Unprivileged users should not be able to mount mtd block devices
when they lack sufficient privileges towards the block device
inode. Update mount_mtd() to validate that the user has the
required access to the inode at the specified path. The check
will be skipped for CAP_SYS_ADMIN, so privileged mounts will
continue working as before.
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
#ifdef CONFIG_BLOCK
struct block_device *bdev;
int ret, major;
+ int perm;
#endif
int mtdnr;
/* try the old way - the hack where we allowed users to mount
* /dev/mtdblock$(n) but didn't actually _use_ the blockdev
*/
- bdev = lookup_bdev(dev_name, 0);
+ perm = MAY_READ;
+ if (!(flags & MS_RDONLY))
+ perm |= MAY_WRITE;
+ bdev = lookup_bdev(dev_name, perm);
if (IS_ERR(bdev)) {
ret = PTR_ERR(bdev);
pr_debug("MTDSB: lookup_bdev() returned %d\n", ret);