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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 | * | |
128 | * void add_input_randomness(unsigned int type, unsigned int code, | |
129 | * unsigned int value); | |
130 | * void add_interrupt_randomness(int irq); | |
442a4fff | 131 | * void add_disk_randomness(struct gendisk *disk); |
1da177e4 LT |
132 | * |
133 | * add_input_randomness() uses the input layer interrupt timing, as well as | |
134 | * the event type information from the hardware. | |
135 | * | |
136 | * add_interrupt_randomness() uses the inter-interrupt timing as random | |
137 | * inputs to the entropy pool. Note that not all interrupts are good | |
138 | * sources of randomness! For example, the timer interrupts is not a | |
139 | * good choice, because the periodicity of the interrupts is too | |
442a4fff JW |
140 | * regular, and hence predictable to an attacker. Network Interface |
141 | * Controller interrupts are a better measure, since the timing of the | |
142 | * NIC interrupts are more unpredictable. | |
143 | * | |
144 | * add_disk_randomness() uses what amounts to the seek time of block | |
145 | * layer request events, on a per-disk_devt basis, as input to the | |
146 | * entropy pool. Note that high-speed solid state drives with very low | |
147 | * seek times do not make for good sources of entropy, as their seek | |
148 | * times are usually fairly consistent. | |
1da177e4 LT |
149 | * |
150 | * All of these routines try to estimate how many bits of randomness a | |
151 | * particular randomness source. They do this by keeping track of the | |
152 | * first and second order deltas of the event timings. | |
153 | * | |
154 | * Ensuring unpredictability at system startup | |
155 | * ============================================ | |
156 | * | |
157 | * When any operating system starts up, it will go through a sequence | |
158 | * of actions that are fairly predictable by an adversary, especially | |
159 | * if the start-up does not involve interaction with a human operator. | |
160 | * This reduces the actual number of bits of unpredictability in the | |
161 | * entropy pool below the value in entropy_count. In order to | |
162 | * counteract this effect, it helps to carry information in the | |
163 | * entropy pool across shut-downs and start-ups. To do this, put the | |
164 | * following lines an appropriate script which is run during the boot | |
165 | * sequence: | |
166 | * | |
167 | * echo "Initializing random number generator..." | |
168 | * random_seed=/var/run/random-seed | |
169 | * # Carry a random seed from start-up to start-up | |
170 | * # Load and then save the whole entropy pool | |
171 | * if [ -f $random_seed ]; then | |
172 | * cat $random_seed >/dev/urandom | |
173 | * else | |
174 | * touch $random_seed | |
175 | * fi | |
176 | * chmod 600 $random_seed | |
177 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 | |
178 | * | |
179 | * and the following lines in an appropriate script which is run as | |
180 | * the system is shutdown: | |
181 | * | |
182 | * # Carry a random seed from shut-down to start-up | |
183 | * # Save the whole entropy pool | |
184 | * echo "Saving random seed..." | |
185 | * random_seed=/var/run/random-seed | |
186 | * touch $random_seed | |
187 | * chmod 600 $random_seed | |
188 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 | |
189 | * | |
190 | * For example, on most modern systems using the System V init | |
191 | * scripts, such code fragments would be found in | |
192 | * /etc/rc.d/init.d/random. On older Linux systems, the correct script | |
193 | * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0. | |
194 | * | |
195 | * Effectively, these commands cause the contents of the entropy pool | |
196 | * to be saved at shut-down time and reloaded into the entropy pool at | |
197 | * start-up. (The 'dd' in the addition to the bootup script is to | |
198 | * make sure that /etc/random-seed is different for every start-up, | |
199 | * even if the system crashes without executing rc.0.) Even with | |
200 | * complete knowledge of the start-up activities, predicting the state | |
201 | * of the entropy pool requires knowledge of the previous history of | |
202 | * the system. | |
203 | * | |
204 | * Configuring the /dev/random driver under Linux | |
205 | * ============================================== | |
206 | * | |
207 | * The /dev/random driver under Linux uses minor numbers 8 and 9 of | |
208 | * the /dev/mem major number (#1). So if your system does not have | |
209 | * /dev/random and /dev/urandom created already, they can be created | |
210 | * by using the commands: | |
211 | * | |
212 | * mknod /dev/random c 1 8 | |
213 | * mknod /dev/urandom c 1 9 | |
214 | * | |
215 | * Acknowledgements: | |
216 | * ================= | |
217 | * | |
218 | * Ideas for constructing this random number generator were derived | |
219 | * from Pretty Good Privacy's random number generator, and from private | |
220 | * discussions with Phil Karn. Colin Plumb provided a faster random | |
221 | * number generator, which speed up the mixing function of the entropy | |
222 | * pool, taken from PGPfone. Dale Worley has also contributed many | |
223 | * useful ideas and suggestions to improve this driver. | |
224 | * | |
225 | * Any flaws in the design are solely my responsibility, and should | |
226 | * not be attributed to the Phil, Colin, or any of authors of PGP. | |
227 | * | |
228 | * Further background information on this topic may be obtained from | |
229 | * RFC 1750, "Randomness Recommendations for Security", by Donald | |
230 | * Eastlake, Steve Crocker, and Jeff Schiller. | |
231 | */ | |
232 | ||
233 | #include <linux/utsname.h> | |
1da177e4 LT |
234 | #include <linux/module.h> |
235 | #include <linux/kernel.h> | |
236 | #include <linux/major.h> | |
237 | #include <linux/string.h> | |
238 | #include <linux/fcntl.h> | |
239 | #include <linux/slab.h> | |
240 | #include <linux/random.h> | |
241 | #include <linux/poll.h> | |
242 | #include <linux/init.h> | |
243 | #include <linux/fs.h> | |
244 | #include <linux/genhd.h> | |
245 | #include <linux/interrupt.h> | |
27ac792c | 246 | #include <linux/mm.h> |
1da177e4 LT |
247 | #include <linux/spinlock.h> |
248 | #include <linux/percpu.h> | |
249 | #include <linux/cryptohash.h> | |
5b739ef8 | 250 | #include <linux/fips.h> |
1da177e4 | 251 | |
d178a1eb YL |
252 | #ifdef CONFIG_GENERIC_HARDIRQS |
253 | # include <linux/irq.h> | |
254 | #endif | |
255 | ||
1da177e4 LT |
256 | #include <asm/processor.h> |
257 | #include <asm/uaccess.h> | |
258 | #include <asm/irq.h> | |
259 | #include <asm/io.h> | |
260 | ||
261 | /* | |
262 | * Configuration information | |
263 | */ | |
264 | #define INPUT_POOL_WORDS 128 | |
265 | #define OUTPUT_POOL_WORDS 32 | |
266 | #define SEC_XFER_SIZE 512 | |
e954bc91 | 267 | #define EXTRACT_SIZE 10 |
1da177e4 LT |
268 | |
269 | /* | |
270 | * The minimum number of bits of entropy before we wake up a read on | |
271 | * /dev/random. Should be enough to do a significant reseed. | |
272 | */ | |
273 | static int random_read_wakeup_thresh = 64; | |
274 | ||
275 | /* | |
276 | * If the entropy count falls under this number of bits, then we | |
277 | * should wake up processes which are selecting or polling on write | |
278 | * access to /dev/random. | |
279 | */ | |
280 | static int random_write_wakeup_thresh = 128; | |
281 | ||
282 | /* | |
283 | * When the input pool goes over trickle_thresh, start dropping most | |
284 | * samples to avoid wasting CPU time and reduce lock contention. | |
285 | */ | |
286 | ||
6c036527 | 287 | static int trickle_thresh __read_mostly = INPUT_POOL_WORDS * 28; |
1da177e4 | 288 | |
90b75ee5 | 289 | static DEFINE_PER_CPU(int, trickle_count); |
1da177e4 LT |
290 | |
291 | /* | |
292 | * A pool of size .poolwords is stirred with a primitive polynomial | |
293 | * of degree .poolwords over GF(2). The taps for various sizes are | |
294 | * defined below. They are chosen to be evenly spaced (minimum RMS | |
295 | * distance from evenly spaced; the numbers in the comments are a | |
296 | * scaled squared error sum) except for the last tap, which is 1 to | |
297 | * get the twisting happening as fast as possible. | |
298 | */ | |
299 | static struct poolinfo { | |
300 | int poolwords; | |
301 | int tap1, tap2, tap3, tap4, tap5; | |
302 | } poolinfo_table[] = { | |
303 | /* x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 -- 105 */ | |
304 | { 128, 103, 76, 51, 25, 1 }, | |
305 | /* x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 -- 15 */ | |
306 | { 32, 26, 20, 14, 7, 1 }, | |
307 | #if 0 | |
308 | /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */ | |
309 | { 2048, 1638, 1231, 819, 411, 1 }, | |
310 | ||
311 | /* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */ | |
312 | { 1024, 817, 615, 412, 204, 1 }, | |
313 | ||
314 | /* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */ | |
315 | { 1024, 819, 616, 410, 207, 2 }, | |
316 | ||
317 | /* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */ | |
318 | { 512, 411, 308, 208, 104, 1 }, | |
319 | ||
320 | /* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */ | |
321 | { 512, 409, 307, 206, 102, 2 }, | |
322 | /* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */ | |
323 | { 512, 409, 309, 205, 103, 2 }, | |
324 | ||
325 | /* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */ | |
326 | { 256, 205, 155, 101, 52, 1 }, | |
327 | ||
328 | /* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */ | |
329 | { 128, 103, 78, 51, 27, 2 }, | |
330 | ||
331 | /* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */ | |
332 | { 64, 52, 39, 26, 14, 1 }, | |
333 | #endif | |
334 | }; | |
335 | ||
336 | #define POOLBITS poolwords*32 | |
337 | #define POOLBYTES poolwords*4 | |
338 | ||
339 | /* | |
340 | * For the purposes of better mixing, we use the CRC-32 polynomial as | |
341 | * well to make a twisted Generalized Feedback Shift Reigster | |
342 | * | |
343 | * (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR generators. ACM | |
344 | * Transactions on Modeling and Computer Simulation 2(3):179-194. | |
345 | * Also see M. Matsumoto & Y. Kurita, 1994. Twisted GFSR generators | |
346 | * II. ACM Transactions on Mdeling and Computer Simulation 4:254-266) | |
347 | * | |
348 | * Thanks to Colin Plumb for suggesting this. | |
349 | * | |
350 | * We have not analyzed the resultant polynomial to prove it primitive; | |
351 | * in fact it almost certainly isn't. Nonetheless, the irreducible factors | |
352 | * of a random large-degree polynomial over GF(2) are more than large enough | |
353 | * that periodicity is not a concern. | |
354 | * | |
355 | * The input hash is much less sensitive than the output hash. All | |
356 | * that we want of it is that it be a good non-cryptographic hash; | |
357 | * i.e. it not produce collisions when fed "random" data of the sort | |
358 | * we expect to see. As long as the pool state differs for different | |
359 | * inputs, we have preserved the input entropy and done a good job. | |
360 | * The fact that an intelligent attacker can construct inputs that | |
361 | * will produce controlled alterations to the pool's state is not | |
362 | * important because we don't consider such inputs to contribute any | |
363 | * randomness. The only property we need with respect to them is that | |
364 | * the attacker can't increase his/her knowledge of the pool's state. | |
365 | * Since all additions are reversible (knowing the final state and the | |
366 | * input, you can reconstruct the initial state), if an attacker has | |
367 | * any uncertainty about the initial state, he/she can only shuffle | |
368 | * that uncertainty about, but never cause any collisions (which would | |
369 | * decrease the uncertainty). | |
370 | * | |
371 | * The chosen system lets the state of the pool be (essentially) the input | |
372 | * modulo the generator polymnomial. Now, for random primitive polynomials, | |
373 | * this is a universal class of hash functions, meaning that the chance | |
374 | * of a collision is limited by the attacker's knowledge of the generator | |
375 | * polynomail, so if it is chosen at random, an attacker can never force | |
376 | * a collision. Here, we use a fixed polynomial, but we *can* assume that | |
377 | * ###--> it is unknown to the processes generating the input entropy. <-### | |
378 | * Because of this important property, this is a good, collision-resistant | |
379 | * hash; hash collisions will occur no more often than chance. | |
380 | */ | |
381 | ||
382 | /* | |
383 | * Static global variables | |
384 | */ | |
385 | static DECLARE_WAIT_QUEUE_HEAD(random_read_wait); | |
386 | static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); | |
9a6f70bb | 387 | static struct fasync_struct *fasync; |
1da177e4 LT |
388 | |
389 | #if 0 | |
90ab5ee9 | 390 | static bool debug; |
1da177e4 | 391 | module_param(debug, bool, 0644); |
90b75ee5 MM |
392 | #define DEBUG_ENT(fmt, arg...) do { \ |
393 | if (debug) \ | |
394 | printk(KERN_DEBUG "random %04d %04d %04d: " \ | |
395 | fmt,\ | |
396 | input_pool.entropy_count,\ | |
397 | blocking_pool.entropy_count,\ | |
398 | nonblocking_pool.entropy_count,\ | |
399 | ## arg); } while (0) | |
1da177e4 LT |
400 | #else |
401 | #define DEBUG_ENT(fmt, arg...) do {} while (0) | |
402 | #endif | |
403 | ||
404 | /********************************************************************** | |
405 | * | |
406 | * OS independent entropy store. Here are the functions which handle | |
407 | * storing entropy in an entropy pool. | |
408 | * | |
409 | **********************************************************************/ | |
410 | ||
411 | struct entropy_store; | |
412 | struct entropy_store { | |
43358209 | 413 | /* read-only data: */ |
1da177e4 LT |
414 | struct poolinfo *poolinfo; |
415 | __u32 *pool; | |
416 | const char *name; | |
1da177e4 | 417 | struct entropy_store *pull; |
4015d9a8 | 418 | int limit; |
1da177e4 LT |
419 | |
420 | /* read-write data: */ | |
43358209 | 421 | spinlock_t lock; |
1da177e4 | 422 | unsigned add_ptr; |
cda796a3 | 423 | int entropy_count; |
1da177e4 | 424 | int input_rotate; |
e954bc91 | 425 | __u8 last_data[EXTRACT_SIZE]; |
1da177e4 LT |
426 | }; |
427 | ||
428 | static __u32 input_pool_data[INPUT_POOL_WORDS]; | |
429 | static __u32 blocking_pool_data[OUTPUT_POOL_WORDS]; | |
430 | static __u32 nonblocking_pool_data[OUTPUT_POOL_WORDS]; | |
431 | ||
432 | static struct entropy_store input_pool = { | |
433 | .poolinfo = &poolinfo_table[0], | |
434 | .name = "input", | |
435 | .limit = 1, | |
e4d91918 | 436 | .lock = __SPIN_LOCK_UNLOCKED(&input_pool.lock), |
1da177e4 LT |
437 | .pool = input_pool_data |
438 | }; | |
439 | ||
440 | static struct entropy_store blocking_pool = { | |
441 | .poolinfo = &poolinfo_table[1], | |
442 | .name = "blocking", | |
443 | .limit = 1, | |
444 | .pull = &input_pool, | |
e4d91918 | 445 | .lock = __SPIN_LOCK_UNLOCKED(&blocking_pool.lock), |
1da177e4 LT |
446 | .pool = blocking_pool_data |
447 | }; | |
448 | ||
449 | static struct entropy_store nonblocking_pool = { | |
450 | .poolinfo = &poolinfo_table[1], | |
451 | .name = "nonblocking", | |
452 | .pull = &input_pool, | |
e4d91918 | 453 | .lock = __SPIN_LOCK_UNLOCKED(&nonblocking_pool.lock), |
1da177e4 LT |
454 | .pool = nonblocking_pool_data |
455 | }; | |
456 | ||
457 | /* | |
e68e5b66 | 458 | * This function adds bytes into the entropy "pool". It does not |
1da177e4 | 459 | * update the entropy estimate. The caller should call |
adc782da | 460 | * credit_entropy_bits if this is appropriate. |
1da177e4 LT |
461 | * |
462 | * The pool is stirred with a primitive polynomial of the appropriate | |
463 | * degree, and then twisted. We twist by three bits at a time because | |
464 | * it's cheap to do so and helps slightly in the expected case where | |
465 | * the entropy is concentrated in the low-order bits. | |
466 | */ | |
e68e5b66 MM |
467 | static void mix_pool_bytes_extract(struct entropy_store *r, const void *in, |
468 | int nbytes, __u8 out[64]) | |
1da177e4 LT |
469 | { |
470 | static __u32 const twist_table[8] = { | |
471 | 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158, | |
472 | 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 }; | |
993ba211 | 473 | unsigned long i, j, tap1, tap2, tap3, tap4, tap5; |
feee7697 | 474 | int input_rotate; |
1da177e4 | 475 | int wordmask = r->poolinfo->poolwords - 1; |
e68e5b66 | 476 | const char *bytes = in; |
6d38b827 | 477 | __u32 w; |
1da177e4 LT |
478 | unsigned long flags; |
479 | ||
480 | /* Taps are constant, so we can load them without holding r->lock. */ | |
481 | tap1 = r->poolinfo->tap1; | |
482 | tap2 = r->poolinfo->tap2; | |
483 | tap3 = r->poolinfo->tap3; | |
484 | tap4 = r->poolinfo->tap4; | |
485 | tap5 = r->poolinfo->tap5; | |
1da177e4 LT |
486 | |
487 | spin_lock_irqsave(&r->lock, flags); | |
1da177e4 | 488 | input_rotate = r->input_rotate; |
993ba211 | 489 | i = r->add_ptr; |
1da177e4 | 490 | |
e68e5b66 MM |
491 | /* mix one byte at a time to simplify size handling and churn faster */ |
492 | while (nbytes--) { | |
493 | w = rol32(*bytes++, input_rotate & 31); | |
993ba211 | 494 | i = (i - 1) & wordmask; |
1da177e4 LT |
495 | |
496 | /* XOR in the various taps */ | |
993ba211 | 497 | w ^= r->pool[i]; |
1da177e4 LT |
498 | w ^= r->pool[(i + tap1) & wordmask]; |
499 | w ^= r->pool[(i + tap2) & wordmask]; | |
500 | w ^= r->pool[(i + tap3) & wordmask]; | |
501 | w ^= r->pool[(i + tap4) & wordmask]; | |
502 | w ^= r->pool[(i + tap5) & wordmask]; | |
993ba211 MM |
503 | |
504 | /* Mix the result back in with a twist */ | |
1da177e4 | 505 | r->pool[i] = (w >> 3) ^ twist_table[w & 7]; |
feee7697 MM |
506 | |
507 | /* | |
508 | * Normally, we add 7 bits of rotation to the pool. | |
509 | * At the beginning of the pool, add an extra 7 bits | |
510 | * rotation, so that successive passes spread the | |
511 | * input bits across the pool evenly. | |
512 | */ | |
513 | input_rotate += i ? 7 : 14; | |
1da177e4 LT |
514 | } |
515 | ||
516 | r->input_rotate = input_rotate; | |
993ba211 | 517 | r->add_ptr = i; |
1da177e4 | 518 | |
993ba211 MM |
519 | if (out) |
520 | for (j = 0; j < 16; j++) | |
e68e5b66 | 521 | ((__u32 *)out)[j] = r->pool[(i - j) & wordmask]; |
1da177e4 LT |
522 | |
523 | spin_unlock_irqrestore(&r->lock, flags); | |
524 | } | |
525 | ||
e68e5b66 | 526 | static void mix_pool_bytes(struct entropy_store *r, const void *in, int bytes) |
1da177e4 | 527 | { |
e68e5b66 | 528 | mix_pool_bytes_extract(r, in, bytes, NULL); |
1da177e4 LT |
529 | } |
530 | ||
531 | /* | |
532 | * Credit (or debit) the entropy store with n bits of entropy | |
533 | */ | |
adc782da | 534 | static void credit_entropy_bits(struct entropy_store *r, int nbits) |
1da177e4 LT |
535 | { |
536 | unsigned long flags; | |
8b76f46a | 537 | int entropy_count; |
1da177e4 | 538 | |
adc782da MM |
539 | if (!nbits) |
540 | return; | |
541 | ||
1da177e4 LT |
542 | spin_lock_irqsave(&r->lock, flags); |
543 | ||
adc782da | 544 | DEBUG_ENT("added %d entropy credits to %s\n", nbits, r->name); |
8b76f46a AM |
545 | entropy_count = r->entropy_count; |
546 | entropy_count += nbits; | |
547 | if (entropy_count < 0) { | |
adc782da | 548 | DEBUG_ENT("negative entropy/overflow\n"); |
8b76f46a AM |
549 | entropy_count = 0; |
550 | } else if (entropy_count > r->poolinfo->POOLBITS) | |
551 | entropy_count = r->poolinfo->POOLBITS; | |
552 | r->entropy_count = entropy_count; | |
1da177e4 | 553 | |
88c730da | 554 | /* should we wake readers? */ |
8b76f46a | 555 | if (r == &input_pool && entropy_count >= random_read_wakeup_thresh) { |
88c730da | 556 | wake_up_interruptible(&random_read_wait); |
9a6f70bb JD |
557 | kill_fasync(&fasync, SIGIO, POLL_IN); |
558 | } | |
1da177e4 LT |
559 | spin_unlock_irqrestore(&r->lock, flags); |
560 | } | |
561 | ||
562 | /********************************************************************* | |
563 | * | |
564 | * Entropy input management | |
565 | * | |
566 | *********************************************************************/ | |
567 | ||
568 | /* There is one of these per entropy source */ | |
569 | struct timer_rand_state { | |
570 | cycles_t last_time; | |
90b75ee5 | 571 | long last_delta, last_delta2; |
1da177e4 LT |
572 | unsigned dont_count_entropy:1; |
573 | }; | |
574 | ||
d7e51e66 | 575 | #ifndef CONFIG_GENERIC_HARDIRQS |
2f983570 YL |
576 | |
577 | static struct timer_rand_state *irq_timer_state[NR_IRQS]; | |
578 | ||
579 | static struct timer_rand_state *get_timer_rand_state(unsigned int irq) | |
580 | { | |
581 | return irq_timer_state[irq]; | |
582 | } | |
583 | ||
584 | static void set_timer_rand_state(unsigned int irq, | |
585 | struct timer_rand_state *state) | |
586 | { | |
587 | irq_timer_state[irq] = state; | |
588 | } | |
589 | ||
590 | #else | |
591 | ||
592 | static struct timer_rand_state *get_timer_rand_state(unsigned int irq) | |
593 | { | |
594 | struct irq_desc *desc; | |
595 | ||
596 | desc = irq_to_desc(irq); | |
597 | ||
598 | return desc->timer_rand_state; | |
599 | } | |
600 | ||
601 | static void set_timer_rand_state(unsigned int irq, | |
602 | struct timer_rand_state *state) | |
603 | { | |
604 | struct irq_desc *desc; | |
605 | ||
606 | desc = irq_to_desc(irq); | |
607 | ||
608 | desc->timer_rand_state = state; | |
609 | } | |
0b8f1efa | 610 | #endif |
3060d6fe | 611 | |
3060d6fe YL |
612 | static struct timer_rand_state input_timer_state; |
613 | ||
1da177e4 LT |
614 | /* |
615 | * This function adds entropy to the entropy "pool" by using timing | |
616 | * delays. It uses the timer_rand_state structure to make an estimate | |
617 | * of how many bits of entropy this call has added to the pool. | |
618 | * | |
619 | * The number "num" is also added to the pool - it should somehow describe | |
620 | * the type of event which just happened. This is currently 0-255 for | |
621 | * keyboard scan codes, and 256 upwards for interrupts. | |
622 | * | |
623 | */ | |
624 | static void add_timer_randomness(struct timer_rand_state *state, unsigned num) | |
625 | { | |
626 | struct { | |
1da177e4 | 627 | long jiffies; |
cf833d0b | 628 | unsigned cycles; |
1da177e4 LT |
629 | unsigned num; |
630 | } sample; | |
631 | long delta, delta2, delta3; | |
632 | ||
633 | preempt_disable(); | |
634 | /* if over the trickle threshold, use only 1 in 4096 samples */ | |
635 | if (input_pool.entropy_count > trickle_thresh && | |
b29c617a | 636 | ((__this_cpu_inc_return(trickle_count) - 1) & 0xfff)) |
1da177e4 LT |
637 | goto out; |
638 | ||
639 | sample.jiffies = jiffies; | |
cf833d0b LT |
640 | |
641 | /* Use arch random value, fall back to cycles */ | |
642 | if (!arch_get_random_int(&sample.cycles)) | |
643 | sample.cycles = get_cycles(); | |
644 | ||
1da177e4 | 645 | sample.num = num; |
e68e5b66 | 646 | mix_pool_bytes(&input_pool, &sample, sizeof(sample)); |
1da177e4 LT |
647 | |
648 | /* | |
649 | * Calculate number of bits of randomness we probably added. | |
650 | * We take into account the first, second and third-order deltas | |
651 | * in order to make our estimate. | |
652 | */ | |
653 | ||
654 | if (!state->dont_count_entropy) { | |
655 | delta = sample.jiffies - state->last_time; | |
656 | state->last_time = sample.jiffies; | |
657 | ||
658 | delta2 = delta - state->last_delta; | |
659 | state->last_delta = delta; | |
660 | ||
661 | delta3 = delta2 - state->last_delta2; | |
662 | state->last_delta2 = delta2; | |
663 | ||
664 | if (delta < 0) | |
665 | delta = -delta; | |
666 | if (delta2 < 0) | |
667 | delta2 = -delta2; | |
668 | if (delta3 < 0) | |
669 | delta3 = -delta3; | |
670 | if (delta > delta2) | |
671 | delta = delta2; | |
672 | if (delta > delta3) | |
673 | delta = delta3; | |
674 | ||
675 | /* | |
676 | * delta is now minimum absolute delta. | |
677 | * Round down by 1 bit on general principles, | |
678 | * and limit entropy entimate to 12 bits. | |
679 | */ | |
adc782da MM |
680 | credit_entropy_bits(&input_pool, |
681 | min_t(int, fls(delta>>1), 11)); | |
1da177e4 | 682 | } |
1da177e4 LT |
683 | out: |
684 | preempt_enable(); | |
685 | } | |
686 | ||
d251575a | 687 | void add_input_randomness(unsigned int type, unsigned int code, |
1da177e4 LT |
688 | unsigned int value) |
689 | { | |
690 | static unsigned char last_value; | |
691 | ||
692 | /* ignore autorepeat and the like */ | |
693 | if (value == last_value) | |
694 | return; | |
695 | ||
696 | DEBUG_ENT("input event\n"); | |
697 | last_value = value; | |
698 | add_timer_randomness(&input_timer_state, | |
699 | (type << 4) ^ code ^ (code >> 4) ^ value); | |
700 | } | |
80fc9f53 | 701 | EXPORT_SYMBOL_GPL(add_input_randomness); |
1da177e4 LT |
702 | |
703 | void add_interrupt_randomness(int irq) | |
704 | { | |
3060d6fe YL |
705 | struct timer_rand_state *state; |
706 | ||
707 | state = get_timer_rand_state(irq); | |
708 | ||
709 | if (state == NULL) | |
1da177e4 LT |
710 | return; |
711 | ||
712 | DEBUG_ENT("irq event %d\n", irq); | |
3060d6fe | 713 | add_timer_randomness(state, 0x100 + irq); |
1da177e4 LT |
714 | } |
715 | ||
9361401e | 716 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
717 | void add_disk_randomness(struct gendisk *disk) |
718 | { | |
719 | if (!disk || !disk->random) | |
720 | return; | |
721 | /* first major is 1, so we get >= 0x200 here */ | |
f331c029 TH |
722 | DEBUG_ENT("disk event %d:%d\n", |
723 | MAJOR(disk_devt(disk)), MINOR(disk_devt(disk))); | |
1da177e4 | 724 | |
f331c029 | 725 | add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); |
1da177e4 | 726 | } |
9361401e | 727 | #endif |
1da177e4 | 728 | |
1da177e4 LT |
729 | /********************************************************************* |
730 | * | |
731 | * Entropy extraction routines | |
732 | * | |
733 | *********************************************************************/ | |
734 | ||
90b75ee5 | 735 | static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
1da177e4 LT |
736 | size_t nbytes, int min, int rsvd); |
737 | ||
738 | /* | |
25985edc | 739 | * This utility inline function is responsible for transferring entropy |
1da177e4 LT |
740 | * from the primary pool to the secondary extraction pool. We make |
741 | * sure we pull enough for a 'catastrophic reseed'. | |
742 | */ | |
743 | static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes) | |
744 | { | |
745 | __u32 tmp[OUTPUT_POOL_WORDS]; | |
746 | ||
747 | if (r->pull && r->entropy_count < nbytes * 8 && | |
748 | r->entropy_count < r->poolinfo->POOLBITS) { | |
5a021e9f | 749 | /* If we're limited, always leave two wakeup worth's BITS */ |
1da177e4 | 750 | int rsvd = r->limit ? 0 : random_read_wakeup_thresh/4; |
5a021e9f MM |
751 | int bytes = nbytes; |
752 | ||
753 | /* pull at least as many as BYTES as wakeup BITS */ | |
754 | bytes = max_t(int, bytes, random_read_wakeup_thresh / 8); | |
755 | /* but never more than the buffer size */ | |
756 | bytes = min_t(int, bytes, sizeof(tmp)); | |
1da177e4 LT |
757 | |
758 | DEBUG_ENT("going to reseed %s with %d bits " | |
759 | "(%d of %d requested)\n", | |
760 | r->name, bytes * 8, nbytes * 8, r->entropy_count); | |
761 | ||
90b75ee5 MM |
762 | bytes = extract_entropy(r->pull, tmp, bytes, |
763 | random_read_wakeup_thresh / 8, rsvd); | |
e68e5b66 | 764 | mix_pool_bytes(r, tmp, bytes); |
adc782da | 765 | credit_entropy_bits(r, bytes*8); |
1da177e4 LT |
766 | } |
767 | } | |
768 | ||
769 | /* | |
770 | * These functions extracts randomness from the "entropy pool", and | |
771 | * returns it in a buffer. | |
772 | * | |
773 | * The min parameter specifies the minimum amount we can pull before | |
774 | * failing to avoid races that defeat catastrophic reseeding while the | |
775 | * reserved parameter indicates how much entropy we must leave in the | |
776 | * pool after each pull to avoid starving other readers. | |
777 | * | |
778 | * Note: extract_entropy() assumes that .poolwords is a multiple of 16 words. | |
779 | */ | |
780 | ||
781 | static size_t account(struct entropy_store *r, size_t nbytes, int min, | |
782 | int reserved) | |
783 | { | |
784 | unsigned long flags; | |
785 | ||
1da177e4 LT |
786 | /* Hold lock while accounting */ |
787 | spin_lock_irqsave(&r->lock, flags); | |
788 | ||
cda796a3 | 789 | BUG_ON(r->entropy_count > r->poolinfo->POOLBITS); |
1da177e4 LT |
790 | DEBUG_ENT("trying to extract %d bits from %s\n", |
791 | nbytes * 8, r->name); | |
792 | ||
793 | /* Can we pull enough? */ | |
794 | if (r->entropy_count / 8 < min + reserved) { | |
795 | nbytes = 0; | |
796 | } else { | |
797 | /* If limited, never pull more than available */ | |
798 | if (r->limit && nbytes + reserved >= r->entropy_count / 8) | |
799 | nbytes = r->entropy_count/8 - reserved; | |
800 | ||
90b75ee5 | 801 | if (r->entropy_count / 8 >= nbytes + reserved) |
1da177e4 LT |
802 | r->entropy_count -= nbytes*8; |
803 | else | |
804 | r->entropy_count = reserved; | |
805 | ||
9a6f70bb | 806 | if (r->entropy_count < random_write_wakeup_thresh) { |
1da177e4 | 807 | wake_up_interruptible(&random_write_wait); |
9a6f70bb JD |
808 | kill_fasync(&fasync, SIGIO, POLL_OUT); |
809 | } | |
1da177e4 LT |
810 | } |
811 | ||
812 | DEBUG_ENT("debiting %d entropy credits from %s%s\n", | |
813 | nbytes * 8, r->name, r->limit ? "" : " (unlimited)"); | |
814 | ||
815 | spin_unlock_irqrestore(&r->lock, flags); | |
816 | ||
817 | return nbytes; | |
818 | } | |
819 | ||
820 | static void extract_buf(struct entropy_store *r, __u8 *out) | |
821 | { | |
602b6aee | 822 | int i; |
e68e5b66 MM |
823 | __u32 hash[5], workspace[SHA_WORKSPACE_WORDS]; |
824 | __u8 extract[64]; | |
1da177e4 | 825 | |
1c0ad3d4 | 826 | /* Generate a hash across the pool, 16 words (512 bits) at a time */ |
ffd8d3fa | 827 | sha_init(hash); |
1c0ad3d4 MM |
828 | for (i = 0; i < r->poolinfo->poolwords; i += 16) |
829 | sha_transform(hash, (__u8 *)(r->pool + i), workspace); | |
830 | ||
1da177e4 | 831 | /* |
1c0ad3d4 MM |
832 | * We mix the hash back into the pool to prevent backtracking |
833 | * attacks (where the attacker knows the state of the pool | |
834 | * plus the current outputs, and attempts to find previous | |
835 | * ouputs), unless the hash function can be inverted. By | |
836 | * mixing at least a SHA1 worth of hash data back, we make | |
837 | * brute-forcing the feedback as hard as brute-forcing the | |
838 | * hash. | |
1da177e4 | 839 | */ |
e68e5b66 | 840 | mix_pool_bytes_extract(r, hash, sizeof(hash), extract); |
1da177e4 LT |
841 | |
842 | /* | |
1c0ad3d4 MM |
843 | * To avoid duplicates, we atomically extract a portion of the |
844 | * pool while mixing, and hash one final time. | |
1da177e4 | 845 | */ |
e68e5b66 | 846 | sha_transform(hash, extract, workspace); |
ffd8d3fa MM |
847 | memset(extract, 0, sizeof(extract)); |
848 | memset(workspace, 0, sizeof(workspace)); | |
1da177e4 LT |
849 | |
850 | /* | |
1c0ad3d4 MM |
851 | * In case the hash function has some recognizable output |
852 | * pattern, we fold it in half. Thus, we always feed back | |
853 | * twice as much data as we output. | |
1da177e4 | 854 | */ |
ffd8d3fa MM |
855 | hash[0] ^= hash[3]; |
856 | hash[1] ^= hash[4]; | |
857 | hash[2] ^= rol32(hash[2], 16); | |
858 | memcpy(out, hash, EXTRACT_SIZE); | |
859 | memset(hash, 0, sizeof(hash)); | |
1da177e4 LT |
860 | } |
861 | ||
90b75ee5 | 862 | static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
1da177e4 LT |
863 | size_t nbytes, int min, int reserved) |
864 | { | |
865 | ssize_t ret = 0, i; | |
866 | __u8 tmp[EXTRACT_SIZE]; | |
5b739ef8 | 867 | unsigned long flags; |
1da177e4 LT |
868 | |
869 | xfer_secondary_pool(r, nbytes); | |
870 | nbytes = account(r, nbytes, min, reserved); | |
871 | ||
872 | while (nbytes) { | |
873 | extract_buf(r, tmp); | |
5b739ef8 | 874 | |
e954bc91 | 875 | if (fips_enabled) { |
5b739ef8 NH |
876 | spin_lock_irqsave(&r->lock, flags); |
877 | if (!memcmp(tmp, r->last_data, EXTRACT_SIZE)) | |
878 | panic("Hardware RNG duplicated output!\n"); | |
879 | memcpy(r->last_data, tmp, EXTRACT_SIZE); | |
880 | spin_unlock_irqrestore(&r->lock, flags); | |
881 | } | |
1da177e4 LT |
882 | i = min_t(int, nbytes, EXTRACT_SIZE); |
883 | memcpy(buf, tmp, i); | |
884 | nbytes -= i; | |
885 | buf += i; | |
886 | ret += i; | |
887 | } | |
888 | ||
889 | /* Wipe data just returned from memory */ | |
890 | memset(tmp, 0, sizeof(tmp)); | |
891 | ||
892 | return ret; | |
893 | } | |
894 | ||
895 | static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf, | |
896 | size_t nbytes) | |
897 | { | |
898 | ssize_t ret = 0, i; | |
899 | __u8 tmp[EXTRACT_SIZE]; | |
900 | ||
901 | xfer_secondary_pool(r, nbytes); | |
902 | nbytes = account(r, nbytes, 0, 0); | |
903 | ||
904 | while (nbytes) { | |
905 | if (need_resched()) { | |
906 | if (signal_pending(current)) { | |
907 | if (ret == 0) | |
908 | ret = -ERESTARTSYS; | |
909 | break; | |
910 | } | |
911 | schedule(); | |
912 | } | |
913 | ||
914 | extract_buf(r, tmp); | |
915 | i = min_t(int, nbytes, EXTRACT_SIZE); | |
916 | if (copy_to_user(buf, tmp, i)) { | |
917 | ret = -EFAULT; | |
918 | break; | |
919 | } | |
920 | ||
921 | nbytes -= i; | |
922 | buf += i; | |
923 | ret += i; | |
924 | } | |
925 | ||
926 | /* Wipe data just returned from memory */ | |
927 | memset(tmp, 0, sizeof(tmp)); | |
928 | ||
929 | return ret; | |
930 | } | |
931 | ||
932 | /* | |
933 | * This function is the exported kernel interface. It returns some | |
934 | * number of good random numbers, suitable for seeding TCP sequence | |
935 | * numbers, etc. | |
936 | */ | |
937 | void get_random_bytes(void *buf, int nbytes) | |
938 | { | |
63d77173 PA |
939 | char *p = buf; |
940 | ||
941 | while (nbytes) { | |
942 | unsigned long v; | |
943 | int chunk = min(nbytes, (int)sizeof(unsigned long)); | |
944 | ||
945 | if (!arch_get_random_long(&v)) | |
946 | break; | |
947 | ||
bd29e568 | 948 | memcpy(p, &v, chunk); |
63d77173 PA |
949 | p += chunk; |
950 | nbytes -= chunk; | |
951 | } | |
952 | ||
953 | extract_entropy(&nonblocking_pool, p, nbytes, 0, 0); | |
1da177e4 | 954 | } |
1da177e4 LT |
955 | EXPORT_SYMBOL(get_random_bytes); |
956 | ||
957 | /* | |
958 | * init_std_data - initialize pool with system data | |
959 | * | |
960 | * @r: pool to initialize | |
961 | * | |
962 | * This function clears the pool's entropy count and mixes some system | |
963 | * data into the pool to prepare it for use. The pool is not cleared | |
964 | * as that can only decrease the entropy in the pool. | |
965 | */ | |
966 | static void init_std_data(struct entropy_store *r) | |
967 | { | |
3e88bdff | 968 | int i; |
f8595815 | 969 | ktime_t now; |
1da177e4 LT |
970 | unsigned long flags; |
971 | ||
972 | spin_lock_irqsave(&r->lock, flags); | |
973 | r->entropy_count = 0; | |
974 | spin_unlock_irqrestore(&r->lock, flags); | |
975 | ||
f8595815 | 976 | now = ktime_get_real(); |
e68e5b66 | 977 | mix_pool_bytes(r, &now, sizeof(now)); |
2dac8e54 | 978 | for (i = r->poolinfo->POOLBYTES; i > 0; i -= sizeof flags) { |
3e88bdff TT |
979 | if (!arch_get_random_long(&flags)) |
980 | break; | |
981 | mix_pool_bytes(r, &flags, sizeof(flags)); | |
982 | } | |
e68e5b66 | 983 | mix_pool_bytes(r, utsname(), sizeof(*(utsname()))); |
1da177e4 LT |
984 | } |
985 | ||
53c3f63e | 986 | static int rand_initialize(void) |
1da177e4 LT |
987 | { |
988 | init_std_data(&input_pool); | |
989 | init_std_data(&blocking_pool); | |
990 | init_std_data(&nonblocking_pool); | |
991 | return 0; | |
992 | } | |
993 | module_init(rand_initialize); | |
994 | ||
995 | void rand_initialize_irq(int irq) | |
996 | { | |
997 | struct timer_rand_state *state; | |
998 | ||
3060d6fe YL |
999 | state = get_timer_rand_state(irq); |
1000 | ||
1001 | if (state) | |
1da177e4 LT |
1002 | return; |
1003 | ||
1004 | /* | |
f8595815 | 1005 | * If kzalloc returns null, we just won't use that entropy |
1da177e4 LT |
1006 | * source. |
1007 | */ | |
f8595815 ED |
1008 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
1009 | if (state) | |
3060d6fe | 1010 | set_timer_rand_state(irq, state); |
1da177e4 LT |
1011 | } |
1012 | ||
9361401e | 1013 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1014 | void rand_initialize_disk(struct gendisk *disk) |
1015 | { | |
1016 | struct timer_rand_state *state; | |
1017 | ||
1018 | /* | |
f8595815 | 1019 | * If kzalloc returns null, we just won't use that entropy |
1da177e4 LT |
1020 | * source. |
1021 | */ | |
f8595815 ED |
1022 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
1023 | if (state) | |
1da177e4 | 1024 | disk->random = state; |
1da177e4 | 1025 | } |
9361401e | 1026 | #endif |
1da177e4 LT |
1027 | |
1028 | static ssize_t | |
90b75ee5 | 1029 | random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
1da177e4 LT |
1030 | { |
1031 | ssize_t n, retval = 0, count = 0; | |
1032 | ||
1033 | if (nbytes == 0) | |
1034 | return 0; | |
1035 | ||
1036 | while (nbytes > 0) { | |
1037 | n = nbytes; | |
1038 | if (n > SEC_XFER_SIZE) | |
1039 | n = SEC_XFER_SIZE; | |
1040 | ||
1041 | DEBUG_ENT("reading %d bits\n", n*8); | |
1042 | ||
1043 | n = extract_entropy_user(&blocking_pool, buf, n); | |
1044 | ||
1045 | DEBUG_ENT("read got %d bits (%d still needed)\n", | |
1046 | n*8, (nbytes-n)*8); | |
1047 | ||
1048 | if (n == 0) { | |
1049 | if (file->f_flags & O_NONBLOCK) { | |
1050 | retval = -EAGAIN; | |
1051 | break; | |
1052 | } | |
1053 | ||
1054 | DEBUG_ENT("sleeping?\n"); | |
1055 | ||
1056 | wait_event_interruptible(random_read_wait, | |
1057 | input_pool.entropy_count >= | |
1058 | random_read_wakeup_thresh); | |
1059 | ||
1060 | DEBUG_ENT("awake\n"); | |
1061 | ||
1062 | if (signal_pending(current)) { | |
1063 | retval = -ERESTARTSYS; | |
1064 | break; | |
1065 | } | |
1066 | ||
1067 | continue; | |
1068 | } | |
1069 | ||
1070 | if (n < 0) { | |
1071 | retval = n; | |
1072 | break; | |
1073 | } | |
1074 | count += n; | |
1075 | buf += n; | |
1076 | nbytes -= n; | |
1077 | break; /* This break makes the device work */ | |
1078 | /* like a named pipe */ | |
1079 | } | |
1080 | ||
1da177e4 LT |
1081 | return (count ? count : retval); |
1082 | } | |
1083 | ||
1084 | static ssize_t | |
90b75ee5 | 1085 | urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
1da177e4 LT |
1086 | { |
1087 | return extract_entropy_user(&nonblocking_pool, buf, nbytes); | |
1088 | } | |
1089 | ||
1090 | static unsigned int | |
1091 | random_poll(struct file *file, poll_table * wait) | |
1092 | { | |
1093 | unsigned int mask; | |
1094 | ||
1095 | poll_wait(file, &random_read_wait, wait); | |
1096 | poll_wait(file, &random_write_wait, wait); | |
1097 | mask = 0; | |
1098 | if (input_pool.entropy_count >= random_read_wakeup_thresh) | |
1099 | mask |= POLLIN | POLLRDNORM; | |
1100 | if (input_pool.entropy_count < random_write_wakeup_thresh) | |
1101 | mask |= POLLOUT | POLLWRNORM; | |
1102 | return mask; | |
1103 | } | |
1104 | ||
7f397dcd MM |
1105 | static int |
1106 | write_pool(struct entropy_store *r, const char __user *buffer, size_t count) | |
1da177e4 | 1107 | { |
1da177e4 LT |
1108 | size_t bytes; |
1109 | __u32 buf[16]; | |
1110 | const char __user *p = buffer; | |
1da177e4 | 1111 | |
7f397dcd MM |
1112 | while (count > 0) { |
1113 | bytes = min(count, sizeof(buf)); | |
1114 | if (copy_from_user(&buf, p, bytes)) | |
1115 | return -EFAULT; | |
1da177e4 | 1116 | |
7f397dcd | 1117 | count -= bytes; |
1da177e4 LT |
1118 | p += bytes; |
1119 | ||
e68e5b66 | 1120 | mix_pool_bytes(r, buf, bytes); |
91f3f1e3 | 1121 | cond_resched(); |
1da177e4 | 1122 | } |
7f397dcd MM |
1123 | |
1124 | return 0; | |
1125 | } | |
1126 | ||
90b75ee5 MM |
1127 | static ssize_t random_write(struct file *file, const char __user *buffer, |
1128 | size_t count, loff_t *ppos) | |
7f397dcd MM |
1129 | { |
1130 | size_t ret; | |
7f397dcd MM |
1131 | |
1132 | ret = write_pool(&blocking_pool, buffer, count); | |
1133 | if (ret) | |
1134 | return ret; | |
1135 | ret = write_pool(&nonblocking_pool, buffer, count); | |
1136 | if (ret) | |
1137 | return ret; | |
1138 | ||
7f397dcd | 1139 | return (ssize_t)count; |
1da177e4 LT |
1140 | } |
1141 | ||
43ae4860 | 1142 | static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) |
1da177e4 LT |
1143 | { |
1144 | int size, ent_count; | |
1145 | int __user *p = (int __user *)arg; | |
1146 | int retval; | |
1147 | ||
1148 | switch (cmd) { | |
1149 | case RNDGETENTCNT: | |
43ae4860 MM |
1150 | /* inherently racy, no point locking */ |
1151 | if (put_user(input_pool.entropy_count, p)) | |
1da177e4 LT |
1152 | return -EFAULT; |
1153 | return 0; | |
1154 | case RNDADDTOENTCNT: | |
1155 | if (!capable(CAP_SYS_ADMIN)) | |
1156 | return -EPERM; | |
1157 | if (get_user(ent_count, p)) | |
1158 | return -EFAULT; | |
adc782da | 1159 | credit_entropy_bits(&input_pool, ent_count); |
1da177e4 LT |
1160 | return 0; |
1161 | case RNDADDENTROPY: | |
1162 | if (!capable(CAP_SYS_ADMIN)) | |
1163 | return -EPERM; | |
1164 | if (get_user(ent_count, p++)) | |
1165 | return -EFAULT; | |
1166 | if (ent_count < 0) | |
1167 | return -EINVAL; | |
1168 | if (get_user(size, p++)) | |
1169 | return -EFAULT; | |
7f397dcd MM |
1170 | retval = write_pool(&input_pool, (const char __user *)p, |
1171 | size); | |
1da177e4 LT |
1172 | if (retval < 0) |
1173 | return retval; | |
adc782da | 1174 | credit_entropy_bits(&input_pool, ent_count); |
1da177e4 LT |
1175 | return 0; |
1176 | case RNDZAPENTCNT: | |
1177 | case RNDCLEARPOOL: | |
1178 | /* Clear the entropy pool counters. */ | |
1179 | if (!capable(CAP_SYS_ADMIN)) | |
1180 | return -EPERM; | |
53c3f63e | 1181 | rand_initialize(); |
1da177e4 LT |
1182 | return 0; |
1183 | default: | |
1184 | return -EINVAL; | |
1185 | } | |
1186 | } | |
1187 | ||
9a6f70bb JD |
1188 | static int random_fasync(int fd, struct file *filp, int on) |
1189 | { | |
1190 | return fasync_helper(fd, filp, on, &fasync); | |
1191 | } | |
1192 | ||
2b8693c0 | 1193 | const struct file_operations random_fops = { |
1da177e4 LT |
1194 | .read = random_read, |
1195 | .write = random_write, | |
1196 | .poll = random_poll, | |
43ae4860 | 1197 | .unlocked_ioctl = random_ioctl, |
9a6f70bb | 1198 | .fasync = random_fasync, |
6038f373 | 1199 | .llseek = noop_llseek, |
1da177e4 LT |
1200 | }; |
1201 | ||
2b8693c0 | 1202 | const struct file_operations urandom_fops = { |
1da177e4 LT |
1203 | .read = urandom_read, |
1204 | .write = random_write, | |
43ae4860 | 1205 | .unlocked_ioctl = random_ioctl, |
9a6f70bb | 1206 | .fasync = random_fasync, |
6038f373 | 1207 | .llseek = noop_llseek, |
1da177e4 LT |
1208 | }; |
1209 | ||
1210 | /*************************************************************** | |
1211 | * Random UUID interface | |
1212 | * | |
1213 | * Used here for a Boot ID, but can be useful for other kernel | |
1214 | * drivers. | |
1215 | ***************************************************************/ | |
1216 | ||
1217 | /* | |
1218 | * Generate random UUID | |
1219 | */ | |
1220 | void generate_random_uuid(unsigned char uuid_out[16]) | |
1221 | { | |
1222 | get_random_bytes(uuid_out, 16); | |
c41b20e7 | 1223 | /* Set UUID version to 4 --- truly random generation */ |
1da177e4 LT |
1224 | uuid_out[6] = (uuid_out[6] & 0x0F) | 0x40; |
1225 | /* Set the UUID variant to DCE */ | |
1226 | uuid_out[8] = (uuid_out[8] & 0x3F) | 0x80; | |
1227 | } | |
1da177e4 LT |
1228 | EXPORT_SYMBOL(generate_random_uuid); |
1229 | ||
1230 | /******************************************************************** | |
1231 | * | |
1232 | * Sysctl interface | |
1233 | * | |
1234 | ********************************************************************/ | |
1235 | ||
1236 | #ifdef CONFIG_SYSCTL | |
1237 | ||
1238 | #include <linux/sysctl.h> | |
1239 | ||
1240 | static int min_read_thresh = 8, min_write_thresh; | |
1241 | static int max_read_thresh = INPUT_POOL_WORDS * 32; | |
1242 | static int max_write_thresh = INPUT_POOL_WORDS * 32; | |
1243 | static char sysctl_bootid[16]; | |
1244 | ||
1245 | /* | |
1246 | * These functions is used to return both the bootid UUID, and random | |
1247 | * UUID. The difference is in whether table->data is NULL; if it is, | |
1248 | * then a new UUID is generated and returned to the user. | |
1249 | * | |
1250 | * If the user accesses this via the proc interface, it will be returned | |
1251 | * as an ASCII string in the standard UUID format. If accesses via the | |
1252 | * sysctl system call, it is returned as 16 bytes of binary data. | |
1253 | */ | |
8d65af78 | 1254 | static int proc_do_uuid(ctl_table *table, int write, |
1da177e4 LT |
1255 | void __user *buffer, size_t *lenp, loff_t *ppos) |
1256 | { | |
1257 | ctl_table fake_table; | |
1258 | unsigned char buf[64], tmp_uuid[16], *uuid; | |
1259 | ||
1260 | uuid = table->data; | |
1261 | if (!uuid) { | |
1262 | uuid = tmp_uuid; | |
1da177e4 | 1263 | generate_random_uuid(uuid); |
44e4360f MD |
1264 | } else { |
1265 | static DEFINE_SPINLOCK(bootid_spinlock); | |
1266 | ||
1267 | spin_lock(&bootid_spinlock); | |
1268 | if (!uuid[8]) | |
1269 | generate_random_uuid(uuid); | |
1270 | spin_unlock(&bootid_spinlock); | |
1271 | } | |
1da177e4 | 1272 | |
35900771 JP |
1273 | sprintf(buf, "%pU", uuid); |
1274 | ||
1da177e4 LT |
1275 | fake_table.data = buf; |
1276 | fake_table.maxlen = sizeof(buf); | |
1277 | ||
8d65af78 | 1278 | return proc_dostring(&fake_table, write, buffer, lenp, ppos); |
1da177e4 LT |
1279 | } |
1280 | ||
1da177e4 LT |
1281 | static int sysctl_poolsize = INPUT_POOL_WORDS * 32; |
1282 | ctl_table random_table[] = { | |
1283 | { | |
1da177e4 LT |
1284 | .procname = "poolsize", |
1285 | .data = &sysctl_poolsize, | |
1286 | .maxlen = sizeof(int), | |
1287 | .mode = 0444, | |
6d456111 | 1288 | .proc_handler = proc_dointvec, |
1da177e4 LT |
1289 | }, |
1290 | { | |
1da177e4 LT |
1291 | .procname = "entropy_avail", |
1292 | .maxlen = sizeof(int), | |
1293 | .mode = 0444, | |
6d456111 | 1294 | .proc_handler = proc_dointvec, |
1da177e4 LT |
1295 | .data = &input_pool.entropy_count, |
1296 | }, | |
1297 | { | |
1da177e4 LT |
1298 | .procname = "read_wakeup_threshold", |
1299 | .data = &random_read_wakeup_thresh, | |
1300 | .maxlen = sizeof(int), | |
1301 | .mode = 0644, | |
6d456111 | 1302 | .proc_handler = proc_dointvec_minmax, |
1da177e4 LT |
1303 | .extra1 = &min_read_thresh, |
1304 | .extra2 = &max_read_thresh, | |
1305 | }, | |
1306 | { | |
1da177e4 LT |
1307 | .procname = "write_wakeup_threshold", |
1308 | .data = &random_write_wakeup_thresh, | |
1309 | .maxlen = sizeof(int), | |
1310 | .mode = 0644, | |
6d456111 | 1311 | .proc_handler = proc_dointvec_minmax, |
1da177e4 LT |
1312 | .extra1 = &min_write_thresh, |
1313 | .extra2 = &max_write_thresh, | |
1314 | }, | |
1315 | { | |
1da177e4 LT |
1316 | .procname = "boot_id", |
1317 | .data = &sysctl_bootid, | |
1318 | .maxlen = 16, | |
1319 | .mode = 0444, | |
6d456111 | 1320 | .proc_handler = proc_do_uuid, |
1da177e4 LT |
1321 | }, |
1322 | { | |
1da177e4 LT |
1323 | .procname = "uuid", |
1324 | .maxlen = 16, | |
1325 | .mode = 0444, | |
6d456111 | 1326 | .proc_handler = proc_do_uuid, |
1da177e4 | 1327 | }, |
894d2491 | 1328 | { } |
1da177e4 LT |
1329 | }; |
1330 | #endif /* CONFIG_SYSCTL */ | |
1331 | ||
6e5714ea | 1332 | static u32 random_int_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned; |
1da177e4 | 1333 | |
6e5714ea | 1334 | static int __init random_int_secret_init(void) |
1da177e4 | 1335 | { |
6e5714ea | 1336 | get_random_bytes(random_int_secret, sizeof(random_int_secret)); |
1da177e4 LT |
1337 | return 0; |
1338 | } | |
6e5714ea | 1339 | late_initcall(random_int_secret_init); |
1da177e4 LT |
1340 | |
1341 | /* | |
1342 | * Get a random word for internal kernel use only. Similar to urandom but | |
1343 | * with the goal of minimal entropy pool depletion. As a result, the random | |
1344 | * value is not cryptographically secure but for several uses the cost of | |
1345 | * depleting entropy is too high | |
1346 | */ | |
6e5714ea | 1347 | DEFINE_PER_CPU(__u32 [MD5_DIGEST_WORDS], get_random_int_hash); |
1da177e4 LT |
1348 | unsigned int get_random_int(void) |
1349 | { | |
63d77173 | 1350 | __u32 *hash; |
6e5714ea | 1351 | unsigned int ret; |
8a0a9bd4 | 1352 | |
63d77173 PA |
1353 | if (arch_get_random_int(&ret)) |
1354 | return ret; | |
1355 | ||
1356 | hash = get_cpu_var(get_random_int_hash); | |
8a0a9bd4 | 1357 | |
26a9a418 | 1358 | hash[0] += current->pid + jiffies + get_cycles(); |
6e5714ea DM |
1359 | md5_transform(hash, random_int_secret); |
1360 | ret = hash[0]; | |
8a0a9bd4 LT |
1361 | put_cpu_var(get_random_int_hash); |
1362 | ||
1363 | return ret; | |
1da177e4 LT |
1364 | } |
1365 | ||
1366 | /* | |
1367 | * randomize_range() returns a start address such that | |
1368 | * | |
1369 | * [...... <range> .....] | |
1370 | * start end | |
1371 | * | |
1372 | * a <range> with size "len" starting at the return value is inside in the | |
1373 | * area defined by [start, end], but is otherwise randomized. | |
1374 | */ | |
1375 | unsigned long | |
1376 | randomize_range(unsigned long start, unsigned long end, unsigned long len) | |
1377 | { | |
1378 | unsigned long range = end - len - start; | |
1379 | ||
1380 | if (end <= start + len) | |
1381 | return 0; | |
1382 | return PAGE_ALIGN(get_random_int() % range + start); | |
1383 | } |