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author | Brian Norris <computersforpeace@gmail.com> | 2015-09-21 20:26:59 (GMT) |
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committer | Brian Norris <computersforpeace@gmail.com> | 2015-09-29 20:37:04 (GMT) |
commit | 53bb724f94f57b67213e08a4c155c8c5eb74c644 (patch) | |
tree | 3acf74aec5e263a96c6f8a43161a8264d5ee0ed2 /drivers/mtd/mtdchar.c | |
parent | 4404bd742db767a7f316b1207c46a04a38ca7198 (diff) | |
download | linux-53bb724f94f57b67213e08a4c155c8c5eb74c644.tar.xz |
mtd: provide proper 32/64-bit compat_ioctl() support for BLKPG
After a bit of poking around wondering why my 32-bit user-space can't
seem to send a proper ioctl(BLKPG) to an MTD on my 64-bit kernel
(ARM64), I noticed that struct blkpg_ioctl_arg is actually pretty
unsuitable for use in the ioctl() ABI, due to its use of raw pointers,
and its lack of alignment/packing restrictions (32-bit arch'es tend to
pack the 4 fields into 4 32-bit words, whereas 64-bit arch'es would add
padding after the third int, and make this 6 32-bit words).
Anyway, this means BLKPG deserves some special compat_ioctl handling. Do
the conversion in a small shim for MTD.
block/compat_ioctl.c already has compat support for the block subsystem,
but it does so by a re-marshalling data to/from user-space (see
compat_blkpg_ioctl()). Personally, I think this approach is cleaner.
Tested only on MTD, with an ARM32 user space on an ARM64 kernel.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Diffstat (limited to 'drivers/mtd/mtdchar.c')
-rw-r--r-- | drivers/mtd/mtdchar.c | 42 |
1 files changed, 33 insertions, 9 deletions
diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c index 55fa27e..6d19835 100644 --- a/drivers/mtd/mtdchar.c +++ b/drivers/mtd/mtdchar.c @@ -498,21 +498,17 @@ static int shrink_ecclayout(const struct nand_ecclayout *from, } static int mtdchar_blkpg_ioctl(struct mtd_info *mtd, - struct blkpg_ioctl_arg __user *arg) + struct blkpg_ioctl_arg *arg) { - struct blkpg_ioctl_arg a; struct blkpg_partition p; if (!capable(CAP_SYS_ADMIN)) return -EPERM; - if (copy_from_user(&a, arg, sizeof(struct blkpg_ioctl_arg))) + if (copy_from_user(&p, arg->data, sizeof(p))) return -EFAULT; - if (copy_from_user(&p, a.data, sizeof(struct blkpg_partition))) - return -EFAULT; - - switch (a.op) { + switch (arg->op) { case BLKPG_ADD_PARTITION: /* Only master mtd device must be used to add partitions */ @@ -966,8 +962,13 @@ static int mtdchar_ioctl(struct file *file, u_int cmd, u_long arg) case BLKPG: { - ret = mtdchar_blkpg_ioctl(mtd, - (struct blkpg_ioctl_arg __user *)arg); + struct blkpg_ioctl_arg __user *blk_arg = argp; + struct blkpg_ioctl_arg a; + + if (copy_from_user(&a, blk_arg, sizeof(a))) + ret = -EFAULT; + else + ret = mtdchar_blkpg_ioctl(mtd, &a); break; } @@ -1046,6 +1047,29 @@ static long mtdchar_compat_ioctl(struct file *file, unsigned int cmd, &buf_user->start); break; } + + case BLKPG: + { + /* Convert from blkpg_compat_ioctl_arg to blkpg_ioctl_arg */ + struct blkpg_compat_ioctl_arg __user *uarg = argp; + struct blkpg_compat_ioctl_arg compat_arg; + struct blkpg_ioctl_arg a; + + if (copy_from_user(&compat_arg, uarg, sizeof(compat_arg))) { + ret = -EFAULT; + break; + } + + memset(&a, 0, sizeof(a)); + a.op = compat_arg.op; + a.flags = compat_arg.flags; + a.datalen = compat_arg.datalen; + a.data = compat_ptr(compat_arg.data); + + ret = mtdchar_blkpg_ioctl(mtd, &a); + break; + } + default: ret = mtdchar_ioctl(file, cmd, (unsigned long)argp); } |