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* Copyright (C) 2018 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include "art_field.h"
#include "art_method.h"
#include "base/hiddenapi_flags.h"
#include "base/locks.h"
#include "intrinsics_enum.h"
#include "mirror/class-inl.h"
#include "reflection.h"
#include "runtime.h"
namespace art {
namespace hiddenapi {
// Hidden API enforcement policy
// This must be kept in sync with ApplicationInfo.ApiEnforcementPolicy in
// frameworks/base/core/java/android/content/pm/
enum class EnforcementPolicy {
kDisabled = 0,
kJustWarn = 1, // keep checks enabled, but allow everything (enables logging)
kEnabled = 2, // ban dark grey & blacklist
kMax = kEnabled,
inline EnforcementPolicy EnforcementPolicyFromInt(int api_policy_int) {
DCHECK_GE(api_policy_int, 0);
DCHECK_LE(api_policy_int, static_cast<int>(EnforcementPolicy::kMax));
return static_cast<EnforcementPolicy>(api_policy_int);
// Hidden API access method
// Thist must be kept in sync with VMRuntime.HiddenApiUsageLogger.ACCESS_METHOD_*
enum class AccessMethod {
kNone = 0, // internal test that does not correspond to an actual access by app
kReflection = 1,
kJNI = 2,
kLinking = 3,
// Represents the API domain of a caller/callee.
class AccessContext {
// Initialize to either the fully-trusted or fully-untrusted domain.
explicit AccessContext(bool is_trusted)
: klass_(nullptr),
domain_(ComputeDomain(is_trusted)) {}
// Initialize from class loader and dex file (via dex cache).
AccessContext(ObjPtr<mirror::ClassLoader> class_loader, ObjPtr<mirror::DexCache> dex_cache)
: klass_(nullptr),
domain_(ComputeDomain(class_loader, dex_file_)) {}
// Initialize from class loader and dex file (only used by tests).
AccessContext(ObjPtr<mirror::ClassLoader> class_loader, const DexFile* dex_file)
: klass_(nullptr),
domain_(ComputeDomain(class_loader, dex_file_)) {}
// Initialize from Class.
explicit AccessContext(ObjPtr<mirror::Class> klass)
: klass_(klass),
domain_(ComputeDomain(klass, dex_file_)) {}
ObjPtr<mirror::Class> GetClass() const { return klass_; }
const DexFile* GetDexFile() const { return dex_file_; }
Domain GetDomain() const { return domain_; }
bool IsApplicationDomain() const { return domain_ == Domain::kApplication; }
// Returns true if this domain is always allowed to access the domain of `callee`.
bool CanAlwaysAccess(const AccessContext& callee) const {
return IsDomainMoreTrustedThan(domain_, callee.domain_);
static const DexFile* GetDexFileFromDexCache(ObjPtr<mirror::DexCache> dex_cache)
REQUIRES_SHARED(Locks::mutator_lock_) {
return dex_cache.IsNull() ? nullptr : dex_cache->GetDexFile();
static Domain ComputeDomain(bool is_trusted) {
return is_trusted ? Domain::kCorePlatform : Domain::kApplication;
static Domain ComputeDomain(ObjPtr<mirror::ClassLoader> class_loader, const DexFile* dex_file) {
if (dex_file == nullptr) {
return ComputeDomain(/* is_trusted= */ class_loader.IsNull());
return dex_file->GetHiddenapiDomain();
static Domain ComputeDomain(ObjPtr<mirror::Class> klass, const DexFile* dex_file)
REQUIRES_SHARED(Locks::mutator_lock_) {
// Check other aspects of the context.
Domain domain = ComputeDomain(klass->GetClassLoader(), dex_file);
if (domain == Domain::kApplication &&
klass->ShouldSkipHiddenApiChecks() &&
Runtime::Current()->IsJavaDebuggable()) {
// Class is known, it is marked trusted and we are in debuggable mode.
domain = ComputeDomain(/* is_trusted= */ true);
return domain;
// Pointer to declaring class of the caller/callee (null if not provided).
// This is not safe across GC but we're only using this class for passing
// information about the caller to the access check logic and never retain
// the AccessContext instance beyond that.
const ObjPtr<mirror::Class> klass_;
// DexFile of the caller/callee (null if not provided).
const DexFile* const dex_file_;
// Computed domain of the caller/callee.
const Domain domain_;
class ScopedHiddenApiEnforcementPolicySetting {
explicit ScopedHiddenApiEnforcementPolicySetting(EnforcementPolicy new_policy)
: initial_policy_(Runtime::Current()->GetHiddenApiEnforcementPolicy()) {
~ScopedHiddenApiEnforcementPolicySetting() {
const EnforcementPolicy initial_policy_;
// Implementation details. DO NOT ACCESS DIRECTLY.
namespace detail {
// Class to encapsulate the signature of a member (ArtField or ArtMethod). This
// is used as a helper when matching prefixes, and when logging the signature.
class MemberSignature {
enum MemberType {
std::string class_name_;
std::string member_name_;
std::string type_signature_;
std::string tmp_;
MemberType type_;
inline std::vector<const char*> GetSignatureParts() const;
explicit MemberSignature(ArtField* field) REQUIRES_SHARED(Locks::mutator_lock_);
explicit MemberSignature(ArtMethod* method) REQUIRES_SHARED(Locks::mutator_lock_);
explicit MemberSignature(const ClassAccessor::Field& field);
explicit MemberSignature(const ClassAccessor::Method& method);
void Dump(std::ostream& os) const;
bool Equals(const MemberSignature& other);
bool MemberNameAndTypeMatch(const MemberSignature& other);
// Performs prefix match on this member. Since the full member signature is
// composed of several parts, we match each part in turn (rather than
// building the entire thing in memory and performing a simple prefix match)
bool DoesPrefixMatch(const std::string& prefix) const;
bool IsExempted(const std::vector<std::string>& exemptions);
void WarnAboutAccess(AccessMethod access_method, ApiList list);
void LogAccessToEventLog(uint32_t sampled_value, AccessMethod access_method, bool access_denied);
// Calls back into managed code to notify VMRuntime.nonSdkApiUsageConsumer that
// |member| was accessed. This is usually called when an API is on the black,
// dark grey or light grey lists. Given that the callback can execute arbitrary
// code, a call to this method can result in thread suspension.
void NotifyHiddenApiListener(AccessMethod access_method);
// Locates hiddenapi flags for `field` in the corresponding dex file.
// NB: This is an O(N) operation, linear with the number of members in the class def.
template<typename T>
uint32_t GetDexFlags(T* member) REQUIRES_SHARED(Locks::mutator_lock_);
// Handler of detected core platform API violations. Returns true if access to
// `member` should be denied.
template<typename T>
bool HandleCorePlatformApiViolation(T* member,
const AccessContext& caller_context,
AccessMethod access_method,
EnforcementPolicy policy)
template<typename T>
bool ShouldDenyAccessToMemberImpl(T* member, ApiList api_list, AccessMethod access_method)
inline ArtField* GetInterfaceMemberIfProxy(ArtField* field) { return field; }
inline ArtMethod* GetInterfaceMemberIfProxy(ArtMethod* method)
REQUIRES_SHARED(Locks::mutator_lock_) {
return method->GetInterfaceMethodIfProxy(kRuntimePointerSize);
} // namespace detail
// Returns access flags for the runtime representation of a class member (ArtField/ArtMember).
ALWAYS_INLINE inline uint32_t CreateRuntimeFlags(const ClassAccessor::BaseItem& member) {
uint32_t runtime_flags = 0u;
ApiList api_list(member.GetHiddenapiFlags());
if (api_list.Contains(ApiList::Whitelist())) {
runtime_flags |= kAccPublicApi;
} else {
// Only add domain-specific flags for non-public API members.
// This simplifies hardcoded values for intrinsics.
if (api_list.Contains(ApiList::CorePlatformApi())) {
runtime_flags |= kAccCorePlatformApi;
DCHECK_EQ(runtime_flags & kAccHiddenapiBits, runtime_flags)
<< "Runtime flags not in reserved access flags bits";
return runtime_flags;
// Extracts hiddenapi runtime flags from access flags of ArtField.
ALWAYS_INLINE inline uint32_t GetRuntimeFlags(ArtField* field)
REQUIRES_SHARED(Locks::mutator_lock_) {
return field->GetAccessFlags() & kAccHiddenapiBits;
// Extracts hiddenapi runtime flags from access flags of ArtMethod.
// Uses hardcoded values for intrinsics.
ALWAYS_INLINE inline uint32_t GetRuntimeFlags(ArtMethod* method)
REQUIRES_SHARED(Locks::mutator_lock_) {
if (UNLIKELY(method->IsIntrinsic())) {
switch (static_cast<Intrinsics>(method->GetIntrinsic())) {
case Intrinsics::kSystemArrayCopyChar:
case Intrinsics::kStringGetCharsNoCheck:
case Intrinsics::kReferenceGetReferent:
case Intrinsics::kMemoryPeekByte:
case Intrinsics::kMemoryPokeByte:
case Intrinsics::kUnsafeCASInt:
case Intrinsics::kUnsafeCASLong:
case Intrinsics::kUnsafeCASObject:
case Intrinsics::kUnsafeGet:
case Intrinsics::kUnsafeGetAndAddInt:
case Intrinsics::kUnsafeGetAndAddLong:
case Intrinsics::kUnsafeGetAndSetInt:
case Intrinsics::kUnsafeGetAndSetLong:
case Intrinsics::kUnsafeGetAndSetObject:
case Intrinsics::kUnsafeGetLong:
case Intrinsics::kUnsafeGetLongVolatile:
case Intrinsics::kUnsafeGetObject:
case Intrinsics::kUnsafeGetObjectVolatile:
case Intrinsics::kUnsafeGetVolatile:
case Intrinsics::kUnsafePut:
case Intrinsics::kUnsafePutLong:
case Intrinsics::kUnsafePutLongOrdered:
case Intrinsics::kUnsafePutLongVolatile:
case Intrinsics::kUnsafePutObject:
case Intrinsics::kUnsafePutObjectOrdered:
case Intrinsics::kUnsafePutObjectVolatile:
case Intrinsics::kUnsafePutOrdered:
case Intrinsics::kUnsafePutVolatile:
case Intrinsics::kUnsafeLoadFence:
case Intrinsics::kUnsafeStoreFence:
case Intrinsics::kUnsafeFullFence:
case Intrinsics::kCRC32Update:
case Intrinsics::kCRC32UpdateBytes:
case Intrinsics::kCRC32UpdateByteBuffer:
case Intrinsics::kStringNewStringFromBytes:
case Intrinsics::kStringNewStringFromChars:
case Intrinsics::kStringNewStringFromString:
case Intrinsics::kMemoryPeekIntNative:
case Intrinsics::kMemoryPeekLongNative:
case Intrinsics::kMemoryPeekShortNative:
case Intrinsics::kMemoryPokeIntNative:
case Intrinsics::kMemoryPokeLongNative:
case Intrinsics::kMemoryPokeShortNative:
case Intrinsics::kVarHandleFullFence:
case Intrinsics::kVarHandleAcquireFence:
case Intrinsics::kVarHandleReleaseFence:
case Intrinsics::kVarHandleLoadLoadFence:
case Intrinsics::kVarHandleStoreStoreFence:
case Intrinsics::kVarHandleCompareAndExchange:
case Intrinsics::kVarHandleCompareAndExchangeAcquire:
case Intrinsics::kVarHandleCompareAndExchangeRelease:
case Intrinsics::kVarHandleCompareAndSet:
case Intrinsics::kVarHandleGet:
case Intrinsics::kVarHandleGetAcquire:
case Intrinsics::kVarHandleGetAndAdd:
case Intrinsics::kVarHandleGetAndAddAcquire:
case Intrinsics::kVarHandleGetAndAddRelease:
case Intrinsics::kVarHandleGetAndBitwiseAnd:
case Intrinsics::kVarHandleGetAndBitwiseAndAcquire:
case Intrinsics::kVarHandleGetAndBitwiseAndRelease:
case Intrinsics::kVarHandleGetAndBitwiseOr:
case Intrinsics::kVarHandleGetAndBitwiseOrAcquire:
case Intrinsics::kVarHandleGetAndBitwiseOrRelease:
case Intrinsics::kVarHandleGetAndBitwiseXor:
case Intrinsics::kVarHandleGetAndBitwiseXorAcquire:
case Intrinsics::kVarHandleGetAndBitwiseXorRelease:
case Intrinsics::kVarHandleGetAndSet:
case Intrinsics::kVarHandleGetAndSetAcquire:
case Intrinsics::kVarHandleGetAndSetRelease:
case Intrinsics::kVarHandleGetOpaque:
case Intrinsics::kVarHandleGetVolatile:
case Intrinsics::kVarHandleSet:
case Intrinsics::kVarHandleSetOpaque:
case Intrinsics::kVarHandleSetRelease:
case Intrinsics::kVarHandleSetVolatile:
case Intrinsics::kVarHandleWeakCompareAndSet:
case Intrinsics::kVarHandleWeakCompareAndSetAcquire:
case Intrinsics::kVarHandleWeakCompareAndSetPlain:
case Intrinsics::kVarHandleWeakCompareAndSetRelease:
return 0u;
// Remaining intrinsics are public API. We DCHECK that in SetIntrinsic().
return kAccPublicApi;
} else {
return method->GetAccessFlags() & kAccHiddenapiBits;
// Called by class linker when a new dex file has been registered. Assigns
// the AccessContext domain to the newly-registered dex file based on its
// location and class loader.
void InitializeDexFileDomain(const DexFile& dex_file, ObjPtr<mirror::ClassLoader> class_loader);
// Returns true if access to `member` should be denied in the given context.
// The decision is based on whether the caller is in a trusted context or not.
// Because determining the access context can be expensive, a lambda function
// "fn_get_access_context" is lazily invoked after other criteria have been
// considered.
// This function might print warnings into the log if the member is hidden.
template<typename T>
inline bool ShouldDenyAccessToMember(T* member,
const std::function<AccessContext()>& fn_get_access_context,
AccessMethod access_method)
REQUIRES_SHARED(Locks::mutator_lock_) {
DCHECK(member != nullptr);
// Get the runtime flags encoded in member's access flags.
// Note: this works for proxy methods because they inherit access flags from their
// respective interface methods.
const uint32_t runtime_flags = GetRuntimeFlags(member);
// Exit early if member is public API. This flag is also set for non-boot class
// path fields/methods.
if ((runtime_flags & kAccPublicApi) != 0) {
return false;
// Determine which domain the caller and callee belong to.
// This can be *very* expensive. This is why ShouldDenyAccessToMember
// should not be called on every individual access.
const AccessContext caller_context = fn_get_access_context();
const AccessContext callee_context(member->GetDeclaringClass());
// Non-boot classpath callers should have exited early.
// Check if the caller is always allowed to access members in the callee context.
if (caller_context.CanAlwaysAccess(callee_context)) {
return false;
// Check if this is platform accessing core platform. We may warn if `member` is
// not part of core platform API.
switch (caller_context.GetDomain()) {
case Domain::kApplication: {
// Exit early if access checks are completely disabled.
EnforcementPolicy policy = Runtime::Current()->GetHiddenApiEnforcementPolicy();
if (policy == EnforcementPolicy::kDisabled) {
return false;
// If this is a proxy method, look at the interface method instead.
member = detail::GetInterfaceMemberIfProxy(member);
// Decode hidden API access flags from the dex file.
// This is an O(N) operation scaling with the number of fields/methods
// in the class. Only do this on slow path and only do it once.
ApiList api_list(detail::GetDexFlags(member));
// Member is hidden and caller is not exempted. Enter slow path.
return detail::ShouldDenyAccessToMemberImpl(member, api_list, access_method);
case Domain::kPlatform: {
DCHECK(callee_context.GetDomain() == Domain::kCorePlatform);
// Member is part of core platform API. Accessing it is allowed.
if ((runtime_flags & kAccCorePlatformApi) != 0) {
return false;
// Allow access if access checks are disabled.
EnforcementPolicy policy = Runtime::Current()->GetCorePlatformApiEnforcementPolicy();
if (policy == EnforcementPolicy::kDisabled) {
return false;
// If this is a proxy method, look at the interface method instead.
member = detail::GetInterfaceMemberIfProxy(member);
// Access checks are not disabled, report the violation.
// This may also add kAccCorePlatformApi to the access flags of `member`
// so as to not warn again on next access.
return detail::HandleCorePlatformApiViolation(member,
case Domain::kCorePlatform: {
LOG(FATAL) << "CorePlatform domain should be allowed to access all domains";
// Helper method for callers where access context can be determined beforehand.
// Wraps AccessContext in a lambda and passes it to the real ShouldDenyAccessToMember.
template<typename T>
inline bool ShouldDenyAccessToMember(T* member,
const AccessContext& access_context,
AccessMethod access_method)
REQUIRES_SHARED(Locks::mutator_lock_) {
return ShouldDenyAccessToMember(member, [&]() { return access_context; }, access_method);
} // namespace hiddenapi
} // namespace art