Commit | Line | Data |
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844dd05f MB |
1 | /* |
2 | Added support for the AMD Geode LX RNG | |
3 | (c) Copyright 2004-2005 Advanced Micro Devices, Inc. | |
4 | ||
5 | derived from | |
6 | ||
7 | Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG) | |
8 | (c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com> | |
9 | ||
10 | derived from | |
11 | ||
12 | Hardware driver for the AMD 768 Random Number Generator (RNG) | |
13 | (c) Copyright 2001 Red Hat Inc <alan@redhat.com> | |
14 | ||
15 | derived from | |
16 | ||
17 | Hardware driver for Intel i810 Random Number Generator (RNG) | |
18 | Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com> | |
19 | Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com> | |
20 | ||
21 | Added generic RNG API | |
eb032b98 | 22 | Copyright 2006 Michael Buesch <m@bues.ch> |
844dd05f MB |
23 | Copyright 2005 (c) MontaVista Software, Inc. |
24 | ||
25 | Please read Documentation/hw_random.txt for details on use. | |
26 | ||
27 | ---------------------------------------------------------- | |
28 | This software may be used and distributed according to the terms | |
29 | of the GNU General Public License, incorporated herein by reference. | |
30 | ||
31 | */ | |
32 | ||
33 | ||
34 | #include <linux/device.h> | |
35 | #include <linux/hw_random.h> | |
36 | #include <linux/module.h> | |
37 | #include <linux/kernel.h> | |
38 | #include <linux/fs.h> | |
914e2637 | 39 | #include <linux/sched.h> |
844dd05f | 40 | #include <linux/miscdevice.h> |
be4000bc | 41 | #include <linux/kthread.h> |
844dd05f | 42 | #include <linux/delay.h> |
f7f154f1 | 43 | #include <linux/slab.h> |
d9e79726 | 44 | #include <linux/random.h> |
3a2c0ba5 | 45 | #include <linux/err.h> |
844dd05f MB |
46 | #include <asm/uaccess.h> |
47 | ||
48 | ||
49 | #define RNG_MODULE_NAME "hw_random" | |
50 | #define PFX RNG_MODULE_NAME ": " | |
51 | #define RNG_MISCDEV_MINOR 183 /* official */ | |
52 | ||
53 | ||
54 | static struct hwrng *current_rng; | |
be4000bc | 55 | static struct task_struct *hwrng_fill; |
844dd05f | 56 | static LIST_HEAD(rng_list); |
9372b35e | 57 | /* Protects rng_list and current_rng */ |
844dd05f | 58 | static DEFINE_MUTEX(rng_mutex); |
9372b35e RR |
59 | /* Protects rng read functions, data_avail, rng_buffer and rng_fillbuf */ |
60 | static DEFINE_MUTEX(reading_mutex); | |
9996508b | 61 | static int data_avail; |
be4000bc | 62 | static u8 *rng_buffer, *rng_fillbuf; |
0f734e6e TD |
63 | static unsigned short current_quality; |
64 | static unsigned short default_quality; /* = 0; default to "off" */ | |
be4000bc TD |
65 | |
66 | module_param(current_quality, ushort, 0644); | |
67 | MODULE_PARM_DESC(current_quality, | |
68 | "current hwrng entropy estimation per mill"); | |
0f734e6e TD |
69 | module_param(default_quality, ushort, 0644); |
70 | MODULE_PARM_DESC(default_quality, | |
71 | "default entropy content of hwrng per mill"); | |
be4000bc TD |
72 | |
73 | static void start_khwrngd(void); | |
f7f154f1 | 74 | |
d3cc7996 AS |
75 | static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size, |
76 | int wait); | |
77 | ||
f7f154f1 RR |
78 | static size_t rng_buffer_size(void) |
79 | { | |
80 | return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES; | |
81 | } | |
844dd05f | 82 | |
d3cc7996 AS |
83 | static void add_early_randomness(struct hwrng *rng) |
84 | { | |
85 | unsigned char bytes[16]; | |
86 | int bytes_read; | |
87 | ||
9372b35e | 88 | mutex_lock(&reading_mutex); |
d3cc7996 | 89 | bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1); |
9372b35e | 90 | mutex_unlock(&reading_mutex); |
d3cc7996 AS |
91 | if (bytes_read > 0) |
92 | add_device_randomness(bytes, bytes_read); | |
93 | } | |
94 | ||
3a2c0ba5 RR |
95 | static inline void cleanup_rng(struct kref *kref) |
96 | { | |
97 | struct hwrng *rng = container_of(kref, struct hwrng, ref); | |
98 | ||
99 | if (rng->cleanup) | |
100 | rng->cleanup(rng); | |
101 | } | |
102 | ||
103 | static void set_current_rng(struct hwrng *rng) | |
104 | { | |
105 | BUG_ON(!mutex_is_locked(&rng_mutex)); | |
106 | kref_get(&rng->ref); | |
107 | current_rng = rng; | |
108 | } | |
109 | ||
110 | static void drop_current_rng(void) | |
111 | { | |
112 | BUG_ON(!mutex_is_locked(&rng_mutex)); | |
113 | if (!current_rng) | |
114 | return; | |
115 | ||
116 | /* decrease last reference for triggering the cleanup */ | |
117 | kref_put(¤t_rng->ref, cleanup_rng); | |
118 | current_rng = NULL; | |
119 | } | |
120 | ||
121 | /* Returns ERR_PTR(), NULL or refcounted hwrng */ | |
122 | static struct hwrng *get_current_rng(void) | |
123 | { | |
124 | struct hwrng *rng; | |
125 | ||
126 | if (mutex_lock_interruptible(&rng_mutex)) | |
127 | return ERR_PTR(-ERESTARTSYS); | |
128 | ||
129 | rng = current_rng; | |
130 | if (rng) | |
131 | kref_get(&rng->ref); | |
132 | ||
133 | mutex_unlock(&rng_mutex); | |
134 | return rng; | |
135 | } | |
136 | ||
137 | static void put_rng(struct hwrng *rng) | |
138 | { | |
139 | /* | |
140 | * Hold rng_mutex here so we serialize in case they set_current_rng | |
141 | * on rng again immediately. | |
142 | */ | |
143 | mutex_lock(&rng_mutex); | |
144 | if (rng) | |
145 | kref_put(&rng->ref, cleanup_rng); | |
146 | mutex_unlock(&rng_mutex); | |
147 | } | |
148 | ||
844dd05f MB |
149 | static inline int hwrng_init(struct hwrng *rng) |
150 | { | |
d3cc7996 AS |
151 | if (rng->init) { |
152 | int ret; | |
153 | ||
154 | ret = rng->init(rng); | |
155 | if (ret) | |
156 | return ret; | |
157 | } | |
158 | add_early_randomness(rng); | |
be4000bc | 159 | |
0f734e6e TD |
160 | current_quality = rng->quality ? : default_quality; |
161 | current_quality &= 1023; | |
162 | ||
163 | if (current_quality == 0 && hwrng_fill) | |
164 | kthread_stop(hwrng_fill); | |
be4000bc TD |
165 | if (current_quality > 0 && !hwrng_fill) |
166 | start_khwrngd(); | |
167 | ||
d3cc7996 | 168 | return 0; |
844dd05f MB |
169 | } |
170 | ||
844dd05f MB |
171 | static int rng_dev_open(struct inode *inode, struct file *filp) |
172 | { | |
173 | /* enforce read-only access to this chrdev */ | |
174 | if ((filp->f_mode & FMODE_READ) == 0) | |
175 | return -EINVAL; | |
176 | if (filp->f_mode & FMODE_WRITE) | |
177 | return -EINVAL; | |
178 | return 0; | |
179 | } | |
180 | ||
9996508b IM |
181 | static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size, |
182 | int wait) { | |
183 | int present; | |
184 | ||
9372b35e | 185 | BUG_ON(!mutex_is_locked(&reading_mutex)); |
9996508b IM |
186 | if (rng->read) |
187 | return rng->read(rng, (void *)buffer, size, wait); | |
188 | ||
189 | if (rng->data_present) | |
190 | present = rng->data_present(rng, wait); | |
191 | else | |
192 | present = 1; | |
193 | ||
194 | if (present) | |
195 | return rng->data_read(rng, (u32 *)buffer); | |
196 | ||
197 | return 0; | |
198 | } | |
199 | ||
844dd05f MB |
200 | static ssize_t rng_dev_read(struct file *filp, char __user *buf, |
201 | size_t size, loff_t *offp) | |
202 | { | |
844dd05f | 203 | ssize_t ret = 0; |
984e976f | 204 | int err = 0; |
9996508b | 205 | int bytes_read, len; |
3a2c0ba5 | 206 | struct hwrng *rng; |
844dd05f MB |
207 | |
208 | while (size) { | |
3a2c0ba5 RR |
209 | rng = get_current_rng(); |
210 | if (IS_ERR(rng)) { | |
211 | err = PTR_ERR(rng); | |
844dd05f | 212 | goto out; |
9996508b | 213 | } |
3a2c0ba5 | 214 | if (!rng) { |
844dd05f | 215 | err = -ENODEV; |
3a2c0ba5 | 216 | goto out; |
844dd05f | 217 | } |
984e976f | 218 | |
9372b35e | 219 | mutex_lock(&reading_mutex); |
9996508b | 220 | if (!data_avail) { |
3a2c0ba5 | 221 | bytes_read = rng_get_data(rng, rng_buffer, |
f7f154f1 | 222 | rng_buffer_size(), |
9996508b IM |
223 | !(filp->f_flags & O_NONBLOCK)); |
224 | if (bytes_read < 0) { | |
225 | err = bytes_read; | |
9372b35e | 226 | goto out_unlock_reading; |
9996508b IM |
227 | } |
228 | data_avail = bytes_read; | |
893f1128 | 229 | } |
844dd05f | 230 | |
9996508b IM |
231 | if (!data_avail) { |
232 | if (filp->f_flags & O_NONBLOCK) { | |
233 | err = -EAGAIN; | |
9372b35e | 234 | goto out_unlock_reading; |
9996508b IM |
235 | } |
236 | } else { | |
237 | len = data_avail; | |
238 | if (len > size) | |
239 | len = size; | |
240 | ||
241 | data_avail -= len; | |
242 | ||
243 | if (copy_to_user(buf + ret, rng_buffer + data_avail, | |
244 | len)) { | |
245 | err = -EFAULT; | |
9372b35e | 246 | goto out_unlock_reading; |
9996508b IM |
247 | } |
248 | ||
249 | size -= len; | |
250 | ret += len; | |
844dd05f MB |
251 | } |
252 | ||
9372b35e | 253 | mutex_unlock(&reading_mutex); |
3a2c0ba5 | 254 | put_rng(rng); |
9996508b | 255 | |
844dd05f MB |
256 | if (need_resched()) |
257 | schedule_timeout_interruptible(1); | |
9996508b IM |
258 | |
259 | if (signal_pending(current)) { | |
260 | err = -ERESTARTSYS; | |
844dd05f | 261 | goto out; |
9996508b | 262 | } |
844dd05f MB |
263 | } |
264 | out: | |
265 | return ret ? : err; | |
3a2c0ba5 | 266 | |
9372b35e RR |
267 | out_unlock_reading: |
268 | mutex_unlock(&reading_mutex); | |
3a2c0ba5 RR |
269 | put_rng(rng); |
270 | goto out; | |
844dd05f MB |
271 | } |
272 | ||
273 | ||
62322d25 | 274 | static const struct file_operations rng_chrdev_ops = { |
844dd05f MB |
275 | .owner = THIS_MODULE, |
276 | .open = rng_dev_open, | |
277 | .read = rng_dev_read, | |
6038f373 | 278 | .llseek = noop_llseek, |
844dd05f MB |
279 | }; |
280 | ||
281 | static struct miscdevice rng_miscdev = { | |
282 | .minor = RNG_MISCDEV_MINOR, | |
283 | .name = RNG_MODULE_NAME, | |
e454cea2 | 284 | .nodename = "hwrng", |
844dd05f MB |
285 | .fops = &rng_chrdev_ops, |
286 | }; | |
287 | ||
288 | ||
94fbcded GKH |
289 | static ssize_t hwrng_attr_current_store(struct device *dev, |
290 | struct device_attribute *attr, | |
844dd05f MB |
291 | const char *buf, size_t len) |
292 | { | |
293 | int err; | |
294 | struct hwrng *rng; | |
295 | ||
296 | err = mutex_lock_interruptible(&rng_mutex); | |
297 | if (err) | |
298 | return -ERESTARTSYS; | |
299 | err = -ENODEV; | |
300 | list_for_each_entry(rng, &rng_list, list) { | |
301 | if (strcmp(rng->name, buf) == 0) { | |
302 | if (rng == current_rng) { | |
303 | err = 0; | |
304 | break; | |
305 | } | |
306 | err = hwrng_init(rng); | |
307 | if (err) | |
308 | break; | |
3a2c0ba5 RR |
309 | drop_current_rng(); |
310 | set_current_rng(rng); | |
844dd05f MB |
311 | err = 0; |
312 | break; | |
313 | } | |
314 | } | |
315 | mutex_unlock(&rng_mutex); | |
316 | ||
317 | return err ? : len; | |
318 | } | |
319 | ||
94fbcded GKH |
320 | static ssize_t hwrng_attr_current_show(struct device *dev, |
321 | struct device_attribute *attr, | |
844dd05f MB |
322 | char *buf) |
323 | { | |
844dd05f | 324 | ssize_t ret; |
3a2c0ba5 | 325 | struct hwrng *rng; |
844dd05f | 326 | |
3a2c0ba5 RR |
327 | rng = get_current_rng(); |
328 | if (IS_ERR(rng)) | |
329 | return PTR_ERR(rng); | |
330 | ||
331 | ret = snprintf(buf, PAGE_SIZE, "%s\n", rng ? rng->name : "none"); | |
332 | put_rng(rng); | |
844dd05f MB |
333 | |
334 | return ret; | |
335 | } | |
336 | ||
94fbcded GKH |
337 | static ssize_t hwrng_attr_available_show(struct device *dev, |
338 | struct device_attribute *attr, | |
844dd05f MB |
339 | char *buf) |
340 | { | |
341 | int err; | |
844dd05f MB |
342 | struct hwrng *rng; |
343 | ||
344 | err = mutex_lock_interruptible(&rng_mutex); | |
345 | if (err) | |
346 | return -ERESTARTSYS; | |
347 | buf[0] = '\0'; | |
348 | list_for_each_entry(rng, &rng_list, list) { | |
61daf055 RS |
349 | strlcat(buf, rng->name, PAGE_SIZE); |
350 | strlcat(buf, " ", PAGE_SIZE); | |
844dd05f | 351 | } |
61daf055 | 352 | strlcat(buf, "\n", PAGE_SIZE); |
844dd05f MB |
353 | mutex_unlock(&rng_mutex); |
354 | ||
61daf055 | 355 | return strlen(buf); |
844dd05f MB |
356 | } |
357 | ||
94fbcded GKH |
358 | static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR, |
359 | hwrng_attr_current_show, | |
360 | hwrng_attr_current_store); | |
361 | static DEVICE_ATTR(rng_available, S_IRUGO, | |
362 | hwrng_attr_available_show, | |
363 | NULL); | |
844dd05f MB |
364 | |
365 | ||
b844eba2 | 366 | static void unregister_miscdev(void) |
844dd05f | 367 | { |
94fbcded GKH |
368 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available); |
369 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); | |
b844eba2 | 370 | misc_deregister(&rng_miscdev); |
844dd05f MB |
371 | } |
372 | ||
373 | static int register_miscdev(void) | |
374 | { | |
375 | int err; | |
376 | ||
377 | err = misc_register(&rng_miscdev); | |
378 | if (err) | |
379 | goto out; | |
94fbcded GKH |
380 | err = device_create_file(rng_miscdev.this_device, |
381 | &dev_attr_rng_current); | |
844dd05f MB |
382 | if (err) |
383 | goto err_misc_dereg; | |
94fbcded GKH |
384 | err = device_create_file(rng_miscdev.this_device, |
385 | &dev_attr_rng_available); | |
844dd05f MB |
386 | if (err) |
387 | goto err_remove_current; | |
388 | out: | |
389 | return err; | |
390 | ||
391 | err_remove_current: | |
94fbcded | 392 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); |
844dd05f MB |
393 | err_misc_dereg: |
394 | misc_deregister(&rng_miscdev); | |
395 | goto out; | |
396 | } | |
397 | ||
be4000bc TD |
398 | static int hwrng_fillfn(void *unused) |
399 | { | |
400 | long rc; | |
401 | ||
402 | while (!kthread_should_stop()) { | |
3a2c0ba5 RR |
403 | struct hwrng *rng; |
404 | ||
405 | rng = get_current_rng(); | |
406 | if (IS_ERR(rng) || !rng) | |
be4000bc | 407 | break; |
9372b35e | 408 | mutex_lock(&reading_mutex); |
3a2c0ba5 | 409 | rc = rng_get_data(rng, rng_fillbuf, |
be4000bc | 410 | rng_buffer_size(), 1); |
9372b35e | 411 | mutex_unlock(&reading_mutex); |
3a2c0ba5 | 412 | put_rng(rng); |
be4000bc TD |
413 | if (rc <= 0) { |
414 | pr_warn("hwrng: no data available\n"); | |
415 | msleep_interruptible(10000); | |
416 | continue; | |
417 | } | |
9372b35e | 418 | /* Outside lock, sure, but y'know: randomness. */ |
be4000bc | 419 | add_hwgenerator_randomness((void *)rng_fillbuf, rc, |
e02b8765 | 420 | rc * current_quality * 8 >> 10); |
be4000bc | 421 | } |
9dda727d | 422 | hwrng_fill = NULL; |
be4000bc TD |
423 | return 0; |
424 | } | |
425 | ||
426 | static void start_khwrngd(void) | |
427 | { | |
428 | hwrng_fill = kthread_run(hwrng_fillfn, NULL, "hwrng"); | |
429 | if (hwrng_fill == ERR_PTR(-ENOMEM)) { | |
430 | pr_err("hwrng_fill thread creation failed"); | |
431 | hwrng_fill = NULL; | |
432 | } | |
433 | } | |
434 | ||
844dd05f MB |
435 | int hwrng_register(struct hwrng *rng) |
436 | { | |
844dd05f MB |
437 | int err = -EINVAL; |
438 | struct hwrng *old_rng, *tmp; | |
439 | ||
440 | if (rng->name == NULL || | |
9996508b | 441 | (rng->data_read == NULL && rng->read == NULL)) |
844dd05f MB |
442 | goto out; |
443 | ||
444 | mutex_lock(&rng_mutex); | |
445 | ||
f7f154f1 RR |
446 | /* kmalloc makes this safe for virt_to_page() in virtio_rng.c */ |
447 | err = -ENOMEM; | |
448 | if (!rng_buffer) { | |
449 | rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL); | |
450 | if (!rng_buffer) | |
451 | goto out_unlock; | |
452 | } | |
be4000bc TD |
453 | if (!rng_fillbuf) { |
454 | rng_fillbuf = kmalloc(rng_buffer_size(), GFP_KERNEL); | |
455 | if (!rng_fillbuf) { | |
456 | kfree(rng_buffer); | |
457 | goto out_unlock; | |
458 | } | |
459 | } | |
f7f154f1 | 460 | |
844dd05f MB |
461 | /* Must not register two RNGs with the same name. */ |
462 | err = -EEXIST; | |
463 | list_for_each_entry(tmp, &rng_list, list) { | |
464 | if (strcmp(tmp->name, rng->name) == 0) | |
465 | goto out_unlock; | |
466 | } | |
467 | ||
844dd05f MB |
468 | old_rng = current_rng; |
469 | if (!old_rng) { | |
470 | err = hwrng_init(rng); | |
471 | if (err) | |
472 | goto out_unlock; | |
3a2c0ba5 | 473 | set_current_rng(rng); |
844dd05f MB |
474 | } |
475 | err = 0; | |
d167b6e1 | 476 | if (!old_rng) { |
844dd05f MB |
477 | err = register_miscdev(); |
478 | if (err) { | |
3a2c0ba5 | 479 | drop_current_rng(); |
844dd05f MB |
480 | goto out_unlock; |
481 | } | |
482 | } | |
483 | INIT_LIST_HEAD(&rng->list); | |
484 | list_add_tail(&rng->list, &rng_list); | |
d9e79726 | 485 | |
d3cc7996 AS |
486 | if (old_rng && !rng->init) { |
487 | /* | |
488 | * Use a new device's input to add some randomness to | |
489 | * the system. If this rng device isn't going to be | |
490 | * used right away, its init function hasn't been | |
491 | * called yet; so only use the randomness from devices | |
492 | * that don't need an init callback. | |
493 | */ | |
494 | add_early_randomness(rng); | |
495 | } | |
496 | ||
844dd05f MB |
497 | out_unlock: |
498 | mutex_unlock(&rng_mutex); | |
499 | out: | |
500 | return err; | |
501 | } | |
502 | EXPORT_SYMBOL_GPL(hwrng_register); | |
503 | ||
b844eba2 | 504 | void hwrng_unregister(struct hwrng *rng) |
844dd05f | 505 | { |
844dd05f MB |
506 | mutex_lock(&rng_mutex); |
507 | ||
508 | list_del(&rng->list); | |
509 | if (current_rng == rng) { | |
3a2c0ba5 RR |
510 | drop_current_rng(); |
511 | if (!list_empty(&rng_list)) { | |
512 | struct hwrng *tail; | |
513 | ||
514 | tail = list_entry(rng_list.prev, struct hwrng, list); | |
515 | ||
516 | if (hwrng_init(tail) == 0) | |
517 | set_current_rng(tail); | |
844dd05f MB |
518 | } |
519 | } | |
3a2c0ba5 | 520 | |
be4000bc | 521 | if (list_empty(&rng_list)) { |
1dacb395 | 522 | mutex_unlock(&rng_mutex); |
b844eba2 | 523 | unregister_miscdev(); |
be4000bc TD |
524 | if (hwrng_fill) |
525 | kthread_stop(hwrng_fill); | |
1dacb395 AK |
526 | } else |
527 | mutex_unlock(&rng_mutex); | |
844dd05f | 528 | } |
b844eba2 | 529 | EXPORT_SYMBOL_GPL(hwrng_unregister); |
844dd05f | 530 | |
b7d44d94 ST |
531 | static void __exit hwrng_exit(void) |
532 | { | |
533 | mutex_lock(&rng_mutex); | |
534 | BUG_ON(current_rng); | |
535 | kfree(rng_buffer); | |
be4000bc | 536 | kfree(rng_fillbuf); |
b7d44d94 ST |
537 | mutex_unlock(&rng_mutex); |
538 | } | |
539 | ||
540 | module_exit(hwrng_exit); | |
844dd05f MB |
541 | |
542 | MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver"); | |
543 | MODULE_LICENSE("GPL"); |