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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Wed, 18 Jan 2012 11:39:41 -0800
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Subject: Re: Compat 32-bit syscall entry from 64-bit task!?
To: Andi Kleen <andi@firstfloor.org>
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On Wed, Jan 18, 2012 at 11:36 AM, Andi Kleen <andi@firstfloor.org> wrote:
>
> The real fix is really to use a LSM for custom jails.  Trying to make
> ptrace secure is trying to make a sieve wather tight by plugging the individual
> holes one by one. It's simply not suitable for this.

Umm. But the exact same is true of "LSM for custom jail". It's a
f*&^ing disaster, and it's a whole lot more complicated than ptrace.

Plus it can't even do what ptrace does, so what's the point?  There's
a lot of system calls that don't have any kind of lsm hooks, and
shouldn't. Exactly because THAT is a "plugging individual holes one by
one" approach.

                     Linus