1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * User-space I/O driver support for HID subsystem |
4 | * Copyright (c) 2012 David Herrmann |
5 | */ |
6 | |
7 | /* |
8 | */ |
9 | |
10 | #include <linux/atomic.h> |
11 | #include <linux/compat.h> |
12 | #include <linux/cred.h> |
13 | #include <linux/device.h> |
14 | #include <linux/fs.h> |
15 | #include <linux/hid.h> |
16 | #include <linux/input.h> |
17 | #include <linux/miscdevice.h> |
18 | #include <linux/module.h> |
19 | #include <linux/mutex.h> |
20 | #include <linux/poll.h> |
21 | #include <linux/sched.h> |
22 | #include <linux/spinlock.h> |
23 | #include <linux/uhid.h> |
24 | #include <linux/wait.h> |
25 | |
26 | #define UHID_NAME "uhid" |
27 | #define UHID_BUFSIZE 32 |
28 | |
29 | struct uhid_device { |
30 | struct mutex devlock; |
31 | |
32 | /* This flag tracks whether the HID device is usable for commands from |
33 | * userspace. The flag is already set before hid_add_device(), which |
34 | * runs in workqueue context, to allow hid_add_device() to communicate |
35 | * with userspace. |
36 | * However, if hid_add_device() fails, the flag is cleared without |
37 | * holding devlock. |
38 | * We guarantee that if @running changes from true to false while you're |
39 | * holding @devlock, it's still fine to access @hid. |
40 | */ |
41 | bool running; |
42 | |
43 | __u8 *rd_data; |
44 | uint rd_size; |
45 | |
46 | /* When this is NULL, userspace may use UHID_CREATE/UHID_CREATE2. */ |
47 | struct hid_device *hid; |
48 | struct uhid_event input_buf; |
49 | |
50 | wait_queue_head_t waitq; |
51 | spinlock_t qlock; |
52 | __u8 head; |
53 | __u8 tail; |
54 | struct uhid_event *outq[UHID_BUFSIZE]; |
55 | |
56 | /* blocking GET_REPORT support; state changes protected by qlock */ |
57 | struct mutex report_lock; |
58 | wait_queue_head_t report_wait; |
59 | bool report_running; |
60 | u32 report_id; |
61 | u32 report_type; |
62 | struct uhid_event report_buf; |
63 | struct work_struct worker; |
64 | }; |
65 | |
66 | static struct miscdevice uhid_misc; |
67 | |
68 | static void uhid_device_add_worker(struct work_struct *work) |
69 | { |
70 | struct uhid_device *uhid = container_of(work, struct uhid_device, worker); |
71 | int ret; |
72 | |
73 | ret = hid_add_device(uhid->hid); |
74 | if (ret) { |
75 | hid_err(uhid->hid, "Cannot register HID device: error %d\n" , ret); |
76 | |
77 | /* We used to call hid_destroy_device() here, but that's really |
78 | * messy to get right because we have to coordinate with |
79 | * concurrent writes from userspace that might be in the middle |
80 | * of using uhid->hid. |
81 | * Just leave uhid->hid as-is for now, and clean it up when |
82 | * userspace tries to close or reinitialize the uhid instance. |
83 | * |
84 | * However, we do have to clear the ->running flag and do a |
85 | * wakeup to make sure userspace knows that the device is gone. |
86 | */ |
87 | WRITE_ONCE(uhid->running, false); |
88 | wake_up_interruptible(&uhid->report_wait); |
89 | } |
90 | } |
91 | |
92 | static void uhid_queue(struct uhid_device *uhid, struct uhid_event *ev) |
93 | { |
94 | __u8 newhead; |
95 | |
96 | newhead = (uhid->head + 1) % UHID_BUFSIZE; |
97 | |
98 | if (newhead != uhid->tail) { |
99 | uhid->outq[uhid->head] = ev; |
100 | uhid->head = newhead; |
101 | wake_up_interruptible(&uhid->waitq); |
102 | } else { |
103 | hid_warn(uhid->hid, "Output queue is full\n" ); |
104 | kfree(objp: ev); |
105 | } |
106 | } |
107 | |
108 | static int uhid_queue_event(struct uhid_device *uhid, __u32 event) |
109 | { |
110 | unsigned long flags; |
111 | struct uhid_event *ev; |
112 | |
113 | ev = kzalloc(size: sizeof(*ev), GFP_KERNEL); |
114 | if (!ev) |
115 | return -ENOMEM; |
116 | |
117 | ev->type = event; |
118 | |
119 | spin_lock_irqsave(&uhid->qlock, flags); |
120 | uhid_queue(uhid, ev); |
121 | spin_unlock_irqrestore(lock: &uhid->qlock, flags); |
122 | |
123 | return 0; |
124 | } |
125 | |
126 | static int uhid_hid_start(struct hid_device *hid) |
127 | { |
128 | struct uhid_device *uhid = hid->driver_data; |
129 | struct uhid_event *ev; |
130 | unsigned long flags; |
131 | |
132 | ev = kzalloc(size: sizeof(*ev), GFP_KERNEL); |
133 | if (!ev) |
134 | return -ENOMEM; |
135 | |
136 | ev->type = UHID_START; |
137 | |
138 | if (hid->report_enum[HID_FEATURE_REPORT].numbered) |
139 | ev->u.start.dev_flags |= UHID_DEV_NUMBERED_FEATURE_REPORTS; |
140 | if (hid->report_enum[HID_OUTPUT_REPORT].numbered) |
141 | ev->u.start.dev_flags |= UHID_DEV_NUMBERED_OUTPUT_REPORTS; |
142 | if (hid->report_enum[HID_INPUT_REPORT].numbered) |
143 | ev->u.start.dev_flags |= UHID_DEV_NUMBERED_INPUT_REPORTS; |
144 | |
145 | spin_lock_irqsave(&uhid->qlock, flags); |
146 | uhid_queue(uhid, ev); |
147 | spin_unlock_irqrestore(lock: &uhid->qlock, flags); |
148 | |
149 | return 0; |
150 | } |
151 | |
152 | static void uhid_hid_stop(struct hid_device *hid) |
153 | { |
154 | struct uhid_device *uhid = hid->driver_data; |
155 | |
156 | hid->claimed = 0; |
157 | uhid_queue_event(uhid, event: UHID_STOP); |
158 | } |
159 | |
160 | static int uhid_hid_open(struct hid_device *hid) |
161 | { |
162 | struct uhid_device *uhid = hid->driver_data; |
163 | |
164 | return uhid_queue_event(uhid, event: UHID_OPEN); |
165 | } |
166 | |
167 | static void uhid_hid_close(struct hid_device *hid) |
168 | { |
169 | struct uhid_device *uhid = hid->driver_data; |
170 | |
171 | uhid_queue_event(uhid, event: UHID_CLOSE); |
172 | } |
173 | |
174 | static int uhid_hid_parse(struct hid_device *hid) |
175 | { |
176 | struct uhid_device *uhid = hid->driver_data; |
177 | |
178 | return hid_parse_report(hid, start: uhid->rd_data, size: uhid->rd_size); |
179 | } |
180 | |
181 | /* must be called with report_lock held */ |
182 | static int __uhid_report_queue_and_wait(struct uhid_device *uhid, |
183 | struct uhid_event *ev, |
184 | __u32 *report_id) |
185 | { |
186 | unsigned long flags; |
187 | int ret; |
188 | |
189 | spin_lock_irqsave(&uhid->qlock, flags); |
190 | *report_id = ++uhid->report_id; |
191 | uhid->report_type = ev->type + 1; |
192 | uhid->report_running = true; |
193 | uhid_queue(uhid, ev); |
194 | spin_unlock_irqrestore(lock: &uhid->qlock, flags); |
195 | |
196 | ret = wait_event_interruptible_timeout(uhid->report_wait, |
197 | !uhid->report_running || !READ_ONCE(uhid->running), |
198 | 5 * HZ); |
199 | if (!ret || !READ_ONCE(uhid->running) || uhid->report_running) |
200 | ret = -EIO; |
201 | else if (ret < 0) |
202 | ret = -ERESTARTSYS; |
203 | else |
204 | ret = 0; |
205 | |
206 | uhid->report_running = false; |
207 | |
208 | return ret; |
209 | } |
210 | |
211 | static void uhid_report_wake_up(struct uhid_device *uhid, u32 id, |
212 | const struct uhid_event *ev) |
213 | { |
214 | unsigned long flags; |
215 | |
216 | spin_lock_irqsave(&uhid->qlock, flags); |
217 | |
218 | /* id for old report; drop it silently */ |
219 | if (uhid->report_type != ev->type || uhid->report_id != id) |
220 | goto unlock; |
221 | if (!uhid->report_running) |
222 | goto unlock; |
223 | |
224 | memcpy(&uhid->report_buf, ev, sizeof(*ev)); |
225 | uhid->report_running = false; |
226 | wake_up_interruptible(&uhid->report_wait); |
227 | |
228 | unlock: |
229 | spin_unlock_irqrestore(lock: &uhid->qlock, flags); |
230 | } |
231 | |
232 | static int uhid_hid_get_report(struct hid_device *hid, unsigned char rnum, |
233 | u8 *buf, size_t count, u8 rtype) |
234 | { |
235 | struct uhid_device *uhid = hid->driver_data; |
236 | struct uhid_get_report_reply_req *req; |
237 | struct uhid_event *ev; |
238 | int ret; |
239 | |
240 | if (!READ_ONCE(uhid->running)) |
241 | return -EIO; |
242 | |
243 | ev = kzalloc(size: sizeof(*ev), GFP_KERNEL); |
244 | if (!ev) |
245 | return -ENOMEM; |
246 | |
247 | ev->type = UHID_GET_REPORT; |
248 | ev->u.get_report.rnum = rnum; |
249 | ev->u.get_report.rtype = rtype; |
250 | |
251 | ret = mutex_lock_interruptible(&uhid->report_lock); |
252 | if (ret) { |
253 | kfree(objp: ev); |
254 | return ret; |
255 | } |
256 | |
257 | /* this _always_ takes ownership of @ev */ |
258 | ret = __uhid_report_queue_and_wait(uhid, ev, report_id: &ev->u.get_report.id); |
259 | if (ret) |
260 | goto unlock; |
261 | |
262 | req = &uhid->report_buf.u.get_report_reply; |
263 | if (req->err) { |
264 | ret = -EIO; |
265 | } else { |
266 | ret = min3(count, (size_t)req->size, (size_t)UHID_DATA_MAX); |
267 | memcpy(buf, req->data, ret); |
268 | } |
269 | |
270 | unlock: |
271 | mutex_unlock(lock: &uhid->report_lock); |
272 | return ret; |
273 | } |
274 | |
275 | static int uhid_hid_set_report(struct hid_device *hid, unsigned char rnum, |
276 | const u8 *buf, size_t count, u8 rtype) |
277 | { |
278 | struct uhid_device *uhid = hid->driver_data; |
279 | struct uhid_event *ev; |
280 | int ret; |
281 | |
282 | if (!READ_ONCE(uhid->running) || count > UHID_DATA_MAX) |
283 | return -EIO; |
284 | |
285 | ev = kzalloc(size: sizeof(*ev), GFP_KERNEL); |
286 | if (!ev) |
287 | return -ENOMEM; |
288 | |
289 | ev->type = UHID_SET_REPORT; |
290 | ev->u.set_report.rnum = rnum; |
291 | ev->u.set_report.rtype = rtype; |
292 | ev->u.set_report.size = count; |
293 | memcpy(ev->u.set_report.data, buf, count); |
294 | |
295 | ret = mutex_lock_interruptible(&uhid->report_lock); |
296 | if (ret) { |
297 | kfree(objp: ev); |
298 | return ret; |
299 | } |
300 | |
301 | /* this _always_ takes ownership of @ev */ |
302 | ret = __uhid_report_queue_and_wait(uhid, ev, report_id: &ev->u.set_report.id); |
303 | if (ret) |
304 | goto unlock; |
305 | |
306 | if (uhid->report_buf.u.set_report_reply.err) |
307 | ret = -EIO; |
308 | else |
309 | ret = count; |
310 | |
311 | unlock: |
312 | mutex_unlock(lock: &uhid->report_lock); |
313 | return ret; |
314 | } |
315 | |
316 | static int uhid_hid_raw_request(struct hid_device *hid, unsigned char reportnum, |
317 | __u8 *buf, size_t len, unsigned char rtype, |
318 | int reqtype) |
319 | { |
320 | u8 u_rtype; |
321 | |
322 | switch (rtype) { |
323 | case HID_FEATURE_REPORT: |
324 | u_rtype = UHID_FEATURE_REPORT; |
325 | break; |
326 | case HID_OUTPUT_REPORT: |
327 | u_rtype = UHID_OUTPUT_REPORT; |
328 | break; |
329 | case HID_INPUT_REPORT: |
330 | u_rtype = UHID_INPUT_REPORT; |
331 | break; |
332 | default: |
333 | return -EINVAL; |
334 | } |
335 | |
336 | switch (reqtype) { |
337 | case HID_REQ_GET_REPORT: |
338 | return uhid_hid_get_report(hid, rnum: reportnum, buf, count: len, rtype: u_rtype); |
339 | case HID_REQ_SET_REPORT: |
340 | return uhid_hid_set_report(hid, rnum: reportnum, buf, count: len, rtype: u_rtype); |
341 | default: |
342 | return -EIO; |
343 | } |
344 | } |
345 | |
346 | static int uhid_hid_output_raw(struct hid_device *hid, __u8 *buf, size_t count, |
347 | unsigned char report_type) |
348 | { |
349 | struct uhid_device *uhid = hid->driver_data; |
350 | __u8 rtype; |
351 | unsigned long flags; |
352 | struct uhid_event *ev; |
353 | |
354 | switch (report_type) { |
355 | case HID_FEATURE_REPORT: |
356 | rtype = UHID_FEATURE_REPORT; |
357 | break; |
358 | case HID_OUTPUT_REPORT: |
359 | rtype = UHID_OUTPUT_REPORT; |
360 | break; |
361 | default: |
362 | return -EINVAL; |
363 | } |
364 | |
365 | if (count < 1 || count > UHID_DATA_MAX) |
366 | return -EINVAL; |
367 | |
368 | ev = kzalloc(size: sizeof(*ev), GFP_KERNEL); |
369 | if (!ev) |
370 | return -ENOMEM; |
371 | |
372 | ev->type = UHID_OUTPUT; |
373 | ev->u.output.size = count; |
374 | ev->u.output.rtype = rtype; |
375 | memcpy(ev->u.output.data, buf, count); |
376 | |
377 | spin_lock_irqsave(&uhid->qlock, flags); |
378 | uhid_queue(uhid, ev); |
379 | spin_unlock_irqrestore(lock: &uhid->qlock, flags); |
380 | |
381 | return count; |
382 | } |
383 | |
384 | static int uhid_hid_output_report(struct hid_device *hid, __u8 *buf, |
385 | size_t count) |
386 | { |
387 | return uhid_hid_output_raw(hid, buf, count, report_type: HID_OUTPUT_REPORT); |
388 | } |
389 | |
390 | static const struct hid_ll_driver uhid_hid_driver = { |
391 | .start = uhid_hid_start, |
392 | .stop = uhid_hid_stop, |
393 | .open = uhid_hid_open, |
394 | .close = uhid_hid_close, |
395 | .parse = uhid_hid_parse, |
396 | .raw_request = uhid_hid_raw_request, |
397 | .output_report = uhid_hid_output_report, |
398 | .max_buffer_size = UHID_DATA_MAX, |
399 | }; |
400 | |
401 | #ifdef CONFIG_COMPAT |
402 | |
403 | /* Apparently we haven't stepped on these rakes enough times yet. */ |
404 | struct uhid_create_req_compat { |
405 | __u8 name[128]; |
406 | __u8 phys[64]; |
407 | __u8 uniq[64]; |
408 | |
409 | compat_uptr_t rd_data; |
410 | __u16 rd_size; |
411 | |
412 | __u16 bus; |
413 | __u32 vendor; |
414 | __u32 product; |
415 | __u32 version; |
416 | __u32 country; |
417 | } __attribute__((__packed__)); |
418 | |
419 | static int uhid_event_from_user(const char __user *buffer, size_t len, |
420 | struct uhid_event *event) |
421 | { |
422 | if (in_compat_syscall()) { |
423 | u32 type; |
424 | |
425 | if (get_user(type, buffer)) |
426 | return -EFAULT; |
427 | |
428 | if (type == UHID_CREATE) { |
429 | /* |
430 | * This is our messed up request with compat pointer. |
431 | * It is largish (more than 256 bytes) so we better |
432 | * allocate it from the heap. |
433 | */ |
434 | struct uhid_create_req_compat *compat; |
435 | |
436 | compat = kzalloc(size: sizeof(*compat), GFP_KERNEL); |
437 | if (!compat) |
438 | return -ENOMEM; |
439 | |
440 | buffer += sizeof(type); |
441 | len -= sizeof(type); |
442 | if (copy_from_user(to: compat, from: buffer, |
443 | min(len, sizeof(*compat)))) { |
444 | kfree(objp: compat); |
445 | return -EFAULT; |
446 | } |
447 | |
448 | /* Shuffle the data over to proper structure */ |
449 | event->type = type; |
450 | |
451 | memcpy(event->u.create.name, compat->name, |
452 | sizeof(compat->name)); |
453 | memcpy(event->u.create.phys, compat->phys, |
454 | sizeof(compat->phys)); |
455 | memcpy(event->u.create.uniq, compat->uniq, |
456 | sizeof(compat->uniq)); |
457 | |
458 | event->u.create.rd_data = compat_ptr(uptr: compat->rd_data); |
459 | event->u.create.rd_size = compat->rd_size; |
460 | |
461 | event->u.create.bus = compat->bus; |
462 | event->u.create.vendor = compat->vendor; |
463 | event->u.create.product = compat->product; |
464 | event->u.create.version = compat->version; |
465 | event->u.create.country = compat->country; |
466 | |
467 | kfree(objp: compat); |
468 | return 0; |
469 | } |
470 | /* All others can be copied directly */ |
471 | } |
472 | |
473 | if (copy_from_user(to: event, from: buffer, min(len, sizeof(*event)))) |
474 | return -EFAULT; |
475 | |
476 | return 0; |
477 | } |
478 | #else |
479 | static int uhid_event_from_user(const char __user *buffer, size_t len, |
480 | struct uhid_event *event) |
481 | { |
482 | if (copy_from_user(event, buffer, min(len, sizeof(*event)))) |
483 | return -EFAULT; |
484 | |
485 | return 0; |
486 | } |
487 | #endif |
488 | |
489 | static int uhid_dev_create2(struct uhid_device *uhid, |
490 | const struct uhid_event *ev) |
491 | { |
492 | struct hid_device *hid; |
493 | size_t rd_size, len; |
494 | void *rd_data; |
495 | int ret; |
496 | |
497 | if (uhid->hid) |
498 | return -EALREADY; |
499 | |
500 | rd_size = ev->u.create2.rd_size; |
501 | if (rd_size <= 0 || rd_size > HID_MAX_DESCRIPTOR_SIZE) |
502 | return -EINVAL; |
503 | |
504 | rd_data = kmemdup(p: ev->u.create2.rd_data, size: rd_size, GFP_KERNEL); |
505 | if (!rd_data) |
506 | return -ENOMEM; |
507 | |
508 | uhid->rd_size = rd_size; |
509 | uhid->rd_data = rd_data; |
510 | |
511 | hid = hid_allocate_device(); |
512 | if (IS_ERR(ptr: hid)) { |
513 | ret = PTR_ERR(ptr: hid); |
514 | goto err_free; |
515 | } |
516 | |
517 | /* @hid is zero-initialized, strncpy() is correct, strlcpy() not */ |
518 | len = min(sizeof(hid->name), sizeof(ev->u.create2.name)) - 1; |
519 | strncpy(p: hid->name, q: ev->u.create2.name, size: len); |
520 | len = min(sizeof(hid->phys), sizeof(ev->u.create2.phys)) - 1; |
521 | strncpy(p: hid->phys, q: ev->u.create2.phys, size: len); |
522 | len = min(sizeof(hid->uniq), sizeof(ev->u.create2.uniq)) - 1; |
523 | strncpy(p: hid->uniq, q: ev->u.create2.uniq, size: len); |
524 | |
525 | hid->ll_driver = &uhid_hid_driver; |
526 | hid->bus = ev->u.create2.bus; |
527 | hid->vendor = ev->u.create2.vendor; |
528 | hid->product = ev->u.create2.product; |
529 | hid->version = ev->u.create2.version; |
530 | hid->country = ev->u.create2.country; |
531 | hid->driver_data = uhid; |
532 | hid->dev.parent = uhid_misc.this_device; |
533 | |
534 | uhid->hid = hid; |
535 | uhid->running = true; |
536 | |
537 | /* Adding of a HID device is done through a worker, to allow HID drivers |
538 | * which use feature requests during .probe to work, without they would |
539 | * be blocked on devlock, which is held by uhid_char_write. |
540 | */ |
541 | schedule_work(work: &uhid->worker); |
542 | |
543 | return 0; |
544 | |
545 | err_free: |
546 | kfree(objp: uhid->rd_data); |
547 | uhid->rd_data = NULL; |
548 | uhid->rd_size = 0; |
549 | return ret; |
550 | } |
551 | |
552 | static int uhid_dev_create(struct uhid_device *uhid, |
553 | struct uhid_event *ev) |
554 | { |
555 | struct uhid_create_req orig; |
556 | |
557 | orig = ev->u.create; |
558 | |
559 | if (orig.rd_size <= 0 || orig.rd_size > HID_MAX_DESCRIPTOR_SIZE) |
560 | return -EINVAL; |
561 | if (copy_from_user(to: &ev->u.create2.rd_data, from: orig.rd_data, n: orig.rd_size)) |
562 | return -EFAULT; |
563 | |
564 | memcpy(ev->u.create2.name, orig.name, sizeof(orig.name)); |
565 | memcpy(ev->u.create2.phys, orig.phys, sizeof(orig.phys)); |
566 | memcpy(ev->u.create2.uniq, orig.uniq, sizeof(orig.uniq)); |
567 | ev->u.create2.rd_size = orig.rd_size; |
568 | ev->u.create2.bus = orig.bus; |
569 | ev->u.create2.vendor = orig.vendor; |
570 | ev->u.create2.product = orig.product; |
571 | ev->u.create2.version = orig.version; |
572 | ev->u.create2.country = orig.country; |
573 | |
574 | return uhid_dev_create2(uhid, ev); |
575 | } |
576 | |
577 | static int uhid_dev_destroy(struct uhid_device *uhid) |
578 | { |
579 | if (!uhid->hid) |
580 | return -EINVAL; |
581 | |
582 | WRITE_ONCE(uhid->running, false); |
583 | wake_up_interruptible(&uhid->report_wait); |
584 | |
585 | cancel_work_sync(work: &uhid->worker); |
586 | |
587 | hid_destroy_device(uhid->hid); |
588 | uhid->hid = NULL; |
589 | kfree(objp: uhid->rd_data); |
590 | |
591 | return 0; |
592 | } |
593 | |
594 | static int uhid_dev_input(struct uhid_device *uhid, struct uhid_event *ev) |
595 | { |
596 | if (!READ_ONCE(uhid->running)) |
597 | return -EINVAL; |
598 | |
599 | hid_input_report(hid: uhid->hid, type: HID_INPUT_REPORT, data: ev->u.input.data, |
600 | min_t(size_t, ev->u.input.size, UHID_DATA_MAX), interrupt: 0); |
601 | |
602 | return 0; |
603 | } |
604 | |
605 | static int uhid_dev_input2(struct uhid_device *uhid, struct uhid_event *ev) |
606 | { |
607 | if (!READ_ONCE(uhid->running)) |
608 | return -EINVAL; |
609 | |
610 | hid_input_report(hid: uhid->hid, type: HID_INPUT_REPORT, data: ev->u.input2.data, |
611 | min_t(size_t, ev->u.input2.size, UHID_DATA_MAX), interrupt: 0); |
612 | |
613 | return 0; |
614 | } |
615 | |
616 | static int uhid_dev_get_report_reply(struct uhid_device *uhid, |
617 | struct uhid_event *ev) |
618 | { |
619 | if (!READ_ONCE(uhid->running)) |
620 | return -EINVAL; |
621 | |
622 | uhid_report_wake_up(uhid, id: ev->u.get_report_reply.id, ev); |
623 | return 0; |
624 | } |
625 | |
626 | static int uhid_dev_set_report_reply(struct uhid_device *uhid, |
627 | struct uhid_event *ev) |
628 | { |
629 | if (!READ_ONCE(uhid->running)) |
630 | return -EINVAL; |
631 | |
632 | uhid_report_wake_up(uhid, id: ev->u.set_report_reply.id, ev); |
633 | return 0; |
634 | } |
635 | |
636 | static int uhid_char_open(struct inode *inode, struct file *file) |
637 | { |
638 | struct uhid_device *uhid; |
639 | |
640 | uhid = kzalloc(size: sizeof(*uhid), GFP_KERNEL); |
641 | if (!uhid) |
642 | return -ENOMEM; |
643 | |
644 | mutex_init(&uhid->devlock); |
645 | mutex_init(&uhid->report_lock); |
646 | spin_lock_init(&uhid->qlock); |
647 | init_waitqueue_head(&uhid->waitq); |
648 | init_waitqueue_head(&uhid->report_wait); |
649 | uhid->running = false; |
650 | INIT_WORK(&uhid->worker, uhid_device_add_worker); |
651 | |
652 | file->private_data = uhid; |
653 | stream_open(inode, filp: file); |
654 | |
655 | return 0; |
656 | } |
657 | |
658 | static int uhid_char_release(struct inode *inode, struct file *file) |
659 | { |
660 | struct uhid_device *uhid = file->private_data; |
661 | unsigned int i; |
662 | |
663 | uhid_dev_destroy(uhid); |
664 | |
665 | for (i = 0; i < UHID_BUFSIZE; ++i) |
666 | kfree(objp: uhid->outq[i]); |
667 | |
668 | kfree(objp: uhid); |
669 | |
670 | return 0; |
671 | } |
672 | |
673 | static ssize_t uhid_char_read(struct file *file, char __user *buffer, |
674 | size_t count, loff_t *ppos) |
675 | { |
676 | struct uhid_device *uhid = file->private_data; |
677 | int ret; |
678 | unsigned long flags; |
679 | size_t len; |
680 | |
681 | /* they need at least the "type" member of uhid_event */ |
682 | if (count < sizeof(__u32)) |
683 | return -EINVAL; |
684 | |
685 | try_again: |
686 | if (file->f_flags & O_NONBLOCK) { |
687 | if (uhid->head == uhid->tail) |
688 | return -EAGAIN; |
689 | } else { |
690 | ret = wait_event_interruptible(uhid->waitq, |
691 | uhid->head != uhid->tail); |
692 | if (ret) |
693 | return ret; |
694 | } |
695 | |
696 | ret = mutex_lock_interruptible(&uhid->devlock); |
697 | if (ret) |
698 | return ret; |
699 | |
700 | if (uhid->head == uhid->tail) { |
701 | mutex_unlock(lock: &uhid->devlock); |
702 | goto try_again; |
703 | } else { |
704 | len = min(count, sizeof(**uhid->outq)); |
705 | if (copy_to_user(to: buffer, from: uhid->outq[uhid->tail], n: len)) { |
706 | ret = -EFAULT; |
707 | } else { |
708 | kfree(objp: uhid->outq[uhid->tail]); |
709 | uhid->outq[uhid->tail] = NULL; |
710 | |
711 | spin_lock_irqsave(&uhid->qlock, flags); |
712 | uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE; |
713 | spin_unlock_irqrestore(lock: &uhid->qlock, flags); |
714 | } |
715 | } |
716 | |
717 | mutex_unlock(lock: &uhid->devlock); |
718 | return ret ? ret : len; |
719 | } |
720 | |
721 | static ssize_t uhid_char_write(struct file *file, const char __user *buffer, |
722 | size_t count, loff_t *ppos) |
723 | { |
724 | struct uhid_device *uhid = file->private_data; |
725 | int ret; |
726 | size_t len; |
727 | |
728 | /* we need at least the "type" member of uhid_event */ |
729 | if (count < sizeof(__u32)) |
730 | return -EINVAL; |
731 | |
732 | ret = mutex_lock_interruptible(&uhid->devlock); |
733 | if (ret) |
734 | return ret; |
735 | |
736 | memset(&uhid->input_buf, 0, sizeof(uhid->input_buf)); |
737 | len = min(count, sizeof(uhid->input_buf)); |
738 | |
739 | ret = uhid_event_from_user(buffer, len, event: &uhid->input_buf); |
740 | if (ret) |
741 | goto unlock; |
742 | |
743 | switch (uhid->input_buf.type) { |
744 | case UHID_CREATE: |
745 | /* |
746 | * 'struct uhid_create_req' contains a __user pointer which is |
747 | * copied from, so it's unsafe to allow this with elevated |
748 | * privileges (e.g. from a setuid binary) or via kernel_write(). |
749 | */ |
750 | if (file->f_cred != current_cred()) { |
751 | pr_err_once("UHID_CREATE from different security context by process %d (%s), this is not allowed.\n" , |
752 | task_tgid_vnr(current), current->comm); |
753 | ret = -EACCES; |
754 | goto unlock; |
755 | } |
756 | ret = uhid_dev_create(uhid, ev: &uhid->input_buf); |
757 | break; |
758 | case UHID_CREATE2: |
759 | ret = uhid_dev_create2(uhid, ev: &uhid->input_buf); |
760 | break; |
761 | case UHID_DESTROY: |
762 | ret = uhid_dev_destroy(uhid); |
763 | break; |
764 | case UHID_INPUT: |
765 | ret = uhid_dev_input(uhid, ev: &uhid->input_buf); |
766 | break; |
767 | case UHID_INPUT2: |
768 | ret = uhid_dev_input2(uhid, ev: &uhid->input_buf); |
769 | break; |
770 | case UHID_GET_REPORT_REPLY: |
771 | ret = uhid_dev_get_report_reply(uhid, ev: &uhid->input_buf); |
772 | break; |
773 | case UHID_SET_REPORT_REPLY: |
774 | ret = uhid_dev_set_report_reply(uhid, ev: &uhid->input_buf); |
775 | break; |
776 | default: |
777 | ret = -EOPNOTSUPP; |
778 | } |
779 | |
780 | unlock: |
781 | mutex_unlock(lock: &uhid->devlock); |
782 | |
783 | /* return "count" not "len" to not confuse the caller */ |
784 | return ret ? ret : count; |
785 | } |
786 | |
787 | static __poll_t uhid_char_poll(struct file *file, poll_table *wait) |
788 | { |
789 | struct uhid_device *uhid = file->private_data; |
790 | __poll_t mask = EPOLLOUT | EPOLLWRNORM; /* uhid is always writable */ |
791 | |
792 | poll_wait(filp: file, wait_address: &uhid->waitq, p: wait); |
793 | |
794 | if (uhid->head != uhid->tail) |
795 | mask |= EPOLLIN | EPOLLRDNORM; |
796 | |
797 | return mask; |
798 | } |
799 | |
800 | static const struct file_operations uhid_fops = { |
801 | .owner = THIS_MODULE, |
802 | .open = uhid_char_open, |
803 | .release = uhid_char_release, |
804 | .read = uhid_char_read, |
805 | .write = uhid_char_write, |
806 | .poll = uhid_char_poll, |
807 | .llseek = no_llseek, |
808 | }; |
809 | |
810 | static struct miscdevice uhid_misc = { |
811 | .fops = &uhid_fops, |
812 | .minor = UHID_MINOR, |
813 | .name = UHID_NAME, |
814 | }; |
815 | module_misc_device(uhid_misc); |
816 | |
817 | MODULE_LICENSE("GPL" ); |
818 | MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>" ); |
819 | MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem" ); |
820 | MODULE_ALIAS_MISCDEV(UHID_MINOR); |
821 | MODULE_ALIAS("devname:" UHID_NAME); |
822 | |