rxrpc: Fix exclusive connection handling

"Exclusive connections" are meant to be used for a single client call and
then scrapped.  The idea is to limit the use of the negotiated security
context.  The current code, however, isn't doing this: it is instead
restricting the socket to a single virtual connection and doing all the
calls over that.

This is changed such that the socket no longer maintains a special virtual
connection over which it will do all the calls, but rather gets a new one
each time a new exclusive call is made.

Further, using a socket option for this is a poor choice.  It should be
done on sendmsg with a control message marker instead so that calls can be
marked exclusive individually.  To that end, add RXRPC_EXCLUSIVE_CALL
which, if passed to sendmsg() as a control message element, will cause the
call to be done on an single-use connection.

The socket option (RXRPC_EXCLUSIVE_CONNECTION) still exists and, if set,
will override any lack of RXRPC_EXCLUSIVE_CALL being specified so that
programs using the setsockopt() will appear to work the same.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index efe6673deb28..4ca99445e0b7 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -37,6 +37,8 @@ struct rxrpc_crypt {
 #define rxrpc_queue_call(CALL)	rxrpc_queue_work(&(CALL)->processor)
 #define rxrpc_queue_conn(CONN)	rxrpc_queue_work(&(CONN)->processor)
 
+struct rxrpc_connection;
+
 /*
  * sk_state for RxRPC sockets
  */
@@ -57,7 +59,6 @@ struct rxrpc_sock {
 	struct sock		sk;
 	rxrpc_interceptor_t	interceptor;	/* kernel service Rx interceptor function */
 	struct rxrpc_local	*local;		/* local endpoint */
-	struct rxrpc_connection	*conn;		/* exclusive virtual connection */
 	struct list_head	listen_link;	/* link in the local endpoint's listen list */
 	struct list_head	secureq;	/* calls awaiting connection security clearance */
 	struct list_head	acceptq;	/* calls awaiting acceptance */
@@ -66,13 +67,13 @@ struct rxrpc_sock {
 	struct rb_root		calls;		/* outstanding calls on this socket */
 	unsigned long		flags;
 #define RXRPC_SOCK_CONNECTED		0	/* connect_srx is set */
-#define RXRPC_SOCK_EXCLUSIVE_CONN	1	/* exclusive connection for a client socket */
 	rwlock_t		call_lock;	/* lock for calls */
 	u32			min_sec_level;	/* minimum security level */
 #define RXRPC_SECURITY_MAX	RXRPC_SECURITY_ENCRYPT
+	bool			exclusive;	/* Exclusive connection for a client socket */
+	sa_family_t		family;		/* Protocol family created with */
 	struct sockaddr_rxrpc	srx;		/* local address */
 	struct sockaddr_rxrpc	connect_srx;	/* Default client address from connect() */
-	sa_family_t		family;		/* protocol family created with */
 };
 
 #define rxrpc_sk(__sk) container_of((__sk), struct rxrpc_sock, sk)