Date: Thu, 24 May 2012 20:55:09 -0500 From: Will Drewry <wad@...omium.org> To: Andrew Morton <akpm@...ux-foundation.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, May 24, 2012 at 5:00 PM, Andrew Morton <akpm@...ux-foundation.org> wrote: > 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. Oops :) Here's the context -- https://lkml.org/lkml/2012/5/21/326 I doubt there's need for a repost though. >> 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"! Just to be thorough -- I wanted to make sure the discussion was framed against actual code just in case I was missing something. Otherwise, I'd be happy to see these patches disappear into the annals of the wayback machine. thanks!
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