diff options
| author | Arnd Bergmann <arnd@arndb.de> | 2018-09-11 16:55:03 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-12-17 19:55:30 +0100 |
| commit | 8896dd968b8b2422800c63626268e37d04e1d3e6 (patch) | |
| tree | 1459be756f2ca080c697b412fc2277ca0ca89171 /include/linux | |
| parent | 402f7198311f84a8b56183923532f57a3cc1b63f (diff) | |
compat_ioctl: add compat_ptr_ioctl()
commit 2952db0fd51b0890f728df94ac563c21407f4f43 upstream.
Many drivers have ioctl() handlers that are completely compatible between
32-bit and 64-bit architectures, except for the argument that is passed
down from user space and may have to be passed through compat_ptr()
in order to become a valid 64-bit pointer.
Using ".compat_ptr = compat_ptr_ioctl" in file operations should let
us simplify a lot of those drivers to avoid #ifdef checks, and convert
additional drivers that don't have proper compat handling yet.
On most architectures, the compat_ptr_ioctl() just passes all arguments
to the corresponding ->ioctl handler. The exception is arch/s390, where
compat_ptr() clears the top bit of a 32-bit pointer value, so user space
pointers to the second 2GB alias the first 2GB, as is the case for native
32-bit s390 user space.
The compat_ptr_ioctl() function must therefore be used only with
ioctl functions that either ignore the argument or pass a pointer to a
compatible data type.
If any ioctl command handled by fops->unlocked_ioctl passes a plain
integer instead of a pointer, or any of the passed data types is
incompatible between 32-bit and 64-bit architectures, a proper handler
is required instead of compat_ptr_ioctl.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/fs.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index e0d909d35763..0b4d8fc79e0f 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1727,6 +1727,13 @@ int vfs_mkobj(struct dentry *, umode_t, extern long vfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg); +#ifdef CONFIG_COMPAT +extern long compat_ptr_ioctl(struct file *file, unsigned int cmd, + unsigned long arg); +#else +#define compat_ptr_ioctl NULL +#endif + /* * VFS file helper functions. */ |