Re: [Patch 1/2] selinux: ajust rules for ATTR_FORCE

[OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>]

Stephen Smalley <sds@tycho.nsa.gov> writes:

>> [I'm still not sure what selinux want to do. normally inode_permission()
>> should check truncate() permission, and this FILE__SIZE checks something
>> again...? And we want to check FILE__WRITE for ATTR_[AMC]TIME?]
>
> Explicit setting of mode, owner, group, or timestamps is to be checked
> by the setattr permission, while implicit setting of timestamps or size
> is mediated by the write permission.

E.g. mode change has implicit ATTR_CTIME change. So it meant, we should
check the both of FILE__SETATTR and FILE__WRITE?

> ATTR_FORCE is supposed to suppress permission checking altogether, and
> shouldn't be mixed with multiple attribute changes if some should be
> subject to permission checks while others should not.

I disagree. In fact, ATTR_FORCE is just used for ATTR_KILL_S[UG]ID, and
notify_change() is disallowing the mixed ATTR_MODE and ATTR_KILL_*. I
think it should be enough.

If ATTR_FORCE is confusable, I think we can just add new ATTR_FORCE_MODE
or ATTR_FORCE_KILL, and replace with current ATTR_FORCE. I'm ok either
way.  But, with this change, ATTR_FORCE has no users.

Thanks.
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>