issetugid(2)

NAME

issetugid - is current process tainted by uid or gid changes

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <unistd.h>
int
issetugid(void);

DESCRIPTION

The issetugid() system call returns 1 if the process envi

ronment or memory address space is considered ``tainted'', and returns 0

otherwise.

A process is tainted if it was created as a result of an ex

ecve(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 execu

tion.

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.

A ``tainted'' status is inherited by child processes as a

result of the
fork(2) system call (or other library code that calls fork,

such as
popen(3)).

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 pro

grams such as
su(1) which begin setuid but need to be able to create an

untainted process.

ERRORS

The issetugid() system call is always successful, and no re

turn value is
reserved to indicate an error.

SEE ALSO

execve(2), fork(2), setegid(2), seteuid(2), setgid(2), se

tregid(2),
setreuid(2), setuid(2)

HISTORY

The issetugid() system call first appeared in OpenBSD 2.0

and was also
implemented in FreeBSD 3.0.

BSD August 25, 1996

BSD