Arch Linux

1. Arch Linux 2024 Leader Election Results

   Recently we held our leader election, and the previous Project Leader Levente "anthraxx" Polyák ran again while no other people were nominated for the role.

   As per our election rules he is re-elected for a new term.

   The role of of the project lead within Arch Linux is connected to a few responsibilities regarding decision making (when no consensus can be reached), handling financial matters with SPI and overall project management tasks.

   Congratulations to Levente and all the best wishes for another successful term! 🥳

2. Increasing the default vm.max_map_count value

   The vm.max_map_count parameter will be increased from the default 65530 value to 1048576.

   This change should help address performance, crash or start-up issues for a number of memory intensive applications, particularly for (but not limited to) some Windows games played through Wine/Steam Proton. Overall, end users should have a smoother experience out of the box with no expressed concerns about potential downsides in the related proposal on arch-dev-public mailing list.

   This vm.max_map_count increase is introduced in the 2024.04.07-1 release of the filesystem package and will be effective right after the upgrade.

   Before upgrading, in case you are already setting your own value for that parameter in a sysctl.d configuration file, either remove it (to switch to the new default value) or make sure your configuration file will be read with a higher priority than the /usr/lib/sysctl.d/10-arch.conf file (to supersede the new default value).

3. The xz package has been backdoored

   Update: To our knowledge the malicious code which was distributed via the release tarball never made it into the Arch Linux provided binaries, as the build script was configured to only inject the bad code in Debian/Fedora based package build environments. The news item below can therefore mostly be ignored.

   We are closely monitoring the situation and will update the package and news as neccesary.

   ---

   TL;DR: Upgrade your systems and container images now!

   As many of you may have already read (one), the upstream release tarballs for xz in version 5.6.0 and 5.6.1 contain malicious code which adds a backdoor.

   This vulnerability is tracked in the Arch Linux security tracker (two).

   The xz packages prior to version 5.6.1-2 (specifically 5.6.0-1 and 5.6.1-1) contain this backdoor.

   The following release artifacts contain the compromised xz:

   • installation medium 2024.03.01
   • virtual machine images 20240301.218094 and 20240315.221711
   • container images created between and including 2024-02-24 and 2024-03-28

   The affected release artifacts have been removed from our mirrors.

   We strongly advise against using affected release artifacts and instead downloading what is currently available as latest version!

   Upgrading the system

   It is strongly advised to do a full system upgrade right away if your system currently has xz version 5.6.0-1 or 5.6.1-1 installed:

   pacman -Syu

   Upgrading container images

   To figure out if you are using an affected container image, use either

   podman image history archlinux/archlinux

   or

   docker image history archlinux/archlinux

   depending on whether you use podman or docker.

   Any Arch Linux container image older than 2024-03-29 and younger than 2024-02-24 is affected.

   Run either

   podman image pull archlinux/archlinux

   or

   docker image pull archlinux/archlinux

   to upgrade affected container images to the most recent version.

   Afterwards make sure to rebuild any container images based on the affected versions and also inspect any running containers!

   Regarding sshd authentication bypass/code execution

   From the upstream report (one):

   openssh does not directly use liblzma. However debian and several other distributions patch openssh to support systemd notification, and libsystemd does depend on lzma.

   Arch does not directly link openssh to liblzma, and thus this attack vector is not possible. You can confirm this by issuing the following command:

   ldd "$(command -v sshd)"

   However, out of an abundance of caution, we advise users to remove the malicious code from their system by upgrading either way. This is because other yet-to-be discovered methods to exploit the backdoor could exist.

4. mkinitcpio hook migration and early microcode

   With the release of mkinitcpio v38, several hooks previously provided by Arch packages have been moved to the mkinitcpio upstream project. The hooks are: systemd, udev, encrypt, sd-encrypt, lvm2 and mdadm_udev.

   To ensure no breakage of users' setup occurs, temporary conflicts have been introduced into the respective packages to prevent installing packages that are no longer compatible.

   The following packages needs to be upgraded together:

   • mkinitcpio 38-3
   • systemd 255.4-2
   • lvm2 2.03.23-3
   • mdadm 4.3-2
   • cryptsetup 2.7.0-3

   Please note that the mkinitcpio flag --microcode, and the microcode option in the preset files, has been deprecated in favour of a new microcode hook. This also allows you to drop the microcode initrd lines from your boot configuration as they are now packed together with the main initramfs image.

5. Making dbus-broker our default D-Bus daemon

   We are making dbus-broker our default implementation of D-Bus, for improved performance, reliability and integration with systemd.

   For the foreseeable future we will still support the use of dbus-daemon, the previous implementation. Pacman will ask you whether to install dbus-broker-units or dbus-daemon-units. We recommend picking the default.

   For a more detailed rationale, please see our RFC 25.