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prepare foundations for Secure Boot and image resigning #2505

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merged 12 commits into from Nov 2, 2022

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bcressey
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Issue number:

#2486, #2501

Description of changes:
The commits here divide into three rough groups, though they're all related to the larger goals of being able to resign images and to add support for Secure Boot.

First up is adding support to buildsys to track symlinks and subdirectories, and then moving the bulk of symlink creation into the build-variant task. Images and symlinks are now placed into a versioned directory, rather than all together in a single directory per variant/arch combination. The ultimate goal here is to be able to cleanly archive and later unpack the full contents of a specific build, without worrying about excluding artifacts from other builds or recreating the (surprisingly fiddly and prolific) symlinks.

There's still "latest" but it's now a symlink to the most recent versioned directory (which contains the symlinks alongside the artifacts) rather than a directory (which contains symlinks to artifacts in the parent directory). Scripts that rely on paths to symlinks, as well as tasks in Makefile.toml, should still work. However, any process that relies on moving images into the "expected" directory, such as the GovCloud AMI registration workflow, will break and will need to be updated.

The second set of changes turns the manifest parser into a crate, and makes the variant manifest the new source of truth for published image sizes. buildsys and pubsys are then updated to consume this data. This allows the build-variant task to generate OVAs directly, rather than relying on follow-up tasks in Makefile.toml, which again is in pursuit of the goal for a single task that's responsible for generating all artifacts and symlinks.

What's lost here is the ability to override AMI sizes via environment variables at the cargo make ami step, or to do the same for OVAs during the cargo make step. I didn't feel this was worth the implementation effort, or the cost of duplicate logic, since for OVAs to support this it would be necessary for both the build and resign tasks to track the environment variables and the desired image layout, just to override a property that can now be set in the variant manifest.

Next, the grub-features property in the variant manifest is upgraded to the more general image-features property to store feature flags. Some of these will be GRUB-related (grub-set-private-var, grub-signed-config) and some will pertain to the image as a whole (uefi-secure-boot). Features are also passed into package builds so that they can be used for build conditionals.

Finally there are a couple of minor fixes. The repobuild stage in the Dockerfile is streamlined and the parts of it that are specific to kmod-kit and migrations are moved into those stages to better separate concerns. aws-dev and vmware-dev receive the ability to configure boot settings, and vmware-dev moves to the newer "unified" layout. Both are done under the general theory that dev variants are a laboratory for experimenting with new features and functionality, where backwards compatibility can be cheerfully ignored.

Testing done:
Built lots of OVAs and AMIs. Verified that the images and symlinks were created correctly and that related tasks (ami, repo, upload-ova) still found the expected inputs and produced the expected results in terms of published disk sizes.

Confirmed that the boot settings feature works on aws-dev and vmware-dev.

Here's a visual aid for how the artifacts and symlinks are created, before and after this change.

Terms of contribution:

By submitting this pull request, I agree that this contribution is dual-licensed under the terms of both the Apache License, version 2.0, and the MIT license.

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@zmrow zmrow left a comment

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Whew! Nice job!

🔍

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@webern webern left a comment

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This is pretty big and I'm probably only 20% of the way through it. I wanted to save my work, sorry for what will be multiple reviews:

nits

  • This commit comment buildsys: refactor manifest parser into crate misled me a little since what you are doing is making a buildsys library crate that exposes a manifest module.
  • I wonder if "hint" is the best name for publish_image_size_hint_gib. Maybe publish_image_minimum_size_gib or publish_image_desired_size_gib.

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I need to go through and self resolve or delete some of these things as I was figuring stuff out as I went along. I think the main, potentially useful feedback is that image-features are always assumed to be boolean (might we want other value types in the future) and I think maybe you assume that the presence of the key in the toml file means true (although I might have filled a filter).

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My feedback was rather minor and I don't want to block this. Nice work.

Signed-off-by: Ben Cressey <bcressey@amazon.com>
Signed-off-by: Ben Cressey <bcressey@amazon.com>
The larger goal of this change is to make it easier to archive the
contents of a specific build, to allow it to be saved and restored at
a later point in time or on a different machine.

Now that `buildsys` can track and clean up symlinks from builds, move
all symlink generation into the image build process.

Since `buildsys` can also keep track of artifacts in subdirectories,
switch to versioned directories to store the output of image builds.

Previously, "latest" was a directory containing friendly symlinks to
the most recent set of images. Now it is a symlink to the most recent
versioned directory, and the friendly symlinks are created during the
image build.

Signed-off-by: Ben Cressey <bcressey@amazon.com>
This allows metadata about the variant to be parsed by other tools in
a consistent way. In particular, `pubsys` will need access to fields
related to published image sizes and whether the Secure Boot feature
is enabled.

Signed-off-by: Ben Cressey <bcressey@amazon.com>
Allow manifests to specify a hint for the published image sizes, for
the common case where additional storage space is desired on the data
volume.

A helper function is provided to calculate the sizes for the OS and
data volumes, based on the image layout and the publish size hint.

Signed-off-by: Ben Cressey <bcressey@amazon.com>
The larger goal of this change is to make image builds more hermetic,
rather than relying on additional scripts to run afterwards to create
files and symlinks. That allows the artifacts in the directory to be
archived and extracted elsewhere more easily.

The main historical blocker for generating OVAs along with VMDKs was
that the published image sizes were specified through environment
variables rather than in the variant manifest. Now that the manifest
provides these values, they can be passed through to image builds.

The bulk of this change consists of moving the OVA logic around, and
dropping the unnecessary size checks.

As part of this change, some OVF template fields are also renamed to
standardize on the "os volume" designation for the primary full disk
image. Previously this was called the "root volume" in places, which
can lead to ambiguity because there is also a "root image" used for
in-place updates.

Signed-off-by: Ben Cressey <bcressey@amazon.com>
Switch pubsys over to use the variant manifest to determine published
AMI volume sizes, rather than relying on environment variables.

This aligns AMIs and OVAs around the variant manifest as the source
of truth for properties related to publication, which is a necessary
step for Secure Boot support.

As part of this migration, some fields and variables are renamed to
standardize on the "os volume" designation for the primary full disk
image. Previously this was called the "root volume" in places, which
can lead to ambiguity because there is also a "root image" used for
in-place updates.

Signed-off-by: Ben Cressey <bcressey@amazon.com>
Signed-off-by: Ben Cressey <bcressey@amazon.com>
Signed-off-by: Ben Cressey <bcressey@amazon.com>
Presently there is only one image feature flag, indicating whether
GRUB has the `search` module built-in along with a config file that
sets the "private" variable.

For Secure Boot, we will end up with additional image-level feature
flags. One will be for GRUB, to indicate whether to enforce a signed
config file, and the other will be to enable UEFI Secure Boot.

Since not all of these flags will necessarily be tied to GRUB, take
this opportunity to migrate to a generic "image features" structure
to track the flags before any more are added.

Signed-off-by: Ben Cressey <bcressey@amazon.com>
This allows package builds to depend on image feature flags, which
are set as build conditionals in the spec file.

Signed-off-by: Ben Cressey <bcressey@amazon.com>
Move the steps to handle migrations and the kernel archive out of the
shared repobuild stage and into the respective stages. This lets the
stage be reused by other targets without waiting for the additional
inputs to be available.

Signed-off-by: Ben Cressey <bcressey@amazon.com>
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bcressey commented Nov 2, 2022

First force push applies the suggested fixes from @webern and @jpculp - thanks!

Second force push squashes in the "fixup" commit that I missed.

@bcressey bcressey merged commit 27e0902 into bottlerocket-os:develop Nov 2, 2022
@bcressey bcressey deleted the secureboot-foundations branch November 2, 2022 21:20
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5 participants