linux-kernel - Re: [PATCH] allow execve'ing "/proc/self/exe" even if /proc is not mounted

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Message-ID: <8bd0f97a0906241707k14d09df5t6aa3229ed115b478@mail.gmail.com>
Date:	Wed, 24 Jun 2009 20:07:12 -0400
From:	Mike Frysinger <vapier.adi@...il.com>
To:	Al Viro <viro@...iv.linux.org.uk>
Cc:	Denys Vlasenko <vda.linux@...glemail.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] allow execve'ing "/proc/self/exe" even if /proc is not 
	mounted

On Wed, Jun 24, 2009 at 19:58, Al Viro wrote:
> On Thu, Jun 25, 2009 at 01:00:56AM +0200, Denys Vlasenko wrote:
>> More elegant way is to execute /proc/self/exe.
>> This works just fine as long as /proc is mounted.
>
> So mount it.

well, in the busybox case, in order to run mount you might have to
exec yourself first ...

> No.  This is just plain sick.  Magical pathnames have no business being
> in the kernel.  If procfs is too much for your sensitive soul, do an
> extremely trimmed-down version that would consist of *one* *file* (yes,
> as root and only node on fs).  Said file being a procfs-style symlink,
> doing exactly what /proc/self/exec would do.
>
> On such system you can just mkdir /proc/self, touch /proc/self/exec,
> mount -t self_exec none /proc/self/exec and be done with that.  No
> magic needed, end of the story.

if that is acceptable, how about a special binfmt that depends on
EMBEDDED and we put the magic there.
-mike
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