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      1 /*
      2  * Copyright (C) 2017 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 #include <errno.h>
     18 #include <error.h>
     19 #include <hidl/HidlSupport.h>
     20 #include <jni.h>
     21 #include <nativehelper/JNIHelp.h>
     22 #include <linux/netfilter/nfnetlink.h>
     23 #include <linux/netlink.h>
     24 #include <sys/socket.h>
     25 #include <android-base/unique_fd.h>
     26 #include <android/hardware/tetheroffload/config/1.0/IOffloadConfig.h>
     27 
     28 #define LOG_TAG "OffloadHardwareInterface"
     29 #include <utils/Log.h>
     30 
     31 namespace android {
     32 
     33 using hardware::hidl_handle;
     34 using hardware::hidl_string;
     35 using hardware::tetheroffload::config::V1_0::IOffloadConfig;
     36 
     37 namespace {
     38 
     39 inline const sockaddr * asSockaddr(const sockaddr_nl *nladdr) {
     40     return reinterpret_cast<const sockaddr *>(nladdr);
     41 }
     42 
     43 int conntrackSocket(unsigned groups) {
     44     base::unique_fd s(socket(AF_NETLINK, SOCK_DGRAM, NETLINK_NETFILTER));
     45     if (s.get() < 0) return -errno;
     46 
     47     const struct sockaddr_nl bind_addr = {
     48         .nl_family = AF_NETLINK,
     49         .nl_pad = 0,
     50         .nl_pid = 0,
     51         .nl_groups = groups,
     52     };
     53     if (bind(s.get(), asSockaddr(&bind_addr), sizeof(bind_addr)) != 0) {
     54         return -errno;
     55     }
     56 
     57     const struct sockaddr_nl kernel_addr = {
     58         .nl_family = AF_NETLINK,
     59         .nl_pad = 0,
     60         .nl_pid = 0,
     61         .nl_groups = groups,
     62     };
     63     if (connect(s.get(), asSockaddr(&kernel_addr), sizeof(kernel_addr)) != 0) {
     64         return -errno;
     65     }
     66 
     67     return s.release();
     68 }
     69 
     70 // Return a hidl_handle that owns the file descriptor owned by fd, and will
     71 // auto-close it (otherwise there would be double-close problems).
     72 //
     73 // Rely upon the compiler to eliminate the constexprs used for clarity.
     74 hidl_handle handleFromFileDescriptor(base::unique_fd fd) {
     75     hidl_handle h;
     76 
     77     static constexpr int kNumFds = 1;
     78     static constexpr int kNumInts = 0;
     79     native_handle_t *nh = native_handle_create(kNumFds, kNumInts);
     80     nh->data[0] = fd.release();
     81 
     82     static constexpr bool kTakeOwnership = true;
     83     h.setTo(nh, kTakeOwnership);
     84 
     85     return h;
     86 }
     87 
     88 }  // namespace
     89 
     90 static jboolean android_server_connectivity_tethering_OffloadHardwareInterface_configOffload(
     91         JNIEnv* /* env */) {
     92     sp<IOffloadConfig> configInterface = IOffloadConfig::getService();
     93     if (configInterface.get() == nullptr) {
     94         ALOGD("Could not find IOffloadConfig service.");
     95         return false;
     96     }
     97 
     98     // Per the IConfigOffload definition:
     99     //
    100     // fd1   A file descriptor bound to the following netlink groups
    101     //       (NF_NETLINK_CONNTRACK_NEW | NF_NETLINK_CONNTRACK_DESTROY).
    102     //
    103     // fd2   A file descriptor bound to the following netlink groups
    104     //       (NF_NETLINK_CONNTRACK_UPDATE | NF_NETLINK_CONNTRACK_DESTROY).
    105     base::unique_fd
    106             fd1(conntrackSocket(NF_NETLINK_CONNTRACK_NEW | NF_NETLINK_CONNTRACK_DESTROY)),
    107             fd2(conntrackSocket(NF_NETLINK_CONNTRACK_UPDATE | NF_NETLINK_CONNTRACK_DESTROY));
    108     if (fd1.get() < 0 || fd2.get() < 0) {
    109         ALOGE("Unable to create conntrack handles: %d/%s", errno, strerror(errno));
    110         return false;
    111     }
    112 
    113     hidl_handle h1(handleFromFileDescriptor(std::move(fd1))),
    114                 h2(handleFromFileDescriptor(std::move(fd2)));
    115 
    116     bool rval(false);
    117     hidl_string msg;
    118     const auto status = configInterface->setHandles(h1, h2,
    119             [&rval, &msg](bool success, const hidl_string& errMsg) {
    120                 rval = success;
    121                 msg = errMsg;
    122             });
    123     if (!status.isOk() || !rval) {
    124         ALOGE("IOffloadConfig::setHandles() error: '%s' / '%s'",
    125               status.description().c_str(), msg.c_str());
    126         // If status is somehow not ok, make sure rval captures this too.
    127         rval = false;
    128     }
    129 
    130     return rval;
    131 }
    132 
    133 /*
    134  * JNI registration.
    135  */
    136 static const JNINativeMethod gMethods[] = {
    137     /* name, signature, funcPtr */
    138     { "configOffload", "()Z",
    139       (void*) android_server_connectivity_tethering_OffloadHardwareInterface_configOffload },
    140 };
    141 
    142 int register_android_server_connectivity_tethering_OffloadHardwareInterface(JNIEnv* env) {
    143     return jniRegisterNativeMethods(env,
    144             "com/android/server/connectivity/tethering/OffloadHardwareInterface",
    145             gMethods, NELEM(gMethods));
    146 }
    147 
    148 }; // namespace android
    149