|ISSETUGID(2)||System Calls Manual||ISSETUGID(2)|
issetugid() function returns 1 if the process was made setuid or setgid as the result of the last or other previous
execve() system calls. Otherwise it returns 0.
This system call exists so that library routines (inside libtermlib, libc, or other libraries) can guarantee safe behavior when used inside setuid or setgid programs. Some library routines may be passed insufficient information and hence not know whether the current program was started setuid or setgid because higher level calling code may have made changes to the uid, euid, gid, or egid. Hence these low-level library routines are unable to determine if they are being run with elevated or normal privileges.
In particular, it is wise to use this call to determine if a
pathname returned from a
getenv() call may safely be
open() the specified file. Quite often this
is not wise because the status of the effective uid is not known.
issetugid() system call's result is
unaffected by calls to
setgid(), or other such calls. In case of a
fork(), the child process inherits the same
The status of
issetugid() is only affected
execve(). If a child process executes a new
executable file, a new issetugid status will be determined. This status is
based on the existing process's uid, euid, gid, and egid permissions and on
the modes of the executable file. If the new executable file modes are
setuid or setgid, or if the existing process is executing the new image with
uid != euid or gid != egid, the new process will be considered
issetugid() function is always successful, and no return value is reserved to indicate an error. execve(2), setegid(2), seteuid(2), setgid(2), setuid(2), getenv(3)
issetugid() function call first appeared in OpenBSD 2.0.
|September 10, 2015||OpenBSD-current|