NEWS: last rites

System Internals / systemd - Zbigniew Jędrzejewski-Szmek [] - 30 July 2020 19:02 UTC



- The service manager gained basic support for cgroup v2 freezer. Units can now be suspended or resumed either using new systemctl verbs, freeze and thaw respectively, or via D-Bus.

- PID 1 may now automatically load pre-compiled AppArmor policies from /etc/apparmor/earlypolicy during early boot.

- The CPUAffinity= setting in service unit files now supports a new special value "numa" that causes the CPU affinity masked to be set based on the NUMA mask.

- systemd will now log about all left-over processes remaining in a unit when the unit is stopped. It will now warn about services using KillMode=none, as this is generally an unsafe thing to make use of.

- Two new unit file settings ConditionPathIsEncrypted=/AssertPathIsEncrypted= have been added. They may be used to check whether a specific file system path resides on a block device that is encrypted on the block level (i.e. using dm-crypt/LUKS).

- Another pair of new settings ConditionEnvironment=/AssertEnvironment= has been added that may be used for simple environment checks. This is particularly useful when passing in environment variables from a container manager (or from PAM in case of the systemd --user instance).

- .service unit files now accept a new setting CoredumpFilter= which allows configuration of the memory sections coredumps of the service's processes shall include.

- .mount units gained a new ReadWriteOnly= boolean option. If set it will not be attempted to mount a file system read-only if mounting in read-write mode doesn't succeed. An option is available in /etc/fstab to control the same.

- .socket units gained a new boolean setting PassPacketInfo=. If enabled, the kernel will attach additional per-packet metadata to all packets read from the socket, as an ancillary message. This controls the IP_PKTINFO, IPV6_RECVPKTINFO, NETLINK_PKTINFO socket options, depending on socket type.

- .service units gained a new setting RootHash= which may be used to specify the root hash for verity enabled disk images which are specified in RootImage=. RootVerity= may be used to specify a path to the Verity data matching a RootImage= file system. (The latter is only useful for images that do not contain the Verity data embedded into the same image that carries a GPT partition table following the Discoverable Partition Specification). Similarly, systemd-nspawn gained a new switch --verity-data= that takes a path to a file with the verity data of the disk image supplied in --image=, if the image doesn't contain the verity data itself.

- .service units gained a new setting RootHashSignature= which takes either a base64 encoded PKCS#7 signature of the root hash specified with RootHash=, or a path to a file to read the signature from. This allows validation of the root hash against public keys available in the kernel keyring, and is only supported on recent kernels (>= 5.4)/libcryptsetup (>= 2.30). A similar switch has been added to systemd-nspawn and systemd-dissect (--root-hash-sig=). Support for this mechanism has also been added to systemd-veritysetup.

- .service unit files gained two new options TimeoutStartFailureMode=/TimeoutStopFailureMode= that may be used to tune behaviour if a start or stop timeout is hit, i.e. whether to terminate the service with SIGTERM, SIGABRT or SIGKILL.

- Most options in systemd that accept hexadecimal values prefixed with 0x in additional to the usual decimal notation now also support octal notation when the 0o prefix is used and binary notation if the 0b prefix is used.

- Various command line parameters and configuration file settings that configure key or certificate files now optionally take paths to AF_UNIX sockets in the file system. If configured that way a stream connection is made to the socket and the required data read from it. This is a simple and natural extension to the existing regular file logic, and permits other software to provide keys or certificates via simple IPC services, for example when unencrypted storage on disk is not desired. Specifically, systemd-networkd's Wireguard and MACSEC key file settings as well as systemd-journal-gatewayd's and systemd-journal-remote's PEM key/certificate parameters support this now.

- Unit files, tmpfiles.d/ snippets, sysusers.d/ snippets and other configuration files that support specifier expansion learnt six new specifiers: %a resolves to the current architecture, %o/%w/%B/%W resolve to the various ID fields from /etc/os-release, %l resolves to the "short" hostname of the system, i.e. the hostname configured in the kernel truncated at the first dot.

- Support for the .include syntax in unit files has been removed. The concept has been obsolete for 6 years and we started warning about its pending removal 2 years ago (also see NEWS file below). It's finally gone now.

- StandardError= and StandardOutput= in unit files no longer support the "syslog" and "syslog-console" switches. They were long removed from the documentation, but will now result in warnings when used, and be converted to "journal" and "journal+console" automatically.

- If the service setting User= is set to the "nobody" user, a warning message is now written to the logs (but the value is nonetheless accepted). Setting User=nobody is unsafe, since the primary purpose of the "nobody" user is to own all files whose owner cannot be mapped locally. It's in particular used by the NFS subsystem and in user namespacing. By running a service under this user's UID it might get read and even write access to all these otherwise unmappable files, which is quite likely a major security problem.

- tmpfs mounts automatically created by systemd (/tmp, /run, /dev/shm, and others) now have a size and inode limits applied (50% of RAM for /tmp and /dev/shm, 10% of RAM for other mounts, etc.)

- nss-mymachines lost support for resolution of users and groups, and now only does resolution of hostnames. This functionality is now provided by nss-systemd. Thus, the 'mymachines' entry should be removed from the 'passwd:' and 'group:' lines in /etc/nsswitch.conf (and 'systemd' added if it is not already there).

- A new kernel command line option systemd.hostname= has been added that allows controlling the hostname that is initialized early during boot.

- A kernel command line option "udev.blockdev_read_only" has been added. If specified all hardware block devices that show up are immediately marked as read-only by udev. This option is useful for making sure that a specific boot under no circumstances modifies data on disk. Use "blockdev --setrw" to undo the effect of this, per device.

- A new boolean kernel command line option systemd.swap= has been added, which may be used to turn off automatic activation of swap devices listed in /etc/fstab.

- New kernel command line options systemd.condition-needs-update= and systemd.condition-first-boot= have been added, which override the result of the ConditionNeedsUpdate= and ConditionFirstBoot= conditions.

- A new kernel command line option systemd.clock-usec= has been added that allows setting the system clock to the specified time in µs since Jan 1st, 1970 early during boot. This is in particular useful in order to make test cases more reliable.

- The fs.suid_dumpable sysctl is set to 2 / "suidsafe". This allows systemd-coredump to save core files for suid processes. When saving the core file, systemd-coredump will use the effective uid and gid of the process that faulted.

- The /sys/module/kernel/parameters/crash_kexec_post_notifiers file is now automatically set to "Y" at boot, in order to enable pstore generation for collection with systemd-pstore.

- A new 'hwdb' file has been added that collects information about PCI and USB devices that correctly support auto-suspend, on top of the databases for this we import from the ChromiumOS project. If you have a device that supports auto-suspend correctly and where it should be enabled by default, please submit a patch that adds it to the database (see /usr/lib/udev/hwdb.d/60-autosuspend.hwdb).

- systemd-udevd gained the new configuration option timeout_signal= as well as a corresponding kernel command line option udev.timeout_signal=. The option can be used to configure the UNIX signal that the main daemon sends to the worker processes on timeout. Setting the signal to SIGABRT is useful for debugging.

- .link files managed by systemd-udevd gained options RxFlowControl=, TxFlowControl=, AutoNegotiationFlowControl= in the [Link] section, in order to configure various flow control parameters. They also gained RxMiniBufferSize= and RxJumboBufferSize= in order to configure jumbo frame ring buffer sizes.

- networkd.conf gained a new boolean setting ManageForeignRoutes=. If enabled systemd-networkd manages all routes configured by other tools.

- .network files managed by systemd-networkd gained a new section [SR-IOV], in order to configure SR-IOV capable network devices.

- systemd-networkd's [IPv6Prefix] section in .network files gained a new boolean setting Assign=. If enabled an address from the prefix is automatically assigned to the interface.

- systemd-networkd gained a new section [DHCPv6PrefixDelegation] which controls delegated prefixes assigned by DHCPv6 client. The section has three settings: SubnetID=, Assign=, and Token=. The setting SubnetID= allows explicit configuration of the preferred subnet that systemd-networkd's Prefix Delegation logic assigns to interfaces. If Assign= is enabled (which is the default) an address from any acquired delegated prefix is automatically chosen and assigned to the interface. The setting Token= specifies an optional address generation mode for Assign=.

- systemd-networkd's [Network] section gained a new setting IPv4AcceptLocal=. If enabled the interface accepts packets with local source addresses.

- systemd-networkd gained support for configuring the HTB queuing discipline in the [HierarchyTokenBucket] and [HierarchyTokenBucketClass] sections. Similar the "pfifo" qdisc may be configured in the [PFIFO] section, "GRED" in [GenericRandomEarlyDetection], "SFB" in [StochasticFairBlue], "cake" in [CAKE], "PIE" in [PIE], "DRR" in [DeficitRoundRobinScheduler] and [DeficitRoundRobinSchedulerClass], "BFIFO" in [BFIFO], "PFIFOHeadDrop" in [PFIFOHeadDrop], "PFIFOFast" in [PFIFOFast], "HHF" in [HeavyHitterFilter], "ETS" in [EnhancedTransmissionSelection] and "QFQ" in [QuickFairQueueing] and [QuickFairQueueingClass].

- systemd-networkd gained support for a new Termination= setting in the [CAN] section for configuring the termination resistor. It also gained a new ListenOnly= setting for controlling whether to only listen on CAN interfaces, without interfering with traffic otherwise (which is useful for debugging/monitoring CAN network traffic). DataBitRate=, DataSamplePoint=, FDMode=, FDNonISO= have been added to configure various CAN-FD aspects.

- systemd-networkd's [DHCPv6] section gained a new option WithoutRA=. When enabled, DHCPv6 will be attempted right-away without requiring an Router Advertisement packet suggesting it first (i.e. without the 'M' or 'O' flags set). The [IPv6AcceptRA] section gained a boolean option DHCPv6Client= that may be used to turn off the DHCPv6 client even if the RA packets suggest it.

- systemd-networkd's [DHCPv4] section gained a new setting UseGateway= which may be used to turn off use of the gateway information provided by the DHCP lease. A new FallbackLeaseLifetimeSec= setting may be used to configure how to process leases that lack a lifetime option.

- systemd-networkd's [DHCPv4] and [DHCPServer] sections gained a new setting SendVendorOption= allowing configuration of additional vendor options to send in the DHCP requests/responses. The [DHCPv6] section gained a new SendOption= setting for sending arbitrary DHCP options. RequestOptions= has been added to request arbitrary options from the server. UserClass= has been added to set the DHCP user class field.

- systemd-networkd's [DHCPServer] section gained a new set of options EmitPOP3=/POP3=, EmitSMTP=/SMTP=, EmitLPR=/LPR= for including server information about these three protocols in the DHCP lease. It also gained support for including "MUD" URLs ("Manufacturer Usage Description"). Support for "MUD" URLs was also added to the LLDP stack, configurable in the [LLDP] section in .network files.

- The Mode= settings in [MACVLAN] and [MACVTAP] now support 'source' mode. Also, the sections now support a new setting SourceMACAddress=.

- systemd-networkd's .netdev files now support a new setting
VLANProtocol= in the [Bridge] section that allows configuration of the VLAN protocol to use.

- systemd-networkd supports a new Group= setting in the [Link] section of the .network files, to control the link group.

- systemd-networkd's [Network] section gained a new IPv6LinkLocalAddressGenerationMode= setting, which specifies how IPv6 link local address is generated.

- A new default .network file is now shipped that matches TUN/TAP devices that begin with "vt-" in their name. Such interfaces will have IP routing onto the host links set up automatically. This is supposed to be used by VM managers to trivially acquire a network interface which is fully set up for host communication, simply by carefully picking an interface name to use.

- systemd-networkd's [DHCPv6] section gained a new setting RouteMetric= which sets the route priority for routes specified by the DHCP server.

- systemd-networkd's [DHCPv6] section gained a new setting VendorClass= which configures the vendor class information sent to DHCP server.

- The BlackList= settings in .network files' [DHCPv4] and [IPv6AcceptRA] sections have been renamed DenyList=. The old names are still understood to provide compatibility.

- networkctl gained the new "forcerenew" command for forcing all DHCP server clients to renew their lease. The interface "status" output will now show numerous additional fields of information about an interface. There are new "up" and "down" commands to bring specific interfaces up or down.

- systemd-resolved's DNS= configuration option now optionally accepts a port number (after ":") and a host name (after "#"). When the host name is specified, the DNS-over-TLS certificate is validated to match the specified hostname. Additionally, in case of IPv6 addresses, an interface may be specified (after "%").

- systemd-resolved may be configured to forward single-label DNS names. This is not standard-conformant, but may make sense in setups where public DNS servers are not used.

- systemd-resolved's DNS-over-TLS support gained SNI validation.

- systemd-nspawn's --resolv-conf= switch gained a number of new supported values. Specifically, options starting with "replace-" are like those prefixed "copy-" but replace any existing resolv.conf file. And options ending in "-uplink" and "-stub" can now be used to propagate other flavours of resolv.conf into the container (as defined by systemd-resolved).

- The various programs included in systemd can now optionally output their log messages on stderr prefixed with a timestamp, controlled by the $SYSTEMD_LOG_TIME environment variable.

- systemctl gained a new "-P" switch that is a shortcut for "--value

- "systemctl list-units" and "systemctl list-machines" no longer hide their first output column with --no-legend. To hide the first column, use --plain.

- "systemctl reboot" takes the option "--reboot-argument=". The optional positional argument to "systemctl reboot" is now being deprecated in favor of this option.

- systemd-run gained a new switch --slice-inherit. If specified the unit it generates is placed in the same slice as the systemd-run process itself.

- systemd-journald gained support for zstd compression of large fields in journal files. The hash tables in journal files have been hardened against hash collisions. This is an incompatible change and means that journal files created with new systemd versions are not readable with old versions. If the $SYSTEMD_JOURNAL_KEYED_HASH boolean environment variable for systemd-journald.service is set to 0 this new hardening functionality may be turned off, so that generated journal files remain compatible with older journalctl implementations.

- journalctl will now include a clickable link in the default output for each log message for which an URL with further documentation is known. This is only supported on terminal emulators that support clickable hyperlinks, and is turned off if a pager is used (since "less" still doesn't support hyperlinks, unfortunately). Documentation URLs may be included in log messages either by including a DOCUMENTATION= journal field in it, or by associating a journal message catalog entry with the log message's MESSAGE_ID, which then carries a "Documentation:" tag.

- journald.conf gained a new boolean setting Audit= that may be used to control whether systemd-journald will enable audit during initialization.

- when systemd-journald's log stream is broken up into multiple lines because the PID of the sender changed this is indicated in the generated log records via the _LINE_BREAK=pid-change field.

- journalctl's "-o cat" output mode will now show one or more journal fields specified with --output-fields= instead of unconditionally MESSAGE=. This is useful to retrieve a very specific set of fields without any decoration.

- The sd-journal.h API gained two new functions: sd_journal_enumerate_available_unique() and sd_journal_enumerate_available_data() that operate like their counterparts that lack the _available_ in the name, but skip items that cannot be read and processed by the local implementation (i.e. are compressed in an unsupported format or such),

- coredumpctl gained a new --file= switch, matching the same one in journalctl: a specific journal file may be specified to read the coredump data from.

- coredumps collected by systemd-coredump may now be compressed using the zstd algorithm.

- systemd-binfmt gained a new switch --unregister for unregistering all registered entries at once. This is now invoked automatically at shutdown, so that binary formats registered with the "F" flag will not block clean file system unmounting.

- systemd-notify's --pid= switch gained new values: "parent", "self", "auto" for controlling which PID to send to the service manager: the systemd-notify process' PID, or the one of the process invoking it.

- systemd-logind's Session bus object learnt a new method call SetType() for temporarily updating the session type of an already allocated session. This is useful for upgrading tty sessions to graphical ones once a compositor is invoked.

- systemd-socket-proxy gained a new switch --exit-idle-time= for configuring an exit-on-idle time.

- systemd-repart's --empty= setting gained a new value "create". If specified a new empty regular disk image file is created under the specified name. Its size may be specified with the new --size= option. The latter is also supported without the "create" mode, in order to grow existing disk image files to the specified size. These two new options are useful when creating or manipulating disk images instead of operating on actual block devices.

- systemd-repart drop-ins now support a new UUID= setting to control the UUID to assign to a newly created partition.

- systemd-repart's SizeMin= per-partition parameter now defaults to 10M instead of 0.

- systemd-repart's Label= setting now support the usual, simple specifier expansion.

- systemd-homed's LUKS backend gained the ability to discard empty file system blocks automatically when the user logs out. This is enabled by default to ensure that home directories take minimal space when logged out but get full size guarantees when logged in. This may be controlled with the new --luks-offline-discard= switch to homectl.

- If systemd-homed detects that /home/ is encrypted as a whole it will now default to the directory or subvolume backends instead of the LUKS backend, in order to avoid double encryption. The default storage and file system may now be configured explicitly, too, via the new /etc/systemd/homed.conf configuration file.

- systemd-homed now supports unlocking home directories with FIDO2 security tokens that support the 'hmac-secret' extension, in addition to the existing support for PKCS#11 security token unlocking support. Note that many recent hardware security tokens support both interfaces. The FIDO2 support is accessible via homectl's
--fido2-device= option.

- homectl's --pkcs11-uri= setting now accepts two special parameters: if "auto" is specified and only one suitable PKCS#11 security token is plugged in, its URL is automatically determined and enrolled for unlocking the home directory. If "list" is specified a brief table of suitable PKCS#11 security tokens is shown. Similar, the new--fido2-device= option also supports these two special values, for automatically selecting and listing suitable FIDO2 devices.

- The /etc/crypttab tmp option now optionally takes an argument selecting the file system to use. Moreover, the default is now changed from ext2 to ext4.

- There's a new /etc/crypttab option "keyfile-erase". If specified the key file listed in the same line is removed after use, regardless if
volume activation was successful or not. This is useful if the key file is only acquired transiently at runtime and shall be erased before the system continues to boot.

- There's also a new /etc/crypttab option "try-empty-password". If specified, before asking the user for a password it is attempted to unlock the volume with an empty password. This is useful for installing encrypted images whose password shall be set on first boot instead of at installation time.

- systemd-cryptsetup will now attempt to load the keys to unlock
volumes with automatically from files in /etc/cryptsetup-keys.d/.key and /run/cryptsetup-keys.d/.key, if any of these files exist.

- systemd-cryptsetup may now activate Microsoft BitLocker volumes via /etc/crypttab, during boot.

- logind.conf gained a new RuntimeDirectoryInodesMax= setting to control the inode limit for the per-user $XDG_RUNTIME_DIR tmpfs instance.

- A new generator systemd-xdg-autostart-generator has been added. It generates systemd unit files from XDG autostart .desktop files, and may be used to let the systemd user instance manage services that are started automatically as part of the desktop session.

- "bootctl" gained a new verb "reboot-to-firmware" that may be used to query and change the firmware's 'reboot into firmware' setup flag.

- systemd-firstboot gained a new switch --kernel-command-line= that may be used to initialize the /etc/kernel/cmdline file of the image. It also gained a new switch --root-password-hashed= which is like--root-password= but accepts a pre-hashed UNIX password as argument. The new option --delete-root-password may be used to unset any password for the root user (dangerous!). The --root-shell= switch may be used to control the shell to use for the root account. A new--force option may be used to override any already set settings with the parameters specified on the command line (by default, the tool will not override what has already been set before, i.e. is purely incremental).

- systemd-firstboot gained support for a new --image= switch, which is similar to --root= but accepts the path to a disk image file, on which it then operates.

- A new sd-path.h API has been added to libsystemd. It provides a simple API for retrieving various search paths and primary directories for various resources.

- A new call sd_notify_barrier() has been added to the sd-daemon.h API. The call will block until all previously sent sd_notify() messages have been processed by the service manager. This is useful to remove races caused by a process already having disappeared at the time a notification message is processed by the service manager, making correct attribution impossible. The systemd-notify tool will now make use of this call implicitly, but this can be turned off again
via the new --no-block switch.

- When sending a file descriptor (fd) to the service manager to keep track of, using the sd_notify() mechanism, a new parameter FDPOLL=0 may be specified. If passed the service manager will refrain from poll()ing on the file descriptor. Traditionally (and when the parameter is not specified), the service manager will poll it for POLLHUP or POLLERR events, and immediately close the fds in that case.

- The service manager (PID1) gained a new D-Bus method call SetShowStatus() which may be used to control whether it shall show boot-time status output on the console. This method has a similar effect to sending SIGRTMIN+20/SIGRTMIN+21 to PID 1.

- The sd-bus API gained a number of convenience functions that take
va_list arguments rather than "...". For example, there's now sd_bus_call_methodv() to match sd_bus_call_method(). Those calls make it easier to build wrappers that accept variadic arguments and want to pass a ready va_list structure to sd-bus.

- sd-bus vtable entries can have a new SD_BUS_VTABLE_ABSOLUTE_OFFSET flag which alters how the userdata pointer to pass to the callbacks is determined. When the flag is set, the offset field is converted as-is into a pointer, without adding it to the object pointer the
vtable is associated with.

- sd-bus now exposes four new functions: sd_bus_interface_name_is_valid() + sd_bus_service_name_is_valid() + sd_bus_member_name_is_valid() + sd_bus_object_path_is_valid() will
validate strings to check if they qualify as various D-Bus concepts.

- The sd-bus API gained the SD_BUS_METHOD_WITH_ARGS(), SD_BUS_METHOD_WITH_ARGS_OFFSET() and SD_BUS_SIGNAL_WITH_ARGS() macros that simplify adding argument names to D-Bus methods and signals.

- The man pages for the sd-bus and sd-hwdb APIs have been completed.

- Various D-Bus APIs of systemd daemons now have man pages that document the methods, signals and properties.

- The expectations on user/group name syntax are now documented in detail; documentation on how classic home directories may be converted into home directories managed by homed has been added; documentation regarding integration of homed/userdb functionality in desktops has been added:

- Documentation for the on-disk Journal file format has been updated and has now moved to:

- The interface for containers ( has been extended by a set of environment variables that expose select fields from the host's os-release file to the container payload. Similarly, host's os-release files can be mounted into the container underneath /run/host. Together, those mechanisms provide a standardized way to expose information about the host to the container payload. Both interfaces are implemented in systemd-nspawn.

- All D-Bus services shipped in systemd now implement the generic LogControl1 D-Bus API which allows clients to change log level + target of the service during runtime.

- Only relevant for developers: the mkosi.default symlink has been dropped from version control. Please create a symlink to one of the distribution-specific defaults in .mkosi/ based on your preference.

ae366f3acb NEWS: last rites
NEWS | 80 ++++++++++++++++++++++++++++++++++----------------------------------
1 file changed, 40 insertions(+), 40 deletions(-)


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