1 /*
2 * iptunnel.c "ip tuntap"
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 *
9 * Authors: David Woodhouse <David.Woodhouse@intel.com>
10 *
11 */
12
13 #include <stdio.h>
14 #include <stdlib.h>
15 #include <string.h>
16 #include <unistd.h>
17 #include <sys/types.h>
18 #include <sys/socket.h>
19 #include <arpa/inet.h>
20 #include <sys/ioctl.h>
21 #include <linux/if.h>
22 #include <linux/if_tun.h>
23 #include <pwd.h>
24 #include <grp.h>
25 #include <fcntl.h>
26 #include <dirent.h>
27 #include <errno.h>
28
29 #include "rt_names.h"
30 #include "utils.h"
31 #include "ip_common.h"
32
33 #define TUNDEV "/dev/net/tun"
34
35 static void usage(void) __attribute__((noreturn));
36
usage(void)37 static void usage(void)
38 {
39 fprintf(stderr, "Usage: ip tuntap { add | del } [ dev PHYS_DEV ] \n");
40 fprintf(stderr, " [ mode { tun | tap } ] [ user USER ] [ group GROUP ]\n");
41 fprintf(stderr, " [ one_queue ] [ pi ] [ vnet_hdr ]\n");
42 fprintf(stderr, "\n");
43 fprintf(stderr, "Where: USER := { STRING | NUMBER }\n");
44 fprintf(stderr, " GROUP := { STRING | NUMBER }\n");
45 exit(-1);
46 }
47
tap_add_ioctl(struct ifreq * ifr,uid_t uid,gid_t gid)48 static int tap_add_ioctl(struct ifreq *ifr, uid_t uid, gid_t gid)
49 {
50 int fd = open(TUNDEV, O_RDWR);
51 int ret = -1;
52
53 #ifdef IFF_TUN_EXCL
54 ifr->ifr_flags |= IFF_TUN_EXCL;
55 #endif
56
57 fd = open(TUNDEV, O_RDWR);
58 if (fd < 0) {
59 perror("open");
60 return -1;
61 }
62 if (ioctl(fd, TUNSETIFF, ifr)) {
63 perror("ioctl(TUNSETIFF)");
64 goto out;
65 }
66 if (uid != -1 && ioctl(fd, TUNSETOWNER, uid)) {
67 perror("ioctl(TUNSETOWNER)");
68 goto out;
69 }
70 if (gid != -1 && ioctl(fd, TUNSETGROUP, gid)) {
71 perror("ioctl(TUNSETGROUP)");
72 goto out;
73 }
74 if (ioctl(fd, TUNSETPERSIST, 1)) {
75 perror("ioctl(TUNSETPERSIST)");
76 goto out;
77 }
78 ret = 0;
79 out:
80 close(fd);
81 return ret;
82 }
83
tap_del_ioctl(struct ifreq * ifr)84 static int tap_del_ioctl(struct ifreq *ifr)
85 {
86 int fd = open(TUNDEV, O_RDWR);
87 int ret = -1;
88
89 if (fd < 0) {
90 perror("open");
91 return -1;
92 }
93 if (ioctl(fd, TUNSETIFF, ifr)) {
94 perror("ioctl(TUNSETIFF)");
95 goto out;
96 }
97 if (ioctl(fd, TUNSETPERSIST, 0)) {
98 perror("ioctl(TUNSETPERSIST)");
99 goto out;
100 }
101 ret = 0;
102 out:
103 close(fd);
104 return ret;
105
106 }
parse_args(int argc,char ** argv,struct ifreq * ifr,uid_t * uid,gid_t * gid)107 static int parse_args(int argc, char **argv, struct ifreq *ifr, uid_t *uid, gid_t *gid)
108 {
109 int count = 0;
110
111 memset(ifr, 0, sizeof(*ifr));
112
113 ifr->ifr_flags |= IFF_NO_PI;
114
115 while (argc > 0) {
116 if (matches(*argv, "mode") == 0) {
117 NEXT_ARG();
118 if (matches(*argv, "tun") == 0) {
119 if (ifr->ifr_flags & IFF_TAP) {
120 fprintf(stderr,"You managed to ask for more than one tunnel mode.\n");
121 exit(-1);
122 }
123 ifr->ifr_flags |= IFF_TUN;
124 } else if (matches(*argv, "tap") == 0) {
125 if (ifr->ifr_flags & IFF_TUN) {
126 fprintf(stderr,"You managed to ask for more than one tunnel mode.\n");
127 exit(-1);
128 }
129 ifr->ifr_flags |= IFF_TAP;
130 } else {
131 fprintf(stderr,"Cannot guess tunnel mode.\n");
132 exit(-1);
133 }
134 } else if (uid && matches(*argv, "user") == 0) {
135 char *end;
136 unsigned long user;
137
138 NEXT_ARG();
139 if (**argv && ((user = strtol(*argv, &end, 10)), !*end))
140 *uid = user;
141 else {
142 struct passwd *pw = getpwnam(*argv);
143 if (!pw) {
144 fprintf(stderr, "invalid user \"%s\"\n", *argv);
145 exit(-1);
146 }
147 *uid = pw->pw_uid;
148 }
149 } else if (gid && matches(*argv, "group") == 0) {
150 char *end;
151 unsigned long group;
152
153 NEXT_ARG();
154
155 if (**argv && ((group = strtol(*argv, &end, 10)), !*end))
156 *gid = group;
157 else {
158 struct group *gr = getgrnam(*argv);
159 if (!gr) {
160 fprintf(stderr, "invalid group \"%s\"\n", *argv);
161 exit(-1);
162 }
163 *gid = gr->gr_gid;
164 }
165 } else if (matches(*argv, "pi") == 0) {
166 ifr->ifr_flags &= ~IFF_NO_PI;
167 } else if (matches(*argv, "one_queue") == 0) {
168 ifr->ifr_flags |= IFF_ONE_QUEUE;
169 } else if (matches(*argv, "vnet_hdr") == 0) {
170 ifr->ifr_flags |= IFF_VNET_HDR;
171 } else if (matches(*argv, "dev") == 0) {
172 NEXT_ARG();
173 strncpy(ifr->ifr_name, *argv, IFNAMSIZ-1);
174 } else {
175 if (matches(*argv, "name") == 0) {
176 NEXT_ARG();
177 } else if (matches(*argv, "help") == 0)
178 usage();
179 if (ifr->ifr_name[0])
180 duparg2("name", *argv);
181 strncpy(ifr->ifr_name, *argv, IFNAMSIZ);
182 }
183 count++;
184 argc--; argv++;
185 }
186
187 return 0;
188 }
189
190
do_add(int argc,char ** argv)191 static int do_add(int argc, char **argv)
192 {
193 struct ifreq ifr;
194 uid_t uid = -1;
195 gid_t gid = -1;
196
197 if (parse_args(argc, argv, &ifr, &uid, &gid) < 0)
198 return -1;
199
200 if (!(ifr.ifr_flags & TUN_TYPE_MASK)) {
201 fprintf(stderr, "You failed to specify a tunnel mode\n");
202 return -1;
203 }
204 return tap_add_ioctl(&ifr, uid, gid);
205 }
206
do_del(int argc,char ** argv)207 static int do_del(int argc, char **argv)
208 {
209 struct ifreq ifr;
210
211 if (parse_args(argc, argv, &ifr, NULL, NULL) < 0)
212 return -1;
213
214 return tap_del_ioctl(&ifr);
215 }
216
read_prop(char * dev,char * prop,long * value)217 static int read_prop(char *dev, char *prop, long *value)
218 {
219 char fname[IFNAMSIZ+25], buf[80], *endp;
220 ssize_t len;
221 int fd;
222 long result;
223
224 sprintf(fname, "/sys/class/net/%s/%s", dev, prop);
225 fd = open(fname, O_RDONLY);
226 if (fd < 0) {
227 if (strcmp(prop, "tun_flags"))
228 fprintf(stderr, "open %s: %s\n", fname,
229 strerror(errno));
230 return -1;
231 }
232 len = read(fd, buf, sizeof(buf)-1);
233 close(fd);
234 if (len < 0) {
235 fprintf(stderr, "read %s: %s", fname, strerror(errno));
236 return -1;
237 }
238
239 buf[len] = 0;
240 result = strtol(buf, &endp, 0);
241 if (*endp != '\n') {
242 fprintf(stderr, "Failed to parse %s\n", fname);
243 return -1;
244 }
245 *value = result;
246 return 0;
247 }
248
print_flags(long flags)249 static void print_flags(long flags)
250 {
251 if (flags & IFF_TUN)
252 printf(" tun");
253
254 if (flags & IFF_TAP)
255 printf(" tap");
256
257 if (!(flags & IFF_NO_PI))
258 printf(" pi");
259
260 if (flags & IFF_ONE_QUEUE)
261 printf(" one_queue");
262
263 if (flags & IFF_VNET_HDR)
264 printf(" vnet_hdr");
265
266 flags &= ~(IFF_TUN|IFF_TAP|IFF_NO_PI|IFF_ONE_QUEUE|IFF_VNET_HDR);
267 if (flags)
268 printf(" UNKNOWN_FLAGS:%lx", flags);
269 }
270
do_show(int argc,char ** argv)271 static int do_show(int argc, char **argv)
272 {
273 DIR *dir;
274 struct dirent *d;
275 long flags, owner = -1, group = -1;
276
277 dir = opendir("/sys/class/net");
278 if (!dir) {
279 perror("opendir");
280 return -1;
281 }
282 while ((d = readdir(dir))) {
283 if (d->d_name[0] == '.' &&
284 (d->d_name[1] == 0 || d->d_name[1] == '.'))
285 continue;
286
287 if (read_prop(d->d_name, "tun_flags", &flags))
288 continue;
289
290 read_prop(d->d_name, "owner", &owner);
291 read_prop(d->d_name, "group", &group);
292
293 printf("%s:", d->d_name);
294 print_flags(flags);
295 if (owner != -1)
296 printf(" user %ld", owner);
297 if (group != -1)
298 printf(" group %ld", group);
299 printf("\n");
300 }
301 return 0;
302 }
303
do_iptuntap(int argc,char ** argv)304 int do_iptuntap(int argc, char **argv)
305 {
306 if (argc > 0) {
307 if (matches(*argv, "add") == 0)
308 return do_add(argc-1, argv+1);
309 if (matches(*argv, "del") == 0)
310 return do_del(argc-1, argv+1);
311 if (matches(*argv, "show") == 0 ||
312 matches(*argv, "lst") == 0 ||
313 matches(*argv, "list") == 0)
314 return do_show(argc-1, argv+1);
315 if (matches(*argv, "help") == 0)
316 usage();
317 } else
318 return do_show(0, NULL);
319
320 fprintf(stderr, "Command \"%s\" is unknown, try \"ip tuntap help\".\n",
321 *argv);
322 exit(-1);
323 }
324