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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * random.c -- A strong random number generator
3 *
Matt Mackall9e95ce22005-04-16 15:25:56 -07004 * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 *
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 *
Linus Torvaldsa2080a62012-07-04 11:16:01 -0400128 * void add_device_randomness(const void *buf, unsigned int size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 * void add_input_randomness(unsigned int type, unsigned int code,
130 * unsigned int value);
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400131 * void add_interrupt_randomness(int irq, int irq_flags);
Jarod Wilson442a4ff2011-02-21 21:43:10 +1100132 * void add_disk_randomness(struct gendisk *disk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 *
Linus Torvaldsa2080a62012-07-04 11:16:01 -0400134 * 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 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 * add_input_randomness() uses the input layer interrupt timing, as well as
143 * the event type information from the hardware.
144 *
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400145 * 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.
Jarod Wilson442a4ff2011-02-21 21:43:10 +1100148 *
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.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 *
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>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239#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>
Andrea Righi27ac7922008-07-23 21:28:13 -0700251#include <linux/mm.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252#include <linux/spinlock.h>
Torsten Duwec84dbf62014-06-14 23:38:36 -0400253#include <linux/kthread.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254#include <linux/percpu.h>
255#include <linux/cryptohash.h>
Neil Horman5b739ef2009-06-18 19:50:21 +0800256#include <linux/fips.h>
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400257#include <linux/ptrace.h>
Theodore Ts'oe6d49472012-07-05 10:21:01 -0400258#include <linux/kmemcheck.h>
Theodore Ts'o6265e162013-10-03 01:08:15 -0400259#include <linux/workqueue.h>
Martin Schwidefsky0244ad02013-08-30 09:39:53 +0200260#include <linux/irq.h>
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -0400261#include <linux/syscalls.h>
262#include <linux/completion.h>
Andy Shevchenko8da4b8c2016-05-20 17:01:00 -0700263#include <linux/uuid.h>
Yinghai Lud178a1e2009-01-11 00:35:42 -0800264
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265#include <asm/processor.h>
266#include <asm/uaccess.h>
267#include <asm/irq.h>
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400268#include <asm/irq_regs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269#include <asm/io.h>
270
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400271#define CREATE_TRACE_POINTS
272#include <trace/events/random.h>
273
Theodore Ts'o43759d42014-06-14 21:43:13 -0400274/* #define ADD_INTERRUPT_BENCH */
275
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276/*
277 * Configuration information
278 */
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400279#define INPUT_POOL_SHIFT 12
280#define INPUT_POOL_WORDS (1 << (INPUT_POOL_SHIFT-5))
281#define OUTPUT_POOL_SHIFT 10
282#define OUTPUT_POOL_WORDS (1 << (OUTPUT_POOL_SHIFT-5))
283#define SEC_XFER_SIZE 512
284#define EXTRACT_SIZE 10
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285
Theodore Ts'o392a5462013-11-03 18:24:08 -0500286#define DEBUG_RANDOM_BOOT 0
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287
H. Peter Anvind2e7c962012-07-27 22:26:08 -0400288#define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long))
289
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290/*
Theodore Ts'o95b709b2013-10-02 21:10:35 -0400291 * To allow fractional bits to be tracked, the entropy_count field is
292 * denominated in units of 1/8th bits.
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400293 *
294 * 2*(ENTROPY_SHIFT + log2(poolbits)) must <= 31, or the multiply in
295 * credit_entropy_bits() needs to be 64 bits wide.
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400296 */
297#define ENTROPY_SHIFT 3
298#define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT)
299
300/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 * The minimum number of bits of entropy before we wake up a read on
302 * /dev/random. Should be enough to do a significant reseed.
303 */
Greg Price2132a962013-12-06 21:28:03 -0500304static int random_read_wakeup_bits = 64;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305
306/*
307 * If the entropy count falls under this number of bits, then we
308 * should wake up processes which are selecting or polling on write
309 * access to /dev/random.
310 */
Greg Price2132a962013-12-06 21:28:03 -0500311static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312
313/*
Greg Pricedfd38752013-11-29 14:58:06 -0500314 * The minimum number of seconds between urandom pool reseeding. We
Theodore Ts'of5c27422013-09-22 15:14:32 -0400315 * do this to limit the amount of entropy that can be drained from the
316 * input pool even if there are heavy demands on /dev/urandom.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 */
Theodore Ts'of5c27422013-09-22 15:14:32 -0400318static int random_min_urandom_seed = 60;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319
320/*
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400321 * 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.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325 *
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400326 * 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
Greg Pricedfd38752013-11-29 14:58:06 -0500331 * GFSR generators II. ACM Transactions on Modeling and Computer
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400332 * Simulation 4:254-266)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 *
334 * Thanks to Colin Plumb for suggesting this.
335 *
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400336 * 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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 * decrease the uncertainty).
352 *
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400353 * 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.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365static struct poolinfo {
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400366 int poolbitshift, poolwords, poolbytes, poolbits, poolfracbits;
367#define S(x) ilog2(x)+5, (x), (x)*4, (x)*32, (x) << (ENTROPY_SHIFT+5)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 int tap1, tap2, tap3, tap4, tap5;
369} poolinfo_table[] = {
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400370 /* 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 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376#if 0
377 /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400378 { S(2048), 1638, 1231, 819, 411, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379
380 /* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400381 { S(1024), 817, 615, 412, 204, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382
383 /* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400384 { S(1024), 819, 616, 410, 207, 2 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385
386 /* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400387 { S(512), 411, 308, 208, 104, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388
389 /* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400390 { S(512), 409, 307, 206, 102, 2 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 /* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400392 { S(512), 409, 309, 205, 103, 2 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393
394 /* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400395 { S(256), 205, 155, 101, 52, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396
397 /* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400398 { S(128), 103, 78, 51, 27, 2 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399
400 /* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400401 { S(64), 52, 39, 26, 14, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402#endif
403};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404
405/*
406 * Static global variables
407 */
408static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
409static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -0400410static DECLARE_WAIT_QUEUE_HEAD(urandom_init_wait);
Jeff Dike9a6f70b2008-04-29 01:03:08 -0700411static struct fasync_struct *fasync;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412
Herbert Xu205a5252015-06-09 18:19:39 +0800413static DEFINE_SPINLOCK(random_ready_list_lock);
414static LIST_HEAD(random_ready_list);
415
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416/**********************************************************************
417 *
418 * OS independent entropy store. Here are the functions which handle
419 * storing entropy in an entropy pool.
420 *
421 **********************************************************************/
422
423struct entropy_store;
424struct entropy_store {
Matt Mackall43358202008-04-29 01:03:01 -0700425 /* read-only data: */
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400426 const struct poolinfo *poolinfo;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 __u32 *pool;
428 const char *name;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 struct entropy_store *pull;
Theodore Ts'o6265e162013-10-03 01:08:15 -0400430 struct work_struct push_work;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431
432 /* read-write data: */
Theodore Ts'of5c27422013-09-22 15:14:32 -0400433 unsigned long last_pulled;
Matt Mackall43358202008-04-29 01:03:01 -0700434 spinlock_t lock;
Theodore Ts'oc59974a2013-09-21 19:42:41 -0400435 unsigned short add_ptr;
436 unsigned short input_rotate;
Matt Mackallcda796a2009-01-06 14:42:55 -0800437 int entropy_count;
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400438 int entropy_total;
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400439 unsigned int initialized:1;
Theodore Ts'oc59974a2013-09-21 19:42:41 -0400440 unsigned int limit:1;
441 unsigned int last_data_init:1;
Matt Mackalle954bc92010-05-20 19:55:01 +1000442 __u8 last_data[EXTRACT_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443};
444
Theodore Ts'o6265e162013-10-03 01:08:15 -0400445static void push_to_pool(struct work_struct *work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446static __u32 input_pool_data[INPUT_POOL_WORDS];
447static __u32 blocking_pool_data[OUTPUT_POOL_WORDS];
448static __u32 nonblocking_pool_data[OUTPUT_POOL_WORDS];
449
450static struct entropy_store input_pool = {
451 .poolinfo = &poolinfo_table[0],
452 .name = "input",
453 .limit = 1,
Thomas Gleixnereece09e2011-07-17 21:25:03 +0200454 .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 .pool = input_pool_data
456};
457
458static struct entropy_store blocking_pool = {
459 .poolinfo = &poolinfo_table[1],
460 .name = "blocking",
461 .limit = 1,
462 .pull = &input_pool,
Thomas Gleixnereece09e2011-07-17 21:25:03 +0200463 .lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock),
Theodore Ts'o6265e162013-10-03 01:08:15 -0400464 .pool = blocking_pool_data,
465 .push_work = __WORK_INITIALIZER(blocking_pool.push_work,
466 push_to_pool),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467};
468
469static struct entropy_store nonblocking_pool = {
470 .poolinfo = &poolinfo_table[1],
471 .name = "nonblocking",
472 .pull = &input_pool,
Thomas Gleixnereece09e2011-07-17 21:25:03 +0200473 .lock = __SPIN_LOCK_UNLOCKED(nonblocking_pool.lock),
Theodore Ts'o6265e162013-10-03 01:08:15 -0400474 .pool = nonblocking_pool_data,
475 .push_work = __WORK_INITIALIZER(nonblocking_pool.push_work,
476 push_to_pool),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477};
478
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400479static __u32 const twist_table[8] = {
480 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
481 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
482
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483/*
Matt Mackalle68e5b62008-04-29 01:03:05 -0700484 * This function adds bytes into the entropy "pool". It does not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485 * update the entropy estimate. The caller should call
Matt Mackalladc782d2008-04-29 01:03:07 -0700486 * credit_entropy_bits if this is appropriate.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 *
488 * The pool is stirred with a primitive polynomial of the appropriate
489 * degree, and then twisted. We twist by three bits at a time because
490 * it's cheap to do so and helps slightly in the expected case where
491 * the entropy is concentrated in the low-order bits.
492 */
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400493static void _mix_pool_bytes(struct entropy_store *r, const void *in,
Theodore Ts'o85608f82014-06-10 23:09:20 -0400494 int nbytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495{
Theodore Ts'o85608f82014-06-10 23:09:20 -0400496 unsigned long i, tap1, tap2, tap3, tap4, tap5;
Matt Mackallfeee7692008-04-29 01:03:02 -0700497 int input_rotate;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498 int wordmask = r->poolinfo->poolwords - 1;
Matt Mackalle68e5b62008-04-29 01:03:05 -0700499 const char *bytes = in;
Matt Mackall6d38b822008-04-29 01:03:03 -0700500 __u32 w;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502 tap1 = r->poolinfo->tap1;
503 tap2 = r->poolinfo->tap2;
504 tap3 = r->poolinfo->tap3;
505 tap4 = r->poolinfo->tap4;
506 tap5 = r->poolinfo->tap5;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507
Theodore Ts'o91fcb532014-06-10 22:46:37 -0400508 input_rotate = r->input_rotate;
509 i = r->add_ptr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510
Matt Mackalle68e5b62008-04-29 01:03:05 -0700511 /* mix one byte at a time to simplify size handling and churn faster */
512 while (nbytes--) {
Theodore Ts'oc59974a2013-09-21 19:42:41 -0400513 w = rol32(*bytes++, input_rotate);
Matt Mackall993ba212008-04-29 01:03:04 -0700514 i = (i - 1) & wordmask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515
516 /* XOR in the various taps */
Matt Mackall993ba212008-04-29 01:03:04 -0700517 w ^= r->pool[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518 w ^= r->pool[(i + tap1) & wordmask];
519 w ^= r->pool[(i + tap2) & wordmask];
520 w ^= r->pool[(i + tap3) & wordmask];
521 w ^= r->pool[(i + tap4) & wordmask];
522 w ^= r->pool[(i + tap5) & wordmask];
Matt Mackall993ba212008-04-29 01:03:04 -0700523
524 /* Mix the result back in with a twist */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525 r->pool[i] = (w >> 3) ^ twist_table[w & 7];
Matt Mackallfeee7692008-04-29 01:03:02 -0700526
527 /*
528 * Normally, we add 7 bits of rotation to the pool.
529 * At the beginning of the pool, add an extra 7 bits
530 * rotation, so that successive passes spread the
531 * input bits across the pool evenly.
532 */
Theodore Ts'oc59974a2013-09-21 19:42:41 -0400533 input_rotate = (input_rotate + (i ? 7 : 14)) & 31;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534 }
535
Theodore Ts'o91fcb532014-06-10 22:46:37 -0400536 r->input_rotate = input_rotate;
537 r->add_ptr = i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538}
539
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400540static void __mix_pool_bytes(struct entropy_store *r, const void *in,
Theodore Ts'o85608f82014-06-10 23:09:20 -0400541 int nbytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542{
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400543 trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_);
Theodore Ts'o85608f82014-06-10 23:09:20 -0400544 _mix_pool_bytes(r, in, nbytes);
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400545}
546
547static void mix_pool_bytes(struct entropy_store *r, const void *in,
Theodore Ts'o85608f82014-06-10 23:09:20 -0400548 int nbytes)
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400549{
Theodore Ts'o902c0982012-07-04 10:38:30 -0400550 unsigned long flags;
551
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400552 trace_mix_pool_bytes(r->name, nbytes, _RET_IP_);
Theodore Ts'o902c0982012-07-04 10:38:30 -0400553 spin_lock_irqsave(&r->lock, flags);
Theodore Ts'o85608f82014-06-10 23:09:20 -0400554 _mix_pool_bytes(r, in, nbytes);
Theodore Ts'o902c0982012-07-04 10:38:30 -0400555 spin_unlock_irqrestore(&r->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556}
557
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400558struct fast_pool {
559 __u32 pool[4];
560 unsigned long last;
Theodore Ts'oee3e00e2014-06-15 16:59:24 -0400561 unsigned short reg_idx;
Theodore Ts'o840f9502014-06-14 03:06:57 -0400562 unsigned char count;
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400563};
564
565/*
566 * This is a fast mixing routine used by the interrupt randomness
567 * collector. It's hardcoded for an 128 bit pool and assumes that any
568 * locks that might be needed are taken by the caller.
569 */
Theodore Ts'o43759d42014-06-14 21:43:13 -0400570static void fast_mix(struct fast_pool *f)
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400571{
Theodore Ts'o43759d42014-06-14 21:43:13 -0400572 __u32 a = f->pool[0], b = f->pool[1];
573 __u32 c = f->pool[2], d = f->pool[3];
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400574
Theodore Ts'o43759d42014-06-14 21:43:13 -0400575 a += b; c += d;
George Spelvin19acc772015-02-07 00:32:06 -0500576 b = rol32(b, 6); d = rol32(d, 27);
Theodore Ts'o43759d42014-06-14 21:43:13 -0400577 d ^= a; b ^= c;
Theodore Ts'o655b2262013-09-22 15:24:02 -0400578
Theodore Ts'o43759d42014-06-14 21:43:13 -0400579 a += b; c += d;
George Spelvin19acc772015-02-07 00:32:06 -0500580 b = rol32(b, 16); d = rol32(d, 14);
Theodore Ts'o43759d42014-06-14 21:43:13 -0400581 d ^= a; b ^= c;
582
583 a += b; c += d;
George Spelvin19acc772015-02-07 00:32:06 -0500584 b = rol32(b, 6); d = rol32(d, 27);
Theodore Ts'o43759d42014-06-14 21:43:13 -0400585 d ^= a; b ^= c;
586
587 a += b; c += d;
George Spelvin19acc772015-02-07 00:32:06 -0500588 b = rol32(b, 16); d = rol32(d, 14);
Theodore Ts'o43759d42014-06-14 21:43:13 -0400589 d ^= a; b ^= c;
590
591 f->pool[0] = a; f->pool[1] = b;
592 f->pool[2] = c; f->pool[3] = d;
Theodore Ts'o655b2262013-09-22 15:24:02 -0400593 f->count++;
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400594}
595
Herbert Xu205a5252015-06-09 18:19:39 +0800596static void process_random_ready_list(void)
597{
598 unsigned long flags;
599 struct random_ready_callback *rdy, *tmp;
600
601 spin_lock_irqsave(&random_ready_list_lock, flags);
602 list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) {
603 struct module *owner = rdy->owner;
604
605 list_del_init(&rdy->list);
606 rdy->func(rdy);
607 module_put(owner);
608 }
609 spin_unlock_irqrestore(&random_ready_list_lock, flags);
610}
611
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612/*
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400613 * Credit (or debit) the entropy store with n bits of entropy.
614 * Use credit_entropy_bits_safe() if the value comes from userspace
615 * or otherwise should be checked for extreme values.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616 */
Matt Mackalladc782d2008-04-29 01:03:07 -0700617static void credit_entropy_bits(struct entropy_store *r, int nbits)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618{
Theodore Ts'o902c0982012-07-04 10:38:30 -0400619 int entropy_count, orig;
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400620 const int pool_size = r->poolinfo->poolfracbits;
621 int nfrac = nbits << ENTROPY_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622
Matt Mackalladc782d2008-04-29 01:03:07 -0700623 if (!nbits)
624 return;
625
Theodore Ts'o902c0982012-07-04 10:38:30 -0400626retry:
627 entropy_count = orig = ACCESS_ONCE(r->entropy_count);
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400628 if (nfrac < 0) {
629 /* Debit */
630 entropy_count += nfrac;
631 } else {
632 /*
633 * Credit: we have to account for the possibility of
634 * overwriting already present entropy. Even in the
635 * ideal case of pure Shannon entropy, new contributions
636 * approach the full value asymptotically:
637 *
638 * entropy <- entropy + (pool_size - entropy) *
639 * (1 - exp(-add_entropy/pool_size))
640 *
641 * For add_entropy <= pool_size/2 then
642 * (1 - exp(-add_entropy/pool_size)) >=
643 * (add_entropy/pool_size)*0.7869...
644 * so we can approximate the exponential with
645 * 3/4*add_entropy/pool_size and still be on the
646 * safe side by adding at most pool_size/2 at a time.
647 *
648 * The use of pool_size-2 in the while statement is to
649 * prevent rounding artifacts from making the loop
650 * arbitrarily long; this limits the loop to log2(pool_size)*2
651 * turns no matter how large nbits is.
652 */
653 int pnfrac = nfrac;
654 const int s = r->poolinfo->poolbitshift + ENTROPY_SHIFT + 2;
655 /* The +2 corresponds to the /4 in the denominator */
656
657 do {
658 unsigned int anfrac = min(pnfrac, pool_size/2);
659 unsigned int add =
660 ((pool_size - entropy_count)*anfrac*3) >> s;
661
662 entropy_count += add;
663 pnfrac -= anfrac;
664 } while (unlikely(entropy_count < pool_size-2 && pnfrac));
665 }
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400666
Hannes Frederic Sowa79a84682014-07-18 17:26:41 -0400667 if (unlikely(entropy_count < 0)) {
Theodore Ts'of80bbd82013-10-03 12:02:37 -0400668 pr_warn("random: negative entropy/overflow: pool %s count %d\n",
669 r->name, entropy_count);
670 WARN_ON(1);
Andrew Morton8b76f462008-09-02 14:36:14 -0700671 entropy_count = 0;
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400672 } else if (entropy_count > pool_size)
673 entropy_count = pool_size;
Theodore Ts'o902c0982012-07-04 10:38:30 -0400674 if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
675 goto retry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676
Theodore Ts'o6265e162013-10-03 01:08:15 -0400677 r->entropy_total += nbits;
Linus Torvalds0891ad82013-11-16 10:19:15 -0800678 if (!r->initialized && r->entropy_total > 128) {
679 r->initialized = 1;
680 r->entropy_total = 0;
681 if (r == &nonblocking_pool) {
682 prandom_reseed_late();
Herbert Xu205a5252015-06-09 18:19:39 +0800683 process_random_ready_list();
Herbert Xu1d9de442015-05-21 16:19:54 +0800684 wake_up_all(&urandom_init_wait);
Linus Torvalds0891ad82013-11-16 10:19:15 -0800685 pr_notice("random: %s pool is initialized\n", r->name);
Hannes Frederic Sowa4af712e2013-11-11 12:20:34 +0100686 }
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400687 }
688
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400689 trace_credit_entropy_bits(r->name, nbits,
690 entropy_count >> ENTROPY_SHIFT,
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400691 r->entropy_total, _RET_IP_);
692
Theodore Ts'o6265e162013-10-03 01:08:15 -0400693 if (r == &input_pool) {
Greg Price7d1b08c2013-12-07 09:49:55 -0500694 int entropy_bits = entropy_count >> ENTROPY_SHIFT;
Theodore Ts'o6265e162013-10-03 01:08:15 -0400695
696 /* should we wake readers? */
Greg Price2132a962013-12-06 21:28:03 -0500697 if (entropy_bits >= random_read_wakeup_bits) {
Theodore Ts'o6265e162013-10-03 01:08:15 -0400698 wake_up_interruptible(&random_read_wait);
699 kill_fasync(&fasync, SIGIO, POLL_IN);
700 }
701 /* If the input pool is getting full, send some
702 * entropy to the two output pools, flipping back and
703 * forth between them, until the output pools are 75%
704 * full.
705 */
Greg Price2132a962013-12-06 21:28:03 -0500706 if (entropy_bits > random_write_wakeup_bits &&
Theodore Ts'o6265e162013-10-03 01:08:15 -0400707 r->initialized &&
Greg Price2132a962013-12-06 21:28:03 -0500708 r->entropy_total >= 2*random_read_wakeup_bits) {
Theodore Ts'o6265e162013-10-03 01:08:15 -0400709 static struct entropy_store *last = &blocking_pool;
710 struct entropy_store *other = &blocking_pool;
711
712 if (last == &blocking_pool)
713 other = &nonblocking_pool;
714 if (other->entropy_count <=
715 3 * other->poolinfo->poolfracbits / 4)
716 last = other;
717 if (last->entropy_count <=
718 3 * last->poolinfo->poolfracbits / 4) {
719 schedule_work(&last->push_work);
720 r->entropy_total = 0;
721 }
722 }
Jeff Dike9a6f70b2008-04-29 01:03:08 -0700723 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724}
725
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400726static void credit_entropy_bits_safe(struct entropy_store *r, int nbits)
727{
728 const int nbits_max = (int)(~0U >> (ENTROPY_SHIFT + 1));
729
730 /* Cap the value to avoid overflows */
731 nbits = min(nbits, nbits_max);
732 nbits = max(nbits, -nbits_max);
733
734 credit_entropy_bits(r, nbits);
735}
736
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737/*********************************************************************
738 *
739 * Entropy input management
740 *
741 *********************************************************************/
742
743/* There is one of these per entropy source */
744struct timer_rand_state {
745 cycles_t last_time;
Matt Mackall90b75ee2008-04-29 01:02:55 -0700746 long last_delta, last_delta2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747 unsigned dont_count_entropy:1;
748};
749
Theodore Ts'o644008d2013-11-03 16:40:53 -0500750#define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, };
751
Linus Torvaldsa2080a62012-07-04 11:16:01 -0400752/*
753 * Add device- or boot-specific data to the input and nonblocking
754 * pools to help initialize them to unique values.
755 *
756 * None of this adds any entropy, it is meant to avoid the
757 * problem of the nonblocking pool having similar initial state
758 * across largely identical devices.
759 */
760void add_device_randomness(const void *buf, unsigned int size)
761{
Theodore Ts'o61875f32013-09-21 13:58:22 -0400762 unsigned long time = random_get_entropy() ^ jiffies;
Theodore Ts'o3ef4cb22013-09-12 14:27:22 -0400763 unsigned long flags;
Linus Torvaldsa2080a62012-07-04 11:16:01 -0400764
Theodore Ts'o59108952013-09-12 14:10:25 -0400765 trace_add_device_randomness(size, _RET_IP_);
Theodore Ts'o3ef4cb22013-09-12 14:27:22 -0400766 spin_lock_irqsave(&input_pool.lock, flags);
Theodore Ts'o85608f82014-06-10 23:09:20 -0400767 _mix_pool_bytes(&input_pool, buf, size);
768 _mix_pool_bytes(&input_pool, &time, sizeof(time));
Theodore Ts'o3ef4cb22013-09-12 14:27:22 -0400769 spin_unlock_irqrestore(&input_pool.lock, flags);
770
771 spin_lock_irqsave(&nonblocking_pool.lock, flags);
Theodore Ts'o85608f82014-06-10 23:09:20 -0400772 _mix_pool_bytes(&nonblocking_pool, buf, size);
773 _mix_pool_bytes(&nonblocking_pool, &time, sizeof(time));
Theodore Ts'o3ef4cb22013-09-12 14:27:22 -0400774 spin_unlock_irqrestore(&nonblocking_pool.lock, flags);
Linus Torvaldsa2080a62012-07-04 11:16:01 -0400775}
776EXPORT_SYMBOL(add_device_randomness);
777
Theodore Ts'o644008d2013-11-03 16:40:53 -0500778static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE;
Yinghai Lu3060d6f2008-08-19 20:50:08 -0700779
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780/*
781 * This function adds entropy to the entropy "pool" by using timing
782 * delays. It uses the timer_rand_state structure to make an estimate
783 * of how many bits of entropy this call has added to the pool.
784 *
785 * The number "num" is also added to the pool - it should somehow describe
786 * the type of event which just happened. This is currently 0-255 for
787 * keyboard scan codes, and 256 upwards for interrupts.
788 *
789 */
790static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
791{
Theodore Ts'o40db23e2013-11-03 00:15:05 -0400792 struct entropy_store *r;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793 struct {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794 long jiffies;
Linus Torvaldscf833d02011-12-22 11:36:22 -0800795 unsigned cycles;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700796 unsigned num;
797 } sample;
798 long delta, delta2, delta3;
799
800 preempt_disable();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801
802 sample.jiffies = jiffies;
Theodore Ts'o61875f32013-09-21 13:58:22 -0400803 sample.cycles = random_get_entropy();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804 sample.num = num;
Theodore Ts'o40db23e2013-11-03 00:15:05 -0400805 r = nonblocking_pool.initialized ? &input_pool : &nonblocking_pool;
Theodore Ts'o85608f82014-06-10 23:09:20 -0400806 mix_pool_bytes(r, &sample, sizeof(sample));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807
808 /*
809 * Calculate number of bits of randomness we probably added.
810 * We take into account the first, second and third-order deltas
811 * in order to make our estimate.
812 */
813
814 if (!state->dont_count_entropy) {
815 delta = sample.jiffies - state->last_time;
816 state->last_time = sample.jiffies;
817
818 delta2 = delta - state->last_delta;
819 state->last_delta = delta;
820
821 delta3 = delta2 - state->last_delta2;
822 state->last_delta2 = delta2;
823
824 if (delta < 0)
825 delta = -delta;
826 if (delta2 < 0)
827 delta2 = -delta2;
828 if (delta3 < 0)
829 delta3 = -delta3;
830 if (delta > delta2)
831 delta = delta2;
832 if (delta > delta3)
833 delta = delta3;
834
835 /*
836 * delta is now minimum absolute delta.
837 * Round down by 1 bit on general principles,
838 * and limit entropy entimate to 12 bits.
839 */
Theodore Ts'o40db23e2013-11-03 00:15:05 -0400840 credit_entropy_bits(r, min_t(int, fls(delta>>1), 11));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842 preempt_enable();
843}
844
Stephen Hemmingerd2515752006-01-11 12:17:38 -0800845void add_input_randomness(unsigned int type, unsigned int code,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700846 unsigned int value)
847{
848 static unsigned char last_value;
849
850 /* ignore autorepeat and the like */
851 if (value == last_value)
852 return;
853
Linus Torvalds1da177e2005-04-16 15:20:36 -0700854 last_value = value;
855 add_timer_randomness(&input_timer_state,
856 (type << 4) ^ code ^ (code >> 4) ^ value);
Theodore Ts'of80bbd82013-10-03 12:02:37 -0400857 trace_add_input_randomness(ENTROPY_BITS(&input_pool));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858}
Dmitry Torokhov80fc9f52006-10-11 01:43:58 -0400859EXPORT_SYMBOL_GPL(add_input_randomness);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700860
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400861static DEFINE_PER_CPU(struct fast_pool, irq_randomness);
862
Theodore Ts'o43759d42014-06-14 21:43:13 -0400863#ifdef ADD_INTERRUPT_BENCH
864static unsigned long avg_cycles, avg_deviation;
865
866#define AVG_SHIFT 8 /* Exponential average factor k=1/256 */
867#define FIXED_1_2 (1 << (AVG_SHIFT-1))
868
869static void add_interrupt_bench(cycles_t start)
870{
871 long delta = random_get_entropy() - start;
872
873 /* Use a weighted moving average */
874 delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT);
875 avg_cycles += delta;
876 /* And average deviation */
877 delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT);
878 avg_deviation += delta;
879}
880#else
881#define add_interrupt_bench(x)
882#endif
883
Theodore Ts'oee3e00e2014-06-15 16:59:24 -0400884static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
885{
886 __u32 *ptr = (__u32 *) regs;
887
888 if (regs == NULL)
889 return 0;
890 if (f->reg_idx >= sizeof(struct pt_regs) / sizeof(__u32))
891 f->reg_idx = 0;
892 return *(ptr + f->reg_idx++);
893}
894
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400895void add_interrupt_randomness(int irq, int irq_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896{
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400897 struct entropy_store *r;
Christoph Lameter1b2a1a72014-08-17 12:30:29 -0500898 struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400899 struct pt_regs *regs = get_irq_regs();
900 unsigned long now = jiffies;
Theodore Ts'o655b2262013-09-22 15:24:02 -0400901 cycles_t cycles = random_get_entropy();
Theodore Ts'o43759d42014-06-14 21:43:13 -0400902 __u32 c_high, j_high;
Theodore Ts'o655b2262013-09-22 15:24:02 -0400903 __u64 ip;
H. Peter Anvin83664a62014-03-17 16:36:28 -0700904 unsigned long seed;
Theodore Ts'o91fcb532014-06-10 22:46:37 -0400905 int credit = 0;
Yinghai Lu3060d6f2008-08-19 20:50:08 -0700906
Theodore Ts'oee3e00e2014-06-15 16:59:24 -0400907 if (cycles == 0)
908 cycles = get_reg(fast_pool, regs);
Theodore Ts'o655b2262013-09-22 15:24:02 -0400909 c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0;
910 j_high = (sizeof(now) > 4) ? now >> 32 : 0;
Theodore Ts'o43759d42014-06-14 21:43:13 -0400911 fast_pool->pool[0] ^= cycles ^ j_high ^ irq;
912 fast_pool->pool[1] ^= now ^ c_high;
Theodore Ts'o655b2262013-09-22 15:24:02 -0400913 ip = regs ? instruction_pointer(regs) : _RET_IP_;
Theodore Ts'o43759d42014-06-14 21:43:13 -0400914 fast_pool->pool[2] ^= ip;
Theodore Ts'oee3e00e2014-06-15 16:59:24 -0400915 fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 :
916 get_reg(fast_pool, regs);
Yinghai Lu3060d6f2008-08-19 20:50:08 -0700917
Theodore Ts'o43759d42014-06-14 21:43:13 -0400918 fast_mix(fast_pool);
Theodore Ts'o43759d42014-06-14 21:43:13 -0400919 add_interrupt_bench(cycles);
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400920
Theodore Ts'oee3e00e2014-06-15 16:59:24 -0400921 if ((fast_pool->count < 64) &&
922 !time_after(now, fast_pool->last + HZ))
923 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400925 r = nonblocking_pool.initialized ? &input_pool : &nonblocking_pool;
Theodore Ts'o840f9502014-06-14 03:06:57 -0400926 if (!spin_trylock(&r->lock))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700927 return;
928
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400929 fast_pool->last = now;
Theodore Ts'o85608f82014-06-10 23:09:20 -0400930 __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool));
H. Peter Anvin83664a62014-03-17 16:36:28 -0700931
932 /*
933 * If we have architectural seed generator, produce a seed and
Theodore Ts'o48d6be92014-07-17 05:27:30 -0400934 * add it to the pool. For the sake of paranoia don't let the
935 * architectural seed generator dominate the input from the
936 * interrupt noise.
H. Peter Anvin83664a62014-03-17 16:36:28 -0700937 */
938 if (arch_get_random_seed_long(&seed)) {
Theodore Ts'o85608f82014-06-10 23:09:20 -0400939 __mix_pool_bytes(r, &seed, sizeof(seed));
Theodore Ts'o48d6be92014-07-17 05:27:30 -0400940 credit = 1;
H. Peter Anvin83664a62014-03-17 16:36:28 -0700941 }
Theodore Ts'o91fcb532014-06-10 22:46:37 -0400942 spin_unlock(&r->lock);
H. Peter Anvin83664a62014-03-17 16:36:28 -0700943
Theodore Ts'oee3e00e2014-06-15 16:59:24 -0400944 fast_pool->count = 0;
Theodore Ts'o840f9502014-06-14 03:06:57 -0400945
Theodore Ts'oee3e00e2014-06-15 16:59:24 -0400946 /* award one bit for the contents of the fast pool */
947 credit_entropy_bits(r, credit + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948}
949
David Howells93614012006-09-30 20:45:40 +0200950#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951void add_disk_randomness(struct gendisk *disk)
952{
953 if (!disk || !disk->random)
954 return;
955 /* first major is 1, so we get >= 0x200 here */
Tejun Heof331c022008-09-03 09:01:48 +0200956 add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
Theodore Ts'of80bbd82013-10-03 12:02:37 -0400957 trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS(&input_pool));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700958}
Christoph Hellwigbdcfa3e2014-04-25 00:36:37 -0700959EXPORT_SYMBOL_GPL(add_disk_randomness);
David Howells93614012006-09-30 20:45:40 +0200960#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961
Linus Torvalds1da177e2005-04-16 15:20:36 -0700962/*********************************************************************
963 *
964 * Entropy extraction routines
965 *
966 *********************************************************************/
967
Matt Mackall90b75ee2008-04-29 01:02:55 -0700968static ssize_t extract_entropy(struct entropy_store *r, void *buf,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969 size_t nbytes, int min, int rsvd);
970
971/*
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300972 * This utility inline function is responsible for transferring entropy
Linus Torvalds1da177e2005-04-16 15:20:36 -0700973 * from the primary pool to the secondary extraction pool. We make
974 * sure we pull enough for a 'catastrophic reseed'.
975 */
Theodore Ts'o6265e162013-10-03 01:08:15 -0400976static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700977static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
978{
Theodore Ts'ocff85032014-06-10 23:18:16 -0400979 if (!r->pull ||
980 r->entropy_count >= (nbytes << (ENTROPY_SHIFT + 3)) ||
981 r->entropy_count > r->poolinfo->poolfracbits)
982 return;
983
Theodore Ts'of5c27422013-09-22 15:14:32 -0400984 if (r->limit == 0 && random_min_urandom_seed) {
985 unsigned long now = jiffies;
986
987 if (time_before(now,
988 r->last_pulled + random_min_urandom_seed * HZ))
989 return;
990 r->last_pulled = now;
991 }
Theodore Ts'ocff85032014-06-10 23:18:16 -0400992
993 _xfer_secondary_pool(r, nbytes);
Theodore Ts'o6265e162013-10-03 01:08:15 -0400994}
Matt Mackall5a021e92007-07-19 11:30:14 -0700995
Theodore Ts'o6265e162013-10-03 01:08:15 -0400996static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
997{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998 __u32 tmp[OUTPUT_POOL_WORDS];
999
Greg Price2132a962013-12-06 21:28:03 -05001000 /* For /dev/random's pool, always leave two wakeups' worth */
1001 int rsvd_bytes = r->limit ? 0 : random_read_wakeup_bits / 4;
Theodore Ts'o6265e162013-10-03 01:08:15 -04001002 int bytes = nbytes;
Matt Mackall5a021e92007-07-19 11:30:14 -07001003
Greg Price2132a962013-12-06 21:28:03 -05001004 /* pull at least as much as a wakeup */
1005 bytes = max_t(int, bytes, random_read_wakeup_bits / 8);
Theodore Ts'o6265e162013-10-03 01:08:15 -04001006 /* but never more than the buffer size */
1007 bytes = min_t(int, bytes, sizeof(tmp));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001008
Theodore Ts'of80bbd82013-10-03 12:02:37 -04001009 trace_xfer_secondary_pool(r->name, bytes * 8, nbytes * 8,
1010 ENTROPY_BITS(r), ENTROPY_BITS(r->pull));
Theodore Ts'o6265e162013-10-03 01:08:15 -04001011 bytes = extract_entropy(r->pull, tmp, bytes,
Greg Price2132a962013-12-06 21:28:03 -05001012 random_read_wakeup_bits / 8, rsvd_bytes);
Theodore Ts'o85608f82014-06-10 23:09:20 -04001013 mix_pool_bytes(r, tmp, bytes);
Theodore Ts'o6265e162013-10-03 01:08:15 -04001014 credit_entropy_bits(r, bytes*8);
1015}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001016
Theodore Ts'o6265e162013-10-03 01:08:15 -04001017/*
1018 * Used as a workqueue function so that when the input pool is getting
1019 * full, we can "spill over" some entropy to the output pools. That
1020 * way the output pools can store some of the excess entropy instead
1021 * of letting it go to waste.
1022 */
1023static void push_to_pool(struct work_struct *work)
1024{
1025 struct entropy_store *r = container_of(work, struct entropy_store,
1026 push_work);
1027 BUG_ON(!r);
Greg Price2132a962013-12-06 21:28:03 -05001028 _xfer_secondary_pool(r, random_read_wakeup_bits/8);
Theodore Ts'o6265e162013-10-03 01:08:15 -04001029 trace_push_to_pool(r->name, r->entropy_count >> ENTROPY_SHIFT,
1030 r->pull->entropy_count >> ENTROPY_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001031}
1032
1033/*
Greg Price19fa5be2013-11-29 15:50:06 -05001034 * This function decides how many bytes to actually take from the
1035 * given pool, and also debits the entropy count accordingly.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001036 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001037static size_t account(struct entropy_store *r, size_t nbytes, int min,
1038 int reserved)
1039{
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001040 int entropy_count, orig;
Hannes Frederic Sowa79a84682014-07-18 17:26:41 -04001041 size_t ibytes, nfrac;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001042
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001043 BUG_ON(r->entropy_count > r->poolinfo->poolfracbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044
1045 /* Can we pull enough? */
Jiri Kosina10b3a322013-05-24 15:55:33 -07001046retry:
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001047 entropy_count = orig = ACCESS_ONCE(r->entropy_count);
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001048 ibytes = nbytes;
Greg Price0fb7a012013-12-05 19:32:19 -05001049 /* If limited, never pull more than available */
Theodore Ts'oe33ba5f2014-06-15 21:04:32 -04001050 if (r->limit) {
1051 int have_bytes = entropy_count >> (ENTROPY_SHIFT + 3);
1052
1053 if ((have_bytes -= reserved) < 0)
1054 have_bytes = 0;
1055 ibytes = min_t(size_t, ibytes, have_bytes);
1056 }
Greg Price0fb7a012013-12-05 19:32:19 -05001057 if (ibytes < min)
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001058 ibytes = 0;
Hannes Frederic Sowa79a84682014-07-18 17:26:41 -04001059
1060 if (unlikely(entropy_count < 0)) {
1061 pr_warn("random: negative entropy count: pool %s count %d\n",
1062 r->name, entropy_count);
1063 WARN_ON(1);
1064 entropy_count = 0;
1065 }
1066 nfrac = ibytes << (ENTROPY_SHIFT + 3);
1067 if ((size_t) entropy_count > nfrac)
1068 entropy_count -= nfrac;
1069 else
Theodore Ts'oe33ba5f2014-06-15 21:04:32 -04001070 entropy_count = 0;
Theodore Ts'of9c6d492014-05-16 21:40:41 -04001071
Greg Price0fb7a012013-12-05 19:32:19 -05001072 if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
1073 goto retry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001074
Theodore Ts'of80bbd82013-10-03 12:02:37 -04001075 trace_debit_entropy(r->name, 8 * ibytes);
Greg Price0fb7a012013-12-05 19:32:19 -05001076 if (ibytes &&
Greg Price2132a962013-12-06 21:28:03 -05001077 (r->entropy_count >> ENTROPY_SHIFT) < random_write_wakeup_bits) {
Theodore Ts'ob9809552013-03-04 11:59:12 -05001078 wake_up_interruptible(&random_write_wait);
1079 kill_fasync(&fasync, SIGIO, POLL_OUT);
1080 }
1081
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001082 return ibytes;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083}
1084
Greg Price19fa5be2013-11-29 15:50:06 -05001085/*
1086 * This function does the actual extraction for extract_entropy and
1087 * extract_entropy_user.
1088 *
1089 * Note: we assume that .poolwords is a multiple of 16 words.
1090 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001091static void extract_buf(struct entropy_store *r, __u8 *out)
1092{
Matt Mackall602b6ae2007-05-29 21:54:27 -05001093 int i;
H. Peter Anvind2e7c962012-07-27 22:26:08 -04001094 union {
1095 __u32 w[5];
Theodore Ts'o85a1f772013-09-21 18:06:02 -04001096 unsigned long l[LONGS(20)];
H. Peter Anvind2e7c962012-07-27 22:26:08 -04001097 } hash;
1098 __u32 workspace[SHA_WORKSPACE_WORDS];
Theodore Ts'o902c0982012-07-04 10:38:30 -04001099 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001100
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101 /*
Greg Pricedfd38752013-11-29 14:58:06 -05001102 * If we have an architectural hardware random number
Theodore Ts'o46884442013-12-17 21:16:39 -05001103 * generator, use it for SHA's initial vector
Theodore Ts'o85a1f772013-09-21 18:06:02 -04001104 */
Theodore Ts'o46884442013-12-17 21:16:39 -05001105 sha_init(hash.w);
Theodore Ts'o85a1f772013-09-21 18:06:02 -04001106 for (i = 0; i < LONGS(20); i++) {
1107 unsigned long v;
1108 if (!arch_get_random_long(&v))
1109 break;
Theodore Ts'o46884442013-12-17 21:16:39 -05001110 hash.l[i] = v;
Theodore Ts'o85a1f772013-09-21 18:06:02 -04001111 }
1112
Theodore Ts'o46884442013-12-17 21:16:39 -05001113 /* Generate a hash across the pool, 16 words (512 bits) at a time */
1114 spin_lock_irqsave(&r->lock, flags);
1115 for (i = 0; i < r->poolinfo->poolwords; i += 16)
1116 sha_transform(hash.w, (__u8 *)(r->pool + i), workspace);
1117
Theodore Ts'o85a1f772013-09-21 18:06:02 -04001118 /*
Matt Mackall1c0ad3d2008-04-29 01:03:00 -07001119 * We mix the hash back into the pool to prevent backtracking
1120 * attacks (where the attacker knows the state of the pool
1121 * plus the current outputs, and attempts to find previous
1122 * ouputs), unless the hash function can be inverted. By
1123 * mixing at least a SHA1 worth of hash data back, we make
1124 * brute-forcing the feedback as hard as brute-forcing the
1125 * hash.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126 */
Theodore Ts'o85608f82014-06-10 23:09:20 -04001127 __mix_pool_bytes(r, hash.w, sizeof(hash.w));
Theodore Ts'o902c0982012-07-04 10:38:30 -04001128 spin_unlock_irqrestore(&r->lock, flags);
Matt Mackall1c0ad3d2008-04-29 01:03:00 -07001129
Daniel Borkmannd4c5efd2014-08-26 23:16:35 -04001130 memzero_explicit(workspace, sizeof(workspace));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001131
1132 /*
Matt Mackall1c0ad3d2008-04-29 01:03:00 -07001133 * In case the hash function has some recognizable output
1134 * pattern, we fold it in half. Thus, we always feed back
1135 * twice as much data as we output.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001136 */
H. Peter Anvind2e7c962012-07-27 22:26:08 -04001137 hash.w[0] ^= hash.w[3];
1138 hash.w[1] ^= hash.w[4];
1139 hash.w[2] ^= rol32(hash.w[2], 16);
1140
H. Peter Anvind2e7c962012-07-27 22:26:08 -04001141 memcpy(out, &hash, EXTRACT_SIZE);
Daniel Borkmannd4c5efd2014-08-26 23:16:35 -04001142 memzero_explicit(&hash, sizeof(hash));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001143}
1144
Greg Price19fa5be2013-11-29 15:50:06 -05001145/*
1146 * This function extracts randomness from the "entropy pool", and
1147 * returns it in a buffer.
1148 *
1149 * The min parameter specifies the minimum amount we can pull before
1150 * failing to avoid races that defeat catastrophic reseeding while the
1151 * reserved parameter indicates how much entropy we must leave in the
1152 * pool after each pull to avoid starving other readers.
1153 */
Matt Mackall90b75ee2008-04-29 01:02:55 -07001154static ssize_t extract_entropy(struct entropy_store *r, void *buf,
Theodore Ts'o902c0982012-07-04 10:38:30 -04001155 size_t nbytes, int min, int reserved)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001156{
1157 ssize_t ret = 0, i;
1158 __u8 tmp[EXTRACT_SIZE];
Jarod Wilson1e7e2e02013-05-24 15:55:31 -07001159 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001160
Jarod Wilsonec8f02da2012-11-06 10:42:42 -05001161 /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
Jarod Wilson1e7e2e02013-05-24 15:55:31 -07001162 if (fips_enabled) {
1163 spin_lock_irqsave(&r->lock, flags);
1164 if (!r->last_data_init) {
Theodore Ts'oc59974a2013-09-21 19:42:41 -04001165 r->last_data_init = 1;
Jarod Wilson1e7e2e02013-05-24 15:55:31 -07001166 spin_unlock_irqrestore(&r->lock, flags);
1167 trace_extract_entropy(r->name, EXTRACT_SIZE,
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001168 ENTROPY_BITS(r), _RET_IP_);
Jarod Wilson1e7e2e02013-05-24 15:55:31 -07001169 xfer_secondary_pool(r, EXTRACT_SIZE);
1170 extract_buf(r, tmp);
1171 spin_lock_irqsave(&r->lock, flags);
1172 memcpy(r->last_data, tmp, EXTRACT_SIZE);
1173 }
1174 spin_unlock_irqrestore(&r->lock, flags);
1175 }
Jarod Wilsonec8f02da2012-11-06 10:42:42 -05001176
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001177 trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001178 xfer_secondary_pool(r, nbytes);
1179 nbytes = account(r, nbytes, min, reserved);
1180
1181 while (nbytes) {
1182 extract_buf(r, tmp);
Neil Horman5b739ef2009-06-18 19:50:21 +08001183
Matt Mackalle954bc92010-05-20 19:55:01 +10001184 if (fips_enabled) {
Neil Horman5b739ef2009-06-18 19:50:21 +08001185 spin_lock_irqsave(&r->lock, flags);
1186 if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
1187 panic("Hardware RNG duplicated output!\n");
1188 memcpy(r->last_data, tmp, EXTRACT_SIZE);
1189 spin_unlock_irqrestore(&r->lock, flags);
1190 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191 i = min_t(int, nbytes, EXTRACT_SIZE);
1192 memcpy(buf, tmp, i);
1193 nbytes -= i;
1194 buf += i;
1195 ret += i;
1196 }
1197
1198 /* Wipe data just returned from memory */
Daniel Borkmannd4c5efd2014-08-26 23:16:35 -04001199 memzero_explicit(tmp, sizeof(tmp));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200
1201 return ret;
1202}
1203
Greg Price19fa5be2013-11-29 15:50:06 -05001204/*
1205 * This function extracts randomness from the "entropy pool", and
1206 * returns it in a userspace buffer.
1207 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001208static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
1209 size_t nbytes)
1210{
1211 ssize_t ret = 0, i;
1212 __u8 tmp[EXTRACT_SIZE];
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001213 int large_request = (nbytes > 256);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001215 trace_extract_entropy_user(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216 xfer_secondary_pool(r, nbytes);
1217 nbytes = account(r, nbytes, 0, 0);
1218
1219 while (nbytes) {
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001220 if (large_request && need_resched()) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001221 if (signal_pending(current)) {
1222 if (ret == 0)
1223 ret = -ERESTARTSYS;
1224 break;
1225 }
1226 schedule();
1227 }
1228
1229 extract_buf(r, tmp);
1230 i = min_t(int, nbytes, EXTRACT_SIZE);
1231 if (copy_to_user(buf, tmp, i)) {
1232 ret = -EFAULT;
1233 break;
1234 }
1235
1236 nbytes -= i;
1237 buf += i;
1238 ret += i;
1239 }
1240
1241 /* Wipe data just returned from memory */
Daniel Borkmannd4c5efd2014-08-26 23:16:35 -04001242 memzero_explicit(tmp, sizeof(tmp));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001243
1244 return ret;
1245}
1246
1247/*
1248 * This function is the exported kernel interface. It returns some
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001249 * number of good random numbers, suitable for key generation, seeding
Greg Price18e9cea2013-11-29 14:59:45 -05001250 * TCP sequence numbers, etc. It does not rely on the hardware random
1251 * number generator. For random bytes direct from the hardware RNG
1252 * (when available), use get_random_bytes_arch().
Linus Torvalds1da177e2005-04-16 15:20:36 -07001253 */
1254void get_random_bytes(void *buf, int nbytes)
1255{
Theodore Ts'o392a5462013-11-03 18:24:08 -05001256#if DEBUG_RANDOM_BOOT > 0
1257 if (unlikely(nonblocking_pool.initialized == 0))
1258 printk(KERN_NOTICE "random: %pF get_random_bytes called "
1259 "with %d bits of entropy available\n",
1260 (void *) _RET_IP_,
1261 nonblocking_pool.entropy_total);
1262#endif
Theodore Ts'o59108952013-09-12 14:10:25 -04001263 trace_get_random_bytes(nbytes, _RET_IP_);
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001264 extract_entropy(&nonblocking_pool, buf, nbytes, 0, 0);
1265}
1266EXPORT_SYMBOL(get_random_bytes);
1267
1268/*
Herbert Xu205a5252015-06-09 18:19:39 +08001269 * Add a callback function that will be invoked when the nonblocking
1270 * pool is initialised.
1271 *
1272 * returns: 0 if callback is successfully added
1273 * -EALREADY if pool is already initialised (callback not called)
1274 * -ENOENT if module for callback is not alive
1275 */
1276int add_random_ready_callback(struct random_ready_callback *rdy)
1277{
1278 struct module *owner;
1279 unsigned long flags;
1280 int err = -EALREADY;
1281
1282 if (likely(nonblocking_pool.initialized))
1283 return err;
1284
1285 owner = rdy->owner;
1286 if (!try_module_get(owner))
1287 return -ENOENT;
1288
1289 spin_lock_irqsave(&random_ready_list_lock, flags);
1290 if (nonblocking_pool.initialized)
1291 goto out;
1292
1293 owner = NULL;
1294
1295 list_add(&rdy->list, &random_ready_list);
1296 err = 0;
1297
1298out:
1299 spin_unlock_irqrestore(&random_ready_list_lock, flags);
1300
1301 module_put(owner);
1302
1303 return err;
1304}
1305EXPORT_SYMBOL(add_random_ready_callback);
1306
1307/*
1308 * Delete a previously registered readiness callback function.
1309 */
1310void del_random_ready_callback(struct random_ready_callback *rdy)
1311{
1312 unsigned long flags;
1313 struct module *owner = NULL;
1314
1315 spin_lock_irqsave(&random_ready_list_lock, flags);
1316 if (!list_empty(&rdy->list)) {
1317 list_del_init(&rdy->list);
1318 owner = rdy->owner;
1319 }
1320 spin_unlock_irqrestore(&random_ready_list_lock, flags);
1321
1322 module_put(owner);
1323}
1324EXPORT_SYMBOL(del_random_ready_callback);
1325
1326/*
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001327 * This function will use the architecture-specific hardware random
1328 * number generator if it is available. The arch-specific hw RNG will
1329 * almost certainly be faster than what we can do in software, but it
1330 * is impossible to verify that it is implemented securely (as
1331 * opposed, to, say, the AES encryption of a sequence number using a
1332 * key known by the NSA). So it's useful if we need the speed, but
1333 * only if we're willing to trust the hardware manufacturer not to
1334 * have put in a back door.
1335 */
1336void get_random_bytes_arch(void *buf, int nbytes)
1337{
H. Peter Anvin63d77172011-07-31 13:54:50 -07001338 char *p = buf;
1339
Theodore Ts'o59108952013-09-12 14:10:25 -04001340 trace_get_random_bytes_arch(nbytes, _RET_IP_);
H. Peter Anvin63d77172011-07-31 13:54:50 -07001341 while (nbytes) {
1342 unsigned long v;
1343 int chunk = min(nbytes, (int)sizeof(unsigned long));
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001344
H. Peter Anvin63d77172011-07-31 13:54:50 -07001345 if (!arch_get_random_long(&v))
1346 break;
1347
Luck, Tonybd29e562011-11-16 10:50:56 -08001348 memcpy(p, &v, chunk);
H. Peter Anvin63d77172011-07-31 13:54:50 -07001349 p += chunk;
1350 nbytes -= chunk;
1351 }
1352
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001353 if (nbytes)
1354 extract_entropy(&nonblocking_pool, p, nbytes, 0, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355}
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001356EXPORT_SYMBOL(get_random_bytes_arch);
1357
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358
1359/*
1360 * init_std_data - initialize pool with system data
1361 *
1362 * @r: pool to initialize
1363 *
1364 * This function clears the pool's entropy count and mixes some system
1365 * data into the pool to prepare it for use. The pool is not cleared
1366 * as that can only decrease the entropy in the pool.
1367 */
1368static void init_std_data(struct entropy_store *r)
1369{
Theodore Ts'o3e88bdf2011-12-22 16:28:01 -05001370 int i;
Theodore Ts'o902c0982012-07-04 10:38:30 -04001371 ktime_t now = ktime_get_real();
1372 unsigned long rv;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001373
Theodore Ts'of5c27422013-09-22 15:14:32 -04001374 r->last_pulled = jiffies;
Theodore Ts'o85608f82014-06-10 23:09:20 -04001375 mix_pool_bytes(r, &now, sizeof(now));
H. Peter Anvin9ed17b72013-09-10 23:16:17 -04001376 for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) {
H. Peter Anvin83664a62014-03-17 16:36:28 -07001377 if (!arch_get_random_seed_long(&rv) &&
1378 !arch_get_random_long(&rv))
Theodore Ts'oae9ecd92013-11-03 07:56:17 -05001379 rv = random_get_entropy();
Theodore Ts'o85608f82014-06-10 23:09:20 -04001380 mix_pool_bytes(r, &rv, sizeof(rv));
Theodore Ts'o3e88bdf2011-12-22 16:28:01 -05001381 }
Theodore Ts'o85608f82014-06-10 23:09:20 -04001382 mix_pool_bytes(r, utsname(), sizeof(*(utsname())));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383}
1384
Tony Luckcbc96b72012-07-23 09:47:57 -07001385/*
1386 * Note that setup_arch() may call add_device_randomness()
1387 * long before we get here. This allows seeding of the pools
1388 * with some platform dependent data very early in the boot
1389 * process. But it limits our options here. We must use
1390 * statically allocated structures that already have all
1391 * initializations complete at compile time. We should also
1392 * take care not to overwrite the precious per platform data
1393 * we were given.
1394 */
Matt Mackall53c3f632008-04-29 01:02:58 -07001395static int rand_initialize(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001396{
1397 init_std_data(&input_pool);
1398 init_std_data(&blocking_pool);
1399 init_std_data(&nonblocking_pool);
1400 return 0;
1401}
Theodore Ts'oae9ecd92013-11-03 07:56:17 -05001402early_initcall(rand_initialize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403
David Howells93614012006-09-30 20:45:40 +02001404#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405void rand_initialize_disk(struct gendisk *disk)
1406{
1407 struct timer_rand_state *state;
1408
1409 /*
Eric Dumazetf8595812007-03-28 14:22:33 -07001410 * If kzalloc returns null, we just won't use that entropy
Linus Torvalds1da177e2005-04-16 15:20:36 -07001411 * source.
1412 */
Eric Dumazetf8595812007-03-28 14:22:33 -07001413 state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
Theodore Ts'o644008d2013-11-03 16:40:53 -05001414 if (state) {
1415 state->last_time = INITIAL_JIFFIES;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416 disk->random = state;
Theodore Ts'o644008d2013-11-03 16:40:53 -05001417 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418}
David Howells93614012006-09-30 20:45:40 +02001419#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001420
1421static ssize_t
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001422_random_read(int nonblock, char __user *buf, size_t nbytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423{
Greg Price12ff3a52013-11-29 15:02:33 -05001424 ssize_t n;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425
1426 if (nbytes == 0)
1427 return 0;
1428
Greg Price12ff3a52013-11-29 15:02:33 -05001429 nbytes = min_t(size_t, nbytes, SEC_XFER_SIZE);
1430 while (1) {
1431 n = extract_entropy_user(&blocking_pool, buf, nbytes);
1432 if (n < 0)
1433 return n;
Theodore Ts'of80bbd82013-10-03 12:02:37 -04001434 trace_random_read(n*8, (nbytes-n)*8,
1435 ENTROPY_BITS(&blocking_pool),
1436 ENTROPY_BITS(&input_pool));
Greg Price12ff3a52013-11-29 15:02:33 -05001437 if (n > 0)
1438 return n;
H. Peter Anvin331c6492014-03-17 16:36:29 -07001439
Greg Price12ff3a52013-11-29 15:02:33 -05001440 /* Pool is (near) empty. Maybe wait and retry. */
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001441 if (nonblock)
Greg Price12ff3a52013-11-29 15:02:33 -05001442 return -EAGAIN;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443
Greg Price12ff3a52013-11-29 15:02:33 -05001444 wait_event_interruptible(random_read_wait,
1445 ENTROPY_BITS(&input_pool) >=
Greg Price2132a962013-12-06 21:28:03 -05001446 random_read_wakeup_bits);
Greg Price12ff3a52013-11-29 15:02:33 -05001447 if (signal_pending(current))
1448 return -ERESTARTSYS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001449 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001450}
1451
1452static ssize_t
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001453random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
1454{
1455 return _random_read(file->f_flags & O_NONBLOCK, buf, nbytes);
1456}
1457
1458static ssize_t
Matt Mackall90b75ee2008-04-29 01:02:55 -07001459urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460{
Theodore Ts'o301f0592013-11-03 06:54:51 -05001461 int ret;
1462
1463 if (unlikely(nonblocking_pool.initialized == 0))
1464 printk_once(KERN_NOTICE "random: %s urandom read "
1465 "with %d bits of entropy available\n",
1466 current->comm, nonblocking_pool.entropy_total);
1467
Hannes Frederic Sowa79a84682014-07-18 17:26:41 -04001468 nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));
Theodore Ts'o301f0592013-11-03 06:54:51 -05001469 ret = extract_entropy_user(&nonblocking_pool, buf, nbytes);
Theodore Ts'of80bbd82013-10-03 12:02:37 -04001470
1471 trace_urandom_read(8 * nbytes, ENTROPY_BITS(&nonblocking_pool),
1472 ENTROPY_BITS(&input_pool));
1473 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001474}
1475
1476static unsigned int
1477random_poll(struct file *file, poll_table * wait)
1478{
1479 unsigned int mask;
1480
1481 poll_wait(file, &random_read_wait, wait);
1482 poll_wait(file, &random_write_wait, wait);
1483 mask = 0;
Greg Price2132a962013-12-06 21:28:03 -05001484 if (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001485 mask |= POLLIN | POLLRDNORM;
Greg Price2132a962013-12-06 21:28:03 -05001486 if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001487 mask |= POLLOUT | POLLWRNORM;
1488 return mask;
1489}
1490
Matt Mackall7f397dc2007-05-29 21:58:10 -05001491static int
1492write_pool(struct entropy_store *r, const char __user *buffer, size_t count)
1493{
1494 size_t bytes;
1495 __u32 buf[16];
1496 const char __user *p = buffer;
1497
1498 while (count > 0) {
1499 bytes = min(count, sizeof(buf));
1500 if (copy_from_user(&buf, p, bytes))
1501 return -EFAULT;
1502
1503 count -= bytes;
1504 p += bytes;
1505
Theodore Ts'o85608f82014-06-10 23:09:20 -04001506 mix_pool_bytes(r, buf, bytes);
Matt Mackall91f3f1e2008-02-06 01:37:20 -08001507 cond_resched();
Matt Mackall7f397dc2007-05-29 21:58:10 -05001508 }
1509
1510 return 0;
1511}
1512
Matt Mackall90b75ee2008-04-29 01:02:55 -07001513static ssize_t random_write(struct file *file, const char __user *buffer,
1514 size_t count, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001515{
Matt Mackall7f397dc2007-05-29 21:58:10 -05001516 size_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001517
Matt Mackall7f397dc2007-05-29 21:58:10 -05001518 ret = write_pool(&blocking_pool, buffer, count);
1519 if (ret)
1520 return ret;
1521 ret = write_pool(&nonblocking_pool, buffer, count);
1522 if (ret)
1523 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001524
Matt Mackall7f397dc2007-05-29 21:58:10 -05001525 return (ssize_t)count;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001526}
1527
Matt Mackall43ae4862008-04-29 01:02:58 -07001528static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001529{
1530 int size, ent_count;
1531 int __user *p = (int __user *)arg;
1532 int retval;
1533
1534 switch (cmd) {
1535 case RNDGETENTCNT:
Matt Mackall43ae4862008-04-29 01:02:58 -07001536 /* inherently racy, no point locking */
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001537 ent_count = ENTROPY_BITS(&input_pool);
1538 if (put_user(ent_count, p))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539 return -EFAULT;
1540 return 0;
1541 case RNDADDTOENTCNT:
1542 if (!capable(CAP_SYS_ADMIN))
1543 return -EPERM;
1544 if (get_user(ent_count, p))
1545 return -EFAULT;
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001546 credit_entropy_bits_safe(&input_pool, ent_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001547 return 0;
1548 case RNDADDENTROPY:
1549 if (!capable(CAP_SYS_ADMIN))
1550 return -EPERM;
1551 if (get_user(ent_count, p++))
1552 return -EFAULT;
1553 if (ent_count < 0)
1554 return -EINVAL;
1555 if (get_user(size, p++))
1556 return -EFAULT;
Matt Mackall7f397dc2007-05-29 21:58:10 -05001557 retval = write_pool(&input_pool, (const char __user *)p,
1558 size);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559 if (retval < 0)
1560 return retval;
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001561 credit_entropy_bits_safe(&input_pool, ent_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001562 return 0;
1563 case RNDZAPENTCNT:
1564 case RNDCLEARPOOL:
Theodore Ts'oae9ecd92013-11-03 07:56:17 -05001565 /*
1566 * Clear the entropy pool counters. We no longer clear
1567 * the entropy pool, as that's silly.
1568 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001569 if (!capable(CAP_SYS_ADMIN))
1570 return -EPERM;
Theodore Ts'oae9ecd92013-11-03 07:56:17 -05001571 input_pool.entropy_count = 0;
1572 nonblocking_pool.entropy_count = 0;
1573 blocking_pool.entropy_count = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574 return 0;
1575 default:
1576 return -EINVAL;
1577 }
1578}
1579
Jeff Dike9a6f70b2008-04-29 01:03:08 -07001580static int random_fasync(int fd, struct file *filp, int on)
1581{
1582 return fasync_helper(fd, filp, on, &fasync);
1583}
1584
Arjan van de Ven2b8693c2007-02-12 00:55:32 -08001585const struct file_operations random_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001586 .read = random_read,
1587 .write = random_write,
1588 .poll = random_poll,
Matt Mackall43ae4862008-04-29 01:02:58 -07001589 .unlocked_ioctl = random_ioctl,
Jeff Dike9a6f70b2008-04-29 01:03:08 -07001590 .fasync = random_fasync,
Arnd Bergmann6038f372010-08-15 18:52:59 +02001591 .llseek = noop_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001592};
1593
Arjan van de Ven2b8693c2007-02-12 00:55:32 -08001594const struct file_operations urandom_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001595 .read = urandom_read,
1596 .write = random_write,
Matt Mackall43ae4862008-04-29 01:02:58 -07001597 .unlocked_ioctl = random_ioctl,
Jeff Dike9a6f70b2008-04-29 01:03:08 -07001598 .fasync = random_fasync,
Arnd Bergmann6038f372010-08-15 18:52:59 +02001599 .llseek = noop_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001600};
1601
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001602SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
1603 unsigned int, flags)
1604{
1605 if (flags & ~(GRND_NONBLOCK|GRND_RANDOM))
1606 return -EINVAL;
1607
1608 if (count > INT_MAX)
1609 count = INT_MAX;
1610
1611 if (flags & GRND_RANDOM)
1612 return _random_read(flags & GRND_NONBLOCK, buf, count);
1613
1614 if (unlikely(nonblocking_pool.initialized == 0)) {
1615 if (flags & GRND_NONBLOCK)
1616 return -EAGAIN;
1617 wait_event_interruptible(urandom_init_wait,
1618 nonblocking_pool.initialized);
1619 if (signal_pending(current))
1620 return -ERESTARTSYS;
1621 }
1622 return urandom_read(NULL, buf, count, NULL);
1623}
1624
Linus Torvalds1da177e2005-04-16 15:20:36 -07001625/********************************************************************
1626 *
1627 * Sysctl interface
1628 *
1629 ********************************************************************/
1630
1631#ifdef CONFIG_SYSCTL
1632
1633#include <linux/sysctl.h>
1634
1635static int min_read_thresh = 8, min_write_thresh;
Greg Price8c2aa332013-12-05 19:19:29 -05001636static int max_read_thresh = OUTPUT_POOL_WORDS * 32;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637static int max_write_thresh = INPUT_POOL_WORDS * 32;
1638static char sysctl_bootid[16];
1639
1640/*
Greg Pricef22052b2013-11-29 14:58:16 -05001641 * This function is used to return both the bootid UUID, and random
Linus Torvalds1da177e2005-04-16 15:20:36 -07001642 * UUID. The difference is in whether table->data is NULL; if it is,
1643 * then a new UUID is generated and returned to the user.
1644 *
Greg Pricef22052b2013-11-29 14:58:16 -05001645 * If the user accesses this via the proc interface, the UUID will be
1646 * returned as an ASCII string in the standard UUID format; if via the
1647 * sysctl system call, as 16 bytes of binary data.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001648 */
Joe Perchesa1514272013-06-13 19:37:35 -07001649static int proc_do_uuid(struct ctl_table *table, int write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001650 void __user *buffer, size_t *lenp, loff_t *ppos)
1651{
Joe Perchesa1514272013-06-13 19:37:35 -07001652 struct ctl_table fake_table;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001653 unsigned char buf[64], tmp_uuid[16], *uuid;
1654
1655 uuid = table->data;
1656 if (!uuid) {
1657 uuid = tmp_uuid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001658 generate_random_uuid(uuid);
Mathieu Desnoyers44e43602012-04-12 12:49:12 -07001659 } else {
1660 static DEFINE_SPINLOCK(bootid_spinlock);
1661
1662 spin_lock(&bootid_spinlock);
1663 if (!uuid[8])
1664 generate_random_uuid(uuid);
1665 spin_unlock(&bootid_spinlock);
1666 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001667
Joe Perches35900772009-12-14 18:01:11 -08001668 sprintf(buf, "%pU", uuid);
1669
Linus Torvalds1da177e2005-04-16 15:20:36 -07001670 fake_table.data = buf;
1671 fake_table.maxlen = sizeof(buf);
1672
Alexey Dobriyan8d65af72009-09-23 15:57:19 -07001673 return proc_dostring(&fake_table, write, buffer, lenp, ppos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001674}
1675
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001676/*
1677 * Return entropy available scaled to integral bits
1678 */
Joe Perches5eb10d92014-06-06 14:37:58 -07001679static int proc_do_entropy(struct ctl_table *table, int write,
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001680 void __user *buffer, size_t *lenp, loff_t *ppos)
1681{
Joe Perches5eb10d92014-06-06 14:37:58 -07001682 struct ctl_table fake_table;
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001683 int entropy_count;
1684
1685 entropy_count = *(int *)table->data >> ENTROPY_SHIFT;
1686
1687 fake_table.data = &entropy_count;
1688 fake_table.maxlen = sizeof(entropy_count);
1689
1690 return proc_dointvec(&fake_table, write, buffer, lenp, ppos);
1691}
1692
Linus Torvalds1da177e2005-04-16 15:20:36 -07001693static int sysctl_poolsize = INPUT_POOL_WORDS * 32;
Joe Perchesa1514272013-06-13 19:37:35 -07001694extern struct ctl_table random_table[];
1695struct ctl_table random_table[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001696 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001697 .procname = "poolsize",
1698 .data = &sysctl_poolsize,
1699 .maxlen = sizeof(int),
1700 .mode = 0444,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001701 .proc_handler = proc_dointvec,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001702 },
1703 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001704 .procname = "entropy_avail",
1705 .maxlen = sizeof(int),
1706 .mode = 0444,
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001707 .proc_handler = proc_do_entropy,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001708 .data = &input_pool.entropy_count,
1709 },
1710 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001711 .procname = "read_wakeup_threshold",
Greg Price2132a962013-12-06 21:28:03 -05001712 .data = &random_read_wakeup_bits,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001713 .maxlen = sizeof(int),
1714 .mode = 0644,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001715 .proc_handler = proc_dointvec_minmax,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716 .extra1 = &min_read_thresh,
1717 .extra2 = &max_read_thresh,
1718 },
1719 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001720 .procname = "write_wakeup_threshold",
Greg Price2132a962013-12-06 21:28:03 -05001721 .data = &random_write_wakeup_bits,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001722 .maxlen = sizeof(int),
1723 .mode = 0644,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001724 .proc_handler = proc_dointvec_minmax,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001725 .extra1 = &min_write_thresh,
1726 .extra2 = &max_write_thresh,
1727 },
1728 {
Theodore Ts'of5c27422013-09-22 15:14:32 -04001729 .procname = "urandom_min_reseed_secs",
1730 .data = &random_min_urandom_seed,
1731 .maxlen = sizeof(int),
1732 .mode = 0644,
1733 .proc_handler = proc_dointvec,
1734 },
1735 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001736 .procname = "boot_id",
1737 .data = &sysctl_bootid,
1738 .maxlen = 16,
1739 .mode = 0444,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001740 .proc_handler = proc_do_uuid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741 },
1742 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001743 .procname = "uuid",
1744 .maxlen = 16,
1745 .mode = 0444,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001746 .proc_handler = proc_do_uuid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001747 },
Theodore Ts'o43759d42014-06-14 21:43:13 -04001748#ifdef ADD_INTERRUPT_BENCH
1749 {
1750 .procname = "add_interrupt_avg_cycles",
1751 .data = &avg_cycles,
1752 .maxlen = sizeof(avg_cycles),
1753 .mode = 0444,
1754 .proc_handler = proc_doulongvec_minmax,
1755 },
1756 {
1757 .procname = "add_interrupt_avg_deviation",
1758 .data = &avg_deviation,
1759 .maxlen = sizeof(avg_deviation),
1760 .mode = 0444,
1761 .proc_handler = proc_doulongvec_minmax,
1762 },
1763#endif
Eric W. Biederman894d2492009-11-05 14:34:02 -08001764 { }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001765};
1766#endif /* CONFIG_SYSCTL */
1767
David S. Miller6e5714e2011-08-03 20:50:44 -07001768static u32 random_int_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001769
Theodore Ts'o47d06e52013-09-10 10:52:35 -04001770int random_int_secret_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771{
David S. Miller6e5714e2011-08-03 20:50:44 -07001772 get_random_bytes(random_int_secret, sizeof(random_int_secret));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001773 return 0;
1774}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001775
1776/*
1777 * Get a random word for internal kernel use only. Similar to urandom but
1778 * with the goal of minimal entropy pool depletion. As a result, the random
1779 * value is not cryptographically secure but for several uses the cost of
1780 * depleting entropy is too high
1781 */
Theodore Ts'o74feec52012-07-06 14:03:18 -04001782static DEFINE_PER_CPU(__u32 [MD5_DIGEST_WORDS], get_random_int_hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001783unsigned int get_random_int(void)
1784{
H. Peter Anvin63d77172011-07-31 13:54:50 -07001785 __u32 *hash;
David S. Miller6e5714e2011-08-03 20:50:44 -07001786 unsigned int ret;
Linus Torvalds8a0a9bd2009-05-05 08:17:43 -07001787
H. Peter Anvin63d77172011-07-31 13:54:50 -07001788 if (arch_get_random_int(&ret))
1789 return ret;
1790
1791 hash = get_cpu_var(get_random_int_hash);
Linus Torvalds8a0a9bd2009-05-05 08:17:43 -07001792
Theodore Ts'o61875f32013-09-21 13:58:22 -04001793 hash[0] += current->pid + jiffies + random_get_entropy();
David S. Miller6e5714e2011-08-03 20:50:44 -07001794 md5_transform(hash, random_int_secret);
1795 ret = hash[0];
Linus Torvalds8a0a9bd2009-05-05 08:17:43 -07001796 put_cpu_var(get_random_int_hash);
1797
1798 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001799}
Andy Shevchenko16c7fa02013-04-30 15:27:30 -07001800EXPORT_SYMBOL(get_random_int);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001801
1802/*
Daniel Cashmanec9ee4a2016-02-26 15:19:34 -08001803 * Same as get_random_int(), but returns unsigned long.
1804 */
1805unsigned long get_random_long(void)
1806{
1807 __u32 *hash;
1808 unsigned long ret;
1809
1810 if (arch_get_random_long(&ret))
1811 return ret;
1812
1813 hash = get_cpu_var(get_random_int_hash);
1814
1815 hash[0] += current->pid + jiffies + random_get_entropy();
1816 md5_transform(hash, random_int_secret);
1817 ret = *(unsigned long *)hash;
1818 put_cpu_var(get_random_int_hash);
1819
1820 return ret;
1821}
1822EXPORT_SYMBOL(get_random_long);
1823
1824/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001825 * randomize_range() returns a start address such that
1826 *
1827 * [...... <range> .....]
1828 * start end
1829 *
1830 * a <range> with size "len" starting at the return value is inside in the
1831 * area defined by [start, end], but is otherwise randomized.
1832 */
1833unsigned long
1834randomize_range(unsigned long start, unsigned long end, unsigned long len)
1835{
1836 unsigned long range = end - len - start;
1837
1838 if (end <= start + len)
1839 return 0;
1840 return PAGE_ALIGN(get_random_int() % range + start);
1841}
Torsten Duwec84dbf62014-06-14 23:38:36 -04001842
1843/* Interface for in-kernel drivers of true hardware RNGs.
1844 * Those devices may produce endless random bits and will be throttled
1845 * when our pool is full.
1846 */
1847void add_hwgenerator_randomness(const char *buffer, size_t count,
1848 size_t entropy)
1849{
1850 struct entropy_store *poolp = &input_pool;
1851
Theodore Ts'o3371f3d2016-06-12 18:11:51 -04001852 if (unlikely(nonblocking_pool.initialized == 0))
1853 poolp = &nonblocking_pool;
1854 else {
1855 /* Suspend writing if we're above the trickle
1856 * threshold. We'll be woken up again once below
1857 * random_write_wakeup_thresh, or when the calling
1858 * thread is about to terminate.
1859 */
1860 wait_event_interruptible(random_write_wait,
1861 kthread_should_stop() ||
Torsten Duwec84dbf62014-06-14 23:38:36 -04001862 ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits);
Theodore Ts'o3371f3d2016-06-12 18:11:51 -04001863 }
Torsten Duwec84dbf62014-06-14 23:38:36 -04001864 mix_pool_bytes(poolp, buffer, count);
1865 credit_entropy_bits(poolp, entropy);
1866}
1867EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);