NetBSD/share/man/man4/clockctl.4

.\"	$NetBSD: clockctl.4,v 1.3 2001/11/23 21:06:02 jhawk Exp $
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.\" by Emmanuel Dreyfus.
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.Dd October 20, 2001
.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 Ns :
.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_args :
.Bd -literal
struct clockctl_settimeofday_args {
    struct timeval tv;
    struct timezone 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_args :
.Bd -literal
struct clockctl_clock_settime_args {
    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_args :
.Bd -literal
struct clockctl_adjtime_args {
    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_args :
.Bd -literal
struct clockctl_ntp_adjtime_args {
    struct timex tp;
};
.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 .