[RFC PATCH net-next 31/33] mptcp: Add path manager interface

[Mat Martineau <mathew.j.martineau@linux.intel.com>]

From: Peter Krystad <peter.krystad@linux.intel.com>

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.

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

Signed-off-by: Peter Krystad <peter.krystad@linux.intel.com>
---
 net/mptcp/Makefile   |  2 +-
 net/mptcp/pm.c       | 57 ++++++++++++++++++++++++++++++++++++++++++++
 net/mptcp/protocol.c |  4 ++++
 net/mptcp/protocol.h | 25 ++++++++++++++++++-
 4 files changed, 86 insertions(+), 2 deletions(-)
 create mode 100644 net/mptcp/pm.c

diff --git a/net/mptcp/Makefile b/net/mptcp/Makefile
index 178ae81d8b66..7fe7aa64eda0 100644
--- a/net/mptcp/Makefile
+++ b/net/mptcp/Makefile
@@ -1,4 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_MPTCP) += mptcp.o
 
-mptcp-y := protocol.o subflow.o options.o token.o crypto.o
+mptcp-y := protocol.o subflow.o options.o token.o crypto.o pm.o
diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
new file mode 100644
index 000000000000..512dc110098a
--- /dev/null
+++ b/net/mptcp/pm.c
@@ -0,0 +1,57 @@
+// 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"
+
+void pm_new_connection(struct mptcp_sock *msk)
+{
+	pr_debug("msk=%p", msk);
+}
+
+void pm_fully_established(struct mptcp_sock *msk)
+{
+	pr_debug("msk=%p", msk);
+}
+
+void pm_connection_closed(struct mptcp_sock *msk)
+{
+	pr_debug("msk=%p", msk);
+}
+
+void pm_subflow_established(struct mptcp_sock *msk, u8 id)
+{
+	pr_debug("msk=%p", msk);
+}
+
+void pm_subflow_closed(struct mptcp_sock *msk, u8 id)
+{
+	pr_debug("msk=%p", msk);
+}
+
+void pm_add_addr(struct mptcp_sock *msk, const struct in_addr *addr, u8 id)
+{
+	pr_debug("msk=%p", msk);
+}
+
+void pm_add_addr6(struct mptcp_sock *msk, const struct in6_addr *addr, u8 id)
+{
+	pr_debug("msk=%p", msk);
+}
+
+void pm_rm_addr(struct mptcp_sock *msk, u8 id)
+{
+	pr_debug("msk=%p", msk);
+}
+
+bool pm_addr_signal(struct mptcp_sock *msk, unsigned int *size,
+		    unsigned int remaining, struct mptcp_out_options *opts)
+{
+	pr_debug("msk=%p", msk);
+
+	return false;
+}
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index d4ffa47f53ef..e071fc8191ee 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -632,6 +632,8 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
 		token_update_accept(new_sock->sk, new_mptcp_sock);
 		msk->subflow = NULL;
 
+		pm_new_connection(msk);
+
 		crypto_key_sha1(msk->remote_key, NULL, &ack_seq);
 		msk->write_seq = subflow->idsn + 1;
 		ack_seq++;
@@ -757,6 +759,8 @@ void mptcp_finish_connect(struct sock *sk, int mp_capable)
 		msk->token = subflow->token;
 		pr_debug("msk=%p, token=%u", msk, msk->token);
 
+		pm_new_connection(msk);
+
 		crypto_key_sha1(msk->remote_key, NULL, &ack_seq);
 		msk->write_seq = subflow->idsn + 1;
 		ack_seq++;
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 556981f9e5fd..044665328b79 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -14,7 +14,7 @@
 #define MPTCPOPT_MP_JOIN	1
 #define MPTCPOPT_DSS		2
 #define MPTCPOPT_ADD_ADDR	3
-#define MPTCPOPT_REMOVE_ADDR	4
+#define MPTCPOPT_RM_ADDR	4
 #define MPTCPOPT_MP_PRIO	5
 #define MPTCPOPT_MP_FAIL	6
 #define MPTCPOPT_MP_FASTCLOSE	7
@@ -45,6 +45,17 @@
 #define MPTCP_DSS_HAS_ACK	BIT(0)
 #define MPTCP_DSS_FLAG_MASK	(0x1F)
 
+struct pm_data {
+	u8 addr_id;
+	sa_family_t family;
+	union {
+		struct in_addr addr;
+#if IS_ENABLED(CONFIG_IPV6)
+		struct in6_addr addr6;
+#endif
+	};
+};
+
 /* MPTCP connection sock */
 struct mptcp_sock {
 	/* inet_connection_sock must be the first member */
@@ -56,6 +67,7 @@ struct mptcp_sock {
 	u32		token;
 	struct list_head conn_list;
 	struct socket	*subflow; /* outgoing connect/listener/!mp_capable */
+	struct pm_data	pm;
 };
 
 #define mptcp_for_each_subflow(__msk, __subflow)			\
@@ -157,6 +169,17 @@ void crypto_key_sha1(u64 key, u32 *token, u64 *idsn);
 void crypto_hmac_sha1(u64 key1, u64 key2, u32 *hash_out,
 		      int arg_num, ...);
 
+void pm_new_connection(struct mptcp_sock *msk);
+void pm_fully_established(struct mptcp_sock *msk);
+void pm_connection_closed(struct mptcp_sock *msk);
+void pm_subflow_established(struct mptcp_sock *msk, u8 id);
+void pm_subflow_closed(struct mptcp_sock *msk, u8 id);
+void pm_add_addr(struct mptcp_sock *msk, const struct in_addr *addr, u8 id);
+void pm_add_addr6(struct mptcp_sock *msk, const struct in6_addr *addr, u8 id);
+void pm_rm_addr(struct mptcp_sock *msk, u8 id);
+bool pm_addr_signal(struct mptcp_sock *msk, unsigned int *size,
+		    unsigned int remaining, struct mptcp_out_options *opts);
+
 static inline struct mptcp_ext *mptcp_get_ext(struct sk_buff *skb)
 {
 	return (struct mptcp_ext *)skb_ext_find(skb, SKB_EXT_MPTCP);
-- 
2.22.0