Support multiple se_flags modules
Instead of centralized one se_flags module under system/sepolicy,
additional se_flags modules can be defined anywhere to support defining
downstream branches' own flagging.
Bug: 321875465
Test: TH
Test: soong test
Change-Id: I6e45c859b7f09e27ba1d60033b0db1424472cb63
diff --git a/build/soong/flags.go b/build/soong/flags.go
index b1aebac..c7aeb32 100644
--- a/build/soong/flags.go
+++ b/build/soong/flags.go
@@ -15,22 +15,141 @@
package selinux
import (
+ "maps"
+
"android/soong/android"
+
+ "github.com/google/blueprint"
)
+var (
+ flagsDepTag = dependencyTag{name: "flags"}
+ buildFlagsDepTag = dependencyTag{name: "build_flags"}
+)
+
+func init() {
+ ctx := android.InitRegistrationContext
+ ctx.RegisterModuleType("se_flags", flagsFactory)
+ ctx.RegisterModuleType("se_flags_collector", flagsCollectorFactory)
+}
+
type flagsProperties struct {
- // List of flags to be passed to M4 macro.
+ // List of build time flags for flag-guarding.
Flags []string
+
+ // List of se_flags_collector modules to export flags to.
+ Export_to []string
+}
+
+type flagsModule struct {
+ android.ModuleBase
+ properties flagsProperties
+}
+
+type flagsInfo struct {
+ Flags []string
+}
+
+var flagsProviderKey = blueprint.NewProvider[flagsInfo]()
+
+// se_flags contains a list of build time flags for sepolicy. Build time flags are defined under
+// .scl files (e.g. build/release/build_flags.scl). By importing flags with se_flags modules,
+// sepolicy rules can be guarded by `is_flag_enabled` / `is_flag_disabled` macro.
+//
+// For example, an Android.bp file could have:
+//
+// se_flags {
+// name: "aosp_selinux_flags",
+// flags: ["RELEASE_AVF_ENABLE_DEVICE_ASSIGNMENT"],
+// export_to: ["all_selinux_flags"],
+// }
+//
+// And then one could flag-guard .te file rules:
+//
+// is_flag_enabled(RELEASE_AVF_ENABLE_DEVICE_ASSIGNMENT, `
+// type vfio_handler, domain, coredomain;
+// binder_use(vfio_handler)
+// ')
+//
+// or contexts entries:
+//
+// is_flag_enabled(RELEASE_AVF_ENABLE_DEVICE_ASSIGNMENT, `
+// android.system.virtualizationservice_internal.IVfioHandler u:object_r:vfio_handler_service:s0
+// ')
+func flagsFactory() android.Module {
+ module := &flagsModule{}
+ module.AddProperties(&module.properties)
+ android.InitAndroidModule(module)
+ return module
+}
+
+func (f *flagsModule) DepsMutator(ctx android.BottomUpMutatorContext) {
+ // dep se_flag_collector -> se_flags
+ for _, export := range f.properties.Export_to {
+ ctx.AddReverseDependency(ctx.Module(), flagsDepTag, export)
+ }
+}
+
+func (f *flagsModule) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+ android.SetProvider(ctx, flagsProviderKey, flagsInfo{
+ Flags: f.properties.Flags,
+ })
+}
+
+type buildFlagsInfo struct {
+ BuildFlags map[string]string
+}
+
+var buildFlagsProviderKey = blueprint.NewProvider[buildFlagsInfo]()
+
+type flagsCollectorModule struct {
+ android.ModuleBase
+ buildFlags map[string]string
+}
+
+// se_flags_collector module collects flags from exported se_flags modules (see export_to property
+// of se_flags modules), and then converts them into build-time flags. It will be used to generate
+// M4 macros to flag-guard sepolicy.
+func flagsCollectorFactory() android.Module {
+ module := &flagsCollectorModule{}
+ android.InitAndroidModule(module)
+ return module
+}
+
+func (f *flagsCollectorModule) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+ var flags []string
+ ctx.VisitDirectDepsWithTag(flagsDepTag, func(m android.Module) {
+ if dep, ok := android.OtherModuleProvider(ctx, m, flagsProviderKey); ok {
+ flags = append(flags, dep.Flags...)
+ } else {
+ ctx.ModuleErrorf("unknown dependency %q", ctx.OtherModuleName(m))
+ }
+ })
+ buildFlags := make(map[string]string)
+ for _, flag := range android.SortedUniqueStrings(flags) {
+ if val, ok := ctx.Config().GetBuildFlag(flag); ok {
+ buildFlags[flag] = val
+ }
+ }
+ android.SetProvider(ctx, buildFlagsProviderKey, buildFlagsInfo{
+ BuildFlags: buildFlags,
+ })
+}
+
+type flaggableModuleProperties struct {
+ // List of se_flag_collector modules to be passed to M4 macro.
+ Build_flags []string
}
type flaggableModule interface {
android.Module
flagModuleBase() *flaggableModuleBase
+ flagDeps(ctx android.BottomUpMutatorContext)
getBuildFlags(ctx android.ModuleContext) map[string]string
}
type flaggableModuleBase struct {
- properties flagsProperties
+ properties flaggableModuleProperties
}
func initFlaggableModule(m flaggableModule) {
@@ -42,13 +161,19 @@
return f
}
+func (f *flaggableModuleBase) flagDeps(ctx android.BottomUpMutatorContext) {
+ ctx.AddDependency(ctx.Module(), buildFlagsDepTag, f.properties.Build_flags...)
+}
+
// getBuildFlags returns a map from flag names to flag values.
func (f *flaggableModuleBase) getBuildFlags(ctx android.ModuleContext) map[string]string {
ret := make(map[string]string)
- for _, flag := range android.SortedUniqueStrings(f.properties.Flags) {
- if val, ok := ctx.Config().GetBuildFlag(flag); ok {
- ret[flag] = val
+ ctx.VisitDirectDepsWithTag(buildFlagsDepTag, func(m android.Module) {
+ if dep, ok := android.OtherModuleProvider(ctx, m, buildFlagsProviderKey); ok {
+ maps.Copy(ret, dep.BuildFlags)
+ } else {
+ ctx.PropertyErrorf("build_flags", "unknown dependency %q", ctx.OtherModuleName(m))
}
- }
+ })
return ret
}