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Date:      Sun, 5 Jul 1998 20:18:14 -0500
From:      peter@taronga.com (Peter da Silva)
To:        hackers@FreeBSD.ORG
Subject:   Re: A really hoopy idea for variant symlinks.
Message-ID:  <199807060118.UAA21768@bonkers.taronga.com>
References:  <199807051826.NAA10291@bonkers.taronga.com> <l03130300b1c5a9ee1886@[208.2.87.10]>

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In article <l03130300b1c5a9ee1886@[208.2.87.10]>,
Richard Wackerbarth  <rkw@dataplex.net> wrote:
>As for the mechanism to interogate and set them, this proposal seems OK to me.
>However, to have appropriate value, we need to have A SINGLE VALUE (eg:
>osversion)
>that can be referenced from multiple places. Thus changing a single value would
>change a number of links at the same time.

I see what you're getting at now. If you want to be able to change one variable
and effect a bunch of links at once you need to be able to make subdirectories
so you can get *out* of the /proc directory with variance intact.

	mkdir /proc/curproc/syms/2.2.6
	ln -s /usr/arch/2.2.6/bin /proc/curproc/syms/2.2.6/bin
	ln -s /etc/arch/2.2.6/make.conf /proc/curproc/syms/2.2.6/make.conf
	ln -s 2.2.6 /proc/curproc/syms/osversion

Then you'd use /proc/curproc/syms/osversion/bin ...

I was thinking that you'd use multiple symlinks, but then it's more work to
change, less work to set up.

	ln -s /usr/arch/2.2.6/bin /proc/curproc/syms/bin
	ln -s /usr/arch/2.2.6/make.conf /proc/curproc/syms/make.conf

The other thing you could do is put the os-specific-bits tree outside of
/proc, so you don't have to carry all that baggage around:

	ln -s /usr/arch/FreeBSD-2.2.6 /proc/curproc/syms/osversion

Anyway, I do admit it's a little more cumbersome to set up an environment
that's keyed off a single variable. But you can do it, and even get some
benefit from a central configuration directory (/usr/arch/FreeBSD-2.2.6)
where all that stuff is collected.

In all of this, of course, you need to make damn sure that security-related
software is aware of this mechanism (and any other variant symlink mechanism)
and avoids letting people hijack privs by playing sillybuggers with it.

-- 

This is The Reverend Peter da Silva's Boring Sig File - there are no references
to Wolves, Kibo, Discordianism, or The Church of the Subgenius in this document


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