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NetBSD 6.1.5 - man page for clockctl (netbsd section 4)

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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 operations 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 compromise 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
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