130 lines
4.1 KiB
Groff
130 lines
4.1 KiB
Groff
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.\" $NetBSD: clockctl.4,v 1.1 2001/10/20 09:10:33 manu Exp $
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.\"
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.\" Copyright (c) 2001 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Emmanuel Dreyfus.
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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 NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd Octobrer 20, 2001
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.Dt CLOCKCTL 4
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.Os
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.Sh NAME
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.Nm clockctl
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.Nd Clock subsystem user control
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.Sh SYNOPSIS
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.Cd pseudo-device clockctl
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.Sh DESCRIPTION
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The
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.Nm
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interface brings clock control to non root users. Any user with write access
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to
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.Pa /dev/clockctl
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will be able to perform operations such as
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.Xr settimeofday 2 ,
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.Xr clock_settime 2 ,
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.Xr adjtime 2 ,
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or
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.Xr ntp_adjtime 2 ,
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which are normally restricted to the super-user. Using the
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.Nm
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pseudodevice, it is possible to run daemons such as
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.Xr ntpd 8
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as a non privilegied user, thus lowereing the security implications if an
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exploit is found in this daemon.
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.Pp
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The
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.Nm
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pseudodevice driver provides an
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.Xr ioctl 2
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call for each of the privilegied clock-related system calls. The system
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call stubs in libc will use the
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.Xr ioctl 2
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on
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.Pa /dev/clockctl
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if the special file is present and accessible, or it will revert to the
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plain super-user restricted system call if it is not accessible.
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.Pp
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The following
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.Xr ioctl 2
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calls are defined in
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.Aq Pa sys/clockctl.h Ns :
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.Bl -tag -width CLOCKCTL
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.It Dv CLOCKCTL_SETTIMEOFDAY
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This will run the
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.Xr settimeofday 2
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system call. Argument should be a pointer to a
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.Va struct clockctl_settimeofday_args :
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.Bd -literal
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struct clockctl_settimeofday_args {
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struct timeval tv;
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struct timezone tzp;
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};
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.Ed
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.It Dv CLOCKCTL_CLOCK_SETTIME
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This will run the
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.Xr clock_settime 2
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system call. Argument should be a pointer to a
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.Va struct clockctl_clock_settime_args :
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.Bd -literal
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struct clockctl_clock_settime_args {
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clockid_t clock_id;
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struct timespec tp;
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};
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.Ed
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.It Dv CLOCKCTL_ADJTIME
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This will run the
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.Xr adjtime 2
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system call. Argument should be a pointer to a
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.Va struct clockctl_adjtime_args :
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.Bd -literal
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struct clockctl_adjtime_args {
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struct timeval delta;
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struct timeval olddelta;
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};
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.Ed
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.It Dv CLOCKCTL_NTP_ADJTIME
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This will run the
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.Xr ntp_adjtime 2
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system call. Argument should be a pointer to a
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.Va struct clockctl_ntp_adjtime_args :
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.Bd -literal
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struct clockctl_ntp_adjtime_args {
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struct timex tp;
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};
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.Ed
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.El
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.Sh SEE ALSO
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.Xr settimeofday 2 ,
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.Xr clock_settime 2 ,
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.Xr adjtime 2 ,
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.Xr ioctl 2 .
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