Jan Engelhardt <[email protected]> writes:
> On Aug 21 2007 00:17, OGAWA Hirofumi wrote:
>>Jan Engelhardt <[email protected]> writes:
>>> when a vfat filesystem is mounted without the quiet option, chown fails,
>>> but chmod still succeeds. I think that is wrong.
>>
>>Could you explain why this is wrong more?
>
> Suppose a vfat filesystem is mounted with umask=0 and [not-quiet].
> Then all files will have mode 0777. Trying to change the owner will
> fail, because fat does not know about owners or groups. chmod 0770,
> on the other hand, will succeed, even though fat does not know about
> the permission triplet [user/group/other].
>
> So this patch changes fat's not-quiet behavior so that only UNIX
> modes are accepted that can be mapped lossless between the fat disk
> format and the local system. There is only one attribute, and that is
> the readonly attribute, which is mapped to the UNIX write permission
> bit(s). chmod 0555 is therefore valid (taking away the +w bits <=>
> setting the readonly attribute). Since chmod 0775 and chmod 0755 is
> an ambiguous case as to whether to set or clear the readonly bit,
> these modes are also denied.
I see. Sounds sane. We would be able to see what happen in real world.
However, implementation is really right?
> @@ -186,16 +222,19 @@ int fat_notify_change(struct dentry *den
> if (((attr->ia_valid & ATTR_UID) &&
> (attr->ia_uid != sbi->options.fs_uid)) ||
> ((attr->ia_valid & ATTR_GID) &&
> - (attr->ia_gid != sbi->options.fs_gid)) ||
> - ((attr->ia_valid & ATTR_MODE) &&
> - (attr->ia_mode & ~MSDOS_VALID_MODE)))
> + (attr->ia_gid != sbi->options.fs_gid)))
> error = -EPERM;
> -
> if (error) {
> if (sbi->options.quiet)
> error = 0;
> goto out;
> }
> +
> + if (error == 0 && (attr->ia_valid & ATTR_MODE))
> + if ((error = check_mode(sbi, attr->ia_mode)) != 0 &&
> + sbi->options.quiet)
> + error = 0;
This test is really here? The error is always "0", and it seems
anybody doesn't check after that.
And please separate the check like following
error = check_mode(sbi, attr->ia_mode);
if (error && sbi->options.quiet)
error = 0;
> error = inode_setattr(inode, attr);
> if (error)
> goto out;
--
OGAWA Hirofumi <[email protected]>
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