mptcp: add netlink-based PM

Expose a new netlink family to userspace to control the PM, setting:

 - list of local addresses to be signalled.
 - list of local addresses used to created subflows.
 - maximum number of add_addr option to react

When the msk is fully established, the PM netlink attempts to
announce the 'signal' list via the ADD_ADDR option. Since we
currently lack the ADD_ADDR echo (and related event) only the
first addr is sent.

After exhausting the 'announce' list, the PM tries to create
subflow for each addr in 'local' list, waiting for each
connection to be completed before attempting the next one.

Idea is to add an additional PM hook for ADD_ADDR echo, to allow
the PM netlink announcing multiple addresses, in sequence.
Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/mptcp.h

@@ -32,4 +32,58 @@ enum {
 };
 
 #define MPTCP_SUBFLOW_ATTR_MAX (__MPTCP_SUBFLOW_ATTR_MAX - 1)
+
+/* netlink interface */
+#define MPTCP_PM_NAME		"mptcp_pm"
+#define MPTCP_PM_CMD_GRP_NAME	"mptcp_pm_cmds"
+#define MPTCP_PM_VER		0x1
+
+/*
+ * ATTR types defined for MPTCP
+ */
+enum {
+	MPTCP_PM_ATTR_UNSPEC,
+
+	MPTCP_PM_ATTR_ADDR,				/* nested address */
+	MPTCP_PM_ATTR_RCV_ADD_ADDRS,			/* u32 */
+	MPTCP_PM_ATTR_SUBFLOWS,				/* u32 */
+
+	__MPTCP_PM_ATTR_MAX
+};
+
+#define MPTCP_PM_ATTR_MAX (__MPTCP_PM_ATTR_MAX - 1)
+
+enum {
+	MPTCP_PM_ADDR_ATTR_UNSPEC,
+
+	MPTCP_PM_ADDR_ATTR_FAMILY,			/* u16 */
+	MPTCP_PM_ADDR_ATTR_ID,				/* u8 */
+	MPTCP_PM_ADDR_ATTR_ADDR4,			/* struct in_addr */
+	MPTCP_PM_ADDR_ATTR_ADDR6,			/* struct in6_addr */
+	MPTCP_PM_ADDR_ATTR_PORT,			/* u16 */
+	MPTCP_PM_ADDR_ATTR_FLAGS,			/* u32 */
+	MPTCP_PM_ADDR_ATTR_IF_IDX,			/* s32 */
+
+	__MPTCP_PM_ADDR_ATTR_MAX
+};
+
+#define MPTCP_PM_ADDR_ATTR_MAX (__MPTCP_PM_ADDR_ATTR_MAX - 1)
+
+#define MPTCP_PM_ADDR_FLAG_SIGNAL			(1 << 0)
+#define MPTCP_PM_ADDR_FLAG_SUBFLOW			(1 << 1)
+#define MPTCP_PM_ADDR_FLAG_BACKUP			(1 << 2)
+
+enum {
+	MPTCP_PM_CMD_UNSPEC,
+
+	MPTCP_PM_CMD_ADD_ADDR,
+	MPTCP_PM_CMD_DEL_ADDR,
+	MPTCP_PM_CMD_GET_ADDR,
+	MPTCP_PM_CMD_FLUSH_ADDRS,
+	MPTCP_PM_CMD_SET_LIMITS,
+	MPTCP_PM_CMD_GET_LIMITS,
+
+	__MPTCP_PM_CMD_AFTER_LAST
+};
+
 #endif /* _UAPI_MPTCP_H */

net/mptcp/Makefile

 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_MPTCP) += mptcp.o
 
-mptcp-y := protocol.o subflow.o options.o token.o crypto.o ctrl.o pm.o diag.o mib.o
+mptcp-y := protocol.o subflow.o options.o token.o crypto.o ctrl.o pm.o diag.o \
+	   mib.o pm_netlink.o

net/mptcp/pm.c

@@ -176,7 +176,7 @@ bool mptcp_pm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
 
 int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
 {
-	return 0;
+	return mptcp_pm_nl_get_local_id(msk, skc);
 }
 
 static void pm_worker(struct work_struct *work)
@@ -192,12 +192,15 @@ static void pm_worker(struct work_struct *work)
 	pr_debug("msk=%p status=%x", msk, pm->status);
 	if (pm->status & BIT(MPTCP_PM_ADD_ADDR_RECEIVED)) {
 		pm->status &= ~BIT(MPTCP_PM_ADD_ADDR_RECEIVED);
+		mptcp_pm_nl_add_addr_received(msk);
 	}
 	if (pm->status & BIT(MPTCP_PM_ESTABLISHED)) {
 		pm->status &= ~BIT(MPTCP_PM_ESTABLISHED);
+		mptcp_pm_nl_fully_established(msk);
 	}
 	if (pm->status & BIT(MPTCP_PM_SUBFLOW_ESTABLISHED)) {
 		pm->status &= ~BIT(MPTCP_PM_SUBFLOW_ESTABLISHED);
+		mptcp_pm_nl_subflow_established(msk);
 	}
 
 	spin_unlock_bh(&msk->pm.lock);
@@ -219,6 +222,8 @@ void mptcp_pm_data_init(struct mptcp_sock *msk)
 
 	spin_lock_init(&msk->pm.lock);
 	INIT_WORK(&msk->pm.work, pm_worker);
+
+	mptcp_pm_nl_data_init(msk);
 }
 
 void mptcp_pm_close(struct mptcp_sock *msk)
@@ -232,4 +237,6 @@ 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");
+
+	mptcp_pm_nl_init();
 }

net/mptcp/protocol.h

@@ -396,6 +396,13 @@ bool mptcp_pm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
 			  struct mptcp_addr_info *saddr);
 int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc);
 
+void mptcp_pm_nl_init(void);
+void mptcp_pm_nl_data_init(struct mptcp_sock *msk);
+void mptcp_pm_nl_fully_established(struct mptcp_sock *msk);
+void mptcp_pm_nl_subflow_established(struct mptcp_sock *msk);
+void mptcp_pm_nl_add_addr_received(struct mptcp_sock *msk);
+int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct sock_common *skc);
+
 static inline struct mptcp_ext *mptcp_get_ext(struct sk_buff *skb)
 {
 	return (struct mptcp_ext *)skb_ext_find(skb, SKB_EXT_MPTCP);