Otherwise doing comparing a CGroupMask (which is unsigned in effect)
with the result of CGROUP_CONTROLLER_TO_MASK() will result in warnings
about signedness differences.
We now have the "BPF" pseudo-controllers. These should never be assumed
to be accessible as /sys/fs/cgroup/<controller> and not through
"cgroup.subtree_control" either, hence always check explicitly before we
go to the file system. We do this through our new CGROUP_MASK_V1 and
CGROUP_MASK_V2 definitions.
Also, when we fail, don't clobber the return value.
This brings the call more in-line with our usual coding style, and
removes surprises.
None of the callers seemed to care about this behaviour.
That way we can pin a specific inode and analyze it and manipulate it
without it being swapped out beneath our hands.
Fixes a vulnerability originally found by Jann Horn from Google.
CVE-2018-15687
LP: #1796692https://bugzilla.redhat.com/show_bug.cgi?id=1639076
When we start a service process we pass the selected watchdog timeout to
it with the $WATCHDOG_USEC environment variable. If the unit file is
reconfigured later, we need to make sure to continue to honour the
original timeout, i.e. watch $WATCHDOG_USEC was set to, otherwise we'll
expect the ping at a different time as the service process is sending it
to us.
Hence, whenever we start a unit, save the watchdog timeout, and stick to
that for everything we do.
Fixes: #9467
Let's make sure we always use the right watchdog timeout: when a service
has overwritten it, then stick to it, also for follow-up processes of
the same service.
This was mostly prompted by seeing the expression "in_initrd() && flags
& PROC_CMDLINE_RD_STRICT", which uses & and && without any brackets.
Let's make that a bit more readable and hide all doubts about operator
precedence.
Let's be more careful with what we serialize: let's ensure we never
serialize strings that are longer than LONG_LINE_MAX, so that we know we
can read them back with read_line(…, LONG_LINE_MAX, …) safely.
In order to implement this all serialization functions are move to
serialize.[ch], and internally will do line size checks. We'd rather
skip a serialization line (with a loud warning) than write an overly
long line out. Of course, this is just a second level protection, after
all the data we serialize shouldn't be this long in the first place.
While we are at it also clean up logging: while serializing make sure to
always log about errors immediately. Also, (void)ify all calls we don't
expect errors in (or catch errors as part of the general
fflush_and_check() at the end.
The predicate function manager_timestamp_shall_serialize() simply says
whether to serialize or not serialize a timestamp, and should make
things a bit easier to read.
Yu Watanabe
Lennart Poettering
Evgeny Vereshchagin
Zbigniew Jędrzejewski-Szmek