1/*
2 * Copyright (C) 2014 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// Uncomment for verbose logging.
18// #define LOG_NDEBUG 0
19#define LOG_TAG "webviewchromiumloader"
20
21#include <dlfcn.h>
22#include <errno.h>
23#include <fcntl.h>
24#include <stdio.h>
25#include <stdlib.h>
26#include <string.h>
27#include <unistd.h>
28#include <sys/mman.h>
29#include <sys/stat.h>
30#include <sys/types.h>
31
32#include <jni.h>
33#include <android/dlext.h>
34#include <utils/Log.h>
35
36#define NELEM(x) ((int) (sizeof(x) / sizeof((x)[0])))
37
38namespace android {
39namespace {
40
41void* gReservedAddress = NULL;
42size_t gReservedSize = 0;
43
44jboolean DoReserveAddressSpace(jlong size) {
45  size_t vsize = static_cast<size_t>(size);
46
47  void* addr = mmap(NULL, vsize, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
48  if (addr == MAP_FAILED) {
49    ALOGE("Failed to reserve %zd bytes of address space for future load of "
50          "libwebviewchromium.so: %s",
51          vsize, strerror(errno));
52    return JNI_FALSE;
53  }
54  gReservedAddress = addr;
55  gReservedSize = vsize;
56  ALOGV("Reserved %zd bytes at %p", vsize, addr);
57  return JNI_TRUE;
58}
59
60jboolean DoCreateRelroFile(const char* lib, const char* relro) {
61  // Try to unlink the old file, since if this is being called, the old one is
62  // obsolete.
63  if (unlink(relro) != 0 && errno != ENOENT) {
64    // If something went wrong other than the file not existing, log a warning
65    // but continue anyway in the hope that we can successfully overwrite the
66    // existing file with rename() later.
67    ALOGW("Failed to unlink old file %s: %s", relro, strerror(errno));
68  }
69  static const char tmpsuffix[] = ".XXXXXX";
70  char relro_tmp[strlen(relro) + sizeof(tmpsuffix)];
71  strlcpy(relro_tmp, relro, sizeof(relro_tmp));
72  strlcat(relro_tmp, tmpsuffix, sizeof(relro_tmp));
73  int tmp_fd = TEMP_FAILURE_RETRY(mkstemp(relro_tmp));
74  if (tmp_fd == -1) {
75    ALOGE("Failed to create temporary file %s: %s", relro_tmp, strerror(errno));
76    return JNI_FALSE;
77  }
78  android_dlextinfo extinfo;
79  extinfo.flags = ANDROID_DLEXT_RESERVED_ADDRESS | ANDROID_DLEXT_WRITE_RELRO;
80  extinfo.reserved_addr = gReservedAddress;
81  extinfo.reserved_size = gReservedSize;
82  extinfo.relro_fd = tmp_fd;
83  void* handle = android_dlopen_ext(lib, RTLD_NOW, &extinfo);
84  int close_result = close(tmp_fd);
85  if (handle == NULL) {
86    ALOGE("Failed to load library %s: %s", lib, dlerror());
87    unlink(relro_tmp);
88    return JNI_FALSE;
89  }
90  if (close_result != 0 ||
91      chmod(relro_tmp, S_IRUSR | S_IRGRP | S_IROTH) != 0 ||
92      rename(relro_tmp, relro) != 0) {
93    ALOGE("Failed to update relro file %s: %s", relro, strerror(errno));
94    unlink(relro_tmp);
95    return JNI_FALSE;
96  }
97  ALOGV("Created relro file %s for library %s", relro, lib);
98  return JNI_TRUE;
99}
100
101jboolean DoLoadWithRelroFile(const char* lib, const char* relro) {
102  int relro_fd = TEMP_FAILURE_RETRY(open(relro, O_RDONLY));
103  if (relro_fd == -1) {
104    ALOGE("Failed to open relro file %s: %s", relro, strerror(errno));
105    return JNI_FALSE;
106  }
107  android_dlextinfo extinfo;
108  extinfo.flags = ANDROID_DLEXT_RESERVED_ADDRESS | ANDROID_DLEXT_USE_RELRO;
109  extinfo.reserved_addr = gReservedAddress;
110  extinfo.reserved_size = gReservedSize;
111  extinfo.relro_fd = relro_fd;
112  void* handle = android_dlopen_ext(lib, RTLD_NOW, &extinfo);
113  close(relro_fd);
114  if (handle == NULL) {
115    ALOGE("Failed to load library %s: %s", lib, dlerror());
116    return JNI_FALSE;
117  }
118  ALOGV("Loaded library %s with relro file %s", lib, relro);
119  return JNI_TRUE;
120}
121
122/******************************************************************************/
123/* JNI wrappers - handle string lifetimes and 32/64 ABI choice                */
124/******************************************************************************/
125
126jboolean ReserveAddressSpace(JNIEnv*, jclass, jlong size) {
127  return DoReserveAddressSpace(size);
128}
129
130jboolean CreateRelroFile(JNIEnv* env, jclass, jstring lib32, jstring lib64,
131                         jstring relro32, jstring relro64) {
132#ifdef __LP64__
133  jstring lib = lib64;
134  jstring relro = relro64;
135  (void)lib32; (void)relro32;
136#else
137  jstring lib = lib32;
138  jstring relro = relro32;
139  (void)lib64; (void)relro64;
140#endif
141  jboolean ret = JNI_FALSE;
142  const char* lib_utf8 = env->GetStringUTFChars(lib, NULL);
143  if (lib_utf8 != NULL) {
144    const char* relro_utf8 = env->GetStringUTFChars(relro, NULL);
145    if (relro_utf8 != NULL) {
146      ret = DoCreateRelroFile(lib_utf8, relro_utf8);
147      env->ReleaseStringUTFChars(relro, relro_utf8);
148    }
149    env->ReleaseStringUTFChars(lib, lib_utf8);
150  }
151  return ret;
152}
153
154jboolean LoadWithRelroFile(JNIEnv* env, jclass, jstring lib32, jstring lib64,
155                           jstring relro32, jstring relro64) {
156#ifdef __LP64__
157  jstring lib = lib64;
158  jstring relro = relro64;
159  (void)lib32; (void)relro32;
160#else
161  jstring lib = lib32;
162  jstring relro = relro32;
163  (void)lib64; (void)relro64;
164#endif
165  jboolean ret = JNI_FALSE;
166  const char* lib_utf8 = env->GetStringUTFChars(lib, NULL);
167  if (lib_utf8 != NULL) {
168    const char* relro_utf8 = env->GetStringUTFChars(relro, NULL);
169    if (relro_utf8 != NULL) {
170      ret = DoLoadWithRelroFile(lib_utf8, relro_utf8);
171      env->ReleaseStringUTFChars(relro, relro_utf8);
172    }
173    env->ReleaseStringUTFChars(lib, lib_utf8);
174  }
175  return ret;
176}
177
178const char kClassName[] = "android/webkit/WebViewFactory";
179const JNINativeMethod kJniMethods[] = {
180  { "nativeReserveAddressSpace", "(J)Z",
181      reinterpret_cast<void*>(ReserveAddressSpace) },
182  { "nativeCreateRelroFile",
183      "(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)Z",
184      reinterpret_cast<void*>(CreateRelroFile) },
185  { "nativeLoadWithRelroFile",
186      "(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)Z",
187      reinterpret_cast<void*>(LoadWithRelroFile) },
188};
189
190}  // namespace
191
192void RegisterWebViewFactory(JNIEnv* env) {
193  // If either of these fail, it will set an exception that will be thrown on
194  // return, so no need to handle errors here.
195  jclass clazz = env->FindClass(kClassName);
196  if (clazz) {
197    env->RegisterNatives(clazz, kJniMethods, NELEM(kJniMethods));
198  }
199}
200
201}  // namespace android
202
203JNIEXPORT jint JNI_OnLoad(JavaVM* vm, void*) {
204  JNIEnv* env = NULL;
205  if (vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6) != JNI_OK) {
206    ALOGE("GetEnv failed");
207    return JNI_ERR;
208  }
209  android::RegisterWebViewFactory(env);
210  return JNI_VERSION_1_6;
211}
212