[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 setuid ,
.Nm seteuid ,
.Nm setgid ,
.Nm setegid
.Nd set user and group ID
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <unistd.h>
.Ft int
.Fn setuid "uid_t uid"
.Ft int
.Fn seteuid "uid_t euid"
.Ft int
.Fn setgid "gid_t gid"
.Ft int
.Fn setegid "gid_t egid"
.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-user-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.
.Sh SEE ALSO
.Xr getuid 2 ,
.Xr getgid 2
.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
	40	.Nm setuid ,
	41	.Nm seteuid ,
	42	.Nm setgid ,
	43	.Nm setegid
	44	.Nd set user and group ID
	45	.Sh SYNOPSIS
	46	.Fd #include <sys/types.h>
	47	.Fd #include <unistd.h>
	48	.Ft int
	49	.Fn setuid "uid_t uid"
	50	.Ft int
	51	.Fn seteuid "uid_t euid"
	52	.Ft int
	53	.Fn setgid "gid_t gid"
	54	.Ft int
	55	.Fn setegid "gid_t egid"
	56	.Sh DESCRIPTION
	57	The
	58	.Fn setuid
	59	function
	60	sets the real and effective
	61	user IDs and the saved set-user-ID of the current process
	62	to the specified value.
	63	The
	64	.Fn setuid
65	function is permitted if the effective user ID is that of the super user,
66	or if the specified user ID is the same as the effective user ID. If
67	not, but the specified user ID is the same as the real user ID,
68	.Fn setuid
69	will set the effective user ID to the real user ID.
70	.Pp
71	The
72	.Fn setgid
73	function
74	sets the real and effective
75	group IDs and the saved set-group-ID of the current process
76	to the specified value.
77	The
78	.Fn setgid
79	function is permitted if the effective user ID is that of the super user,
80	or if the specified group ID is the same as the effective group ID. If
81	not, but the specified group ID is the same as the real group ID,
82	.Fn setgid
83	will set the effective group ID to the real group ID.
84	.Pp
85	The
86	.Fn seteuid
87	function
88	.Pq Fn setegid
89	sets the effective user ID (group ID) of the
90	current process.
91	The effective user ID may be set to the value
92	of the real user ID or the saved set-user-ID (see
93	.Xr intro 2
94	and
95	.Xr execve 2 ) ;
96	in this way, the effective user ID of a set-user-ID executable
97	may be toggled by switching to the real user ID, then re-enabled
98	by reverting to the set-user-ID value.
99	Similarly, the effective group ID may be set to the value
100	of the real group ID or the saved set-user-ID.
101	.Pp
102	.Sh RETURN VALUES
103	Upon success, these functions return 0;
104	otherwise \-1 is returned.
105	.Pp
106	If the user is not the super user, or the uid
107	specified is not the real, effective ID, or saved ID,
108	these functions return \-1.
109	.Sh SEE ALSO
110	.Xr getuid 2 ,
111	.Xr getgid 2
112	.Sh STANDARDS
113	The
114	.Fn setuid
115	and
116	.Fn setgid
117	functions are compliant with the
118	.St -p1003.1-90
119	specification with
120	.Li _POSIX_SAVED_IDS
121	defined, with the extensions allowed in section B.4.2.2.
122	The
123	.Fn seteuid
124	and
125	.Fn setegid
126	functions are extensions based on the
127	.Tn POSIX
128	concept of
129	.Li _POSIX_SAVED_IDS ,
130	and have been proposed for a future revision of the standard.