lwn.net

The Mozilla project celebrates 25 years of existence.

A lot has changed since 1998. Mozilla is no longer just a bold idea. We’re a family of organizations — a nonprofit, a public benefit-corporation, and others — that builds products, fuels movements, and invests in responsible tech.

And we’re no longer a small group of engineers in Netscape’s Mountain View office. We’re technologists, researchers, and activists located around the globe — not to mention tens of thousands of volunteers.

But if a Mozillian from 1998 stepped into a Mozilla office (or joined a Mozilla video call) in 2023, I think they’d quickly feel something recognizable. A familiar spirit, and a familiar set of values.

As a general rule, the purpose behind mounting a filesystem is to make that filesystem's contents visible to the system, or at least to the mount namespace where that mount occurs. For similar reasons, it is unusual to mount one filesystem on top of another, since that would cause the contents of the over-mounted filesystem to be hidden. There are exceptions to everything, though, and that extends to mounted filesystems; a "tucking" mechanism proposed by Christian Brauner is designed to hide mounted filesystems underneath other mounts — temporarily, at least.

Security updates have been issued by Debian (joblib, json-smart, libmicrohttpd, and xrdp), Fedora (thunderbird and xorg-x11-server-Xwayland), Mageia (dino, perl-Cpanel-JSON-XS, perl-Net-Server, snort, tigervnc/x11-server, and xapian), SUSE (curl, kernel, openssl-1_0_0, and shim), and Ubuntu (glusterfs, linux-gcp-4.15, musl, and xcftools).

The X.Org project has announced a vulnerability in its X server and Xwayland (CVE-2023-1393). This issue can lead to local privileges elevation on systems where the X server is running privileged and remote code execution for ssh X forwarding sessions.

[...] If a client explicitly destroys the compositor overlay window (aka COW), the Xserver would leave a dangling pointer to that window in the CompScreen structure, which will trigger a use-after-free later.

That has led to the release of xorg-server 21.1.8, xwayland 22.1.9, and xwayland 23.1.1.

The kernel's hierarchical maintainer model works quite well from the standpoint of allowing thousands of developers to work together without (often) stepping on each others' toes. But that model can also make life painful for developers who are trying to make changes across numerous subsystems. Other possible source of pain include changes related to licensing or those where maintainers don't understand the purpose of the work. Nick Alcock has managed to hit all of those hazards together in his effort to perform what would seem like a common-sense cleanup of the kernel's annotations for loadable modules.

Greg Kroah-Hartman has announced the release of the 6.2.9, 6.1.22, 5.15.105, and 5.4.239 stable kernels. The latter (5.4.239) has single patch to fix the permissions of a selftest file, while the other three have a lengthy list of important fixes throughout the kernel tree.

Security updates have been issued by Debian (xorg-server and xrdp), Fedora (mingw-python-certifi, mingw-python3, mingw-zstd, moodle, python-cairosvg, python-markdown-it-py, redis, xorg-x11-server, and yarnpkg), Slackware (mozilla and xorg), SUSE (grub2, ldb, samba, libmicrohttpd, python-Werkzeug, rubygem-rack, samba, sudo, testng, tomcat, webkit2gtk3, xorg-x11-server, xstream, and zstd), and Ubuntu (linux, linux-aws, linux-dell300x, linux-kvm, linux-oracle, linux-raspi2, linux-aws-5.4, linux-azure-5.4, linux-gcp-5.4, linux-hwe-5.4, linux-ibm-5.4, linux-oracle-5.4, linux-raspi-5.4, linux-gke, linux-gke-5.15, linux-ibm, linux-kvm, php-nette, and xorg-server, xorg-server-hwe-18.04, xwayland).

The LWN.net Weekly Edition for March 30, 2023 is available.

The fourth and final keynote for Everything Open 2023 was given by Professor Rebecca Giblin of the Melbourne Law School, University of Melbourne. It revolved around her recent book, Chokepoint Capitalism, which she wrote with Cory Doctorow; it is "a book about why creative labor markets are rigged — and how to unrig them". Giblin had planned to be in Melbourne to give her talk in person, but "the universe had other plans"; she got delayed in Austin, Texas by an unexpected speaking slot at the South by Southwest (SXSW) conference, so she gave her talk via videoconference from there—at nearly midnight in Austin.

Immutable Linux distributions are on the rise recently, with multiple popular distributions creating their own immutable versions.; it could be one of the trends of 2023, as predicted. While many of these immutable distributions are focused on server use, there are also some that offer a desktop experience. OpenSUSE MicroOS Desktop is one of them, with a minimal openSUSE Tumbleweed as the base operating system and applications running as Flatpaks or in containers. In its daily use, it feels a lot like a normal openSUSE desktop. Its biggest benefit is availability of the newest software releases without sacrificing system stability.

Curl maintainer Daniel Stenberg expresses some frustrations with the vulnerability notification policies maintained by the distros mailing list.

The week before we were about to ship the curl 8.0.0 release, I emailed the distros mailing list again like I have done so many times before and told them about the upcoming six(!) vulnerabilities we were about to reveal to the world.

This time turned out to be different.

Because of our updated policy where the fixes were already committed in a public git repository, the distros mailing list’s policy says that if there is a public commit they consider the issue to be public and thus they refuse to accept any embargo.

What they call embargo I of course call heads-up time.

The kernel project has run into similar issues in the past.

Security updates have been issued by Debian (unbound and xorg-server), Fedora (stellarium), Oracle (kernel), SUSE (apache2, oracleasm, python-Werkzeug, rubygem-loofah, sudo, and tomcat), and Ubuntu (git, kernel, and linux-hwe-5.19).

Canonical recently announced that it will no longer ship Flatpak as part of its default installation for the various official Ubuntu flavors, which is in keeping with the practices of the core Ubuntu distribution. The Flatpak package format has gained popularity among Linux users for its convenience and ease of use. Canonical will focus exclusively on its own package-management system, Snap. The decision has caused disgruntlement among some community members, who felt like the distribution was making this decision without regard for its users.

Security updates have been issued by Debian (dino-im and runc), Fedora (qemu), Red Hat (firefox), SUSE (chromium, containerd, docker, kernel, and systemd), and Ubuntu (graphicsmagick, linux-azure, linux-gcp, linux-oem-5.14, linux-oem-5.17, linux-oem-6.0, linux-oem-6.1, and node-url-parse).

The open() system call offers a number of flags that modify its behavior; not all combinations of those flags make sense in a single call. It turns out, though, that the kernel has responded in a surprising way to the combination of O_CREAT and O_DIRECTORY for a long time. After a 2020 change made that response even more surprising, it seems likely that this behavior will soon be fixed, resulting in a rare user-visible semantic change to a core system call.

Version 5.0 of the GnuCash accounting tool is out. Changes include a number of investment-tracking improvements, better completion in the register window, a reworked report-generation system, and more.

Security updates have been issued by Debian (libreoffice and xen), Fedora (chromium, curl, and xen), Red Hat (kernel, kernel-rt, kpatch-patch, and thunderbird), Scientific Linux (thunderbird), Slackware (tar), SUSE (apache2, ceph, curl, dpdk, helm, libgit2, and php7), and Ubuntu (firefox and thunderbird).

Linus has released 6.3-rc4 for testing. "Things are looking pretty normal for this time of the release process."

Matthew Garrett looks at the recent disclosure of GitHub's private host key, how it probably came about, and what a better approach to key management might look like.

The main problem is that client tooling just doesn't handle this well. OpenSSH has no way to do TOFU for CAs, just the keys themselves. This means there's no way to do a git clone ssh://git@github.com/whatever and get a prompt asking you to trust Github's CA. Instead, you need to add a @cert-authority github.com (key) line to your known_hosts file by hand, and since approximately nobody's going to do that there's only marginal benefit in going to the effort to implement this infrastructure. The most important thing we can do to improve the security of the SSH ecosystem is to make it easier to use certificates, and that means improving the behaviour of the clients.

Support for shadow stacks on the x86 architecture has been long in coming; LWN first covered this work in 2018. After five years and numerous versions, though, it would appear that user-space shadow stacks on x86 might just be supported in the 6.4 kernel release. Getting there has required a few changes since we last caught up with this work in early 2022.