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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 13 min ago

Kernel prepatch 5.1-rc6

4 hours 29 min ago
The 5.1-rc6 kernel prepatch is out for testing. "It's Easter Sunday here, but I don't let little things like random major religious holidays interrupt my kernel development workflow. The occasional scuba trip? Sure. But everybody sitting around eating traditional foods? No. You have to have priorities."

Weekend stable kernel updates

Saturday 20th of April 2019 02:50:37 PM
The 5.0.9, 4.19.36, 4.14.113, and 4.9.170 stable kernel updates have all been released. These moderately large updates contain yet another set of important fixes.

[$] Implementing fully immutable files

Friday 19th of April 2019 02:57:19 PM
Like all Unix-like systems, Linux implements the traditional protection bits controlling who can access files in a filesystem (and what access they have). Fewer users, perhaps, are aware of a set of additional permission bits hidden away behind the chattr and lsattr commands. Among other things, these bits can make a file append-only, mark a file to be excluded from backups, cause a file's data to be automatically overwritten on deletion, or make a file immutable. The implementation of many of these features is incomplete at best, so perhaps it's not surprising that immutable files can still be changed in certain limited circumstances. Darrick Wong has posted a patch set changing this behavior, implementing a user-visible behavioral change that he describes as "an extraordinary way to destroy everything".

Security updates for Friday

Friday 19th of April 2019 12:45:45 PM
Security updates have been issued by Fedora (atomic-reactor and osbs-client), openSUSE (libqt5-qtbase, lxc, tar, wget, and xmltooling), Scientific Linux (java-1.8.0-openjdk and java-11-openjdk), SUSE (php5), and Ubuntu (znc).

[$] Tracking pages from get_user_pages()

Thursday 18th of April 2019 04:01:49 PM
As has been recently discussed here, developers for the filesystem and memory-management subsystems have been grappling for years with the problems posed by the get_user_pages() mechanism. This function maps memory into the kernel's address space for direct access by the kernel or peripheral devices, but that kind of access can create confusion in the filesystem layers, which may not be expecting that memory to be written to at any given time. A new patch set from Jérôme Glisse tries to chip away at a piece of the problem, but a complete solution is not yet in view.

Ubuntu 19.04 (Disco Dingo) released

Thursday 18th of April 2019 01:34:58 PM
Ubuntu 19.04, code named "Disco Dingo", has been released, along with the following flavors: Ubuntu Budgie, Kubuntu, Lubuntu, Ubuntu Kylin, Ubuntu MATE, Ubuntu Studio, and Xubuntu. "The Ubuntu kernel has been updated to the 5.0 based Linux kernel, our default toolchain has moved to gcc 8.3 with glibc 2.29, and we've also updated to openssl 1.1.1b and gnutls 3.6.5 with TLS1.3 support. Ubuntu Desktop 19.04 introduces GNOME 3.32 with increased performance, smoother startup animations, quicker icon load times and reduced CPU+GPU load. Fractional scaling for HiDPI screens is now available in Xorg and Wayland. Ubuntu Server 19.04 integrates recent innovations from key open infrastructure projects like OpenStack Stein, Kubernetes, and Ceph with advanced life-cycle management for multi-cloud and on-prem operations, from bare metal, VMware and OpenStack to every major public cloud." More information can be found in the release notes.

OpenSSH 8.0 released

Thursday 18th of April 2019 01:11:27 PM
OpenSSH 8.0 has been released with a bunch of new features and some bug fixes, including one for a security problem: "This release contains mitigation for a weakness in the scp(1) tool and protocol (CVE-2019-6111): when copying files from a remote system to a local directory, scp(1) did not verify that the filenames that the server sent matched those requested by the client. This could allow a hostile server to create or clobber unexpected local files with attacker-controlled content. This release adds client-side checking that the filenames sent from the server match the command-line request, The scp protocol is outdated, inflexible and not readily fixed. We recommend the use of more modern protocols like sftp and rsync for file transfer instead."

Security updates for Thursday

Thursday 18th of April 2019 12:58:58 PM
Security updates have been issued by CentOS (polkit), Gentoo (dovecot, libseccomp, and patch), openSUSE (aubio, blktrace, flac, lxc, lxcfs, pspp, SDL, sqlite3, and xen), Red Hat (java-1.8.0-openjdk, java-11-openjdk, and rh-maven35-jackson-databind), Scientific Linux (java-1.8.0-openjdk), Slackware (libpng), SUSE (python, python3, sqlite3, and xerces-c), and Ubuntu (ntfs-3g).

[$] LWN.net Weekly Edition for April 18, 2019

Thursday 18th of April 2019 01:09:43 AM
The LWN.net Weekly Edition for April 18, 2019 is available.

[$] Business models and open source

Wednesday 17th of April 2019 07:02:09 PM

One of the more lively sessions that was held at the 2019 Legal and Licensing Workshop (LLW) was Heather Meeker's talk on open-source business models and alternative licensing. As a lawyer in private practice, Meeker worked on a number of the alternative licenses that were drafted and presented over the last year or so. But she is also part of a venture capital (VC) firm that is exclusively investing in companies focused on open source, so she has experience in thinking about what kinds of models actually work for those types of businesses.

Stable kernel updates

Wednesday 17th of April 2019 02:38:02 PM
Stable kernels 5.0.8, 4.19.35, 4.14.112, and 4.9.169 have been released. They all contain important fixes and users should upgrade.

Security updates for Wednesday

Wednesday 17th of April 2019 02:31:53 PM
Security updates have been issued by CentOS (mod_auth_mellon), Debian (ghostscript and ruby2.3), openSUSE (dovecot22, gnuplot, and openwsman), Scientific Linux (mod_auth_mellon), SUSE (krb5, openexr, python3, and wget), and Ubuntu (firefox and openjdk-lts).

[$] An update on compliance for containers

Tuesday 16th of April 2019 08:07:57 PM

The inability to determine the contents of container images is a topic that annoys Dirk Hohndel. At last year's Legal and Licensing Workshop (LLW), he gave a presentation that highlighted the problem and some work he had been doing to combat it. At this year's LLW, he updated attendees on the progress that has been made and where he hopes things will go from here.

Security updates for Tuesday

Tuesday 16th of April 2019 02:53:33 PM
Security updates have been issued by Debian (cacti and libxslt), Fedora (pcsc-lite and samba), Gentoo (gnutls, phpmyadmin, and tiff), openSUSE (apache2, clamav, dovecot23, nodejs10, SDL, and webkit2gtk3), Red Hat (mod_auth_mellon and rh-python36-python), SUSE (firefox, nspr, nss and python), and Ubuntu (libxslt and webkit2gtk).

[$] Avoiding page reference-count overflows

Tuesday 16th of April 2019 12:49:34 AM
The 5.1-rc5 announcement mentioned "changes all over" and highlighted a number of the areas that had been touched. One thing that was not mentioned there was the addition of four patches fixing a security-related issue in the core memory-management subsystem. The vulnerability is sufficiently difficult to exploit that almost nobody should feel the need to rush out a kernel update, but it is still interesting to look at as a demonstration of how things can go wrong.

An eBPF overview series from Collabora

Monday 15th of April 2019 08:38:32 PM
Adrian Ratiu is posting a series of articles on the Collabora blog digging into the kernel's eBPF subsystem. The first two parts are available now: an introduction and a look at the virtual machine. "eBPF is a RISC register machine with a total of 11 64-bit registers, a program counter and a 512 byte fixed-size stack. 9 registers are general purpouse read-write, one is a read-only stack pointer and the program counter is implicit, i.e. we can only jump to a certain offset from it. The VM registers are always 64-bit wide (even when running inside a 32-bit ARM processor kernel!) and support 32-bit subregister addressing if the most significant 32 bits are zeroed - this will be very useful in part 4 when cross-compiling and running eBPF programs on embedded devices."

Stable kernel updates

Monday 15th of April 2019 07:10:44 PM
Stable kernels 5.0.7, 4.19.34, 4.14.111, and 4.9.168 were actually released last week, but the email wasn't sent. As usual they all contain important fixes and users should upgrade.

Security updates for Monday

Monday 15th of April 2019 03:02:13 PM
Security updates have been issued by Debian (graphicsmagick, jasper, and libssh2), Fedora (kernel, kernel-headers, kernel-tools, nodejs-simple-markdown, and php), openSUSE (netpbm and xen), and SUSE (audiofile, firefox, java-1_7_0-openjdk, libvirt, openssh, and systemd).

Kernel prepatch 5.1-rc5

Monday 15th of April 2019 02:02:28 PM
The 5.1-rc5 kernel prepatch is out for testing. "Nothing in here makes me feel uncomfortable about this release cycle so far. Knock wood."

[$] Expedited memory reclaim from killed processes

Friday 12th of April 2019 10:26:47 PM
Running out of memory puts a Linux system into a difficult situation; in the worst cases, there is often no way out other than killing one or more processes to reclaim their memory. This killing may be done by the kernel itself or, on systems like Android, by a user-space out-of-memory (OOM) killer process. Killing a process is almost certain to make somebody unhappy; the kernel should at least try to use that process's memory expeditiously so that, with luck, no other processes must die. That does not always happen, though, in current kernels. This patch set from Suren Baghdasaryan aims to improve the situation, but the solution that results in the end may take a different form.

More in Tux Machines

Review: Alpine Linux 3.9.2

Alpine Linux is different in some important ways compared to most other distributions. It uses different libraries, it uses a different service manager (than most), it has different command line tools and a custom installer. All of this can, at first, make Alpine feel a bit unfamiliar, a bit alien. But what I found was that, after a little work had been done to get the system up and running (and after a few missteps on my part) I began to greatly appreciate the distribution. Alpine is unusually small and requires few resources. Even the larger Extended edition I was running required less than 100MB of RAM and less than a gigabyte of disk space after all my services were enabled. I also appreciated that Alpine ships with some security features, like PIE, and does not enable any services it does not need to run. I believe it is fair to say this distribution requires more work to set up. Installing Alpine is not a point-n-click experience, it's more manual and requires a bit of typing. Not as much as setting up Arch Linux, but still more work than average. Setting up services requires a little more work and, in some cases, reading too since Alpine works a little differently than mainstream Linux projects. I repeatedly found it was a good idea to refer to the project's wiki to learn which steps were different on Alpine. What I came away thinking at the end of my trial, and I probably sound old (or at least old fashioned), is Alpine Linux reminds me of what got me into running Linux in the first place, about 20 years ago. Alpine is fast, light, and transparent. It offered very few surprises and does almost nothing automatically. This results in a little more effort on our parts, but it means that Alpine does not do things unless we ask it to perform an action. It is lean, efficient and does not go around changing things or trying to guess what we want to do. These are characteristics I sometimes miss these days in the Linux ecosystem. Read more

today's howtos

Linux v5.1-rc6

It's Easter Sunday here, but I don't let little things like random major religious holidays interrupt my kernel development workflow. The occasional scuba trip? Sure. But everybody sitting around eating traditional foods? No. You have to have priorities. There's only so much memma you can eat even if your wife had to make it from scratch because nobody eats that stuff in the US. Anyway, rc6 is actually larger than I would have liked, which made me go back and look at history, and for some reason that's not all that unusual. We recently had similar rc6 bumps in both 4.18 and 5.0. So I'm not going to worry about it. I think it's just random timing of pull requests, and almost certainly at least partly due to the networking pull request in here (with just over a third of the changes being networking-related, either in drivers or core networking). Read more Also: Linux 5.1-rc6 Kernel Released In Linus Torvalds' Easter Day Message

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