$OpenBSD: issetugid.2,v 1.7 1997/02/18 00:16:09 deraadt Exp $ Copyright (c) 1980, 1991, 1993 The Regents of the University of California. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the...
NAMEissetugid - is current process tainted by uid or gid changes
SYNOPSISIn unistd.h Ft int Fn issetugid void
DESCRIPTIONThe Fn issetugid system call returns 1 if the process environment or memory address space is considered ``tainted'' and returns 0 otherwise.
A process is tainted if it was created as a result of an execve(2) system call which had either of the setuid or setgid bits set (and extra privileges were given as a result) or if it has changed any of its real, effective or saved user or group ID's since it began execution.
This system call exists so that library routines (eg: libc, libtermcap) can reliably determine if it is safe to use information that was obtained from the user, in particular the results from getenv(3) should be viewed with suspicion if it is used to control operation.
It is assumed that a program that clears all privileges as it prepares to execute another will also reset the environment, hence the ``tainted'' status will not be passed on. This is important for programs such as su(1) which begin setuid but need to be able to create an untainted process.