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
18struct 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
30struct port_dev {
31	struct port_list *port;
32	int helper_pid;
33	int telnetd_pid;
34};
35
36struct 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
45static 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
76static 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) < 0) {
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
125static DEFINE_MUTEX(ports_mutex);
126static LIST_HEAD(ports);
127
128static 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
147static DECLARE_WORK(port_work, port_work_proc);
148
149static 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
158void *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) < 0) {
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
223int 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
271void 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
283void port_kern_free(void *d)
284{
285	struct port_dev *dev = d;
286
287	port_remove_dev(dev);
288	kfree(dev);
289}
290
291static 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