Comment by lrvick
2 years ago
I totally grant that the nix system is good at making sure that a given git commit produces a given result. They do a fantastic job at everything from miles 2-10. They just skip the first mile of integrity, which is also one of the easiest to tamper with.
9/10 popular package developers I audit have SMS as a backup account recovery method on their email accounts. Easy to see when I try to reset their email passwords and it says "sms sent to ....". One sim swap and I have the account of a popular package maintainer.
Or, even easier, developers often use custom email domains. Right now there are -thousands- of custom email domains used by package maintainers in NPM for instance, that are expired. Buy domain, and you buy access to contribute commits to an unpopular unnoticed package that a popular package depends on.
Supply chain attacks are my core area of research, and they are easy to do. They are hard to defend against unless you have reproducible builds already. It is crazy NixOS has done so much good work for supply chain integrity and refuses to do the first mile almost every other popular linux distro already makes at least some attempt at.
As for PGP key theft, most people that use PGP today keep the keys on personal HSMs, like a yubikey or nitrokey, such that the private key never comes in contact with the memory of an internet connected computer. Stealing one in most cases would require keylogging the pin, and physically stealing the key.
If you got malware on someones machine, you could still manipulate them at that point in time, though this still will require timing your attack so that they are online and tricking them to tap their key, which dramatically increases attack complexity.
Next level once people sign commits though, is signing code reviews. Then you have removed all single points of failure from your software supply chain.
You're talking sense, but this is due diligence for a developer, not for an operating system or a package manager.
You're free to map your package definitions to the commits they contain and verify any signatures that you find there, but that process will have nothing to do with whether other people have signed the instructions that your machine follows to fetch and build the contents of that commit.
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.
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.
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