1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 */
5
6#include <stdio.h>
7#include <unistd.h>
8#include <errno.h>
9#include <string.h>
10#include <linux/if_tun.h>
11#include <net/if.h>
12#include <sys/ioctl.h>
13#include <sys/socket.h>
14#include <sys/wait.h>
15#include <sys/uio.h>
16#include <kern_util.h>
17#include <os.h>
18#include "tuntap.h"
19
20static int tuntap_user_init(void *data, void *dev)
21{
22	struct tuntap_data *pri = data;
23
24	pri->dev = dev;
25	return 0;
26}
27
28static void tuntap_add_addr(unsigned char *addr, unsigned char *netmask,
29			    void *data)
30{
31	struct tuntap_data *pri = data;
32
33	tap_check_ips(pri->gate_addr, addr);
34	if ((pri->fd == -1) || pri->fixed_config)
35		return;
36	open_addr(addr, netmask, pri->dev_name);
37}
38
39static void tuntap_del_addr(unsigned char *addr, unsigned char *netmask,
40			    void *data)
41{
42	struct tuntap_data *pri = data;
43
44	if ((pri->fd == -1) || pri->fixed_config)
45		return;
46	close_addr(addr, netmask, pri->dev_name);
47}
48
49struct tuntap_pre_exec_data {
50	int stdout_fd;
51	int close_me;
52};
53
54static void tuntap_pre_exec(void *arg)
55{
56	struct tuntap_pre_exec_data *data = arg;
57
58	dup2(data->stdout_fd, 1);
59	close(data->close_me);
60}
61
62static int tuntap_open_tramp(char *gate, int *fd_out, int me, int remote,
63			     char *buffer, int buffer_len, int *used_out)
64{
65	struct tuntap_pre_exec_data data;
66	char version_buf[sizeof("nnnnn\0")];
67	char *argv[] = { "uml_net", version_buf, "tuntap", "up", gate,
68			 NULL };
69	char buf[CMSG_SPACE(sizeof(*fd_out))];
70	struct msghdr msg;
71	struct cmsghdr *cmsg;
72	struct iovec iov;
73	int pid, n, err;
74
75	sprintf(version_buf, "%d", UML_NET_VERSION);
76
77	data.stdout_fd = remote;
78	data.close_me = me;
79
80	pid = run_helper(tuntap_pre_exec, &data, argv);
81
82	if (pid < 0)
83		return pid;
84
85	close(remote);
86
87	msg.msg_name = NULL;
88	msg.msg_namelen = 0;
89	if (buffer != NULL) {
90		iov = ((struct iovec) { buffer, buffer_len });
91		msg.msg_iov = &iov;
92		msg.msg_iovlen = 1;
93	}
94	else {
95		msg.msg_iov = NULL;
96		msg.msg_iovlen = 0;
97	}
98	msg.msg_control = buf;
99	msg.msg_controllen = sizeof(buf);
100	msg.msg_flags = 0;
101	n = recvmsg(me, &msg, 0);
102	*used_out = n;
103	if (n < 0) {
104		err = -errno;
105		printk(UM_KERN_ERR "tuntap_open_tramp : recvmsg failed - "
106		       "errno = %d\n", errno);
107		return err;
108	}
109	helper_wait(pid);
110
111	cmsg = CMSG_FIRSTHDR(&msg);
112	if (cmsg == NULL) {
113		printk(UM_KERN_ERR "tuntap_open_tramp : didn't receive a "
114		       "message\n");
115		return -EINVAL;
116	}
117	if ((cmsg->cmsg_level != SOL_SOCKET) ||
118	   (cmsg->cmsg_type != SCM_RIGHTS)) {
119		printk(UM_KERN_ERR "tuntap_open_tramp : didn't receive a "
120		       "descriptor\n");
121		return -EINVAL;
122	}
123	*fd_out = ((int *) CMSG_DATA(cmsg))[0];
124	os_set_exec_close(*fd_out);
125	return 0;
126}
127
128static int tuntap_open(void *data)
129{
130	struct ifreq ifr;
131	struct tuntap_data *pri = data;
132	char *output, *buffer;
133	int err, fds[2], len, used;
134
135	err = tap_open_common(pri->dev, pri->gate_addr);
136	if (err < 0)
137		return err;
138
139	if (pri->fixed_config) {
140		pri->fd = os_open_file("/dev/net/tun",
141				       of_cloexec(of_rdwr(OPENFLAGS())), 0);
142		if (pri->fd < 0) {
143			printk(UM_KERN_ERR "Failed to open /dev/net/tun, "
144			       "err = %d\n", -pri->fd);
145			return pri->fd;
146		}
147		memset(&ifr, 0, sizeof(ifr));
148		ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
149		strscpy(ifr.ifr_name, pri->dev_name);
150		if (ioctl(pri->fd, TUNSETIFF, &ifr) < 0) {
151			err = -errno;
152			printk(UM_KERN_ERR "TUNSETIFF failed, errno = %d\n",
153			       errno);
154			close(pri->fd);
155			return err;
156		}
157	}
158	else {
159		err = socketpair(AF_UNIX, SOCK_DGRAM, 0, fds);
160		if (err) {
161			err = -errno;
162			printk(UM_KERN_ERR "tuntap_open : socketpair failed - "
163			       "errno = %d\n", errno);
164			return err;
165		}
166
167		buffer = get_output_buffer(&len);
168		if (buffer != NULL)
169			len--;
170		used = 0;
171
172		err = tuntap_open_tramp(pri->gate_addr, &pri->fd, fds[0],
173					fds[1], buffer, len, &used);
174
175		output = buffer;
176		if (err < 0) {
177			printk("%s", output);
178			free_output_buffer(buffer);
179			printk(UM_KERN_ERR "tuntap_open_tramp failed - "
180			       "err = %d\n", -err);
181			return err;
182		}
183
184		pri->dev_name = uml_strdup(buffer);
185		output += IFNAMSIZ;
186		printk("%s", output);
187		free_output_buffer(buffer);
188
189		close(fds[0]);
190		iter_addresses(pri->dev, open_addr, pri->dev_name);
191	}
192
193	return pri->fd;
194}
195
196static void tuntap_close(int fd, void *data)
197{
198	struct tuntap_data *pri = data;
199
200	if (!pri->fixed_config)
201		iter_addresses(pri->dev, close_addr, pri->dev_name);
202	close(fd);
203	pri->fd = -1;
204}
205
206const struct net_user_info tuntap_user_info = {
207	.init		= tuntap_user_init,
208	.open		= tuntap_open,
209	.close	 	= tuntap_close,
210	.remove	 	= NULL,
211	.add_address	= tuntap_add_addr,
212	.delete_address = tuntap_del_addr,
213	.mtu		= ETH_MAX_PACKET,
214	.max_packet	= ETH_MAX_PACKET + ETH_HEADER_OTHER,
215};
216