setreuid(2) — Linux manual pages

setreuid
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Name

setreuid, setregid — set real and/or effective user or group ID

Synopsis

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

`int setreuid(`	uid_t	`ruid`,
	uid_t	`euid)`;

`int setregid(`	gid_t	`rgid`,
	gid_t	`egid)`;

Note

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
`setreuid`(), `setregid`():
`_BSD_SOURCE` \|\| `_XOPEN_SOURCE` >= 500

DESCRIPTION

setreuid() sets real and effective user IDs of the calling process.

Supplying a value of −1 for either the real or effective user ID forces the system to leave that ID unchanged.

Unprivileged processes may only set the effective user ID to the real user ID, the effective user ID or the saved set-user-ID.

POSIX: It is unspecified whether unprivileged processes may set the real user ID to the real user ID, the effective user ID or the saved set-user-ID.

Linux: Unprivileged users may only set the real user ID to the real user ID or the effective user ID.

Linux: If the real user ID is set or the effective user ID is set to a value not equal to the previous real user ID, the saved set-user-ID will be set to the new effective user ID.

Completely analogously, setregid() sets real and effective group ID's of the calling process, and all of the above holds with "group" instead of "user".

RETURN VALUE

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

ERRORS

EPERM: The calling process is not privileged (Linux: does not have the CAP_SETUID capability in the case of setreuid(), or the CAP_SETGID capability in the case of setregid()) and a change other than (i) swapping the effective user (group) ID with the real user (group) ID, or (ii) setting one to the value of the other or (iii) setting the effective user (group) ID to the value of the saved set-user-ID (saved set-group-ID) was specified.

CONFORMING TO

POSIX.1-2001, 4.3BSD (the setreuid() and setregid() function calls first appeared in 4.2BSD).

NOTES

Setting the effective user (group) ID to the saved set-user-ID (saved set-group-ID) is possible since Linux 1.1.37 (1.1.38).

COLOPHON

This page is part of release 2.79 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.

  Copyright (c) 1983, 1991 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 above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.
3. All advertising materials mentioning features or use of this software
   must display the following acknowledgement:
This product includes software developed by the University of
California, Berkeley and its contributors.
4. Neither the name of the University nor the names of its contributors
   may be used to endorse or promote products derived from this software
   without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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SUCH DAMAGE.

    (#)setregid.2 6.4 (Berkeley) 3/10/91

Modified Sat Jul 24 09:08:49 1993 by Rik Faith <faithcs.unc.edu>
Portions extracted from linux/kernel/sys.c:
            Copyright (C) 1991, 1992  Linus Torvalds
            May be distributed under the GNU General Public License
Changes: 1994-07-29 by Wilf <G.Wilfordee.surrey.ac.uk>
         1994-08-02 by Wilf due to change in kernel.
         2004-07-04 by aeb
         2004-05-27 by Michael Kerrisk

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