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1 /*
2  * Copyright (C) 2012 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 <dirent.h>
18 
19 #define LOG_TAG "InterfaceController"
20 #include <cutils/log.h>
21 #include <logwrap/logwrap.h>
22 
23 #include "InterfaceController.h"
24 #include "RouteController.h"
25 
26 const char ipv6_proc_path[] = "/proc/sys/net/ipv6/conf";
27 
28 const char sys_net_path[] = "/sys/class/net";
29 
30 const char wl_util_path[] = "/system/xbin/wlutil";
31 
InterfaceController()32 InterfaceController::InterfaceController() {
33 	// Initial IPv6 settings.
34 	// By default, accept_ra is set to 1 (accept RAs unless forwarding is on) on all interfaces.
35 	// This causes RAs to work or not work based on whether forwarding is on, and causes routes
36 	// learned from RAs to go away when forwarding is turned on. Make this behaviour predictable
37 	// by always setting accept_ra to 2.
38 	setAcceptRA("2");
39 
40 	setAcceptRARouteTable(-RouteController::ROUTE_TABLE_OFFSET_FROM_INDEX);
41 
42 	// Enable optimistic DAD for IPv6 addresses on all interfaces.
43 	setIPv6OptimisticMode("1");
44 }
45 
~InterfaceController()46 InterfaceController::~InterfaceController() {
47 }
48 
writeIPv6ProcPath(const char * interface,const char * setting,const char * value)49 int InterfaceController::writeIPv6ProcPath(const char *interface, const char *setting, const char *value) {
50 	char *path;
51 	if (!isIfaceName(interface)) {
52 		errno = ENOENT;
53 		return -1;
54 	}
55 	asprintf(&path, "%s/%s/%s", ipv6_proc_path, interface, setting);
56 	int success = writeFile(path, value, strlen(value));
57 	free(path);
58 	return success;
59 }
60 
setEnableIPv6(const char * interface,const int on)61 int InterfaceController::setEnableIPv6(const char *interface, const int on) {
62 	// When disable_ipv6 changes from 1 to 0, the kernel starts autoconf.
63 	// When disable_ipv6 changes from 0 to 1, the kernel clears all autoconf
64 	// addresses and routes and disables IPv6 on the interface.
65 	const char *disable_ipv6 = on ? "0" : "1";
66 	return writeIPv6ProcPath(interface, "disable_ipv6", disable_ipv6);
67 }
68 
setIPv6PrivacyExtensions(const char * interface,const int on)69 int InterfaceController::setIPv6PrivacyExtensions(const char *interface, const int on) {
70 	// 0: disable IPv6 privacy addresses
71 	// 0: enable IPv6 privacy addresses and prefer them over non-privacy ones.
72 	return writeIPv6ProcPath(interface, "use_tempaddr", on ? "2" : "0");
73 }
74 
75 // Enables or disables IPv6 ND offload. This is useful for 464xlat on wifi, IPv6 tethering, and
76 // generally implementing IPv6 neighbour discovery and duplicate address detection properly.
77 // TODO: This should be implemented in wpa_supplicant via driver commands instead.
setIPv6NdOffload(char * interface,const int on)78 int InterfaceController::setIPv6NdOffload(char* interface, const int on) {
79     // Only supported on Broadcom chipsets via wlutil for now.
80     if (access(wl_util_path, X_OK) == 0) {
81         const char *argv[] = {
82             wl_util_path,
83             "-a",
84             interface,
85             "ndoe",
86             on ? "1" : "0"
87         };
88         int ret = android_fork_execvp(ARRAY_SIZE(argv), const_cast<char**>(argv), NULL,
89                                       false, false);
90         ALOGD("%s ND offload on %s: %d (%s)",
91               (on ? "enabling" : "disabling"), interface, ret, strerror(errno));
92         return ret;
93     } else {
94         return 0;
95     }
96 }
97 
isInterfaceName(const char * name)98 int InterfaceController::isInterfaceName(const char *name) {
99 	return strcmp(name, ".") &&
100 		strcmp(name, "..") &&
101 		strcmp(name, "default") &&
102 		strcmp(name, "all");
103 }
104 
setOnAllInterfaces(const char * filename,const char * value)105 void InterfaceController::setOnAllInterfaces(const char* filename, const char* value) {
106 	// Set the default value, which is used by any interfaces that are created in the future.
107 	writeIPv6ProcPath("default", filename, value);
108 
109 	// Set the value on all the interfaces that currently exist.
110 	DIR* dir = opendir(ipv6_proc_path);
111 	if (!dir) {
112 		ALOGE("Can't list %s: %s", ipv6_proc_path, strerror(errno));
113 		return;
114 	}
115 	dirent* d;
116 	while ((d = readdir(dir))) {
117 		if (d->d_type == DT_DIR && isInterfaceName(d->d_name)) {
118 			writeIPv6ProcPath(d->d_name, filename, value);
119 		}
120 	}
121 	closedir(dir);
122 }
123 
setAcceptRA(const char * value)124 void InterfaceController::setAcceptRA(const char *value) {
125 	setOnAllInterfaces("accept_ra", value);
126 }
127 
128 // |tableOrOffset| is interpreted as:
129 //     If == 0: default. Routes go into RT6_TABLE_MAIN.
130 //     If > 0: user set. Routes go into the specified table.
131 //     If < 0: automatic. The absolute value is intepreted as an offset and added to the interface
132 //             ID to get the table. If it's set to -1000, routes from interface ID 5 will go into
133 //             table 1005, etc.
setAcceptRARouteTable(int tableOrOffset)134 void InterfaceController::setAcceptRARouteTable(int tableOrOffset) {
135 	char* value;
136 	asprintf(&value, "%d", tableOrOffset);
137 	setOnAllInterfaces("accept_ra_rt_table", value);
138 	free(value);
139 }
140 
setMtu(const char * interface,const char * mtu)141 int InterfaceController::setMtu(const char *interface, const char *mtu)
142 {
143 	char *path;
144 	if (!isIfaceName(interface)) {
145 		errno = ENOENT;
146 		return -1;
147 	}
148 	asprintf(&path, "%s/%s/mtu", sys_net_path, interface);
149 	int success = writeFile(path, mtu, strlen(mtu));
150 	free(path);
151 	return success;
152 }
153 
setIPv6OptimisticMode(const char * value)154 void InterfaceController::setIPv6OptimisticMode(const char *value) {
155 	setOnAllInterfaces("optimistic_dad", value);
156 	setOnAllInterfaces("use_optimistic", value);
157 }
158