Xref: utzoo comp.unix.wizards:15227 comp.bugs.sys5:824
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!tank!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.unix.wizards,comp.bugs.sys5
Subject: Re: setuid (euid) after setuid (uid) on System 5
Message-ID: <16538@mimsy.UUCP>
Date: 26 Mar 89 05:27:19 GMT
References: <123@cat.Fulcrum.BT.CO.UK> <280@cbnewsc.ATT.COM> <1196@auspex.UUCP> <9915@smoke.BRL.MIL>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 17

>In article <1196@auspex.UUCP> guy@auspex.UUCP (Guy Harris) writes:
>>Both BSD and S5 flavors of "setuid" can be implemented atop "setreuid".

In article <9915@smoke.BRL.MIL> gwyn@smoke.BRL.MIL (Doug Gwyn) writes:
>I don't think the "saved set-UID" feature can be emulated using setreuid().

If you are willing to substitute your own getuid(), geteuid(), and
access() for the `real' versions, it can.  (Obviously you also have
to substitute setuid and seteuid.)

In any case, Mike K. has talked about having 4.4 have `saved setuid
done right'.  The real problem with the SysV version is that it
overloads setuid(), and can tell `set all IDs including saved effective
uid' from `set real and effective uid' only when the caller is not root.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris