Switch from the SunOS adjtime() based driver to the timex driver.
There is no FreeBSD-specific code, so call SYS_Timex_Initialise()
and SYS_Timex_Finalise() directly from sys.c.
Remove the driver functions based on adjtime() and switch to the new
timex driver, which is based on ntp_adjtime(). This allows chronyd to
control the kernel frequency, adjust the offset with sub-microsecond
accuracy, and set the kernel leap and sync status. A drawback is that
the maximum slew rate is now limited by the 500 ppm maximum frequency
offset, while adjtime() on NetBSD slewed by up to 5000 ppm.
Remove functions that are included in the new timex driver. Keep only
functions that have extended functionality, i.e. read and set the
frequency using the timex tick field and apply step offset with
ADJ_SETOFFSET.
Merge the code from wrap_adjtimex.c that is still needed with
sys_linux.c and remove the file.
This is based on sys_linux.c and wrap_adjtimex.c. It's intended for all
systems that support the adjtimex() or ntp_adjtime() system call. The
driver functions can be replaced with extended system-specific versions
(e.g. to control the frequency with the tick field on Linux).
Include a test program to determine how the adjtime() implementation
behaves. Check the range of supported offset, support for readonly
operation, and slew rate with different update intervals and offsets.
Also, add a test for ntp_adjtime() to check what frequency range it
supports.
Since the NTPv4 update, the detection of synchronization loops based on
the refid prevents a server to initialize its clock from its clients
after restart. Remove that part from the recommended configuration.
Also, mention the time smoothing feature.
The Linux secure computing (seccomp) facility allows a process to
install a filter in the kernel that will allow only specific system
calls to be made. The process is killed when trying to make other system
calls. This is useful to reduce the kernel attack surface and possibly
prevent kernel exploits when the process is compromised.
Use the libseccomp library to add rules and load the filter into the
kernel. Keep a list of system calls that are always allowed after
chronyd is initialized. Restrict arguments that may be passed to the
socket(), setsockopt(), fcntl(), and ioctl() system calls. Arguments
to socketcall(), which is used on some architectures as a multiplexer
instead of separate socket system calls, are not restricted for now.
The mailonchange directive is not allowed as it calls sendmail.
Calls made by the libraries that chronyd is using have to be covered
too. It's difficult to determine which system calls they need as it may
change after an upgrade and it may depend on their configuration (e.g.
resolver in libc). There are also differences between architectures. It
can all break very easily and is therefore disabled by default. It can
be enabled with the new -F option.
This is based on a patch from Andrew Griffiths <agriffit@redhat.com>.
Fix RTC_Linux_TimePreInit() to return 0 when the RTC device can be
opened, but reading its time fails to at least have the time restored
from the driftfile.
When a large spike occurs in offset_sd the drift removal interval can be
set to an excessively long time, although what ever event caused the
perturbation has passed. At the next set_sync_status() we now compare
the expected drift removal interval with that currently in effect. If
they are significantly different, the current timer is cancelled and new
cycle started using the new drift removal interval.
The optimization avoiding unnecessary setting of the kernel leap status
can cause a problem when something outside chronyd sets the status to
the new expected value. There will be no TMX_SetLeap() call which would
update the saved status and the kernel status will be overwritten with
the old (incorrect) value in a later TMX_*() call.
Always call TMX_SetLeap() to save the new value and for the log message
selection just check if a leap second has been applied.
Adds option -P to chronyd on MacOS X which can be used to enable the
thread time constraint scheduling policy. This near real-time scheduling
policy removes a 1usec bias from the 'System time' offset.
Add maxdistance directive to set the maximum root distance the sources
are allowed to have to be selected. This is useful to reject NTPv4
sources that are no longer synchronized and report large dispersion.
The default value is 3 seconds.
On NetBSD programs with write access to /dev/clockctl can adjust or set
the system clock without the root privileges. Add a function to drop the
privileges and check if the process has write access to the device to
get a more descriptive error message when the chrony uid/gid doesn't
match the owner of the device.
Call the CAM, NIO, NCR initialization functions and setup the access
restrictions before root is dropped. This will be needed on NetBSD,
where it's not possible to bind sockets to privileged ports without the
root privileges. Split the creation of the Unix domain command socket
from the CAM initialization to keep the chrony user as the owner of the
socket.
Follow the removal of the server authentication support and remove also
the client support. The -a and -f options are now silently ignored to
not break scripts. The authhash and password commands print a warning,
but they don't return an error.
With the new support for cmdmon over Unix domain sockets, authentication
is no longer necessary to authorize a client running on localhost with
the permissions of the root or chrony user/group. Remove the cmdmon
authentication support to simplify the code and significantly reduce the
attack surface of the protocol.
Only monitoring commands are now allowed remotely. Users that need to
configure chronyd remotely or locally without root/chrony permissions
are advised to use ssh and/or sudo.
Allow all commands received from the Unix domain command socket (which
is accessible only by the root and chrony user/group), even when they
are not authenticated with the command key.
Allow multiple hostnames/addresses separated by comma to be specified
with the -h option. Hostnames are resolved to up to 16 addresses. When
connecting to an address fails or no reply is received, try the next
address in the list.
Set the default value for the -h option to 127.0.0.1,::1.
If the specified hostname starts with /, consider it to be the path of
the chronyd Unix domain command socket. Create the client socket in the
same directory as the server socket (which is not accessible by others)
and change its permission to 0666 to allow chronyd running without root
privileges to send a reply. Remove the socket on exit.
Call connect() on the socket to set the remote address and switch from
sendto()/recvfrom() to send()/recv(). Setting the IP_RECVERR option no
longer seems to be necessary in order to get ECONNREFUSED errors.
