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Date:      Thu, 9 Sep 1999 01:39:52 -0500
From:      "Jason Young" <doogie@anet-stl.com>
To:        "Daniel O'Connor" <doconnor@gsoft.com.au>
Cc:        <chris@calldei.com>, <freebsd-hackers@FreeBSD.ORG>, "Gustavo V G C Rios" <grios@ddsecurity.com.br>
Subject:   RE: CS Project
Message-ID:  <NCBBJEDMMDOPOMPDEKBPGEFIDDAA.doogie@anet-stl.com>
In-Reply-To: <XFMail.990909155325.doconnor@gsoft.com.au>

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Some further thoughts before I doze off:

> >  allowed to. This should be controlled by sysctls like
> (placement based
> >  on nfs and ffs sysctl placement precedent):
>
> Or even a mount option to procfs :)

After some thought, I think the mount option idea is best. I hadn't
thought of that before. One might want to apply different procfs
security policies to different mounts of procfs, especially in a
jail() situation. Good call.

> >  I think the idea (of a procfs ps) was shot down on the
> lists some time
> >  ago because ps needs to retain the ability to look at
> the process list
> >  in a kernel coredump. IMHO that's a lot of messy kvm
> groveling and
> >  associated kernel-to-userland sync dependencies, just to
> cater to the
> >  (generous figure) 0.5% of the people out there who have
> 1) a crashing
> >  FreeBSD box and 2) the expertise and the will to debug
> the crash dump.
> >  I think that issue needs to be revisited somehow.
>
> Well.. I do use crash dumps, but rarely use ps on them..
> Even so you could have
> 2 implementations of ps, or a ps which allows you to
> compile in a different
> 'back end'. That way you can use either easily.

I think that the best idea here is a single ps implementation with
both backends available. Normally it would use the simple, secure and
possibly privacy-enhancing procfs method, but using the -M or -N
options to specify a dump or kernel file (or the live /dev/kmem and
/kernel, if one were so inclined) would automagically switch ps over
to the kvm grovel method.

This would make the change transparent to both users and developers.
SGID can still be removed - a developer/debugger will already be root
or have had to chown the dump/kernel files to do any debugging.

It would be mild bloat, but disk is cheap, and a disk space to
debugging ease tradeoff has already been made (to the tune of several
megs!) by the decision to build debug kernels by default. I agree with
that. One could also #ifdef the kvm version.

Jason Young
accessUS Chief Network Engineer



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