[apple/xnu.git] / bsd / man / man2 / setuid.2

.\"	$NetBSD: setuid.2,v 1.3 1995/02/27 12:37:06 cgd Exp $
.\"
.\" Copyright (c) 1983, 1991, 1993
.\"	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
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)setuid.2	8.1 (Berkeley) 6/4/93
.\"
.Dd June 4, 1993
.Dt SETUID 2
.Os BSD 4.2
.Sh NAME
.Nm setegid ,
.Nm seteuid ,
.Nm setgid ,
.Nm setuid
.Nd set user and group ID
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fo setegid
.Fa "gid_t egid"
.Fc
.Ft int
.Fo seteuid
.Fa "uid_t euid"
.Fc
.Ft int
.Fo setgid
.Fa "gid_t gid"
.Fc
.Ft int
.Fo setuid
.Fa "uid_t uid"
.Fc
.Sh DESCRIPTION
The
.Fn setuid
function
sets the real and effective
user IDs and the saved set-user-ID of the current process
to the specified value.
The
.Fn setuid
function is permitted if the effective user ID is that of the super user,
or if the specified user ID is the same as the effective user ID.  If
not, but the specified user ID is the same as the real user ID,
.Fn setuid
will set the effective user ID to the real user ID.
.Pp
The
.Fn setgid
function
sets the real and effective
group IDs and the saved set-group-ID of the current process
to the specified value.
The
.Fn setgid
function is permitted if the effective user ID is that of the super user,
or if the specified group ID is the same as the effective group ID.  If
not, but the specified group ID is the same as the real group ID,
.Fn setgid
will set the effective group ID to the real group ID.
.Pp
The
.Fn seteuid
function
.Pq Fn setegid
sets the effective user ID (group ID) of the
current process.
The effective user ID may be set to the value
of the real user ID or the saved set-user-ID (see
.Xr intro 2
and
.Xr execve 2 ) ;
in this way, the effective user ID of a set-user-ID executable
may be toggled by switching to the real user ID, then re-enabled
by reverting to the set-user-ID value.
Similarly, the effective group ID may be set to the value
of the real group ID or the saved set-group-ID.
.Pp
.Sh RETURN VALUES
Upon success, these functions return 0;
otherwise \-1 is returned.
.Pp
If the user is not the super user, or the uid
specified is not the real, effective ID, or saved ID,
these functions return \-1.
.Pp
.Sh ERRORS
The
.Fn setegid ,
.Fn seteuid ,
.Fn setgid ,
and
.Fn setuid
system calls will fail if:
.Bl -tag -width Er
.\" ===========
.It Bq Er EINVAL
The value of the {group,user} ID argument is invalid
and is not supported by the implementation.
.\" ===========
.It Bq Er EPERM
The process does not have appropriate privileges and
the ID argument
does not match the real ID
or the saved set-{group,user}-ID.
.El
.Sh LEGACY SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <unistd.h>
.Pp
The include file
.In sys/types.h
is necessary for all functions.
.Sh SEE ALSO
.Xr getgid 2 ,
.Xr getuid 2 ,
.Xr compat 5
.Sh STANDARDS
The
.Fn setuid
and
.Fn setgid
functions are compliant with the
.St -p1003.1-90
specification with
.Li _POSIX_SAVED_IDS
defined, with the extensions allowed in section B.4.2.2.
The
.Fn seteuid
and
.Fn setegid
functions are extensions based on the 
.Tn POSIX
concept of
.Li _POSIX_SAVED_IDS ,
and have been proposed for a future revision of the standard.
Commit	Line	Data
9bccf70c A	1	.\" $NetBSD: setuid.2,v 1.3 1995/02/27 12:37:06 cgd Exp $
	2	.\"
	3	.\" Copyright (c) 1983, 1991, 1993
	4	.\" The Regents of the University of California. All rights reserved.
	5	.\"
	6	.\" Redistribution and use in source and binary forms, with or without
	7	.\" modification, are permitted provided that the following conditions
	8	.\" are met:
	9	.\" 1. Redistributions of source code must retain the above copyright
	10	.\" notice, this list of conditions and the following disclaimer.
	11	.\" 2. Redistributions in binary form must reproduce the above copyright
	12	.\" notice, this list of conditions and the following disclaimer in the
	13	.\" documentation and/or other materials provided with the distribution.
	14	.\" 3. All advertising materials mentioning features or use of this software
	15	.\" must display the following acknowledgement:
	16	.\" This product includes software developed by the University of
	17	.\" California, Berkeley and its contributors.
	18	.\" 4. Neither the name of the University nor the names of its contributors
	19	.\" may be used to endorse or promote products derived from this software
	20	.\" without specific prior written permission.
	21	.\"
	22	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	23	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	24	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	25	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	26	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	27	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	28	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	29	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	30	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	31	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	32	.\" SUCH DAMAGE.
	33	.\"
	34	.\" @(#)setuid.2 8.1 (Berkeley) 6/4/93
	35	.\"
	36	.Dd June 4, 1993
	37	.Dt SETUID 2
	38	.Os BSD 4.2
	39	.Sh NAME
2d21ac55	40	.Nm setegid ,
9bccf70c A	41	.Nm seteuid ,
9bccf70c A	42	.Nm setgid ,
2d21ac55	43	.Nm setuid
9bccf70c A	44	.Nd set user and group ID
9bccf70c A	45	.Sh SYNOPSIS
9bccf70c A	46	.Fd #include <unistd.h>
9bccf70c A	47	.Ft int
2d21ac55 A	48	.Fo setegid
	49	.Fa "gid_t egid"
	50	.Fc
9bccf70c	51	.Ft int
2d21ac55 A	52	.Fo seteuid
	53	.Fa "uid_t euid"
	54	.Fc
9bccf70c	55	.Ft int
2d21ac55 A	56	.Fo setgid
	57	.Fa "gid_t gid"
	58	.Fc
9bccf70c	59	.Ft int
2d21ac55 A	60	.Fo setuid
	61	.Fa "uid_t uid"
	62	.Fc
9bccf70c A	63	.Sh DESCRIPTION
	64	The
	65	.Fn setuid
	66	function
	67	sets the real and effective
	68	user IDs and the saved set-user-ID of the current process
	69	to the specified value.
	70	The
	71	.Fn setuid
	72	function is permitted if the effective user ID is that of the super user,
	73	or if the specified user ID is the same as the effective user ID. If
	74	not, but the specified user ID is the same as the real user ID,
	75	.Fn setuid
	76	will set the effective user ID to the real user ID.
	77	.Pp
	78	The
	79	.Fn setgid
	80	function
	81	sets the real and effective
	82	group IDs and the saved set-group-ID of the current process
	83	to the specified value.
	84	The
	85	.Fn setgid
	86	function is permitted if the effective user ID is that of the super user,
	87	or if the specified group ID is the same as the effective group ID. If
	88	not, but the specified group ID is the same as the real group ID,
	89	.Fn setgid
	90	will set the effective group ID to the real group ID.
	91	.Pp
	92	The
	93	.Fn seteuid
	94	function
	95	.Pq Fn setegid
	96	sets the effective user ID (group ID) of the
	97	current process.
	98	The effective user ID may be set to the value
	99	of the real user ID or the saved set-user-ID (see
	100	.Xr intro 2
	101	and
	102	.Xr execve 2 ) ;
	103	in this way, the effective user ID of a set-user-ID executable
	104	may be toggled by switching to the real user ID, then re-enabled
	105	by reverting to the set-user-ID value.
	106	Similarly, the effective group ID may be set to the value
d9a64523	107	of the real group ID or the saved set-group-ID.
9bccf70c A	108	.Pp
	109	.Sh RETURN VALUES
	110	Upon success, these functions return 0;
	111	otherwise \-1 is returned.
	112	.Pp
	113	If the user is not the super user, or the uid
	114	specified is not the real, effective ID, or saved ID,
	115	these functions return \-1.
2d21ac55 A	116	.Pp
	117	.Sh ERRORS
	118	The
	119	.Fn setegid ,
	120	.Fn seteuid ,
	121	.Fn setgid ,
	122	and
	123	.Fn setuid
	124	system calls will fail if:
	125	.Bl -tag -width Er
	126	.\" ===========
	127	.It Bq Er EINVAL
	128	The value of the {group,user} ID argument is invalid
	129	and is not supported by the implementation.
	130	.\" ===========
	131	.It Bq Er EPERM
	132	The process does not have appropriate privileges and
	133	the ID argument
	134	does not match the real ID
	135	or the saved set-{group,user}-ID.
	136	.El
	137	.Sh LEGACY SYNOPSIS
	138	.Fd #include <sys/types.h>
	139	.Fd #include <unistd.h>
	140	.Pp
	141	The include file
	142	.In sys/types.h
	143	is necessary for all functions.
9bccf70c	144	.Sh SEE ALSO
2d21ac55	145	.Xr getgid 2 ,
9bccf70c	146	.Xr getuid 2 ,
2d21ac55	147	.Xr compat 5
9bccf70c A	148	.Sh STANDARDS
	149	The
	150	.Fn setuid
	151	and
	152	.Fn setgid
	153	functions are compliant with the
	154	.St -p1003.1-90
	155	specification with
	156	.Li _POSIX_SAVED_IDS
	157	defined, with the extensions allowed in section B.4.2.2.
	158	The
	159	.Fn seteuid
	160	and
	161	.Fn setegid
	162	functions are extensions based on the
	163	.Tn POSIX
	164	concept of
	165	.Li _POSIX_SAVED_IDS ,
	166	and have been proposed for a future revision of the standard.