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/*
* Copyright (C) 2017 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.
*/
#include <errno.h>
#include <error.h>
#include <jni.h>
#include <linux/filter.h>
#include <nativehelper/JNIHelp.h>
#include <nativehelper/JNIHelpCompat.h>
#include <nativehelper/ScopedUtfChars.h>
#include <net/if.h>
#include <netinet/ether.h>
#include <netinet/ip6.h>
#include <netinet/icmp6.h>
#include <sys/socket.h>
#include <stdio.h>
#define LOG_TAG "TetheringUtils"
#include <android/log.h>
namespace android {
static const uint32_t kIPv6NextHeaderOffset = offsetof(ip6_hdr, ip6_nxt);
static const uint32_t kIPv6PayloadStart = sizeof(ip6_hdr);
static const uint32_t kICMPv6TypeOffset = kIPv6PayloadStart + offsetof(icmp6_hdr, icmp6_type);
static void android_net_util_setupIcmpFilter(JNIEnv *env, jobject javaFd, uint32_t type) {
sock_filter filter_code[] = {
// Check header is ICMPv6.
BPF_STMT(BPF_LD | BPF_B | BPF_ABS, kIPv6NextHeaderOffset),
BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, IPPROTO_ICMPV6, 0, 3),
// Check ICMPv6 type.
BPF_STMT(BPF_LD | BPF_B | BPF_ABS, kICMPv6TypeOffset),
BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, type, 0, 1),
// Accept or reject.
BPF_STMT(BPF_RET | BPF_K, 0xffff),
BPF_STMT(BPF_RET | BPF_K, 0)
};
const sock_fprog filter = {
sizeof(filter_code) / sizeof(filter_code[0]),
filter_code,
};
int fd = jniGetFDFromFileDescriptor(env, javaFd);
if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)) != 0) {
jniThrowExceptionFmt(env, "java/net/SocketException",
"setsockopt(SO_ATTACH_FILTER): %s", strerror(errno));
}
}
static void android_net_util_setupNaSocket(JNIEnv *env, jobject clazz, jobject javaFd)
{
android_net_util_setupIcmpFilter(env, javaFd, ND_NEIGHBOR_ADVERT);
}
static void android_net_util_setupNsSocket(JNIEnv *env, jobject clazz, jobject javaFd)
{
android_net_util_setupIcmpFilter(env, javaFd, ND_NEIGHBOR_SOLICIT);
}
static void android_net_util_setupRaSocket(JNIEnv *env, jobject clazz, jobject javaFd,
jint ifIndex)
{
static const int kLinkLocalHopLimit = 255;
int fd = jniGetFDFromFileDescriptor(env, javaFd);
// Set an ICMPv6 filter that only passes Router Solicitations.
struct icmp6_filter rs_only;
ICMP6_FILTER_SETBLOCKALL(&rs_only);
ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &rs_only);
socklen_t len = sizeof(rs_only);
if (setsockopt(fd, IPPROTO_ICMPV6, ICMP6_FILTER, &rs_only, len) != 0) {
jniThrowExceptionFmt(env, "java/net/SocketException",
"setsockopt(ICMP6_FILTER): %s", strerror(errno));
return;
}
// Most/all of the rest of these options can be set via Java code, but
// because we're here on account of setting an icmp6_filter go ahead
// and do it all natively for now.
// Set the multicast hoplimit to 255 (link-local only).
int hops = kLinkLocalHopLimit;
len = sizeof(hops);
if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &hops, len) != 0) {
jniThrowExceptionFmt(env, "java/net/SocketException",
"setsockopt(IPV6_MULTICAST_HOPS): %s", strerror(errno));
return;
}
// Set the unicast hoplimit to 255 (link-local only).
hops = kLinkLocalHopLimit;
len = sizeof(hops);
if (setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &hops, len) != 0) {
jniThrowExceptionFmt(env, "java/net/SocketException",
"setsockopt(IPV6_UNICAST_HOPS): %s", strerror(errno));
return;
}
// Explicitly disable multicast loopback.
int off = 0;
len = sizeof(off);
if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &off, len) != 0) {
jniThrowExceptionFmt(env, "java/net/SocketException",
"setsockopt(IPV6_MULTICAST_LOOP): %s", strerror(errno));
return;
}
// Specify the IPv6 interface to use for outbound multicast.
len = sizeof(ifIndex);
if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_IF, &ifIndex, len) != 0) {
jniThrowExceptionFmt(env, "java/net/SocketException",
"setsockopt(IPV6_MULTICAST_IF): %s", strerror(errno));
return;
}
// Additional options to be considered:
// - IPV6_TCLASS
// - IPV6_RECVPKTINFO
// - IPV6_RECVHOPLIMIT
// Bind to [::].
const struct sockaddr_in6 sin6 = {
.sin6_family = AF_INET6,
.sin6_port = 0,
.sin6_flowinfo = 0,
.sin6_addr = IN6ADDR_ANY_INIT,
.sin6_scope_id = 0,
};
auto sa = reinterpret_cast<const struct sockaddr *>(&sin6);
len = sizeof(sin6);
if (bind(fd, sa, len) != 0) {
jniThrowExceptionFmt(env, "java/net/SocketException",
"bind(IN6ADDR_ANY): %s", strerror(errno));
return;
}
// Join the all-routers multicast group, ff02::2%index.
struct ipv6_mreq all_rtrs = {
.ipv6mr_multiaddr = {{{0xff,2,0,0,0,0,0,0,0,0,0,0,0,0,0,2}}},
.ipv6mr_interface = ifIndex,
};
len = sizeof(all_rtrs);
if (setsockopt(fd, IPPROTO_IPV6, IPV6_JOIN_GROUP, &all_rtrs, len) != 0) {
jniThrowExceptionFmt(env, "java/net/SocketException",
"setsockopt(IPV6_JOIN_GROUP): %s", strerror(errno));
return;
}
}
/*
* JNI registration.
*/
static const JNINativeMethod gMethods[] = {
/* name, signature, funcPtr */
{ "setupNaSocket", "(Ljava/io/FileDescriptor;)V",
(void*) android_net_util_setupNaSocket },
{ "setupNsSocket", "(Ljava/io/FileDescriptor;)V",
(void*) android_net_util_setupNsSocket },
{ "setupRaSocket", "(Ljava/io/FileDescriptor;I)V",
(void*) android_net_util_setupRaSocket },
};
int register_android_net_util_TetheringUtils(JNIEnv* env) {
return jniRegisterNativeMethods(env,
"android/net/util/TetheringUtils",
gMethods, NELEM(gMethods));
}
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 (register_android_net_util_TetheringUtils(env) < 0) {
return JNI_ERR;
}
return JNI_VERSION_1_6;
}
}; // namespace android
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