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The LWN.net Weekly Edition for January 9, 2020 is available.

One of Guido van Rossum's last items of business as he finished his term on the inaugural steering council for Python was toreview the Python Enhancement Proposal (PEP) that proposes a new update and unionoperators for dictionaries. He would still seem to be in favor of the idea,but it will be up to the newly elected steeringcouncil and whoever the council chooses as the PEP-deciding delegate (i.e. BDFL-Delegate).Van Rossum provided some feedback on the PEP and, inevitably, the question of how to spell the operator returned, but thepath toward getting a decision on it is now pretty clear.

Security updates have been issued by Arch Linux (firefox), Debian (python-django and wordpress), Fedora (dovecot), Mageia (opensc, radare2, and varnish), Red Hat (rh-java-common-apache-commons-beanutils), SUSE (containerd, docker, docker-runc, golang-github-docker-libnetwork, java-1_8_0-ibm, java-1_8_0-openjdk, libzypp, openssl-1_0_0, sysstat, and tomcat), and Ubuntu (clamav, linux-azure, and linux-lts-xenial, linux-aws).

It has taken longer than anybody might have liked, but the IPv6 protocol isslowly displacing IPv4 across the Internet. A quick, highly scientific"grep the access logs" test shows that about 16% of the traffic toLWN.net is currently using IPv6, and many large corporate networks areusing IPv6 exclusively internally. This version of the IP protocol wasdesigned to be more flexible than IPv4 in a number of ways; the "extensionheader" mechanism is one way in which that flexibility is achieved. Aproposal to formalize extension-header processing in the kernel'snetworking stack has led to some concerns, though, about how this featurewill be used and what role Linux should play in its development.

Lars Ingebrigtsen providesdetails on the current status of the Gmane archive server and asks forfeedback on whether it is still useful. "Over the past few years,people have asked me what happened to Gmane, and I’ve mostly clasped myhands over my ears and gone 'la la la can’t hear you', because there’snothing about the story I’m now finally going to tell that I don’t findhighly embarrassing. I had hoped I could just continue that way until Idie, but perhaps it would be more constructive to actually tell peoplewhat’s going on instead of doing an ostrich impression." (Thanks toGiovanni Gherdovich).

Firefox 72.0 has been released. In this version Firefox’s EnhancedTracking Protection now blocks fingerprintingscripts. Also picture-in-picture video is available. See the releasenotes for the details of these features and other changes.

Security updates have been issued by Debian (nss and pillow), Red Hat (java-1.8.0-ibm and kernel), Slackware (firefox), SUSE (virglrenderer), and Ubuntu (linux, linux-aws, linux-aws-5.0, linux-azure, linux-gcp, linux-gke-5.0, linux-kvm, linux-oem-osp1, linux-oracle, linux-oracle-5.0, linux-raspi2, linux, linux-aws, linux-kvm, linux-raspi2, linux-snapdragon, linux-kvm, linux-oracle, linux-raspi2, and linux-snapdragon).

The random-number generation facilities in the kernel have been reworkedsome over the past few months—but problems in that subsystem have beenaddressed over an even longer time frame. The most recent changes were made to stop the getrandom() system call fromblocking for long periods of time at system boot, but the underlying causewas the behavior of the blocking random pool. A recent patch set wouldremove that pool and it would seem to be headed for the mainline kernel.

Security updates have been issued by Fedora (chromium, cyrus-imapd, drupal7-l10n_update, drupal7-webform, htmldoc, nethack, php, and singularity), Mageia (advancecomp, apache-commons-compress, cyrus-imapd, cyrus-sasl, dia, freeimage, freeradius, igraph, jhead, jss, libdwarf, libextractor, libxml2, mediawiki, memcached, mozjs60, openconnect, openssl, putty, python-ecdsa, python-werkzeug, shadowsocks-libev, and upx), Oracle (container-tools:1.0 and container-tools:ol8), and Red Hat (kpatch-patch).

The 5.5-rc5 kernel prepatch has beenreleased. Linus added a note to the release announcement: "One sadpiece of news I got this past week was that Bruce Evans has passed away. Bruce wasn't really ever really much directlyinvolved in Linux development - he was active on the BSD side - but he wasthe developer behind Minix/i386, which was what I used for the originalLinux development in the very early days before Linux becameself-hosting."On the stable-update side,5.4.8,4.19.93,4.14.162,4.9.208, and4.4.208 are all available with another setof important fixes.

Anybody who has ever taken a numerical analysis course understands thatfloating-point arithmetic on computers is a messy affair. Even so, it iseasy to underestimate just how messy things can be. This topic came to thefore in an initially unrelated python-ideas mailing-list thread; whatshould the Python statisticsmodule do with floating-point values that are explicitly not numbers?

It is not all that often that the mainstream press looks at issues in the open-source world, but this article from The Atlantic does just that; it looks at the controversy surrounding GitHub renewing its contract with the US Immigration and Customs Enforcement (ICE) agency and the concerns some have had with their code being used by ICE. "So when news of GitHub’s contract with ICE emerged, its employees weren’t the only ones outraged. Because of the transitive nature of open source, volunteer developers—who host code on the site to share with others—may have unwittingly contributed to the code GitHub furnished for ICE, the agency responsible for enforcing immigration policy. Some were troubled by the idea that their code might in some way be used to help agents detain and deport undocumented migrants. But their outrage—and the backlash to it—reveals existential questions about the very nature of open source."

Security updates have been issued by Debian (netty) and Fedora (libssh, nethack, php, samba, and xen).

One of the advantages of the in-kernel BPF virtual machine is that it isfast. BPF programs are just-in-time compiled and run directly by the CPU,so there is no interpreter overhead. For many of the intended use cases,though, "fast" can never be quite fast enough. It is thus unsurprisingthat there are currently anumber of patch sets under development that are intended to speed up oneaspect or another of using BPF in the system. A few, in particular, seemabout ready to hit the mainline.

Over the holiday week, we missed the announcement of Ruby 2.7 on December 25. It is the most recent release of the Ruby programming language and was more than a year in development. There are quite a few new features including experimental pattern matching for case statements (more information can be found in these slides), a new compaction garbage collector for the heap, support for separating positional and keyword arguments, and plenty more.

Security updates have been issued by Red Hat (chromium-browser and rh-git218-git) and SUSE (java-1_8_0-ibm and openssl-1_1).

The LWN.net Weekly Edition for January 2, 2020 is available.

Python prides itself on being a newbie-friendly language; its developershave gone out of their way to try to ensure that easy tasks arestraightforward to program. A recent discussion on the python-ideasmailing list looked at a use case that is common, but often implemented in aninefficient, incorrect fashion, with an eye toward making it easier to docorrectly. Finding the first match for a regular expression in a body oftext is where the conversation started, but it went in some otherinteresting directions as well.

January 1, 2020 marks the beginning of a new year and a new decade. Manythings will doubtless change over the course of this year in thefree-software community and beyond, while others will remain the same. One thing that will certainlyhold true is LWN's tradition of starting the new year with some ill-advisedpredictions about what may be in store. Your editor has no special vision,but neither does he fear being proved badly wrong in a public setting —it's all in a day's work.

Security updates have been issued by Debian (igraph, jhead, libgcrypt20, otrs2, and waitress) and Mageia (clamaw, exiv2, filezilla, hunspell, libidn2, pdfresurrect, roundcubemail, and xpdf).

A proposal to periodically run the fstrimcommand on Fedora 32 systems was discussed recently on the Fedoradevel mailing list.fstrim is used to cause a filesystem to inform the underlyingstorage of unused blocks, which can help SSDs and other types of blockdevices perform better.There were a number of questions and concerns raised,including whether to change the behavior of earlier versions of thedistribution when they get upgraded and if the kernel should be responsiblefor handling the whole problem.

Stable kernels 5.4.7, 4.19.92, and 4.14.161 have been released. They all containimportant fixes and users should upgrade.

Security updates have been issued by Debian (intel-microcode and libbsd), openSUSE (chromium, LibreOffice, and spectre-meltdown-checker), and SUSE (mozilla-nspr, mozilla-nss and python-azure-agent).

Security updates have been issued by Debian (debian-lan-config, freeimage, imagemagick, libxml2, mediawiki, openssl1.0, php5, and tomcat8).

The results from the Debian general resolutionvote on init systems are in; the project's developers chose the option titled "Systemd but wesupport exploring alternatives". It makes systemd into the preferredinit system, and allows packages to use systemd-specific features;packagers are not required to support other init systems, but support forother systems is encouraged where it is practical.

The 5.5-rc4 kernel prepatch is out fortesting. "To absolutely nobody's surprise, last week was very quietindeed. It's hardly even worth making an rc release, but there are _some_fixes in here, so here's the usual weekly Sunday afternoon rc."

Matthew Garrett worksout how to avoid being recorded by "Ring" door cameras in his apartmentbuilding. "The most interesting one here is the deauthenticationframe that access points can use to tell clients that they're no longerwelcome. These can be sent for a variety of reasons, including resourceexhaustion or authentication failure. And, by default, they're entirelyunprotected. Anyone can inject such a frame into your network and causeclients to believe they're no longer authorised to use the network, atwhich point they'll have to go through a new authentication cycle - andwhile they're doing that, they're not able to send any otherpackets."

Security updates have been issued by SUSE (dia, kernel, and libgcrypt).

One of the first uses of the BPF virtualmachine outside of networking was to implement access-control policiesfor the seccomp()system call. Since then, though, the role of BPF in the security area hasnot changed much in the mainline kernel, even though BPF has evolvedconsiderably from the "classic" variant still used with seccomp()to the "extended" BPF now supported by the kernel. That has not been for alack of trying, though. The out-of-tree Landlock security module was covered here over three years ago. We also looked at the kernel runtime securityinstrumentation (KRSI) patch set in September. KP Singh has posted a newKRSI series, so the time seems right for a closer look.

Andrew 'bunnie' Huang has posted a detailed article onwhy creating trustable hardware is so difficult and describing a projecthe's working on to do it anyway. "While open hardware has the opportunity toempower users to innovate and embody a more correct and transparent designintent than closed hardware, at the end of the day any hardware ofsufficient complexity is not practical to verify, whether open orclosed. Even if we published the complete mask set for a modernbillion-transistor CPU, this 'source code' is meaningless without apractical method to verify an equivalence between the mask set and the chipin your possession down to a near-atomic level without simultaneouslydestroying the CPU."

Security updates have been issued by CentOS (firefox, fribidi, nss, nss-softokn, nss-util, openslp, and thunderbird), Debian (opensc), and Mageia (389-ds-base, apache, apache-mod_auth_openidc, kernel, libofx, microcode, php, and ruby).

Security updates have been issued by CentOS (freetype, kernel, nss, nss-softokn, nss-util, and thunderbird), Mageia (ghostpcl, libmirage, and spamassassin), Oracle (fribidi), and SUSE (mariadb-100, shibboleth-sp, and slurm).

Security updates have been issued by Debian (cups, cyrus-sasl2, tightvnc, and x2goclient), Fedora (cacti and cacti-spine), openSUSE (mariadb and samba), Oracle (fribidi, git, and python), Red Hat (fribidi, libyang, and qemu-kvm-rhev), Slackware (openssl and tigervnc), and SUSE (firefox, nspr, nss and kernel).

The third 5.5 kernel prepatch is out; itwas a bit bigger than Linus would have liked."Anyway, I'm hoping rc3 is a one-off. In fact, with the holiday seasoncoming up, I'd be very surprised indeed if it wasn't. So I suspectthings will calm down a lot over the next couple of weeks, but pleasedo use the down-time to do some extra testing instead, ok?"

The5.4.6,4.19.91,4.14.160,4.9.207, and4.4.207stable kernel updates have all been released; each contains another set ofimportant fixes.

The Linux control-group mechanism was designed to make it easy to assignprocesses to groups or move them around; it is a simple matter of writing aprocess ID to the appropriate cgroup.procs file in thecontrol-group filesystem hierarchy. That only works for processes thatactually exist, though. Adding the ability to place a new process into acontrol group at birth is the subject of thispatch set from Christian Brauner.

Michał Górny describesan effort to create something one might have never expected to see: abinary kernel package for the Gentoo distribution. "I have manuallyconfigured the kernels for my private systems long time ago. Today, Iwouldn’t really have bothered. In fact, I realized that for some time I’mreally hesitant to even upgrade them because of the effort needed to updateconfiguration. The worst part is, whenever a new kernel does not boot, Ihave to ask myself: is it a real bug, or is it my fault for configuring itwrong?"

Security updates have been issued by Debian (cyrus-imapd and gdk-pixbuf), Fedora (cacti, cacti-spine, and fribidi), Red Hat (fribidi, git, and openstack-keystone), Scientific Linux (fribidi), Slackware (wavpack), and SUSE (firefox, kernel, mariadb, spectre-meltdown-checker, and trousers).

Version3.11 of the lightweight Alpine Linux distribution is available.Changes include the 5.4 kernel, Raspberry Pi 4 support, GNOME and KDEsupport, and the deprecation of Python 2.

The Cloud Native Computing Foundation (CNCF) is part of the Linux Foundation that is focused on Kubernetes and other cloud technologies. It has announced that The Update Framework (TUF) has graduated to a full member project. "TUF, an open-source technology that secures software update systems, is the first specification and first security-focused project to graduate. Justin Cappos, associate professor of computer science and engineering at NYU Tandon School of Engineering, initially developed the project in 2009. Cappos is also the first academic researcher to lead a graduated project and TUF is the first project born out of a university to graduate.

Security updates have been issued by Arch Linux (git, libgit2, and shadow), Debian (debian-edu-config and python-django), Fedora (python-django), Mageia (apache-commons-beanutils, fence-agents, flightcrew, freerdp, htmldoc, libssh, pacemaker, rsyslog, samba, and sssd), Oracle (freetype and kernel), Scientific Linux (freetype and kernel), SUSE (firefox, spectre-meltdown-checker, thunderbird, xen, and zziplib), and Ubuntu (python-django).

The LWN.net Weekly Edition for December 19, 2019 is available.

2019 is coming to a close. It has been anotherbusy year with a lot going on in the Linux and free-software communities.Here at LWN, we have a longstanding tradition of looking back at the predictions made in January to see justhow badly we did; it's not good to go against tradition no matter howembarrassing the results might be, so we might as well get right into it.

Once upon a time, Linux was installed from a stack of floppydisks—thankfully cassette tape "drives" were long in the past at thatpoint—but floppies were superseded by optical media, first CDs and thenDVDs. These days, those options are starting to fade away in most newcomputer systems; just as it is now rather hard to find a floppy-based Linuxinstaller, not to mention the media and drives themselves, someday opticalmedia installation will disappear as well. For Fedora, that day has not trulyarrived, though a somewhat confusingly presented proposal on the Fedoradevel mailing list is, to a limited extent, a step in that direction.

Stable kernels 5.4.4, 5.3.17, 4.19.90, and 4.14.159 have been released. They all containimportant fixes and users should upgrade.Update: Stable kernels 5.4.5 and 5.3.18 have also been released. This is thelast 5.3.y kernel release and users should move to 5.4.y.

Security updates have been issued by Debian (debian-edu-config, harfbuzz, libvorbis, and python-ecdsa), Fedora (chromium, fribidi, libssh, and openslp), openSUSE (chromium), Oracle (grub2), Red Hat (rh-maven35-apache-commons-beanutils), SUSE (kernel, libssh, mariadb, samba, and xen), and Ubuntu (openjdk-8, openjdk-lts).

Programming languages generally have limits—explicit or implicit—on variousaspects of their operation. Things like the maximum length of anidentifier or the range of values that a variable can store are fairlyobvious examples, but there are others, many of which are unspecifiedby the language designers and come about from various implementations ofthe language. That ambiguity has consequences, so nailing down a widevariety of limits in Python is the target of an ongoing discussion on thepython-dev mailing list.

SpamAssassin 3.4.3 has been released. It includes a new plugin for findingmacros in Office documents, a couple of security fixes, and various otherimprovements. The project is also letting it be known that, due to thedropping of support for rulesets with SHA-1 signatures, versions ofSpamAssassin prior to 3.4.2 will no longer be able to download rule updatesas of the beginning of March.

Security updates have been issued by Debian (libssh, ruby2.3, and ruby2.5), Fedora (kernel and libgit2), openSUSE (chromium and libssh), Oracle (openslp), Red Hat (container-tools:1.0, container-tools:rhel8, freetype, kernel, and kpatch-patch), Scientific Linux (openslp), SUSE (git and LibreOffice), and Ubuntu (graphicsmagick).

XFS filesystem maintainer Darrick Wong summarizesthe significant XFS developments from the last year. "The year2038 poses a special problem for Linux -- any signed 32-bit seconds counterwill overflow back to 1901. Work is underway in the kernel to extend all ofthose counters to support 64-bit counters fully. In 2020, we will beginwork on extending XFS's metadata (primarily inode timestamps and quotaexpiration timer) to support timestamps out to the year 2486. It should bepossible to upgrade to existing V5 filesystems."