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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 | * |
248045b8 | 72 | * void get_random_bytes(void *buf, int 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 | * | |
a2080a67 | 100 | * void add_device_randomness(const void *buf, unsigned int 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); |
2b6c6e3d MB |
105 | * void add_hwgenerator_randomness(const char *buffer, size_t count, |
106 | * size_t entropy); | |
107 | * void add_bootloader_randomness(const void *buf, unsigned int 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); |
eecabf56 | 271 | static void _get_random_bytes(void *buf, int 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; |
cda796a3 | 293 | 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 | */ |
90ed1e67 | 311 | static void _mix_pool_bytes(const void *in, int nbytes) |
1da177e4 | 312 | { |
6e8ec255 | 313 | blake2s_update(&input_pool.hash, in, nbytes); |
1da177e4 LT |
314 | } |
315 | ||
90ed1e67 | 316 | static void __mix_pool_bytes(const void *in, int nbytes) |
00ce1db1 | 317 | { |
90ed1e67 JD |
318 | trace_mix_pool_bytes_nolock(nbytes, _RET_IP_); |
319 | _mix_pool_bytes(in, nbytes); | |
00ce1db1 TT |
320 | } |
321 | ||
90ed1e67 | 322 | static void mix_pool_bytes(const void *in, int nbytes) |
1da177e4 | 323 | { |
902c098a TT |
324 | unsigned long flags; |
325 | ||
90ed1e67 JD |
326 | trace_mix_pool_bytes(nbytes, _RET_IP_); |
327 | spin_lock_irqsave(&input_pool.lock, flags); | |
328 | _mix_pool_bytes(in, nbytes); | |
329 | spin_unlock_irqrestore(&input_pool.lock, flags); | |
1da177e4 LT |
330 | } |
331 | ||
775f4b29 | 332 | struct fast_pool { |
248045b8 JD |
333 | u32 pool[4]; |
334 | unsigned long last; | |
335 | u16 reg_idx; | |
336 | u8 count; | |
775f4b29 TT |
337 | }; |
338 | ||
339 | /* | |
340 | * This is a fast mixing routine used by the interrupt randomness | |
341 | * collector. It's hardcoded for an 128 bit pool and assumes that any | |
342 | * locks that might be needed are taken by the caller. | |
343 | */ | |
43759d4f | 344 | static void fast_mix(struct fast_pool *f) |
775f4b29 | 345 | { |
d38bb085 JD |
346 | u32 a = f->pool[0], b = f->pool[1]; |
347 | u32 c = f->pool[2], d = f->pool[3]; | |
43759d4f TT |
348 | |
349 | a += b; c += d; | |
19acc77a | 350 | b = rol32(b, 6); d = rol32(d, 27); |
43759d4f TT |
351 | d ^= a; b ^= c; |
352 | ||
353 | a += b; c += d; | |
19acc77a | 354 | b = rol32(b, 16); d = rol32(d, 14); |
43759d4f TT |
355 | d ^= a; b ^= c; |
356 | ||
357 | a += b; c += d; | |
19acc77a | 358 | b = rol32(b, 6); d = rol32(d, 27); |
43759d4f TT |
359 | d ^= a; b ^= c; |
360 | ||
361 | a += b; c += d; | |
19acc77a | 362 | b = rol32(b, 16); d = rol32(d, 14); |
43759d4f TT |
363 | d ^= a; b ^= c; |
364 | ||
365 | f->pool[0] = a; f->pool[1] = b; | |
366 | f->pool[2] = c; f->pool[3] = d; | |
655b2264 | 367 | f->count++; |
775f4b29 TT |
368 | } |
369 | ||
205a525c HX |
370 | static void process_random_ready_list(void) |
371 | { | |
372 | unsigned long flags; | |
373 | struct random_ready_callback *rdy, *tmp; | |
374 | ||
375 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
376 | list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) { | |
377 | struct module *owner = rdy->owner; | |
378 | ||
379 | list_del_init(&rdy->list); | |
380 | rdy->func(rdy); | |
381 | module_put(owner); | |
382 | } | |
383 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
384 | } | |
385 | ||
90ed1e67 | 386 | static void credit_entropy_bits(int nbits) |
1da177e4 | 387 | { |
9c07f578 | 388 | int entropy_count, orig; |
18263c4e | 389 | |
a49c010e | 390 | if (nbits <= 0) |
adc782da MM |
391 | return; |
392 | ||
a49c010e JD |
393 | nbits = min(nbits, POOL_BITS); |
394 | ||
c5704490 JD |
395 | do { |
396 | orig = READ_ONCE(input_pool.entropy_count); | |
397 | entropy_count = min(POOL_BITS, orig + nbits); | |
398 | } while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig); | |
1da177e4 | 399 | |
c5704490 | 400 | trace_credit_entropy_bits(nbits, entropy_count, _RET_IP_); |
00ce1db1 | 401 | |
c5704490 | 402 | if (crng_init < 2 && entropy_count >= POOL_MIN_BITS) |
a9412d51 | 403 | crng_reseed(); |
1da177e4 LT |
404 | } |
405 | ||
e192be9d TT |
406 | /********************************************************************* |
407 | * | |
408 | * CRNG using CHACHA20 | |
409 | * | |
410 | *********************************************************************/ | |
411 | ||
186873c5 JD |
412 | enum { |
413 | CRNG_RESEED_INTERVAL = 300 * HZ, | |
414 | CRNG_INIT_CNT_THRESH = 2 * CHACHA_KEY_SIZE | |
415 | }; | |
416 | ||
417 | static struct { | |
418 | u8 key[CHACHA_KEY_SIZE] __aligned(__alignof__(long)); | |
419 | unsigned long birth; | |
420 | unsigned long generation; | |
421 | spinlock_t lock; | |
422 | } base_crng = { | |
423 | .lock = __SPIN_LOCK_UNLOCKED(base_crng.lock) | |
424 | }; | |
425 | ||
426 | struct crng { | |
427 | u8 key[CHACHA_KEY_SIZE]; | |
428 | unsigned long generation; | |
429 | local_lock_t lock; | |
430 | }; | |
431 | ||
432 | static DEFINE_PER_CPU(struct crng, crngs) = { | |
433 | .generation = ULONG_MAX, | |
434 | .lock = INIT_LOCAL_LOCK(crngs.lock), | |
435 | }; | |
e192be9d TT |
436 | |
437 | static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); | |
438 | ||
b169c13d JD |
439 | static void invalidate_batched_entropy(void); |
440 | ||
dc12baac TT |
441 | /* |
442 | * crng_fast_load() can be called by code in the interrupt service | |
73c7733f JD |
443 | * path. So we can't afford to dilly-dally. Returns the number of |
444 | * bytes processed from cp. | |
dc12baac | 445 | */ |
d38bb085 | 446 | static size_t crng_fast_load(const u8 *cp, size_t len) |
e192be9d TT |
447 | { |
448 | unsigned long flags; | |
d38bb085 | 449 | u8 *p; |
73c7733f | 450 | size_t ret = 0; |
e192be9d | 451 | |
186873c5 | 452 | if (!spin_trylock_irqsave(&base_crng.lock, flags)) |
e192be9d | 453 | return 0; |
43838a23 | 454 | if (crng_init != 0) { |
186873c5 | 455 | spin_unlock_irqrestore(&base_crng.lock, flags); |
e192be9d TT |
456 | return 0; |
457 | } | |
186873c5 | 458 | p = base_crng.key; |
e192be9d | 459 | while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) { |
186873c5 | 460 | p[crng_init_cnt % sizeof(base_crng.key)] ^= *cp; |
73c7733f | 461 | cp++; crng_init_cnt++; len--; ret++; |
e192be9d TT |
462 | } |
463 | if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) { | |
b169c13d | 464 | invalidate_batched_entropy(); |
e192be9d | 465 | crng_init = 1; |
e192be9d | 466 | } |
186873c5 | 467 | spin_unlock_irqrestore(&base_crng.lock, flags); |
7c2fe2b3 DB |
468 | if (crng_init == 1) |
469 | pr_notice("fast init done\n"); | |
73c7733f | 470 | return ret; |
e192be9d TT |
471 | } |
472 | ||
dc12baac TT |
473 | /* |
474 | * crng_slow_load() is called by add_device_randomness, which has two | |
475 | * attributes. (1) We can't trust the buffer passed to it is | |
476 | * guaranteed to be unpredictable (so it might not have any entropy at | |
477 | * all), and (2) it doesn't have the performance constraints of | |
478 | * crng_fast_load(). | |
479 | * | |
480 | * So we do something more comprehensive which is guaranteed to touch | |
481 | * all of the primary_crng's state, and which uses a LFSR with a | |
482 | * period of 255 as part of the mixing algorithm. Finally, we do | |
483 | * *not* advance crng_init_cnt since buffer we may get may be something | |
484 | * like a fixed DMI table (for example), which might very well be | |
485 | * unique to the machine, but is otherwise unvarying. | |
486 | */ | |
d38bb085 | 487 | static int crng_slow_load(const u8 *cp, size_t len) |
dc12baac | 488 | { |
248045b8 JD |
489 | unsigned long flags; |
490 | static u8 lfsr = 1; | |
491 | u8 tmp; | |
186873c5 | 492 | unsigned int i, max = sizeof(base_crng.key); |
248045b8 | 493 | const u8 *src_buf = cp; |
186873c5 | 494 | u8 *dest_buf = base_crng.key; |
dc12baac | 495 | |
186873c5 | 496 | if (!spin_trylock_irqsave(&base_crng.lock, flags)) |
dc12baac TT |
497 | return 0; |
498 | if (crng_init != 0) { | |
186873c5 | 499 | spin_unlock_irqrestore(&base_crng.lock, flags); |
dc12baac TT |
500 | return 0; |
501 | } | |
502 | if (len > max) | |
503 | max = len; | |
504 | ||
248045b8 | 505 | for (i = 0; i < max; i++) { |
dc12baac TT |
506 | tmp = lfsr; |
507 | lfsr >>= 1; | |
508 | if (tmp & 1) | |
509 | lfsr ^= 0xE1; | |
186873c5 JD |
510 | tmp = dest_buf[i % sizeof(base_crng.key)]; |
511 | dest_buf[i % sizeof(base_crng.key)] ^= src_buf[i % len] ^ lfsr; | |
dc12baac TT |
512 | lfsr += (tmp << 3) | (tmp >> 5); |
513 | } | |
186873c5 | 514 | spin_unlock_irqrestore(&base_crng.lock, flags); |
dc12baac TT |
515 | return 1; |
516 | } | |
517 | ||
a9412d51 | 518 | static void crng_reseed(void) |
e192be9d | 519 | { |
248045b8 | 520 | unsigned long flags; |
186873c5 JD |
521 | int entropy_count; |
522 | unsigned long next_gen; | |
523 | u8 key[CHACHA_KEY_SIZE]; | |
e192be9d | 524 | |
186873c5 JD |
525 | /* |
526 | * First we make sure we have POOL_MIN_BITS of entropy in the pool, | |
527 | * and then we drain all of it. Only then can we extract a new key. | |
528 | */ | |
a9412d51 JD |
529 | do { |
530 | entropy_count = READ_ONCE(input_pool.entropy_count); | |
531 | if (entropy_count < POOL_MIN_BITS) | |
532 | return; | |
533 | } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count); | |
186873c5 | 534 | extract_entropy(key, sizeof(key)); |
a9412d51 JD |
535 | wake_up_interruptible(&random_write_wait); |
536 | kill_fasync(&fasync, SIGIO, POLL_OUT); | |
537 | ||
186873c5 JD |
538 | /* |
539 | * We copy the new key into the base_crng, overwriting the old one, | |
540 | * and update the generation counter. We avoid hitting ULONG_MAX, | |
541 | * because the per-cpu crngs are initialized to ULONG_MAX, so this | |
542 | * forces new CPUs that come online to always initialize. | |
543 | */ | |
544 | spin_lock_irqsave(&base_crng.lock, flags); | |
545 | memcpy(base_crng.key, key, sizeof(base_crng.key)); | |
546 | next_gen = base_crng.generation + 1; | |
547 | if (next_gen == ULONG_MAX) | |
548 | ++next_gen; | |
549 | WRITE_ONCE(base_crng.generation, next_gen); | |
550 | WRITE_ONCE(base_crng.birth, jiffies); | |
551 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
552 | memzero_explicit(key, sizeof(key)); | |
553 | ||
a9412d51 JD |
554 | if (crng_init < 2) { |
555 | invalidate_batched_entropy(); | |
556 | crng_init = 2; | |
557 | process_random_ready_list(); | |
558 | wake_up_interruptible(&crng_init_wait); | |
559 | kill_fasync(&fasync, SIGIO, POLL_IN); | |
560 | pr_notice("crng init done\n"); | |
561 | if (unseeded_warning.missed) { | |
562 | pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n", | |
563 | unseeded_warning.missed); | |
564 | unseeded_warning.missed = 0; | |
565 | } | |
566 | if (urandom_warning.missed) { | |
567 | pr_notice("%d urandom warning(s) missed due to ratelimiting\n", | |
568 | urandom_warning.missed); | |
569 | urandom_warning.missed = 0; | |
570 | } | |
571 | } | |
e192be9d TT |
572 | } |
573 | ||
186873c5 JD |
574 | /* |
575 | * The general form here is based on a "fast key erasure RNG" from | |
576 | * <https://blog.cr.yp.to/20170723-random.html>. It generates a ChaCha | |
577 | * block using the provided key, and then immediately overwites that | |
578 | * key with half the block. It returns the resultant ChaCha state to the | |
579 | * user, along with the second half of the block containing 32 bytes of | |
580 | * random data that may be used; random_data_len may not be greater than | |
581 | * 32. | |
582 | */ | |
583 | static void crng_fast_key_erasure(u8 key[CHACHA_KEY_SIZE], | |
584 | u32 chacha_state[CHACHA_STATE_WORDS], | |
585 | u8 *random_data, size_t random_data_len) | |
e192be9d | 586 | { |
186873c5 | 587 | u8 first_block[CHACHA_BLOCK_SIZE]; |
009ba856 | 588 | |
186873c5 JD |
589 | BUG_ON(random_data_len > 32); |
590 | ||
591 | chacha_init_consts(chacha_state); | |
592 | memcpy(&chacha_state[4], key, CHACHA_KEY_SIZE); | |
593 | memset(&chacha_state[12], 0, sizeof(u32) * 4); | |
594 | chacha20_block(chacha_state, first_block); | |
595 | ||
596 | memcpy(key, first_block, CHACHA_KEY_SIZE); | |
597 | memcpy(random_data, first_block + CHACHA_KEY_SIZE, random_data_len); | |
598 | memzero_explicit(first_block, sizeof(first_block)); | |
1e7f583a TT |
599 | } |
600 | ||
c92e040d | 601 | /* |
186873c5 JD |
602 | * This function returns a ChaCha state that you may use for generating |
603 | * random data. It also returns up to 32 bytes on its own of random data | |
604 | * that may be used; random_data_len may not be greater than 32. | |
c92e040d | 605 | */ |
186873c5 JD |
606 | static void crng_make_state(u32 chacha_state[CHACHA_STATE_WORDS], |
607 | u8 *random_data, size_t random_data_len) | |
c92e040d | 608 | { |
248045b8 | 609 | unsigned long flags; |
186873c5 | 610 | struct crng *crng; |
c92e040d | 611 | |
186873c5 JD |
612 | BUG_ON(random_data_len > 32); |
613 | ||
614 | /* | |
615 | * For the fast path, we check whether we're ready, unlocked first, and | |
616 | * then re-check once locked later. In the case where we're really not | |
617 | * ready, we do fast key erasure with the base_crng directly, because | |
618 | * this is what crng_{fast,slow}_load mutate during early init. | |
619 | */ | |
620 | if (unlikely(!crng_ready())) { | |
621 | bool ready; | |
622 | ||
623 | spin_lock_irqsave(&base_crng.lock, flags); | |
624 | ready = crng_ready(); | |
625 | if (!ready) | |
626 | crng_fast_key_erasure(base_crng.key, chacha_state, | |
627 | random_data, random_data_len); | |
628 | spin_unlock_irqrestore(&base_crng.lock, flags); | |
629 | if (!ready) | |
630 | return; | |
c92e040d | 631 | } |
186873c5 JD |
632 | |
633 | /* | |
634 | * If the base_crng is more than 5 minutes old, we reseed, which | |
635 | * in turn bumps the generation counter that we check below. | |
636 | */ | |
637 | if (unlikely(time_after(jiffies, READ_ONCE(base_crng.birth) + CRNG_RESEED_INTERVAL))) | |
638 | crng_reseed(); | |
639 | ||
640 | local_lock_irqsave(&crngs.lock, flags); | |
641 | crng = raw_cpu_ptr(&crngs); | |
642 | ||
643 | /* | |
644 | * If our per-cpu crng is older than the base_crng, then it means | |
645 | * somebody reseeded the base_crng. In that case, we do fast key | |
646 | * erasure on the base_crng, and use its output as the new key | |
647 | * for our per-cpu crng. This brings us up to date with base_crng. | |
648 | */ | |
649 | if (unlikely(crng->generation != READ_ONCE(base_crng.generation))) { | |
650 | spin_lock(&base_crng.lock); | |
651 | crng_fast_key_erasure(base_crng.key, chacha_state, | |
652 | crng->key, sizeof(crng->key)); | |
653 | crng->generation = base_crng.generation; | |
654 | spin_unlock(&base_crng.lock); | |
655 | } | |
656 | ||
657 | /* | |
658 | * Finally, when we've made it this far, our per-cpu crng has an up | |
659 | * to date key, and we can do fast key erasure with it to produce | |
660 | * some random data and a ChaCha state for the caller. All other | |
661 | * branches of this function are "unlikely", so most of the time we | |
662 | * should wind up here immediately. | |
663 | */ | |
664 | crng_fast_key_erasure(crng->key, chacha_state, random_data, random_data_len); | |
665 | local_unlock_irqrestore(&crngs.lock, flags); | |
c92e040d TT |
666 | } |
667 | ||
186873c5 | 668 | static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes) |
e192be9d | 669 | { |
186873c5 JD |
670 | bool large_request = nbytes > 256; |
671 | ssize_t ret = 0, len; | |
672 | u32 chacha_state[CHACHA_STATE_WORDS]; | |
673 | u8 output[CHACHA_BLOCK_SIZE]; | |
674 | ||
675 | if (!nbytes) | |
676 | return 0; | |
677 | ||
678 | len = min_t(ssize_t, 32, nbytes); | |
679 | crng_make_state(chacha_state, output, len); | |
680 | ||
681 | if (copy_to_user(buf, output, len)) | |
682 | return -EFAULT; | |
683 | nbytes -= len; | |
684 | buf += len; | |
685 | ret += len; | |
e192be9d TT |
686 | |
687 | while (nbytes) { | |
688 | if (large_request && need_resched()) { | |
186873c5 | 689 | if (signal_pending(current)) |
e192be9d | 690 | break; |
e192be9d TT |
691 | schedule(); |
692 | } | |
693 | ||
186873c5 JD |
694 | chacha20_block(chacha_state, output); |
695 | if (unlikely(chacha_state[12] == 0)) | |
696 | ++chacha_state[13]; | |
697 | ||
698 | len = min_t(ssize_t, nbytes, CHACHA_BLOCK_SIZE); | |
699 | if (copy_to_user(buf, output, len)) { | |
e192be9d TT |
700 | ret = -EFAULT; |
701 | break; | |
702 | } | |
703 | ||
186873c5 JD |
704 | nbytes -= len; |
705 | buf += len; | |
706 | ret += len; | |
e192be9d | 707 | } |
e192be9d | 708 | |
186873c5 JD |
709 | memzero_explicit(chacha_state, sizeof(chacha_state)); |
710 | memzero_explicit(output, sizeof(output)); | |
e192be9d TT |
711 | return ret; |
712 | } | |
713 | ||
1da177e4 LT |
714 | /********************************************************************* |
715 | * | |
716 | * Entropy input management | |
717 | * | |
718 | *********************************************************************/ | |
719 | ||
720 | /* There is one of these per entropy source */ | |
721 | struct timer_rand_state { | |
722 | cycles_t last_time; | |
90b75ee5 | 723 | long last_delta, last_delta2; |
1da177e4 LT |
724 | }; |
725 | ||
644008df TT |
726 | #define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, }; |
727 | ||
a2080a67 | 728 | /* |
e192be9d TT |
729 | * Add device- or boot-specific data to the input pool to help |
730 | * initialize it. | |
a2080a67 | 731 | * |
e192be9d TT |
732 | * None of this adds any entropy; it is meant to avoid the problem of |
733 | * the entropy pool having similar initial state across largely | |
734 | * identical devices. | |
a2080a67 LT |
735 | */ |
736 | void add_device_randomness(const void *buf, unsigned int size) | |
737 | { | |
61875f30 | 738 | unsigned long time = random_get_entropy() ^ jiffies; |
3ef4cb2d | 739 | unsigned long flags; |
a2080a67 | 740 | |
dc12baac TT |
741 | if (!crng_ready() && size) |
742 | crng_slow_load(buf, size); | |
ee7998c5 | 743 | |
5910895f | 744 | trace_add_device_randomness(size, _RET_IP_); |
3ef4cb2d | 745 | spin_lock_irqsave(&input_pool.lock, flags); |
90ed1e67 JD |
746 | _mix_pool_bytes(buf, size); |
747 | _mix_pool_bytes(&time, sizeof(time)); | |
3ef4cb2d | 748 | spin_unlock_irqrestore(&input_pool.lock, flags); |
a2080a67 LT |
749 | } |
750 | EXPORT_SYMBOL(add_device_randomness); | |
751 | ||
644008df | 752 | static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE; |
3060d6fe | 753 | |
1da177e4 LT |
754 | /* |
755 | * This function adds entropy to the entropy "pool" by using timing | |
756 | * delays. It uses the timer_rand_state structure to make an estimate | |
757 | * of how many bits of entropy this call has added to the pool. | |
758 | * | |
759 | * The number "num" is also added to the pool - it should somehow describe | |
760 | * the type of event which just happened. This is currently 0-255 for | |
761 | * keyboard scan codes, and 256 upwards for interrupts. | |
762 | * | |
763 | */ | |
764 | static void add_timer_randomness(struct timer_rand_state *state, unsigned num) | |
765 | { | |
766 | struct { | |
1da177e4 | 767 | long jiffies; |
d38bb085 JD |
768 | unsigned int cycles; |
769 | unsigned int num; | |
1da177e4 LT |
770 | } sample; |
771 | long delta, delta2, delta3; | |
772 | ||
1da177e4 | 773 | sample.jiffies = jiffies; |
61875f30 | 774 | sample.cycles = random_get_entropy(); |
1da177e4 | 775 | sample.num = num; |
90ed1e67 | 776 | mix_pool_bytes(&sample, sizeof(sample)); |
1da177e4 LT |
777 | |
778 | /* | |
779 | * Calculate number of bits of randomness we probably added. | |
780 | * We take into account the first, second and third-order deltas | |
781 | * in order to make our estimate. | |
782 | */ | |
e00d996a QC |
783 | delta = sample.jiffies - READ_ONCE(state->last_time); |
784 | WRITE_ONCE(state->last_time, sample.jiffies); | |
5e747dd9 | 785 | |
e00d996a QC |
786 | delta2 = delta - READ_ONCE(state->last_delta); |
787 | WRITE_ONCE(state->last_delta, delta); | |
5e747dd9 | 788 | |
e00d996a QC |
789 | delta3 = delta2 - READ_ONCE(state->last_delta2); |
790 | WRITE_ONCE(state->last_delta2, delta2); | |
5e747dd9 RV |
791 | |
792 | if (delta < 0) | |
793 | delta = -delta; | |
794 | if (delta2 < 0) | |
795 | delta2 = -delta2; | |
796 | if (delta3 < 0) | |
797 | delta3 = -delta3; | |
798 | if (delta > delta2) | |
799 | delta = delta2; | |
800 | if (delta > delta3) | |
801 | delta = delta3; | |
1da177e4 | 802 | |
5e747dd9 RV |
803 | /* |
804 | * delta is now minimum absolute delta. | |
805 | * Round down by 1 bit on general principles, | |
727d499a | 806 | * and limit entropy estimate to 12 bits. |
5e747dd9 | 807 | */ |
248045b8 | 808 | credit_entropy_bits(min_t(int, fls(delta >> 1), 11)); |
1da177e4 LT |
809 | } |
810 | ||
d251575a | 811 | void add_input_randomness(unsigned int type, unsigned int code, |
248045b8 | 812 | unsigned int value) |
1da177e4 LT |
813 | { |
814 | static unsigned char last_value; | |
815 | ||
816 | /* ignore autorepeat and the like */ | |
817 | if (value == last_value) | |
818 | return; | |
819 | ||
1da177e4 LT |
820 | last_value = value; |
821 | add_timer_randomness(&input_timer_state, | |
822 | (type << 4) ^ code ^ (code >> 4) ^ value); | |
c5704490 | 823 | trace_add_input_randomness(input_pool.entropy_count); |
1da177e4 | 824 | } |
80fc9f53 | 825 | EXPORT_SYMBOL_GPL(add_input_randomness); |
1da177e4 | 826 | |
775f4b29 TT |
827 | static DEFINE_PER_CPU(struct fast_pool, irq_randomness); |
828 | ||
43759d4f TT |
829 | #ifdef ADD_INTERRUPT_BENCH |
830 | static unsigned long avg_cycles, avg_deviation; | |
831 | ||
248045b8 JD |
832 | #define AVG_SHIFT 8 /* Exponential average factor k=1/256 */ |
833 | #define FIXED_1_2 (1 << (AVG_SHIFT - 1)) | |
43759d4f TT |
834 | |
835 | static void add_interrupt_bench(cycles_t start) | |
836 | { | |
248045b8 | 837 | long delta = random_get_entropy() - start; |
43759d4f | 838 | |
248045b8 JD |
839 | /* Use a weighted moving average */ |
840 | delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT); | |
841 | avg_cycles += delta; | |
842 | /* And average deviation */ | |
843 | delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT); | |
844 | avg_deviation += delta; | |
43759d4f TT |
845 | } |
846 | #else | |
847 | #define add_interrupt_bench(x) | |
848 | #endif | |
849 | ||
d38bb085 | 850 | static u32 get_reg(struct fast_pool *f, struct pt_regs *regs) |
ee3e00e9 | 851 | { |
248045b8 | 852 | u32 *ptr = (u32 *)regs; |
92e75428 | 853 | unsigned int idx; |
ee3e00e9 TT |
854 | |
855 | if (regs == NULL) | |
856 | return 0; | |
92e75428 | 857 | idx = READ_ONCE(f->reg_idx); |
d38bb085 | 858 | if (idx >= sizeof(struct pt_regs) / sizeof(u32)) |
92e75428 TT |
859 | idx = 0; |
860 | ptr += idx++; | |
861 | WRITE_ONCE(f->reg_idx, idx); | |
9dfa7bba | 862 | return *ptr; |
ee3e00e9 TT |
863 | } |
864 | ||
703f7066 | 865 | void add_interrupt_randomness(int irq) |
1da177e4 | 866 | { |
248045b8 JD |
867 | struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness); |
868 | struct pt_regs *regs = get_irq_regs(); | |
869 | unsigned long now = jiffies; | |
870 | cycles_t cycles = random_get_entropy(); | |
871 | u32 c_high, j_high; | |
872 | u64 ip; | |
3060d6fe | 873 | |
ee3e00e9 TT |
874 | if (cycles == 0) |
875 | cycles = get_reg(fast_pool, regs); | |
655b2264 TT |
876 | c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0; |
877 | j_high = (sizeof(now) > 4) ? now >> 32 : 0; | |
43759d4f TT |
878 | fast_pool->pool[0] ^= cycles ^ j_high ^ irq; |
879 | fast_pool->pool[1] ^= now ^ c_high; | |
655b2264 | 880 | ip = regs ? instruction_pointer(regs) : _RET_IP_; |
43759d4f | 881 | fast_pool->pool[2] ^= ip; |
248045b8 JD |
882 | fast_pool->pool[3] ^= |
883 | (sizeof(ip) > 4) ? ip >> 32 : get_reg(fast_pool, regs); | |
3060d6fe | 884 | |
43759d4f | 885 | fast_mix(fast_pool); |
43759d4f | 886 | add_interrupt_bench(cycles); |
3060d6fe | 887 | |
43838a23 | 888 | if (unlikely(crng_init == 0)) { |
e192be9d | 889 | if ((fast_pool->count >= 64) && |
d38bb085 | 890 | crng_fast_load((u8 *)fast_pool->pool, sizeof(fast_pool->pool)) > 0) { |
e192be9d TT |
891 | fast_pool->count = 0; |
892 | fast_pool->last = now; | |
c30c575d JD |
893 | if (spin_trylock(&input_pool.lock)) { |
894 | _mix_pool_bytes(&fast_pool->pool, sizeof(fast_pool->pool)); | |
895 | spin_unlock(&input_pool.lock); | |
896 | } | |
e192be9d TT |
897 | } |
898 | return; | |
899 | } | |
900 | ||
248045b8 | 901 | if ((fast_pool->count < 64) && !time_after(now, fast_pool->last + HZ)) |
1da177e4 LT |
902 | return; |
903 | ||
90ed1e67 | 904 | if (!spin_trylock(&input_pool.lock)) |
91fcb532 | 905 | return; |
83664a69 | 906 | |
91fcb532 | 907 | fast_pool->last = now; |
90ed1e67 JD |
908 | __mix_pool_bytes(&fast_pool->pool, sizeof(fast_pool->pool)); |
909 | spin_unlock(&input_pool.lock); | |
83664a69 | 910 | |
ee3e00e9 | 911 | fast_pool->count = 0; |
83664a69 | 912 | |
ee3e00e9 | 913 | /* award one bit for the contents of the fast pool */ |
90ed1e67 | 914 | credit_entropy_bits(1); |
1da177e4 | 915 | } |
4b44f2d1 | 916 | EXPORT_SYMBOL_GPL(add_interrupt_randomness); |
1da177e4 | 917 | |
9361401e | 918 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
919 | void add_disk_randomness(struct gendisk *disk) |
920 | { | |
921 | if (!disk || !disk->random) | |
922 | return; | |
923 | /* first major is 1, so we get >= 0x200 here */ | |
f331c029 | 924 | add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); |
c5704490 | 925 | trace_add_disk_randomness(disk_devt(disk), input_pool.entropy_count); |
1da177e4 | 926 | } |
bdcfa3e5 | 927 | EXPORT_SYMBOL_GPL(add_disk_randomness); |
9361401e | 928 | #endif |
1da177e4 | 929 | |
1da177e4 LT |
930 | /********************************************************************* |
931 | * | |
932 | * Entropy extraction routines | |
933 | * | |
934 | *********************************************************************/ | |
935 | ||
19fa5be1 | 936 | /* |
6e8ec255 JD |
937 | * This is an HKDF-like construction for using the hashed collected entropy |
938 | * as a PRF key, that's then expanded block-by-block. | |
19fa5be1 | 939 | */ |
9c07f578 | 940 | static void extract_entropy(void *buf, size_t nbytes) |
1da177e4 | 941 | { |
902c098a | 942 | unsigned long flags; |
6e8ec255 JD |
943 | u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE]; |
944 | struct { | |
28f425e5 | 945 | unsigned long rdseed[32 / sizeof(long)]; |
6e8ec255 JD |
946 | size_t counter; |
947 | } block; | |
948 | size_t i; | |
949 | ||
c5704490 | 950 | trace_extract_entropy(nbytes, input_pool.entropy_count); |
9c07f578 | 951 | |
28f425e5 JD |
952 | for (i = 0; i < ARRAY_SIZE(block.rdseed); ++i) { |
953 | if (!arch_get_random_seed_long(&block.rdseed[i]) && | |
954 | !arch_get_random_long(&block.rdseed[i])) | |
955 | block.rdseed[i] = random_get_entropy(); | |
85a1f777 TT |
956 | } |
957 | ||
90ed1e67 | 958 | spin_lock_irqsave(&input_pool.lock, flags); |
46884442 | 959 | |
6e8ec255 JD |
960 | /* seed = HASHPRF(last_key, entropy_input) */ |
961 | blake2s_final(&input_pool.hash, seed); | |
1da177e4 | 962 | |
28f425e5 | 963 | /* next_key = HASHPRF(seed, RDSEED || 0) */ |
6e8ec255 JD |
964 | block.counter = 0; |
965 | blake2s(next_key, (u8 *)&block, seed, sizeof(next_key), sizeof(block), sizeof(seed)); | |
966 | blake2s_init_key(&input_pool.hash, BLAKE2S_HASH_SIZE, next_key, sizeof(next_key)); | |
1da177e4 | 967 | |
6e8ec255 JD |
968 | spin_unlock_irqrestore(&input_pool.lock, flags); |
969 | memzero_explicit(next_key, sizeof(next_key)); | |
e192be9d TT |
970 | |
971 | while (nbytes) { | |
6e8ec255 | 972 | i = min_t(size_t, nbytes, BLAKE2S_HASH_SIZE); |
28f425e5 | 973 | /* output = HASHPRF(seed, RDSEED || ++counter) */ |
6e8ec255 JD |
974 | ++block.counter; |
975 | blake2s(buf, (u8 *)&block, seed, i, sizeof(block), sizeof(seed)); | |
e192be9d TT |
976 | nbytes -= i; |
977 | buf += i; | |
e192be9d TT |
978 | } |
979 | ||
6e8ec255 JD |
980 | memzero_explicit(seed, sizeof(seed)); |
981 | memzero_explicit(&block, sizeof(block)); | |
e192be9d TT |
982 | } |
983 | ||
eecabf56 | 984 | #define warn_unseeded_randomness(previous) \ |
248045b8 | 985 | _warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous)) |
eecabf56 | 986 | |
248045b8 | 987 | static void _warn_unseeded_randomness(const char *func_name, void *caller, void **previous) |
eecabf56 TT |
988 | { |
989 | #ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM | |
990 | const bool print_once = false; | |
991 | #else | |
992 | static bool print_once __read_mostly; | |
993 | #endif | |
994 | ||
248045b8 | 995 | if (print_once || crng_ready() || |
eecabf56 TT |
996 | (previous && (caller == READ_ONCE(*previous)))) |
997 | return; | |
998 | WRITE_ONCE(*previous, caller); | |
999 | #ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM | |
1000 | print_once = true; | |
1001 | #endif | |
4e00b339 | 1002 | if (__ratelimit(&unseeded_warning)) |
248045b8 JD |
1003 | printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n", |
1004 | func_name, caller, crng_init); | |
eecabf56 TT |
1005 | } |
1006 | ||
1da177e4 LT |
1007 | /* |
1008 | * This function is the exported kernel interface. It returns some | |
c2557a30 | 1009 | * number of good random numbers, suitable for key generation, seeding |
18e9cea7 GP |
1010 | * TCP sequence numbers, etc. It does not rely on the hardware random |
1011 | * number generator. For random bytes direct from the hardware RNG | |
e297a783 JD |
1012 | * (when available), use get_random_bytes_arch(). In order to ensure |
1013 | * that the randomness provided by this function is okay, the function | |
1014 | * wait_for_random_bytes() should be called and return 0 at least once | |
1015 | * at any point prior. | |
1da177e4 | 1016 | */ |
eecabf56 | 1017 | static void _get_random_bytes(void *buf, int nbytes) |
c2557a30 | 1018 | { |
186873c5 JD |
1019 | u32 chacha_state[CHACHA_STATE_WORDS]; |
1020 | u8 tmp[CHACHA_BLOCK_SIZE]; | |
1021 | ssize_t len; | |
e192be9d | 1022 | |
5910895f | 1023 | trace_get_random_bytes(nbytes, _RET_IP_); |
e192be9d | 1024 | |
186873c5 JD |
1025 | if (!nbytes) |
1026 | return; | |
1027 | ||
1028 | len = min_t(ssize_t, 32, nbytes); | |
1029 | crng_make_state(chacha_state, buf, len); | |
1030 | nbytes -= len; | |
1031 | buf += len; | |
1032 | ||
1033 | while (nbytes) { | |
1034 | if (nbytes < CHACHA_BLOCK_SIZE) { | |
1035 | chacha20_block(chacha_state, tmp); | |
1036 | memcpy(buf, tmp, nbytes); | |
1037 | memzero_explicit(tmp, sizeof(tmp)); | |
1038 | break; | |
1039 | } | |
1040 | ||
1041 | chacha20_block(chacha_state, buf); | |
1042 | if (unlikely(chacha_state[12] == 0)) | |
1043 | ++chacha_state[13]; | |
1ca1b917 | 1044 | nbytes -= CHACHA_BLOCK_SIZE; |
186873c5 | 1045 | buf += CHACHA_BLOCK_SIZE; |
e192be9d TT |
1046 | } |
1047 | ||
186873c5 | 1048 | memzero_explicit(chacha_state, sizeof(chacha_state)); |
c2557a30 | 1049 | } |
eecabf56 TT |
1050 | |
1051 | void get_random_bytes(void *buf, int nbytes) | |
1052 | { | |
1053 | static void *previous; | |
1054 | ||
1055 | warn_unseeded_randomness(&previous); | |
1056 | _get_random_bytes(buf, nbytes); | |
1057 | } | |
c2557a30 TT |
1058 | EXPORT_SYMBOL(get_random_bytes); |
1059 | ||
50ee7529 LT |
1060 | /* |
1061 | * Each time the timer fires, we expect that we got an unpredictable | |
1062 | * jump in the cycle counter. Even if the timer is running on another | |
1063 | * CPU, the timer activity will be touching the stack of the CPU that is | |
1064 | * generating entropy.. | |
1065 | * | |
1066 | * Note that we don't re-arm the timer in the timer itself - we are | |
1067 | * happy to be scheduled away, since that just makes the load more | |
1068 | * complex, but we do not want the timer to keep ticking unless the | |
1069 | * entropy loop is running. | |
1070 | * | |
1071 | * So the re-arming always happens in the entropy loop itself. | |
1072 | */ | |
1073 | static void entropy_timer(struct timer_list *t) | |
1074 | { | |
90ed1e67 | 1075 | credit_entropy_bits(1); |
50ee7529 LT |
1076 | } |
1077 | ||
1078 | /* | |
1079 | * If we have an actual cycle counter, see if we can | |
1080 | * generate enough entropy with timing noise | |
1081 | */ | |
1082 | static void try_to_generate_entropy(void) | |
1083 | { | |
1084 | struct { | |
1085 | unsigned long now; | |
1086 | struct timer_list timer; | |
1087 | } stack; | |
1088 | ||
1089 | stack.now = random_get_entropy(); | |
1090 | ||
1091 | /* Slow counter - or none. Don't even bother */ | |
1092 | if (stack.now == random_get_entropy()) | |
1093 | return; | |
1094 | ||
1095 | timer_setup_on_stack(&stack.timer, entropy_timer, 0); | |
1096 | while (!crng_ready()) { | |
1097 | if (!timer_pending(&stack.timer)) | |
248045b8 | 1098 | mod_timer(&stack.timer, jiffies + 1); |
90ed1e67 | 1099 | mix_pool_bytes(&stack.now, sizeof(stack.now)); |
50ee7529 LT |
1100 | schedule(); |
1101 | stack.now = random_get_entropy(); | |
1102 | } | |
1103 | ||
1104 | del_timer_sync(&stack.timer); | |
1105 | destroy_timer_on_stack(&stack.timer); | |
90ed1e67 | 1106 | mix_pool_bytes(&stack.now, sizeof(stack.now)); |
50ee7529 LT |
1107 | } |
1108 | ||
e297a783 JD |
1109 | /* |
1110 | * Wait for the urandom pool to be seeded and thus guaranteed to supply | |
1111 | * cryptographically secure random numbers. This applies to: the /dev/urandom | |
1112 | * device, the get_random_bytes function, and the get_random_{u32,u64,int,long} | |
1113 | * family of functions. Using any of these functions without first calling | |
1114 | * this function forfeits the guarantee of security. | |
1115 | * | |
1116 | * Returns: 0 if the urandom pool has been seeded. | |
1117 | * -ERESTARTSYS if the function was interrupted by a signal. | |
1118 | */ | |
1119 | int wait_for_random_bytes(void) | |
1120 | { | |
1121 | if (likely(crng_ready())) | |
1122 | return 0; | |
50ee7529 LT |
1123 | |
1124 | do { | |
1125 | int ret; | |
1126 | ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ); | |
1127 | if (ret) | |
1128 | return ret > 0 ? 0 : ret; | |
1129 | ||
1130 | try_to_generate_entropy(); | |
1131 | } while (!crng_ready()); | |
1132 | ||
1133 | return 0; | |
e297a783 JD |
1134 | } |
1135 | EXPORT_SYMBOL(wait_for_random_bytes); | |
1136 | ||
9a47249d JD |
1137 | /* |
1138 | * Returns whether or not the urandom pool has been seeded and thus guaranteed | |
1139 | * to supply cryptographically secure random numbers. This applies to: the | |
1140 | * /dev/urandom device, the get_random_bytes function, and the get_random_{u32, | |
1141 | * ,u64,int,long} family of functions. | |
1142 | * | |
1143 | * Returns: true if the urandom pool has been seeded. | |
1144 | * false if the urandom pool has not been seeded. | |
1145 | */ | |
1146 | bool rng_is_initialized(void) | |
1147 | { | |
1148 | return crng_ready(); | |
1149 | } | |
1150 | EXPORT_SYMBOL(rng_is_initialized); | |
1151 | ||
205a525c HX |
1152 | /* |
1153 | * Add a callback function that will be invoked when the nonblocking | |
1154 | * pool is initialised. | |
1155 | * | |
1156 | * returns: 0 if callback is successfully added | |
1157 | * -EALREADY if pool is already initialised (callback not called) | |
1158 | * -ENOENT if module for callback is not alive | |
1159 | */ | |
1160 | int add_random_ready_callback(struct random_ready_callback *rdy) | |
1161 | { | |
1162 | struct module *owner; | |
1163 | unsigned long flags; | |
1164 | int err = -EALREADY; | |
1165 | ||
e192be9d | 1166 | if (crng_ready()) |
205a525c HX |
1167 | return err; |
1168 | ||
1169 | owner = rdy->owner; | |
1170 | if (!try_module_get(owner)) | |
1171 | return -ENOENT; | |
1172 | ||
1173 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
e192be9d | 1174 | if (crng_ready()) |
205a525c HX |
1175 | goto out; |
1176 | ||
1177 | owner = NULL; | |
1178 | ||
1179 | list_add(&rdy->list, &random_ready_list); | |
1180 | err = 0; | |
1181 | ||
1182 | out: | |
1183 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
1184 | ||
1185 | module_put(owner); | |
1186 | ||
1187 | return err; | |
1188 | } | |
1189 | EXPORT_SYMBOL(add_random_ready_callback); | |
1190 | ||
1191 | /* | |
1192 | * Delete a previously registered readiness callback function. | |
1193 | */ | |
1194 | void del_random_ready_callback(struct random_ready_callback *rdy) | |
1195 | { | |
1196 | unsigned long flags; | |
1197 | struct module *owner = NULL; | |
1198 | ||
1199 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
1200 | if (!list_empty(&rdy->list)) { | |
1201 | list_del_init(&rdy->list); | |
1202 | owner = rdy->owner; | |
1203 | } | |
1204 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
1205 | ||
1206 | module_put(owner); | |
1207 | } | |
1208 | EXPORT_SYMBOL(del_random_ready_callback); | |
1209 | ||
c2557a30 TT |
1210 | /* |
1211 | * This function will use the architecture-specific hardware random | |
1212 | * number generator if it is available. The arch-specific hw RNG will | |
1213 | * almost certainly be faster than what we can do in software, but it | |
1214 | * is impossible to verify that it is implemented securely (as | |
1215 | * opposed, to, say, the AES encryption of a sequence number using a | |
1216 | * key known by the NSA). So it's useful if we need the speed, but | |
1217 | * only if we're willing to trust the hardware manufacturer not to | |
1218 | * have put in a back door. | |
753d433b TH |
1219 | * |
1220 | * Return number of bytes filled in. | |
c2557a30 | 1221 | */ |
753d433b | 1222 | int __must_check get_random_bytes_arch(void *buf, int nbytes) |
1da177e4 | 1223 | { |
753d433b | 1224 | int left = nbytes; |
d38bb085 | 1225 | u8 *p = buf; |
63d77173 | 1226 | |
753d433b TH |
1227 | trace_get_random_bytes_arch(left, _RET_IP_); |
1228 | while (left) { | |
63d77173 | 1229 | unsigned long v; |
753d433b | 1230 | int chunk = min_t(int, left, sizeof(unsigned long)); |
c2557a30 | 1231 | |
63d77173 PA |
1232 | if (!arch_get_random_long(&v)) |
1233 | break; | |
8ddd6efa | 1234 | |
bd29e568 | 1235 | memcpy(p, &v, chunk); |
63d77173 | 1236 | p += chunk; |
753d433b | 1237 | left -= chunk; |
63d77173 PA |
1238 | } |
1239 | ||
753d433b | 1240 | return nbytes - left; |
1da177e4 | 1241 | } |
c2557a30 TT |
1242 | EXPORT_SYMBOL(get_random_bytes_arch); |
1243 | ||
85664172 JD |
1244 | static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU); |
1245 | static int __init parse_trust_cpu(char *arg) | |
1246 | { | |
1247 | return kstrtobool(arg, &trust_cpu); | |
1248 | } | |
1249 | early_param("random.trust_cpu", parse_trust_cpu); | |
1250 | ||
1da177e4 | 1251 | /* |
85664172 JD |
1252 | * Note that setup_arch() may call add_device_randomness() |
1253 | * long before we get here. This allows seeding of the pools | |
1254 | * with some platform dependent data very early in the boot | |
1255 | * process. But it limits our options here. We must use | |
1256 | * statically allocated structures that already have all | |
1257 | * initializations complete at compile time. We should also | |
1258 | * take care not to overwrite the precious per platform data | |
1259 | * we were given. | |
1da177e4 | 1260 | */ |
85664172 | 1261 | int __init rand_initialize(void) |
1da177e4 | 1262 | { |
3e88bdff | 1263 | int i; |
902c098a | 1264 | ktime_t now = ktime_get_real(); |
85664172 | 1265 | bool arch_init = true; |
902c098a | 1266 | unsigned long rv; |
1da177e4 | 1267 | |
6e8ec255 | 1268 | for (i = BLAKE2S_BLOCK_SIZE; i > 0; i -= sizeof(rv)) { |
85664172 JD |
1269 | if (!arch_get_random_seed_long_early(&rv) && |
1270 | !arch_get_random_long_early(&rv)) { | |
1271 | rv = random_get_entropy(); | |
1272 | arch_init = false; | |
1273 | } | |
a02cf3d0 | 1274 | mix_pool_bytes(&rv, sizeof(rv)); |
85664172 | 1275 | } |
a02cf3d0 JD |
1276 | mix_pool_bytes(&now, sizeof(now)); |
1277 | mix_pool_bytes(utsname(), sizeof(*(utsname()))); | |
1278 | ||
186873c5 | 1279 | extract_entropy(base_crng.key, sizeof(base_crng.key)); |
85664172 JD |
1280 | if (arch_init && trust_cpu && crng_init < 2) { |
1281 | invalidate_batched_entropy(); | |
1282 | crng_init = 2; | |
1283 | pr_notice("crng init done (trusting CPU's manufacturer)\n"); | |
1284 | } | |
85664172 | 1285 | |
4e00b339 TT |
1286 | if (ratelimit_disable) { |
1287 | urandom_warning.interval = 0; | |
1288 | unseeded_warning.interval = 0; | |
1289 | } | |
1da177e4 LT |
1290 | return 0; |
1291 | } | |
1da177e4 | 1292 | |
9361401e | 1293 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1294 | void rand_initialize_disk(struct gendisk *disk) |
1295 | { | |
1296 | struct timer_rand_state *state; | |
1297 | ||
1298 | /* | |
f8595815 | 1299 | * If kzalloc returns null, we just won't use that entropy |
1da177e4 LT |
1300 | * source. |
1301 | */ | |
f8595815 | 1302 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
644008df TT |
1303 | if (state) { |
1304 | state->last_time = INITIAL_JIFFIES; | |
1da177e4 | 1305 | disk->random = state; |
644008df | 1306 | } |
1da177e4 | 1307 | } |
9361401e | 1308 | #endif |
1da177e4 | 1309 | |
248045b8 JD |
1310 | static ssize_t urandom_read_nowarn(struct file *file, char __user *buf, |
1311 | size_t nbytes, loff_t *ppos) | |
c6f1deb1 AL |
1312 | { |
1313 | int ret; | |
1314 | ||
c5704490 | 1315 | nbytes = min_t(size_t, nbytes, INT_MAX >> 6); |
186873c5 | 1316 | ret = get_random_bytes_user(buf, nbytes); |
c5704490 | 1317 | trace_urandom_read(8 * nbytes, 0, input_pool.entropy_count); |
c6f1deb1 AL |
1318 | return ret; |
1319 | } | |
1320 | ||
248045b8 JD |
1321 | static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes, |
1322 | loff_t *ppos) | |
1da177e4 | 1323 | { |
9b4d0087 | 1324 | static int maxwarn = 10; |
301f0595 | 1325 | |
e192be9d | 1326 | if (!crng_ready() && maxwarn > 0) { |
9b4d0087 | 1327 | maxwarn--; |
4e00b339 | 1328 | if (__ratelimit(&urandom_warning)) |
12cd53af YL |
1329 | pr_notice("%s: uninitialized urandom read (%zd bytes read)\n", |
1330 | current->comm, nbytes); | |
9b4d0087 | 1331 | } |
c6f1deb1 AL |
1332 | |
1333 | return urandom_read_nowarn(file, buf, nbytes, ppos); | |
1da177e4 LT |
1334 | } |
1335 | ||
248045b8 JD |
1336 | static ssize_t random_read(struct file *file, char __user *buf, size_t nbytes, |
1337 | loff_t *ppos) | |
30c08efe AL |
1338 | { |
1339 | int ret; | |
1340 | ||
1341 | ret = wait_for_random_bytes(); | |
1342 | if (ret != 0) | |
1343 | return ret; | |
1344 | return urandom_read_nowarn(file, buf, nbytes, ppos); | |
1345 | } | |
1346 | ||
248045b8 | 1347 | static __poll_t random_poll(struct file *file, poll_table *wait) |
1da177e4 | 1348 | { |
a11e1d43 | 1349 | __poll_t mask; |
1da177e4 | 1350 | |
30c08efe | 1351 | poll_wait(file, &crng_init_wait, wait); |
a11e1d43 LT |
1352 | poll_wait(file, &random_write_wait, wait); |
1353 | mask = 0; | |
30c08efe | 1354 | if (crng_ready()) |
a9a08845 | 1355 | mask |= EPOLLIN | EPOLLRDNORM; |
489c7fc4 | 1356 | if (input_pool.entropy_count < POOL_MIN_BITS) |
a9a08845 | 1357 | mask |= EPOLLOUT | EPOLLWRNORM; |
1da177e4 LT |
1358 | return mask; |
1359 | } | |
1360 | ||
248045b8 | 1361 | static int write_pool(const char __user *buffer, size_t count) |
1da177e4 | 1362 | { |
1da177e4 | 1363 | size_t bytes; |
91c2afca | 1364 | u8 buf[BLAKE2S_BLOCK_SIZE]; |
1da177e4 | 1365 | const char __user *p = buffer; |
1da177e4 | 1366 | |
7f397dcd MM |
1367 | while (count > 0) { |
1368 | bytes = min(count, sizeof(buf)); | |
91c2afca | 1369 | if (copy_from_user(buf, p, bytes)) |
7f397dcd | 1370 | return -EFAULT; |
7f397dcd | 1371 | count -= bytes; |
1da177e4 | 1372 | p += bytes; |
90ed1e67 | 1373 | mix_pool_bytes(buf, bytes); |
91f3f1e3 | 1374 | cond_resched(); |
1da177e4 | 1375 | } |
7f397dcd MM |
1376 | |
1377 | return 0; | |
1378 | } | |
1379 | ||
90b75ee5 MM |
1380 | static ssize_t random_write(struct file *file, const char __user *buffer, |
1381 | size_t count, loff_t *ppos) | |
7f397dcd MM |
1382 | { |
1383 | size_t ret; | |
7f397dcd | 1384 | |
90ed1e67 | 1385 | ret = write_pool(buffer, count); |
7f397dcd MM |
1386 | if (ret) |
1387 | return ret; | |
1388 | ||
7f397dcd | 1389 | return (ssize_t)count; |
1da177e4 LT |
1390 | } |
1391 | ||
43ae4860 | 1392 | static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) |
1da177e4 LT |
1393 | { |
1394 | int size, ent_count; | |
1395 | int __user *p = (int __user *)arg; | |
1396 | int retval; | |
1397 | ||
1398 | switch (cmd) { | |
1399 | case RNDGETENTCNT: | |
43ae4860 | 1400 | /* inherently racy, no point locking */ |
c5704490 | 1401 | if (put_user(input_pool.entropy_count, p)) |
1da177e4 LT |
1402 | return -EFAULT; |
1403 | return 0; | |
1404 | case RNDADDTOENTCNT: | |
1405 | if (!capable(CAP_SYS_ADMIN)) | |
1406 | return -EPERM; | |
1407 | if (get_user(ent_count, p)) | |
1408 | return -EFAULT; | |
a49c010e JD |
1409 | if (ent_count < 0) |
1410 | return -EINVAL; | |
1411 | credit_entropy_bits(ent_count); | |
1412 | return 0; | |
1da177e4 LT |
1413 | case RNDADDENTROPY: |
1414 | if (!capable(CAP_SYS_ADMIN)) | |
1415 | return -EPERM; | |
1416 | if (get_user(ent_count, p++)) | |
1417 | return -EFAULT; | |
1418 | if (ent_count < 0) | |
1419 | return -EINVAL; | |
1420 | if (get_user(size, p++)) | |
1421 | return -EFAULT; | |
90ed1e67 | 1422 | retval = write_pool((const char __user *)p, size); |
1da177e4 LT |
1423 | if (retval < 0) |
1424 | return retval; | |
a49c010e JD |
1425 | credit_entropy_bits(ent_count); |
1426 | return 0; | |
1da177e4 LT |
1427 | case RNDZAPENTCNT: |
1428 | case RNDCLEARPOOL: | |
ae9ecd92 TT |
1429 | /* |
1430 | * Clear the entropy pool counters. We no longer clear | |
1431 | * the entropy pool, as that's silly. | |
1432 | */ | |
1da177e4 LT |
1433 | if (!capable(CAP_SYS_ADMIN)) |
1434 | return -EPERM; | |
489c7fc4 | 1435 | if (xchg(&input_pool.entropy_count, 0)) { |
042e293e JD |
1436 | wake_up_interruptible(&random_write_wait); |
1437 | kill_fasync(&fasync, SIGIO, POLL_OUT); | |
1438 | } | |
1da177e4 | 1439 | return 0; |
d848e5f8 TT |
1440 | case RNDRESEEDCRNG: |
1441 | if (!capable(CAP_SYS_ADMIN)) | |
1442 | return -EPERM; | |
1443 | if (crng_init < 2) | |
1444 | return -ENODATA; | |
a9412d51 | 1445 | crng_reseed(); |
d848e5f8 | 1446 | return 0; |
1da177e4 LT |
1447 | default: |
1448 | return -EINVAL; | |
1449 | } | |
1450 | } | |
1451 | ||
9a6f70bb JD |
1452 | static int random_fasync(int fd, struct file *filp, int on) |
1453 | { | |
1454 | return fasync_helper(fd, filp, on, &fasync); | |
1455 | } | |
1456 | ||
2b8693c0 | 1457 | const struct file_operations random_fops = { |
248045b8 | 1458 | .read = random_read, |
1da177e4 | 1459 | .write = random_write, |
248045b8 | 1460 | .poll = random_poll, |
43ae4860 | 1461 | .unlocked_ioctl = random_ioctl, |
507e4e2b | 1462 | .compat_ioctl = compat_ptr_ioctl, |
9a6f70bb | 1463 | .fasync = random_fasync, |
6038f373 | 1464 | .llseek = noop_llseek, |
1da177e4 LT |
1465 | }; |
1466 | ||
2b8693c0 | 1467 | const struct file_operations urandom_fops = { |
248045b8 | 1468 | .read = urandom_read, |
1da177e4 | 1469 | .write = random_write, |
43ae4860 | 1470 | .unlocked_ioctl = random_ioctl, |
4aa37c46 | 1471 | .compat_ioctl = compat_ptr_ioctl, |
9a6f70bb | 1472 | .fasync = random_fasync, |
6038f373 | 1473 | .llseek = noop_llseek, |
1da177e4 LT |
1474 | }; |
1475 | ||
248045b8 JD |
1476 | SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int, |
1477 | flags) | |
c6e9d6f3 | 1478 | { |
e297a783 JD |
1479 | int ret; |
1480 | ||
248045b8 | 1481 | if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE)) |
75551dbf AL |
1482 | return -EINVAL; |
1483 | ||
1484 | /* | |
1485 | * Requesting insecure and blocking randomness at the same time makes | |
1486 | * no sense. | |
1487 | */ | |
248045b8 | 1488 | if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM)) |
c6e9d6f3 TT |
1489 | return -EINVAL; |
1490 | ||
1491 | if (count > INT_MAX) | |
1492 | count = INT_MAX; | |
1493 | ||
75551dbf | 1494 | if (!(flags & GRND_INSECURE) && !crng_ready()) { |
c6e9d6f3 TT |
1495 | if (flags & GRND_NONBLOCK) |
1496 | return -EAGAIN; | |
e297a783 JD |
1497 | ret = wait_for_random_bytes(); |
1498 | if (unlikely(ret)) | |
1499 | return ret; | |
c6e9d6f3 | 1500 | } |
c6f1deb1 | 1501 | return urandom_read_nowarn(NULL, buf, count, NULL); |
c6e9d6f3 TT |
1502 | } |
1503 | ||
1da177e4 LT |
1504 | /******************************************************************** |
1505 | * | |
1506 | * Sysctl interface | |
1507 | * | |
1508 | ********************************************************************/ | |
1509 | ||
1510 | #ifdef CONFIG_SYSCTL | |
1511 | ||
1512 | #include <linux/sysctl.h> | |
1513 | ||
db61ffe3 | 1514 | static int random_min_urandom_seed = 60; |
489c7fc4 JD |
1515 | static int random_write_wakeup_bits = POOL_MIN_BITS; |
1516 | static int sysctl_poolsize = POOL_BITS; | |
1da177e4 LT |
1517 | static char sysctl_bootid[16]; |
1518 | ||
1519 | /* | |
f22052b2 | 1520 | * This function is used to return both the bootid UUID, and random |
1da177e4 LT |
1521 | * UUID. The difference is in whether table->data is NULL; if it is, |
1522 | * then a new UUID is generated and returned to the user. | |
1523 | * | |
f22052b2 GP |
1524 | * If the user accesses this via the proc interface, the UUID will be |
1525 | * returned as an ASCII string in the standard UUID format; if via the | |
1526 | * sysctl system call, as 16 bytes of binary data. | |
1da177e4 | 1527 | */ |
248045b8 JD |
1528 | static int proc_do_uuid(struct ctl_table *table, int write, void *buffer, |
1529 | size_t *lenp, loff_t *ppos) | |
1da177e4 | 1530 | { |
a151427e | 1531 | struct ctl_table fake_table; |
1da177e4 LT |
1532 | unsigned char buf[64], tmp_uuid[16], *uuid; |
1533 | ||
1534 | uuid = table->data; | |
1535 | if (!uuid) { | |
1536 | uuid = tmp_uuid; | |
1da177e4 | 1537 | generate_random_uuid(uuid); |
44e4360f MD |
1538 | } else { |
1539 | static DEFINE_SPINLOCK(bootid_spinlock); | |
1540 | ||
1541 | spin_lock(&bootid_spinlock); | |
1542 | if (!uuid[8]) | |
1543 | generate_random_uuid(uuid); | |
1544 | spin_unlock(&bootid_spinlock); | |
1545 | } | |
1da177e4 | 1546 | |
35900771 JP |
1547 | sprintf(buf, "%pU", uuid); |
1548 | ||
1da177e4 LT |
1549 | fake_table.data = buf; |
1550 | fake_table.maxlen = sizeof(buf); | |
1551 | ||
8d65af78 | 1552 | return proc_dostring(&fake_table, write, buffer, lenp, ppos); |
1da177e4 LT |
1553 | } |
1554 | ||
5475e8f0 | 1555 | static struct ctl_table random_table[] = { |
1da177e4 | 1556 | { |
1da177e4 LT |
1557 | .procname = "poolsize", |
1558 | .data = &sysctl_poolsize, | |
1559 | .maxlen = sizeof(int), | |
1560 | .mode = 0444, | |
6d456111 | 1561 | .proc_handler = proc_dointvec, |
1da177e4 LT |
1562 | }, |
1563 | { | |
1da177e4 | 1564 | .procname = "entropy_avail", |
c5704490 | 1565 | .data = &input_pool.entropy_count, |
1da177e4 LT |
1566 | .maxlen = sizeof(int), |
1567 | .mode = 0444, | |
c5704490 | 1568 | .proc_handler = proc_dointvec, |
1da177e4 | 1569 | }, |
1da177e4 | 1570 | { |
1da177e4 | 1571 | .procname = "write_wakeup_threshold", |
2132a96f | 1572 | .data = &random_write_wakeup_bits, |
1da177e4 LT |
1573 | .maxlen = sizeof(int), |
1574 | .mode = 0644, | |
489c7fc4 | 1575 | .proc_handler = proc_dointvec, |
1da177e4 | 1576 | }, |
f5c2742c TT |
1577 | { |
1578 | .procname = "urandom_min_reseed_secs", | |
1579 | .data = &random_min_urandom_seed, | |
1580 | .maxlen = sizeof(int), | |
1581 | .mode = 0644, | |
1582 | .proc_handler = proc_dointvec, | |
1583 | }, | |
1da177e4 | 1584 | { |
1da177e4 LT |
1585 | .procname = "boot_id", |
1586 | .data = &sysctl_bootid, | |
1587 | .maxlen = 16, | |
1588 | .mode = 0444, | |
6d456111 | 1589 | .proc_handler = proc_do_uuid, |
1da177e4 LT |
1590 | }, |
1591 | { | |
1da177e4 LT |
1592 | .procname = "uuid", |
1593 | .maxlen = 16, | |
1594 | .mode = 0444, | |
6d456111 | 1595 | .proc_handler = proc_do_uuid, |
1da177e4 | 1596 | }, |
43759d4f TT |
1597 | #ifdef ADD_INTERRUPT_BENCH |
1598 | { | |
1599 | .procname = "add_interrupt_avg_cycles", | |
1600 | .data = &avg_cycles, | |
1601 | .maxlen = sizeof(avg_cycles), | |
1602 | .mode = 0444, | |
1603 | .proc_handler = proc_doulongvec_minmax, | |
1604 | }, | |
1605 | { | |
1606 | .procname = "add_interrupt_avg_deviation", | |
1607 | .data = &avg_deviation, | |
1608 | .maxlen = sizeof(avg_deviation), | |
1609 | .mode = 0444, | |
1610 | .proc_handler = proc_doulongvec_minmax, | |
1611 | }, | |
1612 | #endif | |
894d2491 | 1613 | { } |
1da177e4 | 1614 | }; |
5475e8f0 XN |
1615 | |
1616 | /* | |
1617 | * rand_initialize() is called before sysctl_init(), | |
1618 | * so we cannot call register_sysctl_init() in rand_initialize() | |
1619 | */ | |
1620 | static int __init random_sysctls_init(void) | |
1621 | { | |
1622 | register_sysctl_init("kernel/random", random_table); | |
1623 | return 0; | |
1624 | } | |
1625 | device_initcall(random_sysctls_init); | |
248045b8 | 1626 | #endif /* CONFIG_SYSCTL */ |
1da177e4 | 1627 | |
77760fd7 JD |
1628 | static atomic_t batch_generation = ATOMIC_INIT(0); |
1629 | ||
f5b98461 JD |
1630 | struct batched_entropy { |
1631 | union { | |
186873c5 JD |
1632 | /* |
1633 | * We make this 1.5x a ChaCha block, so that we get the | |
1634 | * remaining 32 bytes from fast key erasure, plus one full | |
1635 | * block from the detached ChaCha state. We can increase | |
1636 | * the size of this later if needed so long as we keep the | |
1637 | * formula of (integer_blocks + 0.5) * CHACHA_BLOCK_SIZE. | |
1638 | */ | |
1639 | u64 entropy_u64[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u64))]; | |
1640 | u32 entropy_u32[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u32))]; | |
f5b98461 | 1641 | }; |
77760fd7 | 1642 | local_lock_t lock; |
f5b98461 | 1643 | unsigned int position; |
77760fd7 | 1644 | int generation; |
f5b98461 | 1645 | }; |
b1132dea | 1646 | |
1da177e4 | 1647 | /* |
f5b98461 | 1648 | * Get a random word for internal kernel use only. The quality of the random |
186873c5 JD |
1649 | * number is good as /dev/urandom. In order to ensure that the randomness |
1650 | * provided by this function is okay, the function wait_for_random_bytes() | |
1651 | * should be called and return 0 at least once at any point prior. | |
1da177e4 | 1652 | */ |
b7d5dc21 | 1653 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = { |
186873c5 JD |
1654 | .lock = INIT_LOCAL_LOCK(batched_entropy_u64.lock), |
1655 | .position = UINT_MAX | |
b7d5dc21 SAS |
1656 | }; |
1657 | ||
c440408c | 1658 | u64 get_random_u64(void) |
1da177e4 | 1659 | { |
c440408c | 1660 | u64 ret; |
b7d5dc21 | 1661 | unsigned long flags; |
f5b98461 | 1662 | struct batched_entropy *batch; |
eecabf56 | 1663 | static void *previous; |
77760fd7 | 1664 | int next_gen; |
8a0a9bd4 | 1665 | |
eecabf56 | 1666 | warn_unseeded_randomness(&previous); |
d06bfd19 | 1667 | |
77760fd7 | 1668 | local_lock_irqsave(&batched_entropy_u64.lock, flags); |
b7d5dc21 | 1669 | batch = raw_cpu_ptr(&batched_entropy_u64); |
77760fd7 JD |
1670 | |
1671 | next_gen = atomic_read(&batch_generation); | |
186873c5 | 1672 | if (batch->position >= ARRAY_SIZE(batch->entropy_u64) || |
77760fd7 | 1673 | next_gen != batch->generation) { |
186873c5 | 1674 | _get_random_bytes(batch->entropy_u64, sizeof(batch->entropy_u64)); |
f5b98461 | 1675 | batch->position = 0; |
77760fd7 | 1676 | batch->generation = next_gen; |
f5b98461 | 1677 | } |
77760fd7 | 1678 | |
186873c5 JD |
1679 | ret = batch->entropy_u64[batch->position]; |
1680 | batch->entropy_u64[batch->position] = 0; | |
1681 | ++batch->position; | |
77760fd7 | 1682 | local_unlock_irqrestore(&batched_entropy_u64.lock, flags); |
8a0a9bd4 | 1683 | return ret; |
1da177e4 | 1684 | } |
c440408c | 1685 | EXPORT_SYMBOL(get_random_u64); |
1da177e4 | 1686 | |
b7d5dc21 | 1687 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = { |
186873c5 JD |
1688 | .lock = INIT_LOCAL_LOCK(batched_entropy_u32.lock), |
1689 | .position = UINT_MAX | |
b7d5dc21 | 1690 | }; |
77760fd7 | 1691 | |
c440408c | 1692 | u32 get_random_u32(void) |
f5b98461 | 1693 | { |
c440408c | 1694 | u32 ret; |
b7d5dc21 | 1695 | unsigned long flags; |
f5b98461 | 1696 | struct batched_entropy *batch; |
eecabf56 | 1697 | static void *previous; |
77760fd7 | 1698 | int next_gen; |
ec9ee4ac | 1699 | |
eecabf56 | 1700 | warn_unseeded_randomness(&previous); |
d06bfd19 | 1701 | |
77760fd7 | 1702 | local_lock_irqsave(&batched_entropy_u32.lock, flags); |
b7d5dc21 | 1703 | batch = raw_cpu_ptr(&batched_entropy_u32); |
77760fd7 JD |
1704 | |
1705 | next_gen = atomic_read(&batch_generation); | |
186873c5 | 1706 | if (batch->position >= ARRAY_SIZE(batch->entropy_u32) || |
77760fd7 | 1707 | next_gen != batch->generation) { |
186873c5 | 1708 | _get_random_bytes(batch->entropy_u32, sizeof(batch->entropy_u32)); |
f5b98461 | 1709 | batch->position = 0; |
77760fd7 | 1710 | batch->generation = next_gen; |
f5b98461 | 1711 | } |
77760fd7 | 1712 | |
186873c5 JD |
1713 | ret = batch->entropy_u32[batch->position]; |
1714 | batch->entropy_u32[batch->position] = 0; | |
1715 | ++batch->position; | |
77760fd7 | 1716 | local_unlock_irqrestore(&batched_entropy_u32.lock, flags); |
ec9ee4ac DC |
1717 | return ret; |
1718 | } | |
c440408c | 1719 | EXPORT_SYMBOL(get_random_u32); |
ec9ee4ac | 1720 | |
b169c13d JD |
1721 | /* It's important to invalidate all potential batched entropy that might |
1722 | * be stored before the crng is initialized, which we can do lazily by | |
77760fd7 JD |
1723 | * bumping the generation counter. |
1724 | */ | |
b169c13d JD |
1725 | static void invalidate_batched_entropy(void) |
1726 | { | |
77760fd7 | 1727 | atomic_inc(&batch_generation); |
b169c13d JD |
1728 | } |
1729 | ||
99fdafde JC |
1730 | /** |
1731 | * randomize_page - Generate a random, page aligned address | |
1732 | * @start: The smallest acceptable address the caller will take. | |
1733 | * @range: The size of the area, starting at @start, within which the | |
1734 | * random address must fall. | |
1735 | * | |
1736 | * If @start + @range would overflow, @range is capped. | |
1737 | * | |
1738 | * NOTE: Historical use of randomize_range, which this replaces, presumed that | |
1739 | * @start was already page aligned. We now align it regardless. | |
1740 | * | |
1741 | * Return: A page aligned address within [start, start + range). On error, | |
1742 | * @start is returned. | |
1743 | */ | |
248045b8 | 1744 | unsigned long randomize_page(unsigned long start, unsigned long range) |
99fdafde JC |
1745 | { |
1746 | if (!PAGE_ALIGNED(start)) { | |
1747 | range -= PAGE_ALIGN(start) - start; | |
1748 | start = PAGE_ALIGN(start); | |
1749 | } | |
1750 | ||
1751 | if (start > ULONG_MAX - range) | |
1752 | range = ULONG_MAX - start; | |
1753 | ||
1754 | range >>= PAGE_SHIFT; | |
1755 | ||
1756 | if (range == 0) | |
1757 | return start; | |
1758 | ||
1759 | return start + (get_random_long() % range << PAGE_SHIFT); | |
1760 | } | |
1761 | ||
c84dbf61 TD |
1762 | /* Interface for in-kernel drivers of true hardware RNGs. |
1763 | * Those devices may produce endless random bits and will be throttled | |
1764 | * when our pool is full. | |
1765 | */ | |
1766 | void add_hwgenerator_randomness(const char *buffer, size_t count, | |
1767 | size_t entropy) | |
1768 | { | |
43838a23 | 1769 | if (unlikely(crng_init == 0)) { |
73c7733f | 1770 | size_t ret = crng_fast_load(buffer, count); |
90ed1e67 | 1771 | mix_pool_bytes(buffer, ret); |
73c7733f JD |
1772 | count -= ret; |
1773 | buffer += ret; | |
1774 | if (!count || crng_init == 0) | |
1775 | return; | |
3371f3da | 1776 | } |
e192be9d | 1777 | |
c321e907 | 1778 | /* Throttle writing if we're above the trickle threshold. |
489c7fc4 JD |
1779 | * We'll be woken up again once below POOL_MIN_BITS, when |
1780 | * the calling thread is about to terminate, or once | |
1781 | * CRNG_RESEED_INTERVAL has elapsed. | |
e192be9d | 1782 | */ |
c321e907 | 1783 | wait_event_interruptible_timeout(random_write_wait, |
f7e67b8e | 1784 | !system_wq || kthread_should_stop() || |
489c7fc4 | 1785 | input_pool.entropy_count < POOL_MIN_BITS, |
c321e907 | 1786 | CRNG_RESEED_INTERVAL); |
90ed1e67 JD |
1787 | mix_pool_bytes(buffer, count); |
1788 | credit_entropy_bits(entropy); | |
c84dbf61 TD |
1789 | } |
1790 | EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); | |
428826f5 HYW |
1791 | |
1792 | /* Handle random seed passed by bootloader. | |
1793 | * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise | |
1794 | * it would be regarded as device data. | |
1795 | * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER. | |
1796 | */ | |
1797 | void add_bootloader_randomness(const void *buf, unsigned int size) | |
1798 | { | |
1799 | if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER)) | |
1800 | add_hwgenerator_randomness(buf, size, size * 8); | |
1801 | else | |
1802 | add_device_randomness(buf, size); | |
1803 | } | |
3fd57e7a | 1804 | EXPORT_SYMBOL_GPL(add_bootloader_randomness); |