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
18int 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
33void 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. */
50void 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
86err:
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
95int 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
108int 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
123int 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
136int 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
151int 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
167struct change_pre_exec_data {
168	int close_me;
169	int stdout_fd;
170};
171
172static 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
180static 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
206static 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
240void open_addr(unsigned char *addr, unsigned char *netmask, void *arg)
241{
242	change(arg, "add", addr, netmask);
243}
244
245void close_addr(unsigned char *addr, unsigned char *netmask, void *arg)
246{
247	change(arg, "del", addr, netmask);
248}
249
250char *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;
268out:
269	va_end(ap);
270	return ret;
271}
272