]>
Commit | Line | Data |
---|---|---|
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 | ||
51 | static struct hwrng *current_rng; | |
52 | static LIST_HEAD(rng_list); | |
53 | static DEFINE_MUTEX(rng_mutex); | |
54 | static int data_avail; | |
55 | static u8 rng_buffer[SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES] | |
56 | __cacheline_aligned; | |
57 | ||
58 | static inline int hwrng_init(struct hwrng *rng) | |
59 | { | |
60 | if (!rng->init) | |
61 | return 0; | |
62 | return rng->init(rng); | |
63 | } | |
64 | ||
65 | static inline void hwrng_cleanup(struct hwrng *rng) | |
66 | { | |
67 | if (rng && rng->cleanup) | |
68 | rng->cleanup(rng); | |
69 | } | |
70 | ||
71 | static 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 | ||
81 | static 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 | ||
99 | static 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 | } | |
160 | out: | |
161 | return ret ? : err; | |
162 | out_unlock: | |
163 | mutex_unlock(&rng_mutex); | |
164 | goto out; | |
165 | } | |
166 | ||
167 | ||
168 | static 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 | ||
175 | static 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 | ||
183 | static 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 | ||
214 | static 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 | ||
233 | static 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 | ||
258 | static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR, | |
259 | hwrng_attr_current_show, | |
260 | hwrng_attr_current_store); | |
261 | static DEVICE_ATTR(rng_available, S_IRUGO, | |
262 | hwrng_attr_available_show, | |
263 | NULL); | |
264 | ||
265 | ||
266 | static 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 | ||
273 | static 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; | |
288 | out: | |
289 | return err; | |
290 | ||
291 | err_remove_current: | |
292 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); | |
293 | err_misc_dereg: | |
294 | misc_deregister(&rng_miscdev); | |
295 | goto out; | |
296 | } | |
297 | ||
298 | int 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); | |
338 | out_unlock: | |
339 | mutex_unlock(&rng_mutex); | |
340 | out: | |
341 | return err; | |
342 | } | |
343 | EXPORT_SYMBOL_GPL(hwrng_register); | |
344 | ||
345 | void 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 | } | |
368 | EXPORT_SYMBOL_GPL(hwrng_unregister); | |
369 | ||
370 | ||
371 | MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver"); | |
372 | MODULE_LICENSE("GPL"); |