| /* |
| * Copyright 2019, The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #define LOG_TAG "NetworkStackUtils-JNI" |
| |
| #include <dlfcn.h> |
| #include <errno.h> |
| #include <jni.h> |
| #include <linux/filter.h> |
| #include <linux/if_arp.h> |
| #include <net/if.h> |
| #include <netinet/ether.h> |
| #include <netinet/icmp6.h> |
| #include <netinet/ip.h> |
| #include <netinet/ip6.h> |
| #include <netinet/udp.h> |
| #include <stdlib.h> |
| #include <sys/system_properties.h> |
| |
| #include <string> |
| |
| #include <nativehelper/JNIHelp.h> |
| #include <netjniutils/netjniutils.h> |
| |
| #include <android/log.h> |
| #include <bpf/BpfClassic.h> |
| |
| namespace android { |
| constexpr const char NETWORKSTACKUTILS_PKG_NAME[] = |
| "com/android/networkstack/util/NetworkStackUtils"; |
| |
| static const uint16_t kDhcpClientPort = 68; |
| |
| static bool checkLenAndCopy(JNIEnv* env, const jbyteArray& addr, int len, void* dst) { |
| if (env->GetArrayLength(addr) != len) { |
| return false; |
| } |
| env->GetByteArrayRegion(addr, 0, len, reinterpret_cast<jbyte*>(dst)); |
| return true; |
| } |
| |
| static void network_stack_utils_addArpEntry(JNIEnv *env, jclass clazz, jbyteArray ethAddr, |
| jbyteArray ipv4Addr, jstring ifname, jobject javaFd) { |
| arpreq req = {}; |
| sockaddr_in& netAddrStruct = *reinterpret_cast<sockaddr_in*>(&req.arp_pa); |
| sockaddr& ethAddrStruct = req.arp_ha; |
| |
| ethAddrStruct.sa_family = ARPHRD_ETHER; |
| if (!checkLenAndCopy(env, ethAddr, ETH_ALEN, ethAddrStruct.sa_data)) { |
| jniThrowException(env, "java/io/IOException", "Invalid ethAddr length"); |
| return; |
| } |
| |
| netAddrStruct.sin_family = AF_INET; |
| if (!checkLenAndCopy(env, ipv4Addr, sizeof(in_addr), &netAddrStruct.sin_addr)) { |
| jniThrowException(env, "java/io/IOException", "Invalid ipv4Addr length"); |
| return; |
| } |
| |
| int ifLen = env->GetStringLength(ifname); |
| // IFNAMSIZ includes the terminating NULL character |
| if (ifLen >= IFNAMSIZ) { |
| jniThrowException(env, "java/io/IOException", "ifname too long"); |
| return; |
| } |
| env->GetStringUTFRegion(ifname, 0, ifLen, req.arp_dev); |
| |
| req.arp_flags = ATF_COM; // Completed entry (ha valid) |
| int fd = netjniutils::GetNativeFileDescriptor(env, javaFd); |
| if (fd < 0) { |
| jniThrowExceptionFmt(env, "java/io/IOException", "Invalid file descriptor"); |
| return; |
| } |
| // See also: man 7 arp |
| if (ioctl(fd, SIOCSARP, &req)) { |
| jniThrowExceptionFmt(env, "java/io/IOException", "ioctl error: %s", strerror(errno)); |
| return; |
| } |
| } |
| |
| // fd is a "socket(AF_PACKET, SOCK_RAW, ETH_P_IP)" |
| // which guarantees packets already have skb->protocol == htons(ETH_P_IP) |
| static void network_stack_utils_attachDhcpFilter(JNIEnv *env, jclass clazz, jobject javaFd) { |
| static sock_filter filter_code[] = { |
| // Check the protocol is UDP. |
| BPF_LOAD_IPV4_U8(protocol), |
| BPF2_REJECT_IF_NOT_EQUAL(IPPROTO_UDP), |
| |
| // Check this is not a fragment. |
| BPF_LOAD_IPV4_BE16(frag_off), |
| BPF2_REJECT_IF_ANY_MASKED_BITS_SET(IP_MF | IP_OFFMASK), |
| |
| // Get the IP header length. |
| BPF_LOADX_NET_RELATIVE_IPV4_HLEN, |
| |
| // Check the destination port. |
| BPF_LOAD_NETX_RELATIVE_DST_PORT, |
| BPF2_REJECT_IF_NOT_EQUAL(kDhcpClientPort), |
| |
| BPF_ACCEPT, |
| }; |
| const sock_fprog filter = { |
| sizeof(filter_code) / sizeof(filter_code[0]), |
| filter_code, |
| }; |
| |
| int fd = netjniutils::GetNativeFileDescriptor(env, javaFd); |
| if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)) != 0) { |
| jniThrowErrnoException(env, "setsockopt(SO_ATTACH_FILTER)", errno); |
| } |
| } |
| |
| // fd is a "socket(AF_PACKET, SOCK_RAW, ETH_P_IPV6)" |
| // which guarantees packets already have skb->protocol == htons(ETH_P_IPV6) |
| static void network_stack_utils_attachRaFilter(JNIEnv *env, jclass clazz, jobject javaFd) { |
| static sock_filter filter_code[] = { |
| BPF_LOADX_CONSTANT_IPV6_HLEN, |
| |
| // Check IPv6 Next Header is ICMPv6. |
| BPF_LOAD_IPV6_U8(nexthdr), |
| BPF2_REJECT_IF_NOT_EQUAL(IPPROTO_ICMPV6), |
| |
| // Check ICMPv6 type is Router Advertisement. |
| BPF_LOAD_NETX_RELATIVE_ICMP_TYPE, |
| BPF2_REJECT_IF_NOT_EQUAL(ND_ROUTER_ADVERT), |
| |
| BPF_ACCEPT, |
| }; |
| static const sock_fprog filter = { |
| sizeof(filter_code) / sizeof(filter_code[0]), |
| filter_code, |
| }; |
| |
| int fd = netjniutils::GetNativeFileDescriptor(env, javaFd); |
| if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)) != 0) { |
| jniThrowErrnoException(env, "setsockopt(SO_ATTACH_FILTER)", errno); |
| } |
| } |
| |
| // TODO: Move all this filter code into libnetutils. |
| // fd is a "socket(AF_PACKET, SOCK_RAW, ETH_P_ALL)" |
| static void network_stack_utils_attachControlPacketFilter( |
| JNIEnv *env, jclass clazz, jobject javaFd) { |
| // Capture all: |
| // - ARPs |
| // - DHCPv4 packets |
| // - Router Advertisements & Solicitations |
| // - Neighbor Advertisements & Solicitations |
| // |
| // tcpdump: |
| // arp or |
| // '(ip and udp port 68)' or |
| // '(icmp6 and ip6[40] >= 133 and ip6[40] <= 136)' |
| static sock_filter filter_code[] = { |
| // Load the ethertype from skb->protocol |
| BPF_LOAD_SKB_PROTOCOL, |
| |
| // Accept all ARP. |
| // TODO: Figure out how to better filter ARPs on noisy networks. |
| BPF2_ACCEPT_IF_EQUAL(ETHERTYPE_ARP), |
| |
| // If IPv4: (otherwise jump to the 'IPv6 ...' below) |
| BPF_JUMP_IF_NOT_EQUAL(ETHERTYPE_IP, 14), |
| |
| // Check the protocol is UDP. |
| BPF_LOAD_IPV4_U8(protocol), |
| BPF2_REJECT_IF_NOT_EQUAL(IPPROTO_UDP), |
| |
| // Check this is not a fragment. |
| BPF_LOAD_IPV4_BE16(frag_off), |
| BPF2_REJECT_IF_ANY_MASKED_BITS_SET(IP_MF | IP_OFFMASK), |
| |
| // Get the IP header length. |
| BPF_LOADX_NET_RELATIVE_IPV4_HLEN, |
| |
| // Check the source port. |
| BPF_LOAD_NETX_RELATIVE_SRC_PORT, |
| BPF2_ACCEPT_IF_EQUAL(kDhcpClientPort), |
| |
| // Check the destination port. |
| BPF_LOAD_NETX_RELATIVE_DST_PORT, |
| BPF2_ACCEPT_IF_EQUAL(kDhcpClientPort), |
| |
| // Reject any other UDPv4 |
| BPF_REJECT, |
| |
| // IPv6 ... |
| BPF2_REJECT_IF_NOT_EQUAL(ETHERTYPE_IPV6), |
| // Assume standard, 40-byte, extension header-less ipv6 packet |
| BPF_LOADX_CONSTANT_IPV6_HLEN, |
| // ... check IPv6 Next Header is ICMPv6 (ignore fragments), ... |
| BPF_LOAD_IPV6_U8(nexthdr), |
| BPF2_REJECT_IF_NOT_EQUAL(IPPROTO_ICMPV6), |
| // ... and check the ICMPv6 type is one of RS/RA/NS/NA. |
| BPF_LOAD_NETX_RELATIVE_ICMP_TYPE, |
| BPF3_REJECT_IF_NOT_IN_RANGE(ND_ROUTER_SOLICIT, ND_NEIGHBOR_ADVERT), |
| |
| BPF_ACCEPT, |
| }; |
| static const sock_fprog filter = { |
| sizeof(filter_code) / sizeof(filter_code[0]), |
| filter_code, |
| }; |
| |
| int fd = netjniutils::GetNativeFileDescriptor(env, javaFd); |
| if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)) != 0) { |
| jniThrowErrnoException(env, "setsockopt(SO_ATTACH_FILTER)", errno); |
| } |
| } |
| |
| /* |
| * JNI registration. |
| */ |
| static const JNINativeMethod gNetworkStackUtilsMethods[] = { |
| /* name, signature, funcPtr */ |
| { "addArpEntry", "([B[BLjava/lang/String;Ljava/io/FileDescriptor;)V", (void*) network_stack_utils_addArpEntry }, |
| { "attachDhcpFilter", "(Ljava/io/FileDescriptor;)V", (void*) network_stack_utils_attachDhcpFilter }, |
| { "attachRaFilter", "(Ljava/io/FileDescriptor;)V", (void*) network_stack_utils_attachRaFilter }, |
| { "attachControlPacketFilter", "(Ljava/io/FileDescriptor;)V", (void*) network_stack_utils_attachControlPacketFilter }, |
| }; |
| |
| extern "C" jint JNI_OnLoad(JavaVM* vm, void*) { |
| JNIEnv *env; |
| if (vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6) != JNI_OK) { |
| __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "ERROR: GetEnv failed"); |
| return JNI_ERR; |
| } |
| |
| if (jniRegisterNativeMethods(env, NETWORKSTACKUTILS_PKG_NAME, |
| gNetworkStackUtilsMethods, NELEM(gNetworkStackUtilsMethods)) < 0) { |
| return JNI_ERR; |
| } |
| |
| return JNI_VERSION_1_6; |
| |
| } |
| }; // namespace android |