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1 | /* | |
2 | * random.c -- A strong random number generator | |
3 | * | |
4 | * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005 | |
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_device_randomness(const void *buf, unsigned int size); | |
129 | * void add_input_randomness(unsigned int type, unsigned int code, | |
130 | * unsigned int value); | |
131 | * void add_interrupt_randomness(int irq, int irq_flags); | |
132 | * void add_disk_randomness(struct gendisk *disk); | |
133 | * | |
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 | * | |
142 | * add_input_randomness() uses the input layer interrupt timing, as well as | |
143 | * the event type information from the hardware. | |
144 | * | |
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. | |
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. | |
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> | |
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> | |
251 | #include <linux/mm.h> | |
252 | #include <linux/nodemask.h> | |
253 | #include <linux/spinlock.h> | |
254 | #include <linux/kthread.h> | |
255 | #include <linux/percpu.h> | |
256 | #include <linux/cryptohash.h> | |
257 | #include <linux/fips.h> | |
258 | #include <linux/ptrace.h> | |
259 | #include <linux/kmemcheck.h> | |
260 | #include <linux/workqueue.h> | |
261 | #include <linux/irq.h> | |
262 | #include <linux/syscalls.h> | |
263 | #include <linux/completion.h> | |
264 | #include <linux/uuid.h> | |
265 | #include <crypto/chacha20.h> | |
266 | ||
267 | #include <asm/processor.h> | |
268 | #include <linux/uaccess.h> | |
269 | #include <asm/irq.h> | |
270 | #include <asm/irq_regs.h> | |
271 | #include <asm/io.h> | |
272 | ||
273 | #define CREATE_TRACE_POINTS | |
274 | #include <trace/events/random.h> | |
275 | ||
276 | /* #define ADD_INTERRUPT_BENCH */ | |
277 | ||
278 | /* | |
279 | * Configuration information | |
280 | */ | |
281 | #define INPUT_POOL_SHIFT 12 | |
282 | #define INPUT_POOL_WORDS (1 << (INPUT_POOL_SHIFT-5)) | |
283 | #define OUTPUT_POOL_SHIFT 10 | |
284 | #define OUTPUT_POOL_WORDS (1 << (OUTPUT_POOL_SHIFT-5)) | |
285 | #define SEC_XFER_SIZE 512 | |
286 | #define EXTRACT_SIZE 10 | |
287 | ||
288 | #define DEBUG_RANDOM_BOOT 0 | |
289 | ||
290 | #define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long)) | |
291 | ||
292 | /* | |
293 | * To allow fractional bits to be tracked, the entropy_count field is | |
294 | * denominated in units of 1/8th bits. | |
295 | * | |
296 | * 2*(ENTROPY_SHIFT + log2(poolbits)) must <= 31, or the multiply in | |
297 | * credit_entropy_bits() needs to be 64 bits wide. | |
298 | */ | |
299 | #define ENTROPY_SHIFT 3 | |
300 | #define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT) | |
301 | ||
302 | /* | |
303 | * The minimum number of bits of entropy before we wake up a read on | |
304 | * /dev/random. Should be enough to do a significant reseed. | |
305 | */ | |
306 | static int random_read_wakeup_bits = 64; | |
307 | ||
308 | /* | |
309 | * If the entropy count falls under this number of bits, then we | |
310 | * should wake up processes which are selecting or polling on write | |
311 | * access to /dev/random. | |
312 | */ | |
313 | static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS; | |
314 | ||
315 | /* | |
316 | * Variable is currently unused by left for user space compatibility. | |
317 | */ | |
318 | static int random_min_urandom_seed = 60; | |
319 | ||
320 | /* | |
321 | * Originally, we used a primitive polynomial of degree .poolwords | |
322 | * over GF(2). The taps for various sizes are defined below. They | |
323 | * were chosen to be evenly spaced except for the last tap, which is 1 | |
324 | * to get the twisting happening as fast as possible. | |
325 | * | |
326 | * For the purposes of better mixing, we use the CRC-32 polynomial as | |
327 | * well to make a (modified) twisted Generalized Feedback Shift | |
328 | * Register. (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR | |
329 | * generators. ACM Transactions on Modeling and Computer Simulation | |
330 | * 2(3):179-194. Also see M. Matsumoto & Y. Kurita, 1994. Twisted | |
331 | * GFSR generators II. ACM Transactions on Modeling and Computer | |
332 | * Simulation 4:254-266) | |
333 | * | |
334 | * Thanks to Colin Plumb for suggesting this. | |
335 | * | |
336 | * The mixing operation is much less sensitive than the output hash, | |
337 | * where we use SHA-1. All that we want of mixing operation is that | |
338 | * it be a good non-cryptographic hash; i.e. it not produce collisions | |
339 | * when fed "random" data of the sort we expect to see. As long as | |
340 | * the pool state differs for different inputs, we have preserved the | |
341 | * input entropy and done a good job. The fact that an intelligent | |
342 | * attacker can construct inputs that will produce controlled | |
343 | * alterations to the pool's state is not important because we don't | |
344 | * consider such inputs to contribute any randomness. The only | |
345 | * property we need with respect to them is that the attacker can't | |
346 | * increase his/her knowledge of the pool's state. Since all | |
347 | * additions are reversible (knowing the final state and the input, | |
348 | * you can reconstruct the initial state), if an attacker has any | |
349 | * uncertainty about the initial state, he/she can only shuffle that | |
350 | * uncertainty about, but never cause any collisions (which would | |
351 | * decrease the uncertainty). | |
352 | * | |
353 | * Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and | |
354 | * Videau in their paper, "The Linux Pseudorandom Number Generator | |
355 | * Revisited" (see: http://eprint.iacr.org/2012/251.pdf). In their | |
356 | * paper, they point out that we are not using a true Twisted GFSR, | |
357 | * since Matsumoto & Kurita used a trinomial feedback polynomial (that | |
358 | * is, with only three taps, instead of the six that we are using). | |
359 | * As a result, the resulting polynomial is neither primitive nor | |
360 | * irreducible, and hence does not have a maximal period over | |
361 | * GF(2**32). They suggest a slight change to the generator | |
362 | * polynomial which improves the resulting TGFSR polynomial to be | |
363 | * irreducible, which we have made here. | |
364 | */ | |
365 | static struct poolinfo { | |
366 | int poolbitshift, poolwords, poolbytes, poolbits, poolfracbits; | |
367 | #define S(x) ilog2(x)+5, (x), (x)*4, (x)*32, (x) << (ENTROPY_SHIFT+5) | |
368 | int tap1, tap2, tap3, tap4, tap5; | |
369 | } poolinfo_table[] = { | |
370 | /* was: x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 */ | |
371 | /* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */ | |
372 | { S(128), 104, 76, 51, 25, 1 }, | |
373 | /* was: x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 */ | |
374 | /* x^32 + x^26 + x^19 + x^14 + x^7 + x + 1 */ | |
375 | { S(32), 26, 19, 14, 7, 1 }, | |
376 | #if 0 | |
377 | /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */ | |
378 | { S(2048), 1638, 1231, 819, 411, 1 }, | |
379 | ||
380 | /* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */ | |
381 | { S(1024), 817, 615, 412, 204, 1 }, | |
382 | ||
383 | /* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */ | |
384 | { S(1024), 819, 616, 410, 207, 2 }, | |
385 | ||
386 | /* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */ | |
387 | { S(512), 411, 308, 208, 104, 1 }, | |
388 | ||
389 | /* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */ | |
390 | { S(512), 409, 307, 206, 102, 2 }, | |
391 | /* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */ | |
392 | { S(512), 409, 309, 205, 103, 2 }, | |
393 | ||
394 | /* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */ | |
395 | { S(256), 205, 155, 101, 52, 1 }, | |
396 | ||
397 | /* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */ | |
398 | { S(128), 103, 78, 51, 27, 2 }, | |
399 | ||
400 | /* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */ | |
401 | { S(64), 52, 39, 26, 14, 1 }, | |
402 | #endif | |
403 | }; | |
404 | ||
405 | /* | |
406 | * Static global variables | |
407 | */ | |
408 | static DECLARE_WAIT_QUEUE_HEAD(random_read_wait); | |
409 | static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); | |
410 | static struct fasync_struct *fasync; | |
411 | ||
412 | static DEFINE_SPINLOCK(random_ready_list_lock); | |
413 | static LIST_HEAD(random_ready_list); | |
414 | ||
415 | struct crng_state { | |
416 | __u32 state[16]; | |
417 | unsigned long init_time; | |
418 | spinlock_t lock; | |
419 | }; | |
420 | ||
421 | struct crng_state primary_crng = { | |
422 | .lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock), | |
423 | }; | |
424 | ||
425 | /* | |
426 | * crng_init = 0 --> Uninitialized | |
427 | * 1 --> Initialized | |
428 | * 2 --> Initialized from input_pool | |
429 | * | |
430 | * crng_init is protected by primary_crng->lock, and only increases | |
431 | * its value (from 0->1->2). | |
432 | */ | |
433 | static int crng_init = 0; | |
434 | #define crng_ready() (likely(crng_init > 0)) | |
435 | static int crng_init_cnt = 0; | |
436 | #define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE) | |
437 | static void _extract_crng(struct crng_state *crng, | |
438 | __u8 out[CHACHA20_BLOCK_SIZE]); | |
439 | static void _crng_backtrack_protect(struct crng_state *crng, | |
440 | __u8 tmp[CHACHA20_BLOCK_SIZE], int used); | |
441 | static void process_random_ready_list(void); | |
442 | ||
443 | /********************************************************************** | |
444 | * | |
445 | * OS independent entropy store. Here are the functions which handle | |
446 | * storing entropy in an entropy pool. | |
447 | * | |
448 | **********************************************************************/ | |
449 | ||
450 | struct entropy_store; | |
451 | struct entropy_store { | |
452 | /* read-only data: */ | |
453 | const struct poolinfo *poolinfo; | |
454 | __u32 *pool; | |
455 | const char *name; | |
456 | struct entropy_store *pull; | |
457 | struct work_struct push_work; | |
458 | ||
459 | /* read-write data: */ | |
460 | unsigned long last_pulled; | |
461 | spinlock_t lock; | |
462 | unsigned short add_ptr; | |
463 | unsigned short input_rotate; | |
464 | int entropy_count; | |
465 | int entropy_total; | |
466 | unsigned int initialized:1; | |
467 | unsigned int last_data_init:1; | |
468 | __u8 last_data[EXTRACT_SIZE]; | |
469 | }; | |
470 | ||
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); | |
477 | static void push_to_pool(struct work_struct *work); | |
478 | static __u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy; | |
479 | static __u32 blocking_pool_data[OUTPUT_POOL_WORDS] __latent_entropy; | |
480 | ||
481 | static struct entropy_store input_pool = { | |
482 | .poolinfo = &poolinfo_table[0], | |
483 | .name = "input", | |
484 | .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock), | |
485 | .pool = input_pool_data | |
486 | }; | |
487 | ||
488 | static struct entropy_store blocking_pool = { | |
489 | .poolinfo = &poolinfo_table[1], | |
490 | .name = "blocking", | |
491 | .pull = &input_pool, | |
492 | .lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock), | |
493 | .pool = blocking_pool_data, | |
494 | .push_work = __WORK_INITIALIZER(blocking_pool.push_work, | |
495 | push_to_pool), | |
496 | }; | |
497 | ||
498 | static __u32 const twist_table[8] = { | |
499 | 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158, | |
500 | 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 }; | |
501 | ||
502 | /* | |
503 | * This function adds bytes into the entropy "pool". It does not | |
504 | * update the entropy estimate. The caller should call | |
505 | * credit_entropy_bits if this is appropriate. | |
506 | * | |
507 | * The pool is stirred with a primitive polynomial of the appropriate | |
508 | * degree, and then twisted. We twist by three bits at a time because | |
509 | * it's cheap to do so and helps slightly in the expected case where | |
510 | * the entropy is concentrated in the low-order bits. | |
511 | */ | |
512 | static void _mix_pool_bytes(struct entropy_store *r, const void *in, | |
513 | int nbytes) | |
514 | { | |
515 | unsigned long i, tap1, tap2, tap3, tap4, tap5; | |
516 | int input_rotate; | |
517 | int wordmask = r->poolinfo->poolwords - 1; | |
518 | const char *bytes = in; | |
519 | __u32 w; | |
520 | ||
521 | tap1 = r->poolinfo->tap1; | |
522 | tap2 = r->poolinfo->tap2; | |
523 | tap3 = r->poolinfo->tap3; | |
524 | tap4 = r->poolinfo->tap4; | |
525 | tap5 = r->poolinfo->tap5; | |
526 | ||
527 | input_rotate = r->input_rotate; | |
528 | i = r->add_ptr; | |
529 | ||
530 | /* mix one byte at a time to simplify size handling and churn faster */ | |
531 | while (nbytes--) { | |
532 | w = rol32(*bytes++, input_rotate); | |
533 | i = (i - 1) & wordmask; | |
534 | ||
535 | /* XOR in the various taps */ | |
536 | w ^= r->pool[i]; | |
537 | w ^= r->pool[(i + tap1) & wordmask]; | |
538 | w ^= r->pool[(i + tap2) & wordmask]; | |
539 | w ^= r->pool[(i + tap3) & wordmask]; | |
540 | w ^= r->pool[(i + tap4) & wordmask]; | |
541 | w ^= r->pool[(i + tap5) & wordmask]; | |
542 | ||
543 | /* Mix the result back in with a twist */ | |
544 | r->pool[i] = (w >> 3) ^ twist_table[w & 7]; | |
545 | ||
546 | /* | |
547 | * Normally, we add 7 bits of rotation to the pool. | |
548 | * At the beginning of the pool, add an extra 7 bits | |
549 | * rotation, so that successive passes spread the | |
550 | * input bits across the pool evenly. | |
551 | */ | |
552 | input_rotate = (input_rotate + (i ? 7 : 14)) & 31; | |
553 | } | |
554 | ||
555 | r->input_rotate = input_rotate; | |
556 | r->add_ptr = i; | |
557 | } | |
558 | ||
559 | static void __mix_pool_bytes(struct entropy_store *r, const void *in, | |
560 | int nbytes) | |
561 | { | |
562 | trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_); | |
563 | _mix_pool_bytes(r, in, nbytes); | |
564 | } | |
565 | ||
566 | static void mix_pool_bytes(struct entropy_store *r, const void *in, | |
567 | int nbytes) | |
568 | { | |
569 | unsigned long flags; | |
570 | ||
571 | trace_mix_pool_bytes(r->name, nbytes, _RET_IP_); | |
572 | spin_lock_irqsave(&r->lock, flags); | |
573 | _mix_pool_bytes(r, in, nbytes); | |
574 | spin_unlock_irqrestore(&r->lock, flags); | |
575 | } | |
576 | ||
577 | struct fast_pool { | |
578 | __u32 pool[4]; | |
579 | unsigned long last; | |
580 | unsigned short reg_idx; | |
581 | unsigned char count; | |
582 | }; | |
583 | ||
584 | /* | |
585 | * This is a fast mixing routine used by the interrupt randomness | |
586 | * collector. It's hardcoded for an 128 bit pool and assumes that any | |
587 | * locks that might be needed are taken by the caller. | |
588 | */ | |
589 | static void fast_mix(struct fast_pool *f) | |
590 | { | |
591 | __u32 a = f->pool[0], b = f->pool[1]; | |
592 | __u32 c = f->pool[2], d = f->pool[3]; | |
593 | ||
594 | a += b; c += d; | |
595 | b = rol32(b, 6); d = rol32(d, 27); | |
596 | d ^= a; b ^= c; | |
597 | ||
598 | a += b; c += d; | |
599 | b = rol32(b, 16); d = rol32(d, 14); | |
600 | d ^= a; b ^= c; | |
601 | ||
602 | a += b; c += d; | |
603 | b = rol32(b, 6); d = rol32(d, 27); | |
604 | d ^= a; b ^= c; | |
605 | ||
606 | a += b; c += d; | |
607 | b = rol32(b, 16); d = rol32(d, 14); | |
608 | d ^= a; b ^= c; | |
609 | ||
610 | f->pool[0] = a; f->pool[1] = b; | |
611 | f->pool[2] = c; f->pool[3] = d; | |
612 | f->count++; | |
613 | } | |
614 | ||
615 | static void process_random_ready_list(void) | |
616 | { | |
617 | unsigned long flags; | |
618 | struct random_ready_callback *rdy, *tmp; | |
619 | ||
620 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
621 | list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) { | |
622 | struct module *owner = rdy->owner; | |
623 | ||
624 | list_del_init(&rdy->list); | |
625 | rdy->func(rdy); | |
626 | module_put(owner); | |
627 | } | |
628 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
629 | } | |
630 | ||
631 | /* | |
632 | * Credit (or debit) the entropy store with n bits of entropy. | |
633 | * Use credit_entropy_bits_safe() if the value comes from userspace | |
634 | * or otherwise should be checked for extreme values. | |
635 | */ | |
636 | static void credit_entropy_bits(struct entropy_store *r, int nbits) | |
637 | { | |
638 | int entropy_count, orig; | |
639 | const int pool_size = r->poolinfo->poolfracbits; | |
640 | int nfrac = nbits << ENTROPY_SHIFT; | |
641 | ||
642 | if (!nbits) | |
643 | return; | |
644 | ||
645 | retry: | |
646 | entropy_count = orig = ACCESS_ONCE(r->entropy_count); | |
647 | if (nfrac < 0) { | |
648 | /* Debit */ | |
649 | entropy_count += nfrac; | |
650 | } else { | |
651 | /* | |
652 | * Credit: we have to account for the possibility of | |
653 | * overwriting already present entropy. Even in the | |
654 | * ideal case of pure Shannon entropy, new contributions | |
655 | * approach the full value asymptotically: | |
656 | * | |
657 | * entropy <- entropy + (pool_size - entropy) * | |
658 | * (1 - exp(-add_entropy/pool_size)) | |
659 | * | |
660 | * For add_entropy <= pool_size/2 then | |
661 | * (1 - exp(-add_entropy/pool_size)) >= | |
662 | * (add_entropy/pool_size)*0.7869... | |
663 | * so we can approximate the exponential with | |
664 | * 3/4*add_entropy/pool_size and still be on the | |
665 | * safe side by adding at most pool_size/2 at a time. | |
666 | * | |
667 | * The use of pool_size-2 in the while statement is to | |
668 | * prevent rounding artifacts from making the loop | |
669 | * arbitrarily long; this limits the loop to log2(pool_size)*2 | |
670 | * turns no matter how large nbits is. | |
671 | */ | |
672 | int pnfrac = nfrac; | |
673 | const int s = r->poolinfo->poolbitshift + ENTROPY_SHIFT + 2; | |
674 | /* The +2 corresponds to the /4 in the denominator */ | |
675 | ||
676 | do { | |
677 | unsigned int anfrac = min(pnfrac, pool_size/2); | |
678 | unsigned int add = | |
679 | ((pool_size - entropy_count)*anfrac*3) >> s; | |
680 | ||
681 | entropy_count += add; | |
682 | pnfrac -= anfrac; | |
683 | } while (unlikely(entropy_count < pool_size-2 && pnfrac)); | |
684 | } | |
685 | ||
686 | if (unlikely(entropy_count < 0)) { | |
687 | pr_warn("random: negative entropy/overflow: pool %s count %d\n", | |
688 | r->name, entropy_count); | |
689 | WARN_ON(1); | |
690 | entropy_count = 0; | |
691 | } else if (entropy_count > pool_size) | |
692 | entropy_count = pool_size; | |
693 | if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) | |
694 | goto retry; | |
695 | ||
696 | r->entropy_total += nbits; | |
697 | if (!r->initialized && r->entropy_total > 128) { | |
698 | r->initialized = 1; | |
699 | r->entropy_total = 0; | |
700 | } | |
701 | ||
702 | trace_credit_entropy_bits(r->name, nbits, | |
703 | entropy_count >> ENTROPY_SHIFT, | |
704 | r->entropy_total, _RET_IP_); | |
705 | ||
706 | if (r == &input_pool) { | |
707 | int entropy_bits = entropy_count >> ENTROPY_SHIFT; | |
708 | ||
709 | if (crng_init < 2 && entropy_bits >= 128) { | |
710 | crng_reseed(&primary_crng, r); | |
711 | entropy_bits = r->entropy_count >> ENTROPY_SHIFT; | |
712 | } | |
713 | ||
714 | /* should we wake readers? */ | |
715 | if (entropy_bits >= random_read_wakeup_bits) { | |
716 | wake_up_interruptible(&random_read_wait); | |
717 | kill_fasync(&fasync, SIGIO, POLL_IN); | |
718 | } | |
719 | /* If the input pool is getting full, send some | |
720 | * entropy to the blocking pool until it is 75% full. | |
721 | */ | |
722 | if (entropy_bits > random_write_wakeup_bits && | |
723 | r->initialized && | |
724 | r->entropy_total >= 2*random_read_wakeup_bits) { | |
725 | struct entropy_store *other = &blocking_pool; | |
726 | ||
727 | if (other->entropy_count <= | |
728 | 3 * other->poolinfo->poolfracbits / 4) { | |
729 | schedule_work(&other->push_work); | |
730 | r->entropy_total = 0; | |
731 | } | |
732 | } | |
733 | } | |
734 | } | |
735 | ||
736 | static int credit_entropy_bits_safe(struct entropy_store *r, int nbits) | |
737 | { | |
738 | const int nbits_max = (int)(~0U >> (ENTROPY_SHIFT + 1)); | |
739 | ||
740 | if (nbits < 0) | |
741 | return -EINVAL; | |
742 | ||
743 | /* Cap the value to avoid overflows */ | |
744 | nbits = min(nbits, nbits_max); | |
745 | ||
746 | credit_entropy_bits(r, nbits); | |
747 | return 0; | |
748 | } | |
749 | ||
750 | /********************************************************************* | |
751 | * | |
752 | * CRNG using CHACHA20 | |
753 | * | |
754 | *********************************************************************/ | |
755 | ||
756 | #define CRNG_RESEED_INTERVAL (300*HZ) | |
757 | ||
758 | static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); | |
759 | ||
760 | #ifdef CONFIG_NUMA | |
761 | /* | |
762 | * Hack to deal with crazy userspace progams when they are all trying | |
763 | * to access /dev/urandom in parallel. The programs are almost | |
764 | * certainly doing something terribly wrong, but we'll work around | |
765 | * their brain damage. | |
766 | */ | |
767 | static struct crng_state **crng_node_pool __read_mostly; | |
768 | #endif | |
769 | ||
770 | static void crng_initialize(struct crng_state *crng) | |
771 | { | |
772 | int i; | |
773 | unsigned long rv; | |
774 | ||
775 | memcpy(&crng->state[0], "expand 32-byte k", 16); | |
776 | if (crng == &primary_crng) | |
777 | _extract_entropy(&input_pool, &crng->state[4], | |
778 | sizeof(__u32) * 12, 0); | |
779 | else | |
780 | get_random_bytes(&crng->state[4], sizeof(__u32) * 12); | |
781 | for (i = 4; i < 16; i++) { | |
782 | if (!arch_get_random_seed_long(&rv) && | |
783 | !arch_get_random_long(&rv)) | |
784 | rv = random_get_entropy(); | |
785 | crng->state[i] ^= rv; | |
786 | } | |
787 | crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1; | |
788 | } | |
789 | ||
790 | static int crng_fast_load(const char *cp, size_t len) | |
791 | { | |
792 | unsigned long flags; | |
793 | char *p; | |
794 | ||
795 | if (!spin_trylock_irqsave(&primary_crng.lock, flags)) | |
796 | return 0; | |
797 | if (crng_ready()) { | |
798 | spin_unlock_irqrestore(&primary_crng.lock, flags); | |
799 | return 0; | |
800 | } | |
801 | p = (unsigned char *) &primary_crng.state[4]; | |
802 | while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) { | |
803 | p[crng_init_cnt % CHACHA20_KEY_SIZE] ^= *cp; | |
804 | cp++; crng_init_cnt++; len--; | |
805 | } | |
806 | if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) { | |
807 | crng_init = 1; | |
808 | wake_up_interruptible(&crng_init_wait); | |
809 | pr_notice("random: fast init done\n"); | |
810 | } | |
811 | spin_unlock_irqrestore(&primary_crng.lock, flags); | |
812 | return 1; | |
813 | } | |
814 | ||
815 | static void crng_reseed(struct crng_state *crng, struct entropy_store *r) | |
816 | { | |
817 | unsigned long flags; | |
818 | int i, num; | |
819 | union { | |
820 | __u8 block[CHACHA20_BLOCK_SIZE]; | |
821 | __u32 key[8]; | |
822 | } buf; | |
823 | ||
824 | if (r) { | |
825 | num = extract_entropy(r, &buf, 32, 16, 0); | |
826 | if (num == 0) | |
827 | return; | |
828 | } else { | |
829 | _extract_crng(&primary_crng, buf.block); | |
830 | _crng_backtrack_protect(&primary_crng, buf.block, | |
831 | CHACHA20_KEY_SIZE); | |
832 | } | |
833 | spin_lock_irqsave(&primary_crng.lock, flags); | |
834 | for (i = 0; i < 8; i++) { | |
835 | unsigned long rv; | |
836 | if (!arch_get_random_seed_long(&rv) && | |
837 | !arch_get_random_long(&rv)) | |
838 | rv = random_get_entropy(); | |
839 | crng->state[i+4] ^= buf.key[i] ^ rv; | |
840 | } | |
841 | memzero_explicit(&buf, sizeof(buf)); | |
842 | crng->init_time = jiffies; | |
843 | if (crng == &primary_crng && crng_init < 2) { | |
844 | crng_init = 2; | |
845 | process_random_ready_list(); | |
846 | wake_up_interruptible(&crng_init_wait); | |
847 | pr_notice("random: crng init done\n"); | |
848 | } | |
849 | spin_unlock_irqrestore(&primary_crng.lock, flags); | |
850 | } | |
851 | ||
852 | static inline void crng_wait_ready(void) | |
853 | { | |
854 | wait_event_interruptible(crng_init_wait, crng_ready()); | |
855 | } | |
856 | ||
857 | static void _extract_crng(struct crng_state *crng, | |
858 | __u8 out[CHACHA20_BLOCK_SIZE]) | |
859 | { | |
860 | unsigned long v, flags; | |
861 | ||
862 | if (crng_init > 1 && | |
863 | time_after(jiffies, crng->init_time + CRNG_RESEED_INTERVAL)) | |
864 | crng_reseed(crng, crng == &primary_crng ? &input_pool : NULL); | |
865 | spin_lock_irqsave(&crng->lock, flags); | |
866 | if (arch_get_random_long(&v)) | |
867 | crng->state[14] ^= v; | |
868 | chacha20_block(&crng->state[0], out); | |
869 | if (crng->state[12] == 0) | |
870 | crng->state[13]++; | |
871 | spin_unlock_irqrestore(&crng->lock, flags); | |
872 | } | |
873 | ||
874 | static void extract_crng(__u8 out[CHACHA20_BLOCK_SIZE]) | |
875 | { | |
876 | struct crng_state *crng = NULL; | |
877 | ||
878 | #ifdef CONFIG_NUMA | |
879 | if (crng_node_pool) | |
880 | crng = crng_node_pool[numa_node_id()]; | |
881 | if (crng == NULL) | |
882 | #endif | |
883 | crng = &primary_crng; | |
884 | _extract_crng(crng, out); | |
885 | } | |
886 | ||
887 | /* | |
888 | * Use the leftover bytes from the CRNG block output (if there is | |
889 | * enough) to mutate the CRNG key to provide backtracking protection. | |
890 | */ | |
891 | static void _crng_backtrack_protect(struct crng_state *crng, | |
892 | __u8 tmp[CHACHA20_BLOCK_SIZE], int used) | |
893 | { | |
894 | unsigned long flags; | |
895 | __u32 *s, *d; | |
896 | int i; | |
897 | ||
898 | used = round_up(used, sizeof(__u32)); | |
899 | if (used + CHACHA20_KEY_SIZE > CHACHA20_BLOCK_SIZE) { | |
900 | extract_crng(tmp); | |
901 | used = 0; | |
902 | } | |
903 | spin_lock_irqsave(&crng->lock, flags); | |
904 | s = (__u32 *) &tmp[used]; | |
905 | d = &crng->state[4]; | |
906 | for (i=0; i < 8; i++) | |
907 | *d++ ^= *s++; | |
908 | spin_unlock_irqrestore(&crng->lock, flags); | |
909 | } | |
910 | ||
911 | static void crng_backtrack_protect(__u8 tmp[CHACHA20_BLOCK_SIZE], int used) | |
912 | { | |
913 | struct crng_state *crng = NULL; | |
914 | ||
915 | #ifdef CONFIG_NUMA | |
916 | if (crng_node_pool) | |
917 | crng = crng_node_pool[numa_node_id()]; | |
918 | if (crng == NULL) | |
919 | #endif | |
920 | crng = &primary_crng; | |
921 | _crng_backtrack_protect(crng, tmp, used); | |
922 | } | |
923 | ||
924 | static ssize_t extract_crng_user(void __user *buf, size_t nbytes) | |
925 | { | |
926 | ssize_t ret = 0, i = CHACHA20_BLOCK_SIZE; | |
927 | __u8 tmp[CHACHA20_BLOCK_SIZE]; | |
928 | int large_request = (nbytes > 256); | |
929 | ||
930 | while (nbytes) { | |
931 | if (large_request && need_resched()) { | |
932 | if (signal_pending(current)) { | |
933 | if (ret == 0) | |
934 | ret = -ERESTARTSYS; | |
935 | break; | |
936 | } | |
937 | schedule(); | |
938 | } | |
939 | ||
940 | extract_crng(tmp); | |
941 | i = min_t(int, nbytes, CHACHA20_BLOCK_SIZE); | |
942 | if (copy_to_user(buf, tmp, i)) { | |
943 | ret = -EFAULT; | |
944 | break; | |
945 | } | |
946 | ||
947 | nbytes -= i; | |
948 | buf += i; | |
949 | ret += i; | |
950 | } | |
951 | crng_backtrack_protect(tmp, i); | |
952 | ||
953 | /* Wipe data just written to memory */ | |
954 | memzero_explicit(tmp, sizeof(tmp)); | |
955 | ||
956 | return ret; | |
957 | } | |
958 | ||
959 | ||
960 | /********************************************************************* | |
961 | * | |
962 | * Entropy input management | |
963 | * | |
964 | *********************************************************************/ | |
965 | ||
966 | /* There is one of these per entropy source */ | |
967 | struct timer_rand_state { | |
968 | cycles_t last_time; | |
969 | long last_delta, last_delta2; | |
970 | unsigned dont_count_entropy:1; | |
971 | }; | |
972 | ||
973 | #define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, }; | |
974 | ||
975 | /* | |
976 | * Add device- or boot-specific data to the input pool to help | |
977 | * initialize it. | |
978 | * | |
979 | * None of this adds any entropy; it is meant to avoid the problem of | |
980 | * the entropy pool having similar initial state across largely | |
981 | * identical devices. | |
982 | */ | |
983 | void add_device_randomness(const void *buf, unsigned int size) | |
984 | { | |
985 | unsigned long time = random_get_entropy() ^ jiffies; | |
986 | unsigned long flags; | |
987 | ||
988 | trace_add_device_randomness(size, _RET_IP_); | |
989 | spin_lock_irqsave(&input_pool.lock, flags); | |
990 | _mix_pool_bytes(&input_pool, buf, size); | |
991 | _mix_pool_bytes(&input_pool, &time, sizeof(time)); | |
992 | spin_unlock_irqrestore(&input_pool.lock, flags); | |
993 | } | |
994 | EXPORT_SYMBOL(add_device_randomness); | |
995 | ||
996 | static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE; | |
997 | ||
998 | /* | |
999 | * This function adds entropy to the entropy "pool" by using timing | |
1000 | * delays. It uses the timer_rand_state structure to make an estimate | |
1001 | * of how many bits of entropy this call has added to the pool. | |
1002 | * | |
1003 | * The number "num" is also added to the pool - it should somehow describe | |
1004 | * the type of event which just happened. This is currently 0-255 for | |
1005 | * keyboard scan codes, and 256 upwards for interrupts. | |
1006 | * | |
1007 | */ | |
1008 | static void add_timer_randomness(struct timer_rand_state *state, unsigned num) | |
1009 | { | |
1010 | struct entropy_store *r; | |
1011 | struct { | |
1012 | long jiffies; | |
1013 | unsigned cycles; | |
1014 | unsigned num; | |
1015 | } sample; | |
1016 | long delta, delta2, delta3; | |
1017 | ||
1018 | preempt_disable(); | |
1019 | ||
1020 | sample.jiffies = jiffies; | |
1021 | sample.cycles = random_get_entropy(); | |
1022 | sample.num = num; | |
1023 | r = &input_pool; | |
1024 | mix_pool_bytes(r, &sample, sizeof(sample)); | |
1025 | ||
1026 | /* | |
1027 | * Calculate number of bits of randomness we probably added. | |
1028 | * We take into account the first, second and third-order deltas | |
1029 | * in order to make our estimate. | |
1030 | */ | |
1031 | ||
1032 | if (!state->dont_count_entropy) { | |
1033 | delta = sample.jiffies - state->last_time; | |
1034 | state->last_time = sample.jiffies; | |
1035 | ||
1036 | delta2 = delta - state->last_delta; | |
1037 | state->last_delta = delta; | |
1038 | ||
1039 | delta3 = delta2 - state->last_delta2; | |
1040 | state->last_delta2 = delta2; | |
1041 | ||
1042 | if (delta < 0) | |
1043 | delta = -delta; | |
1044 | if (delta2 < 0) | |
1045 | delta2 = -delta2; | |
1046 | if (delta3 < 0) | |
1047 | delta3 = -delta3; | |
1048 | if (delta > delta2) | |
1049 | delta = delta2; | |
1050 | if (delta > delta3) | |
1051 | delta = delta3; | |
1052 | ||
1053 | /* | |
1054 | * delta is now minimum absolute delta. | |
1055 | * Round down by 1 bit on general principles, | |
1056 | * and limit entropy entimate to 12 bits. | |
1057 | */ | |
1058 | credit_entropy_bits(r, min_t(int, fls(delta>>1), 11)); | |
1059 | } | |
1060 | preempt_enable(); | |
1061 | } | |
1062 | ||
1063 | void add_input_randomness(unsigned int type, unsigned int code, | |
1064 | unsigned int value) | |
1065 | { | |
1066 | static unsigned char last_value; | |
1067 | ||
1068 | /* ignore autorepeat and the like */ | |
1069 | if (value == last_value) | |
1070 | return; | |
1071 | ||
1072 | last_value = value; | |
1073 | add_timer_randomness(&input_timer_state, | |
1074 | (type << 4) ^ code ^ (code >> 4) ^ value); | |
1075 | trace_add_input_randomness(ENTROPY_BITS(&input_pool)); | |
1076 | } | |
1077 | EXPORT_SYMBOL_GPL(add_input_randomness); | |
1078 | ||
1079 | static DEFINE_PER_CPU(struct fast_pool, irq_randomness); | |
1080 | ||
1081 | #ifdef ADD_INTERRUPT_BENCH | |
1082 | static unsigned long avg_cycles, avg_deviation; | |
1083 | ||
1084 | #define AVG_SHIFT 8 /* Exponential average factor k=1/256 */ | |
1085 | #define FIXED_1_2 (1 << (AVG_SHIFT-1)) | |
1086 | ||
1087 | static void add_interrupt_bench(cycles_t start) | |
1088 | { | |
1089 | long delta = random_get_entropy() - start; | |
1090 | ||
1091 | /* Use a weighted moving average */ | |
1092 | delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT); | |
1093 | avg_cycles += delta; | |
1094 | /* And average deviation */ | |
1095 | delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT); | |
1096 | avg_deviation += delta; | |
1097 | } | |
1098 | #else | |
1099 | #define add_interrupt_bench(x) | |
1100 | #endif | |
1101 | ||
1102 | static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs) | |
1103 | { | |
1104 | __u32 *ptr = (__u32 *) regs; | |
1105 | ||
1106 | if (regs == NULL) | |
1107 | return 0; | |
1108 | if (f->reg_idx >= sizeof(struct pt_regs) / sizeof(__u32)) | |
1109 | f->reg_idx = 0; | |
1110 | return *(ptr + f->reg_idx++); | |
1111 | } | |
1112 | ||
1113 | void add_interrupt_randomness(int irq, int irq_flags) | |
1114 | { | |
1115 | struct entropy_store *r; | |
1116 | struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness); | |
1117 | struct pt_regs *regs = get_irq_regs(); | |
1118 | unsigned long now = jiffies; | |
1119 | cycles_t cycles = random_get_entropy(); | |
1120 | __u32 c_high, j_high; | |
1121 | __u64 ip; | |
1122 | unsigned long seed; | |
1123 | int credit = 0; | |
1124 | ||
1125 | if (cycles == 0) | |
1126 | cycles = get_reg(fast_pool, regs); | |
1127 | c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0; | |
1128 | j_high = (sizeof(now) > 4) ? now >> 32 : 0; | |
1129 | fast_pool->pool[0] ^= cycles ^ j_high ^ irq; | |
1130 | fast_pool->pool[1] ^= now ^ c_high; | |
1131 | ip = regs ? instruction_pointer(regs) : _RET_IP_; | |
1132 | fast_pool->pool[2] ^= ip; | |
1133 | fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 : | |
1134 | get_reg(fast_pool, regs); | |
1135 | ||
1136 | fast_mix(fast_pool); | |
1137 | add_interrupt_bench(cycles); | |
1138 | ||
1139 | if (!crng_ready()) { | |
1140 | if ((fast_pool->count >= 64) && | |
1141 | crng_fast_load((char *) fast_pool->pool, | |
1142 | sizeof(fast_pool->pool))) { | |
1143 | fast_pool->count = 0; | |
1144 | fast_pool->last = now; | |
1145 | } | |
1146 | return; | |
1147 | } | |
1148 | ||
1149 | if ((fast_pool->count < 64) && | |
1150 | !time_after(now, fast_pool->last + HZ)) | |
1151 | return; | |
1152 | ||
1153 | r = &input_pool; | |
1154 | if (!spin_trylock(&r->lock)) | |
1155 | return; | |
1156 | ||
1157 | fast_pool->last = now; | |
1158 | __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool)); | |
1159 | ||
1160 | /* | |
1161 | * If we have architectural seed generator, produce a seed and | |
1162 | * add it to the pool. For the sake of paranoia don't let the | |
1163 | * architectural seed generator dominate the input from the | |
1164 | * interrupt noise. | |
1165 | */ | |
1166 | if (arch_get_random_seed_long(&seed)) { | |
1167 | __mix_pool_bytes(r, &seed, sizeof(seed)); | |
1168 | credit = 1; | |
1169 | } | |
1170 | spin_unlock(&r->lock); | |
1171 | ||
1172 | fast_pool->count = 0; | |
1173 | ||
1174 | /* award one bit for the contents of the fast pool */ | |
1175 | credit_entropy_bits(r, credit + 1); | |
1176 | } | |
1177 | EXPORT_SYMBOL_GPL(add_interrupt_randomness); | |
1178 | ||
1179 | #ifdef CONFIG_BLOCK | |
1180 | void add_disk_randomness(struct gendisk *disk) | |
1181 | { | |
1182 | if (!disk || !disk->random) | |
1183 | return; | |
1184 | /* first major is 1, so we get >= 0x200 here */ | |
1185 | add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); | |
1186 | trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS(&input_pool)); | |
1187 | } | |
1188 | EXPORT_SYMBOL_GPL(add_disk_randomness); | |
1189 | #endif | |
1190 | ||
1191 | /********************************************************************* | |
1192 | * | |
1193 | * Entropy extraction routines | |
1194 | * | |
1195 | *********************************************************************/ | |
1196 | ||
1197 | /* | |
1198 | * This utility inline function is responsible for transferring entropy | |
1199 | * from the primary pool to the secondary extraction pool. We make | |
1200 | * sure we pull enough for a 'catastrophic reseed'. | |
1201 | */ | |
1202 | static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes); | |
1203 | static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes) | |
1204 | { | |
1205 | if (!r->pull || | |
1206 | r->entropy_count >= (nbytes << (ENTROPY_SHIFT + 3)) || | |
1207 | r->entropy_count > r->poolinfo->poolfracbits) | |
1208 | return; | |
1209 | ||
1210 | _xfer_secondary_pool(r, nbytes); | |
1211 | } | |
1212 | ||
1213 | static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes) | |
1214 | { | |
1215 | __u32 tmp[OUTPUT_POOL_WORDS]; | |
1216 | ||
1217 | int bytes = nbytes; | |
1218 | ||
1219 | /* pull at least as much as a wakeup */ | |
1220 | bytes = max_t(int, bytes, random_read_wakeup_bits / 8); | |
1221 | /* but never more than the buffer size */ | |
1222 | bytes = min_t(int, bytes, sizeof(tmp)); | |
1223 | ||
1224 | trace_xfer_secondary_pool(r->name, bytes * 8, nbytes * 8, | |
1225 | ENTROPY_BITS(r), ENTROPY_BITS(r->pull)); | |
1226 | bytes = extract_entropy(r->pull, tmp, bytes, | |
1227 | random_read_wakeup_bits / 8, 0); | |
1228 | mix_pool_bytes(r, tmp, bytes); | |
1229 | credit_entropy_bits(r, bytes*8); | |
1230 | } | |
1231 | ||
1232 | /* | |
1233 | * Used as a workqueue function so that when the input pool is getting | |
1234 | * full, we can "spill over" some entropy to the output pools. That | |
1235 | * way the output pools can store some of the excess entropy instead | |
1236 | * of letting it go to waste. | |
1237 | */ | |
1238 | static void push_to_pool(struct work_struct *work) | |
1239 | { | |
1240 | struct entropy_store *r = container_of(work, struct entropy_store, | |
1241 | push_work); | |
1242 | BUG_ON(!r); | |
1243 | _xfer_secondary_pool(r, random_read_wakeup_bits/8); | |
1244 | trace_push_to_pool(r->name, r->entropy_count >> ENTROPY_SHIFT, | |
1245 | r->pull->entropy_count >> ENTROPY_SHIFT); | |
1246 | } | |
1247 | ||
1248 | /* | |
1249 | * This function decides how many bytes to actually take from the | |
1250 | * given pool, and also debits the entropy count accordingly. | |
1251 | */ | |
1252 | static size_t account(struct entropy_store *r, size_t nbytes, int min, | |
1253 | int reserved) | |
1254 | { | |
1255 | int entropy_count, orig, have_bytes; | |
1256 | size_t ibytes, nfrac; | |
1257 | ||
1258 | BUG_ON(r->entropy_count > r->poolinfo->poolfracbits); | |
1259 | ||
1260 | /* Can we pull enough? */ | |
1261 | retry: | |
1262 | entropy_count = orig = ACCESS_ONCE(r->entropy_count); | |
1263 | ibytes = nbytes; | |
1264 | /* never pull more than available */ | |
1265 | have_bytes = entropy_count >> (ENTROPY_SHIFT + 3); | |
1266 | ||
1267 | if ((have_bytes -= reserved) < 0) | |
1268 | have_bytes = 0; | |
1269 | ibytes = min_t(size_t, ibytes, have_bytes); | |
1270 | if (ibytes < min) | |
1271 | ibytes = 0; | |
1272 | ||
1273 | if (unlikely(entropy_count < 0)) { | |
1274 | pr_warn("random: negative entropy count: pool %s count %d\n", | |
1275 | r->name, entropy_count); | |
1276 | WARN_ON(1); | |
1277 | entropy_count = 0; | |
1278 | } | |
1279 | nfrac = ibytes << (ENTROPY_SHIFT + 3); | |
1280 | if ((size_t) entropy_count > nfrac) | |
1281 | entropy_count -= nfrac; | |
1282 | else | |
1283 | entropy_count = 0; | |
1284 | ||
1285 | if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) | |
1286 | goto retry; | |
1287 | ||
1288 | trace_debit_entropy(r->name, 8 * ibytes); | |
1289 | if (ibytes && | |
1290 | (r->entropy_count >> ENTROPY_SHIFT) < random_write_wakeup_bits) { | |
1291 | wake_up_interruptible(&random_write_wait); | |
1292 | kill_fasync(&fasync, SIGIO, POLL_OUT); | |
1293 | } | |
1294 | ||
1295 | return ibytes; | |
1296 | } | |
1297 | ||
1298 | /* | |
1299 | * This function does the actual extraction for extract_entropy and | |
1300 | * extract_entropy_user. | |
1301 | * | |
1302 | * Note: we assume that .poolwords is a multiple of 16 words. | |
1303 | */ | |
1304 | static void extract_buf(struct entropy_store *r, __u8 *out) | |
1305 | { | |
1306 | int i; | |
1307 | union { | |
1308 | __u32 w[5]; | |
1309 | unsigned long l[LONGS(20)]; | |
1310 | } hash; | |
1311 | __u32 workspace[SHA_WORKSPACE_WORDS]; | |
1312 | unsigned long flags; | |
1313 | ||
1314 | /* | |
1315 | * If we have an architectural hardware random number | |
1316 | * generator, use it for SHA's initial vector | |
1317 | */ | |
1318 | sha_init(hash.w); | |
1319 | for (i = 0; i < LONGS(20); i++) { | |
1320 | unsigned long v; | |
1321 | if (!arch_get_random_long(&v)) | |
1322 | break; | |
1323 | hash.l[i] = v; | |
1324 | } | |
1325 | ||
1326 | /* Generate a hash across the pool, 16 words (512 bits) at a time */ | |
1327 | spin_lock_irqsave(&r->lock, flags); | |
1328 | for (i = 0; i < r->poolinfo->poolwords; i += 16) | |
1329 | sha_transform(hash.w, (__u8 *)(r->pool + i), workspace); | |
1330 | ||
1331 | /* | |
1332 | * We mix the hash back into the pool to prevent backtracking | |
1333 | * attacks (where the attacker knows the state of the pool | |
1334 | * plus the current outputs, and attempts to find previous | |
1335 | * ouputs), unless the hash function can be inverted. By | |
1336 | * mixing at least a SHA1 worth of hash data back, we make | |
1337 | * brute-forcing the feedback as hard as brute-forcing the | |
1338 | * hash. | |
1339 | */ | |
1340 | __mix_pool_bytes(r, hash.w, sizeof(hash.w)); | |
1341 | spin_unlock_irqrestore(&r->lock, flags); | |
1342 | ||
1343 | memzero_explicit(workspace, sizeof(workspace)); | |
1344 | ||
1345 | /* | |
1346 | * In case the hash function has some recognizable output | |
1347 | * pattern, we fold it in half. Thus, we always feed back | |
1348 | * twice as much data as we output. | |
1349 | */ | |
1350 | hash.w[0] ^= hash.w[3]; | |
1351 | hash.w[1] ^= hash.w[4]; | |
1352 | hash.w[2] ^= rol32(hash.w[2], 16); | |
1353 | ||
1354 | memcpy(out, &hash, EXTRACT_SIZE); | |
1355 | memzero_explicit(&hash, sizeof(hash)); | |
1356 | } | |
1357 | ||
1358 | static ssize_t _extract_entropy(struct entropy_store *r, void *buf, | |
1359 | size_t nbytes, int fips) | |
1360 | { | |
1361 | ssize_t ret = 0, i; | |
1362 | __u8 tmp[EXTRACT_SIZE]; | |
1363 | unsigned long flags; | |
1364 | ||
1365 | while (nbytes) { | |
1366 | extract_buf(r, tmp); | |
1367 | ||
1368 | if (fips) { | |
1369 | spin_lock_irqsave(&r->lock, flags); | |
1370 | if (!memcmp(tmp, r->last_data, EXTRACT_SIZE)) | |
1371 | panic("Hardware RNG duplicated output!\n"); | |
1372 | memcpy(r->last_data, tmp, EXTRACT_SIZE); | |
1373 | spin_unlock_irqrestore(&r->lock, flags); | |
1374 | } | |
1375 | i = min_t(int, nbytes, EXTRACT_SIZE); | |
1376 | memcpy(buf, tmp, i); | |
1377 | nbytes -= i; | |
1378 | buf += i; | |
1379 | ret += i; | |
1380 | } | |
1381 | ||
1382 | /* Wipe data just returned from memory */ | |
1383 | memzero_explicit(tmp, sizeof(tmp)); | |
1384 | ||
1385 | return ret; | |
1386 | } | |
1387 | ||
1388 | /* | |
1389 | * This function extracts randomness from the "entropy pool", and | |
1390 | * returns it in a buffer. | |
1391 | * | |
1392 | * The min parameter specifies the minimum amount we can pull before | |
1393 | * failing to avoid races that defeat catastrophic reseeding while the | |
1394 | * reserved parameter indicates how much entropy we must leave in the | |
1395 | * pool after each pull to avoid starving other readers. | |
1396 | */ | |
1397 | static ssize_t extract_entropy(struct entropy_store *r, void *buf, | |
1398 | size_t nbytes, int min, int reserved) | |
1399 | { | |
1400 | __u8 tmp[EXTRACT_SIZE]; | |
1401 | unsigned long flags; | |
1402 | ||
1403 | /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */ | |
1404 | if (fips_enabled) { | |
1405 | spin_lock_irqsave(&r->lock, flags); | |
1406 | if (!r->last_data_init) { | |
1407 | r->last_data_init = 1; | |
1408 | spin_unlock_irqrestore(&r->lock, flags); | |
1409 | trace_extract_entropy(r->name, EXTRACT_SIZE, | |
1410 | ENTROPY_BITS(r), _RET_IP_); | |
1411 | xfer_secondary_pool(r, EXTRACT_SIZE); | |
1412 | extract_buf(r, tmp); | |
1413 | spin_lock_irqsave(&r->lock, flags); | |
1414 | memcpy(r->last_data, tmp, EXTRACT_SIZE); | |
1415 | } | |
1416 | spin_unlock_irqrestore(&r->lock, flags); | |
1417 | } | |
1418 | ||
1419 | trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_); | |
1420 | xfer_secondary_pool(r, nbytes); | |
1421 | nbytes = account(r, nbytes, min, reserved); | |
1422 | ||
1423 | return _extract_entropy(r, buf, nbytes, fips_enabled); | |
1424 | } | |
1425 | ||
1426 | /* | |
1427 | * This function extracts randomness from the "entropy pool", and | |
1428 | * returns it in a userspace buffer. | |
1429 | */ | |
1430 | static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf, | |
1431 | size_t nbytes) | |
1432 | { | |
1433 | ssize_t ret = 0, i; | |
1434 | __u8 tmp[EXTRACT_SIZE]; | |
1435 | int large_request = (nbytes > 256); | |
1436 | ||
1437 | trace_extract_entropy_user(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_); | |
1438 | xfer_secondary_pool(r, nbytes); | |
1439 | nbytes = account(r, nbytes, 0, 0); | |
1440 | ||
1441 | while (nbytes) { | |
1442 | if (large_request && need_resched()) { | |
1443 | if (signal_pending(current)) { | |
1444 | if (ret == 0) | |
1445 | ret = -ERESTARTSYS; | |
1446 | break; | |
1447 | } | |
1448 | schedule(); | |
1449 | } | |
1450 | ||
1451 | extract_buf(r, tmp); | |
1452 | i = min_t(int, nbytes, EXTRACT_SIZE); | |
1453 | if (copy_to_user(buf, tmp, i)) { | |
1454 | ret = -EFAULT; | |
1455 | break; | |
1456 | } | |
1457 | ||
1458 | nbytes -= i; | |
1459 | buf += i; | |
1460 | ret += i; | |
1461 | } | |
1462 | ||
1463 | /* Wipe data just returned from memory */ | |
1464 | memzero_explicit(tmp, sizeof(tmp)); | |
1465 | ||
1466 | return ret; | |
1467 | } | |
1468 | ||
1469 | /* | |
1470 | * This function is the exported kernel interface. It returns some | |
1471 | * number of good random numbers, suitable for key generation, seeding | |
1472 | * TCP sequence numbers, etc. It does not rely on the hardware random | |
1473 | * number generator. For random bytes direct from the hardware RNG | |
1474 | * (when available), use get_random_bytes_arch(). | |
1475 | */ | |
1476 | void get_random_bytes(void *buf, int nbytes) | |
1477 | { | |
1478 | __u8 tmp[CHACHA20_BLOCK_SIZE]; | |
1479 | ||
1480 | #if DEBUG_RANDOM_BOOT > 0 | |
1481 | if (!crng_ready()) | |
1482 | printk(KERN_NOTICE "random: %pF get_random_bytes called " | |
1483 | "with crng_init = %d\n", (void *) _RET_IP_, crng_init); | |
1484 | #endif | |
1485 | trace_get_random_bytes(nbytes, _RET_IP_); | |
1486 | ||
1487 | while (nbytes >= CHACHA20_BLOCK_SIZE) { | |
1488 | extract_crng(buf); | |
1489 | buf += CHACHA20_BLOCK_SIZE; | |
1490 | nbytes -= CHACHA20_BLOCK_SIZE; | |
1491 | } | |
1492 | ||
1493 | if (nbytes > 0) { | |
1494 | extract_crng(tmp); | |
1495 | memcpy(buf, tmp, nbytes); | |
1496 | crng_backtrack_protect(tmp, nbytes); | |
1497 | } else | |
1498 | crng_backtrack_protect(tmp, CHACHA20_BLOCK_SIZE); | |
1499 | memzero_explicit(tmp, sizeof(tmp)); | |
1500 | } | |
1501 | EXPORT_SYMBOL(get_random_bytes); | |
1502 | ||
1503 | /* | |
1504 | * Add a callback function that will be invoked when the nonblocking | |
1505 | * pool is initialised. | |
1506 | * | |
1507 | * returns: 0 if callback is successfully added | |
1508 | * -EALREADY if pool is already initialised (callback not called) | |
1509 | * -ENOENT if module for callback is not alive | |
1510 | */ | |
1511 | int add_random_ready_callback(struct random_ready_callback *rdy) | |
1512 | { | |
1513 | struct module *owner; | |
1514 | unsigned long flags; | |
1515 | int err = -EALREADY; | |
1516 | ||
1517 | if (crng_ready()) | |
1518 | return err; | |
1519 | ||
1520 | owner = rdy->owner; | |
1521 | if (!try_module_get(owner)) | |
1522 | return -ENOENT; | |
1523 | ||
1524 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
1525 | if (crng_ready()) | |
1526 | goto out; | |
1527 | ||
1528 | owner = NULL; | |
1529 | ||
1530 | list_add(&rdy->list, &random_ready_list); | |
1531 | err = 0; | |
1532 | ||
1533 | out: | |
1534 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
1535 | ||
1536 | module_put(owner); | |
1537 | ||
1538 | return err; | |
1539 | } | |
1540 | EXPORT_SYMBOL(add_random_ready_callback); | |
1541 | ||
1542 | /* | |
1543 | * Delete a previously registered readiness callback function. | |
1544 | */ | |
1545 | void del_random_ready_callback(struct random_ready_callback *rdy) | |
1546 | { | |
1547 | unsigned long flags; | |
1548 | struct module *owner = NULL; | |
1549 | ||
1550 | spin_lock_irqsave(&random_ready_list_lock, flags); | |
1551 | if (!list_empty(&rdy->list)) { | |
1552 | list_del_init(&rdy->list); | |
1553 | owner = rdy->owner; | |
1554 | } | |
1555 | spin_unlock_irqrestore(&random_ready_list_lock, flags); | |
1556 | ||
1557 | module_put(owner); | |
1558 | } | |
1559 | EXPORT_SYMBOL(del_random_ready_callback); | |
1560 | ||
1561 | /* | |
1562 | * This function will use the architecture-specific hardware random | |
1563 | * number generator if it is available. The arch-specific hw RNG will | |
1564 | * almost certainly be faster than what we can do in software, but it | |
1565 | * is impossible to verify that it is implemented securely (as | |
1566 | * opposed, to, say, the AES encryption of a sequence number using a | |
1567 | * key known by the NSA). So it's useful if we need the speed, but | |
1568 | * only if we're willing to trust the hardware manufacturer not to | |
1569 | * have put in a back door. | |
1570 | */ | |
1571 | void get_random_bytes_arch(void *buf, int nbytes) | |
1572 | { | |
1573 | char *p = buf; | |
1574 | ||
1575 | trace_get_random_bytes_arch(nbytes, _RET_IP_); | |
1576 | while (nbytes) { | |
1577 | unsigned long v; | |
1578 | int chunk = min(nbytes, (int)sizeof(unsigned long)); | |
1579 | ||
1580 | if (!arch_get_random_long(&v)) | |
1581 | break; | |
1582 | ||
1583 | memcpy(p, &v, chunk); | |
1584 | p += chunk; | |
1585 | nbytes -= chunk; | |
1586 | } | |
1587 | ||
1588 | if (nbytes) | |
1589 | get_random_bytes(p, nbytes); | |
1590 | } | |
1591 | EXPORT_SYMBOL(get_random_bytes_arch); | |
1592 | ||
1593 | ||
1594 | /* | |
1595 | * init_std_data - initialize pool with system data | |
1596 | * | |
1597 | * @r: pool to initialize | |
1598 | * | |
1599 | * This function clears the pool's entropy count and mixes some system | |
1600 | * data into the pool to prepare it for use. The pool is not cleared | |
1601 | * as that can only decrease the entropy in the pool. | |
1602 | */ | |
1603 | static void init_std_data(struct entropy_store *r) | |
1604 | { | |
1605 | int i; | |
1606 | ktime_t now = ktime_get_real(); | |
1607 | unsigned long rv; | |
1608 | ||
1609 | r->last_pulled = jiffies; | |
1610 | mix_pool_bytes(r, &now, sizeof(now)); | |
1611 | for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) { | |
1612 | if (!arch_get_random_seed_long(&rv) && | |
1613 | !arch_get_random_long(&rv)) | |
1614 | rv = random_get_entropy(); | |
1615 | mix_pool_bytes(r, &rv, sizeof(rv)); | |
1616 | } | |
1617 | mix_pool_bytes(r, utsname(), sizeof(*(utsname()))); | |
1618 | } | |
1619 | ||
1620 | /* | |
1621 | * Note that setup_arch() may call add_device_randomness() | |
1622 | * long before we get here. This allows seeding of the pools | |
1623 | * with some platform dependent data very early in the boot | |
1624 | * process. But it limits our options here. We must use | |
1625 | * statically allocated structures that already have all | |
1626 | * initializations complete at compile time. We should also | |
1627 | * take care not to overwrite the precious per platform data | |
1628 | * we were given. | |
1629 | */ | |
1630 | static int rand_initialize(void) | |
1631 | { | |
1632 | #ifdef CONFIG_NUMA | |
1633 | int i; | |
1634 | struct crng_state *crng; | |
1635 | struct crng_state **pool; | |
1636 | #endif | |
1637 | ||
1638 | init_std_data(&input_pool); | |
1639 | init_std_data(&blocking_pool); | |
1640 | crng_initialize(&primary_crng); | |
1641 | ||
1642 | #ifdef CONFIG_NUMA | |
1643 | pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL); | |
1644 | for_each_online_node(i) { | |
1645 | crng = kmalloc_node(sizeof(struct crng_state), | |
1646 | GFP_KERNEL | __GFP_NOFAIL, i); | |
1647 | spin_lock_init(&crng->lock); | |
1648 | crng_initialize(crng); | |
1649 | pool[i] = crng; | |
1650 | } | |
1651 | mb(); | |
1652 | crng_node_pool = pool; | |
1653 | #endif | |
1654 | return 0; | |
1655 | } | |
1656 | early_initcall(rand_initialize); | |
1657 | ||
1658 | #ifdef CONFIG_BLOCK | |
1659 | void rand_initialize_disk(struct gendisk *disk) | |
1660 | { | |
1661 | struct timer_rand_state *state; | |
1662 | ||
1663 | /* | |
1664 | * If kzalloc returns null, we just won't use that entropy | |
1665 | * source. | |
1666 | */ | |
1667 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); | |
1668 | if (state) { | |
1669 | state->last_time = INITIAL_JIFFIES; | |
1670 | disk->random = state; | |
1671 | } | |
1672 | } | |
1673 | #endif | |
1674 | ||
1675 | static ssize_t | |
1676 | _random_read(int nonblock, char __user *buf, size_t nbytes) | |
1677 | { | |
1678 | ssize_t n; | |
1679 | ||
1680 | if (nbytes == 0) | |
1681 | return 0; | |
1682 | ||
1683 | nbytes = min_t(size_t, nbytes, SEC_XFER_SIZE); | |
1684 | while (1) { | |
1685 | n = extract_entropy_user(&blocking_pool, buf, nbytes); | |
1686 | if (n < 0) | |
1687 | return n; | |
1688 | trace_random_read(n*8, (nbytes-n)*8, | |
1689 | ENTROPY_BITS(&blocking_pool), | |
1690 | ENTROPY_BITS(&input_pool)); | |
1691 | if (n > 0) | |
1692 | return n; | |
1693 | ||
1694 | /* Pool is (near) empty. Maybe wait and retry. */ | |
1695 | if (nonblock) | |
1696 | return -EAGAIN; | |
1697 | ||
1698 | wait_event_interruptible(random_read_wait, | |
1699 | ENTROPY_BITS(&input_pool) >= | |
1700 | random_read_wakeup_bits); | |
1701 | if (signal_pending(current)) | |
1702 | return -ERESTARTSYS; | |
1703 | } | |
1704 | } | |
1705 | ||
1706 | static ssize_t | |
1707 | random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) | |
1708 | { | |
1709 | return _random_read(file->f_flags & O_NONBLOCK, buf, nbytes); | |
1710 | } | |
1711 | ||
1712 | static ssize_t | |
1713 | urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) | |
1714 | { | |
1715 | unsigned long flags; | |
1716 | static int maxwarn = 10; | |
1717 | int ret; | |
1718 | ||
1719 | if (!crng_ready() && maxwarn > 0) { | |
1720 | maxwarn--; | |
1721 | printk(KERN_NOTICE "random: %s: uninitialized urandom read " | |
1722 | "(%zd bytes read)\n", | |
1723 | current->comm, nbytes); | |
1724 | spin_lock_irqsave(&primary_crng.lock, flags); | |
1725 | crng_init_cnt = 0; | |
1726 | spin_unlock_irqrestore(&primary_crng.lock, flags); | |
1727 | } | |
1728 | nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3)); | |
1729 | ret = extract_crng_user(buf, nbytes); | |
1730 | trace_urandom_read(8 * nbytes, 0, ENTROPY_BITS(&input_pool)); | |
1731 | return ret; | |
1732 | } | |
1733 | ||
1734 | static unsigned int | |
1735 | random_poll(struct file *file, poll_table * wait) | |
1736 | { | |
1737 | unsigned int mask; | |
1738 | ||
1739 | poll_wait(file, &random_read_wait, wait); | |
1740 | poll_wait(file, &random_write_wait, wait); | |
1741 | mask = 0; | |
1742 | if (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits) | |
1743 | mask |= POLLIN | POLLRDNORM; | |
1744 | if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits) | |
1745 | mask |= POLLOUT | POLLWRNORM; | |
1746 | return mask; | |
1747 | } | |
1748 | ||
1749 | static int | |
1750 | write_pool(struct entropy_store *r, const char __user *buffer, size_t count) | |
1751 | { | |
1752 | size_t bytes; | |
1753 | __u32 buf[16]; | |
1754 | const char __user *p = buffer; | |
1755 | ||
1756 | while (count > 0) { | |
1757 | bytes = min(count, sizeof(buf)); | |
1758 | if (copy_from_user(&buf, p, bytes)) | |
1759 | return -EFAULT; | |
1760 | ||
1761 | count -= bytes; | |
1762 | p += bytes; | |
1763 | ||
1764 | mix_pool_bytes(r, buf, bytes); | |
1765 | cond_resched(); | |
1766 | } | |
1767 | ||
1768 | return 0; | |
1769 | } | |
1770 | ||
1771 | static ssize_t random_write(struct file *file, const char __user *buffer, | |
1772 | size_t count, loff_t *ppos) | |
1773 | { | |
1774 | size_t ret; | |
1775 | ||
1776 | ret = write_pool(&input_pool, buffer, count); | |
1777 | if (ret) | |
1778 | return ret; | |
1779 | ||
1780 | return (ssize_t)count; | |
1781 | } | |
1782 | ||
1783 | static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) | |
1784 | { | |
1785 | int size, ent_count; | |
1786 | int __user *p = (int __user *)arg; | |
1787 | int retval; | |
1788 | ||
1789 | switch (cmd) { | |
1790 | case RNDGETENTCNT: | |
1791 | /* inherently racy, no point locking */ | |
1792 | ent_count = ENTROPY_BITS(&input_pool); | |
1793 | if (put_user(ent_count, p)) | |
1794 | return -EFAULT; | |
1795 | return 0; | |
1796 | case RNDADDTOENTCNT: | |
1797 | if (!capable(CAP_SYS_ADMIN)) | |
1798 | return -EPERM; | |
1799 | if (get_user(ent_count, p)) | |
1800 | return -EFAULT; | |
1801 | return credit_entropy_bits_safe(&input_pool, ent_count); | |
1802 | case RNDADDENTROPY: | |
1803 | if (!capable(CAP_SYS_ADMIN)) | |
1804 | return -EPERM; | |
1805 | if (get_user(ent_count, p++)) | |
1806 | return -EFAULT; | |
1807 | if (ent_count < 0) | |
1808 | return -EINVAL; | |
1809 | if (get_user(size, p++)) | |
1810 | return -EFAULT; | |
1811 | retval = write_pool(&input_pool, (const char __user *)p, | |
1812 | size); | |
1813 | if (retval < 0) | |
1814 | return retval; | |
1815 | return credit_entropy_bits_safe(&input_pool, ent_count); | |
1816 | case RNDZAPENTCNT: | |
1817 | case RNDCLEARPOOL: | |
1818 | /* | |
1819 | * Clear the entropy pool counters. We no longer clear | |
1820 | * the entropy pool, as that's silly. | |
1821 | */ | |
1822 | if (!capable(CAP_SYS_ADMIN)) | |
1823 | return -EPERM; | |
1824 | input_pool.entropy_count = 0; | |
1825 | blocking_pool.entropy_count = 0; | |
1826 | return 0; | |
1827 | default: | |
1828 | return -EINVAL; | |
1829 | } | |
1830 | } | |
1831 | ||
1832 | static int random_fasync(int fd, struct file *filp, int on) | |
1833 | { | |
1834 | return fasync_helper(fd, filp, on, &fasync); | |
1835 | } | |
1836 | ||
1837 | const struct file_operations random_fops = { | |
1838 | .read = random_read, | |
1839 | .write = random_write, | |
1840 | .poll = random_poll, | |
1841 | .unlocked_ioctl = random_ioctl, | |
1842 | .fasync = random_fasync, | |
1843 | .llseek = noop_llseek, | |
1844 | }; | |
1845 | ||
1846 | const struct file_operations urandom_fops = { | |
1847 | .read = urandom_read, | |
1848 | .write = random_write, | |
1849 | .unlocked_ioctl = random_ioctl, | |
1850 | .fasync = random_fasync, | |
1851 | .llseek = noop_llseek, | |
1852 | }; | |
1853 | ||
1854 | SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, | |
1855 | unsigned int, flags) | |
1856 | { | |
1857 | if (flags & ~(GRND_NONBLOCK|GRND_RANDOM)) | |
1858 | return -EINVAL; | |
1859 | ||
1860 | if (count > INT_MAX) | |
1861 | count = INT_MAX; | |
1862 | ||
1863 | if (flags & GRND_RANDOM) | |
1864 | return _random_read(flags & GRND_NONBLOCK, buf, count); | |
1865 | ||
1866 | if (!crng_ready()) { | |
1867 | if (flags & GRND_NONBLOCK) | |
1868 | return -EAGAIN; | |
1869 | crng_wait_ready(); | |
1870 | if (signal_pending(current)) | |
1871 | return -ERESTARTSYS; | |
1872 | } | |
1873 | return urandom_read(NULL, buf, count, NULL); | |
1874 | } | |
1875 | ||
1876 | /******************************************************************** | |
1877 | * | |
1878 | * Sysctl interface | |
1879 | * | |
1880 | ********************************************************************/ | |
1881 | ||
1882 | #ifdef CONFIG_SYSCTL | |
1883 | ||
1884 | #include <linux/sysctl.h> | |
1885 | ||
1886 | static int min_read_thresh = 8, min_write_thresh; | |
1887 | static int max_read_thresh = OUTPUT_POOL_WORDS * 32; | |
1888 | static int max_write_thresh = INPUT_POOL_WORDS * 32; | |
1889 | static char sysctl_bootid[16]; | |
1890 | ||
1891 | /* | |
1892 | * This function is used to return both the bootid UUID, and random | |
1893 | * UUID. The difference is in whether table->data is NULL; if it is, | |
1894 | * then a new UUID is generated and returned to the user. | |
1895 | * | |
1896 | * If the user accesses this via the proc interface, the UUID will be | |
1897 | * returned as an ASCII string in the standard UUID format; if via the | |
1898 | * sysctl system call, as 16 bytes of binary data. | |
1899 | */ | |
1900 | static int proc_do_uuid(struct ctl_table *table, int write, | |
1901 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
1902 | { | |
1903 | struct ctl_table fake_table; | |
1904 | unsigned char buf[64], tmp_uuid[16], *uuid; | |
1905 | ||
1906 | uuid = table->data; | |
1907 | if (!uuid) { | |
1908 | uuid = tmp_uuid; | |
1909 | generate_random_uuid(uuid); | |
1910 | } else { | |
1911 | static DEFINE_SPINLOCK(bootid_spinlock); | |
1912 | ||
1913 | spin_lock(&bootid_spinlock); | |
1914 | if (!uuid[8]) | |
1915 | generate_random_uuid(uuid); | |
1916 | spin_unlock(&bootid_spinlock); | |
1917 | } | |
1918 | ||
1919 | sprintf(buf, "%pU", uuid); | |
1920 | ||
1921 | fake_table.data = buf; | |
1922 | fake_table.maxlen = sizeof(buf); | |
1923 | ||
1924 | return proc_dostring(&fake_table, write, buffer, lenp, ppos); | |
1925 | } | |
1926 | ||
1927 | /* | |
1928 | * Return entropy available scaled to integral bits | |
1929 | */ | |
1930 | static int proc_do_entropy(struct ctl_table *table, int write, | |
1931 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
1932 | { | |
1933 | struct ctl_table fake_table; | |
1934 | int entropy_count; | |
1935 | ||
1936 | entropy_count = *(int *)table->data >> ENTROPY_SHIFT; | |
1937 | ||
1938 | fake_table.data = &entropy_count; | |
1939 | fake_table.maxlen = sizeof(entropy_count); | |
1940 | ||
1941 | return proc_dointvec(&fake_table, write, buffer, lenp, ppos); | |
1942 | } | |
1943 | ||
1944 | static int sysctl_poolsize = INPUT_POOL_WORDS * 32; | |
1945 | extern struct ctl_table random_table[]; | |
1946 | struct ctl_table random_table[] = { | |
1947 | { | |
1948 | .procname = "poolsize", | |
1949 | .data = &sysctl_poolsize, | |
1950 | .maxlen = sizeof(int), | |
1951 | .mode = 0444, | |
1952 | .proc_handler = proc_dointvec, | |
1953 | }, | |
1954 | { | |
1955 | .procname = "entropy_avail", | |
1956 | .maxlen = sizeof(int), | |
1957 | .mode = 0444, | |
1958 | .proc_handler = proc_do_entropy, | |
1959 | .data = &input_pool.entropy_count, | |
1960 | }, | |
1961 | { | |
1962 | .procname = "read_wakeup_threshold", | |
1963 | .data = &random_read_wakeup_bits, | |
1964 | .maxlen = sizeof(int), | |
1965 | .mode = 0644, | |
1966 | .proc_handler = proc_dointvec_minmax, | |
1967 | .extra1 = &min_read_thresh, | |
1968 | .extra2 = &max_read_thresh, | |
1969 | }, | |
1970 | { | |
1971 | .procname = "write_wakeup_threshold", | |
1972 | .data = &random_write_wakeup_bits, | |
1973 | .maxlen = sizeof(int), | |
1974 | .mode = 0644, | |
1975 | .proc_handler = proc_dointvec_minmax, | |
1976 | .extra1 = &min_write_thresh, | |
1977 | .extra2 = &max_write_thresh, | |
1978 | }, | |
1979 | { | |
1980 | .procname = "urandom_min_reseed_secs", | |
1981 | .data = &random_min_urandom_seed, | |
1982 | .maxlen = sizeof(int), | |
1983 | .mode = 0644, | |
1984 | .proc_handler = proc_dointvec, | |
1985 | }, | |
1986 | { | |
1987 | .procname = "boot_id", | |
1988 | .data = &sysctl_bootid, | |
1989 | .maxlen = 16, | |
1990 | .mode = 0444, | |
1991 | .proc_handler = proc_do_uuid, | |
1992 | }, | |
1993 | { | |
1994 | .procname = "uuid", | |
1995 | .maxlen = 16, | |
1996 | .mode = 0444, | |
1997 | .proc_handler = proc_do_uuid, | |
1998 | }, | |
1999 | #ifdef ADD_INTERRUPT_BENCH | |
2000 | { | |
2001 | .procname = "add_interrupt_avg_cycles", | |
2002 | .data = &avg_cycles, | |
2003 | .maxlen = sizeof(avg_cycles), | |
2004 | .mode = 0444, | |
2005 | .proc_handler = proc_doulongvec_minmax, | |
2006 | }, | |
2007 | { | |
2008 | .procname = "add_interrupt_avg_deviation", | |
2009 | .data = &avg_deviation, | |
2010 | .maxlen = sizeof(avg_deviation), | |
2011 | .mode = 0444, | |
2012 | .proc_handler = proc_doulongvec_minmax, | |
2013 | }, | |
2014 | #endif | |
2015 | { } | |
2016 | }; | |
2017 | #endif /* CONFIG_SYSCTL */ | |
2018 | ||
2019 | static u32 random_int_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned; | |
2020 | ||
2021 | int random_int_secret_init(void) | |
2022 | { | |
2023 | get_random_bytes(random_int_secret, sizeof(random_int_secret)); | |
2024 | return 0; | |
2025 | } | |
2026 | ||
2027 | static DEFINE_PER_CPU(__u32 [MD5_DIGEST_WORDS], get_random_int_hash) | |
2028 | __aligned(sizeof(unsigned long)); | |
2029 | ||
2030 | /* | |
2031 | * Get a random word for internal kernel use only. Similar to urandom but | |
2032 | * with the goal of minimal entropy pool depletion. As a result, the random | |
2033 | * value is not cryptographically secure but for several uses the cost of | |
2034 | * depleting entropy is too high | |
2035 | */ | |
2036 | unsigned int get_random_int(void) | |
2037 | { | |
2038 | __u32 *hash; | |
2039 | unsigned int ret; | |
2040 | ||
2041 | if (arch_get_random_int(&ret)) | |
2042 | return ret; | |
2043 | ||
2044 | hash = get_cpu_var(get_random_int_hash); | |
2045 | ||
2046 | hash[0] += current->pid + jiffies + random_get_entropy(); | |
2047 | md5_transform(hash, random_int_secret); | |
2048 | ret = hash[0]; | |
2049 | put_cpu_var(get_random_int_hash); | |
2050 | ||
2051 | return ret; | |
2052 | } | |
2053 | EXPORT_SYMBOL(get_random_int); | |
2054 | ||
2055 | /* | |
2056 | * Same as get_random_int(), but returns unsigned long. | |
2057 | */ | |
2058 | unsigned long get_random_long(void) | |
2059 | { | |
2060 | __u32 *hash; | |
2061 | unsigned long ret; | |
2062 | ||
2063 | if (arch_get_random_long(&ret)) | |
2064 | return ret; | |
2065 | ||
2066 | hash = get_cpu_var(get_random_int_hash); | |
2067 | ||
2068 | hash[0] += current->pid + jiffies + random_get_entropy(); | |
2069 | md5_transform(hash, random_int_secret); | |
2070 | ret = *(unsigned long *)hash; | |
2071 | put_cpu_var(get_random_int_hash); | |
2072 | ||
2073 | return ret; | |
2074 | } | |
2075 | EXPORT_SYMBOL(get_random_long); | |
2076 | ||
2077 | /** | |
2078 | * randomize_page - Generate a random, page aligned address | |
2079 | * @start: The smallest acceptable address the caller will take. | |
2080 | * @range: The size of the area, starting at @start, within which the | |
2081 | * random address must fall. | |
2082 | * | |
2083 | * If @start + @range would overflow, @range is capped. | |
2084 | * | |
2085 | * NOTE: Historical use of randomize_range, which this replaces, presumed that | |
2086 | * @start was already page aligned. We now align it regardless. | |
2087 | * | |
2088 | * Return: A page aligned address within [start, start + range). On error, | |
2089 | * @start is returned. | |
2090 | */ | |
2091 | unsigned long | |
2092 | randomize_page(unsigned long start, unsigned long range) | |
2093 | { | |
2094 | if (!PAGE_ALIGNED(start)) { | |
2095 | range -= PAGE_ALIGN(start) - start; | |
2096 | start = PAGE_ALIGN(start); | |
2097 | } | |
2098 | ||
2099 | if (start > ULONG_MAX - range) | |
2100 | range = ULONG_MAX - start; | |
2101 | ||
2102 | range >>= PAGE_SHIFT; | |
2103 | ||
2104 | if (range == 0) | |
2105 | return start; | |
2106 | ||
2107 | return start + (get_random_long() % range << PAGE_SHIFT); | |
2108 | } | |
2109 | ||
2110 | /* Interface for in-kernel drivers of true hardware RNGs. | |
2111 | * Those devices may produce endless random bits and will be throttled | |
2112 | * when our pool is full. | |
2113 | */ | |
2114 | void add_hwgenerator_randomness(const char *buffer, size_t count, | |
2115 | size_t entropy) | |
2116 | { | |
2117 | struct entropy_store *poolp = &input_pool; | |
2118 | ||
2119 | if (!crng_ready()) { | |
2120 | crng_fast_load(buffer, count); | |
2121 | return; | |
2122 | } | |
2123 | ||
2124 | /* Suspend writing if we're above the trickle threshold. | |
2125 | * We'll be woken up again once below random_write_wakeup_thresh, | |
2126 | * or when the calling thread is about to terminate. | |
2127 | */ | |
2128 | wait_event_interruptible(random_write_wait, kthread_should_stop() || | |
2129 | ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits); | |
2130 | mix_pool_bytes(poolp, buffer, count); | |
2131 | credit_entropy_bits(poolp, entropy); | |
2132 | } | |
2133 | EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); |