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Date:      Thu, 20 Jul 2000 00:25:48 -0400 (EDT)
From:      Robert Watson <rwatson@FreeBSD.org>
To:        Marcel Moolenaar <marcel@FreeBSD.org>
Cc:        cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org, security-officer@FreeBSD.org
Subject:   Re: cvs commit: src/sys/i386/linux linux_dummy.c linux_misc.c
Message-ID:  <Pine.NEB.3.96L.1000720001526.77319D-100000@fledge.watson.org>
In-Reply-To: <200007190353.UAA71410@freefall.freebsd.org>

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Marcel,

I have not had a chance to review these commits as I am on travel. 
However, it strikes me that these are security-sensitive commits, and I
didn't see a reviewed-by: on the original or MFC commits.  As you know, we
don't have a semantic equivilent to the Linux fsuid behavior, which
(without looking at the patches) strongly suggests to me that we are
emulating the behavior improperly, or noop'ing it.  Incorrect emulation or
no-oping the call may result in an application believing it has given up
privileges when it has not, or giving up privileges that it does not know
that it will.  As a security person who has spent a fair amount of time of
late beating up on Linux people to fix their capabilities implementation
due to incorrect combining of uid and capability semantics, which is a
very complicated thing, I can only point out that this is something we
want to be *very* careful about.  The recent Linux kernel/sendmail bug is
just one example of the results of not being very careful with
security-sensitive calls and behaving predictably from the application
perspective.

Do you feel comfortable that this puts neither the kernel nor privileged
userland applications at risk?  I.e., do we precisely emulate their
semantics and avoid introducing new security problems?

If the answer to either of these questions is no, I'd like to see this
backed out before the release.

Thanks!

On Tue, 18 Jul 2000, Marcel Moolenaar wrote:

> marcel      2000/07/18 20:53:08 PDT
> 
>   Modified files:        (Branch: RELENG_4)
>     sys/i386/linux       linux_dummy.c linux_misc.c 
>   Log:
>   MFC: Implement setfsuid and setfsgid.
>   
>   PR: 16993
>   
>   Revision  Changes    Path
>   1.21.2.1  +1 -3      src/sys/i386/linux/linux_dummy.c
>   1.77.2.2  +21 -1     src/sys/i386/linux/linux_misc.c
> 
> 
> 


  Robert N M Watson 

robert@fledge.watson.org              http://www.watson.org/~robert/
PGP key fingerprint: AF B5 5F FF A6 4A 79 37  ED 5F 55 E9 58 04 6A B1
TIS Labs at Network Associates, Safeport Network Services



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