Search Results: "lowe"

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.

12 April 2024

NOKUBI Takatsugu: mailman3-web error when upgrading to bookworm

I tried to upgrade bullseye machien to bookworm, so I got the following error:
File /usr/lib/python3/dist-packages/django/contrib/auth/mixins.py , line 5, in
from django.contrib.auth.views import redirect_to_login
File /usr/lib/python3/dist-packages/django/contrib/auth/views.py , line 20, in
from django.utils.http import (
ImportError: cannot import name url_has_allowed_host_and_scheme from django.utils.http (/usr/lib/python3/dist-packages/django/utils/http.py) During handling of the above exception, another exception occurred:
It is similar to #1000810, but it is already closed. My solution is: I tried to send to the report, but it rerutns 550 Unknown or archived bug

9 April 2024

Ian Jackson: Why we ve voted No to CfD for Derril Water solar farm

[personal profile] ceb and I are members of the Derril Water Solar Park cooperative. We were recently invited to vote on whether the coop should bid for a Contract for Difference, in a government green electricity auction. We ve voted No. Green electricity from your mainstream supplier is a lie For a while [personal profile] ceb and I have wanted to contribute directly to green energy provision. This isn t really possible in the mainstream consumer electricy market. Mainstream electricity suppliers 100% green energy tariffs are pure greenwashing. In a capitalist boondoogle, they basically divvy up the electricity so that customers on the (typically more expensive) green tariff get the green electricity, and the other customers get whatever is left. (Of course the electricity is actually all mixed up by the National Grid.) There are fewer people signed up for these tariffs than there is green power generated, so this basically means signing up for a green tariff has no effect whatsoever, other than giving evil people more money. Ripple About a year ago we heard about Ripple. The structure is a little complicated, but the basic upshot is: Ripple promote and manage renewable energy schemes. The schemes themselves are each an individual company; the company is largely owned by a co-operative. The co-op is owned by consumers of electricity in the UK., To stop the co-operative being an purely financial investment scheme, shares ownership is limited according to your electricity usage. The electricity is be sold on the open market, and the profits are used to offset members electricity bills. (One gotcha from all of this is that for this to work your electricity billing provider has to be signed up with Ripple, but ours, Octopus, is.) It seemed to us that this was a way for us to directly cause (and pay for!) the actual generation of green electricity. So, we bought shares in one these co-operatives: we are co-owners of the Derril Water Solar Farm. We signed up for the maximum: funding generating capacity corresponding to 120% of our current electricity usage. We paid a little over 5000 for our shares. Contracts for Difference The UK has a renewable energy subsidy scheme, which goes by the name of Contracts for Difference. The idea is that a renewable energy generation company bids in advance, saying that they ll sell their electricity at Y price, for the duration of the contract (15 years in the current round). The lowest bids win. All the electricity from the participating infrastructure is sold on the open market, but if the market price is low the government makes up the difference, and if the price is high, the government takes the winnings. This is supposedly good for giving a stable investment environment, since the price the developer is going to get now doesn t depends on the electricity market over the next 15 years. The CfD system is supposed to encourage development, so you can only apply before you ve commissioned your generation infrastructure. Ripple and CfD Ripple recently invited us to agree that the Derril Water co-operative should bid in the current round of CfDs. If this goes ahead, and we are one of the auction s winners, the result would be that, instead of selling our electricity at the market price, we ll sell it at the fixed CfD price. This would mean that our return on our investment (which show up as savings on our electricity bills) would be decoupled from market electricity prices, and be much more predictable. They can t tell us the price they d want to bid at, and future electricity prices are rather hard to predict, but it s clear from the accompanying projections that they think we d be better off on average with a CfD. The documentation is very full of financial projections and graphs; other factors aren t really discussed in any detail. The rules of the co-op didn t require them to hold a vote, but very sensibly, for such a fundamental change in the model, they decided to treat it roughly the same way as for a rules change: they re hoping to get 75% Yes votes. Voting No The reason we re in this co-op at all is because we want to directly fund renewable electricity. Participating in the CfD auction would involve us competing with capitalist energy companies for government subsidies. Subsidies which are supposed to encourage the provision of green electricity. It seems to us that participating in this auction would remove most of the difference between what we hoped to do by investing in Derril Water, and just participating in the normal consumer electricity market. In particular, if we do win in the auction, that s probably directly removing the funding and investment support model for other, market-investor-funded, projects. In other words, our buying into Derril Water ceases to be an additional green energy project, changing (in its minor way) the UK s electricity mix. It becomes a financial transaction much more tenously connected (if connected at all) to helping mitigate the climate emergency. So our conclusion was that we must vote against.

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Matthew Palmer: How I Tripped Over the Debian Weak Keys Vulnerability

Those of you who haven t been in IT for far, far too long might not know that next month will be the 16th(!) anniversary of the disclosure of what was, at the time, a fairly earth-shattering revelation: that for about 18 months, the Debian OpenSSL package was generating entirely predictable private keys. The recent xz-stential threat (thanks to @nixCraft for making me aware of that one), has got me thinking about my own serendipitous interaction with a major vulnerability. Given that the statute of limitations has (probably) run out, I thought I d share it as a tale of how huh, that s weird can be a powerful threat-hunting tool but only if you ve got the time to keep pulling at the thread.

Prelude to an Adventure Our story begins back in March 2008. I was working at Engine Yard (EY), a now largely-forgotten Rails-focused hosting company, which pioneered several advances in Rails application deployment. Probably EY s greatest claim to lasting fame is that they helped launch a little code hosting platform you might have heard of, by providing them free infrastructure when they were little more than a glimmer in the Internet s eye. I am, of course, talking about everyone s favourite Microsoft product: GitHub. Since GitHub was in the right place, at the right time, with a compelling product offering, they quickly started to gain traction, and grow their userbase. With growth comes challenges, amongst them the one we re focusing on today: SSH login times. Then, as now, GitHub provided SSH access to the git repos they hosted, by SSHing to git@github.com with publickey authentication. They were using the standard way that everyone manages SSH keys: the ~/.ssh/authorized_keys file, and that became a problem as the number of keys started to grow. The way that SSH uses this file is that, when a user connects and asks for publickey authentication, SSH opens the ~/.ssh/authorized_keys file and scans all of the keys listed in it, looking for a key which matches the key that the user presented. This linear search is normally not a huge problem, because nobody in their right mind puts more than a few keys in their ~/.ssh/authorized_keys, right?
2008-era GitHub giving monkey puppet side-eye to the idea that nobody stores many keys in an authorized_keys file
Of course, as a popular, rapidly-growing service, GitHub was gaining users at a fair clip, to the point that the one big file that stored all the SSH keys was starting to visibly impact SSH login times. This problem was also not going to get any better by itself. Something Had To Be Done. EY management was keen on making sure GitHub ran well, and so despite it not really being a hosting problem, they were willing to help fix this problem. For some reason, the late, great, Ezra Zygmuntowitz pointed GitHub in my direction, and let me take the time to really get into the problem with the GitHub team. After examining a variety of different possible solutions, we came to the conclusion that the least-worst option was to patch OpenSSH to lookup keys in a MySQL database, indexed on the key fingerprint. We didn t take this decision on a whim it wasn t a case of yeah, sure, let s just hack around with OpenSSH, what could possibly go wrong? . We knew it was potentially catastrophic if things went sideways, so you can imagine how much worse the other options available were. Ensuring that this wouldn t compromise security was a lot of the effort that went into the change. In the end, though, we rolled it out in early April, and lo! SSH logins were fast, and we were pretty sure we wouldn t have to worry about this problem for a long time to come. Normally, you d think patching OpenSSH to make mass SSH logins super fast would be a good story on its own. But no, this is just the opening scene.

Chekov s Gun Makes its Appearance Fast forward a little under a month, to the first few days of May 2008. I get a message from one of the GitHub team, saying that somehow users were able to access other users repos over SSH. Naturally, as we d recently rolled out the OpenSSH patch, which touched this very thing, the code I d written was suspect number one, so I was called in to help.
The lineup scene from the movie The Usual Suspects They're called The Usual Suspects for a reason, but sometimes, it really is Keyser S ze
Eventually, after more than a little debugging, we discovered that, somehow, there were two users with keys that had the same key fingerprint. This absolutely shouldn t happen it s a bit like winning the lottery twice in a row1 unless the users had somehow shared their keys with each other, of course. Still, it was worth investigating, just in case it was a web application bug, so the GitHub team reached out to the users impacted, to try and figure out what was going on. The users professed no knowledge of each other, neither admitted to publicising their key, and couldn t offer any explanation as to how the other person could possibly have gotten their key. Then things went from weird to what the ? . Because another pair of users showed up, sharing a key fingerprint but it was a different shared key fingerprint. The odds now have gone from winning the lottery multiple times in a row to as close to this literally cannot happen as makes no difference.
Milhouse from The Simpsons says that We're Through The Looking Glass Here, People
Once we were really, really confident that the OpenSSH patch wasn t the cause of the problem, my involvement in the problem basically ended. I wasn t a GitHub employee, and EY had plenty of other customers who needed my help, so I wasn t able to stay deeply involved in the on-going investigation of The Mystery of the Duplicate Keys. However, the GitHub team did keep talking to the users involved, and managed to determine the only apparent common factor was that all the users claimed to be using Debian or Ubuntu systems, which was where their SSH keys would have been generated. That was as far as the investigation had really gotten, when along came May 13, 2008.

Chekov s Gun Goes Off With the publication of DSA-1571-1, everything suddenly became clear. Through a well-meaning but ultimately disasterous cleanup of OpenSSL s randomness generation code, the Debian maintainer had inadvertently reduced the number of possible keys that could be generated by a given user from bazillions to a little over 32,000. With so many people signing up to GitHub some of them no doubt following best practice and freshly generating a separate key it s unsurprising that some collisions occurred. You can imagine the sense of oooooooh, so that s what s going on! that rippled out once the issue was understood. I was mostly glad that we had conclusive evidence that my OpenSSH patch wasn t at fault, little knowing how much more contact I was to have with Debian weak keys in the future, running a huge store of known-compromised keys and using them to find misbehaving Certificate Authorities, amongst other things.

Lessons Learned While I ve not found a description of exactly when and how Luciano Bello discovered the vulnerability that became CVE-2008-0166, I presume he first came across it some time before it was disclosed likely before GitHub tripped over it. The stable Debian release that included the vulnerable code had been released a year earlier, so there was plenty of time for Luciano to have discovered key collisions and go hmm, I wonder what s going on here? , then keep digging until the solution presented itself. The thought hmm, that s odd , followed by intense investigation, leading to the discovery of a major flaw is also what ultimately brought down the recent XZ backdoor. The critical part of that sequence is the ability to do that intense investigation, though. When I reflect on my brush with the Debian weak keys vulnerability, what sticks out to me is the fact that I didn t do the deep investigation. I wonder if Luciano hadn t found it, how long it might have been before it was found. The GitHub team would have continued investigating, presumably, and perhaps they (or I) would have eventually dug deep enough to find it. But we were all super busy myself, working support tickets at EY, and GitHub feverishly building features and fighting the fires in their rapidly-growing service. As it was, Luciano was able to take the time to dig in and find out what was happening, but just like the XZ backdoor, I feel like we, as an industry, got a bit lucky that someone with the skills, time, and energy was on hand at the right time to make a huge difference. It s a luxury to be able to take the time to really dig into a problem, and it s a luxury that most of us rarely have. Perhaps an understated takeaway is that somehow we all need to wrestle back some time to follow our hunches and really dig into the things that make us go hmm .

Support My Hunches If you d like to help me be able to do intense investigations of mysterious software phenomena, you can shout me a refreshing beverage on ko-fi.
  1. the odds are actually probably more like winning the lottery about twenty times in a row. The numbers involved are staggeringly huge, so it s easiest to just approximate it as really, really unlikely .

4 April 2024

John Goerzen: The xz Issue Isn t About Open Source

You ve probably heard of the recent backdoor in xz. There have been a lot of takes on this, most of them boiling down to some version of:
The problem here is with Open Source Software.
I want to say not only is that view so myopic that it pushes towards the incorrect, but also it blinds us to more serious problems. Now, I don t pretend that there are no problems in the FLOSS community. There have been various pieces written about what this issue says about the FLOSS community (usually without actionable solutions). I m not here to say those pieces are wrong. Just that there s a bigger picture. So with this xz issue, it may well be a state actor (aka spy ) that added this malicious code to xz. We also know that proprietary software and systems can be vulnerable. For instance, a Twitter whistleblower revealed that Twitter employed Indian and Chinese spies, some knowingly. A recent report pointed to security lapses at Microsoft, including preventable lapses in security. According to the Wikipedia article on the SolarWinds attack, it was facilitated by various kinds of carelessness, including passwords being posted to Github and weak default passwords. They directly distributed malware-infested updates, encouraged customers to disable anti-malware tools when installing SolarWinds products, and so forth. It would be naive indeed to assume that there aren t black hat actors among the legions of programmers employed by companies that outsource work to low-cost countries some of which have challenges with bribery. So, given all this, we can t really say the problem is Open Source. Maybe it s more broad:
The problem here is with software.
Maybe that inches us closer, but is it really accurate? We have all heard of Boeing s recent issues, which seem to have some element of root causes in corporate carelessness, cost-cutting, and outsourcing. That sounds rather similar to the SolarWinds issue, doesn t it?
Well then, the problem is capitalism.
Maybe it has a role to play, but isn t it a little too easy to just say capitalism and throw up our hands helplessly, just as some do with FLOSS as at the start of this article? After all, capitalism also brought us plenty of products of very high quality over the years. When we can point to successful, non-careless products and I own some of them (for instance, my Framework laptop). We clearly haven t reached the root cause yet. And besides, what would you replace it with? All the major alternatives that have been tried have even stronger downsides. Maybe you replace it with better regulated capitalism , but that s still capitalism.
Then the problem must be with consumers.
As this argument would go, it s consumers buying patterns that drive problems. Buyers individual and corporate seek flashy features and low cost, prizing those over quality and security. No doubt this is true in a lot of cases. Maybe greed or status-conscious societies foster it: Temu promises people to shop like a billionaire , and unloads on them cheap junk, which all but guarantees that shipments from Temu containing products made with forced labor are entering the United States on a regular basis . But consumers are also people, and some fraction of them are quite capable of writing fantastic software, and in fact, do so. So what we need is some way to seize control. Some way to do what is right, despite the pressures of consumers or corporations. Ah yes, dear reader, you have been slogging through all these paragraphs and now realize I have been leading you to this:
Then the solution is Open Source.
Indeed. Faults and all, FLOSS is the most successful movement I know where people are bringing us back to the commons: working and volunteering for the common good, unleashing a thousand creative variants on a theme, iterating in every direction imaginable. We have FLOSS being vital parts of everything from $30 Raspberry Pis to space missions. It is bringing education and communication to impoverished parts of the world. It lets everyone write and release software. And, unlike the SolarWinds and Twitter issues, it exposes both clever solutions and security flaws to the world. If an authentication process in Windows got slower, we would all shrug and mutter Microsoft under our breath. Because, really, what else can we do? We have no agency with Windows. If an authentication process in Linux gets slower, anybody that s interested anybody at all can dive in and ask why and trace it down to root causes. Some look at this and say FLOSS is responsible for this mess. I look at it and say, this would be so much worse if it wasn t FLOSS and experience backs me up on this. FLOSS doesn t prevent security issues itself. What it does do is give capabilities to us all. The ability to investigate. Ability to fix. Yes, even the ability to break and its cousin, the power to learn. And, most rewarding, the ability to contribute.

Lukas M rdian: Netplan v1.0 paves the way to stable, declarative network management

New netplan status diff subcommand, finding differences between configuration and system state As the maintainer and lead developer for Netplan, I m proud to announce the general availability of Netplan v1.0 after more than 7 years of development efforts. Over the years, we ve so far had about 80 individual contributors from around the globe. This includes many contributions from our Netplan core-team at Canonical, but also from other big corporations such as Microsoft or Deutsche Telekom. Those contributions, along with the many we receive from our community of individual contributors, solidify Netplan as a healthy and trusted open source project. In an effort to make Netplan even more dependable, we started shipping upstream patch releases, such as 0.106.1 and 0.107.1, which make it easier to integrate fixes into our users custom workflows. With the release of version 1.0 we primarily focused on stability. However, being a major version upgrade, it allowed us to drop some long-standing legacy code from the libnetplan1 library. Removing this technical debt increases the maintainability of Netplan s codebase going forward. The upcoming Ubuntu 24.04 LTS and Debian 13 releases will ship Netplan v1.0 to millions of users worldwide.

Highlights of version 1.0 In addition to stability and maintainability improvements, it s worth looking at some of the new features that were included in the latest release:
  • Simultaneous WPA2 & WPA3 support.
  • Introduction of a stable libnetplan1 API.
  • Mellanox VF-LAG support for high performance SR-IOV networking.
  • New hairpin and port-mac-learning settings, useful for VXLAN tunnels with FRRouting.
  • New netplan status diff subcommand, finding differences between configuration and system state.
Besides those highlights of the v1.0 release, I d also like to shed some light on new functionality that was integrated within the past two years for those upgrading from the previous Ubuntu 22.04 LTS which used Netplan v0.104:
  • We added support for the management of new network interface types, such as veth, dummy, VXLAN, VRF or InfiniBand (IPoIB).
  • Wireless functionality was improved by integrating Netplan with NetworkManager on desktop systems, adding support for WPA3 and adding the notion of a regulatory-domain, to choose proper frequencies for specific regions.
  • To improve maintainability, we moved to Meson as Netplan s buildsystem, added upstream CI coverage for multiple Linux distributions and integrations (such as Debian testing, NetworkManager, snapd or cloud-init), checks for ABI compatibility, and automatic memory leak detection.
  • We increased consistency between the supported backend renderers (systemd-networkd and NetworkManager), by matching physical network interfaces on permanent MAC address, when the match.macaddress setting is being used, and added new hardware offloading functionality for high performance networking, such as Single-Root IO Virtualisation virtual function link-aggregation (SR-IOV VF-LAG).
The much improved Netplan documentation, that is now hosted on Read the Docs , and new command line subcommands, such as netplan status, make Netplan a well vested tool for declarative network management and troubleshooting.

Integrations Those changes pave the way to integrate Netplan in 3rd party projects, such as system installers or cloud deployment methods. By shipping the new python3-netplan Python bindings to libnetplan, it is now easier than ever to access Netplan functionality and network validation from other projects. We are proud that the Debian Cloud Team chose Netplan to be the default network management tool in their official cloud-images for Debian Bookworm and beyond. Ubuntu s NetworkManager package now uses Netplan as it s default backend on Ubuntu 23.10 Desktop systems and beyond. Further integrations happened with cloud-init and the Calamares installer.
Please check out the Netplan version 1.0 release on GitHub! If you want to learn more, follow our activities on Netplan.io, GitHub, Launchpad, IRC or our Netplan Developer Diaries blog on discourse.

1 April 2024

Arturo Borrero Gonz lez: Kubecon and CloudNativeCon 2024 Europe summary

Kubecon EU 2024 Paris logo This blog post shares my thoughts on attending Kubecon and CloudNativeCon 2024 Europe in Paris. It was my third time at this conference, and it felt bigger than last year s in Amsterdam. Apparently it had an impact on public transport. I missed part of the opening keynote because of the extremely busy rush hour tram in Paris. On Artificial Intelligence, Machine Learning and GPUs Talks about AI, ML, and GPUs were everywhere this year. While it wasn t my main interest, I did learn about GPU resource sharing and power usage on Kubernetes. There were also ideas about offering Models-as-a-Service, which could be cool for Wikimedia Toolforge in the future. See also: On security, policy and authentication This was probably the main interest for me in the event, given Wikimedia Toolforge was about to migrate away from Pod Security Policy, and we were currently evaluating different alternatives. In contrast to my previous attendances to Kubecon, where there were three policy agents with presence in the program schedule, Kyverno, Kubewarden and OpenPolicyAgent (OPA), this time only OPA had the most relevant sessions. One surprising bit I got from one of the OPA sessions was that it could work to authorize linux PAM sessions. Could this be useful for Wikimedia Toolforge? OPA talk I attended several sessions related to authentication topics. I discovered the keycloak software, which looks very promising. I also attended an Oauth2 session which I had a hard time following, because I clearly missed some additional knowledge about how Oauth2 works internally. I also attended a couple of sessions that ended up being a vendor sales talk. See also: On container image builds, harbor registry, etc This topic was also of interest to me because, again, it is a core part of Wikimedia Toolforge. I attended a couple of sessions regarding container image builds, including topics like general best practices, image minimization, and buildpacks. I learned about kpack, which at first sight felt like a nice simplification of how the Toolforge build service was implemented. I also attended a session by the Harbor project maintainers where they shared some valuable information on things happening soon or in the future , for example: On networking I attended a couple of sessions regarding networking. One session in particular I paid special attention to, ragarding on network policies. They discussed new semantics being added to the Kubernetes API. The different layers of abstractions being added to the API, the different hook points, and override layers clearly resembled (to me at least) the network packet filtering stack of the linux kernel (netfilter), but without the 20 (plus) years of experience building the right semantics and user interfaces. Network talk I very recently missed some semantics for limiting the number of open connections per namespace, see Phabricator T356164: [toolforge] several tools get periods of connection refused (104) when connecting to wikis This functionality should be available in the lower level tools, I mean Netfilter. I may submit a proposal upstream at some point, so they consider adding this to the Kubernetes API. Final notes In general, I believe I learned many things, and perhaps even more importantly I re-learned some stuff I had forgotten because of lack of daily exposure. I m really happy that the cloud native way of thinking was reinforced in me, which I still need because most of my muscle memory to approach systems architecture and engineering is from the old pre-cloud days. That being said, I felt less engaged with the content of the conference schedule compared to last year. I don t know if the schedule itself was less interesting, or that I m losing interest? Finally, not an official track in the conference, but we met a bunch of folks from Wikimedia Deutschland. We had a really nice time talking about how wikibase.cloud uses Kubernetes, whether they could run in Wikimedia Cloud Services, and why structured data is so nice. Group photo

29 March 2024

Ravi Dwivedi: A visit to the Taj Mahal

Note: The currency used in this post is Indian Rupees, which was around 83 INR for 1 US Dollar as that time. I and my friend Badri visited the Taj Mahal this month. Taj Mahal is one of the main tourist destinations in India and does not need an introduction, I guess. It is in Agra, in the state of Uttar Pradesh, 188 km from Delhi by train. So, I am writing a post documenting useful information for people who are planning to visit Taj Mahal. Feel free to ask me questions about visiting the Taj Mahal.
Our retiring room at the Old Delhi Railway Station.
We had booked a train from Delhi to Agra. The name of the train was Taj Express, and its scheduled departure time from Hazrat Nizamuddin station in Delhi is 07:08 hours in the morning, and its arrival time at Agra Cantt station is 09:45. So, we booked a retiring room at the Old Delhi railway station for the previous night. This retiring room was hard to find. We woke up at 05:00 in the morning and took the metro to Hazrat Nizamuddin station. We barely reached the station in time, but anyway, the train was not yet at the station; it was late. We reached Agra at 10:30 and checked into our retiring room, took rest and went out for Taj Mahal at 13:00 in the afternoon. Taj Mahal s outer gate is 5 km away from the Agra Cantt station. As we were going out of the railway station, we were chased by an autorickshaw driver who offered to go to Taj Mahal for 150 INR for both of us. I asked him to bring it down to 60 INR, and after some back and forth, he agreed to drop us off at Taj Mahal for 80 INR. But I said we won t pay anything above 60 INR. He agreed with that amount but said that he would need to fill up with more passengers. When we saw that he wasn t making any effort in bringing more passengers, we walked away. As soon as we got out of the railway station complex, an autorickshaw driver came to us and offered to drop us off at Taj Mahal for 20 INR if we are sharing with other passengers and 100 INR if we reserve the auto for us. We agreed to go with 20 INR per person, but he started the autorickshaw as soon as we hopped in. I thought that the third person in the auto was another passenger sharing a ride with us, but later we got to know he was with the driver. Upon reaching the outer gate of Taj Mahal, I gave him 40 INR (for both of us), and he asked to instead give 100 INR as he said we reserved the auto, even though I clearly stated before taking the auto that we wanted to share the auto, not reserve it. I think this was a scam. We walked away, and he didn t insist further. Taj Mahal entrance was like 500 m from the outer gate. We went there and bought offline tickets just outside the West gate. For Indians, the ticket for going inside the Taj Mahal complex is 50 INR, and a visit to the mausoleum costs 200 INR extra.
Security outside the Taj Mahal complex.
This red colored building is entrance to where you can see the Taj Mahal.
Taj Mahal.
Shoe covers for going inside the mausoleum.
Taj Mahal from side angle.
We came out of the Taj Mahal complex at 18:00 and stopped for some tea and snacks. I also bought a fridge magnet for 30 INR. Then we walked back towards Agra Cantt station, as we had a train for Jaipur at midnight. We were hoping to find a restaurant along the way, but we didn t find any that we found interesting, so we just ate at the railway station. During the return trip, we noticed there was a bus stand near the station, which we didn t know about. It turns out you can catch a bus to Taj Mahal from there. You can click here to check out the location of that bus stand on OpenStreetMap.

Expenses These were our expenses per person Retiring room at Delhi Railway Station for 12 hours 131 Train ticket from Delhi to Agra (Taj Express) 110 Retiring room at Agra Cantt station for 12 hours 450 Auto-rickshaw to Taj Mahal 20 Taj Mahal ticket (including going inside the mausoleum): 250 Food 350

Important information for visitors
  • Taj Mahal is closed on Friday.
  • There are plenty of free-of-cost drinking water taps inside the Taj Mahal complex.
  • Ticket price for Indians is 50, for foreigners and NRIs it is 1100, and for people from SAARC/BIMSTEC is 540. 200 extra for the mausoleum for everyone.
  • A visit inside the mausoleum requires covering your shoes or removing them. Shoe covers costs 10 per person inside the complex, but are probably involved free of charge in foreigner tickets. We could not find a place to keep our shoes, but some people managed to enter barefoot, indicating there must be some place to keep your shoes.
  • Mobile phones and cameras are allowed inside the Taj Mahal, but not eatables.
  • We went there on March 10th, and the weather was pleasant. So, we recommend going around that time.
  • Regarding the timings, I found this written near the ticket counter: Taj Mahal opens 30 minutes before sunrise and closes 30 minutes before sunset during normal operating days, so the timings are vague. But we came out of the complex at 18:00 hours. I would interpret that to mean the Taj Mahal is open from 07:00 to 18:00, and the ticket counter closes at around 17:00. During the winter, the timings might differ.
  • The cheapest way to reach Taj Mahal is by bus, and the bus stop is here
Bye for now. See you in the next post :)

28 March 2024

Joey Hess: the vulture in the coal mine

Turns out that VPS provider Vultr's terms of service were quietly changed some time ago to give them a "perpetual, irrevocable" license to use content hosted there in any way, including modifying it and commercializing it "for purposes of providing the Services to you." This is very similar to changes that Github made to their TOS in 2017. Since then, Github has been rebranded as "The world s leading AI-powered developer platform". The language in their TOS now clearly lets them use content stored in Github for training AI. (Probably this is their second line of defense if the current attempt to legitimise copyright laundering via generative AI fails.) Vultr is currently in damage control mode, accusing their concerned customers of spreading "conspiracy theories" (-- founder David Aninowsky) and updating the TOS to remove some of the problem language. Although it still allows them to "make derivative works", so could still allow their AI division to scrape VPS images for training data. Vultr claims this was the legalese version of technical debt, that it only ever applied to posts in a forum (not supported by the actual TOS language) and basically that they and their lawyers are incompetant but not malicious. Maybe they are indeed incompetant. But even if I give them the benefit of the doubt, I expect that many other VPS providers, especially ones targeting non-corporate customers, are watching this closely. If Vultr is not significantly harmed by customers jumping ship, if the latest TOS change is accepted as good enough, then other VPS providers will know that they can try this TOS trick too. If Vultr's AI division does well, others will wonder to what extent it is due to having all this juicy training data. For small self-hosters, this seems like a good time to make sure you're using a VPS provider you can actually trust to not be eyeing your disk image and salivating at the thought of stripmining it for decades of emails. Probably also worth thinking about moving to bare metal hardware, perhaps hosted at home. I wonder if this will finally make it worthwhile to mess around with VPS TPMs?

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. :)

23 March 2024

Kentaro Hayashi: How about allocating more buildd resource for armel and armhf?

This article is cross-posting from grow-your-ideas. This is just an idea. salsa.debian.org

The problem According to Developer Machines [1], current buildd machines are like this:
  • armel: 4 buildd (4 for arm64/armhf/armel)
  • armhf: 7 buildd (4 for arm64/armhf/armel and 3 for armhf only)
[1] https://db.debian.org/machines.cgi In contrast to other buildd architectures, these instances are quite a few and it seems that it causes a shortage of buildd resourses. (e.g. during mass transition, give-back turn around time becomes longer and longer.)

Actual situation As you know, during 64bit time_t transition, many packages should be built, but it seems that +b1 or +bN build becomes slower. (I've hit BD-Uninstalled some times because of missing dependency rebuild) ref. https://qa.debian.org/dose/debcheck/unstable_main/index.html

Expected situation Allocate more buildd resources for armel and armhf. It is just an idea, but how about assigning some buildd as armel/armhf buildd? Above buildd is used only for arm64 buildd currently. Maybe there is some technical reason not suitable for armel/armhf buildd, but I don't know yet.
2024/03/24 UPDATE: arm-arm01,arm-arm03,arm-arm-04 has already assigned to armel/armhf buildd, so it is an invalid proposal. See https://buildd.debian.org/status/architecture.php?a=armhf&suite=sid&buildd=buildd_arm64-arm-arm-01, https://buildd.debian.org/status/architecture.php?a=armhf&suite=sid&buildd=buildd_arm64-arm-arm-03, https://buildd.debian.org/status/architecture.php?a=armhf&suite=sid&buildd=buildd_arm64-arm-arm-04

Additional information
  • arm64: 10 buildd (4 for arm64/armhf/armel, 6 for arm64 only)
  • amd64: 7 buildd (5 for amd64/i386 buildd)
  • riscv64: 9 buildd

Erich Schubert: Do not get Amazon Kids+ or a Fire HD Kids

The Amazon Kids parental controls are extremely insufficient, and I strongly advise against getting any of the Amazon Kids series. The initial permise (and some older reviews) look okay: you can set some time limits, and you can disable anything that requires buying. With the hardware you get one year of the Amazon Kids+ subscription, which includes a lot of interesting content such as books and audio, but also some apps. This seemed attractive: some learning apps, some decent games. Sometimes there seems to be a special Amazon Kids+ edition , supposedly one that has advertisements reduced/removed and no purchasing. However, there are so many things just wrong in Amazon Kids: And, unfortunately, Amazon Kids is full of poor content for kids, such as DIY Fashion Star that I consider to be very dangerous for kids: it is extremely stereotypical, beginning with supposedly female color schemes, model-only body types, and judging people by their clothing (and body). You really thought you could hand-pick suitable apps for your kid on your own? No, you have to identify and remove such contents one by one, with many clicks each, because there is no whitelisting, and no mass-removal (anymore - apparently Amazon removed the workarounds that previously allowed you to mass remove contents). Not with Amazon Kids+, which apparently aims at raising the next generation of zombie customers that buy whatever you tell them to buy. Hence, do not get your kids an Amazon Fire HD tablet!

18 March 2024

Simon Josefsson: Apt archive mirrors in Git-LFS

My effort to improve transparency and confidence of public apt archives continues. I started to work on this in Apt Archive Transparency in which I mention the debdistget project in passing. Debdistget is responsible for mirroring index files for some public apt archives. I ve realized that having a publicly auditable and preserved mirror of the apt repositories is central to being able to do apt transparency work, so the debdistget project has become more central to my project than I thought. Currently I track Trisquel, PureOS, Gnuinos and their upstreams Ubuntu, Debian and Devuan. Debdistget download Release/Package/Sources files and store them in a git repository published on GitLab. Due to size constraints, it uses two repositories: one for the Release/InRelease files (which are small) and one that also include the Package/Sources files (which are large). See for example the repository for Trisquel release files and the Trisquel package/sources files. Repositories for all distributions can be found in debdistutils archives GitLab sub-group. The reason for splitting into two repositories was that the git repository for the combined files become large, and that some of my use-cases only needed the release files. Currently the repositories with packages (which contain a couple of months worth of data now) are 9GB for Ubuntu, 2.5GB for Trisquel/Debian/PureOS, 970MB for Devuan and 450MB for Gnuinos. The repository size is correlated to the size of the archive (for the initial import) plus the frequency and size of updates. Ubuntu s use of Apt Phased Updates (which triggers a higher churn of Packages file modifications) appears to be the primary reason for its larger size. Working with large Git repositories is inefficient and the GitLab CI/CD jobs generate quite some network traffic downloading the git repository over and over again. The most heavy user is the debdistdiff project that download all distribution package repositories to do diff operations on the package lists between distributions. The daily job takes around 80 minutes to run, with the majority of time is spent on downloading the archives. Yes I know I could look into runner-side caching but I dislike complexity caused by caching. Fortunately not all use-cases requires the package files. The debdistcanary project only needs the Release/InRelease files, in order to commit signatures to the Sigstore and Sigsum transparency logs. These jobs still run fairly quickly, but watching the repository size growth worries me. Currently these repositories are at Debian 440MB, PureOS 130MB, Ubuntu/Devuan 90MB, Trisquel 12MB, Gnuinos 2MB. Here I believe the main size correlation is update frequency, and Debian is large because I track the volatile unstable. So I hit a scalability end with my first approach. A couple of months ago I solved this by discarding and resetting these archival repositories. The GitLab CI/CD jobs were fast again and all was well. However this meant discarding precious historic information. A couple of days ago I was reaching the limits of practicality again, and started to explore ways to fix this. I like having data stored in git (it allows easy integration with software integrity tools such as GnuPG and Sigstore, and the git log provides a kind of temporal ordering of data), so it felt like giving up on nice properties to use a traditional database with on-disk approach. So I started to learn about Git-LFS and understanding that it was able to handle multi-GB worth of data that looked promising. Fairly quickly I scripted up a GitLab CI/CD job that incrementally update the Release/Package/Sources files in a git repository that uses Git-LFS to store all the files. The repository size is now at Ubuntu 650kb, Debian 300kb, Trisquel 50kb, Devuan 250kb, PureOS 172kb and Gnuinos 17kb. As can be expected, jobs are quick to clone the git archives: debdistdiff pipelines went from a run-time of 80 minutes down to 10 minutes which more reasonable correlate with the archive size and CPU run-time. The LFS storage size for those repositories are at Ubuntu 15GB, Debian 8GB, Trisquel 1.7GB, Devuan 1.1GB, PureOS/Gnuinos 420MB. This is for a couple of days worth of data. It seems native Git is better at compressing/deduplicating data than Git-LFS is: the combined size for Ubuntu is already 15GB for a couple of days data compared to 8GB for a couple of months worth of data with pure Git. This may be a sub-optimal implementation of Git-LFS in GitLab but it does worry me that this new approach will be difficult to scale too. At some level the difference is understandable, Git-LFS probably store two different Packages files around 90MB each for Trisquel as two 90MB files, but native Git would store it as one compressed version of the 90MB file and one relatively small patch to turn the old files into the next file. So the Git-LFS approach surprisingly scale less well for overall storage-size. Still, the original repository is much smaller, and you usually don t have to pull all LFS files anyway. So it is net win. Throughout this work, I kept thinking about how my approach relates to Debian s snapshot service. Ultimately what I would want is a combination of these two services. To have a good foundation to do transparency work I would want to have a collection of all Release/Packages/Sources files ever published, and ultimately also the source code and binaries. While it makes sense to start on the latest stable releases of distributions, this effort should scale backwards in time as well. For reproducing binaries from source code, I need to be able to securely find earlier versions of binary packages used for rebuilds. So I need to import all the Release/Packages/Sources packages from snapshot into my repositories. The latency to retrieve files from that server is slow so I haven t been able to find an efficient/parallelized way to download the files. If I m able to finish this, I would have confidence that my new Git-LFS based approach to store these files will scale over many years to come. This remains to be seen. Perhaps the repository has to be split up per release or per architecture or similar. Another factor is storage costs. While the git repository size for a Git-LFS based repository with files from several years may be possible to sustain, the Git-LFS storage size surely won t be. It seems GitLab charges the same for files in repositories and in Git-LFS, and it is around $500 per 100GB per year. It may be possible to setup a separate Git-LFS backend not hosted at GitLab to serve the LFS files. Does anyone know of a suitable server implementation for this? I had a quick look at the Git-LFS implementation list and it seems the closest reasonable approach would be to setup the Gitea-clone Forgejo as a self-hosted server. Perhaps a cloud storage approach a la S3 is the way to go? The cost to host this on GitLab will be manageable for up to ~1TB ($5000/year) but scaling it to storing say 500TB of data would mean an yearly fee of $2.5M which seems like poor value for the money. I realized that ultimately I would want a git repository locally with the entire content of all apt archives, including their binary and source packages, ever published. The storage requirements for a service like snapshot (~300TB of data?) is today not prohibitly expensive: 20TB disks are $500 a piece, so a storage enclosure with 36 disks would be around $18.000 for 720TB and using RAID1 means 360TB which is a good start. While I have heard about ~TB-sized Git-LFS repositories, would Git-LFS scale to 1PB? Perhaps the size of a git repository with multi-millions number of Git-LFS pointer files will become unmanageable? To get started on this approach, I decided to import a mirror of Debian s bookworm for amd64 into a Git-LFS repository. That is around 175GB so reasonable cheap to host even on GitLab ($1000/year for 200GB). Having this repository publicly available will make it possible to write software that uses this approach (e.g., porting debdistreproduce), to find out if this is useful and if it could scale. Distributing the apt repository via Git-LFS would also enable other interesting ideas to protecting the data. Consider configuring apt to use a local file:// URL to this git repository, and verifying the git checkout using some method similar to Guix s approach to trusting git content or Sigstore s gitsign. A naive push of the 175GB archive in a single git commit ran into pack size limitations: remote: fatal: pack exceeds maximum allowed size (4.88 GiB) however breaking up the commit into smaller commits for parts of the archive made it possible to push the entire archive. Here are the commands to create this repository: git init
git lfs install
git lfs track 'dists/**' 'pool/**'
git add .gitattributes
git commit -m"Add Git-LFS track attributes." .gitattributes
time debmirror --method=rsync --host ftp.se.debian.org --root :debian --arch=amd64 --source --dist=bookworm,bookworm-updates --section=main --verbose --diff=none --keyring /usr/share/keyrings/debian-archive-keyring.gpg --ignore .git .
git add dists project
git commit -m"Add." -a
git remote add origin git@gitlab.com:debdistutils/archives/debian/mirror.git
git push --set-upstream origin --all
for d in pool//; do
echo $d;
time git add $d;
git commit -m"Add $d." -a
git push
done
The resulting repository size is around 27MB with Git LFS object storage around 174GB. I think this approach would scale to handle all architectures for one release, but working with a single git repository for all releases for all architectures may lead to a too large git repository (>1GB). So maybe one repository per release? These repositories could also be split up on a subset of pool/ files, or there could be one repository per release per architecture or sources. Finally, I have concerns about using SHA1 for identifying objects. It seems both Git and Debian s snapshot service is currently using SHA1. For Git there is SHA-256 transition and it seems GitLab is working on support for SHA256-based repositories. For serious long-term deployment of these concepts, it would be nice to go for SHA256 identifiers directly. Git-LFS already uses SHA256 but Git internally uses SHA1 as does the Debian snapshot service. What do you think? Happy Hacking!

Christoph Berg: vcswatch and git --filter

Debian is running a "vcswatch" service that keeps track of the status of all packaging repositories that have a Vcs-Git (and other VCSes) header set and shows which repos might need a package upload to push pending changes out. Naturally, this is a lot of data and the scratch partition on qa.debian.org had to be expanded several times, up to 300 GB in the last iteration. Attempts to reduce that size using shallow clones (git clone --depth=50) did not result more than a few percent of space saved. Running git gc on all repos helps a bit, but is tedious and as Debian is growing, the repos are still growing both in size and number. I ended up blocking all repos with checkouts larger than a gigabyte, and still the only cure was expanding the disk, or to lower the blocking threshold. Since we only need a tiny bit of info from the repositories, namely the content of debian/changelog and a few other files from debian/, plus the number of commits since the last tag on the packaging branch, it made sense to try to get the info without fetching a full repo clone. The question if we could grab that solely using the GitLab API at salsa.debian.org was never really answered. But then, in #1032623, G bor N meth suggested the use of git clone --filter blob:none. As things go, this sat unattended in the bug report for almost a year until the next "disk full" event made me give it a try. The blob:none filter makes git clone omit all files, fetching only commit and tree information. Any blob (file content) needed at git run time is transparently fetched from the upstream repository, and stored locally. It turned out to be a game-changer. The (largish) repositories I tried it on shrank to 1/100 of the original size. Poking around I figured we could even do better by using tree:0 as filter. This additionally omits all trees from the git clone, again only fetching the information at run time when needed. Some of the larger repos I tried it on shrank to 1/1000 of their original size. I deployed the new option on qa.debian.org and scheduled all repositories to fetch a new clone on the next scan: The initial dip from 100% to 95% is my first "what happens if we block repos > 500 MB" attempt. Over the week after that, the git filter clones reduce the overall disk consumption from almost 300 GB to 15 GB, a 1/20. Some repos shrank from GBs to below a MB. Perhaps I should make all my git clones use one of the filters.

14 March 2024

Matthew Garrett: Digital forgeries are hard

Closing arguments in the trial between various people and Craig Wright over whether he's Satoshi Nakamoto are wrapping up today, amongst a bewildering array of presented evidence. But one utterly astonishing aspect of this lawsuit is that expert witnesses for both sides agreed that much of the digital evidence provided by Craig Wright was unreliable in one way or another, generally including indications that it wasn't produced at the point in time it claimed to be. And it's fascinating reading through the subtle (and, in some cases, not so subtle) ways that that's revealed.

One of the pieces of evidence entered is screenshots of data from Mind Your Own Business, a business management product that's been around for some time. Craig Wright relied on screenshots of various entries from this product to support his claims around having controlled meaningful number of bitcoin before he was publicly linked to being Satoshi. If these were authentic then they'd be strong evidence linking him to the mining of coins before Bitcoin's public availability. Unfortunately the screenshots themselves weren't contemporary - the metadata shows them being created in 2020. This wouldn't fundamentally be a problem (it's entirely reasonable to create new screenshots of old material), as long as it's possible to establish that the material shown in the screenshots was created at that point. Sadly, well.

One part of the disclosed information was an email that contained a zip file that contained a raw database in the format used by MYOB. Importing that into the tool allowed an audit record to be extracted - this record showed that the relevant entries had been added to the database in 2020, shortly before the screenshots were created. This was, obviously, not strong evidence that Craig had held Bitcoin in 2009. This evidence was reported, and was responded to with a couple of additional databases that had an audit trail that was consistent with the dates in the records in question. Well, partially. The audit record included session data, showing an administrator logging into the data base in 2011 and then, uh, logging out in 2023, which is rather more consistent with someone changing their system clock to 2011 to create an entry, and switching it back to present day before logging out. In addition, the audit log included fields that didn't exist in versions of the product released before 2016, strongly suggesting that the entries dated 2009-2011 were created in software released after 2016. And even worse, the order of insertions into the database didn't line up with calendar time - an entry dated before another entry may appear in the database afterwards, indicating that it was created later. But even more obvious? The database schema used for these old entries corresponded to a version of the software released in 2023.

This is all consistent with the idea that these records were created after the fact and backdated to 2009-2011, and that after this evidence was made available further evidence was created and backdated to obfuscate that. In an unusual turn of events, during the trial Craig Wright introduced further evidence in the form of a chain of emails to his former lawyers that indicated he had provided them with login details to his MYOB instance in 2019 - before the metadata associated with the screenshots. The implication isn't entirely clear, but it suggests that either they had an opportunity to examine this data before the metadata suggests it was created, or that they faked the data? So, well, the obvious thing happened, and his former lawyers were asked whether they received these emails. The chain consisted of three emails, two of which they confirmed they'd received. And they received a third email in the chain, but it was different to the one entered in evidence. And, uh, weirdly, they'd received a copy of the email that was submitted - but they'd received it a few days earlier. In 2024.

And again, the forensic evidence is helpful here! It turns out that the email client used associates a timestamp with any attachments, which in this case included an image in the email footer - and the mysterious time travelling email had a timestamp in 2024, not 2019. This was created by the client, so was consistent with the email having been sent in 2024, not being sent in 2019 and somehow getting stuck somewhere before delivery. The date header indicates 2019, as do encoded timestamps in the MIME headers - consistent with the mail being sent by a computer with the clock set to 2019.

But there's a very weird difference between the copy of the email that was submitted in evidence and the copy that was located afterwards! The first included a header inserted by gmail that included a 2019 timestamp, while the latter had a 2024 timestamp. Is there a way to determine which of these could be the truth? It turns out there is! The format of that header changed in 2022, and the version in the email is the new version. The version with the 2019 timestamp is anachronistic - the format simply doesn't match the header that gmail would have introduced in 2019, suggesting that an email sent in 2022 or later was modified to include a timestamp of 2019.

This is by no means the only indication that Craig Wright's evidence may be misleading (there's the whole argument that the Bitcoin white paper was written in LaTeX when general consensus is that it's written in OpenOffice, given that's what the metadata claims), but it's a lovely example of a more general issue.

Our technology chains are complicated. So many moving parts end up influencing the content of the data we generate, and those parts develop over time. It's fantastically difficult to generate an artifact now that precisely corresponds to how it would look in the past, even if we go to the effort of installing an old OS on an old PC and setting the clock appropriately (are you sure you're going to be able to mimic an entirely period appropriate patch level?). Even the version of the font you use in a document may indicate it's anachronistic. I'm pretty good at computers and I no longer have any belief I could fake an old document.

(References: this Dropbox, under "Expert reports", "Patrick Madden". Initial MYOB data is in "Appendix PM7", further analysis is in "Appendix PM42", email analysis is "Sixth Expert Report of Mr Patrick Madden")

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Freexian Collaborators: Monthly report about Debian Long Term Support, February 2024 (by Roberto C. S nchez)

Like each month, have a look at the work funded by Freexian s Debian LTS offering.

Debian LTS contributors In February, 18 contributors have been paid to work on Debian LTS, their reports are available:
  • Abhijith PA did 10.0h (out of 14.0h assigned), thus carrying over 4.0h to the next month.
  • Adrian Bunk did 13.5h (out of 24.25h assigned and 41.75h from previous period), thus carrying over 52.5h to the next month.
  • Bastien Roucari s did 20.0h (out of 20.0h assigned).
  • Ben Hutchings did 2.0h (out of 14.5h assigned and 9.5h from previous period), thus carrying over 22.0h to the next month.
  • Chris Lamb did 18.0h (out of 18.0h assigned).
  • Daniel Leidert did 10.0h (out of 10.0h assigned).
  • Emilio Pozuelo Monfort did 3.0h (out of 28.25h assigned and 31.75h from previous period), thus carrying over 57.0h to the next month.
  • Guilhem Moulin did 7.25h (out of 4.75h assigned and 15.25h from previous period), thus carrying over 12.75h to the next month.
  • Holger Levsen did 0.5h (out of 3.5h assigned and 8.5h from previous period), thus carrying over 11.5h to the next month.
  • Lee Garrett did 0.0h (out of 18.25h assigned and 41.75h from previous period), thus carrying over 60.0h to the next month.
  • Markus Koschany did 40.0h (out of 40.0h assigned).
  • Roberto C. S nchez did 3.5h (out of 8.75h assigned and 3.25h from previous period), thus carrying over 8.5h to the next month.
  • Santiago Ruano Rinc n did 13.5h (out of 13.5h assigned and 2.5h from previous period), thus carrying over 2.5h to the next month.
  • Sean Whitton did 4.5h (out of 0.5h assigned and 5.5h from previous period), thus carrying over 1.5h to the next month.
  • Sylvain Beucler did 24.5h (out of 27.75h assigned and 32.25h from previous period), thus carrying over 35.5h to the next month.
  • Thorsten Alteholz did 14.0h (out of 14.0h assigned).
  • Tobias Frost did 12.0h (out of 12.0h assigned).
  • Utkarsh Gupta did 11.25h (out of 26.75h assigned and 33.25h from previous period), thus carrying over 48.75 to the next month.

Evolution of the situation In February, we have released 17 DLAs. The number of DLAs published during February was a bit lower than usual, as there was much work going on in the area of triaging CVEs (a number of which turned out to not affect Debia buster, and others which ended up being duplicates, or otherwise determined to be invalid). Of the packages which did receive updates, notable were sudo (to fix a privilege management issue), and iwd and wpa (both of which suffered from authentication bypass vulnerabilities). While this has already been already announced in the Freexian blog, we would like to mention here the start of the Long Term Support project for Samba 4.17. You can find all the important details in that post, but we would like to highlight that it is thanks to our LTS sponsors that we are able to fund the work from our partner, Catalyst, towards improving the security support of Samba in Debian 12 (Bookworm).

Thanks to our sponsors Sponsors that joined recently are in bold.

13 March 2024

Russell Coker: The Shape of Computers

Introduction There have been many experiments with the sizes of computers, some of which have stayed around and some have gone away. The trend has been to make computers smaller, the early computers had buildings for them. Recently for come classes computers have started becoming as small as could be reasonably desired. For example phones are thin enough that they can blow away in a strong breeze, smart watches are much the same size as the old fashioned watches they replace, and NUC type computers are as small as they need to be given the size of monitors etc that they connect to. This means that further development in the size and shape of computers will largely be determined by human factors. I think we need to consider how computers might be developed to better suit humans and how to write free software to make such computers usable without being constrained by corporate interests. Those of us who are involved in developing OSs and applications need to consider how to adjust to the changes and ideally anticipate changes. While we can t anticipate the details of future devices we can easily predict general trends such as being smaller, higher resolution, etc. Desktop/Laptop PCs When home computers first came out it was standard to have the keyboard in the main box, the Apple ][ being the most well known example. This has lost popularity due to the demand to have multiple options for a light keyboard that can be moved for convenience combined with multiple options for the box part. But it still pops up occasionally such as the Raspberry Pi 400 [1] which succeeds due to having the computer part being small and light. I think this type of computer will remain a niche product. It could be used in a add a screen to make a laptop as opposed to the add a keyboard to a tablet to make a laptop model but a tablet without a keyboard is more useful than a non-server PC without a display. The PC as box with connections for keyboard, display, etc has a long future ahead of it. But the sizes will probably decrease (they should have stopped making PC cases to fit CD/DVD drives at least 10 years ago). The NUC size is a useful option and I think that DVD drives will stop being used for software soon which will allow a range of smaller form factors. The regular laptop is something that will remain useful, but the tablet with detachable keyboard devices could take a lot of that market. Full functionality for all tasks requires a keyboard because at the moment text editing with a touch screen is an unsolved problem in computer science [2]. The Lenovo Thinkpad X1 Fold [3] and related Lenovo products are very interesting. Advances in materials allow laptops to be thinner and lighter which leaves the screen size as a major limitation to portability. There is a conflict between desiring a large screen to see lots of content and wanting a small size to carry and making a device foldable is an obvious solution that has recently become possible. Making a foldable laptop drives a desire for not having a permanently attached keyboard which then makes a touch screen keyboard a requirement. So this means that user interfaces for PCs have to be adapted to work well on touch screens. The Think line seems to be continuing the history of innovation that it had when owned by IBM. There are also a range of other laptops that have two regular screens so they are essentially the same as the Thinkpad X1 Fold but with two separate screens instead of one folding one, prices are as low as $600US. I think that the typical interfaces for desktop PCs (EG MS-Windows and KDE) don t work well for small devices and touch devices and the Android interface generally isn t a good match for desktop systems. We need to invent more options for this. This is not a criticism of KDE, I use it every day and it works well. But it s designed for use cases that don t match new hardware that is on sale. As an aside it would be nice if Lenovo gave samples of their newest gear to people who make significant contributions to GUIs. Give a few Thinkpad Fold devices to KDE people, a few to GNOME people, and a few others to people involved in Wayland development and see how that promotes software development and future sales. We also need to adopt features from laptops and phones into desktop PCs. When voice recognition software was first released in the 90s it was for desktop PCs, it didn t take off largely because it wasn t very accurate (none of them recognised my voice). Now voice recognition in phones is very accurate and it s very common for desktop PCs to have a webcam or headset with a microphone so it s time for this to be re-visited. GPS support in laptops is obviously useful and can work via Wifi location, via a USB GPS device, or via wwan mobile phone hardware (even if not used for wwan networking). Another possibility is using the same software interfaces as used for GPS on laptops for a static definition of location for a desktop PC or server. The Interesting New Things Watch Like The wrist-watch [4] has been a standard format for easy access to data when on the go since it s military use at the end of the 19th century when the practical benefits beat the supposed femininity of the watch. So it seems most likely that they will continue to be in widespread use in computerised form for the forseeable future. For comparison smart phones have been in widespread use as pocket watches for about 10 years. The question is how will watch computers end up? Will we have Dick Tracy style watch phones that you speak into? Will it be the current smart watch functionality of using the watch to answer a call which goes to a bluetooth headset? Will smart watches end up taking over the functionality of the calculator watch [5] which was popular in the 80 s? With today s technology you could easily have a fully capable PC strapped to your forearm, would that be useful? Phone Like Folding phones (originally popularised as Star Trek Tricorders) seem likely to have a long future ahead of them. Engineering technology has only recently developed to the stage of allowing them to work the way people would hope them to work (a folding screen with no gaps). Phones and tablets with multiple folds are coming out now [6]. This will allow phones to take much of the market share that tablets used to have while tablets and laptops merge at the high end. I ve previously written about Convergence between phones and desktop computers [7], the increased capabilities of phones adds to the case for Convergence. Folding phones also provide new possibilities for the OS. The Oppo OnePlus Open and the Google Pixel Fold both have a UI based around using the two halves of the folding screen for separate data at some times. I think that the current user interfaces for desktop PCs don t properly take advantage of multiple monitors and the possibilities raised by folding phones only adds to the lack. My pet peeve with multiple monitor setups is when they don t make it obvious which monitor has keyboard focus so you send a CTRL-W or ALT-F4 to the wrong screen by mistake, it s a problem that also happens on a single screen but is worse with multiple screens. There are rumours of phones described as three fold (where three means the number of segments with two folds between them), it will be interesting to see how that goes. Will phones go the same way as PCs in terms of having a separation between the compute bit and the input device? It s quite possible to have a compute device in the phone form factor inside a secure pocket which talks via Bluetooth to another device with a display and speakers. Then you could change your phone between a phone-size display and a tablet sized display easily and when using your phone a thief would not be able to easily steal the compute bit (which has passwords etc). Could the watch part of the phone (strapped to your wrist and difficult to steal) be the active part and have a tablet size device as an external display? There are already announcements of smart watches with up to 1GB of RAM (same as the Samsung Galaxy S3), that s enough for a lot of phone functionality. The Rabbit R1 [8] and the Humane AI Pin [9] have some interesting possibilities for AI speech interfaces. Could that take over some of the current phone use? It seems that visually impaired people have been doing badly in the trend towards touch screen phones so an option of a voice interface phone would be a good option for them. As an aside I hope some people are working on AI stuff for FOSS devices. Laptop Like One interesting PC variant I just discovered is the Higole 2 Pro portable battery operated Windows PC with 5.5 touch screen [10]. It looks too thick to fit in the same pockets as current phones but is still very portable. The version with built in battery is $AU423 which is in the usual price range for low end laptops and tablets. I don t think this is the future of computing, but it is something that is usable today while we wait for foldable devices to take over. The recent release of the Apple Vision Pro [11] has driven interest in 3D and head mounted computers. I think this could be a useful peripheral for a laptop or phone but it won t be part of a primary computing environment. In 2011 I wrote about the possibility of using augmented reality technology for providing a desktop computing environment [12]. I wonder how a Vision Pro would work for that on a train or passenger jet. Another interesting thing that s on offer is a laptop with 7 touch screen beside the keyboard [13]. It seems that someone just looked at what parts are available cheaply in China (due to being parts of more popular devices) and what could fit together. I think a keyboard should be central to the monitor for serious typing, but there may be useful corner cases where typing isn t that common and a touch-screen display is of use. Developing a range of strange hardware and then seeing which ones get adopted is a good thing and an advantage of Ali Express and Temu. Useful Hardware for Developing These Things I recently bought a second hand Thinkpad X1 Yoga Gen3 for $359 which has stylus support [14], and it s generally a great little laptop in every other way. There s a common failure case of that model where touch support for fingers breaks but the stylus still works which allows it to be used for testing touch screen functionality while making it cheap. The PineTime is a nice smart watch from Pine64 which is designed to be open [15]. I am quite happy with it but haven t done much with it yet (apart from wearing it every day and getting alerts etc from Android). At $50 when delivered to Australia it s significantly more expensive than most smart watches with similar features but still a lot cheaper than the high end ones. Also the Raspberry Pi Watch [16] is interesting too. The PinePhonePro is an OK phone made to open standards but it s hardware isn t as good as Android phones released in the same year [17]. I ve got some useful stuff done on mine, but the battery life is a major issue and the screen resolution is low. The Librem 5 phone from Purism has a better hardware design for security with switches to disable functionality [18], but it s even slower than the PinePhonePro. These are good devices for test and development but not ones that many people would be excited to use every day. Wwan hardware (for accessing the phone network) in M.2 form factor can be obtained for free if you have access to old/broken laptops. Such devices start at about $35 if you want to buy one. USB GPS devices also start at about $35 so probably not worth getting if you can get a wwan device that does GPS as well. What We Must Do Debian appears to have some voice input software in the pocketsphinx package but no documentation on how it s to be used. This would be a good thing to document, I spent 15 mins looking at it and couldn t get it going. To take advantage of the hardware features in phones we need software support and we ideally don t want free software to lag too far behind proprietary software which IMHO means the typical Android setup for phones/tablets. Support for changing screen resolution is already there as is support for touch screens. Support for adapting the GUI to changed screen size is something that needs to be done even today s hardware of connecting a small laptop to an external monitor doesn t have the ideal functionality for changing the UI. There also seem to be some limitations in touch screen support with multiple screens, I haven t investigated this properly yet, it definitely doesn t work in an expected manner in Ubuntu 22.04 and I haven t yet tested the combinations on Debian/Unstable. ML is becoming a big thing and it has some interesting use cases for small devices where a smart device can compensate for limited input options. There s a lot of work that needs to be done in this area and we are limited by the fact that we can t just rip off the work of other people for use as training data in the way that corporations do. Security is more important for devices that are at high risk of theft. The vast majority of free software installations are way behind Android in terms of security and we need to address that. I have some ideas for improvement but there is always a conflict between security and usability and while Android is usable for it s own special apps it s not usable in a I want to run applications that use any files from any other applicationsin any way I want sense. My post about Sandboxing Phone apps is relevant for people who are interested in this [19]. We also need to extend security models to cope with things like ok google type functionality which has the potential to be a bug and the emerging class of LLM based attacks. I will write more posts about these thing. Please write comments mentioning FOSS hardware and software projects that address these issues and also documentation for such things.

11 March 2024

Joachim Breitner: Convenient sandboxed development environment

I like using one machine and setup for everything, from serious development work to hobby projects to managing my finances. This is very convenient, as often the lines between these are blurred. But it is also scary if I think of the large number of people who I have to trust to not want to extract all my personal data. Whenever I run a cabal install, or a fun VSCode extension gets updated, or anything like that, I am running code that could be malicious or buggy. In a way it is surprising and reassuring that, as far as I can tell, this commonly does not happen. Most open source developers out there seem to be nice and well-meaning, after all.

Convenient or it won t happen Nevertheless I thought I should do something about this. The safest option would probably to use dedicated virtual machines for the development work, with very little interaction with my main system. But knowing me, that did not seem likely to happen, as it sounded like a fair amount of hassle. So I aimed for a viable compromise between security and convenient, and one that does not get too much in the way of my current habits. For instance, it seems desirable to have the project files accessible from my unconstrained environment. This way, I could perform certain actions that need access to secret keys or tokens, but are (unlikely) to run code (e.g. git push, git pull from private repositories, gh pr create) from the outside , and the actual build environment can do without access to these secrets. The user experience I thus want is a quick way to enter a development environment where I can do most of the things I need to do while programming (network access, running command line and GUI programs), with access to the current project, but without access to my actual /home directory. I initially followed the blog post Application Isolation using NixOS Containers by Marcin Sucharski and got something working that mostly did what I wanted, but then a colleague pointed out that tools like firejail can achieve roughly the same with a less global setup. I tried to use firejail, but found it to be a bit too inflexible for my particular whims, so I ended up writing a small wrapper around the lower level sandboxing tool https://github.com/containers/bubblewrap.

Selective bubblewrapping This script, called dev and included below, builds a new filesystem namespace with minimal /proc and /dev directories, it s own /tmp directories. It then binds-mound some directories to make the host s NixOS system available inside the container (/bin, /usr, the nix store including domain socket, stuff for OpenGL applications). My user s home directory is taken from ~/.dev-home and some configuration files are bind-mounted for convenient sharing. I intentionally don t share most of the configuration for example, a direnv enable in the dev environment should not affect the main environment. The X11 socket for graphical applications and the corresponding .Xauthority file is made available. And finally, if I run dev in a project directory, this project directory is bind mounted writable, and the current working directory is preserved. The effect is that I can type dev on the command line to enter dev mode rather conveniently. I can run development tools, including graphical ones like VSCode, and especially the latter with its extensions is part of the sandbox. To do a git push I either exit the development environment (Ctrl-D) or open a separate terminal. Overall, the inconvenience of switching back and forth seems worth the extra protection. Clearly, isn t going to hold against a determined and maybe targeted attacker (e.g. access to the X11 and the nix daemon socket can probably be used to escape easily). But I hope it will help against a compromised dev dependency that just deletes or exfiltrates data, like keys or passwords, from the usual places in $HOME.

Rough corners There is more polishing that could be done.
  • In particular, clicking on a link inside VSCode in the container will currently open Firefox inside the container, without access to my settings and cookies etc. Ideally, links would be opened in the Firefox running outside. This is a problem that has a solution in the world of applications that are sandboxed with Flatpak, and involves a bunch of moving parts (a xdg-desktop-portal user service, a filtering dbus proxy, exposing access to that proxy in the container). I experimented with that for a bit longer than I should have, but could not get it to work to satisfaction (even without a container involved, I could not get xdg-desktop-portal to heed my default browser settings ). For now I will live with manually copying and pasting URLs, we ll see how long this lasts.
  • With this setup (and unlike the NixOS container setup I tried first), the same applications are installed inside and outside. It might be useful to separate the set of installed programs: There is simply no point in running evolution or firefox inside the container, and if I do not even have VSCode or cabal available outside, so that it s less likely that I forget to enter dev before using these tools. It shouldn t be too hard to cargo-cult some of the NixOS Containers infrastructure to be able to have a separate system configuration that I can manage as part of my normal system configuration and make available to bubblewrap here.
So likely I will refine this some more over time. Or get tired of typing dev and going back to what I did before

The script
The dev script (at the time of writing)

9 March 2024

Reproducible Builds: Reproducible Builds in February 2024

Welcome to the February 2024 report from the Reproducible Builds project! In our reports, we try to outline what we have been up to over the past month as well as mentioning some of the important things happening in software supply-chain security.

Reproducible Builds at FOSDEM 2024 Core Reproducible Builds developer Holger Levsen presented at the main track at FOSDEM on Saturday 3rd February this year in Brussels, Belgium. However, that wasn t the only talk related to Reproducible Builds. However, please see our comprehensive FOSDEM 2024 news post for the full details and links.

Maintainer Perspectives on Open Source Software Security Bernhard M. Wiedemann spotted that a recent report entitled Maintainer Perspectives on Open Source Software Security written by Stephen Hendrick and Ashwin Ramaswami of the Linux Foundation sports an infographic which mentions that 56% of [polled] projects support reproducible builds .

Mailing list highlights From our mailing list this month:

Distribution work In Debian this month, 5 reviews of Debian packages were added, 22 were updated and 8 were removed this month adding to Debian s knowledge about identified issues. A number of issue types were updated as well. [ ][ ][ ][ ] In addition, Roland Clobus posted his 23rd update of the status of reproducible ISO images on our mailing list. In particular, Roland helpfully summarised that all major desktops build reproducibly with bullseye, bookworm, trixie and sid provided they are built for a second time within the same DAK run (i.e. [within] 6 hours) and that there will likely be further work at a MiniDebCamp in Hamburg. Furthermore, Roland also responded in-depth to a query about a previous report
Fedora developer Zbigniew J drzejewski-Szmek announced a work-in-progress script called fedora-repro-build that attempts to reproduce an existing package within a koji build environment. Although the projects README file lists a number of fields will always or almost always vary and there is a non-zero list of other known issues, this is an excellent first step towards full Fedora reproducibility.
Jelle van der Waa introduced a new linter rule for Arch Linux packages in order to detect cache files leftover by the Sphinx documentation generator which are unreproducible by nature and should not be packaged. At the time of writing, 7 packages in the Arch repository are affected by this.
Elsewhere, Bernhard M. Wiedemann posted another monthly update for his work elsewhere in openSUSE.

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 256, 257 and 258 to Debian and made the following additional changes:
  • Use a deterministic name instead of trusting gpg s use-embedded-filenames. Many thanks to Daniel Kahn Gillmor dkg@debian.org for reporting this issue and providing feedback. [ ][ ]
  • Don t error-out with a traceback if we encounter struct.unpack-related errors when parsing Python .pyc files. (#1064973). [ ]
  • Don t try and compare rdb_expected_diff on non-GNU systems as %p formatting can vary, especially with respect to MacOS. [ ]
  • Fix compatibility with pytest 8.0. [ ]
  • Temporarily fix support for Python 3.11.8. [ ]
  • Use the 7zip package (over p7zip-full) after a Debian package transition. (#1063559). [ ]
  • Bump the minimum Black source code reformatter requirement to 24.1.1+. [ ]
  • Expand an older changelog entry with a CVE reference. [ ]
  • Make test_zip black clean. [ ]
In addition, James Addison contributed a patch to parse the headers from the diff(1) correctly [ ][ ] thanks! And lastly, Vagrant Cascadian pushed updates in GNU Guix for diffoscope to version 255, 256, and 258, and updated trydiffoscope to 67.0.6.

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, Vagrant Cascadian made a number of changes, including:
  • Create a (working) proof of concept for enabling a specific number of CPUs. [ ][ ]
  • Consistently use 398 days for time variation rather than choosing randomly and update README.rst to match. [ ][ ]
  • Support a new --vary=build_path.path option. [ ][ ][ ][ ]

Website updates There were made a number of improvements to our website this month, including:

Reproducibility testing framework The Reproducible Builds project operates a comprehensive testing framework (available at tests.reproducible-builds.org) in order to check packages and other artifacts for reproducibility. In February, a number of changes were made by Holger Levsen:
  • Debian-related changes:
    • Temporarily disable upgrading/bootstrapping Debian unstable and experimental as they are currently broken. [ ][ ]
    • Use the 64-bit amd64 kernel on all i386 nodes; no more 686 PAE kernels. [ ]
    • Add an Erlang package set. [ ]
  • Other changes:
    • Grant Jan-Benedict Glaw shell access to the Jenkins node. [ ]
    • Enable debugging for NetBSD reproducibility testing. [ ]
    • Use /usr/bin/du --apparent-size in the Jenkins shell monitor. [ ]
    • Revert reproducible nodes: mark osuosl2 as down . [ ]
    • Thanks again to Codethink, for they have doubled the RAM on our arm64 nodes. [ ]
    • Only set /proc/$pid/oom_score_adj to -1000 if it has not already been done. [ ]
    • Add the opemwrt-target-tegra and jtx task to the list of zombie jobs. [ ][ ]
Vagrant Cascadian also made the following changes:
  • Overhaul the handling of OpenSSH configuration files after updating from Debian bookworm. [ ][ ][ ]
  • Add two new armhf architecture build nodes, virt32z and virt64z, and insert them into the Munin monitoring. [ ][ ] [ ][ ]
In addition, Alexander Couzens updated the OpenWrt configuration in order to replace the tegra target with mpc85xx [ ], Jan-Benedict Glaw updated the NetBSD build script to use a separate $TMPDIR to mitigate out of space issues on a tmpfs-backed /tmp [ ] and Zheng Junjie added a link to the GNU Guix tests [ ]. Lastly, node maintenance was performed by Holger Levsen [ ][ ][ ][ ][ ][ ] and Vagrant Cascadian [ ][ ][ ][ ].

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:

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:

8 March 2024

Valhalla's Things: Denim Waistcoat

Posted on March 8, 2024
Tags: madeof:atoms, craft:sewing, FreeSoftWear
A woman wearing a single breasted waistcoat with double darts at the waist, two pocket flaps at the waist and one on the left upper breast. It has four jeans buttons. I had finished sewing my jeans, I had a scant 50 cm of elastic denim left. Unrelated to that, I had just finished drafting a vest with Valentina, after the Cutters Practical Guide to the Cutting of Ladies Garments. A new pattern requires a (wearable) mockup. 50 cm of leftover fabric require a quick project. The decision didn t take a lot of time. As a mockup, I kept things easy: single layer with no lining, some edges finished with a topstitched hem and some with bias tape, and plain tape on the fronts, to give more support to the buttons and buttonholes. I did add pockets: not real welt ones (too much effort on denim), but simple slits covered by flaps. a rectangle of pocketing fabric on the wrong side of a denim
piece; there is a slit in the middle that has been finished with topstitching.
To do them I marked the slits, then I cut two rectangles of pocketing fabric that should have been as wide as the slit + 1.5 cm (width of the pocket) + 3 cm (allowances) and twice the sum of as tall as I wanted the pocket to be plus 1 cm (space above the slit) + 1.5 cm (allowances). Then I put the rectangle on the right side of the denim, aligned so that the top edge was 2.5 cm above the slit, sewed 2 mm from the slit, cut, turned the pocketing to the wrong side, pressed and topstitched 2 mm from the fold to finish the slit. a piece of pocketing fabric folded in half and sewn on all 3
other sides; it does not lay flat on the right side of the fabric because the finished slit (hidden in the picture) is pulling it.
Then I turned the pocketing back to the right side, folded it in half, sewed the side and top seams with a small allowance, pressed and turned it again to the wrong side, where I sewed the seams again to make a french seam. And finally, a simple rectangular denim flap was topstitched to the front, covering the slits. I wasn t as precise as I should have been and the pockets aren t exactly the right size, but they will do to see if I got the positions right (I think that the breast one should be a cm or so lower, the waist ones are fine), and of course they are tiny, but that s to be expected from a waistcoat. The back of the waistcoat, The other thing that wasn t exactly as expected is the back: the pattern splits the bottom part of the back to give it sufficient spring over the hips . The book is probably published in 1892, but I had already found when drafting the foundation skirt that its idea of hips includes a bit of structure. The enough steel to carry a book or a cup of tea kind of structure. I should have expected a lot of spring, and indeed that s what I got. To fit the bottom part of the back on the limited amount of fabric I had to piece it, and I suspect that the flat felled seam in the center is helping it sticking out; I don t think it s exactly bad, but it is a peculiar look. Also, I had to cut the back on the fold, rather than having a seam in the middle and the grain on a different angle. Anyway, my next waistcoat project is going to have a linen-cotton lining and silk fashion fabric, and I d say that the pattern is good enough that I can do a few small fixes and cut it directly in the lining, using it as a second mockup. As for the wrinkles, there is quite a bit, but it looks something that will be solved by a bit of lightweight boning in the side seams and in the front; it will be seen in the second mockup and the finished waistcoat. As for this one, it s definitely going to get some wear as is, in casual contexts. Except. Well, it s a denim waistcoat, right? With a very different cut from the get a denim jacket and rip out the sleeves , but still a denim waistcoat, right? The kind that you cover in patches, right? Outline of a sewing machine with teeth and crossed bones below it, and the text  home sewing is killing fashion / and it's illegal And I may have screenprinted a home sewing is killing fashion patch some time ago, using the SVG from wikimedia commons / the Home Taping is Killing Music page. And. Maybe I ll wait until I have finished the real waistcoat. But I suspect that one, and other sewing / costuming patches may happen in the future. No regrets, as the words on my seam ripper pin say, right? :D

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