
+		goto err_cancel_msg;
+
+	attr = nla_nest_start(msg, OVPN_A_PEER);
+	if (!attr)
+		goto err_cancel_msg;
+
+	if (nla_put_u8(msg, OVPN_A_PEER_DEL_REASON, peer->delete_reason))
+		goto err_cancel_msg;
+
+	if (nla_put_u32(msg, OVPN_A_PEER_ID, peer->id))
+		goto err_cancel_msg;
+
+	nla_nest_end(msg, attr);
+
+	genlmsg_end(msg, hdr);
+
+	genlmsg_multicast_netns(&ovpn_nl_family, dev_net(peer->ovpn->dev), msg,
+				0, OVPN_NLGRP_PEERS, GFP_ATOMIC);
+
+	return 0;
+
+err_cancel_msg:
+	genlmsg_cancel(msg, hdr);
+err_free_msg:
+	nlmsg_free(msg);
+	return ret;
+}
+
 /**
  * ovpn_nl_notify_swap_keys - notify userspace peer's key must be renewed
  * @peer: the peer whose key needs to be renewed
diff --git a/drivers/net/ovpn/netlink.h b/drivers/net/ovpn/netlink.h
index 972d12fc8f93..5bb53bbd36d1 100644
--- a/drivers/net/ovpn/netlink.h
+++ b/drivers/net/ovpn/netlink.h
@@ -12,6 +12,7 @@
 int ovpn_nl_register(void);
 void ovpn_nl_unregister(void);
 
+int ovpn_nl_notify_del_peer(struct ovpn_peer *peer);
 int ovpn_nl_notify_swap_keys(struct ovpn_peer *peer, u8 key_id);
 
 #endif /* _NET_OVPN_NETLINK_H_ */
diff --git a/drivers/net/ovpn/peer.c b/drivers/net/ovpn/peer.c
index c460a71dcc29..3fc64af4f22a 100644
--- a/drivers/net/ovpn/peer.c
+++ b/drivers/net/ovpn/peer.c
@@ -238,6 +238,7 @@ void ovpn_peer_release_kref(struct kref *kref)
 {
 	struct ovpn_peer *peer = container_of(kref, struct ovpn_peer, refcount);
 
+	ovpn_nl_notify_del_peer(peer);
 	ovpn_peer_release(peer);
 	kfree_rcu(peer, rcu);
 }
-- 
2.44.2