CLOCKCTL(4)						   BSD Kernel Interfaces Manual 					       CLOCKCTL(4)

NAME

     clockctl -- Clock subsystem user control

SYNOPSIS

     pseudo-device clockctl

DESCRIPTION

     The clockctl interface brings clock control to non-root users.  Any user with write access to /dev/clockctl will be able to perform opera-
     tions such as settimeofday(2), clock_settime(2), adjtime(2), or ntp_adjtime(2), which are normally restricted to the super-user.  Using the
     clockctl pseudo-device, it is possible to run daemons such as ntpd(8) as non-privileged users, thus reducing the security exposure if a com-
     promise is found in such a daemon.

     The clockctl pseudo-device driver provides an ioctl(2) call for each privileged clock-related system call.  The system call stubs in C
     library will use the ioctl(2) on /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.

     The following ioctl(2) calls are defined in <sys/clockctl.h>:

     CLOCKCTL_SETTIMEOFDAY
	       This will run the settimeofday(2) system call.  Argument should be a pointer to a struct clockctl_settimeofday:

	       struct clockctl_settimeofday {
		       const struct timeval *tv;
		       const void *tzp;
	       };

     CLOCKCTL_CLOCK_SETTIME
	       This will run the clock_settime(2) system call.	Argument should be a pointer to a struct clockctl_clock_settime:

	       struct clockctl_clock_settime {
		       clockid_t clock_id;
		       struct timespec *tp;
	       };

     CLOCKCTL_ADJTIME
	       This will run the adjtime(2) system call.  Argument should be a pointer to a struct clockctl_adjtime:

	       struct clockctl_adjtime {
		       const struct timeval *delta;
		       struct timeval *olddelta;
	       };

     CLOCKCTL_NTP_ADJTIME
	       This will run the ntp_adjtime(2) system call.  Argument should be a pointer to a struct clockctl_ntp_adjtime:

	       struct clockctl_ntp_adjtime {
		       struct timex *tp;
	       };

SEE ALSO

     adjtime(2), clock_settime(2), ioctl(2), settimeofday(2)

HISTORY

     clockctl appeared in NetBSD 1.6.

BSD
								 February 19, 2009							       BSD