native_loader.cpp revision fcd4ee48a4f29c3271e4a3d0f5174f9d6a7042c9 
1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "nativeloader/native_loader.h"
18#include "ScopedUtfChars.h"
19
20#include <dlfcn.h>
21#ifdef __ANDROID__
22#include "dlext_namespaces.h"
23#include "cutils/properties.h"
24#define LOG_TAG "libnativeloader"
25#include "log/log.h"
26#endif
27
28#include <algorithm>
29#include <vector>
30#include <string>
31#include <mutex>
32
33#include "android-base/file.h"
34#include "android-base/macros.h"
35#include "android-base/strings.h"
36
37namespace android {
38
39#if defined(__ANDROID__)
40static constexpr const char* kPublicNativeLibrariesSystemConfigPathFromRoot = "/etc/public.libraries.txt";
41static constexpr const char* kPublicNativeLibrariesVendorConfig = "/vendor/etc/public.libraries.txt";
42
43// (http://b/27588281) This is a workaround for apps using custom classloaders and calling
44// System.load() with an absolute path which is outside of the classloader library search path.
45// This list includes all directories app is allowed to access this way.
46static constexpr const char* kWhitelistedDirectories = "/data:/mnt/expand";
47
48static bool is_debuggable() {
49  char debuggable[PROP_VALUE_MAX];
50  property_get("ro.debuggable", debuggable, "0");
51  return std::string(debuggable) == "1";
52}
53
54class LibraryNamespaces {
55 public:
56  LibraryNamespaces() : initialized_(false) { }
57
58  android_namespace_t* Create(JNIEnv* env,
59                              jobject class_loader,
60                              bool is_shared,
61                              jstring java_library_path,
62                              jstring java_permitted_path) {
63    std::string library_path; // empty string by default.
64
65    if (java_library_path != nullptr) {
66      ScopedUtfChars library_path_utf_chars(env, java_library_path);
67      library_path = library_path_utf_chars.c_str();
68    }
69
70    // (http://b/27588281) This is a workaround for apps using custom
71    // classloaders and calling System.load() with an absolute path which
72    // is outside of the classloader library search path.
73    //
74    // This part effectively allows such a classloader to access anything
75    // under /data and /mnt/expand
76    std::string permitted_path = kWhitelistedDirectories;
77
78    if (java_permitted_path != nullptr) {
79      ScopedUtfChars path(env, java_permitted_path);
80      if (path.c_str() != nullptr && path.size() > 0) {
81        permitted_path = permitted_path + ":" + path.c_str();
82      }
83    }
84
85    if (!initialized_ && !InitPublicNamespace(library_path.c_str())) {
86      return nullptr;
87    }
88
89    android_namespace_t* ns = FindNamespaceByClassLoader(env, class_loader);
90
91    LOG_ALWAYS_FATAL_IF(ns != nullptr,
92                        "There is already a namespace associated with this classloader");
93
94    uint64_t namespace_type = ANDROID_NAMESPACE_TYPE_ISOLATED;
95    if (is_shared) {
96      namespace_type |= ANDROID_NAMESPACE_TYPE_SHARED;
97    }
98
99    android_namespace_t* parent_ns = FindParentNamespaceByClassLoader(env, class_loader);
100
101    ns = android_create_namespace("classloader-namespace",
102                                  nullptr,
103                                  library_path.c_str(),
104                                  namespace_type,
105                                  permitted_path.c_str(),
106                                  parent_ns);
107
108    if (ns != nullptr) {
109      namespaces_.push_back(std::make_pair(env->NewWeakGlobalRef(class_loader), ns));
110    }
111
112    return ns;
113  }
114
115  android_namespace_t* FindNamespaceByClassLoader(JNIEnv* env, jobject class_loader) {
116    auto it = std::find_if(namespaces_.begin(), namespaces_.end(),
117                [&](const std::pair<jweak, android_namespace_t*>& value) {
118                  return env->IsSameObject(value.first, class_loader);
119                });
120    return it != namespaces_.end() ? it->second : nullptr;
121  }
122
123  void Initialize() {
124    // Once public namespace is initialized there is no
125    // point in running this code - it will have no effect
126    // on the current list of public libraries.
127    if (initialized_) {
128      return;
129    }
130
131    std::vector<std::string> sonames;
132    const char* android_root_env = getenv("ANDROID_ROOT");
133    std::string root_dir = android_root_env != nullptr ? android_root_env : "/system";
134    std::string public_native_libraries_system_config =
135            root_dir + kPublicNativeLibrariesSystemConfigPathFromRoot;
136
137    LOG_ALWAYS_FATAL_IF(!ReadConfig(public_native_libraries_system_config, &sonames),
138                        "Error reading public native library list from \"%s\": %s",
139                        public_native_libraries_system_config.c_str(), strerror(errno));
140
141    // For debuggable platform builds use ANDROID_ADDITIONAL_PUBLIC_LIBRARIES environment
142    // variable to add libraries to the list. This is intended for platform tests only.
143    if (is_debuggable()) {
144      const char* additional_libs = getenv("ANDROID_ADDITIONAL_PUBLIC_LIBRARIES");
145      if (additional_libs != nullptr && additional_libs[0] != '\0') {
146        std::vector<std::string> additional_libs_vector = base::Split(additional_libs, ":");
147        std::copy(additional_libs_vector.begin(),
148                  additional_libs_vector.end(),
149                  std::back_inserter(sonames));
150      }
151    }
152
153    // This file is optional, quietly ignore if the file does not exist.
154    ReadConfig(kPublicNativeLibrariesVendorConfig, &sonames);
155
156    // android_init_namespaces() expects all the public libraries
157    // to be loaded so that they can be found by soname alone.
158    //
159    // TODO(dimitry): this is a bit misleading since we do not know
160    // if the vendor public library is going to be opened from /vendor/lib
161    // we might as well end up loading them from /system/lib
162    // For now we rely on CTS test to catch things like this but
163    // it should probably be addressed in the future.
164    for (const auto& soname : sonames) {
165      dlopen(soname.c_str(), RTLD_NOW | RTLD_NODELETE);
166    }
167
168    public_libraries_ = base::Join(sonames, ':');
169  }
170
171  void Reset() {
172    namespaces_.clear();
173  }
174
175 private:
176  bool ReadConfig(const std::string& configFile, std::vector<std::string>* sonames) {
177    // Read list of public native libraries from the config file.
178    std::string file_content;
179    if(!base::ReadFileToString(configFile, &file_content)) {
180      return false;
181    }
182
183    std::vector<std::string> lines = base::Split(file_content, "\n");
184
185    for (const auto& line : lines) {
186      auto trimmed_line = base::Trim(line);
187      if (trimmed_line[0] == '#' || trimmed_line.empty()) {
188        continue;
189      }
190
191      sonames->push_back(trimmed_line);
192    }
193
194    return true;
195  }
196
197  bool InitPublicNamespace(const char* library_path) {
198    // (http://b/25844435) - Some apps call dlopen from generated code (mono jited
199    // code is one example) unknown to linker in which  case linker uses anonymous
200    // namespace. The second argument specifies the search path for the anonymous
201    // namespace which is the library_path of the classloader.
202    initialized_ = android_init_namespaces(public_libraries_.c_str(), library_path);
203
204    return initialized_;
205  }
206
207  jobject GetParentClassLoader(JNIEnv* env, jobject class_loader) {
208    jclass class_loader_class = env->FindClass("java/lang/ClassLoader");
209    jmethodID get_parent = env->GetMethodID(class_loader_class,
210                                            "getParent",
211                                            "()Ljava/lang/ClassLoader;");
212
213    return env->CallObjectMethod(class_loader, get_parent);
214  }
215
216  android_namespace_t* FindParentNamespaceByClassLoader(JNIEnv* env, jobject class_loader) {
217    jobject parent_class_loader = GetParentClassLoader(env, class_loader);
218
219    while (parent_class_loader != nullptr) {
220      android_namespace_t* ns = FindNamespaceByClassLoader(env, parent_class_loader);
221      if (ns != nullptr) {
222        return ns;
223      }
224
225      parent_class_loader = GetParentClassLoader(env, parent_class_loader);
226    }
227    return nullptr;
228  }
229
230  bool initialized_;
231  std::vector<std::pair<jweak, android_namespace_t*>> namespaces_;
232  std::string public_libraries_;
233
234
235  DISALLOW_COPY_AND_ASSIGN(LibraryNamespaces);
236};
237
238static std::mutex g_namespaces_mutex;
239static LibraryNamespaces* g_namespaces = new LibraryNamespaces;
240#endif
241
242void InitializeNativeLoader() {
243#if defined(__ANDROID__)
244  std::lock_guard<std::mutex> guard(g_namespaces_mutex);
245  g_namespaces->Initialize();
246#endif
247}
248
249void ResetNativeLoader() {
250#if defined(__ANDROID__)
251  std::lock_guard<std::mutex> guard(g_namespaces_mutex);
252  g_namespaces->Reset();
253#endif
254}
255
256jstring CreateClassLoaderNamespace(JNIEnv* env,
257                                   int32_t target_sdk_version,
258                                   jobject class_loader,
259                                   bool is_shared,
260                                   jstring library_path,
261                                   jstring permitted_path) {
262#if defined(__ANDROID__)
263  UNUSED(target_sdk_version);
264  std::lock_guard<std::mutex> guard(g_namespaces_mutex);
265  android_namespace_t* ns = g_namespaces->Create(env,
266                                                 class_loader,
267                                                 is_shared,
268                                                 library_path,
269                                                 permitted_path);
270  if (ns == nullptr) {
271    return env->NewStringUTF(dlerror());
272  }
273#else
274  UNUSED(env, target_sdk_version, class_loader, is_shared,
275         library_path, permitted_path);
276#endif
277  return nullptr;
278}
279
280void* OpenNativeLibrary(JNIEnv* env,
281                        int32_t target_sdk_version,
282                        const char* path,
283                        jobject class_loader,
284                        jstring library_path) {
285#if defined(__ANDROID__)
286  UNUSED(target_sdk_version);
287  if (class_loader == nullptr) {
288    return dlopen(path, RTLD_NOW);
289  }
290
291  std::lock_guard<std::mutex> guard(g_namespaces_mutex);
292  android_namespace_t* ns = g_namespaces->FindNamespaceByClassLoader(env, class_loader);
293
294  if (ns == nullptr) {
295    // This is the case where the classloader was not created by ApplicationLoaders
296    // In this case we create an isolated not-shared namespace for it.
297    ns = g_namespaces->Create(env, class_loader, false, library_path, nullptr);
298    if (ns == nullptr) {
299      return nullptr;
300    }
301  }
302
303  android_dlextinfo extinfo;
304  extinfo.flags = ANDROID_DLEXT_USE_NAMESPACE;
305  extinfo.library_namespace = ns;
306
307  return android_dlopen_ext(path, RTLD_NOW, &extinfo);
308#else
309  UNUSED(env, target_sdk_version, class_loader, library_path);
310  return dlopen(path, RTLD_NOW);
311#endif
312}
313
314bool CloseNativeLibrary(void* handle) {
315  return dlclose(handle) == 0;
316}
317
318#if defined(__ANDROID__)
319android_namespace_t* FindNamespaceByClassLoader(JNIEnv* env, jobject class_loader) {
320  std::lock_guard<std::mutex> guard(g_namespaces_mutex);
321  return g_namespaces->FindNamespaceByClassLoader(env, class_loader);
322}
323#endif
324
325}; //  android namespace
326