Date: Sat, 20 Jul 2002 01:06:37 -0600 (MDT) From: "M. Warner Losh" <imp@bsdimp.com> To: bde@zeta.org.au Cc: julian@vicor.com, current@FreeBSD.ORG Subject: Re: [Fwd: FreeBSD/Linux kernel setgid implementation] Message-ID: <20020720.010637.105098846.imp@bsdimp.com> In-Reply-To: <20020720131426.T15254-100000@gamplex.bde.org> References: <20020720130233.Y15254-100000@gamplex.bde.org> <20020720131426.T15254-100000@gamplex.bde.org>
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In message: <20020720131426.T15254-100000@gamplex.bde.org>
Bruce Evans <bde@zeta.org.au> writes:
: On Fri, 19 Jul 2002, Julian Elischer wrote:
:
: > forwarded from bugtraq..
:
: > Indeed, with their rigourous methodology, the authors did detect this error in the setgid linux manpage on Red Hat 7.2. I just wonder if they reported it (the manpage on www.linux.org is still inaccurate at the moment).
: > This paper also reports a real example of a program with the setgid flag only, that thinks it can drop all privileges by calling setgid(getgid()). It is OK on FreeBSD, but not on Linux...
:
: This point will have to be revisited son, since POSIX-1.2001 requires
: _POSIX_SAVED_IDS. I think the full brokenness of _POSIX_SAVED_IDS can
: be avoided using a suitably weaselish definition of "appropriate"
: privilege (give everyone that can do set[ug]id() appropriate privilege,
: so that doing it drops the extra saved [ug]id privilege).
I would ****STRONGLY**** suggest that any attempts to change the
setuid semantics of FreeBSD be resisted unless the person making the
change is willing to a) audit the entire tree for places where the use
of setuid breaks (and to publish the results of the non-breakage cases
too) and b) be the point person for the next year after this change
for the SO to send port breakages too.
Many eyes have looked at the setuid/seteuid instances in the tree and
verified them as being as correct as we can determine. I'd really
hate to see that work undone by subtle changes in the system calls.
Warner
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