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Date: Mon, 17 Oct 2011 20:55:26 +0200
From: Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH 6/X] uprobes: reimplement xol_add_vma() via
	install_special_mapping()
Message-ID: <20111017185526.GA9244@redhat.com>
References: <20110920115938.25326.93059.sendpatchset@srdronam.in.ibm.com> <20111015190007.GA30243@redhat.com> <20111016161359.GA24893@redhat.com> <20111017105054.GC11831@linux.vnet.ibm.com> <1318858455.7251.12.camel@moss-pluto>
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To: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>, Peter Zijlstra <peterz@infradead.org>, Eric Paris <eparis@parisplace.org>, Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>, Linux-mm <linux-mm@kvack.org>, Linus Torvalds <torvalds@linux-foundation.org>, Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>, Hugh Dickins <hughd@google.com>, Christoph Hellwig <hch@infradead.org>, Ananth N Mavinakayanahalli <ananth@in.ibm.com>, Thomas Gleixner <tglx@linutronix.de>, Andi Kleen <andi@firstfloor.org>, Andrew Morton <akpm@linux-foundation.org>, Jim Keniston <jkenisto@linux.vnet.ibm.com>, Roland McGrath <roland@hack.frob.com>, LKML <linux-kernel@vger.kernel.org>

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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