netdev - [PATCH net-next v3 22/24] ovpn: notify userspace when a peer is deleted

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Message-ID: <20240506011637.27272-23-antonio@openvpn.net>
Date: Mon,  6 May 2024 03:16:35 +0200
From: Antonio Quartulli <antonio@...nvpn.net>
To: netdev@...r.kernel.org
Cc: Jakub Kicinski <kuba@...nel.org>,
	Sergey Ryazanov <ryazanov.s.a@...il.com>,
	Paolo Abeni <pabeni@...hat.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Andrew Lunn <andrew@...n.ch>,
	Esben Haabendal <esben@...nix.com>,
	Antonio Quartulli <antonio@...nvpn.net>
Subject: [PATCH net-next v3 22/24] 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 | 56 ++++++++++++++++++++++++++++++++++++++
 drivers/net/ovpn/netlink.h |  8 ++++++
 drivers/net/ovpn/peer.c    |  1 +
 3 files changed, 65 insertions(+)

diff --git a/drivers/net/ovpn/netlink.c b/drivers/net/ovpn/netlink.c
index dc80004eadbb..98c4e389b4f5 100644
--- a/drivers/net/ovpn/netlink.c
+++ b/drivers/net/ovpn/netlink.c
@@ -862,6 +862,62 @@ int ovpn_nl_del_key_doit(struct sk_buff *skb, struct genl_info *info)
 	return 0;
 }
 
+int ovpn_nl_notify_del_peer(struct ovpn_peer *peer)
+{
+	struct sk_buff *msg;
+	struct nlattr *attr;
+	void *hdr;
+	int ret;
+
+	netdev_info(peer->ovpn->dev, "deleting peer with id %u, reason %d\n",
+		    peer->id, peer->delete_reason);
+
+	msg = nlmsg_new(100, GFP_KERNEL);
+	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)) {
+		ret = -EMSGSIZE;
+		goto err_free_msg;
+	}
+
+	attr = nla_nest_start(msg, OVPN_A_PEER);
+	if (!attr) {
+		ret = -EMSGSIZE;
+		goto err_free_msg;
+	}
+
+	if (nla_put_u8(msg, OVPN_A_PEER_DEL_REASON, peer->delete_reason)) {
+		ret = -EMSGSIZE;
+		goto err_free_msg;
+	}
+
+	if (nla_put_u32(msg, OVPN_A_PEER_ID, peer->id)) {
+		ret = -EMSGSIZE;
+		goto err_free_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_KERNEL);
+
+	return 0;
+
+err_free_msg:
+	nlmsg_free(msg);
+	return ret;
+}
+
 int ovpn_nl_notify_swap_keys(struct ovpn_peer *peer)
 {
 	struct sk_buff *msg;
diff --git a/drivers/net/ovpn/netlink.h b/drivers/net/ovpn/netlink.h
index ccc49130a150..d2720fb67257 100644
--- a/drivers/net/ovpn/netlink.h
+++ b/drivers/net/ovpn/netlink.h
@@ -27,6 +27,14 @@ int ovpn_nl_register(void);
  */
 void ovpn_nl_unregister(void);
 
+/**
+ * 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);
+
 /**
  * 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/peer.c b/drivers/net/ovpn/peer.c
index 07daa359b3a2..fb94ace6c9cf 100644
--- a/drivers/net/ovpn/peer.c
+++ b/drivers/net/ovpn/peer.c
@@ -315,6 +315,7 @@ static void ovpn_peer_delete_work(struct work_struct *work)
 	struct ovpn_peer *peer = container_of(work, struct ovpn_peer,
 					      delete_work);
 	ovpn_peer_release(peer);
+	ovpn_nl_notify_del_peer(peer);
 }
 
 void ovpn_peer_release_kref(struct kref *kref)
-- 
2.43.2