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NEWS
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systemd System and Service Manager
CHANGES WITH 252 in spe:
Announcements of Future Feature Removals:
* We intend to remove cgroup v1 support from systemd release after the
end of 2023. If you run services that make explicit use of cgroup v1
features (i.e. the "legacy hierarchy" with separate hierarchies for
each controller), please implement compatibility with cgroup v2 (i.e.
the "unified hierarchy") sooner rather than later. Most of Linux
userspace has been ported over already.
* We intend to remove support for split-usr (/usr mounted separately
during boot) and unmerged-usr (parallel directories /bin and
/usr/bin, /lib and /usr/lib, etc). This will happen in the second
half of 2023, in the first release that falls into that time window.
For more details, see:
https://lists.freedesktop.org/archives/systemd-devel/2022-September/048352.html
Compatibility Breaks:
* ConditionKernelVersion= checks that use the '=' or '!=' operators
will now do simple string comparisons (instead of version comparisons
á la stverscmp()). Version comparisons are still done for the
ordering operators '<', '>', '<=', '>='. Moreover, if no operator is
specified, a shell-style glob match is now done. This creates a minor
incompatibility compared to older systemd versions when the '*', '?',
'[', ']' characters are used, as these will now match as shell globs
instead of literally. Given that kernel version strings typically do
not include these characters we expect little breakage through this
change.
* The service manager will now read the SELinux label used for SELinux
access checks from the unit file at the time it loads the file.
Previously, the label would be read at the moment of the access
check, which was problematic since at that time the unit file might
already have been updated or removed.
New Features:
* systemd-measure is a new tool for calculating and signing expected
TPM2 PCR values for a given unified kernel image (UKI) booted via
sd-stub. The public key used for the signature and the signed
expected PCR information can be embedded inside the UKI. This
information can be extracted from the UKI by external tools and code
in the image itself and is made available to userspace in the booted
kernel.
systemd-cryptsetup, systemd-cryptenroll, and systemd-creds have been
updated to make use of this information if available in the booted
kernel: when locking an encrypted volume/credential to the TPM
systemd-cryptenroll/systemd-creds will use the public key to bind the
volume/credential to any kernel that carries PCR information signed
by the same key pair. When unlocking such volumes/credentials
systemd-cryptsetup/systemd-creds will use the signature embedded in
the booted UKI to gain access.
Binding TPM-based disk encryption to public keys/signatures of PCR
values — instead of literal PCR values — addresses the inherent
"brittleness" of traditional PCR-bound TPM disk encryption schemes:
disks remain accessible even if the UKI is updated, without any TPM
specific preparation during the OS update — as long as each UKI
carries the necessary PCR signature information.
Net effect: if you boot a properly prepared kernel, TPM-bound disk
encryption now defaults to be locked to kernels which carry PCR
signatures from the same key pair. Example: if a hypothetical distro
FooOS prepares its UKIs like this, TPM-based disk encryption is now –
by default – bound to only FooOS kernels, and encrypted volumes bound
to the TPM cannot be unlocked on kernels from other sources. (But do
note this behaviour requires preparation/enabling in the UKI, and of
course users can always enroll non-TPM ways to unlock the volume.)
* systemd-pcrphase is a new tool that is invoked at six places during
system runtime, and measures additional words into TPM2 PCR 11, to
mark milestones of the boot process. This allows binding access to
specific TPM2-encrypted secrets to specific phases of the boot
process. (Example: LUKS2 disk encryption key only accessible in the
initrd, but not later.)
Changes in systemd itself, i.e. the manager and units
* The cpu controller is delegated to user manager units by default, and
CPUWeight= settings are applied to the top-level user slice units
(app.slice, background.slice, session.slice). This provides a degree
of resource isolation between different user services competing for
the CPU.
* Systemd can optionally do a full preset in the "first boot" condition
(instead of just enable-only). This behaviour is controlled by the
compile-time option -Dfirst-boot-full-preset. Right now it defaults
to 'false', but the plan is to switch it to 'true' for the subsequent
release.
* Drop-ins are now allowed for transient units too.
* Systemd will set the taint flag 'support-ended' if it detects that
the OS image is past its end-of-support date. This date is declared
in a new /etc/os-release field SUPPORT_END= described below.
* Two new settings ConditionCredential= and AssertCredential= can be
used to skip or fail units if a certain system credential is not
provided.
* ConditionMemory= accepts size suffixes (K, M, G, T, …).
* DefaultSmackProcessLabel= can be used in system.conf and user.conf to
specify the SMACK security label to use when not specified in a unit
file.
* DefaultDeviceTimeoutSec= can be used in system.conf and user.conf to
specify the default timeout when waiting for device units to
activate.
* C.UTF-8 is used as the default locale if nothing else has been
configured.
* [Condition|Assert]Firmware= have been extended to support certain
SMBIOS fields. For example
ConditionFirmware=smbios-field(board_name = "Custom Board")
conditionalizes the unit to run only when
/sys/class/dmi/id/board_name contains "Custom Board" (without the
quotes).
* ConditionFirstBoot= now correctly evaluates as true only during the
boot phase of the first boot. A unit executed later, after booting
has completed, will no longer evaluate this condition as true.
* Socket units will now create sockets in the SELinuxContext= of the
associated service unit, if any.
* Boot phase transitions (start initrd → exit initrd → boot complete →
shutdown) will be measured into TPM2 PCR 11, so that secrets can be
bound to a specific runtime phase. E.g.: a LUKS encryption key can be
unsealed only in the initrd.
* Service credentials (i.e. SetCredential=/LoadCredential=/…) will now
also be provided to ExecStartPre= processes.
* Various units are now correctly ordered against
initrd-switch-root.target where previously a conflict without
ordering was configured. A stop job for those units would be queued,
but without the ordering it could be executed only after
initrd-switch-root.service, leading to units not being restarted in
the host system as expected.
* In order to fully support the IPMI watchdog driver, which has not yet
been ported to the new common watchdog device interface,
/dev/watchdog0 will be tried first and systemd will silently fallback
to /dev/watchdog if it is not found.
* New watchdog-related D-Bus properties are now published by systemd:
WatchdogDevice, WatchdogLastPingTimestamp,
WatchdogLastPingTimestampMonotonic.
* At shutdown, API virtual files systems (proc, sys, etc.) will be
unmounted lazily.
* At shutdown, systemd will now log about processes blocking unmounting
of file systems.
* A new meson build option 'clock-valid-range-usec-max' was added to
allow disabling system time correction if RTC returns a timestamp far
in the future.
* Propagated restart jobs will no longer be discarded while a unit is
activating.
* PID 1 will now import system credentials from SMBIOS Type 11 fields
("OEM vendor strings"), in addition to qemu_fwcfg. This provides a
simple, fast and generic path for supplying credentials to a VM,
without involving external tools such as cloud-init/ignition.
* The CPUWeight= setting of unit files now accepts a new special value
"idle", which configures "idle" level scheduling for the unit.
* Service processes that are activated due to a .timer or .path unit
triggering will now receive information about this via environment
variables. Note that this is information is lossy, as activation
might be coalesced and only one of the activating triggers will be
reported. This is hence more suited for debugging or tracing rather
than for behaviour decisions.
* The riscv_flush_icache(2) system call has been added to the list of
system calls allowed by default when SystemCallFilter= is used.
* The selinux context derived from the target executable, instead of
'init_t' used for the manager itself, is now used when creating
listening sockets for units that specify SELinuxContextFromNet=yes.
Changes in sd-boot, bootctl, and the Boot Loader Specification:
* The Boot Loader Specification has been cleaned up and clarified.
Various corner cases in version string comparisons have been fixed
(e.g. comparisons for empty strings). Boot counting is now part of
the main specification.
* New PCRs measurements are performed during boot: PCR 11 for the the
kernel+initrd combo, PCR 13 for any sysext images. If a measurement
took place this is now reported to userspace via the new
StubPcrKernelImage and StubPcrInitRDSysExts EFI variables.
* As before, systemd-stub will measure kernel parameters and system
credentials into PCR 12. It will now report this fact via the
StubPcrKernelParameters EFI variable to userspace.
* The UEFI monotonic boot counter is now included in the updated random
seed file maintained by sd-boot, providing some additional entropy.
* sd-stub will use LoadImage/StartImage to execute the kernel, instead
of arranging the image manually and jumping to the kernel entry
point. sd-stub also installs a temporary UEFI SecurityOverride to
allow the (unsigned) nested image to be booted. This is safe because
the outer (signed) stub+kernel binary must have been verified before
the stub was executed.
* Booting in EFI mixed mode (a 64-bit kernel over 32-bit UEFI firmware)
is now supported by sd-boot.
* bootctl gained a bunch of new options: --all-architectures to install
binaries for all supported EFI architectures, --root= and --image=
options to operate on a directory or disk image, and
--install-source= to specify the source for binaries to install,
--efi-boot-option-description= to control the name of the boot entry.
* The sd-boot stub exports a StubFeatures flag, which is used by
bootctl to show features supported by the stub that was used to boot.
* sd-boot will now try to detect and warn about overlapping PE sections
in the UKI.
* sd-stub now accepts (and passes to the initrd and then to the full
OS) new PE sections '.pcrsig' and '.pcrkey' that can be used to embed
signatures of expected PCR values, to allow sealing secrets via the
TPM2 against pre-calculated PCR measurements.
Changes in the hardware database:
* 'systemd-hwdb query' now supports the --root= option.
Changes in systemctl:
* systemctl now supports --state= and --type= options for the 'show'
and 'status' verbs.
* systemctl gained a new verb 'list-automounts' to list automount
points.
* systemctl gained support for a new --image= switch to be able to
operate on the specified disk image (similar to the existing --root=
which operates relative to some directory).
Changes in systemd-networkd:
* networkd can set Linux NetLabel labels for integration with the
network control in security modules via a new NetLabel= option.
* The RapidCommit= is (re-)introduced to enable faster configuration
via DHCPv6 (RFC 3315).
* networkd gained a new option TCPCongestionControlAlgorithm= that
allows setting a per-route TCP algorithm.
* networkd gained a new option KeepFileDescriptor= to allow keeping a
reference (file descriptor) open on TUN/TAP interfaces, which is
useful to avoid link flaps while the underlying service providing the
interface is being serviced.
Changes in systemd-nspawn:
* The --bind= and --overlay= options now support relative paths.
* The --bind= option now supports a 'rootidmap' value, which will
use id-mapped mounts to map the root user inside the container to the
owner of the mounted directory on the host.
Changes in systemd-resolved:
* systemd-resolved now persists DNSOverTLS in its state file too. This
fixes a problem when used in combination with NetworkManager, which
sends the setting only once, causing it to be lost if resolved was
restarted at any point.
* systemd-resolved now exposes a varlink socket at
/run/systemd/resolve/io.systemd.Resolve.Monitor, accessible only for
root. Processed DNS requests in a JSON format will be published to
any clients connected to this socket.
resolvectl gained a 'monitor' verb to make use of this.
* systemd-resolved now treats unsupported DNSSEC algorithms as INSECURE
instead of returning SERVFAIL, as per RFC:
https://datatracker.ietf.org/doc/html/rfc6840#section-5.2
* OpenSSL is the default crypto backend for systemd-resolved. (gnutls
is still supported.)
Changes in libsystemd and other libraries:
* libsystemd now exports sd_bus_error_setfv() (a convenience function
for setting bus errors), sd_id128_string_equal (a convenience
function for 128bit ID string comparisons), and
sd_bus_message_read_strv_extend() (a function to incrementally read
string arrays).
* libsystemd now exports sd_device_get_child_first()/_next() as a
high-level interface for enumerating child devices. It also supports
sd_device_new_child() for opening a child device given a device
object.
* libsystemd now exports sd_device_monitor_set()/get_description()
which allow setting a custom description that will be used in log
messages by sd_device_monitor*.
* Private shared libraries (libsystemd-shared-nnn.so,
libsystemd-core-nnn.so) are now installed into arch-specific
directories to allow multi-arch installs.
* A new sd-gpt.h header is now published, listing GUIDs from the
Discoverable Partitions specification. For more details see:
https://systemd.io/DISCOVERABLE_PARTITIONS/
* A new function sd_hwdb_new_from_path() has been added to open a hwdb
database given an explicit path to the file.
* The signal number argument to sd_event_add_signal() now can now be
ORed with the SD_EVENT_SIGNAL_PROCMASK flag, causing sigprocmask() to
be automatically invoked to block the specified signal. This is
useful to simplify invocations as the caller doesn't have to do this
manually.
* A new convenience call sd_event_set_signal_exit() has been added to
sd-event to set up signal handling so that the event loop
automatically terminates cleanly on SIGTERM/SIGINT.
Changes in other components:
* systemd-sysusers, systemd-tmpfiles, and systemd-sysctl configuration
can now be provided via the credential mechanism.
* systemd-analyze gained a new verb 'compare-versions' that implements
comparisons for versions strings (similarly to 'rpmdev-vercmp' and
'dpkg --compare-versions').
* 'systemd-analyze dump' is extended to accept glob patterns for unit
names to limit the output to matching units.
* tmpfiles.d/ lines can read file contents to write from a credential.
The new modifier char '^' is used to specify that the argument is a
credential name. This mechanism is used to automatically populate
/etc/motd, /etc/issue, and /etc/hosts from credentials.
* tmpfiles.d/ may now be configured to avoid changing uid/gid/mode of
an inode if the specification is prefixed with ':' and the inode
already exists.
* Default tmpfiles.d/ configuration now carries a line to automatically
use an 'ssh.authorized_keys.root' credential if provided to set up
the SSH authorized_keys file for the root user.
* systemd-tmpfiles will now gracefully handle absent source of "C" copy
lines.
* tmpfiles.d/ F/w lines now optionally permit encoding of the payload
in base64. This is useful to write arbitrary binary data into files.
* The pkgconfig and rpm macros files now export the directory for user
units as 'user_tmpfiles_dir' and '%_user_tmpfilesdir'.
* Detection of Apple Virtualization and detection of Parallels and
KubeVirt virtualization on non-x86 archs have been added.
* os-release gained a new field SUPPORT_END=YYYY-MM-DD to inform the
user when their system will become unsupported.
* When performing suspend-then-hibernate, the system will estimate the
discharge rate and use that to set the delay until hibernation and
hibernate immediately instead of suspending when running from a
battery and the capacity is below 5%.
* systemd-sysctl gained a --strict option to fail when a sysctl
setting is unknown to the kernel.
* machinectl supports --force for the 'copy-to' and 'copy-from'
verbs.
* coredumpctl gained the --root and --image options to look for journal
files under the specified root directory, image, or block device.
* 'journalctl -o' and similar commands now implement a new output mode
"short-delta". It is similar to "short-monotonic", but also shows the
time delta between subsequent messages.
* journalctl now respects the --quiet flag when verifying consistency
of journal files.
* Journal log messages gained a new implicit field _RUNTIME_SCOPE= that
will indicate whether a message was logged in the 'initrd' phase or
in the 'system' phase of the boot process.
* Journal files gained a new compatibility flag
'HEADER_INCOMPATIBLE_COMPACT'. Files with this flag implement changes
to the storage format that allow reducing size on disk. As with other
compatibility flags, older journalctl versions will not be able to
read journal files using this new format. The environment variable
'SYSTEMD_JOURNAL_COMPACT=0' can be passed to systemd-journald to
disable this functionality. It is enabled by default.
* systemd-run's --working-directory= switch now works when used in
combination with --scope.
* portablectl gained a --force flag to skip certain sanity checks. This
is implemented using new flags accepted by systemd-portabled for the
*WithExtensions() D-Bus methods: SD_SYSTEMD_PORTABLE_FORCE_ATTACH
flag now means that the attach/detach checks whether the units are
already present and running will be skipped. Similarly,
SD_SYSTEMD_PORTABLE_FORCE_SYSEXT flag means that the check whether
image name matches the name declared inside of the image will be
skipped. Callers must be sure to do those checks themselves if
appropriate.
* systemd-portabled will now use the original filename to check
extension-release.NAME for correctness, in case it is passed a
symlink.
* systemd-portabled now uses PrivateTmp=yes in the 'trusted' profile
too.
* sysext's extension-release files now support '_any' as a special
value for the ID= field, to allow distribution-independent extensions
(e.g.: fully statically compiled binaries, scripts). It also gained
support for a new ARCHITECTURE= field that may be used to explicitly
restrict an image to hosts of a specific architecture.
* systemd-repart now supports creating squashfs partitions. This
requires mksquashfs from squashfs-tools.
* systemd-repart gained a --split flag to also generate split
artifacts, i.e. a separate file for each partition. This is useful in
conjunction with systemd-sysupdate or other tools, or to generate
split dm-verity artifacts.
* systemd-repart is now able to generate dm-verity partitions, including
signatures.
* systemd-repart can now set a partition UUID to zero, allowing it to
be filled in later, such as when using verity partitions.
* systemd-repart now supports drop-ins for its configuration files.
* Package metadata logged by systemd-coredump in the system journal is
now more compact.
* xdg-autostart-service now expands 'tilde' characters in Exec lines.
* systemd-oomd now automatically links against libatomic, if available.
* systemd-oomd now sends out a 'Killed' D-Bus signal when a cgroup is
killed.
* scope units now also provide oom-kill status.
* systemd-pstore will now try to load only the efi_pstore kernel module
before running, ensuring that pstore can be used.
* systemd-logind gained a new StopIdleSessionSec= option to stop an idle
session after a preconfigure timeout.
* systemd-homed will now wait up to 30 seconds for workers to terminate,
rather than indefinitely.
* homectl gained a new '--luks-sector-size=' flag that allows users to
select the preferred LUKS sector size. Must be a power of 2 between 512
and 4096. systemd-userdbd records gained a corresponding field.
* systemd-sysusers will now respect the 'SOURCE_DATE_EPOCH' environment
variable when generating the 'sp_lstchg' field, to ensure an image
build can be reproducible.
* 'udevadm wait' will now listen to kernel uevents too when called with
--initialized=no.
* When naming network devices udev will now consult the Devicetree
"alias" fields for the device.
* systemd-udev will now create infiniband/by-path and
infiniband/by-ibdev links for Infiniband verbs devices.
* ConditionACPower= and systemd-ac-power will now assume the system is
running on AC power if no battery can be found.
* All features and tools using the TPM2 will now communicate with it
using a bind key. Beforehand, the tpm2 support used encrypted sessions
by creating a primary key that was used to encrypt traffic. This
creates a problem as the key created for encrypting the traffic could
be faked by an active interposer on the bus. In cases when a pin is
used, a bind key will be used. The pin is used as the auth value for
the seal key, aka the disk encryption key, and that auth value will be
used in the session establishment. An attacker would need the pin
value to create the secure session and thus an active interposer
without the pin cannot interpose on TPM2 traffic.
* systemd-growfs no longer requires udev to run.
* systemd-backlight now will better support systems with multiple
graphic cards.
* systemd-cryptsetup's keyfile-timeout= option now also works when a
device is used as a keyfile.
* systemd-cryptenroll gained a new --unlock-key-file= option to get the
unlocking key from a key file (instead of prompting the user). Note
that this is the key for unlocking the volume in order to be able to
enroll a new key, but it is not the key that is enrolled.
* systemd-dissect gained a new --umount switch that will safely and
synchronously unmount all partitions of an image previously mounted
with 'systemd-dissect --mount'.
* When using gcrypt, all systemd tools and services will now configure
it to prefer the OS random number generator if present.
Experimental features:
* BPF programs can now be compiled with bpf-gcc (requires libbpf >= 1.0
and bpftool >= 7.0).
* sd-boot can automatically enroll SecureBoot keys from files found on
the ESP. This enrollment can be either automatic ('force' mode) or
controlled by the user ('manual' mode). It is sufficient to place the
SecureBoot keys in the right place in the ESP and they will be picked
up by sd-boot and shown in the boot menu.
* The mkosi config in systemd gained support for automatically
compiling a kernel with the configuration appropriate for testing
systemd. This may be useful when developing or testing systemd in
tandem with the kernel.
Contributions from: 김인수, Adam Williamson, adrian5, Akihiko Odaki,
Alban Bedel, Albert Mikaelyan, Aleksey Vasenev, Alexander Graf,
Alexander Shopov, Alexander Wilson, Alper Nebi Yasak, Andre Kalb,
Andrew Stone, Andrey Albershteyn, Anita Zhang, Ansgar Burchardt,
Antonio Alvarez Feijoo, Arnaud Ferraris, Aryan singh, asavah,
Avamander, Avram Lubkin, Balázs Meskó, Bastien Nocera,
Benjamin Franzke, BerndAdameit, bin456789, Chih-Hsuan Yen,
Christian Brauner, Christian Göttsche, Christian Hesse, Clyde Byrd III,
codefiles, Colin Walters, Cristian Rodríguez, Daan De Meyer,
Daniel Braunwarth, Dan Streetman, Darsey Litzenberger, David Edmundson,
David Jaša, David Rheinsberg, David Tardon, dependabot[bot],
Devendra Tewari, Dominique Martinet, drosdeck, Edson Juliano Drosdeck,
Eduard Tolosa, eggfly, Einsler Lee, Elias Probst, Eli Schwartz,
Evgeny Vereshchagin, exploide, Fei Li, Foster Snowhill, Franck Bui,
Frank Dana, Frantisek Sumsal, Gio, Goffredo Baroncelli, gtwang01,
Guillaume W. Bres, H A, Hans de Goede, Heinrich Schuchardt,
Hugo Carvalho, i-do-cpp, igo95862, j00512545, Jacek Migacz,
Jade Bilkey, James Hilliard, Jan B, Janis Goldschmidt, Jan Janssen,
Jan Luebbe, Jan Macku, Jason A. Donenfeld, Javkhlanbayar Khongorzul,
Jeremy Soller, JeroenHD, jiangchuangang, João Loureiro,
Joaquín Ignacio Aramendía, Johannes Schauer Marin Rodrigues,
Jonas Kümmerlin, Jonas Witschel, Jonathan Lebon, Joost Heitbrink,
Jörg Thalheim, josh-gordon-fb, Kai Lueke, lastkrick,
Lennart Poettering, licunlong, Li kunyu, LockBlock-dev, Loïc Collignon,
Luca Boccassi, Luca BRUNO, Ludwig Nussel, Łukasz Stelmach, Maccraft123,
Marc Kleine-Budde, Marius Vollmer, Martin Wilck, matoro,
Matthias Lisin, Max Gautier, Maxim Mikityanskiy, Michael Biebl,
Michal Koutný, Michal Sekletár, Michal Stanke, Mike Gilbert,
Mitchell Freiderich, msizanoen1, Nick Rosbrook, nl6720, Oleg Solovyov,
Contributions from: 김인수, Adam Williamson, adrian5, Aidan Dang,
Akihiko Odaki, Alban Bedel, Albert Mikaelyan, Aleksey Vasenev,
Alexander Graf, Alexander Shopov, Alexander Wilson, Alper Nebi Yasak,
anarcat, Andre Kalb, Andrew Stone, Andrey Albershteyn, Anita Zhang,
Ansgar Burchardt, Antonio Alvarez Feijoo, Arnaud Ferraris, Aryan singh,
asavah, Avamander, Avram Lubkin, Balázs Meskó, Bastien Nocera,
Benjamin Franzke, BerndAdameit, bin456789, Celeste Liu, Chih-Hsuan Yen,
Christian Brauner, Christian Göttsche, Christian Hesse, Clyde Byrd III,
codefiles, Colin Walters, Cristian Rodríguez, Daan De Meyer,
Daniel Braunwarth, Dan Streetman, Darsey Litzenberger, David Edmundson,
David Jaša, David Rheinsberg, David Seifert, David Tardon,
dependabot[bot], Devendra Tewari, Dominique Martinet, drosdeck,
Edson Juliano Drosdeck, Eduard Tolosa, eggfly, Einsler Lee,
Elias Probst, Eli Schwartz, Evgeny Vereshchagin, exploide, Fei Li,
Foster Snowhill, Franck Bui, Frank Dana, Frantisek Sumsal,
Gerd Hoffmann, Gio, Goffredo Baroncelli, gtwang01, Guillaume W. Bres,
H A, Hans de Goede, Heinrich Schuchardt, Hugo Carvalho, i-do-cpp,
igo95862, j00512545, Jacek Migacz, Jade Bilkey, James Hilliard, Jan B,
Janis Goldschmidt, Jan Janssen, Jan Luebbe, Jan Macku,
Jason A. Donenfeld, Javkhlanbayar Khongorzul, Jeremy Soller, JeroenHD,
jiangchuangang, João Loureiro, Joaquín Ignacio Aramendía,
Johannes Schauer Marin Rodrigues, Jonas Kümmerlin, Jonas Witschel,
Jonathan Lebon, Joost Heitbrink, Jörg Thalheim, josh-gordon-fb,
Kai Lueke, lastkrick, Lennart Poettering, licunlong, Li kunyu,
LockBlock-dev, Loïc Collignon, Lubomir Rintel, Luca Boccassi,
Luca BRUNO, Ludwig Nussel, Łukasz Stelmach, Maccraft123,
Marc Kleine-Budde, Marius Vollmer, Martin Wilck, matoro,
Matthias Lisin, Max Gautier, Maxim Mikityanskiy, Michael Biebl,
Michal Koutný, Michal Sekletár, Michal Stanke, Mike Gilbert,
Mitchell Freiderich, msizanoen1, Nick Rosbrook, nl6720, Oleg Solovyov,
Pablo Ceballos, Pavel Zhukov, Phaedrus Leeds, Philipp Gortan,
Piotr Drąg, Pyfisch, Quentin Deslandes, Rahil Bhimjiani,
Rene Hollander, Richard Huang, Richard Phibel, Rudi Heitbaum,
Sam James, Sarah Brofeldt, Sean Anderson, Sebastian Scheibner,
Shreenidhi Shedi, Sonali Srivastava, Steve Ramage, Suraj Krishnan,
Swapnil Devesh, Ted X. Toth, Thomas Blume, Thomas Haller, Thomas Hebb,
Tomáš Hnyk, Tomasz Paweł Gajc, Topi Miettinen, Ulrich Ölmann, undef,
Uriel Corfa, Victor Westerhuis, Vincent Dagonneau,
Vishal Chillara Srinivas, Vito Caputo, Wenchao Hao, William Roberts,
williamsumendap, wineway, Yu Watanabe, Zbigniew Jędrzejewski-Szmek,
Zhaofeng Li, наб
– Under the Sea, 2022-10-07
CHANGES WITH 251:
Backwards-incompatible changes:
* The minimum kernel version required has been bumped from 3.13 to 4.15,
and CLOCK_BOOTTIME is now assumed to always exist.
* C11 with GNU extensions (aka "gnu11") is now used to build our
components. Public API headers are still restricted to ISO C89.
* In v250, a systemd-networkd feature that automatically configures
routes to addresses specified in AllowedIPs= was added and enabled by
default. However, this causes network connectivity issues in many
existing setups. Hence, it has been disabled by default since
systemd-stable 250.3. The feature can still be used by explicitly
configuring RouteTable= setting in .netdev files.
* Jobs started via StartUnitWithFlags() will no longer return 'skipped'
when a Condition*= check does not succeed, restoring the JobRemoved
signal to the behaviour it had before v250.
* The org.freedesktop.portable1 methods GetMetadataWithExtensions() and
GetImageMetadataWithExtensions() have been fixed to provide an extra
return parameter, containing the actual extension release metadata.
The current implementation was judged to be broken and unusable, and
thus the usual procedure of adding a new set of methods was skipped,
and backward compatibility broken instead on the assumption that
nobody can be affected given the current state of this interface.
* All kernels supported by systemd mix bytes returned by RDRAND (or
similar) into the entropy pool at early boot. This means that on
those systems, even if /dev/urandom is not yet initialized, it still
returns bytes that are of at least RDRAND quality. For that reason,
we no longer have reason to invoke RDRAND from systemd itself, which
has historically been a source of bugs. Furthermore, kernels ≥5.6
provide the getrandom(GRND_INSECURE) interface for returning random
bytes before the entropy pool is initialized without warning into
kmsg, which is what we attempt to use if available. systemd's direct
usage of RDRAND has been removed. x86 systems ≥Broadwell that are
running an older kernel may experience kmsg warnings that were not
seen with 250. For newer kernels, non-x86 systems, or older x86
systems, there should be no visible changes.
* sd-boot will now measure the kernel command line into TPM PCR 12
rather than PCR 8. This improves usefulness of the measurements on
systems where sd-boot is chainloaded from Grub. Grub measures all
commands its executes into PCR 8, which makes it very hard to use
reasonably, hence separate ourselves from that and use PCR 12
instead, which is what certain Ubuntu editions already do. To retain
compatibility with systems running older systemd systems a new meson
option 'efi-tpm-pcr-compat' has been added (which defaults to false).
If enabled, the measurement is done twice: into the new-style PCR 12
*and* the old-style PCR 8. It's strongly advised to migrate all users
to PCR 12 for this purpose in the long run, as we intend to remove
this compatibility feature in two years' time.
* busctl capture now writes output in the newer pcapng format instead
of pcap.
* A udev rule that imported hwdb matches for USB devices with lowercase
hexadecimal vendor/product ID digits was added in systemd 250. This
has been reverted, since uppercase hexadecimal digits are supposed to
be used, and we already had a rule with the appropriate match.
Users might need to adjust their local hwdb entries.
* arch_prctl(2) has been moved to the @default set in the syscall filters
(as exposed via the SystemCallFilter= setting in service unit files).
It is apparently used by the linker now.
* The tmpfiles entries that create the /run/systemd/netif directory and
its subdirectories were moved from tmpfiles.d/systemd.conf to
tmpfiles.d/systemd-network.conf.
Users might need to adjust their files that override tmpfiles.d/systemd.conf
to account for this change.
* The requirement for Portable Services images to contain a well-formed
os-release file (i.e.: contain at least an ID field) is now enforced.
This applies to base images and extensions, and also to systemd-sysext.
Changes in the Boot Loader Specification, kernel-install and sd-boot:
* kernel-install's and bootctl's Boot Loader Specification Type #1
entry generation logic has been reworked. The user may now pick
explicitly by which "token" string to name the installation's boot
entries, via the new /etc/kernel/entry-token file or the new
--entry-token= switch to bootctl. By default — as before — the
entries are named after the local machine ID. However, in "golden
image" environments, where the machine ID shall be initialized on
first boot (as opposed to at installation time before first boot) the
machine ID will not be available at build time. In this case the
--entry-token= switch to bootctl (or the /etc/kernel/entry-token
file) may be used to override the "token" for the entries, for
example the IMAGE_ID= or ID= fields from /etc/os-release. This will
make the OS images independent of any machine ID, and ensure that the
images will not carry any identifiable information before first boot,
but on the other hand means that multiple parallel installations of
the very same image on the same disk cannot be supported.
Summary: if you are building golden images that shall acquire
identity information exclusively on first boot, make sure to both
remove /etc/machine-id *and* to write /etc/kernel/entry-token to the
value of the IMAGE_ID= or ID= field of /etc/os-release or another
suitable identifier before deploying the image.
* The Boot Loader Specification has been extended with
/loader/entries.srel file located in the EFI System Partition (ESP)
that disambiguates the format of the entries in the /loader/entries/
directory (in order to discern them from incompatible uses of this
directory by other projects). For entries that follow the
Specification, the string "type1" is stored in this file.
bootctl will now write this file automatically when installing the
systemd-boot boot loader.
* kernel-install supports a new initrd_generator= setting in
/etc/kernel/install.conf, that is exported as
$KERNEL_INSTALL_INITRD_GENERATOR to kernel-install plugins. This
allows choosing different initrd generators.
* kernel-install will now create a "staging area" (an initially-empty
directory to gather files for a Boot Loader Specification Type #1
entry). The path to this directory is exported as
$KERNEL_INSTALL_STAGING_AREA to kernel-install plugins, which should
drop files there instead of writing them directly to the final
location. kernel-install will move them when all files have been
prepared successfully.
* New option sort-key= has been added to the Boot Loader Specification
to override the sorting order of the entries in the boot menu. It is
read by sd-boot and bootctl, and will be written by kernel-install,
with the default value of IMAGE_ID= or ID= fields from
os-release. Together, this means that on multiboot installations,
entries should be grouped and sorted in a predictable way.
* The sort order of boot entries has been updated: entries which have
the new field sort-key= are sorted by it first, and all entries
without it are ordered later. After that, entries are sorted by
version so that newest entries are towards the beginning of the list.
* The kernel-install tool gained a new 'inspect' verb which shows the
paths and other settings used.
* sd-boot can now optionally beep when the menu is shown and menu
entries are selected, which can be useful on machines without a
working display. (Controllable via a loader.conf setting.)
* The --make-machine-id-directory= switch to bootctl has been replaced
by --make-entry-directory=, given that the entry directory is not
necessarily named after the machine ID, but after some other suitable
ID as selected via --entry-token= described above. The old name of
the option is still understood to maximize compatibility.
* 'bootctl list' gained support for a new --json= switch to output boot
menu entries in JSON format.
* 'bootctl is-installed' now supports the --graceful, and various verbs
omit output with the new option --quiet.
Changes in systemd-homed:
* Starting with v250 systemd-homed uses UID/GID mapping on the mounts
of activated home directories it manages (if the kernel and selected
file systems support it). So far it mapped three UID ranges: the
range from 0…60000, the user's own UID, and the range 60514…65534,
leaving everything else unmapped (in other words, the 16bit UID range
is mapped almost fully, with the exception of the UID subrange used
for systemd-homed users, with one exception: the user's own UID).
Unmapped UIDs may not be used for file ownership in the home
directory — any chown() attempts with them will fail. With this
release a fourth range is added to these mappings:
524288…1879048191. This range is the UID range intended for container
uses, see:
https://systemd.io/UIDS-GIDS
This range may be used for container managers that place container OS
trees in the home directory (which is a questionable approach, for
quota, permission, SUID handling and network file system
compatibility reasons, but nonetheless apparently commonplace). Note
that this mapping is mapped 1:1 in a pass-through fashion, i.e. the
UID assignments from the range are not managed or mapped by
`systemd-homed`, and must be managed with other mechanisms, in the
context of the local system.
Typically, a better approach to user namespacing in relevant
container managers would be to leave container OS trees on disk at
UID offset 0, but then map them to a dynamically allocated runtime
UID range via another UID mount map at container invocation
time. That way user namespace UID ranges become strictly a runtime
concept, and do not leak into persistent file systems, persistent
user databases or persistent configuration, thus greatly simplifying
handling, and improving compatibility with home directories intended
to be portable like the ones managed by systemd-homed.
Changes in shared libraries:
* A new libsystemd-core-<version>.so private shared library is
installed under /usr/lib/systemd/system, mirroring the existing
libsystemd-shared-<version>.so library. This allows the total
installation size to be reduced by binary code reuse.
* The <version> tag used in the name of libsystemd-shared.so and
libsystemd-core.so can be configured via the meson option
'shared-lib-tag'. Distributions may build subsequent versions of the
systemd package with unique tags (e.g. the full package version),
thus allowing multiple installations of those shared libraries to be
available at the same time. This is intended to fix an issue where
programs that link to those libraries would fail to execute because
they were installed earlier or later than the appropriate version of
the library.
* The sd-id128 API gained a new call sd_id128_to_uuid_string() that is
similar to sd_id128_to_string() but formats the ID in RFC 4122 UUID
format instead of as a simple series of hex characters.
* The sd-device API gained two new calls sd_device_new_from_devname()
and sd_device_new_from_path() which permit allocating an sd_device
object from a device node name or file system path.
* sd-device also gained a new call sd_device_open() which will open the
device node associated with a device for which an sd_device object
has been allocated. The call is supposed to address races around
device nodes being removed/recycled due to hotplug events, or media
change events: the call checks internally whether the major/minor of
the device node and the "diskseq" (in case of block devices) match
with the metadata loaded in the sd_device object, thus ensuring that
the device once opened really matches the provided sd_device object.
Changes in PID1, systemctl, and systemd-oomd:
* A new set of service monitor environment variables will be passed to
OnFailure=/OnSuccess= handlers, but only if exactly one unit lists the
handler unit as OnFailure=/OnSuccess=. The variables are:
$MONITOR_SERVICE_RESULT, $MONITOR_EXIT_CODE, $MONITOR_EXIT_STATUS,
$MONITOR_INVOCATION_ID and $MONITOR_UNIT. For cases when a single
handler needs to watch multiple units, use a templated handler.
* A new ExtensionDirectories= setting in service unit files allows
system extensions to be loaded from a directory. (It is similar to
ExtensionImages=, but takes paths to directories, instead of
disk image files.)
'portablectl attach --extension=' now also accepts directory paths.
* The user.delegate and user.invocation_id extended attributes on
cgroups are used in addition to trusted.delegate and
trusted.invocation_id. The latter pair requires privileges to set,
but the former doesn't and can be also set by the unprivileged user
manager.
(Only supported on kernels ≥5.6.)
* Units that were killed by systemd-oomd will now have a service result
of 'oom-kill'. The number of times a service was killed is tallied
in the 'user.oomd_ooms' extended attribute.
The OOMPolicy= unit file setting is now also honoured by
systemd-oomd.
* In unit files the new %y/%Y specifiers can be used to refer to
normalized unit file path, which is particularly useful for symlinked
unit files.
The new %q specifier resolves to the pretty hostname
(i.e. PRETTY_HOSTNAME= from /etc/machine-info).
The new %d specifier resolves to the credentials directory of a
service (same as $CREDENTIALS_DIRECTORY).
* The RootDirectory=, MountAPIVFS=, ExtensionDirectories=,
*Capabilities*=, ProtectHome=, *Directory=, TemporaryFileSystem=,
PrivateTmp=, PrivateDevices=, PrivateNetwork=, NetworkNamespacePath=,
PrivateIPC=, IPCNamespacePath=, PrivateUsers=, ProtectClock=,
ProtectKernelTunables=, ProtectKernelModules=, ProtectKernelLogs=,
MountFlags= service settings now also work in unprivileged user
services, i.e. those run by the user's --user service manager, as long
as user namespaces are enabled on the system.
* Services with Restart=always and a failing ExecCondition= will no
longer be restarted, to bring ExecCondition= behaviour in line with
Condition*= settings.
* LoadCredential= now accepts a directory as the argument; all files
from the directory will be loaded as credentials.
* A new D-Bus property ControlGroupId is now exposed on service units,
that encapsulates the service's numeric cgroup ID that newer kernels
assign to each cgroup.
* PID 1 gained support for configuring the "pre-timeout" of watchdog
devices and the associated governor, via the new
RuntimeWatchdogPreSec= and RuntimeWatchdogPreGovernor= configuration
options in /etc/systemd/system.conf.
* systemctl's --timestamp= option gained a new choice "unix", to show
timestamp as unix times, i.e. seconds since 1970, Jan 1st.
* A new "taint" flag named "old-kernel" is introduced which is set when
the kernel systemd runs on is older then the current baseline version
(see above). The flag is shown in "systemctl status" output.
* Two additional taint flags "short-uid-range" and "short-gid-range"
have been added as well, which are set when systemd notices it is run
within a userns namespace that does not define the full 0…65535 UID
range
* A new "unmerged-usr" taint flag has been added that is set whenever
running on systems where /bin/ + /sbin/ are *not* symlinks to their
counterparts in /usr/, i.e. on systems where the /usr/-merge has not
been completed.
* Generators invoked by PID 1 will now have a couple of useful
environment variables set describing the execution context a
bit. $SYSTEMD_SCOPE encodes whether the generator is called from the
system service manager, or from the per-user service
manager. $SYSTEMD_IN_INITRD encodes whether the generator is invoked
in initrd context or on the host. $SYSTEMD_FIRST_BOOT encodes whether
systemd considers the current boot to be a "first"
boot. $SYSTEMD_VIRTUALIZATION encode whether virtualization is
detected and which type of hypervisor/container
manager. $SYSTEMD_ARCHITECTURE indicates which architecture the
kernel is built for.
* PID 1 will now automatically pick up system credentials from qemu's
fw_cfg interface, thus allowing passing arbitrary data into VM
systems similar to how this is already supported for passing them
into `systemd-nspawn` containers. Credentials may now also be passed
in via the new kernel command line option `systemd.set_credential=`
(note that kernel command line options are world-readable during
runtime, and only useful for credentials that require no
confidentiality). The credentials that can be passed to unified
kernels that use the `systemd-stub` UEFI stub are now similarly
picked up automatically. Automatic importing of system credentials
this way can be turned off via the new
`systemd.import_credentials=no` kernel command line option.
* LoadCredential= will now automatically look for credentials in the
/etc/credstore/, /run/credstore/, /usr/lib/credstore/ directories if
the argument is not an absolute path. Similarly,
LoadCredentialEncrypted= will check the same directories plus
/etc/credstore.encrypted/, /run/credstore.encrypted/ and
/usr/lib/credstore.encrypted/. The idea is to use those directories
as the system-wide location for credentials that services should pick
up automatically.
* System and service credentials are described in great detail in a new
document:
https://systemd.io/CREDENTIALS
Changes in systemd-journald:
* The journal JSON export format has been added to listed of stable
interfaces (https://systemd.io/PORTABILITY_AND_STABILITY/).
* journalctl --list-boots now supports JSON output and the --reverse option.
* Under docs/: JOURNAL_EXPORT_FORMATS was imported from the wiki and
updated, BUILDING_IMAGES is new:
https://systemd.io/JOURNAL_EXPORT_FORMATS
https://systemd.io/BUILDING_IMAGES
Changes in udev:
* Two new hwdb files have been added. One lists "handhelds" (PDAs,
calculators, etc.), the other AV production devices (DJ tables,
keypads, etc.) that should accessible to the seat owner user by
default.
* udevadm trigger gained a new --prioritized-subsystem= option to
process certain subsystems (and all their parent devices) earlier.
systemd-udev-trigger.service now uses this new option to trigger
block and TPM devices first, hopefully making the boot a bit faster.
* udevadm trigger now implements --type=all, --initialized-match,
--initialized-nomatch to trigger both subsystems and devices, only
already-initialized devices, and only devices which haven't been
initialized yet, respectively.
* udevadm gained a new "wait" command for safely waiting for a specific
device to show up in the udev device database. This is useful in