Search Results: "dpk"

9 July 2024

Simon Josefsson: Towards Idempotent Rebuilds?

After rebuilding all added/modified packages in Trisquel, I have been circling around the elephant in the room: 99% of the binary packages in Trisquel comes from Ubuntu, which to a large extent are built from Debian source packages. Is it possible to rebuild the official binary packages identically? Does anyone make an effort to do so? Does anyone care about going through the differences between the official package and a rebuilt version? Reproducible-build.org s effort to track reproducibility bugs in Debian (and other systems) is amazing. However as far as I know, they do not confirm or deny that their rebuilds match the official packages. In fact, typically their rebuilds do not match the official packages, even when they say the package is reproducible, which had me surprised at first. To understand why that happens, compare the buildinfo file for the official coreutils 9.1-1 from Debian bookworm with the buildinfo file for reproducible-build.org s build and you will see that the SHA256 checksum does not match, but still they declare it as a reproducible package. As far as I can tell of the situation, the purpose of their rebuilds are not to say anything about the official binary build, instead the purpose is to offer a QA service to maintainers by performing two builds of a package and declaring success if both builds match. I have felt that something is lacking, and months have passed and I haven t found any project that address the problem I am interested in. During my earlier work I created a project called debdistreproduce which performs rebuilds of the difference between two distributions in a GitLab pipeline, and display diffoscope output for further analysis. A couple of days ago I had the idea of rewriting it to perform rebuilds of a single distribution. A new project debdistrebuild was born and today I m happy to bless it as version 1.0 and to announces the project! Debdistrebuild has rebuilt the top-50 popcon packages from Debian bullseye, bookworm and trixie, on amd64 and arm64, as well as Ubuntu jammy and noble on amd64, see the summary status page for links. This is intended as a proof of concept, to allow people experiment with the concept of doing GitLab-based package rebuilds and analysis. Compare how Guix has the guix challenge command. Or I should say debdistrebuild has attempted to rebuild those distributions. The number of identically built packages are fairly low, so I didn t want to waste resources building the rest of the archive until I understand if the differences are due to consequences of my build environment (plain apt-get build-dep followed by dpkg-buildpackage in a fresh container), or due to some real difference. Summarizing the results, debdistrebuild is able to rebuild 34% of Debian bullseye on amd64, 36% of bookworm on amd64, 32% of bookworm on arm64. The results for trixie and Ubuntu are disappointing, below 10%. So what causes my rebuilds to be different from the official rebuilds? Some are trivial like the classical problem of varying build paths, resulting in a different NT_GNU_BUILD_ID causing a mismatch. Some are a bit strange, like a subtle difference in one of perl s headers file. Some are due to embedded version numbers from a build dependency. Several of the build logs and diffoscope outputs doesn t make sense, likely due to bugs in my build scripts, especially for Ubuntu which appears to strip translations and do other build variations that I don t do. In general, the classes of reproducibility problems are the expected. Some are assembler differences for GnuPG s gpgv-static, likely triggered by upload of a new version of gcc after the original package was built. There are at least two ways to resolve that problem: either use the same version of build dependencies that were used to produce the original build, or demand that all packages that are affected by a change in another package are rebuilt centrally until there are no more differences. The current design of debdistrebuild uses the latest version of a build dependency that is available in the distribution. We call this a idempotent rebuild . This is usually not how the binary packages were built originally, they are often built against earlier versions of their build dependency. That is the situation for most binary distributions. Instead of using the latest build dependency version, higher reproducability may be achieved by rebuilding using the same version of the build dependencies that were used during the original build. This requires parsing buildinfo files to find the right version of the build dependency to install. We believe doing so will lead to a higher number of reproducibly built packages. However it begs the question: can we rebuild that earlier version of the build dependency? This circles back to really old versions and bootstrappable builds eventually. While rebuilding old versions would be interesting on its own, we believe that is less helpful for trusting the latest version and improving a binary distribution: it is challenging to publish a new version of some old package that would fix a reproducibility bug in another package when used as a build dependency, and then rebuild the later packages with the modified earlier version. Those earlier packages were already published, and are part of history. It may be that ultimately it will no longer be possible to rebuild some package, because proper source code is missing (for packages using build dependencies that were never part of a release); hardware to build a package could be missing; or that the source code is no longer publicly distributable. I argue that getting to 100% idempotent rebuilds is an interesting goal on its own, and to reach it we need to start measure idempotent rebuild status. One could conceivable imagine a way to rebuild modified versions of earlier packages, and then rebuild later packages using the modified earlier packages as build dependencies, for the purpose of achieving higher level of reproducible rebuilds of the last version, and to reach for bootstrappability. However, it may be still be that this is insufficient to achieve idempotent rebuilds of the last versions. Idempotent rebuilds are different from a reproducible build (where we try to reproduce the build using the same inputs), and also to bootstrappable builds (in which all binaries are ultimately built from source code). Consider a cycle where package X influence the content of package Y, which in turn influence the content of package X. These cycles may involve several packages, and it is conceivable that a cycle could be circular and infinite. It may be difficult to identify these chains, and even more difficult to break them up, but this effort help identify where to start looking for them. Rebuilding packages using the same build dependency versions as were used during the original build, or rebuilding packages using a bootsrappable build process, both seem orthogonal to the idempotent rebuild problem. Our notion of rebuildability appears thus to be complementary to reproducible-builds.org s definition and bootstrappable.org s definition. Each to their own devices, and Happy Hacking! Addendum about terminology: With idempotent rebuild I am talking about a rebuild of the entire operating system, applied to itself. Compare how you build the latest version of the GNU C Compiler: it first builds itself using whatever system compiler is available (often an earlier version of gcc) which we call step 1. Then step 2 is to build a copy of itself using the compiler built in step 1. The final step 3 is to build another copy of itself using the compiler from step 2. Debian, Ubuntu etc are at step 1 in this process right now. The output of step 2 and step 3 ought to be bit-by-bit identical, or something is wrong. The comparison between step 2 and 3 is what I refer to with an idempotent rebuild. Of course, most packages aren t a compiler that can compile itself. However entire operating systems such as Trisquel, PureOS, Ubuntu or Debian are (hopefully) a self-contained system that ought to be able to rebuild itself to an identical copy. Or something is amiss. The reproducible build and bootstrappable build projects are about improve the quality of step 1. The property I am interested is the identical rebuild and comparison in step 2 and 3. I feel the word idempotent describes the property I m interested in well, but I realize there may be better ways to describe this. Ideas welcome!

10 May 2024

Reproducible Builds: Reproducible Builds in April 2024

Welcome to the April 2024 report from the Reproducible Builds project! In our reports, we attempt to outline what we have been up to over the past month, as well as mentioning some of the important things happening more generally in software supply-chain security. As ever, if you are interested in contributing to the project, please visit our Contribute page on our website. Table of contents:
  1. New backseat-signed tool to validate distributions source inputs
  2. NixOS is not reproducible
  3. Certificate vulnerabilities in F-Droid s fdroidserver
  4. Website updates
  5. Reproducible Builds and Insights from an Independent Verifier for Arch Linux
  6. libntlm now releasing minimal source-only tarballs
  7. Distribution work
  8. Mailing list news
  9. diffoscope
  10. Upstream patches
  11. reprotest
  12. Reproducibility testing framework

New backseat-signed tool to validate distributions source inputs kpcyrd announced a new tool called backseat-signed, after:
I figured out a somewhat straight-forward way to check if a given git archive output is cryptographically claimed to be the source input of a given binary package in either Arch Linux or Debian (or both).
Elaborating more in their announcement post, kpcyrd writes:
I believe this to be the reproducible source tarball thing some people have been asking about. As explained in the README, I believe reproducing autotools-generated tarballs isn t worth everybody s time and instead a distribution that claims to build from source should operate on VCS snapshots instead of tarballs with 25k lines of pre-generated shell-script.
Indeed, many distributions packages already build from VCS snapshots, and this trend is likely to accelerate in response to the xz incident. The announcement led to a lengthy discussion on our mailing list, as well as shorter followup thread from kpcyrd about bootstrapping Autotools projects.

NixOS is not reproducible Morten Linderud posted an post on his blog this month, provocatively titled, NixOS is not reproducible . Although quickly admitting that his title is indeed clickbait , Morten goes on to clarify the precise guarantees and promises that NixOS provides its users. Later in the most, Morten mentions that he was motivated to write the post because:
I have heavily invested my free-time on this topic since 2017, and met some of the accomplishments we have had with Doesn t NixOS solve this? for just as long and I thought it would be of peoples interest to clarify[.]

Certificate vulnerabilities in F-Droid s fdroidserver In early April, Fay Stegerman announced a certificate pinning bypass vulnerability and Proof of Concept (PoC) in the F-Droid fdroidserver tools for managing builds, indexes, updates, and deployments for F-Droid repositories to the oss-security mailing list.
We observed that embedding a v1 (JAR) signature file in an APK with minSdk >= 24 will be ignored by Android/apksigner, which only checks v2/v3 in that case. However, since fdroidserver checks v1 first, regardless of minSdk, and does not verify the signature, it will accept a fake certificate and see an incorrect certificate fingerprint. [ ] We also realised that the above mentioned discrepancy between apksigner and androguard (which fdroidserver uses to extract the v2/v3 certificates) can be abused here as well. [ ]
Later on in the month, Fay followed up with a second post detailing a third vulnerability and a script that could be used to scan for potentially affected .apk files and mentioned that, whilst upstream had acknowledged the vulnerability, they had not yet applied any ameliorating fixes.

Website updates There were a number of improvements made to our website this month, including Chris Lamb updating the archive page to recommend -X and unzipping with TZ=UTC [ ] and adding Maven, Gradle, JDK and Groovy examples to the SOURCE_DATE_EPOCH page [ ]. In addition Jan Zerebecki added a new /contribute/opensuse/ page [ ] and Sertonix fixed the automatic RSS feed detection [ ][ ].

Reproducible Builds and Insights from an Independent Verifier for Arch Linux Joshua Drexel, Esther H nggi and Iy n M ndez Veiga of the School of Computer Science and Information Technology, Hochschule Luzern (HSLU) in Switzerland published a paper this month entitled Reproducible Builds and Insights from an Independent Verifier for Arch Linux. The paper establishes the context as follows:
Supply chain attacks have emerged as a prominent cybersecurity threat in recent years. Reproducible and bootstrappable builds have the potential to reduce such attacks significantly. In combination with independent, exhaustive and periodic source code audits, these measures can effectively eradicate compromises in the building process. In this paper we introduce both concepts, we analyze the achievements over the last ten years and explain the remaining challenges.
What is more, the paper aims to:
contribute to the reproducible builds effort by setting up a rebuilder and verifier instance to test the reproducibility of Arch Linux packages. Using the results from this instance, we uncover an unnoticed and security-relevant packaging issue affecting 16 packages related to Certbot [ ].
A PDF of the paper is available.

libntlm now releasing minimal source-only tarballs Simon Josefsson wrote on his blog this month that, going forward, the libntlm project will now be releasing what they call minimal source-only tarballs :
The XZUtils incident illustrate that tarballs with files that are not included in the git archive offer an opportunity to disguise malicious backdoors. [The] risk of hiding malware is not the only motivation to publish signed minimal source-only tarballs. With pre-generated content in tarballs, there is a risk that GNU/Linux distributions [ship] generated files coming from the tarball into the binary *.deb or *.rpm package file. Typically the person packaging the upstream project never realized that some installed artifacts was not re-built[.]
Simon s post goes into further details how this was achieved, and describes some potential caveats and counters some expected responses as well. A shorter version can be found in the announcement for the 1.8 release of libntlm.

Distribution work In Debian this month, Helmut Grohne filed a bug suggesting the removal of dh-buildinfo, a tool to generate and distribute .buildinfo-like files within binary packages. Note that this is distinct from the .buildinfo generation performed by dpkg-genbuildinfo. By contrast, the entirely optional dh-buildinfo generated a debian/buildinfo file that would be shipped within binary packages as /usr/share/doc/package/buildinfo_$arch.gz. Adrian Bunk recently asked about including source hashes in Debian s .buildinfo files, which prompted Guillem Jover to refresh some old patches to dpkg to make this possible, which revealed some quirks Vagrant Cascadian discovered when testing. In addition, 21 reviews of Debian packages were added, 22 were updated and 16 were removed this month adding to our knowledge about identified issues. A number issue types have been added, such as new random_temporary_filenames_embedded_by_mesonpy and timestamps_added_by_librime toolchain issues. In openSUSE, it was announced that their Factory distribution enabled bit-by-bit reproducible builds for almost all parts of the package. Previously, more parts needed to be ignored when comparing package files, but now only the signature needs to be deleted. In addition, Bernhard M. Wiedemann published theunreproduciblepackage as a proper .rpm package which it allows to better test tools intended to debug reproducibility. Furthermore, it was announced that Bernhard s work on a 100% reproducible openSUSE-based distribution will be funded by NLnet. He also posted another monthly report for his reproducibility work in openSUSE. In GNU Guix, Janneke Nieuwenhuizen submitted a patch set for creating a reproducible source tarball for Guix. That is to say, ensuring that make dist is reproducible when run from Git. [ ] Lastly, in Fedora, a new wiki page was created to propose a change to the distribution. Titled Changes/ReproduciblePackageBuilds , the page summarises itself as a proposal whereby A post-build cleanup is integrated into the RPM build process so that common causes of build irreproducibility in packages are removed, making most of Fedora packages reproducible.

Mailing list news On our mailing list this month:
  • Continuing a thread started in March 2024 about the Arch Linux minimal container now being 100% reproducible, John Gilmore followed up with a post about the practical and philosophical distinctions of local vs. remote storage of the various artifacts needed to build packages.
  • Chris Lamb asked the list which conferences readers are attending these days: After peak Covid and other industry-wide changes, conferences are no longer the must attend events they previously were especially in the area of software supply-chain security. In rough, practical terms, it seems harder to justify conference travel today than it did in mid-2019. The thread generated a number of responses which would be of interest to anyone planning travel in Q3 and Q4 of 2024.
  • James Addison wrote to the list about a quirk in Git related to its core.autocrlf functionality, thus helpfully passing on a slightly off-topic and perhaps not of direct relevance to anyone on the list today note that might still be the kind of issue that is useful to be aware of if-and-when puzzling over unexpected git content / checksum issues (situations that I do expect people on this list encounter from time-to-time) .

diffoscope diffoscope is our in-depth and content-aware diff utility that can locate and diagnose reproducibility issues. This month, Chris Lamb made a number of changes such as uploading versions 263, 264 and 265 to Debian and made the following additional changes:
  • Don t crash on invalid .zip files, even if we encounter their badness halfway through the file and not at the time of their initial opening. [ ]
  • Prevent odt2txt tests from always being skipped due to an (impossibly) new version requirement. [ ]
  • Avoid parens-in-parens in test skipping messages. [ ]
  • Ensure that tests with >=-style version constraints actually print the tool name. [ ]
In addition, Fay Stegerman fixed a crash when there are (invalid) duplicate entries in .zip which was originally reported in Debian bug #1068705). [ ] Fay also added a user-visible note to a diff when there are duplicate entries in ZIP files [ ]. Lastly, Vagrant Cascadian added an external tool pointer for the zipdetails tool under GNU Guix [ ] and proposed updates to diffoscope in Guix as well [ ] which were merged as [264] [265], fixed a regression in test coverage and increased verbosity of the test suite[ ].

Upstream patches The Reproducible Builds project detects, dissects and attempts to fix as many currently-unreproducible packages as possible. We endeavour to send all of our patches upstream where appropriate. This month, we wrote a large number of such patches, including:

reprotest reprotest is our tool for building the same source code twice in different environments and then checking the binaries produced by each build for any differences. This month, reprotest version 0.7.27 was uploaded to Debian unstable) by Vagrant Cascadian who made the following additional changes:
  • Enable specific number of CPUs using --vary=num_cpus.cpus=X. [ ]
  • Consistently use 398 days for time variation, rather than choosing randomly each time. [ ]
  • Disable builds of arch:any packages. [ ]
  • Update the description for the build_path.path option in README.rst. [ ]
  • Update escape sequences for compatibility with Python 3.12. (#1068853). [ ]
  • Remove the generic upstream signing-key [ ] and update the packages signing key with the currently active team members [ ].
  • Update the packaging Standards-Version to 4.7.0. [ ]
In addition, Holger Levsen fixed some spelling errors detected by the spellintian tool [ ] and Vagrant Cascadian updated reprotest in GNU Guix to 0.7.27.

Reproducibility testing framework The Reproducible Builds project operates a comprehensive testing framework running primarily at tests.reproducible-builds.org in order to check packages and other artifacts for reproducibility. In April, an enormous number of changes were made by Holger Levsen:
  • Debian-related changes:
    • Adjust for changed internal IP addresses at Codethink. [ ]
    • Automatically cleanup failed diffoscope user services if there are too many failures. [ ][ ]
    • Configure two new nodes at infomanik.cloud. [ ][ ]
    • Schedule Debian experimental even less. [ ][ ]
  • Breakage detection:
    • Exclude currently building packages from breakage detection. [ ]
    • Be more noisy if diffoscope crashes. [ ]
    • Health check: provide clickable URLs in jenkins job log for failed pkg builds due to diffoscope crashes. [ ]
    • Limit graph to about the last 100 days of breakages only. [ ]
    • Fix all found files with bad permissions. [ ]
    • Prepare dealing with diffoscope timeouts. [ ]
    • Detect more cases of failure to debootstrap base system. [ ]
    • Include timestamps of failed job runs. [ ]
  • Documentation updates:
    • Document how to access arm64 nodes at Codethink. [ ]
    • Document how to use infomaniak.cloud. [ ]
    • Drop notes about long stalled LeMaker HiKey960 boards sponsored by HPE and hosted at ETH. [ ]
    • Mention osuosl4 and osuosl5 and explain their usage. [ ]
    • Mention that some packages are built differently. [ ][ ]
    • Improve language in a comment. [ ]
    • Add more notes how to query resource usage from infomaniak.cloud. [ ]
  • Node maintenance:
    • Add ionos4 and ionos14 to THANKS. [ ][ ][ ][ ][ ]
    • Deprecate Squid on ionos1 and ionos10. [ ]
    • Drop obsolete script to powercycle arm64 architecture nodes. [ ]
    • Update system_health_check for new proxy nodes. [ ]
  • Misc changes:
    • Make the update_jdn.sh script more robust. [ ][ ]
    • Update my SSH public key. [ ]
In addition, Mattia Rizzolo added some new host details. [ ]

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:

13 April 2024

Paul Tagliamonte: Domo Arigato, Mr. debugfs

Years ago, at what I think I remember was DebConf 15, I hacked for a while on debhelper to write build-ids to debian binary control files, so that the build-id (more specifically, the ELF note .note.gnu.build-id) wound up in the Debian apt archive metadata. I ve always thought this was super cool, and seeing as how Michael Stapelberg blogged some great pointers around the ecosystem, including the fancy new debuginfod service, and the find-dbgsym-packages helper, which uses these same headers, I don t think I m the only one. At work I ve been using a lot of rust, specifically, async rust using tokio. To try and work on my style, and to dig deeper into the how and why of the decisions made in these frameworks, I ve decided to hack up a project that I ve wanted to do ever since 2015 write a debug filesystem. Let s get to it.

Back to the Future Time to admit something. I really love Plan 9. It s just so good. So many ideas from Plan 9 are just so prescient, and everything just feels right. Not just right like, feels good like, correct. The bit that I ve always liked the most is 9p, the network protocol for serving a filesystem over a network. This leads to all sorts of fun programs, like the Plan 9 ftp client being a 9p server you mount the ftp server and access files like any other files. It s kinda like if fuse were more fully a part of how the operating system worked, but fuse is all running client-side. With 9p there s a single client, and different servers that you can connect to, which may be backed by a hard drive, remote resources over something like SFTP, FTP, HTTP or even purely synthetic. The interesting (maybe sad?) part here is that 9p wound up outliving Plan 9 in terms of adoption 9p is in all sorts of places folks don t usually expect. For instance, the Windows Subsystem for Linux uses the 9p protocol to share files between Windows and Linux. ChromeOS uses it to share files with Crostini, and qemu uses 9p (virtio-p9) to share files between guest and host. If you re noticing a pattern here, you d be right; for some reason 9p is the go-to protocol to exchange files between hypervisor and guest. Why? I have no idea, except maybe due to being designed well, simple to implement, and it s a lot easier to validate the data being shared and validate security boundaries. Simplicity has its value. As a result, there s a lot of lingering 9p support kicking around. Turns out Linux can even handle mounting 9p filesystems out of the box. This means that I can deploy a filesystem to my LAN or my localhost by running a process on top of a computer that needs nothing special, and mount it over the network on an unmodified machine unlike fuse, where you d need client-specific software to run in order to mount the directory. For instance, let s mount a 9p filesystem running on my localhost machine, serving requests on 127.0.0.1:564 (tcp) that goes by the name mountpointname to /mnt.
$ mount -t 9p \
-o trans=tcp,port=564,version=9p2000.u,aname=mountpointname \
127.0.0.1 \
/mnt
Linux will mount away, and attach to the filesystem as the root user, and by default, attach to that mountpoint again for each local user that attempts to use it. Nifty, right? I think so. The server is able to keep track of per-user access and authorization along with the host OS.

WHEREIN I STYX WITH IT Since I wanted to push myself a bit more with rust and tokio specifically, I opted to implement the whole stack myself, without third party libraries on the critical path where I could avoid it. The 9p protocol (sometimes called Styx, the original name for it) is incredibly simple. It s a series of client to server requests, which receive a server to client response. These are, respectively, T messages, which transmit a request to the server, which trigger an R message in response (Reply messages). These messages are TLV payload with a very straight forward structure so straight forward, in fact, that I was able to implement a working server off nothing more than a handful of man pages. Later on after the basics worked, I found a more complete spec page that contains more information about the unix specific variant that I opted to use (9P2000.u rather than 9P2000) due to the level of Linux specific support for the 9P2000.u variant over the 9P2000 protocol.

MR ROBOTO The backend stack over at zoo is rust and tokio running i/o for an HTTP and WebRTC server. I figured I d pick something fairly similar to write my filesystem with, since 9P can be implemented on basically anything with I/O. That means tokio tcp server bits, which construct and use a 9p server, which has an idiomatic Rusty API that partially abstracts the raw R and T messages, but not so much as to cause issues with hiding implementation possibilities. At each abstraction level, there s an escape hatch allowing someone to implement any of the layers if required. I called this framework arigato which can be found over on docs.rs and crates.io.
/// Simplified version of the arigato File trait; this isn't actually
/// the same trait; there's some small cosmetic differences. The
/// actual trait can be found at:
///
/// https://docs.rs/arigato/latest/arigato/server/trait.File.html
trait File  
/// OpenFile is the type returned by this File via an Open call.
 type OpenFile: OpenFile;
/// Return the 9p Qid for this file. A file is the same if the Qid is
 /// the same. A Qid contains information about the mode of the file,
 /// version of the file, and a unique 64 bit identifier.
 fn qid(&self) -> Qid;
/// Construct the 9p Stat struct with metadata about a file.
 async fn stat(&self) -> FileResult<Stat>;
/// Attempt to update the file metadata.
 async fn wstat(&mut self, s: &Stat) -> FileResult<()>;
/// Traverse the filesystem tree.
 async fn walk(&self, path: &[&str]) -> FileResult<(Option<Self>, Vec<Self>)>;
/// Request that a file's reference be removed from the file tree.
 async fn unlink(&mut self) -> FileResult<()>;
/// Create a file at a specific location in the file tree.
 async fn create(
&mut self,
name: &str,
perm: u16,
ty: FileType,
mode: OpenMode,
extension: &str,
) -> FileResult<Self>;
/// Open the File, returning a handle to the open file, which handles
 /// file i/o. This is split into a second type since it is genuinely
 /// unrelated -- and the fact that a file is Open or Closed can be
 /// handled by the  arigato  server for us.
 async fn open(&mut self, mode: OpenMode) -> FileResult<Self::OpenFile>;
 
/// Simplified version of the arigato OpenFile trait; this isn't actually
/// the same trait; there's some small cosmetic differences. The
/// actual trait can be found at:
///
/// https://docs.rs/arigato/latest/arigato/server/trait.OpenFile.html
trait OpenFile  
/// iounit to report for this file. The iounit reported is used for Read
 /// or Write operations to signal, if non-zero, the maximum size that is
 /// guaranteed to be transferred atomically.
 fn iounit(&self) -> u32;
/// Read some number of bytes up to  buf.len()  from the provided
 ///  offset  of the underlying file. The number of bytes read is
 /// returned.
 async fn read_at(
&mut self,
buf: &mut [u8],
offset: u64,
) -> FileResult<u32>;
/// Write some number of bytes up to  buf.len()  from the provided
 ///  offset  of the underlying file. The number of bytes written
 /// is returned.
 fn write_at(
&mut self,
buf: &mut [u8],
offset: u64,
) -> FileResult<u32>;
 

Thanks, decade ago paultag! Let s do it! Let s use arigato to implement a 9p filesystem we ll call debugfs that will serve all the debug files shipped according to the Packages metadata from the apt archive. We ll fetch the Packages file and construct a filesystem based on the reported Build-Id entries. For those who don t know much about how an apt repo works, here s the 2-second crash course on what we re doing. The first is to fetch the Packages file, which is specific to a binary architecture (such as amd64, arm64 or riscv64). That architecture is specific to a component (such as main, contrib or non-free). That component is specific to a suite, such as stable, unstable or any of its aliases (bullseye, bookworm, etc). Let s take a look at the Packages.xz file for the unstable-debug suite, main component, for all amd64 binaries.
$ curl \
https://deb.debian.org/debian-debug/dists/unstable-debug/main/binary-amd64/Packages.xz \
  unxz
This will return the Debian-style rfc2822-like headers, which is an export of the metadata contained inside each .deb file which apt (or other tools that can use the apt repo format) use to fetch information about debs. Let s take a look at the debug headers for the netlabel-tools package in unstable which is a package named netlabel-tools-dbgsym in unstable-debug.
Package: netlabel-tools-dbgsym
Source: netlabel-tools (0.30.0-1)
Version: 0.30.0-1+b1
Installed-Size: 79
Maintainer: Paul Tagliamonte <paultag@debian.org>
Architecture: amd64
Depends: netlabel-tools (= 0.30.0-1+b1)
Description: debug symbols for netlabel-tools
Auto-Built-Package: debug-symbols
Build-Ids: e59f81f6573dadd5d95a6e4474d9388ab2777e2a
Description-md5: a0e587a0cf730c88a4010f78562e6db7
Section: debug
Priority: optional
Filename: pool/main/n/netlabel-tools/netlabel-tools-dbgsym_0.30.0-1+b1_amd64.deb
Size: 62776
SHA256: 0e9bdb087617f0350995a84fb9aa84541bc4df45c6cd717f2157aa83711d0c60
So here, we can parse the package headers in the Packages.xz file, and store, for each Build-Id, the Filename where we can fetch the .deb at. Each .deb contains a number of files but we re only really interested in the files inside the .deb located at or under /usr/lib/debug/.build-id/, which you can find in debugfs under rfc822.rs. It s crude, and very single-purpose, but I m feeling a bit lazy.

Who needs dpkg?! For folks who haven t seen it yet, a .deb file is a special type of .ar file, that contains (usually) three files inside debian-binary, control.tar.xz and data.tar.xz. The core of an .ar file is a fixed size (60 byte) entry header, followed by the specified size number of bytes.
[8 byte .ar file magic]
[60 byte entry header]
[N bytes of data]
[60 byte entry header]
[N bytes of data]
[60 byte entry header]
[N bytes of data]
...
First up was to implement a basic ar parser in ar.rs. Before we get into using it to parse a deb, as a quick diversion, let s break apart a .deb file by hand something that is a bit of a rite of passage (or at least it used to be? I m getting old) during the Debian nm (new member) process, to take a look at where exactly the .debug file lives inside the .deb file.
$ ar x netlabel-tools-dbgsym_0.30.0-1+b1_amd64.deb
$ ls
control.tar.xz debian-binary
data.tar.xz netlabel-tools-dbgsym_0.30.0-1+b1_amd64.deb
$ tar --list -f data.tar.xz   grep '.debug$'
./usr/lib/debug/.build-id/e5/9f81f6573dadd5d95a6e4474d9388ab2777e2a.debug
Since we know quite a bit about the structure of a .deb file, and I had to implement support from scratch anyway, I opted to implement a (very!) basic debfile parser using HTTP Range requests. HTTP Range requests, if supported by the server (denoted by a accept-ranges: bytes HTTP header in response to an HTTP HEAD request to that file) means that we can add a header such as range: bytes=8-68 to specifically request that the returned GET body be the byte range provided (in the above case, the bytes starting from byte offset 8 until byte offset 68). This means we can fetch just the ar file entry from the .deb file until we get to the file inside the .deb we are interested in (in our case, the data.tar.xz file) at which point we can request the body of that file with a final range request. I wound up writing a struct to handle a read_at-style API surface in hrange.rs, which we can pair with ar.rs above and start to find our data in the .deb remotely without downloading and unpacking the .deb at all. After we have the body of the data.tar.xz coming back through the HTTP response, we get to pipe it through an xz decompressor (this kinda sucked in Rust, since a tokio AsyncRead is not the same as an http Body response is not the same as std::io::Read, is not the same as an async (or sync) Iterator is not the same as what the xz2 crate expects; leading me to read blocks of data to a buffer and stuff them through the decoder by looping over the buffer for each lzma2 packet in a loop), and tarfile parser (similarly troublesome). From there we get to iterate over all entries in the tarfile, stopping when we reach our file of interest. Since we can t seek, but gdb needs to, we ll pull it out of the stream into a Cursor<Vec<u8>> in-memory and pass a handle to it back to the user. From here on out its a matter of gluing together a File traited struct in debugfs, and serving the filesystem over TCP using arigato. Done deal!

A quick diversion about compression I was originally hoping to avoid transferring the whole tar file over the network (and therefore also reading the whole debug file into ram, which objectively sucks), but quickly hit issues with figuring out a way around seeking around an xz file. What s interesting is xz has a great primitive to solve this specific problem (specifically, use a block size that allows you to seek to the block as close to your desired seek position just before it, only discarding at most block size - 1 bytes), but data.tar.xz files generated by dpkg appear to have a single mega-huge block for the whole file. I don t know why I would have expected any different, in retrospect. That means that this now devolves into the base case of How do I seek around an lzma2 compressed data stream ; which is a lot more complex of a question. Thankfully, notoriously brilliant tianon was nice enough to introduce me to Jon Johnson who did something super similar adapted a technique to seek inside a compressed gzip file, which lets his service oci.dag.dev seek through Docker container images super fast based on some prior work such as soci-snapshotter, gztool, and zran.c. He also pulled this party trick off for apk based distros over at apk.dag.dev, which seems apropos. Jon was nice enough to publish a lot of his work on this specifically in a central place under the name targz on his GitHub, which has been a ton of fun to read through. The gist is that, by dumping the decompressor s state (window of previous bytes, in-memory data derived from the last N-1 bytes) at specific checkpoints along with the compressed data stream offset in bytes and decompressed offset in bytes, one can seek to that checkpoint in the compressed stream and pick up where you left off creating a similar block mechanism against the wishes of gzip. It means you d need to do an O(n) run over the file, but every request after that will be sped up according to the number of checkpoints you ve taken. Given the complexity of xz and lzma2, I don t think this is possible for me at the moment especially given most of the files I ll be requesting will not be loaded from again especially when I can just cache the debug header by Build-Id. I want to implement this (because I m generally curious and Jon has a way of getting someone excited about compression schemes, which is not a sentence I thought I d ever say out loud), but for now I m going to move on without this optimization. Such a shame, since it kills a lot of the work that went into seeking around the .deb file in the first place, given the debian-binary and control.tar.gz members are so small.

The Good First, the good news right? It works! That s pretty cool. I m positive my younger self would be amused and happy to see this working; as is current day paultag. Let s take debugfs out for a spin! First, we need to mount the filesystem. It even works on an entirely unmodified, stock Debian box on my LAN, which is huge. Let s take it for a spin:
$ mount \
-t 9p \
-o trans=tcp,version=9p2000.u,aname=unstable-debug \
192.168.0.2 \
/usr/lib/debug/.build-id/
And, let s prove to ourselves that this actually mounted before we go trying to use it:
$ mount   grep build-id
192.168.0.2 on /usr/lib/debug/.build-id type 9p (rw,relatime,aname=unstable-debug,access=user,trans=tcp,version=9p2000.u,port=564)
Slick. We ve got an open connection to the server, where our host will keep a connection alive as root, attached to the filesystem provided in aname. Let s take a look at it.
$ ls /usr/lib/debug/.build-id/
00 0d 1a 27 34 41 4e 5b 68 75 82 8E 9b a8 b5 c2 CE db e7 f3
01 0e 1b 28 35 42 4f 5c 69 76 83 8f 9c a9 b6 c3 cf dc E7 f4
02 0f 1c 29 36 43 50 5d 6a 77 84 90 9d aa b7 c4 d0 dd e8 f5
03 10 1d 2a 37 44 51 5e 6b 78 85 91 9e ab b8 c5 d1 de e9 f6
04 11 1e 2b 38 45 52 5f 6c 79 86 92 9f ac b9 c6 d2 df ea f7
05 12 1f 2c 39 46 53 60 6d 7a 87 93 a0 ad ba c7 d3 e0 eb f8
06 13 20 2d 3a 47 54 61 6e 7b 88 94 a1 ae bb c8 d4 e1 ec f9
07 14 21 2e 3b 48 55 62 6f 7c 89 95 a2 af bc c9 d5 e2 ed fa
08 15 22 2f 3c 49 56 63 70 7d 8a 96 a3 b0 bd ca d6 e3 ee fb
09 16 23 30 3d 4a 57 64 71 7e 8b 97 a4 b1 be cb d7 e4 ef fc
0a 17 24 31 3e 4b 58 65 72 7f 8c 98 a5 b2 bf cc d8 E4 f0 fd
0b 18 25 32 3f 4c 59 66 73 80 8d 99 a6 b3 c0 cd d9 e5 f1 fe
0c 19 26 33 40 4d 5a 67 74 81 8e 9a a7 b4 c1 ce da e6 f2 ff
Outstanding. Let s try using gdb to debug a binary that was provided by the Debian archive, and see if it ll load the ELF by build-id from the right .deb in the unstable-debug suite:
$ gdb -q /usr/sbin/netlabelctl
Reading symbols from /usr/sbin/netlabelctl...
Reading symbols from /usr/lib/debug/.build-id/e5/9f81f6573dadd5d95a6e4474d9388ab2777e2a.debug...
(gdb)
Yes! Yes it will!
$ file /usr/lib/debug/.build-id/e5/9f81f6573dadd5d95a6e4474d9388ab2777e2a.debug
/usr/lib/debug/.build-id/e5/9f81f6573dadd5d95a6e4474d9388ab2777e2a.debug: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, interpreter *empty*, BuildID[sha1]=e59f81f6573dadd5d95a6e4474d9388ab2777e2a, for GNU/Linux 3.2.0, with debug_info, not stripped

The Bad Linux s support for 9p is mainline, which is great, but it s not robust. Network issues or server restarts will wedge the mountpoint (Linux can t reconnect when the tcp connection breaks), and things that work fine on local filesystems get translated in a way that causes a lot of network chatter for instance, just due to the way the syscalls are translated, doing an ls, will result in a stat call for each file in the directory, even though linux had just got a stat entry for every file while it was resolving directory names. On top of that, Linux will serialize all I/O with the server, so there s no concurrent requests for file information, writes, or reads pending at the same time to the server; and read and write throughput will degrade as latency increases due to increasing round-trip time, even though there are offsets included in the read and write calls. It works well enough, but is frustrating to run up against, since there s not a lot you can do server-side to help with this beyond implementing the 9P2000.L variant (which, maybe is worth it).

The Ugly Unfortunately, we don t know the file size(s) until we ve actually opened the underlying tar file and found the correct member, so for most files, we don t know the real size to report when getting a stat. We can t parse the tarfiles for every stat call, since that d make ls even slower (bummer). Only hiccup is that when I report a filesize of zero, gdb throws a bit of a fit; let s try with a size of 0 to start:
$ ls -lah /usr/lib/debug/.build-id/e5/9f81f6573dadd5d95a6e4474d9388ab2777e2a.debug
-r--r--r-- 1 root root 0 Dec 31 1969 /usr/lib/debug/.build-id/e5/9f81f6573dadd5d95a6e4474d9388ab2777e2a.debug
$ gdb -q /usr/sbin/netlabelctl
Reading symbols from /usr/sbin/netlabelctl...
Reading symbols from /usr/lib/debug/.build-id/e5/9f81f6573dadd5d95a6e4474d9388ab2777e2a.debug...
warning: Discarding section .note.gnu.build-id which has a section size (24) larger than the file size [in module /usr/lib/debug/.build-id/e5/9f81f6573dadd5d95a6e4474d9388ab2777e2a.debug]
[...]
This obviously won t work since gdb will throw away all our hard work because of stat s output, and neither will loading the real size of the underlying file. That only leaves us with hardcoding a file size and hope nothing else breaks significantly as a result. Let s try it again:
$ ls -lah /usr/lib/debug/.build-id/e5/9f81f6573dadd5d95a6e4474d9388ab2777e2a.debug
-r--r--r-- 1 root root 954M Dec 31 1969 /usr/lib/debug/.build-id/e5/9f81f6573dadd5d95a6e4474d9388ab2777e2a.debug
$ gdb -q /usr/sbin/netlabelctl
Reading symbols from /usr/sbin/netlabelctl...
Reading symbols from /usr/lib/debug/.build-id/e5/9f81f6573dadd5d95a6e4474d9388ab2777e2a.debug...
(gdb)
Much better. I mean, terrible but better. Better for now, anyway.

Kilroy was here Do I think this is a particularly good idea? I mean; kinda. I m probably going to make some fun 9p arigato-based filesystems for use around my LAN, but I don t think I ll be moving to use debugfs until I can figure out how to ensure the connection is more resilient to changing networks, server restarts and fixes on i/o performance. I think it was a useful exercise and is a pretty great hack, but I don t think this ll be shipping anywhere anytime soon. Along with me publishing this post, I ve pushed up all my repos; so you should be able to play along at home! There s a lot more work to be done on arigato; but it does handshake and successfully export a working 9P2000.u filesystem. Check it out on on my github at arigato, debugfs and also on crates.io and docs.rs. At least I can say I was here and I got it working after all these years.

3 April 2024

Joey Hess: reflections on distrusting xz

Was the ssh backdoor the only goal that "Jia Tan" was pursuing with their multi-year operation against xz? I doubt it, and if not, then every fix so far has been incomplete, because everything is still running code written by that entity. If we assume that they had a multilayered plan, that their every action was calculated and malicious, then we have to think about the full threat surface of using xz. This quickly gets into nightmare scenarios of the "trusting trust" variety. What if xz contains a hidden buffer overflow or other vulnerability, that can be exploited by the xz file it's decompressing? This would let the attacker target other packages, as needed. Let's say they want to target gcc. Well, gcc contains a lot of documentation, which includes png images. So they spend a while getting accepted as a documentation contributor on that project, and get added to it a png file that is specially constructed, it has additional binary data appended that exploits the buffer overflow. And instructs xz to modify the source code that comes later when decompressing gcc.tar.xz. More likely, they wouldn't bother with an actual trusting trust attack on gcc, which would be a lot of work to get right. One problem with the ssh backdoor is that well, not all servers on the internet run ssh. (Or systemd.) So webservers seem a likely target of this kind of second stage attack. Apache's docs include png files, nginx does not, but there's always scope to add improved documentation to a project. When would such a vulnerability have been introduced? In February, "Jia Tan" wrote a new decoder for xz. This added 1000+ lines of new C code across several commits. So much code and in just the right place to insert something like this. And why take on such a significant project just two months before inserting the ssh backdoor? "Jia Tan" was already fully accepted as maintainer, and doing lots of other work, it doesn't seem to me that they needed to start this rewrite as part of their cover. They were working closely with xz's author Lasse Collin in this, by indications exchanging patches offlist as they developed it. So Lasse Collin's commits in this time period are also worth scrutiny, because they could have been influenced by "Jia Tan". One that caught my eye comes immediately afterwards: "prepares the code for alternative C versions and inline assembly" Multiple versions and assembly mean even more places to hide such a security hole. I stress that I have not found such a security hole, I'm only considering what the worst case possibilities are. I think we need to fully consider them in order to decide how to fully wrap up this mess. Whether such stealthy security holes have been introduced into xz by "Jia Tan" or not, there are definitely indications that the ssh backdoor was not the end of what they had planned. For one thing, the "test file" based system they introduced was extensible. They could have been planning to add more test files later, that backdoored xz in further ways. And then there's the matter of the disabling of the Landlock sandbox. This was not necessary for the ssh backdoor, because the sandbox is only used by the xz command, not by liblzma. So why did they potentially tip their hand by adding that rogue "." that disables the sandbox? A sandbox would not prevent the kind of attack I discuss above, where xz is just modifying code that it decompresses. Disabling the sandbox suggests that they were going to make xz run arbitrary code, that perhaps wrote to files it shouldn't be touching, to install a backdoor in the system. Both deb and rpm use xz compression, and with the sandbox disabled, whether they link with liblzma or run the xz command, a backdoored xz can write to any file on the system while dpkg or rpm is running and noone is likely to notice, because that's the kind of thing a package manager does. My impression is that all of this was well planned and they were in it for the long haul. They had no reason to stop with backdooring ssh, except for the risk of additional exposure. But they decided to take that risk, with the sandbox disabling. So they planned to do more, and every commit by "Jia Tan", and really every commit that they could have influenced needs to be distrusted. This is why I've suggested to Debian that they revert to an earlier version of xz. That would be my advice to anyone distributing xz. I do have a xz-unscathed fork which I've carefully constructed to avoid all "Jia Tan" involved commits. It feels good to not need to worry about dpkg and tar. I only plan to maintain this fork minimally, eg security fixes. Hopefully Lasse Collin will consider these possibilities and address them in his response to the attack.

Arnaud Rebillout: Firefox: Moving from the Debian package to the Flatpak app (long-term?)

First, thanks to Samuel Henrique for giving notice of recent Firefox CVEs in Debian testing/unstable. At the time I didn't want to upgrade my system (Debian Sid) due to the ongoing t64 transition transition, so I decided I could install the Firefox Flatpak app instead, and why not stick to it long-term? This blog post details all the steps, if ever others want to go the same road. Flatpak Installation Disclaimer: this section is hardly anything more than a copy/paste of the official documentation, and with time it will get outdated, so you'd better follow the official doc. First thing first, let's install Flatpak:
$ sudo apt update
$ sudo apt install flatpak
Then the next step is to add the Flathub remote repository, from where we'll get our Flatpak applications:
$ flatpak remote-add --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo
And that's all there is to it! Now come the optional steps. For GNOME and KDE users, you might want to install a plugin for the software manager specific to your desktop, so that it can support and manage Flatpak apps:
$ which -s gnome-software  && sudo apt install gnome-software-plugin-flatpak
$ which -s plasma-discover && sudo apt install plasma-discover-backend-flatpak
And here's an additional check you can do, as it's something that did bite me in the past: missing xdg-portal-* packages, that are required for Flatpak applications to communicate with the desktop environment. Just to be sure, you can check the output of apt search '^xdg-desktop-portal' to see what's available, and compare with the output of dpkg -l grep xdg-desktop-portal. As you can see, if you're a GNOME or KDE user, there's a portal backend for you, and it should be installed. For reference, this is what I have on my GNOME desktop at the moment:
$ dpkg -l   grep xdg-desktop-portal   awk ' print $2 '
xdg-desktop-portal
xdg-desktop-portal-gnome
xdg-desktop-portal-gtk
Install the Firefox Flatpak app This is trivial, but still, there's a question I've always asked myself: should I install applications system-wide (aka. flatpak --system, the default) or per-user (aka. flatpak --user)? Turns out, this questions is answered in the Flatpak documentation:
Flatpak commands are run system-wide by default. If you are installing applications for day-to-day usage, it is recommended to stick with this default behavior.
Armed with this new knowledge, let's install the Firefox app:
$ flatpak install flathub org.mozilla.firefox
And that's about it! We can give it a go already:
$ flatpak run org.mozilla.firefox
Data migration At this point, running Firefox via Flatpak gives me an "empty" Firefox. That's not what I want, instead I want my usual Firefox, with a gazillion of tabs already opened, a few extensions, bookmarks and so on. As it turns out, Mozilla provides a brief doc for data migration, and it's as simple as moving Firefox data directory around! To clarify, we'll be copying data: Make sure that all Firefox instances are closed, then proceed:
# BEWARE! Below I'm erasing data!
$ rm -fr ~/.var/app/org.mozilla.firefox/.mozilla/firefox/
$ cp -a ~/.mozilla/firefox/ ~/.var/app/org.mozilla.firefox/.mozilla/
To avoid confusing myself, it's also a good idea to rename the local data directory:
$ mv ~/.mozilla/firefox ~/.mozilla/firefox.old.$(date --iso-8601=date)
At this point, flatpak run org.mozilla.firefox takes me to my "usual" everyday Firefox, with all its tabs opened, pinned, bookmarked, etc. More integration? After following all the steps above, I must say that I'm 99% happy. So far, everything works as before, I didn't hit any issue, and I don't even notice that Firefox is running via Flatpak, it's completely transparent. So where's the 1% of unhappiness? The Run a Command dialog from GNOME, the one that shows up via the keyboard shortcut <Alt+F2>. This is how I start my GUI applications, and I usually run two Firefox instances in parallel (one for work, one for personal), using the firefox -p <profile> command. Given that I ran apt purge firefox before (to avoid confusing myself with two installations of Firefox), now the right (and only) way to start Firefox from a command-line is to type flatpak run org.mozilla.firefox -p <profile>. Typing that every time is way too cumbersome, so I need something quicker. Seems like the most straightforward is to create a wrapper script:
$ cat /usr/local/bin/firefox 
#!/bin/sh
exec flatpak run org.mozilla.firefox "$@"
And now I can just hit <Alt+F2> and type firefox -p <profile> to start Firefox with the profile I want, just as before. Neat! Looking forward: system updates I usually update my system manually every now and then, via the well-known pair of commands:
$ sudo apt update
$ sudo apt full-upgrade
The downside of introducing Flatpak, ie. introducing another package manager, is that I'll need to learn new commands to update the software that comes via this channel. Fortunately, there's really not much to learn. From flatpak-update(1):
flatpak update [OPTION...] [REF...] Updates applications and runtimes. [...] If no REF is given, everything is updated, as well as appstream info for all remotes.
Could it be that simple? Apparently yes, the Flatpak equivalent of the two apt commands above is just:
$ flatpak update
Going forward, my options are:
  1. Teach myself to run flatpak update additionally to apt update, manually, everytime I update my system.
  2. Go crazy: let something automatically update my Flatpak apps, in my back and without my consent.
I'm actually tempted to go for option 2 here, and I wonder if GNOME Software will do that for me, provided that I installed gnome-software-plugin-flatpak, and that I checked Software Updates -> Automatic in the Settings (which I did). However, I didn't find any documentation regarding what this setting really does, so I can't say if it will only download updates, or if it will also install it. I'd be happy if it automatically installs new version of Flatpak apps, but at the same time I'd be very unhappy if it automatically upgrades my Debian system... So we'll see. Enough for today, hope this blog post was useful!

2 April 2024

Bits from Debian: Bits from the DPL

Dear Debianites This morning I decided to just start writing Bits from DPL and send whatever I have by 18:00 local time. Here it is, barely proof read, along with all it's warts and grammar mistakes! It's slightly long and doesn't contain any critical information, so if you're not in the mood, don't feel compelled to read it! Get ready for a new DPL! Soon, the voting period will start to elect our next DPL, and my time as DPL will come to an end. Reading the questions posted to the new candidates on debian-vote, it takes quite a bit of restraint to not answer all of them myself, I think I can see how that aspect contributed to me being reeled in to running for DPL! In total I've done so 5 times (the first time I ran, Sam was elected!). Good luck to both Andreas and Sruthi, our current DPL candidates! I've already started working on preparing handover, and there's multiple request from teams that have came in recently that will have to wait for the new term, so I hope they're both ready to hit the ground running! Things that I wish could have gone better Communication Recently, I saw a t-shirt that read:
Adulthood is saying, 'But after this week things will slow down a bit' over and over until you die.
I can relate! With every task, crisis or deadline that appears, I think that once this is over, I'll have some more breathing space to get back to non-urgent, but important tasks. "Bits from the DPL" was something I really wanted to get right this last term, and clearly failed spectacularly. I have two long Bits from the DPL drafts that I never finished, I tend to have prioritised problems of the day over communication. With all the hindsight I have, I'm not sure which is better to prioritise, I do rate communication and transparency very highly and this is really the top thing that I wish I could've done better over the last four years. On that note, thanks to people who provided me with some kind words when I've mentioned this to them before. They pointed out that there are many other ways to communicate and be in touch with the community, and they mentioned that they thought that I did a good job with that. Since I'm still on communication, I think we can all learn to be more effective at it, since it's really so important for the project. Every time I publicly spoke about us spending more money, we got more donations. People out there really like to see how we invest funds in to Debian, instead of just making it heap up. DSA just spent a nice chunk on money on hardware, but we don't have very good visibility on it. It's one thing having it on a public line item in SPI's reporting, but it would be much more exciting if DSA could provide a write-up on all the cool hardware they're buying and what impact it would have on developers, and post it somewhere prominent like debian-devel-announce, Planet Debian or Bits from Debian (from the publicity team). I don't want to single out DSA there, it's difficult and affects many other teams. The Salsa CI team also spent a lot of resources (time and money wise) to extend testing on AMD GPUs and other AMD hardware. It's fantastic and interesting work, and really more people within the project and in the outside world should know about it! I'm not going to push my agendas to the next DPL, but I hope that they continue to encourage people to write about their work, and hopefully at some point we'll build enough excitement in doing so that it becomes a more normal part of our daily work. Founding Debian as a standalone entity This was my number one goal for the project this last term, which was a carried over item from my previous terms. I'm tempted to write everything out here, including the problem statement and our current predicaments, what kind of ground work needs to happen, likely constitutional changes that need to happen, and the nature of the GR that would be needed to make such a thing happen, but if I start with that, I might not finish this mail. In short, I 100% believe that this is still a very high ranking issue for Debian, and perhaps after my term I'd be in a better position to spend more time on this (hmm, is this an instance of "The grass is always better on the other side", or "Next week will go better until I die?"). Anyway, I'm willing to work with any future DPL on this, and perhaps it can in itself be a delegation tasked to properly explore all the options, and write up a report for the project that can lead to a GR. Overall, I'd rather have us take another few years and do this properly, rather than rush into something that is again difficult to change afterwards. So while I very much wish this could've been achieved in the last term, I can't say that I have any regrets here either. My terms in a nutshell COVID-19 and Debian 11 era My first term in 2020 started just as the COVID-19 pandemic became known to spread globally. It was a tough year for everyone, and Debian wasn't immune against its effects either. Many of our contributors got sick, some have lost loved ones (my father passed away in March 2020 just after I became DPL), some have lost their jobs (or other earners in their household have) and the effects of social distancing took a mental and even physical health toll on many. In Debian, we tend to do really well when we get together in person to solve problems, and when DebConf20 got cancelled in person, we understood that that was necessary, but it was still more bad news in a year we had too much of it already. I can't remember if there was ever any kind of formal choice or discussion about this at any time, but the DebConf video team just kind of organically and spontaneously became the orga team for an online DebConf, and that lead to our first ever completely online DebConf. This was great on so many levels. We got to see each other's faces again, even though it was on screen. We had some teams talk to each other face to face for the first time in years, even though it was just on a Jitsi call. It had a lasting cultural change in Debian, some teams still have video meetings now, where they didn't do that before, and I think it's a good supplement to our other methods of communication. We also had a few online Mini-DebConfs that was fun, but DebConf21 was also online, and by then we all developed an online conference fatigue, and while it was another good online event overall, it did start to feel a bit like a zombieconf and after that, we had some really nice events from the Brazillians, but no big global online community events again. In my opinion online MiniDebConfs can be a great way to develop our community and we should spend some further energy into this, but hey! This isn't a platform so let me back out of talking about the future as I see it... Despite all the adversity that we faced together, the Debian 11 release ended up being quite good. It happened about a month or so later than what we ideally would've liked, but it was a solid release nonetheless. It turns out that for quite a few people, staying inside for a few months to focus on Debian bugs was quite productive, and Debian 11 ended up being a very polished release. During this time period we also had to deal with a previous Debian Developer that was expelled for his poor behaviour in Debian, who continued to harass members of the Debian project and in other free software communities after his expulsion. This ended up being quite a lot of work since we had to take legal action to protect our community, and eventually also get the police involved. I'm not going to give him the satisfaction by spending too much time talking about him, but you can read our official statement regarding Daniel Pocock here: https://www.debian.org/News/2021/20211117 In late 2021 and early 2022 we also discussed our general resolution process, and had two consequent votes to address some issues that have affected past votes: In my first term I addressed our delegations that were a bit behind, by the end of my last term all delegation requests are up to date. There's still some work to do, but I'm feeling good that I get to hand this over to the next DPL in a very decent state. Delegation updates can be very deceiving, sometimes a delegation is completely re-written and it was just 1 or 2 hours of work. Other times, a delegation updated can contain one line that has changed or a change in one team member that was the result of days worth of discussion and hashing out differences. I also received quite a few requests either to host a service, or to pay a third-party directly for hosting. This was quite an admin nightmare, it either meant we had to manually do monthly reimbursements to someone, or have our TOs create accounts/agreements at the multiple providers that people use. So, after talking to a few people about this, we founded the DebianNet team (we could've admittedly chosen a better name, but that can happen later on) for providing hosting at two different hosting providers that we have agreement with so that people who host things under debian.net have an easy way to host it, and then at the same time Debian also has more control if a site maintainer goes MIA. More info: https://wiki.debian.org/Teams/DebianNet You might notice some Openstack mentioned there, we had some intention to set up a Debian cloud for hosting these things, that could also be used for other additional Debiany things like archive rebuilds, but these have so far fallen through. We still consider it a good idea and hopefully it will work out some other time (if you're a large company who can sponsor few racks and servers, please get in touch!) DebConf22 and Debian 12 era DebConf22 was the first time we returned to an in-person DebConf. It was a bit smaller than our usual DebConf - understandably so, considering that there were still COVID risks and people who were at high risk or who had family with high risk factors did the sensible thing and stayed home. After watching many MiniDebConfs online, I also attended my first ever MiniDebConf in Hamburg. It still feels odd typing that, it feels like I should've been at one before, but my location makes attending them difficult (on a side-note, a few of us are working on bootstrapping a South African Debian community and hopefully we can pull off MiniDebConf in South Africa later this year). While I was at the MiniDebConf, I gave a talk where I covered the evolution of firmware, from the simple e-proms that you'd find in old printers to the complicated firmware in modern GPUs that basically contain complete operating systems- complete with drivers for the device their running on. I also showed my shiny new laptop, and explained that it's impossible to install that laptop without non-free firmware (you'd get a black display on d-i or Debian live). Also that you couldn't even use an accessibility mode with audio since even that depends on non-free firmware these days. Steve, from the image building team, has said for a while that we need to do a GR to vote for this, and after more discussion at DebConf, I kept nudging him to propose the GR, and we ended up voting in favour of it. I do believe that someone out there should be campaigning for more free firmware (unfortunately in Debian we just don't have the resources for this), but, I'm glad that we have the firmware included. In the end, the choice comes down to whether we still want Debian to be installable on mainstream bare-metal hardware. At this point, I'd like to give a special thanks to the ftpmasters, image building team and the installer team who worked really hard to get the changes done that were needed in order to make this happen for Debian 12, and for being really proactive for remaining niggles that was solved by the time Debian 12.1 was released. The included firmware contributed to Debian 12 being a huge success, but it wasn't the only factor. I had a list of personal peeves, and as the hard freeze hit, I lost hope that these would be fixed and made peace with the fact that Debian 12 would release with those bugs. I'm glad that lots of people proved me wrong and also proved that it's never to late to fix bugs, everything on my list got eliminated by the time final freeze hit, which was great! We usually aim to have a release ready about 2 years after the previous release, sometimes there are complications during a freeze and it can take a bit longer. But due to the excellent co-ordination of the release team and heavy lifting from many DDs, the Debian 12 release happened 21 months and 3 weeks after the Debian 11 release. I hope the work from the release team continues to pay off so that we can achieve their goals of having shorter and less painful freezes in the future! Even though many things were going well, the ongoing usr-merge effort highlighted some social problems within our processes. I started typing out the whole history of usrmerge here, but it's going to be too long for the purpose of this mail. Important questions that did come out of this is, should core Debian packages be team maintained? And also about how far the CTTE should really be able to override a maintainer. We had lots of discussion about this at DebConf22, but didn't make much concrete progress. I think that at some point we'll probably have a GR about package maintenance. Also, thank you to Guillem who very patiently explained a few things to me (after probably having have to done so many times to others before already) and to Helmut who have done the same during the MiniDebConf in Hamburg. I think all the technical and social issues here are fixable, it will just take some time and patience and I have lots of confidence in everyone involved. UsrMerge wiki page: https://wiki.debian.org/UsrMerge DebConf 23 and Debian 13 era DebConf23 took place in Kochi, India. At the end of my Bits from the DPL talk there, someone asked me what the most difficult thing I had to do was during my terms as DPL. I answered that nothing particular stood out, and even the most difficult tasks ended up being rewarding to work on. Little did I know that my most difficult period of being DPL was just about to follow. During the day trip, one of our contributors, Abraham Raji, passed away in a tragic accident. There's really not anything anyone could've done to predict or stop it, but it was devastating to many of us, especially the people closest to him. Quite a number of DebConf attendees went to his funeral, wearing the DebConf t-shirts he designed as a tribute. It still haunts me when I saw his mother scream "He was my everything! He was my everything!", this was by a large margin the hardest day I've ever had in Debian, and I really wasn't ok for even a few weeks after that and I think the hurt will be with many of us for some time to come. So, a plea again to everyone, please take care of yourself! There's probably more people that love you than you realise. A special thanks to the DebConf23 team, who did a really good job despite all the uphills they faced (and there were many!). As DPL, I think that planning for a DebConf is near to impossible, all you can do is show up and just jump into things. I planned to work with Enrico to finish up something that will hopefully save future DPLs some time, and that is a web-based DD certificate creator instead of having the DPL do so manually using LaTeX. It already mostly works, you can see the work so far by visiting https://nm.debian.org/person/ACCOUNTNAME/certificate/ and replacing ACCOUNTNAME with your Debian account name, and if you're a DD, you should see your certificate. It still needs a few minor changes and a DPL signature, but at this point I think that will be finished up when the new DPL start. Thanks to Enrico for working on this! Since my first term, I've been trying to find ways to improve all our accounting/finance issues. Tracking what we spend on things, and getting an annual overview is hard, especially over 3 trusted organisations. The reimbursement process can also be really tedious, especially when you have to provide files in a certain order and combine them into a PDF. So, at DebConf22 we had a meeting along with the treasurer team and Stefano Rivera who said that it might be possible for him to work on a new system as part of his Freexian work. It worked out, and Freexian funded the development of the system since then, and after DebConf23 we handled the reimbursements for the conference via the new reimbursements site: https://reimbursements.debian.net/ It's still early days, but over time it should be linked to all our TOs and we'll use the same category codes across the board. So, overall, our reimbursement process becomes a lot simpler, and also we'll be able to get information like how much money we've spent on any category in any period. It will also help us to track how much money we have available or how much we spend on recurring costs. Right now that needs manual polling from our TOs. So I'm really glad that this is a big long-standing problem in the project that is being fixed. For Debian 13, we're waving goodbye to the KFreeBSD and mipsel ports. But we're also gaining riscv64 and loongarch64 as release architectures! I have 3 different RISC-V based machines on my desk here that I haven't had much time to work with yet, you can expect some blog posts about them soon after my DPL term ends! As Debian is a unix-like system, we're affected by the Year 2038 problem, where systems that uses 32 bit time in seconds since 1970 run out of available time and will wrap back to 1970 or have other undefined behaviour. A detailed wiki page explains how this works in Debian, and currently we're going through a rather large transition to make this possible. I believe this is the right time for Debian to be addressing this, we're still a bit more than a year away for the Debian 13 release, and this provides enough time to test the implementation before 2038 rolls along. Of course, big complicated transitions with dependency loops that causes chaos for everyone would still be too easy, so this past weekend (which is a holiday period in most of the west due to Easter weekend) has been filled with dealing with an upstream bug in xz-utils, where a backdoor was placed in this key piece of software. An Ars Technica covers it quite well, so I won't go into all the details here. I mention it because I want to give yet another special thanks to everyone involved in dealing with this on the Debian side. Everyone involved, from the ftpmasters to security team and others involved were super calm and professional and made quick, high quality decisions. This also lead to the archive being frozen on Saturday, this is the first time I've seen this happen since I've been a DD, but I'm sure next week will go better! Looking forward It's really been an honour for me to serve as DPL. It might well be my biggest achievement in my life. Previous DPLs range from prominent software engineers to game developers, or people who have done things like complete Iron Man, run other huge open source projects and are part of big consortiums. Ian Jackson even authored dpkg and is now working on the very interesting tag2upload service! I'm a relative nobody, just someone who grew up as a poor kid in South Africa, who just really cares about Debian a lot. And, above all, I'm really thankful that I didn't do anything major to screw up Debian for good. Not unlike learning how to use Debian, and also becoming a Debian Developer, I've learned a lot from this and it's been a really valuable growth experience for me. I know I can't possible give all the thanks to everyone who deserves it, so here's a big big thanks to everyone who have worked so hard and who have put in many, many hours to making Debian better, I consider you all heroes! -Jonathan

1 April 2024

Colin Watson: Free software activity in March 2024

My Debian contributions this month were all sponsored by Freexian.

26 March 2024

Emmanuel Kasper: Adding a private / custom Certificate Authority to the firefox trust store

Today at $WORK I needed to add the private company Certificate Authority (CA) to Firefox, and I found the steps were unnecessarily complex. Time to blog about that, and I also made a Debian wiki article of that post, so that future generations can update the information, when Firefox 742 is released on Debian 17. The cacert certificate authority is not included in Debian and Firefox, and is thus a good example of adding a private CA. Note that this does not mean I specifically endorse that CA.
  • Test that SSL connections to a site signed by the private CA is failing
$ gnutls-cli wiki.cacert.org:443
...
- Status: The certificate is NOT trusted. The certificate issuer is unknown. 
*** PKI verification of server certificate failed...
*** Fatal error: Error in the certificate.
  • Download the private CA
$ wget http://www.cacert.org/certs/root_X0F.crt
  • test that a connection works with the private CA
$ gnutls-cli --x509cafile root_X0F.crt wiki.cacert.org:443
...
- Status: The certificate is trusted. 
- Description: (TLS1.2-X.509)-(ECDHE-SECP256R1)-(RSA-SHA256)-(AES-256-GCM)
- Session ID: 37:56:7A:89:EA:5F:13:E8:67:E4:07:94:4B:52:23:63:1E:54:31:69:5D:70:17:3C:D0:A4:80:B0:3A:E5:22:B3
- Options: safe renegotiation,
- Handshake was completed
...
  • add the private CA to the Debian trust store located in /etc/ssl/certs/ca-certificates.crt
$ sudo cp root_X0F.crt /usr/local/share/ca-certificates/cacert-org-root-ca.crt
$ sudo update-ca-certificates --verbose
...
Adding debian:cacert-org-root-ca.pem
...
  • verify that we can connect without passing the private CA on the command line
$ gnutls-cli wiki.cacert.org:443
... 
 - Status: The certificate is trusted.
  • At that point most applications are able to connect to systems with a certificate signed by the private CA (curl, Gnome builtin Browser ). However Firefox is using its own trust store and will still display a security error if connecting to https://wiki.cacert.org. To make Firefox trust the Debian trust store, we need to add a so called security device, in fact an extra library wrapping the Debian trust store. The library will wrap the Debian trust store in the PKCS#11 industry format that Firefox supports.
  • install the pkcs#11 wrapping library and command line tools
$ sudo apt install p11-kit p11-kit-modules
  • verify that the private CA is accessible via PKCS#11
$ trust list   grep --context 2 'CA Cert'
pkcs11:id=%16%B5%32%1B%D4%C7%F3%E0%E6%8E%F3%BD%D2%B0%3A%EE%B2%39%18%D1;type=cert
    type: certificate
    label: CA Cert Signing Authority
    trust: anchor
    category: authority
  • now we need to add a new security device in Firefox pointing to the pkcs11 trust store. The pkcs11 trust store is located in /usr/lib/x86_64-linux-gnu/pkcs11/p11-kit-trust.so
$ dpkg --listfiles p11-kit-modules   grep trust
/usr/lib/x86_64-linux-gnu/pkcs11/p11-kit-trust.so
  • in Firefox (tested in version 115 esr), go to Settings -> Privacy & Security -> Security -> Security Devices.
    Then click Load , in the popup window use My local trust as a module name, and /usr/lib/x86_64-linux-gnu/pkcs11/p11-kit-trust.so as a module filename. After adding the module, you should see it in the list of Security Devices, having /etc/ssl/certs/ca-certificates.crt as a description.
  • now restart Firefox and you should be able to browse https://wiki.cacert.org without security errors

24 March 2024

Niels Thykier: debputy v0.1.21

Earlier today, I have just released debputy version 0.1.21 to Debian unstable. In the blog post, I will highlight some of the new features.
Package boilerplate reduction with automatic relationship substvar Last month, I started a discussion on rethinking how we do relationship substvars such as the $ misc:Depends . These generally ends up being boilerplate runes in the form of Depends: $ misc:Depends , $ shlibs:Depends where you as the packager has to remember exactly which runes apply to your package. My proposed solution was to automatically apply these substvars and this feature has now been implemented in debputy. It is also combined with the feature where essential packages should use Pre-Depends by default for dpkg-shlibdeps related dependencies. I am quite excited about this feature, because I noticed with libcleri that we are now down to 3-5 fields for defining a simple library package. Especially since most C library packages are trivial enough that debputy can auto-derive them to be Multi-Arch: same. As an example, the libcleric1 package is down to 3 fields (Package, Architecture, Description) with Section and Priority being inherited from the Source stanza. I have submitted a MR to show case the boilerplate reduction at https://salsa.debian.org/siridb-team/libcleri/-/merge_requests/3. The removal of libcleric1 (= $ binary:Version ) in that MR relies on another existing feature where debputy can auto-derive a dependency between an arch:any -dev package and the library package based on the .so symlink for the shared library. The arch:any restriction comes from the fact that arch:all and arch:any packages are not built together, so debputy cannot reliably see across the package boundaries during the build (and therefore refuses to do so at all). Packages that have already migrated to debputy can use debputy migrate-from-dh to detect any unnecessary relationship substitution variables in case you want to clean up. The removal of Multi-Arch: same and intra-source dependencies must be done manually and so only be done so when you have validated that it is safe and sane to do. I was willing to do it for the show-case MR, but I am less confident that would bother with these for existing packages in general. Note: I summarized the discussion of the automatic relationship substvar feature earlier this month in https://lists.debian.org/debian-devel/2024/03/msg00030.html for those who want more details. PS: The automatic relationship substvars feature will also appear in debhelper as a part of compat 14.
Language Server (LSP) and Linting I have long been frustrated by our poor editor support for Debian packaging files. To this end, I started working on a Language Server (LSP) feature in debputy that would cover some of our standard Debian packaging files. This release includes the first version of said language server, which covers the following files:
  • debian/control
  • debian/copyright (the machine readable variant)
  • debian/changelog (mostly just spelling)
  • debian/rules
  • debian/debputy.manifest (syntax checks only; use debputy check-manifest for the full validation for now)
Most of the effort has been spent on the Deb822 based files such as debian/control, which comes with diagnostics, quickfixes, spellchecking (but only for relevant fields!), and completion suggestions. Since not everyone has a LSP capable editor and because sometimes you just want diagnostics without having to open each file in an editor, there is also a batch version for the diagnostics via debputy lint. Please see debputy(1) for how debputy lint compares with lintian if you are curious about which tool to use at what time. To help you getting started, there is a now debputy lsp editor-config command that can provide you with the relevant editor config glue. At the moment, emacs (via eglot) and vim with vim-youcompleteme are supported. For those that followed the previous blog posts on writing the language server, I would like to point out that the command line for running the language server has changed to debputy lsp server and you no longer have to tell which format it is. I have decided to make the language server a "polyglot" server for now, which I will hopefully not regret... Time will tell. :) Anyhow, to get started, you will want:
$ apt satisfy 'dh-debputy (>= 0.1.21~), python3-pygls'
# Optionally, for spellchecking
$ apt install python3-hunspell hunspell-en-us
# For emacs integration
$ apt install elpa-dpkg-dev-el markdown-mode-el
# For vim integration via vim-youcompleteme
$ apt install vim-youcompleteme
Specifically for emacs, I also learned two things after the upload. First, you can auto-activate eglot via eglot-ensure. This badly feature interacts with imenu on debian/changelog for reasons I do not understand (causing a several second start up delay until something times out), but it works fine for the other formats. Oddly enough, opening a changelog file and then activating eglot does not trigger this issue at all. In the next version, editor config for emacs will auto-activate eglot on all files except debian/changelog. The second thing is that if you install elpa-markdown-mode, emacs will accept and process markdown in the hover documentation provided by the language server. Accordingly, the editor config for emacs will also mention this package from the next version on. Finally, on a related note, Jelmer and I have been looking at moving some of this logic into a new package called debpkg-metadata. The point being to support easier reuse of linting and LSP related metadata - like pulling a list of known fields for debian/control or sharing logic between lintian-brush and debputy.
Minimal integration mode for Rules-Requires-Root One of the original motivators for starting debputy was to be able to get rid of fakeroot in our build process. While this is possible, debputy currently does not support most of the complex packaging features such as maintscripts and debconf. Unfortunately, the kind of packages that need fakeroot for static ownership tend to also require very complex packaging features. To bridge this gap, the new version of debputy supports a very minimal integration with dh via the dh-sequence-zz-debputy-rrr. This integration mode keeps the vast majority of debhelper sequence in place meaning most dh add-ons will continue to work with dh-sequence-zz-debputy-rrr. The sequence only replaces the following commands:
  • dh_fixperms
  • dh_gencontrol
  • dh_md5sums
  • dh_builddeb
The installations feature of the manifest will be disabled in this integration mode to avoid feature interactions with debhelper tools that expect debian/<pkg> to contain the materialized package. On a related note, the debputy migrate-from-dh command now supports a --migration-target option, so you can choose the desired level of integration without doing code changes. The command will attempt to auto-detect the desired integration from existing package features such as a build-dependency on a relevant dh sequence, so you do not have to remember this new option every time once the migration has started. :)

21 March 2024

Ian Jackson: How to use Rust on Debian (and Ubuntu, etc.)

tl;dr: Don t just apt install rustc cargo. Either do that and make sure to use only Rust libraries from your distro (with the tiresome config runes below); or, just use rustup. Don t do the obvious thing; it s never what you want Debian ships a Rust compiler, and a large number of Rust libraries. But if you just do things the obvious default way, with apt install rustc cargo, you will end up using Debian s compiler but upstream libraries, directly and uncurated from crates.io. This is not what you want. There are about two reasonable things to do, depending on your preferences. Q. Download and run whatever code from the internet? The key question is this: Are you comfortable downloading code, directly from hundreds of upstream Rust package maintainers, and running it ? That s what cargo does. It s one of the main things it s for. Debian s cargo behaves, in this respect, just like upstream s. Let me say that again: Debian s cargo promiscuously downloads code from crates.io just like upstream cargo. So if you use Debian s cargo in the most obvious way, you are still downloading and running all those random libraries. The only thing you re avoiding downloading is the Rust compiler itself, which is precisely the part that is most carefully maintained, and of least concern. Debian s cargo can even download from crates.io when you re building official Debian source packages written in Rust: if you run dpkg-buildpackage, the downloading is suppressed; but a plain cargo build will try to obtain and use dependencies from the upstream ecosystem. ( Happily , if you do this, it s quite likely to bail out early due to version mismatches, before actually downloading anything.) Option 1: WTF, no I don t want curl bash OK, but then you must limit yourself to libraries available within Debian. Each Debian release provides a curated set. It may or may not be sufficient for your needs. Many capable programs can be written using the packages in Debian. But any upstream Rust project that you encounter is likely to be a pain to get working, unless their maintainers specifically intend to support this. (This is fairly rare, and the Rust tooling doesn t make it easy.) To go with this plan, apt install rustc cargo and put this in your configuration, in $HOME/.cargo/config.toml:
[source.debian-packages]
directory = "/usr/share/cargo/registry"
[source.crates-io]
replace-with = "debian-packages"
This causes cargo to look in /usr/share for dependencies, rather than downloading them from crates.io. You must then install the librust-FOO-dev packages for each of your dependencies, with apt. This will allow you to write your own program in Rust, and build it using cargo build. Option 2: Biting the curl bash bullet If you want to build software that isn t specifically targeted at Debian s Rust you will probably need to use packages from crates.io, not from Debian. If you re doing to do that, there is little point not using rustup to get the latest compiler. rustup s install rune is alarming, but cargo will be doing exactly the same kind of thing, only worse (because it trusts many more people) and more hidden. So in this case: do run the curl bash install rune. Hopefully the Rust project you are trying to build have shipped a Cargo.lock; that contains hashes of all the dependencies that they last used and tested. If you run cargo build --locked, cargo will only use those versions, which are hopefully OK. And you can run cargo audit to see if there are any reported vulnerabilities or problems. But you ll have to bootstrap this with cargo install --locked cargo-audit; cargo-audit is from the RUSTSEC folks who do care about these kind of things, so hopefully running their code (and their dependencies) is fine. Note the --locked which is needed because cargo s default behaviour is wrong. Privilege separation This approach is rather alarming. For my personal use, I wrote a privsep tool which allows me to run all this upstream Rust code as a separate user. That tool is nailing-cargo. It s not particularly well productised, or tested, but it does work for at least one person besides me. You may wish to try it out, or consider alternative arrangements. Bug reports and patches welcome. OMG what a mess Indeed. There are large number of technical and social factors at play. cargo itself is deeply troubling, both in principle, and in detail. I often find myself severely disappointed with its maintainers decisions. In mitigation, much of the wider Rust upstream community does takes this kind of thing very seriously, and often makes good choices. RUSTSEC is one of the results. Debian s technical arrangements for Rust packaging are quite dysfunctional, too: IMO the scheme is based on fundamentally wrong design principles. But, the Debian Rust packaging team is dynamic, constantly working the update treadmills; and the team is generally welcoming and helpful. Sadly last time I explored the possibility, the Debian Rust Team didn t have the appetite for more fundamental changes to the workflow (including, for example, changes to dependency version handling). Significant improvements to upstream cargo s approach seem unlikely, too; we can only hope that eventually someone might manage to supplant it.
edited 2024-03-21 21:49 to add a cut tag


comment count unavailable comments

13 March 2024

Freexian Collaborators: Debian Contributions: Upcoming Improvements to Salsa CI, /usr-move, packaging simplemonitor, and more! (by Utkarsh Gupta)

Contributing to Debian is part of Freexian s mission. This article covers the latest achievements of Freexian and their collaborators. All of this is made possible by organizations subscribing to our Long Term Support contracts and consulting services.

/usr-move, by Helmut Grohne Much of the work was spent on handling interaction with time time64 transition and sending patches for mitigating fallout. The set of packages relevant to debootstrap is mostly converted and the patches for glibc and base-files have been refined due to feedback from the upload to Ubuntu noble. Beyond this, he sent patches for all remaining packages that cannot move their files with dh-sequence-movetousr and packages using dpkg-divert in ways that dumat would not recognize.

Upcoming improvements to Salsa CI, by Santiago Ruano Rinc n Last month, Santiago Ruano Rinc n started the work on integrating sbuild into the Salsa CI pipeline. Initially, Santiago used sbuild with the unshare chroot mode. However, after discussion with josch, jochensp and helmut (thanks to them!), it turns out that the unshare mode is not the most suitable for the pipeline, since the level of isolation it provides is not needed, and some test suites would fail (eg: krb5). Additionally, one of the requirements of the build job is the use of ccache, since it is needed by some C/C++ large projects to reduce the compilation time. In the preliminary work with unshare last month, it was not possible to make ccache to work. Finally, Santiago changed the chroot mode, and now has a couple of POC (cf: 1 and 2) that rely on the schroot and sudo, respectively. And the good news is that ccache is successfully used by sbuild with schroot! The image here comes from an example of building grep. At the end of the build, ccache -s shows the statistics of the cache that it used, and so a little more than half of the calls of that job were cacheable. The most important pieces are in place to finish the integration of sbuild into the pipeline. Other than that, Santiago also reviewed the very useful merge request !346, made by IOhannes zm lnig to autodetect the release from debian/changelog. As agreed with IOhannes, Santiago is preparing a merge request to include the release autodetection use case in the very own Salsa CI s CI.

Packaging simplemonitor, by Carles Pina i Estany Carles started using simplemonitor in 2017, opened a WNPP bug in 2022 and started packaging simplemonitor dependencies in October 2023. After packaging five direct and indirect dependencies, Carles finally uploaded simplemonitor to unstable in February. During the packaging of simplemonitor, Carles reported a few issues to upstream. Some of these were to make the simplemonitor package build and run tests reproducibly. A reproducibility issue was reprotest overriding the timezone, which broke simplemonitor s tests. There have been discussions on resolving this upstream in simplemonitor and in reprotest, too. Carles also started upgrading or improving some of simplemonitor s dependencies.

Miscellaneous contributions
  • Stefano Rivera spent some time doing admin on debian.social infrastructure. Including dealing with a spike of abuse on the Jitsi server.
  • Stefano started to prepare a new release of dh-python, including cleaning out a lot of old Python 2.x related code. Thanks to Niels Thykier (outside Freexian) for spear-heading this work.
  • DebConf 24 planning is beginning. Stefano discussed venues and finances with the local team and remotely supported a site-visit by Nattie (outside Freexian).
  • Also in the DebConf 24 context, Santiago took part in discussions and preparations related to the Content Team.
  • A JIT bug was reported against pypy3 in Debian Bookworm. Stefano bisected the upstream history to find the patch (it was already resolved upstream) and released an update to pypy3 in bookworm.
  • Enrico participated in /usr-merge discussions with Helmut.
  • Colin Watson backported a python-channels-redis fix to bookworm, rediscovered while working on debusine.
  • Colin dug into a cluster of celery build failures and tracked the hardest bit down to a Python 3.12 regression, now fixed in unstable. celery should be back in testing once the 64-bit time_t migration is out of the way.
  • Thorsten Alteholz uploaded a new upstream version of cpdb-libs. Unfortunately upstream changed the naming of their release tags, so updating the watch file was a bit demanding. Anyway this version 2.0 is a huge step towards introduction of the new Common Print Dialog Backends.
  • Helmut send patches for 48 cross build failures.
  • Helmut changed debvm to use mkfs.ext4 instead of genext2fs.
  • Helmut sent a debci MR for improving collector robustness.
  • In preparation for DebConf 25, Santiago worked on the Brest Bid.

25 February 2024

Jacob Adams: AAC and Debian

Currently, in a default installation of Debian with the GNOME desktop, Bluetooth headphones that require the AAC codec1 cannot be used. As the Debian wiki outlines, using the AAC codec over Bluetooth, while technically supported by PipeWire, is explicitly disabled in Debian at this time. This is because the fdk-aac library needed to enable this support is currently in the non-free component of the repository, meaning that PipeWire, which is in the main component, cannot depend on it.

How to Fix it Yourself If what you, like me, need is simply for Bluetooth Audio to work with AAC in Debian s default desktop environment2, then you ll need to rebuild the pipewire package to include the AAC codec. While the current version in Debian main has been built with AAC deliberately disabled, it is trivial to enable if you can install a version of the fdk-aac library. I preface this with the usual caveats when it comes to patent and licensing controversies. I am not a lawyer, building this package and/or using it could get you into legal trouble. These instructions have only been tested on an up-to-date copy of Debian 12.
  1. Install pipewire s build dependencies
    sudo apt install build-essential devscripts
    sudo apt build-dep pipewire
    
  2. Install libfdk-aac-dev
    sudo apt install libfdk-aac-dev
    
    If the above doesn t work you ll likely need to enable non-free and try again
    sudo sed -i 's/main/main non-free/g' /etc/apt/sources.list
    sudo apt update
    
    Alternatively, if you wish to ensure you are maximally license-compliant and patent un-infringing3, you can instead build fdk-aac-free which includes only those components of AAC that are known to be patent-free3. This is what should eventually end up in Debian to resolve this problem (see below).
    sudo apt install git-buildpackage
    mkdir fdk-aac-source
    cd fdk-aac-source
    git clone https://salsa.debian.org/multimedia-team/fdk-aac
    cd fdk-aac
    gbp buildpackage
    sudo dpkg -i ../libfdk-aac2_*deb ../libfdk-aac-dev_*deb
    
  3. Get the pipewire source code
    mkdir pipewire-source
    cd pipewire-source
    apt source pipewire
    
    This will create a bunch of files within the pipewire-source directory, but you ll only need the pipewire-<version> folder, this contains all the files you ll need to build the package, with all the debian-specific patches already applied. Note that you don t want to run the apt source command as root, as it will then create files that your regular user cannot edit.
  4. Fix the dependencies and build options To fix up the build scripts to use the fdk-aac library, you need to save the following as pipewire-source/aac.patch
    --- debian/control.orig
    +++ debian/control
    @@ -40,8 +40,8 @@
                 modemmanager-dev,
                 pkg-config,
                 python3-docutils,
    -               systemd [linux-any]
    -Build-Conflicts: libfdk-aac-dev
    +               systemd [linux-any],
    +               libfdk-aac-dev
     Standards-Version: 4.6.2
     Vcs-Browser: https://salsa.debian.org/utopia-team/pipewire
     Vcs-Git: https://salsa.debian.org/utopia-team/pipewire.git
    --- debian/rules.orig
    +++ debian/rules
    @@ -37,7 +37,7 @@
     		-Dauto_features=enabled \
     		-Davahi=enabled \
     		-Dbluez5-backend-native-mm=enabled \
    -		-Dbluez5-codec-aac=disabled \
    +		-Dbluez5-codec-aac=enabled \
     		-Dbluez5-codec-aptx=enabled \
     		-Dbluez5-codec-lc3=enabled \
     		-Dbluez5-codec-lc3plus=disabled \
    
    Then you ll need to run patch from within the pipewire-<version> folder created by apt source:
    patch -p0 < ../aac.patch
    
  5. Build pipewire
    cd pipewire-*
    debuild
    
    Note that you will likely see an error from debsign at the end of this process, this is harmless, you simply don t have a GPG key set up to sign your newly-built package4. Packages don t need to be signed to be installed, and debsign uses a somewhat non-standard signing process that dpkg does not check anyway.
  1. Install libspa-0.2-bluetooth
    sudo dpkg -i libspa-0.2-bluetooth_*.deb
    
  2. Restart PipeWire and/or Reboot
    sudo reboot
    
    Theoretically there s a set of services to restart here that would get pipewire to pick up the new library, probably just pipewire itself. But it s just as easy to restart and ensure everything is using the correct library.

Why This is a slightly unusual situation, as the fdk-aac library is licensed under what even the GNU project acknowledges is a free software license. However, this license explicitly informs the user that they need to acquire a patent license to use this software5:
3. NO PATENT LICENSE NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without limitation the patents of Fraunhofer, ARE GRANTED BY THIS SOFTWARE LICENSE. Fraunhofer provides no warranty of patent non-infringement with respect to this software. You may use this FDK AAC Codec software or modifications thereto only for purposes that are authorized by appropriate patent licenses.
To quote the GNU project:
Because of this, and because the license author is a known patent aggressor, we encourage you to be careful about using or redistributing software under this license: you should first consider whether the licensor might aim to lure you into patent infringement.
AAC is covered by a number of patents, which expire at some point in the 2030s6. As such the current version of the library is potentially legally dubious to ship with any other software, as it could be considered patent-infringing3.

Fedora s solution Since 2017, Fedora has included a modified version of the library as fdk-aac-free, see the announcement and the bugzilla bug requesting review. This version of the library includes only the AAC LC profile, which is believed to be entirely patent-free3. Based on this, there is an open bug report in Debian requesting that the fdk-aac package be moved to the main component and that the pipwire package be updated to build against it.

The Debian NEW queue To resolve these bugs, a version of fdk-aac-free has been uploaded to Debian by Jeremy Bicha. However, to make it into Debian proper, it must first pass through the ftpmaster s NEW queue. The current version of fdk-aac-free has been in the NEW queue since July 2023. Based on conversations in some of the bugs above, it s been there since at least 20227. I hope this helps anyone stuck with AAC to get their hardware working for them while we wait for the package to eventually make it through the NEW queue. Discuss on Hacker News
  1. Such as, for example, any Apple AirPods, which only support AAC AFAICT.
  2. Which, as of Debian 12 is GNOME 3 under Wayland with PipeWire.
  3. I m not a lawyer, I don t know what kinds of infringement might or might not be possible here, do your own research, etc. 2 3 4
  4. And if you DO have a key setup with debsign you almost certainly don t need these instructions.
  5. This was originally phrased as explicitly does not grant any patent rights. It was pointed out on Hacker News that this is not exactly what it says, as it also includes a specific note that you ll need to acquire your own patent license. I ve now quoted the relevant section of the license for clarity.
  6. Wikipedia claims the base patents expire in 2031, with the extensions expiring in 2038, but its source for these claims is some guy s spreadsheet in a forum. The same discussion also brings up Wikipedia s claim and casts some doubt on it, so I m not entirely sure what s correct here, but I didn t feel like doing a patent deep-dive today. If someone can provide a clear answer that would be much appreciated.
  7. According to Jeremy B cha: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1021370#17

24 February 2024

Niels Thykier: Language Server for Debian: Spellchecking

This is my third update on writing a language server for Debian packaging files, which aims at providing a better developer experience for Debian packagers. Lets go over what have done since the last report.
Semantic token support I have added support for what the Language Server Protocol (LSP) call semantic tokens. These are used to provide the editor insights into tokens of interest for users. Allegedly, this is what editors would use for syntax highlighting as well. Unfortunately, eglot (emacs) does not support semantic tokens, so I was not able to test this. There is a 3-year old PR for supporting with the last update being ~3 month basically saying "Please sign the Copyright Assignment". I pinged the GitHub issue in the hopes it will get unstuck. For good measure, I also checked if I could try it via neovim. Before installing, I read the neovim docs, which helpfully listed the features supported. Sadly, I did not spot semantic tokens among those and parked from there. That was a bit of a bummer, but I left the feature in for now. If you have an LSP capable editor that supports semantic tokens, let me know how it works for you! :)
Spellchecking Finally, I implemented something Otto was missing! :) This stared with Paul Wise reminding me that there were Python binding for the hunspell spellchecker. This enabled me to get started with a quick prototype that spellchecked the Description fields in debian/control. I also added spellchecking of comments while I was add it. The spellchecker runs with the standard en_US dictionary from hunspell-en-us, which does not have a lot of technical terms in it. Much less any of the Debian specific slang. I spend considerable time providing a "built-in" wordlist for technical and Debian specific slang to overcome this. I also made a "wordlist" for known Debian people that the spellchecker did not recognise. Said wordlist is fairly short as a proof of concept, and I fully expect it to be community maintained if the language server becomes a success. My second problem was performance. As I had suspected that spellchecking was not the fastest thing in the world. Therefore, I added a very small language server for the debian/changelog, which only supports spellchecking the textual part. Even for a small changelog of a 1000 lines, the spellchecking takes about 5 seconds, which confirmed my suspicion. With every change you do, the existing diagnostics hangs around for 5 seconds before being updated. Notably, in emacs, it seems that diagnostics gets translated into an absolute character offset, so all diagnostics after the change gets misplaced for every character you type. Now, there is little I could do to speed up hunspell. But I can, as always, cheat. The way diagnostics work in the LSP is that the server listens to a set of notifications like "document opened" or "document changed". In a response to that, the LSP can start its diagnostics scanning of the document and eventually publish all the diagnostics to the editor. The spec is quite clear that the server owns the diagnostics and the diagnostics are sent as a "notification" (that is, fire-and-forgot). Accordingly, there is nothing that prevents the server from publishing diagnostics multiple times for a single trigger. The only requirement is that the server publishes the accumulated diagnostics in every publish (that is, no delta updating). Leveraging this, I had the language server for debian/changelog scan the document and publish once for approximately every 25 typos (diagnostics) spotted. This means you quickly get your first result and that clears the obsolete diagnostics. Thereafter, you get frequent updates to the remainder of the document if you do not perform any further changes. That is, up to a predefined max of typos, so we do not overload the client for longer changelogs. If you do any changes, it resets and starts over. The only bit missing was dealing with concurrency. By default, a pygls language server is single threaded. It is not great if the language server hangs for 5 seconds everytime you type anything. Fortunately, pygls has builtin support for asyncio and threaded handlers. For now, I did an async handler that await after each line and setup some manual detection to stop an obsolete diagnostics run. This means the server will fairly quickly abandon an obsolete run. Also, as a side-effect of working on the spellchecking, I fixed multiple typos in the changelog of debputy. :)
Follow up on the "What next?" from my previous update In my previous update, I mentioned I had to finish up my python-debian changes to support getting the location of a token in a deb822 file. That was done, the MR is now filed, and is pending review. Hopefully, it will be merged and uploaded soon. :) I also submitted my proposal for a different way of handling relationship substvars to debian-devel. So far, it seems to have received only positive feedback. I hope it stays that way and we will have this feature soon. Guillem proposed to move some of this into dpkg, which might delay my plans a bit. However, it might be for the better in the long run, so I will wait a bit to see what happens on that front. :) As noted above, I managed to add debian/changelog as a support format for the language server. Even if it only does spellchecking and trimming of trailing newlines on save, it technically is a new format and therefore cross that item off my list. :D Unfortunately, I did not manage to write a linter variant that does not involve using an LSP-capable editor. So that is still pending. Instead, I submitted an MR against elpa-dpkg-dev-el to have it recognize all the fields that the debian/control LSP knows about at this time to offset the lack of semantic token support in eglot.
From here... My sprinting on this topic will soon come to an end, so I have to a bit more careful now with what tasks I open! I think I will narrow my focus to providing a batch linting interface. Ideally, with an auto-fix for some of the more mechanical issues, where this is little doubt about the answer. Additionally, I think the spellchecking will need a bit more maturing. My current code still trips on naming patterns that are "clearly" verbatim or code references like things written in CamelCase or SCREAMING_SNAKE_CASE. That gets annoying really quickly. It also trips on a lot of commands like dpkg-gencontrol, but that is harder to fix since it could have been a real word. I think those will have to be fixed people using quotes around the commands. Maybe the most popular ones will end up in the wordlist. Beyond that, I will play it by ear if I have any time left. :)

20 February 2024

Niels Thykier: Language Server (LSP) support for debian/control

About a month ago, Otto Kek l inen asked for editor extensions for debian related files on the debian-devel mailing list. In that thread, I concluded that what we were missing was a "Language Server" (LSP) for our packaging files. Last week, I started a prototype for such a LSP for the debian/control file as a starting point based on the pygls library. The initial prototype worked and I could do very basic diagnostics plus completion suggestion for field names.
Current features I got 4 basic features implemented, though I have only been able to test two of them in emacs.
  • Diagnostics or linting of basic issues.
  • Completion suggestions for all known field names that I could think of and values for some fields.
  • Folding ranges (untested). This feature enables the editor to "fold" multiple lines. It is often used with multi-line comments and that is the feature currently supported.
  • On save, trim trailing whitespace at the end of lines (untested). Might not be registered correctly on the server end.
Despite its very limited feature set, I feel editing debian/control in emacs is now a much more pleasant experience. Coming back to the features that Otto requested, the above covers a grand total of zero. Sorry, Otto. It is not you, it is me.
Completion suggestions For completion, all known fields are completed. Place the cursor at the start of the line or in a partially written out field name and trigger the completion in your editor. In my case, I can type R-R-R and trigger the completion and the editor will automatically replace it with Rules-Requires-Root as the only applicable match. Your milage may vary since I delegate most of the filtering to the editor, meaning the editor has the final say about whether your input matches anything. The only filtering done on the server side is that the server prunes out fields already used in the paragraph, so you are not presented with the option to repeat an already used field, which would be an error. Admittedly, not an error the language server detects at the moment, but other tools will. When completing field, if the field only has one non-default value such as Essential which can be either no (the default, but you should not use it) or yes, then the completion suggestion will complete the field along with its value. This is mostly only applicable for "yes/no" fields such as Essential and Protected. But it does also trigger for Package-Type at the moment. As for completing values, here the language server can complete the value for simple fields such as "yes/no" fields, Multi-Arch, Package-Type and Priority. I intend to add support for Section as well - maybe also Architecture.
Diagnostics On the diagnostic front, I have added multiple diagnostics:
  • An error marker for syntax errors.
  • An error marker for missing a mandatory field like Package or Architecture. This also includes Standards-Version, which is admittedly mandatory by policy rather than tooling falling part.
  • An error marker for adding Multi-Arch: same to an Architecture: all package.
  • Error marker for providing an unknown value to a field with a set of known values. As an example, writing foo in Multi-Arch would trigger this one.
  • Warning marker for using deprecated fields such as DM-Upload-Allowed, or when setting a field to its default value for fields like Essential. The latter rule only applies to selected fields and notably Multi-Arch: no does not trigger a warning.
  • Info level marker if a field like Priority duplicates the value of the Source paragraph.
Notable omission at this time:
  • No errors are raised if a field does not have a value.
  • No errors are raised if a field is duplicated inside a paragraph.
  • No errors are used if a field is used in the wrong paragraph.
  • No spellchecking of the Description field.
  • No understanding that Foo and X[CBS]-Foo are related. As an example, XC-Package-Type is completely ignored despite being the old name for Package-Type.
  • Quick fixes to solve these problems... :)
Trying it out If you want to try, it is sadly a bit more involved due to things not being uploaded or merged yet. Also, be advised that I will regularly rebase my git branches as I revise the code. The setup:
  • Build and install the deb of the main branch of pygls from https://salsa.debian.org/debian/pygls The package is in NEW and hopefully this step will soon just be a regular apt install.
  • Build and install the deb of the rts-locatable branch of my python-debian fork from https://salsa.debian.org/nthykier/python-debian There is a draft MR of it as well on the main repo.
  • Build and install the deb of the lsp-support branch of debputy from https://salsa.debian.org/debian/debputy
  • Configure your editor to run debputy lsp debian/control as the language server for debian/control. This is depends on your editor. I figured out how to do it for emacs (see below). I also found a guide for neovim at https://neovim.io/doc/user/lsp. Note that debputy can be run from any directory here. The debian/control is a reference to the file format and not a concrete file in this case.
Obviously, the setup should get easier over time. The first three bullet points should eventually get resolved by merges and upload meaning you end up with an apt install command instead of them. For the editor part, I would obviously love it if we can add snippets for editors to make the automatically pick up the language server when the relevant file is installed.
Using the debputy LSP in emacs The guide I found so far relies on eglot. The guide below assumes you have the elpa-dpkg-dev-el package installed for the debian-control-mode. Though it should be a trivially matter to replace debian-control-mode with a different mode if you use a different mode for your debian/control file. In your emacs init file (such as ~/.emacs or ~/.emacs.d/init.el), you add the follow blob.
(with-eval-after-load 'eglot
    (add-to-list 'eglot-server-programs
        '(debian-control-mode . ("debputy" "lsp" "debian/control"))))
Once you open the debian/control file in emacs, you can type M-x eglot to activate the language server. Not sure why that manual step is needed and if someone knows how to automate it such that eglot activates automatically on opening debian/control, please let me know. For testing completions, I often have to manually activate them (with C-M-i or M-x complete-symbol). Though, it is a bit unclear to me whether this is an emacs setting that I have not toggled or something I need to do on the language server side.
From here As next steps, I will probably look into fixing some of the "known missing" items under diagnostics. The quick fix would be a considerable improvement to assisting users. In the not so distant future, I will probably start to look at supporting other files such as debian/changelog or look into supporting configuration, so I can cover formatting features like wrap-and-sort. I am also very much open to how we can provide integrations for this feature into editors by default. I will probably create a separate binary package for specifically this feature that pulls all relevant dependencies that would be able to provide editor integrations as well.

12 February 2024

Emanuele Rocca: Enabling Kernel Settings in Debian

This time it s about enabling new kernel config options in the official Debian kernel packages. A few dependencies are needed to run the various scripts used by the Debian kernel folks, as well as to build the kernel itself:
apt install git gpg python3-debian python3-dacite
apt build-dep linux
With that in place, fetch the linux and kernel-team repos:
git clone --depth 1 https://salsa.debian.org/kernel-team/linux
git clone --depth 1 https://salsa.debian.org/kernel-team/kernel-team
So far you ve only got the Debian-specific bits. Fetch the actual kernel sources now. In the likely case that you re building a stable kernel, run the following from within the linux directory:
debian/bin/genorig.py https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
Use the torvalds repo if you re building an RC version instead:
debian/bin/genorig.py https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Now generate the upstream tarball as well as debian/control. The first command will take a bit, and the second command will fail: but that s success just as the output says.
debian/rules orig
debian/rules debian/control
Now generate patched sources with:
debian/rules source
Time to edit the Kconfig and enable/disable whatever setting you wanted to change. Take a look around the files under debian/config/ to see where your changes should go. If it s a setting shared among multiple architectures that may be debian/config/config. For x86-specific things, the file is debian/config/amd64/config. On aarch64 debian/config/arm64/config. If in doubt, you could try asking #debian-kernel on IRC.
It may look like you need to figure out where exactly in the file the setting should be placed. That is not the case. There s a helpful script fixing things up for you:
../kernel-team/utils/kconfigeditor2/process.py .
The above will fail if you forgot to run debian/rules source. The debian/build/source_rt/Kconfig file is needed by the script:
Traceback (most recent call last):
  File "/tmp/linux/../kernel-team/utils/kconfigeditor2/process.py", line 19, in __init__
    menu = fs_menu[featureset or 'none']
           ~~~~~~~^^^^^^^^^^^^^^^^^^^^^^
KeyError: 'rt'
During handling of the above exception, another exception occurred:
[...]
FileNotFoundError: [Errno 2] No such file or directory: './debian/build/source_rt/Kconfig'
If that happens, run:
debian/rules source
Now process.py should work fine and fix your config file.
Excellent, now the config is updated and we re ready to build the kernel. Off we go:
export MAKEFLAGS=-j$(nproc)
export DEB_BUILD_PROFILES='pkg.linux.nokerneldbg pkg.linux.nokerneldbginfo pkg.linux.notools nodoc'
dpkg-buildpackage -b -nc -uc

28 January 2024

Niels Thykier: Annotating the Debian packaging directory

In my previous blog post Providing online reference documentation for debputy, I made a point about how debhelper documentation was suboptimal on account of being static rather than online. The thing is that debhelper is not alone in this problem space, even if it is a major contributor to the number of packaging files you have to to know about. If we look at the "competition" here such as Fedora and Arch Linux, they tend to only have one packaging file. While most Debian people will tell you a long list of cons about having one packaging file (such a Fedora's spec file being 3+ domain specific languages "mashed" into one file), one major advantage is that there is only "the one packaging file". You only need to remember where to find the documentation for one file, which is great when you are running on wetware with limited storage capacity. Which means as a newbie, you can dedicate less mental resources to tracking multiple files and how they interact and more effort understanding the "one file" at hand. I started by asking myself how can we in Debian make the packaging stack more accessible to newcomers? Spoiler alert, I dug myself into rabbit hole and ended up somewhere else than where I thought I was going. I started by wanting to scan the debian directory and annotate all files that I could with documentation links. The logic was that if debputy could do that for you, then you could spend more mental effort elsewhere. So I combined debputy's packager provided files detection with a static list of files and I quickly had a good starting point for debputy-based packages.
Adding (non-static) dpkg and debhelper files to the mix Now, I could have closed the topic here and said "Look, I did debputy files plus couple of super common files". But I decided to take it a bit further. I added support for handling some dpkg files like packager provided files (such as debian/substvars and debian/symbols). But even then, we all know that debhelper is the big hurdle and a major part of the omission... In another previous blog post (A new Debian package helper: debputy), I made a point about how debputy could list all auxiliary files while debhelper could not. This was exactly the kind of feature that I would need for this feature, if this feature was to cover debhelper. Now, I also remarked in that blog post that I was not willing to maintain such a list. Also, I may have ranted about static documentation being unhelpful for debhelper as it excludes third-party provided tooling. Fortunately, a recent update to dh_assistant had provided some basic plumbing for loading dh sequences. This meant that getting a list of all relevant commands for a source package was a lot easier than it used to be. Once you have a list of commands, it would be possible to check all of them for dh's NOOP PROMISE hints. In these hints, a command can assert it does nothing if a given pkgfile is not present. This lead to the new dh_assistant list-guessed-dh-config-files command that will list all declared pkgfiles and which helpers listed them. With this combined feature set in place, debputy could call dh_assistant to get a list of pkgfiles, pretend they were packager provided files and annotate those along with manpage for the relevant debhelper command. The exciting thing about letting debpputy resolve the pkgfiles is that debputy will resolve "named" files automatically (debhelper tools will only do so when --name is passed), so it is much more likely to detect named pkgfiles correctly too. Side note: I am going to ignore the elephant in the room for now, which is dh_installsystemd and its package@.service files and the wide-spread use of debian/foo.service where there is no package called foo. For the latter case, the "proper" name would be debian/pkg.foo.service. With the new dh_assistant feature done and added to debputy, debputy could now detect the ubiquitous debian/install file. Excellent. But less great was that the very common debian/docs file was not. Turns out that dh_installdocs cannot be skipped by dh, so it cannot have NOOP PROMISE hints. Meh... Well, dh_assistant could learn about a new INTROSPECTABLE marker in addition to the NOOP PROMISE and then I could sprinkle that into a few commands. Indeed that worked and meant that debian/postinst (etc.) are now also detectable. At this point, debputy would be able to identify a wide range of debhelper related configuration files in debian/ and at least associate each of them with one or more commands. Nice, surely, this would be a good place to stop, right...?
Adding more metadata to the files The debhelper detected files only had a command name and manpage URI to that command. It would be nice if we could contextualize this a bit more. Like is this file installed into the package as is like debian/pam or is it a file list to be processed like debian/install. To make this distinction, I could add the most common debhelper file types to my static list and then merge the result together. Except, I do not want to maintain a full list in debputy. Fortunately, debputy has a quite extensible plugin infrastructure, so added a new plugin feature to provide this kind of detail and now I can outsource the problem! I split my definitions into two and placed the generic ones in the debputy-documentation plugin and moved the debhelper related ones to debhelper-documentation. Additionally, third-party dh addons could provide their own debputy plugin to add context to their configuration files. So, this gave birth file categories and configuration features, which described each file on different fronts. As an example, debian/gbp.conf could be tagged as a maint-config to signal that it is not directly related to the package build but more of a tool or style preference file. On the other hand, debian/install and debian/debputy.manifest would both be tagged as a pkg-helper-config. Files like debian/pam were tagged as ppf-file for packager provided file and so on. I mentioned configuration features above and those were added because, I have had a beef with debhelper's "standard" configuration file format as read by filearray and filedoublearray. They are often considered simple to understand, but it is hard to know how a tool will actually read the file. As an example, consider the following:
  • Will the debhelper use filearray, filedoublearray or none of them to read the file? This topic has about 2 bits of entropy.
  • Will the config file be executed if it is marked executable assuming you are using the right compat level? If it is executable, does dh-exec allow renaming for this file? This topic adds 1 or 2 bit of entropy depending on the context.
  • Will the config file be subject to glob expansions? This topic sounds like a boolean but is a complicated mess. The globs can be handled either by debhelper as it parses the file for you. In this case, the globs are applied to every token. However, this is not what dh_install does. Here the last token on each line is supposed to be a directory and therefore not subject to globs. Therefore, dh_install does the globbing itself afterwards but only on part of the tokens. So that is about 2 bits of entropy more. Actually, it gets worse...
    • If the file is executed, debhelper will refuse to expand globs in the output of the command, which was a deliberate design choice by the original debhelper maintainer took when he introduced the feature in debhelper/8.9.12. Except, dh_install feature interacts with the design choice and does enable glob expansion in the tool output, because it does so manually after its filedoublearray call.
So these "simple" files have way too many combinations of how they can be interpreted. I figured it would be helpful if debputy could highlight these difference, so I added support for those as well. Accordingly, debian/install is tagged with multiple tags including dh-executable-config and dh-glob-after-execute. Then, I added a datatable of these tags, so it would be easy for people to look up what they meant. Ok, this seems like a closed deal, right...?
Context, context, context However, the dh-executable-config tag among other are only applicable in compat 9 or later. It does not seem newbie friendly if you are told that this feature exist, but then have to read in the extended description that that it actually does not apply to your package. This problem seems fixable. Thanks to dh_assistant, it is easy to figure out which compat level the package is using. Then tweak some metadata to enable per compat level rules. With that tags like dh-executable-config only appears for packages using compat 9 or later. Also, debputy should be able to tell you where packager provided files like debian/pam are installed. We already have the logic for packager provided files that debputy supports and I am already using debputy engine for detecting the files. If only the plugin provided metadata gave me the install pattern, debputy would be able tell you where this file goes in the package. Indeed, a bit of tweaking later and setting install-pattern to usr/lib/pam.d/ name , debputy presented me with the correct install-path with the package name placing the name placeholder. Now, I have been using debian/pam as an example, because debian/pam is installed into usr/lib/pam.d in compat 14. But in earlier compat levels, it was installed into etc/pam.d. Well, I already had an infrastructure for doing compat file tags. Off we go to add install-pattern to the complat level infrastructure and now changing the compat level would change the path. Great. (Bug warning: The value is off-by-one in the current version of debhelper. This is fixed in git) Also, while we are in this install-pattern business, a number of debhelper config files causes files to be installed into a fixed directory. Like debian/docs which causes file to be installed into /usr/share/docs/ package . Surely, we can expand that as well and provide that bit of context too... and done. (Bug warning: The code currently does not account for the main documentation package context) It is rather common pattern for people to do debian/foo.in files, because they want to custom generation of debian/foo. Which means if you have debian/foo you get "Oh, let me tell you about debian/foo ". Then you rename it to debian/foo.in and the result is "debian/foo.in is a total mystery to me!". That is suboptimal, so lets detect those as well as if they were the original file but add a tag saying that they are a generate template and which file we suspect it generates. Finally, if you use debputy, almost all of the standard debhelper commands are removed from the sequence, since debputy replaces them. It would be weird if these commands still contributed configuration files when they are not actually going to be invoked. This mostly happened naturally due to the way the underlying dh_assistant command works. However, any file mentioned by the debhelper-documentation plugin would still appear unfortunately. So off I went to filter the list of known configuration files against which dh_ commands that dh_assistant thought would be used for this package.
Wrapping it up I was several layers into this and had to dig myself out. I have ended up with a lot of data and metadata. But it was quite difficult for me to arrange the output in a user friendly manner. However, all this data did seem like it would be useful any tool that wants to understand more about the package. So to get out of the rabbit hole, I for now wrapped all of this into JSON and now we have a debputy tool-support annotate-debian-directory command that might be useful for other tools. To try it out, you can try the following demo: In another day, I will figure out how to structure this output so it is useful for non-machine consumers. Suggestions are welcome. :)
Limitations of the approach As a closing remark, I should probably remind people that this feature relies heavily on declarative features. These include:
  • When determining which commands are relevant, using Build-Depends: dh-sequence-foo is much more reliable than configuring it via the Turing complete configuration we call debian/rules.
  • When debhelper commands use NOOP promise hints, dh_assistant can "see" the config files listed those hints, meaning the file will at least be detected. For new introspectable hint and the debputy plugin, it is probably better to wait until the dust settles a bit before adding any of those.
You can help yourself and others to better results by using the declarative way rather than using debian/rules, which is the bane of all introspection!

3 January 2024

John Goerzen: Live Migrating from Raspberry Pi OS bullseye to Debian bookworm

I ve been getting annoyed with Raspberry Pi OS (Raspbian) for years now. It s a fork of Debian, but manages to omit some of the most useful things. So I ve decided to migrate all of my Pis to run pure Debian. These are my reasons:
  1. Raspberry Pi OS has, for years now, specified that there is no upgrade path. That is, to get to a newer major release, it s a reinstall. While I have sometimes worked around this, for a device that is frequently installed in hard-to-reach locations, this is even more important than usual. It s common for me to upgrade machines for a decade or more across Debian releases and there s no reason that it should be so much more difficult with Raspbian.
  2. As I noted in Consider Security First, the security situation for Raspberry Pi OS isn t as good as it is with Debian.
  3. Raspbian lags behind Debian often times by 6 months or more for major releases, and days or weeks for bug fixes and security patches.
  4. Raspbian has no direct backports support, though Raspberry Pi 3 and above can use Debian s backports (per my instructions as Installing Debian Backports on Raspberry Pi)
  5. Raspbian uses a custom kernel without initramfs support
It turns out it is actually possible to do an in-place migration from Raspberry Pi OS bullseye to Debian bookworm. Here I will describe how. Even if you don t have a Raspberry Pi, this might still be instructive on how Raspbian and Debian packages work.

WARNINGS Before continuing, back up your system. This process isn t for the neophyte and it is entirely possible to mess up your boot device to the point that you have to do a fresh install to get your Pi to boot. This isn t a supported process at all.

Architecture Confusion Debian has three ARM-based architectures:
  • armel, for the lowest-end 32-bit ARM devices without hardware floating point support
  • armhf, for the higher-end 32-bit ARM devices with hardware float (hence hf )
  • arm64, for 64-bit ARM devices (which all have hardware float)
Although the Raspberry Pi 0 and 1 do support hardware float, they lack support for other CPU features that Debian s armhf architecture assumes. Therefore, the Raspberry Pi 0 and 1 could only run Debian s armel architecture. Raspberry Pi 3 and above are capable of running 64-bit, and can run both armhf and arm64. Prior to the release of the Raspberry Pi 5 / Raspbian bookworm, Raspbian only shipped the armhf architecture. Well, it was an architecture they called armhf, but it was different from Debian s armhf in that everything was recompiled to work with the more limited set of features on the earlier Raspberry Pi boards. It was really somewhere between Debian s armel and armhf archs. You could run Debian armel on those, but it would run more slowly, due to doing floating point calculations without hardware support. Debian s raspi FAQ goes into this a bit. What I am going to describe here is going from Raspbian armhf to Debian armhf with a 64-bit kernel. Therefore, it will only work with Raspberry Pi 3 and above. It may theoretically be possible to take a Raspberry Pi 2 to Debian armhf with a 32-bit kernel, but I haven t tried this and it may be more difficult. I have seen conflicting information on whether armhf really works on a Pi 2. (If you do try it on a Pi 2, ignore everything about arm64 and 64-bit kernels below, and just go with the linux-image-armmp-lpae kernel per the ARMMP page) There is another wrinkle: Debian doesn t support running 32-bit ARM kernels on 64-bit ARM CPUs, though it does support running a 32-bit userland on them. So we will wind up with a system with kernel packages from arm64 and everything else from armhf. This is a perfectly valid configuration as the arm64 like x86_64 is multiarch (that is, the CPU can natively execute both the 32-bit and 64-bit instructions). (It is theoretically possible to crossgrade a system from 32-bit to 64-bit userland, but that felt like a rather heavy lift for dubious benefit on a Pi; nevertheless, if you want to make this process even more complicated, refer to the CrossGrading page.)

Prerequisites and Limitations In addition to the need for a Raspberry Pi 3 or above in order for this to work, there are a few other things to mention. If you are using the GPIO features of the Pi, I don t know if those work with Debian. I think Raspberry Pi OS modified the desktop environment more than other components. All of my Pis are headless, so I don t know if this process will work if you use a desktop environment. I am assuming you are booting from a MicroSD card as is typical in the Raspberry Pi world. The Pi s firmware looks for a FAT partition (MBR type 0x0c) and looks within it for boot information. Depending on how long ago you first installed an OS on your Pi, your /boot may be too small for Debian. Use df -h /boot to see how big it is. I recommend 200MB at minimum. If your /boot is smaller than that, stop now (or use some other system to shrink your root filesystem and rearrange your partitions; I ve done this, but it s outside the scope of this article.) You need to have stable power. Once you begin this process, your pi will mostly be left in a non-bootable state until you finish. (You did make a backup, right?)

Basic idea The basic idea here is that since bookworm has almost entirely newer packages then bullseye, we can just switch over to it and let the Debian packages replace the Raspbian ones as they are upgraded. Well, it s not quite that easy, but that s the main idea.

Preparation First, make a backup. Even an image of your MicroSD card might be nice. OK, I think I ve said that enough now. It would be a good idea to have a HDMI cable (with the appropriate size of connector for your particular Pi board) and a HDMI display handy so you can troubleshoot any bootup issues with a console.

Preparation: access The Raspberry Pi OS by default sets up a user named pi that can use sudo to gain root without a password. I think this is an insecure practice, but assuming you haven t changed it, you will need to ensure it still works once you move to Debian. Raspberry Pi OS had a patch in their sudo package to enable it, and that will be removed when Debian s sudo package is installed. So, put this in /etc/sudoers.d/010_picompat:
pi ALL=(ALL) NOPASSWD: ALL
Also, there may be no password set for the root account. It would be a good idea to set one; it makes it easier to log in at the console. Use the passwd command as root to do so.

Preparation: bluetooth Debian doesn t correctly identify the Bluetooth hardware address. You can save it off to a file by running hcitool dev > /root/bluetooth-from-raspbian.txt. I don t use Bluetooth, but this should let you develop a script to bring it up properly.

Preparation: Debian archive keyring You will next need to install Debian s archive keyring so that apt can authenticate packages from Debian. Go to the bookworm download page for debian-archive-keyring and copy the URL for one of the files, then download it on the pi. For instance:
wget http://http.us.debian.org/debian/pool/main/d/debian-archive-keyring/debian-archive-keyring_2023.3+deb12u1_all.deb
Use sha256sum to verify the checksum of the downloaded file, comparing it to the package page on the Debian site. Now, you ll install it with:
dpkg -i debian-archive-keyring_2023.3+deb12u1_all.deb

Package first steps From here on, we are making modifications to the system that can leave it in a non-bootable state. Examine /etc/apt/sources.list and all the files in /etc/apt/sources.list.d. Most likely you will want to delete or comment out all lines in all files there. Replace them with something like:
deb http://deb.debian.org/debian/ bookworm main non-free-firmware contrib non-free
deb http://security.debian.org/debian-security bookworm-security main non-free-firmware contrib non-free
deb https://deb.debian.org/debian bookworm-backports main non-free-firmware contrib non-free
(you might leave off contrib and non-free depending on your needs) Now, we re going to tell it that we ll support arm64 packages:
dpkg --add-architecture arm64
And finally, download the bookworm package lists:
apt-get update
If there are any errors from that command, fix them and don t proceed until you have a clean run of apt-get update.

Moving /boot to /boot/firmware The boot FAT partition I mentioned above is mounted at /boot by Raspberry Pi OS, but Debian s scripts assume it will be at /boot/firmware. We need to fix this. First:
umount /boot
mkdir /boot/firmware
Now, edit fstab and change the reference to /boot to be to /boot/firmware. Now:
mount -v /boot/firmware
cd /boot/firmware
mv -vi * ..
This mounts the filesystem at the new location, and moves all its contents back to where apt believes it should be. Debian s packages will populate /boot/firmware later.

Installing the first packages Now we start by installing the first of the needed packages. Eventually we will wind up with roughly the same set Debian uses.
apt-get install linux-image-arm64
apt-get install firmware-brcm80211=20230210-5
apt-get install raspi-firmware
If you get errors relating to firmware-brcm80211 from any commands, run that install firmware-brcm80211 command and then proceed. There are a few packages that Raspbian marked as newer than the version in bookworm (whether or not they really are), and that s one of them.

Configuring the bootloader We need to configure a few things in /etc/default/raspi-firmware before proceeding. Edit that file. First, uncomment (or add) a line like this:
KERNEL_ARCH="arm64"
Next, in /boot/cmdline.txt you can find your old Raspbian boot command line. It will say something like:
root=PARTUUID=...
Save off the bit starting with PARTUUID. Back in /etc/default/raspi-firmware, set a line like this:
ROOTPART=PARTUUID=abcdef00
(substituting your real value for abcdef00). This is necessary because the microSD card device name often changes from /dev/mmcblk0 to /dev/mmcblk1 when switching to Debian s kernel. raspi-firmware will encode the current device name in /boot/firmware/cmdline.txt by default, which will be wrong once you boot into Debian s kernel. The PARTUUID approach lets it work regardless of the device name.

Purging the Raspbian kernel Run:
dpkg --purge raspberrypi-kernel

Upgrading the system At this point, we are going to run the procedure beginning at section 4.4.3 of the Debian release notes. Generally, you will do:
apt-get -u upgrade
apt full-upgrade
Fix any errors at each step before proceeding to the next. Now, to remove some cruft, run:
apt-get --purge autoremove
Inspect the list to make sure nothing important isn t going to be removed.

Removing Raspbian cruft You can list some of the cruft with:
apt list '~o'
And remove it with:
apt purge '~o'
I also don t run Bluetooth, and it seemed to sometimes hang on boot becuase I didn t bother to fix it, so I did:
apt-get --purge remove bluez

Installing some packages This makes sure some basic Debian infrastructure is available:
apt-get install wpasupplicant parted dosfstools wireless-tools iw alsa-tools
apt-get --purge autoremove

Installing firmware Now run:
apt-get install firmware-linux

Resolving firmware package version issues If it gives an error about the installed version of a package, you may need to force it to the bookworm version. For me, this often happened with firmware-atheros, firmware-libertas, and firmware-realtek. Here s how to resolve it, with firmware-realtek as an example:
  1. Go to https://packages.debian.org/PACKAGENAME for instance, https://packages.debian.org/firmware-realtek. Note the version number in bookworm in this case, 20230210-5.
  2. Now, you will force the installation of that package at that version:
    apt-get install firmware-realtek=20230210-5
    
  3. Repeat with every conflicting package until done.
  4. Rerun apt-get install firmware-linux and make sure it runs cleanly.
Also, in the end you should be able to:
apt-get install firmware-atheros firmware-libertas firmware-realtek firmware-linux

Dealing with other Raspbian packages The Debian release notes discuss removing non-Debian packages. There will still be a few of those. Run:
apt list '?narrow(?installed, ?not(?origin(Debian)))'
Deal with them; mostly you will need to force the installation of a bookworm version using the procedure in the section Resolving firmware package version issues above (even if it s not for a firmware package). For non-firmware packages, you might possibly want to add --mark-auto to your apt-get install command line to allow the package to be autoremoved later if the things depending on it go away. If you aren t going to use Bluetooth, I recommend apt-get --purge remove bluez as well. Sometimes it can hang at boot if you don t fix it up as described above.

Set up networking We ll be switching to the Debian method of networking, so we ll create some files in /etc/network/interfaces.d. First, eth0 should look like this:
allow-hotplug eth0
iface eth0 inet dhcp
iface eth0 inet6 auto
And wlan0 should look like this:
allow-hotplug wlan0
iface wlan0 inet dhcp
    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
Raspbian is inconsistent about using eth0/wlan0 or renamed interface. Run ifconfig or ip addr. If you see a long-named interface such as enx<something> or wlp<something>, copy the eth0 file to the one named after the enx interface, or the wlan0 file to the one named after the wlp interface, and edit the internal references to eth0/wlan0 in this new file to name the long interface name. If using wifi, verify that your SSIDs and passwords are in /etc/wpa_supplicant/wpa_supplicant.conf. It should have lines like:
network= 
   ssid="NetworkName"
   psk="passwordHere"
 
(This is where Raspberry Pi OS put them).

Deal with DHCP Raspberry Pi OS used dhcpcd, whereas bookworm normally uses isc-dhcp-client. Verify the system is in the correct state:
apt-get install isc-dhcp-client
apt-get --purge remove dhcpcd dhcpcd-base dhcpcd5 dhcpcd-dbus

Set up LEDs To set up the LEDs to trigger on MicroSD activity as they did with Raspbian, follow the Debian instructions. Run apt-get install sysfsutils. Then put this in a file at /etc/sysfs.d/local-raspi-leds.conf:
class/leds/ACT/brightness = 1
class/leds/ACT/trigger = mmc1

Prepare for boot To make sure all the /boot/firmware files are updated, run update-initramfs -u. Verify that root in /boot/firmware/cmdline.txt references the PARTUUID as appropriate. Verify that /boot/firmware/config.txt contains the lines arm_64bit=1 and upstream_kernel=1. If not, go back to the section on modifying /etc/default/raspi-firmware and fix it up.

The moment arrives Cross your fingers and try rebooting into your Debian system:
reboot
For some reason, I found that the first boot into Debian seems to hang for 30-60 seconds during bootstrap. I m not sure why; don t panic if that happens. It may be necessary to power cycle the Pi for this boot.

Troubleshooting If things don t work out, hook up the Pi to a HDMI display and see what s up. If I anticipated a particular problem, I would have documented it here (a lot of the things I documented here are because I ran into them!) So I can t give specific advice other than to watch boot messages on the console. If you don t even get kernel messages going, then there is some problem with your partition table or /boot/firmware FAT partition. Otherwise, you ve at least got the kernel going and can troubleshoot like usual from there.

Jacob Adams: Fixing My Shell

For an embarassingly long time, my shell has unnecessarily tried to initialize a console font in every kind of interactive terminal. This leaves the following error message in my terminal:
Couldn't get a file descriptor referring to the console.
It even shows up twice when running tmux! Clearly I ve done something horrible to my configuration, and now I ve got to clean it up.

How does Shell Initialization Work? The precise files a shell reads at start-up is somewhat complex, and defined by this excellent chart 1: Shell Startup Flowchart For the purposes of what I m trying to fix, there are two paths that matter.
  • Interactive login shell startup
  • Interactive non-login shell startup
As you can see from the above, trying to distinguish these two paths in bash is an absolute mess. zsh, in contrast, is much cleaner and allows for a clear distinction between these two cases, with login shell configuration files as a superset of configuration files used by non-login shells.

How did we get here? I keep my configuration files in a config repository. Some time ago I got quite frustrated at this whole shell initialization thing, and just linked everything together in one profile file:
.mkshrc -> config/profile
.profile -> config/profile
This appears to have created this mess.

Move to ZSH I ve wanted to move to zsh for a while, and took this opportunity to do so. So my new configuration files are .zprofile and .zshrc instead of .mkshrc and .profile (though I m going to retain those symlinks to allow my old configurations to continue working). mksh is a nice simple shell, but using zsh here allows for more consistency between my home and $WORK environments, and will allow a lot more powerful extensions.

Updating my Prompt ZSH prompts use a totally different configuration via variable expansion. However, it also uses the PROMPT variable, so I set that to the needed values for zsh. There s an excellent ZSH prompt generator at https://zsh-prompt-generator.site that I used to get these variables, though I m sure they re in the zsh documentation somewhere as well. I wanted a simple prompt with user (%n), host (%m), and path (%d). I also wanted a % at the end to distinguish this from other shells.
PROMPT="%n@%m%d%% "

Fixing mksh prompts This worked but surprisingly mksh also looks at PROMPT, leaving my mksh prompt as the literal prompt string without expansion. Fixing this requires setting up a proper shrc and linking it to .mkshrc and .zshrc. I chose to move my existing aliases script to this file, as it also broke in non-login shells when moved to profile. Within this new shrc file we can check what shell we re running via $0:
if [ "$0" = "/bin/zsh" ]   [ "$0" = "zsh" ]   [ "$0" = "-zsh" ]
I chose to add plain zsh here in case I run it manually for whatever reason. I also added -zsh to support tmux as that s what it presents as $0. This also means you ll need to be careful to quote $0 or you ll get fun shell errors. There s probably a better way to do this, but I couldn t find something that was compatible with POSIX shell, which is what most of this has to be written in to be compatible with mksh and zsh2. We can then setup different prompts for each:
if [ "$0" = "/bin/zsh" ]   [ "$0" = "zsh" ]   [ "$0" = "-zsh" ]
then
	PROMPT="%n@%m%d%% "
else
	# Borrowed from
	# http://www.unixmantra.com/2013/05/setting-custom-prompt-in-ksh.html
	PS1='$(id -un)@$(hostname -s)$PWD$ '
fi

Setting Console Font in a Better Way I ve been setting console font via setfont in my .profile for a while. I m not sure where I picked this up, but it s not the right way. I even tried to only run this in a console with -t but that only checks that output is a terminal, not specifically a console.
if [ -t 1 ]
then
	setfont /usr/share/consolefonts/Lat15-Terminus20x10.psf.gz
fi
This also only runs once the console is logged into, instead of initializing it on boot. The correct way to set this up, on Debian-based systems, is reconfiguring console-setup like so:
dpkg-reconfigure console-setup
From there you get a menu of encoding, character set, font, and then font size to configure for your consoles.

VIM mode To enable VIM mode for ZSH, you simply need to set:
bindkeys -v
This allows you to edit your shell commands with basic VIM keybinds.

Getting back Ctrl + Left Arrow and Ctrl + Right Arrow Moving around one word at a time with Ctrl and the arrow keys is broken by vim mode unfortunately, so we ll need to re-enable it:
bindkey "^[[1;5C" forward-word
bindkey "^[[1;5D" backward-word

Why did it show up twice for tmux? Because tmux creates a login shell. Adding:
echo PROFILE
to profile and:
echo SHRC
to shrc confirms this with:
PROFILE
SHRC
SHRC
For now, profile sources shrc so that running twice is expected. But after this exploration and diagram, it s clear we don t need that for zsh. Removing this will break remote bash shells (see above diagram), but I can live without those on my development laptop. Removing that line results in the expected output for a new terminal:
SHRC
And the full output for a new tmux session or console:
PROFILE
SHRC
So finally we re back to a normal state! This post is a bit unfocused but I hope it helps someone else repair or enhance their shell environment. If you liked this4, or know of any other ways to manage this I could use, let me know at fixmyshell@tookmund.com.
  1. This chart comes from the excellent Shell Startup Scripts article by Peter Ward. I ve generated the SVG from the graphviz source linked in the article.
  2. Technically it has be compatible with Korn shell, but a quick google seems to suggest that that s actually a subset of POSIX shell.
  3. I use oh-my-zsh at $WORK but for now I m going to simplify my personal configuration. If I end up using a lot of plugins I ll reconsider this.
  4. Or if you ve found any typos or other issues that I should fix.

1 January 2024

Paul Wise: FLOSS Activities December 2023

Focus This month I didn't have any particular focus. I just worked on issues in my info bubble.

Changes

Issues
  • Feature in UDD
  • Conffile removal needed in neomutt
  • dpkg vendor config needed in Armbian
  • New SWH listers needed for depp & depp (different projects)

Review

Administration
  • Debian wiki: approve accounts

Communication
  • Respond to queries from Debian users and contributors on the mailing lists and IRC

Sponsors The SWH work was sponsored. All other work was done on a volunteer basis.

28 December 2023

Simon Josefsson: Validating debian/copyright: licenserecon

Recently I noticed a new tool called licenserecon written by Peter Blackman, and I helped get licenserecon into Debian. The purpose of licenserecon is to reconcile licenses from debian/copyright against the output from licensecheck, a tool written by Jonas Smedegaard. It assumes DEP5 copyright files. You run the tool in a directory that has a debian/ sub-directory, and its output when it notices mismatches (this is for resolv-wrapper):
# sudo apt install licenserecon
jas@kaka:~/dpkg/resolv-wrapper$ lrc
Parsing Source Tree ....
Running licensecheck ....
d/copyright       licensecheck
BSD-3-Clauses     BSD-3-clause     src/resolv_wrapper.c
BSD-3-Clauses     BSD-3-clause     tests/dns_srv.c
BSD-3-Clauses     BSD-3-clause     tests/test_dns_fake.c
BSD-3-Clauses     BSD-3-clause     tests/test_res_query_search.c
BSD-3-Clauses     BSD-3-clause     tests/torture.c
BSD-3-Clauses     BSD-3-clause     tests/torture.h
jas@kaka:~/dpkg/resolv-wrapper$ 
Noticing one-character typos like this may not bring satisfaction except to the most obsessive-compulsive among us, however the tool has the potential of discovering more serious mistakes. Using it manually once in a while may be useful, however I tend to forget QA steps that are not automated. Could we add this to the Salsa CI/CD pipeline? I recently proposed a merge request to add a wrap-and-sort job to the Salsa CI/CD pipeline (disabled by default) and learned how easy it was to extend it. I think licenserecon is still a bit rough on the edges, and I haven t been able to successfully use it on any but the simplest packages yet. I wouldn t want to suggest it is added to the normal Salsa CI/CD pipeline, even if disabled. If you maintain a Debian package on Salsa and wish to add a licenserecon job to your pipeline, I wrote licenserecon.yml for you. The simplest way to use licenserecon.yml is to replace recipes/debian.yml@salsa-ci-team/pipeline as the Salsa CI/CD configuration file setting with debian/salsa-ci.yml@debian/licenserecon. If you use a debian/salsa-ci.yml file you may put something like this in it instead:
---
include:
  - https://salsa.debian.org/salsa-ci-team/pipeline/raw/master/recipes/debian.yml
  - https://salsa.debian.org/debian/licenserecon/raw/main/debian/licenserecon.yml
Once you trigger the pipeline, this will result in a new job licenserecon that validates debian/copyright against licensecheck output on every build! I have added this to the libcpucycles package on Salsa and the pipeline contains a new job licenserecon whose output currently ends with:
$ cd $ WORKING_DIR /$ SOURCE_DIR 
$ lrc
Parsing Source Tree ....
Running licensecheck ....
No differences found
Cleaning up project directory and file based variables
If upstream releases a new version with files not matching our debian/copyright file, we will detect that on the next Salsa build job rather than months later when somebody happens to run the tools manually or there is some license conflict. Incidentally licenserecon is written in Pascal which brought back old memories with Turbo Pascal back in the MS-DOS days. Thanks Peter for licenserecon, and Jonas for licensecheck making this possible!

Next.