Prototype: Add --tls-details, only for non-remote pulling for now

[mtrmac]

This exposes containers/container-libs#623 , looking for ways to do that.

Absolutely untested at this point.

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Does this PR introduce a user-facing change?

New option --tls-details, for now with very limited scope.

[packit-as-a-service]

[NON-BLOCKING] Packit jobs failed. @containers/packit-build please check. Everyone else, feel free to ignore.

[mtrmac]

I think this highlights the basic design trade-offs:

• We can add --tls-details as a global option.
  • That automatically forwards it to libimage, and hopefully affects all image operations (but not any other operations), for fairly little work.
  • We will still need to scope/audit all other TLS users, and use the --tls-details option.
  • At a first glance it’s a bit unsatisfactory to have registry.PodmanConfig().TLSDetailsFile contain only the path, not the parsed data. The parsing code would have to be repeated in many users. There is probably a trivially way to do better here, I didn’t spend much time looking.
  • This doesn’t affect remote processes at all; how would the option get to the remote server??!
• We can add it as a per-operation option
  • Rather more tedious, but we would ~clearly delineate where we expect it to work and where it isn’t ready yet.
  • Clearly generalizes to remote operation: add the basetls.Config.MarshalText format as an option field.
  • Right now libimage.CopyOptions ignores the SystemContext field AFAICT. We don’t need to change that, we can add a new libimage.CopyOptions.BaseTLSConfig (perhaps preferring CopyOptions but falling back to the initialization-time runtime SystemContext).

[mtrmac]

Does this really need to be manually, separately from pkg/bindings/images.PullOptions? it It seems tedious and error-prone.

[mtrmac]

OK a minimal smoke test is promising:

# cat tls-details-pqc-only.yaml
minVersion: "1.3"
namedGroups:
  - "X25519MLKEM768"
# bin/podman --tls-details tls-details-pqc-only.yaml pull --retry 0 quay.io/foo
Trying to pull quay.io/foo:latest...
Error: unable to copy from source docker://quay.io/foo:latest: initializing source docker://quay.io/foo:latest: pinging container registry quay.io: Get "https://quay.io/v2/": EOF
# bin/podman  --tls-details tls-details-pqc-only.yaml push --retry 0 quay.io/libpod/alpine
Getting image source signatures
Error: trying to reuse blob sha256:03901b4a2ea88eeaad62dbe59b072b28b6efa00491962b8741081c5df50c65e0 at destination: pinging container registry quay.io: Get "https://quay.io/v2/": EOF

("EOF" is how the quay.io server reacts to the inability to negotiate a PQC group.)

Note that this does not yet include even login, which is critical to protect (but hopefully irrelevant to OpenShift).

[mtrmac]

@containers/podman-maintainers RFC on the approach. (In containers/container-libs#619 , Paul suggests not supporting the option for remote at all, or maybe exposing it as an option for the remote server only. That would certainly simplify things.)

[Luap99]

or maybe exposing it as an option for the remote server only.

Well my point is that it is already exposed for the server because it is a global option, podman --tls-details blah system service should work with that logic as it creates the same libpod (and thus libimage) runtime that a podman pull/run would also use. So in that sense this should work?

[mtrmac]

podman --tls-details blah system service should work with that logic

I think so, the way the current version of this PR initializes the runtime.

I suppose machine creation would still need extra code to copy the file + set the flag, or maybe we would leave that for users to do manually.