The OpenSSH project has released version 9.9. This version includes support for the new post-quantum cryptography standard from NIST. The release also includes the next step in the deprecation of DSA keys — they are now disabled by default at compile time, and are expected to be removed entirely in early 2025. The release also contains the normal mixture of bug fixes and small usability improvements.

Dirk Behme led a session discussing the use of Rust's question-mark operator in the kernel at Kangrejos 2024. He was particularly concerned with the concept of "silent" errors that don't print any messages to the console. Other attendees were less convinced that this was a problem, but his presentation sparked a lot of discussion about whether the Rust-for-Linux project could improve error handling in kernel Rust code.

Kangrejos 2024 started off with a talk from Benno Lossin about his recent work to establish a standard for safety documentation in Rust kernel code. Lossin began his talk by giving a brief review of what safety documentation is, and why it's needed, before moving on to the current status of his work. Safety documentation is easier to read and write when there's a shared vocabulary for discussing common requirements; Lossin wants to establish that shared vocabulary for Rust code in the Linux kernel.

Four researchers have published a formal proof that Linux's new deterministic random bit generator (DRBG) is secure in a particular sense — specifically, that the number of queries that would need to be made to it to uncover its internal state depends on the quality of the entropy it can collect from different sources. As long as it can gather enough entropy, it produces secure random numbers.

Since the significant structural changes in Linux 4 and Linux 5.17, there has been no research on the provable security of Linux-DRBG. For the first time (to the best of our knowledge), we formally model the Linux-DRBG in Linux 6.4.8 and prove its security in the seedless robustness model

Thanks to Jason Donenfeld for bringing the paper to our attention.

OpenSnitch is an "interactive application firewall". Like other firewalls, it uses a series of rules to decide what network traffic should be permitted. Unlike many other firewalls, though, OpenSnitch does not ask the user to create a list of rules ahead of time. Instead, the list of rules can be built up incrementally as applications make connections — and the user can peruse both the rules that have built up over time, and statistics on the connections that have been attempted.

On August 13, the US National Institute of Standards and Technology (NIST) published the final form of its new post-quantum cryptographic standards. One key-exchange mechanism and two digital-signature schemes are now officially sanctioned by the institute. Adopting the new standards should be fairly painless for most developers, but the overhead added by the schemes could pose challenges for some applications.

The Forgejo project has announced that, starting from version 9.0, Forgejo will be released under the GPLv3 license (or a later version). Older versions of the software forge remain MIT-licensed.

A copyleft license makes reusing other copyleft software easier. Recently, we discovered that some of the dependencies we used were incompatible with the license Forgejo was distributed with, and they had to be removed for now. Choosing copyleft licenses enables us to reuse more work, and saves us precious time to focus on improving Forgejo itself.

On July 30, Al Viro sent a patch set to the linux-fsdevel mailing list with a comprehensive cover letter explaining his recent work on ensuring that the kernel's internal representation of file descriptors are used correctly in the kernel. File descriptors are ubiquitous; many system calls need to handle them. Viro's review identified a few existing bugs, and may prevent more in the future. He also had suggestions for ways to keep uses consistent throughout the kernel.

Python has had formatted string literals (f-strings), a syntactic shorthand for building strings, since 2015. Recently, Jim Baker, Guido van Rossum, and Paul Everitt have proposed PEP 750 ("Tag Strings For Writing Domain-Specific Languages") which would generalize and expand that mechanism to provide Python library writers with additional flexibility. Reactions to the proposed change were somewhat positive, although there was a good deal of discussion of (and opposition to) the PEP's inclusion of lazy evaluation of template parameters.

Rust is intended to let programmers write safer code. But compilers are not omniscient, and writing Rust code that interfaces with hardware (or that works with memory outside of Rust's lifetime paradigm) requires, at some point, the programmer's assurance that some operations are permissible. Benno Lossin suggested adding some more documentation to the Rust-for-Linux project clarifying the standards for commenting uses of unsafe in kernel code. There's general agreement that such standards are necessary, but less agreement on exactly when it is appropriate to use unsafe.

The PostgreSQL project has released beta versions of PostgreSQL 17 containing several interesting security and usability improvements, alongside the usual performance improvements and bug fixes. If the release proceeds according to the usual timeline, the full release of version 17 is expected in September or October. The most important changes are in what PostgreSQL does when a database supervisor has their credentials revoked, and added support for incremental database backups.

Lix, the fork of Nix that LWN covered in July, has made its second release since forking. This one includes substantial changes to the backend code, including removing a dependency on Bison, and getting a change to the Nix language back upstream.

The general theme of Lix 2.91 is to perform another wave of refactorings and design improvements in preparation for our evolution plans.

Nevertheless, there are a few exciting user facing changes[.]

Researchers from Graz University of Technology have published details of a new attack on the Linux kernel called SLUBStick. The attack uses timing information to turn an ability to trigger use-after-free or double-free bugs into the ability to overwrite page tables, and thence into the ability to read and write arbitrary areas of memory. The good news is that this attack does require an existing bug to be usable; the bad news is that the kernel regularly sees bugs of this kind.

We assume that an unprivileged user has code execution. Additionally, we consider the presence of a heap vulnerability in the Linux kernel. We assume that the Linux kernel incorporates all defense mechanisms available in version 6.4, the most recent Linux kernel version when we started our work. These mechanisms include features such as WˆX, KASLR, SMAP, and kCFI. We do not assume any microarchitectural vulnerabilities, e.g., transient execution, fault injection, or hardware side channels.

Endless OS is a Linux distribution with a focus on improving access to educational tools by providing a simple-to-manage, full-featured desktop for educators and students — one that works offline, with minimal maintenance. The distribution also aims to be suitable for older devices, in order to promote access to computers by ensuring those systems remain usable. In pursuit of those goals, it makes some unusual technical choices. But what makes the distribution really shine is its curated collection of software and educational resources.

Mozilla has announced that Puppeteer, a browser automation and testing library, now has first-class support for Firefox using the WebDriver BiDi protocol. Puppeteer can be used to drive headless browser instances, and is commonly used for automated end-to-end web-site tests.

Whilst the features offered by Puppeteer won't be a surprise, bringing support to multiple browsers has been a significant undertaking. The Firefox support is not based on a Firefox-specific automation protocol, but on WebDriver BiDi, a cross browser protocol that's undergoing standardization at the W3C, and currently has implementation in both Gecko and Chromium. This use of a cross-browser protocol should make it much easier to support many different browsers going forward.