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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 | ||
383 | enum { | |
384 | POOL_BITS = BLAKE2S_HASH_SIZE * 8, | |
385 | POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */ | |
386 | }; | |
387 | ||
388 | /* | |
389 | * Static global variables | |
390 | */ | |
391 | static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); | |
392 | ||
393 | static int crng_init_cnt = 0; | |
394 | ||
1da177e4 LT |
395 | /********************************************************************** |
396 | * | |
397 | * OS independent entropy store. Here are the functions which handle | |
398 | * storing entropy in an entropy pool. | |
399 | * | |
400 | **********************************************************************/ | |
401 | ||
90ed1e67 | 402 | static struct { |
6e8ec255 | 403 | struct blake2s_state hash; |
43358209 | 404 | spinlock_t lock; |
04ec96b7 | 405 | unsigned int entropy_count; |
90ed1e67 | 406 | } input_pool = { |
6e8ec255 JD |
407 | .hash.h = { BLAKE2S_IV0 ^ (0x01010000 | BLAKE2S_HASH_SIZE), |
408 | BLAKE2S_IV1, BLAKE2S_IV2, BLAKE2S_IV3, BLAKE2S_IV4, | |
409 | BLAKE2S_IV5, BLAKE2S_IV6, BLAKE2S_IV7 }, | |
410 | .hash.outlen = BLAKE2S_HASH_SIZE, | |
eece09ec | 411 | .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock), |
1da177e4 LT |
412 | }; |
413 | ||
9c07f578 | 414 | static void extract_entropy(void *buf, size_t nbytes); |
246c03dd | 415 | static bool drain_entropy(void *buf, size_t nbytes); |
90ed1e67 | 416 | |
a9412d51 | 417 | static void crng_reseed(void); |
90ed1e67 | 418 | |
1da177e4 | 419 | /* |
e68e5b66 | 420 | * This function adds bytes into the entropy "pool". It does not |
1da177e4 | 421 | * update the entropy estimate. The caller should call |
adc782da | 422 | * credit_entropy_bits if this is appropriate. |
1da177e4 | 423 | */ |
04ec96b7 | 424 | static void _mix_pool_bytes(const void *in, size_t nbytes) |
1da177e4 | 425 | { |
6e8ec255 | 426 | blake2s_update(&input_pool.hash, in, nbytes); |
1da177e4 LT |
427 | } |
428 | ||
04ec96b7 | 429 | static void mix_pool_bytes(const void *in, size_t nbytes) |
1da177e4 | 430 | { |
902c098a TT |
431 | unsigned long flags; |
432 | ||
90ed1e67 JD |
433 | spin_lock_irqsave(&input_pool.lock, flags); |
434 | _mix_pool_bytes(in, nbytes); | |
435 | spin_unlock_irqrestore(&input_pool.lock, flags); | |
1da177e4 LT |
436 | } |
437 | ||
775f4b29 | 438 | struct fast_pool { |
b2f408fe JD |
439 | union { |
440 | u32 pool32[4]; | |
441 | u64 pool64[2]; | |
442 | }; | |
248045b8 JD |
443 | unsigned long last; |
444 | u16 reg_idx; | |
445 | u8 count; | |
775f4b29 TT |
446 | }; |
447 | ||
448 | /* | |
449 | * This is a fast mixing routine used by the interrupt randomness | |
450 | * collector. It's hardcoded for an 128 bit pool and assumes that any | |
451 | * locks that might be needed are taken by the caller. | |
452 | */ | |
b2f408fe | 453 | static void fast_mix(u32 pool[4]) |
775f4b29 | 454 | { |
b2f408fe JD |
455 | u32 a = pool[0], b = pool[1]; |
456 | u32 c = pool[2], d = pool[3]; | |
43759d4f TT |
457 | |
458 | a += b; c += d; | |
19acc77a | 459 | b = rol32(b, 6); d = rol32(d, 27); |
43759d4f TT |
460 | d ^= a; b ^= c; |
461 | ||
462 | a += b; c += d; | |
19acc77a | 463 | b = rol32(b, 16); d = rol32(d, 14); |
43759d4f TT |
464 | d ^= a; b ^= c; |
465 | ||
466 | a += b; c += d; | |
19acc77a | 467 | b = rol32(b, 6); d = rol32(d, 27); |
43759d4f TT |
468 | d ^= a; b ^= c; |
469 | ||
470 | a += b; c += d; | |
19acc77a | 471 | b = rol32(b, 16); d = rol32(d, 14); |
43759d4f TT |
472 | d ^= a; b ^= c; |
473 | ||
b2f408fe JD |
474 | pool[0] = a; pool[1] = b; |
475 | pool[2] = c; pool[3] = d; | |
775f4b29 TT |
476 | } |
477 | ||
04ec96b7 | 478 | static void credit_entropy_bits(size_t nbits) |
1da177e4 | 479 | { |
04ec96b7 | 480 | unsigned int entropy_count, orig, add; |
18263c4e | 481 | |
04ec96b7 | 482 | if (!nbits) |
adc782da MM |
483 | return; |
484 | ||
04ec96b7 | 485 | add = min_t(size_t, nbits, POOL_BITS); |
a49c010e | 486 | |
c5704490 JD |
487 | do { |
488 | orig = READ_ONCE(input_pool.entropy_count); | |
04ec96b7 | 489 | entropy_count = min_t(unsigned int, POOL_BITS, orig + add); |
c5704490 | 490 | } while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig); |
1da177e4 | 491 | |
c5704490 | 492 | if (crng_init < 2 && entropy_count >= POOL_MIN_BITS) |
a9412d51 | 493 | crng_reseed(); |
1da177e4 LT |
494 | } |
495 | ||
e192be9d TT |
496 | /********************************************************************* |
497 | * | |
498 | * CRNG using CHACHA20 | |
499 | * | |
500 | *********************************************************************/ | |
501 | ||
186873c5 JD |
502 | enum { |
503 | CRNG_RESEED_INTERVAL = 300 * HZ, | |
504 | CRNG_INIT_CNT_THRESH = 2 * CHACHA_KEY_SIZE | |
505 | }; | |
506 | ||
507 | static struct { | |
508 | u8 key[CHACHA_KEY_SIZE] __aligned(__alignof__(long)); | |
509 | unsigned long birth; | |
510 | unsigned long generation; | |
511 | spinlock_t lock; | |
512 | } base_crng = { | |
513 | .lock = __SPIN_LOCK_UNLOCKED(base_crng.lock) | |
514 | }; | |
515 | ||
516 | struct crng { | |
517 | u8 key[CHACHA_KEY_SIZE]; | |
518 | unsigned long generation; | |
519 | local_lock_t lock; | |
520 | }; | |
521 | ||
522 | static DEFINE_PER_CPU(struct crng, crngs) = { | |
523 | .generation = ULONG_MAX, | |
524 | .lock = INIT_LOCAL_LOCK(crngs.lock), | |
525 | }; | |
e192be9d | 526 | |
dc12baac TT |
527 | /* |
528 | * crng_fast_load() can be called by code in the interrupt service | |
73c7733f JD |
529 | * path. So we can't afford to dilly-dally. Returns the number of |
530 | * bytes processed from cp. | |
dc12baac | 531 | */ |
04ec96b7 | 532 | static size_t crng_fast_load(const void *cp, size_t len) |
e192be9d TT |
533 | { |
534 | unsigned long flags; | |
04ec96b7 | 535 | const u8 *src = (const u8 *)cp; |
73c7733f | 536 | size_t ret = 0; |
e192be9d | 537 | |
186873c5 | 538 | if (!spin_trylock_irqsave(&base_crng.lock, flags)) |
e192be9d | 539 | return 0; |
43838a23 | 540 | if (crng_init != 0) { |
186873c5 | 541 | spin_unlock_irqrestore(&base_crng.lock, flags); |
e192be9d TT |
542 | return 0; |
543 | } | |
e192be9d | 544 | while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) { |
04ec96b7 JD |
545 | base_crng.key[crng_init_cnt % sizeof(base_crng.key)] ^= *src; |
546 | src++; crng_init_cnt++; len--; ret++; | |
e192be9d TT |
547 | } |
548 | if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) { | |
0791e8b6 | 549 | ++base_crng.generation; |
e192be9d | 550 | crng_init = 1; |
e192be9d | 551 | } |
186873c5 | 552 | spin_unlock_irqrestore(&base_crng.lock, flags); |
7c2fe2b3 DB |
553 | if (crng_init == 1) |
554 | pr_notice("fast init done\n"); | |
73c7733f | 555 | return ret; |
e192be9d TT |
556 | } |
557 | ||
dc12baac TT |
558 | /* |
559 | * crng_slow_load() is called by add_device_randomness, which has two | |
560 | * attributes. (1) We can't trust the buffer passed to it is | |
561 | * guaranteed to be unpredictable (so it might not have any entropy at | |
562 | * all), and (2) it doesn't have the performance constraints of | |
563 | * crng_fast_load(). | |
564 | * | |
66e4c2b9 JD |
565 | * So, we simply hash the contents in with the current key. Finally, |
566 | * we do *not* advance crng_init_cnt since buffer we may get may be | |
567 | * something like a fixed DMI table (for example), which might very | |
568 | * well be unique to the machine, but is otherwise unvarying. | |
dc12baac | 569 | */ |
04ec96b7 | 570 | static void crng_slow_load(const void *cp, size_t len) |
dc12baac | 571 | { |
248045b8 | 572 | unsigned long flags; |
66e4c2b9 JD |
573 | struct blake2s_state hash; |
574 | ||
575 | blake2s_init(&hash, sizeof(base_crng.key)); | |
dc12baac | 576 | |
186873c5 | 577 | if (!spin_trylock_irqsave(&base_crng.lock, flags)) |
66e4c2b9 | 578 | return; |
dc12baac | 579 | if (crng_init != 0) { |
186873c5 | 580 | spin_unlock_irqrestore(&base_crng.lock, flags); |
66e4c2b9 | 581 | return; |
dc12baac | 582 | } |
66e4c2b9 JD |
583 | |
584 | blake2s_update(&hash, base_crng.key, sizeof(base_crng.key)); | |
585 | blake2s_update(&hash, cp, len); | |
586 | blake2s_final(&hash, base_crng.key); | |
587 | ||
186873c5 | 588 | spin_unlock_irqrestore(&base_crng.lock, flags); |
dc12baac TT |
589 | } |
590 | ||
a9412d51 | 591 | static void crng_reseed(void) |
e192be9d | 592 | { |
248045b8 | 593 | unsigned long flags; |
186873c5 JD |
594 | unsigned long next_gen; |
595 | u8 key[CHACHA_KEY_SIZE]; | |
7191c628 | 596 | bool finalize_init = false; |
e192be9d | 597 | |
246c03dd JD |
598 | /* Only reseed if we can, to prevent brute forcing a small amount of new bits. */ |
599 | if (!drain_entropy(key, sizeof(key))) | |
600 | return; | |
a9412d51 | 601 | |
186873c5 JD |
602 | /* |
603 | * We copy the new key into the base_crng, overwriting the old one, | |
604 | * and update the generation counter. We avoid hitting ULONG_MAX, | |
605 | * because the per-cpu crngs are initialized to ULONG_MAX, so this | |
606 | * forces new CPUs that come online to always initialize. | |
607 | */ | |
608 | spin_lock_irqsave(&base_crng.lock, flags); | |
609 | memcpy(base_crng.key, key, sizeof(base_crng.key)); | |
610 | next_gen = base_crng.generation + 1; | |
611 | if (next_gen == ULONG_MAX) | |
612 | ++next_gen; | |
613 | WRITE_ONCE(base_crng.generation, next_gen); | |
614 | WRITE_ONCE(base_crng.birth, jiffies); | |
a9412d51 | 615 | if (crng_init < 2) { |
a9412d51 | 616 | crng_init = 2; |
7191c628 DB |
617 | finalize_init = true; |
618 | } | |
619 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
620 | memzero_explicit(key, sizeof(key)); | |
621 | if (finalize_init) { | |
a9412d51 JD |
622 | process_random_ready_list(); |
623 | wake_up_interruptible(&crng_init_wait); | |
624 | kill_fasync(&fasync, SIGIO, POLL_IN); | |
625 | pr_notice("crng init done\n"); | |
626 | if (unseeded_warning.missed) { | |
627 | pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n", | |
628 | unseeded_warning.missed); | |
629 | unseeded_warning.missed = 0; | |
630 | } | |
631 | if (urandom_warning.missed) { | |
632 | pr_notice("%d urandom warning(s) missed due to ratelimiting\n", | |
633 | urandom_warning.missed); | |
634 | urandom_warning.missed = 0; | |
635 | } | |
636 | } | |
e192be9d TT |
637 | } |
638 | ||
186873c5 JD |
639 | /* |
640 | * The general form here is based on a "fast key erasure RNG" from | |
641 | * <https://blog.cr.yp.to/20170723-random.html>. It generates a ChaCha | |
642 | * block using the provided key, and then immediately overwites that | |
643 | * key with half the block. It returns the resultant ChaCha state to the | |
644 | * user, along with the second half of the block containing 32 bytes of | |
645 | * random data that may be used; random_data_len may not be greater than | |
646 | * 32. | |
647 | */ | |
648 | static void crng_fast_key_erasure(u8 key[CHACHA_KEY_SIZE], | |
649 | u32 chacha_state[CHACHA_STATE_WORDS], | |
650 | u8 *random_data, size_t random_data_len) | |
e192be9d | 651 | { |
186873c5 | 652 | u8 first_block[CHACHA_BLOCK_SIZE]; |
009ba856 | 653 | |
186873c5 JD |
654 | BUG_ON(random_data_len > 32); |
655 | ||
656 | chacha_init_consts(chacha_state); | |
657 | memcpy(&chacha_state[4], key, CHACHA_KEY_SIZE); | |
658 | memset(&chacha_state[12], 0, sizeof(u32) * 4); | |
659 | chacha20_block(chacha_state, first_block); | |
660 | ||
661 | memcpy(key, first_block, CHACHA_KEY_SIZE); | |
662 | memcpy(random_data, first_block + CHACHA_KEY_SIZE, random_data_len); | |
663 | memzero_explicit(first_block, sizeof(first_block)); | |
1e7f583a TT |
664 | } |
665 | ||
c92e040d | 666 | /* |
186873c5 JD |
667 | * This function returns a ChaCha state that you may use for generating |
668 | * random data. It also returns up to 32 bytes on its own of random data | |
669 | * that may be used; random_data_len may not be greater than 32. | |
c92e040d | 670 | */ |
186873c5 JD |
671 | static void crng_make_state(u32 chacha_state[CHACHA_STATE_WORDS], |
672 | u8 *random_data, size_t random_data_len) | |
c92e040d | 673 | { |
248045b8 | 674 | unsigned long flags; |
186873c5 | 675 | struct crng *crng; |
c92e040d | 676 | |
186873c5 JD |
677 | BUG_ON(random_data_len > 32); |
678 | ||
679 | /* | |
680 | * For the fast path, we check whether we're ready, unlocked first, and | |
681 | * then re-check once locked later. In the case where we're really not | |
682 | * ready, we do fast key erasure with the base_crng directly, because | |
683 | * this is what crng_{fast,slow}_load mutate during early init. | |
684 | */ | |
685 | if (unlikely(!crng_ready())) { | |
686 | bool ready; | |
687 | ||
688 | spin_lock_irqsave(&base_crng.lock, flags); | |
689 | ready = crng_ready(); | |
690 | if (!ready) | |
691 | crng_fast_key_erasure(base_crng.key, chacha_state, | |
692 | random_data, random_data_len); | |
693 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
694 | if (!ready) | |
695 | return; | |
c92e040d | 696 | } |
186873c5 JD |
697 | |
698 | /* | |
699 | * If the base_crng is more than 5 minutes old, we reseed, which | |
700 | * in turn bumps the generation counter that we check below. | |
701 | */ | |
702 | if (unlikely(time_after(jiffies, READ_ONCE(base_crng.birth) + CRNG_RESEED_INTERVAL))) | |
703 | crng_reseed(); | |
704 | ||
705 | local_lock_irqsave(&crngs.lock, flags); | |
706 | crng = raw_cpu_ptr(&crngs); | |
707 | ||
708 | /* | |
709 | * If our per-cpu crng is older than the base_crng, then it means | |
710 | * somebody reseeded the base_crng. In that case, we do fast key | |
711 | * erasure on the base_crng, and use its output as the new key | |
712 | * for our per-cpu crng. This brings us up to date with base_crng. | |
713 | */ | |
714 | if (unlikely(crng->generation != READ_ONCE(base_crng.generation))) { | |
715 | spin_lock(&base_crng.lock); | |
716 | crng_fast_key_erasure(base_crng.key, chacha_state, | |
717 | crng->key, sizeof(crng->key)); | |
718 | crng->generation = base_crng.generation; | |
719 | spin_unlock(&base_crng.lock); | |
720 | } | |
721 | ||
722 | /* | |
723 | * Finally, when we've made it this far, our per-cpu crng has an up | |
724 | * to date key, and we can do fast key erasure with it to produce | |
725 | * some random data and a ChaCha state for the caller. All other | |
726 | * branches of this function are "unlikely", so most of the time we | |
727 | * should wind up here immediately. | |
728 | */ | |
729 | crng_fast_key_erasure(crng->key, chacha_state, random_data, random_data_len); | |
730 | local_unlock_irqrestore(&crngs.lock, flags); | |
c92e040d TT |
731 | } |
732 | ||
186873c5 | 733 | static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes) |
e192be9d | 734 | { |
186873c5 | 735 | bool large_request = nbytes > 256; |
04ec96b7 JD |
736 | ssize_t ret = 0; |
737 | size_t len; | |
186873c5 JD |
738 | u32 chacha_state[CHACHA_STATE_WORDS]; |
739 | u8 output[CHACHA_BLOCK_SIZE]; | |
740 | ||
741 | if (!nbytes) | |
742 | return 0; | |
743 | ||
04ec96b7 | 744 | len = min_t(size_t, 32, nbytes); |
186873c5 JD |
745 | crng_make_state(chacha_state, output, len); |
746 | ||
747 | if (copy_to_user(buf, output, len)) | |
748 | return -EFAULT; | |
749 | nbytes -= len; | |
750 | buf += len; | |
751 | ret += len; | |
e192be9d TT |
752 | |
753 | while (nbytes) { | |
754 | if (large_request && need_resched()) { | |
186873c5 | 755 | if (signal_pending(current)) |
e192be9d | 756 | break; |
e192be9d TT |
757 | schedule(); |
758 | } | |
759 | ||
186873c5 JD |
760 | chacha20_block(chacha_state, output); |
761 | if (unlikely(chacha_state[12] == 0)) | |
762 | ++chacha_state[13]; | |
763 | ||
04ec96b7 | 764 | len = min_t(size_t, nbytes, CHACHA_BLOCK_SIZE); |
186873c5 | 765 | if (copy_to_user(buf, output, len)) { |
e192be9d TT |
766 | ret = -EFAULT; |
767 | break; | |
768 | } | |
769 | ||
186873c5 JD |
770 | nbytes -= len; |
771 | buf += len; | |
772 | ret += len; | |
e192be9d | 773 | } |
e192be9d | 774 | |
186873c5 JD |
775 | memzero_explicit(chacha_state, sizeof(chacha_state)); |
776 | memzero_explicit(output, sizeof(output)); | |
e192be9d TT |
777 | return ret; |
778 | } | |
779 | ||
1da177e4 LT |
780 | /********************************************************************* |
781 | * | |
782 | * Entropy input management | |
783 | * | |
784 | *********************************************************************/ | |
785 | ||
786 | /* There is one of these per entropy source */ | |
787 | struct timer_rand_state { | |
788 | cycles_t last_time; | |
90b75ee5 | 789 | long last_delta, last_delta2; |
1da177e4 LT |
790 | }; |
791 | ||
644008df TT |
792 | #define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, }; |
793 | ||
a2080a67 | 794 | /* |
e192be9d TT |
795 | * Add device- or boot-specific data to the input pool to help |
796 | * initialize it. | |
a2080a67 | 797 | * |
e192be9d TT |
798 | * None of this adds any entropy; it is meant to avoid the problem of |
799 | * the entropy pool having similar initial state across largely | |
800 | * identical devices. | |
a2080a67 | 801 | */ |
04ec96b7 | 802 | void add_device_randomness(const void *buf, size_t size) |
a2080a67 | 803 | { |
61875f30 | 804 | unsigned long time = random_get_entropy() ^ jiffies; |
3ef4cb2d | 805 | unsigned long flags; |
a2080a67 | 806 | |
dc12baac TT |
807 | if (!crng_ready() && size) |
808 | crng_slow_load(buf, size); | |
ee7998c5 | 809 | |
3ef4cb2d | 810 | spin_lock_irqsave(&input_pool.lock, flags); |
90ed1e67 JD |
811 | _mix_pool_bytes(buf, size); |
812 | _mix_pool_bytes(&time, sizeof(time)); | |
3ef4cb2d | 813 | spin_unlock_irqrestore(&input_pool.lock, flags); |
a2080a67 LT |
814 | } |
815 | EXPORT_SYMBOL(add_device_randomness); | |
816 | ||
644008df | 817 | static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE; |
3060d6fe | 818 | |
1da177e4 LT |
819 | /* |
820 | * This function adds entropy to the entropy "pool" by using timing | |
821 | * delays. It uses the timer_rand_state structure to make an estimate | |
822 | * of how many bits of entropy this call has added to the pool. | |
823 | * | |
824 | * The number "num" is also added to the pool - it should somehow describe | |
825 | * the type of event which just happened. This is currently 0-255 for | |
826 | * keyboard scan codes, and 256 upwards for interrupts. | |
827 | * | |
828 | */ | |
04ec96b7 | 829 | static void add_timer_randomness(struct timer_rand_state *state, unsigned int num) |
1da177e4 LT |
830 | { |
831 | struct { | |
1da177e4 | 832 | long jiffies; |
d38bb085 JD |
833 | unsigned int cycles; |
834 | unsigned int num; | |
1da177e4 LT |
835 | } sample; |
836 | long delta, delta2, delta3; | |
837 | ||
1da177e4 | 838 | sample.jiffies = jiffies; |
61875f30 | 839 | sample.cycles = random_get_entropy(); |
1da177e4 | 840 | sample.num = num; |
90ed1e67 | 841 | mix_pool_bytes(&sample, sizeof(sample)); |
1da177e4 LT |
842 | |
843 | /* | |
844 | * Calculate number of bits of randomness we probably added. | |
845 | * We take into account the first, second and third-order deltas | |
846 | * in order to make our estimate. | |
847 | */ | |
e00d996a QC |
848 | delta = sample.jiffies - READ_ONCE(state->last_time); |
849 | WRITE_ONCE(state->last_time, sample.jiffies); | |
5e747dd9 | 850 | |
e00d996a QC |
851 | delta2 = delta - READ_ONCE(state->last_delta); |
852 | WRITE_ONCE(state->last_delta, delta); | |
5e747dd9 | 853 | |
e00d996a QC |
854 | delta3 = delta2 - READ_ONCE(state->last_delta2); |
855 | WRITE_ONCE(state->last_delta2, delta2); | |
5e747dd9 RV |
856 | |
857 | if (delta < 0) | |
858 | delta = -delta; | |
859 | if (delta2 < 0) | |
860 | delta2 = -delta2; | |
861 | if (delta3 < 0) | |
862 | delta3 = -delta3; | |
863 | if (delta > delta2) | |
864 | delta = delta2; | |
865 | if (delta > delta3) | |
866 | delta = delta3; | |
1da177e4 | 867 | |
5e747dd9 RV |
868 | /* |
869 | * delta is now minimum absolute delta. | |
870 | * Round down by 1 bit on general principles, | |
727d499a | 871 | * and limit entropy estimate to 12 bits. |
5e747dd9 | 872 | */ |
04ec96b7 | 873 | credit_entropy_bits(min_t(unsigned int, fls(delta >> 1), 11)); |
1da177e4 LT |
874 | } |
875 | ||
d251575a | 876 | void add_input_randomness(unsigned int type, unsigned int code, |
248045b8 | 877 | unsigned int value) |
1da177e4 LT |
878 | { |
879 | static unsigned char last_value; | |
880 | ||
881 | /* ignore autorepeat and the like */ | |
882 | if (value == last_value) | |
883 | return; | |
884 | ||
1da177e4 LT |
885 | last_value = value; |
886 | add_timer_randomness(&input_timer_state, | |
887 | (type << 4) ^ code ^ (code >> 4) ^ value); | |
888 | } | |
80fc9f53 | 889 | EXPORT_SYMBOL_GPL(add_input_randomness); |
1da177e4 | 890 | |
775f4b29 TT |
891 | static DEFINE_PER_CPU(struct fast_pool, irq_randomness); |
892 | ||
d38bb085 | 893 | static u32 get_reg(struct fast_pool *f, struct pt_regs *regs) |
ee3e00e9 | 894 | { |
248045b8 | 895 | u32 *ptr = (u32 *)regs; |
92e75428 | 896 | unsigned int idx; |
ee3e00e9 TT |
897 | |
898 | if (regs == NULL) | |
899 | return 0; | |
92e75428 | 900 | idx = READ_ONCE(f->reg_idx); |
d38bb085 | 901 | if (idx >= sizeof(struct pt_regs) / sizeof(u32)) |
92e75428 TT |
902 | idx = 0; |
903 | ptr += idx++; | |
904 | WRITE_ONCE(f->reg_idx, idx); | |
9dfa7bba | 905 | return *ptr; |
ee3e00e9 TT |
906 | } |
907 | ||
703f7066 | 908 | void add_interrupt_randomness(int irq) |
1da177e4 | 909 | { |
248045b8 JD |
910 | struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness); |
911 | struct pt_regs *regs = get_irq_regs(); | |
912 | unsigned long now = jiffies; | |
913 | cycles_t cycles = random_get_entropy(); | |
3060d6fe | 914 | |
ee3e00e9 TT |
915 | if (cycles == 0) |
916 | cycles = get_reg(fast_pool, regs); | |
3060d6fe | 917 | |
b2f408fe JD |
918 | if (sizeof(cycles) == 8) |
919 | fast_pool->pool64[0] ^= cycles ^ rol64(now, 32) ^ irq; | |
920 | else { | |
921 | fast_pool->pool32[0] ^= cycles ^ irq; | |
922 | fast_pool->pool32[1] ^= now; | |
923 | } | |
924 | ||
925 | if (sizeof(unsigned long) == 8) | |
926 | fast_pool->pool64[1] ^= regs ? instruction_pointer(regs) : _RET_IP_; | |
927 | else { | |
928 | fast_pool->pool32[2] ^= regs ? instruction_pointer(regs) : _RET_IP_; | |
929 | fast_pool->pool32[3] ^= get_reg(fast_pool, regs); | |
930 | } | |
931 | ||
932 | fast_mix(fast_pool->pool32); | |
933 | ++fast_pool->count; | |
3060d6fe | 934 | |
43838a23 | 935 | if (unlikely(crng_init == 0)) { |
04ec96b7 | 936 | if (fast_pool->count >= 64 && |
b2f408fe | 937 | crng_fast_load(fast_pool->pool32, sizeof(fast_pool->pool32)) > 0) { |
e192be9d TT |
938 | fast_pool->count = 0; |
939 | fast_pool->last = now; | |
c30c575d | 940 | if (spin_trylock(&input_pool.lock)) { |
b2f408fe | 941 | _mix_pool_bytes(&fast_pool->pool32, sizeof(fast_pool->pool32)); |
c30c575d JD |
942 | spin_unlock(&input_pool.lock); |
943 | } | |
e192be9d TT |
944 | } |
945 | return; | |
946 | } | |
947 | ||
248045b8 | 948 | if ((fast_pool->count < 64) && !time_after(now, fast_pool->last + HZ)) |
1da177e4 LT |
949 | return; |
950 | ||
90ed1e67 | 951 | if (!spin_trylock(&input_pool.lock)) |
91fcb532 | 952 | return; |
83664a69 | 953 | |
91fcb532 | 954 | fast_pool->last = now; |
b2f408fe | 955 | _mix_pool_bytes(&fast_pool->pool32, sizeof(fast_pool->pool32)); |
90ed1e67 | 956 | spin_unlock(&input_pool.lock); |
83664a69 | 957 | |
ee3e00e9 | 958 | fast_pool->count = 0; |
83664a69 | 959 | |
ee3e00e9 | 960 | /* award one bit for the contents of the fast pool */ |
90ed1e67 | 961 | credit_entropy_bits(1); |
1da177e4 | 962 | } |
4b44f2d1 | 963 | EXPORT_SYMBOL_GPL(add_interrupt_randomness); |
1da177e4 | 964 | |
9361401e | 965 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
966 | void add_disk_randomness(struct gendisk *disk) |
967 | { | |
968 | if (!disk || !disk->random) | |
969 | return; | |
970 | /* first major is 1, so we get >= 0x200 here */ | |
f331c029 | 971 | add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); |
1da177e4 | 972 | } |
bdcfa3e5 | 973 | EXPORT_SYMBOL_GPL(add_disk_randomness); |
9361401e | 974 | #endif |
1da177e4 | 975 | |
1da177e4 LT |
976 | /********************************************************************* |
977 | * | |
978 | * Entropy extraction routines | |
979 | * | |
980 | *********************************************************************/ | |
981 | ||
19fa5be1 | 982 | /* |
6e8ec255 JD |
983 | * This is an HKDF-like construction for using the hashed collected entropy |
984 | * as a PRF key, that's then expanded block-by-block. | |
19fa5be1 | 985 | */ |
9c07f578 | 986 | static void extract_entropy(void *buf, size_t nbytes) |
1da177e4 | 987 | { |
902c098a | 988 | unsigned long flags; |
6e8ec255 JD |
989 | u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE]; |
990 | struct { | |
28f425e5 | 991 | unsigned long rdseed[32 / sizeof(long)]; |
6e8ec255 JD |
992 | size_t counter; |
993 | } block; | |
994 | size_t i; | |
995 | ||
28f425e5 JD |
996 | for (i = 0; i < ARRAY_SIZE(block.rdseed); ++i) { |
997 | if (!arch_get_random_seed_long(&block.rdseed[i]) && | |
998 | !arch_get_random_long(&block.rdseed[i])) | |
999 | block.rdseed[i] = random_get_entropy(); | |
85a1f777 TT |
1000 | } |
1001 | ||
90ed1e67 | 1002 | spin_lock_irqsave(&input_pool.lock, flags); |
46884442 | 1003 | |
6e8ec255 JD |
1004 | /* seed = HASHPRF(last_key, entropy_input) */ |
1005 | blake2s_final(&input_pool.hash, seed); | |
1da177e4 | 1006 | |
28f425e5 | 1007 | /* next_key = HASHPRF(seed, RDSEED || 0) */ |
6e8ec255 JD |
1008 | block.counter = 0; |
1009 | blake2s(next_key, (u8 *)&block, seed, sizeof(next_key), sizeof(block), sizeof(seed)); | |
1010 | blake2s_init_key(&input_pool.hash, BLAKE2S_HASH_SIZE, next_key, sizeof(next_key)); | |
1da177e4 | 1011 | |
6e8ec255 JD |
1012 | spin_unlock_irqrestore(&input_pool.lock, flags); |
1013 | memzero_explicit(next_key, sizeof(next_key)); | |
e192be9d TT |
1014 | |
1015 | while (nbytes) { | |
6e8ec255 | 1016 | i = min_t(size_t, nbytes, BLAKE2S_HASH_SIZE); |
28f425e5 | 1017 | /* output = HASHPRF(seed, RDSEED || ++counter) */ |
6e8ec255 JD |
1018 | ++block.counter; |
1019 | blake2s(buf, (u8 *)&block, seed, i, sizeof(block), sizeof(seed)); | |
e192be9d TT |
1020 | nbytes -= i; |
1021 | buf += i; | |
e192be9d TT |
1022 | } |
1023 | ||
6e8ec255 JD |
1024 | memzero_explicit(seed, sizeof(seed)); |
1025 | memzero_explicit(&block, sizeof(block)); | |
e192be9d TT |
1026 | } |
1027 | ||
246c03dd JD |
1028 | /* |
1029 | * First we make sure we have POOL_MIN_BITS of entropy in the pool, and then we | |
1030 | * set the entropy count to zero (but don't actually touch any data). Only then | |
1031 | * can we extract a new key with extract_entropy(). | |
1032 | */ | |
1033 | static bool drain_entropy(void *buf, size_t nbytes) | |
1034 | { | |
1035 | unsigned int entropy_count; | |
1036 | do { | |
1037 | entropy_count = READ_ONCE(input_pool.entropy_count); | |
1038 | if (entropy_count < POOL_MIN_BITS) | |
1039 | return false; | |
1040 | } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count); | |
1041 | extract_entropy(buf, nbytes); | |
1042 | wake_up_interruptible(&random_write_wait); | |
1043 | kill_fasync(&fasync, SIGIO, POLL_OUT); | |
1044 | return true; | |
1045 | } | |
1046 | ||
1da177e4 LT |
1047 | /* |
1048 | * This function is the exported kernel interface. It returns some | |
c2557a30 | 1049 | * number of good random numbers, suitable for key generation, seeding |
18e9cea7 GP |
1050 | * TCP sequence numbers, etc. It does not rely on the hardware random |
1051 | * number generator. For random bytes direct from the hardware RNG | |
e297a783 JD |
1052 | * (when available), use get_random_bytes_arch(). In order to ensure |
1053 | * that the randomness provided by this function is okay, the function | |
1054 | * wait_for_random_bytes() should be called and return 0 at least once | |
1055 | * at any point prior. | |
1da177e4 | 1056 | */ |
04ec96b7 | 1057 | static void _get_random_bytes(void *buf, size_t nbytes) |
c2557a30 | 1058 | { |
186873c5 JD |
1059 | u32 chacha_state[CHACHA_STATE_WORDS]; |
1060 | u8 tmp[CHACHA_BLOCK_SIZE]; | |
04ec96b7 | 1061 | size_t len; |
e192be9d | 1062 | |
186873c5 JD |
1063 | if (!nbytes) |
1064 | return; | |
1065 | ||
04ec96b7 | 1066 | len = min_t(size_t, 32, nbytes); |
186873c5 JD |
1067 | crng_make_state(chacha_state, buf, len); |
1068 | nbytes -= len; | |
1069 | buf += len; | |
1070 | ||
1071 | while (nbytes) { | |
1072 | if (nbytes < CHACHA_BLOCK_SIZE) { | |
1073 | chacha20_block(chacha_state, tmp); | |
1074 | memcpy(buf, tmp, nbytes); | |
1075 | memzero_explicit(tmp, sizeof(tmp)); | |
1076 | break; | |
1077 | } | |
1078 | ||
1079 | chacha20_block(chacha_state, buf); | |
1080 | if (unlikely(chacha_state[12] == 0)) | |
1081 | ++chacha_state[13]; | |
1ca1b917 | 1082 | nbytes -= CHACHA_BLOCK_SIZE; |
186873c5 | 1083 | buf += CHACHA_BLOCK_SIZE; |
e192be9d TT |
1084 | } |
1085 | ||
186873c5 | 1086 | memzero_explicit(chacha_state, sizeof(chacha_state)); |
c2557a30 | 1087 | } |
eecabf56 | 1088 | |
04ec96b7 | 1089 | void get_random_bytes(void *buf, size_t nbytes) |
eecabf56 TT |
1090 | { |
1091 | static void *previous; | |
1092 | ||
1093 | warn_unseeded_randomness(&previous); | |
1094 | _get_random_bytes(buf, nbytes); | |
1095 | } | |
c2557a30 TT |
1096 | EXPORT_SYMBOL(get_random_bytes); |
1097 | ||
50ee7529 LT |
1098 | /* |
1099 | * Each time the timer fires, we expect that we got an unpredictable | |
1100 | * jump in the cycle counter. Even if the timer is running on another | |
1101 | * CPU, the timer activity will be touching the stack of the CPU that is | |
1102 | * generating entropy.. | |
1103 | * | |
1104 | * Note that we don't re-arm the timer in the timer itself - we are | |
1105 | * happy to be scheduled away, since that just makes the load more | |
1106 | * complex, but we do not want the timer to keep ticking unless the | |
1107 | * entropy loop is running. | |
1108 | * | |
1109 | * So the re-arming always happens in the entropy loop itself. | |
1110 | */ | |
1111 | static void entropy_timer(struct timer_list *t) | |
1112 | { | |
90ed1e67 | 1113 | credit_entropy_bits(1); |
50ee7529 LT |
1114 | } |
1115 | ||
1116 | /* | |
1117 | * If we have an actual cycle counter, see if we can | |
1118 | * generate enough entropy with timing noise | |
1119 | */ | |
1120 | static void try_to_generate_entropy(void) | |
1121 | { | |
1122 | struct { | |
1123 | unsigned long now; | |
1124 | struct timer_list timer; | |
1125 | } stack; | |
1126 | ||
1127 | stack.now = random_get_entropy(); | |
1128 | ||
1129 | /* Slow counter - or none. Don't even bother */ | |
1130 | if (stack.now == random_get_entropy()) | |
1131 | return; | |
1132 | ||
1133 | timer_setup_on_stack(&stack.timer, entropy_timer, 0); | |
1134 | while (!crng_ready()) { | |
1135 | if (!timer_pending(&stack.timer)) | |
248045b8 | 1136 | mod_timer(&stack.timer, jiffies + 1); |
90ed1e67 | 1137 | mix_pool_bytes(&stack.now, sizeof(stack.now)); |
50ee7529 LT |
1138 | schedule(); |
1139 | stack.now = random_get_entropy(); | |
1140 | } | |
1141 | ||
1142 | del_timer_sync(&stack.timer); | |
1143 | destroy_timer_on_stack(&stack.timer); | |
90ed1e67 | 1144 | mix_pool_bytes(&stack.now, sizeof(stack.now)); |
50ee7529 LT |
1145 | } |
1146 | ||
c2557a30 TT |
1147 | /* |
1148 | * This function will use the architecture-specific hardware random | |
04ec96b7 JD |
1149 | * number generator if it is available. It is not recommended for |
1150 | * use. Use get_random_bytes() instead. It returns the number of | |
1151 | * bytes filled in. | |
c2557a30 | 1152 | */ |
04ec96b7 | 1153 | size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes) |
1da177e4 | 1154 | { |
04ec96b7 | 1155 | size_t left = nbytes; |
d38bb085 | 1156 | u8 *p = buf; |
63d77173 | 1157 | |
753d433b | 1158 | while (left) { |
63d77173 | 1159 | unsigned long v; |
04ec96b7 | 1160 | size_t chunk = min_t(size_t, left, sizeof(unsigned long)); |
c2557a30 | 1161 | |
63d77173 PA |
1162 | if (!arch_get_random_long(&v)) |
1163 | break; | |
8ddd6efa | 1164 | |
bd29e568 | 1165 | memcpy(p, &v, chunk); |
63d77173 | 1166 | p += chunk; |
753d433b | 1167 | left -= chunk; |
63d77173 PA |
1168 | } |
1169 | ||
753d433b | 1170 | return nbytes - left; |
1da177e4 | 1171 | } |
c2557a30 TT |
1172 | EXPORT_SYMBOL(get_random_bytes_arch); |
1173 | ||
85664172 JD |
1174 | static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU); |
1175 | static int __init parse_trust_cpu(char *arg) | |
1176 | { | |
1177 | return kstrtobool(arg, &trust_cpu); | |
1178 | } | |
1179 | early_param("random.trust_cpu", parse_trust_cpu); | |
1180 | ||
1da177e4 | 1181 | /* |
85664172 JD |
1182 | * Note that setup_arch() may call add_device_randomness() |
1183 | * long before we get here. This allows seeding of the pools | |
1184 | * with some platform dependent data very early in the boot | |
1185 | * process. But it limits our options here. We must use | |
1186 | * statically allocated structures that already have all | |
1187 | * initializations complete at compile time. We should also | |
1188 | * take care not to overwrite the precious per platform data | |
1189 | * we were given. | |
1da177e4 | 1190 | */ |
85664172 | 1191 | int __init rand_initialize(void) |
1da177e4 | 1192 | { |
04ec96b7 | 1193 | size_t i; |
902c098a | 1194 | ktime_t now = ktime_get_real(); |
85664172 | 1195 | bool arch_init = true; |
902c098a | 1196 | unsigned long rv; |
1da177e4 | 1197 | |
04ec96b7 | 1198 | for (i = 0; i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) { |
85664172 JD |
1199 | if (!arch_get_random_seed_long_early(&rv) && |
1200 | !arch_get_random_long_early(&rv)) { | |
1201 | rv = random_get_entropy(); | |
1202 | arch_init = false; | |
1203 | } | |
a02cf3d0 | 1204 | mix_pool_bytes(&rv, sizeof(rv)); |
85664172 | 1205 | } |
a02cf3d0 JD |
1206 | mix_pool_bytes(&now, sizeof(now)); |
1207 | mix_pool_bytes(utsname(), sizeof(*(utsname()))); | |
1208 | ||
186873c5 | 1209 | extract_entropy(base_crng.key, sizeof(base_crng.key)); |
0791e8b6 JD |
1210 | ++base_crng.generation; |
1211 | ||
85664172 | 1212 | if (arch_init && trust_cpu && crng_init < 2) { |
85664172 JD |
1213 | crng_init = 2; |
1214 | pr_notice("crng init done (trusting CPU's manufacturer)\n"); | |
1215 | } | |
85664172 | 1216 | |
4e00b339 TT |
1217 | if (ratelimit_disable) { |
1218 | urandom_warning.interval = 0; | |
1219 | unseeded_warning.interval = 0; | |
1220 | } | |
1da177e4 LT |
1221 | return 0; |
1222 | } | |
1da177e4 | 1223 | |
9361401e | 1224 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1225 | void rand_initialize_disk(struct gendisk *disk) |
1226 | { | |
1227 | struct timer_rand_state *state; | |
1228 | ||
1229 | /* | |
f8595815 | 1230 | * If kzalloc returns null, we just won't use that entropy |
1da177e4 LT |
1231 | * source. |
1232 | */ | |
f8595815 | 1233 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
644008df TT |
1234 | if (state) { |
1235 | state->last_time = INITIAL_JIFFIES; | |
1da177e4 | 1236 | disk->random = state; |
644008df | 1237 | } |
1da177e4 | 1238 | } |
9361401e | 1239 | #endif |
1da177e4 | 1240 | |
248045b8 JD |
1241 | static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes, |
1242 | loff_t *ppos) | |
1da177e4 | 1243 | { |
9b4d0087 | 1244 | static int maxwarn = 10; |
301f0595 | 1245 | |
e192be9d | 1246 | if (!crng_ready() && maxwarn > 0) { |
9b4d0087 | 1247 | maxwarn--; |
4e00b339 | 1248 | if (__ratelimit(&urandom_warning)) |
12cd53af YL |
1249 | pr_notice("%s: uninitialized urandom read (%zd bytes read)\n", |
1250 | current->comm, nbytes); | |
9b4d0087 | 1251 | } |
c6f1deb1 | 1252 | |
14c17463 | 1253 | return get_random_bytes_user(buf, nbytes); |
1da177e4 LT |
1254 | } |
1255 | ||
248045b8 JD |
1256 | static ssize_t random_read(struct file *file, char __user *buf, size_t nbytes, |
1257 | loff_t *ppos) | |
30c08efe AL |
1258 | { |
1259 | int ret; | |
1260 | ||
1261 | ret = wait_for_random_bytes(); | |
1262 | if (ret != 0) | |
1263 | return ret; | |
14c17463 | 1264 | return get_random_bytes_user(buf, nbytes); |
30c08efe AL |
1265 | } |
1266 | ||
248045b8 | 1267 | static __poll_t random_poll(struct file *file, poll_table *wait) |
1da177e4 | 1268 | { |
a11e1d43 | 1269 | __poll_t mask; |
1da177e4 | 1270 | |
30c08efe | 1271 | poll_wait(file, &crng_init_wait, wait); |
a11e1d43 LT |
1272 | poll_wait(file, &random_write_wait, wait); |
1273 | mask = 0; | |
30c08efe | 1274 | if (crng_ready()) |
a9a08845 | 1275 | mask |= EPOLLIN | EPOLLRDNORM; |
489c7fc4 | 1276 | if (input_pool.entropy_count < POOL_MIN_BITS) |
a9a08845 | 1277 | mask |= EPOLLOUT | EPOLLWRNORM; |
1da177e4 LT |
1278 | return mask; |
1279 | } | |
1280 | ||
04ec96b7 | 1281 | static int write_pool(const char __user *ubuf, size_t count) |
1da177e4 | 1282 | { |
04ec96b7 | 1283 | size_t len; |
7b5164fb | 1284 | int ret = 0; |
04ec96b7 | 1285 | u8 block[BLAKE2S_BLOCK_SIZE]; |
1da177e4 | 1286 | |
04ec96b7 JD |
1287 | while (count) { |
1288 | len = min(count, sizeof(block)); | |
7b5164fb JD |
1289 | if (copy_from_user(block, ubuf, len)) { |
1290 | ret = -EFAULT; | |
1291 | goto out; | |
1292 | } | |
04ec96b7 JD |
1293 | count -= len; |
1294 | ubuf += len; | |
1295 | mix_pool_bytes(block, len); | |
91f3f1e3 | 1296 | cond_resched(); |
1da177e4 | 1297 | } |
7f397dcd | 1298 | |
7b5164fb JD |
1299 | out: |
1300 | memzero_explicit(block, sizeof(block)); | |
1301 | return ret; | |
7f397dcd MM |
1302 | } |
1303 | ||
90b75ee5 MM |
1304 | static ssize_t random_write(struct file *file, const char __user *buffer, |
1305 | size_t count, loff_t *ppos) | |
7f397dcd | 1306 | { |
04ec96b7 | 1307 | int ret; |
7f397dcd | 1308 | |
90ed1e67 | 1309 | ret = write_pool(buffer, count); |
7f397dcd MM |
1310 | if (ret) |
1311 | return ret; | |
1312 | ||
7f397dcd | 1313 | return (ssize_t)count; |
1da177e4 LT |
1314 | } |
1315 | ||
43ae4860 | 1316 | static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) |
1da177e4 LT |
1317 | { |
1318 | int size, ent_count; | |
1319 | int __user *p = (int __user *)arg; | |
1320 | int retval; | |
1321 | ||
1322 | switch (cmd) { | |
1323 | case RNDGETENTCNT: | |
43ae4860 | 1324 | /* inherently racy, no point locking */ |
c5704490 | 1325 | if (put_user(input_pool.entropy_count, p)) |
1da177e4 LT |
1326 | return -EFAULT; |
1327 | return 0; | |
1328 | case RNDADDTOENTCNT: | |
1329 | if (!capable(CAP_SYS_ADMIN)) | |
1330 | return -EPERM; | |
1331 | if (get_user(ent_count, p)) | |
1332 | return -EFAULT; | |
a49c010e JD |
1333 | if (ent_count < 0) |
1334 | return -EINVAL; | |
1335 | credit_entropy_bits(ent_count); | |
1336 | return 0; | |
1da177e4 LT |
1337 | case RNDADDENTROPY: |
1338 | if (!capable(CAP_SYS_ADMIN)) | |
1339 | return -EPERM; | |
1340 | if (get_user(ent_count, p++)) | |
1341 | return -EFAULT; | |
1342 | if (ent_count < 0) | |
1343 | return -EINVAL; | |
1344 | if (get_user(size, p++)) | |
1345 | return -EFAULT; | |
90ed1e67 | 1346 | retval = write_pool((const char __user *)p, size); |
1da177e4 LT |
1347 | if (retval < 0) |
1348 | return retval; | |
a49c010e JD |
1349 | credit_entropy_bits(ent_count); |
1350 | return 0; | |
1da177e4 LT |
1351 | case RNDZAPENTCNT: |
1352 | case RNDCLEARPOOL: | |
ae9ecd92 TT |
1353 | /* |
1354 | * Clear the entropy pool counters. We no longer clear | |
1355 | * the entropy pool, as that's silly. | |
1356 | */ | |
1da177e4 LT |
1357 | if (!capable(CAP_SYS_ADMIN)) |
1358 | return -EPERM; | |
489c7fc4 | 1359 | if (xchg(&input_pool.entropy_count, 0)) { |
042e293e JD |
1360 | wake_up_interruptible(&random_write_wait); |
1361 | kill_fasync(&fasync, SIGIO, POLL_OUT); | |
1362 | } | |
1da177e4 | 1363 | return 0; |
d848e5f8 TT |
1364 | case RNDRESEEDCRNG: |
1365 | if (!capable(CAP_SYS_ADMIN)) | |
1366 | return -EPERM; | |
1367 | if (crng_init < 2) | |
1368 | return -ENODATA; | |
a9412d51 | 1369 | crng_reseed(); |
d848e5f8 | 1370 | return 0; |
1da177e4 LT |
1371 | default: |
1372 | return -EINVAL; | |
1373 | } | |
1374 | } | |
1375 | ||
9a6f70bb JD |
1376 | static int random_fasync(int fd, struct file *filp, int on) |
1377 | { | |
1378 | return fasync_helper(fd, filp, on, &fasync); | |
1379 | } | |
1380 | ||
2b8693c0 | 1381 | const struct file_operations random_fops = { |
248045b8 | 1382 | .read = random_read, |
1da177e4 | 1383 | .write = random_write, |
248045b8 | 1384 | .poll = random_poll, |
43ae4860 | 1385 | .unlocked_ioctl = random_ioctl, |
507e4e2b | 1386 | .compat_ioctl = compat_ptr_ioctl, |
9a6f70bb | 1387 | .fasync = random_fasync, |
6038f373 | 1388 | .llseek = noop_llseek, |
1da177e4 LT |
1389 | }; |
1390 | ||
2b8693c0 | 1391 | const struct file_operations urandom_fops = { |
248045b8 | 1392 | .read = urandom_read, |
1da177e4 | 1393 | .write = random_write, |
43ae4860 | 1394 | .unlocked_ioctl = random_ioctl, |
4aa37c46 | 1395 | .compat_ioctl = compat_ptr_ioctl, |
9a6f70bb | 1396 | .fasync = random_fasync, |
6038f373 | 1397 | .llseek = noop_llseek, |
1da177e4 LT |
1398 | }; |
1399 | ||
248045b8 JD |
1400 | SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int, |
1401 | flags) | |
c6e9d6f3 | 1402 | { |
248045b8 | 1403 | if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE)) |
75551dbf AL |
1404 | return -EINVAL; |
1405 | ||
1406 | /* | |
1407 | * Requesting insecure and blocking randomness at the same time makes | |
1408 | * no sense. | |
1409 | */ | |
248045b8 | 1410 | if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM)) |
c6e9d6f3 TT |
1411 | return -EINVAL; |
1412 | ||
1413 | if (count > INT_MAX) | |
1414 | count = INT_MAX; | |
1415 | ||
75551dbf | 1416 | if (!(flags & GRND_INSECURE) && !crng_ready()) { |
04ec96b7 JD |
1417 | int ret; |
1418 | ||
c6e9d6f3 TT |
1419 | if (flags & GRND_NONBLOCK) |
1420 | return -EAGAIN; | |
e297a783 JD |
1421 | ret = wait_for_random_bytes(); |
1422 | if (unlikely(ret)) | |
1423 | return ret; | |
c6e9d6f3 | 1424 | } |
14c17463 | 1425 | return get_random_bytes_user(buf, count); |
c6e9d6f3 TT |
1426 | } |
1427 | ||
1da177e4 LT |
1428 | /******************************************************************** |
1429 | * | |
1430 | * Sysctl interface | |
1431 | * | |
1432 | ********************************************************************/ | |
1433 | ||
1434 | #ifdef CONFIG_SYSCTL | |
1435 | ||
1436 | #include <linux/sysctl.h> | |
1437 | ||
db61ffe3 | 1438 | static int random_min_urandom_seed = 60; |
489c7fc4 JD |
1439 | static int random_write_wakeup_bits = POOL_MIN_BITS; |
1440 | static int sysctl_poolsize = POOL_BITS; | |
1da177e4 LT |
1441 | static char sysctl_bootid[16]; |
1442 | ||
1443 | /* | |
f22052b2 | 1444 | * This function is used to return both the bootid UUID, and random |
1da177e4 LT |
1445 | * UUID. The difference is in whether table->data is NULL; if it is, |
1446 | * then a new UUID is generated and returned to the user. | |
1447 | * | |
f22052b2 GP |
1448 | * If the user accesses this via the proc interface, the UUID will be |
1449 | * returned as an ASCII string in the standard UUID format; if via the | |
1450 | * sysctl system call, as 16 bytes of binary data. | |
1da177e4 | 1451 | */ |
248045b8 JD |
1452 | static int proc_do_uuid(struct ctl_table *table, int write, void *buffer, |
1453 | size_t *lenp, loff_t *ppos) | |
1da177e4 | 1454 | { |
a151427e | 1455 | struct ctl_table fake_table; |
1da177e4 LT |
1456 | unsigned char buf[64], tmp_uuid[16], *uuid; |
1457 | ||
1458 | uuid = table->data; | |
1459 | if (!uuid) { | |
1460 | uuid = tmp_uuid; | |
1da177e4 | 1461 | generate_random_uuid(uuid); |
44e4360f MD |
1462 | } else { |
1463 | static DEFINE_SPINLOCK(bootid_spinlock); | |
1464 | ||
1465 | spin_lock(&bootid_spinlock); | |
1466 | if (!uuid[8]) | |
1467 | generate_random_uuid(uuid); | |
1468 | spin_unlock(&bootid_spinlock); | |
1469 | } | |
1da177e4 | 1470 | |
35900771 JP |
1471 | sprintf(buf, "%pU", uuid); |
1472 | ||
1da177e4 LT |
1473 | fake_table.data = buf; |
1474 | fake_table.maxlen = sizeof(buf); | |
1475 | ||
8d65af78 | 1476 | return proc_dostring(&fake_table, write, buffer, lenp, ppos); |
1da177e4 LT |
1477 | } |
1478 | ||
5475e8f0 | 1479 | static struct ctl_table random_table[] = { |
1da177e4 | 1480 | { |
1da177e4 LT |
1481 | .procname = "poolsize", |
1482 | .data = &sysctl_poolsize, | |
1483 | .maxlen = sizeof(int), | |
1484 | .mode = 0444, | |
6d456111 | 1485 | .proc_handler = proc_dointvec, |
1da177e4 LT |
1486 | }, |
1487 | { | |
1da177e4 | 1488 | .procname = "entropy_avail", |
c5704490 | 1489 | .data = &input_pool.entropy_count, |
1da177e4 LT |
1490 | .maxlen = sizeof(int), |
1491 | .mode = 0444, | |
c5704490 | 1492 | .proc_handler = proc_dointvec, |
1da177e4 | 1493 | }, |
1da177e4 | 1494 | { |
1da177e4 | 1495 | .procname = "write_wakeup_threshold", |
2132a96f | 1496 | .data = &random_write_wakeup_bits, |
1da177e4 LT |
1497 | .maxlen = sizeof(int), |
1498 | .mode = 0644, | |
489c7fc4 | 1499 | .proc_handler = proc_dointvec, |
1da177e4 | 1500 | }, |
f5c2742c TT |
1501 | { |
1502 | .procname = "urandom_min_reseed_secs", | |
1503 | .data = &random_min_urandom_seed, | |
1504 | .maxlen = sizeof(int), | |
1505 | .mode = 0644, | |
1506 | .proc_handler = proc_dointvec, | |
1507 | }, | |
1da177e4 | 1508 | { |
1da177e4 LT |
1509 | .procname = "boot_id", |
1510 | .data = &sysctl_bootid, | |
1511 | .maxlen = 16, | |
1512 | .mode = 0444, | |
6d456111 | 1513 | .proc_handler = proc_do_uuid, |
1da177e4 LT |
1514 | }, |
1515 | { | |
1da177e4 LT |
1516 | .procname = "uuid", |
1517 | .maxlen = 16, | |
1518 | .mode = 0444, | |
6d456111 | 1519 | .proc_handler = proc_do_uuid, |
1da177e4 | 1520 | }, |
894d2491 | 1521 | { } |
1da177e4 | 1522 | }; |
5475e8f0 XN |
1523 | |
1524 | /* | |
1525 | * rand_initialize() is called before sysctl_init(), | |
1526 | * so we cannot call register_sysctl_init() in rand_initialize() | |
1527 | */ | |
1528 | static int __init random_sysctls_init(void) | |
1529 | { | |
1530 | register_sysctl_init("kernel/random", random_table); | |
1531 | return 0; | |
1532 | } | |
1533 | device_initcall(random_sysctls_init); | |
248045b8 | 1534 | #endif /* CONFIG_SYSCTL */ |
1da177e4 | 1535 | |
f5b98461 JD |
1536 | struct batched_entropy { |
1537 | union { | |
186873c5 JD |
1538 | /* |
1539 | * We make this 1.5x a ChaCha block, so that we get the | |
1540 | * remaining 32 bytes from fast key erasure, plus one full | |
1541 | * block from the detached ChaCha state. We can increase | |
1542 | * the size of this later if needed so long as we keep the | |
1543 | * formula of (integer_blocks + 0.5) * CHACHA_BLOCK_SIZE. | |
1544 | */ | |
1545 | u64 entropy_u64[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u64))]; | |
1546 | u32 entropy_u32[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u32))]; | |
f5b98461 | 1547 | }; |
77760fd7 | 1548 | local_lock_t lock; |
0791e8b6 | 1549 | unsigned long generation; |
f5b98461 JD |
1550 | unsigned int position; |
1551 | }; | |
b1132dea | 1552 | |
1da177e4 | 1553 | /* |
f5b98461 | 1554 | * Get a random word for internal kernel use only. The quality of the random |
186873c5 JD |
1555 | * number is good as /dev/urandom. In order to ensure that the randomness |
1556 | * provided by this function is okay, the function wait_for_random_bytes() | |
1557 | * should be called and return 0 at least once at any point prior. | |
1da177e4 | 1558 | */ |
b7d5dc21 | 1559 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = { |
186873c5 JD |
1560 | .lock = INIT_LOCAL_LOCK(batched_entropy_u64.lock), |
1561 | .position = UINT_MAX | |
b7d5dc21 SAS |
1562 | }; |
1563 | ||
c440408c | 1564 | u64 get_random_u64(void) |
1da177e4 | 1565 | { |
c440408c | 1566 | u64 ret; |
b7d5dc21 | 1567 | unsigned long flags; |
f5b98461 | 1568 | struct batched_entropy *batch; |
eecabf56 | 1569 | static void *previous; |
0791e8b6 | 1570 | unsigned long next_gen; |
8a0a9bd4 | 1571 | |
eecabf56 | 1572 | warn_unseeded_randomness(&previous); |
d06bfd19 | 1573 | |
77760fd7 | 1574 | local_lock_irqsave(&batched_entropy_u64.lock, flags); |
b7d5dc21 | 1575 | batch = raw_cpu_ptr(&batched_entropy_u64); |
77760fd7 | 1576 | |
0791e8b6 | 1577 | next_gen = READ_ONCE(base_crng.generation); |
186873c5 | 1578 | if (batch->position >= ARRAY_SIZE(batch->entropy_u64) || |
77760fd7 | 1579 | next_gen != batch->generation) { |
186873c5 | 1580 | _get_random_bytes(batch->entropy_u64, sizeof(batch->entropy_u64)); |
f5b98461 | 1581 | batch->position = 0; |
77760fd7 | 1582 | batch->generation = next_gen; |
f5b98461 | 1583 | } |
77760fd7 | 1584 | |
186873c5 JD |
1585 | ret = batch->entropy_u64[batch->position]; |
1586 | batch->entropy_u64[batch->position] = 0; | |
1587 | ++batch->position; | |
77760fd7 | 1588 | local_unlock_irqrestore(&batched_entropy_u64.lock, flags); |
8a0a9bd4 | 1589 | return ret; |
1da177e4 | 1590 | } |
c440408c | 1591 | EXPORT_SYMBOL(get_random_u64); |
1da177e4 | 1592 | |
b7d5dc21 | 1593 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = { |
186873c5 JD |
1594 | .lock = INIT_LOCAL_LOCK(batched_entropy_u32.lock), |
1595 | .position = UINT_MAX | |
b7d5dc21 | 1596 | }; |
77760fd7 | 1597 | |
c440408c | 1598 | u32 get_random_u32(void) |
f5b98461 | 1599 | { |
c440408c | 1600 | u32 ret; |
b7d5dc21 | 1601 | unsigned long flags; |
f5b98461 | 1602 | struct batched_entropy *batch; |
eecabf56 | 1603 | static void *previous; |
0791e8b6 | 1604 | unsigned long next_gen; |
ec9ee4ac | 1605 | |
eecabf56 | 1606 | warn_unseeded_randomness(&previous); |
d06bfd19 | 1607 | |
77760fd7 | 1608 | local_lock_irqsave(&batched_entropy_u32.lock, flags); |
b7d5dc21 | 1609 | batch = raw_cpu_ptr(&batched_entropy_u32); |
77760fd7 | 1610 | |
0791e8b6 | 1611 | next_gen = READ_ONCE(base_crng.generation); |
186873c5 | 1612 | if (batch->position >= ARRAY_SIZE(batch->entropy_u32) || |
77760fd7 | 1613 | next_gen != batch->generation) { |
186873c5 | 1614 | _get_random_bytes(batch->entropy_u32, sizeof(batch->entropy_u32)); |
f5b98461 | 1615 | batch->position = 0; |
77760fd7 | 1616 | batch->generation = next_gen; |
f5b98461 | 1617 | } |
77760fd7 | 1618 | |
186873c5 JD |
1619 | ret = batch->entropy_u32[batch->position]; |
1620 | batch->entropy_u32[batch->position] = 0; | |
1621 | ++batch->position; | |
77760fd7 | 1622 | local_unlock_irqrestore(&batched_entropy_u32.lock, flags); |
ec9ee4ac DC |
1623 | return ret; |
1624 | } | |
c440408c | 1625 | EXPORT_SYMBOL(get_random_u32); |
ec9ee4ac | 1626 | |
99fdafde JC |
1627 | /** |
1628 | * randomize_page - Generate a random, page aligned address | |
1629 | * @start: The smallest acceptable address the caller will take. | |
1630 | * @range: The size of the area, starting at @start, within which the | |
1631 | * random address must fall. | |
1632 | * | |
1633 | * If @start + @range would overflow, @range is capped. | |
1634 | * | |
1635 | * NOTE: Historical use of randomize_range, which this replaces, presumed that | |
1636 | * @start was already page aligned. We now align it regardless. | |
1637 | * | |
1638 | * Return: A page aligned address within [start, start + range). On error, | |
1639 | * @start is returned. | |
1640 | */ | |
248045b8 | 1641 | unsigned long randomize_page(unsigned long start, unsigned long range) |
99fdafde JC |
1642 | { |
1643 | if (!PAGE_ALIGNED(start)) { | |
1644 | range -= PAGE_ALIGN(start) - start; | |
1645 | start = PAGE_ALIGN(start); | |
1646 | } | |
1647 | ||
1648 | if (start > ULONG_MAX - range) | |
1649 | range = ULONG_MAX - start; | |
1650 | ||
1651 | range >>= PAGE_SHIFT; | |
1652 | ||
1653 | if (range == 0) | |
1654 | return start; | |
1655 | ||
1656 | return start + (get_random_long() % range << PAGE_SHIFT); | |
1657 | } | |
1658 | ||
c84dbf61 TD |
1659 | /* Interface for in-kernel drivers of true hardware RNGs. |
1660 | * Those devices may produce endless random bits and will be throttled | |
1661 | * when our pool is full. | |
1662 | */ | |
04ec96b7 | 1663 | void add_hwgenerator_randomness(const void *buffer, size_t count, |
c84dbf61 TD |
1664 | size_t entropy) |
1665 | { | |
43838a23 | 1666 | if (unlikely(crng_init == 0)) { |
73c7733f | 1667 | size_t ret = crng_fast_load(buffer, count); |
90ed1e67 | 1668 | mix_pool_bytes(buffer, ret); |
73c7733f JD |
1669 | count -= ret; |
1670 | buffer += ret; | |
1671 | if (!count || crng_init == 0) | |
1672 | return; | |
3371f3da | 1673 | } |
e192be9d | 1674 | |
c321e907 | 1675 | /* Throttle writing if we're above the trickle threshold. |
489c7fc4 JD |
1676 | * We'll be woken up again once below POOL_MIN_BITS, when |
1677 | * the calling thread is about to terminate, or once | |
1678 | * CRNG_RESEED_INTERVAL has elapsed. | |
e192be9d | 1679 | */ |
c321e907 | 1680 | wait_event_interruptible_timeout(random_write_wait, |
f7e67b8e | 1681 | !system_wq || kthread_should_stop() || |
489c7fc4 | 1682 | input_pool.entropy_count < POOL_MIN_BITS, |
c321e907 | 1683 | CRNG_RESEED_INTERVAL); |
90ed1e67 JD |
1684 | mix_pool_bytes(buffer, count); |
1685 | credit_entropy_bits(entropy); | |
c84dbf61 TD |
1686 | } |
1687 | EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); | |
428826f5 HYW |
1688 | |
1689 | /* Handle random seed passed by bootloader. | |
1690 | * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise | |
1691 | * it would be regarded as device data. | |
1692 | * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER. | |
1693 | */ | |
04ec96b7 | 1694 | void add_bootloader_randomness(const void *buf, size_t size) |
428826f5 HYW |
1695 | { |
1696 | if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER)) | |
1697 | add_hwgenerator_randomness(buf, size, size * 8); | |
1698 | else | |
1699 | add_device_randomness(buf, size); | |
1700 | } | |
3fd57e7a | 1701 | EXPORT_SYMBOL_GPL(add_bootloader_randomness); |