CLOCKCTL(4)             NetBSD 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-priv- ileged 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. NetBSD 8.0 February 19, 2009 NetBSD 8.0

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