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
38 namespace android {
39 namespace {
40
41 void* gReservedAddress = NULL;
42 size_t gReservedSize = 0;
43
DoReserveAddressSpace(jlong size)44 jboolean 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
DoCreateRelroFile(const char * lib,const char * relro)60 jboolean 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
DoLoadWithRelroFile(const char * lib,const char * relro)101 jboolean 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
ReserveAddressSpace(JNIEnv *,jclass,jlong size)126 jboolean ReserveAddressSpace(JNIEnv*, jclass, jlong size) {
127 return DoReserveAddressSpace(size);
128 }
129
CreateRelroFile(JNIEnv * env,jclass,jstring lib32,jstring lib64,jstring relro32,jstring relro64)130 jboolean 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
LoadWithRelroFile(JNIEnv * env,jclass,jstring lib32,jstring lib64,jstring relro32,jstring relro64)154 jboolean 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
178 const char kClassName[] = "android/webkit/WebViewFactory";
179 const 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
RegisterWebViewFactory(JNIEnv * env)192 void 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
JNI_OnLoad(JavaVM * vm,void *)203 JNIEXPORT 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