Some RTCs supported by the Linux kernel don't support the RTC_UIE_ON/OFF
ioctls, which causes chronyd started with the -s option to get stuck in
the initial RTC mode.
After opening the RTC device in the initialization, return error if
the ioctls are not supported to prevent the upper layer from calling the
time_init() function and expecting it to finish.
The function may be called from a separate thread, but logging is not
considered thread safe (e.g. due to using functions which read
environment variables).
Add a function to open a file for reading, writing, or appending.
In uppercase modes errors are handled as fatal, i.e. the caller doesn't
need to check for NULL. To avoid string manipulations in the callers,
the function accepts an optional directory and suffix. New files are
created with specified permissions, which will be needed for saving
keys. The O_EXCL flag is used in the writing mode to make sure a new
file is created (on filesystems that support it).
Also, add a function to rename a temporary file by changing its suffix,
and a function to remove a file.
All functions log all errors, at least as debug messages.
When replacing an existing rtc file with the temporary file, don't
change the ownership or permissions of the temporary file to match the
old rtc file, as if it didn't exist.
When replacing an existing drift file with the temporary file, don't
change the ownership or permissions of the temporary file to match the
old drift file, as if it didn't exist.
Include <limits.h> and use the PATH_MAX macro to define the length of
buffers containing paths to make it constistent. (It's not supposed to
fit all possible paths.)
Call exit() in LOG_Message() after printing a fatal message to allow the
LOG macro or LOG_Message() to be used directly instead of the LOG_FATAL
macro.
Allow a cipher (AES128 or AES256) to be specified as the type of a key
in the key file to authenticate NTP packets with a CMAC instead of the
NTPv4 (RFC 5905) MAC using a hash function. This follows RFC 8573.
Remove the magic constant compensating for copying, conversions, etc.
It cannot possibly be accurate on all hardware. The delay is supposed to
be a minimum delay.
An analysis by Tim Ruffing [1] shows that a length extension attack
adding valid extension fields to NTPv4 packets is possible with some
specific key lengths and hash functions using little-endian length like
MD5 and RIPEMD160.
chronyd currently doesn't process or generate any extension fields, but
it could be a problem in future when a non-authentication extension
field is supported.
Drop support for all RIPEMD functions as they don't seem to be secure in
the context of the NTPv4 MAC. MD5 is kept only for compatibility.
[1] https://mailarchive.ietf.org/arch/msg/ntp/gvibuB6bTbDRBumfHNdJ84Kq4kA
Improve the client's test D to compare the stratum, reference ID,
reference timestamp, and root delay from the received packet with its
own reference data in order to prevent it from synchronizing to itself,
e.g. due to a misconfiguration.
In the local reference mode, instead of returning the adjusted current
time as the reference time, return the same timestamp updated only once
per about 62.5 seconds.
This will enable chronyd to detect polling of itself even when the local
reference mode is active.
Instead of converting the reference timestamp to the NTP format and
back, add a negative double value to the timestamp directly. Move the
code to a separate function. This will allow the timestamp to stay
outside the compiled-in NTP era, which is useful for testing of the
cmdmon protocol.
