Search Results: "beh"

23 March 2022

Matthew Garrett: AMD's Pluton implementation seems to be controllable

I've been digging through the firmware for an AMD laptop with a Ryzen 6000 that incorporates Pluton for the past couple of weeks, and I've got some rough conclusions. Note that these are extremely preliminary and may not be accurate, but I'm going to try to encourage others to look into this in more detail. For those of you at home, I'm using an image from here, specifically version 309. The installer is happy to run under Wine, and if you tell it to "Extract" rather than "Install" it'll leave a file sitting in C:\\DRIVERS\ASUS_GA402RK_309_BIOS_Update_20220322235241 which seems to have an additional 2K of header on it. Strip that and you should have something approximating a flash image.

Looking for UTF16 strings in this reveals something interesting:

Pluton (HSP) X86 Firmware Support
Enable/Disable X86 firmware HSP related code path, including AGESA HSP module, SBIOS HSP related drivers.
Auto - Depends on PcdAmdHspCoreEnable build value
NOTE: PSP directory entry 0xB BIT36 have the highest priority.
NOTE: This option will NOT put HSP hardware in disable state, to disable HSP hardware, you need setup PSP directory entry 0xB, BIT36 to 1.
// EntryValue[36] = 0: Enable, HSP core is enabled.
// EntryValue[36] = 1: Disable, HSP core is disabled then PSP will gate the HSP clock, no further PSP to HSP commands. System will boot without HSP.

"HSP" here means "Hardware Security Processor" - a generic term that refers to Pluton in this case. This is a configuration setting that determines whether Pluton is "enabled" or not - my interpretation of this is that it doesn't directly influence Pluton, but disables all mechanisms that would allow the OS to communicate with it. In this scenario, Pluton has its firmware loaded and could conceivably be functional if the OS knew how to speak to it directly, but the firmware will never speak to it itself. I took a quick look at the Windows drivers for Pluton and it looks like they won't do anything unless the firmware wants to expose Pluton, so this should mean that Windows will do nothing.

So what about the reference to "PSP directory entry 0xB BIT36 have the highest priority"? The PSP is the AMD Platform Security Processor - it's an ARM core on the CPU package that boots before the x86. The PSP firmware lives in the same flash image as the x86 firmware, so the PSP looks for a header that points it towards the firmware it should execute. This gives a pointer to a "directory" - a list of different object types and where they're located in flash (there's a description of this for slightly older AMDs here). Type 0xb is treated slightly specially. Where most types contain the address of where the actual object is, type 0xb contains a 64-bit value that's interpreted as enabling or disabling various features - something AMD calls "soft fusing" (Intel have something similar that involves setting bits in the Firmware Interface Table). The PSP looks at the bits that are set here and alters its behaviour. If bit 36 is set, the PSP tells Pluton to turn itself off and will no longer send any commands to it.

So, we have two mechanisms to disable Pluton - the PSP can tell it to turn itself off, or the x86 firmware can simply never speak to it or admit that it exists. Both of these imply that Pluton has started executing before it's shut down, so it's reasonable to wonder whether it can still do stuff. In the image I'm looking at, there's a blob starting at 0x0069b610 that appears to be firmware for Pluton - it contains chunks that appear to be the reference TPM2 implementation, and it broadly decompiles as valid ARM code. It should be viable to figure out whether it can do anything in the face of being "disabled" via either of the above mechanisms.

Unfortunately for me, the system I'm looking at does set bit 36 in the 0xb entry - as a result, Pluton is disabled before x86 code starts running and I can't investigate further in any straightforward way. The implication that the user-controllable mechanism for disabling Pluton merely disables x86 communication with it rather than turning it off entirely is a little concerning, although (assuming Pluton is behaving as a TPM rather than having an enhanced set of capabilities) skipping any firmware communication means the OS has no way to know what happened before it started running even if it has a mechanism to communicate with Pluton without firmware assistance. In that scenario it'd be viable to write a bootloader shim that just faked up the firmware measurements before handing control to the OS.

The bit 36 disabling mechanism seems more solid? Again, it should be possible to analyse the Pluton firmware to determine whether it actually pays attention to a disable command being sent. But even if it chooses to ignore that, if the PSP is in a position to just cut the clock to Pluton, it's not going to be able to do a lot. At that point we're trusting AMD rather than trusting Microsoft, but given that you're also trusting AMD to execute the code you're giving them to execute, it's hard to avoid placing trust in them.

Overall: I'm reasonably confident that systems that ship with Pluton disabled via setting bit 36 in the soft fuses are going to disable it sufficiently hard that the OS can't do anything about it. Systems that give the user an option to enable or disable it are a little less clear in that respect, and it's possible (but not yet demonstrated) that an OS could communicate with Pluton anyway. However, if that's true, and if the firmware never communicates with Pluton itself, the user could install a stub loader in UEFI that mimicks the firmware behaviour and leaves the OS thinking everything was good when it absolutely is not.

So, assuming that Pluton in its current form on AMD has no capabilities outside those we know about, the disabling mechanisms are probably good enough. It's tough to make a firm statement on this before I have access to a system that doesn't just disable it immediately, so stay tuned for updates.

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20 March 2022

Joerg Jaspert: Another shell script moved to rust

Shell? Rust! Not the first shell script I took and made a rust version of, but probably my largest yet. This time I took my little tm (tmux helper) tool which is (well, was) a bit more than 600 lines of shell, and converted it to Rust. I got most of the functionality done now, only one major part is missing.

What s tm? tm started as a tiny shell script to make handling tmux easier. The first commit in git was in July 2013, but I started writing and using it in 2011. It started out as a kind-of wrapper around ssh, opening tmux windows with an ssh session on some other hosts. It quickly gained support to open multiple ssh sessions in one window, telling tmux to synchronize input (send input to all targets at once), which is great when you have a set of machines that ought to get the same commands.

tm vs clusterssh / mussh In spirit it is similar to clusterssh or mussh, allowing to run the same command on many hosts at the same time. clusterssh sets out to open new terminals (xterm) per host and gives you an input line, that it sends everywhere. mussh appears to take your command and then send it to all the hosts. Both have disadvantages in my opinion: clusterssh opens lots of xterm windows, and you can not easily switch between multiple sessions, mussh just seems to send things over ssh and be done. tm instead just creates a tmux session, telling it to ssh to the targets, possibly setting the tmux option to send input to all panes. And leaves all the rest of the handling to tmux. So you can
  • detach a session and reattach later easily,
  • use tmux great builtin support for copy/paste,
  • see all output, modify things even for one machine only,
  • zoom in to one machine that needs just ONE bit different (cssh can do this too),
  • let colleagues also connect to your tmux session, when needed,
  • easily add more machines to the mix, if needed,
  • and all the other extra features tmux brings.

More tm tm also supports just attaching to existing sessions as well as killing sessions, mostly for lazyness (less to type than using tmux directly). At some point tm gained support for setting up sessions according to some session file . It knows two formats now, one is simple and mostly a list of hostnames to open synchronized sessions for. This may contain LIST commands, which let tm execute that command, expected output is list of hostnames (or more LIST commands) for the session. That, combined with the replacement part, lets us have one config file that opens a set of VMs based on tags our Ganeti runs, based on tags. It is simply a LIST command asking for VMs tagged with the replacement arg and up. Very handy. Or also all VMs on host X . The second format is basically free form tmux commands . Mostly commandline tmux call, just drop the tmux in front collection. Both of them supporting a crude variable replacement.

Conversion to Rust Some while ago I started playing with Rust and it somehow clicked , I do like it. My local git tells me, that I tried starting off with go in 2017, but that appearently did not work out. Fun, everywhere I can read says that Rust ought to be harder to learn. So by now I have most of the functionality implemented in the Rust version, even if I am sure that the code isn t a good Rust example. I m learning, after all, and already have adjusted big parts of it, multiple times, whenever I learn (and understand) something more - and am also sure that this will happen again

Compatibility with old tm It turns out that my goal of staying compatible with the behaviour of the old shell script does make some things rather complicated. For example, the LIST commands in session config files - in shell I just execute them commands, and shell deals with variable/parameter expansion, I just set IFS to newline only and read in what I get back. Simple. Because shell is doing a lot of things for me. Now, in Rust, it is a different thing at all:
  • Properly splitting the line into shell words, taking care of quoting (can t simply take whitespace) (there is shlex)
  • Expanding specials like ~ and $HOME (there is home_dir).
  • Supporting environment variables in general, tm has some that adjust behaviour of it. Which shell can use globally. Used lazy_static for a similar effect - they aren t going to change at runtime ever, anyways.
Properly supporting the commandline arguments also turned out to be a bit more work. Rust appearently has multiple crates supporting this, I settled on clap, but as tm supports getopts -style as well as free-form arguments (subcommands in clap), it takes a bit to get that interpreted right.

Speed Most of the time entirely unimportant in the tool that tm is (open a tmux with one to some ssh connections to some places is not exactly hard or time consuming), there are situations, where one can notice that it s calling out to tmux over and over again, for every single bit to do, and that just takes time: Configurations that open sessions to 20 and more hosts at the same time especially lag in setup time. (My largest setup goes to 443 panes in one window). The compiled Rust version is so much faster there, it s just great. Nice side effect, that is. And yes, in the end it is also only driving tmux, still, it takes less than half the time to do so.

Code, Fun parts As this is still me learning to write Rust, I am sure the code has lots to improve. Some of which I will sure find on my own, but if you have time, I love PRs (or just mails with hints).

Github Also the first time I used Github Actions to see how it goes. Letting it build, test, run clippy and also run a code coverage tool (Yay, more than 50% covered ) on it. Unsure my tests are good, I am not used to writing tests for code, but hey, coverage!

Up next I do have to implement the last missing feature, which is reading the other config file format. A little scared, as that means somehow translating those lines into correct calls within the tmux_interface I am using, not sure that is easy. I could be bad and just shell out to tmux on it all the time, but somehow I don t like the thought of doing that. Maybe (ab)using the control mode, but then, why would I use tmux_interface, so trying to handle it with that first. Afterwards I want to gain a new command, to save existing sessions and be able to recreate them easily. Shouldn t be too hard, tmux has a way to get at that info, somewhere.

15 March 2022

Kunal Mehta: How to mirror the Russian Wikipedia with Debian and Kiwix

It has been reported that the Russian government has threatened to block access to Wikipedia for documenting narratives that do not agree with the official position of the Russian government. One of the anti-censorship strategies I've been working on is Kiwix, an offline Wikipedia reader (and plenty of other content too). Kiwix is free and open source software developed by a great community of people that I really enjoy working with. With threats of censorship, traffic to Kiwix has increased fifty-fold, with users from Russia accounting for 40% of new downloads! You can download copies of every language of Wikipedia for offline reading and distribution, as well as hosting your own read-only mirror, which I'm going to explain today. Disclaimer: depending on where you live it may be illegal or get you in trouble with the authorities to rehost Wikipedia content, please be aware of your digital and physical safety before proceeding. With that out of the way, let's get started. You'll need a Debian (or Ubuntu) server with at least 30GB of free disk space. You'll also want to have a webserver like Apache or nginx installed (I'll share the Apache config here). First, we need to download the latest copy of the Russian Wikipedia.
$ wget 'https://download.kiwix.org/zim/wikipedia/wikipedia_ru_all_maxi_2022-03.zim'
If the download is interrupted or fails, you can use wget -c $url to resume it. Next let's install kiwix-serve and try it out. If you're using Ubuntu, I strongly recommend enabling our Kiwix PPA first.
$ sudo apt update
$ sudo apt install kiwix-tools
$ kiwix-serve -p 3004 wikipedia_ru_all_maxi_2022-03.zim
At this point you should be able to visit http://yourserver.com:3004/ and see the Russian Wikipedia. Awesome! You can use any available port, I just picked 3004. Now let's use systemd to daemonize it so it runs in the background. Create /etc/systemd/system/kiwix-ru-wp.service with the following:
[Unit]
Description=Kiwix Russian Wikipedia
[Service]
Type=simple
User=www-data
ExecStart=/usr/bin/kiwix-serve -p 3004 /path/to/wikipedia_ru_all_maxi_2022-03.zim
Restart=always
[Install]
WantedBy=multi-user.target
Now let's start it and enable it at boot:
$ sudo systemctl start kiwix-ru-wp
$ sudo systemctl enable kiwix-ru-wp
Since we want to expose this on the public internet, we should put it behind a more established webserver and configure HTTPS. Here's the Apache httpd configuration I used:
<VirtualHost *:80>
        ServerName ru-wp.yourserver.com
        ServerAdmin webmaster@localhost
        DocumentRoot /var/www/html
        ErrorLog $ APACHE_LOG_DIR /error.log
        CustomLog $ APACHE_LOG_DIR /access.log combined
        <Proxy *>
                Require all granted
        </Proxy>
        ProxyPass / http://127.0.0.1:3004/
        ProxyPassReverse / http://127.0.0.1:3004/
</VirtualHost>
Put that in /etc/apache2/sites-available/kiwix-ru-wp.conf and run:
$ sudo a2ensite kiwix-ru-wp
$ sudo systemctl reload apache2
Finally, I used certbot to enable HTTPS on that subdomain and redirect all HTTP traffic over to HTTPS. This is an interactive process that is well documented so I'm not going to go into it in detail. You can see my mirror of the Russian Wikipedia, following these instructions, at https://ru-wp.legoktm.com/. Anyone is welcome to use it or distribute the link, though I am not committing to running it long-term. This is certainly not a perfect anti-censorship solution, the copy of Wikipedia that Kiwix provides became out of date the moment it was created, and the setup described here will require you to manually update the service when the new copy is available next month. Finally, if you have some extra bandwith, you can also help seed this as a torrent.

9 March 2022

Jonathan Dowland: Broken webcam aspect ratio

picture of my Sony RX100-III camera Sony RX100-III, relegated to a webcam
Sometimes I have remote meetings with Google Meet. Unlike the other video-conferencing services that I use (Bluejeans, Zoom), my video was stretched out of proportion under Google Meet with Firefox. I haven't found out why this was happening, but I did figure out a work-around. Thanks to Daniel Silverstone, Rob Kendrick, Gregor Herrmann and Ben Allen for pointing me in the right direction! Hardware The lovely Sony RX-100 mk3 that I bought in 2015 has spent most of its life languishing unused. During the Pandemic, once I was working from home all the time, I decided to press-gang it into service as a better-quality webcam. Newer models of this camera the mark 4 onwards have support for a USB mode called "PC Remote", which effectively makes them into webcams. Unfortunately my mark 3 does not support this, but it does have HDMI out, so I picked up a cheap "HDMI to USB Video Capture Card" from eBay. Video modes
Before: wrong aspect ratio Before: wrong aspect ratio
This device offers a selection of different video modes over a webcam interface. I used qv4l2 to explore the different modes. It became clear that the camera was outputting a signal at 16:9, but the modes on offer from the dongle were for a range of different aspect ratios. The picture for these other ratios was not letter or pillar-boxed, but stretched to fit. I also noticed that the modes which had the correct aspect ratio were at very low framerates: 1920x1080@5fps, 1360x768@8fps, 1280x720@10fps. It felt to me that I would look unnatural at such a low framerate. The most promising mode was close to the right ratio, 720x480 and 30 fps. Software
After: corrected aspect ratio After: corrected aspect ratio
My initial solution is to use the v4l2loopback kernel module, which provides a virtual loop-back webcam interface. I can write video data to it from one process, and read it back from another. Loading it as follows:
modprobe v4l2loopback exclusive_caps=1
The option exclusive_caps configures the module into a mode where it initially presents a write-only interface, but once a process has opened a file handle, it then switches to read-only for subsequent processes. Assuming there are no other camera devices connected at the time of loading the module, it will create /dev/video0.1 I experimented briefly with OBS Studio, the very versatile and feature-full streaming tool, which confirmed that I could use filters on the source video to fix the aspect ratio, and emit the result to the virtual device. I don't otherwise use OBS, though, so I achieve the same result using ffmpeg:
fmpeg -s 720x480 -i /dev/video1 -r 30 -f v4l2 -vcodec rawvideo \
    -pix_fmt yuyv422 -s 720x405 /dev/video0
The source options are to select the source video mode I want. The codec and pixel formats are to match what is being emitted (I determined that using ffprobe on the camera device). The resizing is triggered by supplying a different size to the -s parameter. I think that is equivalent to explicitly selecting a "scale" filter, and there might be other filters that could be used instead (to add pillar boxes for example). This worked just as well. In Google Meet, I select the Virtual Camera, and Google Meet is presented with only one video mode, in the correct aspect ratio, and no configurable options for it, so it can't misbehave. Future I'm planning to automate the loading (and unloading) of the module and starting the ffmpeg process in response to the real camera device being plugged or unplugged, using systemd events and services. (I don't leave the camera plugged in all the time due to some bad USB behaviour I've experienced if I do so.) If I get that working, I will write a follow-up.

  1. you can request a specific device name/number with another module option.

2 March 2022

Antoine Beaupr : procmail considered harmful

TL;DR: procmail is a security liability and has been abandoned upstream for the last two decades. If you are still using it, you should probably drop everything and at least remove its SUID flag. There are plenty of alternatives to chose from, and conversion is a one-time, acceptable trade-off.

Procmail is unmaintained procmail is unmaintained. The "Final release", according to Wikipedia, dates back to September 10, 2001 (3.22). That release was shipped in Debian since then, all the way back from Debian 3.0 "woody", twenty years ago. Debian also ships 25 uploads on top of this, with 3.22-21 shipping the "3.23pre" release that has been rumored since at least the November 2001, according to debian/changelog at least:
procmail (3.22-1) unstable; urgency=low
  * New upstream release, which uses the  standard' format for Maildir
    filenames and retries on name collision. It also contains some
    bug fixes from the 3.23pre snapshot dated 2001-09-13.
  * Removed  sendmail' from the Recommends field, since we already
    have  exim' (the default Debian MTA) and  mail-transport-agent'.
  * Removed suidmanager support. Conflicts: suidmanager (<< 0.50).
  * Added support for DEB_BUILD_OPTIONS in the source package.
  * README.Maildir: Do not use locking on the example recipe,
    since it's wrong to do so in this case.
 -- Santiago Vila <sanvila@debian.org>  Wed, 21 Nov 2001 09:40:20 +0100
All Debian suites from buster onwards ship the 3.22-26 release, although the maintainer just pushed a 3.22-27 release to fix a seven year old null pointer dereference, after this article was drafted. Procmail is also shipped in all major distributions: Fedora and its derivatives, Debian derivatives, Gentoo, Arch, FreeBSD, OpenBSD. We all seem to be ignoring this problem. The upstream website (http://procmail.org/) has been down since about 2015, according to Debian bug #805864, with no change since. In effect, every distribution is currently maintaining its fork of this dead program. Note that, after filing a bug to keep Debian from shipping procmail in a stable release again, I was told that the Debian maintainer is apparently in contact with the upstream. And, surprise! they still plan to release that fabled 3.23 release, which has been now in "pre-release" for all those twenty years. In fact, it turns out that 3.23 is considered released already, and that the procmail author actually pushed a 3.24 release, codenamed "Two decades of fixes". That amounts to 25 commits since 3.23pre some of which address serious security issues, but none of which address fundamental issues with the code base.

Procmail is insecure By default, procmail is installed SUID root:mail in Debian. There's no debconf or pre-seed setting that can change this. There has been two bug reports against the Debian to make this configurable (298058, 264011), but both were closed to say that, basically, you should use dpkg-statoverride to change the permissions on the binary. So if anything, you should immediately run this command on any host that you have procmail installed on:
dpkg-statoverride --update --add root root 0755 /usr/bin/procmail
Note that this might break email delivery. It might also not work at all, thanks to usrmerge. Not sure. Yes, everything is on fire. This is fine. In my opinion, even assuming we keep procmail in Debian, that default should be reversed. It should be up to people installing procmail to assign it those dangerous permissions, after careful consideration of the risk involved. The last maintainer of procmail explicitly advised us (in that null pointer dereference bug) and other projects (e.g. OpenBSD, in [2]) to stop shipping it, back in 2014. Quote:
Executive summary: delete the procmail port; the code is not safe and should not be used as a basis for any further work.
I just read some of the code again this morning, after the original author claimed that procmail was active again. It's still littered with bizarre macros like:
#define bit_set(name,which,value) \
  (value?(name[bit_index(which)] =bit_mask(which)):\
  (name[bit_index(which)]&=~bit_mask(which)))
... from regexp.c, line 66 (yes, that's a custom regex engine). Or this one:
#define jj  (aleps.au.sopc)
It uses insecure functions like strcpy extensively. malloc() is thrown around gotos like it's 1984 all over again. (To be fair, it has been feeling like 1984 a lot lately, but that's another matter entirely.) That null pointer deref bug? It's fixed upstream now, in this commit merged a few hours ago, which I presume might be in response to my request to remove procmail from Debian. So while that's nice, this is the just tip of the iceberg. I speculate that one could easily find an exploitable crash in procmail if only by running it through a fuzzer. But I don't need to speculate: procmail had, for years, serious security issues that could possibly lead to root privilege escalation, remotely exploitable if procmail is (as it's designed to do) exposed to the network. Maybe I'm overreacting. Maybe the procmail author will go through the code base and do a proper rewrite. But I don't think that's what is in the cards right now. What I expect will happen next is that people will start fuzzing procmail, throw an uncountable number of bug reports at it which will get fixed in a trickle while never fixing the underlying, serious design flaws behind procmail.

Procmail has better alternatives The reason this is so frustrating is that there are plenty of modern alternatives to procmail which do not suffer from those problems. Alternatives to procmail(1) itself are typically part of mail servers. For example, Dovecot has its own LDA which implements the standard Sieve language (RFC 5228). (Interestingly, Sieve was published as RFC 3028 in 2001, before procmail was formally abandoned.) Courier also has "maildrop" which has its own filtering mechanism, and there is fdm (2007) which is a fetchmail and procmail replacement. Update: there's also mailprocessing, which is not an LDA, but processing an existing folder. It was, however, specifically designed to replace complex Procmail rules. But procmail, of course, doesn't just ship procmail; that would just be too easy. It ships mailstat(1) which we could probably ignore because it only parses procmail log files. But more importantly, it also ships:
  • lockfile(1) - conditional semaphore-file creator
  • formail(1) - mail (re)formatter
lockfile(1) already has a somewhat acceptable replacement in the form of flock(1), part of util-linux (which is Essential, so installed on any normal Debian system). It might not be a direct drop-in replacement, but it should be close enough. formail(1) is similar: the courier maildrop package ships reformail(1) which is, presumably, a rewrite of formail. It's unclear if it's a drop-in replacement, but it should probably possible to port uses of formail to it easily.
Update: the maildrop package ships a SUID root binary (two, even). So if you want only reformail(1), you might want to disable that with:
dpkg-statoverride --update --add root root 0755 /usr/bin/lockmail.maildrop 
dpkg-statoverride --update --add root root 0755 /usr/bin/maildrop
It would be perhaps better to have reformail(1) as a separate package, see bug 1006903 for that discussion.
The real challenge is, of course, migrating those old .procmailrc recipes to Sieve (basically). I added a few examples in the appendix below. You might notice the Sieve examples are easier to read, which is a nice added bonus.

Conclusion There is really, absolutely, no reason to keep procmail in Debian, nor should it be used anywhere at this point. It's a great part of our computing history. May it be kept forever in our museums and historical archives, but not in Debian, and certainly not in actual release. It's just a bomb waiting to go off. It is irresponsible for distributions to keep shipping obsolete and insecure software like this for unsuspecting users. Note that I am grateful to the author, I really am: I used procmail for decades and it served me well. But now, it's time to move, not bring it back from the dead.

Appendix

Previous work It's really weird to have to write this blog post. Back in 2016, I rebuilt my mail setup at home and, to my horror, discovered that procmail had been abandoned for 15 years at that point, thanks to that LWN article from 2010. I would have thought that I was the only weirdo still running procmail after all those years and felt kind of embarrassed to only "now" switch to the more modern (and, honestly, awesome) Sieve language. But no. Since then, Debian shipped three major releases (stretch, buster, and bullseye), all with the same vulnerable procmail release. Then, in early 2022, I found that, at work, we actually had procmail installed everywhere, possibly because userdir-ldap was using it for lockfile until 2019. I sent a patch to fix that and scrambled to remove get rid of procmail everywhere. That took about a day. But many other sites are now in that situation, possibly not imagining they have this glaring security hole in their infrastructure.

Procmail to Sieve recipes I'll collect a few Sieve equivalents to procmail recipes here. If you have any additions, do contact me. All Sieve examples below assume you drop the file in ~/.dovecot.sieve.

deliver mail to "plus" extension folder Say you want to deliver user+foo@example.com to the folder foo. You might write something like this in procmail:
MAILDIR=$HOME/Maildir/
DEFAULT=$MAILDIR
LOGFILE=$HOME/.procmail.log
VERBOSE=off
EXTENSION=$1            # Need to rename it - ?? does not like $1 nor 1
:0
* EXTENSION ?? [a-zA-Z0-9]+
        .$EXTENSION/
That, in sieve language, would be:
require ["variables", "envelope", "fileinto", "subaddress"];
########################################################################
# wildcard +extension
# https://doc.dovecot.org/configuration_manual/sieve/examples/#plus-addressed-mail-filtering
if envelope :matches :detail "to" "*"  
  # Save name in $ name  in all lowercase
  set :lower "name" "$ 1 ";
  fileinto "$ name ";
  stop;
 

Subject into folder This would file all mails with a Subject: line having FreshPorts in it into the freshports folder, and mails from alternc.org mailing lists into the alternc folder:
:0
## mailing list freshports
* ^Subject.*FreshPorts.*
.freshports/
:0
## mailing list alternc
* ^List-Post.*mailto:.*@alternc.org.*
.alternc/
Equivalent Sieve:
if header :contains "subject" "FreshPorts"  
    fileinto "freshports";
  elsif header :contains "List-Id" "alternc.org"  
    fileinto "alternc";
 

Mail sent to root to a reports folder This double rule:
:0
* ^Subject: Cron
* ^From: .*root@
.rapports/
Would look something like this in Sieve:
if header :comparator "i;octet" :contains "Subject" "Cron"  
  if header :regex :comparator "i;octet"  "From" ".*root@"  
        fileinto "rapports";
   
 
Note that this is what the automated converted does (below). It's not very readable, but it works.

Bulk email I didn't have an equivalent of this in procmail, but that's something I did in Sieve:
if header :contains "Precedence" "bulk"  
    fileinto "bulk";
 

Any mailing list This is another rule I didn't have in procmail but I found handy and easy to do in Sieve:
if exists "List-Id"  
    fileinto "lists";
 

This or that I wouldn't remember how to do this in procmail either, but that's an easy one in Sieve:
if anyof (header :contains "from" "example.com",
           header :contains ["to", "cc"] "anarcat@example.com")  
    fileinto "example";
 
You can even pile up a bunch of options together to have one big rule with multiple patterns:
if anyof (exists "X-Cron-Env",
          header :contains ["subject"] ["security run output",
                                        "monthly run output",
                                        "daily run output",
                                        "weekly run output",
                                        "Debian Package Updates",
                                        "Debian package update",
                                        "daily mail stats",
                                        "Anacron job",
                                        "nagios",
                                        "changes report",
                                        "run output",
                                        "[Systraq]",
                                        "Undelivered mail",
                                        "Postfix SMTP server: errors from",
                                        "backupninja",
                                        "DenyHosts report",
                                        "Debian security status",
                                        "apt-listchanges"
                                        ],
           header :contains "Auto-Submitted" "auto-generated",
           envelope :contains "from" ["nagios@",
                                      "logcheck@",
                                      "root@"])
     
    fileinto "rapports";
 

Automated script There is a procmail2sieve.pl script floating around, and mentioned in the dovecot documentation. It didn't work very well for me: I could use it for small things, but I mostly wrote the sieve file from scratch.

Progressive migration Enrico Zini has progressively migrated his procmail setup to Sieve using a clever way: he hooked procmail inside sieve so that he could deliver to the Dovecot LDA and progressively migrate rules one by one, without having a "flag day". See this explanatory blog post for the details, which also shows how to configure Dovecot as an LMTP server with Postfix.

Other examples The Dovecot sieve examples are numerous and also quite useful. At the time of writing, they include virus scanning and spam filtering, vacation auto-replies, includes, archival, and flags.

Harmful considered harmful I am aware that the "considered harmful" title has a long and controversial history, being considered harmful in itself (by some people who are obviously not afraid of contradictions). I have nevertheless deliberately chosen that title, partly to make sure this article gets maximum visibility, but more specifically because I do not have doubts at this moment that procmail is, clearly, a bad idea at this moment in history.

Developing story I must also add that, incredibly, this story has changed while writing it. This article is derived from this bug I filed in Debian to, quite frankly, kick procmail out of Debian. But filing the bug had the interesting effect of pushing the upstream into action: as mentioned above, they have apparently made a new release and merged a bunch of patches in a new git repository. This doesn't change much of the above, at this moment. If anything significant comes out of this effort, I will try to update this article to reflect the situation. I am actually happy to retract the claims in this article if it turns out that procmail is a stellar example of defensive programming and survives fuzzing attacks. But at this moment, I'm pretty confident that will not happen, at least not in scope of the next Debian release cycle.

26 February 2022

Russ Allbery: INN 2.6.5

This is a bit of a sneak preview announcement since I'm waiting for the ISC mirror to update before sending the official announcement to the normal channels, but INN 2.6.5 has been released. (The release was finalized a few days ago, and I'm a bit behind in posting it.) This is a bug fix and minor feature release over INN 2.6.4, and the upgrade should be painless. You can download the new release from ftp.isc.org (once it updates) or my personal INN pages. The latter also has links to the full changelog and the other INN documentation. As always, thanks to Julien LIE for preparing this release and doing most of the maintenance work on INN! Changes in this release:

23 February 2022

Ian Jackson: Rooting an Eos Fairphone 4

Last week I received (finally) my Fairphone 4, supplied with a de-googled operating system, which I had ordered from the E Foundation s shop in December. (I m am very hard on hardware and my venerable Fairphone 2 is really on its last legs.) I expect to have full control over the software on any computing device I own which is as complicated, capable, and therefore, hazardous, as a mobile phone. Unfortunately the Eos image (they prefer to spell it /e/ os , srsly!) doesn t come with a way to get root without taking fairly serious measures including unlocking the bootloader. Unlocking the bootloader wouldn t be desirable for me but I can t live without root. So. I started with these helpful instructions: https://forum.xda-developers.com/t/fairphone-4-root.4376421/ I found the whole process a bit of a trial, and I thought I would write down what I did. But, it s not straightforward, at least for someone like me who only has a dim understanding of all this Android stuff. Unfortunately, due to the number of missteps and restarts, what I actually did is not really a sensible procedure. So here is a retcon of a process I think will work: Unlock the bootloader The E Foundation provide instructions for unlocking the bootloader on a stock FP4, here https://doc.e.foundation/devices/FP4/install and they seem applicable to the Murena phone supplied with Eos pre-installed, too. NB tht unlocking the bootloader wipes the phone. So we do it first. So:
  1. Power on the phone, with no SIM installed
  2. You get a welcome screen.
  3. Skip all things on startup including wifi
  4. Go to the very end of the settings, tap a gazillion times on the phone s version until you re a developer
  5. In the developer settings, allow usb debugging
  6. In the developer settings, allow oem bootloader unlocking
  7. Connect a computer via a USB cable, say yes on phone to USB debugging
  8. adb reboot bootloader
  9. The phone will reboot into a texty kind of screen, the bootloader
  10. fastboot flashing unlock
  11. The phone will reboot, back to the welcome screen
  12. Repeat steps 3-9 (maybe not all are necessary)
  13. fastboot flashing unlock_critical
  14. The phone will reboot, back to the welcome screen
Note that although you are running fastboot, you must run this command with the phone in bootloader mode, not fastboot (aka fastbootd ) mode. If you run fastboot flashing unlcok from fastboot you just get a don t know what you re talking about . I found conflicting instructions on what kind of Vulcan nerve pinches could be used to get into which boot modes, and had poor experiences with those. adb reboot bootloader always worked reliably for me. Some docs say to run fastboot oem unlock; I used flashing. Maybe this depends on the Android tools version. Initial privacy prep and OTA update We want to update the supplied phone OS. The build mine shipped with is too buggy to run Magisk, the application we are going to use to root the phone. (With the pre-installed phone OS, Magisk crashes at the patch boot image step.) But I didn t want to let the phone talk to Google, even for the push notifications registration.
  1. From the welcome screen, skip all things except location, date, time. Notably, do not set up wifi
  2. In settings, microg section
    1. turn off cloud messaging
    2. turn off google safetynet
    3. turn off google registration (NB you must do this after the other two, because their sliders become dysfunctional after you turn google registration off)
    4. turn off both location modules
  3. In settings, location section, turn off allowed location for browser and magic earth
  4. Now go into settings and enable wifi, giving it your wifi details
  5. Tell the phone to update its operating system. This is a big download.
Install Magisk, the root manager (As a starting point I used these instructions https://www.xda-developers.com/how-to-install-magisk/ and a lot of random forum posts.) You will need the official boot.img. Bizarrely there doesn t seem to be a way to obtain this from the phone. Instead, you must download it. You can find it by starting at https://doc.e.foundation/devices/FP4/install which links to https://images.ecloud.global/stable/FP4/. At the time of writing, the most recent version, whose version number seemed to correspond to the OS update I installed above, was IMG-e-0.21-r-20220123158735-stable-FP4.zip.
  1. Download the giant zipfile to your computer
  2. Unzip it to extract boot.img
  3. Copy the file to your phone s storage . Eg, via adb: with the phone booted into the main operating system, using USB debugging, adb push boot.img /storage/self/primary/Download.
  4. On the phone, open the browser, and enter https://f-droid.org. Click on the link to install f-droid. You will need to enable installing apps from the browser (follow the provided flow to the settings, change the setting, and then use Back, and you can do the install). If you wish, you can download the f-droid apk separately on a computer, and verify it with pgp.
  5. Using f-droid, install Magisk. You will need to enable installing apps from f-droid. (I installed Magisk from f-droid because 1. I was going to trust f-droid anyway 2. it has a shorter URL than Magisk s.)
  6. Open the Magisk app. Tell Magisk to install (Magisk, not the app). There will be only one option: patch boot file. Tell it to patch the boot.img file from before.
  7. Transfer the magisk_patched-THING.img back to your computer (eg via adb pull).
  8. adb reboot bootloader
  9. fastboot boot magisk_patched-THING.img (again, NB, from bootloader mode, not from fastboot mode)
  10. In Magisk you ll see it shows as installed. But it s not really; you ve just booted from an image with it. Ask to install Magisk with Direct install .
After you have done all this, I believe that each time you do an over-the-air OS update, you must, between installing the update and rebooting the phone, ask Magisk to Install to inactive slot (after OTA) . Presumably if you forget you must do the fastboot boot dance again. After all this, I was able to use tsu in Termux. There s a strange behaviour with the root prompt you get apropos Termux s request for root; I found that it definitely worked if Termux wasn t the foreground app You have to leave the bootloader unlocked. Howwever, as I understand it, the phone s encryption will still prevent an attacker from hoovering the data out of your phone. The bootloader lock is to prevent someone tricking you into entering the decryption passkey into a trojaned device. Other things to change There are probably other things to change. I have not yet transferred my Signal account from my old phone. It is possible that Signal will require me to re-enable the google push notifications, but I hope that having disabled them in microg it will be happy to use its own system, as it does on my old phone.

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21 February 2022

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, January 2022

A Debian LTS logo
Every month we review the work funded by Freexian s Debian LTS offering. Please find the report for January below. Debian project funding We continue to looking forward to hearing about Debian project proposals from various Debian stakeholders. This month has seen work on a survey that will go out to Debian Developers to gather feedback on what they think should be the priorities for funding in the project. Learn more about the rationale behind this initiative in this article. Debian LTS contributors In January, 13 contributors were paid to work on Debian LTS, their reports are available below. If you re interested in participating in the LTS or ELTS teams, we welcome participation from the Debian community. Simply get in touch with Jeremiah or Rapha l. Evolution of the situation In January we released 34 DLAs. The security tracker currently lists 39 packages with a known CVE and the dla-needed.txt file has 20 packages still needing an update. Thanks to our sponsors Sponsors that joined recently are in bold.

19 February 2022

Shirish Agarwal: The King of Torts John Grisham

John Grisham The King of Torts Lots of things have been happening and I have been unable to be on top of things. There are so many things that happen and keep on happening and a lot of it is just not in control. For those who are watching Brexit, India is going through the same/similar phenomena just without Brexit. I would not like to delve much into Indian happenings as there is no sweet story to tell. Mum is in hospital (diabetic foot) so a lot of time to read books. So I have been making use of the time and at the same time learning or making connections from what I know of the history of the world which goes on enriching what I read all the time. For e.g. in this book, opens up with people who are on Crack. Now while the book is set in 2003, it is still relevant today for a lot of things. There have been rumors and whatnot that the President of the United States, Ronald Reagan supplied a lot of cocaine to black folks in the early 1980s. While that has never been proved, it has been proved somewhat that the CIA and even people in the state department were part of providing crack cocaine to African Americans (as they refer to blacks) in those days. Whether this was because of black power rising or non-profits like ACLU or other organizations is beyond me. I had also read that the GOP (Republicans/Grand Old Party) in the 1970s itself when computers became fast and could do a lot of processing, came to know if education would be as it is, then soon they would no voters. hence they decided to defund education in America, the end result being massive education loans to prospective students and perhaps partly the reason why China produces more than enough STEM graduates than the total number of Americans who become graduates. It is a shame nonetheless, that education in the U.S. is never top  . This is somewhat from a Republican perspective. That is also the reason they are much anti-science.

Tort Cases India doesn t have either class-action suits or tort cases. But before we go headlong, this is what tort means. The book however is not about general tort cases but medical tort cases. The idea is that medical companies often produce medicines claiming they solve x or y issues but more often than not they take short-cuts to get approval from FDA and other regulators. And sooner or later those medicines can and do have harmful effects on the body, sometimes resulting in death. One of the more interesting articles that I read and probably also shared is the work done by Mr. Rob Bilott. While it is a typical David and Goliath story once you read the book, you realize that there are and were many difficulties in Mr. Rob s path that are never fully appreciated or even worked out. The biggest issue is the 8 years that he paid out of his own pocket to get the hundreds and thousands of people tested. How many of us would do that? And this is before proving causation of any disease, illness or anything to a particular environment, pollution etc. is hard even then and even now. Whatever money the victims receive afterward and whatever went to Mr. Rob Bilott would never compensate for the stress faced by him. And lawyers have to be careful, if they ask too little, they are not hurting the company and there is no change in its behavior. If they ask too much, the company can declare Chapter 11, bankruptcy so they have to keep the balance. There is also a lot of greed shown by the tort lawyer and while at the end he does tell about a company s nefarious activities that he suspects he could share his opinion only after giving up his law career. There is and was talk of tort-reform in the book but as can be seen if you reform tort there is just no way to punish such companies but that is in the U.S. There is also some observations that I have shared over the years, for e.g. Europe bans far more drugs than the U.S. does. A major part of it is perhaps due to the fact that Europe has 26/27 independent medical regulators and one country bans medicine for one or the other reason, the rest of Europe also bans the same. In the U.S. it is only the FDA. I have read they have had both funding and staffing issues for years and this is from before the pandemic. The Indian regulators are much worse. One could follow Priyanka Pulla s articles in Mint and others where she has shared how the regulator is corrupt and lazy and a combo of both. And all of this is besides how doctors are corrupted in India by marketing executives of pharma companies. That would be a whole article in itself. In short, when you read this book, there are so many thoughts that come alive when you are reading the book. The sad part is the book doesn t offer any solutions at all. John Grisham s books are usually legal thrillers and courtroom exchanges, this one though is and was very different. This one sadly doesn t take one to any conclusion apart from the fact that we live in an imperfect world and there don t seem to be any solutions. This was even shared by Rep. Katie Porter in her pinned tweet. The Abbvie s of the world will continue to take common people like you and me for a ride.

18 February 2022

Colin Watson: Launchpad now supports SSH Ed25519 keys and RSA SHA-2 signatures

As of 2022-02-16, Launchpad supports a couple of features on its SSH endpoints (git.launchpad.net, bazaar.launchpad.net, ppa.launchpad.net, and upload.ubuntu.com) that it previously didn t: Ed25519 public keys (a well-regarded format, supported by OpenSSH since 6.5 in 2014) and signatures with existing RSA public keys using SHA-2 rather than SHA-1 (supported by OpenSSH since 7.2 in 2016). I m hesitant to call these features new , since they ve been around for a long time elsewhere, and people might quite reasonably ask why it s taken us so long. The problem has always been that Launchpad can t really use a normal SSH server such as OpenSSH because it needs features that aren t practical to implement that way, such as virtual filesystems and dynamic user key authorization against the Launchpad database. Instead, we use Twisted Conch, which is a very extensible Python SSH implementation that has generally served us well. The downside is that, because it s an independent implementation and one that occupies a relatively small niche, it often lags behind in terms of newer protocol features. Catching up to this point has been something we ve been working on for around five years, although it s taken a painfully long time for a variety of reasons which I thought some people might find interesting to go into, at least people who have the patience for details of the SSH protocol. Many of the delays were my own responsibility, although realistically we probably couldn t have added Ed25519 support before OpenSSL/cryptography work that landed in 2019. Phew! Thanks to everyone who works on Twisted, cryptography, and OpenSSL - it s been really useful to be able to build on solid lower-level cryptographic primitives - and to those who helped with code review.

13 February 2022

Gunnar Wolf: Got to boot a RPi Zero 2 W with Debian

About a month ago, I got tired of waiting for the newest member of the Raspberry product lineup to be sold in Mexico, and I bought it from a Chinese reseller through a big online shopping platform. I paid quite a bit of premium (~US$85 instead of the advertised US$15), and got it delivered ten days later Anyway, it s known this machine does not yet boot mainline Linux. The vast majority of ARM systems require the bootloader to load a Device Tree file, presenting the hardware characteristics map. And while the RPi Zero 2 W (hey what an awful and confusing naming scheme they chose!) is mostly similar to a RPi3B+, it is not quite the same thing. A kernel with RPi3B+ s device tree will refuse to boot. Anyway, I started digging, and found that some days ago Stephan Wahren sent a patch to the linux-arm-kernel mailing list with a matching device tree. Read the patch! It s quite simple to read (what is harder is to know where each declaration should go, if you want to write your own, of course). It basically includes all basic details for the main chip in the RPi3 family (BCM2837), pulls in also the declarations from the BCM2836 present in the RPi2, and adds the necessary bits for the USB OTG connection and the WiFi and Bluetooth declarations. Registers the model name as Raspberry Pi Zero 2 W, which you can easily see in the following photo, informs the kernel it has 512MB RAM, and Well, really, it s an easy device tree to read, don t be shy! So, I booted my RPi 3B+ with a freshly downloaded Bookworm image, installed and unpacked linux-source-5.15, applied Stephan s patch, and added the following for the DTB to be generated in the arm64 tree as well:
--- /dev/null   2022-01-26 23:35:40.747999998 +0000
+++ arch/arm64/boot/dts/broadcom/bcm2837-rpi-zero-2-w.dts       2022-02-13 06:28:29.968429953 +0000
@@ -0,0 +1 @@
+#include "arm/bcm2837-rpi-zero-2-w.dts"
Then, ran a simple make dtbs, and Failed, because bcm283x-rpi-wifi-bt.dtsi is not yet in the kernel . OK, no worries: Getting wireless to work is a later step. I commented out the lines causing conflict (10, 33-35, 134-136), and:
root@rpi3-20220212:/usr/src/linux-source-5.15# make dtbs
  DTC     arch/arm64/boot/dts/broadcom/bcm2837-rpi-zero-2-w.dtb
Great! Just copied over that generated file to /boot/firmware/, moved the SD over to my RPiZ2W, and behold! It boots! When I bragged about it in #debian-raspberrypi, steev suggested me to pull in the WiFi patch, that has also been submitted (but not yet accepted) for kernel inclusion. I did so, uncommented the lines I modified, and built again. It builds correctly, and again copied the DTB over. It still does not find the WiFi; dmesg still complains about a missing bit of firmware (failed to load brcm/brcmfmac43430b0-sdio.raspberrypi,model-zero-2-w.bin). Steev pointed out it can be downloaded from RPi Distro s GitHub page, but I called it a night and didn t pursue it any further ;-) So I understand this post is still a far cry from saying our images properly boot under a RPi 0 2 W , but we will get there

4 February 2022

Ian Jackson: EUDCC QR codes vs NHS Travel barcodes vs TAC Verify

The EU Digital Covid Certificate scheme is a format for (digitally signed) vaccination status certificates. Not only EU countries participate - the UK is now a participant in this scheme. I am currently on my way to go skiing in the French Alps. So I needed a certificate that would be accepted in France. AFAICT the official way to do this is to get the international certificate from the NHS, and take it to a French pharmacy who will convert it into something suitably French. (AIUI the NHS international barcode is the same regardless of whether you get it via the NHS website, the NHS app, or a paper letter. NB that there is one barcode per vaccine dose so you have to get the right one - probably that means your booster since there s a 9 month rule!) I read on an forum somewhere that you could use the French TousAntiCovid app to convert the barcode. So I thought I would try that. The TousAntiCovid is Free Softare and on F-Droid, so I was happy to install and use it for this. I also used the French TAC Verify app to check to see what barcodes were accepted. (I found an official document addressed to French professionals recommending this as an option for verifying the status of visitors to one s establishment.) Unfortunately this involves a googlified phone, but one could use a burner phone or ask a friend who s bitten that bullet already. I discovered that, indeed: This made me curious. I used a QR code reader to decode both barcodes. The decodings were identical! A long string of guff starting HC1:. AIUI it is an encoded JWT. But there was a difference in the framing: Binary Eye reported that the NHS barcode used error correction level M (medium, aka 15%). The TousAntiCovid barcode used level L (low, 7%). I had my QR code software regenerate a QR code at level M for the data from the TousAntiCovid code. The result was a QR code which is identical (pixel-wise) to the one from the NHS. So the only difference is the error correction level. Curiously, both L (low, generated by TousAntiCovid, accepted by TAC Verify) and M (medium, generated by NHS, rejected by TAC Verify) are lower than the Q (25") recommended by what I think is the specification. This is all very odd. But the upshot is that I think you can convert the NHS international barcode into something that should work in France simply by passing it through any QR code software to re-encode it at error correction level L (7%). But if you re happy to use the TousAntiCovid app it s probably a good way to store them. I guess I ll find out when I get to France if the converted NHS barcodes work in real establishments. Thanks to the folks behind sanipasse.fr for publishing some helpful backround info and operating a Free Software backed public verification service. Footnote To compare the QR codes pixelwise, I roughly cropped the NHS PDF image using a GUI tool, and then on each of the two images used pnmcrop (to trim the border), pnmscale (to rescale the one-pixel-per-pixel output from Binary Eye) and pnmarith -difference to compare them (producing a pretty squirgly image showing just the pixel edges due to antialiasing).

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29 January 2022

Sylvestre Ledru: An update on rust/coreutils

TLDR: we are making progress on the Rust implementation of the GNU coreutils. Well, it is an understatement to say my previous blog post interested many people. Many articles, blog posts and some podcasts talked about it! As we pushed coreutils 0.0.12 a few days ago and getting closer to the 10 000 stars on github, it is now time to give an update! This has brought a lot of new contributors to this project. Instead of 30 to 60 patches per month, we jumped to 400 to 472 patches every month. Similarly, we saw an increase in the number of contributors (20 to 50 per month from 3 to 8). Two new maintainers (Michael Debertol & Terts Diepraam) stepped in and have been doing a much better job than myself as reviewers now! As a silly metric, according to github, we had 5 561 clones of the repository over the last 2 weeks! The new contributors focused on: Closing the gap with GNU As far as I know, we are only missing stty (change and print terminal line settings) as a program. Thanks to some heroes, basenc, pr, chcon and runcon have been implemented. For example, for the two last programs, Koutheir Attouchi wrote new crates to manage SELinux properly. This crate has been used for some other utilities like cp, ls or id. Leveraging the GNU testsuite to test this implementation Because the GNU testsuite is excellent, we now have a proper CI using it to run the tests. It is pretty long on the Github action CI (almost two hours to run it) but it is an amazing improvement to the way we work. It was a joint work from a bunch of folks (James Robson, Roy Ivy III, etc). To achieve this, we also made it easier to run the GNU testsuite locally with the Rust implementation but also to ignore some tests or adjust some error messages (see build-gnu.sh and run-gnu-test.sh). Following a suggestion of Brian G, a colleague at Mozilla (he did the same for some Firefox major change), we are now collecting the history of fail/pass/error into a separate repository and generating a daily graph showing the evolution of regression. Evolution over time At this date, we have, with GNU/Coreutils 9.0:
Total 611 tests
Pass 214
Skip 84
Fail 298
Error 15
We are now automatically identifying new passing tests and regressions in the CI. For example:
Warning: Congrats! The gnu test tests/chmod/c-option is now passing!
<br />Warning: Congrats! The gnu test tests/chmod/silent is now passing!
<br />Warning: Congrats! The gnu test tests/chmod/umask-x is now passing!
<br />Error: GNU test failed: tests/du/long-from-unreadable. tests/du/long-from-unreadable is passing on 'master'. Maybe you have to rebase?
[...]
<br />Warning: Changes from master: PASS +4 / FAIL +0 / ERROR -4 / SKIP +0
This is also beneficial to GNU as, by implementing some options, Michael Debertol noticed some incorrect behaviors (with sort and cat) or an uninitialized variable (with chmod). Documentations Every day, we are generating the user documentation and of the internal coreutils. User documentation: https://uutils.github.io/coreutils-docs/user/ Example: ls or cp The internal documentation can be seen on: https://uutils.github.io/coreutils-docs/dev/uucore/
For example, the backup style is documented here: https://uutils.github.io/coreutils-docs/dev/uucore/backup_control/index.html More? Besides my work on Debian/Ubuntu, I have also noticed that more and more operating systems are starting to look at this: In parallel, https://github.com/uutils/findutils/, a rust dropped-in replacement for find, is getting more attention lately! Here, the graph showing the evolution of the program using the BFS testsuite (much better than GNU's). Evolution over time - BFS testsuite What is next?
  1. stty needs to be implemented
  2. Improve the GNU compatibility on key programs and reduce the gap
  3. Investigate how to reduce the size of the binaries
  4. Allow Debian and Ubuntu to switch by default without tricky manipulation
How to help? I have been maintaining a list of good first bugs for new comers in the repo! Don't hesitate to contribute, it is much easier than it seems and a terrific way to learn Rust!

23 January 2022

Antoine Beaupr : Switching from OpenNTPd to Chrony

A friend recently reminded me of the existence of chrony, a "versatile implementation of the Network Time Protocol (NTP)". The excellent introduction is worth quoting in full:
It can synchronise the system clock with NTP servers, reference clocks (e.g. GPS receiver), and manual input using wristwatch and keyboard. It can also operate as an NTPv4 (RFC 5905) server and peer to provide a time service to other computers in the network. It is designed to perform well in a wide range of conditions, including intermittent network connections, heavily congested networks, changing temperatures (ordinary computer clocks are sensitive to temperature), and systems that do not run continuosly, or run on a virtual machine. Typical accuracy between two machines synchronised over the Internet is within a few milliseconds; on a LAN, accuracy is typically in tens of microseconds. With hardware timestamping, or a hardware reference clock, sub-microsecond accuracy may be possible.
Now that's already great documentation right there. What it is, why it's good, and what to expect from it. I want more. They have a very handy comparison table between chrony, ntp and openntpd.

My problem with OpenNTPd Following concerns surrounding the security (and complexity) of the venerable ntp program, I have, a long time ago, switched to using openntpd on all my computers. I hadn't thought about it until I recently noticed a lot of noise on one of my servers:
jan 18 10:09:49 curie ntpd[1069]: adjusting local clock by -1.604366s
jan 18 10:08:18 curie ntpd[1069]: adjusting local clock by -1.577608s
jan 18 10:05:02 curie ntpd[1069]: adjusting local clock by -1.574683s
jan 18 10:04:00 curie ntpd[1069]: adjusting local clock by -1.573240s
jan 18 10:02:26 curie ntpd[1069]: adjusting local clock by -1.569592s
You read that right, openntpd was constantly rewinding the clock, sometimes in less than two minutes. The above log was taken while doing diagnostics, looking at the last 30 minutes of logs. So, on average, one 1.5 seconds rewind per 6 minutes! That might be due to a dying real time clock (RTC) or some other hardware problem. I know for a fact that the CMOS battery on that computer (curie) died and I wasn't able to replace it (!). So that's partly garbage-in, garbage-out here. But still, I was curious to see how chrony would behave... (Spoiler: much better.) But I also had trouble on another workstation, that one a much more recent machine (angela). First, it seems OpenNTPd would just fail at boot time:
anarcat@angela:~(main)$ sudo systemctl status openntpd
  openntpd.service - OpenNTPd Network Time Protocol
     Loaded: loaded (/lib/systemd/system/openntpd.service; enabled; vendor pres>
     Active: inactive (dead) since Sun 2022-01-23 09:54:03 EST; 6h ago
       Docs: man:openntpd(8)
    Process: 3291 ExecStartPre=/usr/sbin/ntpd -n $DAEMON_OPTS (code=exited, sta>
    Process: 3294 ExecStart=/usr/sbin/ntpd $DAEMON_OPTS (code=exited, status=0/>
   Main PID: 3298 (code=exited, status=0/SUCCESS)
        CPU: 34ms
jan 23 09:54:03 angela systemd[1]: Starting OpenNTPd Network Time Protocol...
jan 23 09:54:03 angela ntpd[3291]: configuration OK
jan 23 09:54:03 angela ntpd[3297]: ntp engine ready
jan 23 09:54:03 angela ntpd[3297]: ntp: recvfrom: Permission denied
jan 23 09:54:03 angela ntpd[3294]: Terminating
jan 23 09:54:03 angela systemd[1]: Started OpenNTPd Network Time Protocol.
jan 23 09:54:03 angela systemd[1]: openntpd.service: Succeeded.
After a restart, somehow it worked, but it took a long time to sync the clock. At first, it would just not consider any peer at all:
anarcat@angela:~(main)$ sudo ntpctl -s all
0/20 peers valid, clock unsynced
peer
   wt tl st  next  poll          offset       delay      jitter
159.203.8.72 from pool 0.debian.pool.ntp.org
    1  5  2    6s    6s             ---- peer not valid ----
138.197.135.239 from pool 0.debian.pool.ntp.org
    1  5  2    6s    7s             ---- peer not valid ----
216.197.156.83 from pool 0.debian.pool.ntp.org
    1  4  1    2s    9s             ---- peer not valid ----
142.114.187.107 from pool 0.debian.pool.ntp.org
    1  5  2    5s    6s             ---- peer not valid ----
216.6.2.70 from pool 1.debian.pool.ntp.org
    1  4  2    2s    8s             ---- peer not valid ----
207.34.49.172 from pool 1.debian.pool.ntp.org
    1  4  2    0s    5s             ---- peer not valid ----
198.27.76.102 from pool 1.debian.pool.ntp.org
    1  5  2    5s    5s             ---- peer not valid ----
158.69.254.196 from pool 1.debian.pool.ntp.org
    1  4  3    1s    6s             ---- peer not valid ----
149.56.121.16 from pool 2.debian.pool.ntp.org
    1  4  2    5s    9s             ---- peer not valid ----
162.159.200.123 from pool 2.debian.pool.ntp.org
    1  4  3    1s    6s             ---- peer not valid ----
206.108.0.131 from pool 2.debian.pool.ntp.org
    1  4  1    6s    9s             ---- peer not valid ----
205.206.70.40 from pool 2.debian.pool.ntp.org
    1  5  2    8s    9s             ---- peer not valid ----
2001:678:8::123 from pool 2.debian.pool.ntp.org
    1  4  2    5s    9s             ---- peer not valid ----
2606:4700:f1::1 from pool 2.debian.pool.ntp.org
    1  4  3    2s    6s             ---- peer not valid ----
2607:5300:205:200::1991 from pool 2.debian.pool.ntp.org
    1  4  2    5s    9s             ---- peer not valid ----
2607:5300:201:3100::345c from pool 2.debian.pool.ntp.org
    1  4  4    1s    6s             ---- peer not valid ----
209.115.181.110 from pool 3.debian.pool.ntp.org
    1  5  2    5s    6s             ---- peer not valid ----
205.206.70.42 from pool 3.debian.pool.ntp.org
    1  4  2    0s    6s             ---- peer not valid ----
68.69.221.61 from pool 3.debian.pool.ntp.org
    1  4  1    2s    9s             ---- peer not valid ----
162.159.200.1 from pool 3.debian.pool.ntp.org
    1  4  3    4s    7s             ---- peer not valid ----
Then it would accept them, but still wouldn't sync the clock:
anarcat@angela:~(main)$ sudo ntpctl -s all
20/20 peers valid, clock unsynced
peer
   wt tl st  next  poll          offset       delay      jitter
159.203.8.72 from pool 0.debian.pool.ntp.org
    1  8  2    5s    6s         0.672ms    13.507ms     0.442ms
138.197.135.239 from pool 0.debian.pool.ntp.org
    1  7  2    4s    8s         1.260ms    13.388ms     0.494ms
216.197.156.83 from pool 0.debian.pool.ntp.org
    1  7  1    3s    5s        -0.390ms    47.641ms     1.537ms
142.114.187.107 from pool 0.debian.pool.ntp.org
    1  7  2    1s    6s        -0.573ms    15.012ms     1.845ms
216.6.2.70 from pool 1.debian.pool.ntp.org
    1  7  2    3s    8s        -0.178ms    21.691ms     1.807ms
207.34.49.172 from pool 1.debian.pool.ntp.org
    1  7  2    4s    8s        -5.742ms    70.040ms     1.656ms
198.27.76.102 from pool 1.debian.pool.ntp.org
    1  7  2    0s    7s         0.170ms    21.035ms     1.914ms
158.69.254.196 from pool 1.debian.pool.ntp.org
    1  7  3    5s    8s        -2.626ms    20.862ms     2.032ms
149.56.121.16 from pool 2.debian.pool.ntp.org
    1  7  2    6s    8s         0.123ms    20.758ms     2.248ms
162.159.200.123 from pool 2.debian.pool.ntp.org
    1  8  3    4s    5s         2.043ms    14.138ms     1.675ms
206.108.0.131 from pool 2.debian.pool.ntp.org
    1  6  1    0s    7s        -0.027ms    14.189ms     2.206ms
205.206.70.40 from pool 2.debian.pool.ntp.org
    1  7  2    1s    5s        -1.777ms    53.459ms     1.865ms
2001:678:8::123 from pool 2.debian.pool.ntp.org
    1  6  2    1s    8s         0.195ms    14.572ms     2.624ms
2606:4700:f1::1 from pool 2.debian.pool.ntp.org
    1  7  3    6s    9s         2.068ms    14.102ms     1.767ms
2607:5300:205:200::1991 from pool 2.debian.pool.ntp.org
    1  6  2    4s    9s         0.254ms    21.471ms     2.120ms
2607:5300:201:3100::345c from pool 2.debian.pool.ntp.org
    1  7  4    5s    9s        -1.706ms    21.030ms     1.849ms
209.115.181.110 from pool 3.debian.pool.ntp.org
    1  7  2    0s    7s         8.907ms    75.070ms     2.095ms
205.206.70.42 from pool 3.debian.pool.ntp.org
    1  7  2    6s    9s        -1.729ms    53.823ms     2.193ms
68.69.221.61 from pool 3.debian.pool.ntp.org
    1  7  1    1s    7s        -1.265ms    46.355ms     4.171ms
162.159.200.1 from pool 3.debian.pool.ntp.org
    1  7  3    4s    8s         1.732ms    35.792ms     2.228ms
It took a solid five minutes to sync the clock, even though the peers were considered valid within a few seconds:
jan 23 15:58:41 angela systemd[1]: Started OpenNTPd Network Time Protocol.
jan 23 15:58:58 angela ntpd[84086]: peer 142.114.187.107 now valid
jan 23 15:58:58 angela ntpd[84086]: peer 198.27.76.102 now valid
jan 23 15:58:58 angela ntpd[84086]: peer 207.34.49.172 now valid
jan 23 15:58:58 angela ntpd[84086]: peer 209.115.181.110 now valid
jan 23 15:58:59 angela ntpd[84086]: peer 159.203.8.72 now valid
jan 23 15:58:59 angela ntpd[84086]: peer 138.197.135.239 now valid
jan 23 15:58:59 angela ntpd[84086]: peer 162.159.200.123 now valid
jan 23 15:58:59 angela ntpd[84086]: peer 2607:5300:201:3100::345c now valid
jan 23 15:59:00 angela ntpd[84086]: peer 2606:4700:f1::1 now valid
jan 23 15:59:00 angela ntpd[84086]: peer 158.69.254.196 now valid
jan 23 15:59:01 angela ntpd[84086]: peer 216.6.2.70 now valid
jan 23 15:59:01 angela ntpd[84086]: peer 68.69.221.61 now valid
jan 23 15:59:01 angela ntpd[84086]: peer 205.206.70.40 now valid
jan 23 15:59:01 angela ntpd[84086]: peer 205.206.70.42 now valid
jan 23 15:59:02 angela ntpd[84086]: peer 162.159.200.1 now valid
jan 23 15:59:04 angela ntpd[84086]: peer 216.197.156.83 now valid
jan 23 15:59:05 angela ntpd[84086]: peer 206.108.0.131 now valid
jan 23 15:59:05 angela ntpd[84086]: peer 2001:678:8::123 now valid
jan 23 15:59:05 angela ntpd[84086]: peer 149.56.121.16 now valid
jan 23 15:59:07 angela ntpd[84086]: peer 2607:5300:205:200::1991 now valid
jan 23 16:03:47 angela ntpd[84086]: clock is now synced
That seems kind of odd. It was also frustrating to have very little information from ntpctl about the state of the daemon. I understand it's designed to be minimal, but it could inform me on his known offset, for example. It does tell me about the offset with the different peers, but not as clearly as one would expect. It's also unclear how it disciplines the RTC at all.

Compared to chrony Now compare with chrony:
jan 23 16:07:16 angela systemd[1]: Starting chrony, an NTP client/server...
jan 23 16:07:16 angela chronyd[87765]: chronyd version 4.0 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP +SCFILTER +SIGND +ASYNCDNS +NTS +SECHASH +IPV6 -DEBUG)
jan 23 16:07:16 angela chronyd[87765]: Initial frequency 3.814 ppm
jan 23 16:07:16 angela chronyd[87765]: Using right/UTC timezone to obtain leap second data
jan 23 16:07:16 angela chronyd[87765]: Loaded seccomp filter
jan 23 16:07:16 angela systemd[1]: Started chrony, an NTP client/server.
jan 23 16:07:21 angela chronyd[87765]: Selected source 206.108.0.131 (2.debian.pool.ntp.org)
jan 23 16:07:21 angela chronyd[87765]: System clock TAI offset set to 37 seconds
First, you'll notice there's none of that "clock synced" nonsense, it picks a source, and then... it's just done. Because the clock on this computer is not drifting that much, and openntpd had (presumably) just sync'd it anyways. And indeed, if we look at detailed stats from the powerful chronyc client:
anarcat@angela:~(main)$ sudo chronyc tracking
Reference ID    : CE6C0083 (ntp1.torix.ca)
Stratum         : 2
Ref time (UTC)  : Sun Jan 23 21:07:21 2022
System time     : 0.000000311 seconds slow of NTP time
Last offset     : +0.000807989 seconds
RMS offset      : 0.000807989 seconds
Frequency       : 3.814 ppm fast
Residual freq   : -24.434 ppm
Skew            : 1000000.000 ppm
Root delay      : 0.013200894 seconds
Root dispersion : 65.357254028 seconds
Update interval : 1.4 seconds
Leap status     : Normal
We see that we are nanoseconds away from NTP time. That was ran very quickly after starting the server (literally in the same second as chrony picked a source), so stats are a bit weird (e.g. the Skew is huge). After a minute or two, it looks more reasonable:
Reference ID    : CE6C0083 (ntp1.torix.ca)
Stratum         : 2
Ref time (UTC)  : Sun Jan 23 21:09:32 2022
System time     : 0.000487002 seconds slow of NTP time
Last offset     : -0.000332960 seconds
RMS offset      : 0.000751204 seconds
Frequency       : 3.536 ppm fast
Residual freq   : +0.016 ppm
Skew            : 3.707 ppm
Root delay      : 0.013363549 seconds
Root dispersion : 0.000324015 seconds
Update interval : 65.0 seconds
Leap status     : Normal
Now it's learning how good or bad the RTC clock is ("Frequency"), and is smoothly adjusting the System time to follow the average offset (RMS offset, more or less). You'll also notice the Update interval has risen, and will keep expanding as chrony learns more about the internal clock, so it doesn't need to constantly poll the NTP servers to sync the clock. In the above, we're 487 micro seconds (less than a milisecond!) away from NTP time. (People interested in the explanation of every single one of those fields can read the excellent chronyc manpage. That thing made me want to nerd out on NTP again!) On the machine with the bad clock, chrony also did a 1.5 second adjustment, but just once, at startup:
jan 18 11:54:33 curie chronyd[2148399]: Selected source 206.108.0.133 (2.debian.pool.ntp.org) 
jan 18 11:54:33 curie chronyd[2148399]: System clock wrong by -1.606546 seconds 
jan 18 11:54:31 curie chronyd[2148399]: System clock was stepped by -1.606546 seconds 
jan 18 11:54:31 curie chronyd[2148399]: System clock TAI offset set to 37 seconds 
Then it would still struggle to keep the clock in sync, but not as badly as openntpd. Here's the offset a few minutes after that above startup:
System time     : 0.000375352 seconds slow of NTP time
And again a few seconds later:
System time     : 0.001793046 seconds slow of NTP time
I don't currently have access to that machine, and will update this post with the latest status, but so far I've had a very good experience with chrony on that machine, which is a testament to its resilience, and it also just works on my other machines as well.

Extras On top of "just working" (as demonstrated above), I feel that chrony's feature set is so much superior... Here's an excerpt of the extras in chrony, taken from the comparison table:
  • source frequency tracking
  • source state restore from file
  • temperature compensation
  • ready for next NTP era (year 2036)
  • replace unreachable / falseticker servers
  • aware of jitter
  • RTC drift tracking
  • RTC trimming
  • Restore time from file w/o RTC
  • leap seconds correction, in slew mode
  • drops root privileges
I even understand some of that stuff. I think. So kudos to the chrony folks, I'm switching.

Caveats One thing to keep in mind in the above, however is that it's quite possible chrony does as bad of a job as openntpd on that old machine, and just doesn't tell me about it. For example, here's another log sample from another server (marcos):
jan 23 11:13:25 marcos ntpd[1976694]: adjusting clock frequency by 0.451035 to -16.420273ppm
I get those basically every day, which seems to show that it's at least trying to keep track of the hardware clock. In other words, it's quite possible I have no idea what I'm talking about and you definitely need to take this article with a grain of salt. I'm not an NTP expert. Update: I should also mentioned that I haven't evaluated systemd-timesyncd, for a few reasons:
  1. I have enough things running under systemd
  2. I wasn't aware of it when I started writing this
  3. I couldn't find good documentation on it... later I found the above manpage and of course the Arch Wiki but that is very minimal
  4. therefore I can't tell how it compares with chrony or (open)ntpd, so I don't see an enticing reason to switch
It has a few things going for it though:
  • it's likely shipped with your distribution already
  • it drops privileges (possibly like chrony, unclear if it also has seccomp filters)
  • it's minimalist: it only does SNTP so not the server side
  • the status command is good enough that you can tell the clock frequency, precision, and so on (especially when compared to openntpd's ntpctl)
So I'm reserving judgement over it, but I'd certainly note that I'm always a little weary in trusting systemd daemons with the network, and would prefer to keep that attack surface to a minimum. Diversity is a good thing, in general, so I'll keep chrony for now. It would certainly nice to see it added to chrony's comparison table.

Switching to chrony Because the default configuration in chrony (at least as shipped in Debian) is sane (good default peers, no open network by default), installing it is as simple as:
apt install chrony
And because it somehow conflicts with openntpd, that also takes care of removing that cruft as well.

Update: Debian defaults So it seems like I managed to write this entire blog post without putting it in relation with the original reason I had to think about this in the first place, which is odd and should be corrected. This conversation came about on an IRC channel that mentioned that the ntp package (and upstream) is in bad shape in Debian. In that discussion, chrony and ntpsec were discussed as possible replacements, but when we had the discussion on chat, I mentioned I was using openntpd, and promptly realized I was actually unhappy with it. A friend suggested chrony, I tried it, and it worked amazingly, I switched, wrote this blog post, end of story. Except today (2022-02-07, two weeks later), I actually read that thread and realized that something happened in Debian I wasn't actually aware of. In bookworm, systemd-timesyncd was not only shipped, but it was installed by default, as it was marked as a hard dependency of systemd. That was "fixed" in systemd-247.9-2 (see bug 986651), but only by making the dependency a Recommends and marking it as Priority: important. So in effect, systemd-timesyncd became the default NTP daemon in Debian in bookworm, which I find somewhat surprising. timesyncd has many things going for it (as mentioned above), but I do find it a bit annoying that systemd is replacing all those utilities in such a way. I also wonder what is going to happen on upgrades. This is all a little frustrating too because there is no good comparison between the other NTP daemons and timesyncd anywhere. The chrony comparison table doesn't mention it, and an audit by the Core Infrastructure Initiative from 2017 doesn't mention it either, even though timesyncd was announced in 2014. (Same with this blog post from Facebook.)

17 January 2022

Matthew Garrett: Boot Guard and PSB have user-hostile defaults

Compromising an OS without it being detectable is hard. Modern operating systems support the imposition of a security policy or the launch of some sort of monitoring agent sufficient early in boot that even if you compromise the OS, you're probably going to have left some sort of detectable trace[1]. You can avoid this by attacking the lower layers - if you compromise the bootloader then it can just hotpatch a backdoor into the kernel before executing it, for instance.

This is avoided via one of two mechanisms. Measured boot (such as TPM-based Trusted Boot) makes a tamper-proof cryptographic record of what the system booted, with each component in turn creating a measurement of the next component in the boot chain. If a component is tampered with, its measurement will be different. This can be used to either prevent the release of a cryptographic secret if the boot chain is modified (for instance, using the TPM to encrypt the disk encryption key), or can be used to attest the boot state to another device which can tell you whether you're safe or not. The other approach is verified boot (such as UEFI Secure Boot), where each component in the boot chain verifies the next component before executing it. If the verification fails, execution halts.

In both cases, each component in the boot chain measures and/or verifies the next. But something needs to be the first link in this chain, and traditionally this was the system firmware. Which means you could tamper with the system firmware and subvert the entire process - either have the firmware patch the bootloader in RAM after measuring or verifying it, or just load a modified bootloader and lie about the measurements or ignore the verification. Attackers had already been targeting the firmware (Hacking Team had something along these lines, although this was pre-secure boot so just dropped a rootkit into the OS), and given a well-implemented measured and verified boot chain, the firmware becomes an even more attractive target.

Intel's Boot Guard and AMD's Platform Secure Boot attempt to solve this problem by moving the validation of the core system firmware to an (approximately) immutable environment. Intel's solution involves the Management Engine, a separate x86 core integrated into the motherboard chipset. The ME's boot ROM verifies a signature on its firmware before executing it, and once the ME is up it verifies that the system firmware's bootblock is signed using a public key that corresponds to a hash blown into one-time programmable fuses in the chipset. What happens next depends on policy - it can either prevent the system from booting, allow the system to boot to recover the firmware but automatically shut it down after a while, or flag the failure but allow the system to boot anyway. Most policies will also involve a measurement of the bootblock being pushed into the TPM.

AMD's Platform Secure Boot is slightly different. Rather than the root of trust living in the motherboard chipset, it's in AMD's Platform Security Processor which is incorporated directly onto the CPU die. Similar to Boot Guard, the PSP has ROM that verifies the PSP's own firmware, and then that firmware verifies the system firmware signature against a set of blown fuses in the CPU. If that fails, system boot is halted. I'm having trouble finding decent technical documentation about PSB, and what I have found doesn't mention measuring anything into the TPM - if this is the case, PSB only implements verified boot, not measured boot.

What's the practical upshot of this? The first is that you can't replace the system firmware with anything that doesn't have a valid signature, which effectively means you're locked into firmware the vendor chooses to sign. This prevents replacing the system firmware with either a replacement implementation (such as Coreboot) or a modified version of the original implementation (such as firmware that disables locking of CPU functionality or removes hardware allowlists). In this respect, enforcing system firmware verification works against the user rather than benefiting them.
Of course, it also prevents an attacker from doing the same thing, but while this is a real threat to some users, I think it's hard to say that it's a realistic threat for most users.

The problem is that vendors are shipping with Boot Guard and (increasingly) PSB enabled by default. In the AMD case this causes another problem - because the fuses are in the CPU itself, a CPU that's had PSB enabled is no longer compatible with any motherboards running firmware that wasn't signed with the same key. If a user wants to upgrade their system's CPU, they're effectively unable to sell the old one. But in both scenarios, the user's ability to control what their system is running is reduced.

As I said, the threat that these technologies seek to protect against is real. If you're a large company that handles a lot of sensitive data, you should probably worry about it. If you're a journalist or an activist dealing with governments that have a track record of targeting people like you, it should probably be part of your threat model. But otherwise, the probability of you being hit by a purely userland attack is so ludicrously high compared to you being targeted this way that it's just not a big deal.

I think there's a more reasonable tradeoff than where we've ended up. Tying things like disk encryption secrets to TPM state means that if the system firmware is measured into the TPM prior to being executed, we can at least detect that the firmware has been tampered with. In this case nothing prevents the firmware being modified, there's just a record in your TPM that it's no longer the same as it was when you encrypted the secret. So, here's what I'd suggest:

1) The default behaviour of technologies like Boot Guard or PSB should be to measure the firmware signing key and whether the firmware has a valid signature into PCR 7 (the TPM register that is also used to record which UEFI Secure Boot signing key is used to verify the bootloader).
2) If the PCR 7 value changes, the disk encryption key release will be blocked, and the user will be redirected to a key recovery process. This should include remote attestation, allowing the user to be informed that their firmware signing situation has changed.
3) Tooling should be provided to switch the policy from merely measuring to verifying, and users at meaningful risk of firmware-based attacks should be encouraged to make use of this tooling

This would allow users to replace their system firmware at will, at the cost of having to re-seal their disk encryption keys against the new TPM measurements. It would provide enough information that, in the (unlikely for most users) scenario that their firmware has actually been modified without their knowledge, they can identify that. And it would allow users who are at high risk to switch to a higher security state, and for hardware that is explicitly intended to be resilient against attacks to have different defaults.

This is frustratingly close to possible with Boot Guard, but I don't think it's quite there. Before you've blown the Boot Guard fuses, the Boot Guard policy can be read out of flash. This means that you can drop a Boot Guard configuration into flash telling the ME to measure the firmware but not prevent it from running. But there are two problems remaining:

1) The measurement is made into PCR 0, and PCR 0 changes every time your firmware is updated. That makes it a bad default for sealing encryption keys.
2) It doesn't look like the policy is measured before being enforced. This means that an attacker can simply reflash modified firmware with a policy that disables measurement and then make a fake measurement that makes it look like the firmware is ok.

Fixing this seems simple enough - the Boot Guard policy should always be measured, and measurements of the policy and the signing key should be made into a PCR other than PCR 0. If an attacker modified the policy, the PCR value would change. If an attacker modified the firmware without modifying the policy, the PCR value would also change. People who are at high risk would run an app that would blow the Boot Guard policy into fuses rather than just relying on the copy in flash, and enable verification as well as measurement. Now if an attacker tampers with the firmware, the system simply refuses to boot and the attacker doesn't get anything.

Things are harder on the AMD side. I can't find any indication that PSB supports measuring the firmware at all, which obviously makes this approach impossible. I'm somewhat surprised by that, and so wouldn't be surprised if it does do a measurement somewhere. If it doesn't, there's a rather more significant problem - if a system has a socketed CPU, and someone has sufficient physical access to replace the firmware, they can just swap out the CPU as well with one that doesn't have PSB enabled. Under normal circumstances the system firmware can detect this and prompt the user, but given that the attacker has just replaced the firmware we can assume that they'd do so with firmware that doesn't decide to tell the user what just happened. In the absence of better documentation, it's extremely hard to say that PSB actually provides meaningful security benefits.

So, overall: I think Boot Guard protects against a real-world attack that matters to a small but important set of targets. I think most of its benefits could be provided in a way that still gave users control over their system firmware, while also permitting high-risk targets to opt-in to stronger guarantees. Based on what's publicly documented about PSB, it's hard to say that it provides real-world security benefits for anyone at present. In both cases, what's actually shipping reduces the control people have over their systems, and should be considered user-hostile.

[1] Assuming that someone's both turning this on and actually looking at the data produced

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16 January 2022

Chris Lamb: Favourite films of 2021

In my four most recent posts, I went over the memoirs and biographies, the non-fiction, the fiction and the 'classic' novels that I enjoyed reading the most in 2021. But in the very last of my 2021 roundup posts, I'll be going over some of my favourite movies. (Saying that, these are perhaps less of my 'favourite films' than the ones worth remarking on after all, nobody needs to hear that The Godfather is a good movie.) It's probably helpful to remark you that I took a self-directed course in film history in 2021, based around the first volume of Roger Ebert's The Great Movies. This collection of 100-odd movie essays aims to make a tour of the landmarks of the first century of cinema, and I watched all but a handul before the year was out. I am slowly making my way through volume two in 2022. This tome was tremendously useful, and not simply due to the background context that Ebert added to each film: it also brought me into contact with films I would have hardly come through some other means. Would I have ever discovered the sly comedy of Trouble in Paradise (1932) or the touching proto-realism of L'Atalante (1934) any other way? It also helped me to 'get around' to watching films I may have put off watching forever the influential Battleship Potemkin (1925), for instance, and the ur-epic Lawrence of Arabia (1962) spring to mind here. Choosing a 'worst' film is perhaps more difficult than choosing the best. There are first those that left me completely dry (Ready or Not, Written on the Wind, etc.), and those that were simply poorly executed. And there are those that failed to meet their own high opinions of themselves, such as the 'made for Reddit' Tenet (2020) or the inscrutable Vanilla Sky (2001) the latter being an almost perfect example of late-20th century cultural exhaustion. But I must save my most severe judgement for those films where I took a visceral dislike how their subjects were portrayed. The sexually problematic Sixteen Candles (1984) and the pseudo-Catholic vigilantism of The Boondock Saints (1999) both spring to mind here, the latter of which combines so many things I dislike into such a short running time I'd need an entire essay to adequately express how much I disliked it.

Dogtooth (2009) A father, a mother, a brother and two sisters live in a large and affluent house behind a very high wall and an always-locked gate. Only the father ever leaves the property, driving to the factory that he happens to own. Dogtooth goes far beyond any allusion to Josef Fritzl's cellar, though, as the children's education is a grotesque parody of home-schooling. Here, the parents deliberately teach their children the wrong meaning of words (e.g. a yellow flower is called a 'zombie'), all of which renders the outside world utterly meaningless and unreadable, and completely mystifying its very existence. It is this creepy strangeness within a 'regular' family unit in Dogtooth that is both socially and epistemically horrific, and I'll say nothing here of its sexual elements as well. Despite its cold, inscrutable and deadpan surreality, Dogtooth invites all manner of potential interpretations. Is this film about the artificiality of the nuclear family that the West insists is the benchmark of normality? Or is it, as I prefer to believe, something more visceral altogether: an allegory for the various forms of ontological violence wrought by fascism, as well a sobering nod towards some of fascism's inherent appeals? (Perhaps it is both. In 1972, French poststructuralists Gilles and F lix Guattari wrote Anti-Oedipus, which plays with the idea of the family unit as a metaphor for the authoritarian state.) The Greek-language Dogtooth, elegantly shot, thankfully provides no easy answers.

Holy Motors (2012) There is an infamous scene in Un Chien Andalou, the 1929 film collaboration between Luis Bu uel and famed artist Salvador Dal . A young woman is cornered in her own apartment by a threatening man, and she reaches for a tennis racquet in self-defence. But the man suddenly picks up two nearby ropes and drags into the frame two large grand pianos... each leaden with a dead donkey, a stone tablet, a pumpkin and a bewildered priest. This bizarre sketch serves as a better introduction to Leos Carax's Holy Motors than any elementary outline of its plot, which ostensibly follows 24 hours in the life of a man who must play a number of extremely diverse roles around Paris... all for no apparent reason. (And is he even a man?) Surrealism as an art movement gets a pretty bad wrap these days, and perhaps justifiably so. But Holy Motors and Un Chien Andalou serve as a good reminder that surrealism can be, well, 'good, actually'. And if not quite high art, Holy Motors at least demonstrates that surrealism can still unnerving and hilariously funny. Indeed, recalling the whimsy of the plot to a close friend, the tears of laughter came unbidden to my eyes once again. ("And then the limousines...!") Still, it is unclear how Holy Motors truly refreshes surrealism for the twenty-first century. Surrealism was, in part, a reaction to the mechanical and unfeeling brutality of World War I and ultimately sought to release the creative potential of the unconscious mind. Holy Motors cannot be responding to another continental conflagration, and so it appears to me to be some kind of commentary on the roles we exhibit in an era of 'post-postmodernity': a sketch on our age of performative authenticity, perhaps, or an idle doodle on the function and psychosocial function of work. Or perhaps not. After all, this film was produced in a time that offers the near-universal availability of mind-altering substances, and this certainly changes the context in which this film was both created. And, how can I put it, was intended to be watched.

Manchester by the Sea (2016) An absolutely devastating portrayal of a character who is unable to forgive himself and is hesitant to engage with anyone ever again. It features a near-ideal balance between portraying unrecoverable anguish and tender warmth, and is paradoxically grandiose in its subtle intimacy. The mechanics of life led me to watch this lying on a bed in a chain hotel by Heathrow Airport, and if this colourless circumstance blunted the film's emotional impact on me, I am probably thankful for it. Indeed, I find myself reduced in this review to fatuously recalling my favourite interactions instead of providing any real commentary. You could write a whole essay about one particular incident: its surfaces, subtexts and angles... all despite nothing of any substance ever being communicated. Truly stunning.

McCabe & Mrs. Miller (1971) Roger Ebert called this movie one of the saddest films I have ever seen, filled with a yearning for love and home that will not ever come. But whilst it is difficult to disagree with his sentiment, Ebert's choice of sad is somehow not quite the right word. Indeed, I've long regretted that our dictionaries don't have more nuanced blends of tragedy and sadness; perhaps the Ancient Greeks can loan us some. Nevertheless, the plot of this film is of a gambler and a prostitute who become business partners in a new and remote mining town called Presbyterian Church. However, as their town and enterprise booms, it comes to the attention of a large mining corporation who want to bully or buy their way into the action. What makes this film stand out is not the plot itself, however, but its mood and tone the town and its inhabitants seem to be thrown together out of raw lumber, covered alternatively in mud or frozen ice, and their days (and their personalities) are both short and dark in equal measure. As a brief aside, if you haven't seen a Roger Altman film before, this has all the trappings of being a good introduction. As Ebert went on to observe: This is not the kind of movie where the characters are introduced. They are all already here. Furthermore, we can see some of Altman's trademark conversations that overlap, a superb handling of ensemble casts, and a quietly subversive view of the tyranny of 'genre'... and the latter in a time when the appetite for revisionist portrays of the West was not very strong. All of these 'Altmanian' trademarks can be ordered in much stronger measures in his later films: in particular, his comedy-drama Nashville (1975) has 24 main characters, and my jejune interpretation of Gosford Park (2001) is that it is purposefully designed to poke fun those who take a reductionist view of 'genre', or at least on the audience's expectations. (In this case, an Edwardian-era English murder mystery in the style of Agatha Christie, but where no real murder or detection really takes place.) On the other hand, McCabe & Mrs. Miller is actually a poor introduction to Altman. The story is told in a suitable deliberate and slow tempo, and the two stars of the film are shown thoroughly defrocked of any 'star status', in both the visual and moral dimensions. All of these traits are, however, this film's strength, adding up to a credible, fascinating and riveting portrayal of the old West.

Detour (1945) Detour was filmed in less than a week, and it's difficult to decide out of the actors and the screenplay which is its weakest point.... Yet it still somehow seemed to drag me in. The plot revolves around luckless Al who is hitchhiking to California. Al gets a lift from a man called Haskell who quickly falls down dead from a heart attack. Al quickly buries the body and takes Haskell's money, car and identification, believing that the police will believe Al murdered him. An unstable element is soon introduced in the guise of Vera, who, through a set of coincidences that stretches credulity, knows that this 'new' Haskell (ie. Al pretending to be him) is not who he seems. Vera then attaches herself to Al in order to blackmail him, and the world starts to spin out of his control. It must be understood that none of this is executed very well. Rather, what makes Detour so interesting to watch is that its 'errors' lend a distinctively creepy and unnatural hue to the film. Indeed, in the early twentieth century, Sigmund Freud used the word unheimlich to describe the experience of something that is not simply mysterious, but something creepy in a strangely familiar way. This is almost the perfect description of watching Detour its eerie nature means that we are not only frequently second-guessed about where the film is going, but are often uncertain whether we are watching the usual objective perspective offered by cinema. In particular, are all the ham-fisted segues, stilted dialogue and inscrutable character motivations actually a product of Al inventing a story for the viewer? Did he murder Haskell after all, despite the film 'showing' us that Haskell died of natural causes? In other words, are we watching what Al wants us to believe? Regardless of the answers to these questions, the film succeeds precisely because of its accidental or inadvertent choices, so it is an implicit reminder that seeking the director's original intention in any piece of art is a complete mirage. Detour is certainly not a good film, but it just might be a great one. (It is a short film too, and, out of copyright, it is available online for free.)

Safe (1995) Safe is a subtly disturbing film about an upper-middle-class housewife who begins to complain about vague symptoms of illness. Initially claiming that she doesn't feel right, Carol starts to have unexplained headaches, a dry cough and nosebleeds, and eventually begins to have trouble breathing. Carol's family doctor treats her concerns with little care, and suggests to her husband that she sees a psychiatrist. Yet Carol's episodes soon escalate. For example, as a 'homemaker' and with nothing else to occupy her, Carol's orders a new couch for a party. But when the store delivers the wrong one (although it is not altogether clear that they did), Carol has a near breakdown. Unsure where to turn, an 'allergist' tells Carol she has "Environmental Illness," and so Carol eventually checks herself into a new-age commune filled with alternative therapies. On the surface, Safe is thus a film about the increasing about of pesticides and chemicals in our lives, something that was clearly felt far more viscerally in the 1990s. But it is also a film about how lack of genuine healthcare for women must be seen as a critical factor in the rise of crank medicine. (Indeed, it made for something of an uncomfortable watch during the coronavirus lockdown.) More interestingly, however, Safe gently-yet-critically examines the psychosocial causes that may be aggravating Carol's illnesses, including her vacant marriage, her hollow friends and the 'empty calorie' stimulus of suburbia. None of this should be especially new to anyone: the gendered Victorian term 'hysterical' is often all but spoken throughout this film, and perhaps from the very invention of modern medicine, women's symptoms have often regularly minimised or outright dismissed. (Hilary Mantel's 2003 memoir, Giving Up the Ghost is especially harrowing on this.) As I opened this review, the film is subtle in its messaging. Just to take one example from many, the sound of the cars is always just a fraction too loud: there's a scene where a group is eating dinner with a road in the background, and the total effect can be seen as representing the toxic fumes of modernity invading our social lives and health. I won't spoiler the conclusion of this quietly devasting film, but don't expect a happy ending.

The Driver (1978) Critics grossly misunderstood The Driver when it was first released. They interpreted the cold and unemotional affect of the characters with the lack of developmental depth, instead of representing their dissociation from the society around them. This reading was encouraged by the fact that the principal actors aren't given real names and are instead known simply by their archetypes instead: 'The Driver', 'The Detective', 'The Player' and so on. This sort of quasi-Jungian erudition is common in many crime films today (Reservoir Dogs, Kill Bill, Layer Cake, Fight Club), so the critics' misconceptions were entirely reasonable in 1978. The plot of The Driver involves the eponymous Driver, a noted getaway driver for robberies in Los Angeles. His exceptional talent has far prevented him from being captured thus far, so the Detective attempts to catch the Driver by pardoning another gang if they help convict the Driver via a set-up robbery. To give himself an edge, however, The Driver seeks help from the femme fatale 'Player' in order to mislead the Detective. If this all sounds eerily familiar, you would not be far wrong. The film was essentially remade by Nicolas Winding Refn as Drive (2011) and in Edgar Wright's 2017 Baby Driver. Yet The Driver offers something that these neon-noir variants do not. In particular, the car chases around Los Angeles are some of the most captivating I've seen: they aren't thrilling in the sense of tyre squeals, explosions and flying boxes, but rather the vehicles come across like wild animals hunting one another. This feels especially so when the police are hunting The Driver, which feels less like a low-stakes game of cat and mouse than a pack of feral animals working together a gang who will tear apart their prey if they find him. In contrast to the undercar neon glow of the Fast & Furious franchise, the urban realism backdrop of the The Driver's LA metropolis contributes to a sincere feeling of artistic fidelity as well. To be sure, most of this is present in the truly-excellent Drive, where the chase scenes do really communicate a credible sense of stakes. But the substitution of The Driver's grit with Drive's soft neon tilts it slightly towards that common affliction of crime movies: style over substance. Nevertheless, I can highly recommend watching The Driver and Drive together, as it can tell you a lot about the disconnected socioeconomic practices of the 1980s compared to the 2010s. More than that, however, the pseudo-1980s synthwave soundtrack of Drive captures something crucial to analysing the world of today. In particular, these 'sounds from the past filtered through the present' bring to mind the increasing role of nostalgia for lost futures in the culture of today, where temporality and pop culture references are almost-exclusively citational and commemorational.

The Souvenir (2019) The ostensible outline of this quietly understated film follows a shy but ambitious film student who falls into an emotionally fraught relationship with a charismatic but untrustworthy older man. But that doesn't quite cover the plot at all, for not only is The Souvenir a film about a young artist who is inspired, derailed and ultimately strengthened by a toxic relationship, it is also partly a coming-of-age drama, a subtle portrait of class and, finally, a film about the making of a film. Still, one of the geniuses of this truly heartbreaking movie is that none of these many elements crowds out the other. It never, ever feels rushed. Indeed, there are many scenes where the camera simply 'sits there' and quietly observes what is going on. Other films might smother themselves through references to 18th-century oil paintings, but The Souvenir somehow evades this too. And there's a certain ring of credibility to the story as well, no doubt in part due to the fact it is based on director Joanna Hogg's own experiences at film school. A beautifully observed and multi-layered film; I'll be happy if the sequel is one-half as good.

The Wrestler (2008) Randy 'The Ram' Robinson is long past his prime, but he is still rarin' to go in the local pro-wrestling circuit. Yet after a brutal beating that seriously threatens his health, Randy hangs up his tights and pursues a serious relationship... and even tries to reconnect with his estranged daughter. But Randy can't resist the lure of the ring, and readies himself for a comeback. The stage is thus set for Darren Aronofsky's The Wrestler, which is essentially about what drives Randy back to the ring. To be sure, Randy derives much of his money from wrestling as well as his 'fitness', self-image, self-esteem and self-worth. Oh, it's no use insisting that wrestling is fake, for the sport is, needless to say, Randy's identity; it's not for nothing that this film is called The Wrestler. In a number of ways, The Sound of Metal (2019) is both a reaction to (and a quiet remake of) The Wrestler, if only because both movies utilise 'cool' professions to explore such questions of identity. But perhaps simply when The Wrestler was produced makes it the superior film. Indeed, the role of time feels very important for the Wrestler. In the first instance, time is clearly taking its toll on Randy's body, but I felt it more strongly in the sense this was very much a pre-2008 film, released on the cliff-edge of the global financial crisis, and the concomitant precarity of the 2010s. Indeed, it is curious to consider that you couldn't make The Wrestler today, although not because the relationship to work has changed in any fundamentalway. (Indeed, isn't it somewhat depressing the realise that, since the start of the pandemic and the 'work from home' trend to one side, we now require even more people to wreck their bodies and mental health to cover their bills?) No, what I mean to say here is that, post-2016, you cannot portray wrestling on-screen without, how can I put it, unwelcome connotations. All of which then reminds me of Minari's notorious red hat... But I digress. The Wrestler is a grittily stark darkly humorous look into the life of a desperate man and a sorrowful world, all through one tragic profession.

Thief (1981) Frank is an expert professional safecracker and specialises in high-profile diamond heists. He plans to use his ill-gotten gains to retire from crime and build a life for himself with a wife and kids, so he signs on with a top gangster for one last big score. This, of course, could be the plot to any number of heist movies, but Thief does something different. Similar to The Wrestler and The Driver (see above) and a number of other films that I watched this year, Thief seems to be saying about our relationship to work and family in modernity and postmodernity. Indeed, the 'heist film', we are told, is an understudied genre, but part of the pleasure of watching these films is said to arise from how they portray our desired relationship to work. In particular, Frank's desire to pull off that last big job feels less about the money it would bring him, but a displacement from (or proxy for) fulfilling some deep-down desire to have a family or indeed any relationship at all. Because in theory, of course, Frank could enter into a fulfilling long-term relationship right away, without stealing millions of dollars in diamonds... but that's kinda the entire point: Frank needing just one more theft is an excuse to not pursue a relationship and put it off indefinitely in favour of 'work'. (And being Federal crimes, it also means Frank cannot put down meaningful roots in a community.) All this is communicated extremely subtly in the justly-lauded lowkey diner scene, by far the best scene in the movie. The visual aesthetic of Thief is as if you set The Warriors (1979) in a similarly-filthy Chicago, with the Xenophon-inspired plot of The Warriors replaced with an almost deliberate lack of plot development... and the allure of The Warriors' fantastical criminal gangs (with their alluringly well-defined social identities) substituted by a bunch of amoral individuals with no solidarity beyond the immediate moment. A tale of our time, perhaps. I should warn you that the ending of Thief is famously weak, but this is a gritty, intelligent and strangely credible heist movie before you get there.

Uncut Gems (2019) The most exhausting film I've seen in years; the cinematic equivalent of four cups of double espresso, I didn't even bother even trying to sleep after downing Uncut Gems late one night. Directed by the two Safdie Brothers, it often felt like I was watching two films that had been made at the same time. (Or do I mean two films at 2X speed?) No, whatever clumsy metaphor you choose to adopt, the unavoidable effect of this film's finely-tuned chaos is an uncompromising and anxiety-inducing piece of cinema. The plot follows Howard as a man lost to his countless vices mostly gambling with a significant side hustle in adultery, but you get the distinct impression he would be happy with anything that will give him another high. A true junkie's junkie, you might say. You know right from the beginning it's going to end in some kind of disaster, the only question remaining is precisely how and what. Portrayed by an (almost unrecognisable) Adam Sandler, there's an uncanny sense of distance in the emotional chasm between 'Sandler-as-junkie' and 'Sandler-as-regular-star-of-goofy-comedies'. Yet instead of being distracting and reducing the film's affect, this possibly-deliberate intertextuality somehow adds to the masterfully-controlled mayhem. My heart races just at the memory. Oof.

Woman in the Dunes (1964) I ended up watching three films that feature sand this year: Denis Villeneuve's Dune (2021), Lawrence of Arabia (1962) and Woman in the Dunes. But it is this last 1964 film by Hiroshi Teshigahara that will stick in my mind in the years to come. Sure, there is none of the Medician intrigue of Dune or the Super Panavision-70 of Lawrence of Arabia (or its quasi-orientalist score, itself likely stolen from Anton Bruckner's 6th Symphony), but Woman in the Dunes doesn't have to assert its confidence so boldly, and it reveals the enormity of its plot slowly and deliberately instead. Woman in the Dunes never rushes to get to the film's central dilemma, and it uncovers its terror in little hints and insights, all whilst establishing the daily rhythm of life. Woman in the Dunes has something of the uncanny horror as Dogtooth (see above), as well as its broad range of potential interpretations. Both films permit a wide array of readings, without resorting to being deliberately obscurantist or being just plain random it is perhaps this reason why I enjoyed them so much. It is true that asking 'So what does the sand mean?' sounds tediously sophomoric shorn of any context, but it somehow applies to this thoughtfully self-contained piece of cinema.

A Quiet Place (2018) Although A Quiet Place was not actually one of the best films I saw this year, I'm including it here as it is certainly one of the better 'mainstream' Hollywood franchises I came across. Not only is the film very ably constructed and engages on a visceral level, I should point out that it is rare that I can empathise with the peril of conventional horror movies (and perhaps prefer to focus on its cultural and political aesthetics), but I did here. The conceit of this particular post-apocalyptic world is that a family is forced to live in almost complete silence while hiding from creatures that hunt by sound alone. Still, A Quiet Place engages on an intellectual level too, and this probably works in tandem with the pure 'horrorific' elements and make it stick into your mind. In particular, and to my mind at least, A Quiet Place a deeply American conservative film below the surface: it exalts the family structure and a certain kind of sacrifice for your family. (The music often had a passacaglia-like strain too, forming a tombeau for America.) Moreover, you survive in this dystopia by staying quiet that is to say, by staying stoic suggesting that in the wake of any conflict that might beset the world, the best thing to do is to keep quiet. Even communicating with your loved ones can be deadly to both of you, so not emote, acquiesce quietly to your fate, and don't, whatever you do, speak up. (Or join a union.) I could go on, but The Quiet Place is more than this. It's taut and brief, and despite cinema being an increasingly visual medium, it encourages its audience to develop a new relationship with sound.

14 January 2022

Norbert Preining: Future of my packages in Debian

After having been (again) demoted (timed perfectly to my round birthday!) based on flimsy arguments, I have been forced to rethink the level of contribution I want to do for Debian. Considering in particular that I have switched my main desktop to dual-boot into Arch Linux (all on the same btrfs fs with subvolumes, great!) and have run Arch now for several days exclusively, I think it is time to review the packages I am somehow responsible for (full list of packages). After about 20 years in Debian, time to send off quite some stuff that has accumulated over time. KDE/Plasma, frameworks, Gears, and related packages All these packages are group maintained, so there is not much to worry about. Furthermore, a few new faces have joined the team and are actively working on the packages, although mostly on Qt6. I guess that with me not taking action, frameworks, gears, and plasma will fall back over time (frameworks: Debian 5.88 versus current 5.90, gears: Debian 21.08 versus current 21.12, plasma uptodate at the moment). With respect to my packages on OBS, they will probably also go stale over time. Using Arch nowadays I lack the development tools necessary to build Debian packages, and above all, the motivation. I am sorry for all those who have learned to rely on my OBS packages over the last years, bringing modern and uptodate KDE/Plasma to Debian/stable, please direct your complaints at the responsible entities in Debian. Cinnamon As I have written already here, I have reduced my involvement quite a lot, and nowadays Fabio and Joshua are doing the work. But both are not even DM (AFAIR) and I am the only one doing uploads (I got DM upload permissions for it). But I am not sure how long I will continue doing this. This also means that in the near future, Cinnamon will also go stale. TeX related packages Hilmar has DM upload permissions and is very actively caring for the packages, so I don t see any source of concern here. New packages will need to find a new uploader, though. With myself also being part of upstream, I can surely help out in the future with difficult problems. Calibre and related packages Yokota-san (another DM I have sponsored) has DM upload permissions and is very actively caring for the packages, so also here there is not much of concern. Onedrive This is already badly outdated, and I recommend using the OBS builds which are current and provide binaries for Ubuntu and Debian for various versions. ROCm Here fortunately a new generation of developers has taken over maintenance and everything is going smoothly, much better than I could have done, yeah to that! Qalculate related packages These are group maintained, but unfortunately nobody else but me has touched the repos for quite some time. I fear that the packages will go stale rather soon. isync/mbsync I have recently salvaged this package, and use it daily, but I guess it needs to be orphaned sooner or later. CafeOBJ While I am also part of upstream here, I guess it will be orphaned. Julia Julia is group maintained, but unfortunately nobody else but me has touched the repo for quite some time, and we are already far behind the normal releases (and julia got removed from testing). While go stale/orphaned. I recommend installing upstream binaries. python-mechanize Another package that is group maintained in the Python team, but with only me as uploader I guess it will go stale and effectively be orphaned soon. xxhash Has already by orphaned. qpdfview No upstream development, so not much to do, but will be orphaned, too.

9 January 2022

Matthew Garrett: Pluton is not (currently) a threat to software freedom

At CES this week, Lenovo announced that their new Z-series laptops would ship with AMD processors that incorporate Microsoft's Pluton security chip. There's a fair degree of cynicism around whether Microsoft have the interests of the industry as a whole at heart or not, so unsurprisingly people have voiced concerns about Pluton allowing for platform lock-in and future devices no longer booting non-Windows operating systems. Based on what we currently know, I think those concerns are understandable but misplaced.

But first it's helpful to know what Pluton actually is, and that's hard because Microsoft haven't actually provided much in the way of technical detail. The best I've found is a discussion of Pluton in the context of Azure Sphere, Microsoft's IoT security platform. This, in association with the block diagrams on page 12 and 13 of this slidedeck, suggest that Pluton is a general purpose security processor in a similar vein to Google's Titan chip. It has a relatively low powered CPU core, an RNG, and various hardware cryptography engines - there's nothing terribly surprising here, and it's pretty much the same set of components that you'd find in a standard Trusted Platform Module of the sort shipped in pretty much every modern x86 PC. But unlike Titan, Pluton seems to have been designed with the explicit goal of being incorporated into other chips, rather than being a standalone component. In the Azure Sphere case, we see it directly incorporated into a Mediatek chip. In the Xbox Series devices, it's incorporated into the SoC. And now, we're seeing it arrive on general purpose AMD CPUs.

Microsoft's announcement says that Pluton can be shipped in three configurations:as the Trusted Platform Module; as a security processor used for non-TPM scenarios like platform resiliency; or OEMs can choose to ship with Pluton turned off. What we're likely to see to begin with is the former - Pluton will run firmware that exposes a Trusted Computing Group compatible TPM interface. This is almost identical to the status quo. Microsoft have required that all Windows certified hardware ship with a TPM for years now, but for cost reasons this is often not in the form of a separate hardware component. Instead, both Intel and AMD provide support for running the TPM stack on a component separate from the main execution cores on the system - for Intel, this TPM code runs on the Management Engine integrated into the chipset, and for AMD on the Platform Security Processor that's integrated into the CPU package itself.

So in this respect, Pluton changes very little; the only difference is that the TPM code is running on hardware dedicated to that purpose, rather than alongside other code. Importantly, in this mode Pluton will not do anything unless the system firmware or OS ask it to. Pluton cannot independently block the execution of any other code - it knows nothing about the code the CPU is executing unless explicitly told about it. What the OS can certainly do is ask Pluton to verify a signature before executing code, but the OS could also just verify that signature itself. Windows can already be configured to reject software that doesn't have a valid signature. If Microsoft wanted to enforce that they could just change the default today, there's no need to wait until everyone has hardware with Pluton built-in.

The two things that seem to cause people concerns are remote attestation and the fact that Microsoft will be able to ship firmware updates to Pluton via Windows Update. I've written about remote attestation before, so won't go into too many details here, but the short summary is that it's a mechanism that allows your system to prove to a remote site that it booted a specific set of code. What's important to note here is that the TPM (Pluton, in the scenario we're talking about) can't do this on its own - remote attestation can only be triggered with the aid of the operating system. Microsoft's Device Health Attestation is an example of remote attestation in action, and the technology definitely allows remote sites to refuse to grant you access unless you booted a specific set of software. But there are two important things to note here: first, remote attestation cannot prevent you from booting whatever software you want, and second, as evidenced by Microsoft already having a remote attestation product, you don't need Pluton to do this! Remote attestation has been possible since TPMs started shipping over two decades ago.

The other concern is Microsoft having control over the firmware updates. The context here is that TPMs are not magically free of bugs, and sometimes these can have security consequences. One example is Infineon TPMs producing weak RSA keys, a vulnerability that could be rectified by a firmware update to the TPM. Unfortunately these updates had to be issued by the device manufacturer rather than Infineon being able to do so directly. This meant users had to wait for their vendor to get around to shipping an update, something that might not happen at all if the machine was sufficiently old. From a security perspective, being able to ship firmware updates for the TPM without them having to go through the device manufacturer is a huge win.

Microsoft's obviously in a position to ship a firmware update that modifies the TPM's behaviour - there would be no technical barrier to them shipping code that resulted in the TPM just handing out your disk encryption secret on demand. But Microsoft already control the operating system, so they already have your disk encryption secret. There's no need for them to backdoor the TPM to give them something that the TPM's happy to give them anyway. If you don't trust Microsoft then you probably shouldn't be running Windows, and if you're not running Windows Microsoft can't update the firmware on your TPM.

So, as of now, Pluton running firmware that makes it look like a TPM just isn't a terribly interesting change to where we are already. It can't block you running software (either apps or operating systems). It doesn't enable any new privacy concerns. There's no mechanism for Microsoft to forcibly push updates to it if you're not running Windows.

Could this change in future? Potentially. Microsoft mention another use-case for Pluton "as a security processor used for non-TPM scenarios like platform resiliency", but don't go into any more detail. At this point, we don't know the full set of capabilities that Pluton has. Can it DMA? Could it play a role in firmware authentication? There are scenarios where, in theory, a component such as Pluton could be used in ways that would make it more difficult to run arbitrary code. It would be reassuring to hear more about what the non-TPM scenarios are expected to look like and what capabilities Pluton actually has.

But let's not lose sight of something more fundamental here. If Microsoft wanted to block free operating systems from new hardware, they could simply mandate that vendors remove the ability to disable secure boot or modify the key databases. If Microsoft wanted to prevent users from being able to run arbitrary applications, they could just ship an update to Windows that enforced signing requirements. If they want to be hostile to free software, they don't need Pluton to do it.

(Edit: it's been pointed out that I kind of gloss over the fact that remote attestation is a potential threat to free software, as it theoretically allows sites to block access based on which OS you're running. There's various reasons I don't think this is realistic - one is that there's just way too much variability in measurements for it to be practical to write a policy that's strict enough to offer useful guarantees without also blocking a number of legitimate users, and the other is that you can just pass the request through to a machine that is running the appropriate software and have it attest for you. The fact that nobody has actually bothered to use remote attestation for this purpose even though most consumer systems already ship with TPMs suggests that people generally agree with me on that)

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8 January 2022

John Goerzen: Make the Internet Yours Again With an Instant Mesh Network

I m going to lead with the technical punch line, and then explain it: Yggdrasil Network is an opportunistic mesh that can be deployed privately or as part of a global-scale network. Each node gets a stable IPv6 address (or even an entire /64) that is derived from its public key and is bound to that node as long as the node wants it (of course, it can generate a new keypair anytime) and is valid wherever the node joins the mesh. All traffic is end-to-end encrypted. Yggdrasil will automatically discover peers on a LAN via broadcast beacons, and requires zero configuration to peer in such a way. It can also run as an overlay network atop the public Internet. Public peers serve as places to join the global network, and since it s a mesh, if one device on your LAN joins the global network, the others will automatically have visibility on it also, thanks to the mesh routing. It neatly solves a lot of problems of portability (my ssh sessions stay live as I move networks, for instance), VPN (incoming ports aren t required since local nodes can connect to a public peer via an outbound connection), security, and so forth. Now on to the explanation: The Tyranny of IP rigidity Every device on the Internet, at one time, had its own globally-unique IP address. This number was its identifier to the world; with an IP address, you can connect to any machine anywhere. Even now, when you connect to a computer to download a webpage or send a message, under the hood, your computer is talking to the other one by IP address. Only, now it s hard to get one. The Internet protocol we all grew up with, version 4 (IPv4), didn t have enough addresses for the explosive growth we ve seen. Internet providers and IT departments had to use a trick called NAT (Network Address Translation) to give you a sort of fake IP address, so they could put hundreds or thousands of devices behind a single public one. That, plus the mobility of devices changing IPs whenever they change locations has meant that a fundamental rule of the old Internet is now broken: Every participant is an equal peer. (Well, not any more.) Nowadays, you can t you host your own website from your phone. Or share files from your house. (Without, that is, the use of some third-party service that locks you down and acts as an intermediary.) Back in the 90s, I worked at a university, and I, like every other employee, had a PC on my desk with an unfirewalled public IP. I installed a webserver, and poof instant website. Nowadays, running a website from home is just about impossible. You may not have a public IP, and if you do, it likely changes from time to time. And even then, your ISP probably blocks you from running servers on it. In short, you have to buy your way into the resources to participate on the Internet. I wrote about these problems in more detail in my article Recovering Our Lost Free Will Online. Enter Yggdrasil I already gave away the punch line at the top. But what does all that mean?
  • Every device that participates gets an IP address that is fully live on the Yggdrasil network.
  • You can host a website, or a mail server, or whatever you like with your Yggdrasil IP.
  • Encryption and authentication are smaller (though not nonexistent) worries thanks to the built-in end-to-end encryption.
  • You can travel the globe, and your IP will follow you: onto a plane, from continent to continent, wherever. Yggdrasil will find you.
  • I ve set up /etc/hosts on my laptop to use the Yggdrasil IPs for other machines on my LAN. Now I can just ssh foo and it will work from home, from a coffee shop, from a 4G tether, wherever. Now, other tools like tinc can do this, obviously. And I could stop there; I could have a completely closed, private Yggdrasil network. Or, I can join the global Yggdrasil network. Each device, in addition to accepting peers it finds on the LAN, can also be configured to establish outbound peering connections or accept inbound ones over the Internet. Put a public peer or two in your configuration and you ve joined the global network. Most people will probably want to do that on every device (because why not?), but you could also do that from just one device on your LAN. Again, there s no need to explicitly build routes via it; your other machines on the LAN will discover the route s existence and use it. This is one of many projects that are working to democratize and decentralize the Internet. So far, it has been quite successful, growing to over 2000 nodes. It is the direct successor to the earlier cjdns/Hyperboria and BATMAN networks, and aims to be a proof of concept and a viable tool for global expansion. Finally, think about how much easier development is when you don t have to necessarily worry about TLS complexity in every single application. When you don t have to worry about port forwarding and firewall penetration. It s what the Internet should be.

    5 January 2022

    Reproducible Builds: Reproducible Builds in December 2021

    Welcome to the December 2021 report from the Reproducible Builds project! In these reports, we try and summarise what we have been up to over the past month, as well as what else has been occurring in the world of software supply-chain security. As a quick recap of what reproducible builds is trying to address, whilst anyone may inspect the source code of free software for malicious flaws, almost all software is distributed to end users as pre-compiled binaries. The motivation behind the reproducible builds effort is to ensure no flaws have been introduced during this compilation process by promising identical results are always generated from a given source, thus allowing multiple third-parties to come to a consensus on whether a build was compromised. As always, if you would like to contribute to the project, please get in touch with us directly or visit the Contribute page on our website.
    Early in December, Julien Voisin blogged about setting up a rebuilderd instance in order to reproduce Tails images. Working on previous work from 2018, Julien has now set up a public-facing instance which is providing build attestations. As Julien dryly notes in his post, Currently, this isn t really super-useful to anyone, except maybe some Tails developers who want to check that the release manager didn t backdoor the released image. Naturally, we would contend sincerely that this is indeed useful.
    The secure/anonymous Tor browser now supports reproducible source releases. According to the project s changelog, version 0.4.7.3-alpha of Tor can now build reproducible tarballs via the make dist-reprod command. This issue was tracked via Tor issue #26299.
    Fabian Keil posted a question to our mailing list this month asking how they might analyse differences in images produced with the FreeBSD and ElectroBSD s mkimg and makefs commands:
    After rebasing ElectroBSD from FreeBSD stable/11 to stable/12
    I recently noticed that the "memstick" images are unfortunately
    still not 100% reproducible.
    Fabian s original post generated a short back-and-forth with Chris Lamb regarding how diffoscope might be able to support the particular format of images generated by this command set.

    diffoscope diffoscope is our in-depth and content-aware diff utility. Not only can it locate and diagnose reproducibility issues, it can provide human-readable diffs from many kinds of binary formats. This month, Chris Lamb prepared and uploading versions 195, 196, 197 and 198 to Debian, as well as made the following changes:
    • Support showing Ordering differences only within .dsc field values. [ ]
    • Add support for XMLb files. [ ]
    • Also add, for example, /usr/lib/x86_64-linux-gnu to our local binary search path. [ ]
    • Support OCaml versions 4.11, 4.12 and 4.13. [ ]
    • Drop some unnecessary has_same_content_as logging calls. [ ]
    • Replace token variable with an anonymously-named variable instead to remove extra lines. [ ]
    • Don t use the runtime platform s native endianness when unpacking .pyc files. This fixes test failures on big-endian machines. [ ]
    Mattia Rizzolo also made a number of changes to diffoscope this month as well, such as:
    • Also recognize GnuCash files as XML. [ ]
    • Support the pgpdump PGP packet visualiser version 0.34. [ ]
    • Ignore the new Lintian tag binary-with-bad-dynamic-table. [ ]
    • Fix the Enhances field in debian/control. [ ]
    Finally, Brent Spillner fixed the version detection for Black uncompromising code formatter [ ], Jelle van der Waa added an external tool reference for Arch Linux [ ] and Roland Clobus added support for reporting when the GNU_BUILD_ID field has been modified [ ]. Thank you for your contributions!

    Distribution work In Debian this month, 70 reviews of packages were added, 27 were updated and 41 were removed, adding to our database of knowledge about specific issues. A number of issue types were created as well, including: strip-nondeterminism version 1.13.0-1 was uploaded to Debian unstable by Holger Levsen. It included contributions already covered in previous months as well as new ones from Mattia Rizzolo, particularly that the dh_strip_nondeterminism Debian integration interface uses the new get_non_binnmu_date_epoch() utility when available: this is important to ensure that strip-nondeterminism does not break some kinds of binNMUs.
    In the world of openSUSE, however, Bernhard M. Wiedemann posted his monthly reproducible builds status report.
    In NixOS, work towards the longer-term goal of making the graphical installation image reproducible is ongoing. For example, Artturin made the gnome-desktop package reproducible.

    Upstream patches The Reproducible Builds project attempts to fix as many currently-unreproducible packages as possible. In December, we wrote a large number of such patches, including:

    Testing framework The Reproducible Builds project runs a significant testing framework at tests.reproducible-builds.org, to check packages and other artifacts for reproducibility. This month, the following changes were made:
    • Holger Levsen:
      • Run the Debian scheduler less often. [ ]
      • Fix the name of the Debian testing suite name. [ ]
      • Detect builds that are rescheduling due to problems with the diffoscope container. [ ]
      • No longer special-case particular machines having a different /boot partition size. [ ]
      • Automatically fix failed apt-daily and apt-daily-upgrade services [ ], failed e2scrub_all.service & user@ systemd units [ ][ ] as well as generic build failures [ ].
      • Simplify a script to powercycle arm64 architecture nodes hosted at/by codethink.co.uk. [ ]
      • Detect if the udd-mirror.debian.net service is down. [ ]
      • Various miscellaneous node maintenance. [ ][ ]
    • Roland Clobus (Debian live image generation):
      • If the latest snapshot is not complete yet, try to use the previous snapshot instead. [ ]
      • Minor: whitespace correction + comment correction. [ ]
      • Use unique folders and reports for each Debian version. [ ]
      • Turn off debugging. [ ]
      • Add a better error description for incorrect/missing arguments. [ ]
      • Report non-reproducible issues in Debian sid images. [ ]
    Lastly, Mattia Rizzolo updated the automatic logfile parsing rules in a number of ways (eg. to ignore a warning about the Python setuptools deprecation) [ ][ ] and Vagrant Cascadian adjusted the config for the Squid caching proxy on a node. [ ]

    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:

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