Commit | Line | Data |
---|---|---|
66e3e591 KP |
1 | /* |
2 | * chaoskey - driver for ChaosKey device from Altus Metrum. | |
3 | * | |
4 | * This device provides true random numbers using a noise source based | |
5 | * on a reverse-biased p-n junction in avalanche breakdown. More | |
6 | * details can be found at http://chaoskey.org | |
7 | * | |
8 | * The driver connects to the kernel hardware RNG interface to provide | |
9 | * entropy for /dev/random and other kernel activities. It also offers | |
10 | * a separate /dev/ entry to allow for direct access to the random | |
11 | * bit stream. | |
12 | * | |
13 | * Copyright © 2015 Keith Packard <keithp@keithp.com> | |
14 | * | |
15 | * This program is free software; you can redistribute it and/or modify | |
16 | * it under the terms of the GNU General Public License as published by | |
17 | * the Free Software Foundation; version 2 of the License. | |
18 | * | |
19 | * This program is distributed in the hope that it will be useful, but | |
20 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
22 | * General Public License for more details. | |
23 | */ | |
24 | ||
25 | #include <linux/module.h> | |
26 | #include <linux/slab.h> | |
27 | #include <linux/usb.h> | |
28 | #include <linux/wait.h> | |
29 | #include <linux/hw_random.h> | |
8b86ed07 KP |
30 | #include <linux/mutex.h> |
31 | #include <linux/uaccess.h> | |
66e3e591 KP |
32 | |
33 | static struct usb_driver chaoskey_driver; | |
34 | static struct usb_class_driver chaoskey_class; | |
35 | static int chaoskey_rng_read(struct hwrng *rng, void *data, | |
36 | size_t max, bool wait); | |
37 | ||
38 | #define usb_dbg(usb_if, format, arg...) \ | |
39 | dev_dbg(&(usb_if)->dev, format, ## arg) | |
40 | ||
41 | #define usb_err(usb_if, format, arg...) \ | |
42 | dev_err(&(usb_if)->dev, format, ## arg) | |
43 | ||
44 | /* Version Information */ | |
45 | #define DRIVER_VERSION "v0.1" | |
46 | #define DRIVER_AUTHOR "Keith Packard, keithp@keithp.com" | |
47 | #define DRIVER_DESC "Altus Metrum ChaosKey driver" | |
48 | #define DRIVER_SHORT "chaoskey" | |
49 | ||
50 | MODULE_VERSION(DRIVER_VERSION); | |
51 | MODULE_AUTHOR(DRIVER_AUTHOR); | |
52 | MODULE_DESCRIPTION(DRIVER_DESC); | |
53 | MODULE_LICENSE("GPL"); | |
54 | ||
55 | #define CHAOSKEY_VENDOR_ID 0x1d50 /* OpenMoko */ | |
56 | #define CHAOSKEY_PRODUCT_ID 0x60c6 /* ChaosKey */ | |
57 | ||
58 | #define CHAOSKEY_BUF_LEN 64 /* max size of USB full speed packet */ | |
59 | ||
60 | #define NAK_TIMEOUT (HZ) /* stall/wait timeout for device */ | |
61 | ||
62 | #ifdef CONFIG_USB_DYNAMIC_MINORS | |
63 | #define USB_CHAOSKEY_MINOR_BASE 0 | |
64 | #else | |
65 | ||
66 | /* IOWARRIOR_MINOR_BASE + 16, not official yet */ | |
67 | #define USB_CHAOSKEY_MINOR_BASE 224 | |
68 | #endif | |
69 | ||
70 | static const struct usb_device_id chaoskey_table[] = { | |
71 | { USB_DEVICE(CHAOSKEY_VENDOR_ID, CHAOSKEY_PRODUCT_ID) }, | |
72 | { }, | |
73 | }; | |
74 | MODULE_DEVICE_TABLE(usb, chaoskey_table); | |
75 | ||
0ca10122 ON |
76 | static void chaos_read_callback(struct urb *urb); |
77 | ||
66e3e591 KP |
78 | /* Driver-local specific stuff */ |
79 | struct chaoskey { | |
80 | struct usb_interface *interface; | |
81 | char in_ep; | |
82 | struct mutex lock; | |
83 | struct mutex rng_lock; | |
84 | int open; /* open count */ | |
0ca10122 ON |
85 | bool present; /* device not disconnected */ |
86 | bool reading; /* ongoing IO */ | |
66e3e591 KP |
87 | int size; /* size of buf */ |
88 | int valid; /* bytes of buf read */ | |
89 | int used; /* bytes of buf consumed */ | |
90 | char *name; /* product + serial */ | |
91 | struct hwrng hwrng; /* Embedded struct for hwrng */ | |
92 | int hwrng_registered; /* registered with hwrng API */ | |
93 | wait_queue_head_t wait_q; /* for timeouts */ | |
0ca10122 | 94 | struct urb *urb; /* for performing IO */ |
66e3e591 KP |
95 | char *buf; |
96 | }; | |
97 | ||
98 | static void chaoskey_free(struct chaoskey *dev) | |
99 | { | |
0a15e24c ON |
100 | if (dev) { |
101 | usb_dbg(dev->interface, "free"); | |
0ca10122 | 102 | usb_free_urb(dev->urb); |
0a15e24c ON |
103 | kfree(dev->name); |
104 | kfree(dev->buf); | |
105 | kfree(dev); | |
106 | } | |
66e3e591 KP |
107 | } |
108 | ||
109 | static int chaoskey_probe(struct usb_interface *interface, | |
110 | const struct usb_device_id *id) | |
111 | { | |
112 | struct usb_device *udev = interface_to_usbdev(interface); | |
113 | struct usb_host_interface *altsetting = interface->cur_altsetting; | |
114 | int i; | |
115 | int in_ep = -1; | |
116 | struct chaoskey *dev; | |
0a15e24c | 117 | int result = -ENOMEM; |
66e3e591 KP |
118 | int size; |
119 | ||
120 | usb_dbg(interface, "probe %s-%s", udev->product, udev->serial); | |
121 | ||
122 | /* Find the first bulk IN endpoint and its packet size */ | |
123 | for (i = 0; i < altsetting->desc.bNumEndpoints; i++) { | |
124 | if (usb_endpoint_is_bulk_in(&altsetting->endpoint[i].desc)) { | |
8b86ed07 KP |
125 | in_ep = usb_endpoint_num(&altsetting->endpoint[i].desc); |
126 | size = usb_endpoint_maxp(&altsetting->endpoint[i].desc); | |
66e3e591 KP |
127 | break; |
128 | } | |
129 | } | |
130 | ||
131 | /* Validate endpoint and size */ | |
132 | if (in_ep == -1) { | |
133 | usb_dbg(interface, "no IN endpoint found"); | |
134 | return -ENODEV; | |
135 | } | |
136 | if (size <= 0) { | |
137 | usb_dbg(interface, "invalid size (%d)", size); | |
138 | return -ENODEV; | |
139 | } | |
140 | ||
141 | if (size > CHAOSKEY_BUF_LEN) { | |
142 | usb_dbg(interface, "size reduced from %d to %d\n", | |
143 | size, CHAOSKEY_BUF_LEN); | |
144 | size = CHAOSKEY_BUF_LEN; | |
145 | } | |
146 | ||
147 | /* Looks good, allocate and initialize */ | |
148 | ||
149 | dev = kzalloc(sizeof(struct chaoskey), GFP_KERNEL); | |
150 | ||
151 | if (dev == NULL) | |
0a15e24c | 152 | goto out; |
66e3e591 KP |
153 | |
154 | dev->buf = kmalloc(size, GFP_KERNEL); | |
155 | ||
0a15e24c ON |
156 | if (dev->buf == NULL) |
157 | goto out; | |
66e3e591 | 158 | |
0ca10122 ON |
159 | dev->urb = usb_alloc_urb(0, GFP_KERNEL); |
160 | ||
161 | if (!dev->urb) | |
162 | goto out; | |
163 | ||
164 | usb_fill_bulk_urb(dev->urb, | |
165 | udev, | |
166 | usb_rcvbulkpipe(udev, in_ep), | |
167 | dev->buf, | |
168 | size, | |
169 | chaos_read_callback, | |
170 | dev); | |
171 | ||
66e3e591 KP |
172 | /* Construct a name using the product and serial values. Each |
173 | * device needs a unique name for the hwrng code | |
174 | */ | |
175 | ||
176 | if (udev->product && udev->serial) { | |
177 | dev->name = kmalloc(strlen(udev->product) + 1 + | |
178 | strlen(udev->serial) + 1, GFP_KERNEL); | |
0a15e24c ON |
179 | if (dev->name == NULL) |
180 | goto out; | |
66e3e591 KP |
181 | |
182 | strcpy(dev->name, udev->product); | |
183 | strcat(dev->name, "-"); | |
184 | strcat(dev->name, udev->serial); | |
185 | } | |
186 | ||
187 | dev->interface = interface; | |
188 | ||
189 | dev->in_ep = in_ep; | |
190 | ||
191 | dev->size = size; | |
192 | dev->present = 1; | |
193 | ||
194 | init_waitqueue_head(&dev->wait_q); | |
195 | ||
196 | mutex_init(&dev->lock); | |
197 | mutex_init(&dev->rng_lock); | |
198 | ||
199 | usb_set_intfdata(interface, dev); | |
200 | ||
201 | result = usb_register_dev(interface, &chaoskey_class); | |
202 | if (result) { | |
203 | usb_err(interface, "Unable to allocate minor number."); | |
0a15e24c | 204 | goto out; |
66e3e591 KP |
205 | } |
206 | ||
207 | dev->hwrng.name = dev->name ? dev->name : chaoskey_driver.name; | |
208 | dev->hwrng.read = chaoskey_rng_read; | |
209 | ||
210 | /* Set the 'quality' metric. Quality is measured in units of | |
211 | * 1/1024's of a bit ("mills"). This should be set to 1024, | |
212 | * but there is a bug in the hwrng core which masks it with | |
213 | * 1023. | |
214 | * | |
215 | * The patch that has been merged to the crypto development | |
216 | * tree for that bug limits the value to 1024 at most, so by | |
217 | * setting this to 1024 + 1023, we get 1023 before the fix is | |
218 | * merged and 1024 afterwards. We'll patch this driver once | |
219 | * both bits of code are in the same tree. | |
220 | */ | |
221 | dev->hwrng.quality = 1024 + 1023; | |
222 | ||
223 | dev->hwrng_registered = (hwrng_register(&dev->hwrng) == 0); | |
224 | if (!dev->hwrng_registered) | |
225 | usb_err(interface, "Unable to register with hwrng"); | |
226 | ||
227 | usb_enable_autosuspend(udev); | |
228 | ||
229 | usb_dbg(interface, "chaoskey probe success, size %d", dev->size); | |
230 | return 0; | |
0a15e24c ON |
231 | |
232 | out: | |
233 | usb_set_intfdata(interface, NULL); | |
234 | chaoskey_free(dev); | |
235 | return result; | |
66e3e591 KP |
236 | } |
237 | ||
238 | static void chaoskey_disconnect(struct usb_interface *interface) | |
239 | { | |
240 | struct chaoskey *dev; | |
241 | ||
242 | usb_dbg(interface, "disconnect"); | |
243 | dev = usb_get_intfdata(interface); | |
244 | if (!dev) { | |
245 | usb_dbg(interface, "disconnect failed - no dev"); | |
246 | return; | |
247 | } | |
248 | ||
249 | if (dev->hwrng_registered) | |
250 | hwrng_unregister(&dev->hwrng); | |
251 | ||
252 | usb_deregister_dev(interface, &chaoskey_class); | |
253 | ||
254 | usb_set_intfdata(interface, NULL); | |
255 | mutex_lock(&dev->lock); | |
256 | ||
257 | dev->present = 0; | |
0ca10122 | 258 | usb_poison_urb(dev->urb); |
66e3e591 KP |
259 | |
260 | if (!dev->open) { | |
261 | mutex_unlock(&dev->lock); | |
262 | chaoskey_free(dev); | |
263 | } else | |
264 | mutex_unlock(&dev->lock); | |
265 | ||
266 | usb_dbg(interface, "disconnect done"); | |
267 | } | |
268 | ||
269 | static int chaoskey_open(struct inode *inode, struct file *file) | |
270 | { | |
271 | struct chaoskey *dev; | |
272 | struct usb_interface *interface; | |
273 | ||
274 | /* get the interface from minor number and driver information */ | |
275 | interface = usb_find_interface(&chaoskey_driver, iminor(inode)); | |
276 | if (!interface) | |
277 | return -ENODEV; | |
278 | ||
279 | usb_dbg(interface, "open"); | |
280 | ||
281 | dev = usb_get_intfdata(interface); | |
282 | if (!dev) { | |
283 | usb_dbg(interface, "open (dev)"); | |
284 | return -ENODEV; | |
285 | } | |
286 | ||
287 | file->private_data = dev; | |
288 | mutex_lock(&dev->lock); | |
289 | ++dev->open; | |
290 | mutex_unlock(&dev->lock); | |
291 | ||
292 | usb_dbg(interface, "open success"); | |
293 | return 0; | |
294 | } | |
295 | ||
296 | static int chaoskey_release(struct inode *inode, struct file *file) | |
297 | { | |
298 | struct chaoskey *dev = file->private_data; | |
299 | struct usb_interface *interface; | |
300 | ||
301 | if (dev == NULL) | |
302 | return -ENODEV; | |
303 | ||
304 | interface = dev->interface; | |
305 | ||
306 | usb_dbg(interface, "release"); | |
307 | ||
308 | mutex_lock(&dev->lock); | |
309 | ||
310 | usb_dbg(interface, "open count at release is %d", dev->open); | |
311 | ||
312 | if (dev->open <= 0) { | |
313 | usb_dbg(interface, "invalid open count (%d)", dev->open); | |
314 | mutex_unlock(&dev->lock); | |
315 | return -ENODEV; | |
316 | } | |
317 | ||
318 | --dev->open; | |
319 | ||
320 | if (!dev->present) { | |
321 | if (dev->open == 0) { | |
322 | mutex_unlock(&dev->lock); | |
323 | chaoskey_free(dev); | |
324 | } else | |
325 | mutex_unlock(&dev->lock); | |
326 | } else | |
327 | mutex_unlock(&dev->lock); | |
328 | ||
329 | usb_dbg(interface, "release success"); | |
330 | return 0; | |
331 | } | |
332 | ||
0ca10122 ON |
333 | static void chaos_read_callback(struct urb *urb) |
334 | { | |
335 | struct chaoskey *dev = urb->context; | |
336 | int status = urb->status; | |
337 | ||
338 | usb_dbg(dev->interface, "callback status (%d)", status); | |
339 | ||
340 | if (status == 0) | |
341 | dev->valid = urb->actual_length; | |
342 | else | |
343 | dev->valid = 0; | |
344 | ||
345 | dev->used = 0; | |
346 | ||
347 | /* must be seen first before validity is announced */ | |
348 | smp_wmb(); | |
349 | ||
350 | dev->reading = false; | |
351 | wake_up(&dev->wait_q); | |
352 | } | |
353 | ||
66e3e591 KP |
354 | /* Fill the buffer. Called with dev->lock held |
355 | */ | |
356 | static int _chaoskey_fill(struct chaoskey *dev) | |
357 | { | |
358 | DEFINE_WAIT(wait); | |
359 | int result; | |
66e3e591 KP |
360 | |
361 | usb_dbg(dev->interface, "fill"); | |
362 | ||
363 | /* Return immediately if someone called before the buffer was | |
364 | * empty */ | |
365 | if (dev->valid != dev->used) { | |
366 | usb_dbg(dev->interface, "not empty yet (valid %d used %d)", | |
367 | dev->valid, dev->used); | |
368 | return 0; | |
369 | } | |
370 | ||
371 | /* Bail if the device has been removed */ | |
372 | if (!dev->present) { | |
373 | usb_dbg(dev->interface, "device not present"); | |
374 | return -ENODEV; | |
375 | } | |
376 | ||
377 | /* Make sure the device is awake */ | |
378 | result = usb_autopm_get_interface(dev->interface); | |
379 | if (result) { | |
380 | usb_dbg(dev->interface, "wakeup failed (result %d)", result); | |
381 | return result; | |
382 | } | |
383 | ||
0ca10122 ON |
384 | dev->reading = true; |
385 | result = usb_submit_urb(dev->urb, GFP_KERNEL); | |
386 | if (result < 0) { | |
387 | result = usb_translate_errors(result); | |
388 | dev->reading = false; | |
389 | goto out; | |
390 | } | |
391 | ||
392 | result = wait_event_interruptible_timeout( | |
393 | dev->wait_q, | |
394 | !dev->reading, | |
395 | NAK_TIMEOUT); | |
66e3e591 | 396 | |
0ca10122 ON |
397 | if (result < 0) |
398 | goto out; | |
399 | ||
400 | if (result == 0) | |
401 | result = -ETIMEDOUT; | |
402 | else | |
403 | result = dev->valid; | |
404 | out: | |
66e3e591 KP |
405 | /* Let the device go back to sleep eventually */ |
406 | usb_autopm_put_interface(dev->interface); | |
407 | ||
0ca10122 | 408 | usb_dbg(dev->interface, "read %d bytes", dev->valid); |
66e3e591 KP |
409 | |
410 | return result; | |
411 | } | |
412 | ||
413 | static ssize_t chaoskey_read(struct file *file, | |
414 | char __user *buffer, | |
415 | size_t count, | |
416 | loff_t *ppos) | |
417 | { | |
418 | struct chaoskey *dev; | |
419 | ssize_t read_count = 0; | |
420 | int this_time; | |
421 | int result = 0; | |
422 | unsigned long remain; | |
423 | ||
424 | dev = file->private_data; | |
425 | ||
426 | if (dev == NULL || !dev->present) | |
427 | return -ENODEV; | |
428 | ||
429 | usb_dbg(dev->interface, "read %zu", count); | |
430 | ||
431 | while (count > 0) { | |
432 | ||
433 | /* Grab the rng_lock briefly to ensure that the hwrng interface | |
434 | * gets priority over other user access | |
435 | */ | |
436 | result = mutex_lock_interruptible(&dev->rng_lock); | |
437 | if (result) | |
438 | goto bail; | |
439 | mutex_unlock(&dev->rng_lock); | |
440 | ||
441 | result = mutex_lock_interruptible(&dev->lock); | |
442 | if (result) | |
443 | goto bail; | |
444 | if (dev->valid == dev->used) { | |
445 | result = _chaoskey_fill(dev); | |
0ca10122 | 446 | if (result < 0) { |
66e3e591 KP |
447 | mutex_unlock(&dev->lock); |
448 | goto bail; | |
449 | } | |
450 | } | |
451 | ||
452 | this_time = dev->valid - dev->used; | |
453 | if (this_time > count) | |
454 | this_time = count; | |
455 | ||
456 | remain = copy_to_user(buffer, dev->buf + dev->used, this_time); | |
457 | if (remain) { | |
458 | result = -EFAULT; | |
459 | ||
460 | /* Consume the bytes that were copied so we don't leak | |
461 | * data to user space | |
462 | */ | |
463 | dev->used += this_time - remain; | |
464 | mutex_unlock(&dev->lock); | |
465 | goto bail; | |
466 | } | |
467 | ||
468 | count -= this_time; | |
469 | read_count += this_time; | |
470 | buffer += this_time; | |
471 | dev->used += this_time; | |
472 | mutex_unlock(&dev->lock); | |
473 | } | |
474 | bail: | |
475 | if (read_count) { | |
476 | usb_dbg(dev->interface, "read %zu bytes", read_count); | |
477 | return read_count; | |
478 | } | |
479 | usb_dbg(dev->interface, "empty read, result %d", result); | |
0ca10122 ON |
480 | if (result == -ETIMEDOUT) |
481 | result = -EAGAIN; | |
66e3e591 KP |
482 | return result; |
483 | } | |
484 | ||
485 | static int chaoskey_rng_read(struct hwrng *rng, void *data, | |
486 | size_t max, bool wait) | |
487 | { | |
488 | struct chaoskey *dev = container_of(rng, struct chaoskey, hwrng); | |
489 | int this_time; | |
490 | ||
491 | usb_dbg(dev->interface, "rng_read max %zu wait %d", max, wait); | |
492 | ||
493 | if (!dev->present) { | |
494 | usb_dbg(dev->interface, "device not present"); | |
495 | return 0; | |
496 | } | |
497 | ||
498 | /* Hold the rng_lock until we acquire the device lock so that | |
499 | * this operation gets priority over other user access to the | |
500 | * device | |
501 | */ | |
502 | mutex_lock(&dev->rng_lock); | |
503 | ||
504 | mutex_lock(&dev->lock); | |
505 | ||
506 | mutex_unlock(&dev->rng_lock); | |
507 | ||
508 | /* Try to fill the buffer if empty. It doesn't actually matter | |
509 | * if _chaoskey_fill works; we'll just return zero bytes as | |
510 | * the buffer will still be empty | |
511 | */ | |
512 | if (dev->valid == dev->used) | |
513 | (void) _chaoskey_fill(dev); | |
514 | ||
515 | this_time = dev->valid - dev->used; | |
516 | if (this_time > max) | |
517 | this_time = max; | |
518 | ||
1d5c47f5 | 519 | memcpy(data, dev->buf + dev->used, this_time); |
66e3e591 KP |
520 | |
521 | dev->used += this_time; | |
522 | ||
523 | mutex_unlock(&dev->lock); | |
524 | ||
525 | usb_dbg(dev->interface, "rng_read this_time %d\n", this_time); | |
526 | return this_time; | |
527 | } | |
528 | ||
529 | #ifdef CONFIG_PM | |
530 | static int chaoskey_suspend(struct usb_interface *interface, | |
531 | pm_message_t message) | |
532 | { | |
533 | usb_dbg(interface, "suspend"); | |
534 | return 0; | |
535 | } | |
536 | ||
537 | static int chaoskey_resume(struct usb_interface *interface) | |
538 | { | |
539 | usb_dbg(interface, "resume"); | |
540 | return 0; | |
541 | } | |
542 | #else | |
543 | #define chaoskey_suspend NULL | |
544 | #define chaoskey_resume NULL | |
545 | #endif | |
546 | ||
547 | /* file operation pointers */ | |
548 | static const struct file_operations chaoskey_fops = { | |
549 | .owner = THIS_MODULE, | |
550 | .read = chaoskey_read, | |
551 | .open = chaoskey_open, | |
552 | .release = chaoskey_release, | |
553 | .llseek = default_llseek, | |
554 | }; | |
555 | ||
556 | /* class driver information */ | |
557 | static struct usb_class_driver chaoskey_class = { | |
558 | .name = "chaoskey%d", | |
559 | .fops = &chaoskey_fops, | |
560 | .minor_base = USB_CHAOSKEY_MINOR_BASE, | |
561 | }; | |
562 | ||
563 | /* usb specific object needed to register this driver with the usb subsystem */ | |
564 | static struct usb_driver chaoskey_driver = { | |
565 | .name = DRIVER_SHORT, | |
566 | .probe = chaoskey_probe, | |
567 | .disconnect = chaoskey_disconnect, | |
568 | .suspend = chaoskey_suspend, | |
569 | .resume = chaoskey_resume, | |
570 | .reset_resume = chaoskey_resume, | |
571 | .id_table = chaoskey_table, | |
572 | .supports_autosuspend = 1, | |
573 | }; | |
574 | ||
575 | module_usb_driver(chaoskey_driver); | |
576 |