For example in a container we'd log:
Oct 17 17:01:10 rawhide systemd[1]: Started Power-Off.
Oct 17 17:01:10 rawhide systemd[1]: Forcibly powering off: unit succeeded
Oct 17 17:01:10 rawhide systemd[1]: Reached target Power-Off.
Oct 17 17:01:10 rawhide systemd[1]: Shutting down.
and on the console we'd write (in red)
[ !! ] Forcibly powering off: unit succeeded
This is not useful in any way, and the fact that we're calling an "emergency action"
is an internal implementation detail. Let's log about c-a-d and the watchdog actions
only.
The setting is now only looked at when considering an action for a job timeout
or unit start limit. It is ignored for ctrl-alt-del, SuccessAction, SuccessFailure.
v2: turn the parameter into a flag field
v3: rename Options to Flags
Let's make them typesafe, and let's add a nice macro helper for checking
if we are in a test run, which should make testing for this much easier
to read for most cases.
Cgroup v2 provides the eBPF-based device controller, which isn't currently
supported by systemd. This commit aims to provide such support.
There are no user-visible changes, just the device policy and whitelist
start working if cgroup v2 is used.
This shouldn't change control flow, with one exception: we won't send
notifications for boot progress to plymouth anymore during reload, which
is something we really shouldn't.
Allows configuring the watchdog signal (with a default of SIGABRT).
This allows an alternative to SIGABRT when coredumps are not desirable.
Appropriate references to SIGABRT or aborting were renamed to reflect
more liberal watchdog signals.
Closes#8658
Previously, we'd act immediately on StopWhenUnneeded= when a unit state
changes. With this rework we'll maintain a queue instead: whenever
there's the chance that StopWhenUneeded= might have an effect we enqueue
the unit, and process it later when we have nothing better to do.
This should make the implementation a bit more reliable, as the unit notify event
cannot immediately enqueue tons of side-effect jobs that might
contradict each other, but we do so only in a strictly ordered fashion,
from the main event loop.
This slightly changes the check when to consider a unit "unneeded".
Previously, we'd assume that a unit in "deactivating" state could also
be cleaned up. With this new logic we'll only consider units unneeded
that are fully up and have no job queued. This means that whenever
there's something pending for a unit we won't clean it up.
RootImage= may require the following settings
```
DeviceAllow=/dev/loop-control rw
DeviceAllow=block-loop rwm
DeviceAllow=block-blkext rwm
```
This adds the following settings implicitly when RootImage= is
specified.
Fixes#9737.
Usecase is to allow changing the final kill from SIGKILL to SIGQUIT which
should create a core dump useful for debugging why the service didn't stop
with the SIGTERM
These lines are generally out-of-date, incomplete and unnecessary. With
SPDX and git repository much more accurate and fine grained information
about licensing and authorship is available, hence let's drop the
per-file copyright notice. Of course, removing copyright lines of others
is problematic, hence this commit only removes my own lines and leaves
all others untouched. It might be nicer if sooner or later those could
go away too, making git the only and accurate source of authorship
information.
This part of the copyright blurb stems from the GPL use recommendations:
https://www.gnu.org/licenses/gpl-howto.en.html
The concept appears to originate in times where version control was per
file, instead of per tree, and was a way to glue the files together.
Ultimately, we nowadays don't live in that world anymore, and this
information is entirely useless anyway, as people are very welcome to
copy these files into any projects they like, and they shouldn't have to
change bits that are part of our copyright header for that.
hence, let's just get rid of this old cruft, and shorten our codebase a
bit.
Since bb28e68477 parsing failures of
certain unit file settings will result in load failures of units. This
introduces a new load state "bad-setting" that is entered in precisely
this case.
With this addition error messages on bad settings should be a lot more
explicit, as we don't have to show some generic "errno" error in that
case, but can explicitly say that a bad setting is at fault.
Internally this unit load state is entered as soon as any configuration
loader call returns ENOEXEC. Hence: config parser calls should return
ENOEXEC now for such essential unit file settings. Turns out, they
generally already do.
Fixes: #9107
This is very similar to the existing unit method coldplug() but is
called a bit later. The idea is that that coldplug() restores the unit
state from before any prior reload/restart, i.e. puts the deserialized
state in effect. The catchup() call is then called a bit later, to
catch up with the system state for which we missed notifications while
we were reloading. This is only really useful for mount, swap and device
mount points were we should be careful to generate all missing unit
state change events (i.e. call unit_notify() appropriately) for
everything that happened while we were reloading.
This reworks how systemd tracks processes on cgroupv1 systems where
cgroup notification is not reliable. Previously, whenever we had reason
to believe that new processes showed up or got removed we'd scan the
cgroup of the scope or service unit for new processes, and would tidy up
the list of PIDs previously watched. This scanning is relatively slow,
and does not scale well. With this change behaviour is changed: instead
of scanning for new/removed processes right away we do this work in a
per-unit deferred event loop job. This event source is scheduled at a
very low priority, so that it is executed when we have time but does not
starve other event sources. This has two benefits: this expensive work is
coalesced, if events happen in quick succession, and we won't delay
SIGCHLD handling for too long.
This patch basically replaces all direct invocation of
unit_watch_all_pids() in scope.c and service.c with invocations of the
new unit_enqueue_rewatch_pids() call which just enqueues a request of
watching/tidying up the PID sets (with one exception: in
scope_enter_signal() and service_enter_signal() we'll still do
unit_watch_all_pids() synchronously first, since we really want to know
all processes we are about to kill so that we can track them properly.
Moreover, all direct invocations of unit_tidy_watch_pids() and
unit_synthesize_cgroup_empty_event() are removed too, when the
unit_enqueue_rewatch_pids() call is invoked, as the queued job will run
those operations too.
All of this is done on cgroupsv1 systems only, and is disabled on
cgroupsv2 systems as cgroup-empty notifications are reliable there, and
we do not need SIGCHLD events to track processes there.
Fixes: #9138
This way we don't need to repeat the argument twice.
I didn't replace all instances. I think it's better to leave out:
- asserts
- comparisons like x & y == x, which are mathematically equivalent, but
here we aren't checking if flags are set, but if the argument fits in the
flags.
The function is similar to path_kill_slashes() but also removes
initial './', trailing '/.', and '/./' in the path.
When the second argument of path_simplify() is false, then it
behaves as the same as path_kill_slashes(). Hence, this also
replaces path_kill_slashes() with path_simplify().
This adds a flags parameter to unit_notify() which can be used to pass
additional notification information to the function. We the make the old
reload_failure boolean parameter one of these flags, and then add a new
flag that let's unit_notify() if we are configured to restart the
service.
Note that this adjusts behaviour of systemd to match what the docs say.
Fixes: #8398
When I see "test", I have to think three times what the return value
means. With "below" this is immediately clear. ratelimit_below(&limit)
sounds almost like English and is imho immediately obvious.
(I also considered ratelimit_ok, but this strongly implies that being under the
limit is somehow better. Most of the times this is true, but then we use the
ratelimit to detect triple-c-a-d, and "ok" doesn't fit so well there.)
C.f. a1bcaa07.
Scope units are populated from PIDs specified by the bus client. We do
that when a scope is started. We really shouldn't allow scopes to be
started multiple times, as the PIDs then might be heavily out of date.
Moreover, clients should have the guarantee that any scope they allocate
has a clear runtime cycle which is not repetitive.
Double newlines (i.e. one empty lines) are great to structure code. But
let's avoid triple newlines (i.e. two empty lines), quadruple newlines,
quintuple newlines, …, that's just spurious whitespace.
It's an easy way to drop 121 lines of code, and keeps the coding style
of our sources a bit tigther.
Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.
I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
Currently we add target dependencies while we are loading units. This
can create ordering loops even if configuration doesn't contain any
loop. Take for example following configuration,
$ systemctl get-default
multi-user.target
$ cat /etc/systemd/system/test.service
[Unit]
After=default.target
[Service]
ExecStart=/bin/true
[Install]
WantedBy=multi-user.target
If we encounter such unit file early during manager start-up (e.g. load
queue is dispatched while enumerating devices due to SYSTEMD_WANTS in
udev rules) we would add stub unit default.target and we order it Before
test.service. At the same time we add implicit Before to
multi-user.target. Later we merge two units and we create ordering cycle
in the process.
To fix the issue we will now never add any target dependencies until we
loaded all the unit files and resolved all the aliases.
This macro will read a pointer of any type, return it, and set the
pointer to NULL. This is useful as an explicit concept of passing
ownership of a memory area between pointers.
This takes inspiration from Rust:
https://doc.rust-lang.org/std/option/enum.Option.html#method.take
and was suggested by Alan Jenkins (@sourcejedi).
It drops ~160 lines of code from our codebase, which makes me like it.
Also, I think it clarifies passing of ownership, and thus helps
readability a bit (at least for the initiated who know the new macro)
Let's better check this inside of the call than before it, so that we
never issue this while reloading, even should these calls be called due
to other reasons than just the unit notify.
This makes sure the reload state is unset a bit earlier in
manager_reload() so that we can safely call this function from there and
they do the right thing.
Follow-up for e63ebf71ed.
path_is_normalized() will reject paths longer than 4095 bytes, so it's better
to not create a stack variable of unbounded size, but instead do the check first
and only then do that allocation.
Also use _cleanup_ to make things a bit shorter.
https://oss-fuzz.com/v2/issue/5424177403133952/7000
manager_recheck_journal() and manager_recheck_dbus() would be called to early
while we were deserialiazing units, before the systemd-journald.service and
dbus.service have been deserialized. In effect we'd disable logging to the
journald and close the bus connection. The first is not very noticable, it
mostly means that logs emitted during deserialization are lost. The second is
more noticeable, because manager_recheck_dbus() would call bus_done_api() and
bus_done_system() and close dbus connections. Logging and bus connection would
then be restored later after the respective units have been deserialized.
This is easily reproduced by calling:
$ sudo gdbus call --system --dest org.freedesktop.systemd1 --object-path /org/freedesktop/systemd1 --method "org.freedesktop.systemd1.Manager.Reload"
which works fine before 8559b3b75c, and then starts failing with:
Error: GDBus.Error:org.freedesktop.DBus.Error.NoReply: Remote peer disconnected
None of this should happen, and we should delay changing state until after
deserialization is complete when reloading. manager_reload() already included
the calls to manager_recheck_journal() and manager_recheck_dbus(), so the
connection state will be updated after deserialization during reloading is done.
Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1554578.
So, the kernel's management of cgroup/BPF programs is a bit misdesigned:
if you attach a BPF program to a cgroup and close the fd for it it will
stay pinned to the cgroup with no chance of ever removing it again (or
otherwise getting ahold of it again), because the fd is used for
selecting which BPF program to detach. The only way to get rid of the
program again is to destroy the cgroup itself.
This is particularly bad for root the cgroup (and in fact any other
cgroup that we cannot realistically remove during runtime, such as
/system.slice, /init.scope or /system.slice/dbus.service) as getting rid
of the program only works by rebooting the system.
To counter this let's closely keep track to which cgroup a BPF program
is attached and let's implicitly detach the BPF program when we are
about to close the BPF fd.
This hence changes the bpf_program_cgroup_attach() function to track
where we attached the program and changes bpf_program_cgroup_detach() to
use this information. Moreover bpf_program_unref() will now implicitly
call bpf_program_cgroup_detach().
In order to simplify things, bpf_program_cgroup_attach() will now
implicitly invoke bpf_program_load_kernel() when necessary, simplifying
the caller's side.
Finally, this adds proper reference counting to BPF programs. This
is useful for working with two BPF programs in parallel: the BPF program
we are preparing for installation and the BPF program we so far
installed, shortening the window when we detach the old one and reattach
the new one.
Before this change all unit types would default to "private" in the
system service manager and "inherit" to in the user service manager.
With this change this is slightly altered: non-service units of the
system service manager are now run with KeyringMode=shared. This appears
to be the more appropriate choice as isolation is not as desirable for
mount tools, which regularly consume key material. After all mounts are
a shared resource themselves as they appear system-wide hence it makes a
lot of sense to share their key material too.
Fixes: #8159
When various references to the unit were dropped during cleanup in unit_free(),
add_to_gc_queue() could be called on this unit. If the unit was previously in
the gc queue (at the time when unit_free() was called on it), this wouldn't
matter, because it'd have in_gc_queue still set even though it was already
removed from the queue. But if it wasn't set, then the unit could be added to
the queue. Then after unit_free() would deallocate the unit, we would be left
with a dangling pointer in gc_queue.
A unit could be added to the gc queue in two places called from unit_free():
in the job_install calls, and in unit_ref_unset(). The first was OK, because
it was above the LIST_REMOVE(gc_queue,...) call, but the second was not, because
it was after that. Move the all LIST_REMOVE() calls down.
We would free stuff like the names of the unit first, and then recurse
into other structures to remove the unit from there. Technically this
was OK, since the code did not access the name, but this makes debugging
harder. And if any log messages are added in any of those functions, they
are likely to access u->id and such other basic information about the unit.
So let's move the removal of this "basic" information towards the end
of unit_free().
A .socket will reference a .service unit, by registering a UnitRef with the
.service unit. If this .service unit has the .socket unit listed in Wants or
Sockets or such, a cycle will be created. We would not free this cycle
properly, because we treated any unit with non-empty refs as uncollectable. To
solve this issue, treats refs with UnitRef in u->refs_by_target similarly to
the refs in u->dependencies, and check if the "other" unit is known to be
needed. If it is not needed, do not treat the reference from it as preventing
the unit we are looking at from being freed.
No functional change.
The source unit manages the reference. It allocates the UnitRef structure and
registers it in the target unit, and then the reference must be destroyed
before the source unit is destroyed. Thus, is should be OK to include the
pointer to the source unit, it should be live as long as the reference exists.
v2:
- rename refs to refs_by_target
"check" is unclear: what is true, what is false? Let's rename to "can_gc" and
revert the return value ("positive" values are easier to grok).
v2:
- rename from unit_can_gc to unit_may_gc
This adds a new bus call to service and scope units called
AttachProcesses() that moves arbitrary processes into the cgroup of the
unit. The primary user for this new API is systemd itself: the systemd
--user instance uses this call of the systemd --system instance to
migrate processes if itself gets the request to migrate processes and
the kernel refuses this due to access restrictions.
The primary use-case of this is to make "systemd-run --scope --user …"
invoked from user session scopes work correctly on pure cgroupsv2
environments. There, the kernel refuses to migrate processes between two
unprivileged-owned cgroups unless the requestor as well as the ownership
of the closest parent cgroup all match. This however is not the case
between the session-XYZ.scope unit of a login session and the
user@ABC.service of the systemd --user instance.
The new logic always tries to move the processes on its own, but if
that doesn't work when being the user manager, then the system manager
is asked to do it instead.
The new operation is relatively restrictive: it will only allow to move
the processes like this if the caller is root, or the UID of the target
unit, caller and process all match. Note that this means that
unprivileged users cannot attach processes to scope units, as those do
not have "owning" users (i.e. they have now User= field).
Fixes: #3388
This removes the current bus_init() call, as it had multiple problems:
it munged handling of the three bus connections we care about (private,
"api" and system) into one, even though the conditions when which was
ready are very different. It also added redundant logging, as the
individual calls it called all logged on their own anyway.
The three calls bus_init_api(), bus_init_private() and bus_init_system()
are now made public. A new call manager_dbus_is_running() is added that
works much like manager_journal_is_running() and is a lot more careful
when checking whether dbus is around. Optionally it checks the unit's
deserialized_state rather than state, in order to accomodate for cases
where we cant to connect to the bus before deserializing the
"subscribed" list, before coldplugging the units.
manager_recheck_dbus() is added, that works a lot like
manager_recheck_journal() and is invoked in unit_notify(), i.e. when
units change state.
All in all this should make handling a bit more alike to journal
handling, and it also fixes one major bug: when running in user mode
we'll now connect to the system bus early on, without conditionalizing
this in anyway.
Let's simplify things a bit: we so far called both functions every
single time, let's just merge one into the other, so that we have fewer
functions to call.
Currently we allowed delegation for alluntis with cgroup backing
except for slices. Let's make this a bit more strict for now, and only
allow this in service and scope units.
Let's also add a generic accessor unit_cgroup_delegate() for checking
whether a unit has delegation turned on that checks the new bool first.
Also, when doing transient units, let's explcitly refuse turning on
delegation for unit types that don#t support it. This is mostly
cosmetical as we wouldn't act on the delegation request anyway, but
certainly helpful for debugging.
Previous code was using the basename(id->fragment_path) which returned
incorrect result if the unit was an instance.
For example, assuming that no instances of "template" have been created so far:
$ systemctl enable template@1
Created symlink from /etc/systemd/system/multi-user.target.wants/template@1.service to /usr/lib/systemd/system/template@.service.
$ systemctl is-enabled template@3.service
disabled
$ systemctl status template@3.service
● template@3.service - openQA Worker #3
Loaded: loaded (/usr/lib/systemd/system/template@.service; enabled; vendor preset: disabled)
[...]
Here the unit file states reported by "status" and "is-enabled" were different.
Before this, each ExecRuntime object is owned by a unit. However,
it may be shared with other units which enable JoinsNamespaceOf=.
Thus, by the serialization/deserialization process, its sharing
information, more specifically, reference counter is lost, and
causes issue #7790.
This makes ExecRuntime objects be managed by manager, and changes
the serialization/deserialization process.
Fixes#7790.
Let's add a per-unit boolean that tells us whether our unit is currently
counted or not. This way it's unlikely we get out of sync again and
things are generally more robust.
This also allows us to remove the counting logic specific to service
units (which was in fact mostly a copy from the generic implementation),
in favour of fully generic code.
Replaces: #7824
This call determines whether a specific unit currently needs access to
the console. It's a fancy wrapper around
exec_context_may_touch_console() ultimately, however for service units
we'll explicitly exclude the SERVICE_EXITED state from when we report
true.
Previously, we'd maintain two hashmaps keyed by PIDs, pointing to Unit
interested in SIGCHLD events for them. This scheme allowed a specific
PID to be watched by exactly 0, 1 or 2 units.
With this rework this is replaced by a single hashmap which is primarily
keyed by the PID and points to a Unit interested in it. However, it
optionally also keyed by the negated PID, in which case it points to a
NULL terminated array of additional Unit objects also interested. This
scheme means arbitrary numbers of Units may now watch the same PID.
Runtime and memory behaviour should not be impact by this change, as for
the common case (i.e. each PID only watched by a single unit) behaviour
stays the same, but for the uncommon case (a PID watched by more than
one unit) we only pay with a single additional memory allocation for the
array.
Why this all? Primarily, because allowing exactly two units to watch a
specific PID is not sufficient for some niche cases, as processes can
belong to more than one unit these days:
1. sd_notify() with MAINPID= can be used to attach a process from a
different cgroup to multiple units.
2. Similar, the PIDFile= setting in unit files can be used for similar
setups,
3. By creating a scope unit a main process of a service may join a
different unit, too.
4. On cgroupsv1 we frequently end up watching all processes remaining in
a scope, and if a process opens lots of scopes one after the other it
might thus end up being watch by many of them.
This patch hence removes the 2-unit-per-PID limit. It also makes a
couple of other changes, some of them quite relevant:
- manager_get_unit_by_pid() (and the bus call wrapping it) when there's
ambiguity will prefer returning the Unit the process belongs to based on
cgroup membership, and only check the watch-pids hashmap if that
fails. This change in logic is probably more in line with what people
expect and makes things more stable as each process can belong to
exactly one cgroup only.
- Every SIGCHLD event is now dispatched to all units interested in its
PID. Previously, there was some magic conditionalization: the SIGCHLD
would only be dispatched to the unit if it was only interested in a
single PID only, or the PID belonged to the control or main PID or we
didn't dispatch a signle SIGCHLD to the unit in the current event loop
iteration yet. These rules were quite arbitrary and also redundant as
the the per-unit handlers would filter the PIDs anyway a second time.
With this change we'll hence relax the rules: all we do now is
dispatch every SIGCHLD event exactly once to each unit interested in
it, and it's up to the unit to then use or ignore this. We use a
generation counter in the unit to ensure that we only invoke the unit
handler once for each event, protecting us from confusion if a unit is
both associated with a specific PID through cgroup membership and
through the "watch_pids" logic. It also protects us from being
confused if the "watch_pids" hashmap is altered while we are
dispatching to it (which is a very likely case).
- sd_notify() message dispatching has been reworked to be very similar
to SIGCHLD handling now. A generation counter is used for dispatching
as well.
This also adds a new test that validates that "watch_pid" registration
and unregstration works correctly.
It was forbidden to create mount units for a symlink. But the reason is
that the mount unit needs to know the real path that will appear in
/proc/self/mountinfo. The kernel dereferences *all* the symlinks in the
path at mount time (I checked this with `mount -c` running under `strace`).
This will have no effect on most systems. As recommended by docs, most
systems use /etc/fstab, as opposed to native mount unit files.
fstab-generator dereferences symlinks for backwards compatibility.
A relatively minor issue regarding Time Of Check / Time Of Use also exists
here. I can't see how to get rid of it entirely. If we pass an absolute
path to mount, the racing process can replace it with a symlink. If we
chdir() to the mount point and pass ".", the racing process can move the
directory. The latter might potentially be nicer, except that it breaks
WorkingDirectory=.
I'm not saying the race is relevant to security - I just want to consider
how bad the effect is. Currently, it can make the mount unit active (and
hence the job return success), despite there never being a matching entry
in /proc/self/mountinfo. This wart will be removed in the next commit;
i.e. it will make the mount unit fail instead.
Let's remove a number of synchronization points from our service
startups: let's drop synchronous match installation, and let's opt for
asynchronous instead.
Also, let's use sd_bus_match_signal() instead of sd_bus_add_match()
where we can.
This adds a new safe_fork() wrapper around fork() and makes use of it
everywhere. The new wrapper does a couple of things we previously did
manually and separately in a safer, more correct and automatic way:
1. Optionally resets signal handlers/mask in the child
2. Sets a name on all processes we fork off right after forking off (and
the patch assigns useful names for all processes we fork off now,
following a systematic naming scheme: always enclosed in () – in order
to indicate that these are not proper, exec()ed processes, but only
forked off children, and if the process is long-running with only our
own code, without execve()'ing something else, it gets am "sd-" prefix.)
3. Optionally closes all file descriptors in the child
4. Optionally sets a PR_SET_DEATHSIG to SIGTERM in the child, in a safe
way so that the parent dying before this happens being handled
safely.
5. Optionally reopens the logs
6. Optionally connects stdin/stdout/stderr to /dev/null
7. Debug logs about the forked off processes.
An auto-restarted unit B may depend on unit A with StopWhenUnneeded=yes.
If A stops before B's restart timeout expires, it'll be started again as part
of B's dependent jobs. However, if stopping takes longer than the timeout, B's
running stop job collides start job which also cancels B's start job. Result is
that neither A or B are active.
Currently, when a service with automatic restarting fails, it transitions
through following states:
1) SERVICE_FAILED or SERVICE_DEAD to indicate the failure,
2) SERVICE_AUTO_RESTART while restart timer is running.
The StopWhenUnneeded= check takes place in service_enter_dead between the two
state mentioned above. We temporarily store the auto restart flag to query it
during the check. Because we don't return control to the main event loop, this
new service unit flag needn't be serialized.
This patch prevents the pathologic situation when the service with Restart=
won't restart automatically. As a side effect it also avoid restarting the
dependency unit with StopWhenUnneeded=yes.
Fixes: #7377
This changes the unit search path logic to never drop the transient and
control directories from the unit search path. This is necessary as we
add new entries to both during runtime, due to the "systemctl
set-property" and transient unit logic.
Previously, the "transient" directory was created during early boot to
deal with this, but the "control" directories were not covered like
that. Creating the control directories early at boot is not possible
however, as /etc might be read-only then, and we do define a persistent
control directory. Hence, let's create these dirs on-demand when we need
them, and make sure the search path clean-up logic never drops them from
the search path even if they are initially missing.
(Also, always create these paths properly labelled)
This majorly refactors the transient unit file and drop-in writing
logic, so that we properly C-escape and specifier-escape (% → %%)
everything we write out, so that when we read it back again, specifiers
are parsed that aren't supposed to be parsed.
This renames unit_write_drop_in() and friends by unit_write_setting().
The name change is supposed to clarify that the functions are not only
used to write drop-in files, but also transient unit files.
The previous "mode" parameter to this function is replaced by a more
generic "flags", which knows additional flags for implicit C-style and
specifier escaping before writing things out. This can cover most
properties where either form of escaping is defined. For the cases where
this isn't sufficient, we add helpers unit_escape_setting() and
unit_concat_strv() for escaping individual strings or strvs properly.
While we are at it, we also prettify generation of transient unit files:
we try to reduce the number of section headers written out: previously
we'd write the right section header our for each setting. With this
change we do so only if the setting lives in a different section than
the one before.
(This should also be considered preparation for when we add proper APIs
to systemd to write normal, persistant unit files through the bus API)
Now that we don't kill control processes anymore, let's at least warn
about any processes left-over in the unit cgroup at the moment of
starting the unit.
Let's move the cgroup empty check for all unit types into the generic
unit_check_gc() call, out of the per-unit-type _check_gc() type. This
not only allows us to share some code, but also hooks up mount and
socket units with this kind of check, for free, as it was missing there
previously.
Before this patch, the bpf cgroup realization state was implicitly set
to "NO", meaning that the bpf configuration was realized but was turned
off. That means invalidation requests for the bpf stuff (which we issue
in blanket fashion when doing a daemon reload) would actually later
result in a us re-realizing the unit, under the assumption it was
already realized once, even though in reality it never was realized
before.
This had the effect that after each daemon-reload we'd end up realizing
*all* defined units, even the unloaded ones, populating cgroupfs with
lots of unneeded empty cgroups.
With this fix we properly set the realiazation state to "INVALIDATED",
i.e. indicating the bpf stuff was never set up for the unit, and hence
when we try to invalidate it later we won't do anything.
This introduces a new function unit_prepare_exec() that encapsulates a
number of calls we do in preparation for spawning off some processes in
all our unit types that do so.
This allows us to neatly unify a bit of code between unit types and
shorten our code.
SuccessAction= is similar to FailureAction= but declares what to do on
success of a unit, rather than on failure. This is useful for running
commands in qemu/nspawn images, that shall power down on completion. We
frequently see "ExecStopPost=/usr/bin/systemctl poweroff" or so in unit
files like this. Offer a simple, more declarative alternative for this.
While we are at it, hook up failure action with unit_dump() and
transient units too.
Already, path_is_safe() refused paths container the "." dir. Doing that
isn't strictly necessary to be "safe" by most definitions of the word.
But it is necessary in order to consider a path "normalized". Hence,
"path_is_safe()" is slightly misleading a name, but
"path_is_normalize()" is more descriptive, hence let's rename things
accordingly.
No functional changes.
Right now, the option only takes one of two possible values "inactive"
or "inactive-or-failed", the former being the default, and exposing same
behaviour as the status quo ante. If set to "inactive-or-failed" units
may be collected by the GC logic when in the "failed" state too.
This logic should be a nicer alternative to using the "-" modifier for
ExecStart= and friends, as the exit data is collected and logged about
and only removed when the GC comes along. This should be useful in
particular for per-connection socket-activated services, as well as
"systemd-run" command lines that shall leave no artifacts in the
system.
I was thinking about whether to expose this as a boolean, but opted for
an enum instead, as I have the suspicion other tweaks like this might be
a added later on, in which case we extend this setting instead of having
to add yet another one.
Also, let's add some documentation for the GC logic.
When preparing for a restart we quickly go through the DEAD/INACTIVE
service state before entering AUTO_RESTART. When doing this, we need to
make sure we don't destroy the FD store. Previously this was done by
checking the failure state of the unit, and keeping the FD store around
when the unit failed, under the assumption that the restart logic will
then get into action.
This is not entirely correct howver, as there might be failure states
that will no result in restarts.
With this commit we slightly alter the logic: a ref counter for the fd
store is added, that is increased right before we handle the restart
logic, and decreased again right-after.
This should ensure that the fdstore lives exactly as long as it needs.
Follow-up for f0bfbfac43.
And let's make use of it to implement two new unit settings with it:
1. LogLevelMax= is a new per-unit setting that may be used to configure
log priority filtering: set it to LogLevelMax=notice and only
messages of level "notice" and lower (i.e. more important) will be
processed, all others are dropped.
2. LogExtraFields= is a new per-unit setting for configuring per-unit
journal fields, that are implicitly included in every log record
generated by the unit's processes. It takes field/value pairs in the
form of FOO=BAR.
Also, related to this, one exisiting unit setting is ported to this new
facility:
3. The invocation ID is now pulled from /run/systemd/units/ instead of
cgroupfs xattrs. This substantially relaxes requirements of systemd
on the kernel version and the privileges it runs with (specifically,
cgroupfs xattrs are not available in containers, since they are
stored in kernel memory, and hence are unsafe to permit to lesser
privileged code).
/run/systemd/units/ is a new directory, which contains a number of files
and symlinks encoding the above information. PID 1 creates and manages
these files, and journald reads them from there.
Note that this is supposed to be a direct path between PID 1 and the
journal only, due to the special runtime environment the journal runs
in. Normally, today we shouldn't introduce new interfaces that (mis-)use
a file system as IPC framework, and instead just an IPC system, but this
is very hard to do between the journal and PID 1, as long as the IPC
system is a subject PID 1 manages, and itself a client to the journal.
This patch cleans up a couple of types used in journal code:
specifically we switch to size_t for a couple of memory-sizing values,
as size_t is the right choice for everything that is memory.
Fixes: #4089Fixes: #3041Fixes: #4441
Previously it was not possible to select which controllers to enable for
a unit where Delegate=yes was set, as all controllers were enabled. With
this change, this is made configurable, and thus delegation units can
pick specifically what they want to manage themselves, and what they
don't care about.
This replaces the dependencies Set* objects by Hashmap* objects, where
the key is the depending Unit, and the value is a bitmask encoding why
the specific dependency was created.
The bitmask contains a number of different, defined bits, that indicate
why dependencies exist, for example whether they are created due to
explicitly configured deps in files, by udev rules or implicitly.
Note that memory usage is not increased by this change, even though we
store more information, as we manage to encode the bit mask inside the
value pointer each Hashmap entry contains.
Why this all? When we know how a dependency came to be, we can update
dependencies correctly when a configuration source changes but others
are left unaltered. Specifically:
1. We can fix UDEV_WANTS dependency generation: so far we kept adding
dependencies configured that way, but if a device lost such a
dependency we couldn't them again as there was no scheme for removing
of dependencies in place.
2. We can implement "pin-pointed" reload of unit files. If we know what
dependencies were created as result of configuration in a unit file,
then we know what to flush out when we want to reload it.
3. It's useful for debugging: "systemd-analyze dump" now shows
this information, helping substantially with understanding how
systemd's dependency tree came to be the way it came to be.
The units that are not loaded don't have dropin_paths set. This
currently results in units that have fragments to always have
NeedDaemonReload=true when masked:
$ find {/usr/lib,/run/user/8086}/systemd/user/meh.service* |xargs ls -ld
lrwxrwxrwx. 1 lkundrak lkundrak 9 Oct 11 11:19 /run/user/8086/systemd/user/meh.service -> /dev/null
-rw-rw-r--. 1 root root 49 Oct 11 10:16 /usr/lib/systemd/user/meh.service
drwxrwxr-x. 2 root root 4096 Oct 11 10:50 /usr/lib/systemd/user/meh.service.d
-rw-rw-r--. 1 root root 666 Oct 11 10:50 /usr/lib/systemd/user/meh.service.d/override.conf
$ systemctl --user daemon-reload
$ busctl --user get-property org.freedesktop.systemd1 \
/org/freedesktop/systemd1/unit/meh_2eservice \
org.freedesktop.systemd1.Unit NeedDaemonReload
b true
In most cases we followed the rule that the special _INVALID and _MAX
values we use in our enums use the full type name as prefix (in contrast
to regular values that we often make shorter), do so for
ExecDirectoryType as well.
No functional changes, just a little bit of renaming to make this code
more like the rest.
This slightly changes how we log about failures. Previously,
service_enter_dead() would log that a service unit failed along with its
result code, and unit_notify() would do this again but without the
result code. For other unit types only the latter would take effect.
This cleans this up: we keep the message in unit_notify() only for debug
purposes, and add type-specific log lines to all our unit types that can
fail, and always place them before unit_notify() is invoked.
Or in other words: the duplicate log message for service units is
removed, and all other unit types get a more useful line with the
precise result code.
This makes sure that if we learn via inotify or another event source
that a cgroup is empty, and we checked that this is indeed the case (as
we might get spurious notifications through inotify, as the inotify
logic through the "cgroups.event" is pretty unspecific and might be
trigger for a variety of reasons), then we'll enqueue a defer event for
it, at a priority lower than SIGCHLD handling, so that we know for sure
that if there's waitid() data for a process we used it before
considering the cgroup empty notification.
Fixes: #6608
We are about to add second cgroup-related queue, called
"cgroup_empty_queue", hence let's rename "cgroup_queue" to
"cgroup_realize_queue" (as that is its purpose) to minimize confusion
about the two queues.
Just a rename, no functional changes.
This adds a new recognizable log message for each unit invocation that
contains structured information about consumed resources of the unit as
a whole after it terminated. This is particular useful for apps that
want to figure out what the resource consumption of a unit given a
specific invocation ID was.
The log message is only generated for units that have at least one
XyzAccounting= property turned on, and currently only covers IP traffic and CPU
time metrics.
With this change we'll invalidate all cgroup settings after coming back
from a daemon reload/reexec, so that the new settings are instantly
applied.
This is useful for the BPF case, because we don't serialize/deserialize
the BPF program fd, and hence have to install a new, updated BPF program
when coming back from the reload/reexec. However, this is also useful
for the rest of the cgroup settings, as it ensures that user
configuration really takes effect wherever we can.
Make sure the current IP accounting counters aren't lost during
reload/reexec.
Note that we destroy all BPF file objects during a reload: the BPF
programs, the access and the accounting maps. The former two need to be
regenerated anyway with the newly loaded configuration data, but the
latter one needs to survive reloads/reexec. In this implementation I
opted to only save/restore the accounting map content instead of the map
itself. While this opens a (theoretic) window where IP traffic is still
accounted to the old map after we read it out, and we thus miss a few
bytes this has the benefit that we can alter the map layout between
versions should the need arise.
Let's make sure that a socket unit's IPAddressAllow=/IPAddressDeny=
settings are in effect on all socket fds associated with it. In order to
make this happen we need to make sure the cgroup the fds are associated
with are the socket unit's cgroup. The only way to do that is invoking
socket()+accept() in them. Since we really don't want to migrate PID 1
around we do this by forking off a helper process, which invokes
socket()/accept() and sends the newly created fd to PID 1. Ugly, but
works, and there's apparently no better way right now.
This generalizes forking off per-unit helper processes in a new function
unit_fork_helper_process(), which is then also used by the NSS chown()
code of socket units.
Usually, it's a good thing that we isolate the kernel session keyring
for the various services and disconnect them from the user keyring.
However, in case of the cryptsetup key caching we actually want that
multiple instances of the cryptsetup service can share the keys in the
root user's user keyring, hence we need to be able to disable this logic
for them.
This adds KeyringMode=inherit|private|shared:
inherit: don't do any keyring magic (this is the default in systemd --user)
private: a private keyring as before (default in systemd --system)
shared: the new setting
The new unit_set_exec_params() call is to units what
manager_set_exec_params() is to the manager object: it initializes the
various fields from the relevant generic properties set.
We just abort startup, without printing any error. Make sure we always
print something, and when we cannot deserialize some unit, just ignore it and
continue.
Fixup for 4bc5d27b94. Without this, we would hang
in daemon-reexec after upgrade.
Since busname units are only useful with kdbus, they weren't actively
used. This was dead code, only compile-tested. If busname units are
ever added back, it'll be cleaner to start from scratch (possibly reverting
parts of this patch).
This reverts commit 2d058a87ff.
When we add another name to a unit (by following an alias), we need to
reload all drop-ins. This is necessary to load any additional dropins
found in the dirs created from the alias name.
Fixes#6334.
When running systemd-analyze verify I would get a random subset of warnings
(sometimes none, sometimes one or two):
dev-mapper-luks\x2d8db85dcf\x2d6230\x2d4e88\x2d940d\x2dba176d062b31.swap: Unit is bound to inactive unit dev-mapper-luks\x2d8db85dcf\x2d6230\x2d4e88\x2d940d\x2dba176d062b31.device. Stopping, too.
home.mount: Unit is bound to inactive unit dev-disk-by\x2duuid-75751556\x2d6e31\x2d438b\x2d99c9\x2dd626330d9a1b.device. Stopping, too.
boot.mount: Unit is bound to inactive unit dev-disk-by\x2duuid-56c56bfd\x2d93f0\x2d48fb\x2dbc4b\x2d90aa67144ea5.device. Stopping, too.
When running with debug on, it's pretty obvious what is happening:
home.mount: Changed dead -> mounted
home.mount: Unit is bound to inactive unit dev-disk-by\x2duuid-75751556\x2d6e31\x2d438b\x2d99c9\x2dd626330d9a1b.device. Stopping, too.
home.mount: Trying to enqueue job home.mount/stop/fail
home.mount: Installed new job home.mount/stop as 27
home.mount: Enqueued job home.mount/stop as 27
...
dev-disk-by\x2duuid-75751556\x2d6e31\x2d438b\x2d99c9\x2dd626330d9a1b.device: Installed new job dev-disk-by\x2duuid-75751556\x2d6e31\x2d438b\x2d99c9\x2dd626330d9a1b.device/start as 47
dev-disk-by\x2duuid-75751556\x2d6e31\x2d438b\x2d99c9\x2dd626330d9a1b.device: Changed dead -> plugged
dev-disk-by\x2duuid-75751556\x2d6e31\x2d438b\x2d99c9\x2dd626330d9a1b.device: Job dev-disk-by\x2duuid-75751556\x2d6e31\x2d438b\x2d99c9\x2dd626330d9a1b.device/start finished, result=done
Fixes#2206, https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=808151.
When a DBus name is released, NameOwnerChanged signal contains an empty string
as new_owner. Commit bbc2908 changed interpretation of the empty string to a
valid name, which is not consistent with values that are sent by dbus-daemon.
As a side effect, this masks symptoms of systemd-logind dbus disconnections
(#2925) by completely restarting it so it can freshly reconnect to dbus.
The state of a unit was not fully restored, especially the
"cgroup_realized_mask/cgroup_enabled_mask" fields were missing.
This could be seen with the following sequence:
$ systemctl show -p TasksCurrent sshd
TasksCurrent=1
$ systemctl daemon-reload
$ systemctl show -p TasksCurrent sshd
TasksCurrent=18446744073709551615
This was also visible with the "status" command: "Tasks: " row wasn't
showed in status of a service after a "daemon-reload" command.
Unit.JobTimeoutSec starts when a job is enqueued in a transaction. The
introduced distinct Unit.JobRunningTimeoutSec starts only when the job starts
running (e.g. it groups all Exec* commands of a service or spans waiting for a
device period.)
Unit.JobRunningTimeoutSec is intended to be used by default instead of
Unit.JobTimeoutSec for device units where such behavior causes less confusion
(consider a job for a _netdev mount device, with this change the timeout will
start ticking only after the network is ready).
log_struct takes multiple format strings, each one followed by arguments.
The _printf_ annotation is not sufficiently flexible to express this,
but we can still annotate the first format string, though not its
arguments (because their number is unknown).
With the annotation, the places which specified the message id or similar
as the first pattern cause a warning from -Wformat-nonliteral. This can
be trivially fixed by putting the MESSAGE= first.
This change will help find issues where a non-literal is erroneously used
as the pattern.
If the unit's SourcePath is below /proc then it's a unit genreated from
a kernel resource (such as a .mount or .swap unit). And those we watch
anyway, and hence should never be out-of-date.
Fixes: #5461
If a client pins a unit, then it makes sense to also implicitly make it
a subscriber. This is useful for clients that just want to watch one
specific unit: they can pin it and receive its messages.
We use our cgroup APIs in various contexts, including from our libraries
sd-login, sd-bus. As we don#t control those environments we can't rely
that the unified cgroup setup logic succeeds, and hence really shouldn't
assert on it.
This more or less reverts 415fc41cea.
cg_[all_]unified() test whether a specific controller or all controllers are on
the unified hierarchy. While what's being asked is a simple binary question,
the callers must assume that the functions may fail any time, which
unnecessarily complicates their usages. This complication is unnecessary.
Internally, the test result is cached anyway and there are only a few places
where the test actually needs to be performed.
This patch simplifies cg_[all_]unified().
* cg_[all_]unified() are updated to return bool. If the result can't be
decided, assertion failure is triggered. Error handlings from their callers
are dropped.
* cg_unified_flush() is updated to calculate the new result synchrnously and
return whether it succeeded or not. Places which need to flush the test
result are updated to test for failure. This ensures that all the following
cg_[all_]unified() tests succeed.
* Places which expected possible cg_[all_]unified() failures are updated to
call and test cg_unified_flush() before calling cg_[all_]unified(). This
includes functions used while setting up mounts during boot and
manager_setup_cgroup().
Embedding sd_id128_t's in constant strings was rather cumbersome. We had
SD_ID128_CONST_STR which returned a const char[], but it had two problems:
- it wasn't possible to statically concatanate this array with a normal string
- gcc wasn't really able to optimize this, and generated code to perform the
"conversion" at runtime.
Because of this, even our own code in coredumpctl wasn't using
SD_ID128_CONST_STR.
Add a new macro to generate a constant string: SD_ID128_MAKE_STR.
It is not as elegant as SD_ID128_CONST_STR, because it requires a repetition
of the numbers, but in practice it is more convenient to use, and allows gcc
to generate smarter code:
$ size .libs/systemd{,-logind,-journald}{.old,}
text data bss dec hex filename
1265204 149564 4808 1419576 15a938 .libs/systemd.old
1260268 149564 4808 1414640 1595f0 .libs/systemd
246805 13852 209 260866 3fb02 .libs/systemd-logind.old
240973 13852 209 255034 3e43a .libs/systemd-logind
146839 4984 34 151857 25131 .libs/systemd-journald.old
146391 4984 34 151409 24f71 .libs/systemd-journald
It is also much easier to check if a certain binary uses a certain MESSAGE_ID:
$ strings .libs/systemd.old|grep MESSAGE_ID
MESSAGE_ID=%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x
MESSAGE_ID=%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x
MESSAGE_ID=%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x
MESSAGE_ID=%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x
$ strings .libs/systemd|grep MESSAGE_ID
MESSAGE_ID=c7a787079b354eaaa9e77b371893cd27
MESSAGE_ID=b07a249cd024414a82dd00cd181378ff
MESSAGE_ID=641257651c1b4ec9a8624d7a40a9e1e7
MESSAGE_ID=de5b426a63be47a7b6ac3eaac82e2f6f
MESSAGE_ID=d34d037fff1847e6ae669a370e694725
MESSAGE_ID=7d4958e842da4a758f6c1cdc7b36dcc5
MESSAGE_ID=1dee0369c7fc4736b7099b38ecb46ee7
MESSAGE_ID=39f53479d3a045ac8e11786248231fbf
MESSAGE_ID=be02cf6855d2428ba40df7e9d022f03d
MESSAGE_ID=7b05ebc668384222baa8881179cfda54
MESSAGE_ID=9d1aaa27d60140bd96365438aad20286
Let's make sure we verify that all BindsTo= are in order before we actually go
and dispatch a start operation to a unit. Normally the job queue should already
have made sure all deps are in order, but this might not have been sufficient
in two cases: a) when the user changes deps during runtime and reloads the
daemon, and b) when the user placed BindsTo= dependencies without matching
After= dependencies, so that we don't actually wait for the bound to unit to be
up before upping also the binding unit.
See: #4725
This is similar to RootDirectory= but mounts the root file system from a
block device or loopback file instead of another directory.
This reuses the image dissector code now used by nspawn and
gpt-auto-discovery.
When an alias is loaded, we resolve this alias to its final unit first to load
the dropin data.
However if the final unit was already loaded, there's no point in reloading the
dropin data a second time.
This patch optimizes this case.
Also this allows the dropin loading code to assume that only units not yet
loaded are passed down. This assumption is not yet used but might be in the
future.
[zj: invert the condition in the if]
Since commit 9d06297, mount units from mountinfo are not bound to their devices
anymore (they use the "Requires" dependency instead).
This has the following drawback: if a media is mounted and the eject button is
pressed then the media is unconditionally ejected leaving some inconsistent
states.
Since udev is the component that is reacting (no matter if the device is used
or not) to the eject button, users expect that udev at least try to unmount the
media properly.
This patch introduces a new property "SYSTEMD_MOUNT_DEVICE_BOUND". When set on
a block device, all units that requires this device will see their "Requires"
dependency upgraded to a "BindTo" one. This is currently only used by cdrom
devices.
This patch also gives the possibility to the user to restore the previous
behavior that is bind a mount unit to a device. This is achieved by passing the
"x-systemd.device-bound" option to mount(8). Please note that currently this is
not working because libmount treats the x-* options has comments therefore
they're not available in utab for later application retrievals.
We generally try to make our destructors robust regarding NULL pointers, much
in the same way as glibc's free(). Do this also for unit_free().
Follow-up for #4748.
For some reasons units remaining in the same process group as PID 1
(same_pgrp=true) fail to acquire the console even if it's not taken by anyone.
So always accept for units with same_pgrp set for now.
In contrast to all other unit types device units when queued just track
external state, they cannot effect state changes on their own. Hence unless a
client or other job waits for them there's no reason to keep them in the job
queue. This adds a concept of GC'ing jobs of this type as soon as no client or
other job waits for them anymore.
To ensure this works correctly we need to track which clients actually
reference a job (i.e. which ones enqueued it). Unfortunately that's pretty
nasty to do for direct connections, as sd_bus_track doesn't work for
them. For now, work around this, by simply remembering in a boolean that a job
was requested by a direct connection, and reset it when we notice the direct
connection is gone. This means the GC logic works fine, except that jobs are
not immediately removed when direct connections disconnect.
In the longer term, a rework of the bus logic should fix this properly. For now
this should be good enough, as GC works for fine all cases except this one, and
thus is a clear improvement over the previous behaviour.
Fixes: #1921
The no_new_privileged_set variable is not used any more since commit
9b232d3241 that fixed another thing. So remove it. Also no
need to check if we are under user manager, remove that part too.
We don't have plural in the name of any other -util files and this
inconsistency trips me up every time I try to type this file name
from memory. "formats-util" is even hard to pronounce.
This reverts some changes introduced in d054f0a4d4.
xsprintf should be used in cases where we calculated the right buffer
size by hand (using DECIMAL_STRING_MAX and such), and never in cases where
we are printing externally specified strings of arbitrary length.
Fixes#4534.
So far "no_gc" was set on -.slice and init.scope, to units that are always
running, cannot be stopped and never exist in an "inactive" state. Since these
units are the only users of this flag, let's remodel it and rename it
"perpetual" and let's derive more funcitonality off it. Specifically, refuse
enqueing stop jobs for these units, and report that they are "unstoppable" in
the CanStop bus property.
We would close all the stored fds in service_release_resources(), which of
course broke the whole concept of storing fds over service restart.
Fixes#4408.
This commit adds a `fd` option to `StandardInput=`,
`StandardOutput=` and `StandardError=` properties in order to
connect standard streams to externally named descriptors provided
by some socket units.
This option looks for a file descriptor named as the corresponding
stream. Custom names can be specified, separated by a colon.
If multiple name-matches exist, the first matching fd will be used.
It is allowed for unit files to have an mtime==0, so instead of assuming that
any file that had mtime==0 was masked, use the load_state to filter masked
units.
Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1384150.
This is useful to turn off explicit module load and unload operations on modular
kernels. This option removes CAP_SYS_MODULE from the capability bounding set for
the unit, and installs a system call filter to block module system calls.
This option will not prevent the kernel from loading modules using the module
auto-load feature which is a system wide operation.
This adds a new invocation ID concept to the service manager. The invocation ID
identifies each runtime cycle of a unit uniquely. A new randomized 128bit ID is
generated each time a unit moves from and inactive to an activating or active
state.
The primary usecase for this concept is to connect the runtime data PID 1
maintains about a service with the offline data the journal stores about it.
Previously we'd use the unit name plus start/stop times, which however is
highly racy since the journal will generally process log data after the service
already ended.
The "invocation ID" kinda matches the "boot ID" concept of the Linux kernel,
except that it applies to an individual unit instead of the whole system.
The invocation ID is passed to the activated processes as environment variable.
It is additionally stored as extended attribute on the cgroup of the unit. The
latter is used by journald to automatically retrieve it for each log logged
message and attach it to the log entry. The environment variable is very easily
accessible, even for unprivileged services. OTOH the extended attribute is only
accessible to privileged processes (this is because cgroupfs only supports the
"trusted." xattr namespace, not "user."). The environment variable may be
altered by services, the extended attribute may not be, hence is the better
choice for the journal.
Note that reading the invocation ID off the extended attribute from journald is
racy, similar to the way reading the unit name for a logging process is.
This patch adds APIs to read the invocation ID to sd-id128:
sd_id128_get_invocation() may be used in a similar fashion to
sd_id128_get_boot().
PID1's own logging is updated to always include the invocation ID when it logs
information about a unit.
A new bus call GetUnitByInvocationID() is added that allows retrieving a bus
path to a unit by its invocation ID. The bus path is built using the invocation
ID, thus providing a path for referring to a unit that is valid only for the
current runtime cycleof it.
Outlook for the future: should the kernel eventually allow passing of cgroup
information along AF_UNIX/SOCK_DGRAM messages via a unique cgroup id, then we
can alter the invocation ID to be generated as hash from that rather than
entirely randomly. This way we can derive the invocation race-freely from the
messages.
Let's make sure that services that use DynamicUser=1 cannot leave files in the
file system should the system accidentally have a world-writable directory
somewhere.
This effectively ensures that directories need to be whitelisted rather than
blacklisted for access when DynamicUser=1 is set.
It is useful for clients to be able to read the last CPU usage counter value of
a unit even if the unit is already terminated. Hence, before destroying a
cgroup's cgroup cache the last CPU usage counter and return it if the cgroup is
gone.
This adds two (privileged) bus calls Ref() and Unref() to the Unit interface.
The two calls may be used by clients to pin a unit into memory, so that various
runtime properties aren't flushed out by the automatic GC. This is necessary
to permit clients to race-freely acquire runtime results (such as process exit
status/code or accumulated CPU time) on successful service termination.
Ref() and Unref() are fully recursive, hence act like the usual reference
counting concept in C. Taking a reference is a privileged operation, as this
allows pinning units into memory which consumes resources.
Transient units may also gain a reference at the time of creation, via the new
AddRef property (that is only defined for transient units at the time of
creation).
This adds the boolean RemoveIPC= setting to service, socket, mount and swap
units (i.e. all unit types that may invoke processes). if turned on, and the
unit's user/group is not root, all IPC objects of the user/group are removed
when the service is shut down. The life-cycle of the IPC objects is hence bound
to the unit life-cycle.
This is particularly relevant for units with dynamic users, as it is essential
that no objects owned by the dynamic users survive the service exiting. In
fact, this patch adds code to imply RemoveIPC= if DynamicUser= is set.
In order to communicate the UID/GID of an executed process back to PID 1 this
adds a new "user lookup" socket pair, that is inherited into the forked
processes, and closed before the exec(). This is needed since we cannot do NSS
from PID 1 due to deadlock risks, However need to know the used UID/GID in
order to clean up IPC owned by it if the unit shuts down.
Currently, systemd uses either the legacy hierarchies or the unified hierarchy.
When the legacy hierarchies are used, systemd uses a named legacy hierarchy
mounted on /sys/fs/cgroup/systemd without any kernel controllers for process
management. Due to the shortcomings in the legacy hierarchy, this involves a
lot of workarounds and complexities.
Because the unified hierarchy can be mounted and used in parallel to legacy
hierarchies, there's no reason for systemd to use a legacy hierarchy for
management even if the kernel resource controllers need to be mounted on legacy
hierarchies. It can simply mount the unified hierarchy under
/sys/fs/cgroup/systemd and use it without affecting other legacy hierarchies.
This disables a significant amount of fragile workaround logics and would allow
using features which depend on the unified hierarchy membership such bpf cgroup
v2 membership test. In time, this would also allow deleting the said
complexities.
This patch updates systemd so that it prefers the unified hierarchy for the
systemd cgroup controller hierarchy when legacy hierarchies are used for kernel
resource controllers.
* cg_unified(@controller) is introduced which tests whether the specific
controller in on unified hierarchy and used to choose the unified hierarchy
code path for process and service management when available. Kernel
controller specific operations remain gated by cg_all_unified().
* "systemd.legacy_systemd_cgroup_controller" kernel argument can be used to
force the use of legacy hierarchy for systemd cgroup controller.
* nspawn: By default nspawn uses the same hierarchies as the host. If
UNIFIED_CGROUP_HIERARCHY is set to 1, unified hierarchy is used for all. If
0, legacy for all.
* nspawn: arg_unified_cgroup_hierarchy is made an enum and now encodes one of
three options - legacy, only systemd controller on unified, and unified. The
value is passed into mount setup functions and controls cgroup configuration.
* nspawn: Interpretation of SYSTEMD_CGROUP_CONTROLLER to the actual mount
option is moved to mount_legacy_cgroup_hierarchy() so that it can take an
appropriate action depending on the configuration of the host.
v2: - CGroupUnified enum replaces open coded integer values to indicate the
cgroup operation mode.
- Various style updates.
v3: Fixed a bug in detect_unified_cgroup_hierarchy() introduced during v2.
v4: Restored legacy container on unified host support and fixed another bug in
detect_unified_cgroup_hierarchy().
A following patch will update cgroup handling so that the systemd controller
(/sys/fs/cgroup/systemd) can use the unified hierarchy even if the kernel
resource controllers are on the legacy hierarchies. This would require
distinguishing whether all controllers are on cgroup v2 or only the systemd
controller is. In preparation, this patch renames cg_unified() to
cg_all_unified().
This patch doesn't cause any functional changes.
Unfortunately, due to the disagreements in the kernel development community,
CPU controller cgroup v2 support has not been merged and enabling it requires
applying two small out-of-tree kernel patches. The situation is explained in
the following documentation.
https://git.kernel.org/cgit/linux/kernel/git/tj/cgroup.git/tree/Documentation/cgroup-v2-cpu.txt?h=cgroup-v2-cpu
While it isn't clear what will happen with CPU controller cgroup v2 support,
there are critical features which are possible only on cgroup v2 such as
buffered write control making cgroup v2 essential for a lot of workloads. This
commit implements systemd CPU controller support on the unified hierarchy so
that users who choose to deploy CPU controller cgroup v2 support can easily
take advantage of it.
On the unified hierarchy, "cpu.weight" knob replaces "cpu.shares" and "cpu.max"
replaces "cpu.cfs_period_us" and "cpu.cfs_quota_us". [Startup]CPUWeight config
options are added with the usual compat translation. CPU quota settings remain
unchanged and apply to both legacy and unified hierarchies.
v2: - Error in man page corrected.
- CPU config application in cgroup_context_apply() refactored.
- CPU accounting now works on unified hierarchy.
This adds a new boolean setting DynamicUser= to service files. If set, a new
user will be allocated dynamically when the unit is started, and released when
it is stopped. The user ID is allocated from the range 61184..65519. The user
will not be added to /etc/passwd (but an NSS module to be added later should
make it show up in getent passwd).
For now, care should be taken that the service writes no files to disk, since
this might result in files owned by UIDs that might get assigned dynamically to
a different service later on. Later patches will tighten sandboxing in order to
ensure that this cannot happen, except for a few selected directories.
A simple way to test this is:
systemd-run -p DynamicUser=1 /bin/sleep 99999
Let's lot at LOG_NOTICE about any processes that we are going to
SIGKILL/SIGABRT because clean termination of them didn't work.
This turns the various boolean flag parameters to cg_kill(), cg_migrate() and
related calls into a single binary flags parameter, simply because the function
now gained even more parameters and the parameter listed shouldn't get too
long.
Logging for killing processes is done either when the kill signal is SIGABRT or
SIGKILL, or on explicit request if KILL_TERMINATE_AND_LOG instead of LOG_TERMINATE
is passed. This isn't used yet in this patch, but is made use of in a later
patch.
The unit load queue can be processed in the middle of setting the
unit's properties, so its load_state would no longer be UNIT_STUB
for the check in bus_unit_set_properties(), which would cause it to
incorrectly return an error.
By default, each iteration of manager_dispatch_sigchld() results in a unit level
sigchld event being invoked. For scope units, this results in a scope_sigchld_event()
which can seemingly stall for workloads that have a large number of PIDs within the
scope. The stall exhibits itself as a SIG_0 being initiated for each u->pids entry
as a result of pid_is_unwaited().
v2:
This patch resolves this condition by only paying to cost of a sigchld in the underlying
scope unit once per sigchld iteration. A new "sigchldgen" member resides within the
Unit struct. The Manager is incremented via the sd event loop, accessed via
sd_event_get_iteration, and the Unit member is set to the same value as the manager each
time that a sigchld event is invoked. If the Manager iteration value and Unit member
match, the sigchld event is not invoked for that iteration.
unit_write_drop_in{,_private}{,_format} are all affected.
We already append a header to the file (and section markers), so those functions
can only be used to write a whole file at once. Including the newline at
the end feels natural.
After this commit newlines will be duplicated. They will be removed in
subsequent commit.
Also, rewrap the "autogenerated" header to fit within 80 columns.
We currently generate log message about unit being started even when
unit was started already and job didn't do anything. This is because job
was requested explicitly and hence became anchor job of the transaction
thus we could not eliminate it. That is fine but, let's not pollute
journal with useless log messages.
$ systemctl start systemd-resolved
$ systemctl start systemd-resolved
$ systemctl start systemd-resolved
Current state:
$ journalctl -u systemd-resolved | grep Started
May 05 15:31:42 rawhide systemd[1]: Started Network Name Resolution.
May 05 15:31:59 rawhide systemd[1]: Started Network Name Resolution.
May 05 15:32:01 rawhide systemd[1]: Started Network Name Resolution.
After patch applied:
$ journalctl -u systemd-resolved | grep Started
May 05 16:42:12 rawhide systemd[1]: Started Network Name Resolution.
Fixes#1723
unit_set_slice() fails with -EBUSY if the unit already has a slice associated
with it. This makes it impossible to override slice through dropin config or
over dbus. There's no reason to disallow slice changes as long as cgroups
aren't realized. Fix it.
Fixes#3240.
Signed-off-by: Tejun Heo <htejun@fb.com>
Reported-by: Davide Cavalca <dcavalca@fb.com>
On the unified hierarchy, blkio controller is renamed to io and the interface
is changed significantly.
* blkio.weight and blkio.weight_device are consolidated into io.weight which
uses the standardized weight range [1, 10000] with 100 as the default value.
* blkio.throttle.{read|write}_{bps|iops}_device are consolidated into io.max.
Expansion of throttling features is being worked on to support
work-conserving absolute limits (io.low and io.high).
* All stats are consolidated into io.stats.
This patchset adds support for the new interface. As the interface has been
revamped and new features are expected to be added, it seems best to treat it
as a separate controller rather than trying to expand the blkio settings
although we might add automatic translation if only blkio settings are
specified.
* io.weight handling is mostly identical to blkio.weight[_device] handling
except that the weight range is different.
* Both read and write bandwidth settings are consolidated into
CGroupIODeviceLimit which describes all limits applicable to the device.
This makes it less painful to add new limits.
* "max" can be used to specify the maximum limit which is equivalent to no
config for max limits and treated as such. If a given CGroupIODeviceLimit
doesn't contain any non-default configs, the config struct is discarded once
the no limit config is applied to cgroup.
* lookup_blkio_device() is renamed to lookup_block_device().
Signed-off-by: Tejun Heo <htejun@fb.com>
