[systemd-devel] systemd 243 released
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Tue Sep 3 14:19:13 UTC 2019
🎆 A new, official systemd release has just 🎉 been 🎊 tagged 🍾. Please download the tarball here:
Changes since the previous release:
* This release enables unprivileged programs (i.e. requiring neither
setuid nor file capabilities) to send ICMP Echo (i.e. ping) requests
by turning on the "net.ipv4.ping_group_range" sysctl of the Linux
kernel for the whole UNIX group range, i.e. all processes. This
change should be reasonably safe, as the kernel support for it was
specifically implemented to allow safe access to ICMP Echo for
processes lacking any privileges. If this is not desirable, it can be
disabled again by setting the parameter to "1 0".
* Previously, filters defined with SystemCallFilter= would have the
effect that any calling of an offending system call would terminate
the calling thread. This behaviour never made much sense, since
killing individual threads of unsuspecting processes is likely to
create more problems than it solves. With this release the default
action changed from killing the thread to killing the whole
process. For this to work correctly both a kernel version (>= 4.14)
and a libseccomp version (>= 2.4.0) supporting this new seccomp
action is required. If an older kernel or libseccomp is used the old
behaviour continues to be used. This change does not affect any
services that have no system call filters defined, or that use
SystemCallErrorNumber= (and thus see EPERM or another error instead
of being killed when calling an offending system call). Note that
systemd documentation always claimed that the whole process is
killed. With this change behaviour is thus adjusted to match the
* On 64 bit systems, the "kernel.pid_max" sysctl is now bumped to
4194304 by default, i.e. the full 22bit range the kernel allows, up
from the old 16bit range. This should improve security and
robustness, as PID collisions are made less likely (though certainly
still possible). There are rumours this might create compatibility
problems, though at this moment no practical ones are known to
us. Downstream distributions are hence advised to undo this change in
their builds if they are concerned about maximum compatibility, but
for everybody else we recommend leaving the value bumped. Besides
improving security and robustness this should also simplify things as
the maximum number of allowed concurrent tasks was previously bounded
by both "kernel.pid_max" and "kernel.threads-max" and now effectively
only a single knob is left ("kernel.threads-max"). There have been
concerns that usability is affected by this change because larger PID
numbers are harder to type, but we believe the change from 5 digits
to 7 digits doesn't hamper usability.
* MemoryLow= and MemoryMin= gained hierarchy-aware counterparts,
DefaultMemoryLow= and DefaultMemoryMin=, which can be used to
hierarchically set default memory protection values for a particular
subtree of the unit hierarchy.
* Memory protection directives can now take a value of zero, allowing
explicit opting out of a default value propagated by an ancestor.
* systemd now defaults to the "unified" cgroup hierarchy setup during
build-time, i.e. -Ddefault-hierarchy=unified is now the build-time
default. Previously, -Ddefault-hierarchy=hybrid was the default. This
change reflects the fact that cgroupsv2 support has matured
substantially in both systemd and in the kernel, and is clearly the
way forward. Downstream production distributions might want to
continue to use -Ddefault-hierarchy=hybrid (or even =legacy) for
their builds as unfortunately the popular container managers have not
caught up with the kernel API changes.
* Man pages are not built by default anymore (html pages were already
disabled by default), to make development builds quicker. When
building systemd for a full installation with documentation, meson
should be called with -Dman=true and/or -Dhtml=true as appropriate.
The default was changed based on the assumption that quick one-off or
repeated development builds are much more common than full optimized
builds for installation, and people need to pass various other
options to when doing "proper" builds anyway, so the gain from making
development builds quicker is bigger than the one time disruption for
Two scripts are created in the *build* directory to generate and
preview man and html pages on demand, e.g.:
* libidn2 is used by default if both libidn2 and libidn are installed.
Please use -Dlibidn=true if libidn is preferred.
* The D-Bus "wire format" of the CPUAffinity= attribute is changed on
big-endian machines. Before, bytes were written and read in native
machine order as exposed by the native libc __cpu_mask interface.
Now, little-endian order is always used (CPUs 0–7 are described by
bits 0–7 in byte 0, CPUs 8–15 are described by byte 1, and so on).
This change fixes D-Bus calls that cross endianness boundary.
The presentation format used for CPUAffinity= by "systemctl show" and
"systemd-analyze dump" is changed to present CPU indices instead of
the raw __cpu_mask bitmask. For example, CPUAffinity=0-1 would be
shown as CPUAffinity=03000000000000000000000000000… (on
little-endian) or CPUAffinity=00000000000000300000000000000… (on
64-bit big-endian), and is now shown as CPUAffinity=0-1, matching the
input format. The maximum integer that will be printed in the new
format is 8191 (four digits), while the old format always used a very
long number (with the length varying by architecture), so they can be
* /usr/sbin/halt.local is no longer supported. Implementation in
distributions was inconsistent and it seems this functionality was
very rarely used.
To replace this functionality, users should:
- either define a new unit and make it a dependency of final.target
(systemctl add-wants final.target my-halt-local.service)
- or move the shutdown script to /usr/lib/systemd/system-shutdown/
and ensure that it accepts "halt", "poweroff", "reboot", and
"kexec" as an argument, see the description in systemd-shutdown(8).
* When a [Match] section in .link or .network file is empty (contains
no match patterns), a warning will be emitted. Please add any "match
all" pattern instead, e.g. OriginalName=* or Name=* in case all
interfaces should really be matched.
* A new setting NUMAPolicy= may be used to set process memory
allocation policy. This setting can be specified in
/etc/systemd/system.conf and hence will set the default policy for
PID1. The default policy can be overridden on a per-service
basis. The related setting NUMAMask= is used to specify NUMA node
mask that should be associated with the selected policy.
* PID 1 will now listen to Out-Of-Memory (OOM) events the kernel
generates when processes it manages are reaching their memory limits,
and will place their units in a special state, and optionally kill or
stop the whole unit.
* The service manager will now expose bus properties for the IO
resources used by units. This information is also shown in "systemctl
status" now (for services that have IOAccounting=yes set). Moreover,
the IO accounting data is included in the resource log message
generated whenever a unit stops.
* Units may now configure an explicit time-out to wait for when killed
with SIGABRT, for example when a service watchdog is hit. Previously,
the regular TimeoutStopSec= time-out was applied in this case too —
now a separate time-out may be set using TimeoutAbortSec=.
* Services may now send a special WATCHDOG=trigger message with
sd_notify() to trigger an immediate "watchdog missed" event, and thus
trigger service termination. This is useful both for testing watchdog
handling, but also for defining error paths in services, that shall
be handled the same way as watchdog events.
* There are two new per-unit settings IPIngressFilterPath= and
IPEgressFilterPath= which allow configuration of a BPF program
(usually by specifying a path to a program uploaded to /sys/fs/bpf/)
to apply to the IP packet ingress/egress path of all processes of a
unit. This is useful to allow running systemd services with BPF
programs set up externally.
* systemctl gained a new "clean" verb for removing the state, cache,
runtime or logs directories of a service while it is terminated. The
new verb may also be used to remove the state maintained on disk for
timer units that have Persistent= configured.
* During the last phase of shutdown systemd will now automatically
increase the log level configured in the "kernel.printk" sysctl so
that any relevant loggable events happening during late shutdown are
made visible. Previously, loggable events happening so late during
shutdown were generally lost if the "kernel.printk" sysctl was set to
high thresholds, as regular logging daemons are terminated at that
time and thus nothing is written to disk.
* If processes terminated during the last phase of shutdown do not exit
quickly systemd will now show their names after a short time, to make
debugging easier. After a longer time-out they are forcibly killed,
* journalctl (and the other tools that display logs) will now highlight
warnings in yellow (previously, both LOG_NOTICE and LOG_WARNING where
shown in bright bold, now only LOG_NOTICE is). Moreover, audit logs
are now shown in blue color, to separate them visually from regular
logs. References to configuration files are now turned into clickable
links on terminals that support that.
* systemd-journald will now stop logging to /var/log/journal during
shutdown when /var/ is on a separate mount, so that it can be
unmounted safely during shutdown.
* systemd-resolved gained support for a new 'strict' DNS-over-TLS mode.
* systemd-resolved "Cache=" configuration option in resolved.conf has
been extended to also accept the 'no-negative' value. Previously,
only a boolean option was allowed (yes/no), having yes as the
default. If this option is set to 'no-negative', negative answers are
not cached while the old cache heuristics are used positive answers.
The default remains unchanged.
* The predictable naming scheme for network devices now supports
generating predictable names for "netdevsim" devices.
Moreover, the "en" prefix was dropped from the ID_NET_NAME_ONBOARD
Those two changes form a new net.naming-policy-scheme= entry.
Distributions which want to preserve naming stability may want to set
the -Ddefault-net-naming-scheme= configuration option.
* systemd-networkd now supports MACsec, nlmon, IPVTAP and Xfrm
* systemd-networkd's bridge FDB support now allows configuration of a
destination address for each entry (Destination=), as well as the
VXLAN VNI (VNI=), as well as an option to declare what an entry is
associated with (AssociatedWith=).
* systemd-networkd's DHCPv4 support now understands a new MaxAttempts=
option for configuring the maximum number of DHCP lease requests. It
also learnt a new BlackList= option for blacklisting DHCP servers (a
similar setting has also been added to the IPv6 RA client), as well
as a SendRelease= option for configuring whether to send a DHCP
RELEASE message when terminating.
* systemd-networkd's DHCPv4 and DHCPv6 stacks can now be configured
separately in the [DHCPv4] and [DHCPv6] sections.
* systemd-networkd's DHCP support will now optionally create an
implicit host route to the DNS server specified in the DHCP lease, in
addition to the routes listed explicitly in the lease. This should
ensure that in multi-homed systems DNS traffic leaves the systems on
the interface that acquired the DNS server information even if other
routes such as default routes exist. This behaviour may be turned on
with the new RoutesToDNS= option.
* systemd-networkd's VXLAN support gained a new option
GenericProtocolExtension= for enabling VXLAN Generic Protocol
Extension support, as well as IPDoNotFragment= for setting the IP
"Don't fragment" bit on outgoing packets. A similar option has been
added to the GENEVE support.
* In systemd-networkd's [Route] section you may now configure
FastOpenNoCookie= for configuring per-route TCP fast-open support, as
well as TTLPropagate= for configuring Label Switched Path (LSP) TTL
propagation. The Type= setting now supports local, broadcast,
anycast, multicast, any, xresolve routes, too.
* systemd-networkd's [Network] section learnt a new option
DefaultRouteOnDevice= for automatically configuring a default route
onto the network device.
* systemd-networkd's bridging support gained two new options ProxyARP=
and ProxyARPWifi= for configuring proxy ARP behaviour as well as
MulticastRouter= for configuring multicast routing behaviour. A new
option MulticastIGMPVersion= may be used to change bridge's multicast
Internet Group Management Protocol (IGMP) version.
* systemd-networkd's FooOverUDP support gained the ability to configure
local and peer IP addresses via Local= and Peer=. A new option
PeerPort= may be used to configure the peer's IP port.
* systemd-networkd's TUN support gained a new setting VnetHeader= for
tweaking Generic Segment Offload support.
* networkctl gained a new "delete" command for removing virtual network
devices, as well as a new "--stats" switch for showing device
* networkd.conf gained a new setting SpeedMeter= and
SpeedMeterIntervalSec=, to measure bitrate of network interfaces. The
measured speed may be shown by 'networkctl status'.
* "networkctl status" now displays MTU and queue lengths, and more
detailed information about VXLAN and bridge devices.
* systemd-networkd's .network and .link files gained a new Property=
setting in the [Match] section, to match against devices with
specific udev properties.
* systemd-networkd's tunnel support gained a new option
AssignToLoopback= for selecting whether to use the loopback device
"lo" as underlying device.
* systemd-networkd's MACAddress= setting in the [Neighbor] section has
been renamed to LinkLayerAddress=, and it now allows configuration of
IP addresses, too.
* systemd-networkd's handling of the kernel's disable_ipv6 sysctl is
simplified: systemd-networkd will disable the sysctl (enable IPv6) if
IPv6 configuration (static or DHCPv6) was found for a given
interface. It will not touch the sysctl otherwise.
* The order of entries is $PATH used by the user manager instance was
changed to put bin/ entries before the corresponding sbin/ entries.
It is recommended to not rely on this order, and only ever have one
binary with a given name in the system paths under /usr.
* A new tool systemd-network-generator has been added that may generate
.network, .netdev and .link files from IP configuration specified on
the kernel command line in the format used by Dracut.
* The CriticalConnection= setting in .network files is now deprecated,
and replaced by a new KeepConfiguration= setting which allows more
detailed configuration of the IP configuration to keep in place.
* systemd-analyze gained a few new verbs:
- "systemd-analyze timestamp" parses and converts timestamps. This is
similar to the existing "systemd-analyze calendar" command which
does the same for recurring calendar events.
- "systemd-analyze timespan" parses and converts timespans (i.e.
durations as opposed to points in time).
- "systemd-analyze condition" will parse and test ConditionXYZ=
- "systemd-analyze exit-status" will parse and convert exit status
codes to their names and back.
- "systemd-analyze unit-files" will print a list of all unit
file paths and unit aliases.
* SuccessExitStatus=, RestartPreventExitStatus=, and
RestartForceExitStatus= now accept exit status names (e.g. "DATAERR"
is equivalent to "65"). Those exit status name mappings may be
displayed with the sytemd-analyze exit-status verb describe above.
* systemd-logind now exposes a per-session SetBrightness() bus call,
which may be used to securely change the brightness of a kernel
brightness device, if it belongs to the session's seat. By using this
call unprivileged clients can make changes to "backlight" and "leds"
devices securely with strict requirements on session membership.
Desktop environments may use this to generically make brightness
changes to such devices without shipping private SUID binaries or
udev rules for that purpose.
* "udevadm info" gained a --wait-for-initialization switch to wait for
a device to be initialized.
* systemd-hibernate-resume-generator will now look for resumeflags= on
the kernel command line, which is similar to rootflags= and may be
used to configure device timeout for the hibernation device.
* sd-event learnt a new API call sd_event_source_disable_unref() for
disabling and unref'ing an event source in a single function. A
related call sd_event_source_disable_unrefp() has been added for use
with gcc's cleanup extension.
* The sd-id128.h public API gained a new definition
SD_ID128_UUID_FORMAT_STR for formatting a 128bit ID in UUID format
* "busctl introspect" gained a new switch --xml-interface for dumping
XML introspection data unmodified.
* PID 1 may now show the unit name instead of the unit description
string in its status output during boot. This may be configured in
the StatusUnitFormat= setting in /etc/systemd/system.conf or the
kernel command line option systemd.status_unit_format=.
* PID 1 now understands a new option KExecWatchdogSec= in
/etc/systemd/system.conf to set a watchdog timeout for kexec reboots.
Previously watchdog functionality was only available for regular
reboots. The new setting defaults to off, because we don't know in
the general case if the watchdog will be reset after kexec (some
drivers do reset it, but not all), and the new userspace might not be
configured to handle the watchdog.
Moreover, the old ShutdownWatchdogSec= setting has been renamed to
RebootWatchdogSec= to more clearly communicate what it is about. The
old name is still accepted for compatibility.
* The systemd.debug_shell kernel command line option now optionally
takes a tty name to spawn the debug shell on, which allows a
different tty to be selected than the built-in default.
* Service units gained a new ExecCondition= setting which will run
before ExecStartPre= and either continue execution of the unit (for
clean exit codes), stop execution without marking the unit failed
(for exit codes 1 through 254), or stop execution and fail the unit
(for exit code 255 or abnormal termination).
* A new service systemd-pstore.service has been added that pulls data
from /sys/fs/pstore/ and saves it to /var/lib/pstore for later
* timedatectl gained new verbs for configuring per-interface NTP
service configuration for systemd-timesyncd.
* "localectl list-locales" won't list non-UTF-8 locales anymore. It's
2019. (You can set non-UTF-8 locales though, if you know their name.)
* If variable assignments in sysctl.d/ files are prefixed with "-" any
failures to apply them are now ignored.
* systemd-random-seed.service now optionally credits entropy when
applying the seed to the system. Set $SYSTEMD_RANDOM_SEED_CREDIT to
true for the service to enable this behaviour, but please consult the
documentation first, since this comes with a couple of caveats.
* systemd-random-seed.service is now a synchronization point for full
initialization of the kernel's entropy pool. Services that require
/dev/urandom to be correctly initialized should be ordered after this
* The systemd-boot boot loader has been updated to optionally maintain
a random seed file in the EFI System Partition (ESP). During the boot
phase, this random seed is read and updated with a new seed
cryptographically derived from it. Another derived seed is passed to
the OS. The latter seed is then credited to the kernel's entropy pool
very early during userspace initialization (from PID 1). This allows
systems to boot up with a fully initialized kernel entropy pool from
earliest boot on, and thus entirely removes all entropy pool
initialization delays from systems using systemd-boot. Special care
is taken to ensure different seeds are derived on system images
replicated to multiple systems. "bootctl status" will show whether
a seed was received from the boot loader.
* bootctl gained two new verbs:
- "bootctl random-seed" will generate the file in ESP and an EFI
variable to allow a random seed to be passed to the OS as described
- "bootctl is-installed" checks whether systemd-boot is currently
* bootctl will warn if it detects that boot entries are misconfigured
(for example if the kernel image was removed without purging the
* A new document has been added describing systemd's use and support
for the kernel's entropy pool subsystem:
* When the system is hibernated the swap device to write the
hibernation image to is now automatically picked from all available
swap devices, preferring the swap device with the highest configured
priority over all others, and picking the device with the most free
space if there are multiple devices with the highest priority.
* /etc/crypttab support has learnt a new keyfile-timeout= per-device
option that permits selecting the timout how long to wait for a
device with an encryption key before asking for the password.
* IOWeight= has learnt to properly set the IO weight when using the
BFQ scheduler officially found in kernels 5.0+.
* A new mailing list has been created for reporting of security issues:
systemd-security at redhat.com. For mode details, see
Contributions from: Aaron Barany, Adrian Bunk, Alan Jenkins, Albrecht
Lohofener, Andrej Valek, Anita Zhang, Arian van Putten, Balint Reczey,
Bastien Nocera, Ben Boeckel, Benjamin Robin, camoz, Chen Qi, Chris
Chiu, Chris Down, Christian Kellner, Clinton Roy, Connor Reeder, Daniel
Black, Daniele Medri, Dan Streetman, Dave Reisner, Dave Ross, David
Art, David Tardon, Debarshi Ray, Dimitri John Ledkov, Dominick Grift,
Donald Buczek, Douglas Christman, Eric DeVolder, EtherGraf, Evgeny
Vereshchagin, Feldwor, Felix Riemann, Florian Dollinger, Francesco
Pennica, Franck Bui, Frantisek Sumsal, Franz Pletz, frederik, Hans
de Goede, Iago López Galeiras, Insun Pyo, Ivan Shapovalov, Iwan Timmer,
Jack, Jakob Unterwurzacher, Jan Chren, Jan Klötzke, Jan Losinski, Jan
Pokorný, Jan Synacek, Jan-Michael Brummer, Jeka Pats, Jeremy Soller,
Jérémy Rosen, Jiri Pirko, Joe Lin, Joerg Behrmann, Joe Richey, Jóhann
B. Guðmundsson, Johannes Christ, Johannes Schmitz, Jonathan Rouleau,
Jorge Niedbalski, Kai Krakow, Kai Lüke, Karel Zak, Kashyap Chamarthy,
Krayushkin Konstantin, Lennart Poettering, Lubomir Rintel, Luca
Boccassi, Luís Ferreira, Marc-André Lureau, Markus Felten, Martin Pitt,
Matthew Leeds, Mattias Jernberg, Michael Biebl, Michael Olbrich,
Michael Prokop, Michael Stapelberg, Michael Zhivich, Michal Koutný,
Michal Sekletar, Mike Gilbert, Milan Broz, Miroslav Lichvar, mpe85,
Mr-Foo, Network Silence, Oliver Harley, pan93412, Paul Menzel, pEJipE,
Peter A. Bigot, Philip Withnall, Piotr Drąg, Rafael Fontenelle, Roberto
Santalla, Ronan Pigott, root, RussianNeuroMancer, Sebastian Jennen,
shinygold, Shreyas Behera, Simon Schricker, Susant Sahani, Thadeu Lima
de Souza Cascardo, Theo Ouzhinski, Thiebaud Weksteen, Thomas Haller,
Thomas Weißschuh, Tomas Mraz, Tommi Rantala, Topi Miettinen, VD-Lycos,
ven, Wieland Hoffmann, William A. Kennington III, William Wold, Xi
Ruoyao, Yuri Chornoivan, Yu Watanabe, Your Name, Zach Smith, Zbigniew
Jędrzejewski-Szmek, Zhang Xianwei
– Camerino, 2019-09-03
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