Merge tag 'rxrpc-fixes-20191220' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

David Howells says:

====================
rxrpc: Fixes

Here are a couple of bugfixes plus a patch that makes one of the bugfixes
easier:

(1) Move the ping and mutex unlock on a new call from rxrpc_input_packet()
into rxrpc_new_incoming_call(), which it calls. This means the
lock-unlock section is entirely within the latter function. This
simplifies patch (2).

(2) Don't take the call->user_mutex at all in the softirq path. Mutexes
aren't allowed to be taken or released there and a patch was merged
that caused a warning to be emitted every time this happened. Looking
at the code again, it looks like that taking the mutex isn't actually
necessary, as the value of call->state will block access to the call.

(3) Fix the incoming call path to check incoming calls earlier to reject
calls to RPC services for which we don't have a security key of the
appropriate class. This avoids an assertion failure if YFS tries
making a secure call to the kafs cache manager RPC service.
====================

Signed-off-by: David S. Miller <[e-mail]>

net/rxrpc/ar-internal.h

···
 struct rxrpc_security {
 	const char		*name;		/* name of this service */
 	u8			security_index;	/* security type provided */
+	u32			no_key_abort;	/* Abort code indicating no key */
 
 	/* Initialise a security service */
 	int (*init)(void);
···
 struct rxrpc_connection *rxrpc_find_service_conn_rcu(struct rxrpc_peer *,
 						     struct sk_buff *);
 struct rxrpc_connection *rxrpc_prealloc_service_connection(struct rxrpc_net *, gfp_t);
-void rxrpc_new_incoming_connection(struct rxrpc_sock *,
-				   struct rxrpc_connection *, struct sk_buff *);
+void rxrpc_new_incoming_connection(struct rxrpc_sock *, struct rxrpc_connection *,
+				   const struct rxrpc_security *, struct key *,
+				   struct sk_buff *);
 void rxrpc_unpublish_service_conn(struct rxrpc_connection *);
 
 /*
···
 int __init rxrpc_init_security(void);
 void rxrpc_exit_security(void);
 int rxrpc_init_client_conn_security(struct rxrpc_connection *);
-int rxrpc_init_server_conn_security(struct rxrpc_connection *);
+bool rxrpc_look_up_server_security(struct rxrpc_local *, struct rxrpc_sock *,
+				   const struct rxrpc_security **, struct key **,
+				   struct sk_buff *);
 
 /*
  * sendmsg.c

net/rxrpc/call_accept.c

···
 }
 
 /*
+ * Ping the other end to fill our RTT cache and to retrieve the rwind
+ * and MTU parameters.
+ */
+static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb)
+{
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+	ktime_t now = skb->tstamp;
+
+	if (call->peer->rtt_usage < 3 ||
+	    ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), now))
+		rxrpc_propose_ACK(call, RXRPC_ACK_PING, sp->hdr.serial,
+				  true, true,
+				  rxrpc_propose_ack_ping_for_params);
+}
+
+/*
  * Allocate a new incoming call from the prealloc pool, along with a connection
  * and a peer as necessary.
  */
···
 						    struct rxrpc_local *local,
 						    struct rxrpc_peer *peer,
 						    struct rxrpc_connection *conn,
+						    const struct rxrpc_security *sec,
+						    struct key *key,
 						    struct sk_buff *skb)
 {
 	struct rxrpc_backlog *b = rx->backlog;
···
 		conn->params.local = rxrpc_get_local(local);
 		conn->params.peer = peer;
 		rxrpc_see_connection(conn);
-		rxrpc_new_incoming_connection(rx, conn, skb);
+		rxrpc_new_incoming_connection(rx, conn, sec, key, skb);
 	} else {
 		rxrpc_get_connection(conn);
 	}
···
 					   struct sk_buff *skb)
 {
 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+	const struct rxrpc_security *sec = NULL;
 	struct rxrpc_connection *conn;
 	struct rxrpc_peer *peer = NULL;
-	struct rxrpc_call *call;
+	struct rxrpc_call *call = NULL;
+	struct key *key = NULL;
 
 	_enter("");
 
···
 				  sp->hdr.seq, RX_INVALID_OPERATION, ESHUTDOWN);
 		skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
 		skb->priority = RX_INVALID_OPERATION;
-		_leave(" = NULL [close]");
-		call = NULL;
-		goto out;
+		goto no_call;
 	}
 
 	/* The peer, connection and call may all have sprung into existence due
···
 	 */
 	conn = rxrpc_find_connection_rcu(local, skb, &peer);
 
-	call = rxrpc_alloc_incoming_call(rx, local, peer, conn, skb);
+	if (!conn && !rxrpc_look_up_server_security(local, rx, &sec, &key, skb))
+		goto no_call;
+
+	call = rxrpc_alloc_incoming_call(rx, local, peer, conn, sec, key, skb);
+	key_put(key);
 	if (!call) {
 		skb->mark = RXRPC_SKB_MARK_REJECT_BUSY;
-		_leave(" = NULL [busy]");
-		call = NULL;
-		goto out;
+		goto no_call;
 	}
 
 	trace_rxrpc_receive(call, rxrpc_receive_incoming,
 			    sp->hdr.serial, sp->hdr.seq);
-
-	/* Lock the call to prevent rxrpc_kernel_send/recv_data() and
-	 * sendmsg()/recvmsg() inconveniently stealing the mutex once the
-	 * notification is generated.
-	 *
-	 * The BUG should never happen because the kernel should be well
-	 * behaved enough not to access the call before the first notification
-	 * event and userspace is prevented from doing so until the state is
-	 * appropriate.
-	 */
-	if (!mutex_trylock(&call->user_mutex))
-		BUG();
 
 	/* Make the call live. */
 	rxrpc_incoming_call(rx, call, skb);
···
 		BUG();
 	}
 	spin_unlock(&conn->state_lock);
+	spin_unlock(&rx->incoming_lock);
+
+	rxrpc_send_ping(call, skb);
 
 	if (call->state == RXRPC_CALL_SERVER_ACCEPTING)
 		rxrpc_notify_socket(call);
···
 	rxrpc_put_call(call, rxrpc_call_put);
 
 	_leave(" = %p{%d}", call, call->debug_id);
-out:
-	spin_unlock(&rx->incoming_lock);
 	return call;
+
+no_call:
+	spin_unlock(&rx->incoming_lock);
+	_leave(" = NULL [%u]", skb->mark);
+	return NULL;
 }
 
 /*

net/rxrpc/conn_event.c

···
 	_enter("{%d}", conn->debug_id);
 
 	ASSERT(conn->security_ix != 0);
-
-	if (!conn->params.key) {
-		_debug("set up security");
-		ret = rxrpc_init_server_conn_security(conn);
-		switch (ret) {
-		case 0:
-			break;
-		case -ENOENT:
-			abort_code = RX_CALL_DEAD;
-			goto abort;
-		default:
-			abort_code = RXKADNOAUTH;
-			goto abort;
-		}
-	}
+	ASSERT(conn->server_key);
 
 	if (conn->security->issue_challenge(conn) < 0) {
 		abort_code = RX_CALL_DEAD;

net/rxrpc/conn_service.c

···
  */
 void rxrpc_new_incoming_connection(struct rxrpc_sock *rx,
 				   struct rxrpc_connection *conn,
+				   const struct rxrpc_security *sec,
+				   struct key *key,
 				   struct sk_buff *skb)
 {
 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
···
 	conn->service_id	= sp->hdr.serviceId;
 	conn->security_ix	= sp->hdr.securityIndex;
 	conn->out_clientflag	= 0;
+	conn->security		= sec;
+	conn->server_key	= key_get(key);
 	if (conn->security_ix)
 		conn->state	= RXRPC_CONN_SERVICE_UNSECURED;
 	else

net/rxrpc/input.c

···
 }
 
 /*
- * Ping the other end to fill our RTT cache and to retrieve the rwind
- * and MTU parameters.
- */
-static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb)
-{
-	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
-	ktime_t now = skb->tstamp;
-
-	if (call->peer->rtt_usage < 3 ||
-	    ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), now))
-		rxrpc_propose_ACK(call, RXRPC_ACK_PING, sp->hdr.serial,
-				  true, true,
-				  rxrpc_propose_ack_ping_for_params);
-}
-
-/*
  * Apply a hard ACK by advancing the Tx window.
  */
 static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
···
 		call = rxrpc_new_incoming_call(local, rx, skb);
 		if (!call)
 			goto reject_packet;
-		rxrpc_send_ping(call, skb);
-		mutex_unlock(&call->user_mutex);
 	}
 
 	/* Process a call packet; this either discards or passes on the ref

net/rxrpc/rxkad.c

···
 	u32 serial;
 	int ret;
 
-	_enter("{%d,%x}", conn->debug_id, key_serial(conn->params.key));
+	_enter("{%d,%x}", conn->debug_id, key_serial(conn->server_key));
 
-	ret = key_validate(conn->params.key);
+	ret = key_validate(conn->server_key);
 	if (ret < 0)
 		return ret;
 
···
 const struct rxrpc_security rxkad = {
 	.name				= "rxkad",
 	.security_index			= RXRPC_SECURITY_RXKAD,
+	.no_key_abort			= RXKADUNKNOWNKEY,
 	.init				= rxkad_init,
 	.exit				= rxkad_exit,
 	.init_connection_security	= rxkad_init_connection_security,

net/rxrpc/security.c

···
 }
 
 /*
- * initialise the security on a server connection
+ * Find the security key for a server connection.
  */
-int rxrpc_init_server_conn_security(struct rxrpc_connection *conn)
+bool rxrpc_look_up_server_security(struct rxrpc_local *local, struct rxrpc_sock *rx,
+				   const struct rxrpc_security **_sec,
+				   struct key **_key,
+				   struct sk_buff *skb)
 {
 	const struct rxrpc_security *sec;
-	struct rxrpc_local *local = conn->params.local;
-	struct rxrpc_sock *rx;
-	struct key *key;
-	key_ref_t kref;
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+	key_ref_t kref = NULL;
 	char kdesc[5 + 1 + 3 + 1];
 
 	_enter("");
 
-	sprintf(kdesc, "%u:%u", conn->service_id, conn->security_ix);
+	sprintf(kdesc, "%u:%u", sp->hdr.serviceId, sp->hdr.securityIndex);
 
-	sec = rxrpc_security_lookup(conn->security_ix);
+	sec = rxrpc_security_lookup(sp->hdr.securityIndex);
 	if (!sec) {
-		_leave(" = -ENOKEY [lookup]");
-		return -ENOKEY;
+		trace_rxrpc_abort(0, "SVS",
+				  sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
+				  RX_INVALID_OPERATION, EKEYREJECTED);
+		skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
+		skb->priority = RX_INVALID_OPERATION;
+		return false;
 	}
 
-	/* find the service */
-	read_lock(&local->services_lock);
-	rx = rcu_dereference_protected(local->service,
-				       lockdep_is_held(&local->services_lock));
-	if (rx && (rx->srx.srx_service == conn->service_id ||
-		   rx->second_service == conn->service_id))
-		goto found_service;
+	if (sp->hdr.securityIndex == RXRPC_SECURITY_NONE)
+		goto out;
 
-	/* the service appears to have died */
-	read_unlock(&local->services_lock);
-	_leave(" = -ENOENT");
-	return -ENOENT;
-
-found_service:
 	if (!rx->securities) {
-		read_unlock(&local->services_lock);
-		_leave(" = -ENOKEY");
-		return -ENOKEY;
+		trace_rxrpc_abort(0, "SVR",
+				  sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
+				  RX_INVALID_OPERATION, EKEYREJECTED);
+		skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
+		skb->priority = RX_INVALID_OPERATION;
+		return false;
 	}
 
 	/* look through the service's keyring */
 	kref = keyring_search(make_key_ref(rx->securities, 1UL),
 			      &key_type_rxrpc_s, kdesc, true);
 	if (IS_ERR(kref)) {
-		read_unlock(&local->services_lock);
-		_leave(" = %ld [search]", PTR_ERR(kref));
-		return PTR_ERR(kref);
+		trace_rxrpc_abort(0, "SVK",
+				  sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
+				  sec->no_key_abort, EKEYREJECTED);
+		skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
+		skb->priority = sec->no_key_abort;
+		return false;
 	}
 
-	key = key_ref_to_ptr(kref);
-	read_unlock(&local->services_lock);
-
-	conn->server_key = key;
-	conn->security = sec;
-
-	_leave(" = 0");
-	return 0;
+out:
+	*_sec = sec;
+	*_key = key_ref_to_ptr(kref);
+	return true;
 }