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From Sat Nov 22 14:56:41 1997
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Date: 22 Nov 1997 19:56:36 -0000
To: krb5-bugs@MIT.EDU
Subject: seteuid.c should not look for _POSIX_SAVED_IDS
X-Send-Pr-Version: 3.99

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>Number: 503
>Category: krb5-libs
>Synopsis: seteuid.c should not look for _POSIX_SAVED_IDS
>Confidential: no
>Severity: critical
>Priority: high
>Responsible: tlyu
>State: closed
>Class: sw-bug
>Submitter-Id: unknown
>Arrival-Date: Sat Nov 22 14:57:01 EST 1997
>Last-Modified: Tue Jan 06 17:29:28 EST 1998
>Originator: Evan Champion

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>Release: krb5-1.0.2

System: BSD/OS 3.1 BSDI BSD/OS 3.1 Kernel #0: Tue Oct 28 19:45:49 EST 1997 i386

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lib/krb5util/seteuid.c should not be looking for _POSIX_SAVED_IDS.
This prevents seteuid() from being used on 4.4BSD systems, as none
of them define _POSIX_SAVED_IDS, and seteuid() is very often the
only set-effective-UID function that actually works. This is
definitely the case on all versions of BSD/OS.

Fix verified to not break anything on BSD/OS 3.1 and FreeBSD
3.0-current. I rather doubt it will break anything on other
platforms either.
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*** /home/evanc/1/krb5-1.0.3/src/lib/krb5util/seteuid.c Mon Nov 17 22:49:40 1997
--- src/lib/krb5util/seteuid.c Sat Nov 22 14:53:19 1997
*** 38,44 ****
int euid_in;
uid_t euid = (uid_t) euid_in;
! #if defined(_POSIX_SAVED_IDS) && defined(HAVE_SETEUID)
return (seteuid(euid)) ;
#if defined(HAVE_SETRESUID)
--- 38,44 ----
int euid_in;
uid_t euid = (uid_t) euid_in;
! #if defined(HAVE_SETEUID)
return (seteuid(euid)) ;
#if defined(HAVE_SETRESUID)

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From: Evan Champion <>
To: krb5-bugs@MIT.EDU
Cc: Subject: krb5-libs/503: More on the BSD/OS setreuid()
Date: Sat, 6 Dec 1997 10:09:51 -0500 (EST)

As an FYI, I was digging through the BSD/OS kernel source to find out what
setreuid() _really_ does, and found this...

* Partially emulate old setreuid usage of exchanging ruid and euid.
* We assume that the intent of setting ruid is to be able to get
* back setuid privilege. So we make sure that we will be able to
* do so, but do not actually set the ruid.

setreuid() is actually implemented as seteuid(). The real uid is never

Now, this code is only included if you have COMPAT_43 or COMPAT_BSDI11
defined. COMPAT_43 is not defined by default, and my kernels don't have
COMPAT_BSDI11 defined.

Even more interesting, in libc's compat-43 part, setruid() is implemented
as setreuid(ruid, -1), when setreuid() never sets the real id :-)


Responsible-Changed-From-To: krb5-unassigned->tlyu
Responsible-Changed-By: tlyu
Responsible-Changed-When: Tue Jan 6 17:28:37 1998

State-Changed-From-To: open-closed
State-Changed-By: tlyu
State-Changed-When: Tue Jan 6 17:28:49 1998

src/lib/krb5util/seteuid.c 1.5

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