linux-kernel - Re: [PATCH 6/X] uprobes: reimplement xol_add_vma() via install_special

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Message-ID: <20111017185526.GA9244@redhat.com>
Date:	Mon, 17 Oct 2011 20:55:26 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Stephen Smalley <sds@...ho.nsa.gov>
Cc:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Eric Paris <eparis@...isplace.org>,
	Ingo Molnar <mingo@...e.hu>,
	Steven Rostedt <rostedt@...dmis.org>,
	Linux-mm <linux-mm@...ck.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Hugh Dickins <hughd@...gle.com>,
	Christoph Hellwig <hch@...radead.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andi Kleen <andi@...stfloor.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jim Keniston <jkenisto@...ux.vnet.ibm.com>,
	Roland McGrath <roland@...k.frob.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 6/X] uprobes: reimplement xol_add_vma() via
	install_special_mapping()

On 10/17, Stephen Smalley wrote:
>
> > Since selinux wasnt happy to have an anonymous vma attached, we would
> > create a pseudo file using shmem_file_setup. However after comments from
> > Peter and Stephan's suggestions we started using override_creds. Peter and
> > Oleg suggest that we use install_special_mapping.
> >
> > Are you okay with using install_special_mapping instead of
> > override_creds()?
>
> That's fine with me.

Good.

> But I'm still not clear on how you are controlling
> the use of this facility from userspace, which is my primary concern.

Yes, but just in case... Any security check in xol_add_vma() is pointless.
The task is already "owned" by uprobes when xol_add_vma() is called.

Oleg.

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