Re: [oss-security] [patch] proc.5: tell how to parse /proc/*/stat correctly

From: Shawn Webb <shawn.webb@hardenedbsd.org>
To: oss-security@lists.openwall.com
Cc: Alejandro Colomar <alx.manpages@gmail.com>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	linux-kernel@vger.kernel.org, linux-man@vger.kernel.org
Subject: Re: [oss-security] [patch] proc.5: tell how to parse /proc/*/stat correctly
Date: Wed, 28 Dec 2022 14:24:36 -0500	[thread overview]
Message-ID: <20221228192436.viuoyil2ntr4lxjo@mutt-hbsd> (raw)
In-Reply-To: <Y6yEv+6iYQQNaqi9@itl-email>

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On Wed, Dec 28, 2022 at 01:02:35PM -0500, Demi Marie Obenour wrote:
> On Wed, Dec 28, 2022 at 12:25:17PM -0500, Shawn Webb wrote:
> > On Wed, Dec 28, 2022 at 11:47:25AM -0500, Demi Marie Obenour wrote:
> > > On Wed, Dec 28, 2022 at 10:24:58AM -0500, Shawn Webb wrote:
> > > > On Tue, Dec 27, 2022 at 04:44:49PM -0800, Lyndon Nerenberg (VE7TFX/VE6BBM) wrote:
> > > > > Dominique Martinet writes:
> > > > > 
> > > > > > But, really, I just don't see how this can practically be said to be parsable...
> > > > > 
> > > > > In its current form it never will be.  The solution is to place
> > > > > this variable-length field last.  Then you can "cut -d ' ' -f 51-"
> > > > > to get the command+args part (assuming I counted all those fields
> > > > > correctly ...)
> > > > > 
> > > > > Of course, this breaks backwards compatability.
> > > > 
> > > > It would also break forwards compatibility in the case new fields
> > > > needed to be added.
> > > > 
> > > > The only solution would be a libxo-style feature wherein a
> > > > machine-parseable format is exposed by virtue of a file extension.
> > > > 
> > > > Examples:
> > > > 
> > > > 1. /proc/pid/stats.json
> > > > 2. /proc/pid/stats.xml
> > > > 3. /proc/pid/stats.yaml_shouldnt_be_a_thing
> > > 
> > > A binary format would be even better.  No risk of ambiguity.
> > 
> > I think the argument I'm trying to make is to be flexible in
> > implementation, allowing for future needs and wants--that is "future
> > proofing".
> 
> Linux should not have an XML, JSON, or YAML serializer.  Linux already
> does way too much; let’s not add one more thing to the list.

Somewhat agreed. I think formats like JSON provide a good balance
between machine parseable and human readable.

As I described earlier, though, when it comes to concepts like procfs
and sysfs, I have a bias towards abandoning them in favor of sysctl.
If sysctl nodes were to be used, no new serialization formats would
need to be implemented--and developers would also use a safter method
of system and process inspection and manipulation.

-- 
Shawn Webb
Cofounder / Security Engineer
HardenedBSD

https://git.hardenedbsd.org/hardenedbsd/pubkeys/-/raw/master/Shawn_Webb/03A4CBEBB82EA5A67D9F3853FF2E67A277F8E1FA.pub.asc

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