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1da177e4 LT |
1 | /* |
2 | * random.c -- A strong random number generator | |
3 | * | |
9e95ce27 | 4 | * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005 |
1da177e4 LT |
5 | * |
6 | * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All | |
7 | * rights reserved. | |
8 | * | |
9 | * Redistribution and use in source and binary forms, with or without | |
10 | * modification, are permitted provided that the following conditions | |
11 | * are met: | |
12 | * 1. Redistributions of source code must retain the above copyright | |
13 | * notice, and the entire permission notice in its entirety, | |
14 | * including the disclaimer of warranties. | |
15 | * 2. Redistributions in binary form must reproduce the above copyright | |
16 | * notice, this list of conditions and the following disclaimer in the | |
17 | * documentation and/or other materials provided with the distribution. | |
18 | * 3. The name of the author may not be used to endorse or promote | |
19 | * products derived from this software without specific prior | |
20 | * written permission. | |
21 | * | |
22 | * ALTERNATIVELY, this product may be distributed under the terms of | |
23 | * the GNU General Public License, in which case the provisions of the GPL are | |
24 | * required INSTEAD OF the above restrictions. (This clause is | |
25 | * necessary due to a potential bad interaction between the GPL and | |
26 | * the restrictions contained in a BSD-style copyright.) | |
27 | * | |
28 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED | |
29 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
30 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF | |
31 | * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE | |
32 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | |
33 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT | |
34 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR | |
35 | * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF | |
36 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
37 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE | |
38 | * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH | |
39 | * DAMAGE. | |
40 | */ | |
41 | ||
42 | /* | |
43 | * (now, with legal B.S. out of the way.....) | |
44 | * | |
45 | * This routine gathers environmental noise from device drivers, etc., | |
46 | * and returns good random numbers, suitable for cryptographic use. | |
47 | * Besides the obvious cryptographic uses, these numbers are also good | |
48 | * for seeding TCP sequence numbers, and other places where it is | |
49 | * desirable to have numbers which are not only random, but hard to | |
50 | * predict by an attacker. | |
51 | * | |
52 | * Theory of operation | |
53 | * =================== | |
54 | * | |
55 | * Computers are very predictable devices. Hence it is extremely hard | |
56 | * to produce truly random numbers on a computer --- as opposed to | |
57 | * pseudo-random numbers, which can easily generated by using a | |
58 | * algorithm. Unfortunately, it is very easy for attackers to guess | |
59 | * the sequence of pseudo-random number generators, and for some | |
60 | * applications this is not acceptable. So instead, we must try to | |
61 | * gather "environmental noise" from the computer's environment, which | |
62 | * must be hard for outside attackers to observe, and use that to | |
63 | * generate random numbers. In a Unix environment, this is best done | |
64 | * from inside the kernel. | |
65 | * | |
66 | * Sources of randomness from the environment include inter-keyboard | |
67 | * timings, inter-interrupt timings from some interrupts, and other | |
68 | * events which are both (a) non-deterministic and (b) hard for an | |
69 | * outside observer to measure. Randomness from these sources are | |
70 | * added to an "entropy pool", which is mixed using a CRC-like function. | |
71 | * This is not cryptographically strong, but it is adequate assuming | |
72 | * the randomness is not chosen maliciously, and it is fast enough that | |
73 | * the overhead of doing it on every interrupt is very reasonable. | |
74 | * As random bytes are mixed into the entropy pool, the routines keep | |
75 | * an *estimate* of how many bits of randomness have been stored into | |
76 | * the random number generator's internal state. | |
77 | * | |
78 | * When random bytes are desired, they are obtained by taking the SHA | |
79 | * hash of the contents of the "entropy pool". The SHA hash avoids | |
80 | * exposing the internal state of the entropy pool. It is believed to | |
81 | * be computationally infeasible to derive any useful information | |
82 | * about the input of SHA from its output. Even if it is possible to | |
83 | * analyze SHA in some clever way, as long as the amount of data | |
84 | * returned from the generator is less than the inherent entropy in | |
85 | * the pool, the output data is totally unpredictable. For this | |
86 | * reason, the routine decreases its internal estimate of how many | |
87 | * bits of "true randomness" are contained in the entropy pool as it | |
88 | * outputs random numbers. | |
89 | * | |
90 | * If this estimate goes to zero, the routine can still generate | |
91 | * random numbers; however, an attacker may (at least in theory) be | |
92 | * able to infer the future output of the generator from prior | |
93 | * outputs. This requires successful cryptanalysis of SHA, which is | |
94 | * not believed to be feasible, but there is a remote possibility. | |
95 | * Nonetheless, these numbers should be useful for the vast majority | |
96 | * of purposes. | |
97 | * | |
98 | * Exported interfaces ---- output | |
99 | * =============================== | |
100 | * | |
101 | * There are three exported interfaces; the first is one designed to | |
102 | * be used from within the kernel: | |
103 | * | |
104 | * void get_random_bytes(void *buf, int nbytes); | |
105 | * | |
106 | * This interface will return the requested number of random bytes, | |
107 | * and place it in the requested buffer. | |
108 | * | |
109 | * The two other interfaces are two character devices /dev/random and | |
110 | * /dev/urandom. /dev/random is suitable for use when very high | |
111 | * quality randomness is desired (for example, for key generation or | |
112 | * one-time pads), as it will only return a maximum of the number of | |
113 | * bits of randomness (as estimated by the random number generator) | |
114 | * contained in the entropy pool. | |
115 | * | |
116 | * The /dev/urandom device does not have this limit, and will return | |
117 | * as many bytes as are requested. As more and more random bytes are | |
118 | * requested without giving time for the entropy pool to recharge, | |
119 | * this will result in random numbers that are merely cryptographically | |
120 | * strong. For many applications, however, this is acceptable. | |
121 | * | |
122 | * Exported interfaces ---- input | |
123 | * ============================== | |
124 | * | |
125 | * The current exported interfaces for gathering environmental noise | |
126 | * from the devices are: | |
127 | * | |
a2080a67 | 128 | * void add_device_randomness(const void *buf, unsigned int size); |
1da177e4 LT |
129 | * void add_input_randomness(unsigned int type, unsigned int code, |
130 | * unsigned int value); | |
775f4b29 | 131 | * void add_interrupt_randomness(int irq, int irq_flags); |
442a4fff | 132 | * void add_disk_randomness(struct gendisk *disk); |
1da177e4 | 133 | * |
a2080a67 LT |
134 | * add_device_randomness() is for adding data to the random pool that |
135 | * is likely to differ between two devices (or possibly even per boot). | |
136 | * This would be things like MAC addresses or serial numbers, or the | |
137 | * read-out of the RTC. This does *not* add any actual entropy to the | |
138 | * pool, but it initializes the pool to different values for devices | |
139 | * that might otherwise be identical and have very little entropy | |
140 | * available to them (particularly common in the embedded world). | |
141 | * | |
1da177e4 LT |
142 | * add_input_randomness() uses the input layer interrupt timing, as well as |
143 | * the event type information from the hardware. | |
144 | * | |
775f4b29 TT |
145 | * add_interrupt_randomness() uses the interrupt timing as random |
146 | * inputs to the entropy pool. Using the cycle counters and the irq source | |
147 | * as inputs, it feeds the randomness roughly once a second. | |
442a4fff JW |
148 | * |
149 | * add_disk_randomness() uses what amounts to the seek time of block | |
150 | * layer request events, on a per-disk_devt basis, as input to the | |
151 | * entropy pool. Note that high-speed solid state drives with very low | |
152 | * seek times do not make for good sources of entropy, as their seek | |
153 | * times are usually fairly consistent. | |
1da177e4 LT |
154 | * |
155 | * All of these routines try to estimate how many bits of randomness a | |
156 | * particular randomness source. They do this by keeping track of the | |
157 | * first and second order deltas of the event timings. | |
158 | * | |
159 | * Ensuring unpredictability at system startup | |
160 | * ============================================ | |
161 | * | |
162 | * When any operating system starts up, it will go through a sequence | |
163 | * of actions that are fairly predictable by an adversary, especially | |
164 | * if the start-up does not involve interaction with a human operator. | |
165 | * This reduces the actual number of bits of unpredictability in the | |
166 | * entropy pool below the value in entropy_count. In order to | |
167 | * counteract this effect, it helps to carry information in the | |
168 | * entropy pool across shut-downs and start-ups. To do this, put the | |
169 | * following lines an appropriate script which is run during the boot | |
170 | * sequence: | |
171 | * | |
172 | * echo "Initializing random number generator..." | |
173 | * random_seed=/var/run/random-seed | |
174 | * # Carry a random seed from start-up to start-up | |
175 | * # Load and then save the whole entropy pool | |
176 | * if [ -f $random_seed ]; then | |
177 | * cat $random_seed >/dev/urandom | |
178 | * else | |
179 | * touch $random_seed | |
180 | * fi | |
181 | * chmod 600 $random_seed | |
182 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 | |
183 | * | |
184 | * and the following lines in an appropriate script which is run as | |
185 | * the system is shutdown: | |
186 | * | |
187 | * # Carry a random seed from shut-down to start-up | |
188 | * # Save the whole entropy pool | |
189 | * echo "Saving random seed..." | |
190 | * random_seed=/var/run/random-seed | |
191 | * touch $random_seed | |
192 | * chmod 600 $random_seed | |
193 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 | |
194 | * | |
195 | * For example, on most modern systems using the System V init | |
196 | * scripts, such code fragments would be found in | |
197 | * /etc/rc.d/init.d/random. On older Linux systems, the correct script | |
198 | * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0. | |
199 | * | |
200 | * Effectively, these commands cause the contents of the entropy pool | |
201 | * to be saved at shut-down time and reloaded into the entropy pool at | |
202 | * start-up. (The 'dd' in the addition to the bootup script is to | |
203 | * make sure that /etc/random-seed is different for every start-up, | |
204 | * even if the system crashes without executing rc.0.) Even with | |
205 | * complete knowledge of the start-up activities, predicting the state | |
206 | * of the entropy pool requires knowledge of the previous history of | |
207 | * the system. | |
208 | * | |
209 | * Configuring the /dev/random driver under Linux | |
210 | * ============================================== | |
211 | * | |
212 | * The /dev/random driver under Linux uses minor numbers 8 and 9 of | |
213 | * the /dev/mem major number (#1). So if your system does not have | |
214 | * /dev/random and /dev/urandom created already, they can be created | |
215 | * by using the commands: | |
216 | * | |
217 | * mknod /dev/random c 1 8 | |
218 | * mknod /dev/urandom c 1 9 | |
219 | * | |
220 | * Acknowledgements: | |
221 | * ================= | |
222 | * | |
223 | * Ideas for constructing this random number generator were derived | |
224 | * from Pretty Good Privacy's random number generator, and from private | |
225 | * discussions with Phil Karn. Colin Plumb provided a faster random | |
226 | * number generator, which speed up the mixing function of the entropy | |
227 | * pool, taken from PGPfone. Dale Worley has also contributed many | |
228 | * useful ideas and suggestions to improve this driver. | |
229 | * | |
230 | * Any flaws in the design are solely my responsibility, and should | |
231 | * not be attributed to the Phil, Colin, or any of authors of PGP. | |
232 | * | |
233 | * Further background information on this topic may be obtained from | |
234 | * RFC 1750, "Randomness Recommendations for Security", by Donald | |
235 | * Eastlake, Steve Crocker, and Jeff Schiller. | |
236 | */ | |
237 | ||
238 | #include <linux/utsname.h> | |
1da177e4 LT |
239 | #include <linux/module.h> |
240 | #include <linux/kernel.h> | |
241 | #include <linux/major.h> | |
242 | #include <linux/string.h> | |
243 | #include <linux/fcntl.h> | |
244 | #include <linux/slab.h> | |
245 | #include <linux/random.h> | |
246 | #include <linux/poll.h> | |
247 | #include <linux/init.h> | |
248 | #include <linux/fs.h> | |
249 | #include <linux/genhd.h> | |
250 | #include <linux/interrupt.h> | |
27ac792c | 251 | #include <linux/mm.h> |
1da177e4 | 252 | #include <linux/spinlock.h> |
c84dbf61 | 253 | #include <linux/kthread.h> |
1da177e4 LT |
254 | #include <linux/percpu.h> |
255 | #include <linux/cryptohash.h> | |
5b739ef8 | 256 | #include <linux/fips.h> |
775f4b29 | 257 | #include <linux/ptrace.h> |
e6d4947b | 258 | #include <linux/kmemcheck.h> |
6265e169 | 259 | #include <linux/workqueue.h> |
0244ad00 | 260 | #include <linux/irq.h> |
c6e9d6f3 TT |
261 | #include <linux/syscalls.h> |
262 | #include <linux/completion.h> | |
8da4b8c4 | 263 | #include <linux/uuid.h> |
e192be9d | 264 | #include <crypto/chacha20.h> |
d178a1eb | 265 | |
1da177e4 LT |
266 | #include <asm/processor.h> |
267 | #include <asm/uaccess.h> | |
268 | #include <asm/irq.h> | |
775f4b29 | 269 | #include <asm/irq_regs.h> |
1da177e4 LT |
270 | #include <asm/io.h> |
271 | ||
00ce1db1 TT |
272 | #define CREATE_TRACE_POINTS |
273 | #include <trace/events/random.h> | |
274 | ||
43759d4f TT |
275 | /* #define ADD_INTERRUPT_BENCH */ |
276 | ||
1da177e4 LT |
277 | /* |
278 | * Configuration information | |
279 | */ | |
30e37ec5 PA |
280 | #define INPUT_POOL_SHIFT 12 |
281 | #define INPUT_POOL_WORDS (1 << (INPUT_POOL_SHIFT-5)) | |
282 | #define OUTPUT_POOL_SHIFT 10 | |
283 | #define OUTPUT_POOL_WORDS (1 << (OUTPUT_POOL_SHIFT-5)) | |
284 | #define SEC_XFER_SIZE 512 | |
285 | #define EXTRACT_SIZE 10 | |
1da177e4 | 286 | |
392a546d | 287 | #define DEBUG_RANDOM_BOOT 0 |
1da177e4 | 288 | |
d2e7c96a PA |
289 | #define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long)) |
290 | ||
a283b5c4 | 291 | /* |
95b709b6 TT |
292 | * To allow fractional bits to be tracked, the entropy_count field is |
293 | * denominated in units of 1/8th bits. | |
30e37ec5 PA |
294 | * |
295 | * 2*(ENTROPY_SHIFT + log2(poolbits)) must <= 31, or the multiply in | |
296 | * credit_entropy_bits() needs to be 64 bits wide. | |
a283b5c4 PA |
297 | */ |
298 | #define ENTROPY_SHIFT 3 | |
299 | #define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT) | |
300 | ||
1da177e4 LT |
301 | /* |
302 | * The minimum number of bits of entropy before we wake up a read on | |
303 | * /dev/random. Should be enough to do a significant reseed. | |
304 | */ | |
2132a96f | 305 | static int random_read_wakeup_bits = 64; |
1da177e4 LT |
306 | |
307 | /* | |
308 | * If the entropy count falls under this number of bits, then we | |
309 | * should wake up processes which are selecting or polling on write | |
310 | * access to /dev/random. | |
311 | */ | |
2132a96f | 312 | static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS; |
1da177e4 LT |
313 | |
314 | /* | |
dfd38750 | 315 | * The minimum number of seconds between urandom pool reseeding. We |
f5c2742c TT |
316 | * do this to limit the amount of entropy that can be drained from the |
317 | * input pool even if there are heavy demands on /dev/urandom. | |
1da177e4 | 318 | */ |
f5c2742c | 319 | static int random_min_urandom_seed = 60; |
1da177e4 LT |
320 | |
321 | /* | |
6e9fa2c8 TT |
322 | * Originally, we used a primitive polynomial of degree .poolwords |
323 | * over GF(2). The taps for various sizes are defined below. They | |
324 | * were chosen to be evenly spaced except for the last tap, which is 1 | |
325 | * to get the twisting happening as fast as possible. | |
326 | * | |
327 | * For the purposes of better mixing, we use the CRC-32 polynomial as | |
328 | * well to make a (modified) twisted Generalized Feedback Shift | |
329 | * Register. (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR | |
330 | * generators. ACM Transactions on Modeling and Computer Simulation | |
331 | * 2(3):179-194. Also see M. Matsumoto & Y. Kurita, 1994. Twisted | |
dfd38750 | 332 | * GFSR generators II. ACM Transactions on Modeling and Computer |
6e9fa2c8 TT |
333 | * Simulation 4:254-266) |
334 | * | |
335 | * Thanks to Colin Plumb for suggesting this. | |
336 | * | |
337 | * The mixing operation is much less sensitive than the output hash, | |
338 | * where we use SHA-1. All that we want of mixing operation is that | |
339 | * it be a good non-cryptographic hash; i.e. it not produce collisions | |
340 | * when fed "random" data of the sort we expect to see. As long as | |
341 | * the pool state differs for different inputs, we have preserved the | |
342 | * input entropy and done a good job. The fact that an intelligent | |
343 | * attacker can construct inputs that will produce controlled | |
344 | * alterations to the pool's state is not important because we don't | |
345 | * consider such inputs to contribute any randomness. The only | |
346 | * property we need with respect to them is that the attacker can't | |
347 | * increase his/her knowledge of the pool's state. Since all | |
348 | * additions are reversible (knowing the final state and the input, | |
349 | * you can reconstruct the initial state), if an attacker has any | |
350 | * uncertainty about the initial state, he/she can only shuffle that | |
351 | * uncertainty about, but never cause any collisions (which would | |
352 | * decrease the uncertainty). | |
353 | * | |
354 | * Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and | |
355 | * Videau in their paper, "The Linux Pseudorandom Number Generator | |
356 | * Revisited" (see: http://eprint.iacr.org/2012/251.pdf). In their | |
357 | * paper, they point out that we are not using a true Twisted GFSR, | |
358 | * since Matsumoto & Kurita used a trinomial feedback polynomial (that | |
359 | * is, with only three taps, instead of the six that we are using). | |
360 | * As a result, the resulting polynomial is neither primitive nor | |
361 | * irreducible, and hence does not have a maximal period over | |
362 | * GF(2**32). They suggest a slight change to the generator | |
363 | * polynomial which improves the resulting TGFSR polynomial to be | |
364 | * irreducible, which we have made here. | |
1da177e4 LT |
365 | */ |
366 | static struct poolinfo { | |
a283b5c4 PA |
367 | int poolbitshift, poolwords, poolbytes, poolbits, poolfracbits; |
368 | #define S(x) ilog2(x)+5, (x), (x)*4, (x)*32, (x) << (ENTROPY_SHIFT+5) | |
1da177e4 LT |
369 | int tap1, tap2, tap3, tap4, tap5; |
370 | } poolinfo_table[] = { | |
6e9fa2c8 TT |
371 | /* was: x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 */ |
372 | /* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */ | |
373 | { S(128), 104, 76, 51, 25, 1 }, | |
374 | /* was: x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 */ | |
375 | /* x^32 + x^26 + x^19 + x^14 + x^7 + x + 1 */ | |
376 | { S(32), 26, 19, 14, 7, 1 }, | |
1da177e4 LT |
377 | #if 0 |
378 | /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */ | |
9ed17b70 | 379 | { S(2048), 1638, 1231, 819, 411, 1 }, |
1da177e4 LT |
380 | |
381 | /* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */ | |
9ed17b70 | 382 | { S(1024), 817, 615, 412, 204, 1 }, |
1da177e4 LT |
383 | |
384 | /* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */ | |
9ed17b70 | 385 | { S(1024), 819, 616, 410, 207, 2 }, |
1da177e4 LT |
386 | |
387 | /* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */ | |
9ed17b70 | 388 | { S(512), 411, 308, 208, 104, 1 }, |
1da177e4 LT |
389 | |
390 | /* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */ | |
9ed17b70 | 391 | { S(512), 409, 307, 206, 102, 2 }, |
1da177e4 | 392 | /* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */ |
9ed17b70 | 393 | { S(512), 409, 309, 205, 103, 2 }, |
1da177e4 LT |
394 | |
395 | /* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */ | |
9ed17b70 | 396 | { S(256), 205, 155, 101, 52, 1 }, |
1da177e4 LT |
397 | |
398 | /* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */ | |
9ed17b70 | 399 | { S(128), 103, 78, 51, 27, 2 }, |
1da177e4 LT |
400 | |
401 | /* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */ | |
9ed17b70 | 402 | { S(64), 52, 39, 26, 14, 1 }, |
1da177e4 LT |
403 | #endif |
404 | }; | |
405 | ||
1da177e4 LT |
406 | /* |
407 | * Static global variables | |
408 | */ | |
409 | static DECLARE_WAIT_QUEUE_HEAD(random_read_wait); | |
410 | static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); | |
c6e9d6f3 | 411 | static DECLARE_WAIT_QUEUE_HEAD(urandom_init_wait); |
9a6f70bb | 412 | static struct fasync_struct *fasync; |
1da177e4 | 413 | |
205a525c HX |
414 | static DEFINE_SPINLOCK(random_ready_list_lock); |
415 | static LIST_HEAD(random_ready_list); | |
416 | ||
e192be9d TT |
417 | struct crng_state { |
418 | __u32 state[16]; | |
419 | unsigned long init_time; | |
420 | spinlock_t lock; | |
421 | }; | |
422 | ||
423 | struct crng_state primary_crng = { | |
424 | .lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock), | |
425 | }; | |
426 | ||
427 | /* | |
428 | * crng_init = 0 --> Uninitialized | |
429 | * 1 --> Initialized | |
430 | * 2 --> Initialized from input_pool | |
431 | * | |
432 | * crng_init is protected by primary_crng->lock, and only increases | |
433 | * its value (from 0->1->2). | |
434 | */ | |
435 | static int crng_init = 0; | |
436 | #define crng_ready() (likely(crng_init > 0)) | |
437 | static int crng_init_cnt = 0; | |
438 | #define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE) | |
439 | static void extract_crng(__u8 out[CHACHA20_BLOCK_SIZE]); | |
440 | static void process_random_ready_list(void); | |
441 | ||
1da177e4 LT |
442 | /********************************************************************** |
443 | * | |
444 | * OS independent entropy store. Here are the functions which handle | |
445 | * storing entropy in an entropy pool. | |
446 | * | |
447 | **********************************************************************/ | |
448 | ||
449 | struct entropy_store; | |
450 | struct entropy_store { | |
43358209 | 451 | /* read-only data: */ |
30e37ec5 | 452 | const struct poolinfo *poolinfo; |
1da177e4 LT |
453 | __u32 *pool; |
454 | const char *name; | |
1da177e4 | 455 | struct entropy_store *pull; |
6265e169 | 456 | struct work_struct push_work; |
1da177e4 LT |
457 | |
458 | /* read-write data: */ | |
f5c2742c | 459 | unsigned long last_pulled; |
43358209 | 460 | spinlock_t lock; |
c59974ae TT |
461 | unsigned short add_ptr; |
462 | unsigned short input_rotate; | |
cda796a3 | 463 | int entropy_count; |
775f4b29 | 464 | int entropy_total; |
775f4b29 | 465 | unsigned int initialized:1; |
c59974ae TT |
466 | unsigned int limit:1; |
467 | unsigned int last_data_init:1; | |
e954bc91 | 468 | __u8 last_data[EXTRACT_SIZE]; |
1da177e4 LT |
469 | }; |
470 | ||
e192be9d TT |
471 | static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
472 | size_t nbytes, int min, int rsvd); | |
473 | static ssize_t _extract_entropy(struct entropy_store *r, void *buf, | |
474 | size_t nbytes, int fips); | |
475 | ||
476 | static void crng_reseed(struct crng_state *crng, struct entropy_store *r); | |
6265e169 | 477 | static void push_to_pool(struct work_struct *work); |
1da177e4 LT |
478 | static __u32 input_pool_data[INPUT_POOL_WORDS]; |
479 | static __u32 blocking_pool_data[OUTPUT_POOL_WORDS]; | |
1da177e4 LT |
480 | |
481 | static struct entropy_store input_pool = { | |
482 | .poolinfo = &poolinfo_table[0], | |
483 | .name = "input", | |
484 | .limit = 1, | |
eece09ec | 485 | .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock), |
1da177e4 LT |
486 | .pool = input_pool_data |
487 | }; | |
488 | ||
489 | static struct entropy_store blocking_pool = { | |
490 | .poolinfo = &poolinfo_table[1], | |
491 | .name = "blocking", | |
492 | .limit = 1, | |
493 | .pull = &input_pool, | |
eece09ec | 494 | .lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock), |
6265e169 TT |
495 | .pool = blocking_pool_data, |
496 | .push_work = __WORK_INITIALIZER(blocking_pool.push_work, | |
497 | push_to_pool), | |
1da177e4 LT |
498 | }; |
499 | ||
775f4b29 TT |
500 | static __u32 const twist_table[8] = { |
501 | 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158, | |
502 | 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 }; | |
503 | ||
1da177e4 | 504 | /* |
e68e5b66 | 505 | * This function adds bytes into the entropy "pool". It does not |
1da177e4 | 506 | * update the entropy estimate. The caller should call |
adc782da | 507 | * credit_entropy_bits if this is appropriate. |
1da177e4 LT |
508 | * |
509 | * The pool is stirred with a primitive polynomial of the appropriate | |
510 | * degree, and then twisted. We twist by three bits at a time because | |
511 | * it's cheap to do so and helps slightly in the expected case where | |
512 | * the entropy is concentrated in the low-order bits. | |
513 | */ | |
00ce1db1 | 514 | static void _mix_pool_bytes(struct entropy_store *r, const void *in, |
85608f8e | 515 | int nbytes) |
1da177e4 | 516 | { |
85608f8e | 517 | unsigned long i, tap1, tap2, tap3, tap4, tap5; |
feee7697 | 518 | int input_rotate; |
1da177e4 | 519 | int wordmask = r->poolinfo->poolwords - 1; |
e68e5b66 | 520 | const char *bytes = in; |
6d38b827 | 521 | __u32 w; |
1da177e4 | 522 | |
1da177e4 LT |
523 | tap1 = r->poolinfo->tap1; |
524 | tap2 = r->poolinfo->tap2; | |
525 | tap3 = r->poolinfo->tap3; | |
526 | tap4 = r->poolinfo->tap4; | |
527 | tap5 = r->poolinfo->tap5; | |
1da177e4 | 528 | |
91fcb532 TT |
529 | input_rotate = r->input_rotate; |
530 | i = r->add_ptr; | |
1da177e4 | 531 | |
e68e5b66 MM |
532 | /* mix one byte at a time to simplify size handling and churn faster */ |
533 | while (nbytes--) { | |
c59974ae | 534 | w = rol32(*bytes++, input_rotate); |
993ba211 | 535 | i = (i - 1) & wordmask; |
1da177e4 LT |
536 | |
537 | /* XOR in the various taps */ | |
993ba211 | 538 | w ^= r->pool[i]; |
1da177e4 LT |
539 | w ^= r->pool[(i + tap1) & wordmask]; |
540 | w ^= r->pool[(i + tap2) & wordmask]; | |
541 | w ^= r->pool[(i + tap3) & wordmask]; | |
542 | w ^= r->pool[(i + tap4) & wordmask]; | |
543 | w ^= r->pool[(i + tap5) & wordmask]; | |
993ba211 MM |
544 | |
545 | /* Mix the result back in with a twist */ | |
1da177e4 | 546 | r->pool[i] = (w >> 3) ^ twist_table[w & 7]; |
feee7697 MM |
547 | |
548 | /* | |
549 | * Normally, we add 7 bits of rotation to the pool. | |
550 | * At the beginning of the pool, add an extra 7 bits | |
551 | * rotation, so that successive passes spread the | |
552 | * input bits across the pool evenly. | |
553 | */ | |
c59974ae | 554 | input_rotate = (input_rotate + (i ? 7 : 14)) & 31; |
1da177e4 LT |
555 | } |
556 | ||
91fcb532 TT |
557 | r->input_rotate = input_rotate; |
558 | r->add_ptr = i; | |
1da177e4 LT |
559 | } |
560 | ||
00ce1db1 | 561 | static void __mix_pool_bytes(struct entropy_store *r, const void *in, |
85608f8e | 562 | int nbytes) |
00ce1db1 TT |
563 | { |
564 | trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_); | |
85608f8e | 565 | _mix_pool_bytes(r, in, nbytes); |
00ce1db1 TT |
566 | } |
567 | ||
568 | static void mix_pool_bytes(struct entropy_store *r, const void *in, | |
85608f8e | 569 | int nbytes) |
1da177e4 | 570 | { |
902c098a TT |
571 | unsigned long flags; |
572 | ||
00ce1db1 | 573 | trace_mix_pool_bytes(r->name, nbytes, _RET_IP_); |
902c098a | 574 | spin_lock_irqsave(&r->lock, flags); |
85608f8e | 575 | _mix_pool_bytes(r, in, nbytes); |
902c098a | 576 | spin_unlock_irqrestore(&r->lock, flags); |
1da177e4 LT |
577 | } |
578 | ||
775f4b29 TT |
579 | struct fast_pool { |
580 | __u32 pool[4]; | |
581 | unsigned long last; | |
ee3e00e9 | 582 | unsigned short reg_idx; |
840f9507 | 583 | unsigned char count; |
775f4b29 TT |
584 | }; |
585 | ||
586 | /* | |
587 | * This is a fast mixing routine used by the interrupt randomness | |
588 | * collector. It's hardcoded for an 128 bit pool and assumes that any | |
589 | * locks that might be needed are taken by the caller. | |
590 | */ | |
43759d4f | 591 | static void fast_mix(struct fast_pool *f) |
775f4b29 | 592 | { |
43759d4f TT |
593 | __u32 a = f->pool[0], b = f->pool[1]; |
594 | __u32 c = f->pool[2], d = f->pool[3]; | |
595 | ||
596 | a += b; c += d; | |
19acc77a | 597 | b = rol32(b, 6); d = rol32(d, 27); |
43759d4f TT |
598 | d ^= a; b ^= c; |
599 | ||
600 | a += b; c += d; | |
19acc77a | 601 | b = rol32(b, 16); d = rol32(d, 14); |
43759d4f TT |
602 | d ^= a; b ^= c; |
603 | ||
604 | a += b; c += d; | |
19acc77a | 605 | b = rol32(b, 6); d = rol32(d, 27); |
43759d4f TT |
606 | d ^= a; b ^= c; |
607 | ||
608 | a += b; c += d; | |
19acc77a | 609 | b = rol32(b, 16); d = rol32(d, 14); |
43759d4f TT |
610 | d ^= a; b ^= c; |
611 | ||
612 | f->pool[0] = a; f->pool[1] = b; | |
613 | f->pool[2] = c; f->pool[3] = d; | |
655b2264 | 614 | f->count++; |
775f4b29 TT |
615 | } |
616 | ||
205a525c HX |
617 | static void process_random_ready_list(void) |
618 | { | |
619 | unsigned long flags; | |
620 | struct random_ready_callback *rdy, *tmp; | |
621 | ||
622 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
623 | list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) { | |
624 | struct module *owner = rdy->owner; | |
625 | ||
626 | list_del_init(&rdy->list); | |
627 | rdy->func(rdy); | |
628 | module_put(owner); | |
629 | } | |
630 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
631 | } | |
632 | ||
1da177e4 | 633 | /* |
a283b5c4 PA |
634 | * Credit (or debit) the entropy store with n bits of entropy. |
635 | * Use credit_entropy_bits_safe() if the value comes from userspace | |
636 | * or otherwise should be checked for extreme values. | |
1da177e4 | 637 | */ |
adc782da | 638 | static void credit_entropy_bits(struct entropy_store *r, int nbits) |
1da177e4 | 639 | { |
902c098a | 640 | int entropy_count, orig; |
30e37ec5 PA |
641 | const int pool_size = r->poolinfo->poolfracbits; |
642 | int nfrac = nbits << ENTROPY_SHIFT; | |
1da177e4 | 643 | |
adc782da MM |
644 | if (!nbits) |
645 | return; | |
646 | ||
902c098a TT |
647 | retry: |
648 | entropy_count = orig = ACCESS_ONCE(r->entropy_count); | |
30e37ec5 PA |
649 | if (nfrac < 0) { |
650 | /* Debit */ | |
651 | entropy_count += nfrac; | |
652 | } else { | |
653 | /* | |
654 | * Credit: we have to account for the possibility of | |
655 | * overwriting already present entropy. Even in the | |
656 | * ideal case of pure Shannon entropy, new contributions | |
657 | * approach the full value asymptotically: | |
658 | * | |
659 | * entropy <- entropy + (pool_size - entropy) * | |
660 | * (1 - exp(-add_entropy/pool_size)) | |
661 | * | |
662 | * For add_entropy <= pool_size/2 then | |
663 | * (1 - exp(-add_entropy/pool_size)) >= | |
664 | * (add_entropy/pool_size)*0.7869... | |
665 | * so we can approximate the exponential with | |
666 | * 3/4*add_entropy/pool_size and still be on the | |
667 | * safe side by adding at most pool_size/2 at a time. | |
668 | * | |
669 | * The use of pool_size-2 in the while statement is to | |
670 | * prevent rounding artifacts from making the loop | |
671 | * arbitrarily long; this limits the loop to log2(pool_size)*2 | |
672 | * turns no matter how large nbits is. | |
673 | */ | |
674 | int pnfrac = nfrac; | |
675 | const int s = r->poolinfo->poolbitshift + ENTROPY_SHIFT + 2; | |
676 | /* The +2 corresponds to the /4 in the denominator */ | |
677 | ||
678 | do { | |
679 | unsigned int anfrac = min(pnfrac, pool_size/2); | |
680 | unsigned int add = | |
681 | ((pool_size - entropy_count)*anfrac*3) >> s; | |
682 | ||
683 | entropy_count += add; | |
684 | pnfrac -= anfrac; | |
685 | } while (unlikely(entropy_count < pool_size-2 && pnfrac)); | |
686 | } | |
00ce1db1 | 687 | |
79a84687 | 688 | if (unlikely(entropy_count < 0)) { |
f80bbd8b TT |
689 | pr_warn("random: negative entropy/overflow: pool %s count %d\n", |
690 | r->name, entropy_count); | |
691 | WARN_ON(1); | |
8b76f46a | 692 | entropy_count = 0; |
30e37ec5 PA |
693 | } else if (entropy_count > pool_size) |
694 | entropy_count = pool_size; | |
902c098a TT |
695 | if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) |
696 | goto retry; | |
1da177e4 | 697 | |
6265e169 | 698 | r->entropy_total += nbits; |
0891ad82 LT |
699 | if (!r->initialized && r->entropy_total > 128) { |
700 | r->initialized = 1; | |
701 | r->entropy_total = 0; | |
775f4b29 TT |
702 | } |
703 | ||
a283b5c4 PA |
704 | trace_credit_entropy_bits(r->name, nbits, |
705 | entropy_count >> ENTROPY_SHIFT, | |
00ce1db1 TT |
706 | r->entropy_total, _RET_IP_); |
707 | ||
6265e169 | 708 | if (r == &input_pool) { |
7d1b08c4 | 709 | int entropy_bits = entropy_count >> ENTROPY_SHIFT; |
6265e169 | 710 | |
e192be9d TT |
711 | if (crng_init < 2 && entropy_bits >= 128) { |
712 | crng_reseed(&primary_crng, r); | |
713 | entropy_bits = r->entropy_count >> ENTROPY_SHIFT; | |
714 | } | |
715 | ||
6265e169 | 716 | /* should we wake readers? */ |
2132a96f | 717 | if (entropy_bits >= random_read_wakeup_bits) { |
6265e169 TT |
718 | wake_up_interruptible(&random_read_wait); |
719 | kill_fasync(&fasync, SIGIO, POLL_IN); | |
720 | } | |
721 | /* If the input pool is getting full, send some | |
e192be9d | 722 | * entropy to the blocking pool until it is 75% full. |
6265e169 | 723 | */ |
2132a96f | 724 | if (entropy_bits > random_write_wakeup_bits && |
6265e169 | 725 | r->initialized && |
2132a96f | 726 | r->entropy_total >= 2*random_read_wakeup_bits) { |
6265e169 TT |
727 | struct entropy_store *other = &blocking_pool; |
728 | ||
6265e169 | 729 | if (other->entropy_count <= |
e192be9d TT |
730 | 3 * other->poolinfo->poolfracbits / 4) { |
731 | schedule_work(&other->push_work); | |
6265e169 TT |
732 | r->entropy_total = 0; |
733 | } | |
734 | } | |
9a6f70bb | 735 | } |
1da177e4 LT |
736 | } |
737 | ||
a283b5c4 PA |
738 | static void credit_entropy_bits_safe(struct entropy_store *r, int nbits) |
739 | { | |
740 | const int nbits_max = (int)(~0U >> (ENTROPY_SHIFT + 1)); | |
741 | ||
742 | /* Cap the value to avoid overflows */ | |
743 | nbits = min(nbits, nbits_max); | |
744 | nbits = max(nbits, -nbits_max); | |
745 | ||
746 | credit_entropy_bits(r, nbits); | |
747 | } | |
748 | ||
e192be9d TT |
749 | /********************************************************************* |
750 | * | |
751 | * CRNG using CHACHA20 | |
752 | * | |
753 | *********************************************************************/ | |
754 | ||
755 | #define CRNG_RESEED_INTERVAL (300*HZ) | |
756 | ||
757 | static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); | |
758 | ||
759 | static void crng_initialize(struct crng_state *crng) | |
760 | { | |
761 | int i; | |
762 | unsigned long rv; | |
763 | ||
764 | memcpy(&crng->state[0], "expand 32-byte k", 16); | |
765 | if (crng == &primary_crng) | |
766 | _extract_entropy(&input_pool, &crng->state[4], | |
767 | sizeof(__u32) * 12, 0); | |
768 | else | |
769 | get_random_bytes(&crng->state[4], sizeof(__u32) * 12); | |
770 | for (i = 4; i < 16; i++) { | |
771 | if (!arch_get_random_seed_long(&rv) && | |
772 | !arch_get_random_long(&rv)) | |
773 | rv = random_get_entropy(); | |
774 | crng->state[i] ^= rv; | |
775 | } | |
776 | crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1; | |
777 | } | |
778 | ||
779 | static int crng_fast_load(const char *cp, size_t len) | |
780 | { | |
781 | unsigned long flags; | |
782 | char *p; | |
783 | ||
784 | if (!spin_trylock_irqsave(&primary_crng.lock, flags)) | |
785 | return 0; | |
786 | if (crng_ready()) { | |
787 | spin_unlock_irqrestore(&primary_crng.lock, flags); | |
788 | return 0; | |
789 | } | |
790 | p = (unsigned char *) &primary_crng.state[4]; | |
791 | while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) { | |
792 | p[crng_init_cnt % CHACHA20_KEY_SIZE] ^= *cp; | |
793 | cp++; crng_init_cnt++; len--; | |
794 | } | |
795 | if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) { | |
796 | crng_init = 1; | |
797 | wake_up_interruptible(&crng_init_wait); | |
798 | pr_notice("random: fast init done\n"); | |
799 | } | |
800 | spin_unlock_irqrestore(&primary_crng.lock, flags); | |
801 | return 1; | |
802 | } | |
803 | ||
804 | static void crng_reseed(struct crng_state *crng, struct entropy_store *r) | |
805 | { | |
806 | unsigned long flags; | |
807 | int i, num; | |
808 | union { | |
809 | __u8 block[CHACHA20_BLOCK_SIZE]; | |
810 | __u32 key[8]; | |
811 | } buf; | |
812 | ||
813 | if (r) { | |
814 | num = extract_entropy(r, &buf, 32, 16, 0); | |
815 | if (num == 0) | |
816 | return; | |
817 | } else | |
818 | extract_crng(buf.block); | |
819 | spin_lock_irqsave(&primary_crng.lock, flags); | |
820 | for (i = 0; i < 8; i++) { | |
821 | unsigned long rv; | |
822 | if (!arch_get_random_seed_long(&rv) && | |
823 | !arch_get_random_long(&rv)) | |
824 | rv = random_get_entropy(); | |
825 | crng->state[i+4] ^= buf.key[i] ^ rv; | |
826 | } | |
827 | memzero_explicit(&buf, sizeof(buf)); | |
828 | crng->init_time = jiffies; | |
829 | if (crng == &primary_crng && crng_init < 2) { | |
830 | crng_init = 2; | |
831 | process_random_ready_list(); | |
832 | wake_up_interruptible(&crng_init_wait); | |
833 | pr_notice("random: crng init done\n"); | |
834 | } | |
835 | spin_unlock_irqrestore(&primary_crng.lock, flags); | |
836 | } | |
837 | ||
838 | static inline void crng_wait_ready(void) | |
839 | { | |
840 | wait_event_interruptible(crng_init_wait, crng_ready()); | |
841 | } | |
842 | ||
843 | static void extract_crng(__u8 out[CHACHA20_BLOCK_SIZE]) | |
844 | { | |
845 | unsigned long v, flags; | |
846 | struct crng_state *crng = &primary_crng; | |
847 | ||
848 | if (crng_init > 1 && | |
849 | time_after(jiffies, crng->init_time + CRNG_RESEED_INTERVAL)) | |
850 | crng_reseed(crng, &input_pool); | |
851 | spin_lock_irqsave(&crng->lock, flags); | |
852 | if (arch_get_random_long(&v)) | |
853 | crng->state[14] ^= v; | |
854 | chacha20_block(&crng->state[0], out); | |
855 | if (crng->state[12] == 0) | |
856 | crng->state[13]++; | |
857 | spin_unlock_irqrestore(&crng->lock, flags); | |
858 | } | |
859 | ||
860 | static ssize_t extract_crng_user(void __user *buf, size_t nbytes) | |
861 | { | |
862 | ssize_t ret = 0, i; | |
863 | __u8 tmp[CHACHA20_BLOCK_SIZE]; | |
864 | int large_request = (nbytes > 256); | |
865 | ||
866 | while (nbytes) { | |
867 | if (large_request && need_resched()) { | |
868 | if (signal_pending(current)) { | |
869 | if (ret == 0) | |
870 | ret = -ERESTARTSYS; | |
871 | break; | |
872 | } | |
873 | schedule(); | |
874 | } | |
875 | ||
876 | extract_crng(tmp); | |
877 | i = min_t(int, nbytes, CHACHA20_BLOCK_SIZE); | |
878 | if (copy_to_user(buf, tmp, i)) { | |
879 | ret = -EFAULT; | |
880 | break; | |
881 | } | |
882 | ||
883 | nbytes -= i; | |
884 | buf += i; | |
885 | ret += i; | |
886 | } | |
887 | ||
888 | /* Wipe data just written to memory */ | |
889 | memzero_explicit(tmp, sizeof(tmp)); | |
890 | ||
891 | return ret; | |
892 | } | |
893 | ||
894 | ||
1da177e4 LT |
895 | /********************************************************************* |
896 | * | |
897 | * Entropy input management | |
898 | * | |
899 | *********************************************************************/ | |
900 | ||
901 | /* There is one of these per entropy source */ | |
902 | struct timer_rand_state { | |
903 | cycles_t last_time; | |
90b75ee5 | 904 | long last_delta, last_delta2; |
1da177e4 LT |
905 | unsigned dont_count_entropy:1; |
906 | }; | |
907 | ||
644008df TT |
908 | #define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, }; |
909 | ||
a2080a67 | 910 | /* |
e192be9d TT |
911 | * Add device- or boot-specific data to the input pool to help |
912 | * initialize it. | |
a2080a67 | 913 | * |
e192be9d TT |
914 | * None of this adds any entropy; it is meant to avoid the problem of |
915 | * the entropy pool having similar initial state across largely | |
916 | * identical devices. | |
a2080a67 LT |
917 | */ |
918 | void add_device_randomness(const void *buf, unsigned int size) | |
919 | { | |
61875f30 | 920 | unsigned long time = random_get_entropy() ^ jiffies; |
3ef4cb2d | 921 | unsigned long flags; |
a2080a67 | 922 | |
5910895f | 923 | trace_add_device_randomness(size, _RET_IP_); |
3ef4cb2d | 924 | spin_lock_irqsave(&input_pool.lock, flags); |
85608f8e TT |
925 | _mix_pool_bytes(&input_pool, buf, size); |
926 | _mix_pool_bytes(&input_pool, &time, sizeof(time)); | |
3ef4cb2d | 927 | spin_unlock_irqrestore(&input_pool.lock, flags); |
a2080a67 LT |
928 | } |
929 | EXPORT_SYMBOL(add_device_randomness); | |
930 | ||
644008df | 931 | static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE; |
3060d6fe | 932 | |
1da177e4 LT |
933 | /* |
934 | * This function adds entropy to the entropy "pool" by using timing | |
935 | * delays. It uses the timer_rand_state structure to make an estimate | |
936 | * of how many bits of entropy this call has added to the pool. | |
937 | * | |
938 | * The number "num" is also added to the pool - it should somehow describe | |
939 | * the type of event which just happened. This is currently 0-255 for | |
940 | * keyboard scan codes, and 256 upwards for interrupts. | |
941 | * | |
942 | */ | |
943 | static void add_timer_randomness(struct timer_rand_state *state, unsigned num) | |
944 | { | |
40db23e5 | 945 | struct entropy_store *r; |
1da177e4 | 946 | struct { |
1da177e4 | 947 | long jiffies; |
cf833d0b | 948 | unsigned cycles; |
1da177e4 LT |
949 | unsigned num; |
950 | } sample; | |
951 | long delta, delta2, delta3; | |
952 | ||
953 | preempt_disable(); | |
1da177e4 LT |
954 | |
955 | sample.jiffies = jiffies; | |
61875f30 | 956 | sample.cycles = random_get_entropy(); |
1da177e4 | 957 | sample.num = num; |
e192be9d | 958 | r = &input_pool; |
85608f8e | 959 | mix_pool_bytes(r, &sample, sizeof(sample)); |
1da177e4 LT |
960 | |
961 | /* | |
962 | * Calculate number of bits of randomness we probably added. | |
963 | * We take into account the first, second and third-order deltas | |
964 | * in order to make our estimate. | |
965 | */ | |
966 | ||
967 | if (!state->dont_count_entropy) { | |
968 | delta = sample.jiffies - state->last_time; | |
969 | state->last_time = sample.jiffies; | |
970 | ||
971 | delta2 = delta - state->last_delta; | |
972 | state->last_delta = delta; | |
973 | ||
974 | delta3 = delta2 - state->last_delta2; | |
975 | state->last_delta2 = delta2; | |
976 | ||
977 | if (delta < 0) | |
978 | delta = -delta; | |
979 | if (delta2 < 0) | |
980 | delta2 = -delta2; | |
981 | if (delta3 < 0) | |
982 | delta3 = -delta3; | |
983 | if (delta > delta2) | |
984 | delta = delta2; | |
985 | if (delta > delta3) | |
986 | delta = delta3; | |
987 | ||
988 | /* | |
989 | * delta is now minimum absolute delta. | |
990 | * Round down by 1 bit on general principles, | |
991 | * and limit entropy entimate to 12 bits. | |
992 | */ | |
40db23e5 | 993 | credit_entropy_bits(r, min_t(int, fls(delta>>1), 11)); |
1da177e4 | 994 | } |
1da177e4 LT |
995 | preempt_enable(); |
996 | } | |
997 | ||
d251575a | 998 | void add_input_randomness(unsigned int type, unsigned int code, |
1da177e4 LT |
999 | unsigned int value) |
1000 | { | |
1001 | static unsigned char last_value; | |
1002 | ||
1003 | /* ignore autorepeat and the like */ | |
1004 | if (value == last_value) | |
1005 | return; | |
1006 | ||
1da177e4 LT |
1007 | last_value = value; |
1008 | add_timer_randomness(&input_timer_state, | |
1009 | (type << 4) ^ code ^ (code >> 4) ^ value); | |
f80bbd8b | 1010 | trace_add_input_randomness(ENTROPY_BITS(&input_pool)); |
1da177e4 | 1011 | } |
80fc9f53 | 1012 | EXPORT_SYMBOL_GPL(add_input_randomness); |
1da177e4 | 1013 | |
775f4b29 TT |
1014 | static DEFINE_PER_CPU(struct fast_pool, irq_randomness); |
1015 | ||
43759d4f TT |
1016 | #ifdef ADD_INTERRUPT_BENCH |
1017 | static unsigned long avg_cycles, avg_deviation; | |
1018 | ||
1019 | #define AVG_SHIFT 8 /* Exponential average factor k=1/256 */ | |
1020 | #define FIXED_1_2 (1 << (AVG_SHIFT-1)) | |
1021 | ||
1022 | static void add_interrupt_bench(cycles_t start) | |
1023 | { | |
1024 | long delta = random_get_entropy() - start; | |
1025 | ||
1026 | /* Use a weighted moving average */ | |
1027 | delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT); | |
1028 | avg_cycles += delta; | |
1029 | /* And average deviation */ | |
1030 | delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT); | |
1031 | avg_deviation += delta; | |
1032 | } | |
1033 | #else | |
1034 | #define add_interrupt_bench(x) | |
1035 | #endif | |
1036 | ||
ee3e00e9 TT |
1037 | static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs) |
1038 | { | |
1039 | __u32 *ptr = (__u32 *) regs; | |
1040 | ||
1041 | if (regs == NULL) | |
1042 | return 0; | |
1043 | if (f->reg_idx >= sizeof(struct pt_regs) / sizeof(__u32)) | |
1044 | f->reg_idx = 0; | |
1045 | return *(ptr + f->reg_idx++); | |
1046 | } | |
1047 | ||
775f4b29 | 1048 | void add_interrupt_randomness(int irq, int irq_flags) |
1da177e4 | 1049 | { |
775f4b29 | 1050 | struct entropy_store *r; |
1b2a1a7e | 1051 | struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness); |
775f4b29 TT |
1052 | struct pt_regs *regs = get_irq_regs(); |
1053 | unsigned long now = jiffies; | |
655b2264 | 1054 | cycles_t cycles = random_get_entropy(); |
43759d4f | 1055 | __u32 c_high, j_high; |
655b2264 | 1056 | __u64 ip; |
83664a69 | 1057 | unsigned long seed; |
91fcb532 | 1058 | int credit = 0; |
3060d6fe | 1059 | |
ee3e00e9 TT |
1060 | if (cycles == 0) |
1061 | cycles = get_reg(fast_pool, regs); | |
655b2264 TT |
1062 | c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0; |
1063 | j_high = (sizeof(now) > 4) ? now >> 32 : 0; | |
43759d4f TT |
1064 | fast_pool->pool[0] ^= cycles ^ j_high ^ irq; |
1065 | fast_pool->pool[1] ^= now ^ c_high; | |
655b2264 | 1066 | ip = regs ? instruction_pointer(regs) : _RET_IP_; |
43759d4f | 1067 | fast_pool->pool[2] ^= ip; |
ee3e00e9 TT |
1068 | fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 : |
1069 | get_reg(fast_pool, regs); | |
3060d6fe | 1070 | |
43759d4f | 1071 | fast_mix(fast_pool); |
43759d4f | 1072 | add_interrupt_bench(cycles); |
3060d6fe | 1073 | |
e192be9d TT |
1074 | if (!crng_ready()) { |
1075 | if ((fast_pool->count >= 64) && | |
1076 | crng_fast_load((char *) fast_pool->pool, | |
1077 | sizeof(fast_pool->pool))) { | |
1078 | fast_pool->count = 0; | |
1079 | fast_pool->last = now; | |
1080 | } | |
1081 | return; | |
1082 | } | |
1083 | ||
ee3e00e9 TT |
1084 | if ((fast_pool->count < 64) && |
1085 | !time_after(now, fast_pool->last + HZ)) | |
1da177e4 LT |
1086 | return; |
1087 | ||
e192be9d | 1088 | r = &input_pool; |
840f9507 | 1089 | if (!spin_trylock(&r->lock)) |
91fcb532 | 1090 | return; |
83664a69 | 1091 | |
91fcb532 | 1092 | fast_pool->last = now; |
85608f8e | 1093 | __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool)); |
83664a69 PA |
1094 | |
1095 | /* | |
1096 | * If we have architectural seed generator, produce a seed and | |
48d6be95 TT |
1097 | * add it to the pool. For the sake of paranoia don't let the |
1098 | * architectural seed generator dominate the input from the | |
1099 | * interrupt noise. | |
83664a69 PA |
1100 | */ |
1101 | if (arch_get_random_seed_long(&seed)) { | |
85608f8e | 1102 | __mix_pool_bytes(r, &seed, sizeof(seed)); |
48d6be95 | 1103 | credit = 1; |
83664a69 | 1104 | } |
91fcb532 | 1105 | spin_unlock(&r->lock); |
83664a69 | 1106 | |
ee3e00e9 | 1107 | fast_pool->count = 0; |
83664a69 | 1108 | |
ee3e00e9 TT |
1109 | /* award one bit for the contents of the fast pool */ |
1110 | credit_entropy_bits(r, credit + 1); | |
1da177e4 | 1111 | } |
4b44f2d1 | 1112 | EXPORT_SYMBOL_GPL(add_interrupt_randomness); |
1da177e4 | 1113 | |
9361401e | 1114 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1115 | void add_disk_randomness(struct gendisk *disk) |
1116 | { | |
1117 | if (!disk || !disk->random) | |
1118 | return; | |
1119 | /* first major is 1, so we get >= 0x200 here */ | |
f331c029 | 1120 | add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); |
f80bbd8b | 1121 | trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS(&input_pool)); |
1da177e4 | 1122 | } |
bdcfa3e5 | 1123 | EXPORT_SYMBOL_GPL(add_disk_randomness); |
9361401e | 1124 | #endif |
1da177e4 | 1125 | |
1da177e4 LT |
1126 | /********************************************************************* |
1127 | * | |
1128 | * Entropy extraction routines | |
1129 | * | |
1130 | *********************************************************************/ | |
1131 | ||
1da177e4 | 1132 | /* |
25985edc | 1133 | * This utility inline function is responsible for transferring entropy |
1da177e4 LT |
1134 | * from the primary pool to the secondary extraction pool. We make |
1135 | * sure we pull enough for a 'catastrophic reseed'. | |
1136 | */ | |
6265e169 | 1137 | static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes); |
1da177e4 LT |
1138 | static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes) |
1139 | { | |
cff85031 TT |
1140 | if (!r->pull || |
1141 | r->entropy_count >= (nbytes << (ENTROPY_SHIFT + 3)) || | |
1142 | r->entropy_count > r->poolinfo->poolfracbits) | |
1143 | return; | |
1144 | ||
f5c2742c TT |
1145 | if (r->limit == 0 && random_min_urandom_seed) { |
1146 | unsigned long now = jiffies; | |
1da177e4 | 1147 | |
f5c2742c TT |
1148 | if (time_before(now, |
1149 | r->last_pulled + random_min_urandom_seed * HZ)) | |
1150 | return; | |
1151 | r->last_pulled = now; | |
1da177e4 | 1152 | } |
cff85031 TT |
1153 | |
1154 | _xfer_secondary_pool(r, nbytes); | |
6265e169 TT |
1155 | } |
1156 | ||
1157 | static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes) | |
1158 | { | |
1159 | __u32 tmp[OUTPUT_POOL_WORDS]; | |
1160 | ||
2132a96f GP |
1161 | /* For /dev/random's pool, always leave two wakeups' worth */ |
1162 | int rsvd_bytes = r->limit ? 0 : random_read_wakeup_bits / 4; | |
6265e169 TT |
1163 | int bytes = nbytes; |
1164 | ||
2132a96f GP |
1165 | /* pull at least as much as a wakeup */ |
1166 | bytes = max_t(int, bytes, random_read_wakeup_bits / 8); | |
6265e169 TT |
1167 | /* but never more than the buffer size */ |
1168 | bytes = min_t(int, bytes, sizeof(tmp)); | |
1169 | ||
f80bbd8b TT |
1170 | trace_xfer_secondary_pool(r->name, bytes * 8, nbytes * 8, |
1171 | ENTROPY_BITS(r), ENTROPY_BITS(r->pull)); | |
6265e169 | 1172 | bytes = extract_entropy(r->pull, tmp, bytes, |
2132a96f | 1173 | random_read_wakeup_bits / 8, rsvd_bytes); |
85608f8e | 1174 | mix_pool_bytes(r, tmp, bytes); |
6265e169 TT |
1175 | credit_entropy_bits(r, bytes*8); |
1176 | } | |
1177 | ||
1178 | /* | |
1179 | * Used as a workqueue function so that when the input pool is getting | |
1180 | * full, we can "spill over" some entropy to the output pools. That | |
1181 | * way the output pools can store some of the excess entropy instead | |
1182 | * of letting it go to waste. | |
1183 | */ | |
1184 | static void push_to_pool(struct work_struct *work) | |
1185 | { | |
1186 | struct entropy_store *r = container_of(work, struct entropy_store, | |
1187 | push_work); | |
1188 | BUG_ON(!r); | |
2132a96f | 1189 | _xfer_secondary_pool(r, random_read_wakeup_bits/8); |
6265e169 TT |
1190 | trace_push_to_pool(r->name, r->entropy_count >> ENTROPY_SHIFT, |
1191 | r->pull->entropy_count >> ENTROPY_SHIFT); | |
1da177e4 LT |
1192 | } |
1193 | ||
1194 | /* | |
19fa5be1 GP |
1195 | * This function decides how many bytes to actually take from the |
1196 | * given pool, and also debits the entropy count accordingly. | |
1da177e4 | 1197 | */ |
1da177e4 LT |
1198 | static size_t account(struct entropy_store *r, size_t nbytes, int min, |
1199 | int reserved) | |
1200 | { | |
a283b5c4 | 1201 | int entropy_count, orig; |
79a84687 | 1202 | size_t ibytes, nfrac; |
1da177e4 | 1203 | |
a283b5c4 | 1204 | BUG_ON(r->entropy_count > r->poolinfo->poolfracbits); |
1da177e4 LT |
1205 | |
1206 | /* Can we pull enough? */ | |
10b3a32d | 1207 | retry: |
a283b5c4 | 1208 | entropy_count = orig = ACCESS_ONCE(r->entropy_count); |
a283b5c4 | 1209 | ibytes = nbytes; |
0fb7a01a | 1210 | /* If limited, never pull more than available */ |
e33ba5fa TT |
1211 | if (r->limit) { |
1212 | int have_bytes = entropy_count >> (ENTROPY_SHIFT + 3); | |
1213 | ||
1214 | if ((have_bytes -= reserved) < 0) | |
1215 | have_bytes = 0; | |
1216 | ibytes = min_t(size_t, ibytes, have_bytes); | |
1217 | } | |
0fb7a01a | 1218 | if (ibytes < min) |
a283b5c4 | 1219 | ibytes = 0; |
79a84687 HFS |
1220 | |
1221 | if (unlikely(entropy_count < 0)) { | |
1222 | pr_warn("random: negative entropy count: pool %s count %d\n", | |
1223 | r->name, entropy_count); | |
1224 | WARN_ON(1); | |
1225 | entropy_count = 0; | |
1226 | } | |
1227 | nfrac = ibytes << (ENTROPY_SHIFT + 3); | |
1228 | if ((size_t) entropy_count > nfrac) | |
1229 | entropy_count -= nfrac; | |
1230 | else | |
e33ba5fa | 1231 | entropy_count = 0; |
f9c6d498 | 1232 | |
0fb7a01a GP |
1233 | if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) |
1234 | goto retry; | |
1da177e4 | 1235 | |
f80bbd8b | 1236 | trace_debit_entropy(r->name, 8 * ibytes); |
0fb7a01a | 1237 | if (ibytes && |
2132a96f | 1238 | (r->entropy_count >> ENTROPY_SHIFT) < random_write_wakeup_bits) { |
b9809552 TT |
1239 | wake_up_interruptible(&random_write_wait); |
1240 | kill_fasync(&fasync, SIGIO, POLL_OUT); | |
1241 | } | |
1242 | ||
a283b5c4 | 1243 | return ibytes; |
1da177e4 LT |
1244 | } |
1245 | ||
19fa5be1 GP |
1246 | /* |
1247 | * This function does the actual extraction for extract_entropy and | |
1248 | * extract_entropy_user. | |
1249 | * | |
1250 | * Note: we assume that .poolwords is a multiple of 16 words. | |
1251 | */ | |
1da177e4 LT |
1252 | static void extract_buf(struct entropy_store *r, __u8 *out) |
1253 | { | |
602b6aee | 1254 | int i; |
d2e7c96a PA |
1255 | union { |
1256 | __u32 w[5]; | |
85a1f777 | 1257 | unsigned long l[LONGS(20)]; |
d2e7c96a PA |
1258 | } hash; |
1259 | __u32 workspace[SHA_WORKSPACE_WORDS]; | |
902c098a | 1260 | unsigned long flags; |
1da177e4 | 1261 | |
85a1f777 | 1262 | /* |
dfd38750 | 1263 | * If we have an architectural hardware random number |
46884442 | 1264 | * generator, use it for SHA's initial vector |
85a1f777 | 1265 | */ |
46884442 | 1266 | sha_init(hash.w); |
85a1f777 TT |
1267 | for (i = 0; i < LONGS(20); i++) { |
1268 | unsigned long v; | |
1269 | if (!arch_get_random_long(&v)) | |
1270 | break; | |
46884442 | 1271 | hash.l[i] = v; |
85a1f777 TT |
1272 | } |
1273 | ||
46884442 TT |
1274 | /* Generate a hash across the pool, 16 words (512 bits) at a time */ |
1275 | spin_lock_irqsave(&r->lock, flags); | |
1276 | for (i = 0; i < r->poolinfo->poolwords; i += 16) | |
1277 | sha_transform(hash.w, (__u8 *)(r->pool + i), workspace); | |
1278 | ||
1da177e4 | 1279 | /* |
1c0ad3d4 MM |
1280 | * We mix the hash back into the pool to prevent backtracking |
1281 | * attacks (where the attacker knows the state of the pool | |
1282 | * plus the current outputs, and attempts to find previous | |
1283 | * ouputs), unless the hash function can be inverted. By | |
1284 | * mixing at least a SHA1 worth of hash data back, we make | |
1285 | * brute-forcing the feedback as hard as brute-forcing the | |
1286 | * hash. | |
1da177e4 | 1287 | */ |
85608f8e | 1288 | __mix_pool_bytes(r, hash.w, sizeof(hash.w)); |
902c098a | 1289 | spin_unlock_irqrestore(&r->lock, flags); |
1da177e4 | 1290 | |
d4c5efdb | 1291 | memzero_explicit(workspace, sizeof(workspace)); |
1da177e4 LT |
1292 | |
1293 | /* | |
1c0ad3d4 MM |
1294 | * In case the hash function has some recognizable output |
1295 | * pattern, we fold it in half. Thus, we always feed back | |
1296 | * twice as much data as we output. | |
1da177e4 | 1297 | */ |
d2e7c96a PA |
1298 | hash.w[0] ^= hash.w[3]; |
1299 | hash.w[1] ^= hash.w[4]; | |
1300 | hash.w[2] ^= rol32(hash.w[2], 16); | |
1301 | ||
d2e7c96a | 1302 | memcpy(out, &hash, EXTRACT_SIZE); |
d4c5efdb | 1303 | memzero_explicit(&hash, sizeof(hash)); |
1da177e4 LT |
1304 | } |
1305 | ||
e192be9d TT |
1306 | static ssize_t _extract_entropy(struct entropy_store *r, void *buf, |
1307 | size_t nbytes, int fips) | |
1308 | { | |
1309 | ssize_t ret = 0, i; | |
1310 | __u8 tmp[EXTRACT_SIZE]; | |
1311 | unsigned long flags; | |
1312 | ||
1313 | while (nbytes) { | |
1314 | extract_buf(r, tmp); | |
1315 | ||
1316 | if (fips) { | |
1317 | spin_lock_irqsave(&r->lock, flags); | |
1318 | if (!memcmp(tmp, r->last_data, EXTRACT_SIZE)) | |
1319 | panic("Hardware RNG duplicated output!\n"); | |
1320 | memcpy(r->last_data, tmp, EXTRACT_SIZE); | |
1321 | spin_unlock_irqrestore(&r->lock, flags); | |
1322 | } | |
1323 | i = min_t(int, nbytes, EXTRACT_SIZE); | |
1324 | memcpy(buf, tmp, i); | |
1325 | nbytes -= i; | |
1326 | buf += i; | |
1327 | ret += i; | |
1328 | } | |
1329 | ||
1330 | /* Wipe data just returned from memory */ | |
1331 | memzero_explicit(tmp, sizeof(tmp)); | |
1332 | ||
1333 | return ret; | |
1334 | } | |
1335 | ||
19fa5be1 GP |
1336 | /* |
1337 | * This function extracts randomness from the "entropy pool", and | |
1338 | * returns it in a buffer. | |
1339 | * | |
1340 | * The min parameter specifies the minimum amount we can pull before | |
1341 | * failing to avoid races that defeat catastrophic reseeding while the | |
1342 | * reserved parameter indicates how much entropy we must leave in the | |
1343 | * pool after each pull to avoid starving other readers. | |
1344 | */ | |
90b75ee5 | 1345 | static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
902c098a | 1346 | size_t nbytes, int min, int reserved) |
1da177e4 | 1347 | { |
1da177e4 | 1348 | __u8 tmp[EXTRACT_SIZE]; |
1e7e2e05 | 1349 | unsigned long flags; |
1da177e4 | 1350 | |
ec8f02da | 1351 | /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */ |
1e7e2e05 JW |
1352 | if (fips_enabled) { |
1353 | spin_lock_irqsave(&r->lock, flags); | |
1354 | if (!r->last_data_init) { | |
c59974ae | 1355 | r->last_data_init = 1; |
1e7e2e05 JW |
1356 | spin_unlock_irqrestore(&r->lock, flags); |
1357 | trace_extract_entropy(r->name, EXTRACT_SIZE, | |
a283b5c4 | 1358 | ENTROPY_BITS(r), _RET_IP_); |
1e7e2e05 JW |
1359 | xfer_secondary_pool(r, EXTRACT_SIZE); |
1360 | extract_buf(r, tmp); | |
1361 | spin_lock_irqsave(&r->lock, flags); | |
1362 | memcpy(r->last_data, tmp, EXTRACT_SIZE); | |
1363 | } | |
1364 | spin_unlock_irqrestore(&r->lock, flags); | |
1365 | } | |
ec8f02da | 1366 | |
a283b5c4 | 1367 | trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_); |
1da177e4 LT |
1368 | xfer_secondary_pool(r, nbytes); |
1369 | nbytes = account(r, nbytes, min, reserved); | |
1370 | ||
e192be9d | 1371 | return _extract_entropy(r, buf, nbytes, fips_enabled); |
1da177e4 LT |
1372 | } |
1373 | ||
19fa5be1 GP |
1374 | /* |
1375 | * This function extracts randomness from the "entropy pool", and | |
1376 | * returns it in a userspace buffer. | |
1377 | */ | |
1da177e4 LT |
1378 | static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf, |
1379 | size_t nbytes) | |
1380 | { | |
1381 | ssize_t ret = 0, i; | |
1382 | __u8 tmp[EXTRACT_SIZE]; | |
c6e9d6f3 | 1383 | int large_request = (nbytes > 256); |
1da177e4 | 1384 | |
a283b5c4 | 1385 | trace_extract_entropy_user(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_); |
1da177e4 LT |
1386 | xfer_secondary_pool(r, nbytes); |
1387 | nbytes = account(r, nbytes, 0, 0); | |
1388 | ||
1389 | while (nbytes) { | |
c6e9d6f3 | 1390 | if (large_request && need_resched()) { |
1da177e4 LT |
1391 | if (signal_pending(current)) { |
1392 | if (ret == 0) | |
1393 | ret = -ERESTARTSYS; | |
1394 | break; | |
1395 | } | |
1396 | schedule(); | |
1397 | } | |
1398 | ||
1399 | extract_buf(r, tmp); | |
1400 | i = min_t(int, nbytes, EXTRACT_SIZE); | |
1401 | if (copy_to_user(buf, tmp, i)) { | |
1402 | ret = -EFAULT; | |
1403 | break; | |
1404 | } | |
1405 | ||
1406 | nbytes -= i; | |
1407 | buf += i; | |
1408 | ret += i; | |
1409 | } | |
1410 | ||
1411 | /* Wipe data just returned from memory */ | |
d4c5efdb | 1412 | memzero_explicit(tmp, sizeof(tmp)); |
1da177e4 LT |
1413 | |
1414 | return ret; | |
1415 | } | |
1416 | ||
1417 | /* | |
1418 | * This function is the exported kernel interface. It returns some | |
c2557a30 | 1419 | * number of good random numbers, suitable for key generation, seeding |
18e9cea7 GP |
1420 | * TCP sequence numbers, etc. It does not rely on the hardware random |
1421 | * number generator. For random bytes direct from the hardware RNG | |
1422 | * (when available), use get_random_bytes_arch(). | |
1da177e4 LT |
1423 | */ |
1424 | void get_random_bytes(void *buf, int nbytes) | |
c2557a30 | 1425 | { |
e192be9d TT |
1426 | __u8 tmp[CHACHA20_BLOCK_SIZE]; |
1427 | ||
392a546d | 1428 | #if DEBUG_RANDOM_BOOT > 0 |
e192be9d | 1429 | if (!crng_ready()) |
392a546d | 1430 | printk(KERN_NOTICE "random: %pF get_random_bytes called " |
e192be9d | 1431 | "with crng_init = %d\n", (void *) _RET_IP_, crng_init); |
392a546d | 1432 | #endif |
5910895f | 1433 | trace_get_random_bytes(nbytes, _RET_IP_); |
e192be9d TT |
1434 | |
1435 | while (nbytes >= CHACHA20_BLOCK_SIZE) { | |
1436 | extract_crng(buf); | |
1437 | buf += CHACHA20_BLOCK_SIZE; | |
1438 | nbytes -= CHACHA20_BLOCK_SIZE; | |
1439 | } | |
1440 | ||
1441 | if (nbytes > 0) { | |
1442 | extract_crng(tmp); | |
1443 | memcpy(buf, tmp, nbytes); | |
1444 | memzero_explicit(tmp, nbytes); | |
1445 | } | |
c2557a30 TT |
1446 | } |
1447 | EXPORT_SYMBOL(get_random_bytes); | |
1448 | ||
205a525c HX |
1449 | /* |
1450 | * Add a callback function that will be invoked when the nonblocking | |
1451 | * pool is initialised. | |
1452 | * | |
1453 | * returns: 0 if callback is successfully added | |
1454 | * -EALREADY if pool is already initialised (callback not called) | |
1455 | * -ENOENT if module for callback is not alive | |
1456 | */ | |
1457 | int add_random_ready_callback(struct random_ready_callback *rdy) | |
1458 | { | |
1459 | struct module *owner; | |
1460 | unsigned long flags; | |
1461 | int err = -EALREADY; | |
1462 | ||
e192be9d | 1463 | if (crng_ready()) |
205a525c HX |
1464 | return err; |
1465 | ||
1466 | owner = rdy->owner; | |
1467 | if (!try_module_get(owner)) | |
1468 | return -ENOENT; | |
1469 | ||
1470 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
e192be9d | 1471 | if (crng_ready()) |
205a525c HX |
1472 | goto out; |
1473 | ||
1474 | owner = NULL; | |
1475 | ||
1476 | list_add(&rdy->list, &random_ready_list); | |
1477 | err = 0; | |
1478 | ||
1479 | out: | |
1480 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
1481 | ||
1482 | module_put(owner); | |
1483 | ||
1484 | return err; | |
1485 | } | |
1486 | EXPORT_SYMBOL(add_random_ready_callback); | |
1487 | ||
1488 | /* | |
1489 | * Delete a previously registered readiness callback function. | |
1490 | */ | |
1491 | void del_random_ready_callback(struct random_ready_callback *rdy) | |
1492 | { | |
1493 | unsigned long flags; | |
1494 | struct module *owner = NULL; | |
1495 | ||
1496 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
1497 | if (!list_empty(&rdy->list)) { | |
1498 | list_del_init(&rdy->list); | |
1499 | owner = rdy->owner; | |
1500 | } | |
1501 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
1502 | ||
1503 | module_put(owner); | |
1504 | } | |
1505 | EXPORT_SYMBOL(del_random_ready_callback); | |
1506 | ||
c2557a30 TT |
1507 | /* |
1508 | * This function will use the architecture-specific hardware random | |
1509 | * number generator if it is available. The arch-specific hw RNG will | |
1510 | * almost certainly be faster than what we can do in software, but it | |
1511 | * is impossible to verify that it is implemented securely (as | |
1512 | * opposed, to, say, the AES encryption of a sequence number using a | |
1513 | * key known by the NSA). So it's useful if we need the speed, but | |
1514 | * only if we're willing to trust the hardware manufacturer not to | |
1515 | * have put in a back door. | |
1516 | */ | |
1517 | void get_random_bytes_arch(void *buf, int nbytes) | |
1da177e4 | 1518 | { |
63d77173 PA |
1519 | char *p = buf; |
1520 | ||
5910895f | 1521 | trace_get_random_bytes_arch(nbytes, _RET_IP_); |
63d77173 PA |
1522 | while (nbytes) { |
1523 | unsigned long v; | |
1524 | int chunk = min(nbytes, (int)sizeof(unsigned long)); | |
c2557a30 | 1525 | |
63d77173 PA |
1526 | if (!arch_get_random_long(&v)) |
1527 | break; | |
1528 | ||
bd29e568 | 1529 | memcpy(p, &v, chunk); |
63d77173 PA |
1530 | p += chunk; |
1531 | nbytes -= chunk; | |
1532 | } | |
1533 | ||
c2557a30 | 1534 | if (nbytes) |
e192be9d | 1535 | get_random_bytes(p, nbytes); |
1da177e4 | 1536 | } |
c2557a30 TT |
1537 | EXPORT_SYMBOL(get_random_bytes_arch); |
1538 | ||
1da177e4 LT |
1539 | |
1540 | /* | |
1541 | * init_std_data - initialize pool with system data | |
1542 | * | |
1543 | * @r: pool to initialize | |
1544 | * | |
1545 | * This function clears the pool's entropy count and mixes some system | |
1546 | * data into the pool to prepare it for use. The pool is not cleared | |
1547 | * as that can only decrease the entropy in the pool. | |
1548 | */ | |
1549 | static void init_std_data(struct entropy_store *r) | |
1550 | { | |
3e88bdff | 1551 | int i; |
902c098a TT |
1552 | ktime_t now = ktime_get_real(); |
1553 | unsigned long rv; | |
1da177e4 | 1554 | |
f5c2742c | 1555 | r->last_pulled = jiffies; |
85608f8e | 1556 | mix_pool_bytes(r, &now, sizeof(now)); |
9ed17b70 | 1557 | for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) { |
83664a69 PA |
1558 | if (!arch_get_random_seed_long(&rv) && |
1559 | !arch_get_random_long(&rv)) | |
ae9ecd92 | 1560 | rv = random_get_entropy(); |
85608f8e | 1561 | mix_pool_bytes(r, &rv, sizeof(rv)); |
3e88bdff | 1562 | } |
85608f8e | 1563 | mix_pool_bytes(r, utsname(), sizeof(*(utsname()))); |
1da177e4 LT |
1564 | } |
1565 | ||
cbc96b75 TL |
1566 | /* |
1567 | * Note that setup_arch() may call add_device_randomness() | |
1568 | * long before we get here. This allows seeding of the pools | |
1569 | * with some platform dependent data very early in the boot | |
1570 | * process. But it limits our options here. We must use | |
1571 | * statically allocated structures that already have all | |
1572 | * initializations complete at compile time. We should also | |
1573 | * take care not to overwrite the precious per platform data | |
1574 | * we were given. | |
1575 | */ | |
53c3f63e | 1576 | static int rand_initialize(void) |
1da177e4 LT |
1577 | { |
1578 | init_std_data(&input_pool); | |
1579 | init_std_data(&blocking_pool); | |
e192be9d | 1580 | crng_initialize(&primary_crng); |
1da177e4 LT |
1581 | return 0; |
1582 | } | |
ae9ecd92 | 1583 | early_initcall(rand_initialize); |
1da177e4 | 1584 | |
9361401e | 1585 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1586 | void rand_initialize_disk(struct gendisk *disk) |
1587 | { | |
1588 | struct timer_rand_state *state; | |
1589 | ||
1590 | /* | |
f8595815 | 1591 | * If kzalloc returns null, we just won't use that entropy |
1da177e4 LT |
1592 | * source. |
1593 | */ | |
f8595815 | 1594 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
644008df TT |
1595 | if (state) { |
1596 | state->last_time = INITIAL_JIFFIES; | |
1da177e4 | 1597 | disk->random = state; |
644008df | 1598 | } |
1da177e4 | 1599 | } |
9361401e | 1600 | #endif |
1da177e4 LT |
1601 | |
1602 | static ssize_t | |
c6e9d6f3 | 1603 | _random_read(int nonblock, char __user *buf, size_t nbytes) |
1da177e4 | 1604 | { |
12ff3a51 | 1605 | ssize_t n; |
1da177e4 LT |
1606 | |
1607 | if (nbytes == 0) | |
1608 | return 0; | |
1609 | ||
12ff3a51 GP |
1610 | nbytes = min_t(size_t, nbytes, SEC_XFER_SIZE); |
1611 | while (1) { | |
1612 | n = extract_entropy_user(&blocking_pool, buf, nbytes); | |
1613 | if (n < 0) | |
1614 | return n; | |
f80bbd8b TT |
1615 | trace_random_read(n*8, (nbytes-n)*8, |
1616 | ENTROPY_BITS(&blocking_pool), | |
1617 | ENTROPY_BITS(&input_pool)); | |
12ff3a51 GP |
1618 | if (n > 0) |
1619 | return n; | |
331c6490 | 1620 | |
12ff3a51 | 1621 | /* Pool is (near) empty. Maybe wait and retry. */ |
c6e9d6f3 | 1622 | if (nonblock) |
12ff3a51 GP |
1623 | return -EAGAIN; |
1624 | ||
1625 | wait_event_interruptible(random_read_wait, | |
1626 | ENTROPY_BITS(&input_pool) >= | |
2132a96f | 1627 | random_read_wakeup_bits); |
12ff3a51 GP |
1628 | if (signal_pending(current)) |
1629 | return -ERESTARTSYS; | |
1da177e4 | 1630 | } |
1da177e4 LT |
1631 | } |
1632 | ||
c6e9d6f3 TT |
1633 | static ssize_t |
1634 | random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) | |
1635 | { | |
1636 | return _random_read(file->f_flags & O_NONBLOCK, buf, nbytes); | |
1637 | } | |
1638 | ||
1da177e4 | 1639 | static ssize_t |
90b75ee5 | 1640 | urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
1da177e4 | 1641 | { |
e192be9d | 1642 | unsigned long flags; |
9b4d0087 | 1643 | static int maxwarn = 10; |
301f0595 TT |
1644 | int ret; |
1645 | ||
e192be9d | 1646 | if (!crng_ready() && maxwarn > 0) { |
9b4d0087 TT |
1647 | maxwarn--; |
1648 | printk(KERN_NOTICE "random: %s: uninitialized urandom read " | |
e192be9d TT |
1649 | "(%zd bytes read)\n", |
1650 | current->comm, nbytes); | |
1651 | spin_lock_irqsave(&primary_crng.lock, flags); | |
1652 | crng_init_cnt = 0; | |
1653 | spin_unlock_irqrestore(&primary_crng.lock, flags); | |
9b4d0087 | 1654 | } |
79a84687 | 1655 | nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3)); |
e192be9d TT |
1656 | ret = extract_crng_user(buf, nbytes); |
1657 | trace_urandom_read(8 * nbytes, 0, ENTROPY_BITS(&input_pool)); | |
f80bbd8b | 1658 | return ret; |
1da177e4 LT |
1659 | } |
1660 | ||
1661 | static unsigned int | |
1662 | random_poll(struct file *file, poll_table * wait) | |
1663 | { | |
1664 | unsigned int mask; | |
1665 | ||
1666 | poll_wait(file, &random_read_wait, wait); | |
1667 | poll_wait(file, &random_write_wait, wait); | |
1668 | mask = 0; | |
2132a96f | 1669 | if (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits) |
1da177e4 | 1670 | mask |= POLLIN | POLLRDNORM; |
2132a96f | 1671 | if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits) |
1da177e4 LT |
1672 | mask |= POLLOUT | POLLWRNORM; |
1673 | return mask; | |
1674 | } | |
1675 | ||
7f397dcd MM |
1676 | static int |
1677 | write_pool(struct entropy_store *r, const char __user *buffer, size_t count) | |
1da177e4 | 1678 | { |
1da177e4 LT |
1679 | size_t bytes; |
1680 | __u32 buf[16]; | |
1681 | const char __user *p = buffer; | |
1da177e4 | 1682 | |
7f397dcd MM |
1683 | while (count > 0) { |
1684 | bytes = min(count, sizeof(buf)); | |
1685 | if (copy_from_user(&buf, p, bytes)) | |
1686 | return -EFAULT; | |
1da177e4 | 1687 | |
7f397dcd | 1688 | count -= bytes; |
1da177e4 LT |
1689 | p += bytes; |
1690 | ||
85608f8e | 1691 | mix_pool_bytes(r, buf, bytes); |
91f3f1e3 | 1692 | cond_resched(); |
1da177e4 | 1693 | } |
7f397dcd MM |
1694 | |
1695 | return 0; | |
1696 | } | |
1697 | ||
90b75ee5 MM |
1698 | static ssize_t random_write(struct file *file, const char __user *buffer, |
1699 | size_t count, loff_t *ppos) | |
7f397dcd MM |
1700 | { |
1701 | size_t ret; | |
7f397dcd | 1702 | |
e192be9d | 1703 | ret = write_pool(&input_pool, buffer, count); |
7f397dcd MM |
1704 | if (ret) |
1705 | return ret; | |
1706 | ||
7f397dcd | 1707 | return (ssize_t)count; |
1da177e4 LT |
1708 | } |
1709 | ||
43ae4860 | 1710 | static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) |
1da177e4 LT |
1711 | { |
1712 | int size, ent_count; | |
1713 | int __user *p = (int __user *)arg; | |
1714 | int retval; | |
1715 | ||
1716 | switch (cmd) { | |
1717 | case RNDGETENTCNT: | |
43ae4860 | 1718 | /* inherently racy, no point locking */ |
a283b5c4 PA |
1719 | ent_count = ENTROPY_BITS(&input_pool); |
1720 | if (put_user(ent_count, p)) | |
1da177e4 LT |
1721 | return -EFAULT; |
1722 | return 0; | |
1723 | case RNDADDTOENTCNT: | |
1724 | if (!capable(CAP_SYS_ADMIN)) | |
1725 | return -EPERM; | |
1726 | if (get_user(ent_count, p)) | |
1727 | return -EFAULT; | |
a283b5c4 | 1728 | credit_entropy_bits_safe(&input_pool, ent_count); |
1da177e4 LT |
1729 | return 0; |
1730 | case RNDADDENTROPY: | |
1731 | if (!capable(CAP_SYS_ADMIN)) | |
1732 | return -EPERM; | |
1733 | if (get_user(ent_count, p++)) | |
1734 | return -EFAULT; | |
1735 | if (ent_count < 0) | |
1736 | return -EINVAL; | |
1737 | if (get_user(size, p++)) | |
1738 | return -EFAULT; | |
7f397dcd MM |
1739 | retval = write_pool(&input_pool, (const char __user *)p, |
1740 | size); | |
1da177e4 LT |
1741 | if (retval < 0) |
1742 | return retval; | |
a283b5c4 | 1743 | credit_entropy_bits_safe(&input_pool, ent_count); |
1da177e4 LT |
1744 | return 0; |
1745 | case RNDZAPENTCNT: | |
1746 | case RNDCLEARPOOL: | |
ae9ecd92 TT |
1747 | /* |
1748 | * Clear the entropy pool counters. We no longer clear | |
1749 | * the entropy pool, as that's silly. | |
1750 | */ | |
1da177e4 LT |
1751 | if (!capable(CAP_SYS_ADMIN)) |
1752 | return -EPERM; | |
ae9ecd92 | 1753 | input_pool.entropy_count = 0; |
ae9ecd92 | 1754 | blocking_pool.entropy_count = 0; |
1da177e4 LT |
1755 | return 0; |
1756 | default: | |
1757 | return -EINVAL; | |
1758 | } | |
1759 | } | |
1760 | ||
9a6f70bb JD |
1761 | static int random_fasync(int fd, struct file *filp, int on) |
1762 | { | |
1763 | return fasync_helper(fd, filp, on, &fasync); | |
1764 | } | |
1765 | ||
2b8693c0 | 1766 | const struct file_operations random_fops = { |
1da177e4 LT |
1767 | .read = random_read, |
1768 | .write = random_write, | |
1769 | .poll = random_poll, | |
43ae4860 | 1770 | .unlocked_ioctl = random_ioctl, |
9a6f70bb | 1771 | .fasync = random_fasync, |
6038f373 | 1772 | .llseek = noop_llseek, |
1da177e4 LT |
1773 | }; |
1774 | ||
2b8693c0 | 1775 | const struct file_operations urandom_fops = { |
1da177e4 LT |
1776 | .read = urandom_read, |
1777 | .write = random_write, | |
43ae4860 | 1778 | .unlocked_ioctl = random_ioctl, |
9a6f70bb | 1779 | .fasync = random_fasync, |
6038f373 | 1780 | .llseek = noop_llseek, |
1da177e4 LT |
1781 | }; |
1782 | ||
c6e9d6f3 TT |
1783 | SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, |
1784 | unsigned int, flags) | |
1785 | { | |
1786 | if (flags & ~(GRND_NONBLOCK|GRND_RANDOM)) | |
1787 | return -EINVAL; | |
1788 | ||
1789 | if (count > INT_MAX) | |
1790 | count = INT_MAX; | |
1791 | ||
1792 | if (flags & GRND_RANDOM) | |
1793 | return _random_read(flags & GRND_NONBLOCK, buf, count); | |
1794 | ||
e192be9d | 1795 | if (!crng_ready()) { |
c6e9d6f3 TT |
1796 | if (flags & GRND_NONBLOCK) |
1797 | return -EAGAIN; | |
e192be9d | 1798 | crng_wait_ready(); |
c6e9d6f3 TT |
1799 | if (signal_pending(current)) |
1800 | return -ERESTARTSYS; | |
1801 | } | |
1802 | return urandom_read(NULL, buf, count, NULL); | |
1803 | } | |
1804 | ||
1da177e4 LT |
1805 | /******************************************************************** |
1806 | * | |
1807 | * Sysctl interface | |
1808 | * | |
1809 | ********************************************************************/ | |
1810 | ||
1811 | #ifdef CONFIG_SYSCTL | |
1812 | ||
1813 | #include <linux/sysctl.h> | |
1814 | ||
1815 | static int min_read_thresh = 8, min_write_thresh; | |
8c2aa339 | 1816 | static int max_read_thresh = OUTPUT_POOL_WORDS * 32; |
1da177e4 LT |
1817 | static int max_write_thresh = INPUT_POOL_WORDS * 32; |
1818 | static char sysctl_bootid[16]; | |
1819 | ||
1820 | /* | |
f22052b2 | 1821 | * This function is used to return both the bootid UUID, and random |
1da177e4 LT |
1822 | * UUID. The difference is in whether table->data is NULL; if it is, |
1823 | * then a new UUID is generated and returned to the user. | |
1824 | * | |
f22052b2 GP |
1825 | * If the user accesses this via the proc interface, the UUID will be |
1826 | * returned as an ASCII string in the standard UUID format; if via the | |
1827 | * sysctl system call, as 16 bytes of binary data. | |
1da177e4 | 1828 | */ |
a151427e | 1829 | static int proc_do_uuid(struct ctl_table *table, int write, |
1da177e4 LT |
1830 | void __user *buffer, size_t *lenp, loff_t *ppos) |
1831 | { | |
a151427e | 1832 | struct ctl_table fake_table; |
1da177e4 LT |
1833 | unsigned char buf[64], tmp_uuid[16], *uuid; |
1834 | ||
1835 | uuid = table->data; | |
1836 | if (!uuid) { | |
1837 | uuid = tmp_uuid; | |
1da177e4 | 1838 | generate_random_uuid(uuid); |
44e4360f MD |
1839 | } else { |
1840 | static DEFINE_SPINLOCK(bootid_spinlock); | |
1841 | ||
1842 | spin_lock(&bootid_spinlock); | |
1843 | if (!uuid[8]) | |
1844 | generate_random_uuid(uuid); | |
1845 | spin_unlock(&bootid_spinlock); | |
1846 | } | |
1da177e4 | 1847 | |
35900771 JP |
1848 | sprintf(buf, "%pU", uuid); |
1849 | ||
1da177e4 LT |
1850 | fake_table.data = buf; |
1851 | fake_table.maxlen = sizeof(buf); | |
1852 | ||
8d65af78 | 1853 | return proc_dostring(&fake_table, write, buffer, lenp, ppos); |
1da177e4 LT |
1854 | } |
1855 | ||
a283b5c4 PA |
1856 | /* |
1857 | * Return entropy available scaled to integral bits | |
1858 | */ | |
5eb10d91 | 1859 | static int proc_do_entropy(struct ctl_table *table, int write, |
a283b5c4 PA |
1860 | void __user *buffer, size_t *lenp, loff_t *ppos) |
1861 | { | |
5eb10d91 | 1862 | struct ctl_table fake_table; |
a283b5c4 PA |
1863 | int entropy_count; |
1864 | ||
1865 | entropy_count = *(int *)table->data >> ENTROPY_SHIFT; | |
1866 | ||
1867 | fake_table.data = &entropy_count; | |
1868 | fake_table.maxlen = sizeof(entropy_count); | |
1869 | ||
1870 | return proc_dointvec(&fake_table, write, buffer, lenp, ppos); | |
1871 | } | |
1872 | ||
1da177e4 | 1873 | static int sysctl_poolsize = INPUT_POOL_WORDS * 32; |
a151427e JP |
1874 | extern struct ctl_table random_table[]; |
1875 | struct ctl_table random_table[] = { | |
1da177e4 | 1876 | { |
1da177e4 LT |
1877 | .procname = "poolsize", |
1878 | .data = &sysctl_poolsize, | |
1879 | .maxlen = sizeof(int), | |
1880 | .mode = 0444, | |
6d456111 | 1881 | .proc_handler = proc_dointvec, |
1da177e4 LT |
1882 | }, |
1883 | { | |
1da177e4 LT |
1884 | .procname = "entropy_avail", |
1885 | .maxlen = sizeof(int), | |
1886 | .mode = 0444, | |
a283b5c4 | 1887 | .proc_handler = proc_do_entropy, |
1da177e4 LT |
1888 | .data = &input_pool.entropy_count, |
1889 | }, | |
1890 | { | |
1da177e4 | 1891 | .procname = "read_wakeup_threshold", |
2132a96f | 1892 | .data = &random_read_wakeup_bits, |
1da177e4 LT |
1893 | .maxlen = sizeof(int), |
1894 | .mode = 0644, | |
6d456111 | 1895 | .proc_handler = proc_dointvec_minmax, |
1da177e4 LT |
1896 | .extra1 = &min_read_thresh, |
1897 | .extra2 = &max_read_thresh, | |
1898 | }, | |
1899 | { | |
1da177e4 | 1900 | .procname = "write_wakeup_threshold", |
2132a96f | 1901 | .data = &random_write_wakeup_bits, |
1da177e4 LT |
1902 | .maxlen = sizeof(int), |
1903 | .mode = 0644, | |
6d456111 | 1904 | .proc_handler = proc_dointvec_minmax, |
1da177e4 LT |
1905 | .extra1 = &min_write_thresh, |
1906 | .extra2 = &max_write_thresh, | |
1907 | }, | |
f5c2742c TT |
1908 | { |
1909 | .procname = "urandom_min_reseed_secs", | |
1910 | .data = &random_min_urandom_seed, | |
1911 | .maxlen = sizeof(int), | |
1912 | .mode = 0644, | |
1913 | .proc_handler = proc_dointvec, | |
1914 | }, | |
1da177e4 | 1915 | { |
1da177e4 LT |
1916 | .procname = "boot_id", |
1917 | .data = &sysctl_bootid, | |
1918 | .maxlen = 16, | |
1919 | .mode = 0444, | |
6d456111 | 1920 | .proc_handler = proc_do_uuid, |
1da177e4 LT |
1921 | }, |
1922 | { | |
1da177e4 LT |
1923 | .procname = "uuid", |
1924 | .maxlen = 16, | |
1925 | .mode = 0444, | |
6d456111 | 1926 | .proc_handler = proc_do_uuid, |
1da177e4 | 1927 | }, |
43759d4f TT |
1928 | #ifdef ADD_INTERRUPT_BENCH |
1929 | { | |
1930 | .procname = "add_interrupt_avg_cycles", | |
1931 | .data = &avg_cycles, | |
1932 | .maxlen = sizeof(avg_cycles), | |
1933 | .mode = 0444, | |
1934 | .proc_handler = proc_doulongvec_minmax, | |
1935 | }, | |
1936 | { | |
1937 | .procname = "add_interrupt_avg_deviation", | |
1938 | .data = &avg_deviation, | |
1939 | .maxlen = sizeof(avg_deviation), | |
1940 | .mode = 0444, | |
1941 | .proc_handler = proc_doulongvec_minmax, | |
1942 | }, | |
1943 | #endif | |
894d2491 | 1944 | { } |
1da177e4 LT |
1945 | }; |
1946 | #endif /* CONFIG_SYSCTL */ | |
1947 | ||
6e5714ea | 1948 | static u32 random_int_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned; |
1da177e4 | 1949 | |
47d06e53 | 1950 | int random_int_secret_init(void) |
1da177e4 | 1951 | { |
6e5714ea | 1952 | get_random_bytes(random_int_secret, sizeof(random_int_secret)); |
1da177e4 LT |
1953 | return 0; |
1954 | } | |
1da177e4 | 1955 | |
b1132dea EB |
1956 | static DEFINE_PER_CPU(__u32 [MD5_DIGEST_WORDS], get_random_int_hash) |
1957 | __aligned(sizeof(unsigned long)); | |
1958 | ||
1da177e4 LT |
1959 | /* |
1960 | * Get a random word for internal kernel use only. Similar to urandom but | |
1961 | * with the goal of minimal entropy pool depletion. As a result, the random | |
1962 | * value is not cryptographically secure but for several uses the cost of | |
1963 | * depleting entropy is too high | |
1964 | */ | |
1965 | unsigned int get_random_int(void) | |
1966 | { | |
63d77173 | 1967 | __u32 *hash; |
6e5714ea | 1968 | unsigned int ret; |
8a0a9bd4 | 1969 | |
63d77173 PA |
1970 | if (arch_get_random_int(&ret)) |
1971 | return ret; | |
1972 | ||
1973 | hash = get_cpu_var(get_random_int_hash); | |
8a0a9bd4 | 1974 | |
61875f30 | 1975 | hash[0] += current->pid + jiffies + random_get_entropy(); |
6e5714ea DM |
1976 | md5_transform(hash, random_int_secret); |
1977 | ret = hash[0]; | |
8a0a9bd4 LT |
1978 | put_cpu_var(get_random_int_hash); |
1979 | ||
1980 | return ret; | |
1da177e4 | 1981 | } |
16c7fa05 | 1982 | EXPORT_SYMBOL(get_random_int); |
1da177e4 | 1983 | |
ec9ee4ac DC |
1984 | /* |
1985 | * Same as get_random_int(), but returns unsigned long. | |
1986 | */ | |
1987 | unsigned long get_random_long(void) | |
1988 | { | |
1989 | __u32 *hash; | |
1990 | unsigned long ret; | |
1991 | ||
1992 | if (arch_get_random_long(&ret)) | |
1993 | return ret; | |
1994 | ||
1995 | hash = get_cpu_var(get_random_int_hash); | |
1996 | ||
1997 | hash[0] += current->pid + jiffies + random_get_entropy(); | |
1998 | md5_transform(hash, random_int_secret); | |
1999 | ret = *(unsigned long *)hash; | |
2000 | put_cpu_var(get_random_int_hash); | |
2001 | ||
2002 | return ret; | |
2003 | } | |
2004 | EXPORT_SYMBOL(get_random_long); | |
2005 | ||
1da177e4 LT |
2006 | /* |
2007 | * randomize_range() returns a start address such that | |
2008 | * | |
2009 | * [...... <range> .....] | |
2010 | * start end | |
2011 | * | |
2012 | * a <range> with size "len" starting at the return value is inside in the | |
2013 | * area defined by [start, end], but is otherwise randomized. | |
2014 | */ | |
2015 | unsigned long | |
2016 | randomize_range(unsigned long start, unsigned long end, unsigned long len) | |
2017 | { | |
2018 | unsigned long range = end - len - start; | |
2019 | ||
2020 | if (end <= start + len) | |
2021 | return 0; | |
2022 | return PAGE_ALIGN(get_random_int() % range + start); | |
2023 | } | |
c84dbf61 TD |
2024 | |
2025 | /* Interface for in-kernel drivers of true hardware RNGs. | |
2026 | * Those devices may produce endless random bits and will be throttled | |
2027 | * when our pool is full. | |
2028 | */ | |
2029 | void add_hwgenerator_randomness(const char *buffer, size_t count, | |
2030 | size_t entropy) | |
2031 | { | |
2032 | struct entropy_store *poolp = &input_pool; | |
2033 | ||
e192be9d TT |
2034 | if (!crng_ready()) { |
2035 | crng_fast_load(buffer, count); | |
2036 | return; | |
3371f3da | 2037 | } |
e192be9d TT |
2038 | |
2039 | /* Suspend writing if we're above the trickle threshold. | |
2040 | * We'll be woken up again once below random_write_wakeup_thresh, | |
2041 | * or when the calling thread is about to terminate. | |
2042 | */ | |
2043 | wait_event_interruptible(random_write_wait, kthread_should_stop() || | |
2044 | ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits); | |
c84dbf61 TD |
2045 | mix_pool_bytes(poolp, buffer, count); |
2046 | credit_entropy_bits(poolp, entropy); | |
2047 | } | |
2048 | EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); |