Commit | Line | Data |
---|---|---|
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 | * | |
104 | * There are three exported interfaces; the first is one designed to | |
105 | * be used from within the kernel: | |
106 | * | |
107 | * void get_random_bytes(void *buf, int nbytes); | |
108 | * | |
109 | * This interface will return the requested number of random bytes, | |
110 | * and place it in the requested buffer. | |
111 | * | |
112 | * The two other interfaces are two character devices /dev/random and | |
113 | * /dev/urandom. /dev/random is suitable for use when very high | |
114 | * quality randomness is desired (for example, for key generation or | |
115 | * one-time pads), as it will only return a maximum of the number of | |
116 | * bits of randomness (as estimated by the random number generator) | |
117 | * contained in the entropy pool. | |
118 | * | |
119 | * The /dev/urandom device does not have this limit, and will return | |
120 | * as many bytes as are requested. As more and more random bytes are | |
121 | * requested without giving time for the entropy pool to recharge, | |
122 | * this will result in random numbers that are merely cryptographically | |
123 | * strong. For many applications, however, this is acceptable. | |
124 | * | |
125 | * Exported interfaces ---- input | |
126 | * ============================== | |
127 | * | |
128 | * The current exported interfaces for gathering environmental noise | |
129 | * from the devices are: | |
130 | * | |
a2080a67 | 131 | * void add_device_randomness(const void *buf, unsigned int size); |
1da177e4 LT |
132 | * void add_input_randomness(unsigned int type, unsigned int code, |
133 | * unsigned int value); | |
775f4b29 | 134 | * void add_interrupt_randomness(int irq, int irq_flags); |
442a4fff | 135 | * void add_disk_randomness(struct gendisk *disk); |
1da177e4 | 136 | * |
a2080a67 LT |
137 | * add_device_randomness() is for adding data to the random pool that |
138 | * is likely to differ between two devices (or possibly even per boot). | |
139 | * This would be things like MAC addresses or serial numbers, or the | |
140 | * read-out of the RTC. This does *not* add any actual entropy to the | |
141 | * pool, but it initializes the pool to different values for devices | |
142 | * that might otherwise be identical and have very little entropy | |
143 | * available to them (particularly common in the embedded world). | |
144 | * | |
1da177e4 LT |
145 | * add_input_randomness() uses the input layer interrupt timing, as well as |
146 | * the event type information from the hardware. | |
147 | * | |
775f4b29 TT |
148 | * add_interrupt_randomness() uses the interrupt timing as random |
149 | * inputs to the entropy pool. Using the cycle counters and the irq source | |
150 | * as inputs, it feeds the randomness roughly once a second. | |
442a4fff JW |
151 | * |
152 | * add_disk_randomness() uses what amounts to the seek time of block | |
153 | * layer request events, on a per-disk_devt basis, as input to the | |
154 | * entropy pool. Note that high-speed solid state drives with very low | |
155 | * seek times do not make for good sources of entropy, as their seek | |
156 | * times are usually fairly consistent. | |
1da177e4 LT |
157 | * |
158 | * All of these routines try to estimate how many bits of randomness a | |
159 | * particular randomness source. They do this by keeping track of the | |
160 | * first and second order deltas of the event timings. | |
161 | * | |
162 | * Ensuring unpredictability at system startup | |
163 | * ============================================ | |
164 | * | |
165 | * When any operating system starts up, it will go through a sequence | |
166 | * of actions that are fairly predictable by an adversary, especially | |
167 | * if the start-up does not involve interaction with a human operator. | |
168 | * This reduces the actual number of bits of unpredictability in the | |
169 | * entropy pool below the value in entropy_count. In order to | |
170 | * counteract this effect, it helps to carry information in the | |
171 | * entropy pool across shut-downs and start-ups. To do this, put the | |
172 | * following lines an appropriate script which is run during the boot | |
173 | * sequence: | |
174 | * | |
175 | * echo "Initializing random number generator..." | |
176 | * random_seed=/var/run/random-seed | |
177 | * # Carry a random seed from start-up to start-up | |
178 | * # Load and then save the whole entropy pool | |
179 | * if [ -f $random_seed ]; then | |
180 | * cat $random_seed >/dev/urandom | |
181 | * else | |
182 | * touch $random_seed | |
183 | * fi | |
184 | * chmod 600 $random_seed | |
185 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 | |
186 | * | |
187 | * and the following lines in an appropriate script which is run as | |
188 | * the system is shutdown: | |
189 | * | |
190 | * # Carry a random seed from shut-down to start-up | |
191 | * # Save the whole entropy pool | |
192 | * echo "Saving random seed..." | |
193 | * random_seed=/var/run/random-seed | |
194 | * touch $random_seed | |
195 | * chmod 600 $random_seed | |
196 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 | |
197 | * | |
198 | * For example, on most modern systems using the System V init | |
199 | * scripts, such code fragments would be found in | |
200 | * /etc/rc.d/init.d/random. On older Linux systems, the correct script | |
201 | * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0. | |
202 | * | |
203 | * Effectively, these commands cause the contents of the entropy pool | |
204 | * to be saved at shut-down time and reloaded into the entropy pool at | |
205 | * start-up. (The 'dd' in the addition to the bootup script is to | |
206 | * make sure that /etc/random-seed is different for every start-up, | |
207 | * even if the system crashes without executing rc.0.) Even with | |
208 | * complete knowledge of the start-up activities, predicting the state | |
209 | * of the entropy pool requires knowledge of the previous history of | |
210 | * the system. | |
211 | * | |
212 | * Configuring the /dev/random driver under Linux | |
213 | * ============================================== | |
214 | * | |
215 | * The /dev/random driver under Linux uses minor numbers 8 and 9 of | |
216 | * the /dev/mem major number (#1). So if your system does not have | |
217 | * /dev/random and /dev/urandom created already, they can be created | |
218 | * by using the commands: | |
219 | * | |
220 | * mknod /dev/random c 1 8 | |
221 | * mknod /dev/urandom c 1 9 | |
222 | * | |
223 | * Acknowledgements: | |
224 | * ================= | |
225 | * | |
226 | * Ideas for constructing this random number generator were derived | |
227 | * from Pretty Good Privacy's random number generator, and from private | |
228 | * discussions with Phil Karn. Colin Plumb provided a faster random | |
229 | * number generator, which speed up the mixing function of the entropy | |
230 | * pool, taken from PGPfone. Dale Worley has also contributed many | |
231 | * useful ideas and suggestions to improve this driver. | |
232 | * | |
233 | * Any flaws in the design are solely my responsibility, and should | |
234 | * not be attributed to the Phil, Colin, or any of authors of PGP. | |
235 | * | |
236 | * Further background information on this topic may be obtained from | |
237 | * RFC 1750, "Randomness Recommendations for Security", by Donald | |
238 | * Eastlake, Steve Crocker, and Jeff Schiller. | |
239 | */ | |
240 | ||
241 | #include <linux/utsname.h> | |
1da177e4 LT |
242 | #include <linux/module.h> |
243 | #include <linux/kernel.h> | |
244 | #include <linux/major.h> | |
245 | #include <linux/string.h> | |
246 | #include <linux/fcntl.h> | |
247 | #include <linux/slab.h> | |
248 | #include <linux/random.h> | |
249 | #include <linux/poll.h> | |
250 | #include <linux/init.h> | |
251 | #include <linux/fs.h> | |
252 | #include <linux/genhd.h> | |
253 | #include <linux/interrupt.h> | |
27ac792c | 254 | #include <linux/mm.h> |
dd0f0cf5 | 255 | #include <linux/nodemask.h> |
1da177e4 | 256 | #include <linux/spinlock.h> |
c84dbf61 | 257 | #include <linux/kthread.h> |
1da177e4 LT |
258 | #include <linux/percpu.h> |
259 | #include <linux/cryptohash.h> | |
5b739ef8 | 260 | #include <linux/fips.h> |
775f4b29 | 261 | #include <linux/ptrace.h> |
6265e169 | 262 | #include <linux/workqueue.h> |
0244ad00 | 263 | #include <linux/irq.h> |
c6e9d6f3 TT |
264 | #include <linux/syscalls.h> |
265 | #include <linux/completion.h> | |
8da4b8c4 | 266 | #include <linux/uuid.h> |
e192be9d | 267 | #include <crypto/chacha20.h> |
d178a1eb | 268 | |
1da177e4 | 269 | #include <asm/processor.h> |
7c0f6ba6 | 270 | #include <linux/uaccess.h> |
1da177e4 | 271 | #include <asm/irq.h> |
775f4b29 | 272 | #include <asm/irq_regs.h> |
1da177e4 LT |
273 | #include <asm/io.h> |
274 | ||
00ce1db1 TT |
275 | #define CREATE_TRACE_POINTS |
276 | #include <trace/events/random.h> | |
277 | ||
43759d4f TT |
278 | /* #define ADD_INTERRUPT_BENCH */ |
279 | ||
1da177e4 LT |
280 | /* |
281 | * Configuration information | |
282 | */ | |
30e37ec5 PA |
283 | #define INPUT_POOL_SHIFT 12 |
284 | #define INPUT_POOL_WORDS (1 << (INPUT_POOL_SHIFT-5)) | |
285 | #define OUTPUT_POOL_SHIFT 10 | |
286 | #define OUTPUT_POOL_WORDS (1 << (OUTPUT_POOL_SHIFT-5)) | |
287 | #define SEC_XFER_SIZE 512 | |
288 | #define EXTRACT_SIZE 10 | |
1da177e4 | 289 | |
1da177e4 | 290 | |
d2e7c96a PA |
291 | #define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long)) |
292 | ||
a283b5c4 | 293 | /* |
95b709b6 TT |
294 | * To allow fractional bits to be tracked, the entropy_count field is |
295 | * denominated in units of 1/8th bits. | |
30e37ec5 PA |
296 | * |
297 | * 2*(ENTROPY_SHIFT + log2(poolbits)) must <= 31, or the multiply in | |
298 | * credit_entropy_bits() needs to be 64 bits wide. | |
a283b5c4 PA |
299 | */ |
300 | #define ENTROPY_SHIFT 3 | |
301 | #define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT) | |
302 | ||
1da177e4 LT |
303 | /* |
304 | * The minimum number of bits of entropy before we wake up a read on | |
305 | * /dev/random. Should be enough to do a significant reseed. | |
306 | */ | |
2132a96f | 307 | static int random_read_wakeup_bits = 64; |
1da177e4 LT |
308 | |
309 | /* | |
310 | * If the entropy count falls under this number of bits, then we | |
311 | * should wake up processes which are selecting or polling on write | |
312 | * access to /dev/random. | |
313 | */ | |
2132a96f | 314 | static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS; |
1da177e4 | 315 | |
1da177e4 | 316 | /* |
6e9fa2c8 TT |
317 | * Originally, we used a primitive polynomial of degree .poolwords |
318 | * over GF(2). The taps for various sizes are defined below. They | |
319 | * were chosen to be evenly spaced except for the last tap, which is 1 | |
320 | * to get the twisting happening as fast as possible. | |
321 | * | |
322 | * For the purposes of better mixing, we use the CRC-32 polynomial as | |
323 | * well to make a (modified) twisted Generalized Feedback Shift | |
324 | * Register. (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR | |
325 | * generators. ACM Transactions on Modeling and Computer Simulation | |
326 | * 2(3):179-194. Also see M. Matsumoto & Y. Kurita, 1994. Twisted | |
dfd38750 | 327 | * GFSR generators II. ACM Transactions on Modeling and Computer |
6e9fa2c8 TT |
328 | * Simulation 4:254-266) |
329 | * | |
330 | * Thanks to Colin Plumb for suggesting this. | |
331 | * | |
332 | * The mixing operation is much less sensitive than the output hash, | |
333 | * where we use SHA-1. All that we want of mixing operation is that | |
334 | * it be a good non-cryptographic hash; i.e. it not produce collisions | |
335 | * when fed "random" data of the sort we expect to see. As long as | |
336 | * the pool state differs for different inputs, we have preserved the | |
337 | * input entropy and done a good job. The fact that an intelligent | |
338 | * attacker can construct inputs that will produce controlled | |
339 | * alterations to the pool's state is not important because we don't | |
340 | * consider such inputs to contribute any randomness. The only | |
341 | * property we need with respect to them is that the attacker can't | |
342 | * increase his/her knowledge of the pool's state. Since all | |
343 | * additions are reversible (knowing the final state and the input, | |
344 | * you can reconstruct the initial state), if an attacker has any | |
345 | * uncertainty about the initial state, he/she can only shuffle that | |
346 | * uncertainty about, but never cause any collisions (which would | |
347 | * decrease the uncertainty). | |
348 | * | |
349 | * Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and | |
350 | * Videau in their paper, "The Linux Pseudorandom Number Generator | |
351 | * Revisited" (see: http://eprint.iacr.org/2012/251.pdf). In their | |
352 | * paper, they point out that we are not using a true Twisted GFSR, | |
353 | * since Matsumoto & Kurita used a trinomial feedback polynomial (that | |
354 | * is, with only three taps, instead of the six that we are using). | |
355 | * As a result, the resulting polynomial is neither primitive nor | |
356 | * irreducible, and hence does not have a maximal period over | |
357 | * GF(2**32). They suggest a slight change to the generator | |
358 | * polynomial which improves the resulting TGFSR polynomial to be | |
359 | * irreducible, which we have made here. | |
1da177e4 LT |
360 | */ |
361 | static struct poolinfo { | |
a283b5c4 PA |
362 | int poolbitshift, poolwords, poolbytes, poolbits, poolfracbits; |
363 | #define S(x) ilog2(x)+5, (x), (x)*4, (x)*32, (x) << (ENTROPY_SHIFT+5) | |
1da177e4 LT |
364 | int tap1, tap2, tap3, tap4, tap5; |
365 | } poolinfo_table[] = { | |
6e9fa2c8 TT |
366 | /* was: x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 */ |
367 | /* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */ | |
368 | { S(128), 104, 76, 51, 25, 1 }, | |
369 | /* was: x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 */ | |
370 | /* x^32 + x^26 + x^19 + x^14 + x^7 + x + 1 */ | |
371 | { S(32), 26, 19, 14, 7, 1 }, | |
1da177e4 LT |
372 | #if 0 |
373 | /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */ | |
9ed17b70 | 374 | { S(2048), 1638, 1231, 819, 411, 1 }, |
1da177e4 LT |
375 | |
376 | /* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */ | |
9ed17b70 | 377 | { S(1024), 817, 615, 412, 204, 1 }, |
1da177e4 LT |
378 | |
379 | /* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */ | |
9ed17b70 | 380 | { S(1024), 819, 616, 410, 207, 2 }, |
1da177e4 LT |
381 | |
382 | /* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */ | |
9ed17b70 | 383 | { S(512), 411, 308, 208, 104, 1 }, |
1da177e4 LT |
384 | |
385 | /* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */ | |
9ed17b70 | 386 | { S(512), 409, 307, 206, 102, 2 }, |
1da177e4 | 387 | /* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */ |
9ed17b70 | 388 | { S(512), 409, 309, 205, 103, 2 }, |
1da177e4 LT |
389 | |
390 | /* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */ | |
9ed17b70 | 391 | { S(256), 205, 155, 101, 52, 1 }, |
1da177e4 LT |
392 | |
393 | /* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */ | |
9ed17b70 | 394 | { S(128), 103, 78, 51, 27, 2 }, |
1da177e4 LT |
395 | |
396 | /* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */ | |
9ed17b70 | 397 | { S(64), 52, 39, 26, 14, 1 }, |
1da177e4 LT |
398 | #endif |
399 | }; | |
400 | ||
1da177e4 LT |
401 | /* |
402 | * Static global variables | |
403 | */ | |
404 | static DECLARE_WAIT_QUEUE_HEAD(random_read_wait); | |
405 | static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); | |
9a6f70bb | 406 | static struct fasync_struct *fasync; |
1da177e4 | 407 | |
205a525c HX |
408 | static DEFINE_SPINLOCK(random_ready_list_lock); |
409 | static LIST_HEAD(random_ready_list); | |
410 | ||
e192be9d TT |
411 | struct crng_state { |
412 | __u32 state[16]; | |
413 | unsigned long init_time; | |
414 | spinlock_t lock; | |
415 | }; | |
416 | ||
417 | struct crng_state primary_crng = { | |
418 | .lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock), | |
419 | }; | |
420 | ||
421 | /* | |
422 | * crng_init = 0 --> Uninitialized | |
423 | * 1 --> Initialized | |
424 | * 2 --> Initialized from input_pool | |
425 | * | |
426 | * crng_init is protected by primary_crng->lock, and only increases | |
427 | * its value (from 0->1->2). | |
428 | */ | |
429 | static int crng_init = 0; | |
430 | #define crng_ready() (likely(crng_init > 0)) | |
431 | static int crng_init_cnt = 0; | |
432 | #define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE) | |
1e7f583a | 433 | static void _extract_crng(struct crng_state *crng, |
9f480fae | 434 | __u32 out[CHACHA20_BLOCK_WORDS]); |
c92e040d | 435 | static void _crng_backtrack_protect(struct crng_state *crng, |
9f480fae | 436 | __u32 tmp[CHACHA20_BLOCK_WORDS], int used); |
e192be9d | 437 | static void process_random_ready_list(void); |
eecabf56 | 438 | static void _get_random_bytes(void *buf, int nbytes); |
e192be9d | 439 | |
1da177e4 LT |
440 | /********************************************************************** |
441 | * | |
442 | * OS independent entropy store. Here are the functions which handle | |
443 | * storing entropy in an entropy pool. | |
444 | * | |
445 | **********************************************************************/ | |
446 | ||
447 | struct entropy_store; | |
448 | struct entropy_store { | |
43358209 | 449 | /* read-only data: */ |
30e37ec5 | 450 | const struct poolinfo *poolinfo; |
1da177e4 LT |
451 | __u32 *pool; |
452 | const char *name; | |
1da177e4 | 453 | struct entropy_store *pull; |
6265e169 | 454 | struct work_struct push_work; |
1da177e4 LT |
455 | |
456 | /* read-write data: */ | |
f5c2742c | 457 | unsigned long last_pulled; |
43358209 | 458 | spinlock_t lock; |
c59974ae TT |
459 | unsigned short add_ptr; |
460 | unsigned short input_rotate; | |
cda796a3 | 461 | int entropy_count; |
775f4b29 | 462 | int entropy_total; |
775f4b29 | 463 | unsigned int initialized:1; |
c59974ae | 464 | unsigned int last_data_init:1; |
e954bc91 | 465 | __u8 last_data[EXTRACT_SIZE]; |
1da177e4 LT |
466 | }; |
467 | ||
e192be9d TT |
468 | static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
469 | size_t nbytes, int min, int rsvd); | |
470 | static ssize_t _extract_entropy(struct entropy_store *r, void *buf, | |
471 | size_t nbytes, int fips); | |
472 | ||
473 | static void crng_reseed(struct crng_state *crng, struct entropy_store *r); | |
6265e169 | 474 | static void push_to_pool(struct work_struct *work); |
0766f788 ER |
475 | static __u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy; |
476 | static __u32 blocking_pool_data[OUTPUT_POOL_WORDS] __latent_entropy; | |
1da177e4 LT |
477 | |
478 | static struct entropy_store input_pool = { | |
479 | .poolinfo = &poolinfo_table[0], | |
480 | .name = "input", | |
eece09ec | 481 | .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock), |
1da177e4 LT |
482 | .pool = input_pool_data |
483 | }; | |
484 | ||
485 | static struct entropy_store blocking_pool = { | |
486 | .poolinfo = &poolinfo_table[1], | |
487 | .name = "blocking", | |
1da177e4 | 488 | .pull = &input_pool, |
eece09ec | 489 | .lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock), |
6265e169 TT |
490 | .pool = blocking_pool_data, |
491 | .push_work = __WORK_INITIALIZER(blocking_pool.push_work, | |
492 | push_to_pool), | |
1da177e4 LT |
493 | }; |
494 | ||
775f4b29 TT |
495 | static __u32 const twist_table[8] = { |
496 | 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158, | |
497 | 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 }; | |
498 | ||
1da177e4 | 499 | /* |
e68e5b66 | 500 | * This function adds bytes into the entropy "pool". It does not |
1da177e4 | 501 | * update the entropy estimate. The caller should call |
adc782da | 502 | * credit_entropy_bits if this is appropriate. |
1da177e4 LT |
503 | * |
504 | * The pool is stirred with a primitive polynomial of the appropriate | |
505 | * degree, and then twisted. We twist by three bits at a time because | |
506 | * it's cheap to do so and helps slightly in the expected case where | |
507 | * the entropy is concentrated in the low-order bits. | |
508 | */ | |
00ce1db1 | 509 | static void _mix_pool_bytes(struct entropy_store *r, const void *in, |
85608f8e | 510 | int nbytes) |
1da177e4 | 511 | { |
85608f8e | 512 | unsigned long i, tap1, tap2, tap3, tap4, tap5; |
feee7697 | 513 | int input_rotate; |
1da177e4 | 514 | int wordmask = r->poolinfo->poolwords - 1; |
e68e5b66 | 515 | const char *bytes = in; |
6d38b827 | 516 | __u32 w; |
1da177e4 | 517 | |
1da177e4 LT |
518 | tap1 = r->poolinfo->tap1; |
519 | tap2 = r->poolinfo->tap2; | |
520 | tap3 = r->poolinfo->tap3; | |
521 | tap4 = r->poolinfo->tap4; | |
522 | tap5 = r->poolinfo->tap5; | |
1da177e4 | 523 | |
91fcb532 TT |
524 | input_rotate = r->input_rotate; |
525 | i = r->add_ptr; | |
1da177e4 | 526 | |
e68e5b66 MM |
527 | /* mix one byte at a time to simplify size handling and churn faster */ |
528 | while (nbytes--) { | |
c59974ae | 529 | w = rol32(*bytes++, input_rotate); |
993ba211 | 530 | i = (i - 1) & wordmask; |
1da177e4 LT |
531 | |
532 | /* XOR in the various taps */ | |
993ba211 | 533 | w ^= r->pool[i]; |
1da177e4 LT |
534 | w ^= r->pool[(i + tap1) & wordmask]; |
535 | w ^= r->pool[(i + tap2) & wordmask]; | |
536 | w ^= r->pool[(i + tap3) & wordmask]; | |
537 | w ^= r->pool[(i + tap4) & wordmask]; | |
538 | w ^= r->pool[(i + tap5) & wordmask]; | |
993ba211 MM |
539 | |
540 | /* Mix the result back in with a twist */ | |
1da177e4 | 541 | r->pool[i] = (w >> 3) ^ twist_table[w & 7]; |
feee7697 MM |
542 | |
543 | /* | |
544 | * Normally, we add 7 bits of rotation to the pool. | |
545 | * At the beginning of the pool, add an extra 7 bits | |
546 | * rotation, so that successive passes spread the | |
547 | * input bits across the pool evenly. | |
548 | */ | |
c59974ae | 549 | input_rotate = (input_rotate + (i ? 7 : 14)) & 31; |
1da177e4 LT |
550 | } |
551 | ||
91fcb532 TT |
552 | r->input_rotate = input_rotate; |
553 | r->add_ptr = i; | |
1da177e4 LT |
554 | } |
555 | ||
00ce1db1 | 556 | static void __mix_pool_bytes(struct entropy_store *r, const void *in, |
85608f8e | 557 | int nbytes) |
00ce1db1 TT |
558 | { |
559 | trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_); | |
85608f8e | 560 | _mix_pool_bytes(r, in, nbytes); |
00ce1db1 TT |
561 | } |
562 | ||
563 | static void mix_pool_bytes(struct entropy_store *r, const void *in, | |
85608f8e | 564 | int nbytes) |
1da177e4 | 565 | { |
902c098a TT |
566 | unsigned long flags; |
567 | ||
00ce1db1 | 568 | trace_mix_pool_bytes(r->name, nbytes, _RET_IP_); |
902c098a | 569 | spin_lock_irqsave(&r->lock, flags); |
85608f8e | 570 | _mix_pool_bytes(r, in, nbytes); |
902c098a | 571 | spin_unlock_irqrestore(&r->lock, flags); |
1da177e4 LT |
572 | } |
573 | ||
775f4b29 TT |
574 | struct fast_pool { |
575 | __u32 pool[4]; | |
576 | unsigned long last; | |
ee3e00e9 | 577 | unsigned short reg_idx; |
840f9507 | 578 | unsigned char count; |
775f4b29 TT |
579 | }; |
580 | ||
581 | /* | |
582 | * This is a fast mixing routine used by the interrupt randomness | |
583 | * collector. It's hardcoded for an 128 bit pool and assumes that any | |
584 | * locks that might be needed are taken by the caller. | |
585 | */ | |
43759d4f | 586 | static void fast_mix(struct fast_pool *f) |
775f4b29 | 587 | { |
43759d4f TT |
588 | __u32 a = f->pool[0], b = f->pool[1]; |
589 | __u32 c = f->pool[2], d = f->pool[3]; | |
590 | ||
591 | a += b; c += d; | |
19acc77a | 592 | b = rol32(b, 6); d = rol32(d, 27); |
43759d4f TT |
593 | d ^= a; b ^= c; |
594 | ||
595 | a += b; c += d; | |
19acc77a | 596 | b = rol32(b, 16); d = rol32(d, 14); |
43759d4f TT |
597 | d ^= a; b ^= c; |
598 | ||
599 | a += b; c += d; | |
19acc77a | 600 | b = rol32(b, 6); d = rol32(d, 27); |
43759d4f TT |
601 | d ^= a; b ^= c; |
602 | ||
603 | a += b; c += d; | |
19acc77a | 604 | b = rol32(b, 16); d = rol32(d, 14); |
43759d4f TT |
605 | d ^= a; b ^= c; |
606 | ||
607 | f->pool[0] = a; f->pool[1] = b; | |
608 | f->pool[2] = c; f->pool[3] = d; | |
655b2264 | 609 | f->count++; |
775f4b29 TT |
610 | } |
611 | ||
205a525c HX |
612 | static void process_random_ready_list(void) |
613 | { | |
614 | unsigned long flags; | |
615 | struct random_ready_callback *rdy, *tmp; | |
616 | ||
617 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
618 | list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) { | |
619 | struct module *owner = rdy->owner; | |
620 | ||
621 | list_del_init(&rdy->list); | |
622 | rdy->func(rdy); | |
623 | module_put(owner); | |
624 | } | |
625 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
626 | } | |
627 | ||
1da177e4 | 628 | /* |
a283b5c4 PA |
629 | * Credit (or debit) the entropy store with n bits of entropy. |
630 | * Use credit_entropy_bits_safe() if the value comes from userspace | |
631 | * or otherwise should be checked for extreme values. | |
1da177e4 | 632 | */ |
adc782da | 633 | static void credit_entropy_bits(struct entropy_store *r, int nbits) |
1da177e4 | 634 | { |
902c098a | 635 | int entropy_count, orig; |
30e37ec5 PA |
636 | const int pool_size = r->poolinfo->poolfracbits; |
637 | int nfrac = nbits << ENTROPY_SHIFT; | |
1da177e4 | 638 | |
adc782da MM |
639 | if (!nbits) |
640 | return; | |
641 | ||
902c098a | 642 | retry: |
6aa7de05 | 643 | entropy_count = orig = READ_ONCE(r->entropy_count); |
30e37ec5 PA |
644 | if (nfrac < 0) { |
645 | /* Debit */ | |
646 | entropy_count += nfrac; | |
647 | } else { | |
648 | /* | |
649 | * Credit: we have to account for the possibility of | |
650 | * overwriting already present entropy. Even in the | |
651 | * ideal case of pure Shannon entropy, new contributions | |
652 | * approach the full value asymptotically: | |
653 | * | |
654 | * entropy <- entropy + (pool_size - entropy) * | |
655 | * (1 - exp(-add_entropy/pool_size)) | |
656 | * | |
657 | * For add_entropy <= pool_size/2 then | |
658 | * (1 - exp(-add_entropy/pool_size)) >= | |
659 | * (add_entropy/pool_size)*0.7869... | |
660 | * so we can approximate the exponential with | |
661 | * 3/4*add_entropy/pool_size and still be on the | |
662 | * safe side by adding at most pool_size/2 at a time. | |
663 | * | |
664 | * The use of pool_size-2 in the while statement is to | |
665 | * prevent rounding artifacts from making the loop | |
666 | * arbitrarily long; this limits the loop to log2(pool_size)*2 | |
667 | * turns no matter how large nbits is. | |
668 | */ | |
669 | int pnfrac = nfrac; | |
670 | const int s = r->poolinfo->poolbitshift + ENTROPY_SHIFT + 2; | |
671 | /* The +2 corresponds to the /4 in the denominator */ | |
672 | ||
673 | do { | |
674 | unsigned int anfrac = min(pnfrac, pool_size/2); | |
675 | unsigned int add = | |
676 | ((pool_size - entropy_count)*anfrac*3) >> s; | |
677 | ||
678 | entropy_count += add; | |
679 | pnfrac -= anfrac; | |
680 | } while (unlikely(entropy_count < pool_size-2 && pnfrac)); | |
681 | } | |
00ce1db1 | 682 | |
79a84687 | 683 | if (unlikely(entropy_count < 0)) { |
f80bbd8b TT |
684 | pr_warn("random: negative entropy/overflow: pool %s count %d\n", |
685 | r->name, entropy_count); | |
686 | WARN_ON(1); | |
8b76f46a | 687 | entropy_count = 0; |
30e37ec5 PA |
688 | } else if (entropy_count > pool_size) |
689 | entropy_count = pool_size; | |
902c098a TT |
690 | if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) |
691 | goto retry; | |
1da177e4 | 692 | |
6265e169 | 693 | r->entropy_total += nbits; |
0891ad82 LT |
694 | if (!r->initialized && r->entropy_total > 128) { |
695 | r->initialized = 1; | |
696 | r->entropy_total = 0; | |
775f4b29 TT |
697 | } |
698 | ||
a283b5c4 PA |
699 | trace_credit_entropy_bits(r->name, nbits, |
700 | entropy_count >> ENTROPY_SHIFT, | |
00ce1db1 TT |
701 | r->entropy_total, _RET_IP_); |
702 | ||
6265e169 | 703 | if (r == &input_pool) { |
7d1b08c4 | 704 | int entropy_bits = entropy_count >> ENTROPY_SHIFT; |
6265e169 | 705 | |
e192be9d TT |
706 | if (crng_init < 2 && entropy_bits >= 128) { |
707 | crng_reseed(&primary_crng, r); | |
708 | entropy_bits = r->entropy_count >> ENTROPY_SHIFT; | |
709 | } | |
710 | ||
6265e169 | 711 | /* should we wake readers? */ |
e8e8a2e4 AK |
712 | if (entropy_bits >= random_read_wakeup_bits && |
713 | wq_has_sleeper(&random_read_wait)) { | |
6265e169 TT |
714 | wake_up_interruptible(&random_read_wait); |
715 | kill_fasync(&fasync, SIGIO, POLL_IN); | |
716 | } | |
717 | /* If the input pool is getting full, send some | |
e192be9d | 718 | * entropy to the blocking pool until it is 75% full. |
6265e169 | 719 | */ |
2132a96f | 720 | if (entropy_bits > random_write_wakeup_bits && |
6265e169 | 721 | r->initialized && |
2132a96f | 722 | r->entropy_total >= 2*random_read_wakeup_bits) { |
6265e169 TT |
723 | struct entropy_store *other = &blocking_pool; |
724 | ||
6265e169 | 725 | if (other->entropy_count <= |
e192be9d TT |
726 | 3 * other->poolinfo->poolfracbits / 4) { |
727 | schedule_work(&other->push_work); | |
6265e169 TT |
728 | r->entropy_total = 0; |
729 | } | |
730 | } | |
9a6f70bb | 731 | } |
1da177e4 LT |
732 | } |
733 | ||
86a574de | 734 | static int credit_entropy_bits_safe(struct entropy_store *r, int nbits) |
a283b5c4 | 735 | { |
9f886f4d | 736 | const int nbits_max = r->poolinfo->poolwords * 32; |
a283b5c4 | 737 | |
86a574de TT |
738 | if (nbits < 0) |
739 | return -EINVAL; | |
740 | ||
a283b5c4 PA |
741 | /* Cap the value to avoid overflows */ |
742 | nbits = min(nbits, nbits_max); | |
a283b5c4 PA |
743 | |
744 | credit_entropy_bits(r, nbits); | |
86a574de | 745 | return 0; |
a283b5c4 PA |
746 | } |
747 | ||
e192be9d TT |
748 | /********************************************************************* |
749 | * | |
750 | * CRNG using CHACHA20 | |
751 | * | |
752 | *********************************************************************/ | |
753 | ||
754 | #define CRNG_RESEED_INTERVAL (300*HZ) | |
755 | ||
756 | static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); | |
757 | ||
1e7f583a TT |
758 | #ifdef CONFIG_NUMA |
759 | /* | |
760 | * Hack to deal with crazy userspace progams when they are all trying | |
761 | * to access /dev/urandom in parallel. The programs are almost | |
762 | * certainly doing something terribly wrong, but we'll work around | |
763 | * their brain damage. | |
764 | */ | |
765 | static struct crng_state **crng_node_pool __read_mostly; | |
766 | #endif | |
767 | ||
b169c13d JD |
768 | static void invalidate_batched_entropy(void); |
769 | ||
e192be9d TT |
770 | static void crng_initialize(struct crng_state *crng) |
771 | { | |
772 | int i; | |
773 | unsigned long rv; | |
774 | ||
775 | memcpy(&crng->state[0], "expand 32-byte k", 16); | |
776 | if (crng == &primary_crng) | |
777 | _extract_entropy(&input_pool, &crng->state[4], | |
778 | sizeof(__u32) * 12, 0); | |
779 | else | |
eecabf56 | 780 | _get_random_bytes(&crng->state[4], sizeof(__u32) * 12); |
e192be9d TT |
781 | for (i = 4; i < 16; i++) { |
782 | if (!arch_get_random_seed_long(&rv) && | |
783 | !arch_get_random_long(&rv)) | |
784 | rv = random_get_entropy(); | |
785 | crng->state[i] ^= rv; | |
786 | } | |
787 | crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1; | |
788 | } | |
789 | ||
790 | static int crng_fast_load(const char *cp, size_t len) | |
791 | { | |
792 | unsigned long flags; | |
793 | char *p; | |
794 | ||
795 | if (!spin_trylock_irqsave(&primary_crng.lock, flags)) | |
796 | return 0; | |
797 | if (crng_ready()) { | |
798 | spin_unlock_irqrestore(&primary_crng.lock, flags); | |
799 | return 0; | |
800 | } | |
801 | p = (unsigned char *) &primary_crng.state[4]; | |
802 | while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) { | |
803 | p[crng_init_cnt % CHACHA20_KEY_SIZE] ^= *cp; | |
804 | cp++; crng_init_cnt++; len--; | |
805 | } | |
4a072c71 | 806 | spin_unlock_irqrestore(&primary_crng.lock, flags); |
e192be9d | 807 | if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) { |
b169c13d | 808 | invalidate_batched_entropy(); |
e192be9d TT |
809 | crng_init = 1; |
810 | wake_up_interruptible(&crng_init_wait); | |
811 | pr_notice("random: fast init done\n"); | |
812 | } | |
e192be9d TT |
813 | return 1; |
814 | } | |
815 | ||
816 | static void crng_reseed(struct crng_state *crng, struct entropy_store *r) | |
817 | { | |
818 | unsigned long flags; | |
819 | int i, num; | |
820 | union { | |
9f480fae | 821 | __u32 block[CHACHA20_BLOCK_WORDS]; |
e192be9d TT |
822 | __u32 key[8]; |
823 | } buf; | |
824 | ||
825 | if (r) { | |
826 | num = extract_entropy(r, &buf, 32, 16, 0); | |
827 | if (num == 0) | |
828 | return; | |
c92e040d | 829 | } else { |
1e7f583a | 830 | _extract_crng(&primary_crng, buf.block); |
c92e040d TT |
831 | _crng_backtrack_protect(&primary_crng, buf.block, |
832 | CHACHA20_KEY_SIZE); | |
833 | } | |
e192be9d TT |
834 | spin_lock_irqsave(&primary_crng.lock, flags); |
835 | for (i = 0; i < 8; i++) { | |
836 | unsigned long rv; | |
837 | if (!arch_get_random_seed_long(&rv) && | |
838 | !arch_get_random_long(&rv)) | |
839 | rv = random_get_entropy(); | |
840 | crng->state[i+4] ^= buf.key[i] ^ rv; | |
841 | } | |
842 | memzero_explicit(&buf, sizeof(buf)); | |
843 | crng->init_time = jiffies; | |
4a072c71 | 844 | spin_unlock_irqrestore(&primary_crng.lock, flags); |
e192be9d | 845 | if (crng == &primary_crng && crng_init < 2) { |
b169c13d | 846 | invalidate_batched_entropy(); |
e192be9d TT |
847 | crng_init = 2; |
848 | process_random_ready_list(); | |
849 | wake_up_interruptible(&crng_init_wait); | |
850 | pr_notice("random: crng init done\n"); | |
851 | } | |
e192be9d TT |
852 | } |
853 | ||
1e7f583a | 854 | static void _extract_crng(struct crng_state *crng, |
9f480fae | 855 | __u32 out[CHACHA20_BLOCK_WORDS]) |
e192be9d TT |
856 | { |
857 | unsigned long v, flags; | |
e192be9d TT |
858 | |
859 | if (crng_init > 1 && | |
860 | time_after(jiffies, crng->init_time + CRNG_RESEED_INTERVAL)) | |
1e7f583a | 861 | crng_reseed(crng, crng == &primary_crng ? &input_pool : NULL); |
e192be9d TT |
862 | spin_lock_irqsave(&crng->lock, flags); |
863 | if (arch_get_random_long(&v)) | |
864 | crng->state[14] ^= v; | |
865 | chacha20_block(&crng->state[0], out); | |
866 | if (crng->state[12] == 0) | |
867 | crng->state[13]++; | |
868 | spin_unlock_irqrestore(&crng->lock, flags); | |
869 | } | |
870 | ||
9f480fae | 871 | static void extract_crng(__u32 out[CHACHA20_BLOCK_WORDS]) |
1e7f583a TT |
872 | { |
873 | struct crng_state *crng = NULL; | |
874 | ||
875 | #ifdef CONFIG_NUMA | |
876 | if (crng_node_pool) | |
877 | crng = crng_node_pool[numa_node_id()]; | |
878 | if (crng == NULL) | |
879 | #endif | |
880 | crng = &primary_crng; | |
881 | _extract_crng(crng, out); | |
882 | } | |
883 | ||
c92e040d TT |
884 | /* |
885 | * Use the leftover bytes from the CRNG block output (if there is | |
886 | * enough) to mutate the CRNG key to provide backtracking protection. | |
887 | */ | |
888 | static void _crng_backtrack_protect(struct crng_state *crng, | |
9f480fae | 889 | __u32 tmp[CHACHA20_BLOCK_WORDS], int used) |
c92e040d TT |
890 | { |
891 | unsigned long flags; | |
892 | __u32 *s, *d; | |
893 | int i; | |
894 | ||
895 | used = round_up(used, sizeof(__u32)); | |
896 | if (used + CHACHA20_KEY_SIZE > CHACHA20_BLOCK_SIZE) { | |
897 | extract_crng(tmp); | |
898 | used = 0; | |
899 | } | |
900 | spin_lock_irqsave(&crng->lock, flags); | |
9f480fae | 901 | s = &tmp[used / sizeof(__u32)]; |
c92e040d TT |
902 | d = &crng->state[4]; |
903 | for (i=0; i < 8; i++) | |
904 | *d++ ^= *s++; | |
905 | spin_unlock_irqrestore(&crng->lock, flags); | |
906 | } | |
907 | ||
9f480fae | 908 | static void crng_backtrack_protect(__u32 tmp[CHACHA20_BLOCK_WORDS], int used) |
c92e040d TT |
909 | { |
910 | struct crng_state *crng = NULL; | |
911 | ||
912 | #ifdef CONFIG_NUMA | |
913 | if (crng_node_pool) | |
914 | crng = crng_node_pool[numa_node_id()]; | |
915 | if (crng == NULL) | |
916 | #endif | |
917 | crng = &primary_crng; | |
918 | _crng_backtrack_protect(crng, tmp, used); | |
919 | } | |
920 | ||
e192be9d TT |
921 | static ssize_t extract_crng_user(void __user *buf, size_t nbytes) |
922 | { | |
c92e040d | 923 | ssize_t ret = 0, i = CHACHA20_BLOCK_SIZE; |
9f480fae | 924 | __u32 tmp[CHACHA20_BLOCK_WORDS]; |
e192be9d TT |
925 | int large_request = (nbytes > 256); |
926 | ||
927 | while (nbytes) { | |
928 | if (large_request && need_resched()) { | |
929 | if (signal_pending(current)) { | |
930 | if (ret == 0) | |
931 | ret = -ERESTARTSYS; | |
932 | break; | |
933 | } | |
934 | schedule(); | |
935 | } | |
936 | ||
937 | extract_crng(tmp); | |
938 | i = min_t(int, nbytes, CHACHA20_BLOCK_SIZE); | |
939 | if (copy_to_user(buf, tmp, i)) { | |
940 | ret = -EFAULT; | |
941 | break; | |
942 | } | |
943 | ||
944 | nbytes -= i; | |
945 | buf += i; | |
946 | ret += i; | |
947 | } | |
c92e040d | 948 | crng_backtrack_protect(tmp, i); |
e192be9d TT |
949 | |
950 | /* Wipe data just written to memory */ | |
951 | memzero_explicit(tmp, sizeof(tmp)); | |
952 | ||
953 | return ret; | |
954 | } | |
955 | ||
956 | ||
1da177e4 LT |
957 | /********************************************************************* |
958 | * | |
959 | * Entropy input management | |
960 | * | |
961 | *********************************************************************/ | |
962 | ||
963 | /* There is one of these per entropy source */ | |
964 | struct timer_rand_state { | |
965 | cycles_t last_time; | |
90b75ee5 | 966 | long last_delta, last_delta2; |
1da177e4 LT |
967 | unsigned dont_count_entropy:1; |
968 | }; | |
969 | ||
644008df TT |
970 | #define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, }; |
971 | ||
a2080a67 | 972 | /* |
e192be9d TT |
973 | * Add device- or boot-specific data to the input pool to help |
974 | * initialize it. | |
a2080a67 | 975 | * |
e192be9d TT |
976 | * None of this adds any entropy; it is meant to avoid the problem of |
977 | * the entropy pool having similar initial state across largely | |
978 | * identical devices. | |
a2080a67 LT |
979 | */ |
980 | void add_device_randomness(const void *buf, unsigned int size) | |
981 | { | |
61875f30 | 982 | unsigned long time = random_get_entropy() ^ jiffies; |
3ef4cb2d | 983 | unsigned long flags; |
a2080a67 | 984 | |
ee7998c5 KC |
985 | if (!crng_ready()) { |
986 | crng_fast_load(buf, size); | |
987 | return; | |
988 | } | |
989 | ||
5910895f | 990 | trace_add_device_randomness(size, _RET_IP_); |
3ef4cb2d | 991 | spin_lock_irqsave(&input_pool.lock, flags); |
85608f8e TT |
992 | _mix_pool_bytes(&input_pool, buf, size); |
993 | _mix_pool_bytes(&input_pool, &time, sizeof(time)); | |
3ef4cb2d | 994 | spin_unlock_irqrestore(&input_pool.lock, flags); |
a2080a67 LT |
995 | } |
996 | EXPORT_SYMBOL(add_device_randomness); | |
997 | ||
644008df | 998 | static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE; |
3060d6fe | 999 | |
1da177e4 LT |
1000 | /* |
1001 | * This function adds entropy to the entropy "pool" by using timing | |
1002 | * delays. It uses the timer_rand_state structure to make an estimate | |
1003 | * of how many bits of entropy this call has added to the pool. | |
1004 | * | |
1005 | * The number "num" is also added to the pool - it should somehow describe | |
1006 | * the type of event which just happened. This is currently 0-255 for | |
1007 | * keyboard scan codes, and 256 upwards for interrupts. | |
1008 | * | |
1009 | */ | |
1010 | static void add_timer_randomness(struct timer_rand_state *state, unsigned num) | |
1011 | { | |
40db23e5 | 1012 | struct entropy_store *r; |
1da177e4 | 1013 | struct { |
1da177e4 | 1014 | long jiffies; |
cf833d0b | 1015 | unsigned cycles; |
1da177e4 LT |
1016 | unsigned num; |
1017 | } sample; | |
1018 | long delta, delta2, delta3; | |
1019 | ||
1020 | preempt_disable(); | |
1da177e4 LT |
1021 | |
1022 | sample.jiffies = jiffies; | |
61875f30 | 1023 | sample.cycles = random_get_entropy(); |
1da177e4 | 1024 | sample.num = num; |
e192be9d | 1025 | r = &input_pool; |
85608f8e | 1026 | mix_pool_bytes(r, &sample, sizeof(sample)); |
1da177e4 LT |
1027 | |
1028 | /* | |
1029 | * Calculate number of bits of randomness we probably added. | |
1030 | * We take into account the first, second and third-order deltas | |
1031 | * in order to make our estimate. | |
1032 | */ | |
1033 | ||
1034 | if (!state->dont_count_entropy) { | |
1035 | delta = sample.jiffies - state->last_time; | |
1036 | state->last_time = sample.jiffies; | |
1037 | ||
1038 | delta2 = delta - state->last_delta; | |
1039 | state->last_delta = delta; | |
1040 | ||
1041 | delta3 = delta2 - state->last_delta2; | |
1042 | state->last_delta2 = delta2; | |
1043 | ||
1044 | if (delta < 0) | |
1045 | delta = -delta; | |
1046 | if (delta2 < 0) | |
1047 | delta2 = -delta2; | |
1048 | if (delta3 < 0) | |
1049 | delta3 = -delta3; | |
1050 | if (delta > delta2) | |
1051 | delta = delta2; | |
1052 | if (delta > delta3) | |
1053 | delta = delta3; | |
1054 | ||
1055 | /* | |
1056 | * delta is now minimum absolute delta. | |
1057 | * Round down by 1 bit on general principles, | |
1058 | * and limit entropy entimate to 12 bits. | |
1059 | */ | |
40db23e5 | 1060 | credit_entropy_bits(r, min_t(int, fls(delta>>1), 11)); |
1da177e4 | 1061 | } |
1da177e4 LT |
1062 | preempt_enable(); |
1063 | } | |
1064 | ||
d251575a | 1065 | void add_input_randomness(unsigned int type, unsigned int code, |
1da177e4 LT |
1066 | unsigned int value) |
1067 | { | |
1068 | static unsigned char last_value; | |
1069 | ||
1070 | /* ignore autorepeat and the like */ | |
1071 | if (value == last_value) | |
1072 | return; | |
1073 | ||
1da177e4 LT |
1074 | last_value = value; |
1075 | add_timer_randomness(&input_timer_state, | |
1076 | (type << 4) ^ code ^ (code >> 4) ^ value); | |
f80bbd8b | 1077 | trace_add_input_randomness(ENTROPY_BITS(&input_pool)); |
1da177e4 | 1078 | } |
80fc9f53 | 1079 | EXPORT_SYMBOL_GPL(add_input_randomness); |
1da177e4 | 1080 | |
775f4b29 TT |
1081 | static DEFINE_PER_CPU(struct fast_pool, irq_randomness); |
1082 | ||
43759d4f TT |
1083 | #ifdef ADD_INTERRUPT_BENCH |
1084 | static unsigned long avg_cycles, avg_deviation; | |
1085 | ||
1086 | #define AVG_SHIFT 8 /* Exponential average factor k=1/256 */ | |
1087 | #define FIXED_1_2 (1 << (AVG_SHIFT-1)) | |
1088 | ||
1089 | static void add_interrupt_bench(cycles_t start) | |
1090 | { | |
1091 | long delta = random_get_entropy() - start; | |
1092 | ||
1093 | /* Use a weighted moving average */ | |
1094 | delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT); | |
1095 | avg_cycles += delta; | |
1096 | /* And average deviation */ | |
1097 | delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT); | |
1098 | avg_deviation += delta; | |
1099 | } | |
1100 | #else | |
1101 | #define add_interrupt_bench(x) | |
1102 | #endif | |
1103 | ||
ee3e00e9 TT |
1104 | static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs) |
1105 | { | |
1106 | __u32 *ptr = (__u32 *) regs; | |
92e75428 | 1107 | unsigned int idx; |
ee3e00e9 TT |
1108 | |
1109 | if (regs == NULL) | |
1110 | return 0; | |
92e75428 TT |
1111 | idx = READ_ONCE(f->reg_idx); |
1112 | if (idx >= sizeof(struct pt_regs) / sizeof(__u32)) | |
1113 | idx = 0; | |
1114 | ptr += idx++; | |
1115 | WRITE_ONCE(f->reg_idx, idx); | |
9dfa7bba | 1116 | return *ptr; |
ee3e00e9 TT |
1117 | } |
1118 | ||
775f4b29 | 1119 | void add_interrupt_randomness(int irq, int irq_flags) |
1da177e4 | 1120 | { |
775f4b29 | 1121 | struct entropy_store *r; |
1b2a1a7e | 1122 | struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness); |
775f4b29 TT |
1123 | struct pt_regs *regs = get_irq_regs(); |
1124 | unsigned long now = jiffies; | |
655b2264 | 1125 | cycles_t cycles = random_get_entropy(); |
43759d4f | 1126 | __u32 c_high, j_high; |
655b2264 | 1127 | __u64 ip; |
83664a69 | 1128 | unsigned long seed; |
91fcb532 | 1129 | int credit = 0; |
3060d6fe | 1130 | |
ee3e00e9 TT |
1131 | if (cycles == 0) |
1132 | cycles = get_reg(fast_pool, regs); | |
655b2264 TT |
1133 | c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0; |
1134 | j_high = (sizeof(now) > 4) ? now >> 32 : 0; | |
43759d4f TT |
1135 | fast_pool->pool[0] ^= cycles ^ j_high ^ irq; |
1136 | fast_pool->pool[1] ^= now ^ c_high; | |
655b2264 | 1137 | ip = regs ? instruction_pointer(regs) : _RET_IP_; |
43759d4f | 1138 | fast_pool->pool[2] ^= ip; |
ee3e00e9 TT |
1139 | fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 : |
1140 | get_reg(fast_pool, regs); | |
3060d6fe | 1141 | |
43759d4f | 1142 | fast_mix(fast_pool); |
43759d4f | 1143 | add_interrupt_bench(cycles); |
3060d6fe | 1144 | |
e192be9d TT |
1145 | if (!crng_ready()) { |
1146 | if ((fast_pool->count >= 64) && | |
1147 | crng_fast_load((char *) fast_pool->pool, | |
1148 | sizeof(fast_pool->pool))) { | |
1149 | fast_pool->count = 0; | |
1150 | fast_pool->last = now; | |
1151 | } | |
1152 | return; | |
1153 | } | |
1154 | ||
ee3e00e9 TT |
1155 | if ((fast_pool->count < 64) && |
1156 | !time_after(now, fast_pool->last + HZ)) | |
1da177e4 LT |
1157 | return; |
1158 | ||
e192be9d | 1159 | r = &input_pool; |
840f9507 | 1160 | if (!spin_trylock(&r->lock)) |
91fcb532 | 1161 | return; |
83664a69 | 1162 | |
91fcb532 | 1163 | fast_pool->last = now; |
85608f8e | 1164 | __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool)); |
83664a69 PA |
1165 | |
1166 | /* | |
1167 | * If we have architectural seed generator, produce a seed and | |
48d6be95 TT |
1168 | * add it to the pool. For the sake of paranoia don't let the |
1169 | * architectural seed generator dominate the input from the | |
1170 | * interrupt noise. | |
83664a69 PA |
1171 | */ |
1172 | if (arch_get_random_seed_long(&seed)) { | |
85608f8e | 1173 | __mix_pool_bytes(r, &seed, sizeof(seed)); |
48d6be95 | 1174 | credit = 1; |
83664a69 | 1175 | } |
91fcb532 | 1176 | spin_unlock(&r->lock); |
83664a69 | 1177 | |
ee3e00e9 | 1178 | fast_pool->count = 0; |
83664a69 | 1179 | |
ee3e00e9 TT |
1180 | /* award one bit for the contents of the fast pool */ |
1181 | credit_entropy_bits(r, credit + 1); | |
1da177e4 | 1182 | } |
4b44f2d1 | 1183 | EXPORT_SYMBOL_GPL(add_interrupt_randomness); |
1da177e4 | 1184 | |
9361401e | 1185 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1186 | void add_disk_randomness(struct gendisk *disk) |
1187 | { | |
1188 | if (!disk || !disk->random) | |
1189 | return; | |
1190 | /* first major is 1, so we get >= 0x200 here */ | |
f331c029 | 1191 | add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); |
f80bbd8b | 1192 | trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS(&input_pool)); |
1da177e4 | 1193 | } |
bdcfa3e5 | 1194 | EXPORT_SYMBOL_GPL(add_disk_randomness); |
9361401e | 1195 | #endif |
1da177e4 | 1196 | |
1da177e4 LT |
1197 | /********************************************************************* |
1198 | * | |
1199 | * Entropy extraction routines | |
1200 | * | |
1201 | *********************************************************************/ | |
1202 | ||
1da177e4 | 1203 | /* |
25985edc | 1204 | * This utility inline function is responsible for transferring entropy |
1da177e4 LT |
1205 | * from the primary pool to the secondary extraction pool. We make |
1206 | * sure we pull enough for a 'catastrophic reseed'. | |
1207 | */ | |
6265e169 | 1208 | static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes); |
1da177e4 LT |
1209 | static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes) |
1210 | { | |
cff85031 TT |
1211 | if (!r->pull || |
1212 | r->entropy_count >= (nbytes << (ENTROPY_SHIFT + 3)) || | |
1213 | r->entropy_count > r->poolinfo->poolfracbits) | |
1214 | return; | |
1215 | ||
cff85031 | 1216 | _xfer_secondary_pool(r, nbytes); |
6265e169 TT |
1217 | } |
1218 | ||
1219 | static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes) | |
1220 | { | |
1221 | __u32 tmp[OUTPUT_POOL_WORDS]; | |
1222 | ||
6265e169 TT |
1223 | int bytes = nbytes; |
1224 | ||
2132a96f GP |
1225 | /* pull at least as much as a wakeup */ |
1226 | bytes = max_t(int, bytes, random_read_wakeup_bits / 8); | |
6265e169 TT |
1227 | /* but never more than the buffer size */ |
1228 | bytes = min_t(int, bytes, sizeof(tmp)); | |
1229 | ||
f80bbd8b TT |
1230 | trace_xfer_secondary_pool(r->name, bytes * 8, nbytes * 8, |
1231 | ENTROPY_BITS(r), ENTROPY_BITS(r->pull)); | |
6265e169 | 1232 | bytes = extract_entropy(r->pull, tmp, bytes, |
43d8a72c | 1233 | random_read_wakeup_bits / 8, 0); |
85608f8e | 1234 | mix_pool_bytes(r, tmp, bytes); |
6265e169 TT |
1235 | credit_entropy_bits(r, bytes*8); |
1236 | } | |
1237 | ||
1238 | /* | |
1239 | * Used as a workqueue function so that when the input pool is getting | |
1240 | * full, we can "spill over" some entropy to the output pools. That | |
1241 | * way the output pools can store some of the excess entropy instead | |
1242 | * of letting it go to waste. | |
1243 | */ | |
1244 | static void push_to_pool(struct work_struct *work) | |
1245 | { | |
1246 | struct entropy_store *r = container_of(work, struct entropy_store, | |
1247 | push_work); | |
1248 | BUG_ON(!r); | |
2132a96f | 1249 | _xfer_secondary_pool(r, random_read_wakeup_bits/8); |
6265e169 TT |
1250 | trace_push_to_pool(r->name, r->entropy_count >> ENTROPY_SHIFT, |
1251 | r->pull->entropy_count >> ENTROPY_SHIFT); | |
1da177e4 LT |
1252 | } |
1253 | ||
1254 | /* | |
19fa5be1 GP |
1255 | * This function decides how many bytes to actually take from the |
1256 | * given pool, and also debits the entropy count accordingly. | |
1da177e4 | 1257 | */ |
1da177e4 LT |
1258 | static size_t account(struct entropy_store *r, size_t nbytes, int min, |
1259 | int reserved) | |
1260 | { | |
43d8a72c | 1261 | int entropy_count, orig, have_bytes; |
79a84687 | 1262 | size_t ibytes, nfrac; |
1da177e4 | 1263 | |
a283b5c4 | 1264 | BUG_ON(r->entropy_count > r->poolinfo->poolfracbits); |
1da177e4 LT |
1265 | |
1266 | /* Can we pull enough? */ | |
10b3a32d | 1267 | retry: |
6aa7de05 | 1268 | entropy_count = orig = READ_ONCE(r->entropy_count); |
a283b5c4 | 1269 | ibytes = nbytes; |
43d8a72c SM |
1270 | /* never pull more than available */ |
1271 | have_bytes = entropy_count >> (ENTROPY_SHIFT + 3); | |
e33ba5fa | 1272 | |
43d8a72c SM |
1273 | if ((have_bytes -= reserved) < 0) |
1274 | have_bytes = 0; | |
1275 | ibytes = min_t(size_t, ibytes, have_bytes); | |
0fb7a01a | 1276 | if (ibytes < min) |
a283b5c4 | 1277 | ibytes = 0; |
79a84687 HFS |
1278 | |
1279 | if (unlikely(entropy_count < 0)) { | |
1280 | pr_warn("random: negative entropy count: pool %s count %d\n", | |
1281 | r->name, entropy_count); | |
1282 | WARN_ON(1); | |
1283 | entropy_count = 0; | |
1284 | } | |
1285 | nfrac = ibytes << (ENTROPY_SHIFT + 3); | |
1286 | if ((size_t) entropy_count > nfrac) | |
1287 | entropy_count -= nfrac; | |
1288 | else | |
e33ba5fa | 1289 | entropy_count = 0; |
f9c6d498 | 1290 | |
0fb7a01a GP |
1291 | if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) |
1292 | goto retry; | |
1da177e4 | 1293 | |
f80bbd8b | 1294 | trace_debit_entropy(r->name, 8 * ibytes); |
0fb7a01a | 1295 | if (ibytes && |
2132a96f | 1296 | (r->entropy_count >> ENTROPY_SHIFT) < random_write_wakeup_bits) { |
b9809552 TT |
1297 | wake_up_interruptible(&random_write_wait); |
1298 | kill_fasync(&fasync, SIGIO, POLL_OUT); | |
1299 | } | |
1300 | ||
a283b5c4 | 1301 | return ibytes; |
1da177e4 LT |
1302 | } |
1303 | ||
19fa5be1 GP |
1304 | /* |
1305 | * This function does the actual extraction for extract_entropy and | |
1306 | * extract_entropy_user. | |
1307 | * | |
1308 | * Note: we assume that .poolwords is a multiple of 16 words. | |
1309 | */ | |
1da177e4 LT |
1310 | static void extract_buf(struct entropy_store *r, __u8 *out) |
1311 | { | |
602b6aee | 1312 | int i; |
d2e7c96a PA |
1313 | union { |
1314 | __u32 w[5]; | |
85a1f777 | 1315 | unsigned long l[LONGS(20)]; |
d2e7c96a PA |
1316 | } hash; |
1317 | __u32 workspace[SHA_WORKSPACE_WORDS]; | |
902c098a | 1318 | unsigned long flags; |
1da177e4 | 1319 | |
85a1f777 | 1320 | /* |
dfd38750 | 1321 | * If we have an architectural hardware random number |
46884442 | 1322 | * generator, use it for SHA's initial vector |
85a1f777 | 1323 | */ |
46884442 | 1324 | sha_init(hash.w); |
85a1f777 TT |
1325 | for (i = 0; i < LONGS(20); i++) { |
1326 | unsigned long v; | |
1327 | if (!arch_get_random_long(&v)) | |
1328 | break; | |
46884442 | 1329 | hash.l[i] = v; |
85a1f777 TT |
1330 | } |
1331 | ||
46884442 TT |
1332 | /* Generate a hash across the pool, 16 words (512 bits) at a time */ |
1333 | spin_lock_irqsave(&r->lock, flags); | |
1334 | for (i = 0; i < r->poolinfo->poolwords; i += 16) | |
1335 | sha_transform(hash.w, (__u8 *)(r->pool + i), workspace); | |
1336 | ||
1da177e4 | 1337 | /* |
1c0ad3d4 MM |
1338 | * We mix the hash back into the pool to prevent backtracking |
1339 | * attacks (where the attacker knows the state of the pool | |
1340 | * plus the current outputs, and attempts to find previous | |
1341 | * ouputs), unless the hash function can be inverted. By | |
1342 | * mixing at least a SHA1 worth of hash data back, we make | |
1343 | * brute-forcing the feedback as hard as brute-forcing the | |
1344 | * hash. | |
1da177e4 | 1345 | */ |
85608f8e | 1346 | __mix_pool_bytes(r, hash.w, sizeof(hash.w)); |
902c098a | 1347 | spin_unlock_irqrestore(&r->lock, flags); |
1da177e4 | 1348 | |
d4c5efdb | 1349 | memzero_explicit(workspace, sizeof(workspace)); |
1da177e4 LT |
1350 | |
1351 | /* | |
1c0ad3d4 MM |
1352 | * In case the hash function has some recognizable output |
1353 | * pattern, we fold it in half. Thus, we always feed back | |
1354 | * twice as much data as we output. | |
1da177e4 | 1355 | */ |
d2e7c96a PA |
1356 | hash.w[0] ^= hash.w[3]; |
1357 | hash.w[1] ^= hash.w[4]; | |
1358 | hash.w[2] ^= rol32(hash.w[2], 16); | |
1359 | ||
d2e7c96a | 1360 | memcpy(out, &hash, EXTRACT_SIZE); |
d4c5efdb | 1361 | memzero_explicit(&hash, sizeof(hash)); |
1da177e4 LT |
1362 | } |
1363 | ||
e192be9d TT |
1364 | static ssize_t _extract_entropy(struct entropy_store *r, void *buf, |
1365 | size_t nbytes, int fips) | |
1366 | { | |
1367 | ssize_t ret = 0, i; | |
1368 | __u8 tmp[EXTRACT_SIZE]; | |
1369 | unsigned long flags; | |
1370 | ||
1371 | while (nbytes) { | |
1372 | extract_buf(r, tmp); | |
1373 | ||
1374 | if (fips) { | |
1375 | spin_lock_irqsave(&r->lock, flags); | |
1376 | if (!memcmp(tmp, r->last_data, EXTRACT_SIZE)) | |
1377 | panic("Hardware RNG duplicated output!\n"); | |
1378 | memcpy(r->last_data, tmp, EXTRACT_SIZE); | |
1379 | spin_unlock_irqrestore(&r->lock, flags); | |
1380 | } | |
1381 | i = min_t(int, nbytes, EXTRACT_SIZE); | |
1382 | memcpy(buf, tmp, i); | |
1383 | nbytes -= i; | |
1384 | buf += i; | |
1385 | ret += i; | |
1386 | } | |
1387 | ||
1388 | /* Wipe data just returned from memory */ | |
1389 | memzero_explicit(tmp, sizeof(tmp)); | |
1390 | ||
1391 | return ret; | |
1392 | } | |
1393 | ||
19fa5be1 GP |
1394 | /* |
1395 | * This function extracts randomness from the "entropy pool", and | |
1396 | * returns it in a buffer. | |
1397 | * | |
1398 | * The min parameter specifies the minimum amount we can pull before | |
1399 | * failing to avoid races that defeat catastrophic reseeding while the | |
1400 | * reserved parameter indicates how much entropy we must leave in the | |
1401 | * pool after each pull to avoid starving other readers. | |
1402 | */ | |
90b75ee5 | 1403 | static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
902c098a | 1404 | size_t nbytes, int min, int reserved) |
1da177e4 | 1405 | { |
1da177e4 | 1406 | __u8 tmp[EXTRACT_SIZE]; |
1e7e2e05 | 1407 | unsigned long flags; |
1da177e4 | 1408 | |
ec8f02da | 1409 | /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */ |
1e7e2e05 JW |
1410 | if (fips_enabled) { |
1411 | spin_lock_irqsave(&r->lock, flags); | |
1412 | if (!r->last_data_init) { | |
c59974ae | 1413 | r->last_data_init = 1; |
1e7e2e05 JW |
1414 | spin_unlock_irqrestore(&r->lock, flags); |
1415 | trace_extract_entropy(r->name, EXTRACT_SIZE, | |
a283b5c4 | 1416 | ENTROPY_BITS(r), _RET_IP_); |
1e7e2e05 JW |
1417 | xfer_secondary_pool(r, EXTRACT_SIZE); |
1418 | extract_buf(r, tmp); | |
1419 | spin_lock_irqsave(&r->lock, flags); | |
1420 | memcpy(r->last_data, tmp, EXTRACT_SIZE); | |
1421 | } | |
1422 | spin_unlock_irqrestore(&r->lock, flags); | |
1423 | } | |
ec8f02da | 1424 | |
a283b5c4 | 1425 | trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_); |
1da177e4 LT |
1426 | xfer_secondary_pool(r, nbytes); |
1427 | nbytes = account(r, nbytes, min, reserved); | |
1428 | ||
e192be9d | 1429 | return _extract_entropy(r, buf, nbytes, fips_enabled); |
1da177e4 LT |
1430 | } |
1431 | ||
19fa5be1 GP |
1432 | /* |
1433 | * This function extracts randomness from the "entropy pool", and | |
1434 | * returns it in a userspace buffer. | |
1435 | */ | |
1da177e4 LT |
1436 | static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf, |
1437 | size_t nbytes) | |
1438 | { | |
1439 | ssize_t ret = 0, i; | |
1440 | __u8 tmp[EXTRACT_SIZE]; | |
c6e9d6f3 | 1441 | int large_request = (nbytes > 256); |
1da177e4 | 1442 | |
a283b5c4 | 1443 | trace_extract_entropy_user(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_); |
1da177e4 LT |
1444 | xfer_secondary_pool(r, nbytes); |
1445 | nbytes = account(r, nbytes, 0, 0); | |
1446 | ||
1447 | while (nbytes) { | |
c6e9d6f3 | 1448 | if (large_request && need_resched()) { |
1da177e4 LT |
1449 | if (signal_pending(current)) { |
1450 | if (ret == 0) | |
1451 | ret = -ERESTARTSYS; | |
1452 | break; | |
1453 | } | |
1454 | schedule(); | |
1455 | } | |
1456 | ||
1457 | extract_buf(r, tmp); | |
1458 | i = min_t(int, nbytes, EXTRACT_SIZE); | |
1459 | if (copy_to_user(buf, tmp, i)) { | |
1460 | ret = -EFAULT; | |
1461 | break; | |
1462 | } | |
1463 | ||
1464 | nbytes -= i; | |
1465 | buf += i; | |
1466 | ret += i; | |
1467 | } | |
1468 | ||
1469 | /* Wipe data just returned from memory */ | |
d4c5efdb | 1470 | memzero_explicit(tmp, sizeof(tmp)); |
1da177e4 LT |
1471 | |
1472 | return ret; | |
1473 | } | |
1474 | ||
eecabf56 TT |
1475 | #define warn_unseeded_randomness(previous) \ |
1476 | _warn_unseeded_randomness(__func__, (void *) _RET_IP_, (previous)) | |
1477 | ||
1478 | static void _warn_unseeded_randomness(const char *func_name, void *caller, | |
1479 | void **previous) | |
1480 | { | |
1481 | #ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM | |
1482 | const bool print_once = false; | |
1483 | #else | |
1484 | static bool print_once __read_mostly; | |
1485 | #endif | |
1486 | ||
1487 | if (print_once || | |
1488 | crng_ready() || | |
1489 | (previous && (caller == READ_ONCE(*previous)))) | |
1490 | return; | |
1491 | WRITE_ONCE(*previous, caller); | |
1492 | #ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM | |
1493 | print_once = true; | |
1494 | #endif | |
51d96dc2 | 1495 | pr_notice("random: %s called from %pS with crng_init=%d\n", |
eecabf56 TT |
1496 | func_name, caller, crng_init); |
1497 | } | |
1498 | ||
1da177e4 LT |
1499 | /* |
1500 | * This function is the exported kernel interface. It returns some | |
c2557a30 | 1501 | * number of good random numbers, suitable for key generation, seeding |
18e9cea7 GP |
1502 | * TCP sequence numbers, etc. It does not rely on the hardware random |
1503 | * number generator. For random bytes direct from the hardware RNG | |
e297a783 JD |
1504 | * (when available), use get_random_bytes_arch(). In order to ensure |
1505 | * that the randomness provided by this function is okay, the function | |
1506 | * wait_for_random_bytes() should be called and return 0 at least once | |
1507 | * at any point prior. | |
1da177e4 | 1508 | */ |
eecabf56 | 1509 | static void _get_random_bytes(void *buf, int nbytes) |
c2557a30 | 1510 | { |
9f480fae | 1511 | __u32 tmp[CHACHA20_BLOCK_WORDS]; |
e192be9d | 1512 | |
5910895f | 1513 | trace_get_random_bytes(nbytes, _RET_IP_); |
e192be9d TT |
1514 | |
1515 | while (nbytes >= CHACHA20_BLOCK_SIZE) { | |
1516 | extract_crng(buf); | |
1517 | buf += CHACHA20_BLOCK_SIZE; | |
1518 | nbytes -= CHACHA20_BLOCK_SIZE; | |
1519 | } | |
1520 | ||
1521 | if (nbytes > 0) { | |
1522 | extract_crng(tmp); | |
1523 | memcpy(buf, tmp, nbytes); | |
c92e040d TT |
1524 | crng_backtrack_protect(tmp, nbytes); |
1525 | } else | |
1526 | crng_backtrack_protect(tmp, CHACHA20_BLOCK_SIZE); | |
1527 | memzero_explicit(tmp, sizeof(tmp)); | |
c2557a30 | 1528 | } |
eecabf56 TT |
1529 | |
1530 | void get_random_bytes(void *buf, int nbytes) | |
1531 | { | |
1532 | static void *previous; | |
1533 | ||
1534 | warn_unseeded_randomness(&previous); | |
1535 | _get_random_bytes(buf, nbytes); | |
1536 | } | |
c2557a30 TT |
1537 | EXPORT_SYMBOL(get_random_bytes); |
1538 | ||
e297a783 JD |
1539 | /* |
1540 | * Wait for the urandom pool to be seeded and thus guaranteed to supply | |
1541 | * cryptographically secure random numbers. This applies to: the /dev/urandom | |
1542 | * device, the get_random_bytes function, and the get_random_{u32,u64,int,long} | |
1543 | * family of functions. Using any of these functions without first calling | |
1544 | * this function forfeits the guarantee of security. | |
1545 | * | |
1546 | * Returns: 0 if the urandom pool has been seeded. | |
1547 | * -ERESTARTSYS if the function was interrupted by a signal. | |
1548 | */ | |
1549 | int wait_for_random_bytes(void) | |
1550 | { | |
1551 | if (likely(crng_ready())) | |
1552 | return 0; | |
1553 | return wait_event_interruptible(crng_init_wait, crng_ready()); | |
1554 | } | |
1555 | EXPORT_SYMBOL(wait_for_random_bytes); | |
1556 | ||
205a525c HX |
1557 | /* |
1558 | * Add a callback function that will be invoked when the nonblocking | |
1559 | * pool is initialised. | |
1560 | * | |
1561 | * returns: 0 if callback is successfully added | |
1562 | * -EALREADY if pool is already initialised (callback not called) | |
1563 | * -ENOENT if module for callback is not alive | |
1564 | */ | |
1565 | int add_random_ready_callback(struct random_ready_callback *rdy) | |
1566 | { | |
1567 | struct module *owner; | |
1568 | unsigned long flags; | |
1569 | int err = -EALREADY; | |
1570 | ||
e192be9d | 1571 | if (crng_ready()) |
205a525c HX |
1572 | return err; |
1573 | ||
1574 | owner = rdy->owner; | |
1575 | if (!try_module_get(owner)) | |
1576 | return -ENOENT; | |
1577 | ||
1578 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
e192be9d | 1579 | if (crng_ready()) |
205a525c HX |
1580 | goto out; |
1581 | ||
1582 | owner = NULL; | |
1583 | ||
1584 | list_add(&rdy->list, &random_ready_list); | |
1585 | err = 0; | |
1586 | ||
1587 | out: | |
1588 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
1589 | ||
1590 | module_put(owner); | |
1591 | ||
1592 | return err; | |
1593 | } | |
1594 | EXPORT_SYMBOL(add_random_ready_callback); | |
1595 | ||
1596 | /* | |
1597 | * Delete a previously registered readiness callback function. | |
1598 | */ | |
1599 | void del_random_ready_callback(struct random_ready_callback *rdy) | |
1600 | { | |
1601 | unsigned long flags; | |
1602 | struct module *owner = NULL; | |
1603 | ||
1604 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
1605 | if (!list_empty(&rdy->list)) { | |
1606 | list_del_init(&rdy->list); | |
1607 | owner = rdy->owner; | |
1608 | } | |
1609 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
1610 | ||
1611 | module_put(owner); | |
1612 | } | |
1613 | EXPORT_SYMBOL(del_random_ready_callback); | |
1614 | ||
c2557a30 TT |
1615 | /* |
1616 | * This function will use the architecture-specific hardware random | |
1617 | * number generator if it is available. The arch-specific hw RNG will | |
1618 | * almost certainly be faster than what we can do in software, but it | |
1619 | * is impossible to verify that it is implemented securely (as | |
1620 | * opposed, to, say, the AES encryption of a sequence number using a | |
1621 | * key known by the NSA). So it's useful if we need the speed, but | |
1622 | * only if we're willing to trust the hardware manufacturer not to | |
1623 | * have put in a back door. | |
1624 | */ | |
1625 | void get_random_bytes_arch(void *buf, int nbytes) | |
1da177e4 | 1626 | { |
63d77173 PA |
1627 | char *p = buf; |
1628 | ||
5910895f | 1629 | trace_get_random_bytes_arch(nbytes, _RET_IP_); |
63d77173 PA |
1630 | while (nbytes) { |
1631 | unsigned long v; | |
1632 | int chunk = min(nbytes, (int)sizeof(unsigned long)); | |
c2557a30 | 1633 | |
63d77173 PA |
1634 | if (!arch_get_random_long(&v)) |
1635 | break; | |
1636 | ||
bd29e568 | 1637 | memcpy(p, &v, chunk); |
63d77173 PA |
1638 | p += chunk; |
1639 | nbytes -= chunk; | |
1640 | } | |
1641 | ||
c2557a30 | 1642 | if (nbytes) |
e192be9d | 1643 | get_random_bytes(p, nbytes); |
1da177e4 | 1644 | } |
c2557a30 TT |
1645 | EXPORT_SYMBOL(get_random_bytes_arch); |
1646 | ||
1da177e4 LT |
1647 | |
1648 | /* | |
1649 | * init_std_data - initialize pool with system data | |
1650 | * | |
1651 | * @r: pool to initialize | |
1652 | * | |
1653 | * This function clears the pool's entropy count and mixes some system | |
1654 | * data into the pool to prepare it for use. The pool is not cleared | |
1655 | * as that can only decrease the entropy in the pool. | |
1656 | */ | |
1657 | static void init_std_data(struct entropy_store *r) | |
1658 | { | |
3e88bdff | 1659 | int i; |
902c098a TT |
1660 | ktime_t now = ktime_get_real(); |
1661 | unsigned long rv; | |
1da177e4 | 1662 | |
f5c2742c | 1663 | r->last_pulled = jiffies; |
85608f8e | 1664 | mix_pool_bytes(r, &now, sizeof(now)); |
9ed17b70 | 1665 | for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) { |
83664a69 PA |
1666 | if (!arch_get_random_seed_long(&rv) && |
1667 | !arch_get_random_long(&rv)) | |
ae9ecd92 | 1668 | rv = random_get_entropy(); |
85608f8e | 1669 | mix_pool_bytes(r, &rv, sizeof(rv)); |
3e88bdff | 1670 | } |
85608f8e | 1671 | mix_pool_bytes(r, utsname(), sizeof(*(utsname()))); |
1da177e4 LT |
1672 | } |
1673 | ||
cbc96b75 TL |
1674 | /* |
1675 | * Note that setup_arch() may call add_device_randomness() | |
1676 | * long before we get here. This allows seeding of the pools | |
1677 | * with some platform dependent data very early in the boot | |
1678 | * process. But it limits our options here. We must use | |
1679 | * statically allocated structures that already have all | |
1680 | * initializations complete at compile time. We should also | |
1681 | * take care not to overwrite the precious per platform data | |
1682 | * we were given. | |
1683 | */ | |
53c3f63e | 1684 | static int rand_initialize(void) |
1da177e4 | 1685 | { |
1e7f583a TT |
1686 | #ifdef CONFIG_NUMA |
1687 | int i; | |
1e7f583a TT |
1688 | struct crng_state *crng; |
1689 | struct crng_state **pool; | |
1690 | #endif | |
1691 | ||
1da177e4 LT |
1692 | init_std_data(&input_pool); |
1693 | init_std_data(&blocking_pool); | |
e192be9d | 1694 | crng_initialize(&primary_crng); |
1e7f583a TT |
1695 | |
1696 | #ifdef CONFIG_NUMA | |
dd0f0cf5 | 1697 | pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL); |
59b8d4f1 | 1698 | for_each_online_node(i) { |
1e7f583a TT |
1699 | crng = kmalloc_node(sizeof(struct crng_state), |
1700 | GFP_KERNEL | __GFP_NOFAIL, i); | |
1701 | spin_lock_init(&crng->lock); | |
1702 | crng_initialize(crng); | |
1703 | pool[i] = crng; | |
1e7f583a TT |
1704 | } |
1705 | mb(); | |
1706 | crng_node_pool = pool; | |
1707 | #endif | |
1da177e4 LT |
1708 | return 0; |
1709 | } | |
ae9ecd92 | 1710 | early_initcall(rand_initialize); |
1da177e4 | 1711 | |
9361401e | 1712 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1713 | void rand_initialize_disk(struct gendisk *disk) |
1714 | { | |
1715 | struct timer_rand_state *state; | |
1716 | ||
1717 | /* | |
f8595815 | 1718 | * If kzalloc returns null, we just won't use that entropy |
1da177e4 LT |
1719 | * source. |
1720 | */ | |
f8595815 | 1721 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
644008df TT |
1722 | if (state) { |
1723 | state->last_time = INITIAL_JIFFIES; | |
1da177e4 | 1724 | disk->random = state; |
644008df | 1725 | } |
1da177e4 | 1726 | } |
9361401e | 1727 | #endif |
1da177e4 LT |
1728 | |
1729 | static ssize_t | |
c6e9d6f3 | 1730 | _random_read(int nonblock, char __user *buf, size_t nbytes) |
1da177e4 | 1731 | { |
12ff3a51 | 1732 | ssize_t n; |
1da177e4 LT |
1733 | |
1734 | if (nbytes == 0) | |
1735 | return 0; | |
1736 | ||
12ff3a51 GP |
1737 | nbytes = min_t(size_t, nbytes, SEC_XFER_SIZE); |
1738 | while (1) { | |
1739 | n = extract_entropy_user(&blocking_pool, buf, nbytes); | |
1740 | if (n < 0) | |
1741 | return n; | |
f80bbd8b TT |
1742 | trace_random_read(n*8, (nbytes-n)*8, |
1743 | ENTROPY_BITS(&blocking_pool), | |
1744 | ENTROPY_BITS(&input_pool)); | |
12ff3a51 GP |
1745 | if (n > 0) |
1746 | return n; | |
331c6490 | 1747 | |
12ff3a51 | 1748 | /* Pool is (near) empty. Maybe wait and retry. */ |
c6e9d6f3 | 1749 | if (nonblock) |
12ff3a51 GP |
1750 | return -EAGAIN; |
1751 | ||
1752 | wait_event_interruptible(random_read_wait, | |
1753 | ENTROPY_BITS(&input_pool) >= | |
2132a96f | 1754 | random_read_wakeup_bits); |
12ff3a51 GP |
1755 | if (signal_pending(current)) |
1756 | return -ERESTARTSYS; | |
1da177e4 | 1757 | } |
1da177e4 LT |
1758 | } |
1759 | ||
c6e9d6f3 TT |
1760 | static ssize_t |
1761 | random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) | |
1762 | { | |
1763 | return _random_read(file->f_flags & O_NONBLOCK, buf, nbytes); | |
1764 | } | |
1765 | ||
1da177e4 | 1766 | static ssize_t |
90b75ee5 | 1767 | urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
1da177e4 | 1768 | { |
e192be9d | 1769 | unsigned long flags; |
9b4d0087 | 1770 | static int maxwarn = 10; |
301f0595 TT |
1771 | int ret; |
1772 | ||
e192be9d | 1773 | if (!crng_ready() && maxwarn > 0) { |
9b4d0087 TT |
1774 | maxwarn--; |
1775 | printk(KERN_NOTICE "random: %s: uninitialized urandom read " | |
e192be9d TT |
1776 | "(%zd bytes read)\n", |
1777 | current->comm, nbytes); | |
1778 | spin_lock_irqsave(&primary_crng.lock, flags); | |
1779 | crng_init_cnt = 0; | |
1780 | spin_unlock_irqrestore(&primary_crng.lock, flags); | |
9b4d0087 | 1781 | } |
79a84687 | 1782 | nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3)); |
e192be9d TT |
1783 | ret = extract_crng_user(buf, nbytes); |
1784 | trace_urandom_read(8 * nbytes, 0, ENTROPY_BITS(&input_pool)); | |
f80bbd8b | 1785 | return ret; |
1da177e4 LT |
1786 | } |
1787 | ||
afc9a42b | 1788 | static __poll_t |
1da177e4 LT |
1789 | random_poll(struct file *file, poll_table * wait) |
1790 | { | |
afc9a42b | 1791 | __poll_t mask; |
1da177e4 LT |
1792 | |
1793 | poll_wait(file, &random_read_wait, wait); | |
1794 | poll_wait(file, &random_write_wait, wait); | |
1795 | mask = 0; | |
2132a96f | 1796 | if (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits) |
a9a08845 | 1797 | mask |= EPOLLIN | EPOLLRDNORM; |
2132a96f | 1798 | if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits) |
a9a08845 | 1799 | mask |= EPOLLOUT | EPOLLWRNORM; |
1da177e4 LT |
1800 | return mask; |
1801 | } | |
1802 | ||
7f397dcd MM |
1803 | static int |
1804 | write_pool(struct entropy_store *r, const char __user *buffer, size_t count) | |
1da177e4 | 1805 | { |
1da177e4 LT |
1806 | size_t bytes; |
1807 | __u32 buf[16]; | |
1808 | const char __user *p = buffer; | |
1da177e4 | 1809 | |
7f397dcd MM |
1810 | while (count > 0) { |
1811 | bytes = min(count, sizeof(buf)); | |
1812 | if (copy_from_user(&buf, p, bytes)) | |
1813 | return -EFAULT; | |
1da177e4 | 1814 | |
7f397dcd | 1815 | count -= bytes; |
1da177e4 LT |
1816 | p += bytes; |
1817 | ||
85608f8e | 1818 | mix_pool_bytes(r, buf, bytes); |
91f3f1e3 | 1819 | cond_resched(); |
1da177e4 | 1820 | } |
7f397dcd MM |
1821 | |
1822 | return 0; | |
1823 | } | |
1824 | ||
90b75ee5 MM |
1825 | static ssize_t random_write(struct file *file, const char __user *buffer, |
1826 | size_t count, loff_t *ppos) | |
7f397dcd MM |
1827 | { |
1828 | size_t ret; | |
7f397dcd | 1829 | |
e192be9d | 1830 | ret = write_pool(&input_pool, buffer, count); |
7f397dcd MM |
1831 | if (ret) |
1832 | return ret; | |
1833 | ||
7f397dcd | 1834 | return (ssize_t)count; |
1da177e4 LT |
1835 | } |
1836 | ||
43ae4860 | 1837 | static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) |
1da177e4 LT |
1838 | { |
1839 | int size, ent_count; | |
1840 | int __user *p = (int __user *)arg; | |
1841 | int retval; | |
1842 | ||
1843 | switch (cmd) { | |
1844 | case RNDGETENTCNT: | |
43ae4860 | 1845 | /* inherently racy, no point locking */ |
a283b5c4 PA |
1846 | ent_count = ENTROPY_BITS(&input_pool); |
1847 | if (put_user(ent_count, p)) | |
1da177e4 LT |
1848 | return -EFAULT; |
1849 | return 0; | |
1850 | case RNDADDTOENTCNT: | |
1851 | if (!capable(CAP_SYS_ADMIN)) | |
1852 | return -EPERM; | |
1853 | if (get_user(ent_count, p)) | |
1854 | return -EFAULT; | |
86a574de | 1855 | return credit_entropy_bits_safe(&input_pool, ent_count); |
1da177e4 LT |
1856 | case RNDADDENTROPY: |
1857 | if (!capable(CAP_SYS_ADMIN)) | |
1858 | return -EPERM; | |
1859 | if (get_user(ent_count, p++)) | |
1860 | return -EFAULT; | |
1861 | if (ent_count < 0) | |
1862 | return -EINVAL; | |
1863 | if (get_user(size, p++)) | |
1864 | return -EFAULT; | |
7f397dcd MM |
1865 | retval = write_pool(&input_pool, (const char __user *)p, |
1866 | size); | |
1da177e4 LT |
1867 | if (retval < 0) |
1868 | return retval; | |
86a574de | 1869 | return credit_entropy_bits_safe(&input_pool, ent_count); |
1da177e4 LT |
1870 | case RNDZAPENTCNT: |
1871 | case RNDCLEARPOOL: | |
ae9ecd92 TT |
1872 | /* |
1873 | * Clear the entropy pool counters. We no longer clear | |
1874 | * the entropy pool, as that's silly. | |
1875 | */ | |
1da177e4 LT |
1876 | if (!capable(CAP_SYS_ADMIN)) |
1877 | return -EPERM; | |
ae9ecd92 | 1878 | input_pool.entropy_count = 0; |
ae9ecd92 | 1879 | blocking_pool.entropy_count = 0; |
1da177e4 LT |
1880 | return 0; |
1881 | default: | |
1882 | return -EINVAL; | |
1883 | } | |
1884 | } | |
1885 | ||
9a6f70bb JD |
1886 | static int random_fasync(int fd, struct file *filp, int on) |
1887 | { | |
1888 | return fasync_helper(fd, filp, on, &fasync); | |
1889 | } | |
1890 | ||
2b8693c0 | 1891 | const struct file_operations random_fops = { |
1da177e4 LT |
1892 | .read = random_read, |
1893 | .write = random_write, | |
1894 | .poll = random_poll, | |
43ae4860 | 1895 | .unlocked_ioctl = random_ioctl, |
9a6f70bb | 1896 | .fasync = random_fasync, |
6038f373 | 1897 | .llseek = noop_llseek, |
1da177e4 LT |
1898 | }; |
1899 | ||
2b8693c0 | 1900 | const struct file_operations urandom_fops = { |
1da177e4 LT |
1901 | .read = urandom_read, |
1902 | .write = random_write, | |
43ae4860 | 1903 | .unlocked_ioctl = random_ioctl, |
9a6f70bb | 1904 | .fasync = random_fasync, |
6038f373 | 1905 | .llseek = noop_llseek, |
1da177e4 LT |
1906 | }; |
1907 | ||
c6e9d6f3 TT |
1908 | SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, |
1909 | unsigned int, flags) | |
1910 | { | |
e297a783 JD |
1911 | int ret; |
1912 | ||
c6e9d6f3 TT |
1913 | if (flags & ~(GRND_NONBLOCK|GRND_RANDOM)) |
1914 | return -EINVAL; | |
1915 | ||
1916 | if (count > INT_MAX) | |
1917 | count = INT_MAX; | |
1918 | ||
1919 | if (flags & GRND_RANDOM) | |
1920 | return _random_read(flags & GRND_NONBLOCK, buf, count); | |
1921 | ||
e192be9d | 1922 | if (!crng_ready()) { |
c6e9d6f3 TT |
1923 | if (flags & GRND_NONBLOCK) |
1924 | return -EAGAIN; | |
e297a783 JD |
1925 | ret = wait_for_random_bytes(); |
1926 | if (unlikely(ret)) | |
1927 | return ret; | |
c6e9d6f3 TT |
1928 | } |
1929 | return urandom_read(NULL, buf, count, NULL); | |
1930 | } | |
1931 | ||
1da177e4 LT |
1932 | /******************************************************************** |
1933 | * | |
1934 | * Sysctl interface | |
1935 | * | |
1936 | ********************************************************************/ | |
1937 | ||
1938 | #ifdef CONFIG_SYSCTL | |
1939 | ||
1940 | #include <linux/sysctl.h> | |
1941 | ||
1942 | static int min_read_thresh = 8, min_write_thresh; | |
8c2aa339 | 1943 | static int max_read_thresh = OUTPUT_POOL_WORDS * 32; |
1da177e4 | 1944 | static int max_write_thresh = INPUT_POOL_WORDS * 32; |
db61ffe3 | 1945 | static int random_min_urandom_seed = 60; |
1da177e4 LT |
1946 | static char sysctl_bootid[16]; |
1947 | ||
1948 | /* | |
f22052b2 | 1949 | * This function is used to return both the bootid UUID, and random |
1da177e4 LT |
1950 | * UUID. The difference is in whether table->data is NULL; if it is, |
1951 | * then a new UUID is generated and returned to the user. | |
1952 | * | |
f22052b2 GP |
1953 | * If the user accesses this via the proc interface, the UUID will be |
1954 | * returned as an ASCII string in the standard UUID format; if via the | |
1955 | * sysctl system call, as 16 bytes of binary data. | |
1da177e4 | 1956 | */ |
a151427e | 1957 | static int proc_do_uuid(struct ctl_table *table, int write, |
1da177e4 LT |
1958 | void __user *buffer, size_t *lenp, loff_t *ppos) |
1959 | { | |
a151427e | 1960 | struct ctl_table fake_table; |
1da177e4 LT |
1961 | unsigned char buf[64], tmp_uuid[16], *uuid; |
1962 | ||
1963 | uuid = table->data; | |
1964 | if (!uuid) { | |
1965 | uuid = tmp_uuid; | |
1da177e4 | 1966 | generate_random_uuid(uuid); |
44e4360f MD |
1967 | } else { |
1968 | static DEFINE_SPINLOCK(bootid_spinlock); | |
1969 | ||
1970 | spin_lock(&bootid_spinlock); | |
1971 | if (!uuid[8]) | |
1972 | generate_random_uuid(uuid); | |
1973 | spin_unlock(&bootid_spinlock); | |
1974 | } | |
1da177e4 | 1975 | |
35900771 JP |
1976 | sprintf(buf, "%pU", uuid); |
1977 | ||
1da177e4 LT |
1978 | fake_table.data = buf; |
1979 | fake_table.maxlen = sizeof(buf); | |
1980 | ||
8d65af78 | 1981 | return proc_dostring(&fake_table, write, buffer, lenp, ppos); |
1da177e4 LT |
1982 | } |
1983 | ||
a283b5c4 PA |
1984 | /* |
1985 | * Return entropy available scaled to integral bits | |
1986 | */ | |
5eb10d91 | 1987 | static int proc_do_entropy(struct ctl_table *table, int write, |
a283b5c4 PA |
1988 | void __user *buffer, size_t *lenp, loff_t *ppos) |
1989 | { | |
5eb10d91 | 1990 | struct ctl_table fake_table; |
a283b5c4 PA |
1991 | int entropy_count; |
1992 | ||
1993 | entropy_count = *(int *)table->data >> ENTROPY_SHIFT; | |
1994 | ||
1995 | fake_table.data = &entropy_count; | |
1996 | fake_table.maxlen = sizeof(entropy_count); | |
1997 | ||
1998 | return proc_dointvec(&fake_table, write, buffer, lenp, ppos); | |
1999 | } | |
2000 | ||
1da177e4 | 2001 | static int sysctl_poolsize = INPUT_POOL_WORDS * 32; |
a151427e JP |
2002 | extern struct ctl_table random_table[]; |
2003 | struct ctl_table random_table[] = { | |
1da177e4 | 2004 | { |
1da177e4 LT |
2005 | .procname = "poolsize", |
2006 | .data = &sysctl_poolsize, | |
2007 | .maxlen = sizeof(int), | |
2008 | .mode = 0444, | |
6d456111 | 2009 | .proc_handler = proc_dointvec, |
1da177e4 LT |
2010 | }, |
2011 | { | |
1da177e4 LT |
2012 | .procname = "entropy_avail", |
2013 | .maxlen = sizeof(int), | |
2014 | .mode = 0444, | |
a283b5c4 | 2015 | .proc_handler = proc_do_entropy, |
1da177e4 LT |
2016 | .data = &input_pool.entropy_count, |
2017 | }, | |
2018 | { | |
1da177e4 | 2019 | .procname = "read_wakeup_threshold", |
2132a96f | 2020 | .data = &random_read_wakeup_bits, |
1da177e4 LT |
2021 | .maxlen = sizeof(int), |
2022 | .mode = 0644, | |
6d456111 | 2023 | .proc_handler = proc_dointvec_minmax, |
1da177e4 LT |
2024 | .extra1 = &min_read_thresh, |
2025 | .extra2 = &max_read_thresh, | |
2026 | }, | |
2027 | { | |
1da177e4 | 2028 | .procname = "write_wakeup_threshold", |
2132a96f | 2029 | .data = &random_write_wakeup_bits, |
1da177e4 LT |
2030 | .maxlen = sizeof(int), |
2031 | .mode = 0644, | |
6d456111 | 2032 | .proc_handler = proc_dointvec_minmax, |
1da177e4 LT |
2033 | .extra1 = &min_write_thresh, |
2034 | .extra2 = &max_write_thresh, | |
2035 | }, | |
f5c2742c TT |
2036 | { |
2037 | .procname = "urandom_min_reseed_secs", | |
2038 | .data = &random_min_urandom_seed, | |
2039 | .maxlen = sizeof(int), | |
2040 | .mode = 0644, | |
2041 | .proc_handler = proc_dointvec, | |
2042 | }, | |
1da177e4 | 2043 | { |
1da177e4 LT |
2044 | .procname = "boot_id", |
2045 | .data = &sysctl_bootid, | |
2046 | .maxlen = 16, | |
2047 | .mode = 0444, | |
6d456111 | 2048 | .proc_handler = proc_do_uuid, |
1da177e4 LT |
2049 | }, |
2050 | { | |
1da177e4 LT |
2051 | .procname = "uuid", |
2052 | .maxlen = 16, | |
2053 | .mode = 0444, | |
6d456111 | 2054 | .proc_handler = proc_do_uuid, |
1da177e4 | 2055 | }, |
43759d4f TT |
2056 | #ifdef ADD_INTERRUPT_BENCH |
2057 | { | |
2058 | .procname = "add_interrupt_avg_cycles", | |
2059 | .data = &avg_cycles, | |
2060 | .maxlen = sizeof(avg_cycles), | |
2061 | .mode = 0444, | |
2062 | .proc_handler = proc_doulongvec_minmax, | |
2063 | }, | |
2064 | { | |
2065 | .procname = "add_interrupt_avg_deviation", | |
2066 | .data = &avg_deviation, | |
2067 | .maxlen = sizeof(avg_deviation), | |
2068 | .mode = 0444, | |
2069 | .proc_handler = proc_doulongvec_minmax, | |
2070 | }, | |
2071 | #endif | |
894d2491 | 2072 | { } |
1da177e4 LT |
2073 | }; |
2074 | #endif /* CONFIG_SYSCTL */ | |
2075 | ||
f5b98461 JD |
2076 | struct batched_entropy { |
2077 | union { | |
c440408c JD |
2078 | u64 entropy_u64[CHACHA20_BLOCK_SIZE / sizeof(u64)]; |
2079 | u32 entropy_u32[CHACHA20_BLOCK_SIZE / sizeof(u32)]; | |
f5b98461 JD |
2080 | }; |
2081 | unsigned int position; | |
2082 | }; | |
b169c13d | 2083 | static rwlock_t batched_entropy_reset_lock = __RW_LOCK_UNLOCKED(batched_entropy_reset_lock); |
b1132dea | 2084 | |
1da177e4 | 2085 | /* |
f5b98461 JD |
2086 | * Get a random word for internal kernel use only. The quality of the random |
2087 | * number is either as good as RDRAND or as good as /dev/urandom, with the | |
e297a783 JD |
2088 | * goal of being quite fast and not depleting entropy. In order to ensure |
2089 | * that the randomness provided by this function is okay, the function | |
2090 | * wait_for_random_bytes() should be called and return 0 at least once | |
2091 | * at any point prior. | |
1da177e4 | 2092 | */ |
c440408c JD |
2093 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64); |
2094 | u64 get_random_u64(void) | |
1da177e4 | 2095 | { |
c440408c | 2096 | u64 ret; |
72e5c740 | 2097 | bool use_lock; |
4a072c71 | 2098 | unsigned long flags = 0; |
f5b98461 | 2099 | struct batched_entropy *batch; |
eecabf56 | 2100 | static void *previous; |
8a0a9bd4 | 2101 | |
c440408c JD |
2102 | #if BITS_PER_LONG == 64 |
2103 | if (arch_get_random_long((unsigned long *)&ret)) | |
63d77173 | 2104 | return ret; |
c440408c JD |
2105 | #else |
2106 | if (arch_get_random_long((unsigned long *)&ret) && | |
2107 | arch_get_random_long((unsigned long *)&ret + 1)) | |
2108 | return ret; | |
2109 | #endif | |
63d77173 | 2110 | |
eecabf56 | 2111 | warn_unseeded_randomness(&previous); |
d06bfd19 | 2112 | |
72e5c740 | 2113 | use_lock = READ_ONCE(crng_init) < 2; |
c440408c | 2114 | batch = &get_cpu_var(batched_entropy_u64); |
b169c13d JD |
2115 | if (use_lock) |
2116 | read_lock_irqsave(&batched_entropy_reset_lock, flags); | |
c440408c | 2117 | if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) { |
9f480fae | 2118 | extract_crng((__u32 *)batch->entropy_u64); |
f5b98461 JD |
2119 | batch->position = 0; |
2120 | } | |
c440408c | 2121 | ret = batch->entropy_u64[batch->position++]; |
b169c13d JD |
2122 | if (use_lock) |
2123 | read_unlock_irqrestore(&batched_entropy_reset_lock, flags); | |
c440408c | 2124 | put_cpu_var(batched_entropy_u64); |
8a0a9bd4 | 2125 | return ret; |
1da177e4 | 2126 | } |
c440408c | 2127 | EXPORT_SYMBOL(get_random_u64); |
1da177e4 | 2128 | |
c440408c JD |
2129 | static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32); |
2130 | u32 get_random_u32(void) | |
f5b98461 | 2131 | { |
c440408c | 2132 | u32 ret; |
72e5c740 | 2133 | bool use_lock; |
4a072c71 | 2134 | unsigned long flags = 0; |
f5b98461 | 2135 | struct batched_entropy *batch; |
eecabf56 | 2136 | static void *previous; |
ec9ee4ac | 2137 | |
f5b98461 | 2138 | if (arch_get_random_int(&ret)) |
ec9ee4ac DC |
2139 | return ret; |
2140 | ||
eecabf56 | 2141 | warn_unseeded_randomness(&previous); |
d06bfd19 | 2142 | |
72e5c740 | 2143 | use_lock = READ_ONCE(crng_init) < 2; |
c440408c | 2144 | batch = &get_cpu_var(batched_entropy_u32); |
b169c13d JD |
2145 | if (use_lock) |
2146 | read_lock_irqsave(&batched_entropy_reset_lock, flags); | |
c440408c | 2147 | if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) { |
9f480fae | 2148 | extract_crng(batch->entropy_u32); |
f5b98461 JD |
2149 | batch->position = 0; |
2150 | } | |
c440408c | 2151 | ret = batch->entropy_u32[batch->position++]; |
b169c13d JD |
2152 | if (use_lock) |
2153 | read_unlock_irqrestore(&batched_entropy_reset_lock, flags); | |
c440408c | 2154 | put_cpu_var(batched_entropy_u32); |
ec9ee4ac DC |
2155 | return ret; |
2156 | } | |
c440408c | 2157 | EXPORT_SYMBOL(get_random_u32); |
ec9ee4ac | 2158 | |
b169c13d JD |
2159 | /* It's important to invalidate all potential batched entropy that might |
2160 | * be stored before the crng is initialized, which we can do lazily by | |
2161 | * simply resetting the counter to zero so that it's re-extracted on the | |
2162 | * next usage. */ | |
2163 | static void invalidate_batched_entropy(void) | |
2164 | { | |
2165 | int cpu; | |
2166 | unsigned long flags; | |
2167 | ||
2168 | write_lock_irqsave(&batched_entropy_reset_lock, flags); | |
2169 | for_each_possible_cpu (cpu) { | |
2170 | per_cpu_ptr(&batched_entropy_u32, cpu)->position = 0; | |
2171 | per_cpu_ptr(&batched_entropy_u64, cpu)->position = 0; | |
2172 | } | |
2173 | write_unlock_irqrestore(&batched_entropy_reset_lock, flags); | |
2174 | } | |
2175 | ||
99fdafde JC |
2176 | /** |
2177 | * randomize_page - Generate a random, page aligned address | |
2178 | * @start: The smallest acceptable address the caller will take. | |
2179 | * @range: The size of the area, starting at @start, within which the | |
2180 | * random address must fall. | |
2181 | * | |
2182 | * If @start + @range would overflow, @range is capped. | |
2183 | * | |
2184 | * NOTE: Historical use of randomize_range, which this replaces, presumed that | |
2185 | * @start was already page aligned. We now align it regardless. | |
2186 | * | |
2187 | * Return: A page aligned address within [start, start + range). On error, | |
2188 | * @start is returned. | |
2189 | */ | |
2190 | unsigned long | |
2191 | randomize_page(unsigned long start, unsigned long range) | |
2192 | { | |
2193 | if (!PAGE_ALIGNED(start)) { | |
2194 | range -= PAGE_ALIGN(start) - start; | |
2195 | start = PAGE_ALIGN(start); | |
2196 | } | |
2197 | ||
2198 | if (start > ULONG_MAX - range) | |
2199 | range = ULONG_MAX - start; | |
2200 | ||
2201 | range >>= PAGE_SHIFT; | |
2202 | ||
2203 | if (range == 0) | |
2204 | return start; | |
2205 | ||
2206 | return start + (get_random_long() % range << PAGE_SHIFT); | |
2207 | } | |
2208 | ||
c84dbf61 TD |
2209 | /* Interface for in-kernel drivers of true hardware RNGs. |
2210 | * Those devices may produce endless random bits and will be throttled | |
2211 | * when our pool is full. | |
2212 | */ | |
2213 | void add_hwgenerator_randomness(const char *buffer, size_t count, | |
2214 | size_t entropy) | |
2215 | { | |
2216 | struct entropy_store *poolp = &input_pool; | |
2217 | ||
e192be9d TT |
2218 | if (!crng_ready()) { |
2219 | crng_fast_load(buffer, count); | |
2220 | return; | |
3371f3da | 2221 | } |
e192be9d TT |
2222 | |
2223 | /* Suspend writing if we're above the trickle threshold. | |
2224 | * We'll be woken up again once below random_write_wakeup_thresh, | |
2225 | * or when the calling thread is about to terminate. | |
2226 | */ | |
2227 | wait_event_interruptible(random_write_wait, kthread_should_stop() || | |
2228 | ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits); | |
c84dbf61 TD |
2229 | mix_pool_bytes(poolp, buffer, count); |
2230 | credit_entropy_bits(poolp, entropy); | |
2231 | } | |
2232 | EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); |