NAME
issetugid —
is current process tainted
by uid or gid changes
SYNOPSIS
#include <unistd.h>
int
issetugid(
void);
DESCRIPTION
The
issetugid() function 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 (e.g., libc) 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
programs such as
su(1) which begin
setuid but need to be able to create an untainted process.
ERRORS
The
issetugid() function is always successful, and no return
value is reserved to indicate an error.
SEE ALSO
execve(2),
fork(2),
setegid(2),
seteuid(2),
setgid(2),
setregid(2),
setreuid(2),
setuid(2)
HISTORY
A
issetugid() function call first appeared in
OpenBSD 2.0 and was also implemented in
FreeBSD 3.0.
FreeBSD
implementation was imported in
NetBSD 1.5.