1 /*
2 device.c -- Interaction with Linux ethertap and tun/tap device
3 Copyright (C) 2001-2005 Ivo Timmermans,
4 2001-2014 Guus Sliepen <guus@tinc-vpn.org>
5
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License along
17 with this program; if not, write to the Free Software Foundation, Inc.,
18 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
19 */
20
21 #include "../system.h"
22
23 #ifdef HAVE_LINUX_IF_TUN_H
24 #include <linux/if_tun.h>
25 #define DEFAULT_DEVICE "/dev/net/tun"
26 #else
27 #define DEFAULT_DEVICE "/dev/tap0"
28 #endif
29
30 #include "../conf.h"
31 #include "../device.h"
32 #include "../logger.h"
33 #include "../net.h"
34 #include "../route.h"
35 #include "../utils.h"
36 #include "../xalloc.h"
37
38 typedef enum device_type_t {
39 DEVICE_TYPE_ETHERTAP,
40 DEVICE_TYPE_TUN,
41 DEVICE_TYPE_TAP,
42 } device_type_t;
43
44 int device_fd = -1;
45 static device_type_t device_type;
46 char *device = NULL;
47 char *iface = NULL;
48 static char *type = NULL;
49 static char ifrname[IFNAMSIZ];
50 static const char *device_info;
51
52 static uint64_t device_total_in = 0;
53 static uint64_t device_total_out = 0;
54
setup_device(void)55 static bool setup_device(void) {
56 struct ifreq ifr;
57 bool t1q = false;
58
59 if(!get_config_string(lookup_config(config_tree, "Device"), &device)) {
60 device = xstrdup(DEFAULT_DEVICE);
61 }
62
63 if(!get_config_string(lookup_config(config_tree, "Interface"), &iface))
64 #ifdef HAVE_LINUX_IF_TUN_H
65 if(netname != NULL) {
66 iface = xstrdup(netname);
67 }
68
69 #else
70 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
71 #endif
72 device_fd = open(device, O_RDWR | O_NONBLOCK);
73
74 if(device_fd < 0) {
75 logger(LOG_ERR, "Could not open %s: %s", device, strerror(errno));
76 return false;
77 }
78
79 #ifdef FD_CLOEXEC
80 fcntl(device_fd, F_SETFD, FD_CLOEXEC);
81 #endif
82
83 #ifdef HAVE_LINUX_IF_TUN_H
84 /* Ok now check if this is an old ethertap or a new tun/tap thingie */
85
86 memset(&ifr, 0, sizeof(ifr));
87
88 get_config_string(lookup_config(config_tree, "DeviceType"), &type);
89
90 if(type && strcasecmp(type, "tun") && strcasecmp(type, "tap")) {
91 logger(LOG_ERR, "Unknown device type %s!", type);
92 return false;
93 }
94
95 if((type && !strcasecmp(type, "tun")) || (!type && routing_mode == RMODE_ROUTER)) {
96 ifr.ifr_flags = IFF_TUN;
97 device_type = DEVICE_TYPE_TUN;
98 device_info = "Linux tun/tap device (tun mode)";
99 } else {
100 if(routing_mode == RMODE_ROUTER) {
101 overwrite_mac = true;
102 }
103
104 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
105 device_type = DEVICE_TYPE_TAP;
106 device_info = "Linux tun/tap device (tap mode)";
107 }
108
109 #ifdef IFF_ONE_QUEUE
110
111 /* Set IFF_ONE_QUEUE flag... */
112 if(get_config_bool(lookup_config(config_tree, "IffOneQueue"), &t1q) && t1q) {
113 ifr.ifr_flags |= IFF_ONE_QUEUE;
114 }
115
116 #endif
117
118 if(iface) {
119 strncpy(ifr.ifr_name, iface, IFNAMSIZ);
120 ifr.ifr_name[IFNAMSIZ - 1] = 0;
121 }
122
123 if(!ioctl(device_fd, TUNSETIFF, &ifr)) {
124 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
125 ifrname[IFNAMSIZ - 1] = 0;
126 free(iface);
127 iface = xstrdup(ifrname);
128 } else if(errno == EPERM || errno == EBUSY) {
129 logger(LOG_ERR, "Error while trying to configure %s: %s", device, strerror(errno));
130 return false;
131 } else if(!ioctl(device_fd, (('T' << 8) | 202), &ifr)) {
132 logger(LOG_WARNING, "Old ioctl() request was needed for %s", device);
133 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
134 ifrname[IFNAMSIZ - 1] = 0;
135 free(iface);
136 iface = xstrdup(ifrname);
137 } else
138 #endif
139 {
140 if(routing_mode == RMODE_ROUTER) {
141 overwrite_mac = true;
142 }
143
144 device_info = "Linux ethertap device";
145 device_type = DEVICE_TYPE_ETHERTAP;
146 free(iface);
147 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
148 }
149
150 if(overwrite_mac && !ioctl(device_fd, SIOCGIFHWADDR, &ifr)) {
151 memcpy(mymac.x, ifr.ifr_hwaddr.sa_data, ETH_ALEN);
152 }
153
154 logger(LOG_INFO, "%s is a %s", device, device_info);
155
156 return true;
157 }
158
close_device(void)159 static void close_device(void) {
160 close(device_fd);
161
162 free(type);
163 free(device);
164 free(iface);
165 }
166
read_packet(vpn_packet_t * packet)167 static bool read_packet(vpn_packet_t *packet) {
168 int lenin;
169
170 switch(device_type) {
171 case DEVICE_TYPE_TUN:
172 lenin = read(device_fd, packet->data + 10, MTU - 10);
173
174 if(lenin <= 0) {
175 logger(LOG_ERR, "Error while reading from %s %s: %s",
176 device_info, device, strerror(errno));
177 return false;
178 }
179
180 memset(packet->data, 0, 12);
181 packet->len = lenin + 10;
182 break;
183
184 case DEVICE_TYPE_TAP:
185 lenin = read(device_fd, packet->data, MTU);
186
187 if(lenin <= 0) {
188 logger(LOG_ERR, "Error while reading from %s %s: %s",
189 device_info, device, strerror(errno));
190 return false;
191 }
192
193 packet->len = lenin;
194 break;
195
196 case DEVICE_TYPE_ETHERTAP:
197 lenin = read(device_fd, packet->data - 2, MTU + 2);
198
199 if(lenin <= 0) {
200 logger(LOG_ERR, "Error while reading from %s %s: %s",
201 device_info, device, strerror(errno));
202 return false;
203 }
204
205 packet->len = lenin - 2;
206 break;
207 }
208
209 device_total_in += packet->len;
210
211 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Read packet of %d bytes from %s", packet->len,
212 device_info);
213
214 return true;
215 }
216
write_packet(vpn_packet_t * packet)217 static bool write_packet(vpn_packet_t *packet) {
218 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Writing packet of %d bytes to %s",
219 packet->len, device_info);
220
221 switch(device_type) {
222 case DEVICE_TYPE_TUN:
223 packet->data[10] = packet->data[11] = 0;
224
225 if(write(device_fd, packet->data + 10, packet->len - 10) < 0) {
226 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
227 strerror(errno));
228 return false;
229 }
230
231 break;
232
233 case DEVICE_TYPE_TAP:
234 if(write(device_fd, packet->data, packet->len) < 0) {
235 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
236 strerror(errno));
237 return false;
238 }
239
240 break;
241
242 case DEVICE_TYPE_ETHERTAP:
243 memcpy(packet->data - 2, &packet->len, 2);
244
245 if(write(device_fd, packet->data - 2, packet->len + 2) < 0) {
246 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
247 strerror(errno));
248 return false;
249 }
250
251 break;
252 }
253
254 device_total_out += packet->len;
255
256 return true;
257 }
258
dump_device_stats(void)259 static void dump_device_stats(void) {
260 logger(LOG_DEBUG, "Statistics for %s %s:", device_info, device);
261 logger(LOG_DEBUG, " total bytes in: %10"PRIu64, device_total_in);
262 logger(LOG_DEBUG, " total bytes out: %10"PRIu64, device_total_out);
263 }
264
265 const devops_t os_devops = {
266 .setup = setup_device,
267 .close = close_device,
268 .read = read_packet,
269 .write = write_packet,
270 .dump_stats = dump_device_stats,
271 };
272