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The io_uring subsystem, first introduced in2019, has quickly become the leading way to perform high-bandwidth,asynchronous I/O. It has drawn the attention of many developers, including,more recently,those who are focused more on security than performance. Now some membersof the security community are lamenting a perceived lack of thought about security support inio_uring, and are trying to remedy that shortcoming by adding audit andLinux security module support there. That process is proving difficult,and has raised the prospect of an unpleasant fallback solution.

Greg Kroah-Hartman has announced the release of the 5.12.9, 5.10.42, 5.4.124, 4.19.193, 4.14.235, 4.9.271, and 4.4.271 stable kernels. As usual, thesecontain fixes throughout the kernel tree; users should upgrade.

Security updates have been issued by Arch Linux (chromium, curl, dhclient, dhcp, firefox, keycloak, lib32-curl, lib32-libcurl-compat, lib32-libcurl-gnutls, libcurl-compat, libcurl-gnutls, opera, packagekit, pam-u2f, postgresql, rabbitmq, redis, ruby-bundler, and zint), Debian (caribou, firefox-esr, imagemagick, and isc-dhcp), Fedora (mapserver, mingw-python-pillow, and python-pillow), openSUSE (chromium), Red Hat (firefox, glib2, pki-core:10.6, polkit, rh-ruby26-ruby, and rh-ruby27-ruby), SUSE (ceph, dhcp, libwebp, nginx, qemu, squid, and xstream), and Ubuntu (firefox, linux, linux-aws, linux-aws-hwe, linux-azure, linux-azure-4.15, linux-gcp, linux-gcp-4.15, linux-hwe, linux-kvm, linux-oracle, linux-snapdragon, linux, linux-aws, linux-azure, linux-gcp, linux-kvm, linux-oracle, and policykit-1).

The LWN.net Weekly Edition for June 3, 2021 is available.

When last we looked in on Fedora CoreOS back in December,it was under consideration to become an official Fedora edition. That hasnot happened, yet at least, but it would seem that the CoreOS "emerging edition"is still undergoing some difficulties trying to fit in with the rest ofFedora. There are differences between the needs of a container operatingsystem and those of more general-purpose distributions, which still need tobe worked out if Fedora CoreOS is going to "graduate".

Robert McQueen takesa look at the state of the GNOME Foundation.

Security updates have been issued by Debian (squid), Fedora (dhcp), openSUSE (gstreamer, gstreamer-plugins-bad, gstreamer-plugins-base, gstreamer-plugins-good, gstreamer-plugins-ugly and slurm), Oracle (glib2 and kernel), Red Hat (kernel, kernel-rt, perl, and tcpdump), Scientific Linux (glib2), SUSE (bind, dhcp, lz4, and shim), and Ubuntu (dnsmasq, lasso, and python-django).

OpenSUSELeap 15.3 has been released. "There is one huge change from theprevious Leap versions. openSUSE Leap 15.3 is built not just from SUSELinux Enterprise source code like in previous versions, but built with theexact same binary packages, which strengthens the flow between Leap and SLElike a yin yang." There are a lot of new features as well, see theannouncement for details.

Matthew Garrett has written up the long,complex series of steps required to build an x86 device that only bootscode that the creator wants to run there. "At this point everythingin the boot process is cryptographically verified, and so should bedifficult to tamper with. Unfortunately this isn't really sufficient - onx86 systems there's typically no verification of the integrity of thesecure boot database. An attacker with physical access to the system couldattach a programmer directly to the firmware flash and rewrite the secureboot database to include keys they control. They could then replace theboot image with one that they've signed, and the machine would happily bootcode that the attacker controlled. We need to be able to demonstrate thatthe system booted using the correct secure boot keys, and the only way wecan do that is to use the TPM."

Over the last month or so, there has been a good bit of newssurrounding the idea of increasing the performance of the CPythoninterpreter. At the 2021Python Language Summit in mid-May, Guido van Rossum announcedthat he and a small team are being funded by Microsoft to work with thecommunity on getting performance improvements upstream into theinterpreter—crucially, without breaking the C API so that the ecosystem ofPython extensions (e.g. NumPy) continue towork. Another talk at the summit lookedat Cinder, which is a performance-oriented CPython fork that is used inproduction at Instagram. Cinder was recently released as open-sourcesoftware, as was anotherproject to speed up CPython that originated at Dropbox: Pyston.

The GCC Steering Committee has decided torelax the requirement to assign copyright to the Free SoftwareFoundation. "Contributors who have an FSF Copyright Assignment don'tneed to change anything. Contributors who wish to utilize the DeveloperCertificate of Origin should add a Signed-off-by message to their commitmessages. Developers with commit access may add their name to the DCO listin the MAINTAINERS file to certify the DCO for all future commits in lieuof individual Signed-off-by messages for each commit."

Firefox 89 has been released. Thechanges in this version focus on the look and feel. "We’ve redesignedand modernized the core experience to be cleaner, more inviting, and easierto use. " This release also includes enhancements to the privacyofferings. "We’veenhanced the privacy of the Firefox Browser’s Private Browsing modewith Total Cookie Protection, which confines cookies to the site where theywere created, preventing companies from using cookies to track your browsing across sites. This feature was originally launched in Firefox’s ETP Strict mode."

Security updates have been issued by Fedora (cflow, chromium, eterm, gnutls, and kernel), Mageia (kernel and kernel-linus), Oracle (glib2), Red Hat (glib2, kernel, kernel-rt, and kpatch-patch), SUSE (curl, djvulibre, gstreamer, gstreamer-plugins-bad, gstreamer-plugins-base, gstreamer-plugins-good, gstreamer-plugins-ugly, nginx, python-httplib2, and slurm), and Ubuntu (gupnp, libwebp, postgresql-10, postgresql-12, postgresql-13, and python3.8).

The GCC compiler, like other GNU projects, has long required contributorsto complete paperwork assigning the copyrights on their work to the FreeSoftware Foundation. That requirement has just been dropped, andcontributors can now attach a Signed-off-by tag indicating use of theDevelopers Certificate ofOrigin instead. "This change is consistent withthe practices of many other major Free Software projects, such as theLinux kernel." Initial discussionsuggests that some developers were surprised by this change and are yet to be convinced that it is a goodidea.

The seccomp()mechanism allows a process to load a BPF program to restrict its future useof system calls; it is a simple but flexible sandboxing mechanism that iswidely used. Those filter programs, though, run on the "classic" BPF virtualmachine, rather than the extended BPF(eBPF) machine used elsewhere in the kernel. Moving seccomp() to eBPF has been an often-requestedchange, but security concerns have prevented that from happening. Thelatest attempt to enable eBPF is this patchset from YiFei Zhu; whether it will succeed where others have failedremains to be seen.

Security updates have been issued by Debian (hyperkitty, libxml2, nginx, openjdk-11-jre-dcevm, rxvt-unicode, samba, and webkit2gtk), Fedora (exiv2, java-1.8.0-openjdk-aarch32, mingw-python-pillow, opendmarc, php-symfony3, php-symfony4, python-pillow, runc, rust-cranelift-codegen-shared, rust-cranelift-entity, and rxvt-unicode), openSUSE (curl, hivex, libu2f-host, libX11, libxls, singularity, and upx), Oracle (dotnet3.1 and dotnet5.0), Red Hat (docker, glib2, and runc), and Ubuntu (lz4).

The fourth 5.13 kernel prepatch is out fortesting. "So after two small rc releases, the other shoe finallydropped, and rc4 is fairly sizable."

AlmaLinux 8.4, a clone of RHEL filling the role that CentOS used toplay, has been released. Changes include full support for secure boot, adeveloper repository with packages not found in RHEL, and more; see the releasenotes for details.

Modern computing systems can feature multiple types of memory that differ intheir performance characteristics. The most common example is NUMAarchitectures, where memory attached to the local node is faster to accessthan memory on other nodes. Recently, persistent memory hasstarted appearing in deployed systems as well; this type of memory isbyte-addressable like DRAM, but it is available in larger sizes and is slower toaccess, especially for writes. This new memory type makes memory allocation even more complicatedfor the kernel, driving the need for a method to better manage multiple types ofmemory in one system.

The 5.12.8, 5.10.41, and 5.4.123 stable kernels have been released.These contain only a small handful of changes, including fixes to the BPFverifier to address a privilegeescalation vulnerability. Users of those series should upgrade.

Security updates have been issued by Debian (nginx), Fedora (chromium, curl, kernel, php-symfony3, php-symfony4, python-lxml, python-pip, and runc), Mageia (ceph and wireshark), openSUSE (mpv), Oracle (bind, idm:DL1, redis:6, slapi-nis, squid:4, and xorg-x11-server), SUSE (curl, nginx, postgresql10, postgresql12, postgresql13, slurm, slurm_18_08, and slurm_20_11), and Ubuntu (nginx).

Over on the Python Software Foundation blog, the reports from day 1 of the Python Language Summit are available. At the time of this writing, a few from day 2 are ready as well. There are lots of interesting topics discussed at the summit, including a talk on making CPython faster from Python creator Guido van Rossum. "Seven months ago, Guido van Rossum left a brief retirement to work at Microsoft. He was given the freedom to pick a project and decided to work on making CPython faster. Microsoft will be funding a small team consisting of Guido van Rossum, Mark Shannon, Eric Snow, and possibly others. [...] The team is optimistic about doubling CPython's speed for 3.11. They plan to try an adaptive, specializing byte code interpreter, which is a bit like the existing inline cache and a bit like the shadow byte code covered in Dino Viehland's talk." Some of the ideas go back to Shannon's thoughts on speeding up the interpreter that we looked at back in December.

When kernel developers want to communicate something about the state of arunning kernel, they tend to use printk(); that results in a logentry that is intended — with varying success — to be human-readable. As ithappens, though, theconsumers of that information are often not human; the kernel's log outputis also read by automated monitoring systems that are looking forproblems. The result is an impedance mismatch that often ends with themonitoring system missing important messages. The printk()format indexing patch set is the latest of many attempts to improvethis situation.

Security updates have been issued by Debian (djvulibre), Fedora (slapi-nis and upx), Gentoo (ceph and nginx), openSUSE (python-httplib2 and rubygem-actionpack-5_1), Slackware (curl), SUSE (curl, libX11, and python-httplib2), and Ubuntu (isc-dhcp, lz4, and nginx).

The LWN.net Weekly Edition for May 27, 2021 is available.

Internet RelayChat (IRC) is a longstanding protocol—or series of protocols—forcreating online,text-based chat rooms.While many of the "channels" (as chat rooms are usually called) are highly useful toa wide variety of projects and organizations, including much of thefree-software world,IRC seems to have a community that suffers frommore than its fair share of disagreements, hostile forks, vitriol, and other types ofdivisiveness. It is perhaps no huge surprise, then, that the IRCworld is currently undergoing another of its periodic upheavals. Thelargest IRC network, freenode, isembroiled in a messy dispute that has ledto the mass resignationof many of its volunteer staff, the founding of a competitor network (run by the former staff),and its abandonment by multiple high-profile projects.

Stable kernels 5.12.7, 5.10.40, 5.4.122, 4.19.192, 4.14.234, 4.9.270, and 4.4.270 have been released. As usual, theycontain important fixes and users should upgrade.

Security updates have been issued by Arch Linux (djvulibre, dotnet-runtime, dotnet-runtime-3.1, dotnet-sdk, dotnet-sdk-3.1, gupnp, hivex, lz4, matrix-synapse, prometheus, python-pydantic, runc, thunderbird, and websvn), Fedora (composer, moodle, and wordpress), Gentoo (bash, boost, busybox, containerd, curl, dnsmasq, ffmpeg, firejail, gnome-autoar, gptfdisk, icu, lcms, libX11, mariadb, mumble, mupdf, mutt, mysql, nettle, nextcloud-client, opensmtpd, openssh, openvpn, php, postgresql, prosody, rxvt-unicode, samba, screen, smarty, spamassassin, squid, stunnel, tar, tcpreplay, and telegram-desktop), openSUSE (Botan), Red Hat (kernel), Slackware (gnutls), SUSE (hivex, libu2f-host, and rubygem-actionpack-5_1), and Ubuntu (apport, exiv2, and libx11).

Version 3.0 ofMagit, a Git interface that runs inside emacs, has been released. "The big change are the completely reworked menus used to selectarguments and invoke suffix commands. Magit now uses the Transient package toimplement these menus." See the releasenotes for more details.

On March 24, version 1.6.0 of the Juliaprogramming language was released. This is thefirst feature release since 1.0 came out in 2018. The new releasesignificantly reduces the "time to first plot", which is a common source ofdissatisfaction for newcomers to the language, by parallelizingpre-compilation, downloading packages more efficiently, and reducing thefrequency of just-in-time re-compilations at run time.

Security updates have been issued by Fedora (python-eventlet), openSUSE (grub2 and mpv), and Red Hat (kpatch-patch and rh-ruby25-ruby).

Version1.1 of the Inkscape vector image editor has been released."Among the highlights in Inkscape 1.1 are a Welcome dialog, a CommandPalette, a revamped Dialog Docking System, and searchable preferenceoptions, along with new formats for exporting your work."

The multi-generational LRU patch set is a significant reworking of thekernel's memory-management subsystem that promises better performance for anumber of workloads; it was covered here inApril. Since then, two new versions of that work have been released bydeveloper Yu Zhao, withversion 3being posted on May 20. Some significant changes have been made sincethe original post, so another look is in order.

Security updates have been issued by Debian (libx11, prosody, and ring), Fedora (ceph, glibc, kernel, libxml2, python-pip, slurm, and tpm2-tss), Mageia (bind, libx11, mediawiki, openjpeg2, postgresql, and thunderbird), openSUSE (Botan, cacti, cacti-spine, chromium, djvulibre, fribidi, graphviz, java-1_8_0-openj9, kernel, libass, libxml2, lz4, and python-httplib2), and Slackware (expat).

The third 5.13 kernel prepatch is out fortesting. "It's been a very calm rc3 week, and at least in purenumber of commits this is the smallest rc3 we've had in the 5.xseries.Considering that the merge window was not in any way small, this is abit surprising, but I suspect it's one of those 'not everybody sent infixes this week' things that will rectify itself next week."This prepatch does include reverts and fixes for a long series of brokenpatches identified in the TAB report on the UMNmess.

The5.12.6,5.10.39,5.4.121,4.19.191,4.14.233,4.9.269, and4.4.269stable kernels have all been released; each contains yet another set ofimportant fixes.

In 2018, LWN covered a talk by GernotHeiser about the seL4 project, which has developed an open-sourceoperating system for safety-critical applications and gone to the troubleof proving its correctness. Much of that work has been done at CSIRO inAustralia. Heiser has announcedvia Twitter that CSIRO's support for this project is being shut down, withthe staff being redirected to artificial-intelligence projects. Hopefully the seL4 Foundation, established in2020, will be able to carry on this interesting work.

Version 5.34.0 of the Perl language has been released."Perl 5.34.0 represents approximately 11 months of development sincePerl 5.32.0 and contains approximately 280,000 lines of changes across2,100 files from 78 authors." See thispage for a list of changes; they include a new try/catch syntax, a newoctal syntax, and many improvements to various modules.

Among the many changes merged for the 5.13 kernel is support for the LLVMcontrol-flow integrity (CFI) mechanism. CFI defends against exploits byensuring that indirect function calls have not been redirected by anattacker. Quite a bit of work was needed to make this feature work wellfor the kernel, but the result appears to be production-ready and able todefend Linux systems from a range of attacks.

Security updates have been issued by Arch Linux (ceph, chromium, firefox, gitlab, hedgedoc, keycloak, libx11, mariadb, opendmarc, prosody, python-babel, python-flask-security-too, redmine, squid, and vivaldi), Debian (lz4), Fedora (ceph and python-pydantic), and openSUSE (cacti, cacti-spine).

The RISC-V CPU architecture has beengaining prominence for some years; its relatively open nature makes it anattractive platform on which a number of companies have built products.Linux supportsRISC-V well, but there is one gaping hole: there is no support forvirtualization with KVM,despite the fact that a high-quality implementation exists. A recent attempt to add that support is shiningsome light on a part of the ecosystem that, it seems, does not work quiteas wellas one would like.

Security updates have been issued by Fedora (cacti, cacti-spine, exif, firefox, kernel, mariadb, and thunderbird), Mageia (kernel, kernel-linus, and libxml2), openSUSE (exim and jhead), Oracle (slapi-nis and xorg-x11-server), Scientific Linux (slapi-nis and xorg-x11-server), Slackware (libX11), SUSE (djvulibre, fribidi, graphviz, grub2, libass, libxml2, lz4, python-httplib2, redis, rubygem-actionpack-4_2, and xen), and Ubuntu (pillow and python-babel).

The LWN.net Weekly Edition for May 20, 2021 is available.

May 11 marked a new major release for the Python-based Flask webmicroframework project, but Flask 2.0was only part of the story. While the framework may be the most visiblepiece, it is one of a small handful of cooperating libraries that providesolutions for various web-development tasks; all are incorporated into the Pallets projects organization. Forthe first time, allsix libraries that make up Pallets were released at the same time andeach had a new major version number. In part, that new major versionindicated that Python 2 support was being left behind, but there isplenty more that went into the coordinated release.

Stable kernels 5.12.5, 5.11.22, 5.10.38, and 5.4.120 have been released. This is the last5.11.y kernel and users should move to 5.12.y at this time.

Security updates have been issued by Fedora (cacti, cacti-spine, exif, and hivex), Red Hat (bash, bind, bluez, brotli, container-tools:rhel8, cpio, curl, dotnet3.1, dotnet5.0, dovecot, evolution, exiv2, freerdp, ghostscript, glibc, GNOME, go-toolset:rhel8, grafana, gssdp and gupnp, httpd:2.4, idm:DL1, idm:DL1 and idm:client, ipa, kernel, kernel-rt, krb5, libdb, libvncserver, libxml2, linux-firmware, mailman:2.1, mingw packages, NetworkManager and libnma, opensc, p11-kit, pandoc, perl, pki-core:10.6 and pki-deps:10.6, poppler and evince, python-cryptography, python-lxml, python-urllib3, python27:2.7, python3, python38:3.8, qt5-qtbase, raptor2, redis:6, rh-mariadb103-mariadb and rh-mariadb103-galera, rust-toolset:rhel8, samba, sane-backends, shim, slapi-nis, spice, spice-vdagent, sqlite, squid:4, sudo, systemd, tigervnc, trousers, unbound, userspace graphics, xorg-x11, and mesa, virt:rhel and virt-devel:rhel, wpa_supplicant, and xorg-x11-server), SUSE (kernel), and Ubuntu (djvulibre, gst-plugins-base1.0, linux-raspi, linux-raspi-5.4, python-pip, and runc).

Several readers have alerted us to some serious problems at freenode, which runs an IRC network thatis popular in the free-software world. Evidently there has been a changeof control within the volunteer-run organization that has led to theresignations of multiple different volunteers, at least in part dueto a concern about the personal information of freenode users under the newmanagement. "Thefreenode resignation FAQ" has collected a bunch of information (andlinks to even more resignation letters) that may help shed some light on this mess.From the FAQ: "Freenode staff have stepped down. The network thatruns at freenode.org/net/com should now be assumed to be under control of amalicious party."In the meantime, many of the volunteers who resigned have formed Libera.Chat to continue the legacy offreenode. LWN will be keeping an eye on the situation, stay tuned ...

Control groups (cgroups) are meant to limit access to a shared resource amongprocesses in the system. One such resource is the values used to specifyan encrypted-memory region for a virtual machine, such as the address-spaceidentifiers (ASIDs) used by the AMD SecureEncrypted Virtualization (SEV) feature. Vipin Sharma setout to add a control group for these ASIDs back in September; based on the feedback,though, he expanded the idea into a controller to track and limit any countable resource.The patch set became the controllerfor the misc control group and has been merged for Linux 5.13.

The Mozilla Security Blog announcesthat there is a new site-isolation mechanism available for testing in theFirefox browser. It's a defense against Meltdown and Spectre exploits.

Security updates have been issued by Debian (chromium, curl, prosody, and ruby-rack-cors), Fedora (dotnet3.1 and dotnet5.0), openSUSE (ibsim and prosody), SUSE (kernel and python3), and Ubuntu (caribou and djvulibre).