Commit | Line | Data |
---|---|---|
844dd05f | 1 | /* |
dd801483 CL |
2 | * hw_random/core.c: HWRNG core API |
3 | * | |
4 | * Copyright 2006 Michael Buesch <m@bues.ch> | |
5 | * Copyright 2005 (c) MontaVista Software, Inc. | |
6 | * | |
4f4cfa6c | 7 | * Please read Documentation/admin-guide/hw_random.rst for details on use. |
dd801483 CL |
8 | * |
9 | * This software may be used and distributed according to the terms | |
10 | * of the GNU General Public License, incorporated herein by reference. | |
844dd05f MB |
11 | */ |
12 | ||
affdec58 | 13 | #include <linux/delay.h> |
844dd05f | 14 | #include <linux/device.h> |
affdec58 CL |
15 | #include <linux/err.h> |
16 | #include <linux/fs.h> | |
844dd05f | 17 | #include <linux/hw_random.h> |
844dd05f | 18 | #include <linux/kernel.h> |
be4000bc | 19 | #include <linux/kthread.h> |
174cd4b1 | 20 | #include <linux/sched/signal.h> |
affdec58 CL |
21 | #include <linux/miscdevice.h> |
22 | #include <linux/module.h> | |
d9e79726 | 23 | #include <linux/random.h> |
affdec58 CL |
24 | #include <linux/sched.h> |
25 | #include <linux/slab.h> | |
7c0f6ba6 | 26 | #include <linux/uaccess.h> |
844dd05f | 27 | |
844dd05f | 28 | #define RNG_MODULE_NAME "hw_random" |
844dd05f MB |
29 | |
30 | static struct hwrng *current_rng; | |
10a515dd HF |
31 | /* the current rng has been explicitly chosen by user via sysfs */ |
32 | static int cur_rng_set_by_user; | |
be4000bc | 33 | static struct task_struct *hwrng_fill; |
2bbb6983 | 34 | /* list of registered rngs, sorted decending by quality */ |
844dd05f | 35 | static LIST_HEAD(rng_list); |
9372b35e | 36 | /* Protects rng_list and current_rng */ |
844dd05f | 37 | static DEFINE_MUTEX(rng_mutex); |
9372b35e RR |
38 | /* Protects rng read functions, data_avail, rng_buffer and rng_fillbuf */ |
39 | static DEFINE_MUTEX(reading_mutex); | |
9996508b | 40 | static int data_avail; |
be4000bc | 41 | static u8 *rng_buffer, *rng_fillbuf; |
0f734e6e TD |
42 | static unsigned short current_quality; |
43 | static unsigned short default_quality; /* = 0; default to "off" */ | |
be4000bc TD |
44 | |
45 | module_param(current_quality, ushort, 0644); | |
46 | MODULE_PARM_DESC(current_quality, | |
fae29f13 | 47 | "current hwrng entropy estimation per 1024 bits of input"); |
0f734e6e TD |
48 | module_param(default_quality, ushort, 0644); |
49 | MODULE_PARM_DESC(default_quality, | |
fae29f13 | 50 | "default entropy content of hwrng per 1024 bits of input"); |
be4000bc | 51 | |
ff77c150 | 52 | static void drop_current_rng(void); |
90ac41bd | 53 | static int hwrng_init(struct hwrng *rng); |
be4000bc | 54 | static void start_khwrngd(void); |
f7f154f1 | 55 | |
d3cc7996 AS |
56 | static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size, |
57 | int wait); | |
58 | ||
f7f154f1 RR |
59 | static size_t rng_buffer_size(void) |
60 | { | |
61 | return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES; | |
62 | } | |
844dd05f | 63 | |
d3cc7996 AS |
64 | static void add_early_randomness(struct hwrng *rng) |
65 | { | |
d3cc7996 | 66 | int bytes_read; |
6d4952d9 | 67 | size_t size = min_t(size_t, 16, rng_buffer_size()); |
d3cc7996 | 68 | |
9372b35e | 69 | mutex_lock(&reading_mutex); |
78887832 | 70 | bytes_read = rng_get_data(rng, rng_buffer, size, 0); |
9372b35e | 71 | mutex_unlock(&reading_mutex); |
d3cc7996 | 72 | if (bytes_read > 0) |
6d4952d9 | 73 | add_device_randomness(rng_buffer, bytes_read); |
d3cc7996 AS |
74 | } |
75 | ||
3a2c0ba5 RR |
76 | static inline void cleanup_rng(struct kref *kref) |
77 | { | |
78 | struct hwrng *rng = container_of(kref, struct hwrng, ref); | |
79 | ||
80 | if (rng->cleanup) | |
81 | rng->cleanup(rng); | |
a027f30d | 82 | |
77584ee5 | 83 | complete(&rng->cleanup_done); |
3a2c0ba5 RR |
84 | } |
85 | ||
90ac41bd | 86 | static int set_current_rng(struct hwrng *rng) |
3a2c0ba5 | 87 | { |
90ac41bd HX |
88 | int err; |
89 | ||
3a2c0ba5 | 90 | BUG_ON(!mutex_is_locked(&rng_mutex)); |
90ac41bd HX |
91 | |
92 | err = hwrng_init(rng); | |
93 | if (err) | |
94 | return err; | |
95 | ||
ff77c150 | 96 | drop_current_rng(); |
3a2c0ba5 | 97 | current_rng = rng; |
90ac41bd HX |
98 | |
99 | return 0; | |
3a2c0ba5 RR |
100 | } |
101 | ||
102 | static void drop_current_rng(void) | |
103 | { | |
104 | BUG_ON(!mutex_is_locked(&rng_mutex)); | |
105 | if (!current_rng) | |
106 | return; | |
107 | ||
108 | /* decrease last reference for triggering the cleanup */ | |
109 | kref_put(¤t_rng->ref, cleanup_rng); | |
110 | current_rng = NULL; | |
111 | } | |
112 | ||
113 | /* Returns ERR_PTR(), NULL or refcounted hwrng */ | |
daae28de LV |
114 | static struct hwrng *get_current_rng_nolock(void) |
115 | { | |
116 | if (current_rng) | |
117 | kref_get(¤t_rng->ref); | |
118 | ||
119 | return current_rng; | |
120 | } | |
121 | ||
3a2c0ba5 RR |
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 | ||
daae28de | 129 | rng = get_current_rng_nolock(); |
3a2c0ba5 RR |
130 | |
131 | mutex_unlock(&rng_mutex); | |
132 | return rng; | |
133 | } | |
134 | ||
135 | static void put_rng(struct hwrng *rng) | |
136 | { | |
137 | /* | |
138 | * Hold rng_mutex here so we serialize in case they set_current_rng | |
139 | * on rng again immediately. | |
140 | */ | |
141 | mutex_lock(&rng_mutex); | |
142 | if (rng) | |
143 | kref_put(&rng->ref, cleanup_rng); | |
144 | mutex_unlock(&rng_mutex); | |
145 | } | |
146 | ||
90ac41bd | 147 | static int hwrng_init(struct hwrng *rng) |
844dd05f | 148 | { |
15b66cd5 HX |
149 | if (kref_get_unless_zero(&rng->ref)) |
150 | goto skip_init; | |
151 | ||
d3cc7996 AS |
152 | if (rng->init) { |
153 | int ret; | |
154 | ||
155 | ret = rng->init(rng); | |
156 | if (ret) | |
157 | return ret; | |
158 | } | |
15b66cd5 HX |
159 | |
160 | kref_init(&rng->ref); | |
161 | reinit_completion(&rng->cleanup_done); | |
162 | ||
163 | skip_init: | |
0f734e6e | 164 | current_quality = rng->quality ? : default_quality; |
506bf0c0 KP |
165 | if (current_quality > 1024) |
166 | current_quality = 1024; | |
0f734e6e TD |
167 | |
168 | if (current_quality == 0 && hwrng_fill) | |
169 | kthread_stop(hwrng_fill); | |
be4000bc TD |
170 | if (current_quality > 0 && !hwrng_fill) |
171 | start_khwrngd(); | |
172 | ||
d3cc7996 | 173 | return 0; |
844dd05f MB |
174 | } |
175 | ||
844dd05f MB |
176 | static int rng_dev_open(struct inode *inode, struct file *filp) |
177 | { | |
178 | /* enforce read-only access to this chrdev */ | |
179 | if ((filp->f_mode & FMODE_READ) == 0) | |
180 | return -EINVAL; | |
181 | if (filp->f_mode & FMODE_WRITE) | |
182 | return -EINVAL; | |
183 | return 0; | |
184 | } | |
185 | ||
9996508b IM |
186 | static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size, |
187 | int wait) { | |
188 | int present; | |
189 | ||
9372b35e | 190 | BUG_ON(!mutex_is_locked(&reading_mutex)); |
9996508b IM |
191 | if (rng->read) |
192 | return rng->read(rng, (void *)buffer, size, wait); | |
193 | ||
194 | if (rng->data_present) | |
195 | present = rng->data_present(rng, wait); | |
196 | else | |
197 | present = 1; | |
198 | ||
199 | if (present) | |
200 | return rng->data_read(rng, (u32 *)buffer); | |
201 | ||
202 | return 0; | |
203 | } | |
204 | ||
844dd05f MB |
205 | static ssize_t rng_dev_read(struct file *filp, char __user *buf, |
206 | size_t size, loff_t *offp) | |
207 | { | |
844dd05f | 208 | ssize_t ret = 0; |
984e976f | 209 | int err = 0; |
9996508b | 210 | int bytes_read, len; |
3a2c0ba5 | 211 | struct hwrng *rng; |
844dd05f MB |
212 | |
213 | while (size) { | |
3a2c0ba5 RR |
214 | rng = get_current_rng(); |
215 | if (IS_ERR(rng)) { | |
216 | err = PTR_ERR(rng); | |
844dd05f | 217 | goto out; |
9996508b | 218 | } |
3a2c0ba5 | 219 | if (!rng) { |
844dd05f | 220 | err = -ENODEV; |
3a2c0ba5 | 221 | goto out; |
844dd05f | 222 | } |
984e976f | 223 | |
1ab87298 JS |
224 | if (mutex_lock_interruptible(&reading_mutex)) { |
225 | err = -ERESTARTSYS; | |
226 | goto out_put; | |
227 | } | |
9996508b | 228 | if (!data_avail) { |
3a2c0ba5 | 229 | bytes_read = rng_get_data(rng, rng_buffer, |
f7f154f1 | 230 | rng_buffer_size(), |
9996508b IM |
231 | !(filp->f_flags & O_NONBLOCK)); |
232 | if (bytes_read < 0) { | |
233 | err = bytes_read; | |
9372b35e | 234 | goto out_unlock_reading; |
9996508b IM |
235 | } |
236 | data_avail = bytes_read; | |
893f1128 | 237 | } |
844dd05f | 238 | |
9996508b IM |
239 | if (!data_avail) { |
240 | if (filp->f_flags & O_NONBLOCK) { | |
241 | err = -EAGAIN; | |
9372b35e | 242 | goto out_unlock_reading; |
9996508b IM |
243 | } |
244 | } else { | |
245 | len = data_avail; | |
246 | if (len > size) | |
247 | len = size; | |
248 | ||
249 | data_avail -= len; | |
250 | ||
251 | if (copy_to_user(buf + ret, rng_buffer + data_avail, | |
252 | len)) { | |
253 | err = -EFAULT; | |
9372b35e | 254 | goto out_unlock_reading; |
9996508b IM |
255 | } |
256 | ||
257 | size -= len; | |
258 | ret += len; | |
844dd05f MB |
259 | } |
260 | ||
9372b35e | 261 | mutex_unlock(&reading_mutex); |
3a2c0ba5 | 262 | put_rng(rng); |
9996508b | 263 | |
844dd05f MB |
264 | if (need_resched()) |
265 | schedule_timeout_interruptible(1); | |
9996508b IM |
266 | |
267 | if (signal_pending(current)) { | |
268 | err = -ERESTARTSYS; | |
844dd05f | 269 | goto out; |
9996508b | 270 | } |
844dd05f MB |
271 | } |
272 | out: | |
273 | return ret ? : err; | |
3a2c0ba5 | 274 | |
9372b35e RR |
275 | out_unlock_reading: |
276 | mutex_unlock(&reading_mutex); | |
1ab87298 | 277 | out_put: |
3a2c0ba5 RR |
278 | put_rng(rng); |
279 | goto out; | |
844dd05f MB |
280 | } |
281 | ||
62322d25 | 282 | static const struct file_operations rng_chrdev_ops = { |
844dd05f MB |
283 | .owner = THIS_MODULE, |
284 | .open = rng_dev_open, | |
285 | .read = rng_dev_read, | |
6038f373 | 286 | .llseek = noop_llseek, |
844dd05f MB |
287 | }; |
288 | ||
0daa7a0a TI |
289 | static const struct attribute_group *rng_dev_groups[]; |
290 | ||
844dd05f | 291 | static struct miscdevice rng_miscdev = { |
fd50d71f | 292 | .minor = HWRNG_MINOR, |
844dd05f | 293 | .name = RNG_MODULE_NAME, |
e454cea2 | 294 | .nodename = "hwrng", |
844dd05f | 295 | .fops = &rng_chrdev_ops, |
0daa7a0a | 296 | .groups = rng_dev_groups, |
844dd05f MB |
297 | }; |
298 | ||
142a27f0 PM |
299 | static int enable_best_rng(void) |
300 | { | |
301 | int ret = -ENODEV; | |
302 | ||
303 | BUG_ON(!mutex_is_locked(&rng_mutex)); | |
304 | ||
305 | /* rng_list is sorted by quality, use the best (=first) one */ | |
306 | if (!list_empty(&rng_list)) { | |
307 | struct hwrng *new_rng; | |
308 | ||
309 | new_rng = list_entry(rng_list.next, struct hwrng, list); | |
310 | ret = ((new_rng == current_rng) ? 0 : set_current_rng(new_rng)); | |
311 | if (!ret) | |
312 | cur_rng_set_by_user = 0; | |
0e4b5294 GH |
313 | } else { |
314 | drop_current_rng(); | |
315 | cur_rng_set_by_user = 0; | |
316 | ret = 0; | |
142a27f0 PM |
317 | } |
318 | ||
319 | return ret; | |
320 | } | |
321 | ||
94fbcded GKH |
322 | static ssize_t hwrng_attr_current_store(struct device *dev, |
323 | struct device_attribute *attr, | |
844dd05f MB |
324 | const char *buf, size_t len) |
325 | { | |
142a27f0 | 326 | int err = -ENODEV; |
daae28de | 327 | struct hwrng *rng, *old_rng, *new_rng; |
844dd05f MB |
328 | |
329 | err = mutex_lock_interruptible(&rng_mutex); | |
330 | if (err) | |
331 | return -ERESTARTSYS; | |
142a27f0 | 332 | |
daae28de | 333 | old_rng = current_rng; |
142a27f0 PM |
334 | if (sysfs_streq(buf, "")) { |
335 | err = enable_best_rng(); | |
336 | } else { | |
337 | list_for_each_entry(rng, &rng_list, list) { | |
338 | if (sysfs_streq(rng->name, buf)) { | |
339 | cur_rng_set_by_user = 1; | |
90ac41bd | 340 | err = set_current_rng(rng); |
142a27f0 PM |
341 | break; |
342 | } | |
844dd05f MB |
343 | } |
344 | } | |
daae28de | 345 | new_rng = get_current_rng_nolock(); |
844dd05f MB |
346 | mutex_unlock(&rng_mutex); |
347 | ||
daae28de LV |
348 | if (new_rng) { |
349 | if (new_rng != old_rng) | |
350 | add_early_randomness(new_rng); | |
351 | put_rng(new_rng); | |
352 | } | |
353 | ||
844dd05f MB |
354 | return err ? : len; |
355 | } | |
356 | ||
94fbcded GKH |
357 | static ssize_t hwrng_attr_current_show(struct device *dev, |
358 | struct device_attribute *attr, | |
844dd05f MB |
359 | char *buf) |
360 | { | |
844dd05f | 361 | ssize_t ret; |
3a2c0ba5 | 362 | struct hwrng *rng; |
844dd05f | 363 | |
3a2c0ba5 RR |
364 | rng = get_current_rng(); |
365 | if (IS_ERR(rng)) | |
366 | return PTR_ERR(rng); | |
367 | ||
368 | ret = snprintf(buf, PAGE_SIZE, "%s\n", rng ? rng->name : "none"); | |
369 | put_rng(rng); | |
844dd05f MB |
370 | |
371 | return ret; | |
372 | } | |
373 | ||
94fbcded GKH |
374 | static ssize_t hwrng_attr_available_show(struct device *dev, |
375 | struct device_attribute *attr, | |
844dd05f MB |
376 | char *buf) |
377 | { | |
378 | int err; | |
844dd05f MB |
379 | struct hwrng *rng; |
380 | ||
381 | err = mutex_lock_interruptible(&rng_mutex); | |
382 | if (err) | |
383 | return -ERESTARTSYS; | |
384 | buf[0] = '\0'; | |
385 | list_for_each_entry(rng, &rng_list, list) { | |
61daf055 RS |
386 | strlcat(buf, rng->name, PAGE_SIZE); |
387 | strlcat(buf, " ", PAGE_SIZE); | |
844dd05f | 388 | } |
61daf055 | 389 | strlcat(buf, "\n", PAGE_SIZE); |
844dd05f MB |
390 | mutex_unlock(&rng_mutex); |
391 | ||
61daf055 | 392 | return strlen(buf); |
844dd05f MB |
393 | } |
394 | ||
10a515dd HF |
395 | static ssize_t hwrng_attr_selected_show(struct device *dev, |
396 | struct device_attribute *attr, | |
397 | char *buf) | |
398 | { | |
399 | return snprintf(buf, PAGE_SIZE, "%d\n", cur_rng_set_by_user); | |
400 | } | |
401 | ||
94fbcded GKH |
402 | static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR, |
403 | hwrng_attr_current_show, | |
404 | hwrng_attr_current_store); | |
405 | static DEVICE_ATTR(rng_available, S_IRUGO, | |
406 | hwrng_attr_available_show, | |
407 | NULL); | |
10a515dd HF |
408 | static DEVICE_ATTR(rng_selected, S_IRUGO, |
409 | hwrng_attr_selected_show, | |
410 | NULL); | |
844dd05f | 411 | |
0daa7a0a TI |
412 | static struct attribute *rng_dev_attrs[] = { |
413 | &dev_attr_rng_current.attr, | |
414 | &dev_attr_rng_available.attr, | |
10a515dd | 415 | &dev_attr_rng_selected.attr, |
0daa7a0a TI |
416 | NULL |
417 | }; | |
418 | ||
419 | ATTRIBUTE_GROUPS(rng_dev); | |
844dd05f | 420 | |
ac3a497f | 421 | static void __exit unregister_miscdev(void) |
844dd05f | 422 | { |
b844eba2 | 423 | misc_deregister(&rng_miscdev); |
844dd05f MB |
424 | } |
425 | ||
ac3a497f | 426 | static int __init register_miscdev(void) |
844dd05f | 427 | { |
0daa7a0a | 428 | return misc_register(&rng_miscdev); |
844dd05f MB |
429 | } |
430 | ||
be4000bc TD |
431 | static int hwrng_fillfn(void *unused) |
432 | { | |
433 | long rc; | |
434 | ||
08e97aec | 435 | while (!kthread_should_stop()) { |
3a2c0ba5 RR |
436 | struct hwrng *rng; |
437 | ||
438 | rng = get_current_rng(); | |
439 | if (IS_ERR(rng) || !rng) | |
be4000bc | 440 | break; |
9372b35e | 441 | mutex_lock(&reading_mutex); |
3a2c0ba5 | 442 | rc = rng_get_data(rng, rng_fillbuf, |
be4000bc | 443 | rng_buffer_size(), 1); |
9372b35e | 444 | mutex_unlock(&reading_mutex); |
3a2c0ba5 | 445 | put_rng(rng); |
be4000bc TD |
446 | if (rc <= 0) { |
447 | pr_warn("hwrng: no data available\n"); | |
448 | msleep_interruptible(10000); | |
449 | continue; | |
450 | } | |
9372b35e | 451 | /* Outside lock, sure, but y'know: randomness. */ |
be4000bc | 452 | add_hwgenerator_randomness((void *)rng_fillbuf, rc, |
e02b8765 | 453 | rc * current_quality * 8 >> 10); |
be4000bc | 454 | } |
9dda727d | 455 | hwrng_fill = NULL; |
be4000bc TD |
456 | return 0; |
457 | } | |
458 | ||
459 | static void start_khwrngd(void) | |
460 | { | |
461 | hwrng_fill = kthread_run(hwrng_fillfn, NULL, "hwrng"); | |
17fb874d | 462 | if (IS_ERR(hwrng_fill)) { |
4d0ec229 | 463 | pr_err("hwrng_fill thread creation failed\n"); |
be4000bc TD |
464 | hwrng_fill = NULL; |
465 | } | |
466 | } | |
467 | ||
844dd05f MB |
468 | int hwrng_register(struct hwrng *rng) |
469 | { | |
844dd05f | 470 | int err = -EINVAL; |
28443671 | 471 | struct hwrng *tmp; |
2bbb6983 | 472 | struct list_head *rng_list_ptr; |
28443671 | 473 | bool is_new_current = false; |
844dd05f | 474 | |
2a971e3b | 475 | if (!rng->name || (!rng->data_read && !rng->read)) |
844dd05f MB |
476 | goto out; |
477 | ||
478 | mutex_lock(&rng_mutex); | |
daae28de | 479 | |
844dd05f MB |
480 | /* Must not register two RNGs with the same name. */ |
481 | err = -EEXIST; | |
482 | list_for_each_entry(tmp, &rng_list, list) { | |
483 | if (strcmp(tmp->name, rng->name) == 0) | |
484 | goto out_unlock; | |
485 | } | |
486 | ||
15b66cd5 HX |
487 | init_completion(&rng->cleanup_done); |
488 | complete(&rng->cleanup_done); | |
489 | ||
2bbb6983 HF |
490 | /* rng_list is sorted by decreasing quality */ |
491 | list_for_each(rng_list_ptr, &rng_list) { | |
492 | tmp = list_entry(rng_list_ptr, struct hwrng, list); | |
493 | if (tmp->quality < rng->quality) | |
494 | break; | |
495 | } | |
496 | list_add_tail(&rng->list, rng_list_ptr); | |
497 | ||
28443671 LV |
498 | if (!current_rng || |
499 | (!cur_rng_set_by_user && rng->quality > current_rng->quality)) { | |
2bbb6983 HF |
500 | /* |
501 | * Set new rng as current as the new rng source | |
10a515dd HF |
502 | * provides better entropy quality and was not |
503 | * chosen by userspace. | |
2bbb6983 | 504 | */ |
90ac41bd | 505 | err = set_current_rng(rng); |
844dd05f MB |
506 | if (err) |
507 | goto out_unlock; | |
28443671 LV |
508 | /* to use current_rng in add_early_randomness() we need |
509 | * to take a ref | |
510 | */ | |
511 | is_new_current = true; | |
512 | kref_get(&rng->ref); | |
844dd05f | 513 | } |
daae28de | 514 | mutex_unlock(&rng_mutex); |
28443671 | 515 | if (is_new_current || !rng->init) { |
d3cc7996 AS |
516 | /* |
517 | * Use a new device's input to add some randomness to | |
518 | * the system. If this rng device isn't going to be | |
519 | * used right away, its init function hasn't been | |
daae28de LV |
520 | * called yet by set_current_rng(); so only use the |
521 | * randomness from devices that don't need an init callback | |
d3cc7996 AS |
522 | */ |
523 | add_early_randomness(rng); | |
524 | } | |
28443671 LV |
525 | if (is_new_current) |
526 | put_rng(rng); | |
527 | return 0; | |
844dd05f MB |
528 | out_unlock: |
529 | mutex_unlock(&rng_mutex); | |
530 | out: | |
531 | return err; | |
532 | } | |
533 | EXPORT_SYMBOL_GPL(hwrng_register); | |
534 | ||
b844eba2 | 535 | void hwrng_unregister(struct hwrng *rng) |
844dd05f | 536 | { |
daae28de | 537 | struct hwrng *old_rng, *new_rng; |
837bf7cc MB |
538 | int err; |
539 | ||
844dd05f MB |
540 | mutex_lock(&rng_mutex); |
541 | ||
daae28de | 542 | old_rng = current_rng; |
844dd05f | 543 | list_del(&rng->list); |
837bf7cc MB |
544 | if (current_rng == rng) { |
545 | err = enable_best_rng(); | |
546 | if (err) { | |
547 | drop_current_rng(); | |
548 | cur_rng_set_by_user = 0; | |
549 | } | |
550 | } | |
3a2c0ba5 | 551 | |
daae28de | 552 | new_rng = get_current_rng_nolock(); |
be4000bc | 553 | if (list_empty(&rng_list)) { |
1dacb395 | 554 | mutex_unlock(&rng_mutex); |
be4000bc TD |
555 | if (hwrng_fill) |
556 | kthread_stop(hwrng_fill); | |
1dacb395 AK |
557 | } else |
558 | mutex_unlock(&rng_mutex); | |
a027f30d | 559 | |
daae28de LV |
560 | if (new_rng) { |
561 | if (old_rng != new_rng) | |
562 | add_early_randomness(new_rng); | |
563 | put_rng(new_rng); | |
564 | } | |
565 | ||
77584ee5 | 566 | wait_for_completion(&rng->cleanup_done); |
844dd05f | 567 | } |
b844eba2 | 568 | EXPORT_SYMBOL_GPL(hwrng_unregister); |
844dd05f | 569 | |
4d9b519c DT |
570 | static void devm_hwrng_release(struct device *dev, void *res) |
571 | { | |
572 | hwrng_unregister(*(struct hwrng **)res); | |
573 | } | |
574 | ||
575 | static int devm_hwrng_match(struct device *dev, void *res, void *data) | |
576 | { | |
577 | struct hwrng **r = res; | |
578 | ||
579 | if (WARN_ON(!r || !*r)) | |
580 | return 0; | |
581 | ||
582 | return *r == data; | |
583 | } | |
584 | ||
585 | int devm_hwrng_register(struct device *dev, struct hwrng *rng) | |
586 | { | |
587 | struct hwrng **ptr; | |
588 | int error; | |
589 | ||
590 | ptr = devres_alloc(devm_hwrng_release, sizeof(*ptr), GFP_KERNEL); | |
591 | if (!ptr) | |
592 | return -ENOMEM; | |
593 | ||
594 | error = hwrng_register(rng); | |
595 | if (error) { | |
596 | devres_free(ptr); | |
597 | return error; | |
598 | } | |
599 | ||
600 | *ptr = rng; | |
601 | devres_add(dev, ptr); | |
602 | return 0; | |
603 | } | |
604 | EXPORT_SYMBOL_GPL(devm_hwrng_register); | |
605 | ||
606 | void devm_hwrng_unregister(struct device *dev, struct hwrng *rng) | |
607 | { | |
608 | devres_release(dev, devm_hwrng_release, devm_hwrng_match, rng); | |
609 | } | |
610 | EXPORT_SYMBOL_GPL(devm_hwrng_unregister); | |
611 | ||
ac3a497f HX |
612 | static int __init hwrng_modinit(void) |
613 | { | |
45645709 | 614 | int ret; |
58b022ac PM |
615 | |
616 | /* kmalloc makes this safe for virt_to_page() in virtio_rng.c */ | |
617 | rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL); | |
618 | if (!rng_buffer) | |
619 | return -ENOMEM; | |
620 | ||
621 | rng_fillbuf = kmalloc(rng_buffer_size(), GFP_KERNEL); | |
622 | if (!rng_fillbuf) { | |
623 | kfree(rng_buffer); | |
624 | return -ENOMEM; | |
625 | } | |
626 | ||
627 | ret = register_miscdev(); | |
628 | if (ret) { | |
629 | kfree(rng_fillbuf); | |
630 | kfree(rng_buffer); | |
631 | } | |
632 | ||
633 | return ret; | |
ac3a497f HX |
634 | } |
635 | ||
636 | static void __exit hwrng_modexit(void) | |
b7d44d94 ST |
637 | { |
638 | mutex_lock(&rng_mutex); | |
639 | BUG_ON(current_rng); | |
640 | kfree(rng_buffer); | |
be4000bc | 641 | kfree(rng_fillbuf); |
b7d44d94 | 642 | mutex_unlock(&rng_mutex); |
ac3a497f HX |
643 | |
644 | unregister_miscdev(); | |
b7d44d94 ST |
645 | } |
646 | ||
ac3a497f HX |
647 | module_init(hwrng_modinit); |
648 | module_exit(hwrng_modexit); | |
844dd05f MB |
649 | |
650 | MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver"); | |
651 | MODULE_LICENSE("GPL"); |