Brief items

Privacy analysis of FLoC (Mozilla blog)

Over on the Mozilla blog, Eric Rescorla looks into some of the privacy implications of the Federated Learning of Cohorts (FLoC), which is a Google effort to replace third-party cookies with a different type of identifier that is less trackable. But less tracking does not equal no tracking. "People's interests aren't constant and neither are their FLoC IDs. Currently, FLoC IDs seem to be recomputed every week or so. This means that if a tracker is able to use other information to link up user visits over time, they can use the combination of FLoC IDs in week 1, week 2, etc. to distinguish individual users. This is a particular concern because it works even with modern anti-tracking mechanisms such as Firefox's Total Cookie Protection (TCP). TCP is intended to prevent trackers from correlating visits across sites but not multiple visits to one site. FLoC restores cross-site tracking even if users have TCP enabled."

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Google's fully homomorphic encryption package

The Google Developers Blog has this announcement describing the release of a fully homomorphic encryption project under the Apache license. "With FHE, encrypted data can travel across the Internet to a server, where it can be processed without being decrypted. Google’s transpiler will enable developers to write code for any type of basic computation such as simple string processing or math, and run it on encrypted data. The transpiler will transform that code into a version that can run on encrypted data. This then allows developers to create new programming applications that don’t need unencrypted data." See this white paper for more details on how it all works.

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Privilege escalation with polkit: How to get root on Linux with a seven-year-old bug (GitHub blog)

On the GitHub blog, Kevin Backhouse writes about a privilege escalation vulnerability in polkit, which "enables an unprivileged local user to get a root shell on the system" CVE-2021-3560 "is triggered by starting a dbus-send command but killing it while polkit is still in the middle of processing the request. [...] Why does killing the dbus-send command cause an authentication bypass? The vulnerability is in step four of the sequence of events listed above. What happens if polkit asks dbus-daemon for the UID of connection :1.96, but connection :1.96 no longer exists? dbus-daemon handles that situation correctly and returns an error. But it turns out that polkit does not handle that error correctly. In fact, polkit mishandles the error in a particularly unfortunate way: rather than rejecting the request, it treats the request as though it came from a process with UID 0. In other words, it immediately authorizes the request because it thinks the request has come from a root process."

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Kernel release status

The current development kernel is 5.13-rc6, released on June 13. Linus said: "Nothing particularly special to say about this - rc6 is certainly smaller than rc5 was, so we're moving in the right direction".

Stable updates: 5.12.10, 5.10.43, 5.4.125, 4.19.194, 4.14.236, 4.9.272, and 4.4.272 were released on June 10, followed by 5.12.11, 5.10.44, 5.4.126, 4.19.195, 4.14.237, 4.9.273, and 4.4.273 on June 16. Not content with those, Greg Kroah-Hartman has started the review process for 5.12.12, 5.10.45, and 5.4.127; they are due on June 18.

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Aya: writing BPF in Rust

The first release of the Aya BPF library has been announced; this project allows the writing of BPF programs in the Rust language. "Over the last year I've talked with many folks interested in using eBPF in the Rust community. My goal is to get as many of you involved in the project as possible! Now that the rustc target has been merged, it's time to build a solid foundation so that we can enable developers to write great eBPF enabled apps".

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linux.dev mailboxes for kernel developers

Konstantin Ryabitsev has announced a new service providing @linux.dev mailboxes for people to use with kernel development. The documentation page has more information. "This is a BETA offering. Currently, it is only available to people listed in the MAINTAINERS file. We hope to be able to offer it to everyone else who can demonstrate an ongoing history of contributions to the Linux kernel (patches, git commits, mailing list discussions, etc)."

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Distribution quote of the week

I've been saying for years that as more and more consumers who just want a device which gives them those tools without a hassle move to just working on their phones and tablets, the share of Linux among people who actually want a computer will go up, and I think we're definitely seeing that among programmers, engineers, students, and gamers. Will that translate eventually to the general public? Maybe not, but that's okay. World domination isn't the only definition of success.

— Matthew Miller

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A possible copyright-policy change for glibc

The GNU C Library developers are asking for comments on a proposal to stop requiring developers to assign their copyrights to the Free Software Foundation. This mirrors the recent change by GCC, except that the community is being consulted first. "The changes to accept patches with or without FSF copyright assignment would be effective on August 2nd, and would apply to all open branches. The glibc stewards, like the GCC SC, continue to affirm the principles of Free Software, and that will never change."

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FSFE: REUSE Booster helps Free Software projects with licensing and copyright

The Free Software Foundation Europe introduces REUSE Booster. REUSE is a set of best practices to make Free Software licensing easier. "With REUSE Booster, we go one step further. We invite Free Software projects to register for getting help by the FSFE's legal experts. As the name suggests, this will boost the process of adopting the best practices as well as general understanding of licensing and copyright." The registration deadline is July 8.

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Poettering: The Wondrous World of Discoverable GPT Disk Images

In a lengthy blog post, Lennart Poettering describes the advantages of using the unique IDs (UUIDs) and flags from the discoverable partitions specification to label the entries in a GUID Partition Table (GPT). That information can be used to tag disk images in a self-descriptive way, so that external configuration files (such as /etc/fstab) are not needed to assemble the filesystems for the running system. Systemd can use this information in a variety of ways, including for running the image in a container: "If a disk image follows the Discoverable Partition Specification then systemd-nspawn has all it needs to just boot it up. Specifically, if you have a GPT disk image in a file foobar.raw and you want to boot it up in a container, just run systemd-nspawn -i foobar.raw -b, and that's it (you can specify a block device like /dev/sdb too if you like). It becomes easy and natural to prepare disk images that can be booted either on a physical machine, inside a virtual machine manager or inside such a container manager: the necessary meta-information is included in the image, easily accessible before actually looking into its file systems."

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Development quote of the week

The Google researchers examining these silent corrupt execution errors (CEEs) concluded "mercurial cores" were to blame – CPUs that miscalculated occasionally, under different circumstances, in a way that defied prediction. (That's mercurial as in unpredictable, not Mercurial as in the version control system of the same name.)

The errors were not the result of chip architecture design missteps, and they're not detected during manufacturing tests. Rather, Google engineers theorize, the errors have arisen because we've pushed semiconductor manufacturing to a point where failures have become more frequent and we lack the tools to identify them in advance.

— The Register (Thanks to Jörg Sommer)

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