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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
*
* 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.
*/
#include "hidden_api.h"
#include <nativehelper/scoped_local_ref.h>
#include "base/dumpable.h"
#include "thread-current-inl.h"
#include "well_known_classes.h"
#ifdef ART_TARGET_ANDROID
#include <metricslogger/metrics_logger.h>
using android::metricslogger::ComplexEventLogger;
using android::metricslogger::ACTION_HIDDEN_API_ACCESSED;
using android::metricslogger::FIELD_HIDDEN_API_ACCESS_METHOD;
using android::metricslogger::FIELD_HIDDEN_API_ACCESS_DENIED;
using android::metricslogger::FIELD_HIDDEN_API_SIGNATURE;
#endif
namespace art {
namespace hiddenapi {
// Set to true if we should always print a warning in logcat for all hidden API accesses, not just
// dark grey and black. This can be set to true for developer preview / beta builds, but should be
// false for public release builds.
// Note that when flipping this flag, you must also update the expectations of test 674-hiddenapi
// as it affects whether or not we warn for light grey APIs that have been added to the exemptions
// list.
static constexpr bool kLogAllAccesses = false;
static inline std::ostream& operator<<(std::ostream& os, AccessMethod value) {
switch (value) {
case kNone:
LOG(FATAL) << "Internal access to hidden API should not be logged";
UNREACHABLE();
case kReflection:
os << "reflection";
break;
case kJNI:
os << "JNI";
break;
case kLinking:
os << "linking";
break;
}
return os;
}
static constexpr bool EnumsEqual(EnforcementPolicy policy, HiddenApiAccessFlags::ApiList apiList) {
return static_cast<int>(policy) == static_cast<int>(apiList);
}
// GetMemberAction-related static_asserts.
static_assert(
EnumsEqual(EnforcementPolicy::kDarkGreyAndBlackList, HiddenApiAccessFlags::kDarkGreylist) &&
EnumsEqual(EnforcementPolicy::kBlacklistOnly, HiddenApiAccessFlags::kBlacklist),
"Mismatch between EnforcementPolicy and ApiList enums");
static_assert(
EnforcementPolicy::kJustWarn < EnforcementPolicy::kDarkGreyAndBlackList &&
EnforcementPolicy::kDarkGreyAndBlackList < EnforcementPolicy::kBlacklistOnly,
"EnforcementPolicy values ordering not correct");
namespace detail {
MemberSignature::MemberSignature(ArtField* field) {
class_name_ = field->GetDeclaringClass()->GetDescriptor(&tmp_);
member_name_ = field->GetName();
type_signature_ = field->GetTypeDescriptor();
type_ = kField;
}
MemberSignature::MemberSignature(ArtMethod* method) {
// If this is a proxy method, print the signature of the interface method.
method = method->GetInterfaceMethodIfProxy(
Runtime::Current()->GetClassLinker()->GetImagePointerSize());
class_name_ = method->GetDeclaringClass()->GetDescriptor(&tmp_);
member_name_ = method->GetName();
type_signature_ = method->GetSignature().ToString();
type_ = kMethod;
}
inline std::vector<const char*> MemberSignature::GetSignatureParts() const {
if (type_ == kField) {
return { class_name_.c_str(), "->", member_name_.c_str(), ":", type_signature_.c_str() };
} else {
DCHECK_EQ(type_, kMethod);
return { class_name_.c_str(), "->", member_name_.c_str(), type_signature_.c_str() };
}
}
bool MemberSignature::DoesPrefixMatch(const std::string& prefix) const {
size_t pos = 0;
for (const char* part : GetSignatureParts()) {
size_t count = std::min(prefix.length() - pos, strlen(part));
if (prefix.compare(pos, count, part, 0, count) == 0) {
pos += count;
} else {
return false;
}
}
// We have a complete match if all parts match (we exit the loop without
// returning) AND we've matched the whole prefix.
return pos == prefix.length();
}
bool MemberSignature::IsExempted(const std::vector<std::string>& exemptions) {
for (const std::string& exemption : exemptions) {
if (DoesPrefixMatch(exemption)) {
return true;
}
}
return false;
}
void MemberSignature::Dump(std::ostream& os) const {
for (const char* part : GetSignatureParts()) {
os << part;
}
}
void MemberSignature::WarnAboutAccess(AccessMethod access_method,
HiddenApiAccessFlags::ApiList list) {
LOG(WARNING) << "Accessing hidden " << (type_ == kField ? "field " : "method ")
<< Dumpable<MemberSignature>(*this) << " (" << list << ", " << access_method << ")";
}
#ifdef ART_TARGET_ANDROID
// Convert an AccessMethod enum to a value for logging from the proto enum.
// This method may look odd (the enum values are current the same), but it
// prevents coupling the internal enum to the proto enum (which should never
// be changed) so that we are free to change the internal one if necessary in
// future.
inline static int32_t GetEnumValueForLog(AccessMethod access_method) {
switch (access_method) {
case kNone:
return android::metricslogger::ACCESS_METHOD_NONE;
case kReflection:
return android::metricslogger::ACCESS_METHOD_REFLECTION;
case kJNI:
return android::metricslogger::ACCESS_METHOD_JNI;
case kLinking:
return android::metricslogger::ACCESS_METHOD_LINKING;
default:
DCHECK(false);
}
}
#endif
void MemberSignature::LogAccessToEventLog(AccessMethod access_method, Action action_taken) {
#ifdef ART_TARGET_ANDROID
if (access_method == kLinking || access_method == kNone) {
// Linking warnings come from static analysis/compilation of the bytecode
// and can contain false positives (i.e. code that is never run). We choose
// not to log these in the event log.
// None does not correspond to actual access, so should also be ignored.
return;
}
ComplexEventLogger log_maker(ACTION_HIDDEN_API_ACCESSED);
log_maker.AddTaggedData(FIELD_HIDDEN_API_ACCESS_METHOD, GetEnumValueForLog(access_method));
if (action_taken == kDeny) {
log_maker.AddTaggedData(FIELD_HIDDEN_API_ACCESS_DENIED, 1);
}
std::ostringstream signature_str;
Dump(signature_str);
log_maker.AddTaggedData(FIELD_HIDDEN_API_SIGNATURE, signature_str.str());
log_maker.Record();
#else
UNUSED(access_method);
UNUSED(action_taken);
#endif
}
static ALWAYS_INLINE bool CanUpdateMemberAccessFlags(ArtField*) {
return true;
}
static ALWAYS_INLINE bool CanUpdateMemberAccessFlags(ArtMethod* method) {
return !method->IsIntrinsic();
}
template<typename T>
static ALWAYS_INLINE void MaybeWhitelistMember(Runtime* runtime, T* member)
REQUIRES_SHARED(Locks::mutator_lock_) {
if (CanUpdateMemberAccessFlags(member) && runtime->ShouldDedupeHiddenApiWarnings()) {
member->SetAccessFlags(HiddenApiAccessFlags::EncodeForRuntime(
member->GetAccessFlags(), HiddenApiAccessFlags::kWhitelist));
}
}
template<typename T>
Action GetMemberActionImpl(T* member,
HiddenApiAccessFlags::ApiList api_list,
Action action,
AccessMethod access_method) {
DCHECK_NE(action, kAllow);
// Get the signature, we need it later.
MemberSignature member_signature(member);
Runtime* runtime = Runtime::Current();
// Check for an exemption first. Exempted APIs are treated as white list.
// We only do this if we're about to deny, or if the app is debuggable. This is because:
// - we only print a warning for light greylist violations for debuggable apps
// - for non-debuggable apps, there is no distinction between light grey & whitelisted APIs.
// - we want to avoid the overhead of checking for exemptions for light greylisted APIs whenever
// possible.
const bool shouldWarn = kLogAllAccesses || runtime->IsJavaDebuggable();
if (shouldWarn || action == kDeny) {
if (member_signature.IsExempted(runtime->GetHiddenApiExemptions())) {
action = kAllow;
// Avoid re-examining the exemption list next time.
// Note this results in no warning for the member, which seems like what one would expect.
// Exemptions effectively adds new members to the whitelist.
MaybeWhitelistMember(runtime, member);
return kAllow;
}
if (access_method != kNone) {
// Print a log message with information about this class member access.
// We do this if we're about to block access, or the app is debuggable.
member_signature.WarnAboutAccess(access_method, api_list);
}
}
if (kIsTargetBuild && !kIsTargetLinux) {
uint32_t eventLogSampleRate = runtime->GetHiddenApiEventLogSampleRate();
// Assert that RAND_MAX is big enough, to ensure sampling below works as expected.
static_assert(RAND_MAX >= 0xffff, "RAND_MAX too small");
if (eventLogSampleRate != 0 &&
(static_cast<uint32_t>(std::rand()) & 0xffff) < eventLogSampleRate) {
member_signature.LogAccessToEventLog(access_method, action);
}
}
if (action == kDeny) {
// Block access
return action;
}
// Allow access to this member but print a warning.
DCHECK(action == kAllowButWarn || action == kAllowButWarnAndToast);
if (access_method != kNone) {
// Depending on a runtime flag, we might move the member into whitelist and
// skip the warning the next time the member is accessed.
MaybeWhitelistMember(runtime, member);
// If this action requires a UI warning, set the appropriate flag.
if (shouldWarn &&
(action == kAllowButWarnAndToast || runtime->ShouldAlwaysSetHiddenApiWarningFlag())) {
runtime->SetPendingHiddenApiWarning(true);
}
}
return action;
}
// Need to instantiate this.
template Action GetMemberActionImpl<ArtField>(ArtField* member,
HiddenApiAccessFlags::ApiList api_list,
Action action,
AccessMethod access_method);
template Action GetMemberActionImpl<ArtMethod>(ArtMethod* member,
HiddenApiAccessFlags::ApiList api_list,
Action action,
AccessMethod access_method);
} // namespace detail
template<typename T>
void NotifyHiddenApiListener(T* member) {
Runtime* runtime = Runtime::Current();
if (!runtime->IsAotCompiler()) {
ScopedObjectAccessUnchecked soa(Thread::Current());
ScopedLocalRef<jobject> consumer_object(soa.Env(),
soa.Env()->GetStaticObjectField(
WellKnownClasses::dalvik_system_VMRuntime,
WellKnownClasses::dalvik_system_VMRuntime_nonSdkApiUsageConsumer));
// If the consumer is non-null, we call back to it to let it know that we
// have encountered an API that's in one of our lists.
if (consumer_object != nullptr) {
detail::MemberSignature member_signature(member);
std::ostringstream member_signature_str;
member_signature.Dump(member_signature_str);
ScopedLocalRef<jobject> signature_str(
soa.Env(),
soa.Env()->NewStringUTF(member_signature_str.str().c_str()));
// Call through to Consumer.accept(String memberSignature);
soa.Env()->CallVoidMethod(consumer_object.get(),
WellKnownClasses::java_util_function_Consumer_accept,
signature_str.get());
}
}
}
template void NotifyHiddenApiListener<ArtMethod>(ArtMethod* member);
template void NotifyHiddenApiListener<ArtField>(ArtField* member);
} // namespace hiddenapi
} // namespace art