b31caa95ec
Now that we have the fixed list of whitelisted libraries there is no longer need to check if java_permitted_path is nullptr. In fact checking it prevents custom classloaders created by apps from loading libraries using absolute path. Bug: http://b/28659864 Change-Id: I1bfc16a573b090f70f078ecccd0e4016939a5dc0
298 lines
10 KiB
C++
298 lines
10 KiB
C++
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "nativeloader/native_loader.h"
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#include "ScopedUtfChars.h"
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#include <dlfcn.h>
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#ifdef __ANDROID__
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#include "dlext_namespaces.h"
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#include "cutils/properties.h"
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#include "log/log.h"
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#endif
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#include <algorithm>
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#include <vector>
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#include <string>
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#include <mutex>
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#include "android-base/file.h"
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#include "android-base/macros.h"
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#include "android-base/strings.h"
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namespace android {
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#if defined(__ANDROID__)
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static constexpr const char* kPublicNativeLibrariesSystemConfigPathFromRoot = "/etc/public.libraries.txt";
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static constexpr const char* kPublicNativeLibrariesVendorConfig = "/vendor/etc/public.libraries.txt";
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// (http://b/27588281) This is a workaround for apps using custom classloaders and calling
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// System.load() with an absolute path which is outside of the classloader library search path.
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// This list includes all directories app is allowed to access this way.
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static constexpr const char* kWhitelistedDirectories = "/data:/mnt/expand";
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static bool is_debuggable() {
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char debuggable[PROP_VALUE_MAX];
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property_get("ro.debuggable", debuggable, "0");
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return std::string(debuggable) == "1";
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}
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class LibraryNamespaces {
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public:
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LibraryNamespaces() : initialized_(false) { }
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android_namespace_t* Create(JNIEnv* env,
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jobject class_loader,
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bool is_shared,
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jstring java_library_path,
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jstring java_permitted_path) {
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std::string library_path; // empty string by default.
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if (java_library_path != nullptr) {
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ScopedUtfChars library_path_utf_chars(env, java_library_path);
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library_path = library_path_utf_chars.c_str();
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}
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// (http://b/27588281) This is a workaround for apps using custom
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// classloaders and calling System.load() with an absolute path which
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// is outside of the classloader library search path.
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//
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// This part effectively allows such a classloader to access anything
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// under /data and /mnt/expand
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std::string permitted_path = kWhitelistedDirectories;
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if (java_permitted_path != nullptr) {
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ScopedUtfChars path(env, java_permitted_path);
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if (path.c_str() != nullptr && path.size() > 0) {
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permitted_path = permitted_path + ":" + path.c_str();
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}
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}
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if (!initialized_ && !InitPublicNamespace(library_path.c_str())) {
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return nullptr;
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}
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android_namespace_t* ns = FindNamespaceByClassLoader(env, class_loader);
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LOG_ALWAYS_FATAL_IF(ns != nullptr,
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"There is already a namespace associated with this classloader");
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uint64_t namespace_type = ANDROID_NAMESPACE_TYPE_ISOLATED;
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if (is_shared) {
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namespace_type |= ANDROID_NAMESPACE_TYPE_SHARED;
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}
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ns = android_create_namespace("classloader-namespace",
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nullptr,
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library_path.c_str(),
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namespace_type,
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permitted_path.c_str());
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if (ns != nullptr) {
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namespaces_.push_back(std::make_pair(env->NewWeakGlobalRef(class_loader), ns));
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}
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return ns;
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}
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android_namespace_t* FindNamespaceByClassLoader(JNIEnv* env, jobject class_loader) {
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auto it = std::find_if(namespaces_.begin(), namespaces_.end(),
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[&](const std::pair<jweak, android_namespace_t*>& value) {
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return env->IsSameObject(value.first, class_loader);
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});
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return it != namespaces_.end() ? it->second : nullptr;
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}
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void Initialize() {
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// Once public namespace is initialized there is no
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// point in running this code - it will have no effect
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// on the current list of public libraries.
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if (initialized_) {
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return;
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}
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std::vector<std::string> sonames;
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const char* android_root_env = getenv("ANDROID_ROOT");
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std::string root_dir = android_root_env != nullptr ? android_root_env : "/system";
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std::string public_native_libraries_system_config =
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root_dir + kPublicNativeLibrariesSystemConfigPathFromRoot;
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LOG_ALWAYS_FATAL_IF(!ReadConfig(public_native_libraries_system_config, &sonames),
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"Error reading public native library list from \"%s\": %s",
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public_native_libraries_system_config.c_str(), strerror(errno));
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// For debuggable platform builds use ANDROID_ADDITIONAL_PUBLIC_LIBRARIES environment
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// variable to add libraries to the list. This is intended for platform tests only.
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if (is_debuggable()) {
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const char* additional_libs = getenv("ANDROID_ADDITIONAL_PUBLIC_LIBRARIES");
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if (additional_libs != nullptr && additional_libs[0] != '\0') {
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std::vector<std::string> additional_libs_vector = base::Split(additional_libs, ":");
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std::copy(additional_libs_vector.begin(),
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additional_libs_vector.end(),
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std::back_inserter(sonames));
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}
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}
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// This file is optional, quietly ignore if the file does not exist.
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ReadConfig(kPublicNativeLibrariesVendorConfig, &sonames);
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// android_init_namespaces() expects all the public libraries
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// to be loaded so that they can be found by soname alone.
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//
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// TODO(dimitry): this is a bit misleading since we do not know
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// if the vendor public library is going to be opened from /vendor/lib
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// we might as well end up loading them from /system/lib
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// For now we rely on CTS test to catch things like this but
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// it should probably be addressed in the future.
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for (const auto& soname : sonames) {
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dlopen(soname.c_str(), RTLD_NOW | RTLD_NODELETE);
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}
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public_libraries_ = base::Join(sonames, ':');
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}
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void Reset() {
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namespaces_.clear();
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}
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private:
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bool ReadConfig(const std::string& configFile, std::vector<std::string>* sonames) {
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// Read list of public native libraries from the config file.
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std::string file_content;
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if(!base::ReadFileToString(configFile, &file_content)) {
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return false;
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}
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std::vector<std::string> lines = base::Split(file_content, "\n");
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for (const auto& line : lines) {
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auto trimmed_line = base::Trim(line);
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if (trimmed_line[0] == '#' || trimmed_line.empty()) {
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continue;
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}
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sonames->push_back(trimmed_line);
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}
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return true;
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}
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bool InitPublicNamespace(const char* library_path) {
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// (http://b/25844435) - Some apps call dlopen from generated code (mono jited
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// code is one example) unknown to linker in which case linker uses anonymous
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// namespace. The second argument specifies the search path for the anonymous
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// namespace which is the library_path of the classloader.
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initialized_ = android_init_namespaces(public_libraries_.c_str(), library_path);
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return initialized_;
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}
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bool initialized_;
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std::vector<std::pair<jweak, android_namespace_t*>> namespaces_;
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std::string public_libraries_;
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DISALLOW_COPY_AND_ASSIGN(LibraryNamespaces);
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};
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static std::mutex g_namespaces_mutex;
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static LibraryNamespaces* g_namespaces = new LibraryNamespaces;
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#endif
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void InitializeNativeLoader() {
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#if defined(__ANDROID__)
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std::lock_guard<std::mutex> guard(g_namespaces_mutex);
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g_namespaces->Initialize();
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#endif
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}
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void ResetNativeLoader() {
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#if defined(__ANDROID__)
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std::lock_guard<std::mutex> guard(g_namespaces_mutex);
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g_namespaces->Reset();
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#endif
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}
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jstring CreateClassLoaderNamespace(JNIEnv* env,
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int32_t target_sdk_version,
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jobject class_loader,
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bool is_shared,
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jstring library_path,
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jstring permitted_path) {
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#if defined(__ANDROID__)
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UNUSED(target_sdk_version);
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std::lock_guard<std::mutex> guard(g_namespaces_mutex);
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android_namespace_t* ns = g_namespaces->Create(env,
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class_loader,
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is_shared,
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library_path,
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permitted_path);
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if (ns == nullptr) {
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return env->NewStringUTF(dlerror());
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}
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#else
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UNUSED(env, target_sdk_version, class_loader, is_shared,
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library_path, permitted_path);
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#endif
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return nullptr;
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}
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void* OpenNativeLibrary(JNIEnv* env,
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int32_t target_sdk_version,
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const char* path,
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jobject class_loader,
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jstring library_path) {
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#if defined(__ANDROID__)
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UNUSED(target_sdk_version);
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if (class_loader == nullptr) {
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return dlopen(path, RTLD_NOW);
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}
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std::lock_guard<std::mutex> guard(g_namespaces_mutex);
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android_namespace_t* ns = g_namespaces->FindNamespaceByClassLoader(env, class_loader);
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if (ns == nullptr) {
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// This is the case where the classloader was not created by ApplicationLoaders
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// In this case we create an isolated not-shared namespace for it.
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ns = g_namespaces->Create(env, class_loader, false, library_path, nullptr);
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if (ns == nullptr) {
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return nullptr;
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}
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}
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android_dlextinfo extinfo;
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extinfo.flags = ANDROID_DLEXT_USE_NAMESPACE;
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extinfo.library_namespace = ns;
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return android_dlopen_ext(path, RTLD_NOW, &extinfo);
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#else
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UNUSED(env, target_sdk_version, class_loader, library_path);
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return dlopen(path, RTLD_NOW);
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#endif
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}
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bool CloseNativeLibrary(void* handle) {
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return dlclose(handle) == 0;
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}
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#if defined(__ANDROID__)
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android_namespace_t* FindNamespaceByClassLoader(JNIEnv* env, jobject class_loader) {
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std::lock_guard<std::mutex> guard(g_namespaces_mutex);
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return g_namespaces->FindNamespaceByClassLoader(env, class_loader);
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}
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#endif
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}; // android namespace
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