LWN.net

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

In the Kernel Summittrack at the2019Linux Plumbers Conference, Christian Brauner and Kees Cook led adiscussion on finding a way to do deep argument inspection for seccompfiltering. Currently, seccomp filters can only look at the top-levelarguments to a system call, which means that there are use cases thatcannot be supported. There was a lively discussion in the session, but nodefinitive conclusion was reached; various ideas were considered, but noneseemed to quite fit the bill.

Security updates have been issued by CentOS (firefox and kernel), Debian (thunderbird), Fedora (curl), openSUSE (curl and python-Werkzeug), Oracle (kernel and thunderbird), Red Hat (rh-nginx114-nginx), SUSE (curl, ibus, MozillaFirefox, firefox-glib2, firefox-gtk3, openldap2, openssl, openssl1, python-urllib3, and util-linux and shadow), and Ubuntu (linux, linux-aws, linux-azure, linux-lts-trusty, linux-lts-xenial, linux-oracle, linux-raspi2, linux-snapdragon, and wpa).

The Mozilla blog has an announcementthat Firefox will be moving to 4-week release cycle, starting in 2020."Shorter release cycles provide greater flexibility to supportproduct planning and priority changes due to business or marketrequirements. With four-week cycles, we can be more agile and ship featuresfaster, while applying the same rigor and due diligence needed for ahigh-quality and stable release. Also, we put new features andimplementation of new Web APIs into the hands of developers morequickly." The Firefox ESR (Extended Support Release) release cadencewill remain the same.

At OpenSource Summit North America 2019, David Tarditi from Microsoft gave a talk onseven different properties for highly secure Internet of Things (IoT)devices. The properties are based on a Microsoft Research whitepaper [PDF] from 2017. His high-level summary of the talk was that ifyou are creating a device that will be connecting to the internet and youdon't want it to get "owned", you should pay attention to the properties hewould be describing.Overall, it was an interesting talk, with good analysis of the areas whereeffort needs to be focused to produce secure IoT devices, but it wassomewhat marred by an advertisement for a proprietary product(which, naturally, checked all the boxes) atthe end of the talk.

A new release of CentOS Linux 7 is available. This release is tagged as1908 and derived from Red Hat Enterprise Linux 7.7 source code. The releasenotes have the details. CentOS Linux 7 (1908) is also available for several alternatearchitectures.

Security updates have been issued by Debian (dino-im, python2.7, python3.4, and wpa), Fedora (kmplayer), openSUSE (podman and samba), Oracle (thunderbird), Red Hat (thunderbird), Slackware (expat), SUSE (curl), and Ubuntu (apache2).

The final sessions at the 2019 Linux Kernel Maintainers Summit covered anumber of relatively quick topics, including the "pull depth" for codegoing into the mainline, the handling of hardware vulnerabilities, the ABIstatus of tracepoints, and more.

With a brief announcement,the Free Software Foundation has let it be known that founder RichardStallman has resigned both as president and from the board of directors."The board will be conducting a search for a new president, beginningimmediately. Further details of the search will be published onfsf.org".

The Linux Kernel Maintainers Summit is all about the development process,so it is natural to spend some time on how that process is working at thetop of the maintainer hierarchy. The "is Linus happy?" session during the2019 summit revealed that things are working fairly well at that level, butthat, as always, there are a few things that could be improved.

Stable kernels 5.2.15, 4.19.73, 4.14.144, 4.9.193, and 4.4.193 have been released. They all containimportant fixes and users should upgrade.

Security updates have been issued by Debian (ansible, faad2, linux-4.9, and thunderbird), Fedora (jbig2dec, libextractor, sphinx, and thunderbird), Mageia (expat, kconfig, mediawiki, nodejs, openldap, poppler, thunderbird, webkit2, and wireguard), openSUSE (buildah, ghostscript, go1.12, libmirage, python-urllib3, rdesktop, and skopeo), SUSE (python-Django), and Ubuntu (exim4, ibus, and Wireshark).

The stable kernel process is a perennial topic of discussion at gatheringsof kernel developers; the 2019 Linux Kernel Maintainers Summit was noexception. Sasha Levin ran a session there where developers could talkabout the problems they have with stable kernels and ponder solutions.

The 5.3 kernel is available at last. Theannouncement includes a long discussion about user-space regressions — anext4 filesystem performance improvement had caused some systems to failbooting due to a lack of entropy early after startup. "It's morethat it's an instructive example of what counts as a regression, and whatthe whole 'no regressions' kernel rule means. The reverted commit didn'tchange any API's, and it didn't introduce any new bugs. But it ended upexposing another problem, and as such caused a kernel upgrade to fail for auser. So it got reverted."Some of the more significant changes in 5.3 includescheduler utilization clamping,the pidfd_open() andclone3() system calls,bounded loop support for BPF programs,support for the 0.0.0.0/8 IPv4 address range,a new configurationoption for the soon-to-be-merged realtime preemption code,and more. See theKernelNewbies 5.3 page for lots of details.

There is value in automatic testing systems, but they also present aproblem of their own:how can one keep up with the high volume of bug reports that they generate?At the 2019 Linux Kernel Maintainers Summit, Shuah Khan ran a sessiondedicated to this issue. There was general agreement that the reports arehard to deal with, but not a lot of progress toward a solution.

The first session at the 2019 Linux Kernel Maintainers Summit was alast-minute addition to the schedule. Dmitry Vyukov's Linux PlumbersConference session on the kernel development process (slides[PDF]) had inspired a number of discussions that, it was agreed, shouldcarry over into the summit. The result was a wide-ranging conversationabout the kernel's development tools and what could be done to improvethem.

Security updates have been issued by Debian (curl, dnsmasq, and golang-go.crypto), Mageia (docker, firefox, flash-player-plugin, ghostscript, links, squid, sympa, tcpflow, thunderbird, and znc), openSUSE (srt), Oracle (.NET Core, kernel, libwmf, and poppler), Scientific Linux (firefox), SUSE (cri-o, curl, java-1_8_0-ibm, python-SQLAlchemy, and python-urllib3), and Ubuntu (curl and expat).

Hardening must be performed at all levels of a system, including in thecompiler that is used to build that system. There are two viable compilersin the free-software community now, each of which offers a different set ofsecurity features. Kees Cook ran a session during the Toolchainsmicroconference at the 2019 LinuxPlumbers Conference that examined the security-feature support providedby both GCC and LLVM Clang, noting the places where each one could stand toimprove.

Security updates have been issued by Arch Linux (exim, firefox, and webkit2gtk), Debian (libonig and opensc), Fedora (cobbler), Oracle (firefox and kernel), Red Hat (flash-plugin, kernel, kernel-rt, rh-maven35-jackson-databind, rh-nginx110-nginx, and rh-nginx112-nginx), Scientific Linux (kernel), Slackware (curl, mozilla, and openssl), SUSE (ceph, libvirt, and python-Werkzeug), and Ubuntu (vlc and webkit2gtk).

The LWN.net Weekly Edition for September 12, 2019 is available.

On day two of the 2019Linux Plumbers Conference, two of the principals behind the Open Printingproject led the very first Open Printingmicroconference. Project leader Till Kamppeter and program managerAveek Basu described the current state of printing on Linux and some of theplans for the future, including supporting scanning for multi-functiondevices. The picture they painted was rosy, at least for printing, whichmay not quite match the experience of many Linux users. As with manyprojects, though, Open Printing is starved for contributors—something thatwas reflected in the sparse attendance at the microconference.

At the 2019EmbeddedLinux Conference North America, which was held in San Diego in August,Krzysztof Opasiak gave a presentation on demystifying the ways to monitor—andeven change—USB traffic on a Linux system. He started with the basics ofthe USB protocol and worked up into software and hardware tools toobserve, modify, and fuzz the messages that get sent. Those tools are part of thearsenal that is available to those interested in looking deeply into USB.

Software Guard Extensions (SGX) is a set of security-relatedinstructions for Intel processors; it allows the creation of privateregions of memory, called "enclaves". The aim of this feature is to worklike an inverted sandbox: instead of protecting the system from maliciouscode, it protects an application from a compromised kernel hypervisor,or other application. Linux support for SGX has existed out-of-treefor years, and the effort of upstreaming it has reached animpressive version22 of the patch set. During the upstreaming discussion, the kerneldevelopers discoveredthat the proposed SGX API did not play nicely with existing securitymechanisms, including Linux security modules(LSMs).

Security updates have been issued by Fedora (python38), openSUSE (nginx, nodejs10, nodejs8, python-Twisted, python-Werkzeug, SDL2_image, SDL_image, and util-linux and shadow), Oracle (firefox and nghttp2), Red Hat (.NET Core, firefox, kernel, libwmf, pki-deps:10.6, and poppler), Scientific Linux (firefox), SUSE (ghostscript, libgcrypt, podman, python-SQLAlchemy, qemu, and webkit2gtk3), and Ubuntu (curl, linux-hwe, linux-kvm, linux-oracle, linux-raspi2, systemd, and tomcat8).

The CodeWeavers blog carries the sadnews that Józef Kucia died last month. "Józef first contributed to Wine in March of 2012, showing remarkable skill with Wine’s D3D technology. He became a key contributor to Wine, submitting over 2,500 patches. He also contributed to other open source projects including Mesa and Debian. Józef founded and led the vkd3d project and provided insight and guidance to the Vulkan working group.Józef joined CodeWeavers in 2015, and quickly became one of our most valued employees."

Stable kernels 5.2.14, 4.19.72, 4.14.143, 4.9.192, and 4.4.192 have been released. They all containimportant fixes and users should upgrade.

Security updates have been issued by Debian (docker.io, icedtea-web, and trafficserver), openSUSE (opera), Red Hat (bind, firefox, go-toolset:rhel8, kernel, nghttp2, and polkit), SUSE (buildah, curl, java-1_7_1-ibm, and skopeo), and Ubuntu (freetype, memcached, python2.7, python3.4, and python2.7, python3.5, python3.6, python3.7).

It's that time of the development cycle again: work on the 5.3 kernel iswinding down with an expected final release date of September 15. Read onfor LWN's traditional look at where the code in 5.3 came from in thisrelatively busy development cycle.

Security updates have been issued by Debian (expat, ghostscript, libreoffice, and memcached), Fedora (chromium, grafana, kea, nsd, pdfbox, roundcubemail, and SDL), Gentoo (apache, dbus, exim, libsdl2, pango, perl, vlc, and webkit-gtk), Mageia (dovecot, giflib, golang, icedtea-web, irssi, java-1.8.0-openjdk, libgcrypt, libmspack, mercurial, monit, php, poppler, python-urllib3, rdesktop, SDL12, sdl2, sigil, sqlite3, subversion, tomcat, and zstd), openSUSE (chromium, exim, go1.12, httpie, libmirage, python-SQLAlchemy, and srt), Oracle (firefox, ghostscript, and kernel), SUSE (apache2, mariadb, mariadb-connector-c, postgresql94, python-Django1, python-Pillow, python-urllib3, and qemu), and Ubuntu (exim4).

The eighth and presumably final 5.3prepatch is out for testing. "So we probably didn't strictly need an rc8 this release, but with LPCand the KS conference travel this upcoming week it just makeseverything easier."

Anybody running the Exim mail system will want to apply the updates thatare being released today; there is a remote code-execution vulnerability inits TLS-handling code with a known proof-of-concept exploit. As the advisorysays: "If your Exim server accepts TLS connections, it isvulnerable".

The5.2.12,4.19.70,4.14.142,4.9.191, and4.4.191stable kernels have been released with another set of important fixes.Milliseconds thereafter,5.2.13 and4.19.71were released to fix a regression with the elantech mouse driver.

Google has a long and interesting history contributing to the upstreamLinux kernel. With Chrome OS, Google has tried to learn from some ofthe mistakes of its past and is now working with the upstream Linux kernel asmuch as it can. In a session at the 2019Open Source Summit North America, Google software engineer DougAnderson detailed how and why Chrome OS developers work upstream. Itis an effort intended to help the Linux community as well as Google.

Security updates have been issued by Debian (exim4 and firefox-esr), Fedora (lxc, lxcfs, pdfresurrect, python3-lxc, rdesktop, and seamonkey), Oracle (kernel), and SUSE (nginx, python-Werkzeug, SUSE Manager Client Tools, and util-linux and shadow).

The staging tree was added to the kernel in 2008for the 2.6.28 development cycle as a way to ease the process ofgetting substandard device drivers into shape and merged into themainline. It has been followed by controversy for just about as long. Therecent disagreements over the EROFS and exFAT filesystems have reignited many of thearguments over whether the staging tree is beneficial to the kernelcommunity or not. LWN cannot answer that question, but we can look into what has transpired in thestaging tree in its first eleven years to see if there are any conclusionsto be drawn there.A lot of code has gone into the staging tree over the years; what happenedto it thereafter?

Security updates have been issued by Debian (webkit2gtk), Fedora (systemd), openSUSE (go1.11, python-Twisted, SDL2_image, SDL_image, and wavpack), Oracle (kdelibs and kde-settings, kernel, and qemu-kvm), Red Hat (chromium-browser and firefox), Slackware (seamonkey), SUSE (java-1_8_0-ibm, kernel, and python-urllib3), and Ubuntu (firefox and npm/fstream).

Google has announcedthe release of a new library for applications using differential privacytechniques. "Differentially-private data analysis is a principledapproach that enables organizations to learn from the majority of theirdata while simultaneously ensuring that those results do not allow anyindividual's data to be distinguished or re-identified. This type ofanalysis can be implemented in a wide variety of ways and for manydifferent purposes. For example, if you are a health researcher, you maywant to compare the average amount of time patients remain admitted acrossvarious hospitals in order to determine if there are differences incare. Differential privacy is a high-assurance, analytic means of ensuringthat use cases like this are addressed in a privacy-preservingmanner."

The LWN.net Weekly Edition for September 5, 2019 is available.

The Linux Plumbers Conference has filled up and has closed its waiting list. "All of the spots available have been allocated, so anyone whois not registered at this point will have to wait for next year. Therewill be no on-site registration. We regret that we could notaccommodate everyone. The good news is that all of themicroconferences, refereed talks, Kernel summit track, and Networkingtrack will be recorded on video and made available as soon as possibleafter the conference. Anyone who could not make it to Lisbon this yearwill at least be able to catch up with what went on. Hopefully thosewho wanted to come will make it to a future LPC." LPC will be held in Lisbon, Portugal, September 9-11.

Finding ways to make it easier and faster to mitigate an ongoing attackagainst a Linux system at runtime is part of the motivation behind thekernel runtime security instrumentation (KRSI) project. Its developer, KPSingh, gave a presentation about the project at the 2019LinuxSecurity Summit North America (LSS-NA), which was held in late Augustin San Diego. A prototype of KRSI is implemented as a Linux securitymodule (LSM) that allows eBPF programs to be attached to the kernel'ssecurity hooks.

Security updates have been issued by Arch Linux (grafana, irssi, and jenkins), Debian (freetype, samba, and varnish), Fedora (community-mysql, kernel, kernel-headers, kernel-tools, and python-mitogen), openSUSE (postgresql10 and python-SQLAlchemy), Oracle (kdelibs and kde-settings and squid:4), Red Hat (kdelibs and kde-settings, kernel, kernel-rt, openstack-nova, qemu-kvm, and redis), Scientific Linux (kdelibs and kde-settings, kernel, and qemu-kvm), SUSE (ansible, java-1_7_1-ibm, libosinfo, php53, and qemu), and Ubuntu (irssi, samba, and systemd).

A typical kernel development cycle involves pulling patches from over 100repositories into the mainline. Any of those pulls could conceivablybring with it malicious code, leaving the kernel (and its users) open tocompromise. The kernel's web of trust helps maintainers to ensure thatpull requests are legitimate, but that web has become difficult to maintainin the wake of the recent attacks on keyservers and other problems. So now the kernel community istaking management of its web of trust into its own hands.

Thisgrsecurity blog entry looks at how an ineffective Spectre fix found itsway into the stable kernel releases. If one looks past the advertising,it's a good summary of how the kernel processes can produce the wrongresult. "Despite this warning, this code was merged into ThomasGleixner's x86/tip tree verbatim, as can be seen here.Prior to merging the fix for 5.3-rc1, Linus Torvalds noticed the warning asseen on the LKML mailing list here and fixed it correctly.However, when the actual mergeof the tree was performed, no mention was made of the correction to thefix, and with no specific commit mentioning the correction and fixing italone, everyone else's processes that depended on cherry-picking specificcommits ended up grabbing the bad warning-inducing change.As a further failure, instead of looking at Linus' correct fix (observableby checking out the master tree at the time), the approach seems to havebeen to naively silence the warning by simply swapping the order of the twolines."

Providing meaningful metrics for open-source projects has long been achallenge, as simply measuring downloads, commits, or GitHub stars typicallydoesn't say much about the health or diversity of a project. It's achallenge the Linux Foundation's Community Health Analytics Open Source Software (CHAOSS) project islooking to help solve. At the 2019Open Source Summit North America (OSSNA), Matt Germonprez, one of the foundingmembers of CHAOSS, outlined what the group is currently doing and why itsinitial efforts didn't work out as expected.

Google has announcedthe release of Android 10, the free parts of which are available fromthe Android Open Source Project now. "Privacy is a central focus inAndroid 10, from stronger protections in the platform to new featuresdesigned with privacy in mind. Building on previous releases, Android 10includes extensive changes to protect privacy and give users control, withimproved system UI, stricter permissions, and restrictions on what dataapps can use."

Firefox 69.0 has been released. This release enables on-by-default EnhancedTracking Protection for all users and gives more control over blockingplayback of videos which start playing automatically. See the release notesfor details.

Security updates have been issued by Debian (qemu), Fedora (ansible and wavpack), openSUSE (apache-commons-beanutils, apache2, go1.12, httpie, libreoffice, qemu, and slurm), Oracle (ghostscript), Scientific Linux (ghostscript), SUSE (ardana-ansible, ardana-barbican, ardana-cinder, ardana-cluster, ardana-cobbler, ardana-db, ardana-designate, ardana-extensions-nsx, ardana-glance, ardana-heat, ardana-horizon, ardana-input-model, ardana-installer-ui, ardana-ironic, ardana-keystone, ardana-logging, ardana-magnum, ardana-monasca, ardana-mq, ardana-neutron, ardana-nova, ardana-octavia, ardana-opsconsole, ardana-opsconsole-ui, ardana-osconfig, ardana-service, ardana-ses, ardana-swift, ardana-tempest, crowbar-core, crowbar-ha, crowbar-openstack, crowbar-ui, java-monasca-common, java-monasca-common-kit, openstack-ceilometer, openstack-cinder, openstack-designate, openstack-heat, openstack-horizon-plugin-neutron-fwaas-ui, openstack-horizon-plugin-neutron-lbaas-ui, openstack-horizon-plugin-neutron-vpnaas-ui, openstack-ironic, openstack-ironic-python-agent, openstack-keystone, openstack-magnum, openstack-manila, openstack-monasca-notification, openstack-monasca-persister, openstack -monasca-persister-java, openstack-monasca-persister-java-kit, openstack-neutron, openstack-neutron-gbp, openstack-neutron-lbaas, openstack-nova, openstack-octavia, openstack-tempest, python-ardana-configurationprocessor, python-cinder-tempest-plugin, python-ironicclient, python-keystonemiddleware, python-monasca-tempest-plugin, python-openstackclient, python-openstacksdk, python-proliantutils, python-python-engineio, python-swiftlm, python-vmware-nsx, python-vmware-nsxlib, yast2-crowbar, pacemaker, and php72), and Ubuntu (linux, linux-aws, linux-kvm, linux-raspi2, linux-snapdragon, linux-aws, linux-oracle, linux-raspi2, linux-raspi2, linux-snapdragon, and policykit-1).

The success stories that have gathered around data analyticsdrive broader adoption of the newest artificial-intelligence-basedtechniques—but risks come along with these techniques. The large numbers of freshlyanointed data scientists piling into industry and the sensitivity of theareas given over to machine-learning models—hiring, loans, evensentencing for crime—means there is a danger of misapplied models,which is earning the attention of the public. Two sessions at the recent MinneBOS 2019 conference focused on maintaining ethics andaddressingbias in machine-learning applications.

The 5.3-rc7 kernel prepatch is out fortesting, one day later than usual. The final 5.3 release may also bedelayed a week to accommodate Linus's travel schedule: "So I dosuspect that with my timing (and a number of other developers are probablygoing to be traveling for LPC and KS too) I'll just make an rc8 even if itturns this Labor Day week ends up being very quiet and there might not beany _technical_ reason to delay the release."

Security updates have been issued by Debian (gosa, libav, libextractor, nghttp2, pump, and python2.7), Fedora (dovecot, mod_http2, and pango), Gentoo (dovecot, gnome-desktop, libofx, and nautilus), Mageia (ansible, ghostscript, graphicsmagick, memcached, mpg123, pango, vlc, wavpack, webmin, wireshark, and wpa_supplicant, hostapd), openSUSE (flatpak, libmirage, podman, slirp4netns and libcontainers-common, python-SQLAlchemy, and qemu), Red Hat (ghostscript, java-1.8.0-ibm, and squid:4), and SUSE (kernel, libsolv, libzypp, zypper, NetworkManager, nodejs10, nodejs8, perl, python-Django, and python-SQLAlchemy).