linux-kernel - Re: [PATCH] fs/proc: Add process text segment md5-summing

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Date:	Mon, 12 Nov 2012 18:16:03 -0800
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Arvid Brodin <Arvid.Brodin@...n.com>,
	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	"David Rientjes" <rientjes@...gle.com>
Subject: Re: [PATCH] fs/proc: Add process text segment md5-summing

Andrew Morton <akpm@...ux-foundation.org> writes:

> On Mon, 12 Nov 2012 21:36:17 +0000
> Arvid Brodin <Arvid.Brodin@...n.com> wrote:
>
>> Adds /proc/<pid>/text_md5sum which, when read, calculates an md5sum over
>> the process' text segment. This can detect some cases where the system RAM
>> has been disturbed by e.g. ESD or cosmic radiation (on systems where ECC
>> is not available). It might also detect some accidental or malicious
>> modifications of executables, where the perpetrator has not bothered to
>> cover up the tracks.
>
> I thought the review comments regarding the earlier patch were rather
> fatal, sorry.

To add another nail in the coffin.

You can do this with ptrace or with /proc/<pid>/mem without a kernel
patch.

To make this safe would need a ptrace_may_acces(PTRACE_MODE_READ)
permission check.  At which point not doing this with ptrace just adds
up to extra kernel maintenance for no real point.

Eric


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