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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
22 Copyright 2006 Michael Buesch <m@bues.ch>
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>
39#include <linux/sched.h>
40#include <linux/init.h>
41#include <linux/miscdevice.h>
42#include <linux/delay.h>
43#include <asm/uaccess.h>
44
45
46#define RNG_MODULE_NAME "hw_random"
47#define PFX RNG_MODULE_NAME ": "
48#define RNG_MISCDEV_MINOR 183 /* official */
49
50
51static struct hwrng *current_rng;
52static LIST_HEAD(rng_list);
53static DEFINE_MUTEX(rng_mutex);
54static int data_avail;
55static u8 rng_buffer[SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES]
56 __cacheline_aligned;
57
58static inline int hwrng_init(struct hwrng *rng)
59{
60 if (!rng->init)
61 return 0;
62 return rng->init(rng);
63}
64
65static inline void hwrng_cleanup(struct hwrng *rng)
66{
67 if (rng && rng->cleanup)
68 rng->cleanup(rng);
69}
70
71static int rng_dev_open(struct inode *inode, struct file *filp)
72{
73 /* enforce read-only access to this chrdev */
74 if ((filp->f_mode & FMODE_READ) == 0)
75 return -EINVAL;
76 if (filp->f_mode & FMODE_WRITE)
77 return -EINVAL;
78 return 0;
79}
80
81static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
82 int wait) {
83 int present;
84
85 if (rng->read)
86 return rng->read(rng, (void *)buffer, size, wait);
87
88 if (rng->data_present)
89 present = rng->data_present(rng, wait);
90 else
91 present = 1;
92
93 if (present)
94 return rng->data_read(rng, (u32 *)buffer);
95
96 return 0;
97}
98
99static ssize_t rng_dev_read(struct file *filp, char __user *buf,
100 size_t size, loff_t *offp)
101{
102 ssize_t ret = 0;
103 int err = 0;
104 int bytes_read, len;
105
106 while (size) {
107 if (mutex_lock_interruptible(&rng_mutex)) {
108 err = -ERESTARTSYS;
109 goto out;
110 }
111
112 if (!current_rng) {
113 err = -ENODEV;
114 goto out_unlock;
115 }
116
117 if (!data_avail) {
118 bytes_read = rng_get_data(current_rng, rng_buffer,
119 sizeof(rng_buffer),
120 !(filp->f_flags & O_NONBLOCK));
121 if (bytes_read < 0) {
122 err = bytes_read;
123 goto out_unlock;
124 }
125 data_avail = bytes_read;
126 }
127
128 if (!data_avail) {
129 if (filp->f_flags & O_NONBLOCK) {
130 err = -EAGAIN;
131 goto out_unlock;
132 }
133 } else {
134 len = data_avail;
135 if (len > size)
136 len = size;
137
138 data_avail -= len;
139
140 if (copy_to_user(buf + ret, rng_buffer + data_avail,
141 len)) {
142 err = -EFAULT;
143 goto out_unlock;
144 }
145
146 size -= len;
147 ret += len;
148 }
149
150 mutex_unlock(&rng_mutex);
151
152 if (need_resched())
153 schedule_timeout_interruptible(1);
154
155 if (signal_pending(current)) {
156 err = -ERESTARTSYS;
157 goto out;
158 }
159 }
160out:
161 return ret ? : err;
162out_unlock:
163 mutex_unlock(&rng_mutex);
164 goto out;
165}
166
167
168static const struct file_operations rng_chrdev_ops = {
169 .owner = THIS_MODULE,
170 .open = rng_dev_open,
171 .read = rng_dev_read,
172 .llseek = noop_llseek,
173};
174
175static struct miscdevice rng_miscdev = {
176 .minor = RNG_MISCDEV_MINOR,
177 .name = RNG_MODULE_NAME,
178 .nodename = "hwrng",
179 .fops = &rng_chrdev_ops,
180};
181
182
183static ssize_t hwrng_attr_current_store(struct device *dev,
184 struct device_attribute *attr,
185 const char *buf, size_t len)
186{
187 int err;
188 struct hwrng *rng;
189
190 err = mutex_lock_interruptible(&rng_mutex);
191 if (err)
192 return -ERESTARTSYS;
193 err = -ENODEV;
194 list_for_each_entry(rng, &rng_list, list) {
195 if (strcmp(rng->name, buf) == 0) {
196 if (rng == current_rng) {
197 err = 0;
198 break;
199 }
200 err = hwrng_init(rng);
201 if (err)
202 break;
203 hwrng_cleanup(current_rng);
204 current_rng = rng;
205 err = 0;
206 break;
207 }
208 }
209 mutex_unlock(&rng_mutex);
210
211 return err ? : len;
212}
213
214static ssize_t hwrng_attr_current_show(struct device *dev,
215 struct device_attribute *attr,
216 char *buf)
217{
218 int err;
219 ssize_t ret;
220 const char *name = "none";
221
222 err = mutex_lock_interruptible(&rng_mutex);
223 if (err)
224 return -ERESTARTSYS;
225 if (current_rng)
226 name = current_rng->name;
227 ret = snprintf(buf, PAGE_SIZE, "%s\n", name);
228 mutex_unlock(&rng_mutex);
229
230 return ret;
231}
232
233static ssize_t hwrng_attr_available_show(struct device *dev,
234 struct device_attribute *attr,
235 char *buf)
236{
237 int err;
238 ssize_t ret = 0;
239 struct hwrng *rng;
240
241 err = mutex_lock_interruptible(&rng_mutex);
242 if (err)
243 return -ERESTARTSYS;
244 buf[0] = '\0';
245 list_for_each_entry(rng, &rng_list, list) {
246 strncat(buf, rng->name, PAGE_SIZE - ret - 1);
247 ret += strlen(rng->name);
248 strncat(buf, " ", PAGE_SIZE - ret - 1);
249 ret++;
250 }
251 strncat(buf, "\n", PAGE_SIZE - ret - 1);
252 ret++;
253 mutex_unlock(&rng_mutex);
254
255 return ret;
256}
257
258static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,
259 hwrng_attr_current_show,
260 hwrng_attr_current_store);
261static DEVICE_ATTR(rng_available, S_IRUGO,
262 hwrng_attr_available_show,
263 NULL);
264
265
266static void unregister_miscdev(void)
267{
268 device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available);
269 device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
270 misc_deregister(&rng_miscdev);
271}
272
273static int register_miscdev(void)
274{
275 int err;
276
277 err = misc_register(&rng_miscdev);
278 if (err)
279 goto out;
280 err = device_create_file(rng_miscdev.this_device,
281 &dev_attr_rng_current);
282 if (err)
283 goto err_misc_dereg;
284 err = device_create_file(rng_miscdev.this_device,
285 &dev_attr_rng_available);
286 if (err)
287 goto err_remove_current;
288out:
289 return err;
290
291err_remove_current:
292 device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
293err_misc_dereg:
294 misc_deregister(&rng_miscdev);
295 goto out;
296}
297
298int hwrng_register(struct hwrng *rng)
299{
300 int must_register_misc;
301 int err = -EINVAL;
302 struct hwrng *old_rng, *tmp;
303
304 if (rng->name == NULL ||
305 (rng->data_read == NULL && rng->read == NULL))
306 goto out;
307
308 mutex_lock(&rng_mutex);
309
310 /* Must not register two RNGs with the same name. */
311 err = -EEXIST;
312 list_for_each_entry(tmp, &rng_list, list) {
313 if (strcmp(tmp->name, rng->name) == 0)
314 goto out_unlock;
315 }
316
317 must_register_misc = (current_rng == NULL);
318 old_rng = current_rng;
319 if (!old_rng) {
320 err = hwrng_init(rng);
321 if (err)
322 goto out_unlock;
323 current_rng = rng;
324 }
325 err = 0;
326 if (must_register_misc) {
327 err = register_miscdev();
328 if (err) {
329 if (!old_rng) {
330 hwrng_cleanup(rng);
331 current_rng = NULL;
332 }
333 goto out_unlock;
334 }
335 }
336 INIT_LIST_HEAD(&rng->list);
337 list_add_tail(&rng->list, &rng_list);
338out_unlock:
339 mutex_unlock(&rng_mutex);
340out:
341 return err;
342}
343EXPORT_SYMBOL_GPL(hwrng_register);
344
345void hwrng_unregister(struct hwrng *rng)
346{
347 int err;
348
349 mutex_lock(&rng_mutex);
350
351 list_del(&rng->list);
352 if (current_rng == rng) {
353 hwrng_cleanup(rng);
354 if (list_empty(&rng_list)) {
355 current_rng = NULL;
356 } else {
357 current_rng = list_entry(rng_list.prev, struct hwrng, list);
358 err = hwrng_init(current_rng);
359 if (err)
360 current_rng = NULL;
361 }
362 }
363 if (list_empty(&rng_list))
364 unregister_miscdev();
365
366 mutex_unlock(&rng_mutex);
367}
368EXPORT_SYMBOL_GPL(hwrng_unregister);
369
370
371MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
372MODULE_LICENSE("GPL");
1/*
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 *
7 * Please read Documentation/admin-guide/hw_random.rst for details on use.
8 *
9 * This software may be used and distributed according to the terms
10 * of the GNU General Public License, incorporated herein by reference.
11 */
12
13#include <linux/delay.h>
14#include <linux/device.h>
15#include <linux/err.h>
16#include <linux/fs.h>
17#include <linux/hw_random.h>
18#include <linux/random.h>
19#include <linux/kernel.h>
20#include <linux/kthread.h>
21#include <linux/sched/signal.h>
22#include <linux/miscdevice.h>
23#include <linux/module.h>
24#include <linux/random.h>
25#include <linux/sched.h>
26#include <linux/slab.h>
27#include <linux/uaccess.h>
28
29#define RNG_MODULE_NAME "hw_random"
30
31static struct hwrng *current_rng;
32/* the current rng has been explicitly chosen by user via sysfs */
33static int cur_rng_set_by_user;
34static struct task_struct *hwrng_fill;
35/* list of registered rngs */
36static LIST_HEAD(rng_list);
37/* Protects rng_list and current_rng */
38static DEFINE_MUTEX(rng_mutex);
39/* Protects rng read functions, data_avail, rng_buffer and rng_fillbuf */
40static DEFINE_MUTEX(reading_mutex);
41static int data_avail;
42static u8 *rng_buffer, *rng_fillbuf;
43static unsigned short current_quality;
44static unsigned short default_quality = 1024; /* default to maximum */
45
46module_param(current_quality, ushort, 0644);
47MODULE_PARM_DESC(current_quality,
48 "current hwrng entropy estimation per 1024 bits of input -- obsolete, use rng_quality instead");
49module_param(default_quality, ushort, 0644);
50MODULE_PARM_DESC(default_quality,
51 "default maximum entropy content of hwrng per 1024 bits of input");
52
53static void drop_current_rng(void);
54static int hwrng_init(struct hwrng *rng);
55static int hwrng_fillfn(void *unused);
56
57static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
58 int wait);
59
60static size_t rng_buffer_size(void)
61{
62 return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES;
63}
64
65static void add_early_randomness(struct hwrng *rng)
66{
67 int bytes_read;
68
69 mutex_lock(&reading_mutex);
70 bytes_read = rng_get_data(rng, rng_fillbuf, 32, 0);
71 mutex_unlock(&reading_mutex);
72 if (bytes_read > 0) {
73 size_t entropy = bytes_read * 8 * rng->quality / 1024;
74 add_hwgenerator_randomness(rng_fillbuf, bytes_read, entropy, false);
75 }
76}
77
78static inline void cleanup_rng(struct kref *kref)
79{
80 struct hwrng *rng = container_of(kref, struct hwrng, ref);
81
82 if (rng->cleanup)
83 rng->cleanup(rng);
84
85 complete(&rng->cleanup_done);
86}
87
88static int set_current_rng(struct hwrng *rng)
89{
90 int err;
91
92 BUG_ON(!mutex_is_locked(&rng_mutex));
93
94 err = hwrng_init(rng);
95 if (err)
96 return err;
97
98 drop_current_rng();
99 current_rng = rng;
100
101 /* if necessary, start hwrng thread */
102 if (!hwrng_fill) {
103 hwrng_fill = kthread_run(hwrng_fillfn, NULL, "hwrng");
104 if (IS_ERR(hwrng_fill)) {
105 pr_err("hwrng_fill thread creation failed\n");
106 hwrng_fill = NULL;
107 }
108 }
109
110 return 0;
111}
112
113static void drop_current_rng(void)
114{
115 BUG_ON(!mutex_is_locked(&rng_mutex));
116 if (!current_rng)
117 return;
118
119 /* decrease last reference for triggering the cleanup */
120 kref_put(¤t_rng->ref, cleanup_rng);
121 current_rng = NULL;
122}
123
124/* Returns ERR_PTR(), NULL or refcounted hwrng */
125static struct hwrng *get_current_rng_nolock(void)
126{
127 if (current_rng)
128 kref_get(¤t_rng->ref);
129
130 return current_rng;
131}
132
133static struct hwrng *get_current_rng(void)
134{
135 struct hwrng *rng;
136
137 if (mutex_lock_interruptible(&rng_mutex))
138 return ERR_PTR(-ERESTARTSYS);
139
140 rng = get_current_rng_nolock();
141
142 mutex_unlock(&rng_mutex);
143 return rng;
144}
145
146static void put_rng(struct hwrng *rng)
147{
148 /*
149 * Hold rng_mutex here so we serialize in case they set_current_rng
150 * on rng again immediately.
151 */
152 mutex_lock(&rng_mutex);
153 if (rng)
154 kref_put(&rng->ref, cleanup_rng);
155 mutex_unlock(&rng_mutex);
156}
157
158static int hwrng_init(struct hwrng *rng)
159{
160 if (kref_get_unless_zero(&rng->ref))
161 goto skip_init;
162
163 if (rng->init) {
164 int ret;
165
166 ret = rng->init(rng);
167 if (ret)
168 return ret;
169 }
170
171 kref_init(&rng->ref);
172 reinit_completion(&rng->cleanup_done);
173
174skip_init:
175 rng->quality = min_t(u16, min_t(u16, default_quality, 1024), rng->quality ?: 1024);
176 current_quality = rng->quality; /* obsolete */
177
178 return 0;
179}
180
181static int rng_dev_open(struct inode *inode, struct file *filp)
182{
183 /* enforce read-only access to this chrdev */
184 if ((filp->f_mode & FMODE_READ) == 0)
185 return -EINVAL;
186 if (filp->f_mode & FMODE_WRITE)
187 return -EINVAL;
188 return 0;
189}
190
191static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
192 int wait) {
193 int present;
194
195 BUG_ON(!mutex_is_locked(&reading_mutex));
196 if (rng->read)
197 return rng->read(rng, (void *)buffer, size, wait);
198
199 if (rng->data_present)
200 present = rng->data_present(rng, wait);
201 else
202 present = 1;
203
204 if (present)
205 return rng->data_read(rng, (u32 *)buffer);
206
207 return 0;
208}
209
210static ssize_t rng_dev_read(struct file *filp, char __user *buf,
211 size_t size, loff_t *offp)
212{
213 ssize_t ret = 0;
214 int err = 0;
215 int bytes_read, len;
216 struct hwrng *rng;
217
218 while (size) {
219 rng = get_current_rng();
220 if (IS_ERR(rng)) {
221 err = PTR_ERR(rng);
222 goto out;
223 }
224 if (!rng) {
225 err = -ENODEV;
226 goto out;
227 }
228
229 if (mutex_lock_interruptible(&reading_mutex)) {
230 err = -ERESTARTSYS;
231 goto out_put;
232 }
233 if (!data_avail) {
234 bytes_read = rng_get_data(rng, rng_buffer,
235 rng_buffer_size(),
236 !(filp->f_flags & O_NONBLOCK));
237 if (bytes_read < 0) {
238 err = bytes_read;
239 goto out_unlock_reading;
240 }
241 data_avail = bytes_read;
242 }
243
244 if (!data_avail) {
245 if (filp->f_flags & O_NONBLOCK) {
246 err = -EAGAIN;
247 goto out_unlock_reading;
248 }
249 } else {
250 len = data_avail;
251 if (len > size)
252 len = size;
253
254 data_avail -= len;
255
256 if (copy_to_user(buf + ret, rng_buffer + data_avail,
257 len)) {
258 err = -EFAULT;
259 goto out_unlock_reading;
260 }
261
262 size -= len;
263 ret += len;
264 }
265
266 mutex_unlock(&reading_mutex);
267 put_rng(rng);
268
269 if (need_resched())
270 schedule_timeout_interruptible(1);
271
272 if (signal_pending(current)) {
273 err = -ERESTARTSYS;
274 goto out;
275 }
276 }
277out:
278 return ret ? : err;
279
280out_unlock_reading:
281 mutex_unlock(&reading_mutex);
282out_put:
283 put_rng(rng);
284 goto out;
285}
286
287static const struct file_operations rng_chrdev_ops = {
288 .owner = THIS_MODULE,
289 .open = rng_dev_open,
290 .read = rng_dev_read,
291 .llseek = noop_llseek,
292};
293
294static const struct attribute_group *rng_dev_groups[];
295
296static struct miscdevice rng_miscdev = {
297 .minor = HWRNG_MINOR,
298 .name = RNG_MODULE_NAME,
299 .nodename = "hwrng",
300 .fops = &rng_chrdev_ops,
301 .groups = rng_dev_groups,
302};
303
304static int enable_best_rng(void)
305{
306 struct hwrng *rng, *new_rng = NULL;
307 int ret = -ENODEV;
308
309 BUG_ON(!mutex_is_locked(&rng_mutex));
310
311 /* no rng to use? */
312 if (list_empty(&rng_list)) {
313 drop_current_rng();
314 cur_rng_set_by_user = 0;
315 return 0;
316 }
317
318 /* use the rng which offers the best quality */
319 list_for_each_entry(rng, &rng_list, list) {
320 if (!new_rng || rng->quality > new_rng->quality)
321 new_rng = rng;
322 }
323
324 ret = ((new_rng == current_rng) ? 0 : set_current_rng(new_rng));
325 if (!ret)
326 cur_rng_set_by_user = 0;
327
328 return ret;
329}
330
331static ssize_t rng_current_store(struct device *dev,
332 struct device_attribute *attr,
333 const char *buf, size_t len)
334{
335 int err;
336 struct hwrng *rng, *old_rng, *new_rng;
337
338 err = mutex_lock_interruptible(&rng_mutex);
339 if (err)
340 return -ERESTARTSYS;
341
342 old_rng = current_rng;
343 if (sysfs_streq(buf, "")) {
344 err = enable_best_rng();
345 } else {
346 list_for_each_entry(rng, &rng_list, list) {
347 if (sysfs_streq(rng->name, buf)) {
348 err = set_current_rng(rng);
349 if (!err)
350 cur_rng_set_by_user = 1;
351 break;
352 }
353 }
354 }
355 new_rng = get_current_rng_nolock();
356 mutex_unlock(&rng_mutex);
357
358 if (new_rng) {
359 if (new_rng != old_rng)
360 add_early_randomness(new_rng);
361 put_rng(new_rng);
362 }
363
364 return err ? : len;
365}
366
367static ssize_t rng_current_show(struct device *dev,
368 struct device_attribute *attr,
369 char *buf)
370{
371 ssize_t ret;
372 struct hwrng *rng;
373
374 rng = get_current_rng();
375 if (IS_ERR(rng))
376 return PTR_ERR(rng);
377
378 ret = snprintf(buf, PAGE_SIZE, "%s\n", rng ? rng->name : "none");
379 put_rng(rng);
380
381 return ret;
382}
383
384static ssize_t rng_available_show(struct device *dev,
385 struct device_attribute *attr,
386 char *buf)
387{
388 int err;
389 struct hwrng *rng;
390
391 err = mutex_lock_interruptible(&rng_mutex);
392 if (err)
393 return -ERESTARTSYS;
394 buf[0] = '\0';
395 list_for_each_entry(rng, &rng_list, list) {
396 strlcat(buf, rng->name, PAGE_SIZE);
397 strlcat(buf, " ", PAGE_SIZE);
398 }
399 strlcat(buf, "\n", PAGE_SIZE);
400 mutex_unlock(&rng_mutex);
401
402 return strlen(buf);
403}
404
405static ssize_t rng_selected_show(struct device *dev,
406 struct device_attribute *attr,
407 char *buf)
408{
409 return sysfs_emit(buf, "%d\n", cur_rng_set_by_user);
410}
411
412static ssize_t rng_quality_show(struct device *dev,
413 struct device_attribute *attr,
414 char *buf)
415{
416 ssize_t ret;
417 struct hwrng *rng;
418
419 rng = get_current_rng();
420 if (IS_ERR(rng))
421 return PTR_ERR(rng);
422
423 if (!rng) /* no need to put_rng */
424 return -ENODEV;
425
426 ret = sysfs_emit(buf, "%hu\n", rng->quality);
427 put_rng(rng);
428
429 return ret;
430}
431
432static ssize_t rng_quality_store(struct device *dev,
433 struct device_attribute *attr,
434 const char *buf, size_t len)
435{
436 u16 quality;
437 int ret = -EINVAL;
438
439 if (len < 2)
440 return -EINVAL;
441
442 ret = mutex_lock_interruptible(&rng_mutex);
443 if (ret)
444 return -ERESTARTSYS;
445
446 ret = kstrtou16(buf, 0, &quality);
447 if (ret || quality > 1024) {
448 ret = -EINVAL;
449 goto out;
450 }
451
452 if (!current_rng) {
453 ret = -ENODEV;
454 goto out;
455 }
456
457 current_rng->quality = quality;
458 current_quality = quality; /* obsolete */
459
460 /* the best available RNG may have changed */
461 ret = enable_best_rng();
462
463out:
464 mutex_unlock(&rng_mutex);
465 return ret ? ret : len;
466}
467
468static DEVICE_ATTR_RW(rng_current);
469static DEVICE_ATTR_RO(rng_available);
470static DEVICE_ATTR_RO(rng_selected);
471static DEVICE_ATTR_RW(rng_quality);
472
473static struct attribute *rng_dev_attrs[] = {
474 &dev_attr_rng_current.attr,
475 &dev_attr_rng_available.attr,
476 &dev_attr_rng_selected.attr,
477 &dev_attr_rng_quality.attr,
478 NULL
479};
480
481ATTRIBUTE_GROUPS(rng_dev);
482
483static void __exit unregister_miscdev(void)
484{
485 misc_deregister(&rng_miscdev);
486}
487
488static int __init register_miscdev(void)
489{
490 return misc_register(&rng_miscdev);
491}
492
493static int hwrng_fillfn(void *unused)
494{
495 size_t entropy, entropy_credit = 0; /* in 1/1024 of a bit */
496 long rc;
497
498 while (!kthread_should_stop()) {
499 unsigned short quality;
500 struct hwrng *rng;
501
502 rng = get_current_rng();
503 if (IS_ERR(rng) || !rng)
504 break;
505 mutex_lock(&reading_mutex);
506 rc = rng_get_data(rng, rng_fillbuf,
507 rng_buffer_size(), 1);
508 if (current_quality != rng->quality)
509 rng->quality = current_quality; /* obsolete */
510 quality = rng->quality;
511 mutex_unlock(&reading_mutex);
512
513 if (rc <= 0)
514 hwrng_msleep(rng, 10000);
515
516 put_rng(rng);
517
518 if (rc <= 0)
519 continue;
520
521 /* If we cannot credit at least one bit of entropy,
522 * keep track of the remainder for the next iteration
523 */
524 entropy = rc * quality * 8 + entropy_credit;
525 if ((entropy >> 10) == 0)
526 entropy_credit = entropy;
527
528 /* Outside lock, sure, but y'know: randomness. */
529 add_hwgenerator_randomness((void *)rng_fillbuf, rc,
530 entropy >> 10, true);
531 }
532 hwrng_fill = NULL;
533 return 0;
534}
535
536int hwrng_register(struct hwrng *rng)
537{
538 int err = -EINVAL;
539 struct hwrng *tmp;
540 bool is_new_current = false;
541
542 if (!rng->name || (!rng->data_read && !rng->read))
543 goto out;
544
545 mutex_lock(&rng_mutex);
546
547 /* Must not register two RNGs with the same name. */
548 err = -EEXIST;
549 list_for_each_entry(tmp, &rng_list, list) {
550 if (strcmp(tmp->name, rng->name) == 0)
551 goto out_unlock;
552 }
553 list_add_tail(&rng->list, &rng_list);
554
555 init_completion(&rng->cleanup_done);
556 complete(&rng->cleanup_done);
557 init_completion(&rng->dying);
558
559 if (!current_rng ||
560 (!cur_rng_set_by_user && rng->quality > current_rng->quality)) {
561 /*
562 * Set new rng as current as the new rng source
563 * provides better entropy quality and was not
564 * chosen by userspace.
565 */
566 err = set_current_rng(rng);
567 if (err)
568 goto out_unlock;
569 /* to use current_rng in add_early_randomness() we need
570 * to take a ref
571 */
572 is_new_current = true;
573 kref_get(&rng->ref);
574 }
575 mutex_unlock(&rng_mutex);
576 if (is_new_current || !rng->init) {
577 /*
578 * Use a new device's input to add some randomness to
579 * the system. If this rng device isn't going to be
580 * used right away, its init function hasn't been
581 * called yet by set_current_rng(); so only use the
582 * randomness from devices that don't need an init callback
583 */
584 add_early_randomness(rng);
585 }
586 if (is_new_current)
587 put_rng(rng);
588 return 0;
589out_unlock:
590 mutex_unlock(&rng_mutex);
591out:
592 return err;
593}
594EXPORT_SYMBOL_GPL(hwrng_register);
595
596void hwrng_unregister(struct hwrng *rng)
597{
598 struct hwrng *old_rng, *new_rng;
599 int err;
600
601 mutex_lock(&rng_mutex);
602
603 old_rng = current_rng;
604 list_del(&rng->list);
605 complete_all(&rng->dying);
606 if (current_rng == rng) {
607 err = enable_best_rng();
608 if (err) {
609 drop_current_rng();
610 cur_rng_set_by_user = 0;
611 }
612 }
613
614 new_rng = get_current_rng_nolock();
615 if (list_empty(&rng_list)) {
616 mutex_unlock(&rng_mutex);
617 if (hwrng_fill)
618 kthread_stop(hwrng_fill);
619 } else
620 mutex_unlock(&rng_mutex);
621
622 if (new_rng) {
623 if (old_rng != new_rng)
624 add_early_randomness(new_rng);
625 put_rng(new_rng);
626 }
627
628 wait_for_completion(&rng->cleanup_done);
629}
630EXPORT_SYMBOL_GPL(hwrng_unregister);
631
632static void devm_hwrng_release(struct device *dev, void *res)
633{
634 hwrng_unregister(*(struct hwrng **)res);
635}
636
637static int devm_hwrng_match(struct device *dev, void *res, void *data)
638{
639 struct hwrng **r = res;
640
641 if (WARN_ON(!r || !*r))
642 return 0;
643
644 return *r == data;
645}
646
647int devm_hwrng_register(struct device *dev, struct hwrng *rng)
648{
649 struct hwrng **ptr;
650 int error;
651
652 ptr = devres_alloc(devm_hwrng_release, sizeof(*ptr), GFP_KERNEL);
653 if (!ptr)
654 return -ENOMEM;
655
656 error = hwrng_register(rng);
657 if (error) {
658 devres_free(ptr);
659 return error;
660 }
661
662 *ptr = rng;
663 devres_add(dev, ptr);
664 return 0;
665}
666EXPORT_SYMBOL_GPL(devm_hwrng_register);
667
668void devm_hwrng_unregister(struct device *dev, struct hwrng *rng)
669{
670 devres_release(dev, devm_hwrng_release, devm_hwrng_match, rng);
671}
672EXPORT_SYMBOL_GPL(devm_hwrng_unregister);
673
674long hwrng_msleep(struct hwrng *rng, unsigned int msecs)
675{
676 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
677
678 return wait_for_completion_interruptible_timeout(&rng->dying, timeout);
679}
680EXPORT_SYMBOL_GPL(hwrng_msleep);
681
682static int __init hwrng_modinit(void)
683{
684 int ret;
685
686 /* kmalloc makes this safe for virt_to_page() in virtio_rng.c */
687 rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL);
688 if (!rng_buffer)
689 return -ENOMEM;
690
691 rng_fillbuf = kmalloc(rng_buffer_size(), GFP_KERNEL);
692 if (!rng_fillbuf) {
693 kfree(rng_buffer);
694 return -ENOMEM;
695 }
696
697 ret = register_miscdev();
698 if (ret) {
699 kfree(rng_fillbuf);
700 kfree(rng_buffer);
701 }
702
703 return ret;
704}
705
706static void __exit hwrng_modexit(void)
707{
708 mutex_lock(&rng_mutex);
709 BUG_ON(current_rng);
710 kfree(rng_buffer);
711 kfree(rng_fillbuf);
712 mutex_unlock(&rng_mutex);
713
714 unregister_miscdev();
715}
716
717fs_initcall(hwrng_modinit); /* depends on misc_register() */
718module_exit(hwrng_modexit);
719
720MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
721MODULE_LICENSE("GPL");