Xref: utzoo comp.unix.wizards:15120 comp.bugs.sys5:812
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!eecae!tank!mimsy!eneevax!haven!rutgers!att!cbnewsc!dwd
From: dwd@cbnewsc.ATT.COM (david.w.dykstra)
Newsgroups: comp.unix.wizards,comp.bugs.sys5
Subject: Re: setuid (euid) after setuid (uid) on System 5
Message-ID: <280@cbnewsc.ATT.COM>
Date: 20 Mar 89 16:24:26 GMT
References: <123@cat.Fulcrum.BT.CO.UK>
Organization: AT&T Bell Laboratories
Lines: 25

From article <123@cat.Fulcrum.BT.CO.UK>, by igb@Fulcrum.BT.CO.UK (Ian G Batten):
- 
- Should the following program work or not, on System Five?  This is a
- common idiom in the source code of HoneyDanber uucp, and two local System
- Five machines refuse to honour the second setuid. 
- 
- main ()
- {
-   int uid, euid;
- 
-   printf ("uid = %d; euid = %d\n", uid = getuid (), euid = geteuid ());
-   if (setuid (uid) != 0)
-     perror ("setuid (uid)");
-   printf ("uid = %d; euid = %d\n", getuid (), geteuid ());
-   if (setuid (euid) != 0)
-     perror ("setuid (euid)");
-   printf ("uid = %d; euid = %d\n", getuid (), geteuid ());
- }
This works on my System V 3.2.1 system only if the program is not
set-uid to root.  If it is set-uid to something else (like uucp in the
HoneyDanber stuff) then it works.  I'm not sure why it shouldn't work
for root.

- Dave Dykstra
  AT&T Bell Labs, Skokie, IL   att!ttrdf!dwd