Comment 20 for bug 2048781

I continued exploring this topic myself last week and was able to rely on a tool developed for this: https://github.com/coreos/cargo-vendor-filterer/.

This tool is not ideal in the sense that:
- it vendorize the whole content
- then, it filters by replacing entire crates based on some filtering rules, like arch, platform or file exclusion. The replacement is done by empty module, and rechecksumming.

So basically, cargo and rustc still thinks the crate is available, it just happens to be empty. Consequently, we wouldn’t know if we are impacted or not by security issue before manual checking.

However, I see this as a step in the right direction, so I implemented this in authd: https://github.com/ubuntu/authd/pull/270/files. Here, we are filtering to only keep Linux platform, on all our supported architectures (which is tier 1 and 2 in Rust world).
The benefit is that we are now able to remove our manual recheckshumming after purging the binary library archive files which are part of some crates.

This tool run during the package source build. I would feel better if this was packaged and maintained in ubuntu (as this injects potentially some code), and part of our standard tooling. I will reach out the Rust maintainer for the incoming engineering sprint. I think we can still trust this repository as it’s part of a well-known organization with multi-decades open source famous maintainers.