mptcp: Add path manager interface

Add enough of a path manager interface to allow sending of ADD_ADDR
when an incoming MPTCP connection is created. Capable of sending only
a single IPv4 ADD_ADDR option. The 'pm_data' element of the connection
sock will need to be expanded to handle multiple interfaces and IPv6.
Partial processing of the incoming ADD_ADDR is included so the path
manager notification of that event happens at the proper time, which
involves validating the incoming address information.

This is a skeleton interface definition for events generated by
MPTCP.

Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Co-developed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Florian Westphal <fw@strlen.de>
Co-developed-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Co-developed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Peter Krystad <peter.krystad@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 113 insertions, 0 deletions

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
new file mode 100644
index 000000000000..ad837da0193d
--- /dev/null
+++ b/net/mptcp/pm.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Multipath TCP
+ *
+ * Copyright (c) 2019, Intel Corporation.
+ */
+#include <linux/kernel.h>
+#include <net/tcp.h>
+#include <net/mptcp.h>
+#include "protocol.h"
+
+static struct workqueue_struct *pm_wq;
+
+/* path manager command handlers */
+
+int mptcp_pm_announce_addr(struct mptcp_sock *msk,
+			   const struct mptcp_addr_info *addr)
+{
+	return -ENOTSUPP;
+}
+
+int mptcp_pm_remove_addr(struct mptcp_sock *msk, u8 local_id)
+{
+	return -ENOTSUPP;
+}
+
+int mptcp_pm_remove_subflow(struct mptcp_sock *msk, u8 remote_id)
+{
+	return -ENOTSUPP;
+}
+
+/* path manager event handlers */
+
+void mptcp_pm_new_connection(struct mptcp_sock *msk, int server_side)
+{
+	struct mptcp_pm_data *pm = &msk->pm;
+
+	pr_debug("msk=%p, token=%u side=%d", msk, msk->token, server_side);
+
+	WRITE_ONCE(pm->server_side, server_side);
+}
+
+bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk)
+{
+	pr_debug("msk=%p", msk);
+	return false;
+}
+
+void mptcp_pm_fully_established(struct mptcp_sock *msk)
+{
+	pr_debug("msk=%p", msk);
+}
+
+void mptcp_pm_connection_closed(struct mptcp_sock *msk)
+{
+	pr_debug("msk=%p", msk);
+}
+
+void mptcp_pm_subflow_established(struct mptcp_sock *msk,
+				  struct mptcp_subflow_context *subflow)
+{
+	pr_debug("msk=%p", msk);
+}
+
+void mptcp_pm_subflow_closed(struct mptcp_sock *msk, u8 id)
+{
+	pr_debug("msk=%p", msk);
+}
+
+void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
+				const struct mptcp_addr_info *addr)
+{
+	pr_debug("msk=%p, remote_id=%d", msk, addr->id);
+}
+
+/* path manager helpers */
+
+bool mptcp_pm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
+			  struct mptcp_addr_info *saddr)
+{
+	return false;
+}
+
+int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
+{
+	return 0;
+}
+
+static void pm_worker(struct work_struct *work)
+{
+}
+
+void mptcp_pm_data_init(struct mptcp_sock *msk)
+{
+	msk->pm.add_addr_signaled = 0;
+	msk->pm.add_addr_accepted = 0;
+	msk->pm.local_addr_used = 0;
+	msk->pm.subflows = 0;
+	WRITE_ONCE(msk->pm.work_pending, false);
+	WRITE_ONCE(msk->pm.addr_signal, false);
+	WRITE_ONCE(msk->pm.accept_addr, false);
+	WRITE_ONCE(msk->pm.accept_subflow, false);
+	msk->pm.status = 0;
+
+	spin_lock_init(&msk->pm.lock);
+	INIT_WORK(&msk->pm.work, pm_worker);
+}
+
+void mptcp_pm_init(void)
+{
+	pm_wq = alloc_workqueue("pm_wq", WQ_UNBOUND | WQ_MEM_RECLAIM, 8);
+	if (!pm_wq)
+		panic("Failed to allocate workqueue");
+}