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LWN.net is a comprehensive source of news and opinions from and about the Linux community. This is the main LWN.net feed, listing all articles which are posted to the site front page.
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[$] Continued attacks on HTTP/2

Sre, 04/10/2024 - 14:52

On April 3 security researcher Bartek Nowotarski published the details of a new denial-of-service (DoS) attack, called a "continuation flood", against many HTTP/2-capable web servers. While the attack is not terribly complex, it affects many independent implementations of the HTTP/2 protocol, even though multiple similar vulnerabilities over the years have given implementers plenty of warning.

Security updates for Wednesday

Sre, 04/10/2024 - 13:53
Security updates have been issued by Debian (gtkwave), Fedora (dotnet7.0, dotnet8.0, and python-pillow), Mageia (apache, gstreamer1.0, libreoffice, perl-Data-UUID, and xen), Oracle (kernel, kernel-container, and varnish), Red Hat (edk2, kernel, rear, and unbound), SUSE (apache2-mod_jk, gnutls, less, and xfig), and Ubuntu (bind9, 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-kvm, linux-oracle, linux-oracle-5.4, linux-raspi, linux-raspi-5.4, linux, linux-aws, linux-azure, linux-azure-6.5, linux-gcp, linux-gcp-6.5, linux-hwe-6.5, linux-laptop, linux-lowlatency, linux-lowlatency-hwe-6.5, linux-oem-6.5, linux-oracle, linux-oracle-6.5, linux-starfive, linux-starfive-6.5, linux, 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-hwe-5.15, linux-ibm, linux-ibm-5.15, linux-intel-iotg, linux-intel-iotg-5.15, linux-kvm, linux-lowlatency, linux-lowlatency-hwe-5.15, linux-nvidia, linux-oracle, linux-oracle-5.15, linux-raspi, linux-azure, and xorg-server, xwayland).

The "branch history injection" hardware vulnerability

Tor, 04/09/2024 - 20:22
The mainline kernel has just received a set of commits mitigating the latest x86 hardware vulnerability, known as "branch history injection". From this commit:

Branch History Injection (BHI) attacks may allow a malicious application to influence indirect branch prediction in kernel by poisoning the branch history. eIBRS isolates indirect branch targets in ring0. The BHB can still influence the choice of indirect branch predictor entry, and although branch predictor entries are isolated between modes when eIBRS is enabled, the BHB itself is not isolated between modes.

See this commit for documentation on the command-line parameter that controls this mitigation. There are stable kernel releases (6.8.5, 6.6.26, 6.1.85, and 5.15.154) in the works that also contain the mitigations.

[$] The first Linaro Forum for Arm Linux kernel topics

Tor, 04/09/2024 - 15:50
On February 20, Linaro held the initial get-together for what is intended to be a regular Linux Kernel Forum for the Arm-focused kernel community. This gathering aims to convene approximately a few weeks prior to the merge window opening and prior to the release of the current kernel version under development. Topics covered in the first gathering include preparing 64-bit Arm kernels for low-end embedded systems, memory errors and Compute Express Link (CXL), devlink objectives, and scheduler integration.

OpenSSL 3.3.0 released

Tor, 04/09/2024 - 15:18
Version 3.3.0 of the OpenSSL SSL/TLS implementation has been released. Changes include a number of additions to its QUIC protocol support, some year-2038 improvements for 32-bit systems, and a lot of cryptographic features with descriptions like "Added a new EVP_DigestSqueeze() API. This allows SHAKE to squeeze multiple times with different output sizes." See the release notes for details.

[$] Diagnosing workqueues

Tor, 04/09/2024 - 14:51

There are many mechanisms for deferred work in the Linux kernel. One of them, workqueues, has seen increasing use as part of the move away from software interrupts. Alison Chaiken gave a talk at SCALE about how they compare to software interrupts, the new challenges they pose for system administrators, and what tools are available to kernel developers wishing to diagnose problems with workqueues as they become increasingly prevalent.

Security updates for Tuesday

Tor, 04/09/2024 - 14:25
Security updates have been issued by Debian (expat), Oracle (less and nodejs:20), Slackware (libarchive), SUSE (kubernetes1.23, nghttp2, qt6-base, and util-linux), and Ubuntu (python-django).

Security updates for Tuesday

Tor, 04/02/2024 - 14:41
Security updates have been issued by Fedora (kernel and webkitgtk), Mageia (unixODBC and w3m), and SUSE (libvirt, netty, netty-tcnative, and perl-DBD-SQLite).

[$] Improving performance with SCHED_EXT and IOCost

Pon, 04/01/2024 - 18:57

At SCALE this year Dan Schatzberg and Tejun Heo, both from Meta, gave back-to-back talks about some of the performance-engineering work that they do there. Schatzberg presented on the extensible BPF scheduler, which has been discussed extensively on the kernel mailing list. Heo presented on IOCost — a control group (cgroup) I/O controller optimized for solid-state disks (SSDs) — and the benchmark suite that is necessary to make it work well on different models of disk.

NetBSD 10.0 released

Pon, 04/01/2024 - 15:28
Version 10.0 of the NetBSD system has been released.

The netbsd-10 release branch is more than a year old now, so it is high time the 10.0 release makes it to the front stage. This matches the long time it took for the development branch to get ready for branching, a lot of development went into this new release.

This also caused the release announcement to be one of the longest we ever did.

As might be imagined, there are a lot of changes; see the above-mentioned release announcement for the details.

Security updates for Monday

Pon, 04/01/2024 - 15:10
Security updates have been issued by Arch Linux (xz), Debian (libvirt, mediawiki, util-linux, and xz-utils), Fedora (apache-commons-configuration, cockpit, ghc-base64, ghc-hakyll, ghc-isocline, ghc-toml-parser, gitit, gnutls, pandoc, pandoc-cli, patat, podman-tui, prometheus-podman-exporter, seamonkey, suricata, and xen), Gentoo (XZ utils), Mageia (aide & mhash, emacs, microcode, opensc, and squid), Red Hat (ruby:3.1), and SUSE (kanidm and qpid-proton).

Kernel prepatch 6.9-rc2

Pon, 04/01/2024 - 14:30
The 6.9-rc2 kernel prepatch is out for testing. "Neither snow nor rain nor heat nor gloom of night stays kernel rc releases. Nor does Easter."

A few relevant quotes

Sob, 03/30/2024 - 15:18

I'm on a holiday and only happened to look at my emails and it seems to be a major mess. — Lasse Collin

The reality that we are struggling with is that the free software infrastructure on which much of computing runs is massively and painfully underfunded by society as a whole, and is almost entirely dependent on random people maintaining things in their free time because they find it fun, many of whom are close to burnout. This is, in many ways, the true root cause of this entire event. — Russ Allbery

Incredible work from Andres. The attackers made a serious strategic mistake: they made PostgreSQL slightly slower. — Thomas Munro

There is no way to discuss this in public without turning a single malicious entity into 10 000 malicious entities once the information is widely known.

Making sure the impact and mitigations are known before posting this publicly so that everyone knows what to do before the 10 000 malicious entities start attacking is just common sense. — Marc Deslauriers

Again the FOSS world has proven to be vigilant and proactive in finding bugs and backdoors, IMHO. The level of transparency is stellar, especially compared to proprietary software companies. What the FOSS world has accomplished in 24 hours after detection of the backdoor code in #xz deserves a moment of humbleness. Instead we have flamewars and armchair experts shouting that we must change everything NOW. Which would introduce even more risks. Progress is made iteratively. Learn, adapt, repeat. — Jan Wildeboer

A backdoor in xz

Pet, 03/29/2024 - 18:33
Andres Freund has posted a detailed investigation into a backdoor that was shipped with versions 5.6.0 and 5.6.1 of the xz compression utility. It appears that the malicious code may be aimed at allowing SSH authentication to be bypassed.

I have not yet analyzed precisely what is being checked for in the injected code, to allow unauthorized access. Since this is running in a pre-authentication context, it seems likely to allow some form of access or other form of remote code execution.

The affected versions are not yet widely shipped, but checking systems for the bad version would be a good idea.

Update: there are advisories out now from Arch, Debian, Red Hat, and openSUSE.

A further update from openSUSE:

For our openSUSE Tumbleweed users where SSH is exposed to the internet we recommend installing fresh, as it’s unknown if the backdoor has been exploited. Due to the sophisticated nature of the backdoor an on-system detection of a breach is likely not possible. Also rotation of any credentials that could have been fetched from the system is highly recommended.

[$] Radicle: peer-to-peer collaboration with Git

Pet, 03/29/2024 - 14:40
Radicle is a new, peer-to-peer, MIT/Apache-licensed collaboration platform written in Rust and built on top of Git. It adds support for issues and pull requests (which Radicle calls "patches") on top of core Git, which are stored in the Git repository itself. Unlike GitHub, GitLab, and similar forges, Radicle is distributed; it doesn't rely on having everyone use the same server. Instead, Radicle instances form a network that synchronizes changes between nodes.

Security updates for Friday

Pet, 03/29/2024 - 14:11
Security updates have been issued by Debian (chromium), Fedora (apache-commons-configuration, chromium, csmock, ofono, onnx, php-tcpdf, and podman-tui), Mageia (curl), Oracle (libreoffice), Slackware (coreutils, seamonkey, and util), SUSE (minidlna, PackageKit, and podman), and Ubuntu (linux-azure-6.5 and linux-intel-iotg, linux-intel-iotg-5.15).

Schaller: Fedora Workstation 40 – what are we working on

Pet, 03/29/2024 - 13:56
Christian Schaller writes about the desktop-oriented work aimed at the upcoming Fedora 40 release.

Another major feature landing in Fedora Workstation 40 that Jonas Ådahl and Ray Strode has spent a lot of effort on is finalizing the remote desktop support for GNOME on Wayland. So there has been support for remote connections for already logged in sessions already, but with these updates you can do the login remotely too and thus the session do not need to be started already on the remote machine. This work will also enable 3rd party solutions to do remote logins on Wayland systems, so while I am not at liberty to mention names, be on the lookout for more 3rd party Wayland remoting software becoming available this year.

[$] The race to replace Redis

Čet, 03/28/2024 - 21:31

On March 21, Redis Ltd. announced that the Redis "in-memory data store" project would now be released under non-free, source-available licenses, starting with Redis 7.4. The news is unwelcome, but not entirely unexpected. What is unusual with this situation is the number of Redis alternatives to choose from; there are at least four options to choose as a replacement for those who wish to stay with free software, including a pre-existing fork called KeyDB and the Linux Foundation's newly-announced Valkey project. The question now is which one(s) Linux distributions, users, and providers will choose to take its place.

[$] Declarative partitioning in PostgreSQL

Čet, 03/28/2024 - 16:34

Keith Fiske gave a talk (with slides) about the state of partitioning — splitting a large table into smaller tables for performance reasons — in PostgreSQL at SCALE this year. He spoke about the existing support for partitioning, what work still needs to be done, and what place existing partitioning tools, like his own pg_partman, still have as PostgreSQL gains more built-in features.

Samba 4.20.0 released

Čet, 03/28/2024 - 15:19
Version 4.20.0 of the Samba Windows interoperability suite has been released. Changes include better support for group-managed service accounts, an experimental Windows search protocol client, support for conditional access control entries, and more.
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