Build vbmeta partitions with soong
AVB is Android Verified Boot:
https://source.android.com/docs/security/features/verifiedboot
It works by signing all the partitions, but then also including an extra
metadata paritition called vbmeta that depends on all the other
signed partitions. This creates a requirement that you update all those
partitions and the vbmeta partition together, so in order to relax that
requirement products can set up "chained" vbmeta partitions, where a
chained partition like vbmeta_system might contain the avb metadata for
just a few products. In cuttlefish vbmeta_system contains metadata about
product, system, and system_ext. Using chained partitions, that group of
partitions can be updated independently from the other signed
partitions.
Bug: 377563298
Test: m nothing (the diff test currently fails, but this is a start)
Change-Id: I397af3a418bd23bcbf8f620c436afcacf69974fd
diff --git a/fsgen/Android.bp b/fsgen/Android.bp
index 690ad28..8cd7518 100644
--- a/fsgen/Android.bp
+++ b/fsgen/Android.bp
@@ -16,6 +16,7 @@
"filesystem_creator.go",
"fsgen_mutators.go",
"prebuilt_etc_modules_gen.go",
+ "vbmeta_partitions.go",
],
testSrcs: [
"filesystem_creator_test.go",
diff --git a/fsgen/filesystem_creator.go b/fsgen/filesystem_creator.go
index bdffabf..b580ea9 100644
--- a/fsgen/filesystem_creator.go
+++ b/fsgen/filesystem_creator.go
@@ -44,6 +44,9 @@
type filesystemCreatorProps struct {
Generated_partition_types []string `blueprint:"mutated"`
Unsupported_partition_types []string `blueprint:"mutated"`
+
+ Vbmeta_module_names []string `blueprint:"mutated"`
+ Vbmeta_partition_names []string `blueprint:"mutated"`
}
type filesystemCreator struct {
@@ -67,16 +70,24 @@
}
func (f *filesystemCreator) createInternalModules(ctx android.LoadHookContext) {
- soongGeneratedPartitions := &ctx.Config().Get(fsGenStateOnceKey).(*FsGenState).soongGeneratedPartitions
- for _, partitionType := range *soongGeneratedPartitions {
+ soongGeneratedPartitions := generatedPartitions(ctx)
+ finalSoongGeneratedPartitions := make([]string, 0, len(soongGeneratedPartitions))
+ for _, partitionType := range soongGeneratedPartitions {
if f.createPartition(ctx, partitionType) {
f.properties.Generated_partition_types = append(f.properties.Generated_partition_types, partitionType)
+ finalSoongGeneratedPartitions = append(finalSoongGeneratedPartitions, partitionType)
} else {
f.properties.Unsupported_partition_types = append(f.properties.Unsupported_partition_types, partitionType)
- _, *soongGeneratedPartitions = android.RemoveFromList(partitionType, *soongGeneratedPartitions)
}
}
- f.createDeviceModule(ctx)
+
+ for _, x := range createVbmetaPartitions(ctx, finalSoongGeneratedPartitions) {
+ f.properties.Vbmeta_module_names = append(f.properties.Vbmeta_module_names, x.moduleName)
+ f.properties.Vbmeta_partition_names = append(f.properties.Vbmeta_partition_names, x.partitionName)
+ }
+
+ ctx.Config().Get(fsGenStateOnceKey).(*FsGenState).soongGeneratedPartitions = finalSoongGeneratedPartitions
+ f.createDeviceModule(ctx, finalSoongGeneratedPartitions, f.properties.Vbmeta_module_names)
}
func generatedModuleName(cfg android.Config, suffix string) string {
@@ -91,7 +102,11 @@
return generatedModuleName(cfg, fmt.Sprintf("%s_image", partitionType))
}
-func (f *filesystemCreator) createDeviceModule(ctx android.LoadHookContext) {
+func (f *filesystemCreator) createDeviceModule(
+ ctx android.LoadHookContext,
+ generatedPartitionTypes []string,
+ vbmetaPartitions []string,
+) {
baseProps := &struct {
Name *string
}{
@@ -100,21 +115,22 @@
// Currently, only the system and system_ext partition module is created.
partitionProps := &filesystem.PartitionNameProperties{}
- if android.InList("system", f.properties.Generated_partition_types) {
+ if android.InList("system", generatedPartitionTypes) {
partitionProps.System_partition_name = proptools.StringPtr(generatedModuleNameForPartition(ctx.Config(), "system"))
}
- if android.InList("system_ext", f.properties.Generated_partition_types) {
+ if android.InList("system_ext", generatedPartitionTypes) {
partitionProps.System_ext_partition_name = proptools.StringPtr(generatedModuleNameForPartition(ctx.Config(), "system_ext"))
}
- if android.InList("vendor", f.properties.Generated_partition_types) {
+ if android.InList("vendor", generatedPartitionTypes) {
partitionProps.Vendor_partition_name = proptools.StringPtr(generatedModuleNameForPartition(ctx.Config(), "vendor"))
}
- if android.InList("product", f.properties.Generated_partition_types) {
+ if android.InList("product", generatedPartitionTypes) {
partitionProps.Product_partition_name = proptools.StringPtr(generatedModuleNameForPartition(ctx.Config(), "product"))
}
- if android.InList("odm", f.properties.Generated_partition_types) {
+ if android.InList("odm", generatedPartitionTypes) {
partitionProps.Odm_partition_name = proptools.StringPtr(generatedModuleNameForPartition(ctx.Config(), "odm"))
}
+ partitionProps.Vbmeta_partitions = vbmetaPartitions
ctx.CreateModule(filesystem.AndroidDeviceFactory, baseProps, partitionProps)
}
@@ -334,12 +350,15 @@
type filesystemBaseProperty struct {
Name *string
Compile_multilib *string
+ Visibility []string
}
func generateBaseProps(namePtr *string) *filesystemBaseProperty {
return &filesystemBaseProperty{
Name: namePtr,
Compile_multilib: proptools.StringPtr("both"),
+ // The vbmeta modules are currently in the root directory and depend on the partitions
+ Visibility: []string{"//.", "//build/soong:__subpackages__"},
}
}
@@ -435,16 +454,42 @@
return file
}
+func createVbmetaDiff(ctx android.ModuleContext, vbmetaModuleName string, vbmetaPartitionName string) android.Path {
+ vbmetaModule := ctx.GetDirectDepWithTag(vbmetaModuleName, generatedVbmetaPartitionDepTag)
+ outputFilesProvider, ok := android.OtherModuleProvider(ctx, vbmetaModule, android.OutputFilesProvider)
+ if !ok {
+ ctx.ModuleErrorf("Expected module %s to provide OutputFiles", vbmetaModule)
+ }
+ if len(outputFilesProvider.DefaultOutputFiles) != 1 {
+ ctx.ModuleErrorf("Expected 1 output file from module %s", vbmetaModule)
+ }
+ soongVbMetaFile := outputFilesProvider.DefaultOutputFiles[0]
+ makeVbmetaFile := android.PathForArbitraryOutput(ctx, fmt.Sprintf("target/product/%s/%s.img", ctx.Config().DeviceName(), vbmetaPartitionName))
+
+ diffTestResultFile := android.PathForModuleOut(ctx, fmt.Sprintf("diff_test_%s.txt", vbmetaModuleName))
+ builder := android.NewRuleBuilder(pctx, ctx)
+ builder.Command().Text("diff").
+ Input(soongVbMetaFile).
+ Input(makeVbmetaFile)
+ builder.Command().Text("touch").Output(diffTestResultFile)
+ builder.Build(vbmetaModuleName+" diff test", vbmetaModuleName+" diff test")
+ return diffTestResultFile
+}
+
type systemImageDepTagType struct {
blueprint.BaseDependencyTag
}
var generatedFilesystemDepTag systemImageDepTagType
+var generatedVbmetaPartitionDepTag systemImageDepTagType
func (f *filesystemCreator) DepsMutator(ctx android.BottomUpMutatorContext) {
for _, partitionType := range f.properties.Generated_partition_types {
ctx.AddDependency(ctx.Module(), generatedFilesystemDepTag, generatedModuleNameForPartition(ctx.Config(), partitionType))
}
+ for _, vbmetaModule := range f.properties.Vbmeta_module_names {
+ ctx.AddDependency(ctx.Module(), generatedVbmetaPartitionDepTag, vbmetaModule)
+ }
}
func (f *filesystemCreator) GenerateAndroidBuildActions(ctx android.ModuleContext) {
@@ -474,6 +519,11 @@
diffTestFiles = append(diffTestFiles, diffTestFile)
ctx.Phony(fmt.Sprintf("soong_generated_%s_filesystem_test", partitionType), diffTestFile)
}
+ for i, vbmetaModule := range f.properties.Vbmeta_module_names {
+ diffTestFile := createVbmetaDiff(ctx, vbmetaModule, f.properties.Vbmeta_partition_names[i])
+ diffTestFiles = append(diffTestFiles, diffTestFile)
+ ctx.Phony(fmt.Sprintf("soong_generated_%s_filesystem_test", f.properties.Vbmeta_partition_names[i]), diffTestFile)
+ }
ctx.Phony("soong_generated_filesystem_tests", diffTestFiles...)
}
diff --git a/fsgen/fsgen_mutators.go b/fsgen/fsgen_mutators.go
index f3aec00..92ea128 100644
--- a/fsgen/fsgen_mutators.go
+++ b/fsgen/fsgen_mutators.go
@@ -145,7 +145,6 @@
},
"system_dlkm": {},
},
- soongGeneratedPartitions: generatedPartitions(ctx),
fsDepsMutex: sync.Mutex{},
moduleToInstallationProps: map[string]installationProperties{},
}
diff --git a/fsgen/vbmeta_partitions.go b/fsgen/vbmeta_partitions.go
new file mode 100644
index 0000000..f5b5f1c
--- /dev/null
+++ b/fsgen/vbmeta_partitions.go
@@ -0,0 +1,174 @@
+// Copyright (C) 2024 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 fsgen
+
+import (
+ "android/soong/android"
+ "android/soong/filesystem"
+ "slices"
+ "strconv"
+
+ "github.com/google/blueprint/proptools"
+)
+
+type vbmetaModuleInfo struct {
+ // The name of the generated vbmeta module
+ moduleName string
+ // The name of the module that avb understands. This is the name passed to --chain_partition,
+ // and also the basename of the output file. (the output file is called partitionName + ".img")
+ partitionName string
+}
+
+// Creates the vbmeta partition and the chained vbmeta partitions. Returns the list of module names
+// that the function created. May return nil if the product isn't using avb.
+//
+// AVB is Android Verified Boot: https://source.android.com/docs/security/features/verifiedboot
+// It works by signing all the partitions, but then also including an extra metadata paritition
+// called vbmeta that depends on all the other signed partitions. This creates a requirement
+// that you update all those partitions and the vbmeta partition together, so in order to relax
+// that requirement products can set up "chained" vbmeta partitions, where a chained partition
+// like vbmeta_system might contain the avb metadata for just a few products. In cuttlefish
+// vbmeta_system contains metadata about product, system, and system_ext. Using chained partitions,
+// that group of partitions can be updated independently from the other signed partitions.
+func createVbmetaPartitions(ctx android.LoadHookContext, generatedPartitionTypes []string) []vbmetaModuleInfo {
+ partitionVars := ctx.Config().ProductVariables().PartitionVarsForSoongMigrationOnlyDoNotUse
+ // Some products seem to have BuildingVbmetaImage as true even when BoardAvbEnable is false
+ if !partitionVars.BuildingVbmetaImage || !partitionVars.BoardAvbEnable {
+ return nil
+ }
+
+ var result []vbmetaModuleInfo
+
+ var chainedPartitions []filesystem.ChainedPartitionProperties
+ var partitionTypesHandledByChainedPartitions []string
+ for chainedName, props := range partitionVars.ChainedVbmetaPartitions {
+ chainedName = "vbmeta_" + chainedName
+ if len(props.Partitions) == 0 {
+ continue
+ }
+ if len(props.Key) == 0 {
+ ctx.ModuleErrorf("No key found for chained avb partition %s", chainedName)
+ continue
+ }
+ if len(props.Algorithm) == 0 {
+ ctx.ModuleErrorf("No algorithm found for chained avb partition %s", chainedName)
+ continue
+ }
+ if len(props.RollbackIndex) == 0 {
+ ctx.ModuleErrorf("No rollback index found for chained avb partition %s", chainedName)
+ continue
+ }
+ ril, err := strconv.ParseInt(props.RollbackIndexLocation, 10, 32)
+ if err != nil {
+ ctx.ModuleErrorf("Rollback index location must be an int, got %s", props.RollbackIndexLocation)
+ continue
+ }
+ // The default is to use the PlatformSecurityPatch, and a lot of product config files
+ // just set it to the platform security patch, so detect that and don't set the property
+ // in soong.
+ var rollbackIndex *int64
+ if props.RollbackIndex != ctx.Config().PlatformSecurityPatch() {
+ i, err := strconv.ParseInt(props.RollbackIndex, 10, 32)
+ if err != nil {
+ ctx.ModuleErrorf("Rollback index must be an int, got %s", props.RollbackIndex)
+ continue
+ }
+ rollbackIndex = &i
+ }
+
+ var partitionModules []string
+ for _, partition := range props.Partitions {
+ partitionTypesHandledByChainedPartitions = append(partitionTypesHandledByChainedPartitions, partition)
+ if !slices.Contains(generatedPartitionTypes, partition) {
+ // The partition is probably unsupported.
+ continue
+ }
+ partitionModules = append(partitionModules, generatedModuleNameForPartition(ctx.Config(), partition))
+ }
+
+ name := generatedModuleName(ctx.Config(), chainedName)
+ ctx.CreateModuleInDirectory(
+ filesystem.VbmetaFactory,
+ ".", // Create in the root directory for now so its easy to get the key
+ &filesystem.VbmetaProperties{
+ Partition_name: proptools.StringPtr(chainedName),
+ Stem: proptools.StringPtr(chainedName + ".img"),
+ Private_key: proptools.StringPtr(props.Key),
+ Algorithm: &props.Algorithm,
+ Rollback_index: rollbackIndex,
+ Rollback_index_location: &ril,
+ Partitions: proptools.NewSimpleConfigurable(partitionModules),
+ }, &struct {
+ Name *string
+ }{
+ Name: &name,
+ },
+ ).HideFromMake()
+
+ chainedPartitions = append(chainedPartitions, filesystem.ChainedPartitionProperties{
+ Name: &chainedName,
+ Rollback_index_location: &ril,
+ Private_key: &props.Key,
+ })
+
+ result = append(result, vbmetaModuleInfo{
+ moduleName: name,
+ partitionName: chainedName,
+ })
+ }
+
+ vbmetaModuleName := generatedModuleName(ctx.Config(), "vbmeta")
+
+ var algorithm *string
+ if len(partitionVars.BoardAvbAlgorithm) > 0 {
+ algorithm = proptools.StringPtr(partitionVars.BoardAvbAlgorithm)
+ }
+ ril, err := strconv.ParseInt(partitionVars.BoardAvbRollbackIndex, 10, 32)
+ if err != nil {
+ ctx.ModuleErrorf("Rollback index location must be an int, got %s", partitionVars.BoardAvbRollbackIndex)
+ }
+
+ var partitionModules []string
+ for _, partitionType := range generatedPartitionTypes {
+ if slices.Contains(partitionTypesHandledByChainedPartitions, partitionType) {
+ // Already handled by a chained vbmeta partition
+ continue
+ }
+ partitionModules = append(partitionModules, generatedModuleNameForPartition(ctx.Config(), partitionType))
+ }
+
+ ctx.CreateModuleInDirectory(
+ filesystem.VbmetaFactory,
+ ".", // Create in the root directory for now so its easy to get the key
+ &filesystem.VbmetaProperties{
+ Stem: proptools.StringPtr("vbmeta.img"),
+ Algorithm: algorithm,
+ Private_key: proptools.StringPtr(partitionVars.BoardAvbKeyPath),
+ Rollback_index_location: &ril,
+ Chained_partitions: chainedPartitions,
+ Partitions: proptools.NewSimpleConfigurable(partitionModules),
+ }, &struct {
+ Name *string
+ }{
+ Name: &vbmetaModuleName,
+ },
+ ).HideFromMake()
+
+ result = append(result, vbmetaModuleInfo{
+ moduleName: vbmetaModuleName,
+ partitionName: "vbmeta",
+ })
+ return result
+}