Slice/ControlGroup only really makes sense for unit types which actually
have cgroups attached to them, hence move them out of the generic Unit
interface and into the specific unit type interfaces.
These fields will continue to be part of Unit though, simply because
things are a log easier that way. However, regardless how this looks
internally we should keep things clean and independent of the specific
implementation of the inside.
"Scope" units are very much like service units, however with the
difference that they are created from pre-existing processes, rather
than processes that systemd itself forks off. This means they are
generated programmatically via the bus API as transient units rather
than from static configuration read from disk. Also, they do not provide
execution-time parameters, as at the time systemd adds the processes to
the scope unit they already exist and the parameters cannot be applied
anymore.
The primary benefit of this new unit type is to create arbitrary cgroups
for worker-processes forked off an existing service.
This commit also adds a a new mode to "systemd-run" to run the specified
processes in a scope rather then a transient service.
Transient units can be created via the bus API. They are configured via
the method call parameters rather than on-disk files. They are subject
to normal GC. Transient units currently may only be created for
services (however, we will extend this), and currently only ExecStart=
and the cgroup parameters can be configured (also to be extended).
Transient units require a unique name, that previously had no
configuration file on disk.
A tool systemd-run is added that makes use of this functionality to run
arbitrary command lines as transient services:
$ systemd-run /bin/ping www.heise.de
Will cause systemd to create a new transient service and run ping in it.
This introduces two bus calls to make runtime changes to selected bus
properties, optionally with persistence.
This currently hooks this up only for three cgroup atributes, but this
brings the infrastructure to add more changable attributes.
This allows setting multiple attributes at once, and takes an array
rather than a dictionary of properties, in order to implement simple
resetting of lists using the same approach as when they are sourced from
unit files. This means, that list properties are appended to by this
call, unless they are first reset via assigning the empty list.
Replace the very generic cgroup hookup with a much simpler one. With
this change only the high-level cgroup settings remain, the ability to
set arbitrary cgroup attributes is removed, so is support for adding
units to arbitrary cgroup controllers or setting arbitrary paths for
them (especially paths that are different for the various controllers).
This also introduces a new -.slice root slice, that is the parent of
system.slice and friends. This enables easy admin configuration of
root-level cgrouo properties.
This replaces DeviceDeny= by DevicePolicy=, and implicitly adds in
/dev/null, /dev/zero and friends if DeviceAllow= is used (unless this is
turned off by DevicePolicy=).
This complements existing functionality of setting variables
through 'systemctl set-environment', the kernel command line,
and through normal environment variables for systemd in session
mode.
- This changes all logind cgroup objects to use slice objects rather
than fixed croup locations.
- logind can now collect minimal information about running
VMs/containers. As fixed cgroup locations can no longer be used we
need an entity that keeps track of machine cgroups in whatever slice
they might be located. Since logind already keeps track of users,
sessions and seats this is a trivial addition.
- nspawn will now register with logind and pass various bits of metadata
along. A new option "--slice=" has been added to place the container
in a specific slice.
- loginctl gained commands to list, introspect and terminate machines.
- user.slice and machine.slice will now be pulled in by logind.service,
since only logind.service requires this slice.
In order to prepare for the kernel cgroup rework, let's introduce a new
unit type to systemd, the "slice". Slices can be arranged in a tree and
are useful to partition resources freely and hierarchally by the user.
Each service unit can now be assigned to one of these slices, and later
on login users and machines may too.
Slices translate pretty directly to the cgroup hierarchy, and the
various objects can be assigned to any of the slices in the tree.
When a sigchld is received from an alien child, main_pid is set to
0 then service_enter_running calls main_pid_good to check if the
child is running. This incorrectly returned true because
kill(main_pid, 0) would return >= 0.
This fixes an error where a service would die and the cgroup would
become empty but the service would still report as active (running).
We can assume that a service for which a watchdog timeout was triggered
is unresponsive to a clean shutdown. However, it still makes sense to
execute the post-stop cleanup commands that can be configured with
ExecStopPost=. Hence, when the timeout is hit enter STOP_SIGKILL rather
than FINAL_SIGKILL.
This is a minor fix because it's not a major issue, this fix just avoid
to get EINVAL error from sigaction(2).
There are two signals can not handled at user space, SIGKILL and
SIGSTOP even we're PID 1, trying to handle these two signals will get
EINVAL error.
There are two kinds of systemd instance, running as system manager or
user session manager, apparently, the latter is a general user space
process which can not handle SIGKILL. The special pid 1 also can not
do that refer to kernel/signal.c:do_sigaction().
However, pid 1 is unkillable because the kernel did attach
SIGNAL_UNKILLABLE to it at system boot up, refer to
init/main.c:start_kernel()
--> rest_init()
--> kernel_thread()
--> kernel_init()
--> init_post()
current->signal->flags |= SIGNAL_UNKILLABLE
This will add another color to the legend called "Loading unit files"
Like the generators it will mark a part of the systemd bar indicating
the time spent while loading unit files.
This partially reverts commit c3a170f3, which moved
efi_get_boot_timestamps too early in main(), before
/sys is assured to be mounted
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=64371
[tomegun: in particular /sys/firmware/efi/efivars needs to be
mounted, which is not a problem if a systemd-initramfs containing
the correct module is being used. But not everyone uses an
initramfs...]
Just calling service_enter_dead() does not kill any processes.
As a result, the old process may still be running when the new one is
started.
After a watchdog failure the service is in an undefined state.
Using the normal shutdown mechanism makes no sense. Instead all processes
are just killed and the service can try to restart.
Just as with SMACK, we don't really know if a policy has been
loaded or not, as the policy interface is write-only. Assume
therefore that if ima is present in securityfs that it is
enabled.
Update the man page to reflect that "ima" is a valid option
now as well.
According to Documentation/security/Smack.txt:
In keeping with the intent of Smack, configuration data is minimal
and not strictly required. The most important configuration step is
mounting the smackfs pseudo filesystem.
This means that checking the mount point should be enough.
Lennart Poettering
Zbigniew Jędrzejewski-Szmek
Auke Kok
Umut Tezduyar
Ross Lagerwall
Chengwei Yang
Thomas Hindoe Paaboel Andersen
Václav Pavlín
Lukas Nykryn
Nirbheek Chauhan
Eelco Dolstra
Zachary Cook
Michael Olbrich
Michal Schmidt
Karol Lewandowski