linux-kernel - Re: [RFC PATCH 0/3] move the secure

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Message-Id: <20120524150057.86c14b35.akpm@linux-foundation.org>
Date:	Thu, 24 May 2012 15:00:57 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Will Drewry <wad@...omium.org>
Cc:	linux-kernel@...r.kernel.org, mcgrathr@...gle.com, hpa@...or.com,
	indan@....nu, netdev@...isplace.org,
	linux-security-module@...r.kernel.org,
	kernel-hardening@...ts.openwall.com, mingo@...hat.com,
	oleg@...hat.com, peterz@...radead.org, rdunlap@...otime.net,
	tglx@...utronix.de, luto@....edu, serge.hallyn@...onical.com,
	pmoore@...hat.com, corbet@....net, markus@...omium.org,
	coreyb@...ux.vnet.ibm.com, keescook@...omium.org,
	viro@...iv.linux.org.uk, jmorris@...ei.org
Subject: Re: [RFC PATCH 0/3] move the secure_computing call

On Thu, 24 May 2012 11:07:58 -0500
Will Drewry <wad@...omium.org> wrote:

> This is an RFC based on the comments from Al Viro and Eric Paris
> regarding ptrace()rs being able to change the system call the kernel
> sees after the seccomp enforcement has occurred (for mode 1 or 2).

Perhaps you could repeat those comments in this changelog.

> With this series applied, a (p)tracer of a process with seccomp enabled
> will be unable to change the tracee's system call number after the
> secure computing check has been performed.
> 
> The x86 change is tested, as is the seccomp.c change.  For other arches,
> it is not (RFC :).  Given that there are other inconsistencies in this
> code across architectures, I'm not sure if it makes sense to attempt to
> fix them all at once or to roll through as I attempt to add seccomp
> filter support.
> 
> As is, the biggest benefit of this change is just setting consistent
> expectations in what the ptrace/seccomp interactions should be.  The
> current ability for ptrace to "bypass" secure computing (by remapping
> allowed system calls) is not necessarily a problem, but it is not
> necessarily intuitive behavior.
> 

Because my take on the above reasoning is "why did you bother writing
these patches"!

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