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1da177e4 LT |
1 | /* |
2 | * random.c -- A strong random number generator | |
3 | * | |
9f9eff85 | 4 | * Copyright (C) 2017-2022 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. |
b169c13d | 5 | * |
9e95ce27 | 6 | * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005 |
1da177e4 LT |
7 | * |
8 | * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All | |
9 | * rights reserved. | |
10 | * | |
11 | * Redistribution and use in source and binary forms, with or without | |
12 | * modification, are permitted provided that the following conditions | |
13 | * are met: | |
14 | * 1. Redistributions of source code must retain the above copyright | |
15 | * notice, and the entire permission notice in its entirety, | |
16 | * including the disclaimer of warranties. | |
17 | * 2. Redistributions in binary form must reproduce the above copyright | |
18 | * notice, this list of conditions and the following disclaimer in the | |
19 | * documentation and/or other materials provided with the distribution. | |
20 | * 3. The name of the author may not be used to endorse or promote | |
21 | * products derived from this software without specific prior | |
22 | * written permission. | |
23 | * | |
24 | * ALTERNATIVELY, this product may be distributed under the terms of | |
25 | * the GNU General Public License, in which case the provisions of the GPL are | |
26 | * required INSTEAD OF the above restrictions. (This clause is | |
27 | * necessary due to a potential bad interaction between the GPL and | |
28 | * the restrictions contained in a BSD-style copyright.) | |
29 | * | |
30 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED | |
31 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
32 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF | |
33 | * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE | |
34 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | |
35 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT | |
36 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR | |
37 | * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF | |
38 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
39 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE | |
40 | * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH | |
41 | * DAMAGE. | |
42 | */ | |
43 | ||
44 | /* | |
1da177e4 LT |
45 | * Exported interfaces ---- output |
46 | * =============================== | |
47 | * | |
92e507d2 | 48 | * There are four exported interfaces; two for use within the kernel, |
c0a8a61e | 49 | * and two for use from userspace. |
1da177e4 | 50 | * |
92e507d2 GS |
51 | * Exported interfaces ---- userspace output |
52 | * ----------------------------------------- | |
1da177e4 | 53 | * |
92e507d2 | 54 | * The userspace interfaces are two character devices /dev/random and |
1da177e4 LT |
55 | * /dev/urandom. /dev/random is suitable for use when very high |
56 | * quality randomness is desired (for example, for key generation or | |
57 | * one-time pads), as it will only return a maximum of the number of | |
58 | * bits of randomness (as estimated by the random number generator) | |
59 | * contained in the entropy pool. | |
60 | * | |
61 | * The /dev/urandom device does not have this limit, and will return | |
62 | * as many bytes as are requested. As more and more random bytes are | |
63 | * requested without giving time for the entropy pool to recharge, | |
64 | * this will result in random numbers that are merely cryptographically | |
65 | * strong. For many applications, however, this is acceptable. | |
66 | * | |
92e507d2 GS |
67 | * Exported interfaces ---- kernel output |
68 | * -------------------------------------- | |
69 | * | |
70 | * The primary kernel interface is | |
71 | * | |
248045b8 | 72 | * void get_random_bytes(void *buf, int nbytes); |
92e507d2 GS |
73 | * |
74 | * This interface will return the requested number of random bytes, | |
75 | * and place it in the requested buffer. This is equivalent to a | |
76 | * read from /dev/urandom. | |
77 | * | |
78 | * For less critical applications, there are the functions: | |
79 | * | |
248045b8 JD |
80 | * u32 get_random_u32() |
81 | * u64 get_random_u64() | |
82 | * unsigned int get_random_int() | |
83 | * unsigned long get_random_long() | |
92e507d2 GS |
84 | * |
85 | * These are produced by a cryptographic RNG seeded from get_random_bytes, | |
86 | * and so do not deplete the entropy pool as much. These are recommended | |
87 | * for most in-kernel operations *if the result is going to be stored in | |
88 | * the kernel*. | |
89 | * | |
90 | * Specifically, the get_random_int() family do not attempt to do | |
91 | * "anti-backtracking". If you capture the state of the kernel (e.g. | |
92 | * by snapshotting the VM), you can figure out previous get_random_int() | |
93 | * return values. But if the value is stored in the kernel anyway, | |
94 | * this is not a problem. | |
95 | * | |
96 | * It *is* safe to expose get_random_int() output to attackers (e.g. as | |
97 | * network cookies); given outputs 1..n, it's not feasible to predict | |
98 | * outputs 0 or n+1. The only concern is an attacker who breaks into | |
99 | * the kernel later; the get_random_int() engine is not reseeded as | |
100 | * often as the get_random_bytes() one. | |
101 | * | |
102 | * get_random_bytes() is needed for keys that need to stay secret after | |
103 | * they are erased from the kernel. For example, any key that will | |
104 | * be wrapped and stored encrypted. And session encryption keys: we'd | |
105 | * like to know that after the session is closed and the keys erased, | |
106 | * the plaintext is unrecoverable to someone who recorded the ciphertext. | |
107 | * | |
108 | * But for network ports/cookies, stack canaries, PRNG seeds, address | |
109 | * space layout randomization, session *authentication* keys, or other | |
110 | * applications where the sensitive data is stored in the kernel in | |
111 | * plaintext for as long as it's sensitive, the get_random_int() family | |
112 | * is just fine. | |
113 | * | |
114 | * Consider ASLR. We want to keep the address space secret from an | |
115 | * outside attacker while the process is running, but once the address | |
116 | * space is torn down, it's of no use to an attacker any more. And it's | |
117 | * stored in kernel data structures as long as it's alive, so worrying | |
118 | * about an attacker's ability to extrapolate it from the get_random_int() | |
119 | * CRNG is silly. | |
120 | * | |
121 | * Even some cryptographic keys are safe to generate with get_random_int(). | |
122 | * In particular, keys for SipHash are generally fine. Here, knowledge | |
123 | * of the key authorizes you to do something to a kernel object (inject | |
124 | * packets to a network connection, or flood a hash table), and the | |
125 | * key is stored with the object being protected. Once it goes away, | |
126 | * we no longer care if anyone knows the key. | |
127 | * | |
128 | * prandom_u32() | |
129 | * ------------- | |
130 | * | |
131 | * For even weaker applications, see the pseudorandom generator | |
132 | * prandom_u32(), prandom_max(), and prandom_bytes(). If the random | |
133 | * numbers aren't security-critical at all, these are *far* cheaper. | |
134 | * Useful for self-tests, random error simulation, randomized backoffs, | |
135 | * and any other application where you trust that nobody is trying to | |
136 | * maliciously mess with you by guessing the "random" numbers. | |
137 | * | |
1da177e4 LT |
138 | * Exported interfaces ---- input |
139 | * ============================== | |
140 | * | |
141 | * The current exported interfaces for gathering environmental noise | |
142 | * from the devices are: | |
143 | * | |
a2080a67 | 144 | * void add_device_randomness(const void *buf, unsigned int size); |
248045b8 | 145 | * void add_input_randomness(unsigned int type, unsigned int code, |
1da177e4 | 146 | * unsigned int value); |
703f7066 | 147 | * void add_interrupt_randomness(int irq); |
248045b8 | 148 | * void add_disk_randomness(struct gendisk *disk); |
2b6c6e3d MB |
149 | * void add_hwgenerator_randomness(const char *buffer, size_t count, |
150 | * size_t entropy); | |
151 | * void add_bootloader_randomness(const void *buf, unsigned int size); | |
1da177e4 | 152 | * |
a2080a67 LT |
153 | * add_device_randomness() is for adding data to the random pool that |
154 | * is likely to differ between two devices (or possibly even per boot). | |
155 | * This would be things like MAC addresses or serial numbers, or the | |
156 | * read-out of the RTC. This does *not* add any actual entropy to the | |
157 | * pool, but it initializes the pool to different values for devices | |
158 | * that might otherwise be identical and have very little entropy | |
159 | * available to them (particularly common in the embedded world). | |
160 | * | |
1da177e4 LT |
161 | * add_input_randomness() uses the input layer interrupt timing, as well as |
162 | * the event type information from the hardware. | |
163 | * | |
775f4b29 TT |
164 | * add_interrupt_randomness() uses the interrupt timing as random |
165 | * inputs to the entropy pool. Using the cycle counters and the irq source | |
166 | * as inputs, it feeds the randomness roughly once a second. | |
442a4fff JW |
167 | * |
168 | * add_disk_randomness() uses what amounts to the seek time of block | |
169 | * layer request events, on a per-disk_devt basis, as input to the | |
170 | * entropy pool. Note that high-speed solid state drives with very low | |
171 | * seek times do not make for good sources of entropy, as their seek | |
172 | * times are usually fairly consistent. | |
1da177e4 LT |
173 | * |
174 | * All of these routines try to estimate how many bits of randomness a | |
175 | * particular randomness source. They do this by keeping track of the | |
176 | * first and second order deltas of the event timings. | |
177 | * | |
2b6c6e3d MB |
178 | * add_hwgenerator_randomness() is for true hardware RNGs, and will credit |
179 | * entropy as specified by the caller. If the entropy pool is full it will | |
180 | * block until more entropy is needed. | |
181 | * | |
182 | * add_bootloader_randomness() is the same as add_hwgenerator_randomness() or | |
183 | * add_device_randomness(), depending on whether or not the configuration | |
184 | * option CONFIG_RANDOM_TRUST_BOOTLOADER is set. | |
185 | * | |
1da177e4 LT |
186 | * Ensuring unpredictability at system startup |
187 | * ============================================ | |
188 | * | |
189 | * When any operating system starts up, it will go through a sequence | |
190 | * of actions that are fairly predictable by an adversary, especially | |
191 | * if the start-up does not involve interaction with a human operator. | |
192 | * This reduces the actual number of bits of unpredictability in the | |
193 | * entropy pool below the value in entropy_count. In order to | |
194 | * counteract this effect, it helps to carry information in the | |
195 | * entropy pool across shut-downs and start-ups. To do this, put the | |
196 | * following lines an appropriate script which is run during the boot | |
197 | * sequence: | |
198 | * | |
199 | * echo "Initializing random number generator..." | |
200 | * random_seed=/var/run/random-seed | |
201 | * # Carry a random seed from start-up to start-up | |
202 | * # Load and then save the whole entropy pool | |
203 | * if [ -f $random_seed ]; then | |
204 | * cat $random_seed >/dev/urandom | |
205 | * else | |
206 | * touch $random_seed | |
207 | * fi | |
208 | * chmod 600 $random_seed | |
209 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 | |
210 | * | |
211 | * and the following lines in an appropriate script which is run as | |
212 | * the system is shutdown: | |
213 | * | |
214 | * # Carry a random seed from shut-down to start-up | |
215 | * # Save the whole entropy pool | |
216 | * echo "Saving random seed..." | |
217 | * random_seed=/var/run/random-seed | |
218 | * touch $random_seed | |
219 | * chmod 600 $random_seed | |
220 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 | |
221 | * | |
222 | * For example, on most modern systems using the System V init | |
223 | * scripts, such code fragments would be found in | |
224 | * /etc/rc.d/init.d/random. On older Linux systems, the correct script | |
225 | * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0. | |
226 | * | |
227 | * Effectively, these commands cause the contents of the entropy pool | |
228 | * to be saved at shut-down time and reloaded into the entropy pool at | |
229 | * start-up. (The 'dd' in the addition to the bootup script is to | |
230 | * make sure that /etc/random-seed is different for every start-up, | |
231 | * even if the system crashes without executing rc.0.) Even with | |
232 | * complete knowledge of the start-up activities, predicting the state | |
233 | * of the entropy pool requires knowledge of the previous history of | |
234 | * the system. | |
235 | * | |
236 | * Configuring the /dev/random driver under Linux | |
237 | * ============================================== | |
238 | * | |
239 | * The /dev/random driver under Linux uses minor numbers 8 and 9 of | |
240 | * the /dev/mem major number (#1). So if your system does not have | |
241 | * /dev/random and /dev/urandom created already, they can be created | |
242 | * by using the commands: | |
243 | * | |
248045b8 JD |
244 | * mknod /dev/random c 1 8 |
245 | * mknod /dev/urandom c 1 9 | |
1da177e4 LT |
246 | */ |
247 | ||
12cd53af YL |
248 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
249 | ||
1da177e4 | 250 | #include <linux/utsname.h> |
1da177e4 LT |
251 | #include <linux/module.h> |
252 | #include <linux/kernel.h> | |
253 | #include <linux/major.h> | |
254 | #include <linux/string.h> | |
255 | #include <linux/fcntl.h> | |
256 | #include <linux/slab.h> | |
257 | #include <linux/random.h> | |
258 | #include <linux/poll.h> | |
259 | #include <linux/init.h> | |
260 | #include <linux/fs.h> | |
261 | #include <linux/genhd.h> | |
262 | #include <linux/interrupt.h> | |
27ac792c | 263 | #include <linux/mm.h> |
dd0f0cf5 | 264 | #include <linux/nodemask.h> |
1da177e4 | 265 | #include <linux/spinlock.h> |
c84dbf61 | 266 | #include <linux/kthread.h> |
1da177e4 | 267 | #include <linux/percpu.h> |
775f4b29 | 268 | #include <linux/ptrace.h> |
6265e169 | 269 | #include <linux/workqueue.h> |
0244ad00 | 270 | #include <linux/irq.h> |
4e00b339 | 271 | #include <linux/ratelimit.h> |
c6e9d6f3 TT |
272 | #include <linux/syscalls.h> |
273 | #include <linux/completion.h> | |
8da4b8c4 | 274 | #include <linux/uuid.h> |
1ca1b917 | 275 | #include <crypto/chacha.h> |
9f9eff85 | 276 | #include <crypto/blake2s.h> |
d178a1eb | 277 | |
1da177e4 | 278 | #include <asm/processor.h> |
7c0f6ba6 | 279 | #include <linux/uaccess.h> |
1da177e4 | 280 | #include <asm/irq.h> |
775f4b29 | 281 | #include <asm/irq_regs.h> |
1da177e4 LT |
282 | #include <asm/io.h> |
283 | ||
00ce1db1 TT |
284 | #define CREATE_TRACE_POINTS |
285 | #include <trace/events/random.h> | |
286 | ||
43759d4f TT |
287 | /* #define ADD_INTERRUPT_BENCH */ |
288 | ||
c5704490 | 289 | enum { |
6e8ec255 | 290 | POOL_BITS = BLAKE2S_HASH_SIZE * 8, |
c5704490 | 291 | POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */ |
1da177e4 LT |
292 | }; |
293 | ||
1da177e4 LT |
294 | /* |
295 | * Static global variables | |
296 | */ | |
a11e1d43 | 297 | static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); |
9a6f70bb | 298 | static struct fasync_struct *fasync; |
1da177e4 | 299 | |
205a525c HX |
300 | static DEFINE_SPINLOCK(random_ready_list_lock); |
301 | static LIST_HEAD(random_ready_list); | |
302 | ||
e192be9d | 303 | struct crng_state { |
248045b8 JD |
304 | u32 state[16]; |
305 | unsigned long init_time; | |
306 | spinlock_t lock; | |
e192be9d TT |
307 | }; |
308 | ||
764ed189 | 309 | static struct crng_state primary_crng = { |
e192be9d | 310 | .lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock), |
96562f28 DB |
311 | .state[0] = CHACHA_CONSTANT_EXPA, |
312 | .state[1] = CHACHA_CONSTANT_ND_3, | |
313 | .state[2] = CHACHA_CONSTANT_2_BY, | |
314 | .state[3] = CHACHA_CONSTANT_TE_K, | |
e192be9d TT |
315 | }; |
316 | ||
317 | /* | |
318 | * crng_init = 0 --> Uninitialized | |
319 | * 1 --> Initialized | |
320 | * 2 --> Initialized from input_pool | |
321 | * | |
322 | * crng_init is protected by primary_crng->lock, and only increases | |
323 | * its value (from 0->1->2). | |
324 | */ | |
325 | static int crng_init = 0; | |
f7e67b8e | 326 | static bool crng_need_final_init = false; |
43838a23 | 327 | #define crng_ready() (likely(crng_init > 1)) |
e192be9d | 328 | static int crng_init_cnt = 0; |
d848e5f8 | 329 | static unsigned long crng_global_init_time = 0; |
248045b8 | 330 | #define CRNG_INIT_CNT_THRESH (2 * CHACHA_KEY_SIZE) |
d38bb085 | 331 | static void _extract_crng(struct crng_state *crng, u8 out[CHACHA_BLOCK_SIZE]); |
c92e040d | 332 | static void _crng_backtrack_protect(struct crng_state *crng, |
d38bb085 | 333 | u8 tmp[CHACHA_BLOCK_SIZE], int used); |
e192be9d | 334 | static void process_random_ready_list(void); |
eecabf56 | 335 | static void _get_random_bytes(void *buf, int nbytes); |
e192be9d | 336 | |
4e00b339 TT |
337 | static struct ratelimit_state unseeded_warning = |
338 | RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3); | |
339 | static struct ratelimit_state urandom_warning = | |
340 | RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3); | |
341 | ||
342 | static int ratelimit_disable __read_mostly; | |
343 | ||
344 | module_param_named(ratelimit_disable, ratelimit_disable, int, 0644); | |
345 | MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression"); | |
346 | ||
1da177e4 LT |
347 | /********************************************************************** |
348 | * | |
349 | * OS independent entropy store. Here are the functions which handle | |
350 | * storing entropy in an entropy pool. | |
351 | * | |
352 | **********************************************************************/ | |
353 | ||
90ed1e67 | 354 | static struct { |
6e8ec255 | 355 | struct blake2s_state hash; |
43358209 | 356 | spinlock_t lock; |
cda796a3 | 357 | int entropy_count; |
90ed1e67 | 358 | } input_pool = { |
6e8ec255 JD |
359 | .hash.h = { BLAKE2S_IV0 ^ (0x01010000 | BLAKE2S_HASH_SIZE), |
360 | BLAKE2S_IV1, BLAKE2S_IV2, BLAKE2S_IV3, BLAKE2S_IV4, | |
361 | BLAKE2S_IV5, BLAKE2S_IV6, BLAKE2S_IV7 }, | |
362 | .hash.outlen = BLAKE2S_HASH_SIZE, | |
eece09ec | 363 | .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock), |
1da177e4 LT |
364 | }; |
365 | ||
9c07f578 | 366 | static void extract_entropy(void *buf, size_t nbytes); |
90ed1e67 JD |
367 | |
368 | static void crng_reseed(struct crng_state *crng, bool use_input_pool); | |
369 | ||
1da177e4 | 370 | /* |
e68e5b66 | 371 | * This function adds bytes into the entropy "pool". It does not |
1da177e4 | 372 | * update the entropy estimate. The caller should call |
adc782da | 373 | * credit_entropy_bits if this is appropriate. |
1da177e4 | 374 | */ |
90ed1e67 | 375 | static void _mix_pool_bytes(const void *in, int nbytes) |
1da177e4 | 376 | { |
6e8ec255 | 377 | blake2s_update(&input_pool.hash, in, nbytes); |
1da177e4 LT |
378 | } |
379 | ||
90ed1e67 | 380 | static void __mix_pool_bytes(const void *in, int nbytes) |
00ce1db1 | 381 | { |
90ed1e67 JD |
382 | trace_mix_pool_bytes_nolock(nbytes, _RET_IP_); |
383 | _mix_pool_bytes(in, nbytes); | |
00ce1db1 TT |
384 | } |
385 | ||
90ed1e67 | 386 | static void mix_pool_bytes(const void *in, int nbytes) |
1da177e4 | 387 | { |
902c098a TT |
388 | unsigned long flags; |
389 | ||
90ed1e67 JD |
390 | trace_mix_pool_bytes(nbytes, _RET_IP_); |
391 | spin_lock_irqsave(&input_pool.lock, flags); | |
392 | _mix_pool_bytes(in, nbytes); | |
393 | spin_unlock_irqrestore(&input_pool.lock, flags); | |
1da177e4 LT |
394 | } |
395 | ||
775f4b29 | 396 | struct fast_pool { |
248045b8 JD |
397 | u32 pool[4]; |
398 | unsigned long last; | |
399 | u16 reg_idx; | |
400 | u8 count; | |
775f4b29 TT |
401 | }; |
402 | ||
403 | /* | |
404 | * This is a fast mixing routine used by the interrupt randomness | |
405 | * collector. It's hardcoded for an 128 bit pool and assumes that any | |
406 | * locks that might be needed are taken by the caller. | |
407 | */ | |
43759d4f | 408 | static void fast_mix(struct fast_pool *f) |
775f4b29 | 409 | { |
d38bb085 JD |
410 | u32 a = f->pool[0], b = f->pool[1]; |
411 | u32 c = f->pool[2], d = f->pool[3]; | |
43759d4f TT |
412 | |
413 | a += b; c += d; | |
19acc77a | 414 | b = rol32(b, 6); d = rol32(d, 27); |
43759d4f TT |
415 | d ^= a; b ^= c; |
416 | ||
417 | a += b; c += d; | |
19acc77a | 418 | b = rol32(b, 16); d = rol32(d, 14); |
43759d4f TT |
419 | d ^= a; b ^= c; |
420 | ||
421 | a += b; c += d; | |
19acc77a | 422 | b = rol32(b, 6); d = rol32(d, 27); |
43759d4f TT |
423 | d ^= a; b ^= c; |
424 | ||
425 | a += b; c += d; | |
19acc77a | 426 | b = rol32(b, 16); d = rol32(d, 14); |
43759d4f TT |
427 | d ^= a; b ^= c; |
428 | ||
429 | f->pool[0] = a; f->pool[1] = b; | |
430 | f->pool[2] = c; f->pool[3] = d; | |
655b2264 | 431 | f->count++; |
775f4b29 TT |
432 | } |
433 | ||
205a525c HX |
434 | static void process_random_ready_list(void) |
435 | { | |
436 | unsigned long flags; | |
437 | struct random_ready_callback *rdy, *tmp; | |
438 | ||
439 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
440 | list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) { | |
441 | struct module *owner = rdy->owner; | |
442 | ||
443 | list_del_init(&rdy->list); | |
444 | rdy->func(rdy); | |
445 | module_put(owner); | |
446 | } | |
447 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
448 | } | |
449 | ||
1da177e4 | 450 | /* |
a283b5c4 PA |
451 | * Credit (or debit) the entropy store with n bits of entropy. |
452 | * Use credit_entropy_bits_safe() if the value comes from userspace | |
453 | * or otherwise should be checked for extreme values. | |
1da177e4 | 454 | */ |
90ed1e67 | 455 | static void credit_entropy_bits(int nbits) |
1da177e4 | 456 | { |
9c07f578 | 457 | int entropy_count, orig; |
18263c4e | 458 | |
adc782da MM |
459 | if (!nbits) |
460 | return; | |
461 | ||
c5704490 JD |
462 | do { |
463 | orig = READ_ONCE(input_pool.entropy_count); | |
464 | entropy_count = min(POOL_BITS, orig + nbits); | |
465 | } while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig); | |
1da177e4 | 466 | |
c5704490 | 467 | trace_credit_entropy_bits(nbits, entropy_count, _RET_IP_); |
00ce1db1 | 468 | |
c5704490 | 469 | if (crng_init < 2 && entropy_count >= POOL_MIN_BITS) |
90ed1e67 | 470 | crng_reseed(&primary_crng, true); |
1da177e4 LT |
471 | } |
472 | ||
90ed1e67 | 473 | static int credit_entropy_bits_safe(int nbits) |
a283b5c4 | 474 | { |
86a574de TT |
475 | if (nbits < 0) |
476 | return -EINVAL; | |
477 | ||
a283b5c4 | 478 | /* Cap the value to avoid overflows */ |
248045b8 | 479 | nbits = min(nbits, POOL_BITS); |
a283b5c4 | 480 | |
90ed1e67 | 481 | credit_entropy_bits(nbits); |
86a574de | 482 | return 0; |
a283b5c4 PA |
483 | } |
484 | ||
e192be9d TT |
485 | /********************************************************************* |
486 | * | |
487 | * CRNG using CHACHA20 | |
488 | * | |
489 | *********************************************************************/ | |
490 | ||
248045b8 | 491 | #define CRNG_RESEED_INTERVAL (300 * HZ) |
e192be9d TT |
492 | |
493 | static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); | |
494 | ||
1e7f583a TT |
495 | /* |
496 | * Hack to deal with crazy userspace progams when they are all trying | |
497 | * to access /dev/urandom in parallel. The programs are almost | |
498 | * certainly doing something terribly wrong, but we'll work around | |
499 | * their brain damage. | |
500 | */ | |
501 | static struct crng_state **crng_node_pool __read_mostly; | |
1e7f583a | 502 | |
b169c13d | 503 | static void invalidate_batched_entropy(void); |
fe6f1a6a | 504 | static void numa_crng_init(void); |
b169c13d | 505 | |
9b254366 KC |
506 | static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU); |
507 | static int __init parse_trust_cpu(char *arg) | |
508 | { | |
509 | return kstrtobool(arg, &trust_cpu); | |
510 | } | |
511 | early_param("random.trust_cpu", parse_trust_cpu); | |
512 | ||
5cbe0f13 | 513 | static bool crng_init_try_arch(struct crng_state *crng) |
e192be9d | 514 | { |
248045b8 JD |
515 | int i; |
516 | bool arch_init = true; | |
517 | unsigned long rv; | |
e192be9d | 518 | |
e192be9d TT |
519 | for (i = 4; i < 16; i++) { |
520 | if (!arch_get_random_seed_long(&rv) && | |
39a8883a | 521 | !arch_get_random_long(&rv)) { |
e192be9d | 522 | rv = random_get_entropy(); |
5cbe0f13 | 523 | arch_init = false; |
39a8883a | 524 | } |
e192be9d TT |
525 | crng->state[i] ^= rv; |
526 | } | |
5cbe0f13 MR |
527 | |
528 | return arch_init; | |
529 | } | |
530 | ||
ebf76063 | 531 | static bool __init crng_init_try_arch_early(void) |
253d3194 | 532 | { |
248045b8 JD |
533 | int i; |
534 | bool arch_init = true; | |
535 | unsigned long rv; | |
253d3194 MR |
536 | |
537 | for (i = 4; i < 16; i++) { | |
538 | if (!arch_get_random_seed_long_early(&rv) && | |
539 | !arch_get_random_long_early(&rv)) { | |
540 | rv = random_get_entropy(); | |
541 | arch_init = false; | |
542 | } | |
ebf76063 | 543 | primary_crng.state[i] ^= rv; |
253d3194 MR |
544 | } |
545 | ||
546 | return arch_init; | |
547 | } | |
548 | ||
7b873241 | 549 | static void crng_initialize_secondary(struct crng_state *crng) |
5cbe0f13 | 550 | { |
a181e0fd | 551 | chacha_init_consts(crng->state); |
d38bb085 | 552 | _get_random_bytes(&crng->state[4], sizeof(u32) * 12); |
5cbe0f13 MR |
553 | crng_init_try_arch(crng); |
554 | crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1; | |
555 | } | |
556 | ||
ebf76063 | 557 | static void __init crng_initialize_primary(void) |
5cbe0f13 | 558 | { |
9c07f578 | 559 | extract_entropy(&primary_crng.state[4], sizeof(u32) * 12); |
ebf76063 | 560 | if (crng_init_try_arch_early() && trust_cpu && crng_init < 2) { |
fe6f1a6a JD |
561 | invalidate_batched_entropy(); |
562 | numa_crng_init(); | |
39a8883a | 563 | crng_init = 2; |
161212c7 | 564 | pr_notice("crng init done (trusting CPU's manufacturer)\n"); |
39a8883a | 565 | } |
ebf76063 | 566 | primary_crng.init_time = jiffies - CRNG_RESEED_INTERVAL - 1; |
e192be9d TT |
567 | } |
568 | ||
9d5505f1 | 569 | static void crng_finalize_init(void) |
f7e67b8e | 570 | { |
f7e67b8e DB |
571 | if (!system_wq) { |
572 | /* We can't call numa_crng_init until we have workqueues, | |
573 | * so mark this for processing later. */ | |
574 | crng_need_final_init = true; | |
575 | return; | |
576 | } | |
577 | ||
578 | invalidate_batched_entropy(); | |
579 | numa_crng_init(); | |
580 | crng_init = 2; | |
9d5505f1 | 581 | crng_need_final_init = false; |
f7e67b8e DB |
582 | process_random_ready_list(); |
583 | wake_up_interruptible(&crng_init_wait); | |
584 | kill_fasync(&fasync, SIGIO, POLL_IN); | |
585 | pr_notice("crng init done\n"); | |
586 | if (unseeded_warning.missed) { | |
587 | pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n", | |
588 | unseeded_warning.missed); | |
589 | unseeded_warning.missed = 0; | |
590 | } | |
591 | if (urandom_warning.missed) { | |
592 | pr_notice("%d urandom warning(s) missed due to ratelimiting\n", | |
593 | urandom_warning.missed); | |
594 | urandom_warning.missed = 0; | |
595 | } | |
596 | } | |
597 | ||
6c1e851c | 598 | static void do_numa_crng_init(struct work_struct *work) |
8ef35c86 TT |
599 | { |
600 | int i; | |
601 | struct crng_state *crng; | |
602 | struct crng_state **pool; | |
603 | ||
248045b8 | 604 | pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL | __GFP_NOFAIL); |
8ef35c86 TT |
605 | for_each_online_node(i) { |
606 | crng = kmalloc_node(sizeof(struct crng_state), | |
607 | GFP_KERNEL | __GFP_NOFAIL, i); | |
608 | spin_lock_init(&crng->lock); | |
5cbe0f13 | 609 | crng_initialize_secondary(crng); |
8ef35c86 TT |
610 | pool[i] = crng; |
611 | } | |
5d73d1e3 EB |
612 | /* pairs with READ_ONCE() in select_crng() */ |
613 | if (cmpxchg_release(&crng_node_pool, NULL, pool) != NULL) { | |
8ef35c86 TT |
614 | for_each_node(i) |
615 | kfree(pool[i]); | |
616 | kfree(pool); | |
617 | } | |
618 | } | |
6c1e851c TT |
619 | |
620 | static DECLARE_WORK(numa_crng_init_work, do_numa_crng_init); | |
621 | ||
622 | static void numa_crng_init(void) | |
623 | { | |
7b873241 JD |
624 | if (IS_ENABLED(CONFIG_NUMA)) |
625 | schedule_work(&numa_crng_init_work); | |
6c1e851c | 626 | } |
5d73d1e3 EB |
627 | |
628 | static struct crng_state *select_crng(void) | |
629 | { | |
7b873241 JD |
630 | if (IS_ENABLED(CONFIG_NUMA)) { |
631 | struct crng_state **pool; | |
632 | int nid = numa_node_id(); | |
633 | ||
634 | /* pairs with cmpxchg_release() in do_numa_crng_init() */ | |
635 | pool = READ_ONCE(crng_node_pool); | |
636 | if (pool && pool[nid]) | |
637 | return pool[nid]; | |
638 | } | |
5d73d1e3 | 639 | |
5d73d1e3 EB |
640 | return &primary_crng; |
641 | } | |
8ef35c86 | 642 | |
dc12baac TT |
643 | /* |
644 | * crng_fast_load() can be called by code in the interrupt service | |
73c7733f JD |
645 | * path. So we can't afford to dilly-dally. Returns the number of |
646 | * bytes processed from cp. | |
dc12baac | 647 | */ |
d38bb085 | 648 | static size_t crng_fast_load(const u8 *cp, size_t len) |
e192be9d TT |
649 | { |
650 | unsigned long flags; | |
d38bb085 | 651 | u8 *p; |
73c7733f | 652 | size_t ret = 0; |
e192be9d TT |
653 | |
654 | if (!spin_trylock_irqsave(&primary_crng.lock, flags)) | |
655 | return 0; | |
43838a23 | 656 | if (crng_init != 0) { |
e192be9d TT |
657 | spin_unlock_irqrestore(&primary_crng.lock, flags); |
658 | return 0; | |
659 | } | |
248045b8 | 660 | p = (u8 *)&primary_crng.state[4]; |
e192be9d | 661 | while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) { |
1ca1b917 | 662 | p[crng_init_cnt % CHACHA_KEY_SIZE] ^= *cp; |
73c7733f | 663 | cp++; crng_init_cnt++; len--; ret++; |
e192be9d | 664 | } |
4a072c71 | 665 | spin_unlock_irqrestore(&primary_crng.lock, flags); |
e192be9d | 666 | if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) { |
b169c13d | 667 | invalidate_batched_entropy(); |
e192be9d | 668 | crng_init = 1; |
12cd53af | 669 | pr_notice("fast init done\n"); |
e192be9d | 670 | } |
73c7733f | 671 | return ret; |
e192be9d TT |
672 | } |
673 | ||
dc12baac TT |
674 | /* |
675 | * crng_slow_load() is called by add_device_randomness, which has two | |
676 | * attributes. (1) We can't trust the buffer passed to it is | |
677 | * guaranteed to be unpredictable (so it might not have any entropy at | |
678 | * all), and (2) it doesn't have the performance constraints of | |
679 | * crng_fast_load(). | |
680 | * | |
681 | * So we do something more comprehensive which is guaranteed to touch | |
682 | * all of the primary_crng's state, and which uses a LFSR with a | |
683 | * period of 255 as part of the mixing algorithm. Finally, we do | |
684 | * *not* advance crng_init_cnt since buffer we may get may be something | |
685 | * like a fixed DMI table (for example), which might very well be | |
686 | * unique to the machine, but is otherwise unvarying. | |
687 | */ | |
d38bb085 | 688 | static int crng_slow_load(const u8 *cp, size_t len) |
dc12baac | 689 | { |
248045b8 JD |
690 | unsigned long flags; |
691 | static u8 lfsr = 1; | |
692 | u8 tmp; | |
693 | unsigned int i, max = CHACHA_KEY_SIZE; | |
694 | const u8 *src_buf = cp; | |
695 | u8 *dest_buf = (u8 *)&primary_crng.state[4]; | |
dc12baac TT |
696 | |
697 | if (!spin_trylock_irqsave(&primary_crng.lock, flags)) | |
698 | return 0; | |
699 | if (crng_init != 0) { | |
700 | spin_unlock_irqrestore(&primary_crng.lock, flags); | |
701 | return 0; | |
702 | } | |
703 | if (len > max) | |
704 | max = len; | |
705 | ||
248045b8 | 706 | for (i = 0; i < max; i++) { |
dc12baac TT |
707 | tmp = lfsr; |
708 | lfsr >>= 1; | |
709 | if (tmp & 1) | |
710 | lfsr ^= 0xE1; | |
1ca1b917 EB |
711 | tmp = dest_buf[i % CHACHA_KEY_SIZE]; |
712 | dest_buf[i % CHACHA_KEY_SIZE] ^= src_buf[i % len] ^ lfsr; | |
dc12baac TT |
713 | lfsr += (tmp << 3) | (tmp >> 5); |
714 | } | |
715 | spin_unlock_irqrestore(&primary_crng.lock, flags); | |
716 | return 1; | |
717 | } | |
718 | ||
90ed1e67 | 719 | static void crng_reseed(struct crng_state *crng, bool use_input_pool) |
e192be9d | 720 | { |
248045b8 | 721 | unsigned long flags; |
6e8ec255 | 722 | int i; |
e192be9d | 723 | union { |
248045b8 JD |
724 | u8 block[CHACHA_BLOCK_SIZE]; |
725 | u32 key[8]; | |
e192be9d TT |
726 | } buf; |
727 | ||
90ed1e67 | 728 | if (use_input_pool) { |
9c07f578 JD |
729 | int entropy_count; |
730 | do { | |
731 | entropy_count = READ_ONCE(input_pool.entropy_count); | |
c5704490 | 732 | if (entropy_count < POOL_MIN_BITS) |
9c07f578 JD |
733 | return; |
734 | } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count); | |
735 | extract_entropy(buf.key, sizeof(buf.key)); | |
489c7fc4 JD |
736 | wake_up_interruptible(&random_write_wait); |
737 | kill_fasync(&fasync, SIGIO, POLL_OUT); | |
c92e040d | 738 | } else { |
1e7f583a | 739 | _extract_crng(&primary_crng, buf.block); |
c92e040d | 740 | _crng_backtrack_protect(&primary_crng, buf.block, |
1ca1b917 | 741 | CHACHA_KEY_SIZE); |
c92e040d | 742 | } |
0bb29a84 | 743 | spin_lock_irqsave(&crng->lock, flags); |
e192be9d | 744 | for (i = 0; i < 8; i++) { |
248045b8 | 745 | unsigned long rv; |
e192be9d TT |
746 | if (!arch_get_random_seed_long(&rv) && |
747 | !arch_get_random_long(&rv)) | |
748 | rv = random_get_entropy(); | |
248045b8 | 749 | crng->state[i + 4] ^= buf.key[i] ^ rv; |
e192be9d TT |
750 | } |
751 | memzero_explicit(&buf, sizeof(buf)); | |
009ba856 | 752 | WRITE_ONCE(crng->init_time, jiffies); |
0bb29a84 | 753 | spin_unlock_irqrestore(&crng->lock, flags); |
9d5505f1 DB |
754 | if (crng == &primary_crng && crng_init < 2) |
755 | crng_finalize_init(); | |
e192be9d TT |
756 | } |
757 | ||
248045b8 | 758 | static void _extract_crng(struct crng_state *crng, u8 out[CHACHA_BLOCK_SIZE]) |
e192be9d | 759 | { |
2ee25b69 | 760 | unsigned long flags, init_time; |
009ba856 EB |
761 | |
762 | if (crng_ready()) { | |
763 | init_time = READ_ONCE(crng->init_time); | |
764 | if (time_after(READ_ONCE(crng_global_init_time), init_time) || | |
765 | time_after(jiffies, init_time + CRNG_RESEED_INTERVAL)) | |
90ed1e67 | 766 | crng_reseed(crng, crng == &primary_crng); |
009ba856 | 767 | } |
e192be9d | 768 | spin_lock_irqsave(&crng->lock, flags); |
e192be9d TT |
769 | chacha20_block(&crng->state[0], out); |
770 | if (crng->state[12] == 0) | |
771 | crng->state[13]++; | |
772 | spin_unlock_irqrestore(&crng->lock, flags); | |
773 | } | |
774 | ||
d38bb085 | 775 | static void extract_crng(u8 out[CHACHA_BLOCK_SIZE]) |
1e7f583a | 776 | { |
5d73d1e3 | 777 | _extract_crng(select_crng(), out); |
1e7f583a TT |
778 | } |
779 | ||
c92e040d TT |
780 | /* |
781 | * Use the leftover bytes from the CRNG block output (if there is | |
782 | * enough) to mutate the CRNG key to provide backtracking protection. | |
783 | */ | |
784 | static void _crng_backtrack_protect(struct crng_state *crng, | |
d38bb085 | 785 | u8 tmp[CHACHA_BLOCK_SIZE], int used) |
c92e040d | 786 | { |
248045b8 JD |
787 | unsigned long flags; |
788 | u32 *s, *d; | |
789 | int i; | |
c92e040d | 790 | |
d38bb085 | 791 | used = round_up(used, sizeof(u32)); |
1ca1b917 | 792 | if (used + CHACHA_KEY_SIZE > CHACHA_BLOCK_SIZE) { |
c92e040d TT |
793 | extract_crng(tmp); |
794 | used = 0; | |
795 | } | |
796 | spin_lock_irqsave(&crng->lock, flags); | |
248045b8 | 797 | s = (u32 *)&tmp[used]; |
c92e040d | 798 | d = &crng->state[4]; |
248045b8 | 799 | for (i = 0; i < 8; i++) |
c92e040d TT |
800 | *d++ ^= *s++; |
801 | spin_unlock_irqrestore(&crng->lock, flags); | |
802 | } | |
803 | ||
d38bb085 | 804 | static void crng_backtrack_protect(u8 tmp[CHACHA_BLOCK_SIZE], int used) |
c92e040d | 805 | { |
5d73d1e3 | 806 | _crng_backtrack_protect(select_crng(), tmp, used); |
c92e040d TT |
807 | } |
808 | ||
e192be9d TT |
809 | static ssize_t extract_crng_user(void __user *buf, size_t nbytes) |
810 | { | |
1ca1b917 | 811 | ssize_t ret = 0, i = CHACHA_BLOCK_SIZE; |
d38bb085 | 812 | u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4); |
e192be9d TT |
813 | int large_request = (nbytes > 256); |
814 | ||
815 | while (nbytes) { | |
816 | if (large_request && need_resched()) { | |
817 | if (signal_pending(current)) { | |
818 | if (ret == 0) | |
819 | ret = -ERESTARTSYS; | |
820 | break; | |
821 | } | |
822 | schedule(); | |
823 | } | |
824 | ||
825 | extract_crng(tmp); | |
1ca1b917 | 826 | i = min_t(int, nbytes, CHACHA_BLOCK_SIZE); |
e192be9d TT |
827 | if (copy_to_user(buf, tmp, i)) { |
828 | ret = -EFAULT; | |
829 | break; | |
830 | } | |
831 | ||
832 | nbytes -= i; | |
833 | buf += i; | |
834 | ret += i; | |
835 | } | |
c92e040d | 836 | crng_backtrack_protect(tmp, i); |
e192be9d TT |
837 | |
838 | /* Wipe data just written to memory */ | |
839 | memzero_explicit(tmp, sizeof(tmp)); | |
840 | ||
841 | return ret; | |
842 | } | |
843 | ||
1da177e4 LT |
844 | /********************************************************************* |
845 | * | |
846 | * Entropy input management | |
847 | * | |
848 | *********************************************************************/ | |
849 | ||
850 | /* There is one of these per entropy source */ | |
851 | struct timer_rand_state { | |
852 | cycles_t last_time; | |
90b75ee5 | 853 | long last_delta, last_delta2; |
1da177e4 LT |
854 | }; |
855 | ||
644008df TT |
856 | #define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, }; |
857 | ||
a2080a67 | 858 | /* |
e192be9d TT |
859 | * Add device- or boot-specific data to the input pool to help |
860 | * initialize it. | |
a2080a67 | 861 | * |
e192be9d TT |
862 | * None of this adds any entropy; it is meant to avoid the problem of |
863 | * the entropy pool having similar initial state across largely | |
864 | * identical devices. | |
a2080a67 LT |
865 | */ |
866 | void add_device_randomness(const void *buf, unsigned int size) | |
867 | { | |
61875f30 | 868 | unsigned long time = random_get_entropy() ^ jiffies; |
3ef4cb2d | 869 | unsigned long flags; |
a2080a67 | 870 | |
dc12baac TT |
871 | if (!crng_ready() && size) |
872 | crng_slow_load(buf, size); | |
ee7998c5 | 873 | |
5910895f | 874 | trace_add_device_randomness(size, _RET_IP_); |
3ef4cb2d | 875 | spin_lock_irqsave(&input_pool.lock, flags); |
90ed1e67 JD |
876 | _mix_pool_bytes(buf, size); |
877 | _mix_pool_bytes(&time, sizeof(time)); | |
3ef4cb2d | 878 | spin_unlock_irqrestore(&input_pool.lock, flags); |
a2080a67 LT |
879 | } |
880 | EXPORT_SYMBOL(add_device_randomness); | |
881 | ||
644008df | 882 | static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE; |
3060d6fe | 883 | |
1da177e4 LT |
884 | /* |
885 | * This function adds entropy to the entropy "pool" by using timing | |
886 | * delays. It uses the timer_rand_state structure to make an estimate | |
887 | * of how many bits of entropy this call has added to the pool. | |
888 | * | |
889 | * The number "num" is also added to the pool - it should somehow describe | |
890 | * the type of event which just happened. This is currently 0-255 for | |
891 | * keyboard scan codes, and 256 upwards for interrupts. | |
892 | * | |
893 | */ | |
894 | static void add_timer_randomness(struct timer_rand_state *state, unsigned num) | |
895 | { | |
896 | struct { | |
1da177e4 | 897 | long jiffies; |
d38bb085 JD |
898 | unsigned int cycles; |
899 | unsigned int num; | |
1da177e4 LT |
900 | } sample; |
901 | long delta, delta2, delta3; | |
902 | ||
1da177e4 | 903 | sample.jiffies = jiffies; |
61875f30 | 904 | sample.cycles = random_get_entropy(); |
1da177e4 | 905 | sample.num = num; |
90ed1e67 | 906 | mix_pool_bytes(&sample, sizeof(sample)); |
1da177e4 LT |
907 | |
908 | /* | |
909 | * Calculate number of bits of randomness we probably added. | |
910 | * We take into account the first, second and third-order deltas | |
911 | * in order to make our estimate. | |
912 | */ | |
e00d996a QC |
913 | delta = sample.jiffies - READ_ONCE(state->last_time); |
914 | WRITE_ONCE(state->last_time, sample.jiffies); | |
5e747dd9 | 915 | |
e00d996a QC |
916 | delta2 = delta - READ_ONCE(state->last_delta); |
917 | WRITE_ONCE(state->last_delta, delta); | |
5e747dd9 | 918 | |
e00d996a QC |
919 | delta3 = delta2 - READ_ONCE(state->last_delta2); |
920 | WRITE_ONCE(state->last_delta2, delta2); | |
5e747dd9 RV |
921 | |
922 | if (delta < 0) | |
923 | delta = -delta; | |
924 | if (delta2 < 0) | |
925 | delta2 = -delta2; | |
926 | if (delta3 < 0) | |
927 | delta3 = -delta3; | |
928 | if (delta > delta2) | |
929 | delta = delta2; | |
930 | if (delta > delta3) | |
931 | delta = delta3; | |
1da177e4 | 932 | |
5e747dd9 RV |
933 | /* |
934 | * delta is now minimum absolute delta. | |
935 | * Round down by 1 bit on general principles, | |
727d499a | 936 | * and limit entropy estimate to 12 bits. |
5e747dd9 | 937 | */ |
248045b8 | 938 | credit_entropy_bits(min_t(int, fls(delta >> 1), 11)); |
1da177e4 LT |
939 | } |
940 | ||
d251575a | 941 | void add_input_randomness(unsigned int type, unsigned int code, |
248045b8 | 942 | unsigned int value) |
1da177e4 LT |
943 | { |
944 | static unsigned char last_value; | |
945 | ||
946 | /* ignore autorepeat and the like */ | |
947 | if (value == last_value) | |
948 | return; | |
949 | ||
1da177e4 LT |
950 | last_value = value; |
951 | add_timer_randomness(&input_timer_state, | |
952 | (type << 4) ^ code ^ (code >> 4) ^ value); | |
c5704490 | 953 | trace_add_input_randomness(input_pool.entropy_count); |
1da177e4 | 954 | } |
80fc9f53 | 955 | EXPORT_SYMBOL_GPL(add_input_randomness); |
1da177e4 | 956 | |
775f4b29 TT |
957 | static DEFINE_PER_CPU(struct fast_pool, irq_randomness); |
958 | ||
43759d4f TT |
959 | #ifdef ADD_INTERRUPT_BENCH |
960 | static unsigned long avg_cycles, avg_deviation; | |
961 | ||
248045b8 JD |
962 | #define AVG_SHIFT 8 /* Exponential average factor k=1/256 */ |
963 | #define FIXED_1_2 (1 << (AVG_SHIFT - 1)) | |
43759d4f TT |
964 | |
965 | static void add_interrupt_bench(cycles_t start) | |
966 | { | |
248045b8 | 967 | long delta = random_get_entropy() - start; |
43759d4f | 968 | |
248045b8 JD |
969 | /* Use a weighted moving average */ |
970 | delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT); | |
971 | avg_cycles += delta; | |
972 | /* And average deviation */ | |
973 | delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT); | |
974 | avg_deviation += delta; | |
43759d4f TT |
975 | } |
976 | #else | |
977 | #define add_interrupt_bench(x) | |
978 | #endif | |
979 | ||
d38bb085 | 980 | static u32 get_reg(struct fast_pool *f, struct pt_regs *regs) |
ee3e00e9 | 981 | { |
248045b8 | 982 | u32 *ptr = (u32 *)regs; |
92e75428 | 983 | unsigned int idx; |
ee3e00e9 TT |
984 | |
985 | if (regs == NULL) | |
986 | return 0; | |
92e75428 | 987 | idx = READ_ONCE(f->reg_idx); |
d38bb085 | 988 | if (idx >= sizeof(struct pt_regs) / sizeof(u32)) |
92e75428 TT |
989 | idx = 0; |
990 | ptr += idx++; | |
991 | WRITE_ONCE(f->reg_idx, idx); | |
9dfa7bba | 992 | return *ptr; |
ee3e00e9 TT |
993 | } |
994 | ||
703f7066 | 995 | void add_interrupt_randomness(int irq) |
1da177e4 | 996 | { |
248045b8 JD |
997 | struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness); |
998 | struct pt_regs *regs = get_irq_regs(); | |
999 | unsigned long now = jiffies; | |
1000 | cycles_t cycles = random_get_entropy(); | |
1001 | u32 c_high, j_high; | |
1002 | u64 ip; | |
3060d6fe | 1003 | |
ee3e00e9 TT |
1004 | if (cycles == 0) |
1005 | cycles = get_reg(fast_pool, regs); | |
655b2264 TT |
1006 | c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0; |
1007 | j_high = (sizeof(now) > 4) ? now >> 32 : 0; | |
43759d4f TT |
1008 | fast_pool->pool[0] ^= cycles ^ j_high ^ irq; |
1009 | fast_pool->pool[1] ^= now ^ c_high; | |
655b2264 | 1010 | ip = regs ? instruction_pointer(regs) : _RET_IP_; |
43759d4f | 1011 | fast_pool->pool[2] ^= ip; |
248045b8 JD |
1012 | fast_pool->pool[3] ^= |
1013 | (sizeof(ip) > 4) ? ip >> 32 : get_reg(fast_pool, regs); | |
3060d6fe | 1014 | |
43759d4f | 1015 | fast_mix(fast_pool); |
43759d4f | 1016 | add_interrupt_bench(cycles); |
3060d6fe | 1017 | |
43838a23 | 1018 | if (unlikely(crng_init == 0)) { |
e192be9d | 1019 | if ((fast_pool->count >= 64) && |
d38bb085 | 1020 | crng_fast_load((u8 *)fast_pool->pool, sizeof(fast_pool->pool)) > 0) { |
e192be9d TT |
1021 | fast_pool->count = 0; |
1022 | fast_pool->last = now; | |
1023 | } | |
1024 | return; | |
1025 | } | |
1026 | ||
248045b8 | 1027 | if ((fast_pool->count < 64) && !time_after(now, fast_pool->last + HZ)) |
1da177e4 LT |
1028 | return; |
1029 | ||
90ed1e67 | 1030 | if (!spin_trylock(&input_pool.lock)) |
91fcb532 | 1031 | return; |
83664a69 | 1032 | |
91fcb532 | 1033 | fast_pool->last = now; |
90ed1e67 JD |
1034 | __mix_pool_bytes(&fast_pool->pool, sizeof(fast_pool->pool)); |
1035 | spin_unlock(&input_pool.lock); | |
83664a69 | 1036 | |
ee3e00e9 | 1037 | fast_pool->count = 0; |
83664a69 | 1038 | |
ee3e00e9 | 1039 | /* award one bit for the contents of the fast pool */ |
90ed1e67 | 1040 | credit_entropy_bits(1); |
1da177e4 | 1041 | } |
4b44f2d1 | 1042 | EXPORT_SYMBOL_GPL(add_interrupt_randomness); |
1da177e4 | 1043 | |
9361401e | 1044 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1045 | void add_disk_randomness(struct gendisk *disk) |
1046 | { | |
1047 | if (!disk || !disk->random) | |
1048 | return; | |
1049 | /* first major is 1, so we get >= 0x200 here */ | |
f331c029 | 1050 | add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); |
c5704490 | 1051 | trace_add_disk_randomness(disk_devt(disk), input_pool.entropy_count); |
1da177e4 | 1052 | } |
bdcfa3e5 | 1053 | EXPORT_SYMBOL_GPL(add_disk_randomness); |
9361401e | 1054 | #endif |
1da177e4 | 1055 | |
1da177e4 LT |
1056 | /********************************************************************* |
1057 | * | |
1058 | * Entropy extraction routines | |
1059 | * | |
1060 | *********************************************************************/ | |
1061 | ||
19fa5be1 | 1062 | /* |
6e8ec255 JD |
1063 | * This is an HKDF-like construction for using the hashed collected entropy |
1064 | * as a PRF key, that's then expanded block-by-block. | |
19fa5be1 | 1065 | */ |
9c07f578 | 1066 | static void extract_entropy(void *buf, size_t nbytes) |
1da177e4 | 1067 | { |
902c098a | 1068 | unsigned long flags; |
6e8ec255 JD |
1069 | u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE]; |
1070 | struct { | |
1071 | unsigned long rdrand[32 / sizeof(long)]; | |
1072 | size_t counter; | |
1073 | } block; | |
1074 | size_t i; | |
1075 | ||
c5704490 | 1076 | trace_extract_entropy(nbytes, input_pool.entropy_count); |
9c07f578 | 1077 | |
6e8ec255 JD |
1078 | for (i = 0; i < ARRAY_SIZE(block.rdrand); ++i) { |
1079 | if (!arch_get_random_long(&block.rdrand[i])) | |
1080 | block.rdrand[i] = random_get_entropy(); | |
85a1f777 TT |
1081 | } |
1082 | ||
90ed1e67 | 1083 | spin_lock_irqsave(&input_pool.lock, flags); |
46884442 | 1084 | |
6e8ec255 JD |
1085 | /* seed = HASHPRF(last_key, entropy_input) */ |
1086 | blake2s_final(&input_pool.hash, seed); | |
1da177e4 | 1087 | |
6e8ec255 JD |
1088 | /* next_key = HASHPRF(seed, RDRAND || 0) */ |
1089 | block.counter = 0; | |
1090 | blake2s(next_key, (u8 *)&block, seed, sizeof(next_key), sizeof(block), sizeof(seed)); | |
1091 | blake2s_init_key(&input_pool.hash, BLAKE2S_HASH_SIZE, next_key, sizeof(next_key)); | |
1da177e4 | 1092 | |
6e8ec255 JD |
1093 | spin_unlock_irqrestore(&input_pool.lock, flags); |
1094 | memzero_explicit(next_key, sizeof(next_key)); | |
e192be9d TT |
1095 | |
1096 | while (nbytes) { | |
6e8ec255 JD |
1097 | i = min_t(size_t, nbytes, BLAKE2S_HASH_SIZE); |
1098 | /* output = HASHPRF(seed, RDRAND || ++counter) */ | |
1099 | ++block.counter; | |
1100 | blake2s(buf, (u8 *)&block, seed, i, sizeof(block), sizeof(seed)); | |
e192be9d TT |
1101 | nbytes -= i; |
1102 | buf += i; | |
e192be9d TT |
1103 | } |
1104 | ||
6e8ec255 JD |
1105 | memzero_explicit(seed, sizeof(seed)); |
1106 | memzero_explicit(&block, sizeof(block)); | |
e192be9d TT |
1107 | } |
1108 | ||
eecabf56 | 1109 | #define warn_unseeded_randomness(previous) \ |
248045b8 | 1110 | _warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous)) |
eecabf56 | 1111 | |
248045b8 | 1112 | static void _warn_unseeded_randomness(const char *func_name, void *caller, void **previous) |
eecabf56 TT |
1113 | { |
1114 | #ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM | |
1115 | const bool print_once = false; | |
1116 | #else | |
1117 | static bool print_once __read_mostly; | |
1118 | #endif | |
1119 | ||
248045b8 | 1120 | if (print_once || crng_ready() || |
eecabf56 TT |
1121 | (previous && (caller == READ_ONCE(*previous)))) |
1122 | return; | |
1123 | WRITE_ONCE(*previous, caller); | |
1124 | #ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM | |
1125 | print_once = true; | |
1126 | #endif | |
4e00b339 | 1127 | if (__ratelimit(&unseeded_warning)) |
248045b8 JD |
1128 | printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n", |
1129 | func_name, caller, crng_init); | |
eecabf56 TT |
1130 | } |
1131 | ||
1da177e4 LT |
1132 | /* |
1133 | * This function is the exported kernel interface. It returns some | |
c2557a30 | 1134 | * number of good random numbers, suitable for key generation, seeding |
18e9cea7 GP |
1135 | * TCP sequence numbers, etc. It does not rely on the hardware random |
1136 | * number generator. For random bytes direct from the hardware RNG | |
e297a783 JD |
1137 | * (when available), use get_random_bytes_arch(). In order to ensure |
1138 | * that the randomness provided by this function is okay, the function | |
1139 | * wait_for_random_bytes() should be called and return 0 at least once | |
1140 | * at any point prior. | |
1da177e4 | 1141 | */ |
eecabf56 | 1142 | static void _get_random_bytes(void *buf, int nbytes) |
c2557a30 | 1143 | { |
d38bb085 | 1144 | u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4); |
e192be9d | 1145 | |
5910895f | 1146 | trace_get_random_bytes(nbytes, _RET_IP_); |
e192be9d | 1147 | |
1ca1b917 | 1148 | while (nbytes >= CHACHA_BLOCK_SIZE) { |
e192be9d | 1149 | extract_crng(buf); |
1ca1b917 EB |
1150 | buf += CHACHA_BLOCK_SIZE; |
1151 | nbytes -= CHACHA_BLOCK_SIZE; | |
e192be9d TT |
1152 | } |
1153 | ||
1154 | if (nbytes > 0) { | |
1155 | extract_crng(tmp); | |
1156 | memcpy(buf, tmp, nbytes); | |
c92e040d TT |
1157 | crng_backtrack_protect(tmp, nbytes); |
1158 | } else | |
1ca1b917 | 1159 | crng_backtrack_protect(tmp, CHACHA_BLOCK_SIZE); |
c92e040d | 1160 | memzero_explicit(tmp, sizeof(tmp)); |
c2557a30 | 1161 | } |
eecabf56 TT |
1162 | |
1163 | void get_random_bytes(void *buf, int nbytes) | |
1164 | { | |
1165 | static void *previous; | |
1166 | ||
1167 | warn_unseeded_randomness(&previous); | |
1168 | _get_random_bytes(buf, nbytes); | |
1169 | } | |
c2557a30 TT |
1170 | EXPORT_SYMBOL(get_random_bytes); |
1171 | ||
50ee7529 LT |
1172 | /* |
1173 | * Each time the timer fires, we expect that we got an unpredictable | |
1174 | * jump in the cycle counter. Even if the timer is running on another | |
1175 | * CPU, the timer activity will be touching the stack of the CPU that is | |
1176 | * generating entropy.. | |
1177 | * | |
1178 | * Note that we don't re-arm the timer in the timer itself - we are | |
1179 | * happy to be scheduled away, since that just makes the load more | |
1180 | * complex, but we do not want the timer to keep ticking unless the | |
1181 | * entropy loop is running. | |
1182 | * | |
1183 | * So the re-arming always happens in the entropy loop itself. | |
1184 | */ | |
1185 | static void entropy_timer(struct timer_list *t) | |
1186 | { | |
90ed1e67 | 1187 | credit_entropy_bits(1); |
50ee7529 LT |
1188 | } |
1189 | ||
1190 | /* | |
1191 | * If we have an actual cycle counter, see if we can | |
1192 | * generate enough entropy with timing noise | |
1193 | */ | |
1194 | static void try_to_generate_entropy(void) | |
1195 | { | |
1196 | struct { | |
1197 | unsigned long now; | |
1198 | struct timer_list timer; | |
1199 | } stack; | |
1200 | ||
1201 | stack.now = random_get_entropy(); | |
1202 | ||
1203 | /* Slow counter - or none. Don't even bother */ | |
1204 | if (stack.now == random_get_entropy()) | |
1205 | return; | |
1206 | ||
1207 | timer_setup_on_stack(&stack.timer, entropy_timer, 0); | |
1208 | while (!crng_ready()) { | |
1209 | if (!timer_pending(&stack.timer)) | |
248045b8 | 1210 | mod_timer(&stack.timer, jiffies + 1); |
90ed1e67 | 1211 | mix_pool_bytes(&stack.now, sizeof(stack.now)); |
50ee7529 LT |
1212 | schedule(); |
1213 | stack.now = random_get_entropy(); | |
1214 | } | |
1215 | ||
1216 | del_timer_sync(&stack.timer); | |
1217 | destroy_timer_on_stack(&stack.timer); | |
90ed1e67 | 1218 | mix_pool_bytes(&stack.now, sizeof(stack.now)); |
50ee7529 LT |
1219 | } |
1220 | ||
e297a783 JD |
1221 | /* |
1222 | * Wait for the urandom pool to be seeded and thus guaranteed to supply | |
1223 | * cryptographically secure random numbers. This applies to: the /dev/urandom | |
1224 | * device, the get_random_bytes function, and the get_random_{u32,u64,int,long} | |
1225 | * family of functions. Using any of these functions without first calling | |
1226 | * this function forfeits the guarantee of security. | |
1227 | * | |
1228 | * Returns: 0 if the urandom pool has been seeded. | |
1229 | * -ERESTARTSYS if the function was interrupted by a signal. | |
1230 | */ | |
1231 | int wait_for_random_bytes(void) | |
1232 | { | |
1233 | if (likely(crng_ready())) | |
1234 | return 0; | |
50ee7529 LT |
1235 | |
1236 | do { | |
1237 | int ret; | |
1238 | ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ); | |
1239 | if (ret) | |
1240 | return ret > 0 ? 0 : ret; | |
1241 | ||
1242 | try_to_generate_entropy(); | |
1243 | } while (!crng_ready()); | |
1244 | ||
1245 | return 0; | |
e297a783 JD |
1246 | } |
1247 | EXPORT_SYMBOL(wait_for_random_bytes); | |
1248 | ||
9a47249d JD |
1249 | /* |
1250 | * Returns whether or not the urandom pool has been seeded and thus guaranteed | |
1251 | * to supply cryptographically secure random numbers. This applies to: the | |
1252 | * /dev/urandom device, the get_random_bytes function, and the get_random_{u32, | |
1253 | * ,u64,int,long} family of functions. | |
1254 | * | |
1255 | * Returns: true if the urandom pool has been seeded. | |
1256 | * false if the urandom pool has not been seeded. | |
1257 | */ | |
1258 | bool rng_is_initialized(void) | |
1259 | { | |
1260 | return crng_ready(); | |
1261 | } | |
1262 | EXPORT_SYMBOL(rng_is_initialized); | |
1263 | ||
205a525c HX |
1264 | /* |
1265 | * Add a callback function that will be invoked when the nonblocking | |
1266 | * pool is initialised. | |
1267 | * | |
1268 | * returns: 0 if callback is successfully added | |
1269 | * -EALREADY if pool is already initialised (callback not called) | |
1270 | * -ENOENT if module for callback is not alive | |
1271 | */ | |
1272 | int add_random_ready_callback(struct random_ready_callback *rdy) | |
1273 | { | |
1274 | struct module *owner; | |
1275 | unsigned long flags; | |
1276 | int err = -EALREADY; | |
1277 | ||
e192be9d | 1278 | if (crng_ready()) |
205a525c HX |
1279 | return err; |
1280 | ||
1281 | owner = rdy->owner; | |
1282 | if (!try_module_get(owner)) | |
1283 | return -ENOENT; | |
1284 | ||
1285 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
e192be9d | 1286 | if (crng_ready()) |
205a525c HX |
1287 | goto out; |
1288 | ||
1289 | owner = NULL; | |
1290 | ||
1291 | list_add(&rdy->list, &random_ready_list); | |
1292 | err = 0; | |
1293 | ||
1294 | out: | |
1295 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
1296 | ||
1297 | module_put(owner); | |
1298 | ||
1299 | return err; | |
1300 | } | |
1301 | EXPORT_SYMBOL(add_random_ready_callback); | |
1302 | ||
1303 | /* | |
1304 | * Delete a previously registered readiness callback function. | |
1305 | */ | |
1306 | void del_random_ready_callback(struct random_ready_callback *rdy) | |
1307 | { | |
1308 | unsigned long flags; | |
1309 | struct module *owner = NULL; | |
1310 | ||
1311 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
1312 | if (!list_empty(&rdy->list)) { | |
1313 | list_del_init(&rdy->list); | |
1314 | owner = rdy->owner; | |
1315 | } | |
1316 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
1317 | ||
1318 | module_put(owner); | |
1319 | } | |
1320 | EXPORT_SYMBOL(del_random_ready_callback); | |
1321 | ||
c2557a30 TT |
1322 | /* |
1323 | * This function will use the architecture-specific hardware random | |
1324 | * number generator if it is available. The arch-specific hw RNG will | |
1325 | * almost certainly be faster than what we can do in software, but it | |
1326 | * is impossible to verify that it is implemented securely (as | |
1327 | * opposed, to, say, the AES encryption of a sequence number using a | |
1328 | * key known by the NSA). So it's useful if we need the speed, but | |
1329 | * only if we're willing to trust the hardware manufacturer not to | |
1330 | * have put in a back door. | |
753d433b TH |
1331 | * |
1332 | * Return number of bytes filled in. | |
c2557a30 | 1333 | */ |
753d433b | 1334 | int __must_check get_random_bytes_arch(void *buf, int nbytes) |
1da177e4 | 1335 | { |
753d433b | 1336 | int left = nbytes; |
d38bb085 | 1337 | u8 *p = buf; |
63d77173 | 1338 | |
753d433b TH |
1339 | trace_get_random_bytes_arch(left, _RET_IP_); |
1340 | while (left) { | |
63d77173 | 1341 | unsigned long v; |
753d433b | 1342 | int chunk = min_t(int, left, sizeof(unsigned long)); |
c2557a30 | 1343 | |
63d77173 PA |
1344 | if (!arch_get_random_long(&v)) |
1345 | break; | |
8ddd6efa | 1346 | |
bd29e568 | 1347 | memcpy(p, &v, chunk); |
63d77173 | 1348 | p += chunk; |
753d433b | 1349 | left -= chunk; |
63d77173 PA |
1350 | } |
1351 | ||
753d433b | 1352 | return nbytes - left; |
1da177e4 | 1353 | } |
c2557a30 TT |
1354 | EXPORT_SYMBOL(get_random_bytes_arch); |
1355 | ||
1da177e4 LT |
1356 | /* |
1357 | * init_std_data - initialize pool with system data | |
1358 | * | |
1da177e4 LT |
1359 | * This function clears the pool's entropy count and mixes some system |
1360 | * data into the pool to prepare it for use. The pool is not cleared | |
1361 | * as that can only decrease the entropy in the pool. | |
1362 | */ | |
90ed1e67 | 1363 | static void __init init_std_data(void) |
1da177e4 | 1364 | { |
3e88bdff | 1365 | int i; |
902c098a TT |
1366 | ktime_t now = ktime_get_real(); |
1367 | unsigned long rv; | |
1da177e4 | 1368 | |
90ed1e67 | 1369 | mix_pool_bytes(&now, sizeof(now)); |
6e8ec255 | 1370 | for (i = BLAKE2S_BLOCK_SIZE; i > 0; i -= sizeof(rv)) { |
83664a69 PA |
1371 | if (!arch_get_random_seed_long(&rv) && |
1372 | !arch_get_random_long(&rv)) | |
ae9ecd92 | 1373 | rv = random_get_entropy(); |
90ed1e67 | 1374 | mix_pool_bytes(&rv, sizeof(rv)); |
3e88bdff | 1375 | } |
90ed1e67 | 1376 | mix_pool_bytes(utsname(), sizeof(*(utsname()))); |
1da177e4 LT |
1377 | } |
1378 | ||
cbc96b75 TL |
1379 | /* |
1380 | * Note that setup_arch() may call add_device_randomness() | |
1381 | * long before we get here. This allows seeding of the pools | |
1382 | * with some platform dependent data very early in the boot | |
1383 | * process. But it limits our options here. We must use | |
1384 | * statically allocated structures that already have all | |
1385 | * initializations complete at compile time. We should also | |
1386 | * take care not to overwrite the precious per platform data | |
1387 | * we were given. | |
1388 | */ | |
d5553523 | 1389 | int __init rand_initialize(void) |
1da177e4 | 1390 | { |
90ed1e67 | 1391 | init_std_data(); |
f7e67b8e | 1392 | if (crng_need_final_init) |
9d5505f1 | 1393 | crng_finalize_init(); |
ebf76063 | 1394 | crng_initialize_primary(); |
d848e5f8 | 1395 | crng_global_init_time = jiffies; |
4e00b339 TT |
1396 | if (ratelimit_disable) { |
1397 | urandom_warning.interval = 0; | |
1398 | unseeded_warning.interval = 0; | |
1399 | } | |
1da177e4 LT |
1400 | return 0; |
1401 | } | |
1da177e4 | 1402 | |
9361401e | 1403 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1404 | void rand_initialize_disk(struct gendisk *disk) |
1405 | { | |
1406 | struct timer_rand_state *state; | |
1407 | ||
1408 | /* | |
f8595815 | 1409 | * If kzalloc returns null, we just won't use that entropy |
1da177e4 LT |
1410 | * source. |
1411 | */ | |
f8595815 | 1412 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
644008df TT |
1413 | if (state) { |
1414 | state->last_time = INITIAL_JIFFIES; | |
1da177e4 | 1415 | disk->random = state; |
644008df | 1416 | } |
1da177e4 | 1417 | } |
9361401e | 1418 | #endif |
1da177e4 | 1419 | |
248045b8 JD |
1420 | static ssize_t urandom_read_nowarn(struct file *file, char __user *buf, |
1421 | size_t nbytes, loff_t *ppos) | |
c6f1deb1 AL |
1422 | { |
1423 | int ret; | |
1424 | ||
c5704490 | 1425 | nbytes = min_t(size_t, nbytes, INT_MAX >> 6); |
c6f1deb1 | 1426 | ret = extract_crng_user(buf, nbytes); |
c5704490 | 1427 | trace_urandom_read(8 * nbytes, 0, input_pool.entropy_count); |
c6f1deb1 AL |
1428 | return ret; |
1429 | } | |
1430 | ||
248045b8 JD |
1431 | static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes, |
1432 | loff_t *ppos) | |
1da177e4 | 1433 | { |
9b4d0087 | 1434 | static int maxwarn = 10; |
301f0595 | 1435 | |
e192be9d | 1436 | if (!crng_ready() && maxwarn > 0) { |
9b4d0087 | 1437 | maxwarn--; |
4e00b339 | 1438 | if (__ratelimit(&urandom_warning)) |
12cd53af YL |
1439 | pr_notice("%s: uninitialized urandom read (%zd bytes read)\n", |
1440 | current->comm, nbytes); | |
9b4d0087 | 1441 | } |
c6f1deb1 AL |
1442 | |
1443 | return urandom_read_nowarn(file, buf, nbytes, ppos); | |
1da177e4 LT |
1444 | } |
1445 | ||
248045b8 JD |
1446 | static ssize_t random_read(struct file *file, char __user *buf, size_t nbytes, |
1447 | loff_t *ppos) | |
30c08efe AL |
1448 | { |
1449 | int ret; | |
1450 | ||
1451 | ret = wait_for_random_bytes(); | |
1452 | if (ret != 0) | |
1453 | return ret; | |
1454 | return urandom_read_nowarn(file, buf, nbytes, ppos); | |
1455 | } | |
1456 | ||
248045b8 | 1457 | static __poll_t random_poll(struct file *file, poll_table *wait) |
1da177e4 | 1458 | { |
a11e1d43 | 1459 | __poll_t mask; |
1da177e4 | 1460 | |
30c08efe | 1461 | poll_wait(file, &crng_init_wait, wait); |
a11e1d43 LT |
1462 | poll_wait(file, &random_write_wait, wait); |
1463 | mask = 0; | |
30c08efe | 1464 | if (crng_ready()) |
a9a08845 | 1465 | mask |= EPOLLIN | EPOLLRDNORM; |
489c7fc4 | 1466 | if (input_pool.entropy_count < POOL_MIN_BITS) |
a9a08845 | 1467 | mask |= EPOLLOUT | EPOLLWRNORM; |
1da177e4 LT |
1468 | return mask; |
1469 | } | |
1470 | ||
248045b8 | 1471 | static int write_pool(const char __user *buffer, size_t count) |
1da177e4 | 1472 | { |
1da177e4 | 1473 | size_t bytes; |
d38bb085 | 1474 | u32 t, buf[16]; |
1da177e4 | 1475 | const char __user *p = buffer; |
1da177e4 | 1476 | |
7f397dcd | 1477 | while (count > 0) { |
81e69df3 TT |
1478 | int b, i = 0; |
1479 | ||
7f397dcd MM |
1480 | bytes = min(count, sizeof(buf)); |
1481 | if (copy_from_user(&buf, p, bytes)) | |
1482 | return -EFAULT; | |
1da177e4 | 1483 | |
d38bb085 | 1484 | for (b = bytes; b > 0; b -= sizeof(u32), i++) { |
81e69df3 TT |
1485 | if (!arch_get_random_int(&t)) |
1486 | break; | |
1487 | buf[i] ^= t; | |
1488 | } | |
1489 | ||
7f397dcd | 1490 | count -= bytes; |
1da177e4 LT |
1491 | p += bytes; |
1492 | ||
90ed1e67 | 1493 | mix_pool_bytes(buf, bytes); |
91f3f1e3 | 1494 | cond_resched(); |
1da177e4 | 1495 | } |
7f397dcd MM |
1496 | |
1497 | return 0; | |
1498 | } | |
1499 | ||
90b75ee5 MM |
1500 | static ssize_t random_write(struct file *file, const char __user *buffer, |
1501 | size_t count, loff_t *ppos) | |
7f397dcd MM |
1502 | { |
1503 | size_t ret; | |
7f397dcd | 1504 | |
90ed1e67 | 1505 | ret = write_pool(buffer, count); |
7f397dcd MM |
1506 | if (ret) |
1507 | return ret; | |
1508 | ||
7f397dcd | 1509 | return (ssize_t)count; |
1da177e4 LT |
1510 | } |
1511 | ||
43ae4860 | 1512 | static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) |
1da177e4 LT |
1513 | { |
1514 | int size, ent_count; | |
1515 | int __user *p = (int __user *)arg; | |
1516 | int retval; | |
1517 | ||
1518 | switch (cmd) { | |
1519 | case RNDGETENTCNT: | |
43ae4860 | 1520 | /* inherently racy, no point locking */ |
c5704490 | 1521 | if (put_user(input_pool.entropy_count, p)) |
1da177e4 LT |
1522 | return -EFAULT; |
1523 | return 0; | |
1524 | case RNDADDTOENTCNT: | |
1525 | if (!capable(CAP_SYS_ADMIN)) | |
1526 | return -EPERM; | |
1527 | if (get_user(ent_count, p)) | |
1528 | return -EFAULT; | |
90ed1e67 | 1529 | return credit_entropy_bits_safe(ent_count); |
1da177e4 LT |
1530 | case RNDADDENTROPY: |
1531 | if (!capable(CAP_SYS_ADMIN)) | |
1532 | return -EPERM; | |
1533 | if (get_user(ent_count, p++)) | |
1534 | return -EFAULT; | |
1535 | if (ent_count < 0) | |
1536 | return -EINVAL; | |
1537 | if (get_user(size, p++)) | |
1538 | return -EFAULT; | |
90ed1e67 | 1539 | retval = write_pool((const char __user *)p, size); |
1da177e4 LT |
1540 | if (retval < 0) |
1541 | return retval; | |
90ed1e67 | 1542 | return credit_entropy_bits_safe(ent_count); |
1da177e4 LT |
1543 | case RNDZAPENTCNT: |
1544 | case RNDCLEARPOOL: | |
ae9ecd92 TT |
1545 | /* |
1546 | * Clear the entropy pool counters. We no longer clear | |
1547 | * the entropy pool, as that's silly. | |
1548 | */ | |
1da177e4 LT |
1549 | if (!capable(CAP_SYS_ADMIN)) |
1550 | return -EPERM; | |
489c7fc4 | 1551 | if (xchg(&input_pool.entropy_count, 0)) { |
042e293e JD |
1552 | wake_up_interruptible(&random_write_wait); |
1553 | kill_fasync(&fasync, SIGIO, POLL_OUT); | |
1554 | } | |
1da177e4 | 1555 | return 0; |
d848e5f8 TT |
1556 | case RNDRESEEDCRNG: |
1557 | if (!capable(CAP_SYS_ADMIN)) | |
1558 | return -EPERM; | |
1559 | if (crng_init < 2) | |
1560 | return -ENODATA; | |
90ed1e67 | 1561 | crng_reseed(&primary_crng, true); |
009ba856 | 1562 | WRITE_ONCE(crng_global_init_time, jiffies - 1); |
d848e5f8 | 1563 | return 0; |
1da177e4 LT |
1564 | default: |
1565 | return -EINVAL; | |
1566 | } | |
1567 | } | |
1568 | ||
9a6f70bb JD |
1569 | static int random_fasync(int fd, struct file *filp, int on) |
1570 | { | |
1571 | return fasync_helper(fd, filp, on, &fasync); | |
1572 | } | |
1573 | ||
2b8693c0 | 1574 | const struct file_operations random_fops = { |
248045b8 | 1575 | .read = random_read, |
1da177e4 | 1576 | .write = random_write, |
248045b8 | 1577 | .poll = random_poll, |
43ae4860 | 1578 | .unlocked_ioctl = random_ioctl, |
507e4e2b | 1579 | .compat_ioctl = compat_ptr_ioctl, |
9a6f70bb | 1580 | .fasync = random_fasync, |
6038f373 | 1581 | .llseek = noop_llseek, |
1da177e4 LT |
1582 | }; |
1583 | ||
2b8693c0 | 1584 | const struct file_operations urandom_fops = { |
248045b8 | 1585 | .read = urandom_read, |
1da177e4 | 1586 | .write = random_write, |
43ae4860 | 1587 | .unlocked_ioctl = random_ioctl, |
4aa37c46 | 1588 | .compat_ioctl = compat_ptr_ioctl, |
9a6f70bb | 1589 | .fasync = random_fasync, |
6038f373 | 1590 | .llseek = noop_llseek, |
1da177e4 LT |
1591 | }; |
1592 | ||
248045b8 JD |
1593 | SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int, |
1594 | flags) | |
c6e9d6f3 | 1595 | { |
e297a783 JD |
1596 | int ret; |
1597 | ||
248045b8 | 1598 | if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE)) |
75551dbf AL |
1599 | return -EINVAL; |
1600 | ||
1601 | /* | |
1602 | * Requesting insecure and blocking randomness at the same time makes | |
1603 | * no sense. | |
1604 | */ | |
248045b8 | 1605 | if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM)) |
c6e9d6f3 TT |
1606 | return -EINVAL; |
1607 | ||
1608 | if (count > INT_MAX) | |
1609 | count = INT_MAX; | |
1610 | ||
75551dbf | 1611 | if (!(flags & GRND_INSECURE) && !crng_ready()) { |
c6e9d6f3 TT |
1612 | if (flags & GRND_NONBLOCK) |
1613 | return -EAGAIN; | |
e297a783 JD |
1614 | ret = wait_for_random_bytes(); |
1615 | if (unlikely(ret)) | |
1616 | return ret; | |
c6e9d6f3 | 1617 | } |
c6f1deb1 | 1618 | return urandom_read_nowarn(NULL, buf, count, NULL); |
c6e9d6f3 TT |
1619 | } |
1620 | ||
1da177e4 LT |
1621 | /******************************************************************** |
1622 | * | |
1623 | * Sysctl interface | |
1624 | * | |
1625 | ********************************************************************/ | |
1626 | ||
1627 | #ifdef CONFIG_SYSCTL | |
1628 | ||
1629 | #include <linux/sysctl.h> | |
1630 | ||
db61ffe3 | 1631 | static int random_min_urandom_seed = 60; |
489c7fc4 JD |
1632 | static int random_write_wakeup_bits = POOL_MIN_BITS; |
1633 | static int sysctl_poolsize = POOL_BITS; | |
1da177e4 LT |
1634 | static char sysctl_bootid[16]; |
1635 | ||
1636 | /* | |
f22052b2 | 1637 | * This function is used to return both the bootid UUID, and random |
1da177e4 LT |
1638 | * UUID. The difference is in whether table->data is NULL; if it is, |
1639 | * then a new UUID is generated and returned to the user. | |
1640 | * | |
f22052b2 GP |
1641 | * If the user accesses this via the proc interface, the UUID will be |
1642 | * returned as an ASCII string in the standard UUID format; if via the | |
1643 | * sysctl system call, as 16 bytes of binary data. | |
1da177e4 | 1644 | */ |
248045b8 JD |
1645 | static int proc_do_uuid(struct ctl_table *table, int write, void *buffer, |
1646 | size_t *lenp, loff_t *ppos) | |
1da177e4 | 1647 | { |
a151427e | 1648 | struct ctl_table fake_table; |
1da177e4 LT |
1649 | unsigned char buf[64], tmp_uuid[16], *uuid; |
1650 | ||
1651 | uuid = table->data; | |
1652 | if (!uuid) { | |
1653 | uuid = tmp_uuid; | |
1da177e4 | 1654 | generate_random_uuid(uuid); |
44e4360f MD |
1655 | } else { |
1656 | static DEFINE_SPINLOCK(bootid_spinlock); | |
1657 | ||
1658 | spin_lock(&bootid_spinlock); | |
1659 | if (!uuid[8]) | |
1660 | generate_random_uuid(uuid); | |
1661 | spin_unlock(&bootid_spinlock); | |
1662 | } | |
1da177e4 | 1663 | |
35900771 JP |
1664 | sprintf(buf, "%pU", uuid); |
1665 | ||
1da177e4 LT |
1666 | fake_table.data = buf; |
1667 | fake_table.maxlen = sizeof(buf); | |
1668 | ||
8d65af78 | 1669 | return proc_dostring(&fake_table, write, buffer, lenp, ppos); |
1da177e4 LT |
1670 | } |
1671 | ||
5475e8f0 | 1672 | static struct ctl_table random_table[] = { |
1da177e4 | 1673 | { |
1da177e4 LT |
1674 | .procname = "poolsize", |
1675 | .data = &sysctl_poolsize, | |
1676 | .maxlen = sizeof(int), | |
1677 | .mode = 0444, | |
6d456111 | 1678 | .proc_handler = proc_dointvec, |
1da177e4 LT |
1679 | }, |
1680 | { | |
1da177e4 | 1681 | .procname = "entropy_avail", |
c5704490 | 1682 | .data = &input_pool.entropy_count, |
1da177e4 LT |
1683 | .maxlen = sizeof(int), |
1684 | .mode = 0444, | |
c5704490 | 1685 | .proc_handler = proc_dointvec, |
1da177e4 | 1686 | }, |
1da177e4 | 1687 | { |
1da177e4 | 1688 | .procname = "write_wakeup_threshold", |
2132a96f | 1689 | .data = &random_write_wakeup_bits, |
1da177e4 LT |
1690 | .maxlen = sizeof(int), |
1691 | .mode = 0644, | |
489c7fc4 | 1692 | .proc_handler = proc_dointvec, |
1da177e4 | 1693 | }, |
f5c2742c TT |
1694 | { |
1695 | .procname = "urandom_min_reseed_secs", | |
1696 | .data = &random_min_urandom_seed, | |
1697 | .maxlen = sizeof(int), | |
1698 | .mode = 0644, | |
1699 | .proc_handler = proc_dointvec, | |
1700 | }, | |
1da177e4 | 1701 | { |
1da177e4 LT |
1702 | .procname = "boot_id", |
1703 | .data = &sysctl_bootid, | |
1704 | .maxlen = 16, | |
1705 | .mode = 0444, | |
6d456111 | 1706 | .proc_handler = proc_do_uuid, |
1da177e4 LT |
1707 | }, |
1708 | { | |
1da177e4 LT |
1709 | .procname = "uuid", |
1710 | .maxlen = 16, | |
1711 | .mode = 0444, | |
6d456111 | 1712 | .proc_handler = proc_do_uuid, |
1da177e4 | 1713 | }, |
43759d4f TT |
1714 | #ifdef ADD_INTERRUPT_BENCH |
1715 | { | |
1716 | .procname = "add_interrupt_avg_cycles", | |
1717 | .data = &avg_cycles, | |
1718 | .maxlen = sizeof(avg_cycles), | |
1719 | .mode = 0444, | |
1720 | .proc_handler = proc_doulongvec_minmax, | |
1721 | }, | |
1722 | { | |
1723 | .procname = "add_interrupt_avg_deviation", | |
1724 | .data = &avg_deviation, | |
1725 | .maxlen = sizeof(avg_deviation), | |
1726 | .mode = 0444, | |
1727 | .proc_handler = proc_doulongvec_minmax, | |
1728 | }, | |
1729 | #endif | |
894d2491 | 1730 | { } |
1da177e4 | 1731 | }; |
5475e8f0 XN |
1732 | |
1733 | /* | |
1734 | * rand_initialize() is called before sysctl_init(), | |
1735 | * so we cannot call register_sysctl_init() in rand_initialize() | |
1736 | */ | |
1737 | static int __init random_sysctls_init(void) | |
1738 | { | |
1739 | register_sysctl_init("kernel/random", random_table); | |
1740 | return 0; | |
1741 | } | |
1742 | device_initcall(random_sysctls_init); | |
248045b8 | 1743 | #endif /* CONFIG_SYSCTL */ |
1da177e4 | 1744 | |
f5b98461 JD |
1745 | struct batched_entropy { |
1746 | union { | |
1ca1b917 EB |
1747 | u64 entropy_u64[CHACHA_BLOCK_SIZE / sizeof(u64)]; |
1748 | u32 entropy_u32[CHACHA_BLOCK_SIZE / sizeof(u32)]; | |
f5b98461 JD |
1749 | }; |
1750 | unsigned int position; | |
b7d5dc21 | 1751 | spinlock_t batch_lock; |
f5b98461 | 1752 | }; |
b1132dea | 1753 | |
1da177e4 | 1754 | /* |
f5b98461 | 1755 | * Get a random word for internal kernel use only. The quality of the random |
69efea71 JD |
1756 | * number is good as /dev/urandom, but there is no backtrack protection, with |
1757 | * the goal of being quite fast and not depleting entropy. In order to ensure | |
e297a783 | 1758 | * that the randomness provided by this function is okay, the function |
69efea71 JD |
1759 | * wait_for_random_bytes() should be called and return 0 at least once at any |
1760 | * point prior. | |
1da177e4 | 1761 | */ |
b7d5dc21 | 1762 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = { |
248045b8 | 1763 | .batch_lock = __SPIN_LOCK_UNLOCKED(batched_entropy_u64.lock), |
b7d5dc21 SAS |
1764 | }; |
1765 | ||
c440408c | 1766 | u64 get_random_u64(void) |
1da177e4 | 1767 | { |
c440408c | 1768 | u64 ret; |
b7d5dc21 | 1769 | unsigned long flags; |
f5b98461 | 1770 | struct batched_entropy *batch; |
eecabf56 | 1771 | static void *previous; |
8a0a9bd4 | 1772 | |
eecabf56 | 1773 | warn_unseeded_randomness(&previous); |
d06bfd19 | 1774 | |
b7d5dc21 SAS |
1775 | batch = raw_cpu_ptr(&batched_entropy_u64); |
1776 | spin_lock_irqsave(&batch->batch_lock, flags); | |
c440408c | 1777 | if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) { |
a5e9f557 | 1778 | extract_crng((u8 *)batch->entropy_u64); |
f5b98461 JD |
1779 | batch->position = 0; |
1780 | } | |
c440408c | 1781 | ret = batch->entropy_u64[batch->position++]; |
b7d5dc21 | 1782 | spin_unlock_irqrestore(&batch->batch_lock, flags); |
8a0a9bd4 | 1783 | return ret; |
1da177e4 | 1784 | } |
c440408c | 1785 | EXPORT_SYMBOL(get_random_u64); |
1da177e4 | 1786 | |
b7d5dc21 | 1787 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = { |
248045b8 | 1788 | .batch_lock = __SPIN_LOCK_UNLOCKED(batched_entropy_u32.lock), |
b7d5dc21 | 1789 | }; |
c440408c | 1790 | u32 get_random_u32(void) |
f5b98461 | 1791 | { |
c440408c | 1792 | u32 ret; |
b7d5dc21 | 1793 | unsigned long flags; |
f5b98461 | 1794 | struct batched_entropy *batch; |
eecabf56 | 1795 | static void *previous; |
ec9ee4ac | 1796 | |
eecabf56 | 1797 | warn_unseeded_randomness(&previous); |
d06bfd19 | 1798 | |
b7d5dc21 SAS |
1799 | batch = raw_cpu_ptr(&batched_entropy_u32); |
1800 | spin_lock_irqsave(&batch->batch_lock, flags); | |
c440408c | 1801 | if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) { |
a5e9f557 | 1802 | extract_crng((u8 *)batch->entropy_u32); |
f5b98461 JD |
1803 | batch->position = 0; |
1804 | } | |
c440408c | 1805 | ret = batch->entropy_u32[batch->position++]; |
b7d5dc21 | 1806 | spin_unlock_irqrestore(&batch->batch_lock, flags); |
ec9ee4ac DC |
1807 | return ret; |
1808 | } | |
c440408c | 1809 | EXPORT_SYMBOL(get_random_u32); |
ec9ee4ac | 1810 | |
b169c13d JD |
1811 | /* It's important to invalidate all potential batched entropy that might |
1812 | * be stored before the crng is initialized, which we can do lazily by | |
1813 | * simply resetting the counter to zero so that it's re-extracted on the | |
1814 | * next usage. */ | |
1815 | static void invalidate_batched_entropy(void) | |
1816 | { | |
1817 | int cpu; | |
1818 | unsigned long flags; | |
1819 | ||
248045b8 | 1820 | for_each_possible_cpu(cpu) { |
b7d5dc21 SAS |
1821 | struct batched_entropy *batched_entropy; |
1822 | ||
1823 | batched_entropy = per_cpu_ptr(&batched_entropy_u32, cpu); | |
1824 | spin_lock_irqsave(&batched_entropy->batch_lock, flags); | |
1825 | batched_entropy->position = 0; | |
1826 | spin_unlock(&batched_entropy->batch_lock); | |
1827 | ||
1828 | batched_entropy = per_cpu_ptr(&batched_entropy_u64, cpu); | |
1829 | spin_lock(&batched_entropy->batch_lock); | |
1830 | batched_entropy->position = 0; | |
1831 | spin_unlock_irqrestore(&batched_entropy->batch_lock, flags); | |
b169c13d | 1832 | } |
b169c13d JD |
1833 | } |
1834 | ||
99fdafde JC |
1835 | /** |
1836 | * randomize_page - Generate a random, page aligned address | |
1837 | * @start: The smallest acceptable address the caller will take. | |
1838 | * @range: The size of the area, starting at @start, within which the | |
1839 | * random address must fall. | |
1840 | * | |
1841 | * If @start + @range would overflow, @range is capped. | |
1842 | * | |
1843 | * NOTE: Historical use of randomize_range, which this replaces, presumed that | |
1844 | * @start was already page aligned. We now align it regardless. | |
1845 | * | |
1846 | * Return: A page aligned address within [start, start + range). On error, | |
1847 | * @start is returned. | |
1848 | */ | |
248045b8 | 1849 | unsigned long randomize_page(unsigned long start, unsigned long range) |
99fdafde JC |
1850 | { |
1851 | if (!PAGE_ALIGNED(start)) { | |
1852 | range -= PAGE_ALIGN(start) - start; | |
1853 | start = PAGE_ALIGN(start); | |
1854 | } | |
1855 | ||
1856 | if (start > ULONG_MAX - range) | |
1857 | range = ULONG_MAX - start; | |
1858 | ||
1859 | range >>= PAGE_SHIFT; | |
1860 | ||
1861 | if (range == 0) | |
1862 | return start; | |
1863 | ||
1864 | return start + (get_random_long() % range << PAGE_SHIFT); | |
1865 | } | |
1866 | ||
c84dbf61 TD |
1867 | /* Interface for in-kernel drivers of true hardware RNGs. |
1868 | * Those devices may produce endless random bits and will be throttled | |
1869 | * when our pool is full. | |
1870 | */ | |
1871 | void add_hwgenerator_randomness(const char *buffer, size_t count, | |
1872 | size_t entropy) | |
1873 | { | |
43838a23 | 1874 | if (unlikely(crng_init == 0)) { |
73c7733f | 1875 | size_t ret = crng_fast_load(buffer, count); |
90ed1e67 | 1876 | mix_pool_bytes(buffer, ret); |
73c7733f JD |
1877 | count -= ret; |
1878 | buffer += ret; | |
1879 | if (!count || crng_init == 0) | |
1880 | return; | |
3371f3da | 1881 | } |
e192be9d | 1882 | |
c321e907 | 1883 | /* Throttle writing if we're above the trickle threshold. |
489c7fc4 JD |
1884 | * We'll be woken up again once below POOL_MIN_BITS, when |
1885 | * the calling thread is about to terminate, or once | |
1886 | * CRNG_RESEED_INTERVAL has elapsed. | |
e192be9d | 1887 | */ |
c321e907 | 1888 | wait_event_interruptible_timeout(random_write_wait, |
f7e67b8e | 1889 | !system_wq || kthread_should_stop() || |
489c7fc4 | 1890 | input_pool.entropy_count < POOL_MIN_BITS, |
c321e907 | 1891 | CRNG_RESEED_INTERVAL); |
90ed1e67 JD |
1892 | mix_pool_bytes(buffer, count); |
1893 | credit_entropy_bits(entropy); | |
c84dbf61 TD |
1894 | } |
1895 | EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); | |
428826f5 HYW |
1896 | |
1897 | /* Handle random seed passed by bootloader. | |
1898 | * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise | |
1899 | * it would be regarded as device data. | |
1900 | * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER. | |
1901 | */ | |
1902 | void add_bootloader_randomness(const void *buf, unsigned int size) | |
1903 | { | |
1904 | if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER)) | |
1905 | add_hwgenerator_randomness(buf, size, size * 8); | |
1906 | else | |
1907 | add_device_randomness(buf, size); | |
1908 | } | |
3fd57e7a | 1909 | EXPORT_SYMBOL_GPL(add_bootloader_randomness); |