rxrpc: Support keys with multiple authentication tokens

rxrpc-type keys can have multiple tokens attached for different security
classes.  Currently, rxrpc always picks the first one, whether or not the
security class it indicates is supported.

Add preliminary support for choosing which security class will be used
(this will need to be directed from a higher layer) and go through the
tokens to find one that's supported.
Signed-off-by: David Howells <dhowells@redhat.com>

net/rxrpc/ar-internal.h

@@ -12,6 +12,7 @@
 #include <net/netns/generic.h>
 #include <net/sock.h>
 #include <net/af_rxrpc.h>
+#include <keys/rxrpc-type.h>
 #include "protocol.h"
 
 #if 0
@@ -217,7 +218,8 @@ struct rxrpc_security {
 	void (*exit)(void);
 
 	/* initialise a connection's security */
-	int (*init_connection_security)(struct rxrpc_connection *);
+	int (*init_connection_security)(struct rxrpc_connection *,
+					struct rxrpc_key_token *);
 
 	/* prime a connection's packet security */
 	int (*prime_packet_security)(struct rxrpc_connection *);

net/rxrpc/conn_event.c

@@ -333,7 +333,8 @@ static int rxrpc_process_event(struct rxrpc_connection *conn,
 		if (ret < 0)
 			return ret;
 
-		ret = conn->security->init_connection_security(conn);
+		ret = conn->security->init_connection_security(
+			conn, conn->params.key->payload.data[0]);
 		if (ret < 0)
 			return ret;
 

net/rxrpc/insecure.c

@@ -8,7 +8,8 @@
 #include <net/af_rxrpc.h>
 #include "ar-internal.h"
 
-static int none_init_connection_security(struct rxrpc_connection *conn)
+static int none_init_connection_security(struct rxrpc_connection *conn,
+					 struct rxrpc_key_token *token)
 {
 	return 0;
 }

net/rxrpc/rxkad.c

@@ -49,15 +49,14 @@ static DEFINE_MUTEX(rxkad_ci_mutex);
 /*
  * initialise connection security
  */
-static int rxkad_init_connection_security(struct rxrpc_connection *conn)
+static int rxkad_init_connection_security(struct rxrpc_connection *conn,
+					  struct rxrpc_key_token *token)
 {
 	struct crypto_sync_skcipher *ci;
-	struct rxrpc_key_token *token;
 	int ret;
 
 	_enter("{%d},{%x}", conn->debug_id, key_serial(conn->params.key));
 
-	token = conn->params.key->payload.data[0];
 	conn->security_ix = token->security_index;
 
 	ci = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0);

net/rxrpc/security.c

@@ -81,16 +81,17 @@ int rxrpc_init_client_conn_security(struct rxrpc_connection *conn)
 	if (ret < 0)
 		return ret;
 
-	token = key->payload.data[0];
-	if (!token)
-		return -EKEYREJECTED;
+	for (token = key->payload.data[0]; token; token = token->next) {
+		sec = rxrpc_security_lookup(token->security_index);
+		if (sec)
+			goto found;
+	}
+	return -EKEYREJECTED;
 
-	sec = rxrpc_security_lookup(token->security_index);
-	if (!sec)
-		return -EKEYREJECTED;
+found:
 	conn->security = sec;
 
-	ret = conn->security->init_connection_security(conn);
+	ret = conn->security->init_connection_security(conn, token);
 	if (ret < 0) {
 		conn->security = &rxrpc_no_security;
 		return ret;