1 /*
2 * Copyright (C) 2018 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 <linux/rtnetlink.h>
18 #include <net/if.h>
19
20 #include <array>
21 #include <cstdlib>
22 #include <iostream>
23 #include <sstream>
24 #include <string>
25
26 #include "android-base/logging.h"
27 #include <cutils/properties.h>
28 #include <gflags/gflags.h>
29
30 #include "common/libs/net/netlink_client.h"
31 #include "common/libs/net/netlink_request.h"
32 #include "common/libs/net/network_interface.h"
33 #include "common/libs/net/network_interface_manager.h"
34
35 DEFINE_string(mac_address, "", "mac address to use for wlan0");
36
str_to_mac(const std::string & mac_str)37 static std::array<unsigned char, 6> str_to_mac(const std::string& mac_str) {
38 std::array<unsigned char, 6> mac;
39 std::istringstream stream(mac_str);
40 for (int i = 0; i < 6; i++) {
41 int num;
42 stream >> std::hex >> num;
43 mac[i] = num;
44 stream.get();
45 }
46 return mac;
47 }
48
49 // TODO(schuffelen): Merge this with the ip_link_add binary.
CreateWifiWrapper(const std::string & source,const std::string & destination)50 int CreateWifiWrapper(const std::string& source,
51 const std::string& destination) {
52 auto factory = cuttlefish::NetlinkClientFactory::Default();
53 std::unique_ptr<cuttlefish::NetlinkClient> nl(factory->New(NETLINK_ROUTE));
54
55 LOG(INFO) << "Setting " << source << " mac address to " << FLAGS_mac_address;
56 int32_t index = if_nametoindex(source.c_str());
57 // Setting the address is available in RTM_SETLINK, but not RTM_NEWLINK.
58 // https://elixir.bootlin.com/linux/v5.4.44/source/net/core/rtnetlink.c#L2785
59 // https://elixir.bootlin.com/linux/v5.4.44/source/net/core/rtnetlink.c#L2460
60 // Setting the address seems to work better on the underlying ethernet device,
61 // and this mac address is inherited by the virt_wifi device.
62 cuttlefish::NetlinkRequest fix_mac_request(
63 RTM_SETLINK, NLM_F_REQUEST|NLM_F_ACK|0x600);
64 fix_mac_request.Append(ifinfomsg {
65 .ifi_index = index,
66 .ifi_change = 0xFFFFFFFF,
67 });
68 fix_mac_request.AddMacAddress(str_to_mac(FLAGS_mac_address));
69 bool fix_mac = nl->Send(fix_mac_request);
70 if (!fix_mac) {
71 LOG(ERROR) << "setup_network: could not fix mac address";
72 return -5;
73 }
74
75 // http://maz-programmersdiary.blogspot.com/2011/09/netlink-sockets.html
76 cuttlefish::NetlinkRequest link_add_request(RTM_NEWLINK,
77 NLM_F_REQUEST|NLM_F_ACK|0x600);
78 link_add_request.Append(ifinfomsg {
79 .ifi_change = 0xFFFFFFFF,
80 });
81 if (index == 0) {
82 LOG(ERROR) << "setup_network: invalid interface name '" << source << "'\n";
83 return -2;
84 }
85 link_add_request.AddString(IFLA_IFNAME, destination);
86 link_add_request.AddInt(IFLA_LINK, index);
87
88 link_add_request.PushList(IFLA_LINKINFO);
89 link_add_request.AddString(IFLA_INFO_KIND, "virt_wifi");
90 link_add_request.PushList(IFLA_INFO_DATA);
91 link_add_request.PopList();
92 link_add_request.PopList();
93
94 bool link_add_success = nl->Send(link_add_request);
95 if (!link_add_success) {
96 LOG(ERROR) << "setup_network: could not add link " << destination;
97 return -3;
98 }
99
100 cuttlefish::NetlinkRequest bring_up_backing_request(RTM_SETLINK,
101 NLM_F_REQUEST|NLM_F_ACK|0x600);
102 bring_up_backing_request.Append(ifinfomsg {
103 .ifi_index = index,
104 .ifi_flags = IFF_UP,
105 .ifi_change = 0xFFFFFFFF,
106 });
107
108 bool link_backing_up = nl->Send(bring_up_backing_request);
109 if (!link_backing_up) {
110 LOG(ERROR) << "setup_network: could not bring up backing " << source;
111 return -4;
112 }
113
114 return 0;
115 }
116
RenameNetwork(const std::string & name,const std::string & new_name)117 int RenameNetwork(const std::string& name, const std::string& new_name) {
118 static auto net_manager =
119 cuttlefish::NetworkInterfaceManager::New(cuttlefish::NetlinkClientFactory::Default());
120 auto connection = net_manager->Open(name, "ignore");
121 if (!connection) {
122 LOG(ERROR) << "setup_network: could not open " << name << " on device.";
123 return -1;
124 }
125 connection->SetName(new_name);
126 bool changes_applied = net_manager->ApplyChanges(*connection);
127 if (!changes_applied) {
128 LOG(ERROR) << "setup_network: can't rename " << name << " to " << new_name;
129 return -1;
130 }
131 return 0;
132 }
133
main(int argc,char ** argv)134 int main(int argc, char** argv) {
135 char wifi_address[PROPERTY_VALUE_MAX + 1];
136 property_get("ro.boot.wifi_mac_address", wifi_address, "");
137
138 SetCommandLineOptionWithMode("mac_address", wifi_address,
139 google::FlagSettingMode::SET_FLAGS_DEFAULT);
140
141 gflags::ParseCommandLineFlags(&argc, &argv, true);
142
143 int renamed_eth0 = RenameNetwork("eth0", "buried_eth0");
144 if (renamed_eth0 != 0) {
145 return renamed_eth0;
146 }
147 return CreateWifiWrapper("buried_eth0", "wlan0");
148 }
149