+++ /dev/null
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-.\" must display the following acknowledgement:
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-.\" @(#)setregid.2 6.4 (Berkeley) 3/10/91
-.\"
-.\" Modified Sat Jul 24 09:08:49 1993 by Rik Faith <faith@cs.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.Wilford@ee.surrey.ac.uk>
-.\" 1994-08-02 by Wilf due to change in kernel.
-.\" 2004-07-04 by aeb
-.\" 2004-05-27 by Michael Kerrisk
-.\"
-.TH SETREUID 2 2014-09-21 "Linux" "Linux Programmer's Manual"
-.SH NAME
-setreuid, setregid \- set real and/or effective user or group ID
-.SH SYNOPSIS
-.B #include <sys/types.h>
-.br
-.B #include <unistd.h>
-.sp
-.BI "int setreuid(uid_t " ruid ", uid_t " euid );
-.br
-.BI "int setregid(gid_t " rgid ", gid_t " egid );
-.sp
-.in -4n
-Feature Test Macro Requirements for glibc (see
-.BR feature_test_macros (7)):
-.in
-.sp
-.BR setreuid (),
-.BR setregid ():
-.RS 4
-.ad l
-_BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
-_XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
-.ad
-.RE
-.SH DESCRIPTION
-.BR 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.
-
-Unprivileged users may only set the real user ID to
-the real user ID or the effective user ID.
-
-If the real user ID is set (i.e.,
-.I ruid
-is not \-1) 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,
-.BR setregid ()
-sets real and effective group ID's of the calling process,
-and all of the above holds with "group" instead of "user".
-.SH RETURN VALUE
-On success, zero is returned.
-On error, \-1 is returned, and
-.I errno
-is set appropriately.
-
-.IR Note :
-there are cases where
-.BR setreuid ()
-can fail even when the caller is UID 0;
-it is a grave security error to omit checking for a failure return from
-.BR setreuid ().
-.SH ERRORS
-.TP
-.B EAGAIN
-The call would change the caller's real UID (i.e.,
-.I ruid
-does not match the caller's real UID),
-but there was a temporary failure allocating the
-necessary kernel data structures.
-.TP
-.B EAGAIN
-.I ruid
-does not match the caller's real UID and this call would
-bring the number of processes belonging to the real user ID
-.I ruid
-over the caller's
-.B RLIMIT_NPROC
-resource limit.
-Since Linux 3.1, this error case no longer occurs
-(but robust applications should check for this error);
-see the description of
-.B EAGAIN
-in
-.BR execve (2).
-.TP
-.B EINVAL
-One or more of the target user or group IDs
-is not valid in this user namespace.
-.TP
-.B EPERM
-The calling process is not privileged
-(Linux: does not have the
-.B CAP_SETUID
-capability in the case of
-.BR setreuid (),
-or the
-.B CAP_SETGID
-capability in the case of
-.BR 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.
-.SH CONFORMING TO
-POSIX.1-2001, 4.3BSD (the
-.BR setreuid ()
-and
-.BR setregid ()
-function calls first appeared in 4.2BSD).
-.SH 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).
-
-POSIX.1 does not specify all of possible ID changes that are permitted
-on Linux for an unprivileged process.
-For
-.BR setreuid (),
-the effective user ID can be made the same as the
-real user ID or the save set-user-ID,
-and 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.
-For
-.BR setregid (),
-the real group ID can be changed to the value of the saved set-group-ID,
-and the effective group ID can be changed to the value of
-the real group ID or the saved set-group-ID.
-The precise details of what ID changes are permitted vary
-across implementations.
-
-POSIX.1 makes no specification about the effect of these calls
-on the saved set-user-ID and saved set-group-ID.
-
-The original Linux
-.BR setreuid ()
-and
-.BR setregid ()
-system calls supported only 16-bit user and group IDs.
-Subsequently, Linux 2.4 added
-.BR setreuid32 ()
-and
-.BR setregid32 (),
-supporting 32-bit IDs.
-The glibc
-.BR setreuid ()
-and
-.BR setregid ()
-wrapper functions transparently deal with the variations across kernel versions.
-.SH SEE ALSO
-.BR getgid (2),
-.BR getuid (2),
-.BR seteuid (2),
-.BR setgid (2),
-.BR setresuid (2),
-.BR setuid (2),
-.BR capabilities (7),
-.BR user_namespaces (7)
-.SH COLOPHON
-This page is part of release 3.79 of the Linux
-.I man-pages
-project.
-A description of the project,
-information about reporting bugs,
-and the latest version of this page,
-can be found at
-\%http://www.kernel.org/doc/man\-pages/.
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