1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
4 */
5
6 #include <linux/completion.h>
7 #include <linux/interrupt.h>
8 #include <linux/list.h>
9 #include <linux/mutex.h>
10 #include <linux/slab.h>
11 #include <linux/workqueue.h>
12 #include <asm/atomic.h>
13 #include <init.h>
14 #include <irq_kern.h>
15 #include <os.h>
16 #include "port.h"
17
18 struct port_list {
19 struct list_head list;
20 atomic_t wait_count;
21 int has_connection;
22 struct completion done;
23 int port;
24 int fd;
25 spinlock_t lock;
26 struct list_head pending;
27 struct list_head connections;
28 };
29
30 struct port_dev {
31 struct port_list *port;
32 int helper_pid;
33 int telnetd_pid;
34 };
35
36 struct connection {
37 struct list_head list;
38 int fd;
39 int helper_pid;
40 int socket[2];
41 int telnetd_pid;
42 struct port_list *port;
43 };
44
pipe_interrupt(int irq,void * data)45 static irqreturn_t pipe_interrupt(int irq, void *data)
46 {
47 struct connection *conn = data;
48 int fd;
49
50 fd = os_rcv_fd(conn->socket[0], &conn->helper_pid);
51 if (fd < 0) {
52 if (fd == -EAGAIN)
53 return IRQ_NONE;
54
55 printk(KERN_ERR "pipe_interrupt : os_rcv_fd returned %d\n",
56 -fd);
57 os_close_file(conn->fd);
58 }
59
60 list_del(&conn->list);
61
62 conn->fd = fd;
63 list_add(&conn->list, &conn->port->connections);
64
65 complete(&conn->port->done);
66 return IRQ_HANDLED;
67 }
68
69 #define NO_WAITER_MSG \
70 "****\n" \
71 "There are currently no UML consoles waiting for port connections.\n" \
72 "Either disconnect from one to make it available or activate some more\n" \
73 "by enabling more consoles in the UML /etc/inittab.\n" \
74 "****\n"
75
port_accept(struct port_list * port)76 static int port_accept(struct port_list *port)
77 {
78 struct connection *conn;
79 int fd, socket[2], pid;
80
81 fd = port_connection(port->fd, socket, &pid);
82 if (fd < 0) {
83 if (fd != -EAGAIN)
84 printk(KERN_ERR "port_accept : port_connection "
85 "returned %d\n", -fd);
86 goto out;
87 }
88
89 conn = kmalloc(sizeof(*conn), GFP_ATOMIC);
90 if (conn == NULL) {
91 printk(KERN_ERR "port_accept : failed to allocate "
92 "connection\n");
93 goto out_close;
94 }
95 *conn = ((struct connection)
96 { .list = LIST_HEAD_INIT(conn->list),
97 .fd = fd,
98 .socket = { socket[0], socket[1] },
99 .telnetd_pid = pid,
100 .port = port });
101
102 if (um_request_irq(TELNETD_IRQ, socket[0], IRQ_READ, pipe_interrupt,
103 IRQF_SHARED, "telnetd", conn)) {
104 printk(KERN_ERR "port_accept : failed to get IRQ for "
105 "telnetd\n");
106 goto out_free;
107 }
108
109 if (atomic_read(&port->wait_count) == 0) {
110 os_write_file(fd, NO_WAITER_MSG, sizeof(NO_WAITER_MSG));
111 printk(KERN_ERR "No one waiting for port\n");
112 }
113 list_add(&conn->list, &port->pending);
114 return 1;
115
116 out_free:
117 kfree(conn);
118 out_close:
119 os_close_file(fd);
120 os_kill_process(pid, 1);
121 out:
122 return 0;
123 }
124
125 static DEFINE_MUTEX(ports_mutex);
126 static LIST_HEAD(ports);
127
port_work_proc(struct work_struct * unused)128 static void port_work_proc(struct work_struct *unused)
129 {
130 struct port_list *port;
131 struct list_head *ele;
132 unsigned long flags;
133
134 local_irq_save(flags);
135 list_for_each(ele, &ports) {
136 port = list_entry(ele, struct port_list, list);
137 if (!port->has_connection)
138 continue;
139
140 while (port_accept(port))
141 ;
142 port->has_connection = 0;
143 }
144 local_irq_restore(flags);
145 }
146
147 DECLARE_WORK(port_work, port_work_proc);
148
port_interrupt(int irq,void * data)149 static irqreturn_t port_interrupt(int irq, void *data)
150 {
151 struct port_list *port = data;
152
153 port->has_connection = 1;
154 schedule_work(&port_work);
155 return IRQ_HANDLED;
156 }
157
port_data(int port_num)158 void *port_data(int port_num)
159 {
160 struct list_head *ele;
161 struct port_list *port;
162 struct port_dev *dev = NULL;
163 int fd;
164
165 mutex_lock(&ports_mutex);
166 list_for_each(ele, &ports) {
167 port = list_entry(ele, struct port_list, list);
168 if (port->port == port_num)
169 goto found;
170 }
171 port = kmalloc(sizeof(struct port_list), GFP_KERNEL);
172 if (port == NULL) {
173 printk(KERN_ERR "Allocation of port list failed\n");
174 goto out;
175 }
176
177 fd = port_listen_fd(port_num);
178 if (fd < 0) {
179 printk(KERN_ERR "binding to port %d failed, errno = %d\n",
180 port_num, -fd);
181 goto out_free;
182 }
183
184 if (um_request_irq(ACCEPT_IRQ, fd, IRQ_READ, port_interrupt,
185 IRQF_SHARED, "port", port)) {
186 printk(KERN_ERR "Failed to get IRQ for port %d\n", port_num);
187 goto out_close;
188 }
189
190 *port = ((struct port_list)
191 { .list = LIST_HEAD_INIT(port->list),
192 .wait_count = ATOMIC_INIT(0),
193 .has_connection = 0,
194 .port = port_num,
195 .fd = fd,
196 .pending = LIST_HEAD_INIT(port->pending),
197 .connections = LIST_HEAD_INIT(port->connections) });
198 spin_lock_init(&port->lock);
199 init_completion(&port->done);
200 list_add(&port->list, &ports);
201
202 found:
203 dev = kmalloc(sizeof(struct port_dev), GFP_KERNEL);
204 if (dev == NULL) {
205 printk(KERN_ERR "Allocation of port device entry failed\n");
206 goto out;
207 }
208
209 *dev = ((struct port_dev) { .port = port,
210 .helper_pid = -1,
211 .telnetd_pid = -1 });
212 goto out;
213
214 out_close:
215 os_close_file(fd);
216 out_free:
217 kfree(port);
218 out:
219 mutex_unlock(&ports_mutex);
220 return dev;
221 }
222
port_wait(void * data)223 int port_wait(void *data)
224 {
225 struct port_dev *dev = data;
226 struct connection *conn;
227 struct port_list *port = dev->port;
228 int fd;
229
230 atomic_inc(&port->wait_count);
231 while (1) {
232 fd = -ERESTARTSYS;
233 if (wait_for_completion_interruptible(&port->done))
234 goto out;
235
236 spin_lock(&port->lock);
237
238 conn = list_entry(port->connections.next, struct connection,
239 list);
240 list_del(&conn->list);
241 spin_unlock(&port->lock);
242
243 os_shutdown_socket(conn->socket[0], 1, 1);
244 os_close_file(conn->socket[0]);
245 os_shutdown_socket(conn->socket[1], 1, 1);
246 os_close_file(conn->socket[1]);
247
248 /* This is done here because freeing an IRQ can't be done
249 * within the IRQ handler. So, pipe_interrupt always ups
250 * the semaphore regardless of whether it got a successful
251 * connection. Then we loop here throwing out failed
252 * connections until a good one is found.
253 */
254 um_free_irq(TELNETD_IRQ, conn);
255
256 if (conn->fd >= 0)
257 break;
258 os_close_file(conn->fd);
259 kfree(conn);
260 }
261
262 fd = conn->fd;
263 dev->helper_pid = conn->helper_pid;
264 dev->telnetd_pid = conn->telnetd_pid;
265 kfree(conn);
266 out:
267 atomic_dec(&port->wait_count);
268 return fd;
269 }
270
port_remove_dev(void * d)271 void port_remove_dev(void *d)
272 {
273 struct port_dev *dev = d;
274
275 if (dev->helper_pid != -1)
276 os_kill_process(dev->helper_pid, 0);
277 if (dev->telnetd_pid != -1)
278 os_kill_process(dev->telnetd_pid, 1);
279 dev->helper_pid = -1;
280 dev->telnetd_pid = -1;
281 }
282
port_kern_free(void * d)283 void port_kern_free(void *d)
284 {
285 struct port_dev *dev = d;
286
287 port_remove_dev(dev);
288 kfree(dev);
289 }
290
free_port(void)291 static void free_port(void)
292 {
293 struct list_head *ele;
294 struct port_list *port;
295
296 list_for_each(ele, &ports) {
297 port = list_entry(ele, struct port_list, list);
298 free_irq_by_fd(port->fd);
299 os_close_file(port->fd);
300 }
301 }
302
303 __uml_exitcall(free_port);
304
