Search Results: "Guillem Jover"

5 March 2022

Reproducible Builds: Reproducible Builds in February 2022

Welcome to the February 2022 report from the Reproducible Builds project. In these reports, we try to round-up the important things we and others have been up to over the past month. As ever, if you are interested in contributing to the project, please visit our Contribute page on our website.
Jiawen Xiong, Yong Shi, Boyuan Chen, Filipe R. Cogo and Zhen Ming Jiang have published a new paper titled Towards Build Verifiability for Java-based Systems (PDF). The abstract of the paper contains the following:
Various efforts towards build verifiability have been made to C/C++-based systems, yet the techniques for Java-based systems are not systematic and are often specific to a particular build tool (eg. Maven). In this study, we present a systematic approach towards build verifiability on Java-based systems.

GitBOM is a flexible scheme to track the source code used to generate build artifacts via Git-like unique identifiers. Although the project has been active for a while, the community around GitBOM has now started running weekly community meetings.
The paper Chris Lamb and Stefano Zacchiroli is now available in the March/April 2022 issue of IEEE Software. Titled Reproducible Builds: Increasing the Integrity of Software Supply Chains (PDF), the abstract of the paper contains the following:
We first define the problem, and then provide insight into the challenges of making real-world software build in a reproducible manner-this is, when every build generates bit-for-bit identical results. Through the experience of the Reproducible Builds project making the Debian Linux distribution reproducible, we also describe the affinity between reproducibility and quality assurance (QA).

In openSUSE, Bernhard M. Wiedemann posted his monthly reproducible builds status report.
On our mailing list this month, Thomas Schmitt started a thread around the SOURCE_DATE_EPOCH specification related to formats that cannot help embedding potentially timezone-specific timestamp. (Full thread index.)
The Yocto Project is pleased to report that it s core metadata (OpenEmbedded-Core) is now reproducible for all recipes (100% coverage) after issues with newer languages such as Golang were resolved. This was announced in their recent Year in Review publication. It is of particular interest for security updates so that systems can have specific components updated but reducing the risk of other unintended changes and making the sections of the system changing very clear for audit. The project is now also making heavy use of equivalence of build output to determine whether further items in builds need to be rebuilt or whether cached previously built items can be used. As mentioned in the article above, there are now public servers sharing this equivalence information. Reproducibility is key in making this possible and effective to reduce build times/costs/resource usage.

diffoscope diffoscope is our in-depth and content-aware diff utility. Not only can it locate and diagnose reproducibility issues, it can provide human-readable diffs from many kinds of binary formats. This month, Chris Lamb prepared and uploaded versions 203, 204, 205 and 206 to Debian unstable, as well as made the following changes to the code itself:
  • Bug fixes:
    • Fix a file(1)-related regression where Debian .changes files that contained non-ASCII text were not identified as such, therefore resulting in seemingly arbitrary packages not actually comparing the nested files themselves. The non-ASCII parts were typically in the Maintainer or in the changelog text. [ ][ ]
    • Fix a regression when comparing directories against non-directories. [ ][ ]
    • If we fail to scan using binwalk, return False from BinwalkFile.recognizes. [ ]
    • If we fail to import binwalk, don t report that we are missing the Python rpm module! [ ]
  • Testsuite improvements:
    • Add a test for recent file(1) issue regarding .changes files. [ ]
    • Use our assert_diff utility where we can within the set of tests. [ ]
    • Don t run our binwalk-related tests as root or fakeroot. The latest version of binwalk has some new security protection against this. [ ]
  • Codebase improvements:
    • Drop the _PATH suffix from module-level globals that are not paths. [ ]
    • Tidy some control flow in Difference._reverse_self. [ ]
    • Don t print a warning to the console regarding NT_GNU_BUILD_ID changes. [ ]
In addition, Mattia Rizzolo updated the Debian packaging to ensure that diffoscope and diffoscope-minimal packages have the same version. [ ]

Website updates There were quite a few changes to the Reproducible Builds website and documentation this month as well, including:
  • Chris Lamb:
    • Considerably rework the Who is involved? page. [ ][ ]
    • Move the Bash/shell script into a Python script. [ ][ ][ ]
  • Daniel Shahaf:
    • Try a different Markdown footnote content syntax to work around a rendering issue. [ ][ ][ ]
  • Holger Levsen:
    • Make a huge number of changes to the Who is involved? page, including pre-populating a large number of contributors who cannot be identified from the metadata of the website itself. [ ][ ][ ][ ][ ]
    • Improve linking to sponsors in sidebar navigation. [ ]
    • drop sponsors paragraph as the navigation is clearer now. [ ]
    • Add Mullvad VPN as a bronze-level sponsor . [ ][ ]
  • Vagrant Cascadian:

Upstream patches The Reproducible Builds project attempts to fix as many currently-unreproducible packages as possible. February s patches included the following:

Testing framework The Reproducible Builds project runs a significant testing framework at, to check packages and other artifacts for reproducibility. This month, the following changes were made:
  • Daniel Golle:
    • Update the OpenWrt configuration to not depend on the host LLVM, adding lines to the .config seed to build LLVM for eBPF from source. [ ]
    • Preserve more OpenWrt-related build artifacts. [ ]
  • Holger Levsen:
  • Temporary use a different Git tree when building OpenWrt as our tests had been broken since September 2020. This was reverted after the patch in question was accepted by Paul Spooren into the canonical openwrt.git repository the next day.
    • Various improvements to debugging OpenWrt reproducibility. [ ][ ][ ][ ][ ]
    • Ignore useradd warnings when building packages. [ ]
    • Update the script to powercycle armhf architecture nodes to add a hint to where nodes named virt-*. [ ]
    • Update the node health check to also fix failed logrotate and man-db services. [ ]
  • Mattia Rizzolo:
    • Update the website job after script was rewritten in Python. [ ]
    • Make sure to set the DIFFOSCOPE environment variable when available. [ ]
  • Vagrant Cascadian:
    • Various updates to the diffoscope timeouts. [ ][ ][ ]
Node maintenance was also performed by Holger Levsen [ ] and Vagrant Cascadian [ ].

Finally If you are interested in contributing to the Reproducible Builds project, please visit our Contribute page on our website. However, you can get in touch with us via:

16 February 2021

Michael Prokop: How to properly use 3rd party Debian repository signing keys with apt

(Blogging this, since this is a recurring anti-pattern I noticed at several customers and often comes up during deployments of 3rd party repositories.) Update on 2021-02-19: clarified, that Signed-By requires apt >= 1.1, thanks Vincent Bernat Many upstream projects provide Debian repository instructions like this:
curl -fsSL   sudo apt-key add -
Do not follow this, for different reasons, including:
  1. You do not see what you get before adding the GPG key to your global apt trust store
  2. You can t easily script this via your preferred configuration management (the apt-key manpage clearly discourages programmatic usage)
  3. The signing key is considered valid for all your enabled Debian repositories (instead of only a specific one)
  4. You need GnuPG (either gnupg2 or gnupg1) on your system for usage with apt-key
There s a much better approach to this: download the GPG key, make sure it s in the appropriate format, then use it via deb [signed-by=/usr/share/keyrings/ ] in your apt s sources list configuration. Note and FTR: the Signed-By feature is available starting with apt 1.1 (so apt in Debian jessie/8 and older does not support it). TL;DR: As an example, let s demonstrate this with the Tailscale Debian repository for buster.
Downloading the GPG file will give you an ascii-armored GPG file:
% curl -fsSL -o buster.gpg
% gpg --keyid-format long buster.gpg 
gpg: WARNING: no command supplied.  Trying to guess what you mean ...
pub   rsa4096/458CA832957F5868 2020-02-25 [SC]
uid                           Tailscale Inc. (Package repository signing key) <>
sub   rsa4096/B1547A3DDAAF03C6 2020-02-25 [E]
% file buster.gpg
buster.gpg: PGP public key block Public-Key (old)
If you have apt version >= 1.4 available (Debian >=stretch/9 and Ubuntu >=bionic/18.04), you can use this file directly as follows:
% sudo mv buster.gpg /usr/share/keyrings/tailscale.asc
% cat /etc/apt/sources.list.d/tailscale.list
deb [signed-by=/usr/share/keyrings/tailscale.asc] buster main
% sudo apt update
And you re done! Iff your apt version really is older than 1.4, you need to convert the ascii-armored GPG file into a GPG key public ring file (AKA binary OpenPGP format), either by just dearmor-ing it (if you don t care about checking ID + fingerprint):
% gpg --dearmor < buster.gpg > tailscale.gpg
or if you prefer to go via GPG, you can also use a temporary GPG home directory (if you don t care about going through your personal GPG setup):
% mkdir --mode=700 /tmp/gpg-tmpdir
% gpg --homedir /tmp/gpg-tmpdir --import ./buster.gpg
gpg: keybox '/tmp/gpg-tmpdir/pubring.kbx' created
gpg: /tmp/gpg-tmpdir/trustdb.gpg: trustdb created
gpg: key 458CA832957F5868: public key "Tailscale Inc. (Package repository signing key) <>" imported
gpg: Total number processed: 1
gpg:               imported: 1
% gpg --homedir /tmp/gpg-tmpdir --output tailscale.gpg  --export-options=export-minimal --export 0x458CA832957F5868
% rm -rf /tmp/gpg-tmpdir
The resulting GPG key public ring file should look like that:
% file tailscale.gpg 
tailscale.gpg: PGP/GPG key public ring (v4) created Tue Feb 25 04:51:20 2020 RSA (Encrypt or Sign) 4096 bits MPI=0xc00399b10bc12858...
% gpg tailscale.gpg 
gpg: WARNING: no command supplied.  Trying to guess what you mean ...
pub   rsa4096/458CA832957F5868 2020-02-25 [SC]
uid                           Tailscale Inc. (Package repository signing key) <>
sub   rsa4096/B1547A3DDAAF03C6 2020-02-25 [E]
Then you can use this GPG file on your system as follows:
% sudo mv tailscale.gpg /usr/share/keyrings/tailscale.gpg
% cat /etc/apt/sources.list.d/tailscale.list
deb [signed-by=/usr/share/keyrings/tailscale.gpg] buster main
% sudo apt update
Such a setup ensures:
  1. You can verify the GPG key file (ID + fingerprint)
  2. You can easily ship files via /usr/share/keyrings/ and refer to it in your deployment scripts, configuration management, (and can also easily update or get rid of them again!)
  3. The GPG key is valid only for the repositories with the corresponding [signed-by=/usr/share/keyrings/ ] entry
  4. You don t need to install GnuPG (neither gnupg2 nor gnupg1) on the system which is using the 3rd party Debian repository
Thanks: Guillem Jover for reviewing an early draft of this blog article.

31 January 2021

Chris Lamb: Free software activities in January 2021

Here is my monthly update covering what I have been doing in the free software world during January 2021 (previous month):

Reproducible Builds One of the original promises of open source software is that distributed peer review and transparency of process results in enhanced end-user security. However, whilst anyone may inspect the source code of free and open source software for malicious flaws, almost all software today is distributed as pre-compiled binaries. This allows nefarious third-parties to compromise systems by injecting malicious code into ostensibly secure software during the various compilation and distribution processes. The motivation behind the Reproducible Builds effort is to ensure no flaws have been introduced during this compilation process by promising identical results are always generated from a given source, thus allowing multiple third-parties to come to a consensus on whether a build was compromised. This month, I:
I also made the following changes to diffoscope, our in-depth and content-aware diff utility that can locate and diagnose reproducibility issues, releasing version 164, version 165 and version 166 as well as triaging and merging many contributions from others:

Debian Uploads Debian LTS This month I worked 18 hours on Debian Long Term Support (LTS) and 12 hours on its sister Extended LTS project. You can find out more about the project via the following video:

10 January 2021

Iustin Pop: Dealing with evil ads

Background I usually don t mind ads, as not as they not very intrusive. I get that the current media model is basically ad-funded, and that unless I want to pay $1/month or so to 50 web sites, I have to accept ads, so I don t run an ad-blocker. Sure, sometimes are annoying (hey YT, mid-roll ads are borderline), but I ve also seen many good ads, as in interesting or funny even. Well, I don t think I ever bought anything as direct result from ads, so I don t know how useful ads are for the companies, but hey, what do I care. Except there a few ad networks that run what I would say are basically revolting ads. Things I don t want to ever accidentally see while eating, or things that are really make you go WTF? Maybe you know them, maybe you don t, but I guess there are people who don t know how to clean their ears, or people for whom a fast 7 day weight loss routine actually works. Thankfully, most of the time I don t browse sites which use this networks, but randomly they do leak to even sites I do browse. If I m not very stressed already, I can ignore them, otherwise they really, really annoy me. Case in point, I was on Slashdot, and because I was logged on and recently had mod points, the right side column had a check-box disable ads . That sidebar had some relatively meaningful ads, like a VPN subscription (not that I would use it, but it is a tech thing), or even a book about Kali Linux, etc. etc. So I click the disable ads , and the right column goes away. I scroll down happily, only to be met, at the bottom, by the best way to clean your ear , the most 50 useless planes ever built (which had a drawing of something that was for sure never ever built outside of in movies), you won t believe how this child actor looks today , etc.

Solving the problem The above really, really pissed me off, so I went to search how to block ad network . To my surprise, the fix was not that simple, for standard users at least.

Method 1: hosts file The hosts file is reasonable as it is relatively cross-platform (Linux and Windows and Mac, I think), but how the heck do you edit hosts on your phone? And furthermore, it has some significant downsides. First, /etc/hosts lists individual hosts, so for an entire ad network, the example I had had two screens of host names. This is really unmaintainable, since rotating host names, or having a gazillion of them is trivial. Second, it cannot return negative answers. I.e. you have to give each of those hosts a valid IPv4/IPv6, and have something either reply with 404 or another 4xx response, or not listen on port 80/443. Too annoying. And finally, it s a client-side solution, so one would have to replicate it across all clients in a home, and keep it in sync.

Method 2: ad-blockers I dislike ad-blockers on principle, since they need wide permissions on all pages, but it is a recommended solution. However, to my surprise, one finds threads saying ad-blocker foo has whitelisted ad network bar, at which point you re WTF? Why do I use an ad-blocker if they get paid by the lowest of the ad networks to show the ads? And again, it s a client-side solution, and one would have to deploy it across N clients, and keep them in sync, etc.

Method 3: HTTP proxy blocking To my surprise, I didn t find this mentioned in a quick internet search. Well, HTTP proxies have long gone the way of the dodo due to HTTPs everywhere , and while one can still use them even with HTTPS, it s not that convenient:
  • you need to tunnel all traffic through them, which might result in bottlenecks (especially for media playing/maybe video-conference/etc.).
  • or even worse, there might be protocol issues/incompatibilities due to 100% tunneling.
  • running a proxy opens up some potential security issues on the internal network, so you need to harden the proxy as well, and maintain it.
  • you need to configure all clients to know about the proxy (via DHCP or manually), which might or might not work well, since it s client-dependent.
  • you can only block at CONNECT level (host name), and you have to build up regexes for the host name.
On the good side, the actual blocking configuration is centralised, and the only distributed configuration is pointing the clients through the proxy. While I used to run a proxy back in HTTP times, the gains were significant back them (media elements caching, downloads caching, all with a slow pipe, etc.), but today is not worth it, so I ve stopped and won t bring a proxy back just for this.

Method 4: DNS resolver filtering After thinking through all the options, I thought - hey, a caching/recursive DNS resolver is what most people with a local network run, right? How difficult is to block at resolver level? and oh my, it is so trivial, for some resolvers at least. And yes, I didn t know about this a week ago

Response Policy Zones Now, of course, there is a standard for this, called Response Policy Zone, and which is supported across multiple resolvers. There are many tutorials on how to use RPZs to configure things, some of them quite detailed - e.g. this one, or a simple/more straightforward one here. The upstream BIND documentation also explains things quite well here, so you can go that route as well. It looks a bit hairy for me thought, but it works, and since it is a standard, it can be more easily deployed. There are many discussions on the internet about how to configure RPZs, how to not even resolve the names (if you re going to return something explicitly/statically), etc. so there are docs, but again it seems a bit overdone.

Resolver hooks There s another way too, if your resolver allows scripting. For example, the PowerDNS resolver allow Lua scripting, and has a relatively simple API at least, to me it looks way, way simpler than the RPZ equivalent. After 20 minutes of reading the docs, I ended up with this, IMO trivial, solution (in a file named e.g. rules.lua):
ads = newDS()
ads:add( '', '', '' )

function preresolve(dq)
  if ads:check(dq.qname) then
    dq.rcode = pdns.NXDOMAIN
    return true;
  return false;
and that s it. Well, enable it/load the file in the configuration, but nothing else. Syntax is pretty straightforward, matching by suffix here, and if you need more complex stuff, you can of course do it; it s just Lua and a simple API. I don t see any immediate equivalent in Bind, so there s that, but if you can use PowerDNS, then the above solution seems simple for simple cases, and could be extended if needed (not sure in which cases). The only other thing one needs to do is to serve the local/custom resolver to all clients, whether desktop or mobile, and that s it. DNS server is bread-and-butter in DHCP, so better support than proxy, and once the host name has been (mis)resolved, nothing is involved anymore in the communication path. True, your name server might get higher CPU usage, but for home network, this should not be a problem. Can this filtering method (either RPZ or hooks) be worked around by ad networks? Sure, like anything. But changing the base domain is not fun. DNSSEC might break it (note Bind RPZ can be configure to ignore DNSSEC), but I m more worried about DNS-over-HTTPS, which I thought initially it s done for the user, but now I m not so sure anymore. Not being in control even of your own DNS resolver seems evil , but what do I know.

Combined authoritative + recursive solution This solution was provided by Guillem Jover, who uses unbound, which is a combined authoritative name server and recursive resolver in one, and dnsmasq (which is even more things, I think):
For my LANs I use unbound, and then block this kind of thing in /etc/unbound/unbound.conf.d/block.conf, with stuff like:
 local-zone: refuse
But then for things that are mobile, and might get out of the LAN, such as laptops, I also block with dnsmasq in /etc/dnsmasq.d/block.conf, with stuff like:
I still use ublock-origin to block stuff at the browser level, though, for yet an extra layer of noise suppression. :)
Thanks for the info!

Happy browsing! 10 lines of Lua, and now for sure I m going to get even fatter without the this natural method will melt your belly fat in 7 days information. Or I will just throw away banana peels without knowing what I could do with hem. After a few days, I asked myself but ads are not so bad, why did I and then realised that yes, ads are not so bad anymore. And Slashdot actually loads faster So, happy browsing!

3 October 2017

Dimitri John Ledkov: An interesting bug - network-manager, glibc, dpkg-shlibdeps, systemd, and finally binutils

Not so long ago I went to effectively recompile NetworkManager and fix up minor bug in it. It built fine across all architectures, was considered to be installable etc. And I was expecting it to just migrate across. At the time, glibc was at 2.26 in artful-proposed and NetworkManager was built against it. However release pocket was at glibc 2.24. In Ubuntu we have a ProposedMigration process in place which ensures that newly built packages do not regress in the number of architectures built for; installable on; and do not regress themselves or any reverse dependencies at runtime.

Thus before my build of NetworkManager was considered for migration, it was tested in the release pocket against packages in the release pocket. Specifically, since package metadata only requires glibc 2.17 NetworkManager was tested against glibc currently in the release pocket, which should just work fine....
autopkgtest [21:47:38]: test nm: [-----------------------
test_auto_ip4 (__main__.ColdplugEthernet)
ethernet: auto-connection, IPv4 ... FAIL ----- NetworkManager.log -----
NetworkManager: /lib/x86_64-linux-gnu/ version GLIBC_2.25' not found (required by NetworkManager)
At first I only saw failing tests, which I thought is transient failure. Thus they were retried a few times. Then I looked at the autopkgtest log and saw above error messages. Perplexed, I have started a lxd container with ubuntu artful, enabled proposed and installed just network-manager from artful-proposed and indeed a simple NetworkManager --help failed with above error from linker.

I am too young to know what dependency-hell means, since ever since I used Linux (Ubuntu 7.04) all glibc symbols were versioned, and dpkg-shlibdeps would generate correct minimum dependencies for a package. Alas in this case readelf confirmed that indeed /usr/sbin/NetworkManager requires 2.25 and dpkg depends is >= 2.17.

Further reading readelf output I checked that all of the glibc symbols used are 2.17 or lower, and only the "Version needs section '.gnu.version_r'" referenced GLIBC_2.25 symbol. Inspecting dpkg-shlibdeps code I noticed that it does not parse that section and only searches through the dynamic symbols used to establish the minimum required version.

Things started to smell fishy. On one hand, I trust dpkg-shlibdeps to generate the right dependencies. On the other hand I also trust linker to not tell lies either. Hence I opened a Debian BTS bug report about this issue.

At this point, I really wanted to figure out where the reference to 2.25 comes from. Clearly it was not from any private symbols as then the reference would be on 2.26. Checking glibc abi lists I found there were only a handful of symbols marked as 2.25
$ grep 2.25 ./sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
GLIBC_2.25 GLIBC_2.25 A
GLIBC_2.25 __explicit_bzero_chk F
GLIBC_2.25 explicit_bzero F
GLIBC_2.25 getentropy F
GLIBC_2.25 getrandom F
GLIBC_2.25 strfromd F
GLIBC_2.25 strfromf F
GLIBC_2.25 strfroml F
Blindly grepping for these in network-manager source tree I found following:
$ grep explicit_bzero -r src/ explicit_bzero],
src/systemd/src/basic/string-util.h:void explicit_bzero(void *p, size_t l);
src/systemd/src/basic/string-util.c:void explicit_bzero(void *p, size_t l)
src/systemd/src/basic/string-util.c: explicit_bzero(x, strlen(x));
First of all it seems like network-manager includes a partial embedded copy of systemd. Secondly that code is compiled into a temporary library and has autconf detection logic to use explicit_bzero. It also has an embedded implementation of explicit_bzero when it is not available in libc, however it does not have FORTIFY_SOURCES implementation of said function (__explicit_bzero_chk) as was later pointed out to me. And whilst this function is compiled into an intermediary noinst library, no functions that use explicit_bzero are used in the end by NetworkManger binary. To proof this, I've dropped all code that uses explicit_bzero, rebuild the package against glibc 2.26, and voila it only had Version reference on glibc 2.17 as expected from the end-result usage of shared symbols.

At this point toolchain bug was a suspect. It seems like whilst explicit_bzero shared symbol got optimised out, the version reference on 2.25 persisted to the linked binaries. At this point in the archive a snapshot version of binutils was in use. And in fact forcefully downgrading bintuils resulted in correct compilation / versions table referencing only glibc 2.17.

Mathias then took over a tarball of object files and filed upstream bug report against bintuils: "[2.29 Regression] ld.bfd keeps a version reference in .gnu.version_r for symbols which are optimized out". The discussion in that bug report is a bit beyond me as to me binutils is black magic. All I understood there was "we moved sweep and pass to another place due to some bugs", doing that introduced this bug, thus do multiple sweep and passes to make sure we fix old bugs and don't regress this either. Or something like that. Comments / Better description of the bintuils fix are welcomed.

Binutils got fixed by upstream developers, cherry-picked into debian, and ubuntu, network-manager got rebuild and everything is wonderful now. However, it does look like unused / deadend code paths tripped up optimisations in the toolchain which managed to slip by distribution package dependency generation and needless require a higher up version of glibc. I guess the lesson here is do not embed/compile unused code. Also I'm not sure why network-manager uses networkd internals like this, and maybe systemd should expose more APIs or serialise more state into /run, as most other things query things over dbus, private socket, or by establishing watches on /run/systemd/netif. I'll look into that another day.

Thanks a lot to Guillem Jover, Matthias Klose, Alan Modra, H.J. Lu, and others for getting involved. I would not be able to raise, debug, or fix this issue all by myself.

30 September 2017

Chris Lamb: Free software activities in September 2017

Here is my monthly update covering what I have been doing in the free software world in September 2017 (previous month):
Reproducible builds

Whilst anyone can inspect the source code of free software for malicious flaws, most software is distributed pre-compiled to end users. The motivation behind the Reproducible Builds effort is to allow verification that no flaws have been introduced either maliciously or accidentally during this compilation process by promising identical results are always generated from a given source, thus allowing multiple third-parties to come to a consensus on whether a build was compromised. I have generously been awarded a grant from the Core Infrastructure Initiative to fund my work in this area. This month I:
  • Published a short blog post about how to determine which packages on your system are reproducible. [...]
  • Submitted a pull request for Numpy to make the generated files reproducible. [...]
  • Provided a patch to GTK upstream to ensure the immodules.cache files are reproducible. [...]
  • Within Debian:
    • Updated, moving it to HTTPS, adding cachebusting as well as keeping the number up-to-date.
    • Submitted the following patches to fix reproducibility-related toolchain issues:
      • gdk-pixbuf: Make the output of gdk-pixbuf-query-loaders reproducible. (#875704)
      • texlive-bin: Make PDF IDs reproducible. (#874102)
    • Submitted a patch to fix a reproducibility issue in doit.
  • Categorised a large number of packages and issues in the Reproducible Builds "notes" repository.
  • Chaired our monthly IRC meeting. [...]
  • Worked on publishing our weekly reports. (#123, #124, #125, #126 & #127)

I also made the following changes to our tooling:

reproducible-check is our script to determine which packages actually installed on your system are reproducible or not.

  • Handle multi-architecture systems correctly. (#875887)
  • Use the "restricted" data file to mask transient issues. (#875861)
  • Expire the cache file after one day and base the local cache filename on the remote name. [...] [...]
I also blogged about this utility. [...]

diffoscope is our in-depth and content-aware diff utility that can locate and diagnose reproducibility issues.

  • Filed an issue attempting to identify the causes behind an increased number of timeouts visible in our CI infrastructure, including running a number of benchmarks of recent versions. (#875324)
  • New features:
    • Add "binwalking" support to analyse concatenated CPIO archives such as initramfs images. (#820631).
    • Print a message if we are reading data from standard input. [...]
  • Bug fixes:
    • Loosen matching of file(1)'s output to ensure we correctly also match TTF files under file version 5.32. [...]
    • Correct references to path_apparent_size in comparators.utils.file and self.buf in diffoscope.diff. [...] [...]
  • Testing:
    • Make failing some critical flake8 tests result in a failed build. [...]
    • Check we identify all CPIO fixtures. [...]
  • Misc:
    • No need for try-assert-except block in [...]
    • Compare types with identity not equality. [...] [...]
    • Use's lazy argument interpolation. [...]
    • Remove unused imports. [...]
    • Numerous PEP8, flake8, whitespace, other cosmetic tidy-ups.


strip-nondeterminism is our tool to remove specific non-deterministic results from a completed build.

  • Log which handler processed a file. (#876140). [...]


disorderfs is our FUSE-based filesystem that deliberately introduces non-determinism into directory system calls in order to flush out reproducibility issues.

Debian My activities as the current Debian Project Leader are covered in my monthly "Bits from the DPL" email to the debian-devel-announce mailing list.
Lintian I made a large number of changes to Lintian, the static analysis tool for Debian packages. It reports on various errors, omissions and general quality-assurance issues to maintainers: I also blogged specifically about the Lintian 2.5.54 release.

Patches contributed
  • debconf: Please add a context manager to (#877096)
  • Add pronouns to ALL_STATUS_DESC. (#875128)
  • user-setup: Please drop set_special_users hack added for "the convenience of heavy testers". (#875909)
  • postgresql-common: Please update README.Debian for PostgreSQL 10. (#876438)
  • django-sitetree: Should not mask test failures. (#877321)
  • charmtimetracker:
    • Missing binary dependency on libqt5sql5-sqlite. (#873918)
    • Please drop "Cross-Platform" from package description. (#873917)
I also submitted 5 patches for packages with incorrect calls to find(1) in debian/rules against hamster-applet, libkml, pyferret, python-gssapi & roundcube.

Debian LTS

This month I have been paid to work 15 hours on Debian Long Term Support (LTS). In that time I did the following:
  • "Frontdesk" duties, triaging CVEs, etc.
  • Documented an example usage of autopkgtests to test security changes.
  • Issued DLA 1084-1 and DLA 1085-1 for libidn and libidn2-0 to fix an integer overflow vulnerabilities in Punycode handling.
  • Issued DLA 1091-1 for unrar-free to prevent a directory traversal vulnerability from a specially-crafted .rar archive. This update introduces an regression test.
  • Issued DLA 1092-1 for libarchive to prevent malicious .xar archives causing a denial of service via a heap-based buffer over-read.
  • Issued DLA 1096-1 for wordpress-shibboleth, correcting an cross-site scripting vulnerability in the Shibboleth identity provider module.

  • python-django:
    • 1.11.5-1 New upstream security release. (#874415)
    • 1.11.5-2 Apply upstream patch to fix QuerySet.defer() with "super" and "subclass" fields. (#876816)
    • 2.0~alpha1-2 New upstream alpha release of Django 2.0, dropping support for Python 2.x.
  • redis:
    • 4.0.2-1 New upstream release.
    • 4.0.2-2 Update 0004-redis-check-rdb autopkgtest test to ensure that the redis.rdb file exists before testing against it.
    • 4.0.2-2~bpo9+1 Upload to stretch-backports.
  • aptfs (0.11.0-1) New upstream release, moving away from using /var/lib/apt/lists internals. Thanks to Julian Andres Klode for a helpful bug report. (#874765)
  • lintian (2.5.53, 2.5.54) New upstream releases. (Documented in more detail above.)
  • bfs (1.1.2-1) New upstream release.
  • docbook-to-man (1:2.0.0-39) Tighten autopkgtests and enable testing via
  • python-daiquiri (1.3.0-1) New upstream release.

I also made the following non-maintainer uploads (NMUs):

Debian bugs filed
  • clipit: Please choose a sensible startup default in "live" mode. (#875903)
  • git-buildpackage: Please add a --reset option to gbp pull. (#875852)
  • bluez: Please default Device "friendly name" to hostname without domain. (#874094)
  • Please explicitly link to packages,tracker (#876746)
  • Requests for packaging:
    • selfspy log everything you do on the computer. (#873955)
    • shoogle use the Google API from the shell. (#873916)

FTP Team

As a Debian FTP assistant I ACCEPTed 86 packages: bgw-replstatus, build-essential, caja-admin, caja-rename, calamares, cdiff, cockpit, colorized-logs, comptext, comptty, copyq, django-allauth, django-paintstore, django-q, django-test-without-migrations, docker-runc, emacs-db, emacs-uuid, esxml, fast5, flake8-docstrings, gcc-6-doc, gcc-7-doc, gcc-8, golang-github-go-logfmt-logfmt, golang-github-google-go-cmp, golang-github-nightlyone-lockfile, golang-github-oklog-ulid, golang-pault-go-macchanger, h2o, inhomog, ip4r, ldc, libayatana-appindicator, libbson-perl, libencoding-fixlatin-perl, libfile-monitor-lite-perl, libhtml-restrict-perl, libmojo-rabbitmq-client-perl, libmoosex-types-laxnum-perl, libparse-mime-perl, libplack-test-agent-perl, libpod-projectdocs-perl, libregexp-pattern-license-perl, libstring-trim-perl, libtext-simpletable-autowidth-perl, libvirt, linux, mac-fdisk, myspell-sq, node-coveralls, node-module-deps, nov-el, owncloud-client, pantomime-clojure, pg-dirtyread, pgfincore, pgpool2, pgsql-asn1oid, phpliteadmin, powerlevel9k, pyjokes, python-evdev, python-oslo.db, python-pygal, python-wsaccel, python3.7, r-cran-bindrcpp, r-cran-dotcall64, r-cran-glue, r-cran-gtable, r-cran-pkgconfig, r-cran-rlang, r-cran-spatstat.utils, resolvconf-admin, retro-gtk, ring-ssl-clojure, robot-detection, rpy2-2.8, ruby-hocon, sass-stylesheets-compass, selinux-dbus, selinux-python, statsmodels, webkit2-sharp & weston. I additionally filed 4 RC bugs against packages that had incomplete debian/copyright files against: comptext, comptext, ldc & python-oslo.concurrency.

25 September 2017

Chris Lamb: Lintian: We are all Perl developers now

Lintian is a static analysis tool for Debian packages, reporting on various errors, omissions and general quality-assurance issues to maintainers. I've previously written about my exploits with Lintian as well as authoring a short tutorial on how to write your own Lintian check. Anyway, I recently uploaded version 2.5.53 about two months since previous release. The biggest changes you may notice are supporting the latest version of the Debian Policy as well the addition of checks to encourage the migration to Python 3. Thanks to all who contributed patches, code review and bug reports to this release. The full changelog is as follows:
lintian (2.5.53) unstable; urgency=medium
  The "we are all Perl developers now" release.
  * Summary of tag changes:
    + Added:
      - alternatively-build-depends-on-python-sphinx-and-python3-sphinx
      - build-depends-on-python-sphinx-only
      - dependency-on-python-version-marked-for-end-of-life
      - maintainer-script-interpreter
      - missing-call-to-dpkg-maintscript-helper
      - node-package-install-in-nodejs-rootdir
      - override-file-in-wrong-package
      - package-installs-java-bytecode
      - python-foo-but-no-python3-foo
      - script-needs-depends-on-sensible-utils
      - script-uses-deprecated-nodejs-location
      - transitional-package-should-be-oldlibs-optional
      - unnecessary-testsuite-autopkgtest-header
      - vcs-browser-links-to-empty-view
    + Removed:
      - debug-package-should-be-priority-extra
      - missing-classpath
      - transitional-package-should-be-oldlibs-extra
  * checks/
    + [CL] Fix an apache2-unparsable-dependency false positive by allowing
      periods (".") in dependency names.  (Closes: #873701)
  * checks/
    + [CL] Apply patches from Guillem Jover & Boud Roukema to improve the
      description of the binary-file-built-without-LFS-support tag.
      (Closes: #874078)
  * checks/changes. pm,desc :
    + [CL] Ignore DFSG-repacked packages when checking for upstream
      source tarball signatures as they will never match by definition.
      (Closes: #871957)
    + [CL] Downgrade severity of orig-tarball-missing-upstream-signature
      from "E:" to "W:" as many common tools do not make including the
      signatures easy enough right now.  (Closes: #870722, #870069)
    + [CL] Expand the explanation of the
      orig-tarball-missing-upstream-signature tag to include the location
      of where dpkg-source will look. Thanks to Theodore Ts'o for the
  * checks/
    + [CL] Address a number of issues in copyright-year-in-future:
      - Prevent false positives in port numbers, email addresses, ISO
        standard numbers and matching specific and general street
        addresses.  (Closes: #869788)
      - Match all violating years in a line, not just the first (eg.
      - Ignore meta copyright statements such as "Original Author". Thanks
        to Thorsten Alteholz for the bug report.  (Closes: #873323)
      - Expand testsuite.
  * checks/cruft. pm,desc :
    + [CL] Downgrade severity of file-contains-fixme-placeholder
      tag from "important" (ie. "E:") to "wishlist" (ie. "I:").
      Thanks to Gregor Herrmann for the suggestion.
    + [CL] Apply patch from Alex Muntada (alexm) to use "substr" instead
      of "substring" in mentions-deprecated-usr-lib-perl5-directory's
      description.  (Closes: #871767)
    + [CL] Don't check copyright_hints file for FIXME placeholders.
      (Closes: #872843)
    + [CL] Don't match quoted "FIXME" variants as they are almost always
      deliberate. Thanks to Adrian Bunk for the report.  (Closes: #870199)
    + [CL] Avoid false positives in missing source checks for "CSS Browser
      Selector".  (Closes: #874381)
  * checks/
    + [CL] Prevent a false positive of
      missing-build-dependency-for-dh_-command that can be exposed by
      following the advice for the recently added
      useless-autoreconf-build-depends tag.  (Closes: #869541)
  * checks/debian-readme. pm,desc :
    + [CL] Ensure readme-debian-contains-debmake-template also checks
      for templates "Automatically generated by debmake".
  * checks/description. desc,pm :
    + [CL] Clarify explanation of description-starts-with-leading-spaces
      tag. Thanks to Taylor Kline  for the report
      and patch.  (Closes: #849622)
    + [NT] Skip capitalization-error-in-description-synopsis for
      auto-generated packages (such as dbgsym packages).
  * checks/fields. desc,pm :
    + [CL] Ensure that python3-foo packages have "Section: python", not
      just python2-foo.  (Closes: #870272)
    + [RG] Do no longer require debug packages to be priority extra.
    + [BR] Use Lintian::Data for name/section mapping
    + [CL] Check for packages including "?rev=0&sc=0" in Vcs-Browser.
      (Closes: #681713)
    + [NT] Transitional packages should now be "oldlibs/optional" rather
      than "oldlibs/extra".  The related tag has been renamed accordingly.
  * checks/
    + [NT] Skip the check on auto-generated binary packages (such as
      dbgsym packages).
  * checks/files. pm,desc :
    + [BR] Avoid privacy-breach-generic false positives for legal.xml.
    + [BR] Detect install of node package under /usr/lib/nodejs/[^/]*$
    + [CL] Check for packages shipping compiled Java class files. Thanks
      Carn  Draug .  (Closes: #873211)
    + [BR] Privacy breach is no longer experimental.
  * checks/init.d.desc:
    + [RG] Do not recommend a versioned dependency on lsb-base in
      init.d-script-needs-depends-on-lsb-base.  (Closes: #847144)
  * checks/
    + [CL] Additionally consider .cljc files as code to avoid false-
      positive codeless-jar warnings.  (Closes: #870649)
    + [CL] Drop problematic missing-classpath check.  (Closes: #857123)
  * checks/menu-format.desc:
    + [CL] Prevent false positives in desktop-entry-lacks-keywords-entry
      for "Link" and "Directory" .desktop files.  (Closes: #873702)
  * checks/python. pm,desc :
    + [CL] Split out Python checks from "scripts" check to a new, source
      check of type "source".
    + [CL] Check for python-foo without corresponding python3-foo packages
      to assist in Python 2.x deprecation.  (Closes: #870681)
    + [CL] Check for packages that Build-Depend on python-sphinx only.
      (Closes: #870730)
    + [CL] Check for packages that alternatively Build-Depend on the
      Python 2 and Python 3 versions of Sphinx.  (Closes: #870758)
    + [CL] Check for binary packages that depend on Python 2.x.
      (Closes: #870822)
  * checks/
    + [CL] Correct false positives in
      unconditional-use-of-dpkg-statoverride by detecting "if !" as a
      valid shell prefix.  (Closes: #869587)
    + [CL] Check for missing calls to dpkg-maintscript-helper(1) in
      maintainer scripts.  (Closes: #872042)
    + [CL] Check for packages using sensible-utils without declaring a
      dependency after its split from debianutils.  (Closes: #872611)
    + [CL] Warn about scripts using "nodejs" as an interpreter now that
      nodejs provides /usr/bin/node.  (Closes: #873096)
    + [BR] Add a statistic tag giving interpreter.
  * checks/testsuite. desc,pm :
    + [CL] Remove recommendations to add a "Testsuite: autopkgtest" field
      to debian/control as it is added when needed by dpkg-source(1)
      since dpkg 1.17.1.  (Closes: #865531)
    + [CL] Warn if we see an unnecessary "Testsuite: autopkgtest" header
      in debian/control.
    + [NT] Recognise "autopkgtest-pkg-go" as a valid test suite.
    + [CL] Recognise "autopkgtest-pkg-elpa" as a valid test suite.
      (Closes: #873458)
    + [CL] Recognise "autopkgtest-pkg-octave" as a valid test suite.
      (Closes: #875985)
    + [CL] Update the description of unknown-testsuite to reflect that
      "autopkgtest" is not the only valid value; the referenced URL
      is out-of-date (filed as #876008).  (Closes: #876003)
  * data/binaries/embedded-libs:
    + [RG] Detect embedded copies of heimdal, libgxps, libquicktime,
      libsass, libytnef, and taglib.
    + [RG] Use an additional string to detect embedded copies of
      openjpeg2.  (Closes: #762956)
  * data/fields/name_section_mappings:
    + [BR] node- package section is javascript.
    + [CL] Apply patch from Guillem Jover to add more section mappings.
      (Closes: #874121)
  * data/fields/obsolete-packages:
    + [MR] Add dh-systemd.  (Closes: #872076)
  * data/fields/perl-provides:
    + [CL] Refresh perl provides.
  * data/fields/virtual-packages:
    + [CL] Update data file from archive. This fixes a false positive for
      "bacula-director".  (Closes: #835120)
  * data/files/obsolete-paths:
    + [CL] Add note to /etc/bash_completion.d entry regarding stricter
      filename requirements.  (Closes: #814599)
  * data/files/privacy-breaker-websites:
    + [BR] Detect custom donation logos like apache.
    + [BR] Detect generic counter website.
  * data/standards-version/release-dates:
    + [CL] Add 4.0.1 and 4.1.0 as known standards versions.
      (Closes: #875509)
  * debian/control:
    + [CL] Mention Debian Policy v4.1.0 in the description.
    + [CL] Add myself to Uploaders.
    + [CL] Drop unnecessary "Testsuite: autopkgtest"; this is implied from
      debian/tests/control existing.
  * commands/
    + [CL] Add a --list-tags option to print all tags Lintian knows about.
      Thanks to Rajendra Gokhale for the suggestion.  (Closes: #779675)
  * commands/
    + [CL] Apply patch from Maia Everett to avoid British spelling when
      using en_US locale.  (Closes: #868897)
  * lib/Lintian/
    + [CL] Stop emitting  maintainer,uploader -address-causes-mail-loops
      for addresses.  (Closes: #871575)
  * lib/Lintian/Collect/
    + [NT] Introduce an "auto-generated" argument for "is_pkg_class".
  * lib/Lintian/
    + [CL] Modify Lintian::Data's "all" to always return keys in insertion
      order, dropping dependency on libtie-ixhash-perl.
  * helpers/coll/objdump-info-helper:
    + [CL] Apply patch from Steve Langasek to accommodate binutils 2.29
      outputting symbols in a different format on ppc64el.
      (Closes: #869750)
  * t/tests/fields-perl-provides/tags:
    + [CL] Update expected output to match new Perl provides.
  * t/tests/files-privacybreach/*:
    + [CL] Add explicit test for packages including external fonts via
      the Google Font API. Thanks to Ian Jackson for the report.
      (Closes: #873434)
    + [CL] Add explicit test for packages including external fonts via
      the Typekit API via <script/> HTML tags.
  * t/tests/*/desc:
    + [CL] Add missing entries in "Test-For" fields to make
      development/testing workflow less error-prone.
  * private/generate-tag-summary:
    + [CL] git-describe(1) will usually emit 7 hexadecimal digits as the
      abbreviated object name,  However, as this can be user-dependent,
      pass --abbrev=0 to ensure it does not vary between systems.  This
      also means we do not need to strip it ourselves.
  * private/refresh-*:
    + [CL] Use as the default mirror.
    + [CL] Update locations of Contents-<arch> files; they are now
      namespaced by distribution (eg. "main").
 -- Chris Lamb <>  Wed, 20 Sep 2017 09:25:06 +0100

17 September 2017

Russ Allbery: Free software log (July and August 2017)

I've wanted to start making one of these posts for a few months but have struggled to find the time. But it seems like a good idea, particularly since I get more done when I write down what I do, so you all get a rather belated one. This covers July and August; hopefully the September one will come closer to the end of September. Debian August was DebConf, which included a ton of Policy work thanks to Sean Whitton's energy and encouragement. During DebConf, we incorporated work from Hideki Yamane to convert Policy to reStructuredText, which has already made it far easier to maintain. (Thanks also to David Bremner for a lot of proofreading of the result.) We also did a massive bug triage and closed a ton of older bugs on which there had been no forward progress for many years. After DebConf, as expected, we flushed out various bugs in the reStructuredText conversion and build infrastructure. I fixed a variety of build and packaging issues and started doing some more formatting cleanup, including moving some footnotes to make the resulting document more readable. During July and August, partly at DebConf and partly not, I also merged wording fixes for seven bugs and proposed wording (not yet finished) for three more, as well as participated in various Policy discussions. Policy was nearly all of my Debian work over these two months, but I did upload a new version of the webauth package to build with OpenSSL 1.1 and drop transitional packages. Kerberos I still haven't decided my long-term strategy with the Kerberos packages I maintain. My personal use of Kerberos is now fairly marginal, but I still care a lot about the software and can't convince myself to give it up. This month, I started dusting off pam-krb5 in preparation for a new release. There's been an open issue for a while around defer_pwchange support in Heimdal, and I spent some time on that and tracked it down to an upstream bug in Heimdal as well as a few issues in pam-krb5. The pam-krb5 issues are now fixed in Git, but I haven't gotten any response upstream from the Heimdal bug report. I also dusted off three old Heimdal patches and submitted them as upstream merge requests and reported some more deficiencies I found in FAST support. On the pam-krb5 front, I updated the test suite for the current version of Heimdal (which changed some of the prompting) and updated the portability support code, but haven't yet pulled the trigger on a new release. Other Software I merged a couple of pull requests in podlators, one to fix various typos (thanks, Jakub Wilk) and one to change the formatting of man page references and function names to match the current Linux manual page standard (thanks, Guillem Jover). I also documented a bad interaction with line-buffered output in the Term::ANSIColor man page. Neither of these have seen a new release yet.

29 August 2017

Reproducible builds folks: Reproducible Builds: Weekly report #122

Here's what happened in the Reproducible Builds effort between Sunday August 20 and Saturday August 26 2017: Debian development Packages reviewed and fixed, and bugs filed Forwarded upstream: Accepted repoducibility NMUs in Debian: Other issues: Reviews of unreproducible packages 16 package reviews have been added, 38 have been updated and 48 have been removed in this week, adding to our knowledge about identified issues. 2 issue types have been updated: Weekly QA work During our reproducibility testing, FTBFS bugs have been detected and reported by: diffoscope development disorderfs development Version 0.5.2-1 was uploaded to unstable by Ximin Luo. It included contributions from: reprotest development Misc. This week's edition was written in alphabetical order by Bernhard M. Wiedemann, Chris Lamb, Mattia Rizzolo & reviewed by a bunch of Reproducible Builds folks on IRC & the mailing lists.

28 May 2017

Russ Allbery: Debian Policy

Today, about a month later than I had intended due to having three consecutive work weeks that mostly drained me of energy, I finally uploaded Debian Policy to Debian experimental. This went to experimental rather than unstable for two reasons: I expect there to be a few more point-release changes to packaging and formatting uploaded to experimental before uploading to unstable for the start of the buster development cycle. (I've indeed already noticed about six minor bugs, including the missing release date in the upgrading checklist....) Due to the DocBook conversion, and the resources rightly devoted to the stretch release instead, it may be a bit before the new Policy version shows up properly in all the places it's published. As you might expect from it having been more than a year since the previous release, there were a lot of accumulated changes. I posted the full upgrading-checklist entries to debian-devel-announce, or of course you can install the debian-policy package from experimental and review them in /usr/share/doc/debian-policy/upgrading-checklist.txt.gz.

18 May 2017

Michael Prokop: Debugging a mystery: ssh causing strange exit codes?

XKCD comic 1722 Recently we had a WTF moment at a customer of mine which is worth sharing. In an automated deployment procedure we re installing Debian systems and setting up MySQL HA/Scalability. Installation of the first node works fine, but during installation of the second node something weird is going on. Even though the deployment procedure reported that everything went fine: it wasn t fine at all. After bisecting to the relevant command lines where it s going wrong we identified that the failure is happening between two ssh/scp commands, which are invoked inside a chroot through a shell wrapper. The ssh command caused a wrong exit code showing up: instead of bailing out with an error (we re running under set -e ) it returned with exit code 0 and the deployment procedure continued, even though there was a fatal error. Initially we triggered the bug when two ssh/scp command lines close to each other were executed, but I managed to find a minimal example for demonstration purposes:
# cat ssh_wrapper 
chroot << "EOF" / /bin/bash
ssh root@localhost hostname >/dev/null
exit 1
echo "return code = $?"
What we d expect is the following behavior, receive exit code 1 from the last command line in the chroot wrapper:
# ./ssh_wrapper 
return code = 1
But what we actually get is exit code 0:
# ./ssh_wrapper 
return code = 0
Uhm?! So what s going wrong and what s the fix? Let s find out what s causing the problem:
# cat ssh_wrapper 
chroot << "EOF" / /bin/bash
ssh root@localhost command_does_not_exist >/dev/null 2>&1
exit "$?"
echo "return code = $?"
# ./ssh_wrapper 
return code = 127
Ok, so if we invoke it with a binary that does not exist we properly get exit code 127, as expected.
What about switching /bin/bash to /bin/sh (which corresponds to dash here) to make sure it s not a bash bug:
# cat ssh_wrapper 
chroot << "EOF" / /bin/sh
ssh root@localhost hostname >/dev/null
exit 1
echo "return code = $?"
# ./ssh_wrapper 
return code = 1
Oh, but that works as expected!? When looking at this behavior I had the feeling that something is going wrong with file descriptors. So what about wrapping the ssh command line within different tools? No luck with stdbuf -i0 -o0 -e0 ssh root@localhost hostname , nor with script -c ssh root@localhost hostname /dev/null and also not with socat EXEC: ssh root@localhost hostname STDIO . But it works under unbuffer(1) from the expect package:
# cat ssh_wrapper 
chroot << "EOF" / /bin/bash
unbuffer ssh root@localhost hostname >/dev/null
exit 1
echo "return code = $?"
# ./ssh_wrapper 
return code = 1
So my bet on something with the file descriptor handling was right. Going through the ssh manpage, what about using ssh s -n option to prevent reading from standard input (stdin)?
# cat ssh_wrapper
chroot << "EOF" / /bin/bash
ssh -n root@localhost hostname >/dev/null
exit 1
echo "return code = $?"
# ./ssh_wrapper 
return code = 1
Bingo! Quoting ssh(1):
     -n      Redirects stdin from /dev/null (actually, prevents reading from stdin).
             This must be used when ssh is run in the background.  A common trick is
             to use this to run X11 programs on a remote machine.  For example,
             ssh -n emacs & will start an emacs on,
             and the X11 connection will be automatically forwarded over an encrypted
             channel.  The ssh program will be put in the background.  (This does not work
             if ssh needs to ask for a password or passphrase; see also the -f option.)
Let s execute the scripts through strace -ff -s500 ./ssh_wrapper to see what s going in more detail.
In the strace run without ssh s -n option we see that it s cloning stdin (file descriptor 0), getting assigned to file descriptor 4:
dup(0)            = 4
read(4, "exit 1\n", 16384) = 7
while in the strace run with ssh s -n option being present there s no file descriptor duplication but only:
open("/dev/null", O_RDONLY) = 4
This matches ssh.c s ssh_session2_open function (where stdin_null_flag corresponds to ssh s -n option):
        if (stdin_null_flag)                                              
                in = open(_PATH_DEVNULL, O_RDONLY);
                in = dup(STDIN_FILENO);
This behavior can also be simulated if we explicitly read from /dev/null, and this indeed works as well:
# cat ssh_wrapper
chroot << "EOF" / /bin/bash
ssh root@localhost hostname >/dev/null </dev/null
exit 1
echo "return code = $?"
# ./ssh_wrapper 
return code = 1
The underlying problem is that both bash and ssh are consuming from stdin. This can be verified via:
# cat ssh_wrapper
chroot << "EOF" / /bin/bash
echo "Inner: pre"
while read line; do echo "Eat: $line" ; done
echo "Inner: post"
exit 3
echo "Outer: exit code = $?"
# ./ssh_wrapper
Inner: pre
Eat: echo "Inner: post"
Eat: exit 3
Outer: exit code = 0
This behavior applies to bash, ksh, mksh, posh and zsh. Only dash doesn t show this behavior.
To understand the difference between bash and dash executions we can use the following test scripts:
# cat stdin-test-cmp
TEST_SH=bash strace -v -s500 -ff ./stdin-test 2>&1   tee stdin-test-bash.out
TEST_SH=dash strace -v -s500 -ff ./stdin-test 2>&1   tee stdin-test-dash.out
# cat stdin-test
: $ TEST_SH:=dash 
echo "Inner: pre"
while read line; do echo "Eat: $line"; done
echo "Inner: post"
exit 3
echo "Outer: exit code = $?"
When executing ./stdin-test-cmp and comparing the generated files stdin-test-bash.out and stdin-test-dash.out you ll notice that dash consumes all stdin in one single go (a single read(0, ) ), instead of character-by-character as specified by POSIX and implemented by bash, ksh, mksh, posh and zsh. See stdin-test-bash.out on the left side and stdin-test-dash.out on the right side in this screenshot: screenshot of vimdiff on *.out files So when ssh tries to read from stdin there s nothing there anymore. Quoting POSIX s sh section:
When the shell is using standard input and it invokes a command that also uses standard input, the shell shall ensure that the standard input file pointer points directly after the command it has read when the command begins execution. It shall not read ahead in such a manner that any characters intended to be read by the invoked command are consumed by the shell (whether interpreted by the shell or not) or that characters that are not read by the invoked command are not seen by the shell. When the command expecting to read standard input is started asynchronously by an interactive shell, it is unspecified whether characters are read by the command or interpreted by the shell. If the standard input to sh is a FIFO or terminal device and is set to non-blocking reads, then sh shall enable blocking reads on standard input. This shall remain in effect when the command completes.
So while we learned that both bash and ssh are consuming from stdin and this needs to prevented by either using ssh s -n or explicitly specifying stdin, we also noticed that dash s behavior is different from all the other main shells and could be considered a bug (which we reported as #862907). Lessons learned: Thanks to Guillem Jover for review and feedback regarding this blog post.

14 March 2017

Reproducible builds folks: Reproducible Builds: week 98 in Stretch cycle

Here's what happened in the Reproducible Builds effort between Sunday March 5 and Saturday March 11 2017: Upcoming events Reproducible Builds Hackathon Hamburg The Reproducible Builds Hamburg Hackathon 2017, or RB-HH-2017 for short, is a 3 day hacking event taking place in the CCC Hamburg Hackerspace located inside the Frappant, which is collective art space located in a historical monument in Hamburg, Germany. The aim of the hackathon is to spent some days working on Reproducible Builds in every distribution and project. The event is open to anybody interested on working on Reproducible Builds issues in any distro or project, with or without prio experience! Packages filed Chris Lamb: Toolchain development Reviews of unreproducible packages 39 package reviews have been added, 7 have been updated and 9 have been removed in this week, adding to our knowledge about identified issues. 2 issue types have been added: Weekly QA work During our reproducibility testing, FTBFS bugs have been detected and reported by: development reproducible-website development Misc. This week's edition was written by Chris Lamb, Holger Levsen, Vagrant Cascadian & reviewed by a bunch of Reproducible Builds folks on IRC & the mailing lists.

21 February 2017

Reproducible builds folks: Reproducible Builds: week 95 in Stretch cycle

Here's what happened in the Reproducible Builds effort between Sunday February 12 and Saturday February 18 2017: Upcoming Events The Reproducible Build Zoo will be presented by Vagrant Cascadian at the Embedded Linux Conference in Portland, Oregon, February 22nd. Introduction to Reproducible Builds will be presented by Vagrant Cascadian at Scale15x in Pasadena, California, March 5th. Toolchain development and fixes Ximin Luo posted a preliminary spec for BUILD_PATH_PREFIX_MAP, bringing together work and research from previous weeks. Ximin refactored and consolidated much of our existing documentation on both SOURCE_DATE_EPOCH and BUILD_PATH_PREFIX_MAP into one unified page, Standard Environment Variables, with extended discussion on related solutions and how these all fit into people's ideas of what reproducible builds should look like in the long term. The specific pages for each variable still remain, at Timestamps Proposal and Build Path Proposal, only without content that was previously duplicated on both pages. Ximin filed #855282 against devscripts for debsign(1) to support buildinfo files, and wrote an initial series of patches for it with some further additions from Guillem Jover. Packages reviewed and fixed, and bugs filed Chris Lamb: Reviews of unreproducible packages 35 package reviews have been added, 1 have been updated and 17 have been removed in this week, adding to our knowledge about identified issues. 1 issue type has been added: Weekly QA work During our reproducibility testing, the following FTBFS bugs have been detected and reported by: diffoscope development diffoscope 77 was uploaded to unstable by Mattia Rizzolo. It included contributions from: strip-nondeterminism development strip-nondeterminism 0.031-1 was uploaded to unstable by Chris Lamb. It included contributions from: strip-nondeterminism 0.031-1~bpo8+1 was uploaded to jessie-backports by Mattia. Misc. This week's edition was written by Ximin Luo & reviewed by a bunch of Reproducible Builds folks on IRC & the mailing lists.

31 January 2017

Reproducible builds folks: Reproducible Builds: week 92 in Stretch cycle

Here's what happened in the Reproducible Builds effort between Sunday January 22 and Saturday January 28 2017: Media coverage Upcoming Events Reproducible work in other projects John Gilmore wrote an interesting mail about how worked on reproducible builds in the early 1990s. It's eye opening to see how the dealt with basically the very same problems we're dealing with today, how they solved them and then to realize that most of this has been forgotten and bit-rotted in the last 20 years. How will we prevent history repeating itself here? Toolchain development and fixes Christoph Biedl wrote a mail describing an interesting problem in to the way binNMUs are done in Debian. Guillem Jover made a number of changes to dpkg that affect the Reproducible Builds effort within Debian: Packages reviewed and fixed, and bugs filed Chris Lamb: Dhole: Reviews of unreproducible packages 17 package reviews have been added, 4 have been updated and 6 have been removed in this week, adding to our knowledge about identified issues. 2 issue types have been added: 1 issue type has been removed: Weekly QA work During our reproducibility testing, the following FTBFS bugs have been detected and reported by: diffoscope development reprotest development development Misc. This week's edition was written by Chris Lamb and Holger Levsen & reviewed by a bunch of Reproducible Builds folks on IRC & the mailing lists.

24 December 2016

Russ Allbery: rra-c-util 6.2

This is my general collection of utility functions, standard tests, and portability code, mostly for C but also including a fair bit of Perl these days. This release improves probing for GCC and Clang warning flags (thanks to Guillem Jover for a good hint there), adds a new is_file_contents test function to the Perl Test::RRA module for comparing whole files, and adds a new test that scans for non-https URLs in my documentation. It also fixes some issues with the Perl strictness test caused by not requiring a new enough version of Test::Strict. You can get the latest release from the rra-c-util distribution page.

17 November 2016

Reproducible builds folks: Reproducible Builds: week 81 in Stretch cycle

What happened in the Reproducible Builds effort between Sunday November 6 and Saturday November 12 2016: Media coverage Matthew Garrett blogged about Tor, TPMs and service integrity attestation and how reproducible builds are the base for systems integrity. The Linux Foundation announced renewed funding for us as part of the Core Infrastructure Initiative. Thank you! Outreachy updates Maria Glukhova has been accepted into the Outreachy winter internship and will work with us the Debian reproducible builds team. To quote her words
siamezzze: I've been accepted to #outreachy winter internship - going to
work with Debian reproducible builds team. So excited about that! <3
Toolchain development and fixes dpkg: debrebuild: Bugs filed Chris Lamb: Daniel Shahaf: Niko Tyni: Reiner Herrman: Reviews of unreproducible packages 136 package reviews have been added, 5 have been updated and 7 have been removed in this week, adding to our knowledge about identified issues. 3 issue types have been updated: Weekly QA work During of reproducibility testing, some FTBFS bugs have been detected and reported by: diffoscope development A new version of diffoscope 62~bpo8+1 was uploaded to jessie-backports by Mattia Rizzolo. Meanwhile in git, Ximin Luo greatly improved speed by fixing a O(n2) lookup which was causing diffs of large packages such as GCC and glibc to take many more hours than was necessary. When this commit is released, we should hopefully see full diffs for such packages again. Currently we have 197 source packages which - when built - diffoscope fails to analyse. development Debian: website F-Droid was finally added to our list of partner projects. (This was an oversight and they had already been working with us for some time.) Misc. This week's edition was written by Ximin Luo and Holger Levsen and reviewed by a bunch of Reproducible Builds folks on IRC.

9 August 2016

Reproducible builds folks: Reproducible builds: week 67 in Stretch cycle

What happened in the Reproducible Builds effort between Sunday July 31 and Saturday August 6 2016: Toolchain development and fixes Packages fixed and bugs filed The following 24 packages have become reproducible - in our current test setup - due to changes in their build-dependencies: alglib aspcud boomaga fcl flute haskell-hopenpgp indigo italc kst ktexteditor libgroove libjson-rpc-cpp libqes luminance-hdr openscenegraph palabos petri-foo pgagent sisl srm-ifce vera++ visp x42-plugins zbackup The following packages have become reproducible after being fixed: The following newly-uploaded packages appear to be reproducible now, for reasons we were not able to figure out. (Relevant changelogs did not mention reproducible builds.) Some uploads have addressed some reproducibility issues, but not all of them: Patches submitted that have not made their way to the archive yet: Package reviews and QA These are reviews of reproduciblity issues of Debian packages. 276 package reviews have been added, 172 have been updated and 44 have been removed in this week. 7 FTBFS bugs have been reported by Chris Lamb. Reproducibility tools Test infrastructure For testing the impact of allowing variations of the buildpath (which up until now we required to be identical for reproducible rebuilds), Reiner Herrmann contribed a patch which enabled build path variations on testing/i386. This is possible now since dpkg 1.18.10 enables the --fixdebugpath build flag feature by default, which should result in reproducible builds (for C code) even with varying paths. So far we haven't had many results due to disturbances in our build network in the last days, but it seems this would mean roughly between 5-15% additional unreproducible packages - compared to what we see now. We'll keep you updated on the numbers (and problems with compilers and common frameworks) as we find them. lynxis continued work to test LEDE and OpenWrt on two different hosts, to include date variation in the tests. Mattia and Holger worked on the (mass) deployment scripts, so that the - for space reasons - only GIT clone resides in ~jenkins-adm/ and not anymore in Holger's homedir, so that soon Mattia (and possibly others!) will be able to fully maintain this setup, while Holger is doing siesta. Miscellaneous Chris, dkg, h01ger and Ximin attended a Core Infrastricture Initiative summit meeting in New York City, to discuss and promote this Reproducible Builds project. The CII was set up in the wake of the Heartbleed SSL vulnerability to support software projects that are critical to the functioning of the internet. This week's edition was written by Ximin Luo and Holger Levsen and reviewed by a bunch of Reproducible Builds folks on IRC.

10 March 2016

Lunar: Reproducible builds: week 45 in Stretch cycle

What happened in the reproducible builds effort between February 28th and March 5th:

Toolchain fixes
  • Antonio Terceiro uploaded gem2deb/0.27 that forces generated gemspecs to use the date from debian/changelog.
  • Antonio Terceiro uploaded gem2deb/0.28 that forces generated gemspecs to have their contains file lists sorted.
  • Robert Luberda uploaded ispell/3.4.00-5 which make builds of hashes reproducible.
  • C dric Boutillier uploaded ruby-ronn/0.7.3-4 which will make the output locale agnostic. Original patch by Chris Lamb.
  • Markus Koschany uploaded spring/101.0+dfsg-1. Fixed by Alexandre Detiste.
Ximin Luo resubmitted the patch adding the --clamp-mtime option to Tar on Savannah's bug tracker. Lunar rebased our experimental dpkg on top of the current master branch. Changes in the test infrastructure are required before uploading a new version to our experimental repository. Reiner Herrmann rebased our custom texlive-bin against the latest uploaded version.

Packages fixed The following 77 packages have become reproducible due to changes in their build dependencies: asciidoctor, atig, fuel-astute, jekyll, libphone-ui-shr, linkchecker, maven-plugin-testing, node-iscroll, origami-pdf, plexus-digest, pry, python-avro, python-odf, rails, ruby-actionpack-xml-parser, ruby-active-model-serializers, ruby-activerecord-session-store, ruby-api-pagination, ruby-babosa, ruby-carrierwave, ruby-classifier-reborn, ruby-compass, ruby-concurrent, ruby-configurate, ruby-crack, ruby-css-parser, ruby-cucumber-rails, ruby-delorean, ruby-encryptor, ruby-fakeweb, ruby-flexmock, ruby-fog-vsphere, ruby-gemojione, ruby-git, ruby-grack, ruby-htmlentities, ruby-jekyll-feed, ruby-json-schema, ruby-listen, ruby-markerb, ruby-mathml, ruby-mini-magick, ruby-net-telnet, ruby-omniauth-azure-oauth2, ruby-omniauth-saml, ruby-org, ruby-origin, ruby-prawn, ruby-pygments.rb, ruby-raemon, ruby-rails-deprecated-sanitizer, ruby-raindrops, ruby-rbpdf, ruby-rbvmomi, ruby-recaptcha, ruby-ref, ruby-responders, ruby-rjb, ruby-rspec-rails, ruby-rspec, ruby-rufus-scheduler, ruby-sass-rails, ruby-sass, ruby-sentry-raven, ruby-sequel-pg, ruby-sequel, ruby-settingslogic, ruby-shoulda-matchers, ruby-slack-notifier, ruby-symboltable, ruby-timers, ruby-zip, ticgit, tmuxinator, vagrant, wagon, yard. 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:
  • #816209 on elog by Reiner Herrmann: use printf instead of echo which is shell-independent.
  • #816214 on python-pip by Reiner Herrmann: removes timestamp from generated Python scripts.
  • #816230 on rows by Reiner Herrmann: tell grep to always treat the input as text.
  • #816232 on eficas by Reiner Herrmann: use printf instead of echo which is shell-independent.
Florent Daigniere and bancfc reported that linux-grsec was currently built with GRKERNSEC_RANDSTRUCT which will prevent reproducible builds with the current packaging. pbuilder has been updated to the last version to be able to support Build-Depends-Arch and Build-Conflicts-Arch. (Mattia Rizzolo, h01ger) New package sets have been added for Subgraph OS, which is based on Debian Stretch: packages and build dependencies. (h01ger) Two new armhf build nodes have been added (thanks Vagrant Cascadian) and integrated in our Jenkins setup with 8 new armhf builder jobs. (h01ger)

strip-nondeterminism development strip-nondeterminism version 0.016-1 was released on Sunday 28th. It will now normalize the POT-Creation-Date field in GNU Gettext .mo files. (Reiner Herrmann) Several improvements to the packages metadata have also been made. (h01ger, Ben Finney)

Package reviews 185 reviews have been removed, 91 added and 33 updated in the previous week. New issue: fileorder_in_gemspec_files_list. 43 FTBFS bugs were reported by Chris Lamb, Martin Michlmayr, and gregor herrmann.

Misc. After merging the patch from Dhiru Kholia adding support for SOURCE_DATE_EPOCH in rpm, Florian Festi opened a discussion on the rpm-ecosystem mailing list about reproducible builds. On March 4th, Lunar gave an overview of the general reproducible builds effort at the Internet Freedom Festival in Valencia.

5 March 2016

Lunar: Reproducible builds: week 44 in Stretch cycle

What happened in the reproducible builds effort between February 21th and February 27th:

Toolchain fixes Didier Raboud uploaded pyppd/1.0.2-4 which makes PPD generation deterministic. Emmanuel Bourg uploaded plexus-maven-plugin/1.3.8-10 which sorts the components in the components.xml files generated by the plugin. Guillem Jover has implemented stable ordering for members of the control archives in .debs. Chris Lamb submitted another patch to improve reproducibility of files generated by cython.

Packages fixed The following packages have become reproducible due to changes in their build dependencies: dctrl-tools, debian-edu, dvdwizard, dymo-cups-drivers, ekg2, epson-inkjet-printer-escpr, expeyes, fades, foomatic-db, galternatives, gnuradio, gpodder, gutenprint icewm, invesalius, jodconverter-cli latex-mk, libiio, libimobiledevice, libmcrypt, libopendbx, lives, lttnganalyses, m2300w, microdc2, navit, po4a, ptouch-driver, pxljr, tasksel, tilda, vdr-plugin-infosatepg, xaos. The following packages became reproducible after getting fixed: Some uploads fixed some reproducibility issues, but not all of them: The reproducibly tests for Debian now vary the provider of /bin/sh between bash and dash. (Reiner Herrmann)

diffoscope development diffoscope version 50 was released on February 27th. It adds a new comparator for PostScript files, makes the directory tests pass on slower hardware, and line ordering variations in .deb md5sums files will not be hidden anymore. Version 51 uploaded the next day re-added test data missing from the previous tarball. diffoscope is looking for a new primary maintainer.

Package reviews 87 reviews have been removed, 61 added and 43 updated in the previous week. New issues: captures_shell_variable_in_autofoo_script, varying_ordering_in_data_tar_gz_or_control_tar_gz. 30 new FTBFS have been reported by Chris Lamb, Antonio Terceiro, Aaron M. Ucko, Michael Tautschnig, and Tobias Frost.

Misc. The release team reported on their discussion about the topic of rebuilding all of Stretch to make it self-contained (in respect to reproducibility). Christian Boltz is hoping someone could talk about reproducible builds at the openSUSE conference happening June 22nd-26th in N rnberg, Germany.

8 February 2016

Lunar: Reproducible builds: week 41 in Stretch cycle

What happened in the reproducible builds effort this week:

Toolchain fixes After remarks from Guillem Jover, Lunar updated his patch adding generation of .buildinfo files in dpkg.

Packages fixed The following packages have become reproducible due to changes in their build dependencies: dracut, ent, gdcm, guilt, lazarus, magit, matita, resource-agents, rurple-ng, shadow, shorewall-doc, udiskie. The following packages became reproducible after getting fixed:
  • disque/1.0~rc1-5 by Chris Lamb, noticed by Reiner Herrmann.
  • dlm/4.0.4-2 by Ferenc W gner.
  • drbd-utils/8.9.6-1 by Apollon Oikonomopoulos.
  • java-common/0.54 by by Emmanuel Bourg.
  • libjibx1.2-java/1.2.6-1 by Emmanuel Bourg.
  • libzstd/0.4.7-1 by Kevin Murray.
  • python-releases/1.0.0-1 by Jan Dittberner.
  • redis/2:3.0.7-2 by Chris Lamb, noticed by Reiner Herrmann.
  • tetex-brev/4.22.github.20140417-3 by Petter Reinholdtsen.
Some uploads fixed some reproducibility issues, but not all of them:
  • anarchism/14.0-4 by Holger Levsen.
  • hhvm/3.11.1+dfsg-1 by Faidon Liambotis.
  • netty/1:4.0.34-1 by Emmanuel Bourg.
Patches submitted which have not made their way to the archive yet:
  • #813309 on lapack by Reiner Herrmann: removes the test log and sorts the files packed into the static library locale-independently.
  • #813345 on elastix by akira: suggest to use the $datetime placeholder in Doxygen footer.
  • #813892 on dietlibc by Reiner Herrmann: remove gzip headers, sort md5sums file, and sort object files linked in static libraries.
  • #813912 on git by Reiner Herrmann: remove timestamps from documentation generated with asciidoc, remove gzip headers, and sort md5sums and tclIndex files. For the first time, we've reached more than 20,000 packages with reproducible builds for sid on amd64 with our current test framework. Vagrant Cascadian has set up another test system for armhf. Enabling four more builder jobs to be added to Jenkins. (h01ger)

Package reviews 233 reviews have been removed, 111 added and 86 updated in the previous week. 36 new FTBFS bugs were reported by Chris Lamb and Alastair McKinstry. New issue: timestamps_in_manpages_generated_by_yat2m. The description for the blacklisted_on_jenkins issue has been improved. Some packages are also now tagged with blacklisted_on_jenkins_armhf_only.

Misc. Steven Chamberlain gave an update on the status of FreeBSD and variants after the BSD devroom at FOSDEM 16. He also discussed how jails can be used for easier and faster reproducibility tests. The video for h01ger's talk in the main track of FOSDEM 16 about the reproducible ecosystem is now available.