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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * random.c -- A strong random number generator
3 *
Jason A. Donenfeldb169c132017-06-07 19:45:31 -04004 * Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All
5 * Rights Reserved.
6 *
Matt Mackall9e95ce22005-04-16 15:25:56 -07007 * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005
Linus Torvalds1da177e2005-04-16 15:20:36 -07008 *
9 * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All
10 * rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, and the entire permission notice in its entirety,
17 * including the disclaimer of warranties.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. The name of the author may not be used to endorse or promote
22 * products derived from this software without specific prior
23 * written permission.
24 *
25 * ALTERNATIVELY, this product may be distributed under the terms of
26 * the GNU General Public License, in which case the provisions of the GPL are
27 * required INSTEAD OF the above restrictions. (This clause is
28 * necessary due to a potential bad interaction between the GPL and
29 * the restrictions contained in a BSD-style copyright.)
30 *
31 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
32 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
33 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
34 * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
35 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
36 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
37 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
38 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
39 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
40 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
41 * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
42 * DAMAGE.
43 */
44
45/*
46 * (now, with legal B.S. out of the way.....)
47 *
48 * This routine gathers environmental noise from device drivers, etc.,
49 * and returns good random numbers, suitable for cryptographic use.
50 * Besides the obvious cryptographic uses, these numbers are also good
51 * for seeding TCP sequence numbers, and other places where it is
52 * desirable to have numbers which are not only random, but hard to
53 * predict by an attacker.
54 *
55 * Theory of operation
56 * ===================
57 *
58 * Computers are very predictable devices. Hence it is extremely hard
59 * to produce truly random numbers on a computer --- as opposed to
60 * pseudo-random numbers, which can easily generated by using a
61 * algorithm. Unfortunately, it is very easy for attackers to guess
62 * the sequence of pseudo-random number generators, and for some
63 * applications this is not acceptable. So instead, we must try to
64 * gather "environmental noise" from the computer's environment, which
65 * must be hard for outside attackers to observe, and use that to
66 * generate random numbers. In a Unix environment, this is best done
67 * from inside the kernel.
68 *
69 * Sources of randomness from the environment include inter-keyboard
70 * timings, inter-interrupt timings from some interrupts, and other
71 * events which are both (a) non-deterministic and (b) hard for an
72 * outside observer to measure. Randomness from these sources are
73 * added to an "entropy pool", which is mixed using a CRC-like function.
74 * This is not cryptographically strong, but it is adequate assuming
75 * the randomness is not chosen maliciously, and it is fast enough that
76 * the overhead of doing it on every interrupt is very reasonable.
77 * As random bytes are mixed into the entropy pool, the routines keep
78 * an *estimate* of how many bits of randomness have been stored into
79 * the random number generator's internal state.
80 *
81 * When random bytes are desired, they are obtained by taking the SHA
82 * hash of the contents of the "entropy pool". The SHA hash avoids
83 * exposing the internal state of the entropy pool. It is believed to
84 * be computationally infeasible to derive any useful information
85 * about the input of SHA from its output. Even if it is possible to
86 * analyze SHA in some clever way, as long as the amount of data
87 * returned from the generator is less than the inherent entropy in
88 * the pool, the output data is totally unpredictable. For this
89 * reason, the routine decreases its internal estimate of how many
90 * bits of "true randomness" are contained in the entropy pool as it
91 * outputs random numbers.
92 *
93 * If this estimate goes to zero, the routine can still generate
94 * random numbers; however, an attacker may (at least in theory) be
95 * able to infer the future output of the generator from prior
96 * outputs. This requires successful cryptanalysis of SHA, which is
97 * not believed to be feasible, but there is a remote possibility.
98 * Nonetheless, these numbers should be useful for the vast majority
99 * of purposes.
100 *
101 * Exported interfaces ---- output
102 * ===============================
103 *
104 * There are three exported interfaces; the first is one designed to
105 * be used from within the kernel:
106 *
107 * void get_random_bytes(void *buf, int nbytes);
108 *
109 * This interface will return the requested number of random bytes,
110 * and place it in the requested buffer.
111 *
112 * The two other interfaces are two character devices /dev/random and
113 * /dev/urandom. /dev/random is suitable for use when very high
114 * quality randomness is desired (for example, for key generation or
115 * one-time pads), as it will only return a maximum of the number of
116 * bits of randomness (as estimated by the random number generator)
117 * contained in the entropy pool.
118 *
119 * The /dev/urandom device does not have this limit, and will return
120 * as many bytes as are requested. As more and more random bytes are
121 * requested without giving time for the entropy pool to recharge,
122 * this will result in random numbers that are merely cryptographically
123 * strong. For many applications, however, this is acceptable.
124 *
125 * Exported interfaces ---- input
126 * ==============================
127 *
128 * The current exported interfaces for gathering environmental noise
129 * from the devices are:
130 *
Linus Torvaldsa2080a62012-07-04 11:16:01 -0400131 * void add_device_randomness(const void *buf, unsigned int size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 * void add_input_randomness(unsigned int type, unsigned int code,
133 * unsigned int value);
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400134 * void add_interrupt_randomness(int irq, int irq_flags);
Jarod Wilson442a4ff2011-02-21 21:43:10 +1100135 * void add_disk_randomness(struct gendisk *disk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 *
Linus Torvaldsa2080a62012-07-04 11:16:01 -0400137 * add_device_randomness() is for adding data to the random pool that
138 * is likely to differ between two devices (or possibly even per boot).
139 * This would be things like MAC addresses or serial numbers, or the
140 * read-out of the RTC. This does *not* add any actual entropy to the
141 * pool, but it initializes the pool to different values for devices
142 * that might otherwise be identical and have very little entropy
143 * available to them (particularly common in the embedded world).
144 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145 * add_input_randomness() uses the input layer interrupt timing, as well as
146 * the event type information from the hardware.
147 *
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400148 * add_interrupt_randomness() uses the interrupt timing as random
149 * inputs to the entropy pool. Using the cycle counters and the irq source
150 * as inputs, it feeds the randomness roughly once a second.
Jarod Wilson442a4ff2011-02-21 21:43:10 +1100151 *
152 * add_disk_randomness() uses what amounts to the seek time of block
153 * layer request events, on a per-disk_devt basis, as input to the
154 * entropy pool. Note that high-speed solid state drives with very low
155 * seek times do not make for good sources of entropy, as their seek
156 * times are usually fairly consistent.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157 *
158 * All of these routines try to estimate how many bits of randomness a
159 * particular randomness source. They do this by keeping track of the
160 * first and second order deltas of the event timings.
161 *
162 * Ensuring unpredictability at system startup
163 * ============================================
164 *
165 * When any operating system starts up, it will go through a sequence
166 * of actions that are fairly predictable by an adversary, especially
167 * if the start-up does not involve interaction with a human operator.
168 * This reduces the actual number of bits of unpredictability in the
169 * entropy pool below the value in entropy_count. In order to
170 * counteract this effect, it helps to carry information in the
171 * entropy pool across shut-downs and start-ups. To do this, put the
172 * following lines an appropriate script which is run during the boot
173 * sequence:
174 *
175 * echo "Initializing random number generator..."
176 * random_seed=/var/run/random-seed
177 * # Carry a random seed from start-up to start-up
178 * # Load and then save the whole entropy pool
179 * if [ -f $random_seed ]; then
180 * cat $random_seed >/dev/urandom
181 * else
182 * touch $random_seed
183 * fi
184 * chmod 600 $random_seed
185 * dd if=/dev/urandom of=$random_seed count=1 bs=512
186 *
187 * and the following lines in an appropriate script which is run as
188 * the system is shutdown:
189 *
190 * # Carry a random seed from shut-down to start-up
191 * # Save the whole entropy pool
192 * echo "Saving random seed..."
193 * random_seed=/var/run/random-seed
194 * touch $random_seed
195 * chmod 600 $random_seed
196 * dd if=/dev/urandom of=$random_seed count=1 bs=512
197 *
198 * For example, on most modern systems using the System V init
199 * scripts, such code fragments would be found in
200 * /etc/rc.d/init.d/random. On older Linux systems, the correct script
201 * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0.
202 *
203 * Effectively, these commands cause the contents of the entropy pool
204 * to be saved at shut-down time and reloaded into the entropy pool at
205 * start-up. (The 'dd' in the addition to the bootup script is to
206 * make sure that /etc/random-seed is different for every start-up,
207 * even if the system crashes without executing rc.0.) Even with
208 * complete knowledge of the start-up activities, predicting the state
209 * of the entropy pool requires knowledge of the previous history of
210 * the system.
211 *
212 * Configuring the /dev/random driver under Linux
213 * ==============================================
214 *
215 * The /dev/random driver under Linux uses minor numbers 8 and 9 of
216 * the /dev/mem major number (#1). So if your system does not have
217 * /dev/random and /dev/urandom created already, they can be created
218 * by using the commands:
219 *
220 * mknod /dev/random c 1 8
221 * mknod /dev/urandom c 1 9
222 *
223 * Acknowledgements:
224 * =================
225 *
226 * Ideas for constructing this random number generator were derived
227 * from Pretty Good Privacy's random number generator, and from private
228 * discussions with Phil Karn. Colin Plumb provided a faster random
229 * number generator, which speed up the mixing function of the entropy
230 * pool, taken from PGPfone. Dale Worley has also contributed many
231 * useful ideas and suggestions to improve this driver.
232 *
233 * Any flaws in the design are solely my responsibility, and should
234 * not be attributed to the Phil, Colin, or any of authors of PGP.
235 *
236 * Further background information on this topic may be obtained from
237 * RFC 1750, "Randomness Recommendations for Security", by Donald
238 * Eastlake, Steve Crocker, and Jeff Schiller.
239 */
240
241#include <linux/utsname.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242#include <linux/module.h>
243#include <linux/kernel.h>
244#include <linux/major.h>
245#include <linux/string.h>
246#include <linux/fcntl.h>
247#include <linux/slab.h>
248#include <linux/random.h>
249#include <linux/poll.h>
250#include <linux/init.h>
251#include <linux/fs.h>
252#include <linux/genhd.h>
253#include <linux/interrupt.h>
Andrea Righi27ac7922008-07-23 21:28:13 -0700254#include <linux/mm.h>
Michael Ellermandd0f0cf2016-07-31 00:23:08 +1000255#include <linux/nodemask.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256#include <linux/spinlock.h>
Torsten Duwec84dbf62014-06-14 23:38:36 -0400257#include <linux/kthread.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258#include <linux/percpu.h>
259#include <linux/cryptohash.h>
Neil Horman5b739ef2009-06-18 19:50:21 +0800260#include <linux/fips.h>
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400261#include <linux/ptrace.h>
Theodore Ts'o6265e162013-10-03 01:08:15 -0400262#include <linux/workqueue.h>
Martin Schwidefsky0244ad02013-08-30 09:39:53 +0200263#include <linux/irq.h>
Theodore Ts'o76dbabb2018-04-25 01:12:32 -0400264#include <linux/ratelimit.h>
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -0400265#include <linux/syscalls.h>
266#include <linux/completion.h>
Andy Shevchenko8da4b8c2016-05-20 17:01:00 -0700267#include <linux/uuid.h>
Theodore Ts'oe192be92016-06-12 18:13:36 -0400268#include <crypto/chacha20.h>
Yinghai Lud178a1e2009-01-11 00:35:42 -0800269
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270#include <asm/processor.h>
Linus Torvalds7c0f6ba2016-12-24 11:46:01 -0800271#include <linux/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272#include <asm/irq.h>
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400273#include <asm/irq_regs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274#include <asm/io.h>
275
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400276#define CREATE_TRACE_POINTS
277#include <trace/events/random.h>
278
Theodore Ts'o43759d42014-06-14 21:43:13 -0400279/* #define ADD_INTERRUPT_BENCH */
280
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281/*
282 * Configuration information
283 */
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400284#define INPUT_POOL_SHIFT 12
285#define INPUT_POOL_WORDS (1 << (INPUT_POOL_SHIFT-5))
286#define OUTPUT_POOL_SHIFT 10
287#define OUTPUT_POOL_WORDS (1 << (OUTPUT_POOL_SHIFT-5))
288#define SEC_XFER_SIZE 512
289#define EXTRACT_SIZE 10
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291
H. Peter Anvind2e7c962012-07-27 22:26:08 -0400292#define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long))
293
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294/*
Theodore Ts'o95b709b2013-10-02 21:10:35 -0400295 * To allow fractional bits to be tracked, the entropy_count field is
296 * denominated in units of 1/8th bits.
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400297 *
298 * 2*(ENTROPY_SHIFT + log2(poolbits)) must <= 31, or the multiply in
299 * credit_entropy_bits() needs to be 64 bits wide.
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400300 */
301#define ENTROPY_SHIFT 3
302#define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT)
303
304/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 * The minimum number of bits of entropy before we wake up a read on
306 * /dev/random. Should be enough to do a significant reseed.
307 */
Greg Price2132a962013-12-06 21:28:03 -0500308static int random_read_wakeup_bits = 64;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309
310/*
311 * If the entropy count falls under this number of bits, then we
312 * should wake up processes which are selecting or polling on write
313 * access to /dev/random.
314 */
Greg Price2132a962013-12-06 21:28:03 -0500315static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316
317/*
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400318 * Originally, we used a primitive polynomial of degree .poolwords
319 * over GF(2). The taps for various sizes are defined below. They
320 * were chosen to be evenly spaced except for the last tap, which is 1
321 * to get the twisting happening as fast as possible.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322 *
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400323 * For the purposes of better mixing, we use the CRC-32 polynomial as
324 * well to make a (modified) twisted Generalized Feedback Shift
325 * Register. (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR
326 * generators. ACM Transactions on Modeling and Computer Simulation
327 * 2(3):179-194. Also see M. Matsumoto & Y. Kurita, 1994. Twisted
Greg Pricedfd38752013-11-29 14:58:06 -0500328 * GFSR generators II. ACM Transactions on Modeling and Computer
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400329 * Simulation 4:254-266)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330 *
331 * Thanks to Colin Plumb for suggesting this.
332 *
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400333 * The mixing operation is much less sensitive than the output hash,
334 * where we use SHA-1. All that we want of mixing operation is that
335 * it be a good non-cryptographic hash; i.e. it not produce collisions
336 * when fed "random" data of the sort we expect to see. As long as
337 * the pool state differs for different inputs, we have preserved the
338 * input entropy and done a good job. The fact that an intelligent
339 * attacker can construct inputs that will produce controlled
340 * alterations to the pool's state is not important because we don't
341 * consider such inputs to contribute any randomness. The only
342 * property we need with respect to them is that the attacker can't
343 * increase his/her knowledge of the pool's state. Since all
344 * additions are reversible (knowing the final state and the input,
345 * you can reconstruct the initial state), if an attacker has any
346 * uncertainty about the initial state, he/she can only shuffle that
347 * uncertainty about, but never cause any collisions (which would
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 * decrease the uncertainty).
349 *
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400350 * Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and
351 * Videau in their paper, "The Linux Pseudorandom Number Generator
352 * Revisited" (see: http://eprint.iacr.org/2012/251.pdf). In their
353 * paper, they point out that we are not using a true Twisted GFSR,
354 * since Matsumoto & Kurita used a trinomial feedback polynomial (that
355 * is, with only three taps, instead of the six that we are using).
356 * As a result, the resulting polynomial is neither primitive nor
357 * irreducible, and hence does not have a maximal period over
358 * GF(2**32). They suggest a slight change to the generator
359 * polynomial which improves the resulting TGFSR polynomial to be
360 * irreducible, which we have made here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362static struct poolinfo {
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400363 int poolbitshift, poolwords, poolbytes, poolbits, poolfracbits;
364#define S(x) ilog2(x)+5, (x), (x)*4, (x)*32, (x) << (ENTROPY_SHIFT+5)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365 int tap1, tap2, tap3, tap4, tap5;
366} poolinfo_table[] = {
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400367 /* was: x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 */
368 /* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */
369 { S(128), 104, 76, 51, 25, 1 },
370 /* was: x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 */
371 /* x^32 + x^26 + x^19 + x^14 + x^7 + x + 1 */
372 { S(32), 26, 19, 14, 7, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373#if 0
374 /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400375 { S(2048), 1638, 1231, 819, 411, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376
377 /* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400378 { S(1024), 817, 615, 412, 204, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379
380 /* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400381 { S(1024), 819, 616, 410, 207, 2 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382
383 /* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400384 { S(512), 411, 308, 208, 104, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385
386 /* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400387 { S(512), 409, 307, 206, 102, 2 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 /* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400389 { S(512), 409, 309, 205, 103, 2 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390
391 /* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400392 { S(256), 205, 155, 101, 52, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393
394 /* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400395 { S(128), 103, 78, 51, 27, 2 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396
397 /* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400398 { S(64), 52, 39, 26, 14, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399#endif
400};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401
402/*
403 * Static global variables
404 */
405static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
406static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
Jeff Dike9a6f70b2008-04-29 01:03:08 -0700407static struct fasync_struct *fasync;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408
Herbert Xu205a5252015-06-09 18:19:39 +0800409static DEFINE_SPINLOCK(random_ready_list_lock);
410static LIST_HEAD(random_ready_list);
411
Theodore Ts'oe192be92016-06-12 18:13:36 -0400412struct crng_state {
413 __u32 state[16];
414 unsigned long init_time;
415 spinlock_t lock;
416};
417
418struct crng_state primary_crng = {
419 .lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock),
420};
421
422/*
423 * crng_init = 0 --> Uninitialized
424 * 1 --> Initialized
425 * 2 --> Initialized from input_pool
426 *
427 * crng_init is protected by primary_crng->lock, and only increases
428 * its value (from 0->1->2).
429 */
430static int crng_init = 0;
Theodore Ts'o6e513bc2018-04-11 13:27:52 -0400431#define crng_ready() (likely(crng_init > 1))
Theodore Ts'oe192be92016-06-12 18:13:36 -0400432static int crng_init_cnt = 0;
Theodore Ts'o90936d92018-04-11 16:32:17 -0400433static unsigned long crng_global_init_time = 0;
Theodore Ts'oe192be92016-06-12 18:13:36 -0400434#define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE)
Theodore Ts'o1e7f5832016-05-02 02:04:41 -0400435static void _extract_crng(struct crng_state *crng,
436 __u8 out[CHACHA20_BLOCK_SIZE]);
Theodore Ts'oc92e0402016-05-04 13:29:18 -0400437static void _crng_backtrack_protect(struct crng_state *crng,
438 __u8 tmp[CHACHA20_BLOCK_SIZE], int used);
Theodore Ts'oe192be92016-06-12 18:13:36 -0400439static void process_random_ready_list(void);
Theodore Ts'oeecabf52017-06-08 04:16:59 -0400440static void _get_random_bytes(void *buf, int nbytes);
Theodore Ts'oe192be92016-06-12 18:13:36 -0400441
Theodore Ts'o76dbabb2018-04-25 01:12:32 -0400442static struct ratelimit_state unseeded_warning =
443 RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3);
444static struct ratelimit_state urandom_warning =
445 RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3);
446
447static int ratelimit_disable __read_mostly;
448
449module_param_named(ratelimit_disable, ratelimit_disable, int, 0644);
450MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression");
451
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452/**********************************************************************
453 *
454 * OS independent entropy store. Here are the functions which handle
455 * storing entropy in an entropy pool.
456 *
457 **********************************************************************/
458
459struct entropy_store;
460struct entropy_store {
Matt Mackall43358202008-04-29 01:03:01 -0700461 /* read-only data: */
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400462 const struct poolinfo *poolinfo;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 __u32 *pool;
464 const char *name;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465 struct entropy_store *pull;
Theodore Ts'o6265e162013-10-03 01:08:15 -0400466 struct work_struct push_work;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467
468 /* read-write data: */
Theodore Ts'of5c27422013-09-22 15:14:32 -0400469 unsigned long last_pulled;
Matt Mackall43358202008-04-29 01:03:01 -0700470 spinlock_t lock;
Theodore Ts'oc59974a2013-09-21 19:42:41 -0400471 unsigned short add_ptr;
472 unsigned short input_rotate;
Matt Mackallcda796a2009-01-06 14:42:55 -0800473 int entropy_count;
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400474 int entropy_total;
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400475 unsigned int initialized:1;
Theodore Ts'oc59974a2013-09-21 19:42:41 -0400476 unsigned int last_data_init:1;
Matt Mackalle954bc92010-05-20 19:55:01 +1000477 __u8 last_data[EXTRACT_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478};
479
Theodore Ts'oe192be92016-06-12 18:13:36 -0400480static ssize_t extract_entropy(struct entropy_store *r, void *buf,
481 size_t nbytes, int min, int rsvd);
482static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
483 size_t nbytes, int fips);
484
485static void crng_reseed(struct crng_state *crng, struct entropy_store *r);
Theodore Ts'o6265e162013-10-03 01:08:15 -0400486static void push_to_pool(struct work_struct *work);
Emese Revfy0766f782016-06-20 20:42:34 +0200487static __u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy;
488static __u32 blocking_pool_data[OUTPUT_POOL_WORDS] __latent_entropy;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489
490static struct entropy_store input_pool = {
491 .poolinfo = &poolinfo_table[0],
492 .name = "input",
Thomas Gleixnereece09e2011-07-17 21:25:03 +0200493 .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494 .pool = input_pool_data
495};
496
497static struct entropy_store blocking_pool = {
498 .poolinfo = &poolinfo_table[1],
499 .name = "blocking",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500 .pull = &input_pool,
Thomas Gleixnereece09e2011-07-17 21:25:03 +0200501 .lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock),
Theodore Ts'o6265e162013-10-03 01:08:15 -0400502 .pool = blocking_pool_data,
503 .push_work = __WORK_INITIALIZER(blocking_pool.push_work,
504 push_to_pool),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700505};
506
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400507static __u32 const twist_table[8] = {
508 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
509 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
510
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511/*
Matt Mackalle68e5b62008-04-29 01:03:05 -0700512 * This function adds bytes into the entropy "pool". It does not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 * update the entropy estimate. The caller should call
Matt Mackalladc782d2008-04-29 01:03:07 -0700514 * credit_entropy_bits if this is appropriate.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 *
516 * The pool is stirred with a primitive polynomial of the appropriate
517 * degree, and then twisted. We twist by three bits at a time because
518 * it's cheap to do so and helps slightly in the expected case where
519 * the entropy is concentrated in the low-order bits.
520 */
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400521static void _mix_pool_bytes(struct entropy_store *r, const void *in,
Theodore Ts'o85608f82014-06-10 23:09:20 -0400522 int nbytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523{
Theodore Ts'o85608f82014-06-10 23:09:20 -0400524 unsigned long i, tap1, tap2, tap3, tap4, tap5;
Matt Mackallfeee7692008-04-29 01:03:02 -0700525 int input_rotate;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 int wordmask = r->poolinfo->poolwords - 1;
Matt Mackalle68e5b62008-04-29 01:03:05 -0700527 const char *bytes = in;
Matt Mackall6d38b822008-04-29 01:03:03 -0700528 __u32 w;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530 tap1 = r->poolinfo->tap1;
531 tap2 = r->poolinfo->tap2;
532 tap3 = r->poolinfo->tap3;
533 tap4 = r->poolinfo->tap4;
534 tap5 = r->poolinfo->tap5;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535
Theodore Ts'o91fcb532014-06-10 22:46:37 -0400536 input_rotate = r->input_rotate;
537 i = r->add_ptr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538
Matt Mackalle68e5b62008-04-29 01:03:05 -0700539 /* mix one byte at a time to simplify size handling and churn faster */
540 while (nbytes--) {
Theodore Ts'oc59974a2013-09-21 19:42:41 -0400541 w = rol32(*bytes++, input_rotate);
Matt Mackall993ba212008-04-29 01:03:04 -0700542 i = (i - 1) & wordmask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543
544 /* XOR in the various taps */
Matt Mackall993ba212008-04-29 01:03:04 -0700545 w ^= r->pool[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546 w ^= r->pool[(i + tap1) & wordmask];
547 w ^= r->pool[(i + tap2) & wordmask];
548 w ^= r->pool[(i + tap3) & wordmask];
549 w ^= r->pool[(i + tap4) & wordmask];
550 w ^= r->pool[(i + tap5) & wordmask];
Matt Mackall993ba212008-04-29 01:03:04 -0700551
552 /* Mix the result back in with a twist */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 r->pool[i] = (w >> 3) ^ twist_table[w & 7];
Matt Mackallfeee7692008-04-29 01:03:02 -0700554
555 /*
556 * Normally, we add 7 bits of rotation to the pool.
557 * At the beginning of the pool, add an extra 7 bits
558 * rotation, so that successive passes spread the
559 * input bits across the pool evenly.
560 */
Theodore Ts'oc59974a2013-09-21 19:42:41 -0400561 input_rotate = (input_rotate + (i ? 7 : 14)) & 31;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562 }
563
Theodore Ts'o91fcb532014-06-10 22:46:37 -0400564 r->input_rotate = input_rotate;
565 r->add_ptr = i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566}
567
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400568static void __mix_pool_bytes(struct entropy_store *r, const void *in,
Theodore Ts'o85608f82014-06-10 23:09:20 -0400569 int nbytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570{
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400571 trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_);
Theodore Ts'o85608f82014-06-10 23:09:20 -0400572 _mix_pool_bytes(r, in, nbytes);
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400573}
574
575static void mix_pool_bytes(struct entropy_store *r, const void *in,
Theodore Ts'o85608f82014-06-10 23:09:20 -0400576 int nbytes)
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400577{
Theodore Ts'o902c0982012-07-04 10:38:30 -0400578 unsigned long flags;
579
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400580 trace_mix_pool_bytes(r->name, nbytes, _RET_IP_);
Theodore Ts'o902c0982012-07-04 10:38:30 -0400581 spin_lock_irqsave(&r->lock, flags);
Theodore Ts'o85608f82014-06-10 23:09:20 -0400582 _mix_pool_bytes(r, in, nbytes);
Theodore Ts'o902c0982012-07-04 10:38:30 -0400583 spin_unlock_irqrestore(&r->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584}
585
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400586struct fast_pool {
587 __u32 pool[4];
588 unsigned long last;
Theodore Ts'oee3e00e2014-06-15 16:59:24 -0400589 unsigned short reg_idx;
Theodore Ts'o840f9502014-06-14 03:06:57 -0400590 unsigned char count;
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400591};
592
593/*
594 * This is a fast mixing routine used by the interrupt randomness
595 * collector. It's hardcoded for an 128 bit pool and assumes that any
596 * locks that might be needed are taken by the caller.
597 */
Theodore Ts'o43759d42014-06-14 21:43:13 -0400598static void fast_mix(struct fast_pool *f)
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400599{
Theodore Ts'o43759d42014-06-14 21:43:13 -0400600 __u32 a = f->pool[0], b = f->pool[1];
601 __u32 c = f->pool[2], d = f->pool[3];
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400602
Theodore Ts'o43759d42014-06-14 21:43:13 -0400603 a += b; c += d;
George Spelvin19acc772015-02-07 00:32:06 -0500604 b = rol32(b, 6); d = rol32(d, 27);
Theodore Ts'o43759d42014-06-14 21:43:13 -0400605 d ^= a; b ^= c;
Theodore Ts'o655b2262013-09-22 15:24:02 -0400606
Theodore Ts'o43759d42014-06-14 21:43:13 -0400607 a += b; c += d;
George Spelvin19acc772015-02-07 00:32:06 -0500608 b = rol32(b, 16); d = rol32(d, 14);
Theodore Ts'o43759d42014-06-14 21:43:13 -0400609 d ^= a; b ^= c;
610
611 a += b; c += d;
George Spelvin19acc772015-02-07 00:32:06 -0500612 b = rol32(b, 6); d = rol32(d, 27);
Theodore Ts'o43759d42014-06-14 21:43:13 -0400613 d ^= a; b ^= c;
614
615 a += b; c += d;
George Spelvin19acc772015-02-07 00:32:06 -0500616 b = rol32(b, 16); d = rol32(d, 14);
Theodore Ts'o43759d42014-06-14 21:43:13 -0400617 d ^= a; b ^= c;
618
619 f->pool[0] = a; f->pool[1] = b;
620 f->pool[2] = c; f->pool[3] = d;
Theodore Ts'o655b2262013-09-22 15:24:02 -0400621 f->count++;
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400622}
623
Herbert Xu205a5252015-06-09 18:19:39 +0800624static void process_random_ready_list(void)
625{
626 unsigned long flags;
627 struct random_ready_callback *rdy, *tmp;
628
629 spin_lock_irqsave(&random_ready_list_lock, flags);
630 list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) {
631 struct module *owner = rdy->owner;
632
633 list_del_init(&rdy->list);
634 rdy->func(rdy);
635 module_put(owner);
636 }
637 spin_unlock_irqrestore(&random_ready_list_lock, flags);
638}
639
Linus Torvalds1da177e2005-04-16 15:20:36 -0700640/*
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400641 * Credit (or debit) the entropy store with n bits of entropy.
642 * Use credit_entropy_bits_safe() if the value comes from userspace
643 * or otherwise should be checked for extreme values.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644 */
Matt Mackalladc782d2008-04-29 01:03:07 -0700645static void credit_entropy_bits(struct entropy_store *r, int nbits)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700646{
Theodore Ts'o902c0982012-07-04 10:38:30 -0400647 int entropy_count, orig;
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400648 const int pool_size = r->poolinfo->poolfracbits;
649 int nfrac = nbits << ENTROPY_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650
Matt Mackalladc782d2008-04-29 01:03:07 -0700651 if (!nbits)
652 return;
653
Theodore Ts'o902c0982012-07-04 10:38:30 -0400654retry:
655 entropy_count = orig = ACCESS_ONCE(r->entropy_count);
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400656 if (nfrac < 0) {
657 /* Debit */
658 entropy_count += nfrac;
659 } else {
660 /*
661 * Credit: we have to account for the possibility of
662 * overwriting already present entropy. Even in the
663 * ideal case of pure Shannon entropy, new contributions
664 * approach the full value asymptotically:
665 *
666 * entropy <- entropy + (pool_size - entropy) *
667 * (1 - exp(-add_entropy/pool_size))
668 *
669 * For add_entropy <= pool_size/2 then
670 * (1 - exp(-add_entropy/pool_size)) >=
671 * (add_entropy/pool_size)*0.7869...
672 * so we can approximate the exponential with
673 * 3/4*add_entropy/pool_size and still be on the
674 * safe side by adding at most pool_size/2 at a time.
675 *
676 * The use of pool_size-2 in the while statement is to
677 * prevent rounding artifacts from making the loop
678 * arbitrarily long; this limits the loop to log2(pool_size)*2
679 * turns no matter how large nbits is.
680 */
681 int pnfrac = nfrac;
682 const int s = r->poolinfo->poolbitshift + ENTROPY_SHIFT + 2;
683 /* The +2 corresponds to the /4 in the denominator */
684
685 do {
686 unsigned int anfrac = min(pnfrac, pool_size/2);
687 unsigned int add =
688 ((pool_size - entropy_count)*anfrac*3) >> s;
689
690 entropy_count += add;
691 pnfrac -= anfrac;
692 } while (unlikely(entropy_count < pool_size-2 && pnfrac));
693 }
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400694
Hannes Frederic Sowa79a84682014-07-18 17:26:41 -0400695 if (unlikely(entropy_count < 0)) {
Theodore Ts'of80bbd82013-10-03 12:02:37 -0400696 pr_warn("random: negative entropy/overflow: pool %s count %d\n",
697 r->name, entropy_count);
698 WARN_ON(1);
Andrew Morton8b76f462008-09-02 14:36:14 -0700699 entropy_count = 0;
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400700 } else if (entropy_count > pool_size)
701 entropy_count = pool_size;
Theodore Ts'o902c0982012-07-04 10:38:30 -0400702 if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
703 goto retry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704
Theodore Ts'o6265e162013-10-03 01:08:15 -0400705 r->entropy_total += nbits;
Linus Torvalds0891ad82013-11-16 10:19:15 -0800706 if (!r->initialized && r->entropy_total > 128) {
707 r->initialized = 1;
708 r->entropy_total = 0;
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400709 }
710
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400711 trace_credit_entropy_bits(r->name, nbits,
712 entropy_count >> ENTROPY_SHIFT,
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400713 r->entropy_total, _RET_IP_);
714
Theodore Ts'o6265e162013-10-03 01:08:15 -0400715 if (r == &input_pool) {
Greg Price7d1b08c2013-12-07 09:49:55 -0500716 int entropy_bits = entropy_count >> ENTROPY_SHIFT;
Theodore Ts'o6265e162013-10-03 01:08:15 -0400717
Theodore Ts'oe192be92016-06-12 18:13:36 -0400718 if (crng_init < 2 && entropy_bits >= 128) {
719 crng_reseed(&primary_crng, r);
720 entropy_bits = r->entropy_count >> ENTROPY_SHIFT;
721 }
722
Theodore Ts'o6265e162013-10-03 01:08:15 -0400723 /* should we wake readers? */
Greg Price2132a962013-12-06 21:28:03 -0500724 if (entropy_bits >= random_read_wakeup_bits) {
Theodore Ts'o6265e162013-10-03 01:08:15 -0400725 wake_up_interruptible(&random_read_wait);
726 kill_fasync(&fasync, SIGIO, POLL_IN);
727 }
728 /* If the input pool is getting full, send some
Theodore Ts'oe192be92016-06-12 18:13:36 -0400729 * entropy to the blocking pool until it is 75% full.
Theodore Ts'o6265e162013-10-03 01:08:15 -0400730 */
Greg Price2132a962013-12-06 21:28:03 -0500731 if (entropy_bits > random_write_wakeup_bits &&
Theodore Ts'o6265e162013-10-03 01:08:15 -0400732 r->initialized &&
Greg Price2132a962013-12-06 21:28:03 -0500733 r->entropy_total >= 2*random_read_wakeup_bits) {
Theodore Ts'o6265e162013-10-03 01:08:15 -0400734 struct entropy_store *other = &blocking_pool;
735
Theodore Ts'o6265e162013-10-03 01:08:15 -0400736 if (other->entropy_count <=
Theodore Ts'oe192be92016-06-12 18:13:36 -0400737 3 * other->poolinfo->poolfracbits / 4) {
738 schedule_work(&other->push_work);
Theodore Ts'o6265e162013-10-03 01:08:15 -0400739 r->entropy_total = 0;
740 }
741 }
Jeff Dike9a6f70b2008-04-29 01:03:08 -0700742 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743}
744
Theodore Ts'o86a574d2016-07-03 17:01:26 -0400745static int credit_entropy_bits_safe(struct entropy_store *r, int nbits)
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400746{
Theodore Ts'ob0afd9d2017-02-25 18:21:33 -0400747 const int nbits_max = r->poolinfo->poolwords * 32;
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400748
Theodore Ts'o86a574d2016-07-03 17:01:26 -0400749 if (nbits < 0)
750 return -EINVAL;
751
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400752 /* Cap the value to avoid overflows */
753 nbits = min(nbits, nbits_max);
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400754
755 credit_entropy_bits(r, nbits);
Theodore Ts'o86a574d2016-07-03 17:01:26 -0400756 return 0;
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400757}
758
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759/*********************************************************************
760 *
Theodore Ts'oe192be92016-06-12 18:13:36 -0400761 * CRNG using CHACHA20
762 *
763 *********************************************************************/
764
765#define CRNG_RESEED_INTERVAL (300*HZ)
766
767static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
768
Theodore Ts'o1e7f5832016-05-02 02:04:41 -0400769#ifdef CONFIG_NUMA
770/*
771 * Hack to deal with crazy userspace progams when they are all trying
772 * to access /dev/urandom in parallel. The programs are almost
773 * certainly doing something terribly wrong, but we'll work around
774 * their brain damage.
775 */
776static struct crng_state **crng_node_pool __read_mostly;
777#endif
778
Jason A. Donenfeldb169c132017-06-07 19:45:31 -0400779static void invalidate_batched_entropy(void);
780
Theodore Ts'oe192be92016-06-12 18:13:36 -0400781static void crng_initialize(struct crng_state *crng)
782{
783 int i;
784 unsigned long rv;
785
786 memcpy(&crng->state[0], "expand 32-byte k", 16);
787 if (crng == &primary_crng)
788 _extract_entropy(&input_pool, &crng->state[4],
789 sizeof(__u32) * 12, 0);
790 else
Theodore Ts'oeecabf52017-06-08 04:16:59 -0400791 _get_random_bytes(&crng->state[4], sizeof(__u32) * 12);
Theodore Ts'oe192be92016-06-12 18:13:36 -0400792 for (i = 4; i < 16; i++) {
793 if (!arch_get_random_seed_long(&rv) &&
794 !arch_get_random_long(&rv))
795 rv = random_get_entropy();
796 crng->state[i] ^= rv;
797 }
798 crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
799}
800
Theodore Ts'o812b51a2018-04-11 15:23:56 -0400801#ifdef CONFIG_NUMA
Theodore Ts'offc5b502018-04-23 18:51:28 -0400802static void do_numa_crng_init(struct work_struct *work)
Theodore Ts'o812b51a2018-04-11 15:23:56 -0400803{
804 int i;
805 struct crng_state *crng;
806 struct crng_state **pool;
807
808 pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL);
809 for_each_online_node(i) {
810 crng = kmalloc_node(sizeof(struct crng_state),
811 GFP_KERNEL | __GFP_NOFAIL, i);
812 spin_lock_init(&crng->lock);
813 crng_initialize(crng);
814 pool[i] = crng;
815 }
816 mb();
817 if (cmpxchg(&crng_node_pool, NULL, pool)) {
818 for_each_node(i)
819 kfree(pool[i]);
820 kfree(pool);
821 }
822}
Theodore Ts'offc5b502018-04-23 18:51:28 -0400823
824static DECLARE_WORK(numa_crng_init_work, do_numa_crng_init);
825
826static void numa_crng_init(void)
827{
828 schedule_work(&numa_crng_init_work);
829}
Theodore Ts'o812b51a2018-04-11 15:23:56 -0400830#else
831static void numa_crng_init(void) {}
832#endif
833
Theodore Ts'o7b6b1f32018-04-11 14:58:27 -0400834/*
835 * crng_fast_load() can be called by code in the interrupt service
836 * path. So we can't afford to dilly-dally.
837 */
Theodore Ts'oe192be92016-06-12 18:13:36 -0400838static int crng_fast_load(const char *cp, size_t len)
839{
840 unsigned long flags;
841 char *p;
842
843 if (!spin_trylock_irqsave(&primary_crng.lock, flags))
844 return 0;
Theodore Ts'o6e513bc2018-04-11 13:27:52 -0400845 if (crng_init != 0) {
Theodore Ts'oe192be92016-06-12 18:13:36 -0400846 spin_unlock_irqrestore(&primary_crng.lock, flags);
847 return 0;
848 }
849 p = (unsigned char *) &primary_crng.state[4];
850 while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) {
851 p[crng_init_cnt % CHACHA20_KEY_SIZE] ^= *cp;
852 cp++; crng_init_cnt++; len--;
853 }
Jason A. Donenfeld4a072c72017-06-15 00:45:26 +0200854 spin_unlock_irqrestore(&primary_crng.lock, flags);
Theodore Ts'oe192be92016-06-12 18:13:36 -0400855 if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
Jason A. Donenfeldb169c132017-06-07 19:45:31 -0400856 invalidate_batched_entropy();
Theodore Ts'oe192be92016-06-12 18:13:36 -0400857 crng_init = 1;
858 wake_up_interruptible(&crng_init_wait);
859 pr_notice("random: fast init done\n");
860 }
Theodore Ts'oe192be92016-06-12 18:13:36 -0400861 return 1;
862}
863
Theodore Ts'o7b6b1f32018-04-11 14:58:27 -0400864/*
865 * crng_slow_load() is called by add_device_randomness, which has two
866 * attributes. (1) We can't trust the buffer passed to it is
867 * guaranteed to be unpredictable (so it might not have any entropy at
868 * all), and (2) it doesn't have the performance constraints of
869 * crng_fast_load().
870 *
871 * So we do something more comprehensive which is guaranteed to touch
872 * all of the primary_crng's state, and which uses a LFSR with a
873 * period of 255 as part of the mixing algorithm. Finally, we do
874 * *not* advance crng_init_cnt since buffer we may get may be something
875 * like a fixed DMI table (for example), which might very well be
876 * unique to the machine, but is otherwise unvarying.
877 */
878static int crng_slow_load(const char *cp, size_t len)
879{
880 unsigned long flags;
881 static unsigned char lfsr = 1;
882 unsigned char tmp;
883 unsigned i, max = CHACHA20_KEY_SIZE;
884 const char * src_buf = cp;
885 char * dest_buf = (char *) &primary_crng.state[4];
886
887 if (!spin_trylock_irqsave(&primary_crng.lock, flags))
888 return 0;
889 if (crng_init != 0) {
890 spin_unlock_irqrestore(&primary_crng.lock, flags);
891 return 0;
892 }
893 if (len > max)
894 max = len;
895
896 for (i = 0; i < max ; i++) {
897 tmp = lfsr;
898 lfsr >>= 1;
899 if (tmp & 1)
900 lfsr ^= 0xE1;
901 tmp = dest_buf[i % CHACHA20_KEY_SIZE];
902 dest_buf[i % CHACHA20_KEY_SIZE] ^= src_buf[i % len] ^ lfsr;
903 lfsr += (tmp << 3) | (tmp >> 5);
904 }
905 spin_unlock_irqrestore(&primary_crng.lock, flags);
906 return 1;
907}
908
Theodore Ts'oe192be92016-06-12 18:13:36 -0400909static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
910{
911 unsigned long flags;
912 int i, num;
913 union {
914 __u8 block[CHACHA20_BLOCK_SIZE];
915 __u32 key[8];
916 } buf;
917
918 if (r) {
919 num = extract_entropy(r, &buf, 32, 16, 0);
920 if (num == 0)
921 return;
Theodore Ts'oc92e0402016-05-04 13:29:18 -0400922 } else {
Theodore Ts'o1e7f5832016-05-02 02:04:41 -0400923 _extract_crng(&primary_crng, buf.block);
Theodore Ts'oc92e0402016-05-04 13:29:18 -0400924 _crng_backtrack_protect(&primary_crng, buf.block,
925 CHACHA20_KEY_SIZE);
926 }
Theodore Ts'od152fcc2018-04-12 00:50:45 -0400927 spin_lock_irqsave(&crng->lock, flags);
Theodore Ts'oe192be92016-06-12 18:13:36 -0400928 for (i = 0; i < 8; i++) {
929 unsigned long rv;
930 if (!arch_get_random_seed_long(&rv) &&
931 !arch_get_random_long(&rv))
932 rv = random_get_entropy();
933 crng->state[i+4] ^= buf.key[i] ^ rv;
934 }
935 memzero_explicit(&buf, sizeof(buf));
936 crng->init_time = jiffies;
Theodore Ts'od152fcc2018-04-12 00:50:45 -0400937 spin_unlock_irqrestore(&crng->lock, flags);
Theodore Ts'oe192be92016-06-12 18:13:36 -0400938 if (crng == &primary_crng && crng_init < 2) {
Jason A. Donenfeldb169c132017-06-07 19:45:31 -0400939 invalidate_batched_entropy();
Theodore Ts'o812b51a2018-04-11 15:23:56 -0400940 numa_crng_init();
Theodore Ts'oe192be92016-06-12 18:13:36 -0400941 crng_init = 2;
942 process_random_ready_list();
943 wake_up_interruptible(&crng_init_wait);
944 pr_notice("random: crng init done\n");
Theodore Ts'o76dbabb2018-04-25 01:12:32 -0400945 if (unseeded_warning.missed) {
946 pr_notice("random: %d get_random_xx warning(s) missed "
947 "due to ratelimiting\n",
948 unseeded_warning.missed);
949 unseeded_warning.missed = 0;
950 }
951 if (urandom_warning.missed) {
952 pr_notice("random: %d urandom warning(s) missed "
953 "due to ratelimiting\n",
954 urandom_warning.missed);
955 urandom_warning.missed = 0;
956 }
Theodore Ts'oe192be92016-06-12 18:13:36 -0400957 }
Theodore Ts'oe192be92016-06-12 18:13:36 -0400958}
959
Theodore Ts'o1e7f5832016-05-02 02:04:41 -0400960static void _extract_crng(struct crng_state *crng,
961 __u8 out[CHACHA20_BLOCK_SIZE])
Theodore Ts'oe192be92016-06-12 18:13:36 -0400962{
963 unsigned long v, flags;
Theodore Ts'oe192be92016-06-12 18:13:36 -0400964
Theodore Ts'o6e513bc2018-04-11 13:27:52 -0400965 if (crng_ready() &&
Theodore Ts'o90936d92018-04-11 16:32:17 -0400966 (time_after(crng_global_init_time, crng->init_time) ||
967 time_after(jiffies, crng->init_time + CRNG_RESEED_INTERVAL)))
Theodore Ts'o1e7f5832016-05-02 02:04:41 -0400968 crng_reseed(crng, crng == &primary_crng ? &input_pool : NULL);
Theodore Ts'oe192be92016-06-12 18:13:36 -0400969 spin_lock_irqsave(&crng->lock, flags);
970 if (arch_get_random_long(&v))
971 crng->state[14] ^= v;
972 chacha20_block(&crng->state[0], out);
973 if (crng->state[12] == 0)
974 crng->state[13]++;
975 spin_unlock_irqrestore(&crng->lock, flags);
976}
977
Theodore Ts'o1e7f5832016-05-02 02:04:41 -0400978static void extract_crng(__u8 out[CHACHA20_BLOCK_SIZE])
979{
980 struct crng_state *crng = NULL;
981
982#ifdef CONFIG_NUMA
983 if (crng_node_pool)
984 crng = crng_node_pool[numa_node_id()];
985 if (crng == NULL)
986#endif
987 crng = &primary_crng;
988 _extract_crng(crng, out);
989}
990
Theodore Ts'oc92e0402016-05-04 13:29:18 -0400991/*
992 * Use the leftover bytes from the CRNG block output (if there is
993 * enough) to mutate the CRNG key to provide backtracking protection.
994 */
995static void _crng_backtrack_protect(struct crng_state *crng,
996 __u8 tmp[CHACHA20_BLOCK_SIZE], int used)
997{
998 unsigned long flags;
999 __u32 *s, *d;
1000 int i;
1001
1002 used = round_up(used, sizeof(__u32));
1003 if (used + CHACHA20_KEY_SIZE > CHACHA20_BLOCK_SIZE) {
1004 extract_crng(tmp);
1005 used = 0;
1006 }
1007 spin_lock_irqsave(&crng->lock, flags);
1008 s = (__u32 *) &tmp[used];
1009 d = &crng->state[4];
1010 for (i=0; i < 8; i++)
1011 *d++ ^= *s++;
1012 spin_unlock_irqrestore(&crng->lock, flags);
1013}
1014
1015static void crng_backtrack_protect(__u8 tmp[CHACHA20_BLOCK_SIZE], int used)
1016{
1017 struct crng_state *crng = NULL;
1018
1019#ifdef CONFIG_NUMA
1020 if (crng_node_pool)
1021 crng = crng_node_pool[numa_node_id()];
1022 if (crng == NULL)
1023#endif
1024 crng = &primary_crng;
1025 _crng_backtrack_protect(crng, tmp, used);
1026}
1027
Theodore Ts'oe192be92016-06-12 18:13:36 -04001028static ssize_t extract_crng_user(void __user *buf, size_t nbytes)
1029{
Theodore Ts'oc92e0402016-05-04 13:29:18 -04001030 ssize_t ret = 0, i = CHACHA20_BLOCK_SIZE;
Theodore Ts'oe192be92016-06-12 18:13:36 -04001031 __u8 tmp[CHACHA20_BLOCK_SIZE];
1032 int large_request = (nbytes > 256);
1033
1034 while (nbytes) {
1035 if (large_request && need_resched()) {
1036 if (signal_pending(current)) {
1037 if (ret == 0)
1038 ret = -ERESTARTSYS;
1039 break;
1040 }
1041 schedule();
1042 }
1043
1044 extract_crng(tmp);
1045 i = min_t(int, nbytes, CHACHA20_BLOCK_SIZE);
1046 if (copy_to_user(buf, tmp, i)) {
1047 ret = -EFAULT;
1048 break;
1049 }
1050
1051 nbytes -= i;
1052 buf += i;
1053 ret += i;
1054 }
Theodore Ts'oc92e0402016-05-04 13:29:18 -04001055 crng_backtrack_protect(tmp, i);
Theodore Ts'oe192be92016-06-12 18:13:36 -04001056
1057 /* Wipe data just written to memory */
1058 memzero_explicit(tmp, sizeof(tmp));
1059
1060 return ret;
1061}
1062
1063
1064/*********************************************************************
1065 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001066 * Entropy input management
1067 *
1068 *********************************************************************/
1069
1070/* There is one of these per entropy source */
1071struct timer_rand_state {
1072 cycles_t last_time;
Matt Mackall90b75ee2008-04-29 01:02:55 -07001073 long last_delta, last_delta2;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001074 unsigned dont_count_entropy:1;
1075};
1076
Theodore Ts'o644008d2013-11-03 16:40:53 -05001077#define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, };
1078
Linus Torvaldsa2080a62012-07-04 11:16:01 -04001079/*
Theodore Ts'oe192be92016-06-12 18:13:36 -04001080 * Add device- or boot-specific data to the input pool to help
1081 * initialize it.
Linus Torvaldsa2080a62012-07-04 11:16:01 -04001082 *
Theodore Ts'oe192be92016-06-12 18:13:36 -04001083 * None of this adds any entropy; it is meant to avoid the problem of
1084 * the entropy pool having similar initial state across largely
1085 * identical devices.
Linus Torvaldsa2080a62012-07-04 11:16:01 -04001086 */
1087void add_device_randomness(const void *buf, unsigned int size)
1088{
Theodore Ts'o61875f32013-09-21 13:58:22 -04001089 unsigned long time = random_get_entropy() ^ jiffies;
Theodore Ts'o3ef4cb22013-09-12 14:27:22 -04001090 unsigned long flags;
Linus Torvaldsa2080a62012-07-04 11:16:01 -04001091
Theodore Ts'o7b6b1f32018-04-11 14:58:27 -04001092 if (!crng_ready() && size)
1093 crng_slow_load(buf, size);
Kees Cookee7998c2017-07-12 14:34:04 -07001094
Theodore Ts'o59108952013-09-12 14:10:25 -04001095 trace_add_device_randomness(size, _RET_IP_);
Theodore Ts'o3ef4cb22013-09-12 14:27:22 -04001096 spin_lock_irqsave(&input_pool.lock, flags);
Theodore Ts'o85608f82014-06-10 23:09:20 -04001097 _mix_pool_bytes(&input_pool, buf, size);
1098 _mix_pool_bytes(&input_pool, &time, sizeof(time));
Theodore Ts'o3ef4cb22013-09-12 14:27:22 -04001099 spin_unlock_irqrestore(&input_pool.lock, flags);
Linus Torvaldsa2080a62012-07-04 11:16:01 -04001100}
1101EXPORT_SYMBOL(add_device_randomness);
1102
Theodore Ts'o644008d2013-11-03 16:40:53 -05001103static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE;
Yinghai Lu3060d6f2008-08-19 20:50:08 -07001104
Linus Torvalds1da177e2005-04-16 15:20:36 -07001105/*
1106 * This function adds entropy to the entropy "pool" by using timing
1107 * delays. It uses the timer_rand_state structure to make an estimate
1108 * of how many bits of entropy this call has added to the pool.
1109 *
1110 * The number "num" is also added to the pool - it should somehow describe
1111 * the type of event which just happened. This is currently 0-255 for
1112 * keyboard scan codes, and 256 upwards for interrupts.
1113 *
1114 */
1115static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
1116{
Theodore Ts'o40db23e2013-11-03 00:15:05 -04001117 struct entropy_store *r;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001118 struct {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119 long jiffies;
Linus Torvaldscf833d02011-12-22 11:36:22 -08001120 unsigned cycles;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001121 unsigned num;
1122 } sample;
1123 long delta, delta2, delta3;
1124
1125 preempt_disable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126
1127 sample.jiffies = jiffies;
Theodore Ts'o61875f32013-09-21 13:58:22 -04001128 sample.cycles = random_get_entropy();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129 sample.num = num;
Theodore Ts'oe192be92016-06-12 18:13:36 -04001130 r = &input_pool;
Theodore Ts'o85608f82014-06-10 23:09:20 -04001131 mix_pool_bytes(r, &sample, sizeof(sample));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001132
1133 /*
1134 * Calculate number of bits of randomness we probably added.
1135 * We take into account the first, second and third-order deltas
1136 * in order to make our estimate.
1137 */
1138
1139 if (!state->dont_count_entropy) {
1140 delta = sample.jiffies - state->last_time;
1141 state->last_time = sample.jiffies;
1142
1143 delta2 = delta - state->last_delta;
1144 state->last_delta = delta;
1145
1146 delta3 = delta2 - state->last_delta2;
1147 state->last_delta2 = delta2;
1148
1149 if (delta < 0)
1150 delta = -delta;
1151 if (delta2 < 0)
1152 delta2 = -delta2;
1153 if (delta3 < 0)
1154 delta3 = -delta3;
1155 if (delta > delta2)
1156 delta = delta2;
1157 if (delta > delta3)
1158 delta = delta3;
1159
1160 /*
1161 * delta is now minimum absolute delta.
1162 * Round down by 1 bit on general principles,
1163 * and limit entropy entimate to 12 bits.
1164 */
Theodore Ts'o40db23e2013-11-03 00:15:05 -04001165 credit_entropy_bits(r, min_t(int, fls(delta>>1), 11));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001166 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001167 preempt_enable();
1168}
1169
Stephen Hemmingerd2515752006-01-11 12:17:38 -08001170void add_input_randomness(unsigned int type, unsigned int code,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001171 unsigned int value)
1172{
1173 static unsigned char last_value;
1174
1175 /* ignore autorepeat and the like */
1176 if (value == last_value)
1177 return;
1178
Linus Torvalds1da177e2005-04-16 15:20:36 -07001179 last_value = value;
1180 add_timer_randomness(&input_timer_state,
1181 (type << 4) ^ code ^ (code >> 4) ^ value);
Theodore Ts'of80bbd82013-10-03 12:02:37 -04001182 trace_add_input_randomness(ENTROPY_BITS(&input_pool));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001183}
Dmitry Torokhov80fc9f52006-10-11 01:43:58 -04001184EXPORT_SYMBOL_GPL(add_input_randomness);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001185
Theodore Ts'o775f4b22012-07-02 07:52:16 -04001186static DEFINE_PER_CPU(struct fast_pool, irq_randomness);
1187
Theodore Ts'o43759d42014-06-14 21:43:13 -04001188#ifdef ADD_INTERRUPT_BENCH
1189static unsigned long avg_cycles, avg_deviation;
1190
1191#define AVG_SHIFT 8 /* Exponential average factor k=1/256 */
1192#define FIXED_1_2 (1 << (AVG_SHIFT-1))
1193
1194static void add_interrupt_bench(cycles_t start)
1195{
1196 long delta = random_get_entropy() - start;
1197
1198 /* Use a weighted moving average */
1199 delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT);
1200 avg_cycles += delta;
1201 /* And average deviation */
1202 delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT);
1203 avg_deviation += delta;
1204}
1205#else
1206#define add_interrupt_bench(x)
1207#endif
1208
Theodore Ts'oee3e00e2014-06-15 16:59:24 -04001209static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
1210{
1211 __u32 *ptr = (__u32 *) regs;
Theodore Ts'o92e75422017-06-07 19:01:32 -04001212 unsigned int idx;
Theodore Ts'oee3e00e2014-06-15 16:59:24 -04001213
1214 if (regs == NULL)
1215 return 0;
Theodore Ts'o92e75422017-06-07 19:01:32 -04001216 idx = READ_ONCE(f->reg_idx);
1217 if (idx >= sizeof(struct pt_regs) / sizeof(__u32))
1218 idx = 0;
1219 ptr += idx++;
1220 WRITE_ONCE(f->reg_idx, idx);
Michael Schmitz9dfa7bb2017-04-30 19:49:21 +12001221 return *ptr;
Theodore Ts'oee3e00e2014-06-15 16:59:24 -04001222}
1223
Theodore Ts'o775f4b22012-07-02 07:52:16 -04001224void add_interrupt_randomness(int irq, int irq_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001225{
Theodore Ts'o775f4b22012-07-02 07:52:16 -04001226 struct entropy_store *r;
Christoph Lameter1b2a1a72014-08-17 12:30:29 -05001227 struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);
Theodore Ts'o775f4b22012-07-02 07:52:16 -04001228 struct pt_regs *regs = get_irq_regs();
1229 unsigned long now = jiffies;
Theodore Ts'o655b2262013-09-22 15:24:02 -04001230 cycles_t cycles = random_get_entropy();
Theodore Ts'o43759d42014-06-14 21:43:13 -04001231 __u32 c_high, j_high;
Theodore Ts'o655b2262013-09-22 15:24:02 -04001232 __u64 ip;
H. Peter Anvin83664a62014-03-17 16:36:28 -07001233 unsigned long seed;
Theodore Ts'o91fcb532014-06-10 22:46:37 -04001234 int credit = 0;
Yinghai Lu3060d6f2008-08-19 20:50:08 -07001235
Theodore Ts'oee3e00e2014-06-15 16:59:24 -04001236 if (cycles == 0)
1237 cycles = get_reg(fast_pool, regs);
Theodore Ts'o655b2262013-09-22 15:24:02 -04001238 c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0;
1239 j_high = (sizeof(now) > 4) ? now >> 32 : 0;
Theodore Ts'o43759d42014-06-14 21:43:13 -04001240 fast_pool->pool[0] ^= cycles ^ j_high ^ irq;
1241 fast_pool->pool[1] ^= now ^ c_high;
Theodore Ts'o655b2262013-09-22 15:24:02 -04001242 ip = regs ? instruction_pointer(regs) : _RET_IP_;
Theodore Ts'o43759d42014-06-14 21:43:13 -04001243 fast_pool->pool[2] ^= ip;
Theodore Ts'oee3e00e2014-06-15 16:59:24 -04001244 fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 :
1245 get_reg(fast_pool, regs);
Yinghai Lu3060d6f2008-08-19 20:50:08 -07001246
Theodore Ts'o43759d42014-06-14 21:43:13 -04001247 fast_mix(fast_pool);
Theodore Ts'o43759d42014-06-14 21:43:13 -04001248 add_interrupt_bench(cycles);
Theodore Ts'o775f4b22012-07-02 07:52:16 -04001249
Theodore Ts'o6e513bc2018-04-11 13:27:52 -04001250 if (unlikely(crng_init == 0)) {
Theodore Ts'oe192be92016-06-12 18:13:36 -04001251 if ((fast_pool->count >= 64) &&
1252 crng_fast_load((char *) fast_pool->pool,
1253 sizeof(fast_pool->pool))) {
1254 fast_pool->count = 0;
1255 fast_pool->last = now;
1256 }
1257 return;
1258 }
1259
Theodore Ts'oee3e00e2014-06-15 16:59:24 -04001260 if ((fast_pool->count < 64) &&
1261 !time_after(now, fast_pool->last + HZ))
1262 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001263
Theodore Ts'oe192be92016-06-12 18:13:36 -04001264 r = &input_pool;
Theodore Ts'o840f9502014-06-14 03:06:57 -04001265 if (!spin_trylock(&r->lock))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266 return;
1267
Theodore Ts'o775f4b22012-07-02 07:52:16 -04001268 fast_pool->last = now;
Theodore Ts'o85608f82014-06-10 23:09:20 -04001269 __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool));
H. Peter Anvin83664a62014-03-17 16:36:28 -07001270
1271 /*
1272 * If we have architectural seed generator, produce a seed and
Theodore Ts'o48d6be92014-07-17 05:27:30 -04001273 * add it to the pool. For the sake of paranoia don't let the
1274 * architectural seed generator dominate the input from the
1275 * interrupt noise.
H. Peter Anvin83664a62014-03-17 16:36:28 -07001276 */
1277 if (arch_get_random_seed_long(&seed)) {
Theodore Ts'o85608f82014-06-10 23:09:20 -04001278 __mix_pool_bytes(r, &seed, sizeof(seed));
Theodore Ts'o48d6be92014-07-17 05:27:30 -04001279 credit = 1;
H. Peter Anvin83664a62014-03-17 16:36:28 -07001280 }
Theodore Ts'o91fcb532014-06-10 22:46:37 -04001281 spin_unlock(&r->lock);
H. Peter Anvin83664a62014-03-17 16:36:28 -07001282
Theodore Ts'oee3e00e2014-06-15 16:59:24 -04001283 fast_pool->count = 0;
Theodore Ts'o840f9502014-06-14 03:06:57 -04001284
Theodore Ts'oee3e00e2014-06-15 16:59:24 -04001285 /* award one bit for the contents of the fast pool */
1286 credit_entropy_bits(r, credit + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001287}
Stephan Mueller4b44f2d2016-05-02 02:14:34 -04001288EXPORT_SYMBOL_GPL(add_interrupt_randomness);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289
David Howells93614012006-09-30 20:45:40 +02001290#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07001291void add_disk_randomness(struct gendisk *disk)
1292{
1293 if (!disk || !disk->random)
1294 return;
1295 /* first major is 1, so we get >= 0x200 here */
Tejun Heof331c022008-09-03 09:01:48 +02001296 add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
Theodore Ts'of80bbd82013-10-03 12:02:37 -04001297 trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS(&input_pool));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298}
Christoph Hellwigbdcfa3e2014-04-25 00:36:37 -07001299EXPORT_SYMBOL_GPL(add_disk_randomness);
David Howells93614012006-09-30 20:45:40 +02001300#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001301
Linus Torvalds1da177e2005-04-16 15:20:36 -07001302/*********************************************************************
1303 *
1304 * Entropy extraction routines
1305 *
1306 *********************************************************************/
1307
Linus Torvalds1da177e2005-04-16 15:20:36 -07001308/*
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001309 * This utility inline function is responsible for transferring entropy
Linus Torvalds1da177e2005-04-16 15:20:36 -07001310 * from the primary pool to the secondary extraction pool. We make
1311 * sure we pull enough for a 'catastrophic reseed'.
1312 */
Theodore Ts'o6265e162013-10-03 01:08:15 -04001313static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001314static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
1315{
Theodore Ts'ocff85032014-06-10 23:18:16 -04001316 if (!r->pull ||
1317 r->entropy_count >= (nbytes << (ENTROPY_SHIFT + 3)) ||
1318 r->entropy_count > r->poolinfo->poolfracbits)
1319 return;
1320
Theodore Ts'ocff85032014-06-10 23:18:16 -04001321 _xfer_secondary_pool(r, nbytes);
Theodore Ts'o6265e162013-10-03 01:08:15 -04001322}
Matt Mackall5a021e92007-07-19 11:30:14 -07001323
Theodore Ts'o6265e162013-10-03 01:08:15 -04001324static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
1325{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001326 __u32 tmp[OUTPUT_POOL_WORDS];
1327
Theodore Ts'o6265e162013-10-03 01:08:15 -04001328 int bytes = nbytes;
Matt Mackall5a021e92007-07-19 11:30:14 -07001329
Greg Price2132a962013-12-06 21:28:03 -05001330 /* pull at least as much as a wakeup */
1331 bytes = max_t(int, bytes, random_read_wakeup_bits / 8);
Theodore Ts'o6265e162013-10-03 01:08:15 -04001332 /* but never more than the buffer size */
1333 bytes = min_t(int, bytes, sizeof(tmp));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001334
Theodore Ts'of80bbd82013-10-03 12:02:37 -04001335 trace_xfer_secondary_pool(r->name, bytes * 8, nbytes * 8,
1336 ENTROPY_BITS(r), ENTROPY_BITS(r->pull));
Theodore Ts'o6265e162013-10-03 01:08:15 -04001337 bytes = extract_entropy(r->pull, tmp, bytes,
Stephan Müller43d8a722016-12-27 23:40:59 +01001338 random_read_wakeup_bits / 8, 0);
Theodore Ts'o85608f82014-06-10 23:09:20 -04001339 mix_pool_bytes(r, tmp, bytes);
Theodore Ts'o6265e162013-10-03 01:08:15 -04001340 credit_entropy_bits(r, bytes*8);
1341}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342
Theodore Ts'o6265e162013-10-03 01:08:15 -04001343/*
1344 * Used as a workqueue function so that when the input pool is getting
1345 * full, we can "spill over" some entropy to the output pools. That
1346 * way the output pools can store some of the excess entropy instead
1347 * of letting it go to waste.
1348 */
1349static void push_to_pool(struct work_struct *work)
1350{
1351 struct entropy_store *r = container_of(work, struct entropy_store,
1352 push_work);
1353 BUG_ON(!r);
Greg Price2132a962013-12-06 21:28:03 -05001354 _xfer_secondary_pool(r, random_read_wakeup_bits/8);
Theodore Ts'o6265e162013-10-03 01:08:15 -04001355 trace_push_to_pool(r->name, r->entropy_count >> ENTROPY_SHIFT,
1356 r->pull->entropy_count >> ENTROPY_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357}
1358
1359/*
Greg Price19fa5be2013-11-29 15:50:06 -05001360 * This function decides how many bytes to actually take from the
1361 * given pool, and also debits the entropy count accordingly.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001362 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363static size_t account(struct entropy_store *r, size_t nbytes, int min,
1364 int reserved)
1365{
Stephan Müller43d8a722016-12-27 23:40:59 +01001366 int entropy_count, orig, have_bytes;
Hannes Frederic Sowa79a84682014-07-18 17:26:41 -04001367 size_t ibytes, nfrac;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001369 BUG_ON(r->entropy_count > r->poolinfo->poolfracbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370
1371 /* Can we pull enough? */
Jiri Kosina10b3a322013-05-24 15:55:33 -07001372retry:
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001373 entropy_count = orig = ACCESS_ONCE(r->entropy_count);
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001374 ibytes = nbytes;
Stephan Müller43d8a722016-12-27 23:40:59 +01001375 /* never pull more than available */
1376 have_bytes = entropy_count >> (ENTROPY_SHIFT + 3);
Theodore Ts'oe33ba5f2014-06-15 21:04:32 -04001377
Stephan Müller43d8a722016-12-27 23:40:59 +01001378 if ((have_bytes -= reserved) < 0)
1379 have_bytes = 0;
1380 ibytes = min_t(size_t, ibytes, have_bytes);
Greg Price0fb7a012013-12-05 19:32:19 -05001381 if (ibytes < min)
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001382 ibytes = 0;
Hannes Frederic Sowa79a84682014-07-18 17:26:41 -04001383
1384 if (unlikely(entropy_count < 0)) {
1385 pr_warn("random: negative entropy count: pool %s count %d\n",
1386 r->name, entropy_count);
1387 WARN_ON(1);
1388 entropy_count = 0;
1389 }
1390 nfrac = ibytes << (ENTROPY_SHIFT + 3);
1391 if ((size_t) entropy_count > nfrac)
1392 entropy_count -= nfrac;
1393 else
Theodore Ts'oe33ba5f2014-06-15 21:04:32 -04001394 entropy_count = 0;
Theodore Ts'of9c6d492014-05-16 21:40:41 -04001395
Greg Price0fb7a012013-12-05 19:32:19 -05001396 if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
1397 goto retry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398
Theodore Ts'of80bbd82013-10-03 12:02:37 -04001399 trace_debit_entropy(r->name, 8 * ibytes);
Greg Price0fb7a012013-12-05 19:32:19 -05001400 if (ibytes &&
Greg Price2132a962013-12-06 21:28:03 -05001401 (r->entropy_count >> ENTROPY_SHIFT) < random_write_wakeup_bits) {
Theodore Ts'ob9809552013-03-04 11:59:12 -05001402 wake_up_interruptible(&random_write_wait);
1403 kill_fasync(&fasync, SIGIO, POLL_OUT);
1404 }
1405
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001406 return ibytes;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001407}
1408
Greg Price19fa5be2013-11-29 15:50:06 -05001409/*
1410 * This function does the actual extraction for extract_entropy and
1411 * extract_entropy_user.
1412 *
1413 * Note: we assume that .poolwords is a multiple of 16 words.
1414 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001415static void extract_buf(struct entropy_store *r, __u8 *out)
1416{
Matt Mackall602b6ae2007-05-29 21:54:27 -05001417 int i;
H. Peter Anvind2e7c962012-07-27 22:26:08 -04001418 union {
1419 __u32 w[5];
Theodore Ts'o85a1f772013-09-21 18:06:02 -04001420 unsigned long l[LONGS(20)];
H. Peter Anvind2e7c962012-07-27 22:26:08 -04001421 } hash;
1422 __u32 workspace[SHA_WORKSPACE_WORDS];
Theodore Ts'o902c0982012-07-04 10:38:30 -04001423 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425 /*
Greg Pricedfd38752013-11-29 14:58:06 -05001426 * If we have an architectural hardware random number
Theodore Ts'o46884442013-12-17 21:16:39 -05001427 * generator, use it for SHA's initial vector
Theodore Ts'o85a1f772013-09-21 18:06:02 -04001428 */
Theodore Ts'o46884442013-12-17 21:16:39 -05001429 sha_init(hash.w);
Theodore Ts'o85a1f772013-09-21 18:06:02 -04001430 for (i = 0; i < LONGS(20); i++) {
1431 unsigned long v;
1432 if (!arch_get_random_long(&v))
1433 break;
Theodore Ts'o46884442013-12-17 21:16:39 -05001434 hash.l[i] = v;
Theodore Ts'o85a1f772013-09-21 18:06:02 -04001435 }
1436
Theodore Ts'o46884442013-12-17 21:16:39 -05001437 /* Generate a hash across the pool, 16 words (512 bits) at a time */
1438 spin_lock_irqsave(&r->lock, flags);
1439 for (i = 0; i < r->poolinfo->poolwords; i += 16)
1440 sha_transform(hash.w, (__u8 *)(r->pool + i), workspace);
1441
Theodore Ts'o85a1f772013-09-21 18:06:02 -04001442 /*
Matt Mackall1c0ad3d2008-04-29 01:03:00 -07001443 * We mix the hash back into the pool to prevent backtracking
1444 * attacks (where the attacker knows the state of the pool
1445 * plus the current outputs, and attempts to find previous
1446 * ouputs), unless the hash function can be inverted. By
1447 * mixing at least a SHA1 worth of hash data back, we make
1448 * brute-forcing the feedback as hard as brute-forcing the
1449 * hash.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001450 */
Theodore Ts'o85608f82014-06-10 23:09:20 -04001451 __mix_pool_bytes(r, hash.w, sizeof(hash.w));
Theodore Ts'o902c0982012-07-04 10:38:30 -04001452 spin_unlock_irqrestore(&r->lock, flags);
Matt Mackall1c0ad3d2008-04-29 01:03:00 -07001453
Daniel Borkmannd4c5efd2014-08-26 23:16:35 -04001454 memzero_explicit(workspace, sizeof(workspace));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001455
1456 /*
Matt Mackall1c0ad3d2008-04-29 01:03:00 -07001457 * In case the hash function has some recognizable output
1458 * pattern, we fold it in half. Thus, we always feed back
1459 * twice as much data as we output.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460 */
H. Peter Anvind2e7c962012-07-27 22:26:08 -04001461 hash.w[0] ^= hash.w[3];
1462 hash.w[1] ^= hash.w[4];
1463 hash.w[2] ^= rol32(hash.w[2], 16);
1464
H. Peter Anvind2e7c962012-07-27 22:26:08 -04001465 memcpy(out, &hash, EXTRACT_SIZE);
Daniel Borkmannd4c5efd2014-08-26 23:16:35 -04001466 memzero_explicit(&hash, sizeof(hash));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001467}
1468
Theodore Ts'oe192be92016-06-12 18:13:36 -04001469static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
1470 size_t nbytes, int fips)
1471{
1472 ssize_t ret = 0, i;
1473 __u8 tmp[EXTRACT_SIZE];
1474 unsigned long flags;
1475
1476 while (nbytes) {
1477 extract_buf(r, tmp);
1478
1479 if (fips) {
1480 spin_lock_irqsave(&r->lock, flags);
1481 if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
1482 panic("Hardware RNG duplicated output!\n");
1483 memcpy(r->last_data, tmp, EXTRACT_SIZE);
1484 spin_unlock_irqrestore(&r->lock, flags);
1485 }
1486 i = min_t(int, nbytes, EXTRACT_SIZE);
1487 memcpy(buf, tmp, i);
1488 nbytes -= i;
1489 buf += i;
1490 ret += i;
1491 }
1492
1493 /* Wipe data just returned from memory */
1494 memzero_explicit(tmp, sizeof(tmp));
1495
1496 return ret;
1497}
1498
Greg Price19fa5be2013-11-29 15:50:06 -05001499/*
1500 * This function extracts randomness from the "entropy pool", and
1501 * returns it in a buffer.
1502 *
1503 * The min parameter specifies the minimum amount we can pull before
1504 * failing to avoid races that defeat catastrophic reseeding while the
1505 * reserved parameter indicates how much entropy we must leave in the
1506 * pool after each pull to avoid starving other readers.
1507 */
Matt Mackall90b75ee2008-04-29 01:02:55 -07001508static ssize_t extract_entropy(struct entropy_store *r, void *buf,
Theodore Ts'o902c0982012-07-04 10:38:30 -04001509 size_t nbytes, int min, int reserved)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001510{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511 __u8 tmp[EXTRACT_SIZE];
Jarod Wilson1e7e2e02013-05-24 15:55:31 -07001512 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001513
Jarod Wilsonec8f02da2012-11-06 10:42:42 -05001514 /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
Jarod Wilson1e7e2e02013-05-24 15:55:31 -07001515 if (fips_enabled) {
1516 spin_lock_irqsave(&r->lock, flags);
1517 if (!r->last_data_init) {
Theodore Ts'oc59974a2013-09-21 19:42:41 -04001518 r->last_data_init = 1;
Jarod Wilson1e7e2e02013-05-24 15:55:31 -07001519 spin_unlock_irqrestore(&r->lock, flags);
1520 trace_extract_entropy(r->name, EXTRACT_SIZE,
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001521 ENTROPY_BITS(r), _RET_IP_);
Jarod Wilson1e7e2e02013-05-24 15:55:31 -07001522 xfer_secondary_pool(r, EXTRACT_SIZE);
1523 extract_buf(r, tmp);
1524 spin_lock_irqsave(&r->lock, flags);
1525 memcpy(r->last_data, tmp, EXTRACT_SIZE);
1526 }
1527 spin_unlock_irqrestore(&r->lock, flags);
1528 }
Jarod Wilsonec8f02da2012-11-06 10:42:42 -05001529
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001530 trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001531 xfer_secondary_pool(r, nbytes);
1532 nbytes = account(r, nbytes, min, reserved);
1533
Theodore Ts'oe192be92016-06-12 18:13:36 -04001534 return _extract_entropy(r, buf, nbytes, fips_enabled);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001535}
1536
Greg Price19fa5be2013-11-29 15:50:06 -05001537/*
1538 * This function extracts randomness from the "entropy pool", and
1539 * returns it in a userspace buffer.
1540 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001541static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
1542 size_t nbytes)
1543{
1544 ssize_t ret = 0, i;
1545 __u8 tmp[EXTRACT_SIZE];
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001546 int large_request = (nbytes > 256);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001547
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001548 trace_extract_entropy_user(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001549 xfer_secondary_pool(r, nbytes);
1550 nbytes = account(r, nbytes, 0, 0);
1551
1552 while (nbytes) {
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001553 if (large_request && need_resched()) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001554 if (signal_pending(current)) {
1555 if (ret == 0)
1556 ret = -ERESTARTSYS;
1557 break;
1558 }
1559 schedule();
1560 }
1561
1562 extract_buf(r, tmp);
1563 i = min_t(int, nbytes, EXTRACT_SIZE);
1564 if (copy_to_user(buf, tmp, i)) {
1565 ret = -EFAULT;
1566 break;
1567 }
1568
1569 nbytes -= i;
1570 buf += i;
1571 ret += i;
1572 }
1573
1574 /* Wipe data just returned from memory */
Daniel Borkmannd4c5efd2014-08-26 23:16:35 -04001575 memzero_explicit(tmp, sizeof(tmp));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001576
1577 return ret;
1578}
1579
Theodore Ts'oeecabf52017-06-08 04:16:59 -04001580#define warn_unseeded_randomness(previous) \
1581 _warn_unseeded_randomness(__func__, (void *) _RET_IP_, (previous))
1582
1583static void _warn_unseeded_randomness(const char *func_name, void *caller,
1584 void **previous)
1585{
1586#ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM
1587 const bool print_once = false;
1588#else
1589 static bool print_once __read_mostly;
1590#endif
1591
1592 if (print_once ||
1593 crng_ready() ||
1594 (previous && (caller == READ_ONCE(*previous))))
1595 return;
1596 WRITE_ONCE(*previous, caller);
1597#ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM
1598 print_once = true;
1599#endif
Theodore Ts'o76dbabb2018-04-25 01:12:32 -04001600 if (__ratelimit(&unseeded_warning))
1601 pr_notice("random: %s called from %pS with crng_init=%d\n",
1602 func_name, caller, crng_init);
Theodore Ts'oeecabf52017-06-08 04:16:59 -04001603}
1604
Linus Torvalds1da177e2005-04-16 15:20:36 -07001605/*
1606 * This function is the exported kernel interface. It returns some
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001607 * number of good random numbers, suitable for key generation, seeding
Greg Price18e9cea2013-11-29 14:59:45 -05001608 * TCP sequence numbers, etc. It does not rely on the hardware random
1609 * number generator. For random bytes direct from the hardware RNG
Jason A. Donenfelde297a782017-06-07 19:58:56 -04001610 * (when available), use get_random_bytes_arch(). In order to ensure
1611 * that the randomness provided by this function is okay, the function
1612 * wait_for_random_bytes() should be called and return 0 at least once
1613 * at any point prior.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614 */
Theodore Ts'oeecabf52017-06-08 04:16:59 -04001615static void _get_random_bytes(void *buf, int nbytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616{
Theodore Ts'oe192be92016-06-12 18:13:36 -04001617 __u8 tmp[CHACHA20_BLOCK_SIZE];
1618
Theodore Ts'o59108952013-09-12 14:10:25 -04001619 trace_get_random_bytes(nbytes, _RET_IP_);
Theodore Ts'oe192be92016-06-12 18:13:36 -04001620
1621 while (nbytes >= CHACHA20_BLOCK_SIZE) {
1622 extract_crng(buf);
1623 buf += CHACHA20_BLOCK_SIZE;
1624 nbytes -= CHACHA20_BLOCK_SIZE;
1625 }
1626
1627 if (nbytes > 0) {
1628 extract_crng(tmp);
1629 memcpy(buf, tmp, nbytes);
Theodore Ts'oc92e0402016-05-04 13:29:18 -04001630 crng_backtrack_protect(tmp, nbytes);
1631 } else
1632 crng_backtrack_protect(tmp, CHACHA20_BLOCK_SIZE);
1633 memzero_explicit(tmp, sizeof(tmp));
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001634}
Theodore Ts'oeecabf52017-06-08 04:16:59 -04001635
1636void get_random_bytes(void *buf, int nbytes)
1637{
1638 static void *previous;
1639
1640 warn_unseeded_randomness(&previous);
1641 _get_random_bytes(buf, nbytes);
1642}
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001643EXPORT_SYMBOL(get_random_bytes);
1644
1645/*
Jason A. Donenfelde297a782017-06-07 19:58:56 -04001646 * Wait for the urandom pool to be seeded and thus guaranteed to supply
1647 * cryptographically secure random numbers. This applies to: the /dev/urandom
1648 * device, the get_random_bytes function, and the get_random_{u32,u64,int,long}
1649 * family of functions. Using any of these functions without first calling
1650 * this function forfeits the guarantee of security.
1651 *
1652 * Returns: 0 if the urandom pool has been seeded.
1653 * -ERESTARTSYS if the function was interrupted by a signal.
1654 */
1655int wait_for_random_bytes(void)
1656{
1657 if (likely(crng_ready()))
1658 return 0;
1659 return wait_event_interruptible(crng_init_wait, crng_ready());
1660}
1661EXPORT_SYMBOL(wait_for_random_bytes);
1662
1663/*
Herbert Xu205a5252015-06-09 18:19:39 +08001664 * Add a callback function that will be invoked when the nonblocking
1665 * pool is initialised.
1666 *
1667 * returns: 0 if callback is successfully added
1668 * -EALREADY if pool is already initialised (callback not called)
1669 * -ENOENT if module for callback is not alive
1670 */
1671int add_random_ready_callback(struct random_ready_callback *rdy)
1672{
1673 struct module *owner;
1674 unsigned long flags;
1675 int err = -EALREADY;
1676
Theodore Ts'oe192be92016-06-12 18:13:36 -04001677 if (crng_ready())
Herbert Xu205a5252015-06-09 18:19:39 +08001678 return err;
1679
1680 owner = rdy->owner;
1681 if (!try_module_get(owner))
1682 return -ENOENT;
1683
1684 spin_lock_irqsave(&random_ready_list_lock, flags);
Theodore Ts'oe192be92016-06-12 18:13:36 -04001685 if (crng_ready())
Herbert Xu205a5252015-06-09 18:19:39 +08001686 goto out;
1687
1688 owner = NULL;
1689
1690 list_add(&rdy->list, &random_ready_list);
1691 err = 0;
1692
1693out:
1694 spin_unlock_irqrestore(&random_ready_list_lock, flags);
1695
1696 module_put(owner);
1697
1698 return err;
1699}
1700EXPORT_SYMBOL(add_random_ready_callback);
1701
1702/*
1703 * Delete a previously registered readiness callback function.
1704 */
1705void del_random_ready_callback(struct random_ready_callback *rdy)
1706{
1707 unsigned long flags;
1708 struct module *owner = NULL;
1709
1710 spin_lock_irqsave(&random_ready_list_lock, flags);
1711 if (!list_empty(&rdy->list)) {
1712 list_del_init(&rdy->list);
1713 owner = rdy->owner;
1714 }
1715 spin_unlock_irqrestore(&random_ready_list_lock, flags);
1716
1717 module_put(owner);
1718}
1719EXPORT_SYMBOL(del_random_ready_callback);
1720
1721/*
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001722 * This function will use the architecture-specific hardware random
1723 * number generator if it is available. The arch-specific hw RNG will
1724 * almost certainly be faster than what we can do in software, but it
1725 * is impossible to verify that it is implemented securely (as
1726 * opposed, to, say, the AES encryption of a sequence number using a
1727 * key known by the NSA). So it's useful if we need the speed, but
1728 * only if we're willing to trust the hardware manufacturer not to
1729 * have put in a back door.
1730 */
1731void get_random_bytes_arch(void *buf, int nbytes)
1732{
H. Peter Anvin63d77172011-07-31 13:54:50 -07001733 char *p = buf;
1734
Theodore Ts'o59108952013-09-12 14:10:25 -04001735 trace_get_random_bytes_arch(nbytes, _RET_IP_);
H. Peter Anvin63d77172011-07-31 13:54:50 -07001736 while (nbytes) {
1737 unsigned long v;
1738 int chunk = min(nbytes, (int)sizeof(unsigned long));
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001739
H. Peter Anvin63d77172011-07-31 13:54:50 -07001740 if (!arch_get_random_long(&v))
1741 break;
1742
Luck, Tonybd29e562011-11-16 10:50:56 -08001743 memcpy(p, &v, chunk);
H. Peter Anvin63d77172011-07-31 13:54:50 -07001744 p += chunk;
1745 nbytes -= chunk;
1746 }
1747
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001748 if (nbytes)
Theodore Ts'oe192be92016-06-12 18:13:36 -04001749 get_random_bytes(p, nbytes);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001750}
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001751EXPORT_SYMBOL(get_random_bytes_arch);
1752
Linus Torvalds1da177e2005-04-16 15:20:36 -07001753
1754/*
1755 * init_std_data - initialize pool with system data
1756 *
1757 * @r: pool to initialize
1758 *
1759 * This function clears the pool's entropy count and mixes some system
1760 * data into the pool to prepare it for use. The pool is not cleared
1761 * as that can only decrease the entropy in the pool.
1762 */
1763static void init_std_data(struct entropy_store *r)
1764{
Theodore Ts'o3e88bdf2011-12-22 16:28:01 -05001765 int i;
Theodore Ts'o902c0982012-07-04 10:38:30 -04001766 ktime_t now = ktime_get_real();
1767 unsigned long rv;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768
Theodore Ts'of5c27422013-09-22 15:14:32 -04001769 r->last_pulled = jiffies;
Theodore Ts'o85608f82014-06-10 23:09:20 -04001770 mix_pool_bytes(r, &now, sizeof(now));
H. Peter Anvin9ed17b72013-09-10 23:16:17 -04001771 for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) {
H. Peter Anvin83664a62014-03-17 16:36:28 -07001772 if (!arch_get_random_seed_long(&rv) &&
1773 !arch_get_random_long(&rv))
Theodore Ts'oae9ecd92013-11-03 07:56:17 -05001774 rv = random_get_entropy();
Theodore Ts'o85608f82014-06-10 23:09:20 -04001775 mix_pool_bytes(r, &rv, sizeof(rv));
Theodore Ts'o3e88bdf2011-12-22 16:28:01 -05001776 }
Theodore Ts'o85608f82014-06-10 23:09:20 -04001777 mix_pool_bytes(r, utsname(), sizeof(*(utsname())));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001778}
1779
Tony Luckcbc96b72012-07-23 09:47:57 -07001780/*
1781 * Note that setup_arch() may call add_device_randomness()
1782 * long before we get here. This allows seeding of the pools
1783 * with some platform dependent data very early in the boot
1784 * process. But it limits our options here. We must use
1785 * statically allocated structures that already have all
1786 * initializations complete at compile time. We should also
1787 * take care not to overwrite the precious per platform data
1788 * we were given.
1789 */
Matt Mackall53c3f632008-04-29 01:02:58 -07001790static int rand_initialize(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001791{
1792 init_std_data(&input_pool);
1793 init_std_data(&blocking_pool);
Theodore Ts'oe192be92016-06-12 18:13:36 -04001794 crng_initialize(&primary_crng);
Theodore Ts'o90936d92018-04-11 16:32:17 -04001795 crng_global_init_time = jiffies;
Theodore Ts'o76dbabb2018-04-25 01:12:32 -04001796 if (ratelimit_disable) {
1797 urandom_warning.interval = 0;
1798 unseeded_warning.interval = 0;
1799 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800 return 0;
1801}
Theodore Ts'oae9ecd92013-11-03 07:56:17 -05001802early_initcall(rand_initialize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001803
David Howells93614012006-09-30 20:45:40 +02001804#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07001805void rand_initialize_disk(struct gendisk *disk)
1806{
1807 struct timer_rand_state *state;
1808
1809 /*
Eric Dumazetf8595812007-03-28 14:22:33 -07001810 * If kzalloc returns null, we just won't use that entropy
Linus Torvalds1da177e2005-04-16 15:20:36 -07001811 * source.
1812 */
Eric Dumazetf8595812007-03-28 14:22:33 -07001813 state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
Theodore Ts'o644008d2013-11-03 16:40:53 -05001814 if (state) {
1815 state->last_time = INITIAL_JIFFIES;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001816 disk->random = state;
Theodore Ts'o644008d2013-11-03 16:40:53 -05001817 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001818}
David Howells93614012006-09-30 20:45:40 +02001819#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001820
1821static ssize_t
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001822_random_read(int nonblock, char __user *buf, size_t nbytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001823{
Greg Price12ff3a52013-11-29 15:02:33 -05001824 ssize_t n;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001825
1826 if (nbytes == 0)
1827 return 0;
1828
Greg Price12ff3a52013-11-29 15:02:33 -05001829 nbytes = min_t(size_t, nbytes, SEC_XFER_SIZE);
1830 while (1) {
1831 n = extract_entropy_user(&blocking_pool, buf, nbytes);
1832 if (n < 0)
1833 return n;
Theodore Ts'of80bbd82013-10-03 12:02:37 -04001834 trace_random_read(n*8, (nbytes-n)*8,
1835 ENTROPY_BITS(&blocking_pool),
1836 ENTROPY_BITS(&input_pool));
Greg Price12ff3a52013-11-29 15:02:33 -05001837 if (n > 0)
1838 return n;
H. Peter Anvin331c6492014-03-17 16:36:29 -07001839
Greg Price12ff3a52013-11-29 15:02:33 -05001840 /* Pool is (near) empty. Maybe wait and retry. */
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001841 if (nonblock)
Greg Price12ff3a52013-11-29 15:02:33 -05001842 return -EAGAIN;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001843
Greg Price12ff3a52013-11-29 15:02:33 -05001844 wait_event_interruptible(random_read_wait,
1845 ENTROPY_BITS(&input_pool) >=
Greg Price2132a962013-12-06 21:28:03 -05001846 random_read_wakeup_bits);
Greg Price12ff3a52013-11-29 15:02:33 -05001847 if (signal_pending(current))
1848 return -ERESTARTSYS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001849 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001850}
1851
1852static ssize_t
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001853random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
1854{
1855 return _random_read(file->f_flags & O_NONBLOCK, buf, nbytes);
1856}
1857
1858static ssize_t
Matt Mackall90b75ee2008-04-29 01:02:55 -07001859urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001860{
Theodore Ts'oe192be92016-06-12 18:13:36 -04001861 unsigned long flags;
Theodore Ts'o9b4d0082016-06-13 10:10:51 -04001862 static int maxwarn = 10;
Theodore Ts'o301f0592013-11-03 06:54:51 -05001863 int ret;
1864
Theodore Ts'oe192be92016-06-12 18:13:36 -04001865 if (!crng_ready() && maxwarn > 0) {
Theodore Ts'o9b4d0082016-06-13 10:10:51 -04001866 maxwarn--;
Theodore Ts'o76dbabb2018-04-25 01:12:32 -04001867 if (__ratelimit(&urandom_warning))
1868 printk(KERN_NOTICE "random: %s: uninitialized "
1869 "urandom read (%zd bytes read)\n",
1870 current->comm, nbytes);
Theodore Ts'oe192be92016-06-12 18:13:36 -04001871 spin_lock_irqsave(&primary_crng.lock, flags);
1872 crng_init_cnt = 0;
1873 spin_unlock_irqrestore(&primary_crng.lock, flags);
Theodore Ts'o9b4d0082016-06-13 10:10:51 -04001874 }
Hannes Frederic Sowa79a84682014-07-18 17:26:41 -04001875 nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));
Theodore Ts'oe192be92016-06-12 18:13:36 -04001876 ret = extract_crng_user(buf, nbytes);
1877 trace_urandom_read(8 * nbytes, 0, ENTROPY_BITS(&input_pool));
Theodore Ts'of80bbd82013-10-03 12:02:37 -04001878 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001879}
1880
1881static unsigned int
1882random_poll(struct file *file, poll_table * wait)
1883{
1884 unsigned int mask;
1885
1886 poll_wait(file, &random_read_wait, wait);
1887 poll_wait(file, &random_write_wait, wait);
1888 mask = 0;
Greg Price2132a962013-12-06 21:28:03 -05001889 if (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001890 mask |= POLLIN | POLLRDNORM;
Greg Price2132a962013-12-06 21:28:03 -05001891 if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001892 mask |= POLLOUT | POLLWRNORM;
1893 return mask;
1894}
1895
Matt Mackall7f397dc2007-05-29 21:58:10 -05001896static int
1897write_pool(struct entropy_store *r, const char __user *buffer, size_t count)
1898{
1899 size_t bytes;
Theodore Ts'oaf41fd02018-07-14 23:55:57 -04001900 __u32 t, buf[16];
Matt Mackall7f397dc2007-05-29 21:58:10 -05001901 const char __user *p = buffer;
1902
1903 while (count > 0) {
Theodore Ts'oaf41fd02018-07-14 23:55:57 -04001904 int b, i = 0;
1905
Matt Mackall7f397dc2007-05-29 21:58:10 -05001906 bytes = min(count, sizeof(buf));
1907 if (copy_from_user(&buf, p, bytes))
1908 return -EFAULT;
1909
Theodore Ts'oaf41fd02018-07-14 23:55:57 -04001910 for (b = bytes ; b > 0 ; b -= sizeof(__u32), i++) {
1911 if (!arch_get_random_int(&t))
1912 break;
1913 buf[i] ^= t;
1914 }
1915
Matt Mackall7f397dc2007-05-29 21:58:10 -05001916 count -= bytes;
1917 p += bytes;
1918
Theodore Ts'o85608f82014-06-10 23:09:20 -04001919 mix_pool_bytes(r, buf, bytes);
Matt Mackall91f3f1e2008-02-06 01:37:20 -08001920 cond_resched();
Matt Mackall7f397dc2007-05-29 21:58:10 -05001921 }
1922
1923 return 0;
1924}
1925
Matt Mackall90b75ee2008-04-29 01:02:55 -07001926static ssize_t random_write(struct file *file, const char __user *buffer,
1927 size_t count, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001928{
Matt Mackall7f397dc2007-05-29 21:58:10 -05001929 size_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001930
Theodore Ts'oe192be92016-06-12 18:13:36 -04001931 ret = write_pool(&input_pool, buffer, count);
Matt Mackall7f397dc2007-05-29 21:58:10 -05001932 if (ret)
1933 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001934
Matt Mackall7f397dc2007-05-29 21:58:10 -05001935 return (ssize_t)count;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001936}
1937
Matt Mackall43ae4862008-04-29 01:02:58 -07001938static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001939{
1940 int size, ent_count;
1941 int __user *p = (int __user *)arg;
1942 int retval;
1943
1944 switch (cmd) {
1945 case RNDGETENTCNT:
Matt Mackall43ae4862008-04-29 01:02:58 -07001946 /* inherently racy, no point locking */
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001947 ent_count = ENTROPY_BITS(&input_pool);
1948 if (put_user(ent_count, p))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001949 return -EFAULT;
1950 return 0;
1951 case RNDADDTOENTCNT:
1952 if (!capable(CAP_SYS_ADMIN))
1953 return -EPERM;
1954 if (get_user(ent_count, p))
1955 return -EFAULT;
Theodore Ts'o86a574d2016-07-03 17:01:26 -04001956 return credit_entropy_bits_safe(&input_pool, ent_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001957 case RNDADDENTROPY:
1958 if (!capable(CAP_SYS_ADMIN))
1959 return -EPERM;
1960 if (get_user(ent_count, p++))
1961 return -EFAULT;
1962 if (ent_count < 0)
1963 return -EINVAL;
1964 if (get_user(size, p++))
1965 return -EFAULT;
Matt Mackall7f397dc2007-05-29 21:58:10 -05001966 retval = write_pool(&input_pool, (const char __user *)p,
1967 size);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001968 if (retval < 0)
1969 return retval;
Theodore Ts'o86a574d2016-07-03 17:01:26 -04001970 return credit_entropy_bits_safe(&input_pool, ent_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001971 case RNDZAPENTCNT:
1972 case RNDCLEARPOOL:
Theodore Ts'oae9ecd92013-11-03 07:56:17 -05001973 /*
1974 * Clear the entropy pool counters. We no longer clear
1975 * the entropy pool, as that's silly.
1976 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001977 if (!capable(CAP_SYS_ADMIN))
1978 return -EPERM;
Theodore Ts'oae9ecd92013-11-03 07:56:17 -05001979 input_pool.entropy_count = 0;
Theodore Ts'oae9ecd92013-11-03 07:56:17 -05001980 blocking_pool.entropy_count = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001981 return 0;
Theodore Ts'o90936d92018-04-11 16:32:17 -04001982 case RNDRESEEDCRNG:
1983 if (!capable(CAP_SYS_ADMIN))
1984 return -EPERM;
1985 if (crng_init < 2)
1986 return -ENODATA;
1987 crng_reseed(&primary_crng, NULL);
1988 crng_global_init_time = jiffies - 1;
1989 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001990 default:
1991 return -EINVAL;
1992 }
1993}
1994
Jeff Dike9a6f70b2008-04-29 01:03:08 -07001995static int random_fasync(int fd, struct file *filp, int on)
1996{
1997 return fasync_helper(fd, filp, on, &fasync);
1998}
1999
Arjan van de Ven2b8693c2007-02-12 00:55:32 -08002000const struct file_operations random_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002001 .read = random_read,
2002 .write = random_write,
2003 .poll = random_poll,
Matt Mackall43ae4862008-04-29 01:02:58 -07002004 .unlocked_ioctl = random_ioctl,
Jeff Dike9a6f70b2008-04-29 01:03:08 -07002005 .fasync = random_fasync,
Arnd Bergmann6038f372010-08-15 18:52:59 +02002006 .llseek = noop_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002007};
2008
Arjan van de Ven2b8693c2007-02-12 00:55:32 -08002009const struct file_operations urandom_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002010 .read = urandom_read,
2011 .write = random_write,
Matt Mackall43ae4862008-04-29 01:02:58 -07002012 .unlocked_ioctl = random_ioctl,
Jeff Dike9a6f70b2008-04-29 01:03:08 -07002013 .fasync = random_fasync,
Arnd Bergmann6038f372010-08-15 18:52:59 +02002014 .llseek = noop_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002015};
2016
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04002017SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
2018 unsigned int, flags)
2019{
Jason A. Donenfelde297a782017-06-07 19:58:56 -04002020 int ret;
2021
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04002022 if (flags & ~(GRND_NONBLOCK|GRND_RANDOM))
2023 return -EINVAL;
2024
2025 if (count > INT_MAX)
2026 count = INT_MAX;
2027
2028 if (flags & GRND_RANDOM)
2029 return _random_read(flags & GRND_NONBLOCK, buf, count);
2030
Theodore Ts'oe192be92016-06-12 18:13:36 -04002031 if (!crng_ready()) {
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04002032 if (flags & GRND_NONBLOCK)
2033 return -EAGAIN;
Jason A. Donenfelde297a782017-06-07 19:58:56 -04002034 ret = wait_for_random_bytes();
2035 if (unlikely(ret))
2036 return ret;
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04002037 }
2038 return urandom_read(NULL, buf, count, NULL);
2039}
2040
Linus Torvalds1da177e2005-04-16 15:20:36 -07002041/********************************************************************
2042 *
2043 * Sysctl interface
2044 *
2045 ********************************************************************/
2046
2047#ifdef CONFIG_SYSCTL
2048
2049#include <linux/sysctl.h>
2050
2051static int min_read_thresh = 8, min_write_thresh;
Greg Price8c2aa332013-12-05 19:19:29 -05002052static int max_read_thresh = OUTPUT_POOL_WORDS * 32;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002053static int max_write_thresh = INPUT_POOL_WORDS * 32;
Fabio Estevamdb61ffe2017-01-31 14:36:07 -02002054static int random_min_urandom_seed = 60;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002055static char sysctl_bootid[16];
2056
2057/*
Greg Pricef22052b2013-11-29 14:58:16 -05002058 * This function is used to return both the bootid UUID, and random
Linus Torvalds1da177e2005-04-16 15:20:36 -07002059 * UUID. The difference is in whether table->data is NULL; if it is,
2060 * then a new UUID is generated and returned to the user.
2061 *
Greg Pricef22052b2013-11-29 14:58:16 -05002062 * If the user accesses this via the proc interface, the UUID will be
2063 * returned as an ASCII string in the standard UUID format; if via the
2064 * sysctl system call, as 16 bytes of binary data.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002065 */
Joe Perchesa1514272013-06-13 19:37:35 -07002066static int proc_do_uuid(struct ctl_table *table, int write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002067 void __user *buffer, size_t *lenp, loff_t *ppos)
2068{
Joe Perchesa1514272013-06-13 19:37:35 -07002069 struct ctl_table fake_table;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070 unsigned char buf[64], tmp_uuid[16], *uuid;
2071
2072 uuid = table->data;
2073 if (!uuid) {
2074 uuid = tmp_uuid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002075 generate_random_uuid(uuid);
Mathieu Desnoyers44e43602012-04-12 12:49:12 -07002076 } else {
2077 static DEFINE_SPINLOCK(bootid_spinlock);
2078
2079 spin_lock(&bootid_spinlock);
2080 if (!uuid[8])
2081 generate_random_uuid(uuid);
2082 spin_unlock(&bootid_spinlock);
2083 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002084
Joe Perches35900772009-12-14 18:01:11 -08002085 sprintf(buf, "%pU", uuid);
2086
Linus Torvalds1da177e2005-04-16 15:20:36 -07002087 fake_table.data = buf;
2088 fake_table.maxlen = sizeof(buf);
2089
Alexey Dobriyan8d65af72009-09-23 15:57:19 -07002090 return proc_dostring(&fake_table, write, buffer, lenp, ppos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002091}
2092
H. Peter Anvina283b5c2013-09-10 23:16:17 -04002093/*
2094 * Return entropy available scaled to integral bits
2095 */
Joe Perches5eb10d92014-06-06 14:37:58 -07002096static int proc_do_entropy(struct ctl_table *table, int write,
H. Peter Anvina283b5c2013-09-10 23:16:17 -04002097 void __user *buffer, size_t *lenp, loff_t *ppos)
2098{
Joe Perches5eb10d92014-06-06 14:37:58 -07002099 struct ctl_table fake_table;
H. Peter Anvina283b5c2013-09-10 23:16:17 -04002100 int entropy_count;
2101
2102 entropy_count = *(int *)table->data >> ENTROPY_SHIFT;
2103
2104 fake_table.data = &entropy_count;
2105 fake_table.maxlen = sizeof(entropy_count);
2106
2107 return proc_dointvec(&fake_table, write, buffer, lenp, ppos);
2108}
2109
Linus Torvalds1da177e2005-04-16 15:20:36 -07002110static int sysctl_poolsize = INPUT_POOL_WORDS * 32;
Joe Perchesa1514272013-06-13 19:37:35 -07002111extern struct ctl_table random_table[];
2112struct ctl_table random_table[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002114 .procname = "poolsize",
2115 .data = &sysctl_poolsize,
2116 .maxlen = sizeof(int),
2117 .mode = 0444,
Eric W. Biederman6d456112009-11-16 03:11:48 -08002118 .proc_handler = proc_dointvec,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002119 },
2120 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002121 .procname = "entropy_avail",
2122 .maxlen = sizeof(int),
2123 .mode = 0444,
H. Peter Anvina283b5c2013-09-10 23:16:17 -04002124 .proc_handler = proc_do_entropy,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002125 .data = &input_pool.entropy_count,
2126 },
2127 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002128 .procname = "read_wakeup_threshold",
Greg Price2132a962013-12-06 21:28:03 -05002129 .data = &random_read_wakeup_bits,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002130 .maxlen = sizeof(int),
2131 .mode = 0644,
Eric W. Biederman6d456112009-11-16 03:11:48 -08002132 .proc_handler = proc_dointvec_minmax,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002133 .extra1 = &min_read_thresh,
2134 .extra2 = &max_read_thresh,
2135 },
2136 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002137 .procname = "write_wakeup_threshold",
Greg Price2132a962013-12-06 21:28:03 -05002138 .data = &random_write_wakeup_bits,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002139 .maxlen = sizeof(int),
2140 .mode = 0644,
Eric W. Biederman6d456112009-11-16 03:11:48 -08002141 .proc_handler = proc_dointvec_minmax,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002142 .extra1 = &min_write_thresh,
2143 .extra2 = &max_write_thresh,
2144 },
2145 {
Theodore Ts'of5c27422013-09-22 15:14:32 -04002146 .procname = "urandom_min_reseed_secs",
2147 .data = &random_min_urandom_seed,
2148 .maxlen = sizeof(int),
2149 .mode = 0644,
2150 .proc_handler = proc_dointvec,
2151 },
2152 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153 .procname = "boot_id",
2154 .data = &sysctl_bootid,
2155 .maxlen = 16,
2156 .mode = 0444,
Eric W. Biederman6d456112009-11-16 03:11:48 -08002157 .proc_handler = proc_do_uuid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002158 },
2159 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002160 .procname = "uuid",
2161 .maxlen = 16,
2162 .mode = 0444,
Eric W. Biederman6d456112009-11-16 03:11:48 -08002163 .proc_handler = proc_do_uuid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002164 },
Theodore Ts'o43759d42014-06-14 21:43:13 -04002165#ifdef ADD_INTERRUPT_BENCH
2166 {
2167 .procname = "add_interrupt_avg_cycles",
2168 .data = &avg_cycles,
2169 .maxlen = sizeof(avg_cycles),
2170 .mode = 0444,
2171 .proc_handler = proc_doulongvec_minmax,
2172 },
2173 {
2174 .procname = "add_interrupt_avg_deviation",
2175 .data = &avg_deviation,
2176 .maxlen = sizeof(avg_deviation),
2177 .mode = 0444,
2178 .proc_handler = proc_doulongvec_minmax,
2179 },
2180#endif
Eric W. Biederman894d2492009-11-05 14:34:02 -08002181 { }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002182};
2183#endif /* CONFIG_SYSCTL */
2184
Jason A. Donenfeldf5b98462017-01-06 19:32:01 +01002185struct batched_entropy {
2186 union {
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002187 u64 entropy_u64[CHACHA20_BLOCK_SIZE / sizeof(u64)];
2188 u32 entropy_u32[CHACHA20_BLOCK_SIZE / sizeof(u32)];
Jason A. Donenfeldf5b98462017-01-06 19:32:01 +01002189 };
2190 unsigned int position;
2191};
Jason A. Donenfeldb169c132017-06-07 19:45:31 -04002192static rwlock_t batched_entropy_reset_lock = __RW_LOCK_UNLOCKED(batched_entropy_reset_lock);
Eric Biggersb1132dea2016-05-04 21:08:39 -04002193
Linus Torvalds1da177e2005-04-16 15:20:36 -07002194/*
Jason A. Donenfeldf5b98462017-01-06 19:32:01 +01002195 * Get a random word for internal kernel use only. The quality of the random
2196 * number is either as good as RDRAND or as good as /dev/urandom, with the
Jason A. Donenfelde297a782017-06-07 19:58:56 -04002197 * goal of being quite fast and not depleting entropy. In order to ensure
2198 * that the randomness provided by this function is okay, the function
2199 * wait_for_random_bytes() should be called and return 0 at least once
2200 * at any point prior.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002201 */
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002202static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64);
2203u64 get_random_u64(void)
Daniel Cashmanec9ee4a2016-02-26 15:19:34 -08002204{
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002205 u64 ret;
Sebastian Andrzej Siewior72e5c742017-06-30 16:37:13 +02002206 bool use_lock;
Jason A. Donenfeld4a072c72017-06-15 00:45:26 +02002207 unsigned long flags = 0;
Jason A. Donenfeldf5b98462017-01-06 19:32:01 +01002208 struct batched_entropy *batch;
Theodore Ts'oeecabf52017-06-08 04:16:59 -04002209 static void *previous;
Daniel Cashmanec9ee4a2016-02-26 15:19:34 -08002210
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002211#if BITS_PER_LONG == 64
2212 if (arch_get_random_long((unsigned long *)&ret))
Daniel Cashmanec9ee4a2016-02-26 15:19:34 -08002213 return ret;
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002214#else
2215 if (arch_get_random_long((unsigned long *)&ret) &&
2216 arch_get_random_long((unsigned long *)&ret + 1))
2217 return ret;
2218#endif
Daniel Cashmanec9ee4a2016-02-26 15:19:34 -08002219
Theodore Ts'oeecabf52017-06-08 04:16:59 -04002220 warn_unseeded_randomness(&previous);
Jason A. Donenfeldd06bfd12017-06-07 23:06:55 -04002221
Sebastian Andrzej Siewior72e5c742017-06-30 16:37:13 +02002222 use_lock = READ_ONCE(crng_init) < 2;
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002223 batch = &get_cpu_var(batched_entropy_u64);
Jason A. Donenfeldb169c132017-06-07 19:45:31 -04002224 if (use_lock)
2225 read_lock_irqsave(&batched_entropy_reset_lock, flags);
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002226 if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) {
2227 extract_crng((u8 *)batch->entropy_u64);
Jason A. Donenfeldf5b98462017-01-06 19:32:01 +01002228 batch->position = 0;
2229 }
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002230 ret = batch->entropy_u64[batch->position++];
Jason A. Donenfeldb169c132017-06-07 19:45:31 -04002231 if (use_lock)
2232 read_unlock_irqrestore(&batched_entropy_reset_lock, flags);
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002233 put_cpu_var(batched_entropy_u64);
Daniel Cashmanec9ee4a2016-02-26 15:19:34 -08002234 return ret;
2235}
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002236EXPORT_SYMBOL(get_random_u64);
Daniel Cashmanec9ee4a2016-02-26 15:19:34 -08002237
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002238static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32);
2239u32 get_random_u32(void)
Jason A. Donenfeldf5b98462017-01-06 19:32:01 +01002240{
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002241 u32 ret;
Sebastian Andrzej Siewior72e5c742017-06-30 16:37:13 +02002242 bool use_lock;
Jason A. Donenfeld4a072c72017-06-15 00:45:26 +02002243 unsigned long flags = 0;
Jason A. Donenfeldf5b98462017-01-06 19:32:01 +01002244 struct batched_entropy *batch;
Theodore Ts'oeecabf52017-06-08 04:16:59 -04002245 static void *previous;
Jason A. Donenfeldf5b98462017-01-06 19:32:01 +01002246
2247 if (arch_get_random_int(&ret))
2248 return ret;
2249
Theodore Ts'oeecabf52017-06-08 04:16:59 -04002250 warn_unseeded_randomness(&previous);
Jason A. Donenfeldd06bfd12017-06-07 23:06:55 -04002251
Sebastian Andrzej Siewior72e5c742017-06-30 16:37:13 +02002252 use_lock = READ_ONCE(crng_init) < 2;
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002253 batch = &get_cpu_var(batched_entropy_u32);
Jason A. Donenfeldb169c132017-06-07 19:45:31 -04002254 if (use_lock)
2255 read_lock_irqsave(&batched_entropy_reset_lock, flags);
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002256 if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) {
2257 extract_crng((u8 *)batch->entropy_u32);
Jason A. Donenfeldf5b98462017-01-06 19:32:01 +01002258 batch->position = 0;
2259 }
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002260 ret = batch->entropy_u32[batch->position++];
Jason A. Donenfeldb169c132017-06-07 19:45:31 -04002261 if (use_lock)
2262 read_unlock_irqrestore(&batched_entropy_reset_lock, flags);
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002263 put_cpu_var(batched_entropy_u32);
Jason A. Donenfeldf5b98462017-01-06 19:32:01 +01002264 return ret;
2265}
Jason A. Donenfeldc4404082017-01-22 16:34:08 +01002266EXPORT_SYMBOL(get_random_u32);
Jason A. Donenfeldf5b98462017-01-06 19:32:01 +01002267
Jason A. Donenfeldb169c132017-06-07 19:45:31 -04002268/* It's important to invalidate all potential batched entropy that might
2269 * be stored before the crng is initialized, which we can do lazily by
2270 * simply resetting the counter to zero so that it's re-extracted on the
2271 * next usage. */
2272static void invalidate_batched_entropy(void)
2273{
2274 int cpu;
2275 unsigned long flags;
2276
2277 write_lock_irqsave(&batched_entropy_reset_lock, flags);
2278 for_each_possible_cpu (cpu) {
2279 per_cpu_ptr(&batched_entropy_u32, cpu)->position = 0;
2280 per_cpu_ptr(&batched_entropy_u64, cpu)->position = 0;
2281 }
2282 write_unlock_irqrestore(&batched_entropy_reset_lock, flags);
2283}
2284
Jason Cooper99fdafd2016-10-11 13:53:52 -07002285/**
2286 * randomize_page - Generate a random, page aligned address
2287 * @start: The smallest acceptable address the caller will take.
2288 * @range: The size of the area, starting at @start, within which the
2289 * random address must fall.
2290 *
2291 * If @start + @range would overflow, @range is capped.
2292 *
2293 * NOTE: Historical use of randomize_range, which this replaces, presumed that
2294 * @start was already page aligned. We now align it regardless.
2295 *
2296 * Return: A page aligned address within [start, start + range). On error,
2297 * @start is returned.
2298 */
2299unsigned long
2300randomize_page(unsigned long start, unsigned long range)
2301{
2302 if (!PAGE_ALIGNED(start)) {
2303 range -= PAGE_ALIGN(start) - start;
2304 start = PAGE_ALIGN(start);
2305 }
2306
2307 if (start > ULONG_MAX - range)
2308 range = ULONG_MAX - start;
2309
2310 range >>= PAGE_SHIFT;
2311
2312 if (range == 0)
2313 return start;
2314
2315 return start + (get_random_long() % range << PAGE_SHIFT);
2316}
2317
Torsten Duwec84dbf62014-06-14 23:38:36 -04002318/* Interface for in-kernel drivers of true hardware RNGs.
2319 * Those devices may produce endless random bits and will be throttled
2320 * when our pool is full.
2321 */
2322void add_hwgenerator_randomness(const char *buffer, size_t count,
2323 size_t entropy)
2324{
2325 struct entropy_store *poolp = &input_pool;
2326
Theodore Ts'o6e513bc2018-04-11 13:27:52 -04002327 if (unlikely(crng_init == 0)) {
Theodore Ts'oe192be92016-06-12 18:13:36 -04002328 crng_fast_load(buffer, count);
2329 return;
Theodore Ts'o3371f3d2016-06-12 18:11:51 -04002330 }
Theodore Ts'oe192be92016-06-12 18:13:36 -04002331
2332 /* Suspend writing if we're above the trickle threshold.
2333 * We'll be woken up again once below random_write_wakeup_thresh,
2334 * or when the calling thread is about to terminate.
2335 */
2336 wait_event_interruptible(random_write_wait, kthread_should_stop() ||
2337 ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits);
Torsten Duwec84dbf62014-06-14 23:38:36 -04002338 mix_pool_bytes(poolp, buffer, count);
2339 credit_entropy_bits(poolp, entropy);
2340}
2341EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);