linux-kernel - Re: [Patch] allow file truncations when both suid and write permissions set

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Message-ID: <4A4C887F.2050508@redhat.com>
Date:	Thu, 02 Jul 2009 18:14:23 +0800
From:	Amerigo Wang <amwang@...hat.com>
To:	Eric Paris <eparis@...hat.com>
CC:	Eric Sandeen <sandeen@...hat.com>, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, Eugene Teo <eteo@...hat.com>,
	viro@...iv.linux.org.uk
Subject: Re: [Patch] allow file truncations when both suid and write  permissions
 set

Eric Paris wrote:
> So NAK on both Amerigo's and Eric's patch.  ATTR_FORCE is wrong.
> ATTR_FORCE here is going to force the security system to accept ALL of
> the attr changes, not just the ATTR_KILL_SUID and/or ATTR_KILL_SGID you
> |= in from should_remove_suid.
> You need to follow esandeen's recommendation, change file_remove_suid()
> to dentry_remove_suid() and then use dentry_remove_suid() in do_truncate
> instead of what you are currently trying to do (and I think that's
> supposed to be done under the i_mutex right?)
>   
But file_remove_suid() actually adds ATTR_FORCE too, in __remove_suid()...

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