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
35static void usage(void) __attribute__((noreturn));
36
37static 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
48static 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
84static 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}
107static 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
191static 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
207static 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
217static 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
249static 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
271static 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
304int 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