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1da177e4 LT |
1 | /* |
2 | * random.c -- A strong random number generator | |
3 | * | |
b169c13d JD |
4 | * Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All |
5 | * Rights Reserved. | |
6 | * | |
9e95ce27 | 7 | * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005 |
1da177e4 LT |
8 | * |
9 | * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All | |
10 | * rights reserved. | |
11 | * | |
12 | * Redistribution and use in source and binary forms, with or without | |
13 | * modification, are permitted provided that the following conditions | |
14 | * are met: | |
15 | * 1. Redistributions of source code must retain the above copyright | |
16 | * notice, and the entire permission notice in its entirety, | |
17 | * including the disclaimer of warranties. | |
18 | * 2. Redistributions in binary form must reproduce the above copyright | |
19 | * notice, this list of conditions and the following disclaimer in the | |
20 | * documentation and/or other materials provided with the distribution. | |
21 | * 3. The name of the author may not be used to endorse or promote | |
22 | * products derived from this software without specific prior | |
23 | * written permission. | |
24 | * | |
25 | * ALTERNATIVELY, this product may be distributed under the terms of | |
26 | * the GNU General Public License, in which case the provisions of the GPL are | |
27 | * required INSTEAD OF the above restrictions. (This clause is | |
28 | * necessary due to a potential bad interaction between the GPL and | |
29 | * the restrictions contained in a BSD-style copyright.) | |
30 | * | |
31 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED | |
32 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
33 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF | |
34 | * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE | |
35 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | |
36 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT | |
37 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR | |
38 | * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF | |
39 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
40 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE | |
41 | * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH | |
42 | * DAMAGE. | |
43 | */ | |
44 | ||
45 | /* | |
46 | * (now, with legal B.S. out of the way.....) | |
47 | * | |
48 | * This routine gathers environmental noise from device drivers, etc., | |
49 | * and returns good random numbers, suitable for cryptographic use. | |
50 | * Besides the obvious cryptographic uses, these numbers are also good | |
51 | * for seeding TCP sequence numbers, and other places where it is | |
52 | * desirable to have numbers which are not only random, but hard to | |
53 | * predict by an attacker. | |
54 | * | |
55 | * Theory of operation | |
56 | * =================== | |
57 | * | |
58 | * Computers are very predictable devices. Hence it is extremely hard | |
59 | * to produce truly random numbers on a computer --- as opposed to | |
60 | * pseudo-random numbers, which can easily generated by using a | |
61 | * algorithm. Unfortunately, it is very easy for attackers to guess | |
62 | * the sequence of pseudo-random number generators, and for some | |
63 | * applications this is not acceptable. So instead, we must try to | |
64 | * gather "environmental noise" from the computer's environment, which | |
65 | * must be hard for outside attackers to observe, and use that to | |
66 | * generate random numbers. In a Unix environment, this is best done | |
67 | * from inside the kernel. | |
68 | * | |
69 | * Sources of randomness from the environment include inter-keyboard | |
70 | * timings, inter-interrupt timings from some interrupts, and other | |
71 | * events which are both (a) non-deterministic and (b) hard for an | |
72 | * outside observer to measure. Randomness from these sources are | |
73 | * added to an "entropy pool", which is mixed using a CRC-like function. | |
74 | * This is not cryptographically strong, but it is adequate assuming | |
75 | * the randomness is not chosen maliciously, and it is fast enough that | |
76 | * the overhead of doing it on every interrupt is very reasonable. | |
77 | * As random bytes are mixed into the entropy pool, the routines keep | |
78 | * an *estimate* of how many bits of randomness have been stored into | |
79 | * the random number generator's internal state. | |
80 | * | |
81 | * When random bytes are desired, they are obtained by taking the SHA | |
82 | * hash of the contents of the "entropy pool". The SHA hash avoids | |
83 | * exposing the internal state of the entropy pool. It is believed to | |
84 | * be computationally infeasible to derive any useful information | |
85 | * about the input of SHA from its output. Even if it is possible to | |
86 | * analyze SHA in some clever way, as long as the amount of data | |
87 | * returned from the generator is less than the inherent entropy in | |
88 | * the pool, the output data is totally unpredictable. For this | |
89 | * reason, the routine decreases its internal estimate of how many | |
90 | * bits of "true randomness" are contained in the entropy pool as it | |
91 | * outputs random numbers. | |
92 | * | |
93 | * If this estimate goes to zero, the routine can still generate | |
94 | * random numbers; however, an attacker may (at least in theory) be | |
95 | * able to infer the future output of the generator from prior | |
96 | * outputs. This requires successful cryptanalysis of SHA, which is | |
97 | * not believed to be feasible, but there is a remote possibility. | |
98 | * Nonetheless, these numbers should be useful for the vast majority | |
99 | * of purposes. | |
100 | * | |
101 | * Exported interfaces ---- output | |
102 | * =============================== | |
103 | * | |
92e507d2 GS |
104 | * There are four exported interfaces; two for use within the kernel, |
105 | * and two or use from userspace. | |
1da177e4 | 106 | * |
92e507d2 GS |
107 | * Exported interfaces ---- userspace output |
108 | * ----------------------------------------- | |
1da177e4 | 109 | * |
92e507d2 | 110 | * The userspace interfaces are two character devices /dev/random and |
1da177e4 LT |
111 | * /dev/urandom. /dev/random is suitable for use when very high |
112 | * quality randomness is desired (for example, for key generation or | |
113 | * one-time pads), as it will only return a maximum of the number of | |
114 | * bits of randomness (as estimated by the random number generator) | |
115 | * contained in the entropy pool. | |
116 | * | |
117 | * The /dev/urandom device does not have this limit, and will return | |
118 | * as many bytes as are requested. As more and more random bytes are | |
119 | * requested without giving time for the entropy pool to recharge, | |
120 | * this will result in random numbers that are merely cryptographically | |
121 | * strong. For many applications, however, this is acceptable. | |
122 | * | |
92e507d2 GS |
123 | * Exported interfaces ---- kernel output |
124 | * -------------------------------------- | |
125 | * | |
126 | * The primary kernel interface is | |
127 | * | |
128 | * void get_random_bytes(void *buf, int nbytes); | |
129 | * | |
130 | * This interface will return the requested number of random bytes, | |
131 | * and place it in the requested buffer. This is equivalent to a | |
132 | * read from /dev/urandom. | |
133 | * | |
134 | * For less critical applications, there are the functions: | |
135 | * | |
136 | * u32 get_random_u32() | |
137 | * u64 get_random_u64() | |
138 | * unsigned int get_random_int() | |
139 | * unsigned long get_random_long() | |
140 | * | |
141 | * These are produced by a cryptographic RNG seeded from get_random_bytes, | |
142 | * and so do not deplete the entropy pool as much. These are recommended | |
143 | * for most in-kernel operations *if the result is going to be stored in | |
144 | * the kernel*. | |
145 | * | |
146 | * Specifically, the get_random_int() family do not attempt to do | |
147 | * "anti-backtracking". If you capture the state of the kernel (e.g. | |
148 | * by snapshotting the VM), you can figure out previous get_random_int() | |
149 | * return values. But if the value is stored in the kernel anyway, | |
150 | * this is not a problem. | |
151 | * | |
152 | * It *is* safe to expose get_random_int() output to attackers (e.g. as | |
153 | * network cookies); given outputs 1..n, it's not feasible to predict | |
154 | * outputs 0 or n+1. The only concern is an attacker who breaks into | |
155 | * the kernel later; the get_random_int() engine is not reseeded as | |
156 | * often as the get_random_bytes() one. | |
157 | * | |
158 | * get_random_bytes() is needed for keys that need to stay secret after | |
159 | * they are erased from the kernel. For example, any key that will | |
160 | * be wrapped and stored encrypted. And session encryption keys: we'd | |
161 | * like to know that after the session is closed and the keys erased, | |
162 | * the plaintext is unrecoverable to someone who recorded the ciphertext. | |
163 | * | |
164 | * But for network ports/cookies, stack canaries, PRNG seeds, address | |
165 | * space layout randomization, session *authentication* keys, or other | |
166 | * applications where the sensitive data is stored in the kernel in | |
167 | * plaintext for as long as it's sensitive, the get_random_int() family | |
168 | * is just fine. | |
169 | * | |
170 | * Consider ASLR. We want to keep the address space secret from an | |
171 | * outside attacker while the process is running, but once the address | |
172 | * space is torn down, it's of no use to an attacker any more. And it's | |
173 | * stored in kernel data structures as long as it's alive, so worrying | |
174 | * about an attacker's ability to extrapolate it from the get_random_int() | |
175 | * CRNG is silly. | |
176 | * | |
177 | * Even some cryptographic keys are safe to generate with get_random_int(). | |
178 | * In particular, keys for SipHash are generally fine. Here, knowledge | |
179 | * of the key authorizes you to do something to a kernel object (inject | |
180 | * packets to a network connection, or flood a hash table), and the | |
181 | * key is stored with the object being protected. Once it goes away, | |
182 | * we no longer care if anyone knows the key. | |
183 | * | |
184 | * prandom_u32() | |
185 | * ------------- | |
186 | * | |
187 | * For even weaker applications, see the pseudorandom generator | |
188 | * prandom_u32(), prandom_max(), and prandom_bytes(). If the random | |
189 | * numbers aren't security-critical at all, these are *far* cheaper. | |
190 | * Useful for self-tests, random error simulation, randomized backoffs, | |
191 | * and any other application where you trust that nobody is trying to | |
192 | * maliciously mess with you by guessing the "random" numbers. | |
193 | * | |
1da177e4 LT |
194 | * Exported interfaces ---- input |
195 | * ============================== | |
196 | * | |
197 | * The current exported interfaces for gathering environmental noise | |
198 | * from the devices are: | |
199 | * | |
a2080a67 | 200 | * void add_device_randomness(const void *buf, unsigned int size); |
1da177e4 LT |
201 | * void add_input_randomness(unsigned int type, unsigned int code, |
202 | * unsigned int value); | |
703f7066 | 203 | * void add_interrupt_randomness(int irq); |
442a4fff | 204 | * void add_disk_randomness(struct gendisk *disk); |
2b6c6e3d MB |
205 | * void add_hwgenerator_randomness(const char *buffer, size_t count, |
206 | * size_t entropy); | |
207 | * void add_bootloader_randomness(const void *buf, unsigned int size); | |
1da177e4 | 208 | * |
a2080a67 LT |
209 | * add_device_randomness() is for adding data to the random pool that |
210 | * is likely to differ between two devices (or possibly even per boot). | |
211 | * This would be things like MAC addresses or serial numbers, or the | |
212 | * read-out of the RTC. This does *not* add any actual entropy to the | |
213 | * pool, but it initializes the pool to different values for devices | |
214 | * that might otherwise be identical and have very little entropy | |
215 | * available to them (particularly common in the embedded world). | |
216 | * | |
1da177e4 LT |
217 | * add_input_randomness() uses the input layer interrupt timing, as well as |
218 | * the event type information from the hardware. | |
219 | * | |
775f4b29 TT |
220 | * add_interrupt_randomness() uses the interrupt timing as random |
221 | * inputs to the entropy pool. Using the cycle counters and the irq source | |
222 | * as inputs, it feeds the randomness roughly once a second. | |
442a4fff JW |
223 | * |
224 | * add_disk_randomness() uses what amounts to the seek time of block | |
225 | * layer request events, on a per-disk_devt basis, as input to the | |
226 | * entropy pool. Note that high-speed solid state drives with very low | |
227 | * seek times do not make for good sources of entropy, as their seek | |
228 | * times are usually fairly consistent. | |
1da177e4 LT |
229 | * |
230 | * All of these routines try to estimate how many bits of randomness a | |
231 | * particular randomness source. They do this by keeping track of the | |
232 | * first and second order deltas of the event timings. | |
233 | * | |
2b6c6e3d MB |
234 | * add_hwgenerator_randomness() is for true hardware RNGs, and will credit |
235 | * entropy as specified by the caller. If the entropy pool is full it will | |
236 | * block until more entropy is needed. | |
237 | * | |
238 | * add_bootloader_randomness() is the same as add_hwgenerator_randomness() or | |
239 | * add_device_randomness(), depending on whether or not the configuration | |
240 | * option CONFIG_RANDOM_TRUST_BOOTLOADER is set. | |
241 | * | |
1da177e4 LT |
242 | * Ensuring unpredictability at system startup |
243 | * ============================================ | |
244 | * | |
245 | * When any operating system starts up, it will go through a sequence | |
246 | * of actions that are fairly predictable by an adversary, especially | |
247 | * if the start-up does not involve interaction with a human operator. | |
248 | * This reduces the actual number of bits of unpredictability in the | |
249 | * entropy pool below the value in entropy_count. In order to | |
250 | * counteract this effect, it helps to carry information in the | |
251 | * entropy pool across shut-downs and start-ups. To do this, put the | |
252 | * following lines an appropriate script which is run during the boot | |
253 | * sequence: | |
254 | * | |
255 | * echo "Initializing random number generator..." | |
256 | * random_seed=/var/run/random-seed | |
257 | * # Carry a random seed from start-up to start-up | |
258 | * # Load and then save the whole entropy pool | |
259 | * if [ -f $random_seed ]; then | |
260 | * cat $random_seed >/dev/urandom | |
261 | * else | |
262 | * touch $random_seed | |
263 | * fi | |
264 | * chmod 600 $random_seed | |
265 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 | |
266 | * | |
267 | * and the following lines in an appropriate script which is run as | |
268 | * the system is shutdown: | |
269 | * | |
270 | * # Carry a random seed from shut-down to start-up | |
271 | * # Save the whole entropy pool | |
272 | * echo "Saving random seed..." | |
273 | * random_seed=/var/run/random-seed | |
274 | * touch $random_seed | |
275 | * chmod 600 $random_seed | |
276 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 | |
277 | * | |
278 | * For example, on most modern systems using the System V init | |
279 | * scripts, such code fragments would be found in | |
280 | * /etc/rc.d/init.d/random. On older Linux systems, the correct script | |
281 | * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0. | |
282 | * | |
283 | * Effectively, these commands cause the contents of the entropy pool | |
284 | * to be saved at shut-down time and reloaded into the entropy pool at | |
285 | * start-up. (The 'dd' in the addition to the bootup script is to | |
286 | * make sure that /etc/random-seed is different for every start-up, | |
287 | * even if the system crashes without executing rc.0.) Even with | |
288 | * complete knowledge of the start-up activities, predicting the state | |
289 | * of the entropy pool requires knowledge of the previous history of | |
290 | * the system. | |
291 | * | |
292 | * Configuring the /dev/random driver under Linux | |
293 | * ============================================== | |
294 | * | |
295 | * The /dev/random driver under Linux uses minor numbers 8 and 9 of | |
296 | * the /dev/mem major number (#1). So if your system does not have | |
297 | * /dev/random and /dev/urandom created already, they can be created | |
298 | * by using the commands: | |
299 | * | |
300 | * mknod /dev/random c 1 8 | |
301 | * mknod /dev/urandom c 1 9 | |
302 | * | |
303 | * Acknowledgements: | |
304 | * ================= | |
305 | * | |
306 | * Ideas for constructing this random number generator were derived | |
307 | * from Pretty Good Privacy's random number generator, and from private | |
308 | * discussions with Phil Karn. Colin Plumb provided a faster random | |
309 | * number generator, which speed up the mixing function of the entropy | |
310 | * pool, taken from PGPfone. Dale Worley has also contributed many | |
311 | * useful ideas and suggestions to improve this driver. | |
312 | * | |
313 | * Any flaws in the design are solely my responsibility, and should | |
314 | * not be attributed to the Phil, Colin, or any of authors of PGP. | |
315 | * | |
316 | * Further background information on this topic may be obtained from | |
317 | * RFC 1750, "Randomness Recommendations for Security", by Donald | |
318 | * Eastlake, Steve Crocker, and Jeff Schiller. | |
319 | */ | |
320 | ||
12cd53af YL |
321 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
322 | ||
1da177e4 | 323 | #include <linux/utsname.h> |
1da177e4 LT |
324 | #include <linux/module.h> |
325 | #include <linux/kernel.h> | |
326 | #include <linux/major.h> | |
327 | #include <linux/string.h> | |
328 | #include <linux/fcntl.h> | |
329 | #include <linux/slab.h> | |
330 | #include <linux/random.h> | |
331 | #include <linux/poll.h> | |
332 | #include <linux/init.h> | |
333 | #include <linux/fs.h> | |
334 | #include <linux/genhd.h> | |
335 | #include <linux/interrupt.h> | |
27ac792c | 336 | #include <linux/mm.h> |
dd0f0cf5 | 337 | #include <linux/nodemask.h> |
1da177e4 | 338 | #include <linux/spinlock.h> |
c84dbf61 | 339 | #include <linux/kthread.h> |
1da177e4 | 340 | #include <linux/percpu.h> |
5b739ef8 | 341 | #include <linux/fips.h> |
775f4b29 | 342 | #include <linux/ptrace.h> |
6265e169 | 343 | #include <linux/workqueue.h> |
0244ad00 | 344 | #include <linux/irq.h> |
4e00b339 | 345 | #include <linux/ratelimit.h> |
c6e9d6f3 TT |
346 | #include <linux/syscalls.h> |
347 | #include <linux/completion.h> | |
8da4b8c4 | 348 | #include <linux/uuid.h> |
1ca1b917 | 349 | #include <crypto/chacha.h> |
a24d22b2 | 350 | #include <crypto/sha1.h> |
d178a1eb | 351 | |
1da177e4 | 352 | #include <asm/processor.h> |
7c0f6ba6 | 353 | #include <linux/uaccess.h> |
1da177e4 | 354 | #include <asm/irq.h> |
775f4b29 | 355 | #include <asm/irq_regs.h> |
1da177e4 LT |
356 | #include <asm/io.h> |
357 | ||
00ce1db1 TT |
358 | #define CREATE_TRACE_POINTS |
359 | #include <trace/events/random.h> | |
360 | ||
43759d4f TT |
361 | /* #define ADD_INTERRUPT_BENCH */ |
362 | ||
1da177e4 LT |
363 | /* |
364 | * Configuration information | |
365 | */ | |
30e37ec5 PA |
366 | #define INPUT_POOL_SHIFT 12 |
367 | #define INPUT_POOL_WORDS (1 << (INPUT_POOL_SHIFT-5)) | |
368 | #define OUTPUT_POOL_SHIFT 10 | |
369 | #define OUTPUT_POOL_WORDS (1 << (OUTPUT_POOL_SHIFT-5)) | |
30e37ec5 | 370 | #define EXTRACT_SIZE 10 |
1da177e4 | 371 | |
1da177e4 | 372 | |
d2e7c96a PA |
373 | #define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long)) |
374 | ||
a283b5c4 | 375 | /* |
95b709b6 TT |
376 | * To allow fractional bits to be tracked, the entropy_count field is |
377 | * denominated in units of 1/8th bits. | |
30e37ec5 | 378 | * |
3bd0b5bf | 379 | * 2*(ENTROPY_SHIFT + poolbitshift) must <= 31, or the multiply in |
30e37ec5 | 380 | * credit_entropy_bits() needs to be 64 bits wide. |
a283b5c4 PA |
381 | */ |
382 | #define ENTROPY_SHIFT 3 | |
383 | #define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT) | |
384 | ||
1da177e4 LT |
385 | /* |
386 | * If the entropy count falls under this number of bits, then we | |
387 | * should wake up processes which are selecting or polling on write | |
388 | * access to /dev/random. | |
389 | */ | |
2132a96f | 390 | static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS; |
1da177e4 | 391 | |
1da177e4 | 392 | /* |
6e9fa2c8 TT |
393 | * Originally, we used a primitive polynomial of degree .poolwords |
394 | * over GF(2). The taps for various sizes are defined below. They | |
395 | * were chosen to be evenly spaced except for the last tap, which is 1 | |
396 | * to get the twisting happening as fast as possible. | |
397 | * | |
398 | * For the purposes of better mixing, we use the CRC-32 polynomial as | |
399 | * well to make a (modified) twisted Generalized Feedback Shift | |
400 | * Register. (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR | |
401 | * generators. ACM Transactions on Modeling and Computer Simulation | |
402 | * 2(3):179-194. Also see M. Matsumoto & Y. Kurita, 1994. Twisted | |
dfd38750 | 403 | * GFSR generators II. ACM Transactions on Modeling and Computer |
6e9fa2c8 TT |
404 | * Simulation 4:254-266) |
405 | * | |
406 | * Thanks to Colin Plumb for suggesting this. | |
407 | * | |
408 | * The mixing operation is much less sensitive than the output hash, | |
409 | * where we use SHA-1. All that we want of mixing operation is that | |
410 | * it be a good non-cryptographic hash; i.e. it not produce collisions | |
411 | * when fed "random" data of the sort we expect to see. As long as | |
412 | * the pool state differs for different inputs, we have preserved the | |
413 | * input entropy and done a good job. The fact that an intelligent | |
414 | * attacker can construct inputs that will produce controlled | |
415 | * alterations to the pool's state is not important because we don't | |
416 | * consider such inputs to contribute any randomness. The only | |
417 | * property we need with respect to them is that the attacker can't | |
418 | * increase his/her knowledge of the pool's state. Since all | |
419 | * additions are reversible (knowing the final state and the input, | |
420 | * you can reconstruct the initial state), if an attacker has any | |
421 | * uncertainty about the initial state, he/she can only shuffle that | |
422 | * uncertainty about, but never cause any collisions (which would | |
423 | * decrease the uncertainty). | |
424 | * | |
425 | * Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and | |
426 | * Videau in their paper, "The Linux Pseudorandom Number Generator | |
427 | * Revisited" (see: http://eprint.iacr.org/2012/251.pdf). In their | |
428 | * paper, they point out that we are not using a true Twisted GFSR, | |
429 | * since Matsumoto & Kurita used a trinomial feedback polynomial (that | |
430 | * is, with only three taps, instead of the six that we are using). | |
431 | * As a result, the resulting polynomial is neither primitive nor | |
432 | * irreducible, and hence does not have a maximal period over | |
433 | * GF(2**32). They suggest a slight change to the generator | |
434 | * polynomial which improves the resulting TGFSR polynomial to be | |
435 | * irreducible, which we have made here. | |
1da177e4 | 436 | */ |
26e0854a | 437 | static const struct poolinfo { |
3bd0b5bf RV |
438 | int poolbitshift, poolwords, poolbytes, poolfracbits; |
439 | #define S(x) ilog2(x)+5, (x), (x)*4, (x) << (ENTROPY_SHIFT+5) | |
1da177e4 LT |
440 | int tap1, tap2, tap3, tap4, tap5; |
441 | } poolinfo_table[] = { | |
6e9fa2c8 TT |
442 | /* was: x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 */ |
443 | /* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */ | |
444 | { S(128), 104, 76, 51, 25, 1 }, | |
1da177e4 LT |
445 | }; |
446 | ||
1da177e4 LT |
447 | /* |
448 | * Static global variables | |
449 | */ | |
a11e1d43 | 450 | static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); |
9a6f70bb | 451 | static struct fasync_struct *fasync; |
1da177e4 | 452 | |
205a525c HX |
453 | static DEFINE_SPINLOCK(random_ready_list_lock); |
454 | static LIST_HEAD(random_ready_list); | |
455 | ||
e192be9d TT |
456 | struct crng_state { |
457 | __u32 state[16]; | |
458 | unsigned long init_time; | |
459 | spinlock_t lock; | |
460 | }; | |
461 | ||
764ed189 | 462 | static struct crng_state primary_crng = { |
e192be9d TT |
463 | .lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock), |
464 | }; | |
465 | ||
466 | /* | |
467 | * crng_init = 0 --> Uninitialized | |
468 | * 1 --> Initialized | |
469 | * 2 --> Initialized from input_pool | |
470 | * | |
471 | * crng_init is protected by primary_crng->lock, and only increases | |
472 | * its value (from 0->1->2). | |
473 | */ | |
474 | static int crng_init = 0; | |
43838a23 | 475 | #define crng_ready() (likely(crng_init > 1)) |
e192be9d | 476 | static int crng_init_cnt = 0; |
d848e5f8 | 477 | static unsigned long crng_global_init_time = 0; |
1ca1b917 EB |
478 | #define CRNG_INIT_CNT_THRESH (2*CHACHA_KEY_SIZE) |
479 | static void _extract_crng(struct crng_state *crng, __u8 out[CHACHA_BLOCK_SIZE]); | |
c92e040d | 480 | static void _crng_backtrack_protect(struct crng_state *crng, |
1ca1b917 | 481 | __u8 tmp[CHACHA_BLOCK_SIZE], int used); |
e192be9d | 482 | static void process_random_ready_list(void); |
eecabf56 | 483 | static void _get_random_bytes(void *buf, int nbytes); |
e192be9d | 484 | |
4e00b339 TT |
485 | static struct ratelimit_state unseeded_warning = |
486 | RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3); | |
487 | static struct ratelimit_state urandom_warning = | |
488 | RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3); | |
489 | ||
490 | static int ratelimit_disable __read_mostly; | |
491 | ||
492 | module_param_named(ratelimit_disable, ratelimit_disable, int, 0644); | |
493 | MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression"); | |
494 | ||
1da177e4 LT |
495 | /********************************************************************** |
496 | * | |
497 | * OS independent entropy store. Here are the functions which handle | |
498 | * storing entropy in an entropy pool. | |
499 | * | |
500 | **********************************************************************/ | |
501 | ||
502 | struct entropy_store; | |
503 | struct entropy_store { | |
43358209 | 504 | /* read-only data: */ |
30e37ec5 | 505 | const struct poolinfo *poolinfo; |
1da177e4 LT |
506 | __u32 *pool; |
507 | const char *name; | |
1da177e4 LT |
508 | |
509 | /* read-write data: */ | |
43358209 | 510 | spinlock_t lock; |
c59974ae TT |
511 | unsigned short add_ptr; |
512 | unsigned short input_rotate; | |
cda796a3 | 513 | int entropy_count; |
c59974ae | 514 | unsigned int last_data_init:1; |
e954bc91 | 515 | __u8 last_data[EXTRACT_SIZE]; |
1da177e4 LT |
516 | }; |
517 | ||
e192be9d TT |
518 | static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
519 | size_t nbytes, int min, int rsvd); | |
520 | static ssize_t _extract_entropy(struct entropy_store *r, void *buf, | |
521 | size_t nbytes, int fips); | |
522 | ||
523 | static void crng_reseed(struct crng_state *crng, struct entropy_store *r); | |
0766f788 | 524 | static __u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy; |
1da177e4 LT |
525 | |
526 | static struct entropy_store input_pool = { | |
527 | .poolinfo = &poolinfo_table[0], | |
528 | .name = "input", | |
eece09ec | 529 | .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock), |
1da177e4 LT |
530 | .pool = input_pool_data |
531 | }; | |
532 | ||
775f4b29 TT |
533 | static __u32 const twist_table[8] = { |
534 | 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158, | |
535 | 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 }; | |
536 | ||
1da177e4 | 537 | /* |
e68e5b66 | 538 | * This function adds bytes into the entropy "pool". It does not |
1da177e4 | 539 | * update the entropy estimate. The caller should call |
adc782da | 540 | * credit_entropy_bits if this is appropriate. |
1da177e4 LT |
541 | * |
542 | * The pool is stirred with a primitive polynomial of the appropriate | |
543 | * degree, and then twisted. We twist by three bits at a time because | |
544 | * it's cheap to do so and helps slightly in the expected case where | |
545 | * the entropy is concentrated in the low-order bits. | |
546 | */ | |
00ce1db1 | 547 | static void _mix_pool_bytes(struct entropy_store *r, const void *in, |
85608f8e | 548 | int nbytes) |
1da177e4 | 549 | { |
85608f8e | 550 | unsigned long i, tap1, tap2, tap3, tap4, tap5; |
feee7697 | 551 | int input_rotate; |
1da177e4 | 552 | int wordmask = r->poolinfo->poolwords - 1; |
e68e5b66 | 553 | const char *bytes = in; |
6d38b827 | 554 | __u32 w; |
1da177e4 | 555 | |
1da177e4 LT |
556 | tap1 = r->poolinfo->tap1; |
557 | tap2 = r->poolinfo->tap2; | |
558 | tap3 = r->poolinfo->tap3; | |
559 | tap4 = r->poolinfo->tap4; | |
560 | tap5 = r->poolinfo->tap5; | |
1da177e4 | 561 | |
91fcb532 TT |
562 | input_rotate = r->input_rotate; |
563 | i = r->add_ptr; | |
1da177e4 | 564 | |
e68e5b66 MM |
565 | /* mix one byte at a time to simplify size handling and churn faster */ |
566 | while (nbytes--) { | |
c59974ae | 567 | w = rol32(*bytes++, input_rotate); |
993ba211 | 568 | i = (i - 1) & wordmask; |
1da177e4 LT |
569 | |
570 | /* XOR in the various taps */ | |
993ba211 | 571 | w ^= r->pool[i]; |
1da177e4 LT |
572 | w ^= r->pool[(i + tap1) & wordmask]; |
573 | w ^= r->pool[(i + tap2) & wordmask]; | |
574 | w ^= r->pool[(i + tap3) & wordmask]; | |
575 | w ^= r->pool[(i + tap4) & wordmask]; | |
576 | w ^= r->pool[(i + tap5) & wordmask]; | |
993ba211 MM |
577 | |
578 | /* Mix the result back in with a twist */ | |
1da177e4 | 579 | r->pool[i] = (w >> 3) ^ twist_table[w & 7]; |
feee7697 MM |
580 | |
581 | /* | |
582 | * Normally, we add 7 bits of rotation to the pool. | |
583 | * At the beginning of the pool, add an extra 7 bits | |
584 | * rotation, so that successive passes spread the | |
585 | * input bits across the pool evenly. | |
586 | */ | |
c59974ae | 587 | input_rotate = (input_rotate + (i ? 7 : 14)) & 31; |
1da177e4 LT |
588 | } |
589 | ||
91fcb532 TT |
590 | r->input_rotate = input_rotate; |
591 | r->add_ptr = i; | |
1da177e4 LT |
592 | } |
593 | ||
00ce1db1 | 594 | static void __mix_pool_bytes(struct entropy_store *r, const void *in, |
85608f8e | 595 | int nbytes) |
00ce1db1 TT |
596 | { |
597 | trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_); | |
85608f8e | 598 | _mix_pool_bytes(r, in, nbytes); |
00ce1db1 TT |
599 | } |
600 | ||
601 | static void mix_pool_bytes(struct entropy_store *r, const void *in, | |
85608f8e | 602 | int nbytes) |
1da177e4 | 603 | { |
902c098a TT |
604 | unsigned long flags; |
605 | ||
00ce1db1 | 606 | trace_mix_pool_bytes(r->name, nbytes, _RET_IP_); |
902c098a | 607 | spin_lock_irqsave(&r->lock, flags); |
85608f8e | 608 | _mix_pool_bytes(r, in, nbytes); |
902c098a | 609 | spin_unlock_irqrestore(&r->lock, flags); |
1da177e4 LT |
610 | } |
611 | ||
775f4b29 TT |
612 | struct fast_pool { |
613 | __u32 pool[4]; | |
614 | unsigned long last; | |
ee3e00e9 | 615 | unsigned short reg_idx; |
840f9507 | 616 | unsigned char count; |
775f4b29 TT |
617 | }; |
618 | ||
619 | /* | |
620 | * This is a fast mixing routine used by the interrupt randomness | |
621 | * collector. It's hardcoded for an 128 bit pool and assumes that any | |
622 | * locks that might be needed are taken by the caller. | |
623 | */ | |
43759d4f | 624 | static void fast_mix(struct fast_pool *f) |
775f4b29 | 625 | { |
43759d4f TT |
626 | __u32 a = f->pool[0], b = f->pool[1]; |
627 | __u32 c = f->pool[2], d = f->pool[3]; | |
628 | ||
629 | a += b; c += d; | |
19acc77a | 630 | b = rol32(b, 6); d = rol32(d, 27); |
43759d4f TT |
631 | d ^= a; b ^= c; |
632 | ||
633 | a += b; c += d; | |
19acc77a | 634 | b = rol32(b, 16); d = rol32(d, 14); |
43759d4f TT |
635 | d ^= a; b ^= c; |
636 | ||
637 | a += b; c += d; | |
19acc77a | 638 | b = rol32(b, 6); d = rol32(d, 27); |
43759d4f TT |
639 | d ^= a; b ^= c; |
640 | ||
641 | a += b; c += d; | |
19acc77a | 642 | b = rol32(b, 16); d = rol32(d, 14); |
43759d4f TT |
643 | d ^= a; b ^= c; |
644 | ||
645 | f->pool[0] = a; f->pool[1] = b; | |
646 | f->pool[2] = c; f->pool[3] = d; | |
655b2264 | 647 | f->count++; |
775f4b29 TT |
648 | } |
649 | ||
205a525c HX |
650 | static void process_random_ready_list(void) |
651 | { | |
652 | unsigned long flags; | |
653 | struct random_ready_callback *rdy, *tmp; | |
654 | ||
655 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
656 | list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) { | |
657 | struct module *owner = rdy->owner; | |
658 | ||
659 | list_del_init(&rdy->list); | |
660 | rdy->func(rdy); | |
661 | module_put(owner); | |
662 | } | |
663 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
664 | } | |
665 | ||
1da177e4 | 666 | /* |
a283b5c4 PA |
667 | * Credit (or debit) the entropy store with n bits of entropy. |
668 | * Use credit_entropy_bits_safe() if the value comes from userspace | |
669 | * or otherwise should be checked for extreme values. | |
1da177e4 | 670 | */ |
adc782da | 671 | static void credit_entropy_bits(struct entropy_store *r, int nbits) |
1da177e4 | 672 | { |
118a4417 | 673 | int entropy_count, orig; |
30e37ec5 PA |
674 | const int pool_size = r->poolinfo->poolfracbits; |
675 | int nfrac = nbits << ENTROPY_SHIFT; | |
1da177e4 | 676 | |
adc782da MM |
677 | if (!nbits) |
678 | return; | |
679 | ||
902c098a | 680 | retry: |
6aa7de05 | 681 | entropy_count = orig = READ_ONCE(r->entropy_count); |
30e37ec5 PA |
682 | if (nfrac < 0) { |
683 | /* Debit */ | |
684 | entropy_count += nfrac; | |
685 | } else { | |
686 | /* | |
687 | * Credit: we have to account for the possibility of | |
688 | * overwriting already present entropy. Even in the | |
689 | * ideal case of pure Shannon entropy, new contributions | |
690 | * approach the full value asymptotically: | |
691 | * | |
692 | * entropy <- entropy + (pool_size - entropy) * | |
693 | * (1 - exp(-add_entropy/pool_size)) | |
694 | * | |
695 | * For add_entropy <= pool_size/2 then | |
696 | * (1 - exp(-add_entropy/pool_size)) >= | |
697 | * (add_entropy/pool_size)*0.7869... | |
698 | * so we can approximate the exponential with | |
699 | * 3/4*add_entropy/pool_size and still be on the | |
700 | * safe side by adding at most pool_size/2 at a time. | |
701 | * | |
702 | * The use of pool_size-2 in the while statement is to | |
703 | * prevent rounding artifacts from making the loop | |
704 | * arbitrarily long; this limits the loop to log2(pool_size)*2 | |
705 | * turns no matter how large nbits is. | |
706 | */ | |
707 | int pnfrac = nfrac; | |
708 | const int s = r->poolinfo->poolbitshift + ENTROPY_SHIFT + 2; | |
709 | /* The +2 corresponds to the /4 in the denominator */ | |
710 | ||
711 | do { | |
712 | unsigned int anfrac = min(pnfrac, pool_size/2); | |
713 | unsigned int add = | |
714 | ((pool_size - entropy_count)*anfrac*3) >> s; | |
715 | ||
716 | entropy_count += add; | |
717 | pnfrac -= anfrac; | |
718 | } while (unlikely(entropy_count < pool_size-2 && pnfrac)); | |
719 | } | |
00ce1db1 | 720 | |
870e05b1 | 721 | if (WARN_ON(entropy_count < 0)) { |
12cd53af | 722 | pr_warn("negative entropy/overflow: pool %s count %d\n", |
f80bbd8b | 723 | r->name, entropy_count); |
8b76f46a | 724 | entropy_count = 0; |
30e37ec5 PA |
725 | } else if (entropy_count > pool_size) |
726 | entropy_count = pool_size; | |
902c098a TT |
727 | if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) |
728 | goto retry; | |
1da177e4 | 729 | |
a283b5c4 | 730 | trace_credit_entropy_bits(r->name, nbits, |
eb9d1bf0 | 731 | entropy_count >> ENTROPY_SHIFT, _RET_IP_); |
00ce1db1 | 732 | |
6265e169 | 733 | if (r == &input_pool) { |
7d1b08c4 | 734 | int entropy_bits = entropy_count >> ENTROPY_SHIFT; |
6265e169 | 735 | |
118a4417 | 736 | if (crng_init < 2 && entropy_bits >= 128) |
e192be9d | 737 | crng_reseed(&primary_crng, r); |
9a6f70bb | 738 | } |
1da177e4 LT |
739 | } |
740 | ||
86a574de | 741 | static int credit_entropy_bits_safe(struct entropy_store *r, int nbits) |
a283b5c4 | 742 | { |
9f886f4d | 743 | const int nbits_max = r->poolinfo->poolwords * 32; |
a283b5c4 | 744 | |
86a574de TT |
745 | if (nbits < 0) |
746 | return -EINVAL; | |
747 | ||
a283b5c4 PA |
748 | /* Cap the value to avoid overflows */ |
749 | nbits = min(nbits, nbits_max); | |
a283b5c4 PA |
750 | |
751 | credit_entropy_bits(r, nbits); | |
86a574de | 752 | return 0; |
a283b5c4 PA |
753 | } |
754 | ||
e192be9d TT |
755 | /********************************************************************* |
756 | * | |
757 | * CRNG using CHACHA20 | |
758 | * | |
759 | *********************************************************************/ | |
760 | ||
761 | #define CRNG_RESEED_INTERVAL (300*HZ) | |
762 | ||
763 | static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); | |
764 | ||
1e7f583a TT |
765 | #ifdef CONFIG_NUMA |
766 | /* | |
767 | * Hack to deal with crazy userspace progams when they are all trying | |
768 | * to access /dev/urandom in parallel. The programs are almost | |
769 | * certainly doing something terribly wrong, but we'll work around | |
770 | * their brain damage. | |
771 | */ | |
772 | static struct crng_state **crng_node_pool __read_mostly; | |
773 | #endif | |
774 | ||
b169c13d | 775 | static void invalidate_batched_entropy(void); |
fe6f1a6a | 776 | static void numa_crng_init(void); |
b169c13d | 777 | |
9b254366 KC |
778 | static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU); |
779 | static int __init parse_trust_cpu(char *arg) | |
780 | { | |
781 | return kstrtobool(arg, &trust_cpu); | |
782 | } | |
783 | early_param("random.trust_cpu", parse_trust_cpu); | |
784 | ||
5cbe0f13 | 785 | static bool crng_init_try_arch(struct crng_state *crng) |
e192be9d TT |
786 | { |
787 | int i; | |
5cbe0f13 | 788 | bool arch_init = true; |
e192be9d TT |
789 | unsigned long rv; |
790 | ||
e192be9d TT |
791 | for (i = 4; i < 16; i++) { |
792 | if (!arch_get_random_seed_long(&rv) && | |
39a8883a | 793 | !arch_get_random_long(&rv)) { |
e192be9d | 794 | rv = random_get_entropy(); |
5cbe0f13 | 795 | arch_init = false; |
39a8883a | 796 | } |
e192be9d TT |
797 | crng->state[i] ^= rv; |
798 | } | |
5cbe0f13 MR |
799 | |
800 | return arch_init; | |
801 | } | |
802 | ||
253d3194 MR |
803 | static bool __init crng_init_try_arch_early(struct crng_state *crng) |
804 | { | |
805 | int i; | |
806 | bool arch_init = true; | |
807 | unsigned long rv; | |
808 | ||
809 | for (i = 4; i < 16; i++) { | |
810 | if (!arch_get_random_seed_long_early(&rv) && | |
811 | !arch_get_random_long_early(&rv)) { | |
812 | rv = random_get_entropy(); | |
813 | arch_init = false; | |
814 | } | |
815 | crng->state[i] ^= rv; | |
816 | } | |
817 | ||
818 | return arch_init; | |
819 | } | |
820 | ||
ab9a7e27 | 821 | static void __maybe_unused crng_initialize_secondary(struct crng_state *crng) |
5cbe0f13 | 822 | { |
a181e0fd | 823 | chacha_init_consts(crng->state); |
5cbe0f13 MR |
824 | _get_random_bytes(&crng->state[4], sizeof(__u32) * 12); |
825 | crng_init_try_arch(crng); | |
826 | crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1; | |
827 | } | |
828 | ||
829 | static void __init crng_initialize_primary(struct crng_state *crng) | |
830 | { | |
a181e0fd | 831 | chacha_init_consts(crng->state); |
5cbe0f13 | 832 | _extract_entropy(&input_pool, &crng->state[4], sizeof(__u32) * 12, 0); |
253d3194 | 833 | if (crng_init_try_arch_early(crng) && trust_cpu) { |
fe6f1a6a JD |
834 | invalidate_batched_entropy(); |
835 | numa_crng_init(); | |
39a8883a | 836 | crng_init = 2; |
12cd53af | 837 | pr_notice("crng done (trusting CPU's manufacturer)\n"); |
39a8883a | 838 | } |
e192be9d TT |
839 | crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1; |
840 | } | |
841 | ||
8ef35c86 | 842 | #ifdef CONFIG_NUMA |
6c1e851c | 843 | static void do_numa_crng_init(struct work_struct *work) |
8ef35c86 TT |
844 | { |
845 | int i; | |
846 | struct crng_state *crng; | |
847 | struct crng_state **pool; | |
848 | ||
849 | pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL); | |
850 | for_each_online_node(i) { | |
851 | crng = kmalloc_node(sizeof(struct crng_state), | |
852 | GFP_KERNEL | __GFP_NOFAIL, i); | |
853 | spin_lock_init(&crng->lock); | |
5cbe0f13 | 854 | crng_initialize_secondary(crng); |
8ef35c86 TT |
855 | pool[i] = crng; |
856 | } | |
5d73d1e3 EB |
857 | /* pairs with READ_ONCE() in select_crng() */ |
858 | if (cmpxchg_release(&crng_node_pool, NULL, pool) != NULL) { | |
8ef35c86 TT |
859 | for_each_node(i) |
860 | kfree(pool[i]); | |
861 | kfree(pool); | |
862 | } | |
863 | } | |
6c1e851c TT |
864 | |
865 | static DECLARE_WORK(numa_crng_init_work, do_numa_crng_init); | |
866 | ||
867 | static void numa_crng_init(void) | |
868 | { | |
869 | schedule_work(&numa_crng_init_work); | |
870 | } | |
5d73d1e3 EB |
871 | |
872 | static struct crng_state *select_crng(void) | |
873 | { | |
874 | struct crng_state **pool; | |
875 | int nid = numa_node_id(); | |
876 | ||
877 | /* pairs with cmpxchg_release() in do_numa_crng_init() */ | |
878 | pool = READ_ONCE(crng_node_pool); | |
879 | if (pool && pool[nid]) | |
880 | return pool[nid]; | |
881 | ||
882 | return &primary_crng; | |
883 | } | |
8ef35c86 TT |
884 | #else |
885 | static void numa_crng_init(void) {} | |
5d73d1e3 EB |
886 | |
887 | static struct crng_state *select_crng(void) | |
888 | { | |
889 | return &primary_crng; | |
890 | } | |
8ef35c86 TT |
891 | #endif |
892 | ||
dc12baac TT |
893 | /* |
894 | * crng_fast_load() can be called by code in the interrupt service | |
895 | * path. So we can't afford to dilly-dally. | |
896 | */ | |
e192be9d TT |
897 | static int crng_fast_load(const char *cp, size_t len) |
898 | { | |
899 | unsigned long flags; | |
900 | char *p; | |
901 | ||
902 | if (!spin_trylock_irqsave(&primary_crng.lock, flags)) | |
903 | return 0; | |
43838a23 | 904 | if (crng_init != 0) { |
e192be9d TT |
905 | spin_unlock_irqrestore(&primary_crng.lock, flags); |
906 | return 0; | |
907 | } | |
908 | p = (unsigned char *) &primary_crng.state[4]; | |
909 | while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) { | |
1ca1b917 | 910 | p[crng_init_cnt % CHACHA_KEY_SIZE] ^= *cp; |
e192be9d TT |
911 | cp++; crng_init_cnt++; len--; |
912 | } | |
4a072c71 | 913 | spin_unlock_irqrestore(&primary_crng.lock, flags); |
e192be9d | 914 | if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) { |
b169c13d | 915 | invalidate_batched_entropy(); |
e192be9d | 916 | crng_init = 1; |
12cd53af | 917 | pr_notice("fast init done\n"); |
e192be9d | 918 | } |
e192be9d TT |
919 | return 1; |
920 | } | |
921 | ||
dc12baac TT |
922 | /* |
923 | * crng_slow_load() is called by add_device_randomness, which has two | |
924 | * attributes. (1) We can't trust the buffer passed to it is | |
925 | * guaranteed to be unpredictable (so it might not have any entropy at | |
926 | * all), and (2) it doesn't have the performance constraints of | |
927 | * crng_fast_load(). | |
928 | * | |
929 | * So we do something more comprehensive which is guaranteed to touch | |
930 | * all of the primary_crng's state, and which uses a LFSR with a | |
931 | * period of 255 as part of the mixing algorithm. Finally, we do | |
932 | * *not* advance crng_init_cnt since buffer we may get may be something | |
933 | * like a fixed DMI table (for example), which might very well be | |
934 | * unique to the machine, but is otherwise unvarying. | |
935 | */ | |
936 | static int crng_slow_load(const char *cp, size_t len) | |
937 | { | |
938 | unsigned long flags; | |
939 | static unsigned char lfsr = 1; | |
940 | unsigned char tmp; | |
1ca1b917 | 941 | unsigned i, max = CHACHA_KEY_SIZE; |
dc12baac TT |
942 | const char * src_buf = cp; |
943 | char * dest_buf = (char *) &primary_crng.state[4]; | |
944 | ||
945 | if (!spin_trylock_irqsave(&primary_crng.lock, flags)) | |
946 | return 0; | |
947 | if (crng_init != 0) { | |
948 | spin_unlock_irqrestore(&primary_crng.lock, flags); | |
949 | return 0; | |
950 | } | |
951 | if (len > max) | |
952 | max = len; | |
953 | ||
954 | for (i = 0; i < max ; i++) { | |
955 | tmp = lfsr; | |
956 | lfsr >>= 1; | |
957 | if (tmp & 1) | |
958 | lfsr ^= 0xE1; | |
1ca1b917 EB |
959 | tmp = dest_buf[i % CHACHA_KEY_SIZE]; |
960 | dest_buf[i % CHACHA_KEY_SIZE] ^= src_buf[i % len] ^ lfsr; | |
dc12baac TT |
961 | lfsr += (tmp << 3) | (tmp >> 5); |
962 | } | |
963 | spin_unlock_irqrestore(&primary_crng.lock, flags); | |
964 | return 1; | |
965 | } | |
966 | ||
e192be9d TT |
967 | static void crng_reseed(struct crng_state *crng, struct entropy_store *r) |
968 | { | |
969 | unsigned long flags; | |
970 | int i, num; | |
971 | union { | |
1ca1b917 | 972 | __u8 block[CHACHA_BLOCK_SIZE]; |
e192be9d TT |
973 | __u32 key[8]; |
974 | } buf; | |
975 | ||
976 | if (r) { | |
977 | num = extract_entropy(r, &buf, 32, 16, 0); | |
978 | if (num == 0) | |
979 | return; | |
c92e040d | 980 | } else { |
1e7f583a | 981 | _extract_crng(&primary_crng, buf.block); |
c92e040d | 982 | _crng_backtrack_protect(&primary_crng, buf.block, |
1ca1b917 | 983 | CHACHA_KEY_SIZE); |
c92e040d | 984 | } |
0bb29a84 | 985 | spin_lock_irqsave(&crng->lock, flags); |
e192be9d TT |
986 | for (i = 0; i < 8; i++) { |
987 | unsigned long rv; | |
988 | if (!arch_get_random_seed_long(&rv) && | |
989 | !arch_get_random_long(&rv)) | |
990 | rv = random_get_entropy(); | |
991 | crng->state[i+4] ^= buf.key[i] ^ rv; | |
992 | } | |
993 | memzero_explicit(&buf, sizeof(buf)); | |
009ba856 | 994 | WRITE_ONCE(crng->init_time, jiffies); |
0bb29a84 | 995 | spin_unlock_irqrestore(&crng->lock, flags); |
e192be9d | 996 | if (crng == &primary_crng && crng_init < 2) { |
b169c13d | 997 | invalidate_batched_entropy(); |
8ef35c86 | 998 | numa_crng_init(); |
e192be9d TT |
999 | crng_init = 2; |
1000 | process_random_ready_list(); | |
1001 | wake_up_interruptible(&crng_init_wait); | |
30c08efe | 1002 | kill_fasync(&fasync, SIGIO, POLL_IN); |
12cd53af | 1003 | pr_notice("crng init done\n"); |
4e00b339 | 1004 | if (unseeded_warning.missed) { |
12cd53af | 1005 | pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n", |
4e00b339 TT |
1006 | unseeded_warning.missed); |
1007 | unseeded_warning.missed = 0; | |
1008 | } | |
1009 | if (urandom_warning.missed) { | |
12cd53af | 1010 | pr_notice("%d urandom warning(s) missed due to ratelimiting\n", |
4e00b339 TT |
1011 | urandom_warning.missed); |
1012 | urandom_warning.missed = 0; | |
1013 | } | |
e192be9d | 1014 | } |
e192be9d TT |
1015 | } |
1016 | ||
1e7f583a | 1017 | static void _extract_crng(struct crng_state *crng, |
1ca1b917 | 1018 | __u8 out[CHACHA_BLOCK_SIZE]) |
e192be9d | 1019 | { |
009ba856 EB |
1020 | unsigned long v, flags, init_time; |
1021 | ||
1022 | if (crng_ready()) { | |
1023 | init_time = READ_ONCE(crng->init_time); | |
1024 | if (time_after(READ_ONCE(crng_global_init_time), init_time) || | |
1025 | time_after(jiffies, init_time + CRNG_RESEED_INTERVAL)) | |
1026 | crng_reseed(crng, crng == &primary_crng ? | |
1027 | &input_pool : NULL); | |
1028 | } | |
e192be9d TT |
1029 | spin_lock_irqsave(&crng->lock, flags); |
1030 | if (arch_get_random_long(&v)) | |
1031 | crng->state[14] ^= v; | |
1032 | chacha20_block(&crng->state[0], out); | |
1033 | if (crng->state[12] == 0) | |
1034 | crng->state[13]++; | |
1035 | spin_unlock_irqrestore(&crng->lock, flags); | |
1036 | } | |
1037 | ||
1ca1b917 | 1038 | static void extract_crng(__u8 out[CHACHA_BLOCK_SIZE]) |
1e7f583a | 1039 | { |
5d73d1e3 | 1040 | _extract_crng(select_crng(), out); |
1e7f583a TT |
1041 | } |
1042 | ||
c92e040d TT |
1043 | /* |
1044 | * Use the leftover bytes from the CRNG block output (if there is | |
1045 | * enough) to mutate the CRNG key to provide backtracking protection. | |
1046 | */ | |
1047 | static void _crng_backtrack_protect(struct crng_state *crng, | |
1ca1b917 | 1048 | __u8 tmp[CHACHA_BLOCK_SIZE], int used) |
c92e040d TT |
1049 | { |
1050 | unsigned long flags; | |
1051 | __u32 *s, *d; | |
1052 | int i; | |
1053 | ||
1054 | used = round_up(used, sizeof(__u32)); | |
1ca1b917 | 1055 | if (used + CHACHA_KEY_SIZE > CHACHA_BLOCK_SIZE) { |
c92e040d TT |
1056 | extract_crng(tmp); |
1057 | used = 0; | |
1058 | } | |
1059 | spin_lock_irqsave(&crng->lock, flags); | |
a5e9f557 | 1060 | s = (__u32 *) &tmp[used]; |
c92e040d TT |
1061 | d = &crng->state[4]; |
1062 | for (i=0; i < 8; i++) | |
1063 | *d++ ^= *s++; | |
1064 | spin_unlock_irqrestore(&crng->lock, flags); | |
1065 | } | |
1066 | ||
1ca1b917 | 1067 | static void crng_backtrack_protect(__u8 tmp[CHACHA_BLOCK_SIZE], int used) |
c92e040d | 1068 | { |
5d73d1e3 | 1069 | _crng_backtrack_protect(select_crng(), tmp, used); |
c92e040d TT |
1070 | } |
1071 | ||
e192be9d TT |
1072 | static ssize_t extract_crng_user(void __user *buf, size_t nbytes) |
1073 | { | |
1ca1b917 EB |
1074 | ssize_t ret = 0, i = CHACHA_BLOCK_SIZE; |
1075 | __u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4); | |
e192be9d TT |
1076 | int large_request = (nbytes > 256); |
1077 | ||
1078 | while (nbytes) { | |
1079 | if (large_request && need_resched()) { | |
1080 | if (signal_pending(current)) { | |
1081 | if (ret == 0) | |
1082 | ret = -ERESTARTSYS; | |
1083 | break; | |
1084 | } | |
1085 | schedule(); | |
1086 | } | |
1087 | ||
1088 | extract_crng(tmp); | |
1ca1b917 | 1089 | i = min_t(int, nbytes, CHACHA_BLOCK_SIZE); |
e192be9d TT |
1090 | if (copy_to_user(buf, tmp, i)) { |
1091 | ret = -EFAULT; | |
1092 | break; | |
1093 | } | |
1094 | ||
1095 | nbytes -= i; | |
1096 | buf += i; | |
1097 | ret += i; | |
1098 | } | |
c92e040d | 1099 | crng_backtrack_protect(tmp, i); |
e192be9d TT |
1100 | |
1101 | /* Wipe data just written to memory */ | |
1102 | memzero_explicit(tmp, sizeof(tmp)); | |
1103 | ||
1104 | return ret; | |
1105 | } | |
1106 | ||
1107 | ||
1da177e4 LT |
1108 | /********************************************************************* |
1109 | * | |
1110 | * Entropy input management | |
1111 | * | |
1112 | *********************************************************************/ | |
1113 | ||
1114 | /* There is one of these per entropy source */ | |
1115 | struct timer_rand_state { | |
1116 | cycles_t last_time; | |
90b75ee5 | 1117 | long last_delta, last_delta2; |
1da177e4 LT |
1118 | }; |
1119 | ||
644008df TT |
1120 | #define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, }; |
1121 | ||
a2080a67 | 1122 | /* |
e192be9d TT |
1123 | * Add device- or boot-specific data to the input pool to help |
1124 | * initialize it. | |
a2080a67 | 1125 | * |
e192be9d TT |
1126 | * None of this adds any entropy; it is meant to avoid the problem of |
1127 | * the entropy pool having similar initial state across largely | |
1128 | * identical devices. | |
a2080a67 LT |
1129 | */ |
1130 | void add_device_randomness(const void *buf, unsigned int size) | |
1131 | { | |
61875f30 | 1132 | unsigned long time = random_get_entropy() ^ jiffies; |
3ef4cb2d | 1133 | unsigned long flags; |
a2080a67 | 1134 | |
dc12baac TT |
1135 | if (!crng_ready() && size) |
1136 | crng_slow_load(buf, size); | |
ee7998c5 | 1137 | |
5910895f | 1138 | trace_add_device_randomness(size, _RET_IP_); |
3ef4cb2d | 1139 | spin_lock_irqsave(&input_pool.lock, flags); |
85608f8e TT |
1140 | _mix_pool_bytes(&input_pool, buf, size); |
1141 | _mix_pool_bytes(&input_pool, &time, sizeof(time)); | |
3ef4cb2d | 1142 | spin_unlock_irqrestore(&input_pool.lock, flags); |
a2080a67 LT |
1143 | } |
1144 | EXPORT_SYMBOL(add_device_randomness); | |
1145 | ||
644008df | 1146 | static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE; |
3060d6fe | 1147 | |
1da177e4 LT |
1148 | /* |
1149 | * This function adds entropy to the entropy "pool" by using timing | |
1150 | * delays. It uses the timer_rand_state structure to make an estimate | |
1151 | * of how many bits of entropy this call has added to the pool. | |
1152 | * | |
1153 | * The number "num" is also added to the pool - it should somehow describe | |
1154 | * the type of event which just happened. This is currently 0-255 for | |
1155 | * keyboard scan codes, and 256 upwards for interrupts. | |
1156 | * | |
1157 | */ | |
1158 | static void add_timer_randomness(struct timer_rand_state *state, unsigned num) | |
1159 | { | |
40db23e5 | 1160 | struct entropy_store *r; |
1da177e4 | 1161 | struct { |
1da177e4 | 1162 | long jiffies; |
cf833d0b | 1163 | unsigned cycles; |
1da177e4 LT |
1164 | unsigned num; |
1165 | } sample; | |
1166 | long delta, delta2, delta3; | |
1167 | ||
1da177e4 | 1168 | sample.jiffies = jiffies; |
61875f30 | 1169 | sample.cycles = random_get_entropy(); |
1da177e4 | 1170 | sample.num = num; |
e192be9d | 1171 | r = &input_pool; |
85608f8e | 1172 | mix_pool_bytes(r, &sample, sizeof(sample)); |
1da177e4 LT |
1173 | |
1174 | /* | |
1175 | * Calculate number of bits of randomness we probably added. | |
1176 | * We take into account the first, second and third-order deltas | |
1177 | * in order to make our estimate. | |
1178 | */ | |
e00d996a QC |
1179 | delta = sample.jiffies - READ_ONCE(state->last_time); |
1180 | WRITE_ONCE(state->last_time, sample.jiffies); | |
5e747dd9 | 1181 | |
e00d996a QC |
1182 | delta2 = delta - READ_ONCE(state->last_delta); |
1183 | WRITE_ONCE(state->last_delta, delta); | |
5e747dd9 | 1184 | |
e00d996a QC |
1185 | delta3 = delta2 - READ_ONCE(state->last_delta2); |
1186 | WRITE_ONCE(state->last_delta2, delta2); | |
5e747dd9 RV |
1187 | |
1188 | if (delta < 0) | |
1189 | delta = -delta; | |
1190 | if (delta2 < 0) | |
1191 | delta2 = -delta2; | |
1192 | if (delta3 < 0) | |
1193 | delta3 = -delta3; | |
1194 | if (delta > delta2) | |
1195 | delta = delta2; | |
1196 | if (delta > delta3) | |
1197 | delta = delta3; | |
1da177e4 | 1198 | |
5e747dd9 RV |
1199 | /* |
1200 | * delta is now minimum absolute delta. | |
1201 | * Round down by 1 bit on general principles, | |
727d499a | 1202 | * and limit entropy estimate to 12 bits. |
5e747dd9 RV |
1203 | */ |
1204 | credit_entropy_bits(r, min_t(int, fls(delta>>1), 11)); | |
1da177e4 LT |
1205 | } |
1206 | ||
d251575a | 1207 | void add_input_randomness(unsigned int type, unsigned int code, |
1da177e4 LT |
1208 | unsigned int value) |
1209 | { | |
1210 | static unsigned char last_value; | |
1211 | ||
1212 | /* ignore autorepeat and the like */ | |
1213 | if (value == last_value) | |
1214 | return; | |
1215 | ||
1da177e4 LT |
1216 | last_value = value; |
1217 | add_timer_randomness(&input_timer_state, | |
1218 | (type << 4) ^ code ^ (code >> 4) ^ value); | |
f80bbd8b | 1219 | trace_add_input_randomness(ENTROPY_BITS(&input_pool)); |
1da177e4 | 1220 | } |
80fc9f53 | 1221 | EXPORT_SYMBOL_GPL(add_input_randomness); |
1da177e4 | 1222 | |
775f4b29 TT |
1223 | static DEFINE_PER_CPU(struct fast_pool, irq_randomness); |
1224 | ||
43759d4f TT |
1225 | #ifdef ADD_INTERRUPT_BENCH |
1226 | static unsigned long avg_cycles, avg_deviation; | |
1227 | ||
1228 | #define AVG_SHIFT 8 /* Exponential average factor k=1/256 */ | |
1229 | #define FIXED_1_2 (1 << (AVG_SHIFT-1)) | |
1230 | ||
1231 | static void add_interrupt_bench(cycles_t start) | |
1232 | { | |
1233 | long delta = random_get_entropy() - start; | |
1234 | ||
1235 | /* Use a weighted moving average */ | |
1236 | delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT); | |
1237 | avg_cycles += delta; | |
1238 | /* And average deviation */ | |
1239 | delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT); | |
1240 | avg_deviation += delta; | |
1241 | } | |
1242 | #else | |
1243 | #define add_interrupt_bench(x) | |
1244 | #endif | |
1245 | ||
ee3e00e9 TT |
1246 | static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs) |
1247 | { | |
1248 | __u32 *ptr = (__u32 *) regs; | |
92e75428 | 1249 | unsigned int idx; |
ee3e00e9 TT |
1250 | |
1251 | if (regs == NULL) | |
1252 | return 0; | |
92e75428 TT |
1253 | idx = READ_ONCE(f->reg_idx); |
1254 | if (idx >= sizeof(struct pt_regs) / sizeof(__u32)) | |
1255 | idx = 0; | |
1256 | ptr += idx++; | |
1257 | WRITE_ONCE(f->reg_idx, idx); | |
9dfa7bba | 1258 | return *ptr; |
ee3e00e9 TT |
1259 | } |
1260 | ||
703f7066 | 1261 | void add_interrupt_randomness(int irq) |
1da177e4 | 1262 | { |
775f4b29 | 1263 | struct entropy_store *r; |
1b2a1a7e | 1264 | struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness); |
775f4b29 TT |
1265 | struct pt_regs *regs = get_irq_regs(); |
1266 | unsigned long now = jiffies; | |
655b2264 | 1267 | cycles_t cycles = random_get_entropy(); |
43759d4f | 1268 | __u32 c_high, j_high; |
655b2264 | 1269 | __u64 ip; |
3060d6fe | 1270 | |
ee3e00e9 TT |
1271 | if (cycles == 0) |
1272 | cycles = get_reg(fast_pool, regs); | |
655b2264 TT |
1273 | c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0; |
1274 | j_high = (sizeof(now) > 4) ? now >> 32 : 0; | |
43759d4f TT |
1275 | fast_pool->pool[0] ^= cycles ^ j_high ^ irq; |
1276 | fast_pool->pool[1] ^= now ^ c_high; | |
655b2264 | 1277 | ip = regs ? instruction_pointer(regs) : _RET_IP_; |
43759d4f | 1278 | fast_pool->pool[2] ^= ip; |
ee3e00e9 TT |
1279 | fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 : |
1280 | get_reg(fast_pool, regs); | |
3060d6fe | 1281 | |
43759d4f | 1282 | fast_mix(fast_pool); |
43759d4f | 1283 | add_interrupt_bench(cycles); |
3060d6fe | 1284 | |
43838a23 | 1285 | if (unlikely(crng_init == 0)) { |
e192be9d TT |
1286 | if ((fast_pool->count >= 64) && |
1287 | crng_fast_load((char *) fast_pool->pool, | |
1288 | sizeof(fast_pool->pool))) { | |
1289 | fast_pool->count = 0; | |
1290 | fast_pool->last = now; | |
1291 | } | |
1292 | return; | |
1293 | } | |
1294 | ||
ee3e00e9 TT |
1295 | if ((fast_pool->count < 64) && |
1296 | !time_after(now, fast_pool->last + HZ)) | |
1da177e4 LT |
1297 | return; |
1298 | ||
e192be9d | 1299 | r = &input_pool; |
840f9507 | 1300 | if (!spin_trylock(&r->lock)) |
91fcb532 | 1301 | return; |
83664a69 | 1302 | |
91fcb532 | 1303 | fast_pool->last = now; |
85608f8e | 1304 | __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool)); |
91fcb532 | 1305 | spin_unlock(&r->lock); |
83664a69 | 1306 | |
ee3e00e9 | 1307 | fast_pool->count = 0; |
83664a69 | 1308 | |
ee3e00e9 | 1309 | /* award one bit for the contents of the fast pool */ |
390596c9 | 1310 | credit_entropy_bits(r, 1); |
1da177e4 | 1311 | } |
4b44f2d1 | 1312 | EXPORT_SYMBOL_GPL(add_interrupt_randomness); |
1da177e4 | 1313 | |
9361401e | 1314 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1315 | void add_disk_randomness(struct gendisk *disk) |
1316 | { | |
1317 | if (!disk || !disk->random) | |
1318 | return; | |
1319 | /* first major is 1, so we get >= 0x200 here */ | |
f331c029 | 1320 | add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); |
f80bbd8b | 1321 | trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS(&input_pool)); |
1da177e4 | 1322 | } |
bdcfa3e5 | 1323 | EXPORT_SYMBOL_GPL(add_disk_randomness); |
9361401e | 1324 | #endif |
1da177e4 | 1325 | |
1da177e4 LT |
1326 | /********************************************************************* |
1327 | * | |
1328 | * Entropy extraction routines | |
1329 | * | |
1330 | *********************************************************************/ | |
1331 | ||
1da177e4 | 1332 | /* |
19fa5be1 GP |
1333 | * This function decides how many bytes to actually take from the |
1334 | * given pool, and also debits the entropy count accordingly. | |
1da177e4 | 1335 | */ |
1da177e4 LT |
1336 | static size_t account(struct entropy_store *r, size_t nbytes, int min, |
1337 | int reserved) | |
1338 | { | |
43d8a72c | 1339 | int entropy_count, orig, have_bytes; |
79a84687 | 1340 | size_t ibytes, nfrac; |
1da177e4 | 1341 | |
a283b5c4 | 1342 | BUG_ON(r->entropy_count > r->poolinfo->poolfracbits); |
1da177e4 LT |
1343 | |
1344 | /* Can we pull enough? */ | |
10b3a32d | 1345 | retry: |
6aa7de05 | 1346 | entropy_count = orig = READ_ONCE(r->entropy_count); |
a283b5c4 | 1347 | ibytes = nbytes; |
43d8a72c SM |
1348 | /* never pull more than available */ |
1349 | have_bytes = entropy_count >> (ENTROPY_SHIFT + 3); | |
e33ba5fa | 1350 | |
43d8a72c SM |
1351 | if ((have_bytes -= reserved) < 0) |
1352 | have_bytes = 0; | |
1353 | ibytes = min_t(size_t, ibytes, have_bytes); | |
0fb7a01a | 1354 | if (ibytes < min) |
a283b5c4 | 1355 | ibytes = 0; |
79a84687 | 1356 | |
870e05b1 | 1357 | if (WARN_ON(entropy_count < 0)) { |
12cd53af | 1358 | pr_warn("negative entropy count: pool %s count %d\n", |
79a84687 | 1359 | r->name, entropy_count); |
79a84687 HFS |
1360 | entropy_count = 0; |
1361 | } | |
1362 | nfrac = ibytes << (ENTROPY_SHIFT + 3); | |
1363 | if ((size_t) entropy_count > nfrac) | |
1364 | entropy_count -= nfrac; | |
1365 | else | |
e33ba5fa | 1366 | entropy_count = 0; |
f9c6d498 | 1367 | |
0fb7a01a GP |
1368 | if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) |
1369 | goto retry; | |
1da177e4 | 1370 | |
f80bbd8b | 1371 | trace_debit_entropy(r->name, 8 * ibytes); |
12faac30 | 1372 | if (ibytes && ENTROPY_BITS(r) < random_write_wakeup_bits) { |
a11e1d43 | 1373 | wake_up_interruptible(&random_write_wait); |
b9809552 TT |
1374 | kill_fasync(&fasync, SIGIO, POLL_OUT); |
1375 | } | |
1376 | ||
a283b5c4 | 1377 | return ibytes; |
1da177e4 LT |
1378 | } |
1379 | ||
19fa5be1 | 1380 | /* |
118a4417 | 1381 | * This function does the actual extraction for extract_entropy. |
19fa5be1 GP |
1382 | * |
1383 | * Note: we assume that .poolwords is a multiple of 16 words. | |
1384 | */ | |
1da177e4 LT |
1385 | static void extract_buf(struct entropy_store *r, __u8 *out) |
1386 | { | |
602b6aee | 1387 | int i; |
d2e7c96a PA |
1388 | union { |
1389 | __u32 w[5]; | |
85a1f777 | 1390 | unsigned long l[LONGS(20)]; |
d2e7c96a | 1391 | } hash; |
6b0b0fa2 | 1392 | __u32 workspace[SHA1_WORKSPACE_WORDS]; |
902c098a | 1393 | unsigned long flags; |
1da177e4 | 1394 | |
85a1f777 | 1395 | /* |
dfd38750 | 1396 | * If we have an architectural hardware random number |
46884442 | 1397 | * generator, use it for SHA's initial vector |
85a1f777 | 1398 | */ |
6b0b0fa2 | 1399 | sha1_init(hash.w); |
85a1f777 TT |
1400 | for (i = 0; i < LONGS(20); i++) { |
1401 | unsigned long v; | |
1402 | if (!arch_get_random_long(&v)) | |
1403 | break; | |
46884442 | 1404 | hash.l[i] = v; |
85a1f777 TT |
1405 | } |
1406 | ||
46884442 TT |
1407 | /* Generate a hash across the pool, 16 words (512 bits) at a time */ |
1408 | spin_lock_irqsave(&r->lock, flags); | |
1409 | for (i = 0; i < r->poolinfo->poolwords; i += 16) | |
6b0b0fa2 | 1410 | sha1_transform(hash.w, (__u8 *)(r->pool + i), workspace); |
46884442 | 1411 | |
1da177e4 | 1412 | /* |
1c0ad3d4 MM |
1413 | * We mix the hash back into the pool to prevent backtracking |
1414 | * attacks (where the attacker knows the state of the pool | |
1415 | * plus the current outputs, and attempts to find previous | |
1416 | * ouputs), unless the hash function can be inverted. By | |
1417 | * mixing at least a SHA1 worth of hash data back, we make | |
1418 | * brute-forcing the feedback as hard as brute-forcing the | |
1419 | * hash. | |
1da177e4 | 1420 | */ |
85608f8e | 1421 | __mix_pool_bytes(r, hash.w, sizeof(hash.w)); |
902c098a | 1422 | spin_unlock_irqrestore(&r->lock, flags); |
1da177e4 | 1423 | |
d4c5efdb | 1424 | memzero_explicit(workspace, sizeof(workspace)); |
1da177e4 LT |
1425 | |
1426 | /* | |
1c0ad3d4 MM |
1427 | * In case the hash function has some recognizable output |
1428 | * pattern, we fold it in half. Thus, we always feed back | |
1429 | * twice as much data as we output. | |
1da177e4 | 1430 | */ |
d2e7c96a PA |
1431 | hash.w[0] ^= hash.w[3]; |
1432 | hash.w[1] ^= hash.w[4]; | |
1433 | hash.w[2] ^= rol32(hash.w[2], 16); | |
1434 | ||
d2e7c96a | 1435 | memcpy(out, &hash, EXTRACT_SIZE); |
d4c5efdb | 1436 | memzero_explicit(&hash, sizeof(hash)); |
1da177e4 LT |
1437 | } |
1438 | ||
e192be9d TT |
1439 | static ssize_t _extract_entropy(struct entropy_store *r, void *buf, |
1440 | size_t nbytes, int fips) | |
1441 | { | |
1442 | ssize_t ret = 0, i; | |
1443 | __u8 tmp[EXTRACT_SIZE]; | |
1444 | unsigned long flags; | |
1445 | ||
1446 | while (nbytes) { | |
1447 | extract_buf(r, tmp); | |
1448 | ||
1449 | if (fips) { | |
1450 | spin_lock_irqsave(&r->lock, flags); | |
1451 | if (!memcmp(tmp, r->last_data, EXTRACT_SIZE)) | |
1452 | panic("Hardware RNG duplicated output!\n"); | |
1453 | memcpy(r->last_data, tmp, EXTRACT_SIZE); | |
1454 | spin_unlock_irqrestore(&r->lock, flags); | |
1455 | } | |
1456 | i = min_t(int, nbytes, EXTRACT_SIZE); | |
1457 | memcpy(buf, tmp, i); | |
1458 | nbytes -= i; | |
1459 | buf += i; | |
1460 | ret += i; | |
1461 | } | |
1462 | ||
1463 | /* Wipe data just returned from memory */ | |
1464 | memzero_explicit(tmp, sizeof(tmp)); | |
1465 | ||
1466 | return ret; | |
1467 | } | |
1468 | ||
19fa5be1 GP |
1469 | /* |
1470 | * This function extracts randomness from the "entropy pool", and | |
1471 | * returns it in a buffer. | |
1472 | * | |
1473 | * The min parameter specifies the minimum amount we can pull before | |
1474 | * failing to avoid races that defeat catastrophic reseeding while the | |
1475 | * reserved parameter indicates how much entropy we must leave in the | |
1476 | * pool after each pull to avoid starving other readers. | |
1477 | */ | |
90b75ee5 | 1478 | static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
902c098a | 1479 | size_t nbytes, int min, int reserved) |
1da177e4 | 1480 | { |
1da177e4 | 1481 | __u8 tmp[EXTRACT_SIZE]; |
1e7e2e05 | 1482 | unsigned long flags; |
1da177e4 | 1483 | |
ec8f02da | 1484 | /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */ |
1e7e2e05 JW |
1485 | if (fips_enabled) { |
1486 | spin_lock_irqsave(&r->lock, flags); | |
1487 | if (!r->last_data_init) { | |
c59974ae | 1488 | r->last_data_init = 1; |
1e7e2e05 JW |
1489 | spin_unlock_irqrestore(&r->lock, flags); |
1490 | trace_extract_entropy(r->name, EXTRACT_SIZE, | |
a283b5c4 | 1491 | ENTROPY_BITS(r), _RET_IP_); |
1e7e2e05 JW |
1492 | extract_buf(r, tmp); |
1493 | spin_lock_irqsave(&r->lock, flags); | |
1494 | memcpy(r->last_data, tmp, EXTRACT_SIZE); | |
1495 | } | |
1496 | spin_unlock_irqrestore(&r->lock, flags); | |
1497 | } | |
ec8f02da | 1498 | |
a283b5c4 | 1499 | trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_); |
1da177e4 LT |
1500 | nbytes = account(r, nbytes, min, reserved); |
1501 | ||
e192be9d | 1502 | return _extract_entropy(r, buf, nbytes, fips_enabled); |
1da177e4 LT |
1503 | } |
1504 | ||
eecabf56 TT |
1505 | #define warn_unseeded_randomness(previous) \ |
1506 | _warn_unseeded_randomness(__func__, (void *) _RET_IP_, (previous)) | |
1507 | ||
1508 | static void _warn_unseeded_randomness(const char *func_name, void *caller, | |
1509 | void **previous) | |
1510 | { | |
1511 | #ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM | |
1512 | const bool print_once = false; | |
1513 | #else | |
1514 | static bool print_once __read_mostly; | |
1515 | #endif | |
1516 | ||
1517 | if (print_once || | |
1518 | crng_ready() || | |
1519 | (previous && (caller == READ_ONCE(*previous)))) | |
1520 | return; | |
1521 | WRITE_ONCE(*previous, caller); | |
1522 | #ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM | |
1523 | print_once = true; | |
1524 | #endif | |
4e00b339 | 1525 | if (__ratelimit(&unseeded_warning)) |
1b710b1b SS |
1526 | printk_deferred(KERN_NOTICE "random: %s called from %pS " |
1527 | "with crng_init=%d\n", func_name, caller, | |
1528 | crng_init); | |
eecabf56 TT |
1529 | } |
1530 | ||
1da177e4 LT |
1531 | /* |
1532 | * This function is the exported kernel interface. It returns some | |
c2557a30 | 1533 | * number of good random numbers, suitable for key generation, seeding |
18e9cea7 GP |
1534 | * TCP sequence numbers, etc. It does not rely on the hardware random |
1535 | * number generator. For random bytes direct from the hardware RNG | |
e297a783 JD |
1536 | * (when available), use get_random_bytes_arch(). In order to ensure |
1537 | * that the randomness provided by this function is okay, the function | |
1538 | * wait_for_random_bytes() should be called and return 0 at least once | |
1539 | * at any point prior. | |
1da177e4 | 1540 | */ |
eecabf56 | 1541 | static void _get_random_bytes(void *buf, int nbytes) |
c2557a30 | 1542 | { |
1ca1b917 | 1543 | __u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4); |
e192be9d | 1544 | |
5910895f | 1545 | trace_get_random_bytes(nbytes, _RET_IP_); |
e192be9d | 1546 | |
1ca1b917 | 1547 | while (nbytes >= CHACHA_BLOCK_SIZE) { |
e192be9d | 1548 | extract_crng(buf); |
1ca1b917 EB |
1549 | buf += CHACHA_BLOCK_SIZE; |
1550 | nbytes -= CHACHA_BLOCK_SIZE; | |
e192be9d TT |
1551 | } |
1552 | ||
1553 | if (nbytes > 0) { | |
1554 | extract_crng(tmp); | |
1555 | memcpy(buf, tmp, nbytes); | |
c92e040d TT |
1556 | crng_backtrack_protect(tmp, nbytes); |
1557 | } else | |
1ca1b917 | 1558 | crng_backtrack_protect(tmp, CHACHA_BLOCK_SIZE); |
c92e040d | 1559 | memzero_explicit(tmp, sizeof(tmp)); |
c2557a30 | 1560 | } |
eecabf56 TT |
1561 | |
1562 | void get_random_bytes(void *buf, int nbytes) | |
1563 | { | |
1564 | static void *previous; | |
1565 | ||
1566 | warn_unseeded_randomness(&previous); | |
1567 | _get_random_bytes(buf, nbytes); | |
1568 | } | |
c2557a30 TT |
1569 | EXPORT_SYMBOL(get_random_bytes); |
1570 | ||
50ee7529 LT |
1571 | |
1572 | /* | |
1573 | * Each time the timer fires, we expect that we got an unpredictable | |
1574 | * jump in the cycle counter. Even if the timer is running on another | |
1575 | * CPU, the timer activity will be touching the stack of the CPU that is | |
1576 | * generating entropy.. | |
1577 | * | |
1578 | * Note that we don't re-arm the timer in the timer itself - we are | |
1579 | * happy to be scheduled away, since that just makes the load more | |
1580 | * complex, but we do not want the timer to keep ticking unless the | |
1581 | * entropy loop is running. | |
1582 | * | |
1583 | * So the re-arming always happens in the entropy loop itself. | |
1584 | */ | |
1585 | static void entropy_timer(struct timer_list *t) | |
1586 | { | |
1587 | credit_entropy_bits(&input_pool, 1); | |
1588 | } | |
1589 | ||
1590 | /* | |
1591 | * If we have an actual cycle counter, see if we can | |
1592 | * generate enough entropy with timing noise | |
1593 | */ | |
1594 | static void try_to_generate_entropy(void) | |
1595 | { | |
1596 | struct { | |
1597 | unsigned long now; | |
1598 | struct timer_list timer; | |
1599 | } stack; | |
1600 | ||
1601 | stack.now = random_get_entropy(); | |
1602 | ||
1603 | /* Slow counter - or none. Don't even bother */ | |
1604 | if (stack.now == random_get_entropy()) | |
1605 | return; | |
1606 | ||
1607 | timer_setup_on_stack(&stack.timer, entropy_timer, 0); | |
1608 | while (!crng_ready()) { | |
1609 | if (!timer_pending(&stack.timer)) | |
1610 | mod_timer(&stack.timer, jiffies+1); | |
1611 | mix_pool_bytes(&input_pool, &stack.now, sizeof(stack.now)); | |
1612 | schedule(); | |
1613 | stack.now = random_get_entropy(); | |
1614 | } | |
1615 | ||
1616 | del_timer_sync(&stack.timer); | |
1617 | destroy_timer_on_stack(&stack.timer); | |
1618 | mix_pool_bytes(&input_pool, &stack.now, sizeof(stack.now)); | |
1619 | } | |
1620 | ||
e297a783 JD |
1621 | /* |
1622 | * Wait for the urandom pool to be seeded and thus guaranteed to supply | |
1623 | * cryptographically secure random numbers. This applies to: the /dev/urandom | |
1624 | * device, the get_random_bytes function, and the get_random_{u32,u64,int,long} | |
1625 | * family of functions. Using any of these functions without first calling | |
1626 | * this function forfeits the guarantee of security. | |
1627 | * | |
1628 | * Returns: 0 if the urandom pool has been seeded. | |
1629 | * -ERESTARTSYS if the function was interrupted by a signal. | |
1630 | */ | |
1631 | int wait_for_random_bytes(void) | |
1632 | { | |
1633 | if (likely(crng_ready())) | |
1634 | return 0; | |
50ee7529 LT |
1635 | |
1636 | do { | |
1637 | int ret; | |
1638 | ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ); | |
1639 | if (ret) | |
1640 | return ret > 0 ? 0 : ret; | |
1641 | ||
1642 | try_to_generate_entropy(); | |
1643 | } while (!crng_ready()); | |
1644 | ||
1645 | return 0; | |
e297a783 JD |
1646 | } |
1647 | EXPORT_SYMBOL(wait_for_random_bytes); | |
1648 | ||
9a47249d JD |
1649 | /* |
1650 | * Returns whether or not the urandom pool has been seeded and thus guaranteed | |
1651 | * to supply cryptographically secure random numbers. This applies to: the | |
1652 | * /dev/urandom device, the get_random_bytes function, and the get_random_{u32, | |
1653 | * ,u64,int,long} family of functions. | |
1654 | * | |
1655 | * Returns: true if the urandom pool has been seeded. | |
1656 | * false if the urandom pool has not been seeded. | |
1657 | */ | |
1658 | bool rng_is_initialized(void) | |
1659 | { | |
1660 | return crng_ready(); | |
1661 | } | |
1662 | EXPORT_SYMBOL(rng_is_initialized); | |
1663 | ||
205a525c HX |
1664 | /* |
1665 | * Add a callback function that will be invoked when the nonblocking | |
1666 | * pool is initialised. | |
1667 | * | |
1668 | * returns: 0 if callback is successfully added | |
1669 | * -EALREADY if pool is already initialised (callback not called) | |
1670 | * -ENOENT if module for callback is not alive | |
1671 | */ | |
1672 | int add_random_ready_callback(struct random_ready_callback *rdy) | |
1673 | { | |
1674 | struct module *owner; | |
1675 | unsigned long flags; | |
1676 | int err = -EALREADY; | |
1677 | ||
e192be9d | 1678 | if (crng_ready()) |
205a525c HX |
1679 | return err; |
1680 | ||
1681 | owner = rdy->owner; | |
1682 | if (!try_module_get(owner)) | |
1683 | return -ENOENT; | |
1684 | ||
1685 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
e192be9d | 1686 | if (crng_ready()) |
205a525c HX |
1687 | goto out; |
1688 | ||
1689 | owner = NULL; | |
1690 | ||
1691 | list_add(&rdy->list, &random_ready_list); | |
1692 | err = 0; | |
1693 | ||
1694 | out: | |
1695 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
1696 | ||
1697 | module_put(owner); | |
1698 | ||
1699 | return err; | |
1700 | } | |
1701 | EXPORT_SYMBOL(add_random_ready_callback); | |
1702 | ||
1703 | /* | |
1704 | * Delete a previously registered readiness callback function. | |
1705 | */ | |
1706 | void del_random_ready_callback(struct random_ready_callback *rdy) | |
1707 | { | |
1708 | unsigned long flags; | |
1709 | struct module *owner = NULL; | |
1710 | ||
1711 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
1712 | if (!list_empty(&rdy->list)) { | |
1713 | list_del_init(&rdy->list); | |
1714 | owner = rdy->owner; | |
1715 | } | |
1716 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
1717 | ||
1718 | module_put(owner); | |
1719 | } | |
1720 | EXPORT_SYMBOL(del_random_ready_callback); | |
1721 | ||
c2557a30 TT |
1722 | /* |
1723 | * This function will use the architecture-specific hardware random | |
1724 | * number generator if it is available. The arch-specific hw RNG will | |
1725 | * almost certainly be faster than what we can do in software, but it | |
1726 | * is impossible to verify that it is implemented securely (as | |
1727 | * opposed, to, say, the AES encryption of a sequence number using a | |
1728 | * key known by the NSA). So it's useful if we need the speed, but | |
1729 | * only if we're willing to trust the hardware manufacturer not to | |
1730 | * have put in a back door. | |
753d433b TH |
1731 | * |
1732 | * Return number of bytes filled in. | |
c2557a30 | 1733 | */ |
753d433b | 1734 | int __must_check get_random_bytes_arch(void *buf, int nbytes) |
1da177e4 | 1735 | { |
753d433b | 1736 | int left = nbytes; |
63d77173 PA |
1737 | char *p = buf; |
1738 | ||
753d433b TH |
1739 | trace_get_random_bytes_arch(left, _RET_IP_); |
1740 | while (left) { | |
63d77173 | 1741 | unsigned long v; |
753d433b | 1742 | int chunk = min_t(int, left, sizeof(unsigned long)); |
c2557a30 | 1743 | |
63d77173 PA |
1744 | if (!arch_get_random_long(&v)) |
1745 | break; | |
8ddd6efa | 1746 | |
bd29e568 | 1747 | memcpy(p, &v, chunk); |
63d77173 | 1748 | p += chunk; |
753d433b | 1749 | left -= chunk; |
63d77173 PA |
1750 | } |
1751 | ||
753d433b | 1752 | return nbytes - left; |
1da177e4 | 1753 | } |
c2557a30 TT |
1754 | EXPORT_SYMBOL(get_random_bytes_arch); |
1755 | ||
1da177e4 LT |
1756 | /* |
1757 | * init_std_data - initialize pool with system data | |
1758 | * | |
1759 | * @r: pool to initialize | |
1760 | * | |
1761 | * This function clears the pool's entropy count and mixes some system | |
1762 | * data into the pool to prepare it for use. The pool is not cleared | |
1763 | * as that can only decrease the entropy in the pool. | |
1764 | */ | |
d5553523 | 1765 | static void __init init_std_data(struct entropy_store *r) |
1da177e4 | 1766 | { |
3e88bdff | 1767 | int i; |
902c098a TT |
1768 | ktime_t now = ktime_get_real(); |
1769 | unsigned long rv; | |
1da177e4 | 1770 | |
85608f8e | 1771 | mix_pool_bytes(r, &now, sizeof(now)); |
9ed17b70 | 1772 | for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) { |
83664a69 PA |
1773 | if (!arch_get_random_seed_long(&rv) && |
1774 | !arch_get_random_long(&rv)) | |
ae9ecd92 | 1775 | rv = random_get_entropy(); |
85608f8e | 1776 | mix_pool_bytes(r, &rv, sizeof(rv)); |
3e88bdff | 1777 | } |
85608f8e | 1778 | mix_pool_bytes(r, utsname(), sizeof(*(utsname()))); |
1da177e4 LT |
1779 | } |
1780 | ||
cbc96b75 TL |
1781 | /* |
1782 | * Note that setup_arch() may call add_device_randomness() | |
1783 | * long before we get here. This allows seeding of the pools | |
1784 | * with some platform dependent data very early in the boot | |
1785 | * process. But it limits our options here. We must use | |
1786 | * statically allocated structures that already have all | |
1787 | * initializations complete at compile time. We should also | |
1788 | * take care not to overwrite the precious per platform data | |
1789 | * we were given. | |
1790 | */ | |
d5553523 | 1791 | int __init rand_initialize(void) |
1da177e4 LT |
1792 | { |
1793 | init_std_data(&input_pool); | |
5cbe0f13 | 1794 | crng_initialize_primary(&primary_crng); |
d848e5f8 | 1795 | crng_global_init_time = jiffies; |
4e00b339 TT |
1796 | if (ratelimit_disable) { |
1797 | urandom_warning.interval = 0; | |
1798 | unseeded_warning.interval = 0; | |
1799 | } | |
1da177e4 LT |
1800 | return 0; |
1801 | } | |
1da177e4 | 1802 | |
9361401e | 1803 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1804 | void rand_initialize_disk(struct gendisk *disk) |
1805 | { | |
1806 | struct timer_rand_state *state; | |
1807 | ||
1808 | /* | |
f8595815 | 1809 | * If kzalloc returns null, we just won't use that entropy |
1da177e4 LT |
1810 | * source. |
1811 | */ | |
f8595815 | 1812 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
644008df TT |
1813 | if (state) { |
1814 | state->last_time = INITIAL_JIFFIES; | |
1da177e4 | 1815 | disk->random = state; |
644008df | 1816 | } |
1da177e4 | 1817 | } |
9361401e | 1818 | #endif |
1da177e4 | 1819 | |
c6f1deb1 AL |
1820 | static ssize_t |
1821 | urandom_read_nowarn(struct file *file, char __user *buf, size_t nbytes, | |
1822 | loff_t *ppos) | |
1823 | { | |
1824 | int ret; | |
1825 | ||
1826 | nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3)); | |
1827 | ret = extract_crng_user(buf, nbytes); | |
1828 | trace_urandom_read(8 * nbytes, 0, ENTROPY_BITS(&input_pool)); | |
1829 | return ret; | |
1830 | } | |
1831 | ||
1da177e4 | 1832 | static ssize_t |
90b75ee5 | 1833 | urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
1da177e4 | 1834 | { |
e192be9d | 1835 | unsigned long flags; |
9b4d0087 | 1836 | static int maxwarn = 10; |
301f0595 | 1837 | |
e192be9d | 1838 | if (!crng_ready() && maxwarn > 0) { |
9b4d0087 | 1839 | maxwarn--; |
4e00b339 | 1840 | if (__ratelimit(&urandom_warning)) |
12cd53af YL |
1841 | pr_notice("%s: uninitialized urandom read (%zd bytes read)\n", |
1842 | current->comm, nbytes); | |
e192be9d TT |
1843 | spin_lock_irqsave(&primary_crng.lock, flags); |
1844 | crng_init_cnt = 0; | |
1845 | spin_unlock_irqrestore(&primary_crng.lock, flags); | |
9b4d0087 | 1846 | } |
c6f1deb1 AL |
1847 | |
1848 | return urandom_read_nowarn(file, buf, nbytes, ppos); | |
1da177e4 LT |
1849 | } |
1850 | ||
30c08efe AL |
1851 | static ssize_t |
1852 | random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) | |
1853 | { | |
1854 | int ret; | |
1855 | ||
1856 | ret = wait_for_random_bytes(); | |
1857 | if (ret != 0) | |
1858 | return ret; | |
1859 | return urandom_read_nowarn(file, buf, nbytes, ppos); | |
1860 | } | |
1861 | ||
afc9a42b | 1862 | static __poll_t |
a11e1d43 | 1863 | random_poll(struct file *file, poll_table * wait) |
1da177e4 | 1864 | { |
a11e1d43 | 1865 | __poll_t mask; |
1da177e4 | 1866 | |
30c08efe | 1867 | poll_wait(file, &crng_init_wait, wait); |
a11e1d43 LT |
1868 | poll_wait(file, &random_write_wait, wait); |
1869 | mask = 0; | |
30c08efe | 1870 | if (crng_ready()) |
a9a08845 | 1871 | mask |= EPOLLIN | EPOLLRDNORM; |
2132a96f | 1872 | if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits) |
a9a08845 | 1873 | mask |= EPOLLOUT | EPOLLWRNORM; |
1da177e4 LT |
1874 | return mask; |
1875 | } | |
1876 | ||
7f397dcd MM |
1877 | static int |
1878 | write_pool(struct entropy_store *r, const char __user *buffer, size_t count) | |
1da177e4 | 1879 | { |
1da177e4 | 1880 | size_t bytes; |
81e69df3 | 1881 | __u32 t, buf[16]; |
1da177e4 | 1882 | const char __user *p = buffer; |
1da177e4 | 1883 | |
7f397dcd | 1884 | while (count > 0) { |
81e69df3 TT |
1885 | int b, i = 0; |
1886 | ||
7f397dcd MM |
1887 | bytes = min(count, sizeof(buf)); |
1888 | if (copy_from_user(&buf, p, bytes)) | |
1889 | return -EFAULT; | |
1da177e4 | 1890 | |
81e69df3 TT |
1891 | for (b = bytes ; b > 0 ; b -= sizeof(__u32), i++) { |
1892 | if (!arch_get_random_int(&t)) | |
1893 | break; | |
1894 | buf[i] ^= t; | |
1895 | } | |
1896 | ||
7f397dcd | 1897 | count -= bytes; |
1da177e4 LT |
1898 | p += bytes; |
1899 | ||
85608f8e | 1900 | mix_pool_bytes(r, buf, bytes); |
91f3f1e3 | 1901 | cond_resched(); |
1da177e4 | 1902 | } |
7f397dcd MM |
1903 | |
1904 | return 0; | |
1905 | } | |
1906 | ||
90b75ee5 MM |
1907 | static ssize_t random_write(struct file *file, const char __user *buffer, |
1908 | size_t count, loff_t *ppos) | |
7f397dcd MM |
1909 | { |
1910 | size_t ret; | |
7f397dcd | 1911 | |
e192be9d | 1912 | ret = write_pool(&input_pool, buffer, count); |
7f397dcd MM |
1913 | if (ret) |
1914 | return ret; | |
1915 | ||
7f397dcd | 1916 | return (ssize_t)count; |
1da177e4 LT |
1917 | } |
1918 | ||
43ae4860 | 1919 | static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) |
1da177e4 LT |
1920 | { |
1921 | int size, ent_count; | |
1922 | int __user *p = (int __user *)arg; | |
1923 | int retval; | |
1924 | ||
1925 | switch (cmd) { | |
1926 | case RNDGETENTCNT: | |
43ae4860 | 1927 | /* inherently racy, no point locking */ |
a283b5c4 PA |
1928 | ent_count = ENTROPY_BITS(&input_pool); |
1929 | if (put_user(ent_count, p)) | |
1da177e4 LT |
1930 | return -EFAULT; |
1931 | return 0; | |
1932 | case RNDADDTOENTCNT: | |
1933 | if (!capable(CAP_SYS_ADMIN)) | |
1934 | return -EPERM; | |
1935 | if (get_user(ent_count, p)) | |
1936 | return -EFAULT; | |
86a574de | 1937 | return credit_entropy_bits_safe(&input_pool, ent_count); |
1da177e4 LT |
1938 | case RNDADDENTROPY: |
1939 | if (!capable(CAP_SYS_ADMIN)) | |
1940 | return -EPERM; | |
1941 | if (get_user(ent_count, p++)) | |
1942 | return -EFAULT; | |
1943 | if (ent_count < 0) | |
1944 | return -EINVAL; | |
1945 | if (get_user(size, p++)) | |
1946 | return -EFAULT; | |
7f397dcd MM |
1947 | retval = write_pool(&input_pool, (const char __user *)p, |
1948 | size); | |
1da177e4 LT |
1949 | if (retval < 0) |
1950 | return retval; | |
86a574de | 1951 | return credit_entropy_bits_safe(&input_pool, ent_count); |
1da177e4 LT |
1952 | case RNDZAPENTCNT: |
1953 | case RNDCLEARPOOL: | |
ae9ecd92 TT |
1954 | /* |
1955 | * Clear the entropy pool counters. We no longer clear | |
1956 | * the entropy pool, as that's silly. | |
1957 | */ | |
1da177e4 LT |
1958 | if (!capable(CAP_SYS_ADMIN)) |
1959 | return -EPERM; | |
ae9ecd92 | 1960 | input_pool.entropy_count = 0; |
1da177e4 | 1961 | return 0; |
d848e5f8 TT |
1962 | case RNDRESEEDCRNG: |
1963 | if (!capable(CAP_SYS_ADMIN)) | |
1964 | return -EPERM; | |
1965 | if (crng_init < 2) | |
1966 | return -ENODATA; | |
11a0b5e0 | 1967 | crng_reseed(&primary_crng, &input_pool); |
009ba856 | 1968 | WRITE_ONCE(crng_global_init_time, jiffies - 1); |
d848e5f8 | 1969 | return 0; |
1da177e4 LT |
1970 | default: |
1971 | return -EINVAL; | |
1972 | } | |
1973 | } | |
1974 | ||
9a6f70bb JD |
1975 | static int random_fasync(int fd, struct file *filp, int on) |
1976 | { | |
1977 | return fasync_helper(fd, filp, on, &fasync); | |
1978 | } | |
1979 | ||
2b8693c0 | 1980 | const struct file_operations random_fops = { |
1da177e4 LT |
1981 | .read = random_read, |
1982 | .write = random_write, | |
a11e1d43 | 1983 | .poll = random_poll, |
43ae4860 | 1984 | .unlocked_ioctl = random_ioctl, |
507e4e2b | 1985 | .compat_ioctl = compat_ptr_ioctl, |
9a6f70bb | 1986 | .fasync = random_fasync, |
6038f373 | 1987 | .llseek = noop_llseek, |
1da177e4 LT |
1988 | }; |
1989 | ||
2b8693c0 | 1990 | const struct file_operations urandom_fops = { |
1da177e4 LT |
1991 | .read = urandom_read, |
1992 | .write = random_write, | |
43ae4860 | 1993 | .unlocked_ioctl = random_ioctl, |
4aa37c46 | 1994 | .compat_ioctl = compat_ptr_ioctl, |
9a6f70bb | 1995 | .fasync = random_fasync, |
6038f373 | 1996 | .llseek = noop_llseek, |
1da177e4 LT |
1997 | }; |
1998 | ||
c6e9d6f3 TT |
1999 | SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, |
2000 | unsigned int, flags) | |
2001 | { | |
e297a783 JD |
2002 | int ret; |
2003 | ||
75551dbf AL |
2004 | if (flags & ~(GRND_NONBLOCK|GRND_RANDOM|GRND_INSECURE)) |
2005 | return -EINVAL; | |
2006 | ||
2007 | /* | |
2008 | * Requesting insecure and blocking randomness at the same time makes | |
2009 | * no sense. | |
2010 | */ | |
2011 | if ((flags & (GRND_INSECURE|GRND_RANDOM)) == (GRND_INSECURE|GRND_RANDOM)) | |
c6e9d6f3 TT |
2012 | return -EINVAL; |
2013 | ||
2014 | if (count > INT_MAX) | |
2015 | count = INT_MAX; | |
2016 | ||
75551dbf | 2017 | if (!(flags & GRND_INSECURE) && !crng_ready()) { |
c6e9d6f3 TT |
2018 | if (flags & GRND_NONBLOCK) |
2019 | return -EAGAIN; | |
e297a783 JD |
2020 | ret = wait_for_random_bytes(); |
2021 | if (unlikely(ret)) | |
2022 | return ret; | |
c6e9d6f3 | 2023 | } |
c6f1deb1 | 2024 | return urandom_read_nowarn(NULL, buf, count, NULL); |
c6e9d6f3 TT |
2025 | } |
2026 | ||
1da177e4 LT |
2027 | /******************************************************************** |
2028 | * | |
2029 | * Sysctl interface | |
2030 | * | |
2031 | ********************************************************************/ | |
2032 | ||
2033 | #ifdef CONFIG_SYSCTL | |
2034 | ||
2035 | #include <linux/sysctl.h> | |
2036 | ||
c95ea0c6 | 2037 | static int min_write_thresh; |
1da177e4 | 2038 | static int max_write_thresh = INPUT_POOL_WORDS * 32; |
db61ffe3 | 2039 | static int random_min_urandom_seed = 60; |
1da177e4 LT |
2040 | static char sysctl_bootid[16]; |
2041 | ||
2042 | /* | |
f22052b2 | 2043 | * This function is used to return both the bootid UUID, and random |
1da177e4 LT |
2044 | * UUID. The difference is in whether table->data is NULL; if it is, |
2045 | * then a new UUID is generated and returned to the user. | |
2046 | * | |
f22052b2 GP |
2047 | * If the user accesses this via the proc interface, the UUID will be |
2048 | * returned as an ASCII string in the standard UUID format; if via the | |
2049 | * sysctl system call, as 16 bytes of binary data. | |
1da177e4 | 2050 | */ |
a151427e | 2051 | static int proc_do_uuid(struct ctl_table *table, int write, |
32927393 | 2052 | void *buffer, size_t *lenp, loff_t *ppos) |
1da177e4 | 2053 | { |
a151427e | 2054 | struct ctl_table fake_table; |
1da177e4 LT |
2055 | unsigned char buf[64], tmp_uuid[16], *uuid; |
2056 | ||
2057 | uuid = table->data; | |
2058 | if (!uuid) { | |
2059 | uuid = tmp_uuid; | |
1da177e4 | 2060 | generate_random_uuid(uuid); |
44e4360f MD |
2061 | } else { |
2062 | static DEFINE_SPINLOCK(bootid_spinlock); | |
2063 | ||
2064 | spin_lock(&bootid_spinlock); | |
2065 | if (!uuid[8]) | |
2066 | generate_random_uuid(uuid); | |
2067 | spin_unlock(&bootid_spinlock); | |
2068 | } | |
1da177e4 | 2069 | |
35900771 JP |
2070 | sprintf(buf, "%pU", uuid); |
2071 | ||
1da177e4 LT |
2072 | fake_table.data = buf; |
2073 | fake_table.maxlen = sizeof(buf); | |
2074 | ||
8d65af78 | 2075 | return proc_dostring(&fake_table, write, buffer, lenp, ppos); |
1da177e4 LT |
2076 | } |
2077 | ||
a283b5c4 PA |
2078 | /* |
2079 | * Return entropy available scaled to integral bits | |
2080 | */ | |
5eb10d91 | 2081 | static int proc_do_entropy(struct ctl_table *table, int write, |
a2541dcb | 2082 | void *buffer, size_t *lenp, loff_t *ppos) |
a283b5c4 | 2083 | { |
5eb10d91 | 2084 | struct ctl_table fake_table; |
a283b5c4 PA |
2085 | int entropy_count; |
2086 | ||
2087 | entropy_count = *(int *)table->data >> ENTROPY_SHIFT; | |
2088 | ||
2089 | fake_table.data = &entropy_count; | |
2090 | fake_table.maxlen = sizeof(entropy_count); | |
2091 | ||
2092 | return proc_dointvec(&fake_table, write, buffer, lenp, ppos); | |
2093 | } | |
2094 | ||
1da177e4 | 2095 | static int sysctl_poolsize = INPUT_POOL_WORDS * 32; |
a151427e JP |
2096 | extern struct ctl_table random_table[]; |
2097 | struct ctl_table random_table[] = { | |
1da177e4 | 2098 | { |
1da177e4 LT |
2099 | .procname = "poolsize", |
2100 | .data = &sysctl_poolsize, | |
2101 | .maxlen = sizeof(int), | |
2102 | .mode = 0444, | |
6d456111 | 2103 | .proc_handler = proc_dointvec, |
1da177e4 LT |
2104 | }, |
2105 | { | |
1da177e4 LT |
2106 | .procname = "entropy_avail", |
2107 | .maxlen = sizeof(int), | |
2108 | .mode = 0444, | |
a283b5c4 | 2109 | .proc_handler = proc_do_entropy, |
1da177e4 LT |
2110 | .data = &input_pool.entropy_count, |
2111 | }, | |
1da177e4 | 2112 | { |
1da177e4 | 2113 | .procname = "write_wakeup_threshold", |
2132a96f | 2114 | .data = &random_write_wakeup_bits, |
1da177e4 LT |
2115 | .maxlen = sizeof(int), |
2116 | .mode = 0644, | |
6d456111 | 2117 | .proc_handler = proc_dointvec_minmax, |
1da177e4 LT |
2118 | .extra1 = &min_write_thresh, |
2119 | .extra2 = &max_write_thresh, | |
2120 | }, | |
f5c2742c TT |
2121 | { |
2122 | .procname = "urandom_min_reseed_secs", | |
2123 | .data = &random_min_urandom_seed, | |
2124 | .maxlen = sizeof(int), | |
2125 | .mode = 0644, | |
2126 | .proc_handler = proc_dointvec, | |
2127 | }, | |
1da177e4 | 2128 | { |
1da177e4 LT |
2129 | .procname = "boot_id", |
2130 | .data = &sysctl_bootid, | |
2131 | .maxlen = 16, | |
2132 | .mode = 0444, | |
6d456111 | 2133 | .proc_handler = proc_do_uuid, |
1da177e4 LT |
2134 | }, |
2135 | { | |
1da177e4 LT |
2136 | .procname = "uuid", |
2137 | .maxlen = 16, | |
2138 | .mode = 0444, | |
6d456111 | 2139 | .proc_handler = proc_do_uuid, |
1da177e4 | 2140 | }, |
43759d4f TT |
2141 | #ifdef ADD_INTERRUPT_BENCH |
2142 | { | |
2143 | .procname = "add_interrupt_avg_cycles", | |
2144 | .data = &avg_cycles, | |
2145 | .maxlen = sizeof(avg_cycles), | |
2146 | .mode = 0444, | |
2147 | .proc_handler = proc_doulongvec_minmax, | |
2148 | }, | |
2149 | { | |
2150 | .procname = "add_interrupt_avg_deviation", | |
2151 | .data = &avg_deviation, | |
2152 | .maxlen = sizeof(avg_deviation), | |
2153 | .mode = 0444, | |
2154 | .proc_handler = proc_doulongvec_minmax, | |
2155 | }, | |
2156 | #endif | |
894d2491 | 2157 | { } |
1da177e4 LT |
2158 | }; |
2159 | #endif /* CONFIG_SYSCTL */ | |
2160 | ||
f5b98461 JD |
2161 | struct batched_entropy { |
2162 | union { | |
1ca1b917 EB |
2163 | u64 entropy_u64[CHACHA_BLOCK_SIZE / sizeof(u64)]; |
2164 | u32 entropy_u32[CHACHA_BLOCK_SIZE / sizeof(u32)]; | |
f5b98461 JD |
2165 | }; |
2166 | unsigned int position; | |
b7d5dc21 | 2167 | spinlock_t batch_lock; |
f5b98461 | 2168 | }; |
b1132dea | 2169 | |
1da177e4 | 2170 | /* |
f5b98461 | 2171 | * Get a random word for internal kernel use only. The quality of the random |
69efea71 JD |
2172 | * number is good as /dev/urandom, but there is no backtrack protection, with |
2173 | * the goal of being quite fast and not depleting entropy. In order to ensure | |
e297a783 | 2174 | * that the randomness provided by this function is okay, the function |
69efea71 JD |
2175 | * wait_for_random_bytes() should be called and return 0 at least once at any |
2176 | * point prior. | |
1da177e4 | 2177 | */ |
b7d5dc21 SAS |
2178 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = { |
2179 | .batch_lock = __SPIN_LOCK_UNLOCKED(batched_entropy_u64.lock), | |
2180 | }; | |
2181 | ||
c440408c | 2182 | u64 get_random_u64(void) |
1da177e4 | 2183 | { |
c440408c | 2184 | u64 ret; |
b7d5dc21 | 2185 | unsigned long flags; |
f5b98461 | 2186 | struct batched_entropy *batch; |
eecabf56 | 2187 | static void *previous; |
8a0a9bd4 | 2188 | |
eecabf56 | 2189 | warn_unseeded_randomness(&previous); |
d06bfd19 | 2190 | |
b7d5dc21 SAS |
2191 | batch = raw_cpu_ptr(&batched_entropy_u64); |
2192 | spin_lock_irqsave(&batch->batch_lock, flags); | |
c440408c | 2193 | if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) { |
a5e9f557 | 2194 | extract_crng((u8 *)batch->entropy_u64); |
f5b98461 JD |
2195 | batch->position = 0; |
2196 | } | |
c440408c | 2197 | ret = batch->entropy_u64[batch->position++]; |
b7d5dc21 | 2198 | spin_unlock_irqrestore(&batch->batch_lock, flags); |
8a0a9bd4 | 2199 | return ret; |
1da177e4 | 2200 | } |
c440408c | 2201 | EXPORT_SYMBOL(get_random_u64); |
1da177e4 | 2202 | |
b7d5dc21 SAS |
2203 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = { |
2204 | .batch_lock = __SPIN_LOCK_UNLOCKED(batched_entropy_u32.lock), | |
2205 | }; | |
c440408c | 2206 | u32 get_random_u32(void) |
f5b98461 | 2207 | { |
c440408c | 2208 | u32 ret; |
b7d5dc21 | 2209 | unsigned long flags; |
f5b98461 | 2210 | struct batched_entropy *batch; |
eecabf56 | 2211 | static void *previous; |
ec9ee4ac | 2212 | |
eecabf56 | 2213 | warn_unseeded_randomness(&previous); |
d06bfd19 | 2214 | |
b7d5dc21 SAS |
2215 | batch = raw_cpu_ptr(&batched_entropy_u32); |
2216 | spin_lock_irqsave(&batch->batch_lock, flags); | |
c440408c | 2217 | if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) { |
a5e9f557 | 2218 | extract_crng((u8 *)batch->entropy_u32); |
f5b98461 JD |
2219 | batch->position = 0; |
2220 | } | |
c440408c | 2221 | ret = batch->entropy_u32[batch->position++]; |
b7d5dc21 | 2222 | spin_unlock_irqrestore(&batch->batch_lock, flags); |
ec9ee4ac DC |
2223 | return ret; |
2224 | } | |
c440408c | 2225 | EXPORT_SYMBOL(get_random_u32); |
ec9ee4ac | 2226 | |
b169c13d JD |
2227 | /* It's important to invalidate all potential batched entropy that might |
2228 | * be stored before the crng is initialized, which we can do lazily by | |
2229 | * simply resetting the counter to zero so that it's re-extracted on the | |
2230 | * next usage. */ | |
2231 | static void invalidate_batched_entropy(void) | |
2232 | { | |
2233 | int cpu; | |
2234 | unsigned long flags; | |
2235 | ||
b169c13d | 2236 | for_each_possible_cpu (cpu) { |
b7d5dc21 SAS |
2237 | struct batched_entropy *batched_entropy; |
2238 | ||
2239 | batched_entropy = per_cpu_ptr(&batched_entropy_u32, cpu); | |
2240 | spin_lock_irqsave(&batched_entropy->batch_lock, flags); | |
2241 | batched_entropy->position = 0; | |
2242 | spin_unlock(&batched_entropy->batch_lock); | |
2243 | ||
2244 | batched_entropy = per_cpu_ptr(&batched_entropy_u64, cpu); | |
2245 | spin_lock(&batched_entropy->batch_lock); | |
2246 | batched_entropy->position = 0; | |
2247 | spin_unlock_irqrestore(&batched_entropy->batch_lock, flags); | |
b169c13d | 2248 | } |
b169c13d JD |
2249 | } |
2250 | ||
99fdafde JC |
2251 | /** |
2252 | * randomize_page - Generate a random, page aligned address | |
2253 | * @start: The smallest acceptable address the caller will take. | |
2254 | * @range: The size of the area, starting at @start, within which the | |
2255 | * random address must fall. | |
2256 | * | |
2257 | * If @start + @range would overflow, @range is capped. | |
2258 | * | |
2259 | * NOTE: Historical use of randomize_range, which this replaces, presumed that | |
2260 | * @start was already page aligned. We now align it regardless. | |
2261 | * | |
2262 | * Return: A page aligned address within [start, start + range). On error, | |
2263 | * @start is returned. | |
2264 | */ | |
2265 | unsigned long | |
2266 | randomize_page(unsigned long start, unsigned long range) | |
2267 | { | |
2268 | if (!PAGE_ALIGNED(start)) { | |
2269 | range -= PAGE_ALIGN(start) - start; | |
2270 | start = PAGE_ALIGN(start); | |
2271 | } | |
2272 | ||
2273 | if (start > ULONG_MAX - range) | |
2274 | range = ULONG_MAX - start; | |
2275 | ||
2276 | range >>= PAGE_SHIFT; | |
2277 | ||
2278 | if (range == 0) | |
2279 | return start; | |
2280 | ||
2281 | return start + (get_random_long() % range << PAGE_SHIFT); | |
2282 | } | |
2283 | ||
c84dbf61 TD |
2284 | /* Interface for in-kernel drivers of true hardware RNGs. |
2285 | * Those devices may produce endless random bits and will be throttled | |
2286 | * when our pool is full. | |
2287 | */ | |
2288 | void add_hwgenerator_randomness(const char *buffer, size_t count, | |
2289 | size_t entropy) | |
2290 | { | |
2291 | struct entropy_store *poolp = &input_pool; | |
2292 | ||
43838a23 | 2293 | if (unlikely(crng_init == 0)) { |
e192be9d TT |
2294 | crng_fast_load(buffer, count); |
2295 | return; | |
3371f3da | 2296 | } |
e192be9d TT |
2297 | |
2298 | /* Suspend writing if we're above the trickle threshold. | |
2299 | * We'll be woken up again once below random_write_wakeup_thresh, | |
2300 | * or when the calling thread is about to terminate. | |
2301 | */ | |
08e97aec | 2302 | wait_event_interruptible(random_write_wait, kthread_should_stop() || |
e192be9d | 2303 | ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits); |
c84dbf61 TD |
2304 | mix_pool_bytes(poolp, buffer, count); |
2305 | credit_entropy_bits(poolp, entropy); | |
2306 | } | |
2307 | EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); | |
428826f5 HYW |
2308 | |
2309 | /* Handle random seed passed by bootloader. | |
2310 | * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise | |
2311 | * it would be regarded as device data. | |
2312 | * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER. | |
2313 | */ | |
2314 | void add_bootloader_randomness(const void *buf, unsigned int size) | |
2315 | { | |
2316 | if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER)) | |
2317 | add_hwgenerator_randomness(buf, size, size * 8); | |
2318 | else | |
2319 | add_device_randomness(buf, size); | |
2320 | } | |
3fd57e7a | 2321 | EXPORT_SYMBOL_GPL(add_bootloader_randomness); |