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 <stdarg.h>
9 #include <errno.h>
10 #include <stddef.h>
11 #include <string.h>
12 #include <sys/socket.h>
13 #include <sys/wait.h>
14 #include <net_user.h>
15 #include <os.h>
16 #include <um_malloc.h>
17 
tap_open_common(void * dev,char * gate_addr)18 int tap_open_common(void *dev, char *gate_addr)
19 {
20 	int tap_addr[4];
21 
22 	if (gate_addr == NULL)
23 		return 0;
24 	if (sscanf(gate_addr, "%d.%d.%d.%d", &tap_addr[0],
25 		  &tap_addr[1], &tap_addr[2], &tap_addr[3]) != 4) {
26 		printk(UM_KERN_ERR "Invalid tap IP address - '%s'\n",
27 		       gate_addr);
28 		return -EINVAL;
29 	}
30 	return 0;
31 }
32 
tap_check_ips(char * gate_addr,unsigned char * eth_addr)33 void tap_check_ips(char *gate_addr, unsigned char *eth_addr)
34 {
35 	int tap_addr[4];
36 
37 	if ((gate_addr != NULL) &&
38 	    (sscanf(gate_addr, "%d.%d.%d.%d", &tap_addr[0],
39 		    &tap_addr[1], &tap_addr[2], &tap_addr[3]) == 4) &&
40 	    (eth_addr[0] == tap_addr[0]) &&
41 	    (eth_addr[1] == tap_addr[1]) &&
42 	    (eth_addr[2] == tap_addr[2]) &&
43 	    (eth_addr[3] == tap_addr[3])) {
44 		printk(UM_KERN_ERR "The tap IP address and the UML eth IP "
45 		       "address must be different\n");
46 	}
47 }
48 
49 /* Do reliable error handling as this fails frequently enough. */
read_output(int fd,char * output,int len)50 void read_output(int fd, char *output, int len)
51 {
52 	int remain, ret, expected;
53 	char c;
54 	char *str;
55 
56 	if (output == NULL) {
57 		output = &c;
58 		len = sizeof(c);
59 	}
60 
61 	*output = '\0';
62 	ret = read(fd, &remain, sizeof(remain));
63 
64 	if (ret != sizeof(remain)) {
65 		if (ret < 0)
66 			ret = -errno;
67 		expected = sizeof(remain);
68 		str = "length";
69 		goto err;
70 	}
71 
72 	while (remain != 0) {
73 		expected = (remain < len) ? remain : len;
74 		ret = read(fd, output, expected);
75 		if (ret != expected) {
76 			if (ret < 0)
77 				ret = -errno;
78 			str = "data";
79 			goto err;
80 		}
81 		remain -= ret;
82 	}
83 
84 	return;
85 
86 err:
87 	if (ret < 0)
88 		printk(UM_KERN_ERR "read_output - read of %s failed, "
89 		       "errno = %d\n", str, -ret);
90 	else
91 		printk(UM_KERN_ERR "read_output - read of %s failed, read only "
92 		       "%d of %d bytes\n", str, ret, expected);
93 }
94 
net_read(int fd,void * buf,int len)95 int net_read(int fd, void *buf, int len)
96 {
97 	int n;
98 
99 	n = read(fd,  buf,  len);
100 
101 	if ((n < 0) && (errno == EAGAIN))
102 		return 0;
103 	else if (n == 0)
104 		return -ENOTCONN;
105 	return n;
106 }
107 
net_recvfrom(int fd,void * buf,int len)108 int net_recvfrom(int fd, void *buf, int len)
109 {
110 	int n;
111 
112 	CATCH_EINTR(n = recvfrom(fd,  buf,  len, 0, NULL, NULL));
113 	if (n < 0) {
114 		if (errno == EAGAIN)
115 			return 0;
116 		return -errno;
117 	}
118 	else if (n == 0)
119 		return -ENOTCONN;
120 	return n;
121 }
122 
net_write(int fd,void * buf,int len)123 int net_write(int fd, void *buf, int len)
124 {
125 	int n;
126 
127 	n = write(fd, buf, len);
128 
129 	if ((n < 0) && (errno == EAGAIN))
130 		return 0;
131 	else if (n == 0)
132 		return -ENOTCONN;
133 	return n;
134 }
135 
net_send(int fd,void * buf,int len)136 int net_send(int fd, void *buf, int len)
137 {
138 	int n;
139 
140 	CATCH_EINTR(n = send(fd, buf, len, 0));
141 	if (n < 0) {
142 		if (errno == EAGAIN)
143 			return 0;
144 		return -errno;
145 	}
146 	else if (n == 0)
147 		return -ENOTCONN;
148 	return n;
149 }
150 
net_sendto(int fd,void * buf,int len,void * to,int sock_len)151 int net_sendto(int fd, void *buf, int len, void *to, int sock_len)
152 {
153 	int n;
154 
155 	CATCH_EINTR(n = sendto(fd, buf, len, 0, (struct sockaddr *) to,
156 			       sock_len));
157 	if (n < 0) {
158 		if (errno == EAGAIN)
159 			return 0;
160 		return -errno;
161 	}
162 	else if (n == 0)
163 		return -ENOTCONN;
164 	return n;
165 }
166 
167 struct change_pre_exec_data {
168 	int close_me;
169 	int stdout_fd;
170 };
171 
change_pre_exec(void * arg)172 static void change_pre_exec(void *arg)
173 {
174 	struct change_pre_exec_data *data = arg;
175 
176 	close(data->close_me);
177 	dup2(data->stdout_fd, 1);
178 }
179 
change_tramp(char ** argv,char * output,int output_len)180 static int change_tramp(char **argv, char *output, int output_len)
181 {
182 	int pid, fds[2], err;
183 	struct change_pre_exec_data pe_data;
184 
185 	err = os_pipe(fds, 1, 0);
186 	if (err < 0) {
187 		printk(UM_KERN_ERR "change_tramp - pipe failed, err = %d\n",
188 		       -err);
189 		return err;
190 	}
191 	pe_data.close_me = fds[0];
192 	pe_data.stdout_fd = fds[1];
193 	pid = run_helper(change_pre_exec, &pe_data, argv);
194 
195 	if (pid > 0)	/* Avoid hang as we won't get data in failure case. */
196 		read_output(fds[0], output, output_len);
197 
198 	close(fds[0]);
199 	close(fds[1]);
200 
201 	if (pid > 0)
202 		helper_wait(pid);
203 	return pid;
204 }
205 
change(char * dev,char * what,unsigned char * addr,unsigned char * netmask)206 static void change(char *dev, char *what, unsigned char *addr,
207 		   unsigned char *netmask)
208 {
209 	char addr_buf[sizeof("255.255.255.255\0")];
210 	char netmask_buf[sizeof("255.255.255.255\0")];
211 	char version[sizeof("nnnnn\0")];
212 	char *argv[] = { "uml_net", version, what, dev, addr_buf,
213 			 netmask_buf, NULL };
214 	char *output;
215 	int output_len, pid;
216 
217 	sprintf(version, "%d", UML_NET_VERSION);
218 	sprintf(addr_buf, "%d.%d.%d.%d", addr[0], addr[1], addr[2], addr[3]);
219 	sprintf(netmask_buf, "%d.%d.%d.%d", netmask[0], netmask[1],
220 		netmask[2], netmask[3]);
221 
222 	output_len = UM_KERN_PAGE_SIZE;
223 	output = uml_kmalloc(output_len, UM_GFP_KERNEL);
224 	if (output == NULL)
225 		printk(UM_KERN_ERR "change : failed to allocate output "
226 		       "buffer\n");
227 
228 	pid = change_tramp(argv, output, output_len);
229 	if (pid < 0) {
230 		kfree(output);
231 		return;
232 	}
233 
234 	if (output != NULL) {
235 		printk("%s", output);
236 		kfree(output);
237 	}
238 }
239 
open_addr(unsigned char * addr,unsigned char * netmask,void * arg)240 void open_addr(unsigned char *addr, unsigned char *netmask, void *arg)
241 {
242 	change(arg, "add", addr, netmask);
243 }
244 
close_addr(unsigned char * addr,unsigned char * netmask,void * arg)245 void close_addr(unsigned char *addr, unsigned char *netmask, void *arg)
246 {
247 	change(arg, "del", addr, netmask);
248 }
249 
split_if_spec(char * str,...)250 char *split_if_spec(char *str, ...)
251 {
252 	char **arg, *end, *ret = NULL;
253 	va_list ap;
254 
255 	va_start(ap, str);
256 	while ((arg = va_arg(ap, char **)) != NULL) {
257 		if (*str == '\0')
258 			goto out;
259 		end = strchr(str, ',');
260 		if (end != str)
261 			*arg = str;
262 		if (end == NULL)
263 			goto out;
264 		*end++ = '\0';
265 		str = end;
266 	}
267 	ret = str;
268 out:
269 	va_end(ap);
270 	return ret;
271 }
272