136 lines
4.3 KiB
Groff
136 lines
4.3 KiB
Groff
.\" $NetBSD: setuid.2,v 1.5 1997/07/14 23:20:15 kleink Exp $
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.\"
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.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)setuid.2 8.1 (Berkeley) 6/4/93
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.\"
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.Dd June 4, 1993
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.Dt SETUID 2
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.Os BSD 4.2
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.Sh NAME
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.Nm setuid ,
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.Nm seteuid ,
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.Nm setgid ,
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.Nm setegid
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.Nd set user and group ID
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.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <unistd.h>
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.Ft int
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.Fn setuid "uid_t uid"
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.Ft int
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.Fn seteuid "uid_t euid"
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.Ft int
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.Fn setgid "gid_t gid"
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.Ft int
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.Fn setegid "gid_t egid"
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.Sh DESCRIPTION
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The
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.Fn setuid
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function
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sets the real and effective
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user IDs and the saved set-user-ID of the current process
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to the specified value.
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The
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.Fn setuid
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function is permitted if the specified ID is equal to the real user ID
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of the process, or if the effective user ID is that of the super user.
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.Pp
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The
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.Fn setgid
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function
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sets the real and effective
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group IDs and the saved set-group-ID of the current process
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to the specified value.
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The
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.Fn setgid
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function is permitted if the specified ID is equal to the real group ID
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of the process, or if the effective user ID is that of the super user.
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.Pp
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The
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.Fn seteuid
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function
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.Pq Fn setegid
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sets the effective user ID (group ID) of the
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current process.
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The effective user ID may be set to the value
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of the real user ID or the saved set-user-ID (see
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.Xr intro 2
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and
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.Xr execve 2 ) ;
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in this way, the effective user ID of a set-user-ID executable
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may be toggled by switching to the real user ID, then re-enabled
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by reverting to the set-user-ID value.
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Similarly, the effective group ID may be set to the value
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of the real group ID or the saved set-user-ID.
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.Pp
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.Sh RETURN VALUES
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Upon success, these functions return 0;
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otherwise \-1 is returned.
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.Pp
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If the user is not the super user, or the uid
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specified is not the real, effective ID, or saved ID,
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these functions return \-1.
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.Sh SEE ALSO
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.Xr getuid 2 ,
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.Xr getgid 2
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.Sh STANDARDS
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The
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.Fn setuid
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and
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.Fn setgid
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functions are compliant with the
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.St -p1003.1-90
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specification with
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.Li _POSIX_SAVED_IDS
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not defined.
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We do not implement the
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.Li _POSIX_SAVED_IDS
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option as specified in the standard
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because this would make it impossible for a set-user-ID executable owned
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by a user other than the super-user to permanently revoke its privileges.
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.Pp
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The
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.Fn seteuid
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and
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.Fn setegid
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functions are extensions based on the
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.Tn POSIX
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concept of
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.Li _POSIX_SAVED_IDS ,
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and have been proposed for a future revision of the standard.
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They provide the same feature of toggling effective IDs as
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.Li _POSIX_SAVED_IDS ,
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but do so independent of the current effective
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ID, rather than requiring the super-user to permanently revoke its
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privileges.
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