[lrvick]

Sure I could write a lot of tooling to try and do this sort of basic verification manually in Nix every single time i pin a new package, but at that point why am I using nix over distros that have native support for maintainer level supply chain integrity?

Compare to the Arch model where all official packages must be signed with keys belonging to a reasonably well vetted web of trust.

Developers outside the web of trust that want to contribute yolo unsigned packages to Arch still can, but those must go into AUR where users must opt-in to and manually review each individual untrusted/unsigned package.

https://wiki.archlinux.org/title/Pacman/Package_signing

Nix decided to have the yolo AUR model by default, with no method to elect to use only signed packages, because signing and web of trust are not even supported at all, even optionally.

This is wildly irresponsible given how many people use Nix today.

Nix is two steps forward in deterministic, immutable, and unprivileged package management, and one giant leap backwards in supply chain integrity.

This is why we cannot have nice things.

[__MatrixMan__]

Nix is two steps forward in these ways because they chose to focus on making things composable and repeatable instead of being curators of quality and trustworthiness.

One magical thing about Nix is that there's a very small divide between managing to install software in the first place and creating an artifact that others can use for the same purpose.

Because of this, practically every NixOS user has their configuration in source control--we're basically each building our own Linux distro with only packages that we trust. Some of us probably sign those commits too.

The ecosystem is useful because it encourages this kind if participation. Having a list of privileged maintainers would interrupt this.

It's unsurprising that a group of people who has worked quite hard to make this possible would be uninterested in creating a scheme whereby they are now responsible for determining which of their users creations is legitimate. Nix attracts users who are interested in that sort of thing, so let it be a userspace problem.

If you want to curate a list of trustworthy packages and work with their developers to set up a chain of trust that starts in a yubikey extends to a signature in a flake output, then I'll help because that sounds like useful work, but I wish you would stop criticizing a brick for not already being a house.

[lrvick]

My criticism is not so much on NixOS itself. If it wants to be a fun, composable, and easy to work on with minimal participation friction, fair enough. The yolo approach to contribution integrity has clearly resulted in fast development of ideas that might have been unable to grow in other distros.

I suppose where my, perhaps misdirected, anxiety comes from is that I run a security consulting company and see NixOS being used as-is in high risk applications, to compile binaries responsible for protecting peoples property or safety, and on the workstations of production engineering teams. Places where it has no business being because supply chain integrity is a non goal.

Maybe you are right though, and the answer is not trying to add supply chain security practices onto a community that does not want them, but to create a security focused fork of that distro that can inherit all that great community work and be a drop-in replacement for NixOS in environments where supply chain security is of critical importance.

I tried and failed to get buy-in for even -optional- expression integrity support back in 2018 and gave up on nix after that. https://github.com/NixOS/rfcs/pull/34

I did prototype a git multisig solution in the years following that though: https://git.distrust.co/public/supsig https://git.distrust.co/public/git-sig

It is already being used in production by some as nothing better exists atm.

A security focused Nix fork that imports, reviews, and git-sig (or similar) signs commits from NixOS and has signature verification built into the package manager, is probably the only way forward, and I would be willing to ally with others interested in this.

[__MatrixMan__]

"A fork of nix" sounds awful drastic. Seems like you just need a curated list of packages which conform to some standard re:

- getting a dev sig when they get the code

- checking that sig

- adding a packager sig

And then you need to somehow inject a check before the user comes in contact with the outputs:

> are these signers in my trusted list?

Your users can then enable dev-sig-mode and point their sig checker at the list of keys. Hopefully that's less than whatever a fork of the whole OS entails.

Rather than framing it as a move towards signatures for all of NixOS, I'd frame it as you have a community of users who are willing to maintain a list of trusted keys and work with developers to standardize signature hand-off, and you want to add experimeny features to serve the little pocket of Nixdom that you're carving out for those users.

Avoid anything that smells like you're expecting NixOS act as an authority over which packages are trustworthy and for its devs do the political work of maintaining that list on behalf of the users. Many of us have landed at NixOS because we want less of that top-down nanny business, but we probably like the idea that users would themselves configure such a list.

I can maybe help come up with a standard flow for the signature hand-off, but the harder thing will be intercepting the myriad ways that a user might come in contact with derivation outputs and putting a sig check in their path. You may need another ally that knows the guts better than I do, not just the packaging side of things.

Hopefully we don't have to tamper with nix-env and nix-shell and `nix flake build` and `nix flake run` and `nix flake develop` all separately. Hopefully there's some common place where inbound bits can be checked regardless of how the user has asked for them.

[lrvick]

I went to Nix liking everything about it except the fact there was no way to even -optionally- add signatures to NixOS core component contributions and package expressions, let alone verifying either of those as an end user.

I was informed the way to get changes into Nix was go ask the Nix Gods in the form of an RFC. I did that, and there was some interest, but ultimately it descended into bike shedding about optimal signing schemes and the idea was ultimately rejected by said Nix Gods. I felt very nannied to be honest, and felt I had to give up on nix.

I have had no viable alternatives but to use Arch and Debian for high security build systems across the industries I service and write all sorts of kludgy tools to hash pin packages to get deterministic results since that is what I can prove the integrity of back to the authors.

If you feel you have the social capital with nix leadership to try another RFC for an optional signature verifier hooked into nix user tools for both nix core and expressions, with optional signing from either authors or community members, that would be welcome progress and would certainly make me give the path of directly working with the nix community (vs forking) a second look.

My ideal would be to point nix at a repo of public keys, and nix would not download or execute anything whose supply chain did not start with those keys. This would be incredible for say docker build containers that only need small subsets of packages like compilers for a start... and then eventually a full bootable set of packages supported.

I would happily review any such proposals are capable of meeting threat models requiring high supply chain security.

Contact info on https://lance.dev

[__MatrixMan__]

I certainly don't have that social capital at right now, but I do intend to be hacking around in these areas in the future. If I get something useful working then I will probably be in a position to build that capital.

Because now that we have reframed it as something that puts users in explicit control of their trust graph and not something that would make NixOS like all the other distros, it's a feature that I'd like to use.

----

I'm working on a data annotation layer which I intend to apply as a filesystem and use nix and my test case. Edits are conceived of as annotations, so there's this sense that every file can be built by following a path of edits from the empty file. This makes for slow reads, but near-instant copies (you're just adding a new pointer at the same position in the edit graph as the file you're copying). It's a strange design choice, but it would solve some problems when using nix flakes with large repositories (everything gets copied into the nix store and it can take a while).

Signatures are exactly the sort of thing I was imagining living in an annotation. Ideally, the annotation adheres to patterns in the data and not the named file, so if the package applied a patch which invalidates the signature then the signature doubles as a link to the original, which can be diffed with the patched version and the user can be shown why it fails, not just that it fails. It's a long shot but that's the dream.

With a bit of luck I'll find a more elegant way to handle this without playing whack-a-mole with each user facing utility that builds a derivation. Maybe some kind of dashboard which shows you which files the system is rendering and whether they have associated signatures (or other metadata, known malicious, etc). The challenge, in the signature case, will be knowing which files are ok to be unsigned and which need to fail on read if not signed. Certainly we can't require a separate signature for every file we render.

It might be a long time coming though, this work proceeds on weekends and holidays and it's pretty far from a useful state. I'm still fiddling with tuning the rolling hash based fragmentation algorithm such that files are constructed out of right-sized fragments which end up being reused if the files are similar.