build/images/vbmeta.gni

# Copyright 2019 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

# Build arguments used in the context of verified boot.
# See [this document](https://android.googlesource.com/platform/external/avb/+/HEAD/README.md)
# for more information.

import("//build/compiled_action.gni")

declare_args() {
  # If true, then a vbmeta image will be generated for provided ZBI
  # and the paving script will pave vbmeta images to the target device.
  use_vbmeta = false

  # a key which will be used to sign VBMETA and images for AVB
  avb_key = ""

  # AVB metadata which will be used to validate public key
  avb_atx_metadata = ""

  # Partition name from where image will be verified
  zvb_partition_name = "zircon"

  # Additional VBMeta Descriptors to add to the vbmeta image during assembly.
  #
  # To add a descriptor, include GN code such as:
  #
  # ```
  # extra_vbmeta_descriptors = [{
  #   name = "zircon"         # name of the partition
  #   size = 12345            # size of the partition in bytes
  #   flags = 1               # custom vbmeta flags to add
  #   min_avb_version = "1.1" # minimum avb version
  # }]
  # ```
  extra_vbmeta_descriptors = false

  # DEPRECATED:  Remove when no boards set a value for these.
  board_extra_vbmeta_images = []
  avb_algorithm = "DEPRECATED"
}

# DEPRECATED: Remove when no boards set a value for this.
not_needed([
             "board_extra_vbmeta_images",
             "avb_algorithm",
           ])

# Creates a VBMeta image from a given ZBI.
#
# The image is created next to provided ZBI at "${zbi_path}.vbmeta".
#
# Parameters
#
#   * zbi
#     - Required: Label of the associated ZBI target. Must be defined within
#       the same file as the vbmeta() target.
#     - Type: label
#
#   * testonly, visibility
#     - Optional: The usual GN meanings.
#
template("vbmeta") {
  assert(defined(invoker.zbi), "`zbi` must be defined")

  zbi_outputs = get_target_outputs(invoker.zbi)
  zbi_path = zbi_outputs[0]
  output_vbmeta = zbi_path + ".vbmeta"

  compiled_action(target_name) {
    forward_variables_from(invoker,
                           [
                             "testonly",
                             "visibility",
                           ])

    tool = "//src/lib/assembly/vbmeta:bin"
    tool_output_name = "vbmeta"

    sources = [
      avb_atx_metadata,
      avb_key,
      zbi_path,
    ]
    outputs = [ output_vbmeta ]

    args = [
      "--zbi",
      rebase_path(zbi_path, root_build_dir),
      "--private-key-pem",
      rebase_path(avb_key, root_build_dir),
      "--public-key-metadata",
      rebase_path(avb_atx_metadata, root_build_dir),
      "--output",
      rebase_path(output_vbmeta, root_build_dir),
    ]
    deps = [ invoker.zbi ]

    metadata = {
      images = [
        {
          label = get_label_info(":$target_name", "label_with_toolchain")
          name = target_name
          path = rebase_path(output_vbmeta, root_build_dir)
          type = "vbmeta"
          cpu = current_cpu
          if (defined(testonly) && testonly) {
            testonly = true
          }
          forward_variables_from(invoker, [ "tags" ])
        },
      ]
    }
  }
}