1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
5  * James Leu (jleu@mindspring.net).
6  * Copyright (C) 2001 by various other people who didn't put their name here.
7  */
8 
9 #include <stdio.h>
10 #include <unistd.h>
11 #include <errno.h>
12 #include <string.h>
13 #include <sys/socket.h>
14 #include <sys/wait.h>
15 #include "etap.h"
16 #include <os.h>
17 #include <net_user.h>
18 #include <um_malloc.h>
19 
20 #define MAX_PACKET ETH_MAX_PACKET
21 
22 static int etap_user_init(void *data, void *dev)
23 {
24 	struct ethertap_data *pri = data;
25 
26 	pri->dev = dev;
27 	return 0;
28 }
29 
30 struct addr_change {
31 	enum { ADD_ADDR, DEL_ADDR } what;
32 	unsigned char addr[4];
33 	unsigned char netmask[4];
34 };
35 
36 static void etap_change(int op, unsigned char *addr, unsigned char *netmask,
37 			int fd)
38 {
39 	struct addr_change change;
40 	char *output;
41 	int n;
42 
43 	change.what = op;
44 	memcpy(change.addr, addr, sizeof(change.addr));
45 	memcpy(change.netmask, netmask, sizeof(change.netmask));
46 	CATCH_EINTR(n = write(fd, &change, sizeof(change)));
47 	if (n != sizeof(change)) {
48 		printk(UM_KERN_ERR "etap_change - request failed, err = %d\n",
49 		       errno);
50 		return;
51 	}
52 
53 	output = uml_kmalloc(UM_KERN_PAGE_SIZE, UM_GFP_KERNEL);
54 	if (output == NULL)
55 		printk(UM_KERN_ERR "etap_change : Failed to allocate output "
56 		       "buffer\n");
57 	read_output(fd, output, UM_KERN_PAGE_SIZE);
58 	if (output != NULL) {
59 		printk("%s", output);
60 		kfree(output);
61 	}
62 }
63 
64 static void etap_open_addr(unsigned char *addr, unsigned char *netmask,
65 			   void *arg)
66 {
67 	etap_change(ADD_ADDR, addr, netmask, *((int *) arg));
68 }
69 
70 static void etap_close_addr(unsigned char *addr, unsigned char *netmask,
71 			    void *arg)
72 {
73 	etap_change(DEL_ADDR, addr, netmask, *((int *) arg));
74 }
75 
76 struct etap_pre_exec_data {
77 	int control_remote;
78 	int control_me;
79 	int data_me;
80 };
81 
82 static void etap_pre_exec(void *arg)
83 {
84 	struct etap_pre_exec_data *data = arg;
85 
86 	dup2(data->control_remote, 1);
87 	close(data->data_me);
88 	close(data->control_me);
89 }
90 
91 static int etap_tramp(char *dev, char *gate, int control_me,
92 		      int control_remote, int data_me, int data_remote)
93 {
94 	struct etap_pre_exec_data pe_data;
95 	int pid, err, n;
96 	char version_buf[sizeof("nnnnn\0")];
97 	char data_fd_buf[sizeof("nnnnnn\0")];
98 	char gate_buf[sizeof("nnn.nnn.nnn.nnn\0")];
99 	char *setup_args[] = { "uml_net", version_buf, "ethertap", dev,
100 			       data_fd_buf, gate_buf, NULL };
101 	char *nosetup_args[] = { "uml_net", version_buf, "ethertap",
102 				 dev, data_fd_buf, NULL };
103 	char **args, c;
104 
105 	sprintf(data_fd_buf, "%d", data_remote);
106 	sprintf(version_buf, "%d", UML_NET_VERSION);
107 	if (gate != NULL) {
108 		strncpy(gate_buf, gate, 15);
109 		args = setup_args;
110 	}
111 	else args = nosetup_args;
112 
113 	err = 0;
114 	pe_data.control_remote = control_remote;
115 	pe_data.control_me = control_me;
116 	pe_data.data_me = data_me;
117 	pid = run_helper(etap_pre_exec, &pe_data, args);
118 
119 	if (pid < 0)
120 		err = pid;
121 	close(data_remote);
122 	close(control_remote);
123 	CATCH_EINTR(n = read(control_me, &c, sizeof(c)));
124 	if (n != sizeof(c)) {
125 		err = -errno;
126 		printk(UM_KERN_ERR "etap_tramp : read of status failed, "
127 		       "err = %d\n", -err);
128 		return err;
129 	}
130 	if (c != 1) {
131 		printk(UM_KERN_ERR "etap_tramp : uml_net failed\n");
132 		err = helper_wait(pid);
133 	}
134 	return err;
135 }
136 
137 static int etap_open(void *data)
138 {
139 	struct ethertap_data *pri = data;
140 	char *output;
141 	int data_fds[2], control_fds[2], err, output_len;
142 
143 	err = tap_open_common(pri->dev, pri->gate_addr);
144 	if (err)
145 		return err;
146 
147 	err = socketpair(AF_UNIX, SOCK_DGRAM, 0, data_fds);
148 	if (err) {
149 		err = -errno;
150 		printk(UM_KERN_ERR "etap_open - data socketpair failed - "
151 		       "err = %d\n", errno);
152 		return err;
153 	}
154 
155 	err = socketpair(AF_UNIX, SOCK_STREAM, 0, control_fds);
156 	if (err) {
157 		err = -errno;
158 		printk(UM_KERN_ERR "etap_open - control socketpair failed - "
159 		       "err = %d\n", errno);
160 		goto out_close_data;
161 	}
162 
163 	err = etap_tramp(pri->dev_name, pri->gate_addr, control_fds[0],
164 			 control_fds[1], data_fds[0], data_fds[1]);
165 	output_len = UM_KERN_PAGE_SIZE;
166 	output = uml_kmalloc(output_len, UM_GFP_KERNEL);
167 	read_output(control_fds[0], output, output_len);
168 
169 	if (output == NULL)
170 		printk(UM_KERN_ERR "etap_open : failed to allocate output "
171 		       "buffer\n");
172 	else {
173 		printk("%s", output);
174 		kfree(output);
175 	}
176 
177 	if (err < 0) {
178 		printk(UM_KERN_ERR "etap_tramp failed - err = %d\n", -err);
179 		goto out_close_control;
180 	}
181 
182 	pri->data_fd = data_fds[0];
183 	pri->control_fd = control_fds[0];
184 	iter_addresses(pri->dev, etap_open_addr, &pri->control_fd);
185 	return data_fds[0];
186 
187 out_close_control:
188 	close(control_fds[0]);
189 	close(control_fds[1]);
190 out_close_data:
191 	close(data_fds[0]);
192 	close(data_fds[1]);
193 	return err;
194 }
195 
196 static void etap_close(int fd, void *data)
197 {
198 	struct ethertap_data *pri = data;
199 
200 	iter_addresses(pri->dev, etap_close_addr, &pri->control_fd);
201 	close(fd);
202 
203 	if (shutdown(pri->data_fd, SHUT_RDWR) < 0)
204 		printk(UM_KERN_ERR "etap_close - shutdown data socket failed, "
205 		       "errno = %d\n", errno);
206 
207 	if (shutdown(pri->control_fd, SHUT_RDWR) < 0)
208 		printk(UM_KERN_ERR "etap_close - shutdown control socket "
209 		       "failed, errno = %d\n", errno);
210 
211 	close(pri->data_fd);
212 	pri->data_fd = -1;
213 	close(pri->control_fd);
214 	pri->control_fd = -1;
215 }
216 
217 static void etap_add_addr(unsigned char *addr, unsigned char *netmask,
218 			  void *data)
219 {
220 	struct ethertap_data *pri = data;
221 
222 	tap_check_ips(pri->gate_addr, addr);
223 	if (pri->control_fd == -1)
224 		return;
225 	etap_open_addr(addr, netmask, &pri->control_fd);
226 }
227 
228 static void etap_del_addr(unsigned char *addr, unsigned char *netmask,
229 			  void *data)
230 {
231 	struct ethertap_data *pri = data;
232 
233 	if (pri->control_fd == -1)
234 		return;
235 
236 	etap_close_addr(addr, netmask, &pri->control_fd);
237 }
238 
239 const struct net_user_info ethertap_user_info = {
240 	.init		= etap_user_init,
241 	.open		= etap_open,
242 	.close	 	= etap_close,
243 	.remove	 	= NULL,
244 	.add_address	= etap_add_addr,
245 	.delete_address = etap_del_addr,
246 	.mtu		= ETH_MAX_PACKET,
247 	.max_packet	= ETH_MAX_PACKET + ETH_HEADER_ETHERTAP,
248 };
249