pthread_setugid_np(2) [osx man page]

PTHREAD_SETUGID_NP(2)					      BSD System Calls Manual					     PTHREAD_SETUGID_NP(2)

NAME

     pthread_setugid_np -- Set the per-thread userid and single groupid.

SYNOPSIS

     #include <sys/types.h>
     #include <sys/unistd.h>

     int
     pthread_setugid_np(uid_t uid, gid_t gid);

DESCRIPTION

     pthread_setugid_np() changes the current thread's effective, real, and saved userid and groupid to the requested userid and groupid ( uid and
     gid , respectively) and clears all other groupids.

     uid can be the current real userid, KAUTH_UID_NONE, or, if the caller is privileged, any userid.  gid can be the current real groupid or, if
     the caller is priviledged, any single groupid.

     Setting uid to KAUTH_UID_NONE means to "revert to the per process credential".

CAVEATS

     Temporarily restoring root privileges for a non-privileged process is only possible on a per-process basis and not a per-thread basis.

     pthread_setugid_np() is not intended as a privilege escalation mechanism.

     Do not use pthread_setugid_np.2() in a security sensitive situation.

RETURN VALUES

     Upon successful completion, a value of 0 is returned.  Otherwise, -1 is returned and the global variable errno is set to indicate the error.

ERRORS

     pthread_setugid_np() fails if one or more of the following are true:

     [EPERM]		The calling process does not have the correct credentials to set the override identity (i.e. The current credentials do
			not imply "super-user").

     [EPERM]		If uid is set to KAUTH_UID_NONE, the current thread must already be assuming another identity in order to revert back.

     [EPERM]		The current thread cannot already be assuming another identity.

SEE ALSO

     setuid(2) setgid(2) seteuid(2) setegid(2)

BSD
								  October 1, 2008							       BSD

SETUID(2)						     Linux Programmer's Manual							 SETUID(2)

NAME

       setuid - set user identity

SYNOPSIS

       #include <sys/types.h>
       #include <unistd.h>

       int setuid(uid_t uid);

DESCRIPTION

       setuid  sets the effective user ID of the current process.  If the effective userid of the caller is root, the real and saved user ID's are
       also set.

       Under Linux, setuid is implemented like the POSIX version with the _POSIX_SAVED_IDS feature.  This allows a setuid (other than  root)  pro-
       gram to drop all of its user privileges, do some un-privileged work, and then re-engage the original effective user ID in a secure manner.

       If  the	user is root or the program is setuid root, special care must be taken. The setuid function checks the effective uid of the caller
       and if it is the superuser, all process related user ID's are set to uid.  After this has occurred, it is impossible  for  the  program	to
       regain root privileges.

       Thus, a setuid-root program wishing to temporarily drop root privileges, assume the identity of a non-root user, and then regain root priv-
       ileges afterwards cannot use setuid.  You can accomplish this with the (non-POSIX, BSD) call seteuid.

RETURN VALUE

       On success, zero is returned.  On error, -1 is returned, and errno is set appropriately.

ERRORS

       EPERM  The user is not the super-user, and uid does not match the real or saved user ID of the calling process.

CONFORMING TO

       SVr4, SVID, POSIX.1.  Not quite compatible with the 4.4BSD call, which sets all of the real, saved, and effective user IDs.  SVr4 documents
       an additional EINVAL error condition.

LINUX-SPECIFIC REMARKS
       Linux  has the concept of filesystem user ID, normally equal to the effective user ID.  The setuid call also sets the filesystem user ID of
       the current process.  See setfsuid(2).

       If uid is different from the old effective uid, the process will be forbidden from leaving core dumps.

SEE ALSO

       getuid(2), setreuid(2), seteuid(2), setfsuid(2)

Linux 1.1.36							    1994-07-29								 SETUID(2)