mptcp: Add handling of incoming MP_JOIN requests

Process the MP_JOIN option in a SYN packet with the same flow
as MP_CAPABLE but when the third ACK is received add the
subflow to the MPTCP socket subflow list instead of adding it to
the TCP socket accept queue.

The subflow is added at the end of the subflow list so it will not
interfere with the existing subflows operation and no data is
expected to be transmitted on it.

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>
Signed-off-by: Peter Krystad <peter.krystad@linux.intel.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 27 insertions, 0 deletions

diff --git a/net/mptcp/token.c b/net/mptcp/token.c
index b71b53c0ac8d..129a5ad1bc35 100644
--- a/net/mptcp/token.c
+++ b/net/mptcp/token.c
@@ -141,6 +141,33 @@ int mptcp_token_new_accept(u32 token, struct sock *conn)
 }
 
 /**
+ * mptcp_token_get_sock - retrieve mptcp connection sock using its token
+ * @token: token of the mptcp connection to retrieve
+ *
+ * This function returns the mptcp connection structure with the given token.
+ * A reference count on the mptcp socket returned is taken.
+ *
+ * returns NULL if no connection with the given token value exists.
+ */
+struct mptcp_sock *mptcp_token_get_sock(u32 token)
+{
+	struct sock *conn;
+
+	spin_lock_bh(&token_tree_lock);
+	conn = radix_tree_lookup(&token_tree, token);
+	if (conn) {
+		/* token still reserved? */
+		if (conn == (struct sock *)&token_used)
+			conn = NULL;
+		else
+			sock_hold(conn);
+	}
+	spin_unlock_bh(&token_tree_lock);
+
+	return mptcp_sk(conn);
+}
+
+/**
  * mptcp_token_destroy_request - remove mptcp connection/token
  * @token - token of mptcp connection to remove
  *