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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 | * | |
186873c5 | 70 | * The primary kernel interfaces are: |
92e507d2 | 71 | * |
04ec96b7 | 72 | * void get_random_bytes(void *buf, size_t nbytes); |
248045b8 JD |
73 | * u32 get_random_u32() |
74 | * u64 get_random_u64() | |
75 | * unsigned int get_random_int() | |
76 | * unsigned long get_random_long() | |
92e507d2 | 77 | * |
186873c5 JD |
78 | * These interfaces will return the requested number of random bytes |
79 | * into the given buffer or as a return value. This is equivalent to a | |
80 | * read from /dev/urandom. The get_random_{u32,u64,int,long}() family | |
81 | * of functions may be higher performance for one-off random integers, | |
82 | * because they do a bit of buffering. | |
92e507d2 GS |
83 | * |
84 | * prandom_u32() | |
85 | * ------------- | |
86 | * | |
87 | * For even weaker applications, see the pseudorandom generator | |
88 | * prandom_u32(), prandom_max(), and prandom_bytes(). If the random | |
89 | * numbers aren't security-critical at all, these are *far* cheaper. | |
90 | * Useful for self-tests, random error simulation, randomized backoffs, | |
91 | * and any other application where you trust that nobody is trying to | |
92 | * maliciously mess with you by guessing the "random" numbers. | |
93 | * | |
1da177e4 LT |
94 | * Exported interfaces ---- input |
95 | * ============================== | |
96 | * | |
97 | * The current exported interfaces for gathering environmental noise | |
98 | * from the devices are: | |
99 | * | |
04ec96b7 | 100 | * void add_device_randomness(const void *buf, size_t size); |
248045b8 | 101 | * void add_input_randomness(unsigned int type, unsigned int code, |
1da177e4 | 102 | * unsigned int value); |
703f7066 | 103 | * void add_interrupt_randomness(int irq); |
248045b8 | 104 | * void add_disk_randomness(struct gendisk *disk); |
04ec96b7 | 105 | * void add_hwgenerator_randomness(const void *buffer, size_t count, |
2b6c6e3d | 106 | * size_t entropy); |
04ec96b7 | 107 | * void add_bootloader_randomness(const void *buf, size_t size); |
1da177e4 | 108 | * |
a2080a67 LT |
109 | * add_device_randomness() is for adding data to the random pool that |
110 | * is likely to differ between two devices (or possibly even per boot). | |
111 | * This would be things like MAC addresses or serial numbers, or the | |
112 | * read-out of the RTC. This does *not* add any actual entropy to the | |
113 | * pool, but it initializes the pool to different values for devices | |
114 | * that might otherwise be identical and have very little entropy | |
115 | * available to them (particularly common in the embedded world). | |
116 | * | |
1da177e4 LT |
117 | * add_input_randomness() uses the input layer interrupt timing, as well as |
118 | * the event type information from the hardware. | |
119 | * | |
775f4b29 TT |
120 | * add_interrupt_randomness() uses the interrupt timing as random |
121 | * inputs to the entropy pool. Using the cycle counters and the irq source | |
122 | * as inputs, it feeds the randomness roughly once a second. | |
442a4fff JW |
123 | * |
124 | * add_disk_randomness() uses what amounts to the seek time of block | |
125 | * layer request events, on a per-disk_devt basis, as input to the | |
126 | * entropy pool. Note that high-speed solid state drives with very low | |
127 | * seek times do not make for good sources of entropy, as their seek | |
128 | * times are usually fairly consistent. | |
1da177e4 LT |
129 | * |
130 | * All of these routines try to estimate how many bits of randomness a | |
131 | * particular randomness source. They do this by keeping track of the | |
132 | * first and second order deltas of the event timings. | |
133 | * | |
2b6c6e3d MB |
134 | * add_hwgenerator_randomness() is for true hardware RNGs, and will credit |
135 | * entropy as specified by the caller. If the entropy pool is full it will | |
136 | * block until more entropy is needed. | |
137 | * | |
138 | * add_bootloader_randomness() is the same as add_hwgenerator_randomness() or | |
139 | * add_device_randomness(), depending on whether or not the configuration | |
140 | * option CONFIG_RANDOM_TRUST_BOOTLOADER is set. | |
141 | * | |
1da177e4 LT |
142 | * Ensuring unpredictability at system startup |
143 | * ============================================ | |
144 | * | |
145 | * When any operating system starts up, it will go through a sequence | |
146 | * of actions that are fairly predictable by an adversary, especially | |
147 | * if the start-up does not involve interaction with a human operator. | |
148 | * This reduces the actual number of bits of unpredictability in the | |
149 | * entropy pool below the value in entropy_count. In order to | |
150 | * counteract this effect, it helps to carry information in the | |
151 | * entropy pool across shut-downs and start-ups. To do this, put the | |
152 | * following lines an appropriate script which is run during the boot | |
153 | * sequence: | |
154 | * | |
155 | * echo "Initializing random number generator..." | |
156 | * random_seed=/var/run/random-seed | |
157 | * # Carry a random seed from start-up to start-up | |
158 | * # Load and then save the whole entropy pool | |
159 | * if [ -f $random_seed ]; then | |
160 | * cat $random_seed >/dev/urandom | |
161 | * else | |
162 | * touch $random_seed | |
163 | * fi | |
164 | * chmod 600 $random_seed | |
165 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 | |
166 | * | |
167 | * and the following lines in an appropriate script which is run as | |
168 | * the system is shutdown: | |
169 | * | |
170 | * # Carry a random seed from shut-down to start-up | |
171 | * # Save the whole entropy pool | |
172 | * echo "Saving random seed..." | |
173 | * random_seed=/var/run/random-seed | |
174 | * touch $random_seed | |
175 | * chmod 600 $random_seed | |
176 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 | |
177 | * | |
178 | * For example, on most modern systems using the System V init | |
179 | * scripts, such code fragments would be found in | |
180 | * /etc/rc.d/init.d/random. On older Linux systems, the correct script | |
181 | * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0. | |
182 | * | |
183 | * Effectively, these commands cause the contents of the entropy pool | |
184 | * to be saved at shut-down time and reloaded into the entropy pool at | |
185 | * start-up. (The 'dd' in the addition to the bootup script is to | |
186 | * make sure that /etc/random-seed is different for every start-up, | |
187 | * even if the system crashes without executing rc.0.) Even with | |
188 | * complete knowledge of the start-up activities, predicting the state | |
189 | * of the entropy pool requires knowledge of the previous history of | |
190 | * the system. | |
191 | * | |
192 | * Configuring the /dev/random driver under Linux | |
193 | * ============================================== | |
194 | * | |
195 | * The /dev/random driver under Linux uses minor numbers 8 and 9 of | |
196 | * the /dev/mem major number (#1). So if your system does not have | |
197 | * /dev/random and /dev/urandom created already, they can be created | |
198 | * by using the commands: | |
199 | * | |
248045b8 JD |
200 | * mknod /dev/random c 1 8 |
201 | * mknod /dev/urandom c 1 9 | |
1da177e4 LT |
202 | */ |
203 | ||
12cd53af YL |
204 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
205 | ||
1da177e4 | 206 | #include <linux/utsname.h> |
1da177e4 LT |
207 | #include <linux/module.h> |
208 | #include <linux/kernel.h> | |
209 | #include <linux/major.h> | |
210 | #include <linux/string.h> | |
211 | #include <linux/fcntl.h> | |
212 | #include <linux/slab.h> | |
213 | #include <linux/random.h> | |
214 | #include <linux/poll.h> | |
215 | #include <linux/init.h> | |
216 | #include <linux/fs.h> | |
217 | #include <linux/genhd.h> | |
218 | #include <linux/interrupt.h> | |
27ac792c | 219 | #include <linux/mm.h> |
dd0f0cf5 | 220 | #include <linux/nodemask.h> |
1da177e4 | 221 | #include <linux/spinlock.h> |
c84dbf61 | 222 | #include <linux/kthread.h> |
1da177e4 | 223 | #include <linux/percpu.h> |
775f4b29 | 224 | #include <linux/ptrace.h> |
6265e169 | 225 | #include <linux/workqueue.h> |
0244ad00 | 226 | #include <linux/irq.h> |
4e00b339 | 227 | #include <linux/ratelimit.h> |
c6e9d6f3 TT |
228 | #include <linux/syscalls.h> |
229 | #include <linux/completion.h> | |
8da4b8c4 | 230 | #include <linux/uuid.h> |
1ca1b917 | 231 | #include <crypto/chacha.h> |
9f9eff85 | 232 | #include <crypto/blake2s.h> |
d178a1eb | 233 | |
1da177e4 | 234 | #include <asm/processor.h> |
7c0f6ba6 | 235 | #include <linux/uaccess.h> |
1da177e4 | 236 | #include <asm/irq.h> |
775f4b29 | 237 | #include <asm/irq_regs.h> |
1da177e4 LT |
238 | #include <asm/io.h> |
239 | ||
00ce1db1 TT |
240 | #define CREATE_TRACE_POINTS |
241 | #include <trace/events/random.h> | |
242 | ||
43759d4f TT |
243 | /* #define ADD_INTERRUPT_BENCH */ |
244 | ||
c5704490 | 245 | enum { |
6e8ec255 | 246 | POOL_BITS = BLAKE2S_HASH_SIZE * 8, |
c5704490 | 247 | POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */ |
1da177e4 LT |
248 | }; |
249 | ||
1da177e4 LT |
250 | /* |
251 | * Static global variables | |
252 | */ | |
a11e1d43 | 253 | static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); |
9a6f70bb | 254 | static struct fasync_struct *fasync; |
1da177e4 | 255 | |
205a525c HX |
256 | static DEFINE_SPINLOCK(random_ready_list_lock); |
257 | static LIST_HEAD(random_ready_list); | |
258 | ||
e192be9d TT |
259 | /* |
260 | * crng_init = 0 --> Uninitialized | |
261 | * 1 --> Initialized | |
262 | * 2 --> Initialized from input_pool | |
263 | * | |
264 | * crng_init is protected by primary_crng->lock, and only increases | |
265 | * its value (from 0->1->2). | |
266 | */ | |
267 | static int crng_init = 0; | |
43838a23 | 268 | #define crng_ready() (likely(crng_init > 1)) |
e192be9d | 269 | static int crng_init_cnt = 0; |
e192be9d | 270 | static void process_random_ready_list(void); |
04ec96b7 | 271 | static void _get_random_bytes(void *buf, size_t nbytes); |
e192be9d | 272 | |
4e00b339 TT |
273 | static struct ratelimit_state unseeded_warning = |
274 | RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3); | |
275 | static struct ratelimit_state urandom_warning = | |
276 | RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3); | |
277 | ||
278 | static int ratelimit_disable __read_mostly; | |
279 | ||
280 | module_param_named(ratelimit_disable, ratelimit_disable, int, 0644); | |
281 | MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression"); | |
282 | ||
1da177e4 LT |
283 | /********************************************************************** |
284 | * | |
285 | * OS independent entropy store. Here are the functions which handle | |
286 | * storing entropy in an entropy pool. | |
287 | * | |
288 | **********************************************************************/ | |
289 | ||
90ed1e67 | 290 | static struct { |
6e8ec255 | 291 | struct blake2s_state hash; |
43358209 | 292 | spinlock_t lock; |
04ec96b7 | 293 | unsigned int entropy_count; |
90ed1e67 | 294 | } input_pool = { |
6e8ec255 JD |
295 | .hash.h = { BLAKE2S_IV0 ^ (0x01010000 | BLAKE2S_HASH_SIZE), |
296 | BLAKE2S_IV1, BLAKE2S_IV2, BLAKE2S_IV3, BLAKE2S_IV4, | |
297 | BLAKE2S_IV5, BLAKE2S_IV6, BLAKE2S_IV7 }, | |
298 | .hash.outlen = BLAKE2S_HASH_SIZE, | |
eece09ec | 299 | .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock), |
1da177e4 LT |
300 | }; |
301 | ||
9c07f578 | 302 | static void extract_entropy(void *buf, size_t nbytes); |
90ed1e67 | 303 | |
a9412d51 | 304 | static void crng_reseed(void); |
90ed1e67 | 305 | |
1da177e4 | 306 | /* |
e68e5b66 | 307 | * This function adds bytes into the entropy "pool". It does not |
1da177e4 | 308 | * update the entropy estimate. The caller should call |
adc782da | 309 | * credit_entropy_bits if this is appropriate. |
1da177e4 | 310 | */ |
04ec96b7 | 311 | static void _mix_pool_bytes(const void *in, size_t nbytes) |
1da177e4 | 312 | { |
6e8ec255 | 313 | blake2s_update(&input_pool.hash, in, nbytes); |
1da177e4 LT |
314 | } |
315 | ||
04ec96b7 | 316 | static void mix_pool_bytes(const void *in, size_t nbytes) |
1da177e4 | 317 | { |
902c098a TT |
318 | unsigned long flags; |
319 | ||
90ed1e67 JD |
320 | trace_mix_pool_bytes(nbytes, _RET_IP_); |
321 | spin_lock_irqsave(&input_pool.lock, flags); | |
322 | _mix_pool_bytes(in, nbytes); | |
323 | spin_unlock_irqrestore(&input_pool.lock, flags); | |
1da177e4 LT |
324 | } |
325 | ||
775f4b29 | 326 | struct fast_pool { |
248045b8 JD |
327 | u32 pool[4]; |
328 | unsigned long last; | |
329 | u16 reg_idx; | |
330 | u8 count; | |
775f4b29 TT |
331 | }; |
332 | ||
333 | /* | |
334 | * This is a fast mixing routine used by the interrupt randomness | |
335 | * collector. It's hardcoded for an 128 bit pool and assumes that any | |
336 | * locks that might be needed are taken by the caller. | |
337 | */ | |
43759d4f | 338 | static void fast_mix(struct fast_pool *f) |
775f4b29 | 339 | { |
d38bb085 JD |
340 | u32 a = f->pool[0], b = f->pool[1]; |
341 | u32 c = f->pool[2], d = f->pool[3]; | |
43759d4f TT |
342 | |
343 | a += b; c += d; | |
19acc77a | 344 | b = rol32(b, 6); d = rol32(d, 27); |
43759d4f TT |
345 | d ^= a; b ^= c; |
346 | ||
347 | a += b; c += d; | |
19acc77a | 348 | b = rol32(b, 16); d = rol32(d, 14); |
43759d4f TT |
349 | d ^= a; b ^= c; |
350 | ||
351 | a += b; c += d; | |
19acc77a | 352 | b = rol32(b, 6); d = rol32(d, 27); |
43759d4f TT |
353 | d ^= a; b ^= c; |
354 | ||
355 | a += b; c += d; | |
19acc77a | 356 | b = rol32(b, 16); d = rol32(d, 14); |
43759d4f TT |
357 | d ^= a; b ^= c; |
358 | ||
359 | f->pool[0] = a; f->pool[1] = b; | |
360 | f->pool[2] = c; f->pool[3] = d; | |
655b2264 | 361 | f->count++; |
775f4b29 TT |
362 | } |
363 | ||
205a525c HX |
364 | static void process_random_ready_list(void) |
365 | { | |
366 | unsigned long flags; | |
367 | struct random_ready_callback *rdy, *tmp; | |
368 | ||
369 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
370 | list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) { | |
371 | struct module *owner = rdy->owner; | |
372 | ||
373 | list_del_init(&rdy->list); | |
374 | rdy->func(rdy); | |
375 | module_put(owner); | |
376 | } | |
377 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
378 | } | |
379 | ||
04ec96b7 | 380 | static void credit_entropy_bits(size_t nbits) |
1da177e4 | 381 | { |
04ec96b7 | 382 | unsigned int entropy_count, orig, add; |
18263c4e | 383 | |
04ec96b7 | 384 | if (!nbits) |
adc782da MM |
385 | return; |
386 | ||
04ec96b7 | 387 | add = min_t(size_t, nbits, POOL_BITS); |
a49c010e | 388 | |
c5704490 JD |
389 | do { |
390 | orig = READ_ONCE(input_pool.entropy_count); | |
04ec96b7 | 391 | entropy_count = min_t(unsigned int, POOL_BITS, orig + add); |
c5704490 | 392 | } while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig); |
1da177e4 | 393 | |
c5704490 | 394 | trace_credit_entropy_bits(nbits, entropy_count, _RET_IP_); |
00ce1db1 | 395 | |
c5704490 | 396 | if (crng_init < 2 && entropy_count >= POOL_MIN_BITS) |
a9412d51 | 397 | crng_reseed(); |
1da177e4 LT |
398 | } |
399 | ||
e192be9d TT |
400 | /********************************************************************* |
401 | * | |
402 | * CRNG using CHACHA20 | |
403 | * | |
404 | *********************************************************************/ | |
405 | ||
186873c5 JD |
406 | enum { |
407 | CRNG_RESEED_INTERVAL = 300 * HZ, | |
408 | CRNG_INIT_CNT_THRESH = 2 * CHACHA_KEY_SIZE | |
409 | }; | |
410 | ||
411 | static struct { | |
412 | u8 key[CHACHA_KEY_SIZE] __aligned(__alignof__(long)); | |
413 | unsigned long birth; | |
414 | unsigned long generation; | |
415 | spinlock_t lock; | |
416 | } base_crng = { | |
417 | .lock = __SPIN_LOCK_UNLOCKED(base_crng.lock) | |
418 | }; | |
419 | ||
420 | struct crng { | |
421 | u8 key[CHACHA_KEY_SIZE]; | |
422 | unsigned long generation; | |
423 | local_lock_t lock; | |
424 | }; | |
425 | ||
426 | static DEFINE_PER_CPU(struct crng, crngs) = { | |
427 | .generation = ULONG_MAX, | |
428 | .lock = INIT_LOCAL_LOCK(crngs.lock), | |
429 | }; | |
e192be9d TT |
430 | |
431 | static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); | |
432 | ||
b169c13d JD |
433 | static void invalidate_batched_entropy(void); |
434 | ||
dc12baac TT |
435 | /* |
436 | * crng_fast_load() can be called by code in the interrupt service | |
73c7733f JD |
437 | * path. So we can't afford to dilly-dally. Returns the number of |
438 | * bytes processed from cp. | |
dc12baac | 439 | */ |
04ec96b7 | 440 | static size_t crng_fast_load(const void *cp, size_t len) |
e192be9d TT |
441 | { |
442 | unsigned long flags; | |
04ec96b7 | 443 | const u8 *src = (const u8 *)cp; |
73c7733f | 444 | size_t ret = 0; |
e192be9d | 445 | |
186873c5 | 446 | if (!spin_trylock_irqsave(&base_crng.lock, flags)) |
e192be9d | 447 | return 0; |
43838a23 | 448 | if (crng_init != 0) { |
186873c5 | 449 | spin_unlock_irqrestore(&base_crng.lock, flags); |
e192be9d TT |
450 | return 0; |
451 | } | |
e192be9d | 452 | while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) { |
04ec96b7 JD |
453 | base_crng.key[crng_init_cnt % sizeof(base_crng.key)] ^= *src; |
454 | src++; crng_init_cnt++; len--; ret++; | |
e192be9d TT |
455 | } |
456 | if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) { | |
b169c13d | 457 | invalidate_batched_entropy(); |
e192be9d | 458 | crng_init = 1; |
e192be9d | 459 | } |
186873c5 | 460 | spin_unlock_irqrestore(&base_crng.lock, flags); |
7c2fe2b3 DB |
461 | if (crng_init == 1) |
462 | pr_notice("fast init done\n"); | |
73c7733f | 463 | return ret; |
e192be9d TT |
464 | } |
465 | ||
dc12baac TT |
466 | /* |
467 | * crng_slow_load() is called by add_device_randomness, which has two | |
468 | * attributes. (1) We can't trust the buffer passed to it is | |
469 | * guaranteed to be unpredictable (so it might not have any entropy at | |
470 | * all), and (2) it doesn't have the performance constraints of | |
471 | * crng_fast_load(). | |
472 | * | |
66e4c2b9 JD |
473 | * So, we simply hash the contents in with the current key. Finally, |
474 | * we do *not* advance crng_init_cnt since buffer we may get may be | |
475 | * something like a fixed DMI table (for example), which might very | |
476 | * well be unique to the machine, but is otherwise unvarying. | |
dc12baac | 477 | */ |
04ec96b7 | 478 | static void crng_slow_load(const void *cp, size_t len) |
dc12baac | 479 | { |
248045b8 | 480 | unsigned long flags; |
66e4c2b9 JD |
481 | struct blake2s_state hash; |
482 | ||
483 | blake2s_init(&hash, sizeof(base_crng.key)); | |
dc12baac | 484 | |
186873c5 | 485 | if (!spin_trylock_irqsave(&base_crng.lock, flags)) |
66e4c2b9 | 486 | return; |
dc12baac | 487 | if (crng_init != 0) { |
186873c5 | 488 | spin_unlock_irqrestore(&base_crng.lock, flags); |
66e4c2b9 | 489 | return; |
dc12baac | 490 | } |
66e4c2b9 JD |
491 | |
492 | blake2s_update(&hash, base_crng.key, sizeof(base_crng.key)); | |
493 | blake2s_update(&hash, cp, len); | |
494 | blake2s_final(&hash, base_crng.key); | |
495 | ||
186873c5 | 496 | spin_unlock_irqrestore(&base_crng.lock, flags); |
dc12baac TT |
497 | } |
498 | ||
a9412d51 | 499 | static void crng_reseed(void) |
e192be9d | 500 | { |
248045b8 | 501 | unsigned long flags; |
186873c5 JD |
502 | int entropy_count; |
503 | unsigned long next_gen; | |
504 | u8 key[CHACHA_KEY_SIZE]; | |
e192be9d | 505 | |
186873c5 JD |
506 | /* |
507 | * First we make sure we have POOL_MIN_BITS of entropy in the pool, | |
508 | * and then we drain all of it. Only then can we extract a new key. | |
509 | */ | |
a9412d51 JD |
510 | do { |
511 | entropy_count = READ_ONCE(input_pool.entropy_count); | |
512 | if (entropy_count < POOL_MIN_BITS) | |
513 | return; | |
514 | } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count); | |
186873c5 | 515 | extract_entropy(key, sizeof(key)); |
a9412d51 JD |
516 | wake_up_interruptible(&random_write_wait); |
517 | kill_fasync(&fasync, SIGIO, POLL_OUT); | |
518 | ||
186873c5 JD |
519 | /* |
520 | * We copy the new key into the base_crng, overwriting the old one, | |
521 | * and update the generation counter. We avoid hitting ULONG_MAX, | |
522 | * because the per-cpu crngs are initialized to ULONG_MAX, so this | |
523 | * forces new CPUs that come online to always initialize. | |
524 | */ | |
525 | spin_lock_irqsave(&base_crng.lock, flags); | |
526 | memcpy(base_crng.key, key, sizeof(base_crng.key)); | |
527 | next_gen = base_crng.generation + 1; | |
528 | if (next_gen == ULONG_MAX) | |
529 | ++next_gen; | |
530 | WRITE_ONCE(base_crng.generation, next_gen); | |
531 | WRITE_ONCE(base_crng.birth, jiffies); | |
532 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
533 | memzero_explicit(key, sizeof(key)); | |
534 | ||
a9412d51 JD |
535 | if (crng_init < 2) { |
536 | invalidate_batched_entropy(); | |
537 | crng_init = 2; | |
538 | process_random_ready_list(); | |
539 | wake_up_interruptible(&crng_init_wait); | |
540 | kill_fasync(&fasync, SIGIO, POLL_IN); | |
541 | pr_notice("crng init done\n"); | |
542 | if (unseeded_warning.missed) { | |
543 | pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n", | |
544 | unseeded_warning.missed); | |
545 | unseeded_warning.missed = 0; | |
546 | } | |
547 | if (urandom_warning.missed) { | |
548 | pr_notice("%d urandom warning(s) missed due to ratelimiting\n", | |
549 | urandom_warning.missed); | |
550 | urandom_warning.missed = 0; | |
551 | } | |
552 | } | |
e192be9d TT |
553 | } |
554 | ||
186873c5 JD |
555 | /* |
556 | * The general form here is based on a "fast key erasure RNG" from | |
557 | * <https://blog.cr.yp.to/20170723-random.html>. It generates a ChaCha | |
558 | * block using the provided key, and then immediately overwites that | |
559 | * key with half the block. It returns the resultant ChaCha state to the | |
560 | * user, along with the second half of the block containing 32 bytes of | |
561 | * random data that may be used; random_data_len may not be greater than | |
562 | * 32. | |
563 | */ | |
564 | static void crng_fast_key_erasure(u8 key[CHACHA_KEY_SIZE], | |
565 | u32 chacha_state[CHACHA_STATE_WORDS], | |
566 | u8 *random_data, size_t random_data_len) | |
e192be9d | 567 | { |
186873c5 | 568 | u8 first_block[CHACHA_BLOCK_SIZE]; |
009ba856 | 569 | |
186873c5 JD |
570 | BUG_ON(random_data_len > 32); |
571 | ||
572 | chacha_init_consts(chacha_state); | |
573 | memcpy(&chacha_state[4], key, CHACHA_KEY_SIZE); | |
574 | memset(&chacha_state[12], 0, sizeof(u32) * 4); | |
575 | chacha20_block(chacha_state, first_block); | |
576 | ||
577 | memcpy(key, first_block, CHACHA_KEY_SIZE); | |
578 | memcpy(random_data, first_block + CHACHA_KEY_SIZE, random_data_len); | |
579 | memzero_explicit(first_block, sizeof(first_block)); | |
1e7f583a TT |
580 | } |
581 | ||
c92e040d | 582 | /* |
186873c5 JD |
583 | * This function returns a ChaCha state that you may use for generating |
584 | * random data. It also returns up to 32 bytes on its own of random data | |
585 | * that may be used; random_data_len may not be greater than 32. | |
c92e040d | 586 | */ |
186873c5 JD |
587 | static void crng_make_state(u32 chacha_state[CHACHA_STATE_WORDS], |
588 | u8 *random_data, size_t random_data_len) | |
c92e040d | 589 | { |
248045b8 | 590 | unsigned long flags; |
186873c5 | 591 | struct crng *crng; |
c92e040d | 592 | |
186873c5 JD |
593 | BUG_ON(random_data_len > 32); |
594 | ||
595 | /* | |
596 | * For the fast path, we check whether we're ready, unlocked first, and | |
597 | * then re-check once locked later. In the case where we're really not | |
598 | * ready, we do fast key erasure with the base_crng directly, because | |
599 | * this is what crng_{fast,slow}_load mutate during early init. | |
600 | */ | |
601 | if (unlikely(!crng_ready())) { | |
602 | bool ready; | |
603 | ||
604 | spin_lock_irqsave(&base_crng.lock, flags); | |
605 | ready = crng_ready(); | |
606 | if (!ready) | |
607 | crng_fast_key_erasure(base_crng.key, chacha_state, | |
608 | random_data, random_data_len); | |
609 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
610 | if (!ready) | |
611 | return; | |
c92e040d | 612 | } |
186873c5 JD |
613 | |
614 | /* | |
615 | * If the base_crng is more than 5 minutes old, we reseed, which | |
616 | * in turn bumps the generation counter that we check below. | |
617 | */ | |
618 | if (unlikely(time_after(jiffies, READ_ONCE(base_crng.birth) + CRNG_RESEED_INTERVAL))) | |
619 | crng_reseed(); | |
620 | ||
621 | local_lock_irqsave(&crngs.lock, flags); | |
622 | crng = raw_cpu_ptr(&crngs); | |
623 | ||
624 | /* | |
625 | * If our per-cpu crng is older than the base_crng, then it means | |
626 | * somebody reseeded the base_crng. In that case, we do fast key | |
627 | * erasure on the base_crng, and use its output as the new key | |
628 | * for our per-cpu crng. This brings us up to date with base_crng. | |
629 | */ | |
630 | if (unlikely(crng->generation != READ_ONCE(base_crng.generation))) { | |
631 | spin_lock(&base_crng.lock); | |
632 | crng_fast_key_erasure(base_crng.key, chacha_state, | |
633 | crng->key, sizeof(crng->key)); | |
634 | crng->generation = base_crng.generation; | |
635 | spin_unlock(&base_crng.lock); | |
636 | } | |
637 | ||
638 | /* | |
639 | * Finally, when we've made it this far, our per-cpu crng has an up | |
640 | * to date key, and we can do fast key erasure with it to produce | |
641 | * some random data and a ChaCha state for the caller. All other | |
642 | * branches of this function are "unlikely", so most of the time we | |
643 | * should wind up here immediately. | |
644 | */ | |
645 | crng_fast_key_erasure(crng->key, chacha_state, random_data, random_data_len); | |
646 | local_unlock_irqrestore(&crngs.lock, flags); | |
c92e040d TT |
647 | } |
648 | ||
186873c5 | 649 | static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes) |
e192be9d | 650 | { |
186873c5 | 651 | bool large_request = nbytes > 256; |
04ec96b7 JD |
652 | ssize_t ret = 0; |
653 | size_t len; | |
186873c5 JD |
654 | u32 chacha_state[CHACHA_STATE_WORDS]; |
655 | u8 output[CHACHA_BLOCK_SIZE]; | |
656 | ||
657 | if (!nbytes) | |
658 | return 0; | |
659 | ||
04ec96b7 | 660 | len = min_t(size_t, 32, nbytes); |
186873c5 JD |
661 | crng_make_state(chacha_state, output, len); |
662 | ||
663 | if (copy_to_user(buf, output, len)) | |
664 | return -EFAULT; | |
665 | nbytes -= len; | |
666 | buf += len; | |
667 | ret += len; | |
e192be9d TT |
668 | |
669 | while (nbytes) { | |
670 | if (large_request && need_resched()) { | |
186873c5 | 671 | if (signal_pending(current)) |
e192be9d | 672 | break; |
e192be9d TT |
673 | schedule(); |
674 | } | |
675 | ||
186873c5 JD |
676 | chacha20_block(chacha_state, output); |
677 | if (unlikely(chacha_state[12] == 0)) | |
678 | ++chacha_state[13]; | |
679 | ||
04ec96b7 | 680 | len = min_t(size_t, nbytes, CHACHA_BLOCK_SIZE); |
186873c5 | 681 | if (copy_to_user(buf, output, len)) { |
e192be9d TT |
682 | ret = -EFAULT; |
683 | break; | |
684 | } | |
685 | ||
186873c5 JD |
686 | nbytes -= len; |
687 | buf += len; | |
688 | ret += len; | |
e192be9d | 689 | } |
e192be9d | 690 | |
186873c5 JD |
691 | memzero_explicit(chacha_state, sizeof(chacha_state)); |
692 | memzero_explicit(output, sizeof(output)); | |
e192be9d TT |
693 | return ret; |
694 | } | |
695 | ||
1da177e4 LT |
696 | /********************************************************************* |
697 | * | |
698 | * Entropy input management | |
699 | * | |
700 | *********************************************************************/ | |
701 | ||
702 | /* There is one of these per entropy source */ | |
703 | struct timer_rand_state { | |
704 | cycles_t last_time; | |
90b75ee5 | 705 | long last_delta, last_delta2; |
1da177e4 LT |
706 | }; |
707 | ||
644008df TT |
708 | #define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, }; |
709 | ||
a2080a67 | 710 | /* |
e192be9d TT |
711 | * Add device- or boot-specific data to the input pool to help |
712 | * initialize it. | |
a2080a67 | 713 | * |
e192be9d TT |
714 | * None of this adds any entropy; it is meant to avoid the problem of |
715 | * the entropy pool having similar initial state across largely | |
716 | * identical devices. | |
a2080a67 | 717 | */ |
04ec96b7 | 718 | void add_device_randomness(const void *buf, size_t size) |
a2080a67 | 719 | { |
61875f30 | 720 | unsigned long time = random_get_entropy() ^ jiffies; |
3ef4cb2d | 721 | unsigned long flags; |
a2080a67 | 722 | |
dc12baac TT |
723 | if (!crng_ready() && size) |
724 | crng_slow_load(buf, size); | |
ee7998c5 | 725 | |
5910895f | 726 | trace_add_device_randomness(size, _RET_IP_); |
3ef4cb2d | 727 | spin_lock_irqsave(&input_pool.lock, flags); |
90ed1e67 JD |
728 | _mix_pool_bytes(buf, size); |
729 | _mix_pool_bytes(&time, sizeof(time)); | |
3ef4cb2d | 730 | spin_unlock_irqrestore(&input_pool.lock, flags); |
a2080a67 LT |
731 | } |
732 | EXPORT_SYMBOL(add_device_randomness); | |
733 | ||
644008df | 734 | static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE; |
3060d6fe | 735 | |
1da177e4 LT |
736 | /* |
737 | * This function adds entropy to the entropy "pool" by using timing | |
738 | * delays. It uses the timer_rand_state structure to make an estimate | |
739 | * of how many bits of entropy this call has added to the pool. | |
740 | * | |
741 | * The number "num" is also added to the pool - it should somehow describe | |
742 | * the type of event which just happened. This is currently 0-255 for | |
743 | * keyboard scan codes, and 256 upwards for interrupts. | |
744 | * | |
745 | */ | |
04ec96b7 | 746 | static void add_timer_randomness(struct timer_rand_state *state, unsigned int num) |
1da177e4 LT |
747 | { |
748 | struct { | |
1da177e4 | 749 | long jiffies; |
d38bb085 JD |
750 | unsigned int cycles; |
751 | unsigned int num; | |
1da177e4 LT |
752 | } sample; |
753 | long delta, delta2, delta3; | |
754 | ||
1da177e4 | 755 | sample.jiffies = jiffies; |
61875f30 | 756 | sample.cycles = random_get_entropy(); |
1da177e4 | 757 | sample.num = num; |
90ed1e67 | 758 | mix_pool_bytes(&sample, sizeof(sample)); |
1da177e4 LT |
759 | |
760 | /* | |
761 | * Calculate number of bits of randomness we probably added. | |
762 | * We take into account the first, second and third-order deltas | |
763 | * in order to make our estimate. | |
764 | */ | |
e00d996a QC |
765 | delta = sample.jiffies - READ_ONCE(state->last_time); |
766 | WRITE_ONCE(state->last_time, sample.jiffies); | |
5e747dd9 | 767 | |
e00d996a QC |
768 | delta2 = delta - READ_ONCE(state->last_delta); |
769 | WRITE_ONCE(state->last_delta, delta); | |
5e747dd9 | 770 | |
e00d996a QC |
771 | delta3 = delta2 - READ_ONCE(state->last_delta2); |
772 | WRITE_ONCE(state->last_delta2, delta2); | |
5e747dd9 RV |
773 | |
774 | if (delta < 0) | |
775 | delta = -delta; | |
776 | if (delta2 < 0) | |
777 | delta2 = -delta2; | |
778 | if (delta3 < 0) | |
779 | delta3 = -delta3; | |
780 | if (delta > delta2) | |
781 | delta = delta2; | |
782 | if (delta > delta3) | |
783 | delta = delta3; | |
1da177e4 | 784 | |
5e747dd9 RV |
785 | /* |
786 | * delta is now minimum absolute delta. | |
787 | * Round down by 1 bit on general principles, | |
727d499a | 788 | * and limit entropy estimate to 12 bits. |
5e747dd9 | 789 | */ |
04ec96b7 | 790 | credit_entropy_bits(min_t(unsigned int, fls(delta >> 1), 11)); |
1da177e4 LT |
791 | } |
792 | ||
d251575a | 793 | void add_input_randomness(unsigned int type, unsigned int code, |
248045b8 | 794 | unsigned int value) |
1da177e4 LT |
795 | { |
796 | static unsigned char last_value; | |
797 | ||
798 | /* ignore autorepeat and the like */ | |
799 | if (value == last_value) | |
800 | return; | |
801 | ||
1da177e4 LT |
802 | last_value = value; |
803 | add_timer_randomness(&input_timer_state, | |
804 | (type << 4) ^ code ^ (code >> 4) ^ value); | |
c5704490 | 805 | trace_add_input_randomness(input_pool.entropy_count); |
1da177e4 | 806 | } |
80fc9f53 | 807 | EXPORT_SYMBOL_GPL(add_input_randomness); |
1da177e4 | 808 | |
775f4b29 TT |
809 | static DEFINE_PER_CPU(struct fast_pool, irq_randomness); |
810 | ||
43759d4f TT |
811 | #ifdef ADD_INTERRUPT_BENCH |
812 | static unsigned long avg_cycles, avg_deviation; | |
813 | ||
248045b8 JD |
814 | #define AVG_SHIFT 8 /* Exponential average factor k=1/256 */ |
815 | #define FIXED_1_2 (1 << (AVG_SHIFT - 1)) | |
43759d4f TT |
816 | |
817 | static void add_interrupt_bench(cycles_t start) | |
818 | { | |
248045b8 | 819 | long delta = random_get_entropy() - start; |
43759d4f | 820 | |
248045b8 JD |
821 | /* Use a weighted moving average */ |
822 | delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT); | |
823 | avg_cycles += delta; | |
824 | /* And average deviation */ | |
825 | delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT); | |
826 | avg_deviation += delta; | |
43759d4f TT |
827 | } |
828 | #else | |
829 | #define add_interrupt_bench(x) | |
830 | #endif | |
831 | ||
d38bb085 | 832 | static u32 get_reg(struct fast_pool *f, struct pt_regs *regs) |
ee3e00e9 | 833 | { |
248045b8 | 834 | u32 *ptr = (u32 *)regs; |
92e75428 | 835 | unsigned int idx; |
ee3e00e9 TT |
836 | |
837 | if (regs == NULL) | |
838 | return 0; | |
92e75428 | 839 | idx = READ_ONCE(f->reg_idx); |
d38bb085 | 840 | if (idx >= sizeof(struct pt_regs) / sizeof(u32)) |
92e75428 TT |
841 | idx = 0; |
842 | ptr += idx++; | |
843 | WRITE_ONCE(f->reg_idx, idx); | |
9dfa7bba | 844 | return *ptr; |
ee3e00e9 TT |
845 | } |
846 | ||
703f7066 | 847 | void add_interrupt_randomness(int irq) |
1da177e4 | 848 | { |
248045b8 JD |
849 | struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness); |
850 | struct pt_regs *regs = get_irq_regs(); | |
851 | unsigned long now = jiffies; | |
852 | cycles_t cycles = random_get_entropy(); | |
853 | u32 c_high, j_high; | |
854 | u64 ip; | |
3060d6fe | 855 | |
ee3e00e9 TT |
856 | if (cycles == 0) |
857 | cycles = get_reg(fast_pool, regs); | |
655b2264 TT |
858 | c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0; |
859 | j_high = (sizeof(now) > 4) ? now >> 32 : 0; | |
43759d4f TT |
860 | fast_pool->pool[0] ^= cycles ^ j_high ^ irq; |
861 | fast_pool->pool[1] ^= now ^ c_high; | |
655b2264 | 862 | ip = regs ? instruction_pointer(regs) : _RET_IP_; |
43759d4f | 863 | fast_pool->pool[2] ^= ip; |
248045b8 JD |
864 | fast_pool->pool[3] ^= |
865 | (sizeof(ip) > 4) ? ip >> 32 : get_reg(fast_pool, regs); | |
3060d6fe | 866 | |
43759d4f | 867 | fast_mix(fast_pool); |
43759d4f | 868 | add_interrupt_bench(cycles); |
3060d6fe | 869 | |
43838a23 | 870 | if (unlikely(crng_init == 0)) { |
04ec96b7 JD |
871 | if (fast_pool->count >= 64 && |
872 | crng_fast_load(fast_pool->pool, sizeof(fast_pool->pool)) > 0) { | |
e192be9d TT |
873 | fast_pool->count = 0; |
874 | fast_pool->last = now; | |
c30c575d JD |
875 | if (spin_trylock(&input_pool.lock)) { |
876 | _mix_pool_bytes(&fast_pool->pool, sizeof(fast_pool->pool)); | |
877 | spin_unlock(&input_pool.lock); | |
878 | } | |
e192be9d TT |
879 | } |
880 | return; | |
881 | } | |
882 | ||
248045b8 | 883 | if ((fast_pool->count < 64) && !time_after(now, fast_pool->last + HZ)) |
1da177e4 LT |
884 | return; |
885 | ||
90ed1e67 | 886 | if (!spin_trylock(&input_pool.lock)) |
91fcb532 | 887 | return; |
83664a69 | 888 | |
91fcb532 | 889 | fast_pool->last = now; |
04ec96b7 | 890 | _mix_pool_bytes(&fast_pool->pool, sizeof(fast_pool->pool)); |
90ed1e67 | 891 | spin_unlock(&input_pool.lock); |
83664a69 | 892 | |
ee3e00e9 | 893 | fast_pool->count = 0; |
83664a69 | 894 | |
ee3e00e9 | 895 | /* award one bit for the contents of the fast pool */ |
90ed1e67 | 896 | credit_entropy_bits(1); |
1da177e4 | 897 | } |
4b44f2d1 | 898 | EXPORT_SYMBOL_GPL(add_interrupt_randomness); |
1da177e4 | 899 | |
9361401e | 900 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
901 | void add_disk_randomness(struct gendisk *disk) |
902 | { | |
903 | if (!disk || !disk->random) | |
904 | return; | |
905 | /* first major is 1, so we get >= 0x200 here */ | |
f331c029 | 906 | add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); |
c5704490 | 907 | trace_add_disk_randomness(disk_devt(disk), input_pool.entropy_count); |
1da177e4 | 908 | } |
bdcfa3e5 | 909 | EXPORT_SYMBOL_GPL(add_disk_randomness); |
9361401e | 910 | #endif |
1da177e4 | 911 | |
1da177e4 LT |
912 | /********************************************************************* |
913 | * | |
914 | * Entropy extraction routines | |
915 | * | |
916 | *********************************************************************/ | |
917 | ||
19fa5be1 | 918 | /* |
6e8ec255 JD |
919 | * This is an HKDF-like construction for using the hashed collected entropy |
920 | * as a PRF key, that's then expanded block-by-block. | |
19fa5be1 | 921 | */ |
9c07f578 | 922 | static void extract_entropy(void *buf, size_t nbytes) |
1da177e4 | 923 | { |
902c098a | 924 | unsigned long flags; |
6e8ec255 JD |
925 | u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE]; |
926 | struct { | |
28f425e5 | 927 | unsigned long rdseed[32 / sizeof(long)]; |
6e8ec255 JD |
928 | size_t counter; |
929 | } block; | |
930 | size_t i; | |
931 | ||
c5704490 | 932 | trace_extract_entropy(nbytes, input_pool.entropy_count); |
9c07f578 | 933 | |
28f425e5 JD |
934 | for (i = 0; i < ARRAY_SIZE(block.rdseed); ++i) { |
935 | if (!arch_get_random_seed_long(&block.rdseed[i]) && | |
936 | !arch_get_random_long(&block.rdseed[i])) | |
937 | block.rdseed[i] = random_get_entropy(); | |
85a1f777 TT |
938 | } |
939 | ||
90ed1e67 | 940 | spin_lock_irqsave(&input_pool.lock, flags); |
46884442 | 941 | |
6e8ec255 JD |
942 | /* seed = HASHPRF(last_key, entropy_input) */ |
943 | blake2s_final(&input_pool.hash, seed); | |
1da177e4 | 944 | |
28f425e5 | 945 | /* next_key = HASHPRF(seed, RDSEED || 0) */ |
6e8ec255 JD |
946 | block.counter = 0; |
947 | blake2s(next_key, (u8 *)&block, seed, sizeof(next_key), sizeof(block), sizeof(seed)); | |
948 | blake2s_init_key(&input_pool.hash, BLAKE2S_HASH_SIZE, next_key, sizeof(next_key)); | |
1da177e4 | 949 | |
6e8ec255 JD |
950 | spin_unlock_irqrestore(&input_pool.lock, flags); |
951 | memzero_explicit(next_key, sizeof(next_key)); | |
e192be9d TT |
952 | |
953 | while (nbytes) { | |
6e8ec255 | 954 | i = min_t(size_t, nbytes, BLAKE2S_HASH_SIZE); |
28f425e5 | 955 | /* output = HASHPRF(seed, RDSEED || ++counter) */ |
6e8ec255 JD |
956 | ++block.counter; |
957 | blake2s(buf, (u8 *)&block, seed, i, sizeof(block), sizeof(seed)); | |
e192be9d TT |
958 | nbytes -= i; |
959 | buf += i; | |
e192be9d TT |
960 | } |
961 | ||
6e8ec255 JD |
962 | memzero_explicit(seed, sizeof(seed)); |
963 | memzero_explicit(&block, sizeof(block)); | |
e192be9d TT |
964 | } |
965 | ||
eecabf56 | 966 | #define warn_unseeded_randomness(previous) \ |
248045b8 | 967 | _warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous)) |
eecabf56 | 968 | |
248045b8 | 969 | static void _warn_unseeded_randomness(const char *func_name, void *caller, void **previous) |
eecabf56 TT |
970 | { |
971 | #ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM | |
972 | const bool print_once = false; | |
973 | #else | |
974 | static bool print_once __read_mostly; | |
975 | #endif | |
976 | ||
248045b8 | 977 | if (print_once || crng_ready() || |
eecabf56 TT |
978 | (previous && (caller == READ_ONCE(*previous)))) |
979 | return; | |
980 | WRITE_ONCE(*previous, caller); | |
981 | #ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM | |
982 | print_once = true; | |
983 | #endif | |
4e00b339 | 984 | if (__ratelimit(&unseeded_warning)) |
248045b8 JD |
985 | printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n", |
986 | func_name, caller, crng_init); | |
eecabf56 TT |
987 | } |
988 | ||
1da177e4 LT |
989 | /* |
990 | * This function is the exported kernel interface. It returns some | |
c2557a30 | 991 | * number of good random numbers, suitable for key generation, seeding |
18e9cea7 GP |
992 | * TCP sequence numbers, etc. It does not rely on the hardware random |
993 | * number generator. For random bytes direct from the hardware RNG | |
e297a783 JD |
994 | * (when available), use get_random_bytes_arch(). In order to ensure |
995 | * that the randomness provided by this function is okay, the function | |
996 | * wait_for_random_bytes() should be called and return 0 at least once | |
997 | * at any point prior. | |
1da177e4 | 998 | */ |
04ec96b7 | 999 | static void _get_random_bytes(void *buf, size_t nbytes) |
c2557a30 | 1000 | { |
186873c5 JD |
1001 | u32 chacha_state[CHACHA_STATE_WORDS]; |
1002 | u8 tmp[CHACHA_BLOCK_SIZE]; | |
04ec96b7 | 1003 | size_t len; |
e192be9d | 1004 | |
5910895f | 1005 | trace_get_random_bytes(nbytes, _RET_IP_); |
e192be9d | 1006 | |
186873c5 JD |
1007 | if (!nbytes) |
1008 | return; | |
1009 | ||
04ec96b7 | 1010 | len = min_t(size_t, 32, nbytes); |
186873c5 JD |
1011 | crng_make_state(chacha_state, buf, len); |
1012 | nbytes -= len; | |
1013 | buf += len; | |
1014 | ||
1015 | while (nbytes) { | |
1016 | if (nbytes < CHACHA_BLOCK_SIZE) { | |
1017 | chacha20_block(chacha_state, tmp); | |
1018 | memcpy(buf, tmp, nbytes); | |
1019 | memzero_explicit(tmp, sizeof(tmp)); | |
1020 | break; | |
1021 | } | |
1022 | ||
1023 | chacha20_block(chacha_state, buf); | |
1024 | if (unlikely(chacha_state[12] == 0)) | |
1025 | ++chacha_state[13]; | |
1ca1b917 | 1026 | nbytes -= CHACHA_BLOCK_SIZE; |
186873c5 | 1027 | buf += CHACHA_BLOCK_SIZE; |
e192be9d TT |
1028 | } |
1029 | ||
186873c5 | 1030 | memzero_explicit(chacha_state, sizeof(chacha_state)); |
c2557a30 | 1031 | } |
eecabf56 | 1032 | |
04ec96b7 | 1033 | void get_random_bytes(void *buf, size_t nbytes) |
eecabf56 TT |
1034 | { |
1035 | static void *previous; | |
1036 | ||
1037 | warn_unseeded_randomness(&previous); | |
1038 | _get_random_bytes(buf, nbytes); | |
1039 | } | |
c2557a30 TT |
1040 | EXPORT_SYMBOL(get_random_bytes); |
1041 | ||
50ee7529 LT |
1042 | /* |
1043 | * Each time the timer fires, we expect that we got an unpredictable | |
1044 | * jump in the cycle counter. Even if the timer is running on another | |
1045 | * CPU, the timer activity will be touching the stack of the CPU that is | |
1046 | * generating entropy.. | |
1047 | * | |
1048 | * Note that we don't re-arm the timer in the timer itself - we are | |
1049 | * happy to be scheduled away, since that just makes the load more | |
1050 | * complex, but we do not want the timer to keep ticking unless the | |
1051 | * entropy loop is running. | |
1052 | * | |
1053 | * So the re-arming always happens in the entropy loop itself. | |
1054 | */ | |
1055 | static void entropy_timer(struct timer_list *t) | |
1056 | { | |
90ed1e67 | 1057 | credit_entropy_bits(1); |
50ee7529 LT |
1058 | } |
1059 | ||
1060 | /* | |
1061 | * If we have an actual cycle counter, see if we can | |
1062 | * generate enough entropy with timing noise | |
1063 | */ | |
1064 | static void try_to_generate_entropy(void) | |
1065 | { | |
1066 | struct { | |
1067 | unsigned long now; | |
1068 | struct timer_list timer; | |
1069 | } stack; | |
1070 | ||
1071 | stack.now = random_get_entropy(); | |
1072 | ||
1073 | /* Slow counter - or none. Don't even bother */ | |
1074 | if (stack.now == random_get_entropy()) | |
1075 | return; | |
1076 | ||
1077 | timer_setup_on_stack(&stack.timer, entropy_timer, 0); | |
1078 | while (!crng_ready()) { | |
1079 | if (!timer_pending(&stack.timer)) | |
248045b8 | 1080 | mod_timer(&stack.timer, jiffies + 1); |
90ed1e67 | 1081 | mix_pool_bytes(&stack.now, sizeof(stack.now)); |
50ee7529 LT |
1082 | schedule(); |
1083 | stack.now = random_get_entropy(); | |
1084 | } | |
1085 | ||
1086 | del_timer_sync(&stack.timer); | |
1087 | destroy_timer_on_stack(&stack.timer); | |
90ed1e67 | 1088 | mix_pool_bytes(&stack.now, sizeof(stack.now)); |
50ee7529 LT |
1089 | } |
1090 | ||
e297a783 JD |
1091 | /* |
1092 | * Wait for the urandom pool to be seeded and thus guaranteed to supply | |
1093 | * cryptographically secure random numbers. This applies to: the /dev/urandom | |
1094 | * device, the get_random_bytes function, and the get_random_{u32,u64,int,long} | |
1095 | * family of functions. Using any of these functions without first calling | |
1096 | * this function forfeits the guarantee of security. | |
1097 | * | |
1098 | * Returns: 0 if the urandom pool has been seeded. | |
1099 | * -ERESTARTSYS if the function was interrupted by a signal. | |
1100 | */ | |
1101 | int wait_for_random_bytes(void) | |
1102 | { | |
1103 | if (likely(crng_ready())) | |
1104 | return 0; | |
50ee7529 LT |
1105 | |
1106 | do { | |
1107 | int ret; | |
1108 | ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ); | |
1109 | if (ret) | |
1110 | return ret > 0 ? 0 : ret; | |
1111 | ||
1112 | try_to_generate_entropy(); | |
1113 | } while (!crng_ready()); | |
1114 | ||
1115 | return 0; | |
e297a783 JD |
1116 | } |
1117 | EXPORT_SYMBOL(wait_for_random_bytes); | |
1118 | ||
9a47249d JD |
1119 | /* |
1120 | * Returns whether or not the urandom pool has been seeded and thus guaranteed | |
1121 | * to supply cryptographically secure random numbers. This applies to: the | |
1122 | * /dev/urandom device, the get_random_bytes function, and the get_random_{u32, | |
1123 | * ,u64,int,long} family of functions. | |
1124 | * | |
1125 | * Returns: true if the urandom pool has been seeded. | |
1126 | * false if the urandom pool has not been seeded. | |
1127 | */ | |
1128 | bool rng_is_initialized(void) | |
1129 | { | |
1130 | return crng_ready(); | |
1131 | } | |
1132 | EXPORT_SYMBOL(rng_is_initialized); | |
1133 | ||
205a525c HX |
1134 | /* |
1135 | * Add a callback function that will be invoked when the nonblocking | |
1136 | * pool is initialised. | |
1137 | * | |
1138 | * returns: 0 if callback is successfully added | |
1139 | * -EALREADY if pool is already initialised (callback not called) | |
1140 | * -ENOENT if module for callback is not alive | |
1141 | */ | |
1142 | int add_random_ready_callback(struct random_ready_callback *rdy) | |
1143 | { | |
1144 | struct module *owner; | |
1145 | unsigned long flags; | |
1146 | int err = -EALREADY; | |
1147 | ||
e192be9d | 1148 | if (crng_ready()) |
205a525c HX |
1149 | return err; |
1150 | ||
1151 | owner = rdy->owner; | |
1152 | if (!try_module_get(owner)) | |
1153 | return -ENOENT; | |
1154 | ||
1155 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
e192be9d | 1156 | if (crng_ready()) |
205a525c HX |
1157 | goto out; |
1158 | ||
1159 | owner = NULL; | |
1160 | ||
1161 | list_add(&rdy->list, &random_ready_list); | |
1162 | err = 0; | |
1163 | ||
1164 | out: | |
1165 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
1166 | ||
1167 | module_put(owner); | |
1168 | ||
1169 | return err; | |
1170 | } | |
1171 | EXPORT_SYMBOL(add_random_ready_callback); | |
1172 | ||
1173 | /* | |
1174 | * Delete a previously registered readiness callback function. | |
1175 | */ | |
1176 | void del_random_ready_callback(struct random_ready_callback *rdy) | |
1177 | { | |
1178 | unsigned long flags; | |
1179 | struct module *owner = NULL; | |
1180 | ||
1181 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
1182 | if (!list_empty(&rdy->list)) { | |
1183 | list_del_init(&rdy->list); | |
1184 | owner = rdy->owner; | |
1185 | } | |
1186 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
1187 | ||
1188 | module_put(owner); | |
1189 | } | |
1190 | EXPORT_SYMBOL(del_random_ready_callback); | |
1191 | ||
c2557a30 TT |
1192 | /* |
1193 | * This function will use the architecture-specific hardware random | |
04ec96b7 JD |
1194 | * number generator if it is available. It is not recommended for |
1195 | * use. Use get_random_bytes() instead. It returns the number of | |
1196 | * bytes filled in. | |
c2557a30 | 1197 | */ |
04ec96b7 | 1198 | size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes) |
1da177e4 | 1199 | { |
04ec96b7 | 1200 | size_t left = nbytes; |
d38bb085 | 1201 | u8 *p = buf; |
63d77173 | 1202 | |
753d433b TH |
1203 | trace_get_random_bytes_arch(left, _RET_IP_); |
1204 | while (left) { | |
63d77173 | 1205 | unsigned long v; |
04ec96b7 | 1206 | size_t chunk = min_t(size_t, left, sizeof(unsigned long)); |
c2557a30 | 1207 | |
63d77173 PA |
1208 | if (!arch_get_random_long(&v)) |
1209 | break; | |
8ddd6efa | 1210 | |
bd29e568 | 1211 | memcpy(p, &v, chunk); |
63d77173 | 1212 | p += chunk; |
753d433b | 1213 | left -= chunk; |
63d77173 PA |
1214 | } |
1215 | ||
753d433b | 1216 | return nbytes - left; |
1da177e4 | 1217 | } |
c2557a30 TT |
1218 | EXPORT_SYMBOL(get_random_bytes_arch); |
1219 | ||
85664172 JD |
1220 | static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU); |
1221 | static int __init parse_trust_cpu(char *arg) | |
1222 | { | |
1223 | return kstrtobool(arg, &trust_cpu); | |
1224 | } | |
1225 | early_param("random.trust_cpu", parse_trust_cpu); | |
1226 | ||
1da177e4 | 1227 | /* |
85664172 JD |
1228 | * Note that setup_arch() may call add_device_randomness() |
1229 | * long before we get here. This allows seeding of the pools | |
1230 | * with some platform dependent data very early in the boot | |
1231 | * process. But it limits our options here. We must use | |
1232 | * statically allocated structures that already have all | |
1233 | * initializations complete at compile time. We should also | |
1234 | * take care not to overwrite the precious per platform data | |
1235 | * we were given. | |
1da177e4 | 1236 | */ |
85664172 | 1237 | int __init rand_initialize(void) |
1da177e4 | 1238 | { |
04ec96b7 | 1239 | size_t i; |
902c098a | 1240 | ktime_t now = ktime_get_real(); |
85664172 | 1241 | bool arch_init = true; |
902c098a | 1242 | unsigned long rv; |
1da177e4 | 1243 | |
04ec96b7 | 1244 | for (i = 0; i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) { |
85664172 JD |
1245 | if (!arch_get_random_seed_long_early(&rv) && |
1246 | !arch_get_random_long_early(&rv)) { | |
1247 | rv = random_get_entropy(); | |
1248 | arch_init = false; | |
1249 | } | |
a02cf3d0 | 1250 | mix_pool_bytes(&rv, sizeof(rv)); |
85664172 | 1251 | } |
a02cf3d0 JD |
1252 | mix_pool_bytes(&now, sizeof(now)); |
1253 | mix_pool_bytes(utsname(), sizeof(*(utsname()))); | |
1254 | ||
186873c5 | 1255 | extract_entropy(base_crng.key, sizeof(base_crng.key)); |
85664172 JD |
1256 | if (arch_init && trust_cpu && crng_init < 2) { |
1257 | invalidate_batched_entropy(); | |
1258 | crng_init = 2; | |
1259 | pr_notice("crng init done (trusting CPU's manufacturer)\n"); | |
1260 | } | |
85664172 | 1261 | |
4e00b339 TT |
1262 | if (ratelimit_disable) { |
1263 | urandom_warning.interval = 0; | |
1264 | unseeded_warning.interval = 0; | |
1265 | } | |
1da177e4 LT |
1266 | return 0; |
1267 | } | |
1da177e4 | 1268 | |
9361401e | 1269 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1270 | void rand_initialize_disk(struct gendisk *disk) |
1271 | { | |
1272 | struct timer_rand_state *state; | |
1273 | ||
1274 | /* | |
f8595815 | 1275 | * If kzalloc returns null, we just won't use that entropy |
1da177e4 LT |
1276 | * source. |
1277 | */ | |
f8595815 | 1278 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
644008df TT |
1279 | if (state) { |
1280 | state->last_time = INITIAL_JIFFIES; | |
1da177e4 | 1281 | disk->random = state; |
644008df | 1282 | } |
1da177e4 | 1283 | } |
9361401e | 1284 | #endif |
1da177e4 | 1285 | |
248045b8 JD |
1286 | static ssize_t urandom_read_nowarn(struct file *file, char __user *buf, |
1287 | size_t nbytes, loff_t *ppos) | |
c6f1deb1 | 1288 | { |
434537ae | 1289 | ssize_t ret; |
c6f1deb1 | 1290 | |
186873c5 | 1291 | ret = get_random_bytes_user(buf, nbytes); |
04ec96b7 | 1292 | trace_urandom_read(nbytes, input_pool.entropy_count); |
c6f1deb1 AL |
1293 | return ret; |
1294 | } | |
1295 | ||
248045b8 JD |
1296 | static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes, |
1297 | loff_t *ppos) | |
1da177e4 | 1298 | { |
9b4d0087 | 1299 | static int maxwarn = 10; |
301f0595 | 1300 | |
e192be9d | 1301 | if (!crng_ready() && maxwarn > 0) { |
9b4d0087 | 1302 | maxwarn--; |
4e00b339 | 1303 | if (__ratelimit(&urandom_warning)) |
12cd53af YL |
1304 | pr_notice("%s: uninitialized urandom read (%zd bytes read)\n", |
1305 | current->comm, nbytes); | |
9b4d0087 | 1306 | } |
c6f1deb1 AL |
1307 | |
1308 | return urandom_read_nowarn(file, buf, nbytes, ppos); | |
1da177e4 LT |
1309 | } |
1310 | ||
248045b8 JD |
1311 | static ssize_t random_read(struct file *file, char __user *buf, size_t nbytes, |
1312 | loff_t *ppos) | |
30c08efe AL |
1313 | { |
1314 | int ret; | |
1315 | ||
1316 | ret = wait_for_random_bytes(); | |
1317 | if (ret != 0) | |
1318 | return ret; | |
1319 | return urandom_read_nowarn(file, buf, nbytes, ppos); | |
1320 | } | |
1321 | ||
248045b8 | 1322 | static __poll_t random_poll(struct file *file, poll_table *wait) |
1da177e4 | 1323 | { |
a11e1d43 | 1324 | __poll_t mask; |
1da177e4 | 1325 | |
30c08efe | 1326 | poll_wait(file, &crng_init_wait, wait); |
a11e1d43 LT |
1327 | poll_wait(file, &random_write_wait, wait); |
1328 | mask = 0; | |
30c08efe | 1329 | if (crng_ready()) |
a9a08845 | 1330 | mask |= EPOLLIN | EPOLLRDNORM; |
489c7fc4 | 1331 | if (input_pool.entropy_count < POOL_MIN_BITS) |
a9a08845 | 1332 | mask |= EPOLLOUT | EPOLLWRNORM; |
1da177e4 LT |
1333 | return mask; |
1334 | } | |
1335 | ||
04ec96b7 | 1336 | static int write_pool(const char __user *ubuf, size_t count) |
1da177e4 | 1337 | { |
04ec96b7 | 1338 | size_t len; |
7b5164fb | 1339 | int ret = 0; |
04ec96b7 | 1340 | u8 block[BLAKE2S_BLOCK_SIZE]; |
1da177e4 | 1341 | |
04ec96b7 JD |
1342 | while (count) { |
1343 | len = min(count, sizeof(block)); | |
7b5164fb JD |
1344 | if (copy_from_user(block, ubuf, len)) { |
1345 | ret = -EFAULT; | |
1346 | goto out; | |
1347 | } | |
04ec96b7 JD |
1348 | count -= len; |
1349 | ubuf += len; | |
1350 | mix_pool_bytes(block, len); | |
91f3f1e3 | 1351 | cond_resched(); |
1da177e4 | 1352 | } |
7f397dcd | 1353 | |
7b5164fb JD |
1354 | out: |
1355 | memzero_explicit(block, sizeof(block)); | |
1356 | return ret; | |
7f397dcd MM |
1357 | } |
1358 | ||
90b75ee5 MM |
1359 | static ssize_t random_write(struct file *file, const char __user *buffer, |
1360 | size_t count, loff_t *ppos) | |
7f397dcd | 1361 | { |
04ec96b7 | 1362 | int ret; |
7f397dcd | 1363 | |
90ed1e67 | 1364 | ret = write_pool(buffer, count); |
7f397dcd MM |
1365 | if (ret) |
1366 | return ret; | |
1367 | ||
7f397dcd | 1368 | return (ssize_t)count; |
1da177e4 LT |
1369 | } |
1370 | ||
43ae4860 | 1371 | static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) |
1da177e4 LT |
1372 | { |
1373 | int size, ent_count; | |
1374 | int __user *p = (int __user *)arg; | |
1375 | int retval; | |
1376 | ||
1377 | switch (cmd) { | |
1378 | case RNDGETENTCNT: | |
43ae4860 | 1379 | /* inherently racy, no point locking */ |
c5704490 | 1380 | if (put_user(input_pool.entropy_count, p)) |
1da177e4 LT |
1381 | return -EFAULT; |
1382 | return 0; | |
1383 | case RNDADDTOENTCNT: | |
1384 | if (!capable(CAP_SYS_ADMIN)) | |
1385 | return -EPERM; | |
1386 | if (get_user(ent_count, p)) | |
1387 | return -EFAULT; | |
a49c010e JD |
1388 | if (ent_count < 0) |
1389 | return -EINVAL; | |
1390 | credit_entropy_bits(ent_count); | |
1391 | return 0; | |
1da177e4 LT |
1392 | case RNDADDENTROPY: |
1393 | if (!capable(CAP_SYS_ADMIN)) | |
1394 | return -EPERM; | |
1395 | if (get_user(ent_count, p++)) | |
1396 | return -EFAULT; | |
1397 | if (ent_count < 0) | |
1398 | return -EINVAL; | |
1399 | if (get_user(size, p++)) | |
1400 | return -EFAULT; | |
90ed1e67 | 1401 | retval = write_pool((const char __user *)p, size); |
1da177e4 LT |
1402 | if (retval < 0) |
1403 | return retval; | |
a49c010e JD |
1404 | credit_entropy_bits(ent_count); |
1405 | return 0; | |
1da177e4 LT |
1406 | case RNDZAPENTCNT: |
1407 | case RNDCLEARPOOL: | |
ae9ecd92 TT |
1408 | /* |
1409 | * Clear the entropy pool counters. We no longer clear | |
1410 | * the entropy pool, as that's silly. | |
1411 | */ | |
1da177e4 LT |
1412 | if (!capable(CAP_SYS_ADMIN)) |
1413 | return -EPERM; | |
489c7fc4 | 1414 | if (xchg(&input_pool.entropy_count, 0)) { |
042e293e JD |
1415 | wake_up_interruptible(&random_write_wait); |
1416 | kill_fasync(&fasync, SIGIO, POLL_OUT); | |
1417 | } | |
1da177e4 | 1418 | return 0; |
d848e5f8 TT |
1419 | case RNDRESEEDCRNG: |
1420 | if (!capable(CAP_SYS_ADMIN)) | |
1421 | return -EPERM; | |
1422 | if (crng_init < 2) | |
1423 | return -ENODATA; | |
a9412d51 | 1424 | crng_reseed(); |
d848e5f8 | 1425 | return 0; |
1da177e4 LT |
1426 | default: |
1427 | return -EINVAL; | |
1428 | } | |
1429 | } | |
1430 | ||
9a6f70bb JD |
1431 | static int random_fasync(int fd, struct file *filp, int on) |
1432 | { | |
1433 | return fasync_helper(fd, filp, on, &fasync); | |
1434 | } | |
1435 | ||
2b8693c0 | 1436 | const struct file_operations random_fops = { |
248045b8 | 1437 | .read = random_read, |
1da177e4 | 1438 | .write = random_write, |
248045b8 | 1439 | .poll = random_poll, |
43ae4860 | 1440 | .unlocked_ioctl = random_ioctl, |
507e4e2b | 1441 | .compat_ioctl = compat_ptr_ioctl, |
9a6f70bb | 1442 | .fasync = random_fasync, |
6038f373 | 1443 | .llseek = noop_llseek, |
1da177e4 LT |
1444 | }; |
1445 | ||
2b8693c0 | 1446 | const struct file_operations urandom_fops = { |
248045b8 | 1447 | .read = urandom_read, |
1da177e4 | 1448 | .write = random_write, |
43ae4860 | 1449 | .unlocked_ioctl = random_ioctl, |
4aa37c46 | 1450 | .compat_ioctl = compat_ptr_ioctl, |
9a6f70bb | 1451 | .fasync = random_fasync, |
6038f373 | 1452 | .llseek = noop_llseek, |
1da177e4 LT |
1453 | }; |
1454 | ||
248045b8 JD |
1455 | SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int, |
1456 | flags) | |
c6e9d6f3 | 1457 | { |
248045b8 | 1458 | if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE)) |
75551dbf AL |
1459 | return -EINVAL; |
1460 | ||
1461 | /* | |
1462 | * Requesting insecure and blocking randomness at the same time makes | |
1463 | * no sense. | |
1464 | */ | |
248045b8 | 1465 | if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM)) |
c6e9d6f3 TT |
1466 | return -EINVAL; |
1467 | ||
1468 | if (count > INT_MAX) | |
1469 | count = INT_MAX; | |
1470 | ||
75551dbf | 1471 | if (!(flags & GRND_INSECURE) && !crng_ready()) { |
04ec96b7 JD |
1472 | int ret; |
1473 | ||
c6e9d6f3 TT |
1474 | if (flags & GRND_NONBLOCK) |
1475 | return -EAGAIN; | |
e297a783 JD |
1476 | ret = wait_for_random_bytes(); |
1477 | if (unlikely(ret)) | |
1478 | return ret; | |
c6e9d6f3 | 1479 | } |
c6f1deb1 | 1480 | return urandom_read_nowarn(NULL, buf, count, NULL); |
c6e9d6f3 TT |
1481 | } |
1482 | ||
1da177e4 LT |
1483 | /******************************************************************** |
1484 | * | |
1485 | * Sysctl interface | |
1486 | * | |
1487 | ********************************************************************/ | |
1488 | ||
1489 | #ifdef CONFIG_SYSCTL | |
1490 | ||
1491 | #include <linux/sysctl.h> | |
1492 | ||
db61ffe3 | 1493 | static int random_min_urandom_seed = 60; |
489c7fc4 JD |
1494 | static int random_write_wakeup_bits = POOL_MIN_BITS; |
1495 | static int sysctl_poolsize = POOL_BITS; | |
1da177e4 LT |
1496 | static char sysctl_bootid[16]; |
1497 | ||
1498 | /* | |
f22052b2 | 1499 | * This function is used to return both the bootid UUID, and random |
1da177e4 LT |
1500 | * UUID. The difference is in whether table->data is NULL; if it is, |
1501 | * then a new UUID is generated and returned to the user. | |
1502 | * | |
f22052b2 GP |
1503 | * If the user accesses this via the proc interface, the UUID will be |
1504 | * returned as an ASCII string in the standard UUID format; if via the | |
1505 | * sysctl system call, as 16 bytes of binary data. | |
1da177e4 | 1506 | */ |
248045b8 JD |
1507 | static int proc_do_uuid(struct ctl_table *table, int write, void *buffer, |
1508 | size_t *lenp, loff_t *ppos) | |
1da177e4 | 1509 | { |
a151427e | 1510 | struct ctl_table fake_table; |
1da177e4 LT |
1511 | unsigned char buf[64], tmp_uuid[16], *uuid; |
1512 | ||
1513 | uuid = table->data; | |
1514 | if (!uuid) { | |
1515 | uuid = tmp_uuid; | |
1da177e4 | 1516 | generate_random_uuid(uuid); |
44e4360f MD |
1517 | } else { |
1518 | static DEFINE_SPINLOCK(bootid_spinlock); | |
1519 | ||
1520 | spin_lock(&bootid_spinlock); | |
1521 | if (!uuid[8]) | |
1522 | generate_random_uuid(uuid); | |
1523 | spin_unlock(&bootid_spinlock); | |
1524 | } | |
1da177e4 | 1525 | |
35900771 JP |
1526 | sprintf(buf, "%pU", uuid); |
1527 | ||
1da177e4 LT |
1528 | fake_table.data = buf; |
1529 | fake_table.maxlen = sizeof(buf); | |
1530 | ||
8d65af78 | 1531 | return proc_dostring(&fake_table, write, buffer, lenp, ppos); |
1da177e4 LT |
1532 | } |
1533 | ||
5475e8f0 | 1534 | static struct ctl_table random_table[] = { |
1da177e4 | 1535 | { |
1da177e4 LT |
1536 | .procname = "poolsize", |
1537 | .data = &sysctl_poolsize, | |
1538 | .maxlen = sizeof(int), | |
1539 | .mode = 0444, | |
6d456111 | 1540 | .proc_handler = proc_dointvec, |
1da177e4 LT |
1541 | }, |
1542 | { | |
1da177e4 | 1543 | .procname = "entropy_avail", |
c5704490 | 1544 | .data = &input_pool.entropy_count, |
1da177e4 LT |
1545 | .maxlen = sizeof(int), |
1546 | .mode = 0444, | |
c5704490 | 1547 | .proc_handler = proc_dointvec, |
1da177e4 | 1548 | }, |
1da177e4 | 1549 | { |
1da177e4 | 1550 | .procname = "write_wakeup_threshold", |
2132a96f | 1551 | .data = &random_write_wakeup_bits, |
1da177e4 LT |
1552 | .maxlen = sizeof(int), |
1553 | .mode = 0644, | |
489c7fc4 | 1554 | .proc_handler = proc_dointvec, |
1da177e4 | 1555 | }, |
f5c2742c TT |
1556 | { |
1557 | .procname = "urandom_min_reseed_secs", | |
1558 | .data = &random_min_urandom_seed, | |
1559 | .maxlen = sizeof(int), | |
1560 | .mode = 0644, | |
1561 | .proc_handler = proc_dointvec, | |
1562 | }, | |
1da177e4 | 1563 | { |
1da177e4 LT |
1564 | .procname = "boot_id", |
1565 | .data = &sysctl_bootid, | |
1566 | .maxlen = 16, | |
1567 | .mode = 0444, | |
6d456111 | 1568 | .proc_handler = proc_do_uuid, |
1da177e4 LT |
1569 | }, |
1570 | { | |
1da177e4 LT |
1571 | .procname = "uuid", |
1572 | .maxlen = 16, | |
1573 | .mode = 0444, | |
6d456111 | 1574 | .proc_handler = proc_do_uuid, |
1da177e4 | 1575 | }, |
43759d4f TT |
1576 | #ifdef ADD_INTERRUPT_BENCH |
1577 | { | |
1578 | .procname = "add_interrupt_avg_cycles", | |
1579 | .data = &avg_cycles, | |
1580 | .maxlen = sizeof(avg_cycles), | |
1581 | .mode = 0444, | |
1582 | .proc_handler = proc_doulongvec_minmax, | |
1583 | }, | |
1584 | { | |
1585 | .procname = "add_interrupt_avg_deviation", | |
1586 | .data = &avg_deviation, | |
1587 | .maxlen = sizeof(avg_deviation), | |
1588 | .mode = 0444, | |
1589 | .proc_handler = proc_doulongvec_minmax, | |
1590 | }, | |
1591 | #endif | |
894d2491 | 1592 | { } |
1da177e4 | 1593 | }; |
5475e8f0 XN |
1594 | |
1595 | /* | |
1596 | * rand_initialize() is called before sysctl_init(), | |
1597 | * so we cannot call register_sysctl_init() in rand_initialize() | |
1598 | */ | |
1599 | static int __init random_sysctls_init(void) | |
1600 | { | |
1601 | register_sysctl_init("kernel/random", random_table); | |
1602 | return 0; | |
1603 | } | |
1604 | device_initcall(random_sysctls_init); | |
248045b8 | 1605 | #endif /* CONFIG_SYSCTL */ |
1da177e4 | 1606 | |
77760fd7 JD |
1607 | static atomic_t batch_generation = ATOMIC_INIT(0); |
1608 | ||
f5b98461 JD |
1609 | struct batched_entropy { |
1610 | union { | |
186873c5 JD |
1611 | /* |
1612 | * We make this 1.5x a ChaCha block, so that we get the | |
1613 | * remaining 32 bytes from fast key erasure, plus one full | |
1614 | * block from the detached ChaCha state. We can increase | |
1615 | * the size of this later if needed so long as we keep the | |
1616 | * formula of (integer_blocks + 0.5) * CHACHA_BLOCK_SIZE. | |
1617 | */ | |
1618 | u64 entropy_u64[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u64))]; | |
1619 | u32 entropy_u32[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u32))]; | |
f5b98461 | 1620 | }; |
77760fd7 | 1621 | local_lock_t lock; |
f5b98461 | 1622 | unsigned int position; |
77760fd7 | 1623 | int generation; |
f5b98461 | 1624 | }; |
b1132dea | 1625 | |
1da177e4 | 1626 | /* |
f5b98461 | 1627 | * Get a random word for internal kernel use only. The quality of the random |
186873c5 JD |
1628 | * number is good as /dev/urandom. In order to ensure that the randomness |
1629 | * provided by this function is okay, the function wait_for_random_bytes() | |
1630 | * should be called and return 0 at least once at any point prior. | |
1da177e4 | 1631 | */ |
b7d5dc21 | 1632 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = { |
186873c5 JD |
1633 | .lock = INIT_LOCAL_LOCK(batched_entropy_u64.lock), |
1634 | .position = UINT_MAX | |
b7d5dc21 SAS |
1635 | }; |
1636 | ||
c440408c | 1637 | u64 get_random_u64(void) |
1da177e4 | 1638 | { |
c440408c | 1639 | u64 ret; |
b7d5dc21 | 1640 | unsigned long flags; |
f5b98461 | 1641 | struct batched_entropy *batch; |
eecabf56 | 1642 | static void *previous; |
77760fd7 | 1643 | int next_gen; |
8a0a9bd4 | 1644 | |
eecabf56 | 1645 | warn_unseeded_randomness(&previous); |
d06bfd19 | 1646 | |
77760fd7 | 1647 | local_lock_irqsave(&batched_entropy_u64.lock, flags); |
b7d5dc21 | 1648 | batch = raw_cpu_ptr(&batched_entropy_u64); |
77760fd7 JD |
1649 | |
1650 | next_gen = atomic_read(&batch_generation); | |
186873c5 | 1651 | if (batch->position >= ARRAY_SIZE(batch->entropy_u64) || |
77760fd7 | 1652 | next_gen != batch->generation) { |
186873c5 | 1653 | _get_random_bytes(batch->entropy_u64, sizeof(batch->entropy_u64)); |
f5b98461 | 1654 | batch->position = 0; |
77760fd7 | 1655 | batch->generation = next_gen; |
f5b98461 | 1656 | } |
77760fd7 | 1657 | |
186873c5 JD |
1658 | ret = batch->entropy_u64[batch->position]; |
1659 | batch->entropy_u64[batch->position] = 0; | |
1660 | ++batch->position; | |
77760fd7 | 1661 | local_unlock_irqrestore(&batched_entropy_u64.lock, flags); |
8a0a9bd4 | 1662 | return ret; |
1da177e4 | 1663 | } |
c440408c | 1664 | EXPORT_SYMBOL(get_random_u64); |
1da177e4 | 1665 | |
b7d5dc21 | 1666 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = { |
186873c5 JD |
1667 | .lock = INIT_LOCAL_LOCK(batched_entropy_u32.lock), |
1668 | .position = UINT_MAX | |
b7d5dc21 | 1669 | }; |
77760fd7 | 1670 | |
c440408c | 1671 | u32 get_random_u32(void) |
f5b98461 | 1672 | { |
c440408c | 1673 | u32 ret; |
b7d5dc21 | 1674 | unsigned long flags; |
f5b98461 | 1675 | struct batched_entropy *batch; |
eecabf56 | 1676 | static void *previous; |
77760fd7 | 1677 | int next_gen; |
ec9ee4ac | 1678 | |
eecabf56 | 1679 | warn_unseeded_randomness(&previous); |
d06bfd19 | 1680 | |
77760fd7 | 1681 | local_lock_irqsave(&batched_entropy_u32.lock, flags); |
b7d5dc21 | 1682 | batch = raw_cpu_ptr(&batched_entropy_u32); |
77760fd7 JD |
1683 | |
1684 | next_gen = atomic_read(&batch_generation); | |
186873c5 | 1685 | if (batch->position >= ARRAY_SIZE(batch->entropy_u32) || |
77760fd7 | 1686 | next_gen != batch->generation) { |
186873c5 | 1687 | _get_random_bytes(batch->entropy_u32, sizeof(batch->entropy_u32)); |
f5b98461 | 1688 | batch->position = 0; |
77760fd7 | 1689 | batch->generation = next_gen; |
f5b98461 | 1690 | } |
77760fd7 | 1691 | |
186873c5 JD |
1692 | ret = batch->entropy_u32[batch->position]; |
1693 | batch->entropy_u32[batch->position] = 0; | |
1694 | ++batch->position; | |
77760fd7 | 1695 | local_unlock_irqrestore(&batched_entropy_u32.lock, flags); |
ec9ee4ac DC |
1696 | return ret; |
1697 | } | |
c440408c | 1698 | EXPORT_SYMBOL(get_random_u32); |
ec9ee4ac | 1699 | |
b169c13d JD |
1700 | /* It's important to invalidate all potential batched entropy that might |
1701 | * be stored before the crng is initialized, which we can do lazily by | |
77760fd7 JD |
1702 | * bumping the generation counter. |
1703 | */ | |
b169c13d JD |
1704 | static void invalidate_batched_entropy(void) |
1705 | { | |
77760fd7 | 1706 | atomic_inc(&batch_generation); |
b169c13d JD |
1707 | } |
1708 | ||
99fdafde JC |
1709 | /** |
1710 | * randomize_page - Generate a random, page aligned address | |
1711 | * @start: The smallest acceptable address the caller will take. | |
1712 | * @range: The size of the area, starting at @start, within which the | |
1713 | * random address must fall. | |
1714 | * | |
1715 | * If @start + @range would overflow, @range is capped. | |
1716 | * | |
1717 | * NOTE: Historical use of randomize_range, which this replaces, presumed that | |
1718 | * @start was already page aligned. We now align it regardless. | |
1719 | * | |
1720 | * Return: A page aligned address within [start, start + range). On error, | |
1721 | * @start is returned. | |
1722 | */ | |
248045b8 | 1723 | unsigned long randomize_page(unsigned long start, unsigned long range) |
99fdafde JC |
1724 | { |
1725 | if (!PAGE_ALIGNED(start)) { | |
1726 | range -= PAGE_ALIGN(start) - start; | |
1727 | start = PAGE_ALIGN(start); | |
1728 | } | |
1729 | ||
1730 | if (start > ULONG_MAX - range) | |
1731 | range = ULONG_MAX - start; | |
1732 | ||
1733 | range >>= PAGE_SHIFT; | |
1734 | ||
1735 | if (range == 0) | |
1736 | return start; | |
1737 | ||
1738 | return start + (get_random_long() % range << PAGE_SHIFT); | |
1739 | } | |
1740 | ||
c84dbf61 TD |
1741 | /* Interface for in-kernel drivers of true hardware RNGs. |
1742 | * Those devices may produce endless random bits and will be throttled | |
1743 | * when our pool is full. | |
1744 | */ | |
04ec96b7 | 1745 | void add_hwgenerator_randomness(const void *buffer, size_t count, |
c84dbf61 TD |
1746 | size_t entropy) |
1747 | { | |
43838a23 | 1748 | if (unlikely(crng_init == 0)) { |
73c7733f | 1749 | size_t ret = crng_fast_load(buffer, count); |
90ed1e67 | 1750 | mix_pool_bytes(buffer, ret); |
73c7733f JD |
1751 | count -= ret; |
1752 | buffer += ret; | |
1753 | if (!count || crng_init == 0) | |
1754 | return; | |
3371f3da | 1755 | } |
e192be9d | 1756 | |
c321e907 | 1757 | /* Throttle writing if we're above the trickle threshold. |
489c7fc4 JD |
1758 | * We'll be woken up again once below POOL_MIN_BITS, when |
1759 | * the calling thread is about to terminate, or once | |
1760 | * CRNG_RESEED_INTERVAL has elapsed. | |
e192be9d | 1761 | */ |
c321e907 | 1762 | wait_event_interruptible_timeout(random_write_wait, |
f7e67b8e | 1763 | !system_wq || kthread_should_stop() || |
489c7fc4 | 1764 | input_pool.entropy_count < POOL_MIN_BITS, |
c321e907 | 1765 | CRNG_RESEED_INTERVAL); |
90ed1e67 JD |
1766 | mix_pool_bytes(buffer, count); |
1767 | credit_entropy_bits(entropy); | |
c84dbf61 TD |
1768 | } |
1769 | EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); | |
428826f5 HYW |
1770 | |
1771 | /* Handle random seed passed by bootloader. | |
1772 | * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise | |
1773 | * it would be regarded as device data. | |
1774 | * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER. | |
1775 | */ | |
04ec96b7 | 1776 | void add_bootloader_randomness(const void *buf, size_t size) |
428826f5 HYW |
1777 | { |
1778 | if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER)) | |
1779 | add_hwgenerator_randomness(buf, size, size * 8); | |
1780 | else | |
1781 | add_device_randomness(buf, size); | |
1782 | } | |
3fd57e7a | 1783 | EXPORT_SYMBOL_GPL(add_bootloader_randomness); |