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// Copyright (C) 2021 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package filesystem
import (
"fmt"
"strconv"
"github.com/google/blueprint"
"github.com/google/blueprint/proptools"
"android/soong/android"
)
func init() {
android.RegisterModuleType("vbmeta", vbmetaFactory)
}
type vbmeta struct {
android.ModuleBase
properties vbmetaProperties
output android.OutputPath
installDir android.InstallPath
}
type vbmetaProperties struct {
// Name of the partition stored in vbmeta desc. Defaults to the name of this module.
Partition_name *string
// Set the name of the output. Defaults to <module_name>.img.
Stem *string
// Path to the private key that avbtool will use to sign this vbmeta image.
Private_key *string `android:"path"`
// Algorithm that avbtool will use to sign this vbmeta image. Default is SHA256_RSA4096.
Algorithm *string
// File whose content will provide the rollback index. If unspecified, the rollback index
// is from PLATFORM_SECURITY_PATCH
Rollback_index_file *string `android:"path"`
// Rollback index location of this vbmeta image. Must be 0, 1, 2, etc. Default is 0.
Rollback_index_location *int64
// List of filesystem modules that this vbmeta has descriptors for. The filesystem modules
// have to be signed (use_avb: true).
Partitions []string
// List of chained partitions that this vbmeta deletages the verification.
Chained_partitions []chainedPartitionProperties
}
type chainedPartitionProperties struct {
// Name of the chained partition
Name *string
// Rollback index location of the chained partition. Must be 0, 1, 2, etc. Default is the
// index of this partition in the list + 1.
Rollback_index_location *int64
// Path to the public key that the chained partition is signed with. If this is specified,
// private_key is ignored.
Public_key *string `android:"path"`
// Path to the private key that the chained partition is signed with. If this is specified,
// and public_key is not specified, a public key is extracted from this private key and
// the extracted public key is embedded in the vbmeta image.
Private_key *string `android:"path"`
}
// vbmeta is the partition image that has the verification information for other partitions.
func vbmetaFactory() android.Module {
module := &vbmeta{}
module.AddProperties(&module.properties)
android.InitAndroidArchModule(module, android.DeviceSupported, android.MultilibFirst)
return module
}
type vbmetaDep struct {
blueprint.BaseDependencyTag
kind string
}
var vbmetaPartitionDep = vbmetaDep{kind: "partition"}
func (v *vbmeta) DepsMutator(ctx android.BottomUpMutatorContext) {
ctx.AddDependency(ctx.Module(), vbmetaPartitionDep, v.properties.Partitions...)
}
func (v *vbmeta) installFileName() string {
return proptools.StringDefault(v.properties.Stem, v.BaseModuleName()+".img")
}
func (v *vbmeta) partitionName() string {
return proptools.StringDefault(v.properties.Partition_name, v.BaseModuleName())
}
// See external/avb/libavb/avb_slot_verify.c#VBMETA_MAX_SIZE
const vbmetaMaxSize = 64 * 1024
func (v *vbmeta) GenerateAndroidBuildActions(ctx android.ModuleContext) {
extractedPublicKeys := v.extractPublicKeys(ctx)
v.output = android.PathForModuleOut(ctx, v.installFileName()).OutputPath
builder := android.NewRuleBuilder(pctx, ctx)
cmd := builder.Command().BuiltTool("avbtool").Text("make_vbmeta_image")
key := android.PathForModuleSrc(ctx, proptools.String(v.properties.Private_key))
cmd.FlagWithInput("--key ", key)
algorithm := proptools.StringDefault(v.properties.Algorithm, "SHA256_RSA4096")
cmd.FlagWithArg("--algorithm ", algorithm)
cmd.FlagWithArg("--rollback_index ", v.rollbackIndexCommand(ctx))
ril := proptools.IntDefault(v.properties.Rollback_index_location, 0)
if ril < 0 {
ctx.PropertyErrorf("rollback_index_location", "must be 0, 1, 2, ...")
return
}
cmd.FlagWithArg("--rollback_index_location ", strconv.Itoa(ril))
for _, p := range ctx.GetDirectDepsWithTag(vbmetaPartitionDep) {
f, ok := p.(Filesystem)
if !ok {
ctx.PropertyErrorf("partitions", "%q(type: %s) is not supported",
p.Name(), ctx.OtherModuleType(p))
continue
}
signedImage := f.SignedOutputPath()
if signedImage == nil {
ctx.PropertyErrorf("partitions", "%q(type: %s) is not signed. Use `use_avb: true`",
p.Name(), ctx.OtherModuleType(p))
continue
}
cmd.FlagWithInput("--include_descriptors_from_image ", signedImage)
}
for i, cp := range v.properties.Chained_partitions {
name := proptools.String(cp.Name)
if name == "" {
ctx.PropertyErrorf("chained_partitions", "name must be specified")
continue
}
ril := proptools.IntDefault(cp.Rollback_index_location, i+1)
if ril < 0 {
ctx.PropertyErrorf("chained_partitions", "must be 0, 1, 2, ...")
continue
}
var publicKey android.Path
if cp.Public_key != nil {
publicKey = android.PathForModuleSrc(ctx, proptools.String(cp.Public_key))
} else {
publicKey = extractedPublicKeys[name]
}
cmd.FlagWithArg("--chain_partition ", fmt.Sprintf("%s:%d:%s", name, ril, publicKey.String()))
cmd.Implicit(publicKey)
}
cmd.FlagWithOutput("--output ", v.output)
// libavb expects to be able to read the maximum vbmeta size, so we must provide a partition
// which matches this or the read will fail.
builder.Command().Text("truncate").
FlagWithArg("-s ", strconv.Itoa(vbmetaMaxSize)).
Output(v.output)
builder.Build("vbmeta", fmt.Sprintf("vbmeta %s", ctx.ModuleName()))
v.installDir = android.PathForModuleInstall(ctx, "etc")
ctx.InstallFile(v.installDir, v.installFileName(), v.output)
}
// Returns the embedded shell command that prints the rollback index
func (v *vbmeta) rollbackIndexCommand(ctx android.ModuleContext) string {
var cmd string
if v.properties.Rollback_index_file != nil {
f := android.PathForModuleSrc(ctx, proptools.String(v.properties.Rollback_index_file))
cmd = "cat " + f.String()
} else {
cmd = "date -d 'TZ=\"GMT\" " + ctx.Config().PlatformSecurityPatch() + "' +%s"
}
// Take the first line and remove the newline char
return "$(" + cmd + " | head -1 | tr -d '\n'" + ")"
}
// Extract public keys from chained_partitions.private_key. The keys are indexed with the partition
// name.
func (v *vbmeta) extractPublicKeys(ctx android.ModuleContext) map[string]android.OutputPath {
result := make(map[string]android.OutputPath)
builder := android.NewRuleBuilder(pctx, ctx)
for _, cp := range v.properties.Chained_partitions {
if cp.Private_key == nil {
continue
}
name := proptools.String(cp.Name)
if name == "" {
ctx.PropertyErrorf("chained_partitions", "name must be specified")
continue
}
if _, ok := result[name]; ok {
ctx.PropertyErrorf("chained_partitions", "name %q is duplicated", name)
continue
}
privateKeyFile := android.PathForModuleSrc(ctx, proptools.String(cp.Private_key))
publicKeyFile := android.PathForModuleOut(ctx, name+".avbpubkey").OutputPath
builder.Command().
BuiltTool("avbtool").
Text("extract_public_key").
FlagWithInput("--key ", privateKeyFile).
FlagWithOutput("--output ", publicKeyFile)
result[name] = publicKeyFile
}
builder.Build("vbmeta_extract_public_key", fmt.Sprintf("Extract public keys for %s", ctx.ModuleName()))
return result
}
var _ android.AndroidMkEntriesProvider = (*vbmeta)(nil)
// Implements android.AndroidMkEntriesProvider
func (v *vbmeta) AndroidMkEntries() []android.AndroidMkEntries {
return []android.AndroidMkEntries{android.AndroidMkEntries{
Class: "ETC",
OutputFile: android.OptionalPathForPath(v.output),
ExtraEntries: []android.AndroidMkExtraEntriesFunc{
func(ctx android.AndroidMkExtraEntriesContext, entries *android.AndroidMkEntries) {
entries.SetString("LOCAL_MODULE_PATH", v.installDir.String())
entries.SetString("LOCAL_INSTALLED_MODULE_STEM", v.installFileName())
},
},
}}
}
var _ Filesystem = (*vbmeta)(nil)
func (v *vbmeta) OutputPath() android.Path {
return v.output
}
func (v *vbmeta) SignedOutputPath() android.Path {
return v.OutputPath() // vbmeta is always signed
}
var _ android.OutputFileProducer = (*vbmeta)(nil)
// Implements android.OutputFileProducer
func (v *vbmeta) OutputFiles(tag string) (android.Paths, error) {
if tag == "" {
return []android.Path{v.output}, nil
}
return nil, fmt.Errorf("unsupported module reference tag %q", tag)
}