ovpn: notify userspace on client float event

Send a netlink notification when a client updates its remote UDP
endpoint. The notification includes the new IP address, port, and scope
ID (for IPv6).

Cc: linux-kselftest@vger.kernel.org
Cc: horms@kernel.org
Cc: shuah@kernel.org
Cc: donald.hunter@gmail.com
Signed-off-by: Ralf Lici <ralf@mandelbit.com>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>

Documentation/netlink/specs/ovpn.yaml

@@ -502,6 +502,12 @@ operations:
             - ifindex
             - keyconf
 
+    -
+      name: peer-float-ntf
+      doc: Notification about a peer floating (changing its remote UDP endpoint)
+      notify: peer-get
+      mcgrp: peers
+
 mcast-groups:
   list:
     -

drivers/net/ovpn/netlink.c

@@ -1203,6 +1203,88 @@ int ovpn_nl_peer_del_notify(struct ovpn_peer *peer)
 	return ret;
 }
 
+/**
+ * ovpn_nl_peer_float_notify - notify userspace about peer floating
+ * @peer: the floated peer
+ * @ss: sockaddr representing the new remote endpoint
+ *
+ * Return: 0 on success or a negative error code otherwise
+ */
+int ovpn_nl_peer_float_notify(struct ovpn_peer *peer,
+			      const struct sockaddr_storage *ss)
+{
+	struct ovpn_socket *sock;
+	struct sockaddr_in6 *sa6;
+	struct sockaddr_in *sa;
+	struct sk_buff *msg;
+	struct nlattr *attr;
+	int ret = -EMSGSIZE;
+	void *hdr;
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
+	if (!msg)
+		return -ENOMEM;
+
+	hdr = genlmsg_put(msg, 0, 0, &ovpn_nl_family, 0,
+			  OVPN_CMD_PEER_FLOAT_NTF);
+	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_u32(msg, OVPN_A_PEER_ID, peer->id))
+		goto err_cancel_msg;
+
+	if (ss->ss_family == AF_INET) {
+		sa = (struct sockaddr_in *)ss;
+		if (nla_put_in_addr(msg, OVPN_A_PEER_REMOTE_IPV4,
+				    sa->sin_addr.s_addr) ||
+		    nla_put_net16(msg, OVPN_A_PEER_REMOTE_PORT, sa->sin_port))
+			goto err_cancel_msg;
+	} else if (ss->ss_family == AF_INET6) {
+		sa6 = (struct sockaddr_in6 *)ss;
+		if (nla_put_in6_addr(msg, OVPN_A_PEER_REMOTE_IPV6,
+				     &sa6->sin6_addr) ||
+		    nla_put_u32(msg, OVPN_A_PEER_REMOTE_IPV6_SCOPE_ID,
+				sa6->sin6_scope_id) ||
+		    nla_put_net16(msg, OVPN_A_PEER_REMOTE_PORT, sa6->sin6_port))
+			goto err_cancel_msg;
+	} else {
+		ret = -EAFNOSUPPORT;
+		goto err_cancel_msg;
+	}
+
+	nla_nest_end(msg, attr);
+	genlmsg_end(msg, hdr);
+
+	rcu_read_lock();
+	sock = rcu_dereference(peer->sock);
+	if (!sock) {
+		ret = -EINVAL;
+		goto err_unlock;
+	}
+	genlmsg_multicast_netns(&ovpn_nl_family, sock_net(sock->sk), msg,
+				0, OVPN_NLGRP_PEERS, GFP_ATOMIC);
+	rcu_read_unlock();
+
+	return 0;
+
+err_unlock:
+	rcu_read_unlock();
+err_cancel_msg:
+	genlmsg_cancel(msg, hdr);
+err_free_msg:
+	nlmsg_free(msg);
+	return ret;
+}
+
 /**
  * ovpn_nl_key_swap_notify - notify userspace peer's key must be renewed
  * @peer: the peer whose key needs to be renewed

drivers/net/ovpn/netlink.h

@@ -13,6 +13,8 @@ int ovpn_nl_register(void);
 void ovpn_nl_unregister(void);
 
 int ovpn_nl_peer_del_notify(struct ovpn_peer *peer);
+int ovpn_nl_peer_float_notify(struct ovpn_peer *peer,
+			      const struct sockaddr_storage *ss);
 int ovpn_nl_key_swap_notify(struct ovpn_peer *peer, u8 key_id);
 
 #endif /* _NET_OVPN_NETLINK_H_ */

drivers/net/ovpn/peer.c

@@ -287,6 +287,8 @@ void ovpn_peer_endpoints_update(struct ovpn_peer *peer, struct sk_buff *skb)
 
 	spin_unlock_bh(&peer->lock);
 
+	ovpn_nl_peer_float_notify(peer, &ss);
+
 	/* rehashing is required only in MP mode as P2P has one peer
 	 * only and thus there is no hashtable
 	 */

include/uapi/linux/ovpn.h

@@ -100,6 +100,7 @@ enum {
 	OVPN_CMD_KEY_SWAP,
 	OVPN_CMD_KEY_SWAP_NTF,
 	OVPN_CMD_KEY_DEL,
+	OVPN_CMD_PEER_FLOAT_NTF,
 
 	__OVPN_CMD_MAX,
 	OVPN_CMD_MAX = (__OVPN_CMD_MAX - 1)

tools/testing/selftests/net/ovpn/ovpn-cli.c

@@ -1516,6 +1516,9 @@ static int ovpn_handle_msg(struct nl_msg *msg, void *arg)
 	case OVPN_CMD_PEER_DEL_NTF:
 		fprintf(stdout, "received CMD_PEER_DEL_NTF\n");
 		break;
+	case OVPN_CMD_PEER_FLOAT_NTF:
+		fprintf(stdout, "received CMD_PEER_FLOAT_NTF\n");
+		break;
 	case OVPN_CMD_KEY_SWAP_NTF:
 		fprintf(stdout, "received CMD_KEY_SWAP_NTF\n");
 		break;