linux-stable/include/linux/mtio.h
Arnd Bergmann 1207045da5 compat_ioctl: move tape handling into drivers
MTIOCPOS and MTIOCGET are incompatible between 32-bit and 64-bit user
space, and traditionally have been translated in fs/compat_ioctl.c.

To get rid of that translation handler, move a corresponding
implementation into each of the four drivers implementing those commands.

The interesting part of that is now in a new linux/mtio.h header that
wraps the existing uapi/linux/mtio.h header and provides an abstraction
to let drivers handle both cases easily. Using an in_compat_syscall()
check, the caller does not have to keep track of whether this was
called through .unlocked_ioctl() or .compat_ioctl().

Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "Kai Mäkisara" <Kai.Makisara@kolumbus.fi>
Cc: linux-scsi@vger.kernel.org
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2019-10-23 17:23:44 +02:00

60 lines
1.3 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_MTIO_COMPAT_H
#define _LINUX_MTIO_COMPAT_H
#include <linux/compat.h>
#include <uapi/linux/mtio.h>
#include <linux/uaccess.h>
/*
* helper functions for implementing compat ioctls on the four tape
* drivers: we define the 32-bit layout of each incompatible structure,
* plus a wrapper function to copy it to user space in either format.
*/
struct mtget32 {
s32 mt_type;
s32 mt_resid;
s32 mt_dsreg;
s32 mt_gstat;
s32 mt_erreg;
s32 mt_fileno;
s32 mt_blkno;
};
#define MTIOCGET32 _IOR('m', 2, struct mtget32)
struct mtpos32 {
s32 mt_blkno;
};
#define MTIOCPOS32 _IOR('m', 3, struct mtpos32)
static inline int put_user_mtget(void __user *u, struct mtget *k)
{
struct mtget32 k32 = {
.mt_type = k->mt_type,
.mt_resid = k->mt_resid,
.mt_dsreg = k->mt_dsreg,
.mt_gstat = k->mt_gstat,
.mt_erreg = k->mt_erreg,
.mt_fileno = k->mt_fileno,
.mt_blkno = k->mt_blkno,
};
int ret;
if (in_compat_syscall())
ret = copy_to_user(u, &k32, sizeof(k32));
else
ret = copy_to_user(u, k, sizeof(*k));
return ret ? -EFAULT : 0;
}
static inline int put_user_mtpos(void __user *u, struct mtpos *k)
{
if (in_compat_syscall())
return put_user(k->mt_blkno, (u32 __user *)u);
else
return put_user(k->mt_blkno, (long __user *)u);
}
#endif