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 | |
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(entry: &conn->list); |
61 | |
62 | conn->fd = fd; |
63 | list_add(new: &conn->list, head: &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 | |
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(fd: port->fd, socket_out: socket, pid_out: &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(size: 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(v: &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(new: &conn->list, head: &port->pending); |
114 | return 1; |
115 | |
116 | out_free: |
117 | kfree(objp: 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 | |
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 | static DECLARE_WORK(port_work, port_work_proc); |
148 | |
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(work: &port_work); |
155 | return IRQ_HANDLED; |
156 | } |
157 | |
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(size: 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: 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(x: &port->done); |
200 | list_add(new: &port->list, head: &ports); |
201 | |
202 | found: |
203 | dev = kmalloc(size: 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(objp: port); |
218 | out: |
219 | mutex_unlock(lock: &ports_mutex); |
220 | return dev; |
221 | } |
222 | |
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(v: &port->wait_count); |
231 | while (1) { |
232 | fd = -ERESTARTSYS; |
233 | if (wait_for_completion_interruptible(x: &port->done)) |
234 | goto out; |
235 | |
236 | spin_lock(lock: &port->lock); |
237 | |
238 | conn = list_entry(port->connections.next, struct connection, |
239 | list); |
240 | list_del(entry: &conn->list); |
241 | spin_unlock(lock: &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(objp: conn); |
260 | } |
261 | |
262 | fd = conn->fd; |
263 | dev->helper_pid = conn->helper_pid; |
264 | dev->telnetd_pid = conn->telnetd_pid; |
265 | kfree(objp: conn); |
266 | out: |
267 | atomic_dec(v: &port->wait_count); |
268 | return fd; |
269 | } |
270 | |
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 | |
283 | void port_kern_free(void *d) |
284 | { |
285 | struct port_dev *dev = d; |
286 | |
287 | port_remove_dev(d: dev); |
288 | kfree(objp: dev); |
289 | } |
290 | |
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 | |