Delegation to unpriviliged processes is safe in the unified hierarchy,
hence allow it. This has the benefit of permitting "systemd --user"
instances to further partition their resources between user services.
Makre sure we always return sensible errors for the various, following
the same rules, and document them in a comment in sd-login.c. Also,
update all relevant man pages accordingly.
RT signals operate in a queue, and we should be careful to never merge
two queued signals into one. Hence, makes sure we only ever dequeue a
single signal at a time and leave the remaining ones queued in the
signalfd. In order to implement correct priorities for the signals
introduce one signalfd per priority, so that we only process the highest
priority signal at a time.
In the unified hierarchy delegating controller access is safe, hence
make sure to enable all controllers for the "payload" subcgroup if we
create it, so that the container will have all controllers enabled the
nspawn service itself has.
If the controller managed by systemd cannot found in /proc/$PID/cgroup,
return ENODATA, the usual error for cases where the data being looked
for does not exist, even if the process does.
Previously, on the legacy hierarchy a non-existing cgroup was considered
identical to an empty one, but the unified hierarchy the check for a
non-existing one returned ENOENT.
Let's move the actual cgroup part of it into a new separate function
manager_get_unit_by_pid_cgroup(), and then make
manager_get_unit_by_pid() just a wrapper that also checks the two pid
hashmaps.
Then, let's make sure the various calls that want to deliver events to
the owners of a PID check both hashmaps and the cgroup and deliver the
event to *each* of them. OTOH make sure bus calls like GetUnitByPID()
continue to check the PID hashmaps first and the cgroup only as
fallback.
This simply factors out the uid validation checks from parse_uid() and
uses them everywhere. This simply verifies that the passed UID is
neither 64bit -1 nor 32bit -1.
This adds a new PID_TO_PTR() macro, plus PTR_TO_PID() and makes use of
it wherever we maintain processes in a hash table. Previously we
sometimes used LONG_TO_PTR() and other times ULONG_TO_PTR() for that,
hence let's make this more explicit and clean up things.
Show the same recommended example file in all three man pages, just
highlight the different, relevant parts.
This should be less confusing for users, and clarify what we actually
recommend how /etc/nsswitch.conf is set up.
The recent cgroup-rework changed the error code for un-mounted cgroupfs to
ENOEXEC. Make sure udev ignores it just like ENOENT and does not spill
warnings on the screen.
Virtio buses are undeterministically enumerated, so we cannot use them as a basis
for deterministic naming (see bf81e792f3). However, we are guaranteed that there
is only ever one virtio bus for every parent device, so we can simply skip over
the virtio buses when naming the devices.
This patch set adds full support the new unified cgroup hierarchy logic
of modern kernels.
A new kernel command line option "systemd.unified_cgroup_hierarchy=1" is
added. If specified the unified hierarchy is mounted to /sys/fs/cgroup
instead of a tmpfs. No further hierarchies are mounted. The kernel
command line option defaults to off. We can turn it on by default as
soon as the kernel's APIs regarding this are stabilized (but even then
downstream distros might want to turn this off, as this will break any
tools that access cgroupfs directly).
It is possibly to choose for each boot individually whether the unified
or the legacy hierarchy is used. nspawn will by default provide the
legacy hierarchy to containers if the host is using it, and the unified
otherwise. However it is possible to run containers with the unified
hierarchy on a legacy host and vice versa, by setting the
$UNIFIED_CGROUP_HIERARCHY environment variable for nspawn to 1 or 0,
respectively.
The unified hierarchy provides reliable cgroup empty notifications for
the first time, via inotify. To make use of this we maintain one
manager-wide inotify fd, and each cgroup to it.
This patch also removes cg_delete() which is unused now.
On kernel 4.2 only the "memory" controller is compatible with the
unified hierarchy, hence that's the only controller systemd exposes when
booted in unified heirarchy mode.
This introduces a new enum for enumerating supported controllers, plus a
related enum for the mask bits mapping to it. The core is changed to
make use of this everywhere.
This moves PID 1 into a new "init.scope" implicit scope unit in the root
slice. This is necessary since on the unified hierarchy cgroups may
either contain subgroups or processes but not both. PID 1 hence has to
move out of the root cgroup (strictly speaking the root cgroup is the
only one where processes and subgroups are still allowed, but in order
to support containers nicey, we move PID 1 into the new scope in all
cases.) This new unit is also used on legacy hierarchy setups. It's
actually pretty useful on all systems, as it can then be used to filter
journal messages coming from PID 1, and so on.
The root slice ("-.slice") is now implicitly created and started (and
does not require a unit file on disk anymore), since
that's where "init.scope" is located and the slice needs to be started
before the scope can.
To check whether we are in unified or legacy hierarchy mode we use
statfs() on /sys/fs/cgroup. If the .f_type field reports tmpfs we are in
legacy mode, if it reports cgroupfs we are in unified mode.
This patch set carefuly makes sure that cgls and cgtop continue to work
as desired.
When invoking nspawn as a service it will implicitly create two
subcgroups in the cgroup it is using, one to move the nspawn process
into, the other to move the actual container processes into. This is
done because of the requirement that cgroups may either contain
processes or other subgroups.
We should never connect to the host bus as fallback if connecting to a
container failed via one method. Otherwise connecting to a dbus1
container will always result in a connection to the host.
We rely on the correct error used when opening the kdbus device node,
hence let's make sure we pass it up from the namespaced child process to
the process which actually wants to connect.
