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a07fdae3 | 1 | // SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) |
1da177e4 | 2 | /* |
9f9eff85 | 3 | * Copyright (C) 2017-2022 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. |
9e95ce27 | 4 | * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005 |
5f75d9f3 JD |
5 | * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All rights reserved. |
6 | * | |
7 | * This driver produces cryptographically secure pseudorandom data. It is divided | |
8 | * into roughly six sections, each with a section header: | |
9 | * | |
10 | * - Initialization and readiness waiting. | |
11 | * - Fast key erasure RNG, the "crng". | |
12 | * - Entropy accumulation and extraction routines. | |
13 | * - Entropy collection routines. | |
14 | * - Userspace reader/writer interfaces. | |
15 | * - Sysctl interface. | |
16 | * | |
17 | * The high level overview is that there is one input pool, into which | |
18 | * various pieces of data are hashed. Some of that data is then "credited" as | |
19 | * having a certain number of bits of entropy. When enough bits of entropy are | |
20 | * available, the hash is finalized and handed as a key to a stream cipher that | |
21 | * expands it indefinitely for various consumers. This key is periodically | |
22 | * refreshed as the various entropy collectors, described below, add data to the | |
23 | * input pool and credit it. There is currently no Fortuna-like scheduler | |
24 | * involved, which can lead to malicious entropy sources causing a premature | |
25 | * reseed, and the entropy estimates are, at best, conservative guesses. | |
1da177e4 LT |
26 | */ |
27 | ||
12cd53af YL |
28 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
29 | ||
1da177e4 | 30 | #include <linux/utsname.h> |
1da177e4 LT |
31 | #include <linux/module.h> |
32 | #include <linux/kernel.h> | |
33 | #include <linux/major.h> | |
34 | #include <linux/string.h> | |
35 | #include <linux/fcntl.h> | |
36 | #include <linux/slab.h> | |
37 | #include <linux/random.h> | |
38 | #include <linux/poll.h> | |
39 | #include <linux/init.h> | |
40 | #include <linux/fs.h> | |
41 | #include <linux/genhd.h> | |
42 | #include <linux/interrupt.h> | |
27ac792c | 43 | #include <linux/mm.h> |
dd0f0cf5 | 44 | #include <linux/nodemask.h> |
1da177e4 | 45 | #include <linux/spinlock.h> |
c84dbf61 | 46 | #include <linux/kthread.h> |
1da177e4 | 47 | #include <linux/percpu.h> |
775f4b29 | 48 | #include <linux/ptrace.h> |
6265e169 | 49 | #include <linux/workqueue.h> |
0244ad00 | 50 | #include <linux/irq.h> |
4e00b339 | 51 | #include <linux/ratelimit.h> |
c6e9d6f3 TT |
52 | #include <linux/syscalls.h> |
53 | #include <linux/completion.h> | |
8da4b8c4 | 54 | #include <linux/uuid.h> |
87e7d5ab | 55 | #include <linux/uaccess.h> |
1ca1b917 | 56 | #include <crypto/chacha.h> |
9f9eff85 | 57 | #include <crypto/blake2s.h> |
1da177e4 | 58 | #include <asm/processor.h> |
1da177e4 | 59 | #include <asm/irq.h> |
775f4b29 | 60 | #include <asm/irq_regs.h> |
1da177e4 LT |
61 | #include <asm/io.h> |
62 | ||
5f1bb112 JD |
63 | /********************************************************************* |
64 | * | |
65 | * Initialization and readiness waiting. | |
66 | * | |
67 | * Much of the RNG infrastructure is devoted to various dependencies | |
68 | * being able to wait until the RNG has collected enough entropy and | |
69 | * is ready for safe consumption. | |
70 | * | |
71 | *********************************************************************/ | |
205a525c | 72 | |
e192be9d TT |
73 | /* |
74 | * crng_init = 0 --> Uninitialized | |
75 | * 1 --> Initialized | |
76 | * 2 --> Initialized from input_pool | |
77 | * | |
5f1bb112 | 78 | * crng_init is protected by base_crng->lock, and only increases |
e192be9d TT |
79 | * its value (from 0->1->2). |
80 | */ | |
81 | static int crng_init = 0; | |
43838a23 | 82 | #define crng_ready() (likely(crng_init > 1)) |
5f1bb112 JD |
83 | /* Various types of waiters for crng_init->2 transition. */ |
84 | static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); | |
85 | static struct fasync_struct *fasync; | |
86 | static DEFINE_SPINLOCK(random_ready_list_lock); | |
87 | static LIST_HEAD(random_ready_list); | |
e192be9d | 88 | |
5f1bb112 | 89 | /* Control how we warn userspace. */ |
4e00b339 TT |
90 | static struct ratelimit_state unseeded_warning = |
91 | RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3); | |
4e00b339 | 92 | static int ratelimit_disable __read_mostly; |
4e00b339 TT |
93 | module_param_named(ratelimit_disable, ratelimit_disable, int, 0644); |
94 | MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression"); | |
95 | ||
5f1bb112 JD |
96 | /* |
97 | * Returns whether or not the input pool has been seeded and thus guaranteed | |
6f98a4bf JD |
98 | * to supply cryptographically secure random numbers. This applies to |
99 | * get_random_bytes() and get_random_{u32,u64,int,long}(). | |
5f1bb112 JD |
100 | * |
101 | * Returns: true if the input pool has been seeded. | |
102 | * false if the input pool has not been seeded. | |
103 | */ | |
104 | bool rng_is_initialized(void) | |
105 | { | |
106 | return crng_ready(); | |
107 | } | |
108 | EXPORT_SYMBOL(rng_is_initialized); | |
109 | ||
110 | /* Used by wait_for_random_bytes(), and considered an entropy collector, below. */ | |
111 | static void try_to_generate_entropy(void); | |
112 | ||
113 | /* | |
114 | * Wait for the input pool to be seeded and thus guaranteed to supply | |
6f98a4bf JD |
115 | * cryptographically secure random numbers. This applies to |
116 | * get_random_bytes() and get_random_{u32,u64,int,long}(). Using any | |
117 | * of these functions without first calling this function means that | |
118 | * the returned numbers might not be cryptographically secure. | |
5f1bb112 JD |
119 | * |
120 | * Returns: 0 if the input pool has been seeded. | |
121 | * -ERESTARTSYS if the function was interrupted by a signal. | |
122 | */ | |
123 | int wait_for_random_bytes(void) | |
124 | { | |
125 | if (likely(crng_ready())) | |
126 | return 0; | |
127 | ||
128 | do { | |
129 | int ret; | |
130 | ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ); | |
131 | if (ret) | |
132 | return ret > 0 ? 0 : ret; | |
133 | ||
134 | try_to_generate_entropy(); | |
135 | } while (!crng_ready()); | |
136 | ||
137 | return 0; | |
138 | } | |
139 | EXPORT_SYMBOL(wait_for_random_bytes); | |
140 | ||
141 | /* | |
142 | * Add a callback function that will be invoked when the input | |
143 | * pool is initialised. | |
144 | * | |
145 | * returns: 0 if callback is successfully added | |
146 | * -EALREADY if pool is already initialised (callback not called) | |
147 | * -ENOENT if module for callback is not alive | |
148 | */ | |
149 | int add_random_ready_callback(struct random_ready_callback *rdy) | |
150 | { | |
151 | struct module *owner; | |
152 | unsigned long flags; | |
153 | int err = -EALREADY; | |
154 | ||
155 | if (crng_ready()) | |
156 | return err; | |
157 | ||
158 | owner = rdy->owner; | |
159 | if (!try_module_get(owner)) | |
160 | return -ENOENT; | |
161 | ||
162 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
163 | if (crng_ready()) | |
164 | goto out; | |
165 | ||
166 | owner = NULL; | |
167 | ||
168 | list_add(&rdy->list, &random_ready_list); | |
169 | err = 0; | |
170 | ||
171 | out: | |
172 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
173 | ||
174 | module_put(owner); | |
175 | ||
176 | return err; | |
177 | } | |
178 | EXPORT_SYMBOL(add_random_ready_callback); | |
179 | ||
180 | /* | |
181 | * Delete a previously registered readiness callback function. | |
182 | */ | |
183 | void del_random_ready_callback(struct random_ready_callback *rdy) | |
184 | { | |
185 | unsigned long flags; | |
186 | struct module *owner = NULL; | |
187 | ||
188 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
189 | if (!list_empty(&rdy->list)) { | |
190 | list_del_init(&rdy->list); | |
191 | owner = rdy->owner; | |
192 | } | |
193 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
194 | ||
195 | module_put(owner); | |
196 | } | |
197 | EXPORT_SYMBOL(del_random_ready_callback); | |
198 | ||
199 | static void process_random_ready_list(void) | |
200 | { | |
201 | unsigned long flags; | |
202 | struct random_ready_callback *rdy, *tmp; | |
203 | ||
204 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
205 | list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) { | |
206 | struct module *owner = rdy->owner; | |
207 | ||
208 | list_del_init(&rdy->list); | |
209 | rdy->func(rdy); | |
210 | module_put(owner); | |
211 | } | |
212 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
213 | } | |
214 | ||
215 | #define warn_unseeded_randomness(previous) \ | |
216 | _warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous)) | |
217 | ||
218 | static void _warn_unseeded_randomness(const char *func_name, void *caller, void **previous) | |
219 | { | |
220 | #ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM | |
221 | const bool print_once = false; | |
222 | #else | |
223 | static bool print_once __read_mostly; | |
224 | #endif | |
225 | ||
226 | if (print_once || crng_ready() || | |
227 | (previous && (caller == READ_ONCE(*previous)))) | |
228 | return; | |
229 | WRITE_ONCE(*previous, caller); | |
230 | #ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM | |
231 | print_once = true; | |
232 | #endif | |
233 | if (__ratelimit(&unseeded_warning)) | |
234 | printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n", | |
235 | func_name, caller, crng_init); | |
236 | } | |
237 | ||
238 | ||
3655adc7 | 239 | /********************************************************************* |
1da177e4 | 240 | * |
3655adc7 | 241 | * Fast key erasure RNG, the "crng". |
1da177e4 | 242 | * |
3655adc7 JD |
243 | * These functions expand entropy from the entropy extractor into |
244 | * long streams for external consumption using the "fast key erasure" | |
245 | * RNG described at <https://blog.cr.yp.to/20170723-random.html>. | |
e192be9d | 246 | * |
3655adc7 JD |
247 | * There are a few exported interfaces for use by other drivers: |
248 | * | |
249 | * void get_random_bytes(void *buf, size_t nbytes) | |
250 | * u32 get_random_u32() | |
251 | * u64 get_random_u64() | |
252 | * unsigned int get_random_int() | |
253 | * unsigned long get_random_long() | |
254 | * | |
255 | * These interfaces will return the requested number of random bytes | |
6f98a4bf JD |
256 | * into the given buffer or as a return value. The returned numbers are |
257 | * the same as those of getrandom(0). The integer family of functions may | |
258 | * be higher performance for one-off random integers, because they do a | |
259 | * bit of buffering and do not invoke reseeding. | |
e192be9d TT |
260 | * |
261 | *********************************************************************/ | |
262 | ||
186873c5 JD |
263 | enum { |
264 | CRNG_RESEED_INTERVAL = 300 * HZ, | |
265 | CRNG_INIT_CNT_THRESH = 2 * CHACHA_KEY_SIZE | |
266 | }; | |
267 | ||
268 | static struct { | |
269 | u8 key[CHACHA_KEY_SIZE] __aligned(__alignof__(long)); | |
270 | unsigned long birth; | |
271 | unsigned long generation; | |
272 | spinlock_t lock; | |
273 | } base_crng = { | |
274 | .lock = __SPIN_LOCK_UNLOCKED(base_crng.lock) | |
275 | }; | |
276 | ||
277 | struct crng { | |
278 | u8 key[CHACHA_KEY_SIZE]; | |
279 | unsigned long generation; | |
280 | local_lock_t lock; | |
281 | }; | |
282 | ||
283 | static DEFINE_PER_CPU(struct crng, crngs) = { | |
284 | .generation = ULONG_MAX, | |
285 | .lock = INIT_LOCAL_LOCK(crngs.lock), | |
286 | }; | |
e192be9d | 287 | |
3655adc7 JD |
288 | /* Used by crng_reseed() to extract a new seed from the input pool. */ |
289 | static bool drain_entropy(void *buf, size_t nbytes); | |
e192be9d | 290 | |
dc12baac | 291 | /* |
3655adc7 JD |
292 | * This extracts a new crng key from the input pool, but only if there is a |
293 | * sufficient amount of entropy available, in order to mitigate bruteforcing | |
294 | * of newly added bits. | |
dc12baac | 295 | */ |
a9412d51 | 296 | static void crng_reseed(void) |
e192be9d | 297 | { |
248045b8 | 298 | unsigned long flags; |
186873c5 JD |
299 | unsigned long next_gen; |
300 | u8 key[CHACHA_KEY_SIZE]; | |
7191c628 | 301 | bool finalize_init = false; |
e192be9d | 302 | |
246c03dd JD |
303 | /* Only reseed if we can, to prevent brute forcing a small amount of new bits. */ |
304 | if (!drain_entropy(key, sizeof(key))) | |
305 | return; | |
a9412d51 | 306 | |
186873c5 JD |
307 | /* |
308 | * We copy the new key into the base_crng, overwriting the old one, | |
309 | * and update the generation counter. We avoid hitting ULONG_MAX, | |
310 | * because the per-cpu crngs are initialized to ULONG_MAX, so this | |
311 | * forces new CPUs that come online to always initialize. | |
312 | */ | |
313 | spin_lock_irqsave(&base_crng.lock, flags); | |
314 | memcpy(base_crng.key, key, sizeof(base_crng.key)); | |
315 | next_gen = base_crng.generation + 1; | |
316 | if (next_gen == ULONG_MAX) | |
317 | ++next_gen; | |
318 | WRITE_ONCE(base_crng.generation, next_gen); | |
319 | WRITE_ONCE(base_crng.birth, jiffies); | |
a9412d51 | 320 | if (crng_init < 2) { |
a9412d51 | 321 | crng_init = 2; |
7191c628 DB |
322 | finalize_init = true; |
323 | } | |
324 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
325 | memzero_explicit(key, sizeof(key)); | |
326 | if (finalize_init) { | |
a9412d51 JD |
327 | process_random_ready_list(); |
328 | wake_up_interruptible(&crng_init_wait); | |
329 | kill_fasync(&fasync, SIGIO, POLL_IN); | |
330 | pr_notice("crng init done\n"); | |
331 | if (unseeded_warning.missed) { | |
332 | pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n", | |
333 | unseeded_warning.missed); | |
334 | unseeded_warning.missed = 0; | |
335 | } | |
a9412d51 | 336 | } |
e192be9d TT |
337 | } |
338 | ||
186873c5 | 339 | /* |
3655adc7 JD |
340 | * This generates a ChaCha block using the provided key, and then |
341 | * immediately overwites that key with half the block. It returns | |
342 | * the resultant ChaCha state to the user, along with the second | |
343 | * half of the block containing 32 bytes of random data that may | |
344 | * be used; random_data_len may not be greater than 32. | |
186873c5 JD |
345 | */ |
346 | static void crng_fast_key_erasure(u8 key[CHACHA_KEY_SIZE], | |
347 | u32 chacha_state[CHACHA_STATE_WORDS], | |
348 | u8 *random_data, size_t random_data_len) | |
e192be9d | 349 | { |
186873c5 | 350 | u8 first_block[CHACHA_BLOCK_SIZE]; |
009ba856 | 351 | |
186873c5 JD |
352 | BUG_ON(random_data_len > 32); |
353 | ||
354 | chacha_init_consts(chacha_state); | |
355 | memcpy(&chacha_state[4], key, CHACHA_KEY_SIZE); | |
356 | memset(&chacha_state[12], 0, sizeof(u32) * 4); | |
357 | chacha20_block(chacha_state, first_block); | |
358 | ||
359 | memcpy(key, first_block, CHACHA_KEY_SIZE); | |
360 | memcpy(random_data, first_block + CHACHA_KEY_SIZE, random_data_len); | |
361 | memzero_explicit(first_block, sizeof(first_block)); | |
1e7f583a TT |
362 | } |
363 | ||
c92e040d | 364 | /* |
186873c5 JD |
365 | * This function returns a ChaCha state that you may use for generating |
366 | * random data. It also returns up to 32 bytes on its own of random data | |
367 | * that may be used; random_data_len may not be greater than 32. | |
c92e040d | 368 | */ |
186873c5 JD |
369 | static void crng_make_state(u32 chacha_state[CHACHA_STATE_WORDS], |
370 | u8 *random_data, size_t random_data_len) | |
c92e040d | 371 | { |
248045b8 | 372 | unsigned long flags; |
186873c5 | 373 | struct crng *crng; |
c92e040d | 374 | |
186873c5 JD |
375 | BUG_ON(random_data_len > 32); |
376 | ||
377 | /* | |
378 | * For the fast path, we check whether we're ready, unlocked first, and | |
379 | * then re-check once locked later. In the case where we're really not | |
380 | * ready, we do fast key erasure with the base_crng directly, because | |
da792c6d | 381 | * this is what crng_pre_init_inject() mutates during early init. |
186873c5 JD |
382 | */ |
383 | if (unlikely(!crng_ready())) { | |
384 | bool ready; | |
385 | ||
386 | spin_lock_irqsave(&base_crng.lock, flags); | |
387 | ready = crng_ready(); | |
388 | if (!ready) | |
389 | crng_fast_key_erasure(base_crng.key, chacha_state, | |
390 | random_data, random_data_len); | |
391 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
392 | if (!ready) | |
393 | return; | |
c92e040d | 394 | } |
186873c5 JD |
395 | |
396 | /* | |
397 | * If the base_crng is more than 5 minutes old, we reseed, which | |
398 | * in turn bumps the generation counter that we check below. | |
399 | */ | |
400 | if (unlikely(time_after(jiffies, READ_ONCE(base_crng.birth) + CRNG_RESEED_INTERVAL))) | |
401 | crng_reseed(); | |
402 | ||
403 | local_lock_irqsave(&crngs.lock, flags); | |
404 | crng = raw_cpu_ptr(&crngs); | |
405 | ||
406 | /* | |
407 | * If our per-cpu crng is older than the base_crng, then it means | |
408 | * somebody reseeded the base_crng. In that case, we do fast key | |
409 | * erasure on the base_crng, and use its output as the new key | |
410 | * for our per-cpu crng. This brings us up to date with base_crng. | |
411 | */ | |
412 | if (unlikely(crng->generation != READ_ONCE(base_crng.generation))) { | |
413 | spin_lock(&base_crng.lock); | |
414 | crng_fast_key_erasure(base_crng.key, chacha_state, | |
415 | crng->key, sizeof(crng->key)); | |
416 | crng->generation = base_crng.generation; | |
417 | spin_unlock(&base_crng.lock); | |
418 | } | |
419 | ||
420 | /* | |
421 | * Finally, when we've made it this far, our per-cpu crng has an up | |
422 | * to date key, and we can do fast key erasure with it to produce | |
423 | * some random data and a ChaCha state for the caller. All other | |
424 | * branches of this function are "unlikely", so most of the time we | |
425 | * should wind up here immediately. | |
426 | */ | |
427 | crng_fast_key_erasure(crng->key, chacha_state, random_data, random_data_len); | |
428 | local_unlock_irqrestore(&crngs.lock, flags); | |
c92e040d TT |
429 | } |
430 | ||
3655adc7 | 431 | /* |
da792c6d JD |
432 | * This function is for crng_init == 0 only. It loads entropy directly |
433 | * into the crng's key, without going through the input pool. It is, | |
434 | * generally speaking, not very safe, but we use this only at early | |
435 | * boot time when it's better to have something there rather than | |
436 | * nothing. | |
3655adc7 | 437 | * |
da792c6d JD |
438 | * If account is set, then the crng_init_cnt counter is incremented. |
439 | * This shouldn't be set by functions like add_device_randomness(), | |
440 | * where we can't trust the buffer passed to it is guaranteed to be | |
441 | * unpredictable (so it might not have any entropy at all). | |
442 | * | |
443 | * Returns the number of bytes processed from input, which is bounded | |
444 | * by CRNG_INIT_CNT_THRESH if account is true. | |
3655adc7 | 445 | */ |
c2a7de4f | 446 | static size_t crng_pre_init_inject(const void *input, size_t len, bool account) |
3655adc7 JD |
447 | { |
448 | static int crng_init_cnt = 0; | |
c2a7de4f | 449 | struct blake2s_state hash; |
3655adc7 | 450 | unsigned long flags; |
3655adc7 | 451 | |
c2a7de4f | 452 | blake2s_init(&hash, sizeof(base_crng.key)); |
da792c6d | 453 | |
c2a7de4f | 454 | spin_lock_irqsave(&base_crng.lock, flags); |
3655adc7 JD |
455 | if (crng_init != 0) { |
456 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
457 | return 0; | |
458 | } | |
3655adc7 | 459 | |
da792c6d JD |
460 | if (account) |
461 | len = min_t(size_t, len, CRNG_INIT_CNT_THRESH - crng_init_cnt); | |
3655adc7 | 462 | |
c2a7de4f JD |
463 | blake2s_update(&hash, base_crng.key, sizeof(base_crng.key)); |
464 | blake2s_update(&hash, input, len); | |
465 | blake2s_final(&hash, base_crng.key); | |
3655adc7 | 466 | |
da792c6d JD |
467 | if (account) { |
468 | crng_init_cnt += len; | |
469 | if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) { | |
470 | ++base_crng.generation; | |
471 | crng_init = 1; | |
472 | } | |
473 | } | |
3655adc7 JD |
474 | |
475 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
da792c6d JD |
476 | |
477 | if (crng_init == 1) | |
478 | pr_notice("fast init done\n"); | |
479 | ||
480 | return len; | |
3655adc7 JD |
481 | } |
482 | ||
483 | static void _get_random_bytes(void *buf, size_t nbytes) | |
e192be9d | 484 | { |
186873c5 | 485 | u32 chacha_state[CHACHA_STATE_WORDS]; |
3655adc7 JD |
486 | u8 tmp[CHACHA_BLOCK_SIZE]; |
487 | size_t len; | |
488 | ||
489 | if (!nbytes) | |
490 | return; | |
491 | ||
492 | len = min_t(size_t, 32, nbytes); | |
493 | crng_make_state(chacha_state, buf, len); | |
494 | nbytes -= len; | |
495 | buf += len; | |
496 | ||
497 | while (nbytes) { | |
498 | if (nbytes < CHACHA_BLOCK_SIZE) { | |
499 | chacha20_block(chacha_state, tmp); | |
500 | memcpy(buf, tmp, nbytes); | |
501 | memzero_explicit(tmp, sizeof(tmp)); | |
502 | break; | |
503 | } | |
504 | ||
505 | chacha20_block(chacha_state, buf); | |
506 | if (unlikely(chacha_state[12] == 0)) | |
507 | ++chacha_state[13]; | |
508 | nbytes -= CHACHA_BLOCK_SIZE; | |
509 | buf += CHACHA_BLOCK_SIZE; | |
510 | } | |
511 | ||
512 | memzero_explicit(chacha_state, sizeof(chacha_state)); | |
513 | } | |
514 | ||
515 | /* | |
516 | * This function is the exported kernel interface. It returns some | |
517 | * number of good random numbers, suitable for key generation, seeding | |
518 | * TCP sequence numbers, etc. It does not rely on the hardware random | |
519 | * number generator. For random bytes direct from the hardware RNG | |
520 | * (when available), use get_random_bytes_arch(). In order to ensure | |
521 | * that the randomness provided by this function is okay, the function | |
522 | * wait_for_random_bytes() should be called and return 0 at least once | |
523 | * at any point prior. | |
524 | */ | |
525 | void get_random_bytes(void *buf, size_t nbytes) | |
526 | { | |
527 | static void *previous; | |
528 | ||
529 | warn_unseeded_randomness(&previous); | |
530 | _get_random_bytes(buf, nbytes); | |
531 | } | |
532 | EXPORT_SYMBOL(get_random_bytes); | |
533 | ||
534 | static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes) | |
535 | { | |
536 | bool large_request = nbytes > 256; | |
537 | ssize_t ret = 0; | |
538 | size_t len; | |
539 | u32 chacha_state[CHACHA_STATE_WORDS]; | |
540 | u8 output[CHACHA_BLOCK_SIZE]; | |
541 | ||
542 | if (!nbytes) | |
543 | return 0; | |
544 | ||
545 | len = min_t(size_t, 32, nbytes); | |
546 | crng_make_state(chacha_state, output, len); | |
547 | ||
548 | if (copy_to_user(buf, output, len)) | |
549 | return -EFAULT; | |
550 | nbytes -= len; | |
551 | buf += len; | |
552 | ret += len; | |
553 | ||
554 | while (nbytes) { | |
555 | if (large_request && need_resched()) { | |
556 | if (signal_pending(current)) | |
557 | break; | |
558 | schedule(); | |
559 | } | |
560 | ||
561 | chacha20_block(chacha_state, output); | |
562 | if (unlikely(chacha_state[12] == 0)) | |
563 | ++chacha_state[13]; | |
564 | ||
565 | len = min_t(size_t, nbytes, CHACHA_BLOCK_SIZE); | |
566 | if (copy_to_user(buf, output, len)) { | |
567 | ret = -EFAULT; | |
568 | break; | |
569 | } | |
570 | ||
571 | nbytes -= len; | |
572 | buf += len; | |
573 | ret += len; | |
574 | } | |
575 | ||
576 | memzero_explicit(chacha_state, sizeof(chacha_state)); | |
577 | memzero_explicit(output, sizeof(output)); | |
578 | return ret; | |
579 | } | |
580 | ||
581 | /* | |
582 | * Batched entropy returns random integers. The quality of the random | |
583 | * number is good as /dev/urandom. In order to ensure that the randomness | |
584 | * provided by this function is okay, the function wait_for_random_bytes() | |
585 | * should be called and return 0 at least once at any point prior. | |
586 | */ | |
587 | struct batched_entropy { | |
588 | union { | |
589 | /* | |
590 | * We make this 1.5x a ChaCha block, so that we get the | |
591 | * remaining 32 bytes from fast key erasure, plus one full | |
592 | * block from the detached ChaCha state. We can increase | |
593 | * the size of this later if needed so long as we keep the | |
594 | * formula of (integer_blocks + 0.5) * CHACHA_BLOCK_SIZE. | |
595 | */ | |
596 | u64 entropy_u64[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u64))]; | |
597 | u32 entropy_u32[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u32))]; | |
598 | }; | |
599 | local_lock_t lock; | |
600 | unsigned long generation; | |
601 | unsigned int position; | |
602 | }; | |
603 | ||
604 | ||
605 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = { | |
606 | .lock = INIT_LOCAL_LOCK(batched_entropy_u64.lock), | |
607 | .position = UINT_MAX | |
608 | }; | |
609 | ||
610 | u64 get_random_u64(void) | |
611 | { | |
612 | u64 ret; | |
613 | unsigned long flags; | |
614 | struct batched_entropy *batch; | |
615 | static void *previous; | |
616 | unsigned long next_gen; | |
617 | ||
618 | warn_unseeded_randomness(&previous); | |
619 | ||
620 | local_lock_irqsave(&batched_entropy_u64.lock, flags); | |
621 | batch = raw_cpu_ptr(&batched_entropy_u64); | |
622 | ||
623 | next_gen = READ_ONCE(base_crng.generation); | |
624 | if (batch->position >= ARRAY_SIZE(batch->entropy_u64) || | |
625 | next_gen != batch->generation) { | |
626 | _get_random_bytes(batch->entropy_u64, sizeof(batch->entropy_u64)); | |
627 | batch->position = 0; | |
628 | batch->generation = next_gen; | |
629 | } | |
630 | ||
631 | ret = batch->entropy_u64[batch->position]; | |
632 | batch->entropy_u64[batch->position] = 0; | |
633 | ++batch->position; | |
634 | local_unlock_irqrestore(&batched_entropy_u64.lock, flags); | |
635 | return ret; | |
636 | } | |
637 | EXPORT_SYMBOL(get_random_u64); | |
638 | ||
639 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = { | |
640 | .lock = INIT_LOCAL_LOCK(batched_entropy_u32.lock), | |
641 | .position = UINT_MAX | |
642 | }; | |
643 | ||
644 | u32 get_random_u32(void) | |
645 | { | |
646 | u32 ret; | |
647 | unsigned long flags; | |
648 | struct batched_entropy *batch; | |
649 | static void *previous; | |
650 | unsigned long next_gen; | |
651 | ||
652 | warn_unseeded_randomness(&previous); | |
653 | ||
654 | local_lock_irqsave(&batched_entropy_u32.lock, flags); | |
655 | batch = raw_cpu_ptr(&batched_entropy_u32); | |
656 | ||
657 | next_gen = READ_ONCE(base_crng.generation); | |
658 | if (batch->position >= ARRAY_SIZE(batch->entropy_u32) || | |
659 | next_gen != batch->generation) { | |
660 | _get_random_bytes(batch->entropy_u32, sizeof(batch->entropy_u32)); | |
661 | batch->position = 0; | |
662 | batch->generation = next_gen; | |
663 | } | |
664 | ||
665 | ret = batch->entropy_u32[batch->position]; | |
666 | batch->entropy_u32[batch->position] = 0; | |
667 | ++batch->position; | |
668 | local_unlock_irqrestore(&batched_entropy_u32.lock, flags); | |
669 | return ret; | |
670 | } | |
671 | EXPORT_SYMBOL(get_random_u32); | |
672 | ||
3191dd5a JD |
673 | #ifdef CONFIG_SMP |
674 | /* | |
675 | * This function is called when the CPU is coming up, with entry | |
676 | * CPUHP_RANDOM_PREPARE, which comes before CPUHP_WORKQUEUE_PREP. | |
677 | */ | |
678 | int random_prepare_cpu(unsigned int cpu) | |
679 | { | |
680 | /* | |
681 | * When the cpu comes back online, immediately invalidate both | |
682 | * the per-cpu crng and all batches, so that we serve fresh | |
683 | * randomness. | |
684 | */ | |
685 | per_cpu_ptr(&crngs, cpu)->generation = ULONG_MAX; | |
686 | per_cpu_ptr(&batched_entropy_u32, cpu)->position = UINT_MAX; | |
687 | per_cpu_ptr(&batched_entropy_u64, cpu)->position = UINT_MAX; | |
688 | return 0; | |
689 | } | |
690 | #endif | |
691 | ||
3655adc7 JD |
692 | /** |
693 | * randomize_page - Generate a random, page aligned address | |
694 | * @start: The smallest acceptable address the caller will take. | |
695 | * @range: The size of the area, starting at @start, within which the | |
696 | * random address must fall. | |
697 | * | |
698 | * If @start + @range would overflow, @range is capped. | |
699 | * | |
700 | * NOTE: Historical use of randomize_range, which this replaces, presumed that | |
701 | * @start was already page aligned. We now align it regardless. | |
702 | * | |
703 | * Return: A page aligned address within [start, start + range). On error, | |
704 | * @start is returned. | |
705 | */ | |
706 | unsigned long randomize_page(unsigned long start, unsigned long range) | |
707 | { | |
708 | if (!PAGE_ALIGNED(start)) { | |
709 | range -= PAGE_ALIGN(start) - start; | |
710 | start = PAGE_ALIGN(start); | |
711 | } | |
712 | ||
713 | if (start > ULONG_MAX - range) | |
714 | range = ULONG_MAX - start; | |
715 | ||
716 | range >>= PAGE_SHIFT; | |
717 | ||
718 | if (range == 0) | |
719 | return start; | |
720 | ||
721 | return start + (get_random_long() % range << PAGE_SHIFT); | |
722 | } | |
723 | ||
724 | /* | |
725 | * This function will use the architecture-specific hardware random | |
726 | * number generator if it is available. It is not recommended for | |
727 | * use. Use get_random_bytes() instead. It returns the number of | |
728 | * bytes filled in. | |
729 | */ | |
730 | size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes) | |
731 | { | |
732 | size_t left = nbytes; | |
733 | u8 *p = buf; | |
734 | ||
735 | while (left) { | |
736 | unsigned long v; | |
737 | size_t chunk = min_t(size_t, left, sizeof(unsigned long)); | |
738 | ||
739 | if (!arch_get_random_long(&v)) | |
740 | break; | |
741 | ||
742 | memcpy(p, &v, chunk); | |
743 | p += chunk; | |
744 | left -= chunk; | |
745 | } | |
746 | ||
747 | return nbytes - left; | |
748 | } | |
749 | EXPORT_SYMBOL(get_random_bytes_arch); | |
750 | ||
a5ed7cb1 JD |
751 | |
752 | /********************************************************************** | |
753 | * | |
754 | * Entropy accumulation and extraction routines. | |
755 | * | |
756 | * Callers may add entropy via: | |
757 | * | |
758 | * static void mix_pool_bytes(const void *in, size_t nbytes) | |
759 | * | |
760 | * After which, if added entropy should be credited: | |
761 | * | |
762 | * static void credit_entropy_bits(size_t nbits) | |
763 | * | |
764 | * Finally, extract entropy via these two, with the latter one | |
765 | * setting the entropy count to zero and extracting only if there | |
766 | * is POOL_MIN_BITS entropy credited prior: | |
767 | * | |
768 | * static void extract_entropy(void *buf, size_t nbytes) | |
769 | * static bool drain_entropy(void *buf, size_t nbytes) | |
770 | * | |
771 | **********************************************************************/ | |
772 | ||
3655adc7 JD |
773 | enum { |
774 | POOL_BITS = BLAKE2S_HASH_SIZE * 8, | |
775 | POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */ | |
776 | }; | |
777 | ||
a5ed7cb1 | 778 | /* For notifying userspace should write into /dev/random. */ |
3655adc7 JD |
779 | static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); |
780 | ||
3655adc7 JD |
781 | static struct { |
782 | struct blake2s_state hash; | |
783 | spinlock_t lock; | |
784 | unsigned int entropy_count; | |
785 | } input_pool = { | |
786 | .hash.h = { BLAKE2S_IV0 ^ (0x01010000 | BLAKE2S_HASH_SIZE), | |
787 | BLAKE2S_IV1, BLAKE2S_IV2, BLAKE2S_IV3, BLAKE2S_IV4, | |
788 | BLAKE2S_IV5, BLAKE2S_IV6, BLAKE2S_IV7 }, | |
789 | .hash.outlen = BLAKE2S_HASH_SIZE, | |
790 | .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock), | |
791 | }; | |
792 | ||
a5ed7cb1 JD |
793 | static void _mix_pool_bytes(const void *in, size_t nbytes) |
794 | { | |
795 | blake2s_update(&input_pool.hash, in, nbytes); | |
796 | } | |
3655adc7 JD |
797 | |
798 | /* | |
799 | * This function adds bytes into the entropy "pool". It does not | |
800 | * update the entropy estimate. The caller should call | |
801 | * credit_entropy_bits if this is appropriate. | |
802 | */ | |
a5ed7cb1 | 803 | static void mix_pool_bytes(const void *in, size_t nbytes) |
3655adc7 | 804 | { |
a5ed7cb1 JD |
805 | unsigned long flags; |
806 | ||
807 | spin_lock_irqsave(&input_pool.lock, flags); | |
808 | _mix_pool_bytes(in, nbytes); | |
809 | spin_unlock_irqrestore(&input_pool.lock, flags); | |
3655adc7 JD |
810 | } |
811 | ||
a5ed7cb1 JD |
812 | static void credit_entropy_bits(size_t nbits) |
813 | { | |
814 | unsigned int entropy_count, orig, add; | |
815 | ||
816 | if (!nbits) | |
817 | return; | |
818 | ||
819 | add = min_t(size_t, nbits, POOL_BITS); | |
820 | ||
821 | do { | |
822 | orig = READ_ONCE(input_pool.entropy_count); | |
823 | entropy_count = min_t(unsigned int, POOL_BITS, orig + add); | |
824 | } while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig); | |
825 | ||
826 | if (crng_init < 2 && entropy_count >= POOL_MIN_BITS) | |
827 | crng_reseed(); | |
828 | } | |
829 | ||
830 | /* | |
831 | * This is an HKDF-like construction for using the hashed collected entropy | |
832 | * as a PRF key, that's then expanded block-by-block. | |
833 | */ | |
834 | static void extract_entropy(void *buf, size_t nbytes) | |
3655adc7 JD |
835 | { |
836 | unsigned long flags; | |
a5ed7cb1 JD |
837 | u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE]; |
838 | struct { | |
839 | unsigned long rdseed[32 / sizeof(long)]; | |
840 | size_t counter; | |
841 | } block; | |
842 | size_t i; | |
843 | ||
844 | for (i = 0; i < ARRAY_SIZE(block.rdseed); ++i) { | |
845 | if (!arch_get_random_seed_long(&block.rdseed[i]) && | |
846 | !arch_get_random_long(&block.rdseed[i])) | |
847 | block.rdseed[i] = random_get_entropy(); | |
848 | } | |
3655adc7 JD |
849 | |
850 | spin_lock_irqsave(&input_pool.lock, flags); | |
a5ed7cb1 JD |
851 | |
852 | /* seed = HASHPRF(last_key, entropy_input) */ | |
853 | blake2s_final(&input_pool.hash, seed); | |
854 | ||
855 | /* next_key = HASHPRF(seed, RDSEED || 0) */ | |
856 | block.counter = 0; | |
857 | blake2s(next_key, (u8 *)&block, seed, sizeof(next_key), sizeof(block), sizeof(seed)); | |
858 | blake2s_init_key(&input_pool.hash, BLAKE2S_HASH_SIZE, next_key, sizeof(next_key)); | |
859 | ||
3655adc7 | 860 | spin_unlock_irqrestore(&input_pool.lock, flags); |
a5ed7cb1 JD |
861 | memzero_explicit(next_key, sizeof(next_key)); |
862 | ||
863 | while (nbytes) { | |
864 | i = min_t(size_t, nbytes, BLAKE2S_HASH_SIZE); | |
865 | /* output = HASHPRF(seed, RDSEED || ++counter) */ | |
866 | ++block.counter; | |
867 | blake2s(buf, (u8 *)&block, seed, i, sizeof(block), sizeof(seed)); | |
868 | nbytes -= i; | |
869 | buf += i; | |
870 | } | |
871 | ||
872 | memzero_explicit(seed, sizeof(seed)); | |
873 | memzero_explicit(&block, sizeof(block)); | |
874 | } | |
875 | ||
876 | /* | |
877 | * First we make sure we have POOL_MIN_BITS of entropy in the pool, and then we | |
878 | * set the entropy count to zero (but don't actually touch any data). Only then | |
879 | * can we extract a new key with extract_entropy(). | |
880 | */ | |
881 | static bool drain_entropy(void *buf, size_t nbytes) | |
882 | { | |
883 | unsigned int entropy_count; | |
884 | do { | |
885 | entropy_count = READ_ONCE(input_pool.entropy_count); | |
886 | if (entropy_count < POOL_MIN_BITS) | |
887 | return false; | |
888 | } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count); | |
889 | extract_entropy(buf, nbytes); | |
890 | wake_up_interruptible(&random_write_wait); | |
891 | kill_fasync(&fasync, SIGIO, POLL_OUT); | |
892 | return true; | |
3655adc7 JD |
893 | } |
894 | ||
92c653cf JD |
895 | |
896 | /********************************************************************** | |
897 | * | |
898 | * Entropy collection routines. | |
899 | * | |
900 | * The following exported functions are used for pushing entropy into | |
901 | * the above entropy accumulation routines: | |
902 | * | |
903 | * void add_device_randomness(const void *buf, size_t size); | |
904 | * void add_input_randomness(unsigned int type, unsigned int code, | |
905 | * unsigned int value); | |
906 | * void add_disk_randomness(struct gendisk *disk); | |
907 | * void add_hwgenerator_randomness(const void *buffer, size_t count, | |
908 | * size_t entropy); | |
909 | * void add_bootloader_randomness(const void *buf, size_t size); | |
910 | * void add_interrupt_randomness(int irq); | |
911 | * | |
912 | * add_device_randomness() adds data to the input pool that | |
913 | * is likely to differ between two devices (or possibly even per boot). | |
914 | * This would be things like MAC addresses or serial numbers, or the | |
915 | * read-out of the RTC. This does *not* credit any actual entropy to | |
916 | * the pool, but it initializes the pool to different values for devices | |
917 | * that might otherwise be identical and have very little entropy | |
918 | * available to them (particularly common in the embedded world). | |
919 | * | |
920 | * add_input_randomness() uses the input layer interrupt timing, as well | |
921 | * as the event type information from the hardware. | |
922 | * | |
923 | * add_disk_randomness() uses what amounts to the seek time of block | |
924 | * layer request events, on a per-disk_devt basis, as input to the | |
925 | * entropy pool. Note that high-speed solid state drives with very low | |
926 | * seek times do not make for good sources of entropy, as their seek | |
927 | * times are usually fairly consistent. | |
928 | * | |
929 | * The above two routines try to estimate how many bits of entropy | |
930 | * to credit. They do this by keeping track of the first and second | |
931 | * order deltas of the event timings. | |
932 | * | |
933 | * add_hwgenerator_randomness() is for true hardware RNGs, and will credit | |
934 | * entropy as specified by the caller. If the entropy pool is full it will | |
935 | * block until more entropy is needed. | |
936 | * | |
937 | * add_bootloader_randomness() is the same as add_hwgenerator_randomness() or | |
938 | * add_device_randomness(), depending on whether or not the configuration | |
939 | * option CONFIG_RANDOM_TRUST_BOOTLOADER is set. | |
940 | * | |
941 | * add_interrupt_randomness() uses the interrupt timing as random | |
942 | * inputs to the entropy pool. Using the cycle counters and the irq source | |
943 | * as inputs, it feeds the input pool roughly once a second or after 64 | |
944 | * interrupts, crediting 1 bit of entropy for whichever comes first. | |
945 | * | |
946 | **********************************************************************/ | |
947 | ||
948 | static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU); | |
949 | static int __init parse_trust_cpu(char *arg) | |
950 | { | |
951 | return kstrtobool(arg, &trust_cpu); | |
952 | } | |
953 | early_param("random.trust_cpu", parse_trust_cpu); | |
3655adc7 JD |
954 | |
955 | /* | |
92c653cf JD |
956 | * The first collection of entropy occurs at system boot while interrupts |
957 | * are still turned off. Here we push in RDSEED, a timestamp, and utsname(). | |
958 | * Depending on the above configuration knob, RDSEED may be considered | |
959 | * sufficient for initialization. Note that much earlier setup may already | |
960 | * have pushed entropy into the input pool by the time we get here. | |
3655adc7 | 961 | */ |
92c653cf | 962 | int __init rand_initialize(void) |
3655adc7 | 963 | { |
92c653cf JD |
964 | size_t i; |
965 | ktime_t now = ktime_get_real(); | |
966 | bool arch_init = true; | |
967 | unsigned long rv; | |
186873c5 | 968 | |
92c653cf JD |
969 | for (i = 0; i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) { |
970 | if (!arch_get_random_seed_long_early(&rv) && | |
971 | !arch_get_random_long_early(&rv)) { | |
972 | rv = random_get_entropy(); | |
973 | arch_init = false; | |
974 | } | |
afba0b80 | 975 | _mix_pool_bytes(&rv, sizeof(rv)); |
92c653cf | 976 | } |
afba0b80 JD |
977 | _mix_pool_bytes(&now, sizeof(now)); |
978 | _mix_pool_bytes(utsname(), sizeof(*(utsname()))); | |
186873c5 | 979 | |
92c653cf JD |
980 | extract_entropy(base_crng.key, sizeof(base_crng.key)); |
981 | ++base_crng.generation; | |
186873c5 | 982 | |
92c653cf JD |
983 | if (arch_init && trust_cpu && crng_init < 2) { |
984 | crng_init = 2; | |
985 | pr_notice("crng init done (trusting CPU's manufacturer)\n"); | |
986 | } | |
e192be9d | 987 | |
6f98a4bf | 988 | if (ratelimit_disable) |
92c653cf | 989 | unseeded_warning.interval = 0; |
92c653cf | 990 | return 0; |
3655adc7 | 991 | } |
e192be9d | 992 | |
a2080a67 | 993 | /* |
e192be9d TT |
994 | * Add device- or boot-specific data to the input pool to help |
995 | * initialize it. | |
a2080a67 | 996 | * |
e192be9d TT |
997 | * None of this adds any entropy; it is meant to avoid the problem of |
998 | * the entropy pool having similar initial state across largely | |
999 | * identical devices. | |
a2080a67 | 1000 | */ |
04ec96b7 | 1001 | void add_device_randomness(const void *buf, size_t size) |
a2080a67 | 1002 | { |
abded93e JD |
1003 | cycles_t cycles = random_get_entropy(); |
1004 | unsigned long flags, now = jiffies; | |
a2080a67 | 1005 | |
1daf2f38 | 1006 | if (crng_init == 0 && size) |
c2a7de4f | 1007 | crng_pre_init_inject(buf, size, false); |
ee7998c5 | 1008 | |
3ef4cb2d | 1009 | spin_lock_irqsave(&input_pool.lock, flags); |
abded93e JD |
1010 | _mix_pool_bytes(&cycles, sizeof(cycles)); |
1011 | _mix_pool_bytes(&now, sizeof(now)); | |
90ed1e67 | 1012 | _mix_pool_bytes(buf, size); |
3ef4cb2d | 1013 | spin_unlock_irqrestore(&input_pool.lock, flags); |
a2080a67 LT |
1014 | } |
1015 | EXPORT_SYMBOL(add_device_randomness); | |
1016 | ||
abded93e JD |
1017 | /* There is one of these per entropy source */ |
1018 | struct timer_rand_state { | |
1019 | unsigned long last_time; | |
1020 | long last_delta, last_delta2; | |
1021 | }; | |
1022 | ||
1da177e4 LT |
1023 | /* |
1024 | * This function adds entropy to the entropy "pool" by using timing | |
1025 | * delays. It uses the timer_rand_state structure to make an estimate | |
1026 | * of how many bits of entropy this call has added to the pool. | |
1027 | * | |
1028 | * The number "num" is also added to the pool - it should somehow describe | |
1029 | * the type of event which just happened. This is currently 0-255 for | |
1030 | * keyboard scan codes, and 256 upwards for interrupts. | |
1da177e4 | 1031 | */ |
04ec96b7 | 1032 | static void add_timer_randomness(struct timer_rand_state *state, unsigned int num) |
1da177e4 | 1033 | { |
abded93e JD |
1034 | cycles_t cycles = random_get_entropy(); |
1035 | unsigned long flags, now = jiffies; | |
1da177e4 LT |
1036 | long delta, delta2, delta3; |
1037 | ||
abded93e JD |
1038 | spin_lock_irqsave(&input_pool.lock, flags); |
1039 | _mix_pool_bytes(&cycles, sizeof(cycles)); | |
1040 | _mix_pool_bytes(&now, sizeof(now)); | |
1041 | _mix_pool_bytes(&num, sizeof(num)); | |
1042 | spin_unlock_irqrestore(&input_pool.lock, flags); | |
1da177e4 LT |
1043 | |
1044 | /* | |
1045 | * Calculate number of bits of randomness we probably added. | |
1046 | * We take into account the first, second and third-order deltas | |
1047 | * in order to make our estimate. | |
1048 | */ | |
abded93e JD |
1049 | delta = now - READ_ONCE(state->last_time); |
1050 | WRITE_ONCE(state->last_time, now); | |
5e747dd9 | 1051 | |
e00d996a QC |
1052 | delta2 = delta - READ_ONCE(state->last_delta); |
1053 | WRITE_ONCE(state->last_delta, delta); | |
5e747dd9 | 1054 | |
e00d996a QC |
1055 | delta3 = delta2 - READ_ONCE(state->last_delta2); |
1056 | WRITE_ONCE(state->last_delta2, delta2); | |
5e747dd9 RV |
1057 | |
1058 | if (delta < 0) | |
1059 | delta = -delta; | |
1060 | if (delta2 < 0) | |
1061 | delta2 = -delta2; | |
1062 | if (delta3 < 0) | |
1063 | delta3 = -delta3; | |
1064 | if (delta > delta2) | |
1065 | delta = delta2; | |
1066 | if (delta > delta3) | |
1067 | delta = delta3; | |
1da177e4 | 1068 | |
5e747dd9 RV |
1069 | /* |
1070 | * delta is now minimum absolute delta. | |
1071 | * Round down by 1 bit on general principles, | |
727d499a | 1072 | * and limit entropy estimate to 12 bits. |
5e747dd9 | 1073 | */ |
04ec96b7 | 1074 | credit_entropy_bits(min_t(unsigned int, fls(delta >> 1), 11)); |
1da177e4 LT |
1075 | } |
1076 | ||
d251575a | 1077 | void add_input_randomness(unsigned int type, unsigned int code, |
248045b8 | 1078 | unsigned int value) |
1da177e4 LT |
1079 | { |
1080 | static unsigned char last_value; | |
92c653cf | 1081 | static struct timer_rand_state input_timer_state = { INITIAL_JIFFIES }; |
1da177e4 | 1082 | |
92c653cf | 1083 | /* Ignore autorepeat and the like. */ |
1da177e4 LT |
1084 | if (value == last_value) |
1085 | return; | |
1086 | ||
1da177e4 LT |
1087 | last_value = value; |
1088 | add_timer_randomness(&input_timer_state, | |
1089 | (type << 4) ^ code ^ (code >> 4) ^ value); | |
1090 | } | |
80fc9f53 | 1091 | EXPORT_SYMBOL_GPL(add_input_randomness); |
1da177e4 | 1092 | |
92c653cf JD |
1093 | #ifdef CONFIG_BLOCK |
1094 | void add_disk_randomness(struct gendisk *disk) | |
1095 | { | |
1096 | if (!disk || !disk->random) | |
1097 | return; | |
1098 | /* First major is 1, so we get >= 0x200 here. */ | |
1099 | add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); | |
1100 | } | |
1101 | EXPORT_SYMBOL_GPL(add_disk_randomness); | |
1102 | ||
1103 | void rand_initialize_disk(struct gendisk *disk) | |
1104 | { | |
1105 | struct timer_rand_state *state; | |
1106 | ||
1107 | /* | |
1108 | * If kzalloc returns null, we just won't use that entropy | |
1109 | * source. | |
1110 | */ | |
1111 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); | |
1112 | if (state) { | |
1113 | state->last_time = INITIAL_JIFFIES; | |
1114 | disk->random = state; | |
1115 | } | |
1116 | } | |
1117 | #endif | |
1118 | ||
1119 | /* | |
1120 | * Interface for in-kernel drivers of true hardware RNGs. | |
1121 | * Those devices may produce endless random bits and will be throttled | |
1122 | * when our pool is full. | |
1123 | */ | |
1124 | void add_hwgenerator_randomness(const void *buffer, size_t count, | |
1125 | size_t entropy) | |
1126 | { | |
1127 | if (unlikely(crng_init == 0)) { | |
c2a7de4f | 1128 | size_t ret = crng_pre_init_inject(buffer, count, true); |
92c653cf JD |
1129 | mix_pool_bytes(buffer, ret); |
1130 | count -= ret; | |
1131 | buffer += ret; | |
1132 | if (!count || crng_init == 0) | |
1133 | return; | |
1134 | } | |
1135 | ||
1136 | /* | |
1137 | * Throttle writing if we're above the trickle threshold. | |
1138 | * We'll be woken up again once below POOL_MIN_BITS, when | |
1139 | * the calling thread is about to terminate, or once | |
1140 | * CRNG_RESEED_INTERVAL has elapsed. | |
1141 | */ | |
1142 | wait_event_interruptible_timeout(random_write_wait, | |
1143 | !system_wq || kthread_should_stop() || | |
1144 | input_pool.entropy_count < POOL_MIN_BITS, | |
1145 | CRNG_RESEED_INTERVAL); | |
1146 | mix_pool_bytes(buffer, count); | |
1147 | credit_entropy_bits(entropy); | |
1148 | } | |
1149 | EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); | |
1150 | ||
1151 | /* | |
1152 | * Handle random seed passed by bootloader. | |
1153 | * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise | |
1154 | * it would be regarded as device data. | |
1155 | * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER. | |
1156 | */ | |
1157 | void add_bootloader_randomness(const void *buf, size_t size) | |
1158 | { | |
1159 | if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER)) | |
1160 | add_hwgenerator_randomness(buf, size, size * 8); | |
1161 | else | |
1162 | add_device_randomness(buf, size); | |
1163 | } | |
1164 | EXPORT_SYMBOL_GPL(add_bootloader_randomness); | |
1165 | ||
1166 | struct fast_pool { | |
1167 | union { | |
1168 | u32 pool32[4]; | |
1169 | u64 pool64[2]; | |
1170 | }; | |
58340f8e | 1171 | struct work_struct mix; |
92c653cf | 1172 | unsigned long last; |
3191dd5a | 1173 | unsigned int count; |
92c653cf | 1174 | u16 reg_idx; |
92c653cf JD |
1175 | }; |
1176 | ||
1177 | /* | |
1178 | * This is a fast mixing routine used by the interrupt randomness | |
1179 | * collector. It's hardcoded for an 128 bit pool and assumes that any | |
1180 | * locks that might be needed are taken by the caller. | |
1181 | */ | |
1182 | static void fast_mix(u32 pool[4]) | |
1183 | { | |
1184 | u32 a = pool[0], b = pool[1]; | |
1185 | u32 c = pool[2], d = pool[3]; | |
1186 | ||
1187 | a += b; c += d; | |
1188 | b = rol32(b, 6); d = rol32(d, 27); | |
1189 | d ^= a; b ^= c; | |
1190 | ||
1191 | a += b; c += d; | |
1192 | b = rol32(b, 16); d = rol32(d, 14); | |
1193 | d ^= a; b ^= c; | |
1194 | ||
1195 | a += b; c += d; | |
1196 | b = rol32(b, 6); d = rol32(d, 27); | |
1197 | d ^= a; b ^= c; | |
1198 | ||
1199 | a += b; c += d; | |
1200 | b = rol32(b, 16); d = rol32(d, 14); | |
1201 | d ^= a; b ^= c; | |
1202 | ||
1203 | pool[0] = a; pool[1] = b; | |
1204 | pool[2] = c; pool[3] = d; | |
1205 | } | |
1206 | ||
775f4b29 TT |
1207 | static DEFINE_PER_CPU(struct fast_pool, irq_randomness); |
1208 | ||
3191dd5a JD |
1209 | #ifdef CONFIG_SMP |
1210 | /* | |
1211 | * This function is called when the CPU has just come online, with | |
1212 | * entry CPUHP_AP_RANDOM_ONLINE, just after CPUHP_AP_WORKQUEUE_ONLINE. | |
1213 | */ | |
1214 | int random_online_cpu(unsigned int cpu) | |
1215 | { | |
1216 | /* | |
1217 | * During CPU shutdown and before CPU onlining, add_interrupt_ | |
1218 | * randomness() may schedule mix_interrupt_randomness(), and | |
1219 | * set the MIX_INFLIGHT flag. However, because the worker can | |
1220 | * be scheduled on a different CPU during this period, that | |
1221 | * flag will never be cleared. For that reason, we zero out | |
1222 | * the flag here, which runs just after workqueues are onlined | |
1223 | * for the CPU again. This also has the effect of setting the | |
1224 | * irq randomness count to zero so that new accumulated irqs | |
1225 | * are fresh. | |
1226 | */ | |
1227 | per_cpu_ptr(&irq_randomness, cpu)->count = 0; | |
1228 | return 0; | |
1229 | } | |
1230 | #endif | |
1231 | ||
da3951eb | 1232 | static unsigned long get_reg(struct fast_pool *f, struct pt_regs *regs) |
ee3e00e9 | 1233 | { |
da3951eb | 1234 | unsigned long *ptr = (unsigned long *)regs; |
92e75428 | 1235 | unsigned int idx; |
ee3e00e9 TT |
1236 | |
1237 | if (regs == NULL) | |
1238 | return 0; | |
92e75428 | 1239 | idx = READ_ONCE(f->reg_idx); |
da3951eb | 1240 | if (idx >= sizeof(struct pt_regs) / sizeof(unsigned long)) |
92e75428 TT |
1241 | idx = 0; |
1242 | ptr += idx++; | |
1243 | WRITE_ONCE(f->reg_idx, idx); | |
9dfa7bba | 1244 | return *ptr; |
ee3e00e9 TT |
1245 | } |
1246 | ||
58340f8e JD |
1247 | static void mix_interrupt_randomness(struct work_struct *work) |
1248 | { | |
1249 | struct fast_pool *fast_pool = container_of(work, struct fast_pool, mix); | |
1250 | u32 pool[4]; | |
1251 | ||
1252 | /* Check to see if we're running on the wrong CPU due to hotplug. */ | |
1253 | local_irq_disable(); | |
1254 | if (fast_pool != this_cpu_ptr(&irq_randomness)) { | |
1255 | local_irq_enable(); | |
58340f8e JD |
1256 | return; |
1257 | } | |
1258 | ||
1259 | /* | |
1260 | * Copy the pool to the stack so that the mixer always has a | |
1261 | * consistent view, before we reenable irqs again. | |
1262 | */ | |
1263 | memcpy(pool, fast_pool->pool32, sizeof(pool)); | |
3191dd5a | 1264 | fast_pool->count = 0; |
58340f8e JD |
1265 | fast_pool->last = jiffies; |
1266 | local_irq_enable(); | |
1267 | ||
c2a7de4f JD |
1268 | if (unlikely(crng_init == 0)) { |
1269 | crng_pre_init_inject(pool, sizeof(pool), true); | |
1270 | mix_pool_bytes(pool, sizeof(pool)); | |
1271 | } else { | |
1272 | mix_pool_bytes(pool, sizeof(pool)); | |
1273 | credit_entropy_bits(1); | |
1274 | } | |
1275 | ||
58340f8e JD |
1276 | memzero_explicit(pool, sizeof(pool)); |
1277 | } | |
1278 | ||
703f7066 | 1279 | void add_interrupt_randomness(int irq) |
1da177e4 | 1280 | { |
58340f8e | 1281 | enum { MIX_INFLIGHT = 1U << 31 }; |
abded93e JD |
1282 | cycles_t cycles = random_get_entropy(); |
1283 | unsigned long now = jiffies; | |
248045b8 JD |
1284 | struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness); |
1285 | struct pt_regs *regs = get_irq_regs(); | |
58340f8e | 1286 | unsigned int new_count; |
3060d6fe | 1287 | |
ee3e00e9 TT |
1288 | if (cycles == 0) |
1289 | cycles = get_reg(fast_pool, regs); | |
3060d6fe | 1290 | |
b2f408fe JD |
1291 | if (sizeof(cycles) == 8) |
1292 | fast_pool->pool64[0] ^= cycles ^ rol64(now, 32) ^ irq; | |
1293 | else { | |
1294 | fast_pool->pool32[0] ^= cycles ^ irq; | |
1295 | fast_pool->pool32[1] ^= now; | |
1296 | } | |
1297 | ||
1298 | if (sizeof(unsigned long) == 8) | |
1299 | fast_pool->pool64[1] ^= regs ? instruction_pointer(regs) : _RET_IP_; | |
1300 | else { | |
1301 | fast_pool->pool32[2] ^= regs ? instruction_pointer(regs) : _RET_IP_; | |
1302 | fast_pool->pool32[3] ^= get_reg(fast_pool, regs); | |
1303 | } | |
1304 | ||
1305 | fast_mix(fast_pool->pool32); | |
3191dd5a | 1306 | new_count = ++fast_pool->count; |
3060d6fe | 1307 | |
58340f8e | 1308 | if (new_count & MIX_INFLIGHT) |
1da177e4 LT |
1309 | return; |
1310 | ||
c2a7de4f JD |
1311 | if (new_count < 64 && (!time_after(now, fast_pool->last + HZ) || |
1312 | unlikely(crng_init == 0))) | |
91fcb532 | 1313 | return; |
83664a69 | 1314 | |
58340f8e JD |
1315 | if (unlikely(!fast_pool->mix.func)) |
1316 | INIT_WORK(&fast_pool->mix, mix_interrupt_randomness); | |
3191dd5a | 1317 | fast_pool->count |= MIX_INFLIGHT; |
58340f8e | 1318 | queue_work_on(raw_smp_processor_id(), system_highpri_wq, &fast_pool->mix); |
1da177e4 | 1319 | } |
4b44f2d1 | 1320 | EXPORT_SYMBOL_GPL(add_interrupt_randomness); |
1da177e4 | 1321 | |
50ee7529 LT |
1322 | /* |
1323 | * Each time the timer fires, we expect that we got an unpredictable | |
1324 | * jump in the cycle counter. Even if the timer is running on another | |
1325 | * CPU, the timer activity will be touching the stack of the CPU that is | |
1326 | * generating entropy.. | |
1327 | * | |
1328 | * Note that we don't re-arm the timer in the timer itself - we are | |
1329 | * happy to be scheduled away, since that just makes the load more | |
1330 | * complex, but we do not want the timer to keep ticking unless the | |
1331 | * entropy loop is running. | |
1332 | * | |
1333 | * So the re-arming always happens in the entropy loop itself. | |
1334 | */ | |
1335 | static void entropy_timer(struct timer_list *t) | |
1336 | { | |
90ed1e67 | 1337 | credit_entropy_bits(1); |
50ee7529 LT |
1338 | } |
1339 | ||
1340 | /* | |
1341 | * If we have an actual cycle counter, see if we can | |
1342 | * generate enough entropy with timing noise | |
1343 | */ | |
1344 | static void try_to_generate_entropy(void) | |
1345 | { | |
1346 | struct { | |
abded93e | 1347 | cycles_t cycles; |
50ee7529 LT |
1348 | struct timer_list timer; |
1349 | } stack; | |
1350 | ||
abded93e | 1351 | stack.cycles = random_get_entropy(); |
50ee7529 LT |
1352 | |
1353 | /* Slow counter - or none. Don't even bother */ | |
abded93e | 1354 | if (stack.cycles == random_get_entropy()) |
50ee7529 LT |
1355 | return; |
1356 | ||
1357 | timer_setup_on_stack(&stack.timer, entropy_timer, 0); | |
1358 | while (!crng_ready()) { | |
1359 | if (!timer_pending(&stack.timer)) | |
248045b8 | 1360 | mod_timer(&stack.timer, jiffies + 1); |
abded93e | 1361 | mix_pool_bytes(&stack.cycles, sizeof(stack.cycles)); |
50ee7529 | 1362 | schedule(); |
abded93e | 1363 | stack.cycles = random_get_entropy(); |
50ee7529 LT |
1364 | } |
1365 | ||
1366 | del_timer_sync(&stack.timer); | |
1367 | destroy_timer_on_stack(&stack.timer); | |
abded93e | 1368 | mix_pool_bytes(&stack.cycles, sizeof(stack.cycles)); |
50ee7529 LT |
1369 | } |
1370 | ||
a6adf8e7 JD |
1371 | |
1372 | /********************************************************************** | |
1373 | * | |
1374 | * Userspace reader/writer interfaces. | |
1375 | * | |
1376 | * getrandom(2) is the primary modern interface into the RNG and should | |
1377 | * be used in preference to anything else. | |
1378 | * | |
6f98a4bf JD |
1379 | * Reading from /dev/random and /dev/urandom both have the same effect |
1380 | * as calling getrandom(2) with flags=0. (In earlier versions, however, | |
1381 | * they each had different semantics.) | |
a6adf8e7 JD |
1382 | * |
1383 | * Writing to either /dev/random or /dev/urandom adds entropy to | |
1384 | * the input pool but does not credit it. | |
1385 | * | |
6f98a4bf JD |
1386 | * Polling on /dev/random or /dev/urandom indicates when the RNG |
1387 | * is initialized, on the read side, and when it wants new entropy, | |
1388 | * on the write side. | |
a6adf8e7 JD |
1389 | * |
1390 | * Both /dev/random and /dev/urandom have the same set of ioctls for | |
1391 | * adding entropy, getting the entropy count, zeroing the count, and | |
1392 | * reseeding the crng. | |
1393 | * | |
1394 | **********************************************************************/ | |
1395 | ||
1396 | SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int, | |
1397 | flags) | |
1da177e4 | 1398 | { |
a6adf8e7 JD |
1399 | if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE)) |
1400 | return -EINVAL; | |
301f0595 | 1401 | |
a6adf8e7 JD |
1402 | /* |
1403 | * Requesting insecure and blocking randomness at the same time makes | |
1404 | * no sense. | |
1405 | */ | |
1406 | if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM)) | |
1407 | return -EINVAL; | |
c6f1deb1 | 1408 | |
a6adf8e7 JD |
1409 | if (count > INT_MAX) |
1410 | count = INT_MAX; | |
1da177e4 | 1411 | |
a6adf8e7 JD |
1412 | if (!(flags & GRND_INSECURE) && !crng_ready()) { |
1413 | int ret; | |
30c08efe | 1414 | |
a6adf8e7 JD |
1415 | if (flags & GRND_NONBLOCK) |
1416 | return -EAGAIN; | |
1417 | ret = wait_for_random_bytes(); | |
1418 | if (unlikely(ret)) | |
1419 | return ret; | |
1420 | } | |
1421 | return get_random_bytes_user(buf, count); | |
30c08efe AL |
1422 | } |
1423 | ||
248045b8 | 1424 | static __poll_t random_poll(struct file *file, poll_table *wait) |
1da177e4 | 1425 | { |
a11e1d43 | 1426 | __poll_t mask; |
1da177e4 | 1427 | |
30c08efe | 1428 | poll_wait(file, &crng_init_wait, wait); |
a11e1d43 LT |
1429 | poll_wait(file, &random_write_wait, wait); |
1430 | mask = 0; | |
30c08efe | 1431 | if (crng_ready()) |
a9a08845 | 1432 | mask |= EPOLLIN | EPOLLRDNORM; |
489c7fc4 | 1433 | if (input_pool.entropy_count < POOL_MIN_BITS) |
a9a08845 | 1434 | mask |= EPOLLOUT | EPOLLWRNORM; |
1da177e4 LT |
1435 | return mask; |
1436 | } | |
1437 | ||
04ec96b7 | 1438 | static int write_pool(const char __user *ubuf, size_t count) |
1da177e4 | 1439 | { |
04ec96b7 | 1440 | size_t len; |
7b5164fb | 1441 | int ret = 0; |
04ec96b7 | 1442 | u8 block[BLAKE2S_BLOCK_SIZE]; |
1da177e4 | 1443 | |
04ec96b7 JD |
1444 | while (count) { |
1445 | len = min(count, sizeof(block)); | |
7b5164fb JD |
1446 | if (copy_from_user(block, ubuf, len)) { |
1447 | ret = -EFAULT; | |
1448 | goto out; | |
1449 | } | |
04ec96b7 JD |
1450 | count -= len; |
1451 | ubuf += len; | |
1452 | mix_pool_bytes(block, len); | |
91f3f1e3 | 1453 | cond_resched(); |
1da177e4 | 1454 | } |
7f397dcd | 1455 | |
7b5164fb JD |
1456 | out: |
1457 | memzero_explicit(block, sizeof(block)); | |
1458 | return ret; | |
7f397dcd MM |
1459 | } |
1460 | ||
90b75ee5 MM |
1461 | static ssize_t random_write(struct file *file, const char __user *buffer, |
1462 | size_t count, loff_t *ppos) | |
7f397dcd | 1463 | { |
04ec96b7 | 1464 | int ret; |
7f397dcd | 1465 | |
90ed1e67 | 1466 | ret = write_pool(buffer, count); |
7f397dcd MM |
1467 | if (ret) |
1468 | return ret; | |
1469 | ||
7f397dcd | 1470 | return (ssize_t)count; |
1da177e4 LT |
1471 | } |
1472 | ||
a6adf8e7 JD |
1473 | static ssize_t random_read(struct file *file, char __user *buf, size_t nbytes, |
1474 | loff_t *ppos) | |
1475 | { | |
1476 | int ret; | |
1477 | ||
1478 | ret = wait_for_random_bytes(); | |
1479 | if (ret != 0) | |
1480 | return ret; | |
1481 | return get_random_bytes_user(buf, nbytes); | |
1482 | } | |
1483 | ||
43ae4860 | 1484 | static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) |
1da177e4 LT |
1485 | { |
1486 | int size, ent_count; | |
1487 | int __user *p = (int __user *)arg; | |
1488 | int retval; | |
1489 | ||
1490 | switch (cmd) { | |
1491 | case RNDGETENTCNT: | |
a6adf8e7 | 1492 | /* Inherently racy, no point locking. */ |
c5704490 | 1493 | if (put_user(input_pool.entropy_count, p)) |
1da177e4 LT |
1494 | return -EFAULT; |
1495 | return 0; | |
1496 | case RNDADDTOENTCNT: | |
1497 | if (!capable(CAP_SYS_ADMIN)) | |
1498 | return -EPERM; | |
1499 | if (get_user(ent_count, p)) | |
1500 | return -EFAULT; | |
a49c010e JD |
1501 | if (ent_count < 0) |
1502 | return -EINVAL; | |
1503 | credit_entropy_bits(ent_count); | |
1504 | return 0; | |
1da177e4 LT |
1505 | case RNDADDENTROPY: |
1506 | if (!capable(CAP_SYS_ADMIN)) | |
1507 | return -EPERM; | |
1508 | if (get_user(ent_count, p++)) | |
1509 | return -EFAULT; | |
1510 | if (ent_count < 0) | |
1511 | return -EINVAL; | |
1512 | if (get_user(size, p++)) | |
1513 | return -EFAULT; | |
90ed1e67 | 1514 | retval = write_pool((const char __user *)p, size); |
1da177e4 LT |
1515 | if (retval < 0) |
1516 | return retval; | |
a49c010e JD |
1517 | credit_entropy_bits(ent_count); |
1518 | return 0; | |
1da177e4 LT |
1519 | case RNDZAPENTCNT: |
1520 | case RNDCLEARPOOL: | |
ae9ecd92 TT |
1521 | /* |
1522 | * Clear the entropy pool counters. We no longer clear | |
1523 | * the entropy pool, as that's silly. | |
1524 | */ | |
1da177e4 LT |
1525 | if (!capable(CAP_SYS_ADMIN)) |
1526 | return -EPERM; | |
a3f9e891 | 1527 | if (xchg(&input_pool.entropy_count, 0) >= POOL_MIN_BITS) { |
042e293e JD |
1528 | wake_up_interruptible(&random_write_wait); |
1529 | kill_fasync(&fasync, SIGIO, POLL_OUT); | |
1530 | } | |
1da177e4 | 1531 | return 0; |
d848e5f8 TT |
1532 | case RNDRESEEDCRNG: |
1533 | if (!capable(CAP_SYS_ADMIN)) | |
1534 | return -EPERM; | |
1535 | if (crng_init < 2) | |
1536 | return -ENODATA; | |
a9412d51 | 1537 | crng_reseed(); |
d848e5f8 | 1538 | return 0; |
1da177e4 LT |
1539 | default: |
1540 | return -EINVAL; | |
1541 | } | |
1542 | } | |
1543 | ||
9a6f70bb JD |
1544 | static int random_fasync(int fd, struct file *filp, int on) |
1545 | { | |
1546 | return fasync_helper(fd, filp, on, &fasync); | |
1547 | } | |
1548 | ||
2b8693c0 | 1549 | const struct file_operations random_fops = { |
248045b8 | 1550 | .read = random_read, |
1da177e4 | 1551 | .write = random_write, |
248045b8 | 1552 | .poll = random_poll, |
43ae4860 | 1553 | .unlocked_ioctl = random_ioctl, |
507e4e2b | 1554 | .compat_ioctl = compat_ptr_ioctl, |
9a6f70bb | 1555 | .fasync = random_fasync, |
6038f373 | 1556 | .llseek = noop_llseek, |
1da177e4 LT |
1557 | }; |
1558 | ||
0deff3c4 | 1559 | |
1da177e4 LT |
1560 | /******************************************************************** |
1561 | * | |
0deff3c4 JD |
1562 | * Sysctl interface. |
1563 | * | |
1564 | * These are partly unused legacy knobs with dummy values to not break | |
1565 | * userspace and partly still useful things. They are usually accessible | |
1566 | * in /proc/sys/kernel/random/ and are as follows: | |
1567 | * | |
1568 | * - boot_id - a UUID representing the current boot. | |
1569 | * | |
1570 | * - uuid - a random UUID, different each time the file is read. | |
1571 | * | |
1572 | * - poolsize - the number of bits of entropy that the input pool can | |
1573 | * hold, tied to the POOL_BITS constant. | |
1574 | * | |
1575 | * - entropy_avail - the number of bits of entropy currently in the | |
1576 | * input pool. Always <= poolsize. | |
1577 | * | |
1578 | * - write_wakeup_threshold - the amount of entropy in the input pool | |
1579 | * below which write polls to /dev/random will unblock, requesting | |
1580 | * more entropy, tied to the POOL_MIN_BITS constant. It is writable | |
1581 | * to avoid breaking old userspaces, but writing to it does not | |
1582 | * change any behavior of the RNG. | |
1583 | * | |
d0efdf35 | 1584 | * - urandom_min_reseed_secs - fixed to the value CRNG_RESEED_INTERVAL. |
0deff3c4 JD |
1585 | * It is writable to avoid breaking old userspaces, but writing |
1586 | * to it does not change any behavior of the RNG. | |
1da177e4 LT |
1587 | * |
1588 | ********************************************************************/ | |
1589 | ||
1590 | #ifdef CONFIG_SYSCTL | |
1591 | ||
1592 | #include <linux/sysctl.h> | |
1593 | ||
d0efdf35 | 1594 | static int sysctl_random_min_urandom_seed = CRNG_RESEED_INTERVAL / HZ; |
0deff3c4 | 1595 | static int sysctl_random_write_wakeup_bits = POOL_MIN_BITS; |
489c7fc4 | 1596 | static int sysctl_poolsize = POOL_BITS; |
64276a99 | 1597 | static u8 sysctl_bootid[UUID_SIZE]; |
1da177e4 LT |
1598 | |
1599 | /* | |
f22052b2 | 1600 | * This function is used to return both the bootid UUID, and random |
64276a99 | 1601 | * UUID. The difference is in whether table->data is NULL; if it is, |
1da177e4 | 1602 | * then a new UUID is generated and returned to the user. |
1da177e4 | 1603 | */ |
248045b8 JD |
1604 | static int proc_do_uuid(struct ctl_table *table, int write, void *buffer, |
1605 | size_t *lenp, loff_t *ppos) | |
1da177e4 | 1606 | { |
64276a99 JD |
1607 | u8 tmp_uuid[UUID_SIZE], *uuid; |
1608 | char uuid_string[UUID_STRING_LEN + 1]; | |
1609 | struct ctl_table fake_table = { | |
1610 | .data = uuid_string, | |
1611 | .maxlen = UUID_STRING_LEN | |
1612 | }; | |
1613 | ||
1614 | if (write) | |
1615 | return -EPERM; | |
1da177e4 LT |
1616 | |
1617 | uuid = table->data; | |
1618 | if (!uuid) { | |
1619 | uuid = tmp_uuid; | |
1da177e4 | 1620 | generate_random_uuid(uuid); |
44e4360f MD |
1621 | } else { |
1622 | static DEFINE_SPINLOCK(bootid_spinlock); | |
1623 | ||
1624 | spin_lock(&bootid_spinlock); | |
1625 | if (!uuid[8]) | |
1626 | generate_random_uuid(uuid); | |
1627 | spin_unlock(&bootid_spinlock); | |
1628 | } | |
1da177e4 | 1629 | |
64276a99 JD |
1630 | snprintf(uuid_string, sizeof(uuid_string), "%pU", uuid); |
1631 | return proc_dostring(&fake_table, 0, buffer, lenp, ppos); | |
1da177e4 LT |
1632 | } |
1633 | ||
77553cf8 JD |
1634 | /* The same as proc_dointvec, but writes don't change anything. */ |
1635 | static int proc_do_rointvec(struct ctl_table *table, int write, void *buffer, | |
1636 | size_t *lenp, loff_t *ppos) | |
1637 | { | |
1638 | return write ? 0 : proc_dointvec(table, 0, buffer, lenp, ppos); | |
1639 | } | |
1640 | ||
5475e8f0 | 1641 | static struct ctl_table random_table[] = { |
1da177e4 | 1642 | { |
1da177e4 LT |
1643 | .procname = "poolsize", |
1644 | .data = &sysctl_poolsize, | |
1645 | .maxlen = sizeof(int), | |
1646 | .mode = 0444, | |
6d456111 | 1647 | .proc_handler = proc_dointvec, |
1da177e4 LT |
1648 | }, |
1649 | { | |
1da177e4 | 1650 | .procname = "entropy_avail", |
c5704490 | 1651 | .data = &input_pool.entropy_count, |
1da177e4 LT |
1652 | .maxlen = sizeof(int), |
1653 | .mode = 0444, | |
c5704490 | 1654 | .proc_handler = proc_dointvec, |
1da177e4 | 1655 | }, |
1da177e4 | 1656 | { |
1da177e4 | 1657 | .procname = "write_wakeup_threshold", |
0deff3c4 | 1658 | .data = &sysctl_random_write_wakeup_bits, |
1da177e4 LT |
1659 | .maxlen = sizeof(int), |
1660 | .mode = 0644, | |
77553cf8 | 1661 | .proc_handler = proc_do_rointvec, |
1da177e4 | 1662 | }, |
f5c2742c TT |
1663 | { |
1664 | .procname = "urandom_min_reseed_secs", | |
0deff3c4 | 1665 | .data = &sysctl_random_min_urandom_seed, |
f5c2742c TT |
1666 | .maxlen = sizeof(int), |
1667 | .mode = 0644, | |
77553cf8 | 1668 | .proc_handler = proc_do_rointvec, |
f5c2742c | 1669 | }, |
1da177e4 | 1670 | { |
1da177e4 LT |
1671 | .procname = "boot_id", |
1672 | .data = &sysctl_bootid, | |
1da177e4 | 1673 | .mode = 0444, |
6d456111 | 1674 | .proc_handler = proc_do_uuid, |
1da177e4 LT |
1675 | }, |
1676 | { | |
1da177e4 | 1677 | .procname = "uuid", |
1da177e4 | 1678 | .mode = 0444, |
6d456111 | 1679 | .proc_handler = proc_do_uuid, |
1da177e4 | 1680 | }, |
894d2491 | 1681 | { } |
1da177e4 | 1682 | }; |
5475e8f0 XN |
1683 | |
1684 | /* | |
1685 | * rand_initialize() is called before sysctl_init(), | |
1686 | * so we cannot call register_sysctl_init() in rand_initialize() | |
1687 | */ | |
1688 | static int __init random_sysctls_init(void) | |
1689 | { | |
1690 | register_sysctl_init("kernel/random", random_table); | |
1691 | return 0; | |
1692 | } | |
1693 | device_initcall(random_sysctls_init); | |
0deff3c4 | 1694 | #endif |