1 /*
2  * Copyright 2020, 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 #define LOG_TAG "NetworkUtils"
18 
19 #include <android/file_descriptor_jni.h>
20 #include <android/multinetwork.h>
21 #include <linux/filter.h>
22 #include <linux/tcp.h>
23 #include <netinet/in.h>
24 #include <string.h>
25 
26 #include <bpf/BpfClassic.h>
27 #include <bpf/KernelUtils.h>
28 #include <DnsProxydProtocol.h> // NETID_USE_LOCAL_NAMESERVERS
29 #include <nativehelper/JNIPlatformHelp.h>
30 #include <nativehelper/ScopedPrimitiveArray.h>
31 #include <utils/Log.h>
32 
33 #include "jni.h"
34 
35 #define NETUTILS_PKG_NAME "android/net/NetworkUtils"
36 
37 namespace android {
38 
39 constexpr int MAXPACKETSIZE = 8 * 1024;
40 // FrameworkListener limits the size of commands to 4096 bytes.
41 constexpr int MAXCMDSIZE = 4096;
42 
43 static volatile jclass class_Network = 0;
44 static volatile jmethodID method_fromNetworkHandle = 0;
45 
FindClassOrDie(JNIEnv * env,const char * class_name)46 static inline jclass FindClassOrDie(JNIEnv* env, const char* class_name) {
47     jclass clazz = env->FindClass(class_name);
48     LOG_ALWAYS_FATAL_IF(clazz == NULL, "Unable to find class %s", class_name);
49     return clazz;
50 }
51 
52 template <typename T>
MakeGlobalRefOrDie(JNIEnv * env,T in)53 static inline T MakeGlobalRefOrDie(JNIEnv* env, T in) {
54     jobject res = env->NewGlobalRef(in);
55     LOG_ALWAYS_FATAL_IF(res == NULL, "Unable to create global reference.");
56     return static_cast<T>(res);
57 }
58 
android_net_utils_attachDropAllBPFFilter(JNIEnv * env,jclass clazz,jobject javaFd)59 static void android_net_utils_attachDropAllBPFFilter(JNIEnv *env, jclass clazz, jobject javaFd)
60 {
61     static struct sock_filter filter_code[] = {
62         BPF_REJECT,
63     };
64     static const struct sock_fprog filter = {
65         sizeof(filter_code) / sizeof(filter_code[0]),
66         filter_code,
67     };
68 
69     int fd = AFileDescriptor_getFd(env, javaFd);
70     if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)) != 0) {
71         jniThrowExceptionFmt(env, "java/net/SocketException",
72                 "setsockopt(SO_ATTACH_FILTER): %s", strerror(errno));
73     }
74 }
75 
android_net_utils_detachBPFFilter(JNIEnv * env,jclass clazz,jobject javaFd)76 static void android_net_utils_detachBPFFilter(JNIEnv *env, jclass clazz, jobject javaFd)
77 {
78     int optval_ignored = 0;
79     int fd = AFileDescriptor_getFd(env, javaFd);
80     if (setsockopt(fd, SOL_SOCKET, SO_DETACH_FILTER, &optval_ignored, sizeof(optval_ignored)) !=
81         0) {
82         jniThrowExceptionFmt(env, "java/net/SocketException",
83                 "setsockopt(SO_DETACH_FILTER): %s", strerror(errno));
84     }
85 }
86 
android_net_utils_bindProcessToNetworkHandle(JNIEnv * env,jclass clazz,jlong netHandle)87 static jboolean android_net_utils_bindProcessToNetworkHandle(JNIEnv *env, jclass clazz,
88         jlong netHandle)
89 {
90     return (jboolean) !android_setprocnetwork(netHandle);
91 }
92 
android_net_utils_getBoundNetworkHandleForProcess(JNIEnv * env,jclass clazz)93 static jlong android_net_utils_getBoundNetworkHandleForProcess(JNIEnv *env, jclass clazz)
94 {
95     net_handle_t network;
96     if (android_getprocnetwork(&network) != 0) {
97         jniThrowExceptionFmt(env, "java/lang/IllegalStateException",
98                 "android_getprocnetwork(): %s", strerror(errno));
99         return NETWORK_UNSPECIFIED;
100     }
101     return (jlong) network;
102 }
103 
android_net_utils_bindProcessToNetworkForHostResolution(JNIEnv * env,jclass clazz,jint netId,jlong netHandle)104 static jboolean android_net_utils_bindProcessToNetworkForHostResolution(JNIEnv *env, jclass clazz,
105         jint netId, jlong netHandle)
106 {
107     return (jboolean) !android_setprocdns(netHandle);
108 }
109 
android_net_utils_bindSocketToNetworkHandle(JNIEnv * env,jclass clazz,jobject javaFd,jlong netHandle)110 static jint android_net_utils_bindSocketToNetworkHandle(JNIEnv *env, jclass clazz, jobject javaFd,
111                                                   jlong netHandle) {
112     return android_setsocknetwork(netHandle, AFileDescriptor_getFd(env, javaFd));
113 }
114 
checkLenAndCopy(JNIEnv * env,const jbyteArray & addr,int len,void * dst)115 static bool checkLenAndCopy(JNIEnv* env, const jbyteArray& addr, int len, void* dst)
116 {
117     if (env->GetArrayLength(addr) != len) {
118         return false;
119     }
120     env->GetByteArrayRegion(addr, 0, len, reinterpret_cast<jbyte*>(dst));
121     return true;
122 }
123 
android_net_utils_resNetworkQuery(JNIEnv * env,jclass clazz,jlong netHandle,jstring dname,jint ns_class,jint ns_type,jint flags)124 static jobject android_net_utils_resNetworkQuery(JNIEnv *env, jclass clazz, jlong netHandle,
125         jstring dname, jint ns_class, jint ns_type, jint flags) {
126     const jsize javaCharsCount = env->GetStringLength(dname);
127     const jsize byteCountUTF8 = env->GetStringUTFLength(dname);
128 
129     // Only allow dname which could be simply formatted to UTF8.
130     // In native layer, res_mkquery would re-format the input char array to packet.
131     char queryname[byteCountUTF8 + 1];
132     memset(queryname, 0, (byteCountUTF8 + 1) * sizeof(char));
133 
134     env->GetStringUTFRegion(dname, 0, javaCharsCount, queryname);
135     int fd = android_res_nquery(netHandle, queryname, ns_class, ns_type, flags);
136 
137     if (fd < 0) {
138         jniThrowErrnoException(env, "resNetworkQuery", -fd);
139         return nullptr;
140     }
141 
142     return jniCreateFileDescriptor(env, fd);
143 }
144 
android_net_utils_resNetworkSend(JNIEnv * env,jclass clazz,jlong netHandle,jbyteArray msg,jint msgLen,jint flags)145 static jobject android_net_utils_resNetworkSend(JNIEnv *env, jclass clazz, jlong netHandle,
146         jbyteArray msg, jint msgLen, jint flags) {
147     uint8_t data[MAXCMDSIZE];
148 
149     checkLenAndCopy(env, msg, msgLen, data);
150     int fd = android_res_nsend(netHandle, data, msgLen, flags);
151 
152     if (fd < 0) {
153         jniThrowErrnoException(env, "resNetworkSend", -fd);
154         return nullptr;
155     }
156 
157     return jniCreateFileDescriptor(env, fd);
158 }
159 
android_net_utils_resNetworkResult(JNIEnv * env,jclass clazz,jobject javaFd)160 static jobject android_net_utils_resNetworkResult(JNIEnv *env, jclass clazz, jobject javaFd) {
161     int fd = AFileDescriptor_getFd(env, javaFd);
162     int rcode;
163     uint8_t buf[MAXPACKETSIZE] = {0};
164 
165     int res = android_res_nresult(fd, &rcode, buf, MAXPACKETSIZE);
166     jniSetFileDescriptorOfFD(env, javaFd, -1);
167     if (res < 0) {
168         jniThrowErrnoException(env, "resNetworkResult", -res);
169         return nullptr;
170     }
171 
172     jbyteArray answer = env->NewByteArray(res);
173     if (answer == nullptr) {
174         jniThrowErrnoException(env, "resNetworkResult", ENOMEM);
175         return nullptr;
176     } else {
177         env->SetByteArrayRegion(answer, 0, res, reinterpret_cast<jbyte*>(buf));
178     }
179 
180     jclass class_DnsResponse = env->FindClass("android/net/DnsResolver$DnsResponse");
181     jmethodID ctor = env->GetMethodID(class_DnsResponse, "<init>", "([BI)V");
182 
183     return env->NewObject(class_DnsResponse, ctor, answer, rcode);
184 }
185 
android_net_utils_resNetworkCancel(JNIEnv * env,jclass clazz,jobject javaFd)186 static void android_net_utils_resNetworkCancel(JNIEnv *env, jclass clazz, jobject javaFd) {
187     int fd = AFileDescriptor_getFd(env, javaFd);
188     android_res_cancel(fd);
189     jniSetFileDescriptorOfFD(env, javaFd, -1);
190 }
191 
android_net_utils_getDnsNetwork(JNIEnv * env,jclass clazz)192 static jobject android_net_utils_getDnsNetwork(JNIEnv *env, jclass clazz) {
193     net_handle_t dnsNetHandle = NETWORK_UNSPECIFIED;
194     if (int res = android_getprocdns(&dnsNetHandle) < 0) {
195         jniThrowErrnoException(env, "getDnsNetwork", -res);
196         return nullptr;
197     }
198 
199     if (method_fromNetworkHandle == 0) {
200         // This may be called multiple times concurrently but that is fine
201         class_Network = MakeGlobalRefOrDie(env, FindClassOrDie(env, "android/net/Network"));
202         method_fromNetworkHandle = env->GetStaticMethodID(class_Network, "fromNetworkHandle",
203                 "(J)Landroid/net/Network;");
204     }
205     return env->CallStaticObjectMethod(class_Network, method_fromNetworkHandle,
206             static_cast<jlong>(dnsNetHandle));
207 }
208 
android_net_utils_getTcpRepairWindow(JNIEnv * env,jclass clazz,jobject javaFd)209 static jobject android_net_utils_getTcpRepairWindow(JNIEnv *env, jclass clazz, jobject javaFd) {
210     if (javaFd == NULL) {
211         jniThrowNullPointerException(env, NULL);
212         return NULL;
213     }
214 
215     int fd = AFileDescriptor_getFd(env, javaFd);
216     struct tcp_repair_window trw = {};
217     socklen_t size = sizeof(trw);
218 
219     // Obtain the parameters of the TCP repair window.
220     int rc = getsockopt(fd, IPPROTO_TCP, TCP_REPAIR_WINDOW, &trw, &size);
221     if (rc == -1) {
222         jniThrowErrnoException(env, "getsockopt : TCP_REPAIR_WINDOW", errno);
223         return NULL;
224     }
225 
226     struct tcp_info tcpinfo = {};
227     socklen_t tcpinfo_size = sizeof(tcp_info);
228 
229     // Obtain the window scale from the tcp info structure. This contains a scale factor that
230     // should be applied to the window size.
231     rc = getsockopt(fd, IPPROTO_TCP, TCP_INFO, &tcpinfo, &tcpinfo_size);
232     if (rc == -1) {
233         jniThrowErrnoException(env, "getsockopt : TCP_INFO", errno);
234         return NULL;
235     }
236 
237     jclass class_TcpRepairWindow = env->FindClass(
238         "android/net/connectivity/android/net/TcpRepairWindow");
239     jmethodID ctor = env->GetMethodID(class_TcpRepairWindow, "<init>", "(IIIIII)V");
240 
241     return env->NewObject(class_TcpRepairWindow, ctor, trw.snd_wl1, trw.snd_wnd, trw.max_window,
242             trw.rcv_wnd, trw.rcv_wup, tcpinfo.tcpi_rcv_wscale);
243 }
244 
android_net_utils_setsockoptBytes(JNIEnv * env,jclass clazz,jobject javaFd,jint level,jint option,jbyteArray javaBytes)245 static void android_net_utils_setsockoptBytes(JNIEnv *env, jclass clazz, jobject javaFd,
246         jint level, jint option, jbyteArray javaBytes) {
247     int sock = AFileDescriptor_getFd(env, javaFd);
248     ScopedByteArrayRO value(env, javaBytes);
249     if (setsockopt(sock, level, option, value.get(), value.size()) != 0) {
250         jniThrowErrnoException(env, "setsockoptBytes", errno);
251     }
252 }
253 
android_net_utils_isKernel64Bit(JNIEnv * env,jclass clazz)254 static jboolean android_net_utils_isKernel64Bit(JNIEnv *env, jclass clazz) {
255     return bpf::isKernel64Bit();
256 }
257 
android_net_utils_isKernelX86(JNIEnv * env,jclass clazz)258 static jboolean android_net_utils_isKernelX86(JNIEnv *env, jclass clazz) {
259     return bpf::isX86();
260 }
261 
262 // ----------------------------------------------------------------------------
263 
264 /*
265  * JNI registration.
266  */
267 // clang-format off
268 static const JNINativeMethod gNetworkUtilMethods[] = {
269     /* name, signature, funcPtr */
270     { "bindProcessToNetworkHandle", "(J)Z", (void*) android_net_utils_bindProcessToNetworkHandle },
271     { "getBoundNetworkHandleForProcess", "()J", (void*) android_net_utils_getBoundNetworkHandleForProcess },
272     { "bindProcessToNetworkForHostResolution", "(I)Z", (void*) android_net_utils_bindProcessToNetworkForHostResolution },
273     { "bindSocketToNetworkHandle", "(Ljava/io/FileDescriptor;J)I", (void*) android_net_utils_bindSocketToNetworkHandle },
274     { "attachDropAllBPFFilter", "(Ljava/io/FileDescriptor;)V", (void*) android_net_utils_attachDropAllBPFFilter },
275     { "detachBPFFilter", "(Ljava/io/FileDescriptor;)V", (void*) android_net_utils_detachBPFFilter },
276     { "getTcpRepairWindow", "(Ljava/io/FileDescriptor;)Landroid/net/connectivity/android/net/TcpRepairWindow;", (void*) android_net_utils_getTcpRepairWindow },
277     { "resNetworkSend", "(J[BII)Ljava/io/FileDescriptor;", (void*) android_net_utils_resNetworkSend },
278     { "resNetworkQuery", "(JLjava/lang/String;III)Ljava/io/FileDescriptor;", (void*) android_net_utils_resNetworkQuery },
279     { "resNetworkResult", "(Ljava/io/FileDescriptor;)Landroid/net/DnsResolver$DnsResponse;", (void*) android_net_utils_resNetworkResult },
280     { "resNetworkCancel", "(Ljava/io/FileDescriptor;)V", (void*) android_net_utils_resNetworkCancel },
281     { "getDnsNetwork", "()Landroid/net/Network;", (void*) android_net_utils_getDnsNetwork },
282     { "setsockoptBytes", "(Ljava/io/FileDescriptor;II[B)V",
283     (void*) android_net_utils_setsockoptBytes},
284     { "isKernel64Bit", "()Z", (void*) android_net_utils_isKernel64Bit },
285     { "isKernelX86", "()Z", (void*) android_net_utils_isKernelX86 },
286 };
287 // clang-format on
288 
register_android_net_NetworkUtils(JNIEnv * env)289 int register_android_net_NetworkUtils(JNIEnv* env)
290 {
291     return jniRegisterNativeMethods(env, NETUTILS_PKG_NAME, gNetworkUtilMethods,
292                                     NELEM(gNetworkUtilMethods));
293 }
294 
295 }; // namespace android
296