path: root/networking/tunctl.c (plain)
blob: fa904c2a947208cfae67cf5646028830fdeed32b

1	/* vi: set sw=4 ts=4: */
2	/*
3	* tun devices controller
4	*
5	* Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
6	*
7	* Original code:
8	* Jeff Dike
9	*
10	* Licensed under GPLv2, see file LICENSE in this source tree.
11	*/
12	//config:config TUNCTL
13	//config: bool "tunctl"
14	//config: default y
15	//config: select PLATFORM_LINUX
16	//config: help
17	//config: tunctl creates or deletes tun devices.
18	//config:
19	//config:config FEATURE_TUNCTL_UG
20	//config: bool "Support owner:group assignment"
21	//config: default y
22	//config: depends on TUNCTL
23	//config: help
24	//config: Allow to specify owner and group of newly created interface.
25	//config: 340 bytes of pure bloat. Say no here.
26
27	//applet:IF_TUNCTL(APPLET(tunctl, BB_DIR_SBIN, BB_SUID_DROP))
28
29	//kbuild:lib-$(CONFIG_TUNCTL) += tunctl.o
30
31	//usage:#define tunctl_trivial_usage
32	//usage: "[-f device] ([-t name] | -d name)" IF_FEATURE_TUNCTL_UG(" [-u owner] [-g group] [-b]")
33	//usage:#define tunctl_full_usage "\n\n"
34	//usage: "Create or delete tun interfaces\n"
35	//usage: "\n -f name tun device (/dev/net/tun)"
36	//usage: "\n -t name Create iface 'name'"
37	//usage: "\n -d name Delete iface 'name'"
38	//usage: IF_FEATURE_TUNCTL_UG(
39	//usage: "\n -u owner Set iface owner"
40	//usage: "\n -g group Set iface group"
41	//usage: "\n -b Brief output"
42	//usage: )
43	//usage:
44	//usage:#define tunctl_example_usage
45	//usage: "# tunctl\n"
46	//usage: "# tunctl -d tun0\n"
47
48	#include <netinet/in.h>
49	#include <net/if.h>
50	#include <linux/if_tun.h>
51	#include "libbb.h"
52
53	/* TUNSETGROUP appeared in 2.6.23 */
54	#ifndef TUNSETGROUP
55	#define TUNSETGROUP _IOW('T', 206, int)
56	#endif
57
58	#define IOCTL(a, b, c) ioctl_or_perror_and_die(a, b, c, NULL)
59
60	#if 1
61
62	int tunctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
63	int tunctl_main(int argc UNUSED_PARAM, char **argv)
64	{
65	struct ifreq ifr;
66	int fd;
67	const char *opt_name = "tap%d";
68	const char *opt_device = "/dev/net/tun";
69	#if ENABLE_FEATURE_TUNCTL_UG
70	const char *opt_user, *opt_group;
71	long user = -1, group = -1;
72	#endif
73	unsigned opts;
74
75	enum {
76	OPT_f = 1 << 0, // control device name (/dev/net/tun)
77	OPT_t = 1 << 1, // create named interface
78	OPT_d = 1 << 2, // delete named interface
79	#if ENABLE_FEATURE_TUNCTL_UG
80	OPT_u = 1 << 3, // set new interface owner
81	OPT_g = 1 << 4, // set new interface group
82	OPT_b = 1 << 5, // brief output
83	#endif
84	};
85
86	opt_complementary = "=0:t--d:d--t"; // no arguments; t ^ d
87	opts = getopt32(argv, "f:t:d:" IF_FEATURE_TUNCTL_UG("u:g:b"),
88	&opt_device, &opt_name, &opt_name
89	IF_FEATURE_TUNCTL_UG(, &opt_user, &opt_group));
90
91	// select device
92	memset(&ifr, 0, sizeof(ifr));
93	ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
94	strncpy_IFNAMSIZ(ifr.ifr_name, opt_name);
95
96	// open device
97	fd = xopen(opt_device, O_RDWR);
98	IOCTL(fd, TUNSETIFF, (void *)&ifr);
99
100	// delete?
101	if (opts & OPT_d) {
102	IOCTL(fd, TUNSETPERSIST, (void *)(uintptr_t)0);
103	printf("Set '%s' nonpersistent\n", ifr.ifr_name);
104	return EXIT_SUCCESS;
105	}
106
107	// create
108	#if ENABLE_FEATURE_TUNCTL_UG
109	if (opts & OPT_g) {
110	group = xgroup2gid(opt_group);
111	IOCTL(fd, TUNSETGROUP, (void *)(uintptr_t)group);
112	} else
113	user = geteuid();
114	if (opts & OPT_u)
115	user = xuname2uid(opt_user);
116	IOCTL(fd, TUNSETOWNER, (void *)(uintptr_t)user);
117	#endif
118	IOCTL(fd, TUNSETPERSIST, (void *)(uintptr_t)1);
119
120	// show info
121	#if ENABLE_FEATURE_TUNCTL_UG
122	if (opts & OPT_b) {
123	puts(ifr.ifr_name);
124	} else {
125	printf("Set '%s' %spersistent", ifr.ifr_name, "");
126	printf(" and owned by uid %ld", user);
127	if (group != -1)
128	printf(" gid %ld", group);
129	bb_putchar('\n');
130	}
131	#else
132	puts(ifr.ifr_name);
133	#endif
134	return EXIT_SUCCESS;
135	}
136
137	#else
138
139	/* -210 bytes: */
140
141	int tunctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
142	int tunctl_main(int argc UNUSED_PARAM, char **argv)
143	{
144	struct ifreq ifr;
145	int fd;
146	const char *opt_name = "tap%d";
147	const char *opt_device = "/dev/net/tun";
148	unsigned opts;
149
150	enum {
151	OPT_f = 1 << 0, // control device name (/dev/net/tun)
152	OPT_t = 1 << 1, // create named interface
153	OPT_d = 1 << 2, // delete named interface
154	};
155
156	opt_complementary = "=0:t--d:d--t"; // no arguments; t ^ d
157	opts = getopt32(argv, "f:t:d:u:g:b", // u, g, b accepted and ignored
158	&opt_device, &opt_name, &opt_name, NULL, NULL);
159
160	// set interface name
161	memset(&ifr, 0, sizeof(ifr));
162	ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
163	strncpy_IFNAMSIZ(ifr.ifr_name, opt_name);
164
165	// open device
166	fd = xopen(opt_device, O_RDWR);
167	IOCTL(fd, TUNSETIFF, (void *)&ifr);
168
169	// create or delete interface
170	IOCTL(fd, TUNSETPERSIST, (void *)(uintptr_t)(0 == (opts & OPT_d)));
171
172	return EXIT_SUCCESS;
173	}
174
175	#endif
176