Language Selection

English French German Italian Portuguese Spanish

LWN

Syndicate content
LWN.net is a comprehensive source of news and opinions from and about the Linux community. This is the main LWN.net feed, listing all articles which are posted to the site front page.
Updated: 1 hour 31 min ago

[$] LWN.net Weekly Edition for February 21, 2019

Thursday 21st of February 2019 12:37:20 AM
The LWN.net Weekly Edition for February 21, 2019 is available.

Yaghmour: gitgeist: a git-based social network proof of concept

Wednesday 20th of February 2019 05:53:08 PM
On his blog, Karim Yaghmour writes about an experimental social network that he and a colleague cobbled together using Git. While it is simply a proof of concept at this point, he is looking for feedback and, perhaps, collaborators to take it further. "It turns out that git has practically everything that's needed to act both as storage and protocol for a social network. Not only that, but it's very well-known within and used, deployed and maintained in the circles I navigate, it scales very well (see github), it's used for critical infrastructure (see kernel.org), it provides history, it's distributed by nature, etc. It's got *almost* everything, but not quite everything needed. So what's missing from git? A few basic things that it turns out aren't very hard to take care of: ability to 'follow', getting followee notifications, 'commenting' and an interface for viewing feeds. And instead of writing a whole online treatise of how this could be done, I asked my colleague Francois-Denis Gonthier to implement a proof and concept of this that we called 'gitgeist' and just published on github [https://github.com/opersys/gitgeist-poc]."

[$] Producing an application for both desktop and mobile

Wednesday 20th of February 2019 04:31:09 PM

These days applications are generally moving away from the desktop and toward the mobile space. But taking a multi-platform desktop application and adding two mobile platforms into the mix is difficult to do, as Dirk Hohndel described in his linux.conf.au 2019 talk. Hohndel maintains the Subsurface dive log application, which has added mobile support over the past few years; he wanted to explain the process that the project went through to support all of those platforms. As the subtitle of the talk, "Developing for multiple platforms without losing your mind", indicates, it is a hard problem to solve sanely.

Stable kernel updates

Wednesday 20th of February 2019 03:19:49 PM
Stable kernels 4.20.11, 4.19.24, 4.14.102, 4.9.159, 4.4.175, and 3.18.135 have been released. They all contain important fixes and users should upgrade.

Security updates for Wednesday

Wednesday 20th of February 2019 03:10:10 PM
Security updates have been issued by Debian (ansible, drupal7, and systemd), Fedora (botan2, ceph, and firefox), Oracle (firefox, flatpak, and systemd), Red Hat (firefox), SUSE (gvfs, kernel, libqt5-qtbase, python-numpy, and qemu), and Ubuntu (gdm3).

digiKam 6.0.0 released

Tuesday 19th of February 2019 06:44:41 PM
The digiKam team has announced the release of digiKam 6.0.0. New features include full support of video files management working as photos; an integration of all import/export web-service tools in LightTable, Image editor, and Showfoto; raw file decoding engine supporting new cameras; similarity data is now stored in a separate file; simplified web-service authentication using OAuth protocol; and more.

[$] Patent exhaustion and open source

Tuesday 19th of February 2019 04:55:56 PM

When patents and free software crop up together, the usual question is about patent licensing. Patent exhaustion — the principle that patent rights don't reach past the first sale of a product — is much less frequently discussed. At FOSDEM 2019, US lawyer Van Lindberg argued that several US court decisions related to exhaustion, most of them recent but some less so, could come together to have surprising beneficial effects for free software. He was clear that the argument applied only in the US but, since court systems tend to look to each other for consistency's sake, and because Lindberg is an engaging speaker, the talk was of great interest even in Brussels.

Security updates for Tuesday

Tuesday 19th of February 2019 03:48:33 PM
Security updates have been issued by Debian (chromium, rdesktop, rssh, systemd, and uriparser), Fedora (bouncycastle, eclipse-jgit, eclipse-linuxtools, jackson-annotations, jackson-bom, jackson-core, jackson-databind, jackson-dataformat-xml, jackson-dataformats-binary, jackson-dataformats-text, jackson-datatype-jdk8, jackson-datatype-joda, jackson-datatypes-collections, jackson-jaxrs-providers, jackson-module-jsonSchema, jackson-modules-base, jackson-parent, moby-engine, and subversion), openSUSE (chromium, docker-runc, firefox, GraphicsMagick, kernel, LibVNCServer, php7, pspp, spread-sheet-widget, and runc), SUSE (kernel-firmware, qemu, and systemd), and Ubuntu (nss and systemd).

Debian 9.8 released

Monday 18th of February 2019 07:10:47 PM
The Debian project has announced the eighth update of Debian 9 "stretch". As a stable point release, this version mainly adds bugfixes for security issues and other serious problems. Click below for a list of changes.

[$] The case of the supersized shebang

Monday 18th of February 2019 06:37:50 PM
Regressions are an unavoidable side effect of software development; the kernel is no different in that regard. The 5.0 kernel introduced a change in the handling of the "#!" (or "shebang") lines used to indicate which interpreter should handle an executable text file. The problem has been duly fixed, but the incident shows how easy it can be to introduce unexpected problems and highlights some areas where the kernel's development process does not work as well as we might like.

Security updates for Monday

Monday 18th of February 2019 04:19:36 PM
Security updates have been issued by Arch Linux (cairo, firefox, flatpak, hiawatha, and webkit2gtk), Debian (gsoap, mosquitto, php5, thunderbird, and tiff), Fedora (elfutils, ghostscript, gsi-openssh, kernel, kernel-headers, kernel-tools, kf5-kauth, mingw-podofo, mingw-poppler, mosquitto, podofo, and python-markdown2), Mageia (firefox, flash-player-plugin, lxc, and thunderbird), openSUSE (avahi, docker, libu2f-host, LibVNCServer, nginx, phpMyAdmin, and pspp, spread-sheet-widget), Red Hat (rhvm-appliance), and SUSE (python-numpy).

Kernel prepatch 5.0-rc7

Monday 18th of February 2019 03:38:02 AM
The 5.0-rc7 kernel prepatch has been released. Linus says: "Nothing particularly odd stands out, and everything is pretty small. Just the way I like it."

Geary 0.13.0 released

Sunday 17th of February 2019 03:04:13 PM
Version 0.13.0 of the Geary graphical email client is out. "This is a major new release, featuring a number of new features — including a new user interface for creating and managing email accounts, integration with GNOME Online Accounts (which also provides OAuth login support for some services), improvements in displaying conversations, composing new messages, interacting with other email apps, reporting problems as they occur, and number of important bug fixes, server compatibility fixes, and security fixes."

Ubuntu 18.04.2 LTS released

Friday 15th of February 2019 04:47:06 PM
The Ubuntu team has announced the release of Ubuntu 18.04.2 LTS for its Desktop, Server, and Cloud products, as well as other flavors of Ubuntu with long-term support. Support periods vary for different flavors. "Like previous LTS series, 18.04.2 includes hardware enablement stacks for use on newer hardware. This support is offered on all architectures and is installed by default when using one of the desktop images." Ubuntu Server installs the GA kernel, however the HWE kernel may be selected from the installer bootloader.

[$] Per-vector software-interrupt masking

Friday 15th of February 2019 04:25:02 PM
Software interrupts (or "softirqs") are one of the oldest deferred-execution mechanisms in the kernel, and that age shows at times. Some developers have occasionally been heard to mutter about removing them, but softirqs are too deeply embedded into how the kernel works to be easily ripped out; most developers just leave them alone. So the recent per-vector softirq masking patch set from Frederic Weisbecker is noteworthy as an exception to that rule. Weisbecker is not getting rid of softirqs, but he is trying to reduce their impact and improve their latency.

Two sets of stable kernel updates

Friday 15th of February 2019 03:43:02 PM
Greg Kroah-Hartman released a set of stable kernels that should *not* be used, including: 4.20.9, 4.19.22, 4.14.100, and 4.9.157. Those kernels caused a regression that was reverted in the following kernels: 4.20.10, 4.19.23, 4.14.101, and 4.9.158.

Security updates for Friday

Friday 15th of February 2019 03:20:15 PM
Security updates have been issued by Debian (firefox-esr and unbound), Fedora (docker, libexif, and runc), openSUSE (mozilla-nss, python, rmt-server, and thunderbird), Slackware (mozilla), and SUSE (couchdb, dovecot23, kvm, nodejs6, php53, podofo, python-PyKMIP, rubygem-loofah, util-linux, and velum).

[$] Some challenges for GNOME online accounts

Thursday 14th of February 2019 03:27:19 PM
The cynical among us might be tempted to think that an announcement from the GNOME project about the removal of a feature — a relatively unused feature at that — would be an unremarkable event. In practice, though, Debarshi Ray's announcement that the GNOME Online Accounts (GOA) subsystem would no longer support the "documents" access point touched off a lengthy discussion within the project itself. The resulting discussion revealed a few significant problems with GOA and, indeed, with the concept of online-account management in any sort of open-source umbrella project like GNOME.

Security updates for Thursday

Thursday 14th of February 2019 02:42:24 PM
Security updates have been issued by Debian (python-gnupg), Mageia (avahi, dom4j, gvfs, kauth, libwmf, logback, mad, python, python-django, and radvd), openSUSE (curl, haproxy, lua53, python-slixmpp, runc, spice, and uriparser), Red Hat (flash-plugin), Slackware (mozilla), and SUSE (build and docker-runc).

PostgreSQL 11.2, 10.7, 9.6.12, 9.5.16, and 9.4.21 released

Thursday 14th of February 2019 01:39:38 PM
The PostgreSQL project has put out updated releases for all supported versions. "This release changes the behavior in how PostgreSQL interfaces with 'fsync()' and includes fixes for partitioning and over 70 other bugs that were reported over the past three months." The fsync() issue was covered here in April 2018.

More in Tux Machines

Games: Surviving Mars and OpenMW

Kernel and Security: BPF, Mesa, Embedded World, Kernel Address Sanitizer and More

  • Concurrency management in BPF
    In the beginning, programs run on the in-kernel BPF virtual machine had no persistent internal state and no data that was shared with any other part of the system. The arrival of eBPF and, in particular, its maps functionality, has changed that situation, though, since a map can be shared between two or more BPF programs as well as with processes running in user space. That sharing naturally leads to concurrency problems, so the BPF developers have found themselves needing to add primitives to manage concurrency (the "exchange and add" or XADD instruction, for example). The next step is the addition of a spinlock mechanism to protect data structures, which has also led to some wider discussions on what the BPF memory model should look like. A BPF map can be thought of as a sort of array or hash-table data structure. The actual data stored in a map can be of an arbitrary type, including structures. If a complex structure is read from a map while it is being modified, the result may be internally inconsistent, with surprising (and probably unwelcome) results. In an attempt to prevent such problems, Alexei Starovoitov introduced BPF spinlocks in mid-January; after a number of quick review cycles, version 7 of the patch set was applied on February 1. If all goes well, this feature will be included in the 5.1 kernel.
  • Intel Ready To Add Their Experimental "Iris" Gallium3D Driver To Mesa
    For just over the past year Intel open-source driver developers have been developing a new Gallium3D-based OpenGL driver for Linux systems as the eventual replacement to their long-standing "i965 classic" Mesa driver. The Intel developers are now confident enough in the state of this new driver dubbed Iris that they are looking to merge the driver into mainline Mesa proper.  The Iris Gallium3D driver has now matured enough that Kenneth Graunke, the Intel OTC developer who originally started Iris in late 2017, is looking to merge the driver into the mainline code-base of Mesa. The driver isn't yet complete but it's already in good enough shape that he's looking for it to be merged albeit marked experimental.
  • Hallo Nürnberg!
    Collabora is headed to Nuremberg, Germany next week to take part in the 2019 edition of Embedded World, "the leading international fair for embedded systems". Following a successful first attendance in 2018, we are very much looking forward to our second visit! If you are planning on attending, please come say hello in Hall 4, booth 4-280! This year, we will be showcasing a state-of-the-art infrastructure for end-to-end, embedded software production. From the birth of a software platform, to reproducible continuous builds, to automated testing on hardware, get a firsthand look at our platform building expertise and see how we use continuous integration to increase productivity and quality control in embedded Linux.
  • KASAN Spots Another Kernel Vulnerability From Early Linux 2.6 Through 4.20
    The Kernel Address Sanitizer (KASAN) that detects dynamic memory errors within the Linux kernel code has just picked up another win with uncovering a use-after-free vulnerability that's been around since the early Linux 2.6 kernels. KASAN (along with the other sanitizers) have already proven quite valuable in spotting various coding mistakes hopefully before they are exploited in the real-world. The Kernel Address Sanitizer picked up another feather in its hat with being responsible for the CVE-2019-8912 discovery.
  • io_uring, SCM_RIGHTS, and reference-count cycles
    The io_uring mechanism that was described here in January has been through a number of revisions since then; those changes have generally been fixing implementation issues rather than changing the user-space API. In particular, this patch set seems to have received more than the usual amount of security-related review, which can only be a good thing. Security concerns became a bit of an obstacle for io_uring, though, when virtual filesystem (VFS) maintainer Al Viro threatened to veto the merging of the whole thing. It turns out that there were some reference-counting issues that required his unique experience to straighten out. The VFS layer is a complicated beast; it must manage the complexities of the filesystem namespace in a way that provides the highest possible performance while maintaining security and correctness. Achieving that requires making use of almost all of the locking and concurrency-management mechanisms that the kernel offers, plus a couple more implemented internally. It is fair to say that the number of kernel developers who thoroughly understand how it works is extremely small; indeed, sometimes it seems like Viro is the only one with the full picture. In keeping with time-honored kernel tradition, little of this complexity is documented, so when Viro gets a moment to write down how some of it works, it's worth paying attention. In a long "brain dump", Viro described how file reference counts are managed, how reference-count cycles can come about, and what the kernel does to break them. For those with the time to beat their brains against it for a while, Viro's explanation (along with a few corrections) is well worth reading. For the rest of us, a lighter version follows.

Blacklisting insecure filesystems in openSUSE

The Linux kernel supports a wide variety of filesystem types, many of which have not seen significant use — or maintenance — in many years. Developers in the openSUSE project have concluded that many of these filesystem types are, at this point, more useful to attackers than to openSUSE users and are proposing to blacklist many of them by default. Such changes can be controversial, but it's probably still fair to say that few people expected the massive discussion that resulted, covering everything from the number of OS/2 users to how openSUSE fits into the distribution marketplace. On January 30, Martin Wilck started the discussion with a proposal to add a blacklist preventing the automatic loading of a set of kernel modules implementing (mostly) old filesystems. These include filesystems like JFS, Minix, cramfs, AFFS, and F2FS. For most of these, the logic is that the filesystems are essentially unused and the modules implementing them have seen little maintenance in recent decades. But those modules can still be automatically loaded if a user inserts a removable drive containing one of those filesystem types. There are a number of fuzz-testing efforts underway in the kernel community, but it seems relatively unlikely that any of them are targeting, say, FreeVxFS filesystem images. So it is not unreasonable to suspect that there just might be exploitable bugs in those modules. Preventing modules for ancient, unmaintained filesystems from automatically loading may thus protect some users against flash-drive attacks. If there were to be a fight over a proposal like this, one would ordinarily expect it to be concerned with the specific list of unwelcome modules. But there was relatively little of that. One possible exception is F2FS, the presence of which raised some eyebrows since it is under active development, having received 44 changes in the 5.0 development cycle, for example. Interestingly, it turns out that openSUSE stopped shipping F2FS in September. While the filesystem is being actively developed, it seems that, with rare exceptions, nobody is actively backporting fixes, and the filesystem also lacks a mechanism to prevent an old F2FS implementation from being confused by a filesystem created by a newer version. Rather than deal with these issues, openSUSE decided to just drop the filesystem altogether. As it happens, the blacklist proposal looks likely to allow F2FS to return to the distribution since it can be blacklisted by default. Read more

gitgeist: a git-based social network proof of concept

Are you tired of not owning the data or the platform you use for social postings? I know I am. It's hard to say when I "first" used a social network. I've been on email for about 30 years and one of the early ad-hoc forms of social networks were chain emails. Over the years I was asked to join all sorts of "social" things such as IRC, ICQ, Skype, MSN Messenger, etc. and eventually things like Orkut, MySpace, Facebook, etc. I'll readily admit that I'm not the type of person that happily jumps onto every new social bandwagon that appears on the Internet. I often prefer preserving the quietness of my own thoughts. That, though, hasn't stopped me from finding some meaningfulness participating in Twitter, Facebook, LinkedIn and more recently Google+. Twitter was in fact the first social network that I truly embraced. And it would've remained my primary social network had they not killed their own community by culling the swell of independently-developed Twitter clients that existed. That and their increased control of their API effectively made me look for something else. Right around that time Google+ was being introduced and many in the open source community started participating in that, in some ways to find a fresh place where techies can aggregate away from the noise and sometimes over-the-top nature of Facebook. Eventually I took to that too and started using G+ as my primary social network. That is, until Google recently decided to pull the plug on G+. While Google+ might not have represented a success for Google, it had become a good place for sharing information among the technically-inclined. As such, I found it quite useful for learning and hearing about new things in my field. Soon-to-be-former users of G+ have gone in all sorts of directions. Some have adopted a "c'mon guys, get over it, Facebook is the spot" attitude, others have adopted things like Mastodon, others have fallen back to their existing IDs on Twitter, and yet others, like me, are still looking. Read more