dm ioctl: introduce ioctl_flags

This patch introduces flags for each ioctl function. So far, one flag is defined, IOCTL_FLAGS_NO_PARAMS. It is set if the function processing the ioctl doesn't take or produce any parameters in the section of the data buffer that has a variable size. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>

dm ioctl: introduce ioctl_flags
This patch introduces flags for each ioctl function. So far, one flag is defined, IOCTL_FLAGS_NO_PARAMS. It is set if the function processing the ioctl doesn't take or produce any parameters in the section of the data buffer that has a variable size. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Mikulas Patocka · Alasdair G Kergon
1 parent 5f01520415
Showing 1 changed file with 41 additions and 23 deletions Side-by-side Diff
drivers/md/dm-ioctl.c
@@ -1478,39 +1478,52 @@
 	return r;
 }
  
+/*
+ * The ioctl parameter block consists of two parts, a dm_ioctl struct
+ * followed by a data buffer.  This flag is set if the second part,
+ * which has a variable size, is not used by the function processing
+ * the ioctl.
+ */
+#define IOCTL_FLAGS_NO_PARAMS	1
+
 /*-----------------------------------------------------------------
  * Implementation of open/close/ioctl on the special char
  * device.
  *---------------------------------------------------------------*/
-static ioctl_fn lookup_ioctl(unsigned int cmd)
+static ioctl_fn lookup_ioctl(unsigned int cmd, int *ioctl_flags)
 {
 	static struct {
 		int cmd;
+		int flags;
 		ioctl_fn fn;
 	} _ioctls[] = {
-		{DM_VERSION_CMD, NULL},	/* version is dealt with elsewhere */
-		{DM_REMOVE_ALL_CMD, remove_all},
-		{DM_LIST_DEVICES_CMD, list_devices},
+		{DM_VERSION_CMD, 0, NULL}, /* version is dealt with elsewhere */
+		{DM_REMOVE_ALL_CMD, IOCTL_FLAGS_NO_PARAMS, remove_all},
+		{DM_LIST_DEVICES_CMD, 0, list_devices},
  
-		{DM_DEV_CREATE_CMD, dev_create},
-		{DM_DEV_REMOVE_CMD, dev_remove},
-		{DM_DEV_RENAME_CMD, dev_rename},
-		{DM_DEV_SUSPEND_CMD, dev_suspend},
-		{DM_DEV_STATUS_CMD, dev_status},
-		{DM_DEV_WAIT_CMD, dev_wait},
+		{DM_DEV_CREATE_CMD, IOCTL_FLAGS_NO_PARAMS, dev_create},
+		{DM_DEV_REMOVE_CMD, IOCTL_FLAGS_NO_PARAMS, dev_remove},
+		{DM_DEV_RENAME_CMD, 0, dev_rename},
+		{DM_DEV_SUSPEND_CMD, IOCTL_FLAGS_NO_PARAMS, dev_suspend},
+		{DM_DEV_STATUS_CMD, IOCTL_FLAGS_NO_PARAMS, dev_status},
+		{DM_DEV_WAIT_CMD, 0, dev_wait},
  
-		{DM_TABLE_LOAD_CMD, table_load},
-		{DM_TABLE_CLEAR_CMD, table_clear},
-		{DM_TABLE_DEPS_CMD, table_deps},
-		{DM_TABLE_STATUS_CMD, table_status},
+		{DM_TABLE_LOAD_CMD, 0, table_load},
+		{DM_TABLE_CLEAR_CMD, IOCTL_FLAGS_NO_PARAMS, table_clear},
+		{DM_TABLE_DEPS_CMD, 0, table_deps},
+		{DM_TABLE_STATUS_CMD, 0, table_status},
  
-		{DM_LIST_VERSIONS_CMD, list_versions},
+		{DM_LIST_VERSIONS_CMD, 0, list_versions},
  
-		{DM_TARGET_MSG_CMD, target_message},
-		{DM_DEV_SET_GEOMETRY_CMD, dev_set_geometry}
+		{DM_TARGET_MSG_CMD, 0, target_message},
+		{DM_DEV_SET_GEOMETRY_CMD, 0, dev_set_geometry}
 	};
  
-	return (cmd >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[cmd].fn;
+	if (unlikely(cmd >= ARRAY_SIZE(_ioctls)))
+		return NULL;
+
+	*ioctl_flags = _ioctls[cmd].flags;
+	return _ioctls[cmd].fn;
 }
  
 /*
@@ -1652,6 +1665,7 @@
 static int ctl_ioctl(uint command, struct dm_ioctl __user *user)
 {
 	int r = 0;
+	int ioctl_flags;
 	int param_flags;
 	unsigned int cmd;
 	struct dm_ioctl *uninitialized_var(param);
@@ -1681,7 +1695,7 @@
 	if (cmd == DM_VERSION_CMD)
 		return 0;
  
-	fn = lookup_ioctl(cmd);
+	fn = lookup_ioctl(cmd, &ioctl_flags);
 	if (!fn) {
 		DMWARN("dm_ctl_ioctl: unknown command 0x%x", command);
 		return -ENOTTY;
@@ -1702,6 +1716,10 @@
  
 	param->data_size = sizeof(*param);
 	r = fn(param, input_param_size);
+
+	if (unlikely(param->flags & DM_BUFFER_FULL_FLAG) &&
+	    unlikely(ioctl_flags & IOCTL_FLAGS_NO_PARAMS))
+		DMERR("ioctl %d tried to output some data but has IOCTL_FLAGS_NO_PARAMS set", cmd);
  
 	/*
 	 * Copy the results back to userland.
...	...	@@ -1478,39 +1478,52 @@
1478	1478	return r;
1479	1479	}
1480	1480
	1481	+/*
	1482	+ * The ioctl parameter block consists of two parts, a dm_ioctl struct
	1483	+ * followed by a data buffer. This flag is set if the second part,
	1484	+ * which has a variable size, is not used by the function processing
	1485	+ * the ioctl.
	1486	+ */
	1487	+#define IOCTL_FLAGS_NO_PARAMS 1
	1488	+
1481	1489	/*-----------------------------------------------------------------
1482	1490	* Implementation of open/close/ioctl on the special char
1483	1491	* device.
1484	1492	---------------------------------------------------------------/
1485		-static ioctl_fn lookup_ioctl(unsigned int cmd)
	1493	+static ioctl_fn lookup_ioctl(unsigned int cmd, int *ioctl_flags)
1486	1494	{
1487	1495	static struct {
1488	1496	int cmd;
	1497	+ int flags;
1489	1498	ioctl_fn fn;
1490	1499	} _ioctls[] = {
1491		- {DM_VERSION_CMD, NULL}, /* version is dealt with elsewhere */
1492		- {DM_REMOVE_ALL_CMD, remove_all},
1493		- {DM_LIST_DEVICES_CMD, list_devices},
	1500	+ {DM_VERSION_CMD, 0, NULL}, /* version is dealt with elsewhere */
	1501	+ {DM_REMOVE_ALL_CMD, IOCTL_FLAGS_NO_PARAMS, remove_all},
	1502	+ {DM_LIST_DEVICES_CMD, 0, list_devices},
1494	1503
1495		- {DM_DEV_CREATE_CMD, dev_create},
1496		- {DM_DEV_REMOVE_CMD, dev_remove},
1497		- {DM_DEV_RENAME_CMD, dev_rename},
1498		- {DM_DEV_SUSPEND_CMD, dev_suspend},
1499		- {DM_DEV_STATUS_CMD, dev_status},
1500		- {DM_DEV_WAIT_CMD, dev_wait},
	1504	+ {DM_DEV_CREATE_CMD, IOCTL_FLAGS_NO_PARAMS, dev_create},
	1505	+ {DM_DEV_REMOVE_CMD, IOCTL_FLAGS_NO_PARAMS, dev_remove},
	1506	+ {DM_DEV_RENAME_CMD, 0, dev_rename},
	1507	+ {DM_DEV_SUSPEND_CMD, IOCTL_FLAGS_NO_PARAMS, dev_suspend},
	1508	+ {DM_DEV_STATUS_CMD, IOCTL_FLAGS_NO_PARAMS, dev_status},
	1509	+ {DM_DEV_WAIT_CMD, 0, dev_wait},
1501	1510
1502		- {DM_TABLE_LOAD_CMD, table_load},
1503		- {DM_TABLE_CLEAR_CMD, table_clear},
1504		- {DM_TABLE_DEPS_CMD, table_deps},
1505		- {DM_TABLE_STATUS_CMD, table_status},
	1511	+ {DM_TABLE_LOAD_CMD, 0, table_load},
	1512	+ {DM_TABLE_CLEAR_CMD, IOCTL_FLAGS_NO_PARAMS, table_clear},
	1513	+ {DM_TABLE_DEPS_CMD, 0, table_deps},
	1514	+ {DM_TABLE_STATUS_CMD, 0, table_status},
1506	1515
1507		- {DM_LIST_VERSIONS_CMD, list_versions},
	1516	+ {DM_LIST_VERSIONS_CMD, 0, list_versions},
1508	1517
1509		- {DM_TARGET_MSG_CMD, target_message},
1510		- {DM_DEV_SET_GEOMETRY_CMD, dev_set_geometry}
	1518	+ {DM_TARGET_MSG_CMD, 0, target_message},
	1519	+ {DM_DEV_SET_GEOMETRY_CMD, 0, dev_set_geometry}
1511	1520	};
1512	1521
1513		- return (cmd >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[cmd].fn;
	1522	+ if (unlikely(cmd >= ARRAY_SIZE(_ioctls)))
	1523	+ return NULL;
	1524	+
	1525	+ *ioctl_flags = _ioctls[cmd].flags;
	1526	+ return _ioctls[cmd].fn;
1514	1527	}
1515	1528
1516	1529	/*
...	...	@@ -1652,6 +1665,7 @@
1652	1665	static int ctl_ioctl(uint command, struct dm_ioctl __user *user)
1653	1666	{
1654	1667	int r = 0;
	1668	+ int ioctl_flags;
1655	1669	int param_flags;
1656	1670	unsigned int cmd;
1657	1671	struct dm_ioctl *uninitialized_var(param);
...	...	@@ -1681,7 +1695,7 @@
1681	1695	if (cmd == DM_VERSION_CMD)
1682	1696	return 0;
1683	1697
1684		- fn = lookup_ioctl(cmd);
	1698	+ fn = lookup_ioctl(cmd, &ioctl_flags);
1685	1699	if (!fn) {
1686	1700	DMWARN("dm_ctl_ioctl: unknown command 0x%x", command);
1687	1701	return -ENOTTY;
...	...	@@ -1702,6 +1716,10 @@
1702	1716
1703	1717	param->data_size = sizeof(*param);
1704	1718	r = fn(param, input_param_size);
	1719	+
	1720	+ if (unlikely(param->flags & DM_BUFFER_FULL_FLAG) &&
	1721	+ unlikely(ioctl_flags & IOCTL_FLAGS_NO_PARAMS))
	1722	+ DMERR("ioctl %d tried to output some data but has IOCTL_FLAGS_NO_PARAMS set", cmd);
1705	1723
1706	1724	/*
1707	1725	* Copy the results back to userland.