Linux Weekly News

Back at the end of July, the Python steering council announced its intention to approve the proposal to make the global interpreter lock (GIL) optional over the next few Python releases. The details of that acceptance are still being decided on, but work on the feature is proceeding—in discussion form at least. Beyond that, though, there are efforts underway to solve that hardest of problems in computer science, naming, for the no-GIL version.

The GitHub blog describes a vulnerability in the libcue library (which is used by the GNOME desktop) that can be exploited by a remote attacker to run code on a desktop system if the target can be convinced to click on a malicious link.

The video shows me clicking a link in a webpage, which causes a cue sheet to be downloaded. Because the file is saved to ~/Downloads, it is then automatically scanned by tracker-miners. And because it has a .cue filename extension, tracker-miners uses libcue to parse the file. The file exploits the vulnerability in libcue to gain code execution and pop a calculator.

Security updates have been issued by Fedora (chromium, firefox, and kernel), Gentoo (less and libcue), Red Hat (bind, libvpx, nodejs, and python3), Scientific Linux (firefox and thunderbird), SUSE (conmon, go1.20, go1.21, shadow, and thunderbird), and Ubuntu (libcue, ring, and ruby-kramdown).

The Linux Containers project has announced the release version 0.1 of the Incus system container and virtual-machine manager, which is a community-led fork of Canonical's LXD. Incus 0.1 "is roughly equivalent to LXD 5.18 but with a number of breaking changes on top of the obvious rename". There have been some changes made in the two months since the fork: With this initial release of Incus, we took the opportunity to remove a lot of unused or problematic features from LXD. Most of those changes are things we would have liked to do in LXD but couldn’t due to having strong guarantees around backward compatibility.

Incus will be similarly strict with backward compatibility in the future, but as this is the first release of the fork, it was our one big opportunity to change things.

That said, the API and CLI are still extremely close to what LXD has, making it trivial if not completely seamless to port from LXD to Incus.

There is an online version of Incus for those interested in giving it a try.

One of the significant features added to the mainline kernel during the 6.6 merge window was multi-grain timestamps, which allow the kernel to selectively store file modification times with higher resolution without hurting performance. Unfortunately, this feature also caused some surprising regressions, and was quickly ushered back out of the kernel as a result. It is instructive to look at how this feature went wrong, and how the developers involved plan to move forward from here.

Security updates have been issued by Debian (freerdp2, gnome-boxes, grub2, inetutils, lemonldap-ng, prometheus-alertmanager, python-urllib3, thunderbird, and vinagre), Fedora (freeimage, fwupd, libspf2, mingw-freeimage, thunderbird, and vim), Gentoo (c-ares, dav1d, Heimdal, man-db, and Oracle VirtualBox), Oracle (bind, bind9.16, firefox, ghostscript, glibc, ImageMagick, and thunderbird), Slackware (netatalk), SUSE (ImageMagick, nghttp2, poppler, python, python-gevent, and yq), and Ubuntu (bind9 and vim).

Linus has released 6.6-rc5 for testing. "Things are back to normal, and we have a networking pull this week."

Red Hat has announced that its longstanding "rhsa-announce" mailing list will be shut down on October 10. That is the list that receives security advisories for Red Hat Enterprise Linux and a whole slew of related products. Anybody who was counting on that list for Red Hat security advisories will need to find an alternative; a few options are listed in the announcement.

The latest round of stable kernels, 6.5.6, 6.1.56, and 5.15.134, have been released. Each contains a fairly large collection of important fixes throughout the kernel tree.

On its surface, the BPF virtual machine resembles many other computer architectures; it has registers and instructions to perform the usual operations. But there is a key difference: BPF programs must pass the kernel's verifier before they can be run. The verifier imposes a long list of additional restrictions so that it can prove to itself that any given program is safe to run; getting past those checks can be a source of frustration for BPF developers. At the 2023 GNU Tools Cauldron, José Marchesi looked at the problem of compiling for verified architectures and how the compiler can generate code that will pass verification.

Security updates have been issued by Debian (grub2, libvpx, libx11, libxpm, and qemu), Fedora (firefox, matrix-synapse, tacacs, thunderbird, and xrdp), Oracle (glibc), Red Hat (bind, bind9.16, firefox, frr, ghostscript, glibc, ImageMagick, libeconf, python3.11, python3.9, and thunderbird), Scientific Linux (ImageMagick), SUSE (kernel, libX11, and tomcat), and Ubuntu (linux-hwe-5.15, linux-oracle-5.15).

Ferrous Systems has announced that its Ferrocene Rust compiler will be released under the Apache-2.0 and MIT licenses.

Ferrocene is the main Rust compiler - rustc - but quality managed and qualified for use in automotive and industrial environments (currently by ISO 26262 and IEC 61508) by Ferrous Systems. It operates as a downstream to the Rust project, further increasing its testing and quality on specific platforms.

The license is free, but this is not being run as an open-source project; specifically, contributions from the "general public" are not accepted.

Hardening the Linux kernel is an endless task, with work required on multiple fronts. Sometimes, that work is not done in the kernel itself; other tools, including compilers, can have a significant role to play. At the 2023 GNU Tools Cauldron, Qing Zhao covered some of the work that has been done in the GCC compiler to help with the hardening of the kernel — along with work that still needs to be done.

Security updates have been issued by Debian (chromium, libx11, and libxpm), Fedora (ckeditor, drupal7, glibc, golang-github-cncf-xds, golang-github-envoyproxy-control-plane, golang-github-hashicorp-msgpack, golang-github-minio-highwayhash, golang-github-nats-io, golang-github-nats-io-jwt-2, golang-github-nats-io-nkeys, golang-github-nats-io-streaming-server, golang-github-protobuf, golang-google-protobuf, nats-server, and pgadmin4), Red Hat (firefox and thunderbird), SUSE (chromium, exim, ghostscript, kernel, poppler, python-gevent, and python-reportlab), and Ubuntu (binutils, exim4, jqueryui, linux, linux-aws, linux-aws-5.15, linux-azure, linux-azure-5.15, linux-azure-fde, linux-azure-fde-5.15, linux-gcp, linux-gcp-5.15, linux-gke, linux-gkeop, linux-gkeop-5.15, linux-ibm, linux-ibm-5.15, linux-kvm, linux-lowlatency, linux-lowlatency-hwe-5.15, linux-nvidia, linux-oracle, linux, linux-aws, linux-aws-5.4, linux-azure, linux-azure-5.4, linux-bluefield, linux-gcp, linux-gcp-5.4, linux-gkeop, linux-hwe-5.4, linux-ibm, linux-ibm-5.4, linux-iot, linux-kvm, linux-oracle, linux-oracle-5.4, linux-raspi, linux-raspi-5.4, linux-xilinx-zynqmp, linux, linux-aws, linux-aws-6.2, linux-azure, linux-azure-6.2, linux-azure-fde-6.2, linux-gcp, linux-gcp-6.2, linux-hwe-6.2, linux-kvm, linux-lowlatency, linux-lowlatency-hwe-6.2, linux-oracle, linux-raspi, linux-starfive, linux-kvm, linux-oem-6.1, nodejs, and python-django).

The LWN.net Weekly Edition for October 5, 2023 is available.

The eBPF in-kernel virtual machine is approaching its tenth anniversary as part of Linux; it has grown into a tool with many types of uses in the ecosystem. Alexei Starovoitov, who was the creator of eBPF and did much of the development of it, especially in the early going, gave the opening talk at Linux Security Summit Europe 2023 on the relationship between BPF and security. In it, he related some interesting history, from a somewhat different perspective than what is often described, he said. Among other things, it shows how BPF has been both a security problem and a security solution along the way.

OpenSSH 9.5 is out. Significant changes include a transport-level ping mechanism and keystroke timing obfuscation:

This attempts to hide inter-keystroke timings by sending interactive traffic at fixed intervals (default: every 20ms) when there is only a small amount of data being sent. It also sends fake "chaff" keystrokes for a random interval after the last real keystroke. These are controlled by a new ssh_config ObscureKeystrokeTiming keyword.

Security updates have been issued by Debian (glibc, postgresql-11, and thunderbird), Fedora (openmpi, pmix, prrte, and slurm), Gentoo (glibc and libvpx), Oracle (kernel), Red Hat (kernel), Slackware (libX11 and libXpm), SUSE (firefox, kernel, libeconf, libqb, libraw, libvpx, libX11, libXpm, mdadm, openssl-1_1, poppler, postfix, python311, rubygem-puma, runc, and vim), and Ubuntu (freerdp2, glibc, grub2-signed, grub2-unsigned, libx11, libxpm, linux-intel-iotg, linux-intel-iotg-5.15, linux-oracle, linux-oracle-5.15, and mozjs102).

The SteamOS Linux distribution is focused on gaming, naturally, but the effort to build it has resulted in contributions to multiple areas in the Linux ecosystem. Alberto Garcia has been working on SteamOS and came to Bilbao, Spain to describe some of those contributions at Open Source Summit Europe 2023. There are some obvious areas where a gaming-focused OS might contribute upstream, such as graphics, but the talk showed contributions in several other areas as well.

Qualys has posted an advisory for a vulnerability in the GNU C Library related to the handling of the GLIBC_TUNABLES environment variable:

We successfully exploited this vulnerability and obtained full root privileges on the default installations of Fedora 37 and 38, Ubuntu 22.04 and 23.04, Debian 12 and 13; other distributions are probably also vulnerable and exploitable (one notable exception is Alpine Linux, which uses musl libc, not the glibc).

Updates from distributors are beginning to appear and should be applied on any systems with untrusted users. The curious can see the fix applied to glibc in this patch series.