Commit ee6a129d authored by Arnd Bergmann's avatar Arnd Bergmann
Browse files

compat_ioctl: block: add blkdev_compat_ptr_ioctl 



A lot of block drivers need only a trivial .compat_ioctl callback.

Add a helper function that can be set as the callback pointer
to only convert the argument using the compat_ptr() conversion
and otherwise assume all input and output data is compatible,
or handled using in_compat_syscall() checks.

This mirrors the compat_ptr_ioctl() helper function used in
character devices.

Reviewed-by: default avatarBen Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
parent 78ed001d

block/ioctl.c

+21 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <linux/capability.h>

#include <linux/compat.h>

#include <linux/blkdev.h>

#include <linux/export.h>

#include <linux/gfp.h>
@@ -285,6 +286,26 @@ int __blkdev_driver_ioctl(struct block_device *bdev, fmode_t mode, 
 */

EXPORT_SYMBOL_GPL(__blkdev_driver_ioctl);



#ifdef CONFIG_COMPAT

/*

 * This is the equivalent of compat_ptr_ioctl(), to be used by block

 * drivers that implement only commands that are completely compatible

 * between 32-bit and 64-bit user space

 */

int blkdev_compat_ptr_ioctl(struct block_device *bdev, fmode_t mode,

			unsigned cmd, unsigned long arg)

{

	struct gendisk *disk = bdev->bd_disk;



	if (disk->fops->ioctl)

		return disk->fops->ioctl(bdev, mode, cmd,

					 (unsigned long)compat_ptr(arg));



	return -ENOIOCTLCMD;

}

EXPORT_SYMBOL(blkdev_compat_ptr_ioctl);

#endif



static int blkdev_pr_register(struct block_device *bdev,

		struct pr_registration __user *arg)

{

include/linux/blkdev.h

+7 −0
Original line number Diff line number Diff line
@@ -1711,6 +1711,13 @@ struct block_device_operations { 
	const struct pr_ops *pr_ops;

};



#ifdef CONFIG_COMPAT

extern int blkdev_compat_ptr_ioctl(struct block_device *, fmode_t,

				      unsigned int, unsigned long);

#else

#define blkdev_compat_ptr_ioctl NULL

#endif



extern int __blkdev_driver_ioctl(struct block_device *, fmode_t, unsigned int,

				 unsigned long);

extern int bdev_read_page(struct block_device *, sector_t, struct page *);

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