mptcp: add pm listener events

This patch adds two new MPTCP netlink event types for PM listening
socket create and close, named MPTCP_EVENT_LISTENER_CREATED and
MPTCP_EVENT_LISTENER_CLOSED.

Add a new function mptcp_event_pm_listener() to push the new events
with family, port and addr to userspace.

Invoke mptcp_event_pm_listener() with MPTCP_EVENT_LISTENER_CREATED in
mptcp_listen() and mptcp_pm_nl_create_listen_socket(), invoke it with
MPTCP_EVENT_LISTENER_CLOSED in __mptcp_close_ssk().

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/uapi/linux/mptcp.h

@@ -160,6 +160,12 @@ struct mptcp_info {
  *                           daddr4 | daddr6, sport, dport, backup, if_idx
  *                           [, error]
  * The priority of a subflow has changed. 'error' should not be set.
+ *
+ * MPTCP_EVENT_LISTENER_CREATED: family, sport, saddr4 | saddr6
+ * A new PM listener is created.
+ *
+ * MPTCP_EVENT_LISTENER_CLOSED: family, sport, saddr4 | saddr6
+ * A PM listener is closed.
  */
 enum mptcp_event_type {
 	MPTCP_EVENT_UNSPEC = 0,
@@ -174,6 +180,9 @@ enum mptcp_event_type {
 	MPTCP_EVENT_SUB_CLOSED = 11,
 
 	MPTCP_EVENT_SUB_PRIORITY = 13,
+
+	MPTCP_EVENT_LISTENER_CREATED = 15,
+	MPTCP_EVENT_LISTENER_CLOSED = 16,
 };
 
 enum mptcp_event_attr {

net/mptcp/pm_netlink.c

@@ -1029,6 +1029,8 @@ static int mptcp_pm_nl_create_listen_socket(struct sock *sk,
 	if (err)
 		return err;
 
+	mptcp_event_pm_listener(ssock->sk, MPTCP_EVENT_LISTENER_CREATED);
+
 	return 0;
 }
 
@@ -2152,6 +2154,58 @@ nla_put_failure:
 	kfree_skb(skb);
 }
 
+void mptcp_event_pm_listener(const struct sock *ssk,
+			     enum mptcp_event_type event)
+{
+	const struct inet_sock *issk = inet_sk(ssk);
+	struct net *net = sock_net(ssk);
+	struct nlmsghdr *nlh;
+	struct sk_buff *skb;
+
+	if (!genl_has_listeners(&mptcp_genl_family, net, MPTCP_PM_EV_GRP_OFFSET))
+		return;
+
+	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!skb)
+		return;
+
+	nlh = genlmsg_put(skb, 0, 0, &mptcp_genl_family, 0, event);
+	if (!nlh)
+		goto nla_put_failure;
+
+	if (nla_put_u16(skb, MPTCP_ATTR_FAMILY, ssk->sk_family))
+		goto nla_put_failure;
+
+	if (nla_put_be16(skb, MPTCP_ATTR_SPORT, issk->inet_sport))
+		goto nla_put_failure;
+
+	switch (ssk->sk_family) {
+	case AF_INET:
+		if (nla_put_in_addr(skb, MPTCP_ATTR_SADDR4, issk->inet_saddr))
+			goto nla_put_failure;
+		break;
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+	case AF_INET6: {
+		const struct ipv6_pinfo *np = inet6_sk(ssk);
+
+		if (nla_put_in6_addr(skb, MPTCP_ATTR_SADDR6, &np->saddr))
+			goto nla_put_failure;
+		break;
+	}
+#endif
+	default:
+		WARN_ON_ONCE(1);
+		goto nla_put_failure;
+	}
+
+	genlmsg_end(skb, nlh);
+	mptcp_nl_mcast_send(net, skb, GFP_KERNEL);
+	return;
+
+nla_put_failure:
+	kfree_skb(skb);
+}
+
 void mptcp_event(enum mptcp_event_type type, const struct mptcp_sock *msk,
 		 const struct sock *ssk, gfp_t gfp)
 {
@@ -2197,6 +2251,9 @@ void mptcp_event(enum mptcp_event_type type, const struct mptcp_sock *msk,
 		if (mptcp_event_sub_closed(skb, msk, ssk) < 0)
 			goto nla_put_failure;
 		break;
+	case MPTCP_EVENT_LISTENER_CREATED:
+	case MPTCP_EVENT_LISTENER_CLOSED:
+		break;
 	}
 
 	genlmsg_end(skb, nlh);

net/mptcp/protocol.c

@@ -2355,6 +2355,7 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 			tcp_set_state(ssk, TCP_CLOSE);
 			mptcp_subflow_queue_clean(ssk);
 			inet_csk_listen_stop(ssk);
+			mptcp_event_pm_listener(ssk, MPTCP_EVENT_LISTENER_CLOSED);
 		}
 		__tcp_close(ssk, 0);
 
@@ -3647,6 +3648,8 @@ static int mptcp_listen(struct socket *sock, int backlog)
 	if (!err)
 		mptcp_copy_inaddrs(sock->sk, ssock->sk);
 
+	mptcp_event_pm_listener(ssock->sk, MPTCP_EVENT_LISTENER_CREATED);
+
 unlock:
 	release_sock(sock->sk);
 	return err;

net/mptcp/protocol.h

@@ -839,6 +839,8 @@ void mptcp_event(enum mptcp_event_type type, const struct mptcp_sock *msk,
 		 const struct sock *ssk, gfp_t gfp);
 void mptcp_event_addr_announced(const struct sock *ssk, const struct mptcp_addr_info *info);
 void mptcp_event_addr_removed(const struct mptcp_sock *msk, u8 id);
+void mptcp_event_pm_listener(const struct sock *ssk,
+			     enum mptcp_event_type event);
 bool mptcp_userspace_pm_active(const struct mptcp_sock *msk);
 
 void mptcp_fastopen_gen_msk_ackseq(struct mptcp_sock *msk, struct mptcp_subflow_context *subflow,