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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 |
1da177e4 LT |
5 | * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All |
6 | * rights reserved. | |
1da177e4 LT |
7 | */ |
8 | ||
9 | /* | |
1da177e4 LT |
10 | * Exported interfaces ---- output |
11 | * =============================== | |
12 | * | |
92e507d2 | 13 | * There are four exported interfaces; two for use within the kernel, |
c0a8a61e | 14 | * and two for use from userspace. |
1da177e4 | 15 | * |
92e507d2 GS |
16 | * Exported interfaces ---- userspace output |
17 | * ----------------------------------------- | |
1da177e4 | 18 | * |
92e507d2 | 19 | * The userspace interfaces are two character devices /dev/random and |
1da177e4 LT |
20 | * /dev/urandom. /dev/random is suitable for use when very high |
21 | * quality randomness is desired (for example, for key generation or | |
22 | * one-time pads), as it will only return a maximum of the number of | |
23 | * bits of randomness (as estimated by the random number generator) | |
24 | * contained in the entropy pool. | |
25 | * | |
26 | * The /dev/urandom device does not have this limit, and will return | |
27 | * as many bytes as are requested. As more and more random bytes are | |
28 | * requested without giving time for the entropy pool to recharge, | |
29 | * this will result in random numbers that are merely cryptographically | |
30 | * strong. For many applications, however, this is acceptable. | |
31 | * | |
92e507d2 GS |
32 | * Exported interfaces ---- kernel output |
33 | * -------------------------------------- | |
34 | * | |
186873c5 | 35 | * The primary kernel interfaces are: |
92e507d2 | 36 | * |
04ec96b7 | 37 | * void get_random_bytes(void *buf, size_t nbytes); |
248045b8 JD |
38 | * u32 get_random_u32() |
39 | * u64 get_random_u64() | |
40 | * unsigned int get_random_int() | |
41 | * unsigned long get_random_long() | |
92e507d2 | 42 | * |
186873c5 JD |
43 | * These interfaces will return the requested number of random bytes |
44 | * into the given buffer or as a return value. This is equivalent to a | |
45 | * read from /dev/urandom. The get_random_{u32,u64,int,long}() family | |
46 | * of functions may be higher performance for one-off random integers, | |
47 | * because they do a bit of buffering. | |
92e507d2 GS |
48 | * |
49 | * prandom_u32() | |
50 | * ------------- | |
51 | * | |
52 | * For even weaker applications, see the pseudorandom generator | |
53 | * prandom_u32(), prandom_max(), and prandom_bytes(). If the random | |
54 | * numbers aren't security-critical at all, these are *far* cheaper. | |
55 | * Useful for self-tests, random error simulation, randomized backoffs, | |
56 | * and any other application where you trust that nobody is trying to | |
57 | * maliciously mess with you by guessing the "random" numbers. | |
58 | * | |
1da177e4 LT |
59 | * Exported interfaces ---- input |
60 | * ============================== | |
61 | * | |
62 | * The current exported interfaces for gathering environmental noise | |
63 | * from the devices are: | |
64 | * | |
04ec96b7 | 65 | * void add_device_randomness(const void *buf, size_t size); |
248045b8 | 66 | * void add_input_randomness(unsigned int type, unsigned int code, |
1da177e4 | 67 | * unsigned int value); |
703f7066 | 68 | * void add_interrupt_randomness(int irq); |
248045b8 | 69 | * void add_disk_randomness(struct gendisk *disk); |
04ec96b7 | 70 | * void add_hwgenerator_randomness(const void *buffer, size_t count, |
2b6c6e3d | 71 | * size_t entropy); |
04ec96b7 | 72 | * void add_bootloader_randomness(const void *buf, size_t size); |
1da177e4 | 73 | * |
a2080a67 LT |
74 | * add_device_randomness() is for adding data to the random pool that |
75 | * is likely to differ between two devices (or possibly even per boot). | |
76 | * This would be things like MAC addresses or serial numbers, or the | |
77 | * read-out of the RTC. This does *not* add any actual entropy to the | |
78 | * pool, but it initializes the pool to different values for devices | |
79 | * that might otherwise be identical and have very little entropy | |
80 | * available to them (particularly common in the embedded world). | |
81 | * | |
1da177e4 LT |
82 | * add_input_randomness() uses the input layer interrupt timing, as well as |
83 | * the event type information from the hardware. | |
84 | * | |
775f4b29 TT |
85 | * add_interrupt_randomness() uses the interrupt timing as random |
86 | * inputs to the entropy pool. Using the cycle counters and the irq source | |
87 | * as inputs, it feeds the randomness roughly once a second. | |
442a4fff JW |
88 | * |
89 | * add_disk_randomness() uses what amounts to the seek time of block | |
90 | * layer request events, on a per-disk_devt basis, as input to the | |
91 | * entropy pool. Note that high-speed solid state drives with very low | |
92 | * seek times do not make for good sources of entropy, as their seek | |
93 | * times are usually fairly consistent. | |
1da177e4 LT |
94 | * |
95 | * All of these routines try to estimate how many bits of randomness a | |
96 | * particular randomness source. They do this by keeping track of the | |
97 | * first and second order deltas of the event timings. | |
98 | * | |
2b6c6e3d MB |
99 | * add_hwgenerator_randomness() is for true hardware RNGs, and will credit |
100 | * entropy as specified by the caller. If the entropy pool is full it will | |
101 | * block until more entropy is needed. | |
102 | * | |
103 | * add_bootloader_randomness() is the same as add_hwgenerator_randomness() or | |
104 | * add_device_randomness(), depending on whether or not the configuration | |
105 | * option CONFIG_RANDOM_TRUST_BOOTLOADER is set. | |
106 | * | |
1da177e4 LT |
107 | * Ensuring unpredictability at system startup |
108 | * ============================================ | |
109 | * | |
110 | * When any operating system starts up, it will go through a sequence | |
111 | * of actions that are fairly predictable by an adversary, especially | |
112 | * if the start-up does not involve interaction with a human operator. | |
113 | * This reduces the actual number of bits of unpredictability in the | |
114 | * entropy pool below the value in entropy_count. In order to | |
115 | * counteract this effect, it helps to carry information in the | |
116 | * entropy pool across shut-downs and start-ups. To do this, put the | |
117 | * following lines an appropriate script which is run during the boot | |
118 | * sequence: | |
119 | * | |
120 | * echo "Initializing random number generator..." | |
121 | * random_seed=/var/run/random-seed | |
122 | * # Carry a random seed from start-up to start-up | |
123 | * # Load and then save the whole entropy pool | |
124 | * if [ -f $random_seed ]; then | |
125 | * cat $random_seed >/dev/urandom | |
126 | * else | |
127 | * touch $random_seed | |
128 | * fi | |
129 | * chmod 600 $random_seed | |
130 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 | |
131 | * | |
132 | * and the following lines in an appropriate script which is run as | |
133 | * the system is shutdown: | |
134 | * | |
135 | * # Carry a random seed from shut-down to start-up | |
136 | * # Save the whole entropy pool | |
137 | * echo "Saving random seed..." | |
138 | * random_seed=/var/run/random-seed | |
139 | * touch $random_seed | |
140 | * chmod 600 $random_seed | |
141 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 | |
142 | * | |
143 | * For example, on most modern systems using the System V init | |
144 | * scripts, such code fragments would be found in | |
145 | * /etc/rc.d/init.d/random. On older Linux systems, the correct script | |
146 | * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0. | |
147 | * | |
148 | * Effectively, these commands cause the contents of the entropy pool | |
149 | * to be saved at shut-down time and reloaded into the entropy pool at | |
150 | * start-up. (The 'dd' in the addition to the bootup script is to | |
151 | * make sure that /etc/random-seed is different for every start-up, | |
152 | * even if the system crashes without executing rc.0.) Even with | |
153 | * complete knowledge of the start-up activities, predicting the state | |
154 | * of the entropy pool requires knowledge of the previous history of | |
155 | * the system. | |
156 | * | |
157 | * Configuring the /dev/random driver under Linux | |
158 | * ============================================== | |
159 | * | |
160 | * The /dev/random driver under Linux uses minor numbers 8 and 9 of | |
161 | * the /dev/mem major number (#1). So if your system does not have | |
162 | * /dev/random and /dev/urandom created already, they can be created | |
163 | * by using the commands: | |
164 | * | |
248045b8 JD |
165 | * mknod /dev/random c 1 8 |
166 | * mknod /dev/urandom c 1 9 | |
1da177e4 LT |
167 | */ |
168 | ||
12cd53af YL |
169 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
170 | ||
1da177e4 | 171 | #include <linux/utsname.h> |
1da177e4 LT |
172 | #include <linux/module.h> |
173 | #include <linux/kernel.h> | |
174 | #include <linux/major.h> | |
175 | #include <linux/string.h> | |
176 | #include <linux/fcntl.h> | |
177 | #include <linux/slab.h> | |
178 | #include <linux/random.h> | |
179 | #include <linux/poll.h> | |
180 | #include <linux/init.h> | |
181 | #include <linux/fs.h> | |
182 | #include <linux/genhd.h> | |
183 | #include <linux/interrupt.h> | |
27ac792c | 184 | #include <linux/mm.h> |
dd0f0cf5 | 185 | #include <linux/nodemask.h> |
1da177e4 | 186 | #include <linux/spinlock.h> |
c84dbf61 | 187 | #include <linux/kthread.h> |
1da177e4 | 188 | #include <linux/percpu.h> |
775f4b29 | 189 | #include <linux/ptrace.h> |
6265e169 | 190 | #include <linux/workqueue.h> |
0244ad00 | 191 | #include <linux/irq.h> |
4e00b339 | 192 | #include <linux/ratelimit.h> |
c6e9d6f3 TT |
193 | #include <linux/syscalls.h> |
194 | #include <linux/completion.h> | |
8da4b8c4 | 195 | #include <linux/uuid.h> |
87e7d5ab | 196 | #include <linux/uaccess.h> |
1ca1b917 | 197 | #include <crypto/chacha.h> |
9f9eff85 | 198 | #include <crypto/blake2s.h> |
1da177e4 | 199 | #include <asm/processor.h> |
1da177e4 | 200 | #include <asm/irq.h> |
775f4b29 | 201 | #include <asm/irq_regs.h> |
1da177e4 LT |
202 | #include <asm/io.h> |
203 | ||
5f1bb112 JD |
204 | /********************************************************************* |
205 | * | |
206 | * Initialization and readiness waiting. | |
207 | * | |
208 | * Much of the RNG infrastructure is devoted to various dependencies | |
209 | * being able to wait until the RNG has collected enough entropy and | |
210 | * is ready for safe consumption. | |
211 | * | |
212 | *********************************************************************/ | |
205a525c | 213 | |
e192be9d TT |
214 | /* |
215 | * crng_init = 0 --> Uninitialized | |
216 | * 1 --> Initialized | |
217 | * 2 --> Initialized from input_pool | |
218 | * | |
5f1bb112 | 219 | * crng_init is protected by base_crng->lock, and only increases |
e192be9d TT |
220 | * its value (from 0->1->2). |
221 | */ | |
222 | static int crng_init = 0; | |
43838a23 | 223 | #define crng_ready() (likely(crng_init > 1)) |
5f1bb112 JD |
224 | /* Various types of waiters for crng_init->2 transition. */ |
225 | static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); | |
226 | static struct fasync_struct *fasync; | |
227 | static DEFINE_SPINLOCK(random_ready_list_lock); | |
228 | static LIST_HEAD(random_ready_list); | |
e192be9d | 229 | |
5f1bb112 | 230 | /* Control how we warn userspace. */ |
4e00b339 TT |
231 | static struct ratelimit_state unseeded_warning = |
232 | RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3); | |
233 | static struct ratelimit_state urandom_warning = | |
234 | RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3); | |
4e00b339 | 235 | static int ratelimit_disable __read_mostly; |
4e00b339 TT |
236 | module_param_named(ratelimit_disable, ratelimit_disable, int, 0644); |
237 | MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression"); | |
238 | ||
5f1bb112 JD |
239 | /* |
240 | * Returns whether or not the input pool has been seeded and thus guaranteed | |
241 | * to supply cryptographically secure random numbers. This applies to: the | |
242 | * /dev/urandom device, the get_random_bytes function, and the get_random_{u32, | |
243 | * ,u64,int,long} family of functions. | |
244 | * | |
245 | * Returns: true if the input pool has been seeded. | |
246 | * false if the input pool has not been seeded. | |
247 | */ | |
248 | bool rng_is_initialized(void) | |
249 | { | |
250 | return crng_ready(); | |
251 | } | |
252 | EXPORT_SYMBOL(rng_is_initialized); | |
253 | ||
254 | /* Used by wait_for_random_bytes(), and considered an entropy collector, below. */ | |
255 | static void try_to_generate_entropy(void); | |
256 | ||
257 | /* | |
258 | * Wait for the input pool to be seeded and thus guaranteed to supply | |
259 | * cryptographically secure random numbers. This applies to: the /dev/urandom | |
260 | * device, the get_random_bytes function, and the get_random_{u32,u64,int,long} | |
261 | * family of functions. Using any of these functions without first calling | |
262 | * this function forfeits the guarantee of security. | |
263 | * | |
264 | * Returns: 0 if the input pool has been seeded. | |
265 | * -ERESTARTSYS if the function was interrupted by a signal. | |
266 | */ | |
267 | int wait_for_random_bytes(void) | |
268 | { | |
269 | if (likely(crng_ready())) | |
270 | return 0; | |
271 | ||
272 | do { | |
273 | int ret; | |
274 | ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ); | |
275 | if (ret) | |
276 | return ret > 0 ? 0 : ret; | |
277 | ||
278 | try_to_generate_entropy(); | |
279 | } while (!crng_ready()); | |
280 | ||
281 | return 0; | |
282 | } | |
283 | EXPORT_SYMBOL(wait_for_random_bytes); | |
284 | ||
285 | /* | |
286 | * Add a callback function that will be invoked when the input | |
287 | * pool is initialised. | |
288 | * | |
289 | * returns: 0 if callback is successfully added | |
290 | * -EALREADY if pool is already initialised (callback not called) | |
291 | * -ENOENT if module for callback is not alive | |
292 | */ | |
293 | int add_random_ready_callback(struct random_ready_callback *rdy) | |
294 | { | |
295 | struct module *owner; | |
296 | unsigned long flags; | |
297 | int err = -EALREADY; | |
298 | ||
299 | if (crng_ready()) | |
300 | return err; | |
301 | ||
302 | owner = rdy->owner; | |
303 | if (!try_module_get(owner)) | |
304 | return -ENOENT; | |
305 | ||
306 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
307 | if (crng_ready()) | |
308 | goto out; | |
309 | ||
310 | owner = NULL; | |
311 | ||
312 | list_add(&rdy->list, &random_ready_list); | |
313 | err = 0; | |
314 | ||
315 | out: | |
316 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
317 | ||
318 | module_put(owner); | |
319 | ||
320 | return err; | |
321 | } | |
322 | EXPORT_SYMBOL(add_random_ready_callback); | |
323 | ||
324 | /* | |
325 | * Delete a previously registered readiness callback function. | |
326 | */ | |
327 | void del_random_ready_callback(struct random_ready_callback *rdy) | |
328 | { | |
329 | unsigned long flags; | |
330 | struct module *owner = NULL; | |
331 | ||
332 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
333 | if (!list_empty(&rdy->list)) { | |
334 | list_del_init(&rdy->list); | |
335 | owner = rdy->owner; | |
336 | } | |
337 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
338 | ||
339 | module_put(owner); | |
340 | } | |
341 | EXPORT_SYMBOL(del_random_ready_callback); | |
342 | ||
343 | static void process_random_ready_list(void) | |
344 | { | |
345 | unsigned long flags; | |
346 | struct random_ready_callback *rdy, *tmp; | |
347 | ||
348 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
349 | list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) { | |
350 | struct module *owner = rdy->owner; | |
351 | ||
352 | list_del_init(&rdy->list); | |
353 | rdy->func(rdy); | |
354 | module_put(owner); | |
355 | } | |
356 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
357 | } | |
358 | ||
359 | #define warn_unseeded_randomness(previous) \ | |
360 | _warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous)) | |
361 | ||
362 | static void _warn_unseeded_randomness(const char *func_name, void *caller, void **previous) | |
363 | { | |
364 | #ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM | |
365 | const bool print_once = false; | |
366 | #else | |
367 | static bool print_once __read_mostly; | |
368 | #endif | |
369 | ||
370 | if (print_once || crng_ready() || | |
371 | (previous && (caller == READ_ONCE(*previous)))) | |
372 | return; | |
373 | WRITE_ONCE(*previous, caller); | |
374 | #ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM | |
375 | print_once = true; | |
376 | #endif | |
377 | if (__ratelimit(&unseeded_warning)) | |
378 | printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n", | |
379 | func_name, caller, crng_init); | |
380 | } | |
381 | ||
382 | ||
3655adc7 | 383 | /********************************************************************* |
1da177e4 | 384 | * |
3655adc7 | 385 | * Fast key erasure RNG, the "crng". |
1da177e4 | 386 | * |
3655adc7 JD |
387 | * These functions expand entropy from the entropy extractor into |
388 | * long streams for external consumption using the "fast key erasure" | |
389 | * RNG described at <https://blog.cr.yp.to/20170723-random.html>. | |
e192be9d | 390 | * |
3655adc7 JD |
391 | * There are a few exported interfaces for use by other drivers: |
392 | * | |
393 | * void get_random_bytes(void *buf, size_t nbytes) | |
394 | * u32 get_random_u32() | |
395 | * u64 get_random_u64() | |
396 | * unsigned int get_random_int() | |
397 | * unsigned long get_random_long() | |
398 | * | |
399 | * These interfaces will return the requested number of random bytes | |
400 | * into the given buffer or as a return value. This is equivalent to | |
401 | * a read from /dev/urandom. The integer family of functions may be | |
402 | * higher performance for one-off random integers, because they do a | |
403 | * bit of buffering. | |
e192be9d TT |
404 | * |
405 | *********************************************************************/ | |
406 | ||
186873c5 JD |
407 | enum { |
408 | CRNG_RESEED_INTERVAL = 300 * HZ, | |
409 | CRNG_INIT_CNT_THRESH = 2 * CHACHA_KEY_SIZE | |
410 | }; | |
411 | ||
412 | static struct { | |
413 | u8 key[CHACHA_KEY_SIZE] __aligned(__alignof__(long)); | |
414 | unsigned long birth; | |
415 | unsigned long generation; | |
416 | spinlock_t lock; | |
417 | } base_crng = { | |
418 | .lock = __SPIN_LOCK_UNLOCKED(base_crng.lock) | |
419 | }; | |
420 | ||
421 | struct crng { | |
422 | u8 key[CHACHA_KEY_SIZE]; | |
423 | unsigned long generation; | |
424 | local_lock_t lock; | |
425 | }; | |
426 | ||
427 | static DEFINE_PER_CPU(struct crng, crngs) = { | |
428 | .generation = ULONG_MAX, | |
429 | .lock = INIT_LOCAL_LOCK(crngs.lock), | |
430 | }; | |
e192be9d | 431 | |
3655adc7 JD |
432 | /* Used by crng_reseed() to extract a new seed from the input pool. */ |
433 | static bool drain_entropy(void *buf, size_t nbytes); | |
e192be9d | 434 | |
dc12baac | 435 | /* |
3655adc7 JD |
436 | * This extracts a new crng key from the input pool, but only if there is a |
437 | * sufficient amount of entropy available, in order to mitigate bruteforcing | |
438 | * of newly added bits. | |
dc12baac | 439 | */ |
a9412d51 | 440 | static void crng_reseed(void) |
e192be9d | 441 | { |
248045b8 | 442 | unsigned long flags; |
186873c5 JD |
443 | unsigned long next_gen; |
444 | u8 key[CHACHA_KEY_SIZE]; | |
7191c628 | 445 | bool finalize_init = false; |
e192be9d | 446 | |
246c03dd JD |
447 | /* Only reseed if we can, to prevent brute forcing a small amount of new bits. */ |
448 | if (!drain_entropy(key, sizeof(key))) | |
449 | return; | |
a9412d51 | 450 | |
186873c5 JD |
451 | /* |
452 | * We copy the new key into the base_crng, overwriting the old one, | |
453 | * and update the generation counter. We avoid hitting ULONG_MAX, | |
454 | * because the per-cpu crngs are initialized to ULONG_MAX, so this | |
455 | * forces new CPUs that come online to always initialize. | |
456 | */ | |
457 | spin_lock_irqsave(&base_crng.lock, flags); | |
458 | memcpy(base_crng.key, key, sizeof(base_crng.key)); | |
459 | next_gen = base_crng.generation + 1; | |
460 | if (next_gen == ULONG_MAX) | |
461 | ++next_gen; | |
462 | WRITE_ONCE(base_crng.generation, next_gen); | |
463 | WRITE_ONCE(base_crng.birth, jiffies); | |
a9412d51 | 464 | if (crng_init < 2) { |
a9412d51 | 465 | crng_init = 2; |
7191c628 DB |
466 | finalize_init = true; |
467 | } | |
468 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
469 | memzero_explicit(key, sizeof(key)); | |
470 | if (finalize_init) { | |
a9412d51 JD |
471 | process_random_ready_list(); |
472 | wake_up_interruptible(&crng_init_wait); | |
473 | kill_fasync(&fasync, SIGIO, POLL_IN); | |
474 | pr_notice("crng init done\n"); | |
475 | if (unseeded_warning.missed) { | |
476 | pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n", | |
477 | unseeded_warning.missed); | |
478 | unseeded_warning.missed = 0; | |
479 | } | |
480 | if (urandom_warning.missed) { | |
481 | pr_notice("%d urandom warning(s) missed due to ratelimiting\n", | |
482 | urandom_warning.missed); | |
483 | urandom_warning.missed = 0; | |
484 | } | |
485 | } | |
e192be9d TT |
486 | } |
487 | ||
186873c5 | 488 | /* |
3655adc7 JD |
489 | * This generates a ChaCha block using the provided key, and then |
490 | * immediately overwites that key with half the block. It returns | |
491 | * the resultant ChaCha state to the user, along with the second | |
492 | * half of the block containing 32 bytes of random data that may | |
493 | * be used; random_data_len may not be greater than 32. | |
186873c5 JD |
494 | */ |
495 | static void crng_fast_key_erasure(u8 key[CHACHA_KEY_SIZE], | |
496 | u32 chacha_state[CHACHA_STATE_WORDS], | |
497 | u8 *random_data, size_t random_data_len) | |
e192be9d | 498 | { |
186873c5 | 499 | u8 first_block[CHACHA_BLOCK_SIZE]; |
009ba856 | 500 | |
186873c5 JD |
501 | BUG_ON(random_data_len > 32); |
502 | ||
503 | chacha_init_consts(chacha_state); | |
504 | memcpy(&chacha_state[4], key, CHACHA_KEY_SIZE); | |
505 | memset(&chacha_state[12], 0, sizeof(u32) * 4); | |
506 | chacha20_block(chacha_state, first_block); | |
507 | ||
508 | memcpy(key, first_block, CHACHA_KEY_SIZE); | |
509 | memcpy(random_data, first_block + CHACHA_KEY_SIZE, random_data_len); | |
510 | memzero_explicit(first_block, sizeof(first_block)); | |
1e7f583a TT |
511 | } |
512 | ||
c92e040d | 513 | /* |
186873c5 JD |
514 | * This function returns a ChaCha state that you may use for generating |
515 | * random data. It also returns up to 32 bytes on its own of random data | |
516 | * that may be used; random_data_len may not be greater than 32. | |
c92e040d | 517 | */ |
186873c5 JD |
518 | static void crng_make_state(u32 chacha_state[CHACHA_STATE_WORDS], |
519 | u8 *random_data, size_t random_data_len) | |
c92e040d | 520 | { |
248045b8 | 521 | unsigned long flags; |
186873c5 | 522 | struct crng *crng; |
c92e040d | 523 | |
186873c5 JD |
524 | BUG_ON(random_data_len > 32); |
525 | ||
526 | /* | |
527 | * For the fast path, we check whether we're ready, unlocked first, and | |
528 | * then re-check once locked later. In the case where we're really not | |
529 | * ready, we do fast key erasure with the base_crng directly, because | |
530 | * this is what crng_{fast,slow}_load mutate during early init. | |
531 | */ | |
532 | if (unlikely(!crng_ready())) { | |
533 | bool ready; | |
534 | ||
535 | spin_lock_irqsave(&base_crng.lock, flags); | |
536 | ready = crng_ready(); | |
537 | if (!ready) | |
538 | crng_fast_key_erasure(base_crng.key, chacha_state, | |
539 | random_data, random_data_len); | |
540 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
541 | if (!ready) | |
542 | return; | |
c92e040d | 543 | } |
186873c5 JD |
544 | |
545 | /* | |
546 | * If the base_crng is more than 5 minutes old, we reseed, which | |
547 | * in turn bumps the generation counter that we check below. | |
548 | */ | |
549 | if (unlikely(time_after(jiffies, READ_ONCE(base_crng.birth) + CRNG_RESEED_INTERVAL))) | |
550 | crng_reseed(); | |
551 | ||
552 | local_lock_irqsave(&crngs.lock, flags); | |
553 | crng = raw_cpu_ptr(&crngs); | |
554 | ||
555 | /* | |
556 | * If our per-cpu crng is older than the base_crng, then it means | |
557 | * somebody reseeded the base_crng. In that case, we do fast key | |
558 | * erasure on the base_crng, and use its output as the new key | |
559 | * for our per-cpu crng. This brings us up to date with base_crng. | |
560 | */ | |
561 | if (unlikely(crng->generation != READ_ONCE(base_crng.generation))) { | |
562 | spin_lock(&base_crng.lock); | |
563 | crng_fast_key_erasure(base_crng.key, chacha_state, | |
564 | crng->key, sizeof(crng->key)); | |
565 | crng->generation = base_crng.generation; | |
566 | spin_unlock(&base_crng.lock); | |
567 | } | |
568 | ||
569 | /* | |
570 | * Finally, when we've made it this far, our per-cpu crng has an up | |
571 | * to date key, and we can do fast key erasure with it to produce | |
572 | * some random data and a ChaCha state for the caller. All other | |
573 | * branches of this function are "unlikely", so most of the time we | |
574 | * should wind up here immediately. | |
575 | */ | |
576 | crng_fast_key_erasure(crng->key, chacha_state, random_data, random_data_len); | |
577 | local_unlock_irqrestore(&crngs.lock, flags); | |
c92e040d TT |
578 | } |
579 | ||
3655adc7 JD |
580 | /* |
581 | * This function is for crng_init == 0 only. | |
582 | * | |
583 | * crng_fast_load() can be called by code in the interrupt service | |
584 | * path. So we can't afford to dilly-dally. Returns the number of | |
585 | * bytes processed from cp. | |
586 | */ | |
587 | static size_t crng_fast_load(const void *cp, size_t len) | |
588 | { | |
589 | static int crng_init_cnt = 0; | |
590 | unsigned long flags; | |
591 | const u8 *src = (const u8 *)cp; | |
592 | size_t ret = 0; | |
593 | ||
594 | if (!spin_trylock_irqsave(&base_crng.lock, flags)) | |
595 | return 0; | |
596 | if (crng_init != 0) { | |
597 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
598 | return 0; | |
599 | } | |
600 | while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) { | |
601 | base_crng.key[crng_init_cnt % sizeof(base_crng.key)] ^= *src; | |
602 | src++; crng_init_cnt++; len--; ret++; | |
603 | } | |
604 | if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) { | |
605 | ++base_crng.generation; | |
606 | crng_init = 1; | |
607 | } | |
608 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
609 | if (crng_init == 1) | |
610 | pr_notice("fast init done\n"); | |
611 | return ret; | |
612 | } | |
613 | ||
614 | /* | |
615 | * This function is for crng_init == 0 only. | |
616 | * | |
617 | * crng_slow_load() is called by add_device_randomness, which has two | |
618 | * attributes. (1) We can't trust the buffer passed to it is | |
619 | * guaranteed to be unpredictable (so it might not have any entropy at | |
620 | * all), and (2) it doesn't have the performance constraints of | |
621 | * crng_fast_load(). | |
622 | * | |
623 | * So, we simply hash the contents in with the current key. Finally, | |
624 | * we do *not* advance crng_init_cnt since buffer we may get may be | |
625 | * something like a fixed DMI table (for example), which might very | |
626 | * well be unique to the machine, but is otherwise unvarying. | |
627 | */ | |
628 | static void crng_slow_load(const void *cp, size_t len) | |
629 | { | |
630 | unsigned long flags; | |
631 | struct blake2s_state hash; | |
632 | ||
633 | blake2s_init(&hash, sizeof(base_crng.key)); | |
634 | ||
635 | if (!spin_trylock_irqsave(&base_crng.lock, flags)) | |
636 | return; | |
637 | if (crng_init != 0) { | |
638 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
639 | return; | |
640 | } | |
641 | ||
642 | blake2s_update(&hash, base_crng.key, sizeof(base_crng.key)); | |
643 | blake2s_update(&hash, cp, len); | |
644 | blake2s_final(&hash, base_crng.key); | |
645 | ||
646 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
647 | } | |
648 | ||
649 | static void _get_random_bytes(void *buf, size_t nbytes) | |
e192be9d | 650 | { |
186873c5 | 651 | u32 chacha_state[CHACHA_STATE_WORDS]; |
3655adc7 JD |
652 | u8 tmp[CHACHA_BLOCK_SIZE]; |
653 | size_t len; | |
654 | ||
655 | if (!nbytes) | |
656 | return; | |
657 | ||
658 | len = min_t(size_t, 32, nbytes); | |
659 | crng_make_state(chacha_state, buf, len); | |
660 | nbytes -= len; | |
661 | buf += len; | |
662 | ||
663 | while (nbytes) { | |
664 | if (nbytes < CHACHA_BLOCK_SIZE) { | |
665 | chacha20_block(chacha_state, tmp); | |
666 | memcpy(buf, tmp, nbytes); | |
667 | memzero_explicit(tmp, sizeof(tmp)); | |
668 | break; | |
669 | } | |
670 | ||
671 | chacha20_block(chacha_state, buf); | |
672 | if (unlikely(chacha_state[12] == 0)) | |
673 | ++chacha_state[13]; | |
674 | nbytes -= CHACHA_BLOCK_SIZE; | |
675 | buf += CHACHA_BLOCK_SIZE; | |
676 | } | |
677 | ||
678 | memzero_explicit(chacha_state, sizeof(chacha_state)); | |
679 | } | |
680 | ||
681 | /* | |
682 | * This function is the exported kernel interface. It returns some | |
683 | * number of good random numbers, suitable for key generation, seeding | |
684 | * TCP sequence numbers, etc. It does not rely on the hardware random | |
685 | * number generator. For random bytes direct from the hardware RNG | |
686 | * (when available), use get_random_bytes_arch(). In order to ensure | |
687 | * that the randomness provided by this function is okay, the function | |
688 | * wait_for_random_bytes() should be called and return 0 at least once | |
689 | * at any point prior. | |
690 | */ | |
691 | void get_random_bytes(void *buf, size_t nbytes) | |
692 | { | |
693 | static void *previous; | |
694 | ||
695 | warn_unseeded_randomness(&previous); | |
696 | _get_random_bytes(buf, nbytes); | |
697 | } | |
698 | EXPORT_SYMBOL(get_random_bytes); | |
699 | ||
700 | static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes) | |
701 | { | |
702 | bool large_request = nbytes > 256; | |
703 | ssize_t ret = 0; | |
704 | size_t len; | |
705 | u32 chacha_state[CHACHA_STATE_WORDS]; | |
706 | u8 output[CHACHA_BLOCK_SIZE]; | |
707 | ||
708 | if (!nbytes) | |
709 | return 0; | |
710 | ||
711 | len = min_t(size_t, 32, nbytes); | |
712 | crng_make_state(chacha_state, output, len); | |
713 | ||
714 | if (copy_to_user(buf, output, len)) | |
715 | return -EFAULT; | |
716 | nbytes -= len; | |
717 | buf += len; | |
718 | ret += len; | |
719 | ||
720 | while (nbytes) { | |
721 | if (large_request && need_resched()) { | |
722 | if (signal_pending(current)) | |
723 | break; | |
724 | schedule(); | |
725 | } | |
726 | ||
727 | chacha20_block(chacha_state, output); | |
728 | if (unlikely(chacha_state[12] == 0)) | |
729 | ++chacha_state[13]; | |
730 | ||
731 | len = min_t(size_t, nbytes, CHACHA_BLOCK_SIZE); | |
732 | if (copy_to_user(buf, output, len)) { | |
733 | ret = -EFAULT; | |
734 | break; | |
735 | } | |
736 | ||
737 | nbytes -= len; | |
738 | buf += len; | |
739 | ret += len; | |
740 | } | |
741 | ||
742 | memzero_explicit(chacha_state, sizeof(chacha_state)); | |
743 | memzero_explicit(output, sizeof(output)); | |
744 | return ret; | |
745 | } | |
746 | ||
747 | /* | |
748 | * Batched entropy returns random integers. The quality of the random | |
749 | * number is good as /dev/urandom. In order to ensure that the randomness | |
750 | * provided by this function is okay, the function wait_for_random_bytes() | |
751 | * should be called and return 0 at least once at any point prior. | |
752 | */ | |
753 | struct batched_entropy { | |
754 | union { | |
755 | /* | |
756 | * We make this 1.5x a ChaCha block, so that we get the | |
757 | * remaining 32 bytes from fast key erasure, plus one full | |
758 | * block from the detached ChaCha state. We can increase | |
759 | * the size of this later if needed so long as we keep the | |
760 | * formula of (integer_blocks + 0.5) * CHACHA_BLOCK_SIZE. | |
761 | */ | |
762 | u64 entropy_u64[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u64))]; | |
763 | u32 entropy_u32[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u32))]; | |
764 | }; | |
765 | local_lock_t lock; | |
766 | unsigned long generation; | |
767 | unsigned int position; | |
768 | }; | |
769 | ||
770 | ||
771 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = { | |
772 | .lock = INIT_LOCAL_LOCK(batched_entropy_u64.lock), | |
773 | .position = UINT_MAX | |
774 | }; | |
775 | ||
776 | u64 get_random_u64(void) | |
777 | { | |
778 | u64 ret; | |
779 | unsigned long flags; | |
780 | struct batched_entropy *batch; | |
781 | static void *previous; | |
782 | unsigned long next_gen; | |
783 | ||
784 | warn_unseeded_randomness(&previous); | |
785 | ||
786 | local_lock_irqsave(&batched_entropy_u64.lock, flags); | |
787 | batch = raw_cpu_ptr(&batched_entropy_u64); | |
788 | ||
789 | next_gen = READ_ONCE(base_crng.generation); | |
790 | if (batch->position >= ARRAY_SIZE(batch->entropy_u64) || | |
791 | next_gen != batch->generation) { | |
792 | _get_random_bytes(batch->entropy_u64, sizeof(batch->entropy_u64)); | |
793 | batch->position = 0; | |
794 | batch->generation = next_gen; | |
795 | } | |
796 | ||
797 | ret = batch->entropy_u64[batch->position]; | |
798 | batch->entropy_u64[batch->position] = 0; | |
799 | ++batch->position; | |
800 | local_unlock_irqrestore(&batched_entropy_u64.lock, flags); | |
801 | return ret; | |
802 | } | |
803 | EXPORT_SYMBOL(get_random_u64); | |
804 | ||
805 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = { | |
806 | .lock = INIT_LOCAL_LOCK(batched_entropy_u32.lock), | |
807 | .position = UINT_MAX | |
808 | }; | |
809 | ||
810 | u32 get_random_u32(void) | |
811 | { | |
812 | u32 ret; | |
813 | unsigned long flags; | |
814 | struct batched_entropy *batch; | |
815 | static void *previous; | |
816 | unsigned long next_gen; | |
817 | ||
818 | warn_unseeded_randomness(&previous); | |
819 | ||
820 | local_lock_irqsave(&batched_entropy_u32.lock, flags); | |
821 | batch = raw_cpu_ptr(&batched_entropy_u32); | |
822 | ||
823 | next_gen = READ_ONCE(base_crng.generation); | |
824 | if (batch->position >= ARRAY_SIZE(batch->entropy_u32) || | |
825 | next_gen != batch->generation) { | |
826 | _get_random_bytes(batch->entropy_u32, sizeof(batch->entropy_u32)); | |
827 | batch->position = 0; | |
828 | batch->generation = next_gen; | |
829 | } | |
830 | ||
831 | ret = batch->entropy_u32[batch->position]; | |
832 | batch->entropy_u32[batch->position] = 0; | |
833 | ++batch->position; | |
834 | local_unlock_irqrestore(&batched_entropy_u32.lock, flags); | |
835 | return ret; | |
836 | } | |
837 | EXPORT_SYMBOL(get_random_u32); | |
838 | ||
839 | /** | |
840 | * randomize_page - Generate a random, page aligned address | |
841 | * @start: The smallest acceptable address the caller will take. | |
842 | * @range: The size of the area, starting at @start, within which the | |
843 | * random address must fall. | |
844 | * | |
845 | * If @start + @range would overflow, @range is capped. | |
846 | * | |
847 | * NOTE: Historical use of randomize_range, which this replaces, presumed that | |
848 | * @start was already page aligned. We now align it regardless. | |
849 | * | |
850 | * Return: A page aligned address within [start, start + range). On error, | |
851 | * @start is returned. | |
852 | */ | |
853 | unsigned long randomize_page(unsigned long start, unsigned long range) | |
854 | { | |
855 | if (!PAGE_ALIGNED(start)) { | |
856 | range -= PAGE_ALIGN(start) - start; | |
857 | start = PAGE_ALIGN(start); | |
858 | } | |
859 | ||
860 | if (start > ULONG_MAX - range) | |
861 | range = ULONG_MAX - start; | |
862 | ||
863 | range >>= PAGE_SHIFT; | |
864 | ||
865 | if (range == 0) | |
866 | return start; | |
867 | ||
868 | return start + (get_random_long() % range << PAGE_SHIFT); | |
869 | } | |
870 | ||
871 | /* | |
872 | * This function will use the architecture-specific hardware random | |
873 | * number generator if it is available. It is not recommended for | |
874 | * use. Use get_random_bytes() instead. It returns the number of | |
875 | * bytes filled in. | |
876 | */ | |
877 | size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes) | |
878 | { | |
879 | size_t left = nbytes; | |
880 | u8 *p = buf; | |
881 | ||
882 | while (left) { | |
883 | unsigned long v; | |
884 | size_t chunk = min_t(size_t, left, sizeof(unsigned long)); | |
885 | ||
886 | if (!arch_get_random_long(&v)) | |
887 | break; | |
888 | ||
889 | memcpy(p, &v, chunk); | |
890 | p += chunk; | |
891 | left -= chunk; | |
892 | } | |
893 | ||
894 | return nbytes - left; | |
895 | } | |
896 | EXPORT_SYMBOL(get_random_bytes_arch); | |
897 | ||
898 | enum { | |
899 | POOL_BITS = BLAKE2S_HASH_SIZE * 8, | |
900 | POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */ | |
901 | }; | |
902 | ||
903 | /* | |
904 | * Static global variables | |
905 | */ | |
906 | static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); | |
907 | ||
908 | /********************************************************************** | |
909 | * | |
910 | * OS independent entropy store. Here are the functions which handle | |
911 | * storing entropy in an entropy pool. | |
912 | * | |
913 | **********************************************************************/ | |
914 | ||
915 | static struct { | |
916 | struct blake2s_state hash; | |
917 | spinlock_t lock; | |
918 | unsigned int entropy_count; | |
919 | } input_pool = { | |
920 | .hash.h = { BLAKE2S_IV0 ^ (0x01010000 | BLAKE2S_HASH_SIZE), | |
921 | BLAKE2S_IV1, BLAKE2S_IV2, BLAKE2S_IV3, BLAKE2S_IV4, | |
922 | BLAKE2S_IV5, BLAKE2S_IV6, BLAKE2S_IV7 }, | |
923 | .hash.outlen = BLAKE2S_HASH_SIZE, | |
924 | .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock), | |
925 | }; | |
926 | ||
927 | static void extract_entropy(void *buf, size_t nbytes); | |
928 | static bool drain_entropy(void *buf, size_t nbytes); | |
929 | ||
930 | static void crng_reseed(void); | |
931 | ||
932 | /* | |
933 | * This function adds bytes into the entropy "pool". It does not | |
934 | * update the entropy estimate. The caller should call | |
935 | * credit_entropy_bits if this is appropriate. | |
936 | */ | |
937 | static void _mix_pool_bytes(const void *in, size_t nbytes) | |
938 | { | |
939 | blake2s_update(&input_pool.hash, in, nbytes); | |
940 | } | |
941 | ||
942 | static void mix_pool_bytes(const void *in, size_t nbytes) | |
943 | { | |
944 | unsigned long flags; | |
945 | ||
946 | spin_lock_irqsave(&input_pool.lock, flags); | |
947 | _mix_pool_bytes(in, nbytes); | |
948 | spin_unlock_irqrestore(&input_pool.lock, flags); | |
949 | } | |
950 | ||
951 | struct fast_pool { | |
952 | union { | |
953 | u32 pool32[4]; | |
954 | u64 pool64[2]; | |
955 | }; | |
956 | unsigned long last; | |
957 | u16 reg_idx; | |
958 | u8 count; | |
959 | }; | |
960 | ||
961 | /* | |
962 | * This is a fast mixing routine used by the interrupt randomness | |
963 | * collector. It's hardcoded for an 128 bit pool and assumes that any | |
964 | * locks that might be needed are taken by the caller. | |
965 | */ | |
966 | static void fast_mix(u32 pool[4]) | |
967 | { | |
968 | u32 a = pool[0], b = pool[1]; | |
969 | u32 c = pool[2], d = pool[3]; | |
970 | ||
971 | a += b; c += d; | |
972 | b = rol32(b, 6); d = rol32(d, 27); | |
973 | d ^= a; b ^= c; | |
186873c5 | 974 | |
3655adc7 JD |
975 | a += b; c += d; |
976 | b = rol32(b, 16); d = rol32(d, 14); | |
977 | d ^= a; b ^= c; | |
186873c5 | 978 | |
3655adc7 JD |
979 | a += b; c += d; |
980 | b = rol32(b, 6); d = rol32(d, 27); | |
981 | d ^= a; b ^= c; | |
186873c5 | 982 | |
3655adc7 JD |
983 | a += b; c += d; |
984 | b = rol32(b, 16); d = rol32(d, 14); | |
985 | d ^= a; b ^= c; | |
e192be9d | 986 | |
3655adc7 JD |
987 | pool[0] = a; pool[1] = b; |
988 | pool[2] = c; pool[3] = d; | |
989 | } | |
e192be9d | 990 | |
3655adc7 JD |
991 | static void credit_entropy_bits(size_t nbits) |
992 | { | |
993 | unsigned int entropy_count, orig, add; | |
186873c5 | 994 | |
3655adc7 JD |
995 | if (!nbits) |
996 | return; | |
e192be9d | 997 | |
3655adc7 | 998 | add = min_t(size_t, nbits, POOL_BITS); |
e192be9d | 999 | |
3655adc7 JD |
1000 | do { |
1001 | orig = READ_ONCE(input_pool.entropy_count); | |
1002 | entropy_count = min_t(unsigned int, POOL_BITS, orig + add); | |
1003 | } while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig); | |
1004 | ||
1005 | if (crng_init < 2 && entropy_count >= POOL_MIN_BITS) | |
1006 | crng_reseed(); | |
e192be9d TT |
1007 | } |
1008 | ||
1da177e4 LT |
1009 | /********************************************************************* |
1010 | * | |
1011 | * Entropy input management | |
1012 | * | |
1013 | *********************************************************************/ | |
1014 | ||
1015 | /* There is one of these per entropy source */ | |
1016 | struct timer_rand_state { | |
1017 | cycles_t last_time; | |
90b75ee5 | 1018 | long last_delta, last_delta2; |
1da177e4 LT |
1019 | }; |
1020 | ||
644008df TT |
1021 | #define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, }; |
1022 | ||
a2080a67 | 1023 | /* |
e192be9d TT |
1024 | * Add device- or boot-specific data to the input pool to help |
1025 | * initialize it. | |
a2080a67 | 1026 | * |
e192be9d TT |
1027 | * None of this adds any entropy; it is meant to avoid the problem of |
1028 | * the entropy pool having similar initial state across largely | |
1029 | * identical devices. | |
a2080a67 | 1030 | */ |
04ec96b7 | 1031 | void add_device_randomness(const void *buf, size_t size) |
a2080a67 | 1032 | { |
61875f30 | 1033 | unsigned long time = random_get_entropy() ^ jiffies; |
3ef4cb2d | 1034 | unsigned long flags; |
a2080a67 | 1035 | |
dc12baac TT |
1036 | if (!crng_ready() && size) |
1037 | crng_slow_load(buf, size); | |
ee7998c5 | 1038 | |
3ef4cb2d | 1039 | spin_lock_irqsave(&input_pool.lock, flags); |
90ed1e67 JD |
1040 | _mix_pool_bytes(buf, size); |
1041 | _mix_pool_bytes(&time, sizeof(time)); | |
3ef4cb2d | 1042 | spin_unlock_irqrestore(&input_pool.lock, flags); |
a2080a67 LT |
1043 | } |
1044 | EXPORT_SYMBOL(add_device_randomness); | |
1045 | ||
644008df | 1046 | static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE; |
3060d6fe | 1047 | |
1da177e4 LT |
1048 | /* |
1049 | * This function adds entropy to the entropy "pool" by using timing | |
1050 | * delays. It uses the timer_rand_state structure to make an estimate | |
1051 | * of how many bits of entropy this call has added to the pool. | |
1052 | * | |
1053 | * The number "num" is also added to the pool - it should somehow describe | |
1054 | * the type of event which just happened. This is currently 0-255 for | |
1055 | * keyboard scan codes, and 256 upwards for interrupts. | |
1056 | * | |
1057 | */ | |
04ec96b7 | 1058 | static void add_timer_randomness(struct timer_rand_state *state, unsigned int num) |
1da177e4 LT |
1059 | { |
1060 | struct { | |
1da177e4 | 1061 | long jiffies; |
d38bb085 JD |
1062 | unsigned int cycles; |
1063 | unsigned int num; | |
1da177e4 LT |
1064 | } sample; |
1065 | long delta, delta2, delta3; | |
1066 | ||
1da177e4 | 1067 | sample.jiffies = jiffies; |
61875f30 | 1068 | sample.cycles = random_get_entropy(); |
1da177e4 | 1069 | sample.num = num; |
90ed1e67 | 1070 | mix_pool_bytes(&sample, sizeof(sample)); |
1da177e4 LT |
1071 | |
1072 | /* | |
1073 | * Calculate number of bits of randomness we probably added. | |
1074 | * We take into account the first, second and third-order deltas | |
1075 | * in order to make our estimate. | |
1076 | */ | |
e00d996a QC |
1077 | delta = sample.jiffies - READ_ONCE(state->last_time); |
1078 | WRITE_ONCE(state->last_time, sample.jiffies); | |
5e747dd9 | 1079 | |
e00d996a QC |
1080 | delta2 = delta - READ_ONCE(state->last_delta); |
1081 | WRITE_ONCE(state->last_delta, delta); | |
5e747dd9 | 1082 | |
e00d996a QC |
1083 | delta3 = delta2 - READ_ONCE(state->last_delta2); |
1084 | WRITE_ONCE(state->last_delta2, delta2); | |
5e747dd9 RV |
1085 | |
1086 | if (delta < 0) | |
1087 | delta = -delta; | |
1088 | if (delta2 < 0) | |
1089 | delta2 = -delta2; | |
1090 | if (delta3 < 0) | |
1091 | delta3 = -delta3; | |
1092 | if (delta > delta2) | |
1093 | delta = delta2; | |
1094 | if (delta > delta3) | |
1095 | delta = delta3; | |
1da177e4 | 1096 | |
5e747dd9 RV |
1097 | /* |
1098 | * delta is now minimum absolute delta. | |
1099 | * Round down by 1 bit on general principles, | |
727d499a | 1100 | * and limit entropy estimate to 12 bits. |
5e747dd9 | 1101 | */ |
04ec96b7 | 1102 | credit_entropy_bits(min_t(unsigned int, fls(delta >> 1), 11)); |
1da177e4 LT |
1103 | } |
1104 | ||
d251575a | 1105 | void add_input_randomness(unsigned int type, unsigned int code, |
248045b8 | 1106 | unsigned int value) |
1da177e4 LT |
1107 | { |
1108 | static unsigned char last_value; | |
1109 | ||
1110 | /* ignore autorepeat and the like */ | |
1111 | if (value == last_value) | |
1112 | return; | |
1113 | ||
1da177e4 LT |
1114 | last_value = value; |
1115 | add_timer_randomness(&input_timer_state, | |
1116 | (type << 4) ^ code ^ (code >> 4) ^ value); | |
1117 | } | |
80fc9f53 | 1118 | EXPORT_SYMBOL_GPL(add_input_randomness); |
1da177e4 | 1119 | |
775f4b29 TT |
1120 | static DEFINE_PER_CPU(struct fast_pool, irq_randomness); |
1121 | ||
d38bb085 | 1122 | static u32 get_reg(struct fast_pool *f, struct pt_regs *regs) |
ee3e00e9 | 1123 | { |
248045b8 | 1124 | u32 *ptr = (u32 *)regs; |
92e75428 | 1125 | unsigned int idx; |
ee3e00e9 TT |
1126 | |
1127 | if (regs == NULL) | |
1128 | return 0; | |
92e75428 | 1129 | idx = READ_ONCE(f->reg_idx); |
d38bb085 | 1130 | if (idx >= sizeof(struct pt_regs) / sizeof(u32)) |
92e75428 TT |
1131 | idx = 0; |
1132 | ptr += idx++; | |
1133 | WRITE_ONCE(f->reg_idx, idx); | |
9dfa7bba | 1134 | return *ptr; |
ee3e00e9 TT |
1135 | } |
1136 | ||
703f7066 | 1137 | void add_interrupt_randomness(int irq) |
1da177e4 | 1138 | { |
248045b8 JD |
1139 | struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness); |
1140 | struct pt_regs *regs = get_irq_regs(); | |
1141 | unsigned long now = jiffies; | |
1142 | cycles_t cycles = random_get_entropy(); | |
3060d6fe | 1143 | |
ee3e00e9 TT |
1144 | if (cycles == 0) |
1145 | cycles = get_reg(fast_pool, regs); | |
3060d6fe | 1146 | |
b2f408fe JD |
1147 | if (sizeof(cycles) == 8) |
1148 | fast_pool->pool64[0] ^= cycles ^ rol64(now, 32) ^ irq; | |
1149 | else { | |
1150 | fast_pool->pool32[0] ^= cycles ^ irq; | |
1151 | fast_pool->pool32[1] ^= now; | |
1152 | } | |
1153 | ||
1154 | if (sizeof(unsigned long) == 8) | |
1155 | fast_pool->pool64[1] ^= regs ? instruction_pointer(regs) : _RET_IP_; | |
1156 | else { | |
1157 | fast_pool->pool32[2] ^= regs ? instruction_pointer(regs) : _RET_IP_; | |
1158 | fast_pool->pool32[3] ^= get_reg(fast_pool, regs); | |
1159 | } | |
1160 | ||
1161 | fast_mix(fast_pool->pool32); | |
1162 | ++fast_pool->count; | |
3060d6fe | 1163 | |
43838a23 | 1164 | if (unlikely(crng_init == 0)) { |
04ec96b7 | 1165 | if (fast_pool->count >= 64 && |
b2f408fe | 1166 | crng_fast_load(fast_pool->pool32, sizeof(fast_pool->pool32)) > 0) { |
e192be9d TT |
1167 | fast_pool->count = 0; |
1168 | fast_pool->last = now; | |
c30c575d | 1169 | if (spin_trylock(&input_pool.lock)) { |
b2f408fe | 1170 | _mix_pool_bytes(&fast_pool->pool32, sizeof(fast_pool->pool32)); |
c30c575d JD |
1171 | spin_unlock(&input_pool.lock); |
1172 | } | |
e192be9d TT |
1173 | } |
1174 | return; | |
1175 | } | |
1176 | ||
248045b8 | 1177 | if ((fast_pool->count < 64) && !time_after(now, fast_pool->last + HZ)) |
1da177e4 LT |
1178 | return; |
1179 | ||
90ed1e67 | 1180 | if (!spin_trylock(&input_pool.lock)) |
91fcb532 | 1181 | return; |
83664a69 | 1182 | |
91fcb532 | 1183 | fast_pool->last = now; |
b2f408fe | 1184 | _mix_pool_bytes(&fast_pool->pool32, sizeof(fast_pool->pool32)); |
90ed1e67 | 1185 | spin_unlock(&input_pool.lock); |
83664a69 | 1186 | |
ee3e00e9 | 1187 | fast_pool->count = 0; |
83664a69 | 1188 | |
ee3e00e9 | 1189 | /* award one bit for the contents of the fast pool */ |
90ed1e67 | 1190 | credit_entropy_bits(1); |
1da177e4 | 1191 | } |
4b44f2d1 | 1192 | EXPORT_SYMBOL_GPL(add_interrupt_randomness); |
1da177e4 | 1193 | |
9361401e | 1194 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1195 | void add_disk_randomness(struct gendisk *disk) |
1196 | { | |
1197 | if (!disk || !disk->random) | |
1198 | return; | |
1199 | /* first major is 1, so we get >= 0x200 here */ | |
f331c029 | 1200 | add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); |
1da177e4 | 1201 | } |
bdcfa3e5 | 1202 | EXPORT_SYMBOL_GPL(add_disk_randomness); |
9361401e | 1203 | #endif |
1da177e4 | 1204 | |
1da177e4 LT |
1205 | /********************************************************************* |
1206 | * | |
1207 | * Entropy extraction routines | |
1208 | * | |
1209 | *********************************************************************/ | |
1210 | ||
19fa5be1 | 1211 | /* |
6e8ec255 JD |
1212 | * This is an HKDF-like construction for using the hashed collected entropy |
1213 | * as a PRF key, that's then expanded block-by-block. | |
19fa5be1 | 1214 | */ |
9c07f578 | 1215 | static void extract_entropy(void *buf, size_t nbytes) |
1da177e4 | 1216 | { |
902c098a | 1217 | unsigned long flags; |
6e8ec255 JD |
1218 | u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE]; |
1219 | struct { | |
28f425e5 | 1220 | unsigned long rdseed[32 / sizeof(long)]; |
6e8ec255 JD |
1221 | size_t counter; |
1222 | } block; | |
1223 | size_t i; | |
1224 | ||
28f425e5 JD |
1225 | for (i = 0; i < ARRAY_SIZE(block.rdseed); ++i) { |
1226 | if (!arch_get_random_seed_long(&block.rdseed[i]) && | |
1227 | !arch_get_random_long(&block.rdseed[i])) | |
1228 | block.rdseed[i] = random_get_entropy(); | |
85a1f777 TT |
1229 | } |
1230 | ||
90ed1e67 | 1231 | spin_lock_irqsave(&input_pool.lock, flags); |
46884442 | 1232 | |
6e8ec255 JD |
1233 | /* seed = HASHPRF(last_key, entropy_input) */ |
1234 | blake2s_final(&input_pool.hash, seed); | |
1da177e4 | 1235 | |
28f425e5 | 1236 | /* next_key = HASHPRF(seed, RDSEED || 0) */ |
6e8ec255 JD |
1237 | block.counter = 0; |
1238 | blake2s(next_key, (u8 *)&block, seed, sizeof(next_key), sizeof(block), sizeof(seed)); | |
1239 | blake2s_init_key(&input_pool.hash, BLAKE2S_HASH_SIZE, next_key, sizeof(next_key)); | |
1da177e4 | 1240 | |
6e8ec255 JD |
1241 | spin_unlock_irqrestore(&input_pool.lock, flags); |
1242 | memzero_explicit(next_key, sizeof(next_key)); | |
e192be9d TT |
1243 | |
1244 | while (nbytes) { | |
6e8ec255 | 1245 | i = min_t(size_t, nbytes, BLAKE2S_HASH_SIZE); |
28f425e5 | 1246 | /* output = HASHPRF(seed, RDSEED || ++counter) */ |
6e8ec255 JD |
1247 | ++block.counter; |
1248 | blake2s(buf, (u8 *)&block, seed, i, sizeof(block), sizeof(seed)); | |
e192be9d TT |
1249 | nbytes -= i; |
1250 | buf += i; | |
e192be9d TT |
1251 | } |
1252 | ||
6e8ec255 JD |
1253 | memzero_explicit(seed, sizeof(seed)); |
1254 | memzero_explicit(&block, sizeof(block)); | |
e192be9d TT |
1255 | } |
1256 | ||
246c03dd JD |
1257 | /* |
1258 | * First we make sure we have POOL_MIN_BITS of entropy in the pool, and then we | |
1259 | * set the entropy count to zero (but don't actually touch any data). Only then | |
1260 | * can we extract a new key with extract_entropy(). | |
1261 | */ | |
1262 | static bool drain_entropy(void *buf, size_t nbytes) | |
1263 | { | |
1264 | unsigned int entropy_count; | |
1265 | do { | |
1266 | entropy_count = READ_ONCE(input_pool.entropy_count); | |
1267 | if (entropy_count < POOL_MIN_BITS) | |
1268 | return false; | |
1269 | } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count); | |
1270 | extract_entropy(buf, nbytes); | |
1271 | wake_up_interruptible(&random_write_wait); | |
1272 | kill_fasync(&fasync, SIGIO, POLL_OUT); | |
1273 | return true; | |
1274 | } | |
1275 | ||
50ee7529 LT |
1276 | /* |
1277 | * Each time the timer fires, we expect that we got an unpredictable | |
1278 | * jump in the cycle counter. Even if the timer is running on another | |
1279 | * CPU, the timer activity will be touching the stack of the CPU that is | |
1280 | * generating entropy.. | |
1281 | * | |
1282 | * Note that we don't re-arm the timer in the timer itself - we are | |
1283 | * happy to be scheduled away, since that just makes the load more | |
1284 | * complex, but we do not want the timer to keep ticking unless the | |
1285 | * entropy loop is running. | |
1286 | * | |
1287 | * So the re-arming always happens in the entropy loop itself. | |
1288 | */ | |
1289 | static void entropy_timer(struct timer_list *t) | |
1290 | { | |
90ed1e67 | 1291 | credit_entropy_bits(1); |
50ee7529 LT |
1292 | } |
1293 | ||
1294 | /* | |
1295 | * If we have an actual cycle counter, see if we can | |
1296 | * generate enough entropy with timing noise | |
1297 | */ | |
1298 | static void try_to_generate_entropy(void) | |
1299 | { | |
1300 | struct { | |
1301 | unsigned long now; | |
1302 | struct timer_list timer; | |
1303 | } stack; | |
1304 | ||
1305 | stack.now = random_get_entropy(); | |
1306 | ||
1307 | /* Slow counter - or none. Don't even bother */ | |
1308 | if (stack.now == random_get_entropy()) | |
1309 | return; | |
1310 | ||
1311 | timer_setup_on_stack(&stack.timer, entropy_timer, 0); | |
1312 | while (!crng_ready()) { | |
1313 | if (!timer_pending(&stack.timer)) | |
248045b8 | 1314 | mod_timer(&stack.timer, jiffies + 1); |
90ed1e67 | 1315 | mix_pool_bytes(&stack.now, sizeof(stack.now)); |
50ee7529 LT |
1316 | schedule(); |
1317 | stack.now = random_get_entropy(); | |
1318 | } | |
1319 | ||
1320 | del_timer_sync(&stack.timer); | |
1321 | destroy_timer_on_stack(&stack.timer); | |
90ed1e67 | 1322 | mix_pool_bytes(&stack.now, sizeof(stack.now)); |
50ee7529 LT |
1323 | } |
1324 | ||
85664172 JD |
1325 | static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU); |
1326 | static int __init parse_trust_cpu(char *arg) | |
1327 | { | |
1328 | return kstrtobool(arg, &trust_cpu); | |
1329 | } | |
1330 | early_param("random.trust_cpu", parse_trust_cpu); | |
1331 | ||
1da177e4 | 1332 | /* |
85664172 JD |
1333 | * Note that setup_arch() may call add_device_randomness() |
1334 | * long before we get here. This allows seeding of the pools | |
1335 | * with some platform dependent data very early in the boot | |
1336 | * process. But it limits our options here. We must use | |
1337 | * statically allocated structures that already have all | |
1338 | * initializations complete at compile time. We should also | |
1339 | * take care not to overwrite the precious per platform data | |
1340 | * we were given. | |
1da177e4 | 1341 | */ |
85664172 | 1342 | int __init rand_initialize(void) |
1da177e4 | 1343 | { |
04ec96b7 | 1344 | size_t i; |
902c098a | 1345 | ktime_t now = ktime_get_real(); |
85664172 | 1346 | bool arch_init = true; |
902c098a | 1347 | unsigned long rv; |
1da177e4 | 1348 | |
04ec96b7 | 1349 | for (i = 0; i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) { |
85664172 JD |
1350 | if (!arch_get_random_seed_long_early(&rv) && |
1351 | !arch_get_random_long_early(&rv)) { | |
1352 | rv = random_get_entropy(); | |
1353 | arch_init = false; | |
1354 | } | |
a02cf3d0 | 1355 | mix_pool_bytes(&rv, sizeof(rv)); |
85664172 | 1356 | } |
a02cf3d0 JD |
1357 | mix_pool_bytes(&now, sizeof(now)); |
1358 | mix_pool_bytes(utsname(), sizeof(*(utsname()))); | |
1359 | ||
186873c5 | 1360 | extract_entropy(base_crng.key, sizeof(base_crng.key)); |
0791e8b6 JD |
1361 | ++base_crng.generation; |
1362 | ||
85664172 | 1363 | if (arch_init && trust_cpu && crng_init < 2) { |
85664172 JD |
1364 | crng_init = 2; |
1365 | pr_notice("crng init done (trusting CPU's manufacturer)\n"); | |
1366 | } | |
85664172 | 1367 | |
4e00b339 TT |
1368 | if (ratelimit_disable) { |
1369 | urandom_warning.interval = 0; | |
1370 | unseeded_warning.interval = 0; | |
1371 | } | |
1da177e4 LT |
1372 | return 0; |
1373 | } | |
1da177e4 | 1374 | |
9361401e | 1375 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1376 | void rand_initialize_disk(struct gendisk *disk) |
1377 | { | |
1378 | struct timer_rand_state *state; | |
1379 | ||
1380 | /* | |
f8595815 | 1381 | * If kzalloc returns null, we just won't use that entropy |
1da177e4 LT |
1382 | * source. |
1383 | */ | |
f8595815 | 1384 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
644008df TT |
1385 | if (state) { |
1386 | state->last_time = INITIAL_JIFFIES; | |
1da177e4 | 1387 | disk->random = state; |
644008df | 1388 | } |
1da177e4 | 1389 | } |
9361401e | 1390 | #endif |
1da177e4 | 1391 | |
248045b8 JD |
1392 | static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes, |
1393 | loff_t *ppos) | |
1da177e4 | 1394 | { |
9b4d0087 | 1395 | static int maxwarn = 10; |
301f0595 | 1396 | |
e192be9d | 1397 | if (!crng_ready() && maxwarn > 0) { |
9b4d0087 | 1398 | maxwarn--; |
4e00b339 | 1399 | if (__ratelimit(&urandom_warning)) |
12cd53af YL |
1400 | pr_notice("%s: uninitialized urandom read (%zd bytes read)\n", |
1401 | current->comm, nbytes); | |
9b4d0087 | 1402 | } |
c6f1deb1 | 1403 | |
14c17463 | 1404 | return get_random_bytes_user(buf, nbytes); |
1da177e4 LT |
1405 | } |
1406 | ||
248045b8 JD |
1407 | static ssize_t random_read(struct file *file, char __user *buf, size_t nbytes, |
1408 | loff_t *ppos) | |
30c08efe AL |
1409 | { |
1410 | int ret; | |
1411 | ||
1412 | ret = wait_for_random_bytes(); | |
1413 | if (ret != 0) | |
1414 | return ret; | |
14c17463 | 1415 | return get_random_bytes_user(buf, nbytes); |
30c08efe AL |
1416 | } |
1417 | ||
248045b8 | 1418 | static __poll_t random_poll(struct file *file, poll_table *wait) |
1da177e4 | 1419 | { |
a11e1d43 | 1420 | __poll_t mask; |
1da177e4 | 1421 | |
30c08efe | 1422 | poll_wait(file, &crng_init_wait, wait); |
a11e1d43 LT |
1423 | poll_wait(file, &random_write_wait, wait); |
1424 | mask = 0; | |
30c08efe | 1425 | if (crng_ready()) |
a9a08845 | 1426 | mask |= EPOLLIN | EPOLLRDNORM; |
489c7fc4 | 1427 | if (input_pool.entropy_count < POOL_MIN_BITS) |
a9a08845 | 1428 | mask |= EPOLLOUT | EPOLLWRNORM; |
1da177e4 LT |
1429 | return mask; |
1430 | } | |
1431 | ||
04ec96b7 | 1432 | static int write_pool(const char __user *ubuf, size_t count) |
1da177e4 | 1433 | { |
04ec96b7 | 1434 | size_t len; |
7b5164fb | 1435 | int ret = 0; |
04ec96b7 | 1436 | u8 block[BLAKE2S_BLOCK_SIZE]; |
1da177e4 | 1437 | |
04ec96b7 JD |
1438 | while (count) { |
1439 | len = min(count, sizeof(block)); | |
7b5164fb JD |
1440 | if (copy_from_user(block, ubuf, len)) { |
1441 | ret = -EFAULT; | |
1442 | goto out; | |
1443 | } | |
04ec96b7 JD |
1444 | count -= len; |
1445 | ubuf += len; | |
1446 | mix_pool_bytes(block, len); | |
91f3f1e3 | 1447 | cond_resched(); |
1da177e4 | 1448 | } |
7f397dcd | 1449 | |
7b5164fb JD |
1450 | out: |
1451 | memzero_explicit(block, sizeof(block)); | |
1452 | return ret; | |
7f397dcd MM |
1453 | } |
1454 | ||
90b75ee5 MM |
1455 | static ssize_t random_write(struct file *file, const char __user *buffer, |
1456 | size_t count, loff_t *ppos) | |
7f397dcd | 1457 | { |
04ec96b7 | 1458 | int ret; |
7f397dcd | 1459 | |
90ed1e67 | 1460 | ret = write_pool(buffer, count); |
7f397dcd MM |
1461 | if (ret) |
1462 | return ret; | |
1463 | ||
7f397dcd | 1464 | return (ssize_t)count; |
1da177e4 LT |
1465 | } |
1466 | ||
43ae4860 | 1467 | static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) |
1da177e4 LT |
1468 | { |
1469 | int size, ent_count; | |
1470 | int __user *p = (int __user *)arg; | |
1471 | int retval; | |
1472 | ||
1473 | switch (cmd) { | |
1474 | case RNDGETENTCNT: | |
43ae4860 | 1475 | /* inherently racy, no point locking */ |
c5704490 | 1476 | if (put_user(input_pool.entropy_count, p)) |
1da177e4 LT |
1477 | return -EFAULT; |
1478 | return 0; | |
1479 | case RNDADDTOENTCNT: | |
1480 | if (!capable(CAP_SYS_ADMIN)) | |
1481 | return -EPERM; | |
1482 | if (get_user(ent_count, p)) | |
1483 | return -EFAULT; | |
a49c010e JD |
1484 | if (ent_count < 0) |
1485 | return -EINVAL; | |
1486 | credit_entropy_bits(ent_count); | |
1487 | return 0; | |
1da177e4 LT |
1488 | case RNDADDENTROPY: |
1489 | if (!capable(CAP_SYS_ADMIN)) | |
1490 | return -EPERM; | |
1491 | if (get_user(ent_count, p++)) | |
1492 | return -EFAULT; | |
1493 | if (ent_count < 0) | |
1494 | return -EINVAL; | |
1495 | if (get_user(size, p++)) | |
1496 | return -EFAULT; | |
90ed1e67 | 1497 | retval = write_pool((const char __user *)p, size); |
1da177e4 LT |
1498 | if (retval < 0) |
1499 | return retval; | |
a49c010e JD |
1500 | credit_entropy_bits(ent_count); |
1501 | return 0; | |
1da177e4 LT |
1502 | case RNDZAPENTCNT: |
1503 | case RNDCLEARPOOL: | |
ae9ecd92 TT |
1504 | /* |
1505 | * Clear the entropy pool counters. We no longer clear | |
1506 | * the entropy pool, as that's silly. | |
1507 | */ | |
1da177e4 LT |
1508 | if (!capable(CAP_SYS_ADMIN)) |
1509 | return -EPERM; | |
489c7fc4 | 1510 | if (xchg(&input_pool.entropy_count, 0)) { |
042e293e JD |
1511 | wake_up_interruptible(&random_write_wait); |
1512 | kill_fasync(&fasync, SIGIO, POLL_OUT); | |
1513 | } | |
1da177e4 | 1514 | return 0; |
d848e5f8 TT |
1515 | case RNDRESEEDCRNG: |
1516 | if (!capable(CAP_SYS_ADMIN)) | |
1517 | return -EPERM; | |
1518 | if (crng_init < 2) | |
1519 | return -ENODATA; | |
a9412d51 | 1520 | crng_reseed(); |
d848e5f8 | 1521 | return 0; |
1da177e4 LT |
1522 | default: |
1523 | return -EINVAL; | |
1524 | } | |
1525 | } | |
1526 | ||
9a6f70bb JD |
1527 | static int random_fasync(int fd, struct file *filp, int on) |
1528 | { | |
1529 | return fasync_helper(fd, filp, on, &fasync); | |
1530 | } | |
1531 | ||
2b8693c0 | 1532 | const struct file_operations random_fops = { |
248045b8 | 1533 | .read = random_read, |
1da177e4 | 1534 | .write = random_write, |
248045b8 | 1535 | .poll = random_poll, |
43ae4860 | 1536 | .unlocked_ioctl = random_ioctl, |
507e4e2b | 1537 | .compat_ioctl = compat_ptr_ioctl, |
9a6f70bb | 1538 | .fasync = random_fasync, |
6038f373 | 1539 | .llseek = noop_llseek, |
1da177e4 LT |
1540 | }; |
1541 | ||
2b8693c0 | 1542 | const struct file_operations urandom_fops = { |
248045b8 | 1543 | .read = urandom_read, |
1da177e4 | 1544 | .write = random_write, |
43ae4860 | 1545 | .unlocked_ioctl = random_ioctl, |
4aa37c46 | 1546 | .compat_ioctl = compat_ptr_ioctl, |
9a6f70bb | 1547 | .fasync = random_fasync, |
6038f373 | 1548 | .llseek = noop_llseek, |
1da177e4 LT |
1549 | }; |
1550 | ||
248045b8 JD |
1551 | SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int, |
1552 | flags) | |
c6e9d6f3 | 1553 | { |
248045b8 | 1554 | if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE)) |
75551dbf AL |
1555 | return -EINVAL; |
1556 | ||
1557 | /* | |
1558 | * Requesting insecure and blocking randomness at the same time makes | |
1559 | * no sense. | |
1560 | */ | |
248045b8 | 1561 | if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM)) |
c6e9d6f3 TT |
1562 | return -EINVAL; |
1563 | ||
1564 | if (count > INT_MAX) | |
1565 | count = INT_MAX; | |
1566 | ||
75551dbf | 1567 | if (!(flags & GRND_INSECURE) && !crng_ready()) { |
04ec96b7 JD |
1568 | int ret; |
1569 | ||
c6e9d6f3 TT |
1570 | if (flags & GRND_NONBLOCK) |
1571 | return -EAGAIN; | |
e297a783 JD |
1572 | ret = wait_for_random_bytes(); |
1573 | if (unlikely(ret)) | |
1574 | return ret; | |
c6e9d6f3 | 1575 | } |
14c17463 | 1576 | return get_random_bytes_user(buf, count); |
c6e9d6f3 TT |
1577 | } |
1578 | ||
1da177e4 LT |
1579 | /******************************************************************** |
1580 | * | |
1581 | * Sysctl interface | |
1582 | * | |
1583 | ********************************************************************/ | |
1584 | ||
1585 | #ifdef CONFIG_SYSCTL | |
1586 | ||
1587 | #include <linux/sysctl.h> | |
1588 | ||
db61ffe3 | 1589 | static int random_min_urandom_seed = 60; |
489c7fc4 JD |
1590 | static int random_write_wakeup_bits = POOL_MIN_BITS; |
1591 | static int sysctl_poolsize = POOL_BITS; | |
1da177e4 LT |
1592 | static char sysctl_bootid[16]; |
1593 | ||
1594 | /* | |
f22052b2 | 1595 | * This function is used to return both the bootid UUID, and random |
1da177e4 LT |
1596 | * UUID. The difference is in whether table->data is NULL; if it is, |
1597 | * then a new UUID is generated and returned to the user. | |
1598 | * | |
f22052b2 GP |
1599 | * If the user accesses this via the proc interface, the UUID will be |
1600 | * returned as an ASCII string in the standard UUID format; if via the | |
1601 | * sysctl system call, as 16 bytes of binary data. | |
1da177e4 | 1602 | */ |
248045b8 JD |
1603 | static int proc_do_uuid(struct ctl_table *table, int write, void *buffer, |
1604 | size_t *lenp, loff_t *ppos) | |
1da177e4 | 1605 | { |
a151427e | 1606 | struct ctl_table fake_table; |
1da177e4 LT |
1607 | unsigned char buf[64], tmp_uuid[16], *uuid; |
1608 | ||
1609 | uuid = table->data; | |
1610 | if (!uuid) { | |
1611 | uuid = tmp_uuid; | |
1da177e4 | 1612 | generate_random_uuid(uuid); |
44e4360f MD |
1613 | } else { |
1614 | static DEFINE_SPINLOCK(bootid_spinlock); | |
1615 | ||
1616 | spin_lock(&bootid_spinlock); | |
1617 | if (!uuid[8]) | |
1618 | generate_random_uuid(uuid); | |
1619 | spin_unlock(&bootid_spinlock); | |
1620 | } | |
1da177e4 | 1621 | |
35900771 JP |
1622 | sprintf(buf, "%pU", uuid); |
1623 | ||
1da177e4 LT |
1624 | fake_table.data = buf; |
1625 | fake_table.maxlen = sizeof(buf); | |
1626 | ||
8d65af78 | 1627 | return proc_dostring(&fake_table, write, buffer, lenp, ppos); |
1da177e4 LT |
1628 | } |
1629 | ||
5475e8f0 | 1630 | static struct ctl_table random_table[] = { |
1da177e4 | 1631 | { |
1da177e4 LT |
1632 | .procname = "poolsize", |
1633 | .data = &sysctl_poolsize, | |
1634 | .maxlen = sizeof(int), | |
1635 | .mode = 0444, | |
6d456111 | 1636 | .proc_handler = proc_dointvec, |
1da177e4 LT |
1637 | }, |
1638 | { | |
1da177e4 | 1639 | .procname = "entropy_avail", |
c5704490 | 1640 | .data = &input_pool.entropy_count, |
1da177e4 LT |
1641 | .maxlen = sizeof(int), |
1642 | .mode = 0444, | |
c5704490 | 1643 | .proc_handler = proc_dointvec, |
1da177e4 | 1644 | }, |
1da177e4 | 1645 | { |
1da177e4 | 1646 | .procname = "write_wakeup_threshold", |
2132a96f | 1647 | .data = &random_write_wakeup_bits, |
1da177e4 LT |
1648 | .maxlen = sizeof(int), |
1649 | .mode = 0644, | |
489c7fc4 | 1650 | .proc_handler = proc_dointvec, |
1da177e4 | 1651 | }, |
f5c2742c TT |
1652 | { |
1653 | .procname = "urandom_min_reseed_secs", | |
1654 | .data = &random_min_urandom_seed, | |
1655 | .maxlen = sizeof(int), | |
1656 | .mode = 0644, | |
1657 | .proc_handler = proc_dointvec, | |
1658 | }, | |
1da177e4 | 1659 | { |
1da177e4 LT |
1660 | .procname = "boot_id", |
1661 | .data = &sysctl_bootid, | |
1662 | .maxlen = 16, | |
1663 | .mode = 0444, | |
6d456111 | 1664 | .proc_handler = proc_do_uuid, |
1da177e4 LT |
1665 | }, |
1666 | { | |
1da177e4 LT |
1667 | .procname = "uuid", |
1668 | .maxlen = 16, | |
1669 | .mode = 0444, | |
6d456111 | 1670 | .proc_handler = proc_do_uuid, |
1da177e4 | 1671 | }, |
894d2491 | 1672 | { } |
1da177e4 | 1673 | }; |
5475e8f0 XN |
1674 | |
1675 | /* | |
1676 | * rand_initialize() is called before sysctl_init(), | |
1677 | * so we cannot call register_sysctl_init() in rand_initialize() | |
1678 | */ | |
1679 | static int __init random_sysctls_init(void) | |
1680 | { | |
1681 | register_sysctl_init("kernel/random", random_table); | |
1682 | return 0; | |
1683 | } | |
1684 | device_initcall(random_sysctls_init); | |
248045b8 | 1685 | #endif /* CONFIG_SYSCTL */ |
1da177e4 | 1686 | |
c84dbf61 TD |
1687 | /* Interface for in-kernel drivers of true hardware RNGs. |
1688 | * Those devices may produce endless random bits and will be throttled | |
1689 | * when our pool is full. | |
1690 | */ | |
04ec96b7 | 1691 | void add_hwgenerator_randomness(const void *buffer, size_t count, |
c84dbf61 TD |
1692 | size_t entropy) |
1693 | { | |
43838a23 | 1694 | if (unlikely(crng_init == 0)) { |
73c7733f | 1695 | size_t ret = crng_fast_load(buffer, count); |
90ed1e67 | 1696 | mix_pool_bytes(buffer, ret); |
73c7733f JD |
1697 | count -= ret; |
1698 | buffer += ret; | |
1699 | if (!count || crng_init == 0) | |
1700 | return; | |
3371f3da | 1701 | } |
e192be9d | 1702 | |
c321e907 | 1703 | /* Throttle writing if we're above the trickle threshold. |
489c7fc4 JD |
1704 | * We'll be woken up again once below POOL_MIN_BITS, when |
1705 | * the calling thread is about to terminate, or once | |
1706 | * CRNG_RESEED_INTERVAL has elapsed. | |
e192be9d | 1707 | */ |
c321e907 | 1708 | wait_event_interruptible_timeout(random_write_wait, |
f7e67b8e | 1709 | !system_wq || kthread_should_stop() || |
489c7fc4 | 1710 | input_pool.entropy_count < POOL_MIN_BITS, |
c321e907 | 1711 | CRNG_RESEED_INTERVAL); |
90ed1e67 JD |
1712 | mix_pool_bytes(buffer, count); |
1713 | credit_entropy_bits(entropy); | |
c84dbf61 TD |
1714 | } |
1715 | EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); | |
428826f5 HYW |
1716 | |
1717 | /* Handle random seed passed by bootloader. | |
1718 | * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise | |
1719 | * it would be regarded as device data. | |
1720 | * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER. | |
1721 | */ | |
04ec96b7 | 1722 | void add_bootloader_randomness(const void *buf, size_t size) |
428826f5 HYW |
1723 | { |
1724 | if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER)) | |
1725 | add_hwgenerator_randomness(buf, size, size * 8); | |
1726 | else | |
1727 | add_device_randomness(buf, size); | |
1728 | } | |
3fd57e7a | 1729 | EXPORT_SYMBOL_GPL(add_bootloader_randomness); |