Add After=systemd-networkd.socket to avoid a race condition and networkd
falling back to the non-socket activation code.
Also add Wants=systemd-networkd.socket, so the socket is started when
networkd is started via `systemctl start systemd-networkd.service`.
A Requires is not strictly necessary, as networkd still ships the
non-socket activation code. Should this code be removed one day, the
Wants should be bumped to Requires accordingly.
See also 5544ee8516.
Fixes: #16809
Add `ProtectClock=yes` to systemd units. Since it implies certain
`DeviceAllow=` rules, make sure that the units have `DeviceAllow=` rules so
they are still able to access other devices. Exclude timesyncd and timedated.
We set ProtectKernelLogs=yes on all long running services except for
udevd, since it accesses /dev/kmsg, and journald, since it calls syslog
and accesses /dev/kmsg.
As discussed on systemd-devel [1], in Fedora we get lots of abrt reports
about the watchdog firing [2], but 100% of them seem to be caused by resource
starvation in the machine, and never actual deadlocks in the services being
monitored. Killing the services not only does not improve anything, but it
makes the resource starvation worse, because the service needs cycles to restart,
and coredump processing is also fairly expensive. This adds a configuration option
to allow the value to be changed. If the setting is not set, there is no change.
My plan is to set it to some ridiculusly high value, maybe 1h, to catch cases
where a service is actually hanging.
[1] https://lists.freedesktop.org/archives/systemd-devel/2019-October/043618.html
[2] https://bugzilla.redhat.com/show_bug.cgi?id=1300212
The code supports SIGTERM and SIGINT to termiante the process. It would
be possible to reporpose one of those signals for the restart operation,
but I think it's better to use a completely different signal to avoid
misunderstandings.
While the need for access to character devices can be tricky to determine for
the general case, it's obvious that most of our services have no need to access
block devices. For logind and timedated this can be tightened further.
ProtectHostname= turns off hostname change propagation from host to
service. This means for services that care about the hostname and need
to be able to notice changes to it it's not suitable (though it is
useful for most other cases still).
Let's turn it off hence for journald (which logs the current hostname)
for networkd (which optionally sends the current hostname to dhcp
servers) and resolved (which announces the current hostname via
llmnr/mdns).
Previously, setting this option by default was problematic due to
SELinux (as this would also prohibit the transition from PID1's label to
the service's label). However, this restriction has since been lifted,
hence let's start making use of this universally in our services.
On SELinux system this change should be synchronized with a policy
update that ensures that NNP-ful transitions from init_t to service
labels is permitted.
An while we are at it: sort the settings in the unit files this touches.
This might increase the size of the change in this case, but hopefully
should result in stabler patches later on.
Fixes: #1219
This reverts commit d4e9e574ea.
(systemd.conf.m4 part was already reverted in 5b5d82615011b9827466b7cd5756da35627a1608.)
Together those reverts should "fix" #10025 and #10011. ("fix" is in quotes
because this doesn't really fix the underlying issue, which is combining
DynamicUser= with strict container sandbox, but it avoids the problem by not
using that feature in our default installation.)
Dynamic users don't work well if the service requires matching configuration in
other places, for example dbus policy. This is true for those three services.
In effect, distros create the user statically [1, 2]. Dynamic users make more
sense for "add-on" services where not creating the user, or more precisely,
creating the user lazily, can save resources. For "basic" services, if we are
going to create the user on package installation anyway, setting DynamicUser=
just creates unneeded confusion. The only case where it is actually used is
when somebody forgets to do system configuration. But it's better to have the
service fail cleanly in this case too. If we want to turn on some side-effect
of DynamicUser=yes for those services, we should just do that directly through
fine-grained options. By not using DynamicUser= we also avoid the need to
restart dbus.
[1] bd9bf30727
[2] 48ac1cebde/f/systemd.spec (_473)
(Fedora does not create systemd-timesync user.)
This is generally the safer approach, and is what container managers
(including nspawn) do, hence let's move to this too for our own
services. This is particularly useful as this this means the new
@system-service system call filter group will get serious real-life
testing quickly.
This also switches from firing SIGSYS on unexpected syscalls to
returning EPERM. This would have probably been a better default anyway,
but it's hard to change that these days. When whitelisting system calls
SIGSYS is highly problematic as system calls that are newly introduced
to Linux become minefields for services otherwise.
Note that this enables a system call filter for udev for the first time,
and will block @clock, @mount and @swap from it. Some downstream
distributions might want to revert this locally if they want to permit
unsafe operations on udev rules, but in general this shiuld be mostly
safe, as we already set MountFlags=shared for udevd, hence at least
@mount won't change anything.
The daemon requires the busname unit to operate (on kdbus systems),
since it contains the policy that allows it to acquire its service
name.
This fixes https://bugs.freedesktop.org/show_bug.cgi?id=90287
We will be woken up on rtnl or dbus activity, so let's just quit if some time has passed and that is the only thing that can happen.
Note that we will always stay around if we expect network activity (e.g. DHCP is enabled), as we are not restarted on that.
This way we are sure that /dev/net/tun has been given the right permissions before we try to connect to it.
Ideally, we should create tun/tap devices over netlink, and then this whole issue would go away.
networkd-wait-online should never exist in the default transaction,
unless explicitly enable or pulled in via things like NFS. However, just
enabling networkd shouldn't enable networkd-wait-online, since it's
common to use the former without the latter.
network-pre.target is a passive target that should be pulled in by
services that want to be executed before any network is configured (for
example: firewall scrips).
network-pre.target should be ordered before all network managemet
services (but not be pulled in by them).
network-pre.target should be order after all services that want to be
executed before any network is configured (and be pulled in by them).
Also, rename ProtectedHome= to ProtectHome=, to simplify things a bit.
With this in place we now have two neat options ProtectSystem= and
ProtectHome= for protecting the OS itself (and optionally its
configuration), and for protecting the user's data.
ReadOnlySystem= uses fs namespaces to mount /usr and /boot read-only for
a service.
ProtectedHome= uses fs namespaces to mount /home and /run/user
inaccessible or read-only for a service.
This patch also enables these settings for all our long-running services.
Together they should be good building block for a minimal service
sandbox, removing the ability for services to modify the operating
system or access the user's private data.
Rely on modules being built-in or autoloaded on-demand.
As networkd is a network facing service, we want to limits its capabilities,
as much as possible. Also, we may not have CAP_SYS_MODULE in a container,
and we want networkd to work the same there.
Module autoloading does not always work, but should be fixed by the kernel
patch f98f89a0104454f35a: 'net: tunnels - enable module autoloading', which
is currently in net-next and which people may consider backporting if they
want tunneling support without compiling in the modules.
Early adopters may also use a module-load.d snippet and order
systemd-modules-load.service before networkd to force the module
loading of tunneling modules.
This sholud fix the various build issues people have reported.
This allows us to run networkd mostly unpriviliged with the exception of
CAP_NET_* and CAP_SYS_MODULE. I'd really like to get rid of the latter
though...
The ptrace capability was only necessary to detect virtualizations
environments. Since we changed the logic to determine this to not
require priviliges, there's no need to carry the CAP_SYS_PTRACE
capability anymore.
To make sure we don't delay boot on systems where (some) network links are managed by someone else
we don't block if something else has successfully brought up a link.
We will still block until all links we are aware of that are managed by networkd have been
configured, but if no such links exist, and someone else have configured a link sufficiently
that it has a carrier, it may be that the link is ready so we should no longer block.
Note that in all likelyhood the link is not ready (no addresses/routes configured),
so whatever network managment daemon configured it should provide a similar wait-online
service to block network-online.target until it is ready.
The aim is to block as long as we know networking is not fully configured, but no longer. This
will allow systemd-networkd-wait-online.service to be enabled on any system, even if we don't
know whether networkd is the main/only network manager.
Even in the case networking is fully configured by networkd, the default behavior may not be
sufficient: if two links need to be configured, but the first is fully configured before the
second one appears we will assume the network is up. To work around that, we allow specifying
specific devices to wait for before considering the network up.
This unit is enabled by default, just like systemd-networkd, but will only be pulled in if
anyone pulls in network-online.target.
We may not have a dbus daemon in the initrd (until we can rely on kdbus). In
this case, simply ignore any attempts at using the bus. There is only one user
for now, but surely more to come.
In order to work reliably in the real root without kdbus, but at the same time
don't delay boot when kdbus is in use, order ourselves after dbus.service.
This has the effect that systemd-networkd won't run in containers
without network namespacing wher CAP_NET_ADMIN is (usually) not
available. It will still run in containers with network namespacing on
(where CAP_NET_ADMIN is usually avilable).
We might remove this condition check again if networkd provides services
to apps that also are useful in containers lacking network namespacing,
however, as long as it doesn't it should be handled like udevd and be
excluded in such containers.
Adds a new call sd_event_set_watchdog() that can be used to hook up the
event loop with the watchdog supervision logic of systemd. If enabled
and $WATCHDOG_USEC is set the event loop will ping the invoking systemd
daemon right after coming back from epoll_wait() but not more often than
$WATCHDOG_USEC/4. The epoll_wait() will sleep no longer than
$WATCHDOG_USEC/4*3, to make sure the service manager is called in time.
This means that setting WatchdogSec= in a .service file and calling
sd_event_set_watchdog() in your daemon is enough to hook it up with the
watchdog logic.
Yu Watanabe