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  82 <div class="PageHeadline">
  83 <h1>Welcome to LWN.net</h1>
  84 </div>
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  86 <div class="pure-u-1">
  87        <blockquote style="margin-top: 0">
  88        LWN.net is a reader-supported news site dedicated to producing the best
  89        coverage from within the Linux and free software development communities.
  90        See <a href="/op/FAQ.lwn">the LWN FAQ</a> for more information, and
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  92        access and support our activities.
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  94        <p>
  95        </div><div class="pure-u-1 pure-u-md-1-2 fp-feature">
  96 <div class="Headline"><b>[<font class="Subscription">$</font>] Writing network flow dissectors in BPF</b></div>
  97
  98         <div class="BlurbListing">
  99         <font size="-1">[Kernel] Posted Sep 6, 2018 15:59 UTC (Thu) by corbet</font>
 100         <p>
 101         Network packet headers contain a great deal of information, but the
 102 kernel often only needs a subset of that information to be able to perform
 103 filtering or associate any given packet with a flow. The piece of code that
 104 follows the different layers of packet encapsulation to find the important
 105 data is called a flow dissector. In current Linux kernels, the <a
 106 href="https://elixir.bootlin.com/linux/v4.18.6/source/net/core/flow_dissector.c">flow
 107 dissector</a>
 108 is written in C. A <a href="/Articles/763938/">patch set</a> has been
 109 proposed recently to implement it in BPF with the clear goal of improving
 110 security, flexibility, and maybe even performance.
 111
 112         <p>
 113         <a href="/Articles/764200/">Full Story</a> (<a href="/Articles/764200/#Comments">comments: 1</a>)
 114 <p>
 115 </div>
 116 </div><div class="pure-u-1 pure-u-md-11-24">
 117 <div class="Headline"><b>The Hidden Benefit of Giving Back to Open Source Software (Working Knowledge)</b></div>
 118
 119         <div class="BlurbListing">
 120         <font size="-1">[Briefs] Posted Sep 6, 2018 16:56 UTC (Thu) by corbet</font>
 121         <p>
 122         The Harvard Business School's "Working Knowledge" site has <a
 123 href="https://hbswk.hbs.edu/item/the-hidden-benefit-of-giving-back-to-open-source-software">an
 124 article</a> arguing that it can pay for companies to allow their developers
 125 to contribute back to the projects whose software they use.
 126 "<span>And that presents an interesting dilemma for firms that rely heavily
 127 on open source. Should they allow employees on company time to make updates
 128 and edits to the software for community use that could be used by
 129 competitors? New research by Assistant Professor Frank Nagle, a member of
 130 the Strategy Unit at Harvard Business School, shows that paying employees
 131 to contribute to such software boosts the company’s productivity from using
 132 the software by as much as 100 percent, when compared with free-riding
 133 competitors.</span>"
 134         <p>
 135         <a href="/Articles/764321/">Comments (3 posted)</a>
 136 <p>
 137 </div>
 138 </div>
 139 <div class="pure-u-1 pure-u-md-1-2 fp-feature">
 140 <div class="Headline"><b>[<font class="Subscription">$</font>] LWN.net Weekly Edition for September 6, 2018</b></div>
 141
 142         <font size="-1">Posted Sep 6, 2018 3:03 UTC (Thu)</font><p>
 143         The LWN.net Weekly Edition for September 6, 2018 is available.
 144 <p>
 145         <b>Inside this week's LWN.net Weekly Edition</b>
 146         <ul>
 147 <li> <a href="/Articles/763789/">Front</a>: Life behind the tinfoil curtain; User-space Spectre protection; fs-verity; IDA; Julia part 2; GopherCon.
 148             <li> <a href="/Articles/763791/">Briefs</a>: Tink; Kernel &amp; Maintainer Summit topics; LMDE 3; Firefox 62; GNOME 3.30; Quotes; ...
 149             <li> <a href="/Articles/763792/">Announcements</a>: Newsletters; events; security updates; kernel patches; ...
 150             </ul>
 151 <a href="/Articles/763789/">Read more</a>
 152 <p>
 153
 154 </div><div class="pure-u-1 pure-u-md-11-24">
 155 <div class="Headline"><b>Security updates for Thursday</b></div>
 156
 157         <div class="BlurbListing">
 158         <font size="-1">[Security] Posted Sep 6, 2018 13:55 UTC (Thu) by jake</font>
 159         <p>
 160         Security updates have been issued by <b>Debian</b> (curl, gdm3, git-annex, lcms2, and sympa), <b>Fedora</b> (discount, dolphin-emu, gd, obs-build, osc, tcpflow, and yara), <b>openSUSE</b> (wireshark), <b>Slackware</b> (curl, firefox, ghostscript, and thunderbird), <b>SUSE</b> (apache-pdfbox, curl, dovecot22, and libvirt), and <b>Ubuntu</b> (libtirpc).
 161
 162         <p>
 163         <a href="/Articles/764300/">Full Story</a> (<a href="/Articles/764300/#Comments">comments: none</a>)
 164 <p>
 165 </div>
 166 </div>
 167 <div class="pure-u-1 pure-u-md-1-2 fp-feature">
 168 <div class="Headline"><b>[<font class="Subscription">$</font>] Life behind the tinfoil curtain</b></div>
 169
 170         <div class="BlurbListing">
 171         <font size="-1">[Security] Posted Sep 5, 2018 22:11 UTC (Wed) by jake</font>
 172         <p>
 173         <p>
 174 Security and convenience rarely go hand-in-hand, but if your job (or life)
 175 requires extraordinary care against potentially targeted attacks, the
 176 security side of that tradeoff may win out.  If so, running a system like
 177 <a href="https://www.qubes-os.org/">Qubes&nbsp;OS</a> on your desktop or <a
 178 href="https://copperhead.co/">CopperheadOS</a> on your phone might make sense,
 179 which is just what Konstantin Ryabitsev, Linux Foundation (LF) director of IT
 180 security, has done.  He reported on the experience in a <a
 181 href="https://www.youtube.com/watch?v=8cU4hQg6GvU&index=6&list=PLbzoR-pLrL6rOT6m50HdJFYUHyvA9lurI&t=0s">talk
 182 [YouTube video]</a> entitled "Life Behind the Tinfoil Curtain" at the 2018
 183 <a
 184 href="https://events.linuxfoundation.org/events/linux-security-summit-north-america-2018/">Linux
 185 Security Summit North America</a>.
 186
 187         <p>
 188         <a href="/Articles/764048/">Full Story</a> (<a href="/Articles/764048/#Comments">comments: 9</a>)
 189 <p>
 190 </div>
 191 </div><div class="pure-u-1 pure-u-md-11-24">
 192 <div class="Headline"><b>GNOME 3.30 released</b></div>
 193
 194         <div class="BlurbListing">
 195         <font size="-1">[Development] Posted Sep 5, 2018 21:17 UTC (Wed) by ris</font>
 196         <p>
 197         The GNOME Project has announced the release of GNOME 3.30
 198 "Almería". "<span>This release brings automatic updates in Software, more
 199 games, and a new Podcasts application. Improvements to core GNOME
 200 applications include a refined location and search bar in Files, a
 201 [Thunderbolt] panel in Settings, support for remoting using RDP in Boxes, and
 202 many more.</span>" The <a
 203 href="https://help.gnome.org/misc/release-notes/3.30/">release notes</a>
 204 contain more information.
 205
 206         <p>
 207         <a href="/Articles/764219/">Full Story</a> (<a href="/Articles/764219/#Comments">comments: none</a>)
 208 <p>
 209 </div>
 210 </div>
 211 <div class="pure-u-1 pure-u-md-1-2 fp-feature">
 212 <div class="Headline"><b>[<font class="Subscription">$</font>] Strengthening user-space Spectre v2 protection</b></div>
 213
 214         <div class="BlurbListing">
 215         <font size="-1">[Kernel] Posted Sep 5, 2018 21:47 UTC (Wed) by corbet</font>
 216         <p>
 217         The Spectre variant 2 vulnerability allows the speculative execution of
 218 incorrect (in an attacker-controllable way) indirect branch predictions,
 219 resulting in
 220 the ability to exfiltrate information via side channels.  The kernel has
 221 been reasonably well protected against this variant since shortly after its
 222 disclosure in January.  It is, however, possible for user-space processes
 223 to use Spectre v2 to attack each other; thus far, the mainline kernel has
 224 offered relatively little protection against such attacks.  A recent <a
 225 href="/ml/linux-kernel/nycvar.YFH.7.76.1809041619510.15880@cbobk.fhfr.pm/">proposal</a>
 226 from Jiri Kosina may change that situation, but there are still some
 227 disagreements around the details.
 228
 229         <p>
 230         <a href="/Articles/764209/">Full Story</a> (<a href="/Articles/764209/#Comments">comments: 1</a>)
 231 <p>
 232 </div>
 233 </div><div class="pure-u-1 pure-u-md-11-24">
 234 <div class="Headline"><b>Firefox 62.0 released</b></div>
 235
 236         <div class="BlurbListing">
 237         <font size="-1">[Development] Posted Sep 5, 2018 17:31 UTC (Wed) by ris</font>
 238         <p>
 239         Mozilla has released Firefox 62.0, with several new features. The Firefox
 240 Home (default New Tab) allows users to display up to 4 rows of top sites,
 241 Pocket stories, and highlights; for those using containers there is menu
 242 option to reopen a tab in a different container; Firefox 63 will remove all
 243 trust for Symantec-issued certificates, and it is optional in Firefox
 244 62; FreeBSD support for WebAuthn was added; and more. See the <a
 245 href="https://www.mozilla.org/en-US/firefox/62.0/releasenotes/">release
 246 notes</a> for details.
 247         <p>
 248         <a href="/Articles/764202/">Comments (none posted)</a>
 249 <p>
 250 </div>
 251 </div>
 252 <div class="pure-u-1 pure-u-md-1-2 fp-feature">
 253 <div class="Headline"><b>[<font class="Subscription">$</font>] Learning about Go internals at GopherCon</b></div>
 254
 255         <div class="BlurbListing">
 256         <font size="-1">[Front] Posted Sep 5, 2018 19:20 UTC (Wed) by jake</font>
 257         <p>
 258         <p><a href="https://www.gophercon.com/">GopherCon</a> is the major
 259 conference for the <a href="https://golang.org/">Go language</a>, attended
 260 by 1600
 261 dedicated "gophers", as the members of its community like to call
 262 themselves.  Held for the last five years in Denver, it attracts programmers,
 263 open-source contributors, and technical managers from all over North
 264 America and the world. GopherCon's highly-technical program is an intense
 265 mix of Go internals and programming tutorials, a few of which we will
 266 explore in this article.
 267 <p>
 268 Subscribers can read on for a report from GopherCon by guest author Josh
 269 Berkus.
 270
 271         <p>
 272         <a href="/Articles/764131/">Full Story</a> (<a href="/Articles/764131/#Comments">comments: 10</a>)
 273 <p>
 274 </div>
 275 </div><div class="pure-u-1 pure-u-md-11-24">
 276 <div class="Headline"><b>A set of stable kernels</b></div>
 277
 278         <div class="BlurbListing">
 279         <font size="-1">[Kernel] Posted Sep 5, 2018 15:15 UTC (Wed) by ris</font>
 280         <p>
 281         Greg Kroah-Hartman has released stable kernels <a
 282 href="/Articles/764185/">4.18.6</a>, <a
 283 href="/Articles/764186/">4.14.68</a>, <a
 284 href="/Articles/764187/">4.9.125</a>, <a
 285 href="/Articles/764188/">4.4.154</a>, and <a
 286 href="/Articles/764189/">3.18.121</a>. They all contain important fixes and
 287 users should upgrade.
 288         <p>
 289         <a href="/Articles/764184/">Comments (none posted)</a>
 290 <p>
 291 </div>
 292 </div>
 293 <div class="pure-u-1 pure-u-md-1-2 fp-feature">
 294 <div class="Headline"><b>[<font class="Subscription">$</font>] An introduction to the Julia language, part 2</b></div>
 295
 296         <div class="BlurbListing">
 297         <font size="-1">[Development] Posted Sep 4, 2018 15:57 UTC (Tue) by jake</font>
 298         <p>
 299         <p><a
 300 href="/Articles/763626/">Part 1</a> of this series introduced
 301 the <a href="http://julialang.org/">Julia</a> project's goals and
 302 development process, along with
 303 the language syntax, including the basics of control flow, data
 304 types, and, in more detail, how to work with arrays. In this part,
 305 user-defined functions and the central
 306 concept of multiple dispatch are described. It will also survey Julia's
 307 module and
 308 package system, cover some syntax features, show how to make
 309 plots, and briefly dip into macros and distributed computing.
 310
 311         <p>
 312         <a href="/Articles/764001/">Full Story</a> (<a href="/Articles/764001/#Comments">comments: 7</a>)
 313 <p>
 314 </div>
 315 </div><div class="pure-u-1 pure-u-md-11-24">
 316 <div class="Headline"><b>Security updates for Wednesday</b></div>
 317
 318         <div class="BlurbListing">
 319         <font size="-1">[Security] Posted Sep 5, 2018 15:01 UTC (Wed) by ris</font>
 320         <p>
 321         Security updates have been issued by <b>Debian</b> (lcms2), <b>openSUSE</b> (yubico-piv-tool), <b>Oracle</b> (kernel), and <b>SUSE</b> (cobbler and kvm).
 322
 323         <p>
 324         <a href="/Articles/764182/">Full Story</a> (<a href="/Articles/764182/#Comments">comments: none</a>)
 325 <p>
 326 </div>
 327 </div>
 328 <div class="pure-u-1 pure-u-md-1-2 fp-feature">
 329 <div class="Headline"><b>[<font class="Subscription">$</font>] IDA: simplifying the complex task of allocating integers</b></div>
 330
 331         <div class="BlurbListing">
 332         <font size="-1">[Kernel] Posted Sep 4, 2018 0:15 UTC (Tue) by corbet</font>
 333         <p>
 334         It is common for kernel code to generate unique integers for identifiers.
 335 When one plugs in a flash drive, it will show up as
 336 <tt>/dev/sdN</tt>; that <tt>N</tt> (a letter derived from a
 337 number) must be generated in the
 338 kernel, and it should not already be in use for another drive or unpleasant
 339 things will happen.  One might think that generating such numbers would not
 340 be a difficult task, but that turns out not to be the case, especially in
 341 situations where many numbers must be tracked.  The IDA (for "ID
 342 allocator", perhaps) API exists to handle this specialized task.  In past
 343 kernels, it has managed to make the process of getting an unused number
 344 surprisingly
 345 complex; the 4.19 kernel has a new IDA API that simplifies things
 346 considerably.
 347
 348         <p>
 349         <a href="/Articles/764057/">Full Story</a> (<a href="/Articles/764057/#Comments">comments: 8</a>)
 350 <p>
 351 </div>
 352 </div><div class="pure-u-1 pure-u-md-11-24">
 353 <div class="Headline"><b>Security updates for Tuesday</b></div>
 354
 355         <div class="BlurbListing">
 356         <font size="-1">[Security] Posted Sep 4, 2018 15:14 UTC (Tue) by ris</font>
 357         <p>
 358         Security updates have been issued by <b>openSUSE</b> (ImageMagick, libressl, postgresql10, spice, and spice-gtk), <b>Red Hat</b> (collectd, kernel, Red Hat Gluster Storage, Red Hat Virtualization, RHGS WA, rhvm-appliance, and samba), and <b>SUSE</b> (crowbar, crowbar-core, crowbar-ha, crowbar-openstack, crowbar-ui, kernel, spice, and spice-gtk).
 359
 360         <p>
 361         <a href="/Articles/764130/">Full Story</a> (<a href="/Articles/764130/#Comments">comments: none</a>)
 362 <p>
 363 </div>
 364 </div>
 365 <div class="pure-u-1 pure-u-md-1-2 fp-feature">
 366 <div class="Headline"><b>[<font class="Subscription">$</font>] Protecting files with fs-verity</b></div>
 367
 368         <div class="BlurbListing">
 369         <font size="-1">[Kernel] Posted Aug 30, 2018 18:50 UTC (Thu) by corbet</font>
 370         <p>
 371         The developers of the Android system have, among their many goals, the wish
 372 to better protect Android devices against persistent compromise.  It is bad
 373 if a device is taken over by an attacker; it's worse if it remains
 374 compromised even after a reboot.  Numerous mechanisms for ensuring the
 375 integrity of  installed system files have been proposed and implemented
 376 over the years.  But it seems there is always room for one more; to fill
 377 that space, the <a
 378 href="/ml/linux-fsdevel/20180824161642.1144-1-ebiggers@kernel.org/">fs-verity</a>
 379 mechanism is being proposed as a way to protect individual files from
 380 malicious modification.
 381
 382         <p>
 383         <a href="/Articles/763729/">Full Story</a> (<a href="/Articles/763729/#Comments">comments: 6</a>)
 384 <p>
 385 </div>
 386 </div><div class="pure-u-1 pure-u-md-11-24">
 387 <div class="Headline"><b>Topics sought for the Kernel and Maintainer Summits</b></div>
 388
 389         <div class="BlurbListing">
 390         <font size="-1">[Kernel] Posted Sep 3, 2018 19:07 UTC (Mon) by corbet</font>
 391         <p>
 392         The annual Maintainer and Kernel Summits will be held in Vancouver, BC on
 393 November&nbsp;12 to&nbsp;15, in conjunction with the Linux Plumbers Conference.
 394 The program committee is looking for topics for both summits; read on for
 395 details on how to submit ideas and, perhaps, get an invitation to the
 396 Maintainer Summit.
 397
 398         <p>
 399         <a href="/Articles/764055/">Full Story</a> (<a href="/Articles/764055/#Comments">comments: none</a>)
 400 <p>
 401 </div>
 402 </div>
 403 <div class="pure-u-1 pure-u-md-1-2 fp-feature">
 404 <div class="Headline"><b>LWN.net Weekly Edition for August 30, 2018</b></div>
 405
 406         <font size="-1">Posted Aug 30, 2018 1:06 UTC (Thu)</font><p>
 407         The LWN.net Weekly Edition for August 30, 2018 is available.
 408 <p>
 409         <b>Inside this week's LWN.net Weekly Edition</b>
 410         <ul>
 411 <li> <a href="/Articles/763252/">Front</a>: Julia; C considered dangerous; 4.19 Merge window; I/O controller throughput; KDE onboarding; Dat.
 412             <li> <a href="/Articles/763254/">Briefs</a>: OpenSSH 7.8; 4.19-rc1; Which stable?; Netdev 0x12; Bison 3.1; Quotes; ...
 413             <li> <a href="/Articles/763255/">Announcements</a>: Newsletters; events; security updates; kernel patches; ...
 414             </ul>
 415 <a href="/Articles/763252/">Read more</a>
 416 <p>
 417
 418 </div><div class="pure-u-1 pure-u-md-11-24">
 419 <div class="Headline"><b>Security updates for Monday</b></div>
 420
 421         <div class="BlurbListing">
 422         <font size="-1">[Security] Posted Sep 3, 2018 15:41 UTC (Mon) by ris</font>
 423         <p>
 424         Security updates have been issued by <b>Debian</b> (dojo, libtirpc, mariadb-10.0, php5, ruby-json-jwt, spice, spice-gtk, tomcat8, and trafficserver), <b>Fedora</b> (ghc-hakyll, ghc-hs-bibutils, ghostscript, mariadb, pandoc-citeproc, phpMyAdmin, and xen), <b>Mageia</b> (java-1.8.0-openjdk, libarchive, libgd, libraw, libxcursor, mariadb, mercurial, openssh, openssl, poppler, quazip, squirrelmail, and virtualbox), <b>openSUSE</b> (cobbler, libressl, wireshark, and zutils), and <b>SUSE</b> (couchdb, java-1_7_0-ibm, java-1_7_1-ibm, OpenStack, and spice).
 425
 426         <p>
 427         <a href="/Articles/764046/">Full Story</a> (<a href="/Articles/764046/#Comments">comments: none</a>)
 428 <p>
 429 </div>
 430 </div>
 431 <div class="pure-u-1 pure-u-md-1-2 fp-feature">
 432 <div class="Headline"><b>[<font class="Subscription">$</font>] Measuring (and fixing) I/O-controller throughput loss</b></div>
 433
 434         <div class="BlurbListing">
 435         <font size="-1">[Kernel] Posted Aug 29, 2018 21:20 UTC (Wed) by corbet</font>
 436         <p>
 437         Many services, from web hosting and video streaming to cloud storage,
 438 need to move data to and from storage.  They also often require that each per-client
 439 I/O flow be guaranteed a non-zero amount of bandwidth and a bounded latency. An
 440 expensive way to provide these guarantees is to over-provision
 441 storage resources, keeping each resource underutilized, and thus
 442 have plenty of bandwidth available for the few I/O flows dispatched to
 443 each medium. Alternatively one can use an I/O controller.  Linux provides
 444 two mechanisms designed to throttle some I/O streams to allow others to
 445 meet their bandwidth and latency requirements.  These mechanisms work, but
 446 they come at a cost: a loss of as much as 80% of total available I/O
 447 bandwidth.  I have run some tests to demonstrate this problem; some
 448 upcoming improvements to the <a href="/Articles/601799/">bfq I/O
 449 scheduler</a> promise to improve the situation considerably.
 450
 451         <p>
 452         <a href="/Articles/763603/">Full Story</a> (<a href="/Articles/763603/#Comments">comments: 4</a>)
 453 <p>
 454 </div>
 455 </div><div class="pure-u-1 pure-u-md-11-24">
 456 <div class="Headline"><b>Kernel prepatch 4.19-rc2</b></div>
 457
 458         <div class="BlurbListing">
 459         <font size="-1">[Kernel] Posted Sep 2, 2018 22:29 UTC (Sun) by corbet</font>
 460         <p>
 461         The <a href="/Articles/763988/">4.19-rc2</a> kernel prepatch is out for
 462 testing.
 463 "<span>As usual, the rc2 release is pretty small. People are taking a
 464 breather after the merge window, and it takes a bit of time for bug
 465 reports to start coming in and get identified.</span>"
 466         <p>
 467         <a href="/Articles/763987/">Comments (none posted)</a>
 468 <p>
 469 </div>
 470 </div>
 471 <p><a href="/Articles/?offset=6">--&gt; More news items</a>
 472
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