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platform_system_core/libnativeloader/native_loader.cpp

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/*
* Copyright (C) 2015 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 "nativeloader/native_loader.h"
#include "ScopedUtfChars.h"
#include <dlfcn.h>
#ifdef __ANDROID__
#include "dlext_namespaces.h"
#include "cutils/properties.h"
#define LOG_TAG "libnativeloader"
#include "log/log.h"
#endif
#include <algorithm>
#include <vector>
#include <string>
#include <mutex>
#include "android-base/file.h"
#include "android-base/macros.h"
#include "android-base/strings.h"
namespace android {
#if defined(__ANDROID__)
static constexpr const char* kPublicNativeLibrariesSystemConfigPathFromRoot = "/etc/public.libraries.txt";
static constexpr const char* kPublicNativeLibrariesVendorConfig = "/vendor/etc/public.libraries.txt";
// (http://b/27588281) This is a workaround for apps using custom classloaders and calling
// System.load() with an absolute path which is outside of the classloader library search path.
// This list includes all directories app is allowed to access this way.
static constexpr const char* kWhitelistedDirectories = "/data:/mnt/expand";
static bool is_debuggable() {
char debuggable[PROP_VALUE_MAX];
property_get("ro.debuggable", debuggable, "0");
return std::string(debuggable) == "1";
}
class LibraryNamespaces {
public:
LibraryNamespaces() : initialized_(false) { }
android_namespace_t* Create(JNIEnv* env,
jobject class_loader,
bool is_shared,
jstring java_library_path,
jstring java_permitted_path,
int32_t target_sdk_version) {
std::string library_path; // empty string by default.
if (java_library_path != nullptr) {
ScopedUtfChars library_path_utf_chars(env, java_library_path);
library_path = library_path_utf_chars.c_str();
}
// (http://b/27588281) This is a workaround for apps using custom
// classloaders and calling System.load() with an absolute path which
// is outside of the classloader library search path.
//
// This part effectively allows such a classloader to access anything
// under /data and /mnt/expand
std::string permitted_path = kWhitelistedDirectories;
if (java_permitted_path != nullptr) {
ScopedUtfChars path(env, java_permitted_path);
if (path.c_str() != nullptr && path.size() > 0) {
permitted_path = permitted_path + ":" + path.c_str();
}
}
if (!initialized_ && !InitPublicNamespace(library_path.c_str(), target_sdk_version)) {
return nullptr;
}
android_namespace_t* ns = FindNamespaceByClassLoader(env, class_loader);
LOG_ALWAYS_FATAL_IF(ns != nullptr,
"There is already a namespace associated with this classloader");
uint64_t namespace_type = ANDROID_NAMESPACE_TYPE_ISOLATED;
if (is_shared) {
namespace_type |= ANDROID_NAMESPACE_TYPE_SHARED;
}
ns = android_create_namespace("classloader-namespace",
nullptr,
library_path.c_str(),
namespace_type,
!permitted_path.empty() ?
permitted_path.c_str() :
nullptr);
if (ns != nullptr) {
namespaces_.push_back(std::make_pair(env->NewWeakGlobalRef(class_loader), ns));
}
return ns;
}
android_namespace_t* FindNamespaceByClassLoader(JNIEnv* env, jobject class_loader) {
auto it = std::find_if(namespaces_.begin(), namespaces_.end(),
[&](const std::pair<jweak, android_namespace_t*>& value) {
return env->IsSameObject(value.first, class_loader);
});
return it != namespaces_.end() ? it->second : nullptr;
}
void Initialize() {
// Once public namespace is initialized there is no
// point in running this code - it will have no effect
// on the current list of public libraries.
if (initialized_) {
return;
}
std::vector<std::string> sonames;
const char* android_root_env = getenv("ANDROID_ROOT");
std::string root_dir = android_root_env != nullptr ? android_root_env : "/system";
std::string public_native_libraries_system_config =
root_dir + kPublicNativeLibrariesSystemConfigPathFromRoot;
LOG_ALWAYS_FATAL_IF(!ReadConfig(public_native_libraries_system_config, &sonames),
"Error reading public native library list from \"%s\": %s",
public_native_libraries_system_config.c_str(), strerror(errno));
// For debuggable platform builds use ANDROID_ADDITIONAL_PUBLIC_LIBRARIES environment
// variable to add libraries to the list. This is intended for platform tests only.
if (is_debuggable()) {
const char* additional_libs = getenv("ANDROID_ADDITIONAL_PUBLIC_LIBRARIES");
if (additional_libs != nullptr && additional_libs[0] != '\0') {
std::vector<std::string> additional_libs_vector = base::Split(additional_libs, ":");
std::copy(additional_libs_vector.begin(),
additional_libs_vector.end(),
std::back_inserter(sonames));
}
}
// This file is optional, quietly ignore if the file does not exist.
ReadConfig(kPublicNativeLibrariesVendorConfig, &sonames);
// android_init_namespaces() expects all the public libraries
// to be loaded so that they can be found by soname alone.
//
// TODO(dimitry): this is a bit misleading since we do not know
// if the vendor public library is going to be opened from /vendor/lib
// we might as well end up loading them from /system/lib
// For now we rely on CTS test to catch things like this but
// it should probably be addressed in the future.
for (const auto& soname : sonames) {
dlopen(soname.c_str(), RTLD_NOW | RTLD_NODELETE);
}
public_libraries_ = base::Join(sonames, ':');
}
void Reset() {
namespaces_.clear();
}
private:
bool ReadConfig(const std::string& configFile, std::vector<std::string>* sonames) {
// Read list of public native libraries from the config file.
std::string file_content;
if(!base::ReadFileToString(configFile, &file_content)) {
return false;
}
std::vector<std::string> lines = base::Split(file_content, "\n");
for (const auto& line : lines) {
auto trimmed_line = base::Trim(line);
if (trimmed_line[0] == '#' || trimmed_line.empty()) {
continue;
}
sonames->push_back(trimmed_line);
}
return true;
}
bool InitPublicNamespace(const char* library_path, int32_t target_sdk_version) {
std::string publicNativeLibraries = public_libraries_;
UNUSED(target_sdk_version);
// (http://b/25844435) - Some apps call dlopen from generated code (mono jited
// code is one example) unknown to linker in which case linker uses anonymous
// namespace. The second argument specifies the search path for the anonymous
// namespace which is the library_path of the classloader.
initialized_ = android_init_namespaces(publicNativeLibraries.c_str(), library_path);
return initialized_;
}
bool initialized_;
std::vector<std::pair<jweak, android_namespace_t*>> namespaces_;
std::string public_libraries_;
DISALLOW_COPY_AND_ASSIGN(LibraryNamespaces);
};
static std::mutex g_namespaces_mutex;
static LibraryNamespaces* g_namespaces = new LibraryNamespaces;
#endif
void InitializeNativeLoader() {
#if defined(__ANDROID__)
std::lock_guard<std::mutex> guard(g_namespaces_mutex);
g_namespaces->Initialize();
#endif
}
void ResetNativeLoader() {
#if defined(__ANDROID__)
std::lock_guard<std::mutex> guard(g_namespaces_mutex);
g_namespaces->Reset();
#endif
}
jstring CreateClassLoaderNamespace(JNIEnv* env,
int32_t target_sdk_version,
jobject class_loader,
bool is_shared,
jstring library_path,
jstring permitted_path) {
#if defined(__ANDROID__)
UNUSED(target_sdk_version);
std::lock_guard<std::mutex> guard(g_namespaces_mutex);
android_namespace_t* ns = g_namespaces->Create(env,
class_loader,
is_shared,
library_path,
permitted_path,
target_sdk_version);
if (ns == nullptr) {
return env->NewStringUTF(dlerror());
}
#else
UNUSED(env, target_sdk_version, class_loader, is_shared,
library_path, permitted_path);
#endif
return nullptr;
}
void* OpenNativeLibrary(JNIEnv* env,
int32_t target_sdk_version,
const char* path,
jobject class_loader,
jstring library_path) {
#if defined(__ANDROID__)
UNUSED(target_sdk_version);
if (class_loader == nullptr) {
return dlopen(path, RTLD_NOW);
}
std::lock_guard<std::mutex> guard(g_namespaces_mutex);
android_namespace_t* ns = g_namespaces->FindNamespaceByClassLoader(env, class_loader);
if (ns == nullptr) {
// This is the case where the classloader was not created by ApplicationLoaders
// In this case we create an isolated not-shared namespace for it.
ns = g_namespaces->Create(env, class_loader, false, library_path, nullptr, target_sdk_version);
if (ns == nullptr) {
return nullptr;
}
}
android_dlextinfo extinfo;
extinfo.flags = ANDROID_DLEXT_USE_NAMESPACE;
extinfo.library_namespace = ns;
return android_dlopen_ext(path, RTLD_NOW, &extinfo);
#else
UNUSED(env, target_sdk_version, class_loader, library_path);
return dlopen(path, RTLD_NOW);
#endif
}
bool CloseNativeLibrary(void* handle) {
return dlclose(handle) == 0;
}
#if defined(__ANDROID__)
android_namespace_t* FindNamespaceByClassLoader(JNIEnv* env, jobject class_loader) {
std::lock_guard<std::mutex> guard(g_namespaces_mutex);
return g_namespaces->FindNamespaceByClassLoader(env, class_loader);
}
#endif
}; // android namespace
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