Search Results: "pm"

26 April 2016

Michal Čihař: Weekly phpMyAdmin contributions 2016-W16

Last week was again focused on bug fixing due to increased amount of received bug reports on 4.6.0 release. Fortunately most of the annoying bugs are already fixed in git and will be soon released as 4.6.1. Another bigger task which was started last week was wiki migration. So far we've been using own wiki running MediaWiki and we're migrating it to GitHub wiki. The wiki on GitHub is way simpler, but it seems as better choice for us. During the migration all user documentation will be merged into our documentation, so that it's all in one place and wiki will be targeted on developers. Handled issues:

Filed under: English phpMyAdmin 2 comments

Reproducible builds folks: Reproducible builds: week 52 in Stretch cycle

What happened in the Reproducible Builds effort between April 17th and April 23rd 2016: Toolchain fixes Thomas Weber uploaded lcms2/2.7-1 which will not write uninitialized memory when writing color names. Original patch by Lunar. The GCC 7 development phase has just begun, so Dhole reworked his patch to make gcc use SOURCE_DATE_EPOCH if set which prompted interesting feedback, but it has not been merged yet. Alexis Bienven e submitted a patch for sphinx to strip Python object memory addresses from the generated documentation. Packages fixed The following packages have become reproducible due to changes in their build dependencies: cobertura, commons-pool, easymock, eclipselink, excalibur-logkit, gap-radiroot, gluegen2, jabref, java3d, jcifs, jline, jmock2, josql, jtharness, libfann, libgroboutils-java, libjemmy2-java, libjgoodies-binding-java, libjgrapht0.8-java, libjtds-java, liboptions-java, libpal-java, libzeus-jscl-java, node-transformers, octave-msh, octave-secs2d, openmama, rkward. The following packages have become reproducible after being fixed: Patches submitted that have not made their way to the archive yet: tests.reproducible-builds.org diffoscope development diffoscope 52 was released with changes from Mattia Rizzolo, h01ger, Satyam Zode and Reiner Herrmann, who also did the release. Notable changes included: As usual, diffoscope 52 is available on Debian, Archlinux and PyPI, other distributions will hopefully soon update. Package reviews 28 reviews have been added, 11 have been updated and 94 have been removed in this week. 14 FTBFS bugs were reported by Chris Lamb (one being was a duplicate of a bug filed by Sebastian Ramacher an hour earlier). Misc. This week's edition was written by Lunar, Holger 'h01ger' Levsen and Chris Lamb and reviewed by a bunch of Reproducible builds folks on IRC.

Dirk Eddelbuettel: RcppMgsPack 0.1.0

Over the last few months, I have been working casually on a new package to integrate MessagePack with R. What is MessagePack, you ask? To quote its website, "It's like JSON, but fast and small." Or in more extended terms:
MessagePack is an efficient binary serialization format. It lets you exchange data among multiple languages like JSON. But it's faster and smaller. Small integers are encoded into a single byte, and typical short strings require only one extra byte in addition to the strings themselves.
Now, serialization formats are a dime a dozen: JSON, BSON, Protocol Buffers, CaptnProto, Flatbuffer. The list goes on and on. So why another? In a nutshell: "software ecosystems". I happen to like working with Redis, and within the world of Redis, MessagePack is a first-class citizen supported by things close to the core like the embedded Lua interpreter, as well as fancy external add-ons such as the Redis Desktop Manager GUI. So nothing overly fundamentalist here, but a fairly pragmatic choice based on what happens to fit my needs. Plus, having worked on and off with Protocol Buffers for close to a decade, the chance of working with something not requiring a friggin' schema compiler seemed appealing for a chance. So far, we have been encoding a bunch of data streams at work via MessagePack into Redis (and of course back). It works really well---header-only C++11 libraries for the win. I'll provide an updated RcppRedis which uses this (if present) in due course. For now and the foreseeable future, this RcppMsgPack package will live only on the ghrr drat repository. To make RcppMsgPack work, I currently have to include the MessagePack 1.4.0 headers. A matching package for this version of the headers is in Debian but so far only in experimental. Once this hits the mainline repository I can depend on it, and upload a (lighter, smaller) RcppMsgPack to CRAN. Until then, please just do
## install drat if not present
if (!require(drat)) install.packages("drat")
## use drat to select ghrr repo
drat::addRepo("ghrr")
## install RcppMsgPack
install.packages("RcppMsgPack")
More details, issue tickets etc are at the GitHub repository.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

25 April 2016

Antoine Beaupr : My free software activities, April 2016

Debian Long Term Support (LTS) This is my 5th month working on Debian LTS, started by Raphael Hertzog at Freexian. This is my largest month so far, in which I worked on completing the Xen and NSS packages updates from last month, but also spent a significant amount of time working on phpMyAdmin and libidn.

Updates to NSS and Xen completed This basically consisted on following up on the reviews from other security people. I basically continued building up on Brian's work and tested the package on a test server at Koumbit, which seems to have survived well the upgrade. The details are in this post to the debian-lts mailing list. As for NSS, the package was mostly complete, but I forgot to ship the tests for some reason, so I added them back. I also wrote the release team to see if it was possible to update NSS to the same version in all suites. Unfortunately, this issue is still pending, but I still hope we can find better ways of managing that package in the long term.

IDN and phpMyAdmin Most of my time this month was spent working on IDN and phpMyAdmin. Unfortunately, it turns out that someone else had worked on the libidn package. This is partly my fault: I forgot to check in the dsa-needed.txt file for assignment before working on the package. But considering how in flux the workflow currently is with the switch between the main security team and the LTS team for the wheezy maintenance, I don't feel too bad. Still, I prepared a package which was a bit more painful than it should have been because of GNUlib. I didn't even know about GNUlib before, oddly enough, and after that experience, I feel that it should just not exist at all anymore. I have filed a bug to remove that dependency at the very least, but I do not clearly see how such a tool is necessary on Debian at this point in time. But phpMyAdmin, no one had worked on that. And I understand why: even though it's a very popular package, there were quite a few outstanding issues (8!) in Wheezy, with 10-15 patches to be ported. Plus, it's ... well, PHP. And old PHP at that, with parts of it with modern autoloader classes, and other with mixed HTML and PHP content, require (and not require_once) and all sorts of nasty things you still find in the PHP universe. I nevertheless managed to produce a new Debian package for wheezy and test it on Koumbit's test servers. Hopefully, that can land into Wheezy soon.

Long term software support I am a little worried that we are, both in Jessie and Wheezy sitting in between stable releases for phpMyAdmin, something that is a recurring issue for a lot of packages in Debian stable or LTS. Sometimes, it just happens that the version that happens to be in Debian testing when it is released as stable is just not a supported release upstream. It's the case for phpMyAdmin in Jessie (4.3, whereas 4.0 and 4.4 are supported) and Wheezy (3.4, although it's unclear how long that was supported upstream). But even if the next Debian stable (Stretch), would pick a stable release upstream, there is actually no phpMyAdmin release that has a support window as long as Debian stable (roughly 3 years), let alone as long as Debian LTS (5 years). This is a similar problem with NSS: upstream is simply not supporting their product in the long term, or at least not in the terms we are used to in the Debian community (ie. only security fixes or regressions). This is, in my opinion, a real concern for the reliability and sustainability of the computing infrastructure we are creating. While some developers are of the opinion that software older than 18 months is too old, here we are shipping hardware and software in space or we have Solaris, which is supported for 16 years! Now that is a serious commitment and something we can rely on. 18 months is really, really, a tiny short time in the history of our civilization. I know computer programmers and engineers like to think of themselves in elitist terms, that they are changing the world every other year. But the truth is that things have not changed much in the last 4 decades where computing has existed, both in terms of security or functionality. Two quotes from my little quotes collection come to mind here:
Software gets slower faster than hardware gets faster. - Wirth's law The future is already here it's just not very evenly distributed. - William Gibson
Because of course, the response to my claims that computing is not really advancing is "but look! we have supercomputers in our pockets now!" Yes, of course, we do have those fancy phones and they are super-connected, but they are a threat to our fundamental rights and freedom. And those glittering advances always pale in comparison to what could be done if we wouldn't be wasting our time rewriting the same software over and over again on different, often proprietary, platforms, simply because of the megalomaniac fantasies of egoistic programmers. It would be great to build something that lasts, for a while. Software that does not need to be updated every 16 months. You'd think that something as basic as a screensaver release could survive what is basically the range of human infancy. Yet it seems we like to run mindlessly in the minefield of software development, one generation following the other without questioning the underlying assumption of infinite growth that permeates our dying civilization. I have talked about this before of course, but working with the LTS project just unnerves me so bad that I just needed to let out another rant. (For the record, I really have a lot of respect for JWZ and all the work he has done in the free software world. I frequently refer to his "no-bullshit" backup guide and use Xscreensaver daily. But I do think he was wrong in this case: asking Debian to remove Xscreensaver is just too much. The response from the maintainer was exemplary of how to handle such issues in the future. I restarted Xscreensaver after the stable update, and the message is gone, and things are still all fine. Thanks JWZ and Tormod for keeping things rolling.)

Other free software work With that in mind, I obviously didn't stop doing other computing work this month. In fact, I did a lot of work to try to generally fix the internet, that endless and not-quite-gratifying hobby so many of us are destroying our bodies to accomplish.

Build tools I have experimented a bit more with different build tools. I got worried because at some point cowbuilder got orphaned and I figured I could refresh the way I build packages for LTS. I looked into sbuild, but that ended up not bringing much improvements over my current cowbuilder setup (which I really need to document better). I was asked by the new maintainer to open a bug report to make such setups easier by guessing the basepath better, so we'll see how that goes. I did enjoy the simplicity of gitpkg and discovered cowpoke which made it about 2 times faster to build packages because I could use another server to build larger packages. I also found that gitpkg doesn't use -n by default when calling gzip, which makes it harder to reproduce tarballs when they are themselves built reproducibly, which is the case for Github tarballs (really nice of them). So I filed bug #820842 about that. It would be pretty awesome if such buildds would be available for Debian Developers to do their daily tasks. It could simply be a machine that would spin up a chroot with cowbuilder or it could even be a full, temporary VM although that would take way more resources than a simple VM with a cowbuilder setup. In the meantime, I should probably look at whalebuilder as an alternative to cowbuilder. It is a tool that supports building packages within a Docker chroot, which means that packages are built from a clean environment like pbuilder, and using COW optimisations but also without privileges or network access, which is a huge plus especially when you build untrusted packages.

Ikiwiki admonitions I have done some work to implement Moinmoin-like admonitions in Ikiwiki, something I am quite happy about since it's something I was really missing about Moinmoin. Admonitions bring a really nice way to outline certain blocks with varying severity levels and distinct styles. For example:
Admonitions are great!
This was done with a macro, but basically, since Markdown allows more or less arbitrary HTML, this can also be done with the <div> tag. I like that we don't have a new weird markup here. Yet, I still liked the sub-parser feature of MoinMoin, something that can be implemented in Ikiwiki, but it's a little more clunky. Normally, you'd probably do this with the inline macro and subpages, but it's certainly less intuitive that directly inlined content.

Ereader I got a new e-reader! I was hesitant between the Kobo Aura H20 and the Kobo Glo HD, which were the ones available at Bestbuy. So I bought both and figured I would return the other. That was a painful decision! In the end, both machines are pretty nice:
  • Aura H2O
    • Pros:
      • waterproof
      • larger screen (makes it easier to see web pages and better for the eyes)
      • naturally drawn to it
    • Cons:
      • heavier
      • larger (fits in outside pocket though)
      • port cover finicky
      • more expensive (180$) - prices may go down in future
  • Aura Glo HD
    • Pros
      • smaller (fits in inside pocket of both coats)
      • better resolution in theory (can't notice in practice)
      • cheaper (100$)
      • may be less common on the future (larger models more common? just a guess)
    • Cons
      • no SD card
      • smaller screen
      • power button in the middle
... but in the end, I ended up settling down on the Glo, mostly for the price. Heck, I saved around 100$, so for that amount, I could have gotten two machines so that if one breaks I would still have the other. I have ordered a cover for it on Deal Extreme about two weeks ago, and it still hasn't arrived. I suspect it's going to take a few more months to get there, by which point I may have changed e-reader again. Note that both e-readers needed an update to calibre, so I started working on a calibre backport (#818309) which I will complete soon. So anyways, I looked into better ways of transferring articles from the web to the e-reader, something which I do quite a bit to avoid spending too much time on the computer. Since the bookmark manager I use (Bookie) is pretty much dead, I started looking at other alternatives. And partly inspired by Framasoft's choice of Wallabag for their bookmarking service (Framabag), I started to look into that software, especially since my friend who currently runs the Bookie instance is thinking of switching to Wallabag as well. It seems the simplest way to browse articles remotely through a standard protocol is by implementing OPDS support in Wallabag. OPDS is a standard developed in part by the Internet Archive and it allows for browsing book collections and downloading them. Articles and bookmarks would then be presented as individual books that would be accessible from any OPDS-compatible device. Unfortunately, the Kobo e-readers don't support OPDS out of the box: you need to setup some OPDS-compatible reader like Koreader. And that I found nearly impossible to do: I was able to setup KSM (the "start menu", not to be confused with that KSM), but not Koreader in KSM. Besides, I do not want a separate OS running here on the tablet: I just want to start Koreader every once in a while. KSM just starts another system when you reboot the e-reader, something which is not really convenient on the Kobo. Basically, I just want to add Koreader as a tile in the home screen on the e-reader. I found the documentation on that topic to be sparse and hard to follow. It is often dispersed across multiple forum threads and involves uploading random binaries, often proprietary, to the e-reader. It had been a long time since I was asked to "register my software" frenetically, and I hadn't missed that one bit. So I decided to stay away from this until that solution and its documentation matures a bit.

Streaming re-established I have worked a bit on my home radio stream. I simply turned the Liquidsoap stream back online, and did a few tweaks to the documentation that I had built back then. All that experimenting led me to do two NMUs. One was for gmpc-plugins to fix a FTBFS (bug #807735) and to properly kill the shout streamer when completing the playback (bug #820908). The other was to fix the ezstream manpage (bug #573928), a patch that had been sitting there for 5 years! This was to try to find an easy way to stream random audio (say from a microphone) to the Icecast server, something which is surprisingly difficult, consider how basic that functionality is. I was surprised to see that Darkice just completely fails to start (bug #821040) and I had to fallback to the simplest ices2 software to stream the audio. I am still having issues with Liquidsoap: it's really unstable! As a server, I would expect it to keep running for days if not years. Unfortunately, there's always something that makes it crash. I had assertion failed (bug #821112) and I keep seeing it crash after 2-3 days fairly reliably, a bug I reported 3 years ago and that is still not fixed (bug #727307). Switching back the stream to Vorbis (because I was having problems with the commandline mp3 players and ogg123 is much more lightweight) created another set of problems too, this time with the phone. It seems that Android cannot stream Vorbis at all, something that is even worse in Cyanogenmod... I also had to tweak my MPD config to make the Android client be able to load the larger playlists (see dmix buffer is full).

Android apps So I have also done quite a bit of work again on my phone. I finally was told how to access from Termux from adb shell which is pretty cool because now I can start a screen on my phone and then, when I'm tired of tapping to type, I can just reconnect to it when I plug in a USB cable on my laptop. I sent a pull request to fix the documentation regarding that. I also tried to see how my SMS and Signal situation could be improved. Right now, I have two different apps to do SMS on my phone: I use both Signal and the VoIP.ms SMS client, because I do not have a contract or SIM card in my phone. Both work well independently, but it's somewhat annoying to have to switch between the two. (In fact, I feel that Signal itself has an issue with how it depends on the network to send encrypted messages: I often have to "ping" people in clear text (and therefore in the other app) so that they connect to their data plan to fetch my "secure" signal messages...) Anyways, I figured it would be nice if at least there would be a SMS fallback in Signal that would allow me to send regular text messages from signal through Voip.MS. That was dismissed really fast. Moxie even closed the conversation completely, something I had never experienced before, and doesn't feel exactly pleasant. The Voip.MS side was of course not impressed and basically shrugged it off because Signal was not receptive. I also tried to clear up the Libresignal confusion: there are 3 different projects named "Libresignal", and I am not sure I figured out the right thing, even though the issue is now closed and there's a FAQ that is supposed to make all that clear. Nevertheless, I opened two distinct feature requests to try to steer the conversation into a more productive direction: GCM-less calls and GCM support. But I'm not sure neither will go anywhere. In the meantime, I am using the official signal client, which I downloaded using gplaycli and which I keep up to date with Aptoide. Even though the reliability of that site is definitely questionable, it seems that once you have a trusted version, it is safe to upgrade, regardless of the source because there is a trust path between you and the developer. I also filed a few issues with varying levels of success/response from the community:

Random background radiation And then there's of course the monthly background noise of all the projects I happened to not only stumble on, but also file bugs or patches against:

20 April 2016

Ben Hutchings: Experiments with signed kernels and modules in Debian

I've lately been working on support for Secure Boot in Debian, mostly in the packages maintained by the kernel team. My instructions for setting up UEFI Secure Boot are based on OVMF running on KVM/QEMU. All 'Designed for Windows' PCs should allow reconfiguration of SB, but it may not be easy to do so. They also assume that the firmware includes an EFI shell. Updated: Robert Edmonds pointed out that the 'Designed for Windows' requirements changed with Windows 10: The ability to reconfigure SB is indeed now optional for devices which are designed to always boot with a specific Secure Boot configuration. I also noticed that the requirements say that OEMs should not sign an EFI shell binary. Therefore I've revised the instructions to use efibootmgr instead. Background UEFI Secure Boot, when configured and enabled (which it is on most new PCs) requires that whatever it loads is signed with a trusted key. The one common trusted key for PCs is held by Microsoft, and while they will sign other people's code for a nominal fee, they require that it also validates the code it loads, i.e. the kernel or next stage boot loader. The kernel in turn is responsible for validating any code that could compromise its integrity (kernel modules, kexec images). Currently there are no such signed boot loaders in Debian, though the shim and grub-signed packages included in many other distributions should be usable. However it's possible to load an appropriately configured Linux kernel directly from the UEFI firmware (typically through the shell) which is what I'm doing at the moment. Packaging signed kernels Signing keys obviously need to be protected against disclosure; the private keys can't be included in a source package. We also won't install them on buildds separately, and generating signatures at build time would of course be unreproducible. So I've created a new source package, linux-signed, which contains detached signatures prepared offline. Currently the binary packages built from linux-signed also contain only detached signatures, which are applied as necessary at installation time. The signed kernel image (only on x86 for now) is named /boot/vmlinuz-kversion.efi.signed. However, since packages must not modify files owned by another package and I didn't want to dpkg-divert thousands of modules, the module signatures remain detached. Detached module signatures are a new invention of mine, and require changes in kmod and various other packages to support them. (An alternate might be to put signed modules under a different directory and drop a configuration file in /lib/depmod.d to make them higher priority. But then we end up with two copies of every module installed, which can be a substantial waste of space.) Preparation The packages you need to repeat the experiment: For Secure Boot, you'll then need to copy the signed kernel and the initrd onto the EFI system partition, normally mounted at /boot/efi. SB requires a Platform Key (PK) which will already be installed on a real PC. You can replace it but you don't need to. If you're using OVMF, there are no persistent keys so you do need to generate your own:
openssl req -new -x509 -newkey rsa:2048 -keyout pk.key -out pk.crt \
    -outform der -nodes
You'll also need to install the certificate for my kernel image signing key, which is under debian/certs in the linux-signed package. OVMF requires this in DER format:
openssl x509 -in linux-signed-1~exp3/debian/certs/linux-image-benh@debian.org.cert.pem \
    -out linux.crt -outform der 
You'll need to copy the certificate(s) to a FAT-formatted partition such as the EFI system partition, so that the firmware can read it. Use efibootmgr to add a boot entry for the kernel, for example:
efibootmgr -c -d /dev/sda -L linux-signed -l '\vmlinuz.efi' -u 'initrd=initrd.img root=/dev/sda2 ro quiet'
You should use the same kernel parameters as usual, except that you also need to specify the initrd filename using the initrd= parameter. The EFI stub code at the beginning of the kernel will load the initrd using EFI boot services. Enabling Secure Boot
  1. Reboot the system and enter UEFI setup
  2. Find the menu entry for Secure Boot customisation (in OVMF, it's under 'Device Manager' for some reason)
  3. In OVMF, enrol the PK from pk.crt
  4. Add linux.crt to the DB (whitelist database)
  5. Ensure that Secure Boot is enabled and in 'User Mode'
Booting the kernel in Secure Boot If all went well, Linux will boot as normal. You can confirm that Secure Boot was enabled by reading /sys/kernel/security/securelevel, which will contain 1 if it was. Module signature validation Module signatures are now always checked and unsigned modules will be given the 'E' taint flag. If Secure Boot is used or you add the kernel parameter module.sig_enforce=1, unsigned modules will be rejected. You can also turn on signature enforcement and turn off various other methods of modifying kernel code (such as kexec) by writing 1 to /sys/kernel/security/securelevel.

Reproducible builds folks: Reproducible builds: week 51 in Stretch cycle

What happened in the reproducible builds effort between April 10th and April 16th 2016: Toolchain fixes Antoine Beaupr suggested that gitpkg stops recording timestamps when creating upstream archives. Antoine Beaupr also pointed out that git-buildpackage diverges from the default gzip settings which is a problem for reproducibly recreating released tarballs which were made using the defaults. Alexis Bienven e submitted a patch extending sphinx SOURCE_DATE_EPOCH support to copyright year. Packages fixed The following packages have become reproducible due to changes in their build dependencies: atinject-jsr330, avis, brailleutils, charactermanaj, classycle, commons-io, commons-javaflow, commons-jci, gap-radiroot, jebl2, jetty, libcommons-el-java, libcommons-jxpath-java, libjackson-json-java, libjogl2-java, libmicroba-java, libproxool-java, libregexp-java, mobile-atlas-creator, octave-econometrics, octave-linear-algebra, octave-odepkg, octave-optiminterp, rapidsvn, remotetea, ruby-rinku, tachyon, xhtmlrenderer. The following packages became reproducible after getting fixed: Some uploads fixed some reproducibility issues, but not all of them: Patches submitted which have not made their way to the archive yet: diffoscope development Zbigniew J drzejewski-Szmek noted in #820631 that diffoscope doesn't work properly when a file contains several cpio archives. Package reviews 21 reviews have been added, 14 updated and 22 removed in this week. New issue found: timestamps_in_htm_by_gap. Chris Lamb reported 10 new FTBFS issues. Misc. The video and the slides from the talk "Reproducible builds ecosystem" at LibrePlanet 2016 have been published now. This week's edition was written by Lunar and Holger Levsen. h01ger automated the maintenance and publishing of this weekly newsletter via git.

Michal &#268;iha&#345;: Testing Sphinx documentation with Jenkins

While reviewing comments on phpMyAdmin wiki (which we're shrinking down to developer documentation and moving end user documentation to proper documentation) I've noticed that people complained there on broken links in our documentation. Indeed there was quite some of them as this is something nobody really checks. It seems like obvious task to automate. It seemed to me as obvious as somebody had to do it already. Unfortunately I have not found much, but at least there was Using Jenkins to parse sphinx warnings. This helps with the build warnings, but unfortunately I found no integration for the linkcheck builder. Fortunately it's quite easy with the Jenkins Warnings plugin to write custom parsers and to parse linkcheck output as well. The Sphinx output parser based on above link can be configured like: Regular Expression:
^(.*):(\d+): \((.*)\) (.*)
Mapping Script:
import hudson.plugins.warnings.parser.Warning
String fileName = matcher.group(1)
String lineNumber = matcher.group(2)
String category = matcher.group(3)
String message = matcher.group(4)
return new Warning(fileName, Integer.parseInt(lineNumber), "sphinx", category, message);
Example Log Message:
Percona-Server-1.0.2-3.rst:67: (WARNING/2) Inline literal start-string without end-string.
The Sphinx linkcheck output is quite similar: Regular Expression:
^(.*):(\d+): \[([^\]]*)\] (.*)
Mapping Script:
import hudson.plugins.warnings.parser.Warning
String fileName = matcher.group(1)
String lineNumber = matcher.group(2)
String category = matcher.group(3)
String message = matcher.group(4)
return new Warning(fileName, Integer.parseInt(lineNumber), "sphinx-linkcheck", category, message);
Example Log Message:
faq.rst:793: [broken] http://www.hardened-php.net/: <urlopen error [Errno -3] Temporary failure in name resolution>
All you need to do now is to enable these in your Jenkins project, let the Sphinx parse output and the Sphinx linkcheck one file generated by linkcheck (usually _build/linkcheck/output.txt). The result can be found on the phpMyAdmin CI server.

Filed under: English phpMyAdmin 2 comments

Norbert Preining: GnuPG notes: subkeys, yubikey, gpg1 vs gpg2

Switching from one GnuPG master key to the usage of subkeys was long on my list of things I wanted to do, but never came around. With the advent of a YubiKey NEO in my pocket I finally took the plunge: reading through lots of web pages (and adding one here for confusion), trying to understand the procedures, and above all, understanding my own requirements! gpg-subkeys-yubi To sum up a long story, it was worth the plunge, and all over the security level of my working environment has improved considerable. While the advantages of subkeys are well documented (e.g., Debian Wiki), at the end of the day I was like probably many Debian Developers having one master key that was used for every action: mail decryption and signing, signing of uploads, etc. Traveling a lot I always felt uncomfortable. Despite a lengthy passphrase, I still didn t want my master key to get into wrong hands in case the laptop got stolen. Furthermore, I had my master key on several computers (work, laptop, mail server), which didn t help a lot either. With all this, I started to compile a list of requirements/objectives I wanted to have: Warning Before we start a word of caution make backups, best is to make backups at every stage. You don t want that an erroneous operations wipes out your precious keys without a backup! Preparation In the following I will assume that MASTERKEY environment variable contains the id of the master key to be converted. Furthermore, I have followed some of the advice here, so key ids will be shown in long format. Let us start with the current situation:
$ gpg -K $MASTERKEY
sec   4096R/0x6CACA448860CDC13 2010-09-14
      Key fingerprint = F7D8 A928 26E3 16A1 9FA0  ACF0 6CAC A448 860C DC13
uid                            Norbert Preining <norbert@preining.info>
uid                            Norbert Preining <preining@logic.at>
uid                            Norbert Preining <preining@debian.org>
uid                            Norbert Preining <preining@jaist.ac.jp>
ssb   4096R/0xD1D2BD14810F62B3 2010-09-14
In the following we will go through the following steps: Yubikey SmartCard setup There are several guides out there, but I will in very near future write one about using the NEO for various usage scenaria including GPG keys. Edit the current key The following can be done in one session or in different sessions, the screen logs are after starting with:
$ gpg --expert --edit-key $MASTERKEY
add expiry date Having an expiry date on your key serves two purposes: If you loose it, it will solve itself automatically, and furthermore, you are forced to deal with the key and refresh your gpg knowledge at least once a year. That are two perfect reasons to set expiry to one year. The following log selects each key in turn and sets its expiry date.
$ gpg --expert --edit-key $MASTERKEY
gpg (GnuPG) 1.4.20; Copyright (C) 2015 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
 
Secret key is available.
 
pub  4096R/0x6CACA448860CDC13  created: 2010-09-14  expires: never       usage: SC  
                               trust: ultimate      validity: ultimate
sub  4096R/0xD1D2BD14810F62B3  created: 2010-09-14  expires: never       usage: E   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
 
gpg> expire
Changing expiration time for the primary key.
Please specify how long the key should be valid.
         0 = key does not expire
      <n>  = key expires in n days
      <n>w = key expires in n weeks
      <n>m = key expires in n months
      <n>y = key expires in n years
Key is valid for? (0) 1y
Key expires at Mon 06 Feb 2017 08:09:16 PM JST
Is this correct? (y/N) y
 
You need a passphrase to unlock the secret key for
user: "Norbert Preining <norbert@preining.info>"
4096-bit RSA key, ID 0x6CACA448860CDC13, created 2010-09-14
 
Enter passphrase:
 
pub  4096R/0x6CACA448860CDC13  created: 2010-09-14  expires: 2017-02-06  usage: SC  
                               trust: ultimate      validity: ultimate
sub  4096R/0xD1D2BD14810F62B3  created: 2010-09-14  expires: never       usage: E   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
 
gpg> key 1
 
pub  4096R/0x6CACA448860CDC13  created: 2010-09-14  expires: 2017-02-06  usage: SC  
                               trust: ultimate      validity: ultimate
sub* 4096R/0xD1D2BD14810F62B3  created: 2010-09-14  expires: never       usage: E   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
 
gpg> expire
Changing expiration time for a subkey.
Please specify how long the key should be valid.
         0 = key does not expire
      <n>  = key expires in n days
      <n>w = key expires in n weeks
      <n>m = key expires in n months
      <n>y = key expires in n years
Key is valid for? (0) 1y
Key expires at Mon 06 Feb 2017 08:09:27 PM JST
Is this correct? (y/N) y
 
You need a passphrase to unlock the secret key for
user: "Norbert Preining <norbert@preining.info>"
4096-bit RSA key, ID 0x6CACA448860CDC13, created 2010-09-14
 
Enter passphrase:
 
pub  4096R/0x6CACA448860CDC13  created: 2010-09-14  expires: 2017-02-06  usage: SC  
                               trust: ultimate      validity: ultimate
sub* 4096R/0xD1D2BD14810F62B3  created: 2010-09-14  expires: 2017-02-06  usage: E   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
Add a photo Not strictly necessary, but an interesting feature. gpg suggests 240 288, I resized a photo of my head, greyscaled it, and optimized it with jpegoptim -s -m40 my-photo.jpg. The parameter 40 is the quality, I played around a bit to find the best balance between size and quality. The size should not be too big as the photo will be part of the key!
gpg> addphoto
 
Pick an image to use for your photo ID.  The image must be a JPEG file.
Remember that the image is stored within your public key.  If you use a
very large picture, your key will become very large as well!
Keeping the image close to 240x288 is a good size to use.
 
Enter JPEG filename for photo ID: GPG/norbert-head.jpg
Is this photo correct (y/N/q)? y
 
You need a passphrase to unlock the secret key for
user: "Norbert Preining <norbert@preining.info>"
4096-bit RSA key, ID 0x6CACA448860CDC13, created 2010-09-14
 
Enter passphrase:
 
pub  4096R/0x6CACA448860CDC13  created: 2010-09-14  expires: 2017-02-06  usage: SC  
                               trust: ultimate      validity: ultimate
sub* 4096R/0xD1D2BD14810F62B3  created: 2010-09-14  expires: 2017-02-06  usage: E   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
[ unknown] (5)  [jpeg image of size 4185]
Add subkeys of 2048bit for signing/encryption/authentication Now comes the interesting part, adding three subkeys: one for signing, one for encrypting, and one for authentication. The one for signing is the one you will use for signing your uploads to Debian as well as emails. The authentication key will later be used to provide ssh authentication. Note that you have to use the --expert expert option to edit-key (as shown above), otherwise gpg does not allow to do this. As I want to move the subkeys to the Yubikey NEO, a keysize of 2048bits is necessary. First for the signing:
gpg> addkey
Key is protected.
 
You need a passphrase to unlock the secret key for
user: "Norbert Preining <norbert@preining.info>"
4096-bit RSA key, ID 0x6CACA448860CDC13, created 2010-09-14
 
Enter passphrase:
 
Please select what kind of key you want:
   (3) DSA (sign only)
   (4) RSA (sign only)
   (5) Elgamal (encrypt only)
   (6) RSA (encrypt only)
   (7) DSA (set your own capabilities)
   (8) RSA (set your own capabilities)
Your selection? 4
RSA keys may be between 1024 and 4096 bits long.
What keysize do you want? (2048) 
Requested keysize is 2048 bits
Please specify how long the key should be valid.
         0 = key does not expire
      <n>  = key expires in n days
      <n>w = key expires in n weeks
      <n>m = key expires in n months
      <n>y = key expires in n years
Key is valid for? (0) 1y
Key expires at Mon 06 Feb 2017 08:10:06 PM JST
Is this correct? (y/N) y
Really create? (y/N) y
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
....+++++
..........+++++
 
pub  4096R/0x6CACA448860CDC13  created: 2010-09-14  expires: 2017-02-06  usage: SC  
                               trust: ultimate      validity: ultimate
sub* 4096R/0xD1D2BD14810F62B3  created: 2010-09-14  expires: 2017-02-06  usage: E   
sub  2048R/0xEC00B8DAD32266AA  created: 2016-02-07  expires: 2017-02-06  usage: S   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
[ unknown] (5)  [jpeg image of size 4185]
Now the same for encryption key:
gpg> addkey
Key is protected.
 
You need a passphrase to unlock the secret key for
user: "Norbert Preining <norbert@preining.info>"
4096-bit RSA key, ID 0x6CACA448860CDC13, created 2010-09-14
 
Enter passphrase:
 
Please select what kind of key you want:
   (3) DSA (sign only)
   (4) RSA (sign only)
   (5) Elgamal (encrypt only)
   (6) RSA (encrypt only)
   (7) DSA (set your own capabilities)
   (8) RSA (set your own capabilities)
Your selection? 6
RSA keys may be between 1024 and 4096 bits long.
What keysize do you want? (2048) 
Requested keysize is 2048 bits
Please specify how long the key should be valid.
         0 = key does not expire
      <n>  = key expires in n days
      <n>w = key expires in n weeks
      <n>m = key expires in n months
      <n>y = key expires in n years
Key is valid for? (0) 1y
Key expires at Mon 06 Feb 2017 08:10:20 PM JST
Is this correct? (y/N) y
Really create? (y/N) y
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
..+++++
........+++++
 
pub  4096R/0x6CACA448860CDC13  created: 2010-09-14  expires: 2017-02-06  usage: SC  
                               trust: ultimate      validity: ultimate
sub* 4096R/0xD1D2BD14810F62B3  created: 2010-09-14  expires: 2017-02-06  usage: E   
sub  2048R/0xEC00B8DAD32266AA  created: 2016-02-07  expires: 2017-02-06  usage: S   
sub  2048R/0xBF361ED434425B4C  created: 2016-02-07  expires: 2017-02-06  usage: E   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
[ unknown] (5)  [jpeg image of size 4185]
Finally for the authentication key. Note that only here the --expert is necessary! We use (8) RSA (set your own capabilities) and then toggle sign and encryption capabilities off, and authentication on.
gpg> addkey
Key is protected.
 
You need a passphrase to unlock the secret key for
user: "Norbert Preining <norbert@preining.info>"
4096-bit RSA key, ID 0x6CACA448860CDC13, created 2010-09-14
 
Enter passphrase:
 
Please select what kind of key you want:
   (3) DSA (sign only)
   (4) RSA (sign only)
   (5) Elgamal (encrypt only)
   (6) RSA (encrypt only)
   (7) DSA (set your own capabilities)
   (8) RSA (set your own capabilities)
Your selection? 8
 
Possible actions for a RSA key: Sign Encrypt Authenticate 
Current allowed actions: Sign Encrypt 
 
   (S) Toggle the sign capability
   (E) Toggle the encrypt capability
   (A) Toggle the authenticate capability
   (Q) Finished
 
Your selection? s
 
Possible actions for a RSA key: Sign Encrypt Authenticate 
Current allowed actions: Encrypt 
 
   (S) Toggle the sign capability
   (E) Toggle the encrypt capability
   (A) Toggle the authenticate capability
   (Q) Finished
 
Your selection? e
 
Possible actions for a RSA key: Sign Encrypt Authenticate 
Current allowed actions: 
 
   (S) Toggle the sign capability
   (E) Toggle the encrypt capability
   (A) Toggle the authenticate capability
   (Q) Finished
 
Your selection? a
 
Possible actions for a RSA key: Sign Encrypt Authenticate 
Current allowed actions: Authenticate 
 
   (S) Toggle the sign capability
   (E) Toggle the encrypt capability
   (A) Toggle the authenticate capability
   (Q) Finished
 
Your selection? q
RSA keys may be between 1024 and 4096 bits long.
What keysize do you want? (2048) 
Requested keysize is 2048 bits
Please specify how long the key should be valid.
         0 = key does not expire
      <n>  = key expires in n days
      <n>w = key expires in n weeks
      <n>m = key expires in n months
      <n>y = key expires in n years
Key is valid for? (0) 1y
Key expires at Mon 06 Feb 2017 08:10:34 PM JST
Is this correct? (y/N) y
Really create? (y/N) y
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
......+++++
+++++
 
pub  4096R/0x6CACA448860CDC13  created: 2010-09-14  expires: 2017-02-06  usage: SC  
                               trust: ultimate      validity: ultimate
sub* 4096R/0xD1D2BD14810F62B3  created: 2010-09-14  expires: 2017-02-06  usage: E   
sub  2048R/0xEC00B8DAD32266AA  created: 2016-02-07  expires: 2017-02-06  usage: S   
sub  2048R/0xBF361ED434425B4C  created: 2016-02-07  expires: 2017-02-06  usage: E   
sub  2048R/0x9C7CA4E294F04D49  created: 2016-02-07  expires: 2017-02-06  usage: A   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
[ unknown] (5)  [jpeg image of size 4185]
 
gpg> save
Check the current status Good point to take a break and inspect the current status. We should have one main key and three subkeys, all with expiry dates of 1 year ahead, and a photo also attached to the key:
$ gpg --expert --edit-key $MASTERKEY
gpg (GnuPG) 1.4.20; Copyright (C) 2015 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
 
Secret key is available.
 
gpg: checking the trustdb
gpg: public key 0x0FC3EC02FBBB8AB1 is 58138 seconds newer than the signature
gpg: 3 marginal(s) needed, 1 complete(s) needed, classic trust model
gpg: depth: 0  valid:   2  signed:  28  trust: 0-, 0q, 0n, 0m, 0f, 2u
gpg: depth: 1  valid:  28  signed:  41  trust: 28-, 0q, 0n, 0m, 0f, 0u
gpg: next trustdb check due at 2016-11-02
pub  4096R/0x6CACA448860CDC13  created: 2010-09-14  expires: 2017-02-06  usage: SC  
                               trust: ultimate      validity: ultimate
sub  4096R/0xD1D2BD14810F62B3  created: 2010-09-14  expires: 2017-02-06  usage: E   
sub  2048R/0xEC00B8DAD32266AA  created: 2016-02-07  expires: 2017-02-06  usage: S   
sub  2048R/0xBF361ED434425B4C  created: 2016-02-07  expires: 2017-02-06  usage: E   
sub  2048R/0x9C7CA4E294F04D49  created: 2016-02-07  expires: 2017-02-06  usage: A   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
[ultimate] (5)  [jpeg image of size 4185]
 
gpg>
Create revocation certificate In case something happens, like all your backups are burned, your computers are destroyed, or all data stolen by the NSA, it is a good idea to have an old fashioned paper print out of a revocation certificate which allows you to revoke the key even if you are not in possession of it. This should be printed out and kept in a safe place.
$ gpg --gen-revoke $MASTERKEY > GPG/revoke-certificate-$MASTERKEY.txt
 
sec  4096R/0x6CACA448860CDC13 2010-09-14 Norbert Preining <norbert@preining.info>
 
Create a revocation certificate for this key? (y/N) y
Please select the reason for the revocation:
  0 = No reason specified
  1 = Key has been compromised
  2 = Key is superseded
  3 = Key is no longer used
  Q = Cancel
(Probably you want to select 1 here)
Your decision? 1
Enter an optional description; end it with an empty line:
> 
Reason for revocation: Key has been compromised
(No description given)
Is this okay? (y/N) y
 
You need a passphrase to unlock the secret key for
user: "Norbert Preining <norbert@preining.info>"
4096-bit RSA key, ID 0x6CACA448860CDC13, created 2010-09-14
 
Enter passphrase:
 
ASCII armored output forced.
Revocation certificate created.
Please move it to a medium which you can hide away; if the NSA or KGB or Mossad gets access to this certificate, they can use it to make your key unusable. It is smart to print this certificate and store it away, just in case your media become unreadable. Create gpg 2.1 structure There are currently three versions of gpg available: classic (version 1) which is one static binary, perfect for servers or scripting tasks; stable (version 2.0) which is the modularized version supporting OpenPGP, S/MIME, and Secure Shell; and finally modern (version 2.1 and up) with enhanced features like support for Elliptic Curve cryptography. Debian currently ships version 1 as standard, and also the modern version (but there are traces in experimental of a pending transition). The newer versions of GnuPG are modularized and use an agent. For the following we need to kill any running instance of gpg-agent.
$ killall gpg-agent
After that a simple call to gpg2 to list the secret keys will convert the layout to the new standard:
$ gpg2 -K $MASTERKEY
gpg: keyserver option 'ca-cert-file' is obsolete; please use 'hkp-cacert' in dirmngr.conf
gpg: starting migration from earlier GnuPG versions
gpg: porting secret keys from '/home/norbert/.gnupg/secring.gpg' to gpg-agent
gpg: key 0xD2BF4AA309C5B094: secret key imported
gpg: key 0x6CACA448860CDC13: secret key imported
gpg: migration succeeded
sec   rsa4096/0x6CACA448860CDC13 2010-09-14 [SC] [expires: 2017-02-06]
      Key fingerprint = F7D8 A928 26E3 16A1 9FA0  ACF0 6CAC A448 860C DC13
uid                   [ultimate] Norbert Preining <norbert@preining.info>
uid                   [ultimate] Norbert Preining <preining@logic.at>
uid                   [ultimate] Norbert Preining <preining@debian.org>
uid                   [ultimate] Norbert Preining <preining@jaist.ac.jp>
uid                   [ultimate] [jpeg image of size 4185]
ssb   rsa4096/0xD1D2BD14810F62B3 2010-09-14 [E] [expires: 2017-02-06]
ssb   rsa2048/0xEC00B8DAD32266AA 2016-02-07 [S] [expires: 2017-02-06]
ssb   rsa2048/0xBF361ED434425B4C 2016-02-07 [E] [expires: 2017-02-06]
ssb   rsa2048/0x9C7CA4E294F04D49 2016-02-07 [A] [expires: 2017-02-06]
After this there will be new files/directories in the .gnupg directory, in particular: .gnupg/private-keys-v1.d/ which contains the private keys. Creating backup Now your .gnupg directory contains still all the keys, available for gpg1 and gpg2.1. You MUST MAKE A BACKUP NOW!!! on at least 3 USB sticks and maybe some other offline media. Keep them in a safe place, better in different and safe places, you will need them for extending the expiry date, signing other keys, etc. Warning concerning USB and vfat file systems gpg >= 2.1 requires gpg-agent which in turn needs a socket. If you have the backup on an USB drive (most often with vfat file system), you need to redirect the socket, as vfat does not support sockets! Edit /USBSTICK/gnupghome/S.gpg-agent and enter there
%Assuan%
socket=/dev/shm/S.gpg-agent
After that the socket will be created in /dev/shm/ instead and invoking gpg with gpg2 --homedir /USBSTICK/gnupghome will work. You have done your backups, right? Move sub keys to card As I mentioned, I want to have no keys on my laptop which I carry around to strange countries, instead I want to have them all on a Yubikey NEO. I will describe the setup and usage in details soon, but mention here only how to move the keys to the card. This requires a finished setup including change of pins. Note that when using gpg2 to move the keys to the card, the local copies are actually deleted, but only for the gpg2(.1) files. The gpg1 secret keys are still all in place.
$ gpg2 --edit-key $MASTERKEY
gpg (GnuPG) 2.1.11; Copyright (C) 2016 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
 
Secret key is available.
 
sec  rsa4096/0x6CACA448860CDC13
     created: 2010-09-14  expires: 2017-02-06  usage: SC  
     trust: ultimate      validity: ultimate
ssb  rsa4096/0xD1D2BD14810F62B3
     created: 2010-09-14  expires: 2017-02-06  usage: E   
ssb  rsa2048/0xEC00B8DAD32266AA
     created: 2016-02-07  expires: 2017-02-06  usage: S   
ssb  rsa2048/0xBF361ED434425B4C
     created: 2016-02-07  expires: 2017-02-06  usage: E   
ssb  rsa2048/0x9C7CA4E294F04D49
     created: 2016-02-07  expires: 2017-02-06  usage: A   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
[ultimate] (5)  [jpeg image of size 4185]
 
gpg> key 2
 
sec  rsa4096/0x6CACA448860CDC13
     created: 2010-09-14  expires: 2017-02-06  usage: SC  
     trust: ultimate      validity: ultimate
ssb  rsa4096/0xD1D2BD14810F62B3
     created: 2010-09-14  expires: 2017-02-06  usage: E   
ssb* rsa2048/0xEC00B8DAD32266AA
     created: 2016-02-07  expires: 2017-02-06  usage: S   
ssb  rsa2048/0xBF361ED434425B4C
     created: 2016-02-07  expires: 2017-02-06  usage: E   
ssb  rsa2048/0x9C7CA4E294F04D49
     created: 2016-02-07  expires: 2017-02-06  usage: A   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
[ultimate] (5)  [jpeg image of size 4185]
 
gpg> keytocard
Please select where to store the key:
   (1) Signature key
   (3) Authentication key
Your selection? 1
 
sec  rsa4096/0x6CACA448860CDC13
     created: 2010-09-14  expires: 2017-02-06  usage: SC  
     trust: ultimate      validity: ultimate
ssb  rsa4096/0xD1D2BD14810F62B3
     created: 2010-09-14  expires: 2017-02-06  usage: E   
ssb* rsa2048/0xEC00B8DAD32266AA
     created: 2016-02-07  expires: 2017-02-06  usage: S   
ssb  rsa2048/0xBF361ED434425B4C
     created: 2016-02-07  expires: 2017-02-06  usage: E   
ssb  rsa2048/0x9C7CA4E294F04D49
     created: 2016-02-07  expires: 2017-02-06  usage: A   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
[ultimate] (5)  [jpeg image of size 4185]
 
gpg> key 2
 
sec  rsa4096/0x6CACA448860CDC13
     created: 2010-09-14  expires: 2017-02-06  usage: SC  
     trust: ultimate      validity: ultimate
ssb  rsa4096/0xD1D2BD14810F62B3
     created: 2010-09-14  expires: 2017-02-06  usage: E   
ssb  rsa2048/0xEC00B8DAD32266AA
     created: 2016-02-07  expires: 2017-02-06  usage: S   
ssb  rsa2048/0xBF361ED434425B4C
     created: 2016-02-07  expires: 2017-02-06  usage: E   
ssb  rsa2048/0x9C7CA4E294F04D49
     created: 2016-02-07  expires: 2017-02-06  usage: A   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
[ultimate] (5)  [jpeg image of size 4185]
 
gpg> key 3
 
sec  rsa4096/0x6CACA448860CDC13
     created: 2010-09-14  expires: 2017-02-06  usage: SC  
     trust: ultimate      validity: ultimate
ssb  rsa4096/0xD1D2BD14810F62B3
     created: 2010-09-14  expires: 2017-02-06  usage: E   
ssb  rsa2048/0xEC00B8DAD32266AA
     created: 2016-02-07  expires: 2017-02-06  usage: S   
ssb* rsa2048/0xBF361ED434425B4C
     created: 2016-02-07  expires: 2017-02-06  usage: E   
ssb  rsa2048/0x9C7CA4E294F04D49
     created: 2016-02-07  expires: 2017-02-06  usage: A   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
[ultimate] (5)  [jpeg image of size 4185]
 
gpg> keytocard
Please select where to store the key:
   (2) Encryption key
Your selection? 2
 
sec  rsa4096/0x6CACA448860CDC13
     created: 2010-09-14  expires: 2017-02-06  usage: SC  
     trust: ultimate      validity: ultimate
ssb  rsa4096/0xD1D2BD14810F62B3
     created: 2010-09-14  expires: 2017-02-06  usage: E   
ssb  rsa2048/0xEC00B8DAD32266AA
     created: 2016-02-07  expires: 2017-02-06  usage: S   
ssb* rsa2048/0xBF361ED434425B4C
     created: 2016-02-07  expires: 2017-02-06  usage: E   
ssb  rsa2048/0x9C7CA4E294F04D49
     created: 2016-02-07  expires: 2017-02-06  usage: A   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
[ultimate] (5)  [jpeg image of size 4185]
 
gpg> key 3
 
sec  rsa4096/0x6CACA448860CDC13
     created: 2010-09-14  expires: 2017-02-06  usage: SC  
     trust: ultimate      validity: ultimate
ssb  rsa4096/0xD1D2BD14810F62B3
     created: 2010-09-14  expires: 2017-02-06  usage: E   
ssb  rsa2048/0xEC00B8DAD32266AA
     created: 2016-02-07  expires: 2017-02-06  usage: S   
ssb  rsa2048/0xBF361ED434425B4C
     created: 2016-02-07  expires: 2017-02-06  usage: E   
ssb  rsa2048/0x9C7CA4E294F04D49
     created: 2016-02-07  expires: 2017-02-06  usage: A   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
[ultimate] (5)  [jpeg image of size 4185]
 
gpg> key 4
 
sec  rsa4096/0x6CACA448860CDC13
     created: 2010-09-14  expires: 2017-02-06  usage: SC  
     trust: ultimate      validity: ultimate
ssb  rsa4096/0xD1D2BD14810F62B3
     created: 2010-09-14  expires: 2017-02-06  usage: E   
ssb  rsa2048/0xEC00B8DAD32266AA
     created: 2016-02-07  expires: 2017-02-06  usage: S   
ssb  rsa2048/0xBF361ED434425B4C
     created: 2016-02-07  expires: 2017-02-06  usage: E   
ssb* rsa2048/0x9C7CA4E294F04D49
     created: 2016-02-07  expires: 2017-02-06  usage: A   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
[ultimate] (5)  [jpeg image of size 4185]
 
gpg> keytocard
Please select where to store the key:
   (3) Authentication key
Your selection? 3
 
sec  rsa4096/0x6CACA448860CDC13
     created: 2010-09-14  expires: 2017-02-06  usage: SC  
     trust: ultimate      validity: ultimate
ssb  rsa4096/0xD1D2BD14810F62B3
     created: 2010-09-14  expires: 2017-02-06  usage: E   
ssb  rsa2048/0xEC00B8DAD32266AA
     created: 2016-02-07  expires: 2017-02-06  usage: S   
ssb  rsa2048/0xBF361ED434425B4C
     created: 2016-02-07  expires: 2017-02-06  usage: E   
ssb* rsa2048/0x9C7CA4E294F04D49
     created: 2016-02-07  expires: 2017-02-06  usage: A   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
[ultimate] (5)  [jpeg image of size 4185]
 
gpg> key 4
 
sec  rsa4096/0x6CACA448860CDC13
     created: 2010-09-14  expires: 2017-02-06  usage: SC  
     trust: ultimate      validity: ultimate
ssb  rsa4096/0xD1D2BD14810F62B3
     created: 2010-09-14  expires: 2017-02-06  usage: E   
ssb  rsa2048/0xEC00B8DAD32266AA
     created: 2016-02-07  expires: 2017-02-06  usage: S   
ssb  rsa2048/0xBF361ED434425B4C
     created: 2016-02-07  expires: 2017-02-06  usage: E   
ssb  rsa2048/0x9C7CA4E294F04D49
     created: 2016-02-07  expires: 2017-02-06  usage: A   
[ultimate] (1). Norbert Preining <norbert@preining.info>
[ultimate] (2)  Norbert Preining <preining@logic.at>
[ultimate] (3)  Norbert Preining <preining@debian.org>
[ultimate] (4)  Norbert Preining <preining@jaist.ac.jp>
[ultimate] (5)  [jpeg image of size 4185]
 
gpg> save
Note the repetition of selecting and deselecting keys. Current status After this procedure we are now in the following situation: In gpg words it looks like this:
$ gpg2 -K $MASTERKEY
gpg: keyserver option 'ca-cert-file' is obsolete; please use 'hkp-cacert' in dirmngr.conf
sec   rsa4096/0x6CACA448860CDC13 2010-09-14 [SC] [expires: 2017-02-06]
      Key fingerprint = F7D8 A928 26E3 16A1 9FA0  ACF0 6CAC A448 860C DC13
uid                   [ultimate] Norbert Preining <norbert@preining.info>
uid                   [ultimate] Norbert Preining <preining@logic.at>
uid                   [ultimate] Norbert Preining <preining@debian.org>
uid                   [ultimate] Norbert Preining <preining@jaist.ac.jp>
uid                   [ultimate] [jpeg image of size 4185]
ssb   rsa4096/0xD1D2BD14810F62B3 2010-09-14 [E] [expires: 2017-02-06]
ssb>  rsa2048/0xEC00B8DAD32266AA 2016-02-07 [S] [expires: 2017-02-06]
ssb>  rsa2048/0xBF361ED434425B4C 2016-02-07 [E] [expires: 2017-02-06]
ssb>  rsa2048/0x9C7CA4E294F04D49 2016-02-07 [A] [expires: 2017-02-06]
 
$ gpg -K $MASTERKEY
sec   4096R/0x6CACA448860CDC13 2010-09-14 [expires: 2017-02-06]
      Key fingerprint = F7D8 A928 26E3 16A1 9FA0  ACF0 6CAC A448 860C DC13
uid                            Norbert Preining <norbert@preining.info>
uid                            Norbert Preining <preining@logic.at>
uid                            Norbert Preining <preining@debian.org>
uid                            Norbert Preining <preining@jaist.ac.jp>
uid                            [jpeg image of size 4185]
ssb   4096R/0xD1D2BD14810F62B3 2010-09-14 [expires: 2017-02-06]
ssb   2048R/0xEC00B8DAD32266AA 2016-02-07 [expires: 2017-02-06]
ssb   2048R/0xBF361ED434425B4C 2016-02-07 [expires: 2017-02-06]
ssb   2048R/0x9C7CA4E294F04D49 2016-02-07 [expires: 2017-02-06]
 
$ gpg2 --card-status
 
....
Name of cardholder: Norbert Preining
....
PIN retry counter : 3 3 3
Signature counter : 0
Signature key ....: 5871 F824 2DCC 3660 2362  BE7D EC00 B8DA D322 66AA
      created ....: 2016-02-07 11:10:06
Encryption key....: 2501 195C 90AB F4D2 3DEA  A303 BF36 1ED4 3442 5B4C
      created ....: 2016-02-07 11:10:20
Authentication key: 9CFB 3775 C164 0E99 F0C8  014C 9C7C A4E2 94F0 4D49
      created ....: 2016-02-07 11:10:34
General key info..: sub  rsa2048/0xEC00B8DAD32266AA 2016-02-07 Norbert Preining <norbert@preining.info>
sec   rsa4096/0x6CACA448860CDC13  created: 2010-09-14  expires: 2017-02-06
ssb   rsa4096/0xD1D2BD14810F62B3  created: 2010-09-14  expires: 2017-02-06
ssb>  rsa2048/0xEC00B8DAD32266AA  created: 2016-02-07  expires: 2017-02-06
                                  card-no: 0006 03645719
ssb>  rsa2048/0xBF361ED434425B4C  created: 2016-02-07  expires: 2017-02-06
                                  card-no: 0006 03645719
ssb>  rsa2048/0x9C7CA4E294F04D49  created: 2016-02-07  expires: 2017-02-06
                                  card-no: 0006 03645719
$
Remove private master keys You are sure that you have a working backup? Did you try it with gpg --homedir ...? Only if you are really sure, continue. We are now removing the master key from both the gpg2 and gpg1 setup. removal for gpg2 gpg2 keeps the private keys in ~/.gnupg/private-keys-v1.d/KEYGRIP.key and the KEYGRIP can be found by adding --with-keygrip to the key listing. Be sure to delete the correct file, the one related to the master key.
$ gpg2 --with-keygrip --list-key $MASTERKEY
pub   rsa4096/0x6CACA448860CDC13 2010-09-14 [SC] [expires: 2017-02-06]
      Key fingerprint = F7D8 A928 26E3 16A1 9FA0  ACF0 6CAC A448 860C DC13
      Keygrip = 9DC1E90703856C1DE0EAC970CED7ABF5EE5EF79D
uid                   [ultimate] Norbert Preining <norbert@preining.info>
uid                   [ultimate] Norbert Preining <preining@logic.at>
uid                   [ultimate] Norbert Preining <preining@debian.org>
uid                   [ultimate] Norbert Preining <preining@jaist.ac.jp>
uid                   [ultimate] [jpeg image of size 4185]
sub   rsa4096/0xD1D2BD14810F62B3 2010-09-14 [E] [expires: 2017-02-06]
      Keygrip = 4B8FF57434DD989243666377376903281D861596
sub   rsa2048/0xEC00B8DAD32266AA 2016-02-07 [S] [expires: 2017-02-06]
      Keygrip = 39B14EF1392F2F251863A87AE4D44CE502755C39
sub   rsa2048/0xBF361ED434425B4C 2016-02-07 [E] [expires: 2017-02-06]
      Keygrip = E41C8DDB2A22976AE0DA8D7D11F586EA793203EA
sub   rsa2048/0x9C7CA4E294F04D49 2016-02-07 [A] [expires: 2017-02-06]
      Keygrip = A337DE390143074C6DBFEA64224359B9859B02FC
 
$ rm ~/.gnupg/private-keys-v1.d/9DC1E90703856C1DE0EAC970CED7ABF5EE5EF79D.key
$
After that the missing key is shown in gpg2 -K with an additional # meaning that the key is not available:
$ gpg2 -K $MASTERKEY
sec#  rsa4096/0x6CACA448860CDC13 2010-09-14 [SC] [expires: 2017-02-06]
...
removal for gpg1 Up to gpg v2.0 there is no simple way to delete only one part of the key. We export the subkeys, delete the private key, and reimport the subkeys:
$ gpg --output secret-subkeys --export-secret-subkeys $MASTERKEY
 
$ gpg --delete-secret-keys $MASTERKEY
 
sec  4096R/0x6CACA448860CDC13 2010-09-14 Norbert Preining <norbert@preining.info>
 
Delete this key from the keyring? (y/N) y
This is a secret key! - really delete? (y/N) y
 
$ gpg --import secret-subkeys
gpg: key 0x6CACA448860CDC13: secret key imported
gpg: key 0x6CACA448860CDC13: "Norbert Preining <norbert@preining.info>" not changed
gpg: Total number processed: 1
gpg:              unchanged: 1
gpg:       secret keys read: 1
gpg:   secret keys imported: 1
 
$
Current status We are basically at the stage we wanted to achieve: For gpg2.1 only the old encryption key is available, the master key is not, and the other sub keys are moved to the yubikey:
$ gpg2 -K $MASTERKEY
sec#  rsa4096/0x6CACA448860CDC13 2010-09-14 [SC] [expires: 2017-02-06]
      Key fingerprint = F7D8 A928 26E3 16A1 9FA0  ACF0 6CAC A448 860C DC13
uid                   [ultimate] Norbert Preining <norbert@preining.info>
uid                   [ultimate] Norbert Preining <preining@logic.at>
uid                   [ultimate] Norbert Preining <preining@debian.org>
uid                   [ultimate] Norbert Preining <preining@jaist.ac.jp>
uid                   [ultimate] [jpeg image of size 4185]
ssb   rsa4096/0xD1D2BD14810F62B3 2010-09-14 [E] [expires: 2017-02-06]
ssb>  rsa2048/0xEC00B8DAD32266AA 2016-02-07 [S] [expires: 2017-02-06]
ssb>  rsa2048/0xBF361ED434425B4C 2016-02-07 [E] [expires: 2017-02-06]
ssb>  rsa2048/0x9C7CA4E294F04D49 2016-02-07 [A] [expires: 2017-02-06]
$
And for gpg <= 2.0 the old encryption key and the sub keys are available, but the master key is not:
$ gpg -K $MASTERKEY
sec#  4096R/0x6CACA448860CDC13 2010-09-14 [expires: 2017-02-06]
      Key fingerprint = F7D8 A928 26E3 16A1 9FA0  ACF0 6CAC A448 860C DC13
uid                            Norbert Preining <norbert@preining.info>
uid                            Norbert Preining <preining@logic.at>
uid                            Norbert Preining <preining@debian.org>
uid                            Norbert Preining <preining@jaist.ac.jp>
uid                            [jpeg image of size 4185]
ssb   4096R/0xD1D2BD14810F62B3 2010-09-14 [expires: 2017-02-06]
ssb   2048R/0xEC00B8DAD32266AA 2016-02-07 [expires: 2017-02-06]
ssb   2048R/0xBF361ED434425B4C 2016-02-07 [expires: 2017-02-06]
ssb   2048R/0x9C7CA4E294F04D49 2016-02-07 [expires: 2017-02-06]
 
$
Split the .gnupg directory for mail server and laptop As mentioned, I want to have a gpg1 version available at the server where I read my emails, and be able to sign/encrypt emails there, while on my laptop no secret key is available. Thus I prepare two gnupg directories. For the mailserver the gpg2 specific files are removed:
$ cp -a .gnupg .gnupg-mail
$ cd .gnupg-mail
$ rm -rf private-keys-v1.d/ pubring.gpg~ reader_0.status
$ rm -rf S.gpg-agent* S.scdaemon .gpg-v21-migrated
On my laptop, where I did all this operation, I remove the gpg1 files, namely the outdated secring.gpg:
$ cd $HOME/.gnupg
$ rm secring.gpg
As a last step I move the .gnupg-mail directory to my mail server. Once could *expire* the old encryption key, but for now I leave it as is. Upload keys to keyservers If you are a Debian Developer, a simple update of your master key will suffice:
gpg --keyserver hkp://keyring.debian.org --send-key YOURMASTERKEYID
Note that the update from the keyring server to the actual Debian keyring takes up to one month. Until that time either do not upload anything, or use the (offline) master key for signing. After your key has been updated in the Debian keyring, signatures made with the signing subkey will be accepted for uploading to Debian. It might be also a good idea to upload your new keys to some keyservers like:
gpg --keyserver hkp://pool.sks-keyservers.net --send-key $MASTERKEY
Now you an also fix the configuration file skew between gpg1 and gpg2. Further remark I am currently trying to use the authentication key from my Yubikey NEO as ssh key, but bugs (see #795368 and #818969) prohibit it at the moment. Raphael Herzog gave a possible fix by killing the gpg-agent and restarting it with gpg-agent --daemon from an X terminal, and I can confirm that this worked. After one year before the key expires I need to extend the key validity for another year. For this you need the offline master key. I will describe the process when it becomes necessary. Reading list The following web sites have been useful in collecting the necessary information:
  1. https://iain.learmonth.me/yubikey-neo-gpg/
  2. https://iain.learmonth.me/yubikey-udev/
  3. http://blog.josefsson.org/2014/06/23/offline-gnupg-master-key-and-subkeys-on-yubikey-neo-smartcard/
  4. https://wiki.debian.org/Subkeys
  5. https://jclement.ca/articles/2015/gpg-smartcard/ as modernized version of (3)
  6. https://www.esev.com/blog/post/2015-01-pgp-ssh-key-on-yubikey-neo/ similar style, with ssh and gnome-keyring infos
  7. http://karlgrz.com/2fa-gpg-ssh-keys-with-pass-and-yubikey-neo/ also good reading
  8. https://help.riseup.net/en/security/message-security/openpgp/best-practices good and concise advise on gpg practices
My writing is mostly based on (5) with additions from (4). Please let me know of any errors, improvements, and fixes. I hope this walk-through might help others in the same situation.

19 April 2016

Michal &#268;iha&#345;: Weekly phpMyAdmin contributions 2016-W15

After weeks of bugfixing my focus has again shifted to refactoring and code cleanups. One big area was charsets and collations, which were cached in the session data so far. This had bad effect of making the session data quite huge leading to performance loss on every page, while the cached information is needed only on few pages. I've removed this caching, cleaned up the code and everything seems to be behave faster, even the pages which used cached content in the past. Second area was handling of file uploads. Historically we had two copies of code doing almost the same thing. I've tried to merge them and use File class for all the operations. However this code was built to handle lot of corner cases, so I'm a bit afraid of breaking some special setups. Handled issues:

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18 April 2016

Matthew Garrett: One more attempt at SATA power management

Around a year ago I wrote some patches in an attempt to improve power management on Haswell and Broadwell systems by configuring Serial ATA power management appropriately. I got a couple of reports of them triggering SATA errors for some users, couldn't reproduce them myself and so didn't have a lot of confidence in them. Time passed.

I've been working on power management stuff again this week, so it seemed like a good opportunity to revisit these. I've made a few changes and pushed a couple of trees - one against master and one against 4.5.

First, these probably only have relevance to users of mobile Intel parts in the U or S range (/proc/cpuinfo will tell you - you're looking for a four-digit number that starts with 4 (Haswell), 5 (Broadwell) or 6 (Skylake) and ends with U or S), and won't do anything unless you have SATA drives (including PCI-based SATA). To test them, first disable anything like TLP that might alter your SATA link power management policy. Then check powertop - you should only be getting to PC3 at best. Build a kernel with these patches and boot it. /sys/class/scsi_host/*/link_power_management_policy should read "firmware". Check powertop and see whether you're getting into deeper PC states. Now run your system for a while and check the kernel log for any SATA errors that you didn't see before.

Let me know if you see SATA errors and are willing to help debug this, and leave a comment if you don't see any improvement in PC states.

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15 April 2016

Tanguy Ortolo: Let's Encrypt: threat or opportunity to other certificate authorities?

Let's Encrypt is a certificate authority (CA) that just left beta stage, that provides domain name-validated (DV) X.509 certificates for free and in an automated way: users just have to run a piece of software on their server to get and install a certificate, resulting in a valid TLS setup. A threat to other certificate authorities By providing certificates for free and automatically, Let's Encrypt is probably a threat a other CAs, a least for part of their activity. Indeed, for people that are satisfied with DV certificates, there are not many reasons to pay a commercial CA to get certificates in a non-automated way. For the CAcert non-commercial CA, that may mean a slow death, as this is their main activity . For people that want organization-validated (OV) or extended validation (EV) certificates, Let's Encrypt is not suitable, so it will not change anything regarding that. An opportunity for the most reactive The entrance of Let's Encrypt is also a significant opportunity for the certificate authorities that will be reactive enough to take advantage of their innovation. Indeed, they introduced automation in both domain name validation and certificate issuance (and revocation), by defining an open protocol that is meant to become an Internet standard. That protocol, named ACME, is not tied to Let's Encrypt and has several free software implementations, so it could be used for the same purpose by commercial CAs. A certification authority could, for instance: Such processes may require or benefit from improvements of the ACME protocol, which is the very reason Internet standards are defined in an open way. The first certification authority that would implement such a process could gain an advantage over its competitors, as it would greatly simplify getting and renewing certificates. I think even Let's Encrypt people would be happy to see that happen, as it would serve their goal, that is basically to help securing the Internet! Personally, I could buy such a service (assuming it is not restricted to juridical persons, according to a quite common (and detestable) sale discrimination against natural persons ). Notes
  1. CAcert is an unrecognised certificate authority, that provides an identity validation through a web of trust, and issues DV server certificates that do not include the validated identity. Now that Let's Encrypt can issue valid DV certificates, CAcert is no longer relevant for that activity. It also issues personal certificates, that do include the validated identity, and that can be used for encryption (e.g. S/MIME), signing (e.g. code signing) or authentication, which is an activity Let's Encrypt does not compete with.
  2. Yes, the Organization field of a certificate is probably not relevant to indicate a physical person's name, but the CommonName field is. Yes, that field is usually abused to store the domain name, but a proper use would be to put the owner's name in the CommonName field, and the domain names in the subjectAltName field.

Matthew Garrett: David MacKay

The first time I was paid to do software development came as something of a surprise to me. I was working as a sysadmin in a computational physics research group when a friend asked me if I'd be willing to talk to her PhD supervisor. I had nothing better to do, so said yes. And that was how I started the evening having dinner with David MacKay, and ended the evening better fed, a little drunker and having agreed in principle to be paid to write free software.

I'd been hired to work on Dasher, an information-efficient text entry system. It had been developed by one of David's students as a practical demonstration of arithmetic encoding after David had realised that presenting a visualisation of an effective compression algorithm allowed you to compose text without having to enter as much information into the system. At first this was merely a neat toy, but it soon became clear that the benefits of Dasher had a great deal of overlap with good accessibility software. It required much less precision of input, it made it easy to correct mistakes (you merely had to reverse direction in order to start zooming back out of the text you had entered) and it worked with a variety of input technologies from mice to eye tracking to breathing. My job was to take this codebase and turn it into a project that would be interesting to external developers.

In the year I worked with David, we turned Dasher from a research project into a well-integrated component of Gnome, improved its support for Windows, accepted code from an external contributor who ported it to OS X (using an OpenGL canvas!) and wrote ports for a range of handheld devices. We added code that allowed Dasher to directly control the UI of other applications, making it possible for people to drive word processors without having to leave Dasher. We taught Dasher to speak. We strove to avoid the mistakes present in so many other pieces of accessibility software, such as configuration that could only be managed by an (expensive!) external consultant. And we visited Dasher users and learned how they used it and what more they needed, then went back home and did what we could to provide that.

Working on Dasher was an incredible opportunity. I was involved in the development of exciting code. I spoke on it at multiple conferences. I became part of the Gnome community. I visited the USA for the first time. I entered people's homes and taught them how to use Dasher and experienced their joy as they realised that they could now communicate up to an order of magnitude more quickly. I wrote software that had a meaningful impact on the lives of other people.

Working with David was certainly not easy. Our weekly design meetings were, charitably, intense. He had an astonishing number of ideas, and my job was to figure out how to implement them while (a) not making the application overly complicated and (b) convincing David that it still did everything he wanted. One memorable meeting involved me gradually arguing him down from wanting five new checkboxes to agreeing that there were only two combinations that actually made sense (and hence a single checkbox) - and then admitting that this was broadly equivalent to an existing UI element, so we could just change the behaviour of that slightly without adding anything. I took the opportunity to delete an additional menu item in the process.

I was already aware of the importance of free software in terms of developers, but working with David made it clear to me how important it was to users as well. A community formed around Dasher, helping us improve it and allowing us to develop support for new use cases that made the difference between someone being able to type at two words per minute and being able to manage twenty. David saw that this collaborative development would be vital to creating something bigger than his original ideas, and it succeeded in ways he couldn't have hoped for.

I spent a year in the group and then went back to biology. David went on to channel his strong feelings about social responsibility into issues such as sustainable energy, writing a freely available book on the topic. He served as chief adviser to the UK Department of Energy and Climate Change for five years. And earlier this year he was awarded a knighthood for his services to scientific outreach.

David died yesterday. It's unlikely that I'll ever come close to what he accomplished, but he provided me with much of the inspiration to try to do so anyway. The world is already a less fascinating place without him.

comment count unavailable comments

14 April 2016

Michal &#268;iha&#345;: Gammu 1.37.2

Yesterday, Gammu 1.37.1 and Gammu 1.37.2 have been released. As usual it collects bug fixes and minor improvements. Full list of changes in 1.37.1: Full list of changes in 1.37.2: Would you like to see more features in Gammu? You an support further Gammu development at Bountysource salt or by direct donation.

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13 April 2016

Michal &#268;iha&#345;: Weekly phpMyAdmin contributions 2016-W14

Last week was focused on our SQL parser as several issues have been found there. If was for me also first release of SQL parser to packagist repository. Besides code changes, there was quite some time spent on reviewing incoming issues. Most of they have been already fixed and users will get fixes in the 4.6.1 release. Handled issues:

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11 April 2016

Matthew Garrett: Making it easier to deploy TPMTOTP on non-EFI systems

I've been working on TPMTOTP a little this weekend. I merged a pull request that adds command-line argument handling, which includes the ability to choose the set of PCRs you want to seal to without rebuilding the tools, and also lets you print the base32 encoding of the secret rather than the qr code so you can import it into a wider range of devices. More importantly it also adds support for setting the expected PCR values on the command line rather than reading them out of the TPM, so you can now re-seal the secret against new values before rebooting.

I also wrote some new code myself. TPMTOTP is designed to be usable in the initramfs, allowing you to validate system state before typing in your passphrase. Unfortunately the initramfs itself is one of the things that's measured. So, you end up with something of a chicken and egg problem - TPMTOTP needs access to the secret, and the obvious thing to do is to put the secret in the initramfs. But the secret is sealed against the hash of the initramfs, and so you can't generate the secret until after the initramfs. Modify the initramfs to insert the secret and you change the hash, so the secret is no longer released. Boo.

On EFI systems you can handle this by sticking the secret in an EFI variable (there's some special-casing in the code to deal with the additional metadata on the front of things you read out of efivarfs). But that's not terribly useful if you're not on an EFI system. Thankfully, there's a way around this. TPMs have a small quantity of nvram built into them, so we can stick the secret there. If you pass the -n argument to sealdata, that'll happen. The unseal apps will attempt to pull the secret out of nvram before falling back to looking for a file, so things should just magically work.

I think it's pretty feature complete now, other than TPM2 support? That's on my list.

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8 April 2016

Colin Watson: No more Hash Sum Mismatch errors

The Debian repository format was designed a long time ago. The oldest versions of it were produced with the help of tools such as dpkg-scanpackages and consumed by dselect access methods such as dpkg-ftp. The access methods just fetched a Packages file (perhaps compressed) and used it as an index of which packages were available; each package had an MD5 checksum to defend against transport errors, but being from a more innocent age there was no repository signing or other protection against man-in-the-middle attacks. An important and intentional feature of the early format was that, apart from the top-level Packages file, all other files were static in the sense that, once published, their content would never change without also changing the file name. This means that repositories can be efficiently copied around using rsync without having to tell it to re-checksum all files, and it avoids network races when fetching updates: the repository you re updating from might change in the middle of your update, but as long as the repository maintenance software keeps superseded packages around for a suitable grace period, you ll still be able to fetch them. The repository format evolved rather organically over time as different needs arose, by what one might call distributed consensus among the maintainers of the various client tools that consumed it. Of course all sorts of fields were added to the index files themselves, which have an extensible format so that this kind of thing is usually easy to do. At some point a Sources index for source packages was added, which worked pretty much the same way as Packages except for having a different set of fields. But by far the most significant change to the repository structure was the package pools project. The original repository layout put the packages themselves under the dists/ tree along with the index files. The dists/ tree is organised by suite (modern examples of which would be stable , stable-updates , testing , unstable , xenial , xenial-updates , and so on). This meant that making a release of Debian tended to involve copying lots of data around, and implementing the testing suite would have been very costly. Package pools solved this problem by moving individual package files out of dists/ and into a new pool/ tree, allowing those files to be shared between multiple suites with only a negligible cost in disk space and mirror bandwidth. From a database design perspective this is obviously much more sensible. As part of this project, the original Debian dinstall repository maintenance scripts were replaced by da-katie or dak , which among other things used a new apt-ftparchive program to build the index files; this replaced dpkg-scanpackages and dpkg-scansources, and included its own database cache which made a big difference to performance at the scale of a distribution. A few months after the initial implementation of package pools, Release files were added. These formed a sort of meta-index for each suite, telling APT which index files were available (main/binary-i386/Packages, non-free/source/Sources, and so on) and what their checksums were. Detached signatures were added alongside that (Release.gpg) so that it was now possible to fetch packages securely given a public key for the repository, and client-side verification support for this eventually made its way into Debian and Ubuntu. The repository structure stayed more or less like this for several years. At some point along the way, those of us by now involved in repository maintenance realised that an important property had been lost. I mentioned earlier that the original format allowed race-free updates, but this was no longer true with the introduction of the Release file. A client now had to fetch Release and then fetch whichever other index files such as Packages they wanted, typically in separate HTTP transactions. If a client was unlucky, these transactions would fall on either side of a mirror update and they d get a Hash Sum Mismatch error from APT. Worse, if a mirror was unlucky and also didn t go to special lengths to verify index integrity (most don t), its own updates could span an update of its upstream mirror and then all its clients would see mismatches until the next mirror update. This was compounded by using detached signatures, so Release and Release.gpg were fetched separately and could be out of sync. Fixing this has been a long road (the first time I remember talking about this was in late 2007!), and we ve had to take care to maintain client/server compatibility along the way. The first step was to add inline-signed versions of the Release file, called InRelease, so that there would no longer be a race between fetching Release and fetching its signature. APT has had this for a while, Debian s repository supports it as of stretch, and we finally implemented it for Ubuntu six months ago. Dealing with the other index files is more complicated, though; it isn t sensible to inline them, as clients usually only need to fetch a small fraction of all the indexes available for a given suite. The solution we ve ended up with, thanks to Michael Vogt s work implementing it in APT, is called by-hash and should be familiar in concept to people who ve used git: with the exception of the top-level InRelease file, index files for suites that support the by-hash mechanism may now be fetched using a URL based on one of their hashes listed in InRelease. This means that clients can now operate like this: This is now enabled by default in Ubuntu. It s only there as of xenial (16.04), since earlier versions of Ubuntu don t have the necessary support in APT. With this, hash mismatches on updates should be a thing of the past. There will still be some people who won t yet benefit from this. debmirror doesn t support by-hash yet; apt-cacher-ng only supports it as of xenial, although there s an easy configuration workaround. Full archive mirrors must make sure that they put new by-hash files in place before new InRelease files (I just fixed our recommended two-stage sync script to do this; ubumirror still needs some work; Debian s ftpsync is almost correct but needs a tweak for its handling of translation files, which I ve sent to its maintainers). Other mirrors and proxies that have specific handling of the repository format may need similar changes. Please let me know if you see strange things happening as a result of this change. It s useful to check the output of apt -o Debug::Acquire::http=true update to see exactly what requests are being issued.

6 April 2016

Michal &#268;iha&#345;: API for Weblate

The long requested feature for Weblate is here - it now has API which you can use to control it. It's scope is currently limited, but it will expand in future releases. The API is currently available in Git, deployed on both Demo server and Hosted Weblate, our hosted solution. It will be also part of 2.6 release, which should be released by end of April. Anyway the API now provides basic operations up to translation level - you can not edit individual translations, handle suggestions or other advanced features. However what you can do includes: As you can see this really covers the basic operations which were most frequently requested, more will come in future. You can see more detailed the Weblate API documentation.

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5 April 2016

Ian Wienand: Image building in OpenStack CI

Also titled minimal images - maximal effort! The OpenStack Infrastructure Team manages a large continuous-integration system that provides the broad range of testing the OpenStack project requires. Tests are run thousands of times a day across every project, on multiple platforms and on multiple cloud-providers. There are essentially no manual steps in any part of the process, with every component being automated via scripting, a few home-grown tools and liberal doses of Puppet and Ansible. More importantly, every component resides in the public git trees right alongside every other OpenStack project, with contributions actively encouraged. As with any large system, technical debt can build up and start to affect stability and long-term maintainability. OpenStack Infrastructure can see some of this debt accumulating as more testing environments across more cloud-providers are being added to support ever-growing testing demands. Thus a strong focus of recent work has been consolidating testing platforms to be smaller, better defined and more maintainable. This post illustrates some of the background to the issues and describes how these new platforms are more reliable and maintainable.
OpenStack CI Overview Before getting into details, it's a good idea to get a basic big-picture conceptual model of how OpenStack CI testing works. If you look at the following diagram and follow the numbers with the explanation below, hopefully you'll have all the context you need. Overview of OpenStack CI
  1. The developer uploads their code to gerrit via the git-review tool. There is no further action required on their behalf and the developer simply waits for results.

  2. Gerrit provides a JSON-encoded "firehose" output of everything happening to it. New reviews, votes, updates and more all get sent out over this pipe. Zuul is the overall scheduler that subscribes itself to this information and is responsible for managing the CI jobs appropriate for each change.

  3. Zuul has a configuration that tells it what jobs to run for what projects. Zuul can do lots of interesting things, but for the purposes of this discussion we just consider that it puts the jobs it wants run into gearman for a Jenkins master to consume. gearman is a job-server; as they explain it "[gearman] provides a generic application framework to farm out work to other machines or processes that are better suited to do the work". Zuul puts into gearman basically a tuple (job-name, node-type) for each job it wants run, specifying the unique job name to run and what type of node it should be run on.

  4. A group of Jenkins masters are subscribed to gearman as workers. It is these Jenkins masters that will consume the job requests from the queue and actually get the tests running. However, Jenkins needs two things to be able to run a job a job definition (what to actually do) and a slave node (somewhere to do it). The first part what to do is provided by job-definitions stored in external YAML files and processed by Jenkins Job Builder (jjb) in to job configurations for Jenkins. Each Jenkins master gets these definitions pushed to it constantly by Puppet, thus each Jenkins master instance knows about all the jobs it can run automatically. Zuul also knows about these job definitions; this is the job-name part of the tuple we said it put into gearman. The second part somewhere to run the test takes some more explaining. To the next point...

  5. Several cloud companies donate capacity in their clouds for OpenStack to run CI tests. Overall, this capacity is managed by a customised orchestration tool called nodepool. Nodepool watches the gearman queue and sees what requests are coming out of Zuul. It looks at node-type of jobs in the queue and decides what types of nodes need to start and which cloud providers have capacity to satisfy demand. Nodepool will monitor the start-up of the virtual-machines and register the new nodes to the Jenkins master instances.

  6. At this point, the Jenkins master has what it needs to actually get jobs started. When nodepool registers a host to a Jenkins master as a slave, the Jenkins master can now advertise its ability to consume jobs. For example, if a ubuntu-trusty node is provided to the Jenkins master instance by nodepool, Jenkins can now consume from gearman any job it knows about that is intended to run on an ubuntu-trusty slave. Jekins will run the job as defined in the job-definition on that host ssh-ing in, running scripts, copying the logs and waiting for the result. (It is a gross oversimplification, but for the purposes of OpenStack CI, Jenkins is pretty much used as a glorified ssh/scp wrapper. Zuul Version 3, under development, is working to remove the need for Jenkins to be involved at all).

  7. Eventually, the test will finish. The Jenkins master will put the result back into gearman, which Zuul will consume. The slave will be released back to nodepool, which destroys it and starts all over again (slaves are not reused and also have no sensitive details on them, as they are essentially publicly accessible). Zuul will wait for the results of all jobs for the change and post the result back to Gerrit; it either gives a positive vote or the dreaded negative vote if required jobs failed (it also handles merges to git, but we'll ignore that bit for now).

In a nutshell, that is the CI work-flow that happens thousands-upon-thousands of times a day keeping OpenStack humming along.
Image builds So far we have glossed over how nodepool actually creates the images that it hands out for testing. Image creation, illustrated in step 8 above, contains a lot of important details. Firstly, what are these images and why build them at all? These images are where the "rubber hits the road" they are instantiated into the virtual-machines that will run DevStack, unit-testing or whatever else someone might want to test. The main goal is to provide a stable and consistent environment in which to run a wide-range of tests. A full OpenStack deployment results in hundreds of libraries and millions of lines of code all being exercised at once. The testing-images are right at the bottom of all this, so any instability or inconsistency affects everyone; leading to constant fire-firefighting and major inconvenience as all forward-progress stops when CI fails. We want to support a wide number of platforms interesting to developers such as Ubuntu, Debian, CentOS and Fedora, and we also want to and make it easy to handle new releases and add other platforms. We want to ensure this can be maintained without too much day-to-day hands-on. Caching is a big part of the role of these images. With thousands of jobs going on every day, an occasional network blip is not a minor annoyance, but creates constant and difficult to debug failures. We want jobs to rely on as few external resources as possible so tests are consistent and stable. This means caching things like the git trees tests might use (OpenStack just broke the 1000 repository mark), VM images, packages and other common bits and pieces. Obviously a cache is only as useful as the data in it, so we build these images up every day to keep them fresh.
Snapshot images If you log into almost any cloud-provider's interface, they almost certainly have a range of pre-canned images of common distributions for you to use. At first, the base images for OpenStack CI testing came from what the cloud-providers had as their public image types. However, over time, there are a number of issues that emerge:
  1. No two images, even for the same distribution or platform, are the same. Every provider seems to do something "helpful" to the images which requires some sort of workaround.
  2. Providers rarely leave these images alone. One day you would boot the image to find a bunch of Python libraries pip-installed, or a mount-point moved, or base packages removed (all happened).
  3. Even if the changes are helpful, it does not make for consistent and reproducible testing if every time you run, you're on a slightly different base system.
  4. Providers don't have some images you want (like a latest Fedora), or have different versions, or different point releases. All update asynchronously whenever they get around to it.
So the original incarnations of OpenStack CI images were based on these public images. Nodepool would start one of these provider images and then run a series of scripts on it these scripts would firstly try to work-around any quirks to make the images look as similar as possible across providers, and then do the caching, setup things like authorized keys and finish other configuration tasks. Nodepool would then snapshot this prepared image and start instantiating VM's from these snapshots into the pool for testing. If you hear someone talking about a "snapshot image" in OpenStack CI context, that's likely what they are referring to. Apart from the stability of the underlying images, the other issue you hit with this approach is that the number of images being built starts to explode when you take into account multiple providers and multiple regions. Even with just Rackspace and the (now defunct) HP Cloud we would end up creating snapshot images for 4 or 5 platforms across a total of about 8 regions meaning anywhere up to 40 separate image builds happening daily (you can see how ridiculous it was getting in the logging configuration used at the time). It was almost a fait accompli that some of these would fail every day nodepool can deal with this by reusing old snapshots but this leads to a inconsistent and heterogeneous testing environment. Naturally there was a desire for something more consistent a single image that could run across multiple providers in a much more tightly controlled manner.
Upstream-based builds Upstream distributions do provide "cloud-images", which are usually pre-canned .qcow2 format files suitable for uploading to your average cloud. So the diskimage-builder tool was put into use creating images for nodepool, based on these upstream-provided images. In essence, diskimage-builder uses a series of elements (each, as the name suggests, designed to do one thing) that allow you to build a completely customised image. It handles all the messy bits of laying out the image file, tries to be smart about caching large downloads and final things like conversion to qcow2 or vhd. nodepool has used diskimage-builder to create customised images based upon the upstream releases for some time. These are better, but still have some issues for the CI environment:
  1. You still really have no control over what does or does not go into the upstream base images. You don't notice a change until you deploy a new image based on an updated version and things break.
  2. The images still start with a fair amount of "stuff" on them. For example cloud-init is a rather large Python program and has a fair few dependencies. These dependencies can both conflict with parts of OpenStack or end up tacitly hiding real test requirements (the test doesn't specify it, but the package is there as part of another base dependency. Things then break when the base dependencies change). The whole idea of the CI is that (as much as possible) you're not making any assumptions about what is required to run your tests you want everything explicitly included.
  3. An image that "works everywhere" across multiple cloud-providers is quite a chore. cloud-init hasn't always had support for config-drive and Rackspace's DHCP-less environment, for example. Providers all have their various different networking schemes or configuration methods which needs to be handled consistently.
If you were starting this whole thing again, things like LXC/Docker to keep "systems within systems" might come into play and help alleviate some of the packaging conflicts. Indeed they may play a role in the future. But don't forget that DevStack, the major CI deployment mechanism, was started before Docker existed. And there's tricky stuff with networking and Neutron going on. And things like iSCSI kernel drivers that containers don't support well. And you need to support Ubuntu, Debian, CentOS and Fedora. And you have hundreds of developers already relying on what's there. So change happens incrementally, and in the mean time, there is a clear need for a stable, consistent environment.
Minimal builds To this end, diskimage-builder now has a serial of "minimal" builds that are really that systems with essentially nothing on them. For Debian and Ubuntu this is achieved via debootstrap, for Fedora and CentOS we replicate this with manual installs of base packages into a clean chroot environment. We add on a range of important elements that make the image useful; for example, for networking, we have simple-init which brings up the network consistently across all our providers but has no dependencies to mess with the base system. If you check the elements provided by project-config you can see a range of specific elements that OpenStack Infra runs at each image build (these are actually specified by in arguments to nodepool, see the config file, particularly diskimages section). These custom elements do things like caching, using puppet to install the right authorized_keys files and setup a few needed things to connect to the host. In general, you can see the logs of an image build provided by nodepool for each daily build. So now, each day at 14:14 UTC nodepool builds the daily images that will be used for CI testing. We have one image of each type that (theoretically) works across all our providers. After it finishes building, nodepool uploads the image to all providers (p.s. the process of doing this is so insanely terrible it spawned shade; this deserves many posts of its own) at which point it will start being used for CI jobs. If you wish to replicate this entire process, the build-image.sh script, run on an Ubuntu Trusty host in a virtualenv with diskimage-builder will get you pretty close (let us know of any issues!).
DevStack and bare nodes There are two major ways OpenStack projects test their changes:
  1. Running with DevStack, which brings up a small, but fully-functional, OpenStack cloud with the change-under-test applied. Generally tempest is then used to ensure the big-picture things like creating VM's, networks and storage are all working.
  2. Unit-testing within the project; i.e. what you do when you type tox -e py27 in basically any OpenStack project.
To support this testing, OpenStack CI ended up with the concept of bare nodes and devstack nodes.
  • A bare node was made for unit-testing. While tox has plenty of information about installing required Python packages into the virtualenv for testing, it doesn't know anything about the system packages required to build those Python packages. This means things like gcc and library -devel packages which many Python packages use to build bindings. Thus the bare nodes had an ever-growing and not well-defined list of packages that were pre-installed during the image-build to support unit-testing. Worse still, projects didn't really know their dependencies but just relied on their testing working with this global list that was pre-installed on the image.
  • In contrast to this, DevStack has always been able to bootstrap itself from a blank system to a working OpenStack deployment by ensuring it has the right dependencies installed. We don't want any packages pre-installed here because it hides actual dependencies that we want explicitly defined within DevStack otherwise, when a user goes to deploy DevStack for their development work, things break because their environment differs slightly to the CI one. If you look at all the job definitions in OpenStack, by convention any job running DevStack has a dsvm in the job name this referred to running on a "DevStack Virtual Machine" or a devstack node. As the CI environment has grown, we have more and more testing that isn't DevStack based (puppet apply tests, for example) that rather confusingly want to run on a devstack node because they do not want dependencies installed. While it's just a name, it can be difficult to explain!
Thus we ended up maintaining two node-types, where the difference between them is what was pre-installed on the host and yes, the bare node had more installed than a devstack node, so it wasn't that bare at all!
Specifying Dependencies Clearly it is useful to unify these node types, but we still need to provide a way for the unit-test environments to have their dependencies installed. This is where a tool called bindep comes in. This tool gives project authors a way to specify their system requirements in a similar manner to the way their Python requirements are kept. For example, OpenStack has the concept of global requirements those Python dependencies that are common across all projects so version skew becomes somewhat manageable. This project now has some extra information in the other-requirements.txt file, which lists the system packages required to build the Python packages in the global-requirements list. bindep knows how to look at these lists provided by projects and get the right packages for the platform it is running on. As part of the image-build, we have a cache-bindep element that can go through every project and build a list of the packages it requires. We can thus pre-cache all of these packages onto the images, knowing that they are required by jobs. This both reduces the dependency on external mirrors and improves job performance (as the packages are locally cached) but doesn't pollute the system by having everything pre-installed. Package installation can now happen via the way we really should be doing it as part of the CI job. There is a job-macro called install-distro-packages which a test can use to call bindep to install the packages specified by the project before the run. You might notice the script has a "fallback" list of packages if the project does not specify it's own dependencies this essentially replicates the environment of a bare node as we transition to projects more strictly specifying their system requirements. We can now start with a blank image and all the dependencies to run the job can be expressed by and within the project leading to a consistent and reproducible environment without any hidden dependencies. Several things have broken as part of removing bare nodes this is actually a good thing because it means we have revealed areas where we were making assumptions in jobs about what the underlying platform provides. There's a few other job-macros that can do things like provide MySQL/Postgres instances for testing or setup other common job requirements. By splitting these types of things out from base-images we also improve the performance of jobs who don't waste time doing things like setting up databases for jobs that don't need it. As of this writing, the bindep work is new and still a work-in-progress. But the end result is that we have no more need for a separate bare node type to run unit-tests. This essentially halves the number of image-builds required and brings us to the goal of a single image for each platform running all CI.
Conclusion While dealing with multiple providers, image-types and dependency chains has been a great effort for the infra team, to everyone's credit I don't think the project has really noticed much going on underneath. OpenStack CI has transitioned to a situation where there is a single image type for each platform we test that deploys unmodified across all our providers and runs all testing environments equally. We have better insight into our dependencies and better tools to manage them. This leads to greatly decreased maintenance burden, better consistency and better performance; all great things to bring to OpenStack CI!

Michal &#268;iha&#345;: Weekly phpMyAdmin contributions 2016-W13

Last week was mostly vacation for me, so I'm publishing this report more for not missing one rather than to provide real report. I've spent only little of time on last Tuesday on reviewing issues and there was no coding involved. Handled issues:

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4 April 2016

Matthew Garrett: TPMs, event logs, fine-grained measurements and avoiding fragility in remote-attestation

Trusted Platform Modules are fairly unintelligent devices. They can do some crypto, but they don't have any ability to directly monitor the state of the system they're attached to. This is worked around by having each stage of the boot process "measure" state into registers (Platform Configuration Registers, or PCRs) in the TPM by taking the SHA1 of the next boot component and performing an extend operation. Extend works like this:

New PCR value = SHA1(current value new hash)

ie, the TPM takes the current contents of the PCR (a 20-byte register), concatenates the new SHA1 to the end of that in order to obtain a 40-byte value, takes the SHA1 of this 40-byte value to obtain a 20-byte hash and sets the PCR value to this. This has a couple of interesting properties:But how do we know what those operations were? We control the bootloader and the kernel and we know what extend operations they performed, so that much is easy. But the firmware itself will have performed some number of operations (the firmware itself is measured, as is the firmware configuration, and certain aspects of the boot process that aren't in our control may also be measured) and we may not be able to reconstruct those from scratch.

Thankfully we have more than just the final PCR data. The firmware provides an interface to log each extend operation, and you can read the event log in /sys/kernel/security/tpm0/binary_bios_measurements. You can pull information out of that log and use it to reconstruct the writes the firmware made. Merge those with the writes you performed and you should be able to reconstruct the final TPM state. Hurrah!

The problem is that a lot of what you want to measure into the TPM may vary between machines or change in response to configuration changes or system updates. If you measure every module that grub loads, and if grub changes the order that it loads modules in, you also need to update your calculations of the end result. Thankfully there's a way around this - rather than making policy decisions based on the final TPM value, just use the final TPM value to ensure that the log is valid. If you extract each hash value from the log and simulate an extend operation, you should end up with the same value as is present in the TPM. If so, you know that the log is valid. At that point you can examine individual log entries without having to care about the order that they occurred in, which makes writing your policy significantly easier.

But there's another source of fragility. Imagine that you're measuring every command executed by grub (as is the case in the CoreOS grub). You want to ensure that no inappropriate commands have been run (such as ones that would allow you to modify the loaded kernel after it's been measured), but you also want to permit certain variations - for instance, you might have a primary root filesystem and a fallback root filesystem, and you're ok with either being passed as a kernel argument. One approach would be to write two lines of policy, but there's an even more flexible approach. If the bootloader logs the entire command into the event log, when replaying the log we can verify that the event description hashes to the value that was passed to the TPM. If it does, rather than testing against an explicit hash value, we can examine the string itself. If the event description matches a regular expression provided by the policy then we're good.

This approach makes it possible to write TPM policies that are resistant to changes in ordering and permit fine-grained definition of acceptable values, and which can cleanly separate out local policy, generated policy values and values that are provided by the firmware. The split between machine-specific policy and OS policy allows for the static machine-specific policy to be merged with OS-provided policy, making remote attestation viable even over automated system upgrades.

We've integrated an implementation of this kind of policy into the TPM support code we'd like to integrate into Kubernetes, and CoreOS will soon be generating known-good hashes at image build time. The combination of these means that people using Distributed Trusted Computing under Tectonic will be able to validate the state of their systems with nothing more than a minimal machine-specific policy description.

The support code for all of this should also start making it into other distributions in the near future (the grub code is already in Fedora 24), so with luck we can define a cross-distribution policy format and make it straightforward to handle this in a consistent way even in hetrogenous operating system environments. Remote attestation is a powerful tool for ensuring that your systems are in a valid state, but the difficulty of policy management has been a significant factor in making it difficult for people to deploy in their data centres. Making it easier for people to shield themselves against low-level boot attacks is a big step forward in improving the security of distributed workloads and makes bare-metal hosting a much more viable proposition.

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