NetBSD-5.0.2/share/man/man4/clockctl.4

.\"	$NetBSD: clockctl.4,v 1.5.4.1 2009/03/31 23:32:06 snj Exp $
.\"
.\" Copyright (c) 2001 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Emmanuel Dreyfus.
.\"
.\" 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.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
.\"
.Dd February 19, 2009
.Dt CLOCKCTL 4
.Os
.Sh NAME
.Nm clockctl
.Nd Clock subsystem user control
.Sh SYNOPSIS
.Cd pseudo-device clockctl
.Sh DESCRIPTION
The
.Nm
interface brings clock control to non-root users. Any user with write access
to
.Pa /dev/clockctl
will be able to perform operations such as
.Xr settimeofday 2 ,
.Xr clock_settime 2 ,
.Xr adjtime 2 ,
or
.Xr ntp_adjtime 2 ,
which are normally restricted to the super-user. Using the
.Nm
pseudo-device, it is possible to run daemons such as
.Xr ntpd 8
as non-privileged users, thus reducing the security exposure if a
compromise is found in such a daemon.
.Pp
The
.Nm
pseudo-device driver provides an
.Xr ioctl 2
call for each privileged clock-related system call. The system
call stubs in C library will use the
.Xr ioctl 2
on
.Pa /dev/clockctl
if the special file is present and accessible, or will revert to the
plain super-user-restricted system call if the special file is not accessible.
.Pp
The following
.Xr ioctl 2
calls are defined in
.Aq Pa sys/clockctl.h :
.Bl -tag -width CLOCKCTL
.It Dv CLOCKCTL_SETTIMEOFDAY
This will run the
.Xr settimeofday 2
system call. Argument should be a pointer to a
.Va struct clockctl_settimeofday :
.Bd -literal
struct clockctl_settimeofday {
	const struct timeval *tv;
	const void *tzp;
};
.Ed
.It Dv CLOCKCTL_CLOCK_SETTIME
This will run the
.Xr clock_settime 2
system call. Argument should be a pointer to a
.Va struct clockctl_clock_settime :
.Bd -literal
struct clockctl_clock_settime {
	clockid_t clock_id;
	struct timespec *tp;
};
.Ed
.It Dv CLOCKCTL_ADJTIME
This will run the
.Xr adjtime 2
system call. Argument should be a pointer to a
.Va struct clockctl_adjtime :
.Bd -literal
struct clockctl_adjtime {
	const struct timeval *delta;
	struct timeval *olddelta;
};
.Ed
.It Dv CLOCKCTL_NTP_ADJTIME
This will run the
.Xr ntp_adjtime 2
system call. Argument should be a pointer to a
.Va struct clockctl_ntp_adjtime :
.Bd -literal
struct clockctl_ntp_adjtime {
	struct timex *tp;
.\" Following member is commented out intentionally.
.\"	register_t retval;
};
.Ed
.El
.Sh SEE ALSO
.Xr adjtime 2 ,
.Xr clock_settime 2 ,
.Xr ioctl 2 ,
.Xr settimeofday 2
.Sh HISTORY
.Nm
appeared in
.Nx 1.6 .