/*
* Copyright (C) 2014 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.
*/
#define LOG_TAG "nativebridge"
#include "nativebridge/native_bridge.h"
#include <dlfcn.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <unistd.h>
#include <cstring>
#include <android-base/macros.h>
#include <log/log.h>
namespace android {
// Environment values required by the apps running with native bridge.
struct NativeBridgeRuntimeValues {
const char* os_arch;
const char* cpu_abi;
const char* cpu_abi2;
const char* *supported_abis;
int32_t abi_count;
};
// The symbol name exposed by native-bridge with the type of NativeBridgeCallbacks.
static constexpr const char* kNativeBridgeInterfaceSymbol = "NativeBridgeItf";
enum class NativeBridgeState {
kNotSetup, // Initial state.
kOpened, // After successful dlopen.
kPreInitialized, // After successful pre-initialization.
kInitialized, // After successful initialization.
kClosed // Closed or errors.
};
static constexpr const char* kNotSetupString = "kNotSetup";
static constexpr const char* kOpenedString = "kOpened";
static constexpr const char* kPreInitializedString = "kPreInitialized";
static constexpr const char* kInitializedString = "kInitialized";
static constexpr const char* kClosedString = "kClosed";
static const char* GetNativeBridgeStateString(NativeBridgeState state) {
switch (state) {
case NativeBridgeState::kNotSetup:
return kNotSetupString;
case NativeBridgeState::kOpened:
return kOpenedString;
case NativeBridgeState::kPreInitialized:
return kPreInitializedString;
case NativeBridgeState::kInitialized:
return kInitializedString;
case NativeBridgeState::kClosed:
return kClosedString;
}
}
// Current state of the native bridge.
static NativeBridgeState state = NativeBridgeState::kNotSetup;
// The version of NativeBridge implementation.
// Different Nativebridge interface needs the service of different version of
// Nativebridge implementation.
// Used by isCompatibleWith() which is introduced in v2.
enum NativeBridgeImplementationVersion {
// first version, not used.
DEFAULT_VERSION = 1,
// The version which signal semantic is introduced.
SIGNAL_VERSION = 2,
// The version which namespace semantic is introduced.
NAMESPACE_VERSION = 3,
// The version with vendor namespaces
VENDOR_NAMESPACE_VERSION = 4,
};
// Whether we had an error at some point.
static bool had_error = false;
// Handle of the loaded library.
static void* native_bridge_handle = nullptr;
// Pointer to the callbacks. Available as soon as LoadNativeBridge succeeds, but only initialized
// later.
static const NativeBridgeCallbacks* callbacks = nullptr;
// Callbacks provided by the environment to the bridge. Passed to LoadNativeBridge.
static const NativeBridgeRuntimeCallbacks* runtime_callbacks = nullptr;
// The app's code cache directory.
static char* app_code_cache_dir = nullptr;
// Code cache directory (relative to the application private directory)
// Ideally we'd like to call into framework to retrieve this name. However that's considered an
// implementation detail and will require either hacks or consistent refactorings. We compromise
// and hard code the directory name again here.
static constexpr const char* kCodeCacheDir = "code_cache";
// Characters allowed in a native bridge filename. The first character must
// be in [a-zA-Z] (expected 'l' for "libx"). The rest must be in [a-zA-Z0-9._-].
static bool CharacterAllowed(char c, bool first) {
if (first) {
return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z');
} else {
return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || ('0' <= c && c <= '9') ||
(c == '.') || (c == '_') || (c == '-');
}
}
static void ReleaseAppCodeCacheDir() {
if (app_code_cache_dir != nullptr) {
delete[] app_code_cache_dir;
app_code_cache_dir = nullptr;
}
}
// We only allow simple names for the library. It is supposed to be a file in
// /system/lib or /vendor/lib. Only allow a small range of characters, that is
// names consisting of [a-zA-Z0-9._-] and starting with [a-zA-Z].
bool NativeBridgeNameAcceptable(const char* nb_library_filename) {
const char* ptr = nb_library_filename;
if (*ptr == 0) {
// Emptry string. Allowed, means no native bridge.
return true;
} else {
// First character must be [a-zA-Z].
if (!CharacterAllowed(*ptr, true)) {
// Found an invalid fist character, don't accept.
ALOGE("Native bridge library %s has been rejected for first character %c",
nb_library_filename,
*ptr);
return false;
} else {
// For the rest, be more liberal.
ptr++;
while (*ptr != 0) {
if (!CharacterAllowed(*ptr, false)) {
// Found an invalid character, don't accept.
ALOGE("Native bridge library %s has been rejected for %c", nb_library_filename, *ptr);
return false;
}
ptr++;
}
}
return true;
}
}
// The policy of invoking Nativebridge changed in v3 with/without namespace.
// Suggest Nativebridge implementation not maintain backward-compatible.
static bool isCompatibleWith(const uint32_t version) {
// Libnativebridge is now designed to be forward-compatible. So only "0" is an unsupported
// version.
if (callbacks == nullptr || callbacks->version == 0 || version == 0) {
return false;
}
// If this is a v2+ bridge, it may not be forwards- or backwards-compatible. Check.
if (callbacks->version >= SIGNAL_VERSION) {
return callbacks->isCompatibleWith(version);
}
return true;
}
static void CloseNativeBridge(bool with_error) {
state = NativeBridgeState::kClosed;
had_error |= with_error;
ReleaseAppCodeCacheDir();
}
bool LoadNativeBridge(const char* nb_library_filename,
const NativeBridgeRuntimeCallbacks* runtime_cbs) {
// We expect only one place that calls LoadNativeBridge: Runtime::Init. At that point we are not
// multi-threaded, so we do not need locking here.
if (state != NativeBridgeState::kNotSetup) {
// Setup has been called before. Ignore this call.
if (nb_library_filename != nullptr) { // Avoids some log-spam for dalvikvm.
ALOGW("Called LoadNativeBridge for an already set up native bridge. State is %s.",
GetNativeBridgeStateString(state));
}
// Note: counts as an error, even though the bridge may be functional.
had_error = true;
return false;
}
if (nb_library_filename == nullptr || *nb_library_filename == 0) {
CloseNativeBridge(false);
return false;
} else {
if (!NativeBridgeNameAcceptable(nb_library_filename)) {
CloseNativeBridge(true);
} else {
// Try to open the library.
void* handle = dlopen(nb_library_filename, RTLD_LAZY);
if (handle != nullptr) {
callbacks = reinterpret_cast<NativeBridgeCallbacks*>(dlsym(handle,
kNativeBridgeInterfaceSymbol));
if (callbacks != nullptr) {
if (isCompatibleWith(NAMESPACE_VERSION)) {
// Store the handle for later.
native_bridge_handle = handle;
} else {
callbacks = nullptr;
dlclose(handle);
ALOGW("Unsupported native bridge interface.");
}
} else {
dlclose(handle);
}
}
// Two failure conditions: could not find library (dlopen failed), or could not find native
// bridge interface (dlsym failed). Both are an error and close the native bridge.
if (callbacks == nullptr) {
CloseNativeBridge(true);
} else {
runtime_callbacks = runtime_cbs;
state = NativeBridgeState::kOpened;
}
}
return state == NativeBridgeState::kOpened;
}
}
bool NeedsNativeBridge(const char* instruction_set) {
if (instruction_set == nullptr) {
ALOGE("Null instruction set in NeedsNativeBridge.");
return false;
}
return strncmp(instruction_set, ABI_STRING, strlen(ABI_STRING) + 1) != 0;
}
#ifdef __APPLE__
template<typename T> void UNUSED(const T&) {}
#endif
bool PreInitializeNativeBridge(const char* app_data_dir_in, const char* instruction_set) {
if (state != NativeBridgeState::kOpened) {
ALOGE("Invalid state: native bridge is expected to be opened.");
CloseNativeBridge(true);
return false;
}
if (app_data_dir_in == nullptr) {
ALOGE("Application private directory cannot be null.");
CloseNativeBridge(true);
return false;
}
// Create the path to the application code cache directory.
// The memory will be release after Initialization or when the native bridge is closed.
const size_t len = strlen(app_data_dir_in) + strlen(kCodeCacheDir) + 2; // '\0' + '/'
app_code_cache_dir = new char[len];
snprintf(app_code_cache_dir, len, "%s/%s", app_data_dir_in, kCodeCacheDir);
// Bind-mount /system/lib{,64}/<isa>/cpuinfo to /proc/cpuinfo.
// Failure is not fatal and will keep the native bridge in kPreInitialized.
state = NativeBridgeState::kPreInitialized;
#ifndef __APPLE__
if (instruction_set == nullptr) {
return true;
}
size_t isa_len = strlen(instruction_set);
if (isa_len > 10) {
// 10 is a loose upper bound on the currently known instruction sets (a tight bound is 7 for
// x86_64 [including the trailing \0]). This is so we don't have to change here if there will
// be another instruction set in the future.
ALOGW("Instruction set %s is malformed, must be less than or equal to 10 characters.",
instruction_set);
return true;
}
// If the file does not exist, the mount command will fail,
// so we save the extra file existence check.
char cpuinfo_path[1024];
#if defined(__ANDROID__)
snprintf(cpuinfo_path, sizeof(cpuinfo_path), "/system/lib"
#ifdef __LP64__
"64"
#endif // __LP64__
"/%s/cpuinfo", instruction_set);
#else // !__ANDROID__
// To be able to test on the host, we hardwire a relative path.
snprintf(cpuinfo_path, sizeof(cpuinfo_path), "./cpuinfo");
#endif
// Bind-mount.
if (TEMP_FAILURE_RETRY(mount(cpuinfo_path, // Source.
"/proc/cpuinfo", // Target.
nullptr, // FS type.
MS_BIND, // Mount flags: bind mount.
nullptr)) == -1) { // "Data."
ALOGW("Failed to bind-mount %s as /proc/cpuinfo: %s", cpuinfo_path, strerror(errno));
}
#else // __APPLE__
UNUSED(instruction_set);
ALOGW("Mac OS does not support bind-mounting. Host simulation of native bridge impossible.");
#endif
return true;
}
static void SetCpuAbi(JNIEnv* env, jclass build_class, const char* field, const char* value) {
if (value != nullptr) {
jfieldID field_id = env->GetStaticFieldID(build_class, field, "Ljava/lang/String;");
if (field_id == nullptr) {
env->ExceptionClear();
ALOGW("Could not find %s field.", field);
return;
}
jstring str = env->NewStringUTF(value);
if (str == nullptr) {
env->ExceptionClear();
ALOGW("Could not create string %s.", value);
return;
}
env->SetStaticObjectField(build_class, field_id, str);
}
}
// Set up the environment for the bridged app.
static void SetupEnvironment(const NativeBridgeCallbacks* callbacks, JNIEnv* env, const char* isa) {
// Need a JNIEnv* to do anything.
if (env == nullptr) {
ALOGW("No JNIEnv* to set up app environment.");
return;
}
// Query the bridge for environment values.
const struct NativeBridgeRuntimeValues* env_values = callbacks->getAppEnv(isa);
if (env_values == nullptr) {
return;
}
// Keep the JNIEnv clean.
jint success = env->PushLocalFrame(16); // That should be small and large enough.
if (success < 0) {
// Out of memory, really borked.
ALOGW("Out of memory while setting up app environment.");
env->ExceptionClear();
return;
}
// Reset CPU_ABI & CPU_ABI2 to values required by the apps running with native bridge.
if (env_values->cpu_abi != nullptr || env_values->cpu_abi2 != nullptr ||
env_values->abi_count >= 0) {
jclass bclass_id = env->FindClass("android/os/Build");
if (bclass_id != nullptr) {
SetCpuAbi(env, bclass_id, "CPU_ABI", env_values->cpu_abi);
SetCpuAbi(env, bclass_id, "CPU_ABI2", env_values->cpu_abi2);
} else {
// For example in a host test environment.
env->ExceptionClear();
ALOGW("Could not find Build class.");
}
}
if (env_values->os_arch != nullptr) {
jclass sclass_id = env->FindClass("java/lang/System");
if (sclass_id != nullptr) {
jmethodID set_prop_id = env->GetStaticMethodID(sclass_id, "setUnchangeableSystemProperty",
"(Ljava/lang/String;Ljava/lang/String;)V");
if (set_prop_id != nullptr) {
// Init os.arch to the value reqired by the apps running with native bridge.
env->CallStaticVoidMethod(sclass_id, set_prop_id, env->NewStringUTF("os.arch"),
env->NewStringUTF(env_values->os_arch));
} else {
env->ExceptionClear();
ALOGW("Could not find System#setUnchangeableSystemProperty.");
}
} else {
env->ExceptionClear();
ALOGW("Could not find System class.");
}
}
// Make it pristine again.
env->PopLocalFrame(nullptr);
}
bool InitializeNativeBridge(JNIEnv* env, const char* instruction_set) {
// We expect only one place that calls InitializeNativeBridge: Runtime::DidForkFromZygote. At that
// point we are not multi-threaded, so we do not need locking here.
if (state == NativeBridgeState::kPreInitialized) {
// Check for code cache: if it doesn't exist try to create it.
struct stat st;
if (stat(app_code_cache_dir, &st) == -1) {
if (errno == ENOENT) {
if (mkdir(app_code_cache_dir, S_IRWXU | S_IRWXG | S_IXOTH) == -1) {
ALOGW("Cannot create code cache directory %s: %s.", app_code_cache_dir, strerror(errno));
ReleaseAppCodeCacheDir();
}
} else {
ALOGW("Cannot stat code cache directory %s: %s.", app_code_cache_dir, strerror(errno));
ReleaseAppCodeCacheDir();
}
} else if (!S_ISDIR(st.st_mode)) {
ALOGW("Code cache is not a directory %s.", app_code_cache_dir);
ReleaseAppCodeCacheDir();
}
// If we're still PreInitialized (dind't fail the code cache checks) try to initialize.
if (state == NativeBridgeState::kPreInitialized) {
if (callbacks->initialize(runtime_callbacks, app_code_cache_dir, instruction_set)) {
SetupEnvironment(callbacks, env, instruction_set);
state = NativeBridgeState::kInitialized;
// We no longer need the code cache path, release the memory.
ReleaseAppCodeCacheDir();
} else {
// Unload the library.
dlclose(native_bridge_handle);
CloseNativeBridge(true);
}
}
} else {
CloseNativeBridge(true);
}
return state == NativeBridgeState::kInitialized;
}
void UnloadNativeBridge() {
// We expect only one place that calls UnloadNativeBridge: Runtime::DidForkFromZygote. At that
// point we are not multi-threaded, so we do not need locking here.
switch(state) {
case NativeBridgeState::kOpened:
case NativeBridgeState::kPreInitialized:
case NativeBridgeState::kInitialized:
// Unload.
dlclose(native_bridge_handle);
CloseNativeBridge(false);
break;
case NativeBridgeState::kNotSetup:
// Not even set up. Error.
CloseNativeBridge(true);
break;
case NativeBridgeState::kClosed:
// Ignore.
break;
}
}
bool NativeBridgeError() {
return had_error;
}
bool NativeBridgeAvailable() {
return state == NativeBridgeState::kOpened
|| state == NativeBridgeState::kPreInitialized
|| state == NativeBridgeState::kInitialized;
}
bool NativeBridgeInitialized() {
// Calls of this are supposed to happen in a state where the native bridge is stable, i.e., after
// Runtime::DidForkFromZygote. In that case we do not need a lock.
return state == NativeBridgeState::kInitialized;
}
void* NativeBridgeLoadLibrary(const char* libpath, int flag) {
if (NativeBridgeInitialized()) {
return callbacks->loadLibrary(libpath, flag);
}
return nullptr;
}
void* NativeBridgeGetTrampoline(void* handle, const char* name, const char* shorty,
uint32_t len) {
if (NativeBridgeInitialized()) {
return callbacks->getTrampoline(handle, name, shorty, len);
}
return nullptr;
}
bool NativeBridgeIsSupported(const char* libpath) {
if (NativeBridgeInitialized()) {
return callbacks->isSupported(libpath);
}
return false;
}
uint32_t NativeBridgeGetVersion() {
if (NativeBridgeAvailable()) {
return callbacks->version;
}
return 0;
}
NativeBridgeSignalHandlerFn NativeBridgeGetSignalHandler(int signal) {
if (NativeBridgeInitialized()) {
if (isCompatibleWith(SIGNAL_VERSION)) {
return callbacks->getSignalHandler(signal);
} else {
ALOGE("not compatible with version %d, cannot get signal handler", SIGNAL_VERSION);
}
}
return nullptr;
}
int NativeBridgeUnloadLibrary(void* handle) {
if (NativeBridgeInitialized()) {
if (isCompatibleWith(NAMESPACE_VERSION)) {
return callbacks->unloadLibrary(handle);
} else {
ALOGE("not compatible with version %d, cannot unload library", NAMESPACE_VERSION);
}
}
return -1;
}
const char* NativeBridgeGetError() {
if (NativeBridgeInitialized()) {
if (isCompatibleWith(NAMESPACE_VERSION)) {
return callbacks->getError();
} else {
return "native bridge implementation is not compatible with version 3, cannot get message";
}
}
return "native bridge is not initialized";
}
bool NativeBridgeIsPathSupported(const char* path) {
if (NativeBridgeInitialized()) {
if (isCompatibleWith(NAMESPACE_VERSION)) {
return callbacks->isPathSupported(path);
} else {
ALOGE("not compatible with version %d, cannot check via library path", NAMESPACE_VERSION);
}
}
return false;
}
bool NativeBridgeInitAnonymousNamespace(const char* public_ns_sonames,
const char* anon_ns_library_path) {
if (NativeBridgeInitialized()) {
if (isCompatibleWith(NAMESPACE_VERSION)) {
return callbacks->initAnonymousNamespace(public_ns_sonames, anon_ns_library_path);
} else {
ALOGE("not compatible with version %d, cannot init namespace", NAMESPACE_VERSION);
}
}
return false;
}
native_bridge_namespace_t* NativeBridgeCreateNamespace(const char* name,
const char* ld_library_path,
const char* default_library_path,
uint64_t type,
const char* permitted_when_isolated_path,
native_bridge_namespace_t* parent_ns) {
if (NativeBridgeInitialized()) {
if (isCompatibleWith(NAMESPACE_VERSION)) {
return callbacks->createNamespace(name,
ld_library_path,
default_library_path,
type,
permitted_when_isolated_path,
parent_ns);
} else {
ALOGE("not compatible with version %d, cannot create namespace %s", NAMESPACE_VERSION, name);
}
}
return nullptr;
}
bool NativeBridgeLinkNamespaces(native_bridge_namespace_t* from, native_bridge_namespace_t* to,
const char* shared_libs_sonames) {
if (NativeBridgeInitialized()) {
if (isCompatibleWith(NAMESPACE_VERSION)) {
return callbacks->linkNamespaces(from, to, shared_libs_sonames);
} else {
ALOGE("not compatible with version %d, cannot init namespace", NAMESPACE_VERSION);
}
}
return false;
}
native_bridge_namespace_t* NativeBridgeGetVendorNamespace() {
if (!NativeBridgeInitialized() || !isCompatibleWith(VENDOR_NAMESPACE_VERSION)) {
return nullptr;
}
return callbacks->getVendorNamespace();
}
void* NativeBridgeLoadLibraryExt(const char* libpath, int flag, native_bridge_namespace_t* ns) {
if (NativeBridgeInitialized()) {
if (isCompatibleWith(NAMESPACE_VERSION)) {
return callbacks->loadLibraryExt(libpath, flag, ns);
} else {
ALOGE("not compatible with version %d, cannot load library in namespace", NAMESPACE_VERSION);
}
}
return nullptr;
}
}; // namespace android