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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * random.c -- A strong random number generator
3 *
Matt Mackall9e95ce22005-04-16 15:25:56 -07004 * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 *
6 * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All
7 * rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, and the entire permission notice in its entirety,
14 * including the disclaimer of warranties.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. The name of the author may not be used to endorse or promote
19 * products derived from this software without specific prior
20 * written permission.
21 *
22 * ALTERNATIVELY, this product may be distributed under the terms of
23 * the GNU General Public License, in which case the provisions of the GPL are
24 * required INSTEAD OF the above restrictions. (This clause is
25 * necessary due to a potential bad interaction between the GPL and
26 * the restrictions contained in a BSD-style copyright.)
27 *
28 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
29 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
30 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
31 * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
32 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
33 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
34 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
35 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
36 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
38 * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
39 * DAMAGE.
40 */
41
42/*
43 * (now, with legal B.S. out of the way.....)
44 *
45 * This routine gathers environmental noise from device drivers, etc.,
46 * and returns good random numbers, suitable for cryptographic use.
47 * Besides the obvious cryptographic uses, these numbers are also good
48 * for seeding TCP sequence numbers, and other places where it is
49 * desirable to have numbers which are not only random, but hard to
50 * predict by an attacker.
51 *
52 * Theory of operation
53 * ===================
54 *
55 * Computers are very predictable devices. Hence it is extremely hard
56 * to produce truly random numbers on a computer --- as opposed to
57 * pseudo-random numbers, which can easily generated by using a
58 * algorithm. Unfortunately, it is very easy for attackers to guess
59 * the sequence of pseudo-random number generators, and for some
60 * applications this is not acceptable. So instead, we must try to
61 * gather "environmental noise" from the computer's environment, which
62 * must be hard for outside attackers to observe, and use that to
63 * generate random numbers. In a Unix environment, this is best done
64 * from inside the kernel.
65 *
66 * Sources of randomness from the environment include inter-keyboard
67 * timings, inter-interrupt timings from some interrupts, and other
68 * events which are both (a) non-deterministic and (b) hard for an
69 * outside observer to measure. Randomness from these sources are
70 * added to an "entropy pool", which is mixed using a CRC-like function.
71 * This is not cryptographically strong, but it is adequate assuming
72 * the randomness is not chosen maliciously, and it is fast enough that
73 * the overhead of doing it on every interrupt is very reasonable.
74 * As random bytes are mixed into the entropy pool, the routines keep
75 * an *estimate* of how many bits of randomness have been stored into
76 * the random number generator's internal state.
77 *
78 * When random bytes are desired, they are obtained by taking the SHA
79 * hash of the contents of the "entropy pool". The SHA hash avoids
80 * exposing the internal state of the entropy pool. It is believed to
81 * be computationally infeasible to derive any useful information
82 * about the input of SHA from its output. Even if it is possible to
83 * analyze SHA in some clever way, as long as the amount of data
84 * returned from the generator is less than the inherent entropy in
85 * the pool, the output data is totally unpredictable. For this
86 * reason, the routine decreases its internal estimate of how many
87 * bits of "true randomness" are contained in the entropy pool as it
88 * outputs random numbers.
89 *
90 * If this estimate goes to zero, the routine can still generate
91 * random numbers; however, an attacker may (at least in theory) be
92 * able to infer the future output of the generator from prior
93 * outputs. This requires successful cryptanalysis of SHA, which is
94 * not believed to be feasible, but there is a remote possibility.
95 * Nonetheless, these numbers should be useful for the vast majority
96 * of purposes.
97 *
98 * Exported interfaces ---- output
99 * ===============================
100 *
101 * There are three exported interfaces; the first is one designed to
102 * be used from within the kernel:
103 *
104 * void get_random_bytes(void *buf, int nbytes);
105 *
106 * This interface will return the requested number of random bytes,
107 * and place it in the requested buffer.
108 *
109 * The two other interfaces are two character devices /dev/random and
110 * /dev/urandom. /dev/random is suitable for use when very high
111 * quality randomness is desired (for example, for key generation or
112 * one-time pads), as it will only return a maximum of the number of
113 * bits of randomness (as estimated by the random number generator)
114 * contained in the entropy pool.
115 *
116 * The /dev/urandom device does not have this limit, and will return
117 * as many bytes as are requested. As more and more random bytes are
118 * requested without giving time for the entropy pool to recharge,
119 * this will result in random numbers that are merely cryptographically
120 * strong. For many applications, however, this is acceptable.
121 *
122 * Exported interfaces ---- input
123 * ==============================
124 *
125 * The current exported interfaces for gathering environmental noise
126 * from the devices are:
127 *
Linus Torvaldsa2080a62012-07-04 11:16:01 -0400128 * void add_device_randomness(const void *buf, unsigned int size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 * void add_input_randomness(unsigned int type, unsigned int code,
130 * unsigned int value);
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400131 * void add_interrupt_randomness(int irq, int irq_flags);
Jarod Wilson442a4ff2011-02-21 21:43:10 +1100132 * void add_disk_randomness(struct gendisk *disk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 *
Linus Torvaldsa2080a62012-07-04 11:16:01 -0400134 * add_device_randomness() is for adding data to the random pool that
135 * is likely to differ between two devices (or possibly even per boot).
136 * This would be things like MAC addresses or serial numbers, or the
137 * read-out of the RTC. This does *not* add any actual entropy to the
138 * pool, but it initializes the pool to different values for devices
139 * that might otherwise be identical and have very little entropy
140 * available to them (particularly common in the embedded world).
141 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 * add_input_randomness() uses the input layer interrupt timing, as well as
143 * the event type information from the hardware.
144 *
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400145 * add_interrupt_randomness() uses the interrupt timing as random
146 * inputs to the entropy pool. Using the cycle counters and the irq source
147 * as inputs, it feeds the randomness roughly once a second.
Jarod Wilson442a4ff2011-02-21 21:43:10 +1100148 *
149 * add_disk_randomness() uses what amounts to the seek time of block
150 * layer request events, on a per-disk_devt basis, as input to the
151 * entropy pool. Note that high-speed solid state drives with very low
152 * seek times do not make for good sources of entropy, as their seek
153 * times are usually fairly consistent.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 *
155 * All of these routines try to estimate how many bits of randomness a
156 * particular randomness source. They do this by keeping track of the
157 * first and second order deltas of the event timings.
158 *
159 * Ensuring unpredictability at system startup
160 * ============================================
161 *
162 * When any operating system starts up, it will go through a sequence
163 * of actions that are fairly predictable by an adversary, especially
164 * if the start-up does not involve interaction with a human operator.
165 * This reduces the actual number of bits of unpredictability in the
166 * entropy pool below the value in entropy_count. In order to
167 * counteract this effect, it helps to carry information in the
168 * entropy pool across shut-downs and start-ups. To do this, put the
169 * following lines an appropriate script which is run during the boot
170 * sequence:
171 *
172 * echo "Initializing random number generator..."
173 * random_seed=/var/run/random-seed
174 * # Carry a random seed from start-up to start-up
175 * # Load and then save the whole entropy pool
176 * if [ -f $random_seed ]; then
177 * cat $random_seed >/dev/urandom
178 * else
179 * touch $random_seed
180 * fi
181 * chmod 600 $random_seed
182 * dd if=/dev/urandom of=$random_seed count=1 bs=512
183 *
184 * and the following lines in an appropriate script which is run as
185 * the system is shutdown:
186 *
187 * # Carry a random seed from shut-down to start-up
188 * # Save the whole entropy pool
189 * echo "Saving random seed..."
190 * random_seed=/var/run/random-seed
191 * touch $random_seed
192 * chmod 600 $random_seed
193 * dd if=/dev/urandom of=$random_seed count=1 bs=512
194 *
195 * For example, on most modern systems using the System V init
196 * scripts, such code fragments would be found in
197 * /etc/rc.d/init.d/random. On older Linux systems, the correct script
198 * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0.
199 *
200 * Effectively, these commands cause the contents of the entropy pool
201 * to be saved at shut-down time and reloaded into the entropy pool at
202 * start-up. (The 'dd' in the addition to the bootup script is to
203 * make sure that /etc/random-seed is different for every start-up,
204 * even if the system crashes without executing rc.0.) Even with
205 * complete knowledge of the start-up activities, predicting the state
206 * of the entropy pool requires knowledge of the previous history of
207 * the system.
208 *
209 * Configuring the /dev/random driver under Linux
210 * ==============================================
211 *
212 * The /dev/random driver under Linux uses minor numbers 8 and 9 of
213 * the /dev/mem major number (#1). So if your system does not have
214 * /dev/random and /dev/urandom created already, they can be created
215 * by using the commands:
216 *
217 * mknod /dev/random c 1 8
218 * mknod /dev/urandom c 1 9
219 *
220 * Acknowledgements:
221 * =================
222 *
223 * Ideas for constructing this random number generator were derived
224 * from Pretty Good Privacy's random number generator, and from private
225 * discussions with Phil Karn. Colin Plumb provided a faster random
226 * number generator, which speed up the mixing function of the entropy
227 * pool, taken from PGPfone. Dale Worley has also contributed many
228 * useful ideas and suggestions to improve this driver.
229 *
230 * Any flaws in the design are solely my responsibility, and should
231 * not be attributed to the Phil, Colin, or any of authors of PGP.
232 *
233 * Further background information on this topic may be obtained from
234 * RFC 1750, "Randomness Recommendations for Security", by Donald
235 * Eastlake, Steve Crocker, and Jeff Schiller.
236 */
237
238#include <linux/utsname.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239#include <linux/module.h>
240#include <linux/kernel.h>
241#include <linux/major.h>
242#include <linux/string.h>
243#include <linux/fcntl.h>
244#include <linux/slab.h>
245#include <linux/random.h>
246#include <linux/poll.h>
247#include <linux/init.h>
248#include <linux/fs.h>
249#include <linux/genhd.h>
250#include <linux/interrupt.h>
Andrea Righi27ac7922008-07-23 21:28:13 -0700251#include <linux/mm.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252#include <linux/spinlock.h>
Torsten Duwec84dbf62014-06-14 23:38:36 -0400253#include <linux/kthread.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254#include <linux/percpu.h>
255#include <linux/cryptohash.h>
Neil Horman5b739ef2009-06-18 19:50:21 +0800256#include <linux/fips.h>
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400257#include <linux/ptrace.h>
Theodore Ts'oe6d49472012-07-05 10:21:01 -0400258#include <linux/kmemcheck.h>
Theodore Ts'o6265e162013-10-03 01:08:15 -0400259#include <linux/workqueue.h>
Martin Schwidefsky0244ad02013-08-30 09:39:53 +0200260#include <linux/irq.h>
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -0400261#include <linux/syscalls.h>
262#include <linux/completion.h>
Yinghai Lud178a1e2009-01-11 00:35:42 -0800263
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264#include <asm/processor.h>
265#include <asm/uaccess.h>
266#include <asm/irq.h>
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400267#include <asm/irq_regs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268#include <asm/io.h>
269
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400270#define CREATE_TRACE_POINTS
271#include <trace/events/random.h>
272
Theodore Ts'o43759d42014-06-14 21:43:13 -0400273/* #define ADD_INTERRUPT_BENCH */
274
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275/*
276 * Configuration information
277 */
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400278#define INPUT_POOL_SHIFT 12
279#define INPUT_POOL_WORDS (1 << (INPUT_POOL_SHIFT-5))
280#define OUTPUT_POOL_SHIFT 10
281#define OUTPUT_POOL_WORDS (1 << (OUTPUT_POOL_SHIFT-5))
282#define SEC_XFER_SIZE 512
283#define EXTRACT_SIZE 10
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284
Theodore Ts'o392a5462013-11-03 18:24:08 -0500285#define DEBUG_RANDOM_BOOT 0
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286
H. Peter Anvind2e7c962012-07-27 22:26:08 -0400287#define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long))
288
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289/*
Theodore Ts'o95b709b2013-10-02 21:10:35 -0400290 * To allow fractional bits to be tracked, the entropy_count field is
291 * denominated in units of 1/8th bits.
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400292 *
293 * 2*(ENTROPY_SHIFT + log2(poolbits)) must <= 31, or the multiply in
294 * credit_entropy_bits() needs to be 64 bits wide.
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400295 */
296#define ENTROPY_SHIFT 3
297#define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT)
298
299/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 * The minimum number of bits of entropy before we wake up a read on
301 * /dev/random. Should be enough to do a significant reseed.
302 */
Greg Price2132a962013-12-06 21:28:03 -0500303static int random_read_wakeup_bits = 64;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304
305/*
306 * If the entropy count falls under this number of bits, then we
307 * should wake up processes which are selecting or polling on write
308 * access to /dev/random.
309 */
Greg Price2132a962013-12-06 21:28:03 -0500310static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311
312/*
Greg Pricedfd38752013-11-29 14:58:06 -0500313 * The minimum number of seconds between urandom pool reseeding. We
Theodore Ts'of5c27422013-09-22 15:14:32 -0400314 * do this to limit the amount of entropy that can be drained from the
315 * input pool even if there are heavy demands on /dev/urandom.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316 */
Theodore Ts'of5c27422013-09-22 15:14:32 -0400317static int random_min_urandom_seed = 60;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318
319/*
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400320 * Originally, we used a primitive polynomial of degree .poolwords
321 * over GF(2). The taps for various sizes are defined below. They
322 * were chosen to be evenly spaced except for the last tap, which is 1
323 * to get the twisting happening as fast as possible.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 *
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400325 * For the purposes of better mixing, we use the CRC-32 polynomial as
326 * well to make a (modified) twisted Generalized Feedback Shift
327 * Register. (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR
328 * generators. ACM Transactions on Modeling and Computer Simulation
329 * 2(3):179-194. Also see M. Matsumoto & Y. Kurita, 1994. Twisted
Greg Pricedfd38752013-11-29 14:58:06 -0500330 * GFSR generators II. ACM Transactions on Modeling and Computer
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400331 * Simulation 4:254-266)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 *
333 * Thanks to Colin Plumb for suggesting this.
334 *
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400335 * The mixing operation is much less sensitive than the output hash,
336 * where we use SHA-1. All that we want of mixing operation is that
337 * it be a good non-cryptographic hash; i.e. it not produce collisions
338 * when fed "random" data of the sort we expect to see. As long as
339 * the pool state differs for different inputs, we have preserved the
340 * input entropy and done a good job. The fact that an intelligent
341 * attacker can construct inputs that will produce controlled
342 * alterations to the pool's state is not important because we don't
343 * consider such inputs to contribute any randomness. The only
344 * property we need with respect to them is that the attacker can't
345 * increase his/her knowledge of the pool's state. Since all
346 * additions are reversible (knowing the final state and the input,
347 * you can reconstruct the initial state), if an attacker has any
348 * uncertainty about the initial state, he/she can only shuffle that
349 * uncertainty about, but never cause any collisions (which would
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 * decrease the uncertainty).
351 *
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400352 * Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and
353 * Videau in their paper, "The Linux Pseudorandom Number Generator
354 * Revisited" (see: http://eprint.iacr.org/2012/251.pdf). In their
355 * paper, they point out that we are not using a true Twisted GFSR,
356 * since Matsumoto & Kurita used a trinomial feedback polynomial (that
357 * is, with only three taps, instead of the six that we are using).
358 * As a result, the resulting polynomial is neither primitive nor
359 * irreducible, and hence does not have a maximal period over
360 * GF(2**32). They suggest a slight change to the generator
361 * polynomial which improves the resulting TGFSR polynomial to be
362 * irreducible, which we have made here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364static struct poolinfo {
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400365 int poolbitshift, poolwords, poolbytes, poolbits, poolfracbits;
366#define S(x) ilog2(x)+5, (x), (x)*4, (x)*32, (x) << (ENTROPY_SHIFT+5)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 int tap1, tap2, tap3, tap4, tap5;
368} poolinfo_table[] = {
Theodore Ts'o6e9fa2c2013-09-22 16:04:19 -0400369 /* was: x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 */
370 /* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */
371 { S(128), 104, 76, 51, 25, 1 },
372 /* was: x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 */
373 /* x^32 + x^26 + x^19 + x^14 + x^7 + x + 1 */
374 { S(32), 26, 19, 14, 7, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375#if 0
376 /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400377 { S(2048), 1638, 1231, 819, 411, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378
379 /* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400380 { S(1024), 817, 615, 412, 204, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381
382 /* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400383 { S(1024), 819, 616, 410, 207, 2 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384
385 /* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400386 { S(512), 411, 308, 208, 104, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387
388 /* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400389 { S(512), 409, 307, 206, 102, 2 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390 /* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400391 { S(512), 409, 309, 205, 103, 2 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392
393 /* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400394 { S(256), 205, 155, 101, 52, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395
396 /* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400397 { S(128), 103, 78, 51, 27, 2 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398
399 /* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */
H. Peter Anvin9ed17b72013-09-10 23:16:17 -0400400 { S(64), 52, 39, 26, 14, 1 },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401#endif
402};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403
404/*
405 * Static global variables
406 */
407static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
408static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -0400409static DECLARE_WAIT_QUEUE_HEAD(urandom_init_wait);
Jeff Dike9a6f70b2008-04-29 01:03:08 -0700410static struct fasync_struct *fasync;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411
Herbert Xu205a5252015-06-09 18:19:39 +0800412static DEFINE_SPINLOCK(random_ready_list_lock);
413static LIST_HEAD(random_ready_list);
414
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415/**********************************************************************
416 *
417 * OS independent entropy store. Here are the functions which handle
418 * storing entropy in an entropy pool.
419 *
420 **********************************************************************/
421
422struct entropy_store;
423struct entropy_store {
Matt Mackall43358202008-04-29 01:03:01 -0700424 /* read-only data: */
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400425 const struct poolinfo *poolinfo;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 __u32 *pool;
427 const char *name;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 struct entropy_store *pull;
Theodore Ts'o6265e162013-10-03 01:08:15 -0400429 struct work_struct push_work;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430
431 /* read-write data: */
Theodore Ts'of5c27422013-09-22 15:14:32 -0400432 unsigned long last_pulled;
Matt Mackall43358202008-04-29 01:03:01 -0700433 spinlock_t lock;
Theodore Ts'oc59974a2013-09-21 19:42:41 -0400434 unsigned short add_ptr;
435 unsigned short input_rotate;
Matt Mackallcda796a2009-01-06 14:42:55 -0800436 int entropy_count;
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400437 int entropy_total;
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400438 unsigned int initialized:1;
Theodore Ts'oc59974a2013-09-21 19:42:41 -0400439 unsigned int limit:1;
440 unsigned int last_data_init:1;
Matt Mackalle954bc92010-05-20 19:55:01 +1000441 __u8 last_data[EXTRACT_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442};
443
Theodore Ts'o6265e162013-10-03 01:08:15 -0400444static void push_to_pool(struct work_struct *work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445static __u32 input_pool_data[INPUT_POOL_WORDS];
446static __u32 blocking_pool_data[OUTPUT_POOL_WORDS];
447static __u32 nonblocking_pool_data[OUTPUT_POOL_WORDS];
448
449static struct entropy_store input_pool = {
450 .poolinfo = &poolinfo_table[0],
451 .name = "input",
452 .limit = 1,
Thomas Gleixnereece09e2011-07-17 21:25:03 +0200453 .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454 .pool = input_pool_data
455};
456
457static struct entropy_store blocking_pool = {
458 .poolinfo = &poolinfo_table[1],
459 .name = "blocking",
460 .limit = 1,
461 .pull = &input_pool,
Thomas Gleixnereece09e2011-07-17 21:25:03 +0200462 .lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock),
Theodore Ts'o6265e162013-10-03 01:08:15 -0400463 .pool = blocking_pool_data,
464 .push_work = __WORK_INITIALIZER(blocking_pool.push_work,
465 push_to_pool),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466};
467
468static struct entropy_store nonblocking_pool = {
469 .poolinfo = &poolinfo_table[1],
470 .name = "nonblocking",
471 .pull = &input_pool,
Thomas Gleixnereece09e2011-07-17 21:25:03 +0200472 .lock = __SPIN_LOCK_UNLOCKED(nonblocking_pool.lock),
Theodore Ts'o6265e162013-10-03 01:08:15 -0400473 .pool = nonblocking_pool_data,
474 .push_work = __WORK_INITIALIZER(nonblocking_pool.push_work,
475 push_to_pool),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476};
477
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400478static __u32 const twist_table[8] = {
479 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
480 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
481
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482/*
Matt Mackalle68e5b62008-04-29 01:03:05 -0700483 * This function adds bytes into the entropy "pool". It does not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484 * update the entropy estimate. The caller should call
Matt Mackalladc782d2008-04-29 01:03:07 -0700485 * credit_entropy_bits if this is appropriate.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486 *
487 * The pool is stirred with a primitive polynomial of the appropriate
488 * degree, and then twisted. We twist by three bits at a time because
489 * it's cheap to do so and helps slightly in the expected case where
490 * the entropy is concentrated in the low-order bits.
491 */
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400492static void _mix_pool_bytes(struct entropy_store *r, const void *in,
Theodore Ts'o85608f82014-06-10 23:09:20 -0400493 int nbytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494{
Theodore Ts'o85608f82014-06-10 23:09:20 -0400495 unsigned long i, tap1, tap2, tap3, tap4, tap5;
Matt Mackallfeee7692008-04-29 01:03:02 -0700496 int input_rotate;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497 int wordmask = r->poolinfo->poolwords - 1;
Matt Mackalle68e5b62008-04-29 01:03:05 -0700498 const char *bytes = in;
Matt Mackall6d38b822008-04-29 01:03:03 -0700499 __u32 w;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501 tap1 = r->poolinfo->tap1;
502 tap2 = r->poolinfo->tap2;
503 tap3 = r->poolinfo->tap3;
504 tap4 = r->poolinfo->tap4;
505 tap5 = r->poolinfo->tap5;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506
Theodore Ts'o91fcb532014-06-10 22:46:37 -0400507 input_rotate = r->input_rotate;
508 i = r->add_ptr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509
Matt Mackalle68e5b62008-04-29 01:03:05 -0700510 /* mix one byte at a time to simplify size handling and churn faster */
511 while (nbytes--) {
Theodore Ts'oc59974a2013-09-21 19:42:41 -0400512 w = rol32(*bytes++, input_rotate);
Matt Mackall993ba212008-04-29 01:03:04 -0700513 i = (i - 1) & wordmask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514
515 /* XOR in the various taps */
Matt Mackall993ba212008-04-29 01:03:04 -0700516 w ^= r->pool[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517 w ^= r->pool[(i + tap1) & wordmask];
518 w ^= r->pool[(i + tap2) & wordmask];
519 w ^= r->pool[(i + tap3) & wordmask];
520 w ^= r->pool[(i + tap4) & wordmask];
521 w ^= r->pool[(i + tap5) & wordmask];
Matt Mackall993ba212008-04-29 01:03:04 -0700522
523 /* Mix the result back in with a twist */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 r->pool[i] = (w >> 3) ^ twist_table[w & 7];
Matt Mackallfeee7692008-04-29 01:03:02 -0700525
526 /*
527 * Normally, we add 7 bits of rotation to the pool.
528 * At the beginning of the pool, add an extra 7 bits
529 * rotation, so that successive passes spread the
530 * input bits across the pool evenly.
531 */
Theodore Ts'oc59974a2013-09-21 19:42:41 -0400532 input_rotate = (input_rotate + (i ? 7 : 14)) & 31;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 }
534
Theodore Ts'o91fcb532014-06-10 22:46:37 -0400535 r->input_rotate = input_rotate;
536 r->add_ptr = i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537}
538
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400539static void __mix_pool_bytes(struct entropy_store *r, const void *in,
Theodore Ts'o85608f82014-06-10 23:09:20 -0400540 int nbytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541{
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400542 trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_);
Theodore Ts'o85608f82014-06-10 23:09:20 -0400543 _mix_pool_bytes(r, in, nbytes);
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400544}
545
546static void mix_pool_bytes(struct entropy_store *r, const void *in,
Theodore Ts'o85608f82014-06-10 23:09:20 -0400547 int nbytes)
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400548{
Theodore Ts'o902c0982012-07-04 10:38:30 -0400549 unsigned long flags;
550
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400551 trace_mix_pool_bytes(r->name, nbytes, _RET_IP_);
Theodore Ts'o902c0982012-07-04 10:38:30 -0400552 spin_lock_irqsave(&r->lock, flags);
Theodore Ts'o85608f82014-06-10 23:09:20 -0400553 _mix_pool_bytes(r, in, nbytes);
Theodore Ts'o902c0982012-07-04 10:38:30 -0400554 spin_unlock_irqrestore(&r->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555}
556
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400557struct fast_pool {
558 __u32 pool[4];
559 unsigned long last;
Theodore Ts'oee3e00e2014-06-15 16:59:24 -0400560 unsigned short reg_idx;
Theodore Ts'o840f9502014-06-14 03:06:57 -0400561 unsigned char count;
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400562};
563
564/*
565 * This is a fast mixing routine used by the interrupt randomness
566 * collector. It's hardcoded for an 128 bit pool and assumes that any
567 * locks that might be needed are taken by the caller.
568 */
Theodore Ts'o43759d42014-06-14 21:43:13 -0400569static void fast_mix(struct fast_pool *f)
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400570{
Theodore Ts'o43759d42014-06-14 21:43:13 -0400571 __u32 a = f->pool[0], b = f->pool[1];
572 __u32 c = f->pool[2], d = f->pool[3];
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400573
Theodore Ts'o43759d42014-06-14 21:43:13 -0400574 a += b; c += d;
George Spelvin19acc772015-02-07 00:32:06 -0500575 b = rol32(b, 6); d = rol32(d, 27);
Theodore Ts'o43759d42014-06-14 21:43:13 -0400576 d ^= a; b ^= c;
Theodore Ts'o655b2262013-09-22 15:24:02 -0400577
Theodore Ts'o43759d42014-06-14 21:43:13 -0400578 a += b; c += d;
George Spelvin19acc772015-02-07 00:32:06 -0500579 b = rol32(b, 16); d = rol32(d, 14);
Theodore Ts'o43759d42014-06-14 21:43:13 -0400580 d ^= a; b ^= c;
581
582 a += b; c += d;
George Spelvin19acc772015-02-07 00:32:06 -0500583 b = rol32(b, 6); d = rol32(d, 27);
Theodore Ts'o43759d42014-06-14 21:43:13 -0400584 d ^= a; b ^= c;
585
586 a += b; c += d;
George Spelvin19acc772015-02-07 00:32:06 -0500587 b = rol32(b, 16); d = rol32(d, 14);
Theodore Ts'o43759d42014-06-14 21:43:13 -0400588 d ^= a; b ^= c;
589
590 f->pool[0] = a; f->pool[1] = b;
591 f->pool[2] = c; f->pool[3] = d;
Theodore Ts'o655b2262013-09-22 15:24:02 -0400592 f->count++;
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400593}
594
Herbert Xu205a5252015-06-09 18:19:39 +0800595static void process_random_ready_list(void)
596{
597 unsigned long flags;
598 struct random_ready_callback *rdy, *tmp;
599
600 spin_lock_irqsave(&random_ready_list_lock, flags);
601 list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) {
602 struct module *owner = rdy->owner;
603
604 list_del_init(&rdy->list);
605 rdy->func(rdy);
606 module_put(owner);
607 }
608 spin_unlock_irqrestore(&random_ready_list_lock, flags);
609}
610
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611/*
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400612 * Credit (or debit) the entropy store with n bits of entropy.
613 * Use credit_entropy_bits_safe() if the value comes from userspace
614 * or otherwise should be checked for extreme values.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615 */
Matt Mackalladc782d2008-04-29 01:03:07 -0700616static void credit_entropy_bits(struct entropy_store *r, int nbits)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617{
Theodore Ts'o902c0982012-07-04 10:38:30 -0400618 int entropy_count, orig;
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400619 const int pool_size = r->poolinfo->poolfracbits;
620 int nfrac = nbits << ENTROPY_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621
Matt Mackalladc782d2008-04-29 01:03:07 -0700622 if (!nbits)
623 return;
624
Theodore Ts'o902c0982012-07-04 10:38:30 -0400625retry:
626 entropy_count = orig = ACCESS_ONCE(r->entropy_count);
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400627 if (nfrac < 0) {
628 /* Debit */
629 entropy_count += nfrac;
630 } else {
631 /*
632 * Credit: we have to account for the possibility of
633 * overwriting already present entropy. Even in the
634 * ideal case of pure Shannon entropy, new contributions
635 * approach the full value asymptotically:
636 *
637 * entropy <- entropy + (pool_size - entropy) *
638 * (1 - exp(-add_entropy/pool_size))
639 *
640 * For add_entropy <= pool_size/2 then
641 * (1 - exp(-add_entropy/pool_size)) >=
642 * (add_entropy/pool_size)*0.7869...
643 * so we can approximate the exponential with
644 * 3/4*add_entropy/pool_size and still be on the
645 * safe side by adding at most pool_size/2 at a time.
646 *
647 * The use of pool_size-2 in the while statement is to
648 * prevent rounding artifacts from making the loop
649 * arbitrarily long; this limits the loop to log2(pool_size)*2
650 * turns no matter how large nbits is.
651 */
652 int pnfrac = nfrac;
653 const int s = r->poolinfo->poolbitshift + ENTROPY_SHIFT + 2;
654 /* The +2 corresponds to the /4 in the denominator */
655
656 do {
657 unsigned int anfrac = min(pnfrac, pool_size/2);
658 unsigned int add =
659 ((pool_size - entropy_count)*anfrac*3) >> s;
660
661 entropy_count += add;
662 pnfrac -= anfrac;
663 } while (unlikely(entropy_count < pool_size-2 && pnfrac));
664 }
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400665
Hannes Frederic Sowa79a84682014-07-18 17:26:41 -0400666 if (unlikely(entropy_count < 0)) {
Theodore Ts'of80bbd82013-10-03 12:02:37 -0400667 pr_warn("random: negative entropy/overflow: pool %s count %d\n",
668 r->name, entropy_count);
669 WARN_ON(1);
Andrew Morton8b76f462008-09-02 14:36:14 -0700670 entropy_count = 0;
H. Peter Anvin30e37ec2013-09-10 23:16:17 -0400671 } else if (entropy_count > pool_size)
672 entropy_count = pool_size;
Theodore Ts'o902c0982012-07-04 10:38:30 -0400673 if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
674 goto retry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675
Theodore Ts'o6265e162013-10-03 01:08:15 -0400676 r->entropy_total += nbits;
Linus Torvalds0891ad82013-11-16 10:19:15 -0800677 if (!r->initialized && r->entropy_total > 128) {
678 r->initialized = 1;
679 r->entropy_total = 0;
680 if (r == &nonblocking_pool) {
681 prandom_reseed_late();
Herbert Xu205a5252015-06-09 18:19:39 +0800682 process_random_ready_list();
Herbert Xu1d9de442015-05-21 16:19:54 +0800683 wake_up_all(&urandom_init_wait);
Linus Torvalds0891ad82013-11-16 10:19:15 -0800684 pr_notice("random: %s pool is initialized\n", r->name);
Hannes Frederic Sowa4af712e2013-11-11 12:20:34 +0100685 }
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400686 }
687
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400688 trace_credit_entropy_bits(r->name, nbits,
689 entropy_count >> ENTROPY_SHIFT,
Theodore Ts'o00ce1db2012-07-04 16:19:30 -0400690 r->entropy_total, _RET_IP_);
691
Theodore Ts'o6265e162013-10-03 01:08:15 -0400692 if (r == &input_pool) {
Greg Price7d1b08c2013-12-07 09:49:55 -0500693 int entropy_bits = entropy_count >> ENTROPY_SHIFT;
Theodore Ts'o6265e162013-10-03 01:08:15 -0400694
695 /* should we wake readers? */
Greg Price2132a962013-12-06 21:28:03 -0500696 if (entropy_bits >= random_read_wakeup_bits) {
Theodore Ts'o6265e162013-10-03 01:08:15 -0400697 wake_up_interruptible(&random_read_wait);
698 kill_fasync(&fasync, SIGIO, POLL_IN);
699 }
700 /* If the input pool is getting full, send some
701 * entropy to the two output pools, flipping back and
702 * forth between them, until the output pools are 75%
703 * full.
704 */
Greg Price2132a962013-12-06 21:28:03 -0500705 if (entropy_bits > random_write_wakeup_bits &&
Theodore Ts'o6265e162013-10-03 01:08:15 -0400706 r->initialized &&
Greg Price2132a962013-12-06 21:28:03 -0500707 r->entropy_total >= 2*random_read_wakeup_bits) {
Theodore Ts'o6265e162013-10-03 01:08:15 -0400708 static struct entropy_store *last = &blocking_pool;
709 struct entropy_store *other = &blocking_pool;
710
711 if (last == &blocking_pool)
712 other = &nonblocking_pool;
713 if (other->entropy_count <=
714 3 * other->poolinfo->poolfracbits / 4)
715 last = other;
716 if (last->entropy_count <=
717 3 * last->poolinfo->poolfracbits / 4) {
718 schedule_work(&last->push_work);
719 r->entropy_total = 0;
720 }
721 }
Jeff Dike9a6f70b2008-04-29 01:03:08 -0700722 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723}
724
H. Peter Anvina283b5c2013-09-10 23:16:17 -0400725static void credit_entropy_bits_safe(struct entropy_store *r, int nbits)
726{
727 const int nbits_max = (int)(~0U >> (ENTROPY_SHIFT + 1));
728
729 /* Cap the value to avoid overflows */
730 nbits = min(nbits, nbits_max);
731 nbits = max(nbits, -nbits_max);
732
733 credit_entropy_bits(r, nbits);
734}
735
Linus Torvalds1da177e2005-04-16 15:20:36 -0700736/*********************************************************************
737 *
738 * Entropy input management
739 *
740 *********************************************************************/
741
742/* There is one of these per entropy source */
743struct timer_rand_state {
744 cycles_t last_time;
Matt Mackall90b75ee2008-04-29 01:02:55 -0700745 long last_delta, last_delta2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746 unsigned dont_count_entropy:1;
747};
748
Theodore Ts'o644008d2013-11-03 16:40:53 -0500749#define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, };
750
Linus Torvaldsa2080a62012-07-04 11:16:01 -0400751/*
752 * Add device- or boot-specific data to the input and nonblocking
753 * pools to help initialize them to unique values.
754 *
755 * None of this adds any entropy, it is meant to avoid the
756 * problem of the nonblocking pool having similar initial state
757 * across largely identical devices.
758 */
759void add_device_randomness(const void *buf, unsigned int size)
760{
Theodore Ts'o61875f32013-09-21 13:58:22 -0400761 unsigned long time = random_get_entropy() ^ jiffies;
Theodore Ts'o3ef4cb22013-09-12 14:27:22 -0400762 unsigned long flags;
Linus Torvaldsa2080a62012-07-04 11:16:01 -0400763
Theodore Ts'o59108952013-09-12 14:10:25 -0400764 trace_add_device_randomness(size, _RET_IP_);
Theodore Ts'o3ef4cb22013-09-12 14:27:22 -0400765 spin_lock_irqsave(&input_pool.lock, flags);
Theodore Ts'o85608f82014-06-10 23:09:20 -0400766 _mix_pool_bytes(&input_pool, buf, size);
767 _mix_pool_bytes(&input_pool, &time, sizeof(time));
Theodore Ts'o3ef4cb22013-09-12 14:27:22 -0400768 spin_unlock_irqrestore(&input_pool.lock, flags);
769
770 spin_lock_irqsave(&nonblocking_pool.lock, flags);
Theodore Ts'o85608f82014-06-10 23:09:20 -0400771 _mix_pool_bytes(&nonblocking_pool, buf, size);
772 _mix_pool_bytes(&nonblocking_pool, &time, sizeof(time));
Theodore Ts'o3ef4cb22013-09-12 14:27:22 -0400773 spin_unlock_irqrestore(&nonblocking_pool.lock, flags);
Linus Torvaldsa2080a62012-07-04 11:16:01 -0400774}
775EXPORT_SYMBOL(add_device_randomness);
776
Theodore Ts'o644008d2013-11-03 16:40:53 -0500777static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE;
Yinghai Lu3060d6f2008-08-19 20:50:08 -0700778
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779/*
780 * This function adds entropy to the entropy "pool" by using timing
781 * delays. It uses the timer_rand_state structure to make an estimate
782 * of how many bits of entropy this call has added to the pool.
783 *
784 * The number "num" is also added to the pool - it should somehow describe
785 * the type of event which just happened. This is currently 0-255 for
786 * keyboard scan codes, and 256 upwards for interrupts.
787 *
788 */
789static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
790{
Theodore Ts'o40db23e2013-11-03 00:15:05 -0400791 struct entropy_store *r;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792 struct {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793 long jiffies;
Linus Torvaldscf833d02011-12-22 11:36:22 -0800794 unsigned cycles;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700795 unsigned num;
796 } sample;
797 long delta, delta2, delta3;
798
799 preempt_disable();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800
801 sample.jiffies = jiffies;
Theodore Ts'o61875f32013-09-21 13:58:22 -0400802 sample.cycles = random_get_entropy();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700803 sample.num = num;
Theodore Ts'o40db23e2013-11-03 00:15:05 -0400804 r = nonblocking_pool.initialized ? &input_pool : &nonblocking_pool;
Theodore Ts'o85608f82014-06-10 23:09:20 -0400805 mix_pool_bytes(r, &sample, sizeof(sample));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806
807 /*
808 * Calculate number of bits of randomness we probably added.
809 * We take into account the first, second and third-order deltas
810 * in order to make our estimate.
811 */
812
813 if (!state->dont_count_entropy) {
814 delta = sample.jiffies - state->last_time;
815 state->last_time = sample.jiffies;
816
817 delta2 = delta - state->last_delta;
818 state->last_delta = delta;
819
820 delta3 = delta2 - state->last_delta2;
821 state->last_delta2 = delta2;
822
823 if (delta < 0)
824 delta = -delta;
825 if (delta2 < 0)
826 delta2 = -delta2;
827 if (delta3 < 0)
828 delta3 = -delta3;
829 if (delta > delta2)
830 delta = delta2;
831 if (delta > delta3)
832 delta = delta3;
833
834 /*
835 * delta is now minimum absolute delta.
836 * Round down by 1 bit on general principles,
837 * and limit entropy entimate to 12 bits.
838 */
Theodore Ts'o40db23e2013-11-03 00:15:05 -0400839 credit_entropy_bits(r, min_t(int, fls(delta>>1), 11));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841 preempt_enable();
842}
843
Stephen Hemmingerd2515752006-01-11 12:17:38 -0800844void add_input_randomness(unsigned int type, unsigned int code,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845 unsigned int value)
846{
847 static unsigned char last_value;
848
849 /* ignore autorepeat and the like */
850 if (value == last_value)
851 return;
852
Linus Torvalds1da177e2005-04-16 15:20:36 -0700853 last_value = value;
854 add_timer_randomness(&input_timer_state,
855 (type << 4) ^ code ^ (code >> 4) ^ value);
Theodore Ts'of80bbd82013-10-03 12:02:37 -0400856 trace_add_input_randomness(ENTROPY_BITS(&input_pool));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857}
Dmitry Torokhov80fc9f52006-10-11 01:43:58 -0400858EXPORT_SYMBOL_GPL(add_input_randomness);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700859
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400860static DEFINE_PER_CPU(struct fast_pool, irq_randomness);
861
Theodore Ts'o43759d42014-06-14 21:43:13 -0400862#ifdef ADD_INTERRUPT_BENCH
863static unsigned long avg_cycles, avg_deviation;
864
865#define AVG_SHIFT 8 /* Exponential average factor k=1/256 */
866#define FIXED_1_2 (1 << (AVG_SHIFT-1))
867
868static void add_interrupt_bench(cycles_t start)
869{
870 long delta = random_get_entropy() - start;
871
872 /* Use a weighted moving average */
873 delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT);
874 avg_cycles += delta;
875 /* And average deviation */
876 delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT);
877 avg_deviation += delta;
878}
879#else
880#define add_interrupt_bench(x)
881#endif
882
Theodore Ts'oee3e00e2014-06-15 16:59:24 -0400883static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
884{
885 __u32 *ptr = (__u32 *) regs;
886
887 if (regs == NULL)
888 return 0;
889 if (f->reg_idx >= sizeof(struct pt_regs) / sizeof(__u32))
890 f->reg_idx = 0;
891 return *(ptr + f->reg_idx++);
892}
893
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400894void add_interrupt_randomness(int irq, int irq_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895{
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400896 struct entropy_store *r;
Christoph Lameter1b2a1a72014-08-17 12:30:29 -0500897 struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400898 struct pt_regs *regs = get_irq_regs();
899 unsigned long now = jiffies;
Theodore Ts'o655b2262013-09-22 15:24:02 -0400900 cycles_t cycles = random_get_entropy();
Theodore Ts'o43759d42014-06-14 21:43:13 -0400901 __u32 c_high, j_high;
Theodore Ts'o655b2262013-09-22 15:24:02 -0400902 __u64 ip;
H. Peter Anvin83664a62014-03-17 16:36:28 -0700903 unsigned long seed;
Theodore Ts'o91fcb532014-06-10 22:46:37 -0400904 int credit = 0;
Yinghai Lu3060d6f2008-08-19 20:50:08 -0700905
Theodore Ts'oee3e00e2014-06-15 16:59:24 -0400906 if (cycles == 0)
907 cycles = get_reg(fast_pool, regs);
Theodore Ts'o655b2262013-09-22 15:24:02 -0400908 c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0;
909 j_high = (sizeof(now) > 4) ? now >> 32 : 0;
Theodore Ts'o43759d42014-06-14 21:43:13 -0400910 fast_pool->pool[0] ^= cycles ^ j_high ^ irq;
911 fast_pool->pool[1] ^= now ^ c_high;
Theodore Ts'o655b2262013-09-22 15:24:02 -0400912 ip = regs ? instruction_pointer(regs) : _RET_IP_;
Theodore Ts'o43759d42014-06-14 21:43:13 -0400913 fast_pool->pool[2] ^= ip;
Theodore Ts'oee3e00e2014-06-15 16:59:24 -0400914 fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 :
915 get_reg(fast_pool, regs);
Yinghai Lu3060d6f2008-08-19 20:50:08 -0700916
Theodore Ts'o43759d42014-06-14 21:43:13 -0400917 fast_mix(fast_pool);
Theodore Ts'o43759d42014-06-14 21:43:13 -0400918 add_interrupt_bench(cycles);
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400919
Theodore Ts'oee3e00e2014-06-15 16:59:24 -0400920 if ((fast_pool->count < 64) &&
921 !time_after(now, fast_pool->last + HZ))
922 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700923
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400924 r = nonblocking_pool.initialized ? &input_pool : &nonblocking_pool;
Theodore Ts'o840f9502014-06-14 03:06:57 -0400925 if (!spin_trylock(&r->lock))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700926 return;
927
Theodore Ts'o775f4b22012-07-02 07:52:16 -0400928 fast_pool->last = now;
Theodore Ts'o85608f82014-06-10 23:09:20 -0400929 __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool));
H. Peter Anvin83664a62014-03-17 16:36:28 -0700930
931 /*
932 * If we have architectural seed generator, produce a seed and
Theodore Ts'o48d6be92014-07-17 05:27:30 -0400933 * add it to the pool. For the sake of paranoia don't let the
934 * architectural seed generator dominate the input from the
935 * interrupt noise.
H. Peter Anvin83664a62014-03-17 16:36:28 -0700936 */
937 if (arch_get_random_seed_long(&seed)) {
Theodore Ts'o85608f82014-06-10 23:09:20 -0400938 __mix_pool_bytes(r, &seed, sizeof(seed));
Theodore Ts'o48d6be92014-07-17 05:27:30 -0400939 credit = 1;
H. Peter Anvin83664a62014-03-17 16:36:28 -0700940 }
Theodore Ts'o91fcb532014-06-10 22:46:37 -0400941 spin_unlock(&r->lock);
H. Peter Anvin83664a62014-03-17 16:36:28 -0700942
Theodore Ts'oee3e00e2014-06-15 16:59:24 -0400943 fast_pool->count = 0;
Theodore Ts'o840f9502014-06-14 03:06:57 -0400944
Theodore Ts'oee3e00e2014-06-15 16:59:24 -0400945 /* award one bit for the contents of the fast pool */
946 credit_entropy_bits(r, credit + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700947}
948
David Howells93614012006-09-30 20:45:40 +0200949#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700950void add_disk_randomness(struct gendisk *disk)
951{
952 if (!disk || !disk->random)
953 return;
954 /* first major is 1, so we get >= 0x200 here */
Tejun Heof331c022008-09-03 09:01:48 +0200955 add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
Theodore Ts'of80bbd82013-10-03 12:02:37 -0400956 trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS(&input_pool));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700957}
Christoph Hellwigbdcfa3e2014-04-25 00:36:37 -0700958EXPORT_SYMBOL_GPL(add_disk_randomness);
David Howells93614012006-09-30 20:45:40 +0200959#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700960
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961/*********************************************************************
962 *
963 * Entropy extraction routines
964 *
965 *********************************************************************/
966
Matt Mackall90b75ee2008-04-29 01:02:55 -0700967static ssize_t extract_entropy(struct entropy_store *r, void *buf,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968 size_t nbytes, int min, int rsvd);
969
970/*
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300971 * This utility inline function is responsible for transferring entropy
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972 * from the primary pool to the secondary extraction pool. We make
973 * sure we pull enough for a 'catastrophic reseed'.
974 */
Theodore Ts'o6265e162013-10-03 01:08:15 -0400975static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700976static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
977{
Theodore Ts'ocff85032014-06-10 23:18:16 -0400978 if (!r->pull ||
979 r->entropy_count >= (nbytes << (ENTROPY_SHIFT + 3)) ||
980 r->entropy_count > r->poolinfo->poolfracbits)
981 return;
982
Theodore Ts'of5c27422013-09-22 15:14:32 -0400983 if (r->limit == 0 && random_min_urandom_seed) {
984 unsigned long now = jiffies;
985
986 if (time_before(now,
987 r->last_pulled + random_min_urandom_seed * HZ))
988 return;
989 r->last_pulled = now;
990 }
Theodore Ts'ocff85032014-06-10 23:18:16 -0400991
992 _xfer_secondary_pool(r, nbytes);
Theodore Ts'o6265e162013-10-03 01:08:15 -0400993}
Matt Mackall5a021e92007-07-19 11:30:14 -0700994
Theodore Ts'o6265e162013-10-03 01:08:15 -0400995static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
996{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997 __u32 tmp[OUTPUT_POOL_WORDS];
998
Greg Price2132a962013-12-06 21:28:03 -0500999 /* For /dev/random's pool, always leave two wakeups' worth */
1000 int rsvd_bytes = r->limit ? 0 : random_read_wakeup_bits / 4;
Theodore Ts'o6265e162013-10-03 01:08:15 -04001001 int bytes = nbytes;
Matt Mackall5a021e92007-07-19 11:30:14 -07001002
Greg Price2132a962013-12-06 21:28:03 -05001003 /* pull at least as much as a wakeup */
1004 bytes = max_t(int, bytes, random_read_wakeup_bits / 8);
Theodore Ts'o6265e162013-10-03 01:08:15 -04001005 /* but never more than the buffer size */
1006 bytes = min_t(int, bytes, sizeof(tmp));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001007
Theodore Ts'of80bbd82013-10-03 12:02:37 -04001008 trace_xfer_secondary_pool(r->name, bytes * 8, nbytes * 8,
1009 ENTROPY_BITS(r), ENTROPY_BITS(r->pull));
Theodore Ts'o6265e162013-10-03 01:08:15 -04001010 bytes = extract_entropy(r->pull, tmp, bytes,
Greg Price2132a962013-12-06 21:28:03 -05001011 random_read_wakeup_bits / 8, rsvd_bytes);
Theodore Ts'o85608f82014-06-10 23:09:20 -04001012 mix_pool_bytes(r, tmp, bytes);
Theodore Ts'o6265e162013-10-03 01:08:15 -04001013 credit_entropy_bits(r, bytes*8);
1014}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001015
Theodore Ts'o6265e162013-10-03 01:08:15 -04001016/*
1017 * Used as a workqueue function so that when the input pool is getting
1018 * full, we can "spill over" some entropy to the output pools. That
1019 * way the output pools can store some of the excess entropy instead
1020 * of letting it go to waste.
1021 */
1022static void push_to_pool(struct work_struct *work)
1023{
1024 struct entropy_store *r = container_of(work, struct entropy_store,
1025 push_work);
1026 BUG_ON(!r);
Greg Price2132a962013-12-06 21:28:03 -05001027 _xfer_secondary_pool(r, random_read_wakeup_bits/8);
Theodore Ts'o6265e162013-10-03 01:08:15 -04001028 trace_push_to_pool(r->name, r->entropy_count >> ENTROPY_SHIFT,
1029 r->pull->entropy_count >> ENTROPY_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030}
1031
1032/*
Greg Price19fa5be2013-11-29 15:50:06 -05001033 * This function decides how many bytes to actually take from the
1034 * given pool, and also debits the entropy count accordingly.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001036static size_t account(struct entropy_store *r, size_t nbytes, int min,
1037 int reserved)
1038{
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001039 int entropy_count, orig;
Hannes Frederic Sowa79a84682014-07-18 17:26:41 -04001040 size_t ibytes, nfrac;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001041
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001042 BUG_ON(r->entropy_count > r->poolinfo->poolfracbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043
1044 /* Can we pull enough? */
Jiri Kosina10b3a322013-05-24 15:55:33 -07001045retry:
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001046 entropy_count = orig = ACCESS_ONCE(r->entropy_count);
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001047 ibytes = nbytes;
Greg Price0fb7a012013-12-05 19:32:19 -05001048 /* If limited, never pull more than available */
Theodore Ts'oe33ba5f2014-06-15 21:04:32 -04001049 if (r->limit) {
1050 int have_bytes = entropy_count >> (ENTROPY_SHIFT + 3);
1051
1052 if ((have_bytes -= reserved) < 0)
1053 have_bytes = 0;
1054 ibytes = min_t(size_t, ibytes, have_bytes);
1055 }
Greg Price0fb7a012013-12-05 19:32:19 -05001056 if (ibytes < min)
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001057 ibytes = 0;
Hannes Frederic Sowa79a84682014-07-18 17:26:41 -04001058
1059 if (unlikely(entropy_count < 0)) {
1060 pr_warn("random: negative entropy count: pool %s count %d\n",
1061 r->name, entropy_count);
1062 WARN_ON(1);
1063 entropy_count = 0;
1064 }
1065 nfrac = ibytes << (ENTROPY_SHIFT + 3);
1066 if ((size_t) entropy_count > nfrac)
1067 entropy_count -= nfrac;
1068 else
Theodore Ts'oe33ba5f2014-06-15 21:04:32 -04001069 entropy_count = 0;
Theodore Ts'of9c6d492014-05-16 21:40:41 -04001070
Greg Price0fb7a012013-12-05 19:32:19 -05001071 if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
1072 goto retry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001073
Theodore Ts'of80bbd82013-10-03 12:02:37 -04001074 trace_debit_entropy(r->name, 8 * ibytes);
Greg Price0fb7a012013-12-05 19:32:19 -05001075 if (ibytes &&
Greg Price2132a962013-12-06 21:28:03 -05001076 (r->entropy_count >> ENTROPY_SHIFT) < random_write_wakeup_bits) {
Theodore Ts'ob9809552013-03-04 11:59:12 -05001077 wake_up_interruptible(&random_write_wait);
1078 kill_fasync(&fasync, SIGIO, POLL_OUT);
1079 }
1080
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001081 return ibytes;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001082}
1083
Greg Price19fa5be2013-11-29 15:50:06 -05001084/*
1085 * This function does the actual extraction for extract_entropy and
1086 * extract_entropy_user.
1087 *
1088 * Note: we assume that .poolwords is a multiple of 16 words.
1089 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001090static void extract_buf(struct entropy_store *r, __u8 *out)
1091{
Matt Mackall602b6ae2007-05-29 21:54:27 -05001092 int i;
H. Peter Anvind2e7c962012-07-27 22:26:08 -04001093 union {
1094 __u32 w[5];
Theodore Ts'o85a1f772013-09-21 18:06:02 -04001095 unsigned long l[LONGS(20)];
H. Peter Anvind2e7c962012-07-27 22:26:08 -04001096 } hash;
1097 __u32 workspace[SHA_WORKSPACE_WORDS];
Theodore Ts'o902c0982012-07-04 10:38:30 -04001098 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099
Linus Torvalds1da177e2005-04-16 15:20:36 -07001100 /*
Greg Pricedfd38752013-11-29 14:58:06 -05001101 * If we have an architectural hardware random number
Theodore Ts'o46884442013-12-17 21:16:39 -05001102 * generator, use it for SHA's initial vector
Theodore Ts'o85a1f772013-09-21 18:06:02 -04001103 */
Theodore Ts'o46884442013-12-17 21:16:39 -05001104 sha_init(hash.w);
Theodore Ts'o85a1f772013-09-21 18:06:02 -04001105 for (i = 0; i < LONGS(20); i++) {
1106 unsigned long v;
1107 if (!arch_get_random_long(&v))
1108 break;
Theodore Ts'o46884442013-12-17 21:16:39 -05001109 hash.l[i] = v;
Theodore Ts'o85a1f772013-09-21 18:06:02 -04001110 }
1111
Theodore Ts'o46884442013-12-17 21:16:39 -05001112 /* Generate a hash across the pool, 16 words (512 bits) at a time */
1113 spin_lock_irqsave(&r->lock, flags);
1114 for (i = 0; i < r->poolinfo->poolwords; i += 16)
1115 sha_transform(hash.w, (__u8 *)(r->pool + i), workspace);
1116
Theodore Ts'o85a1f772013-09-21 18:06:02 -04001117 /*
Matt Mackall1c0ad3d2008-04-29 01:03:00 -07001118 * We mix the hash back into the pool to prevent backtracking
1119 * attacks (where the attacker knows the state of the pool
1120 * plus the current outputs, and attempts to find previous
1121 * ouputs), unless the hash function can be inverted. By
1122 * mixing at least a SHA1 worth of hash data back, we make
1123 * brute-forcing the feedback as hard as brute-forcing the
1124 * hash.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125 */
Theodore Ts'o85608f82014-06-10 23:09:20 -04001126 __mix_pool_bytes(r, hash.w, sizeof(hash.w));
Theodore Ts'o902c0982012-07-04 10:38:30 -04001127 spin_unlock_irqrestore(&r->lock, flags);
Matt Mackall1c0ad3d2008-04-29 01:03:00 -07001128
Daniel Borkmannd4c5efd2014-08-26 23:16:35 -04001129 memzero_explicit(workspace, sizeof(workspace));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001130
1131 /*
Matt Mackall1c0ad3d2008-04-29 01:03:00 -07001132 * In case the hash function has some recognizable output
1133 * pattern, we fold it in half. Thus, we always feed back
1134 * twice as much data as we output.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001135 */
H. Peter Anvind2e7c962012-07-27 22:26:08 -04001136 hash.w[0] ^= hash.w[3];
1137 hash.w[1] ^= hash.w[4];
1138 hash.w[2] ^= rol32(hash.w[2], 16);
1139
H. Peter Anvind2e7c962012-07-27 22:26:08 -04001140 memcpy(out, &hash, EXTRACT_SIZE);
Daniel Borkmannd4c5efd2014-08-26 23:16:35 -04001141 memzero_explicit(&hash, sizeof(hash));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001142}
1143
Greg Price19fa5be2013-11-29 15:50:06 -05001144/*
1145 * This function extracts randomness from the "entropy pool", and
1146 * returns it in a buffer.
1147 *
1148 * The min parameter specifies the minimum amount we can pull before
1149 * failing to avoid races that defeat catastrophic reseeding while the
1150 * reserved parameter indicates how much entropy we must leave in the
1151 * pool after each pull to avoid starving other readers.
1152 */
Matt Mackall90b75ee2008-04-29 01:02:55 -07001153static ssize_t extract_entropy(struct entropy_store *r, void *buf,
Theodore Ts'o902c0982012-07-04 10:38:30 -04001154 size_t nbytes, int min, int reserved)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001155{
1156 ssize_t ret = 0, i;
1157 __u8 tmp[EXTRACT_SIZE];
Jarod Wilson1e7e2e02013-05-24 15:55:31 -07001158 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001159
Jarod Wilsonec8f02da2012-11-06 10:42:42 -05001160 /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
Jarod Wilson1e7e2e02013-05-24 15:55:31 -07001161 if (fips_enabled) {
1162 spin_lock_irqsave(&r->lock, flags);
1163 if (!r->last_data_init) {
Theodore Ts'oc59974a2013-09-21 19:42:41 -04001164 r->last_data_init = 1;
Jarod Wilson1e7e2e02013-05-24 15:55:31 -07001165 spin_unlock_irqrestore(&r->lock, flags);
1166 trace_extract_entropy(r->name, EXTRACT_SIZE,
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001167 ENTROPY_BITS(r), _RET_IP_);
Jarod Wilson1e7e2e02013-05-24 15:55:31 -07001168 xfer_secondary_pool(r, EXTRACT_SIZE);
1169 extract_buf(r, tmp);
1170 spin_lock_irqsave(&r->lock, flags);
1171 memcpy(r->last_data, tmp, EXTRACT_SIZE);
1172 }
1173 spin_unlock_irqrestore(&r->lock, flags);
1174 }
Jarod Wilsonec8f02da2012-11-06 10:42:42 -05001175
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001176 trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177 xfer_secondary_pool(r, nbytes);
1178 nbytes = account(r, nbytes, min, reserved);
1179
1180 while (nbytes) {
1181 extract_buf(r, tmp);
Neil Horman5b739ef2009-06-18 19:50:21 +08001182
Matt Mackalle954bc92010-05-20 19:55:01 +10001183 if (fips_enabled) {
Neil Horman5b739ef2009-06-18 19:50:21 +08001184 spin_lock_irqsave(&r->lock, flags);
1185 if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
1186 panic("Hardware RNG duplicated output!\n");
1187 memcpy(r->last_data, tmp, EXTRACT_SIZE);
1188 spin_unlock_irqrestore(&r->lock, flags);
1189 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190 i = min_t(int, nbytes, EXTRACT_SIZE);
1191 memcpy(buf, tmp, i);
1192 nbytes -= i;
1193 buf += i;
1194 ret += i;
1195 }
1196
1197 /* Wipe data just returned from memory */
Daniel Borkmannd4c5efd2014-08-26 23:16:35 -04001198 memzero_explicit(tmp, sizeof(tmp));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001199
1200 return ret;
1201}
1202
Greg Price19fa5be2013-11-29 15:50:06 -05001203/*
1204 * This function extracts randomness from the "entropy pool", and
1205 * returns it in a userspace buffer.
1206 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
1208 size_t nbytes)
1209{
1210 ssize_t ret = 0, i;
1211 __u8 tmp[EXTRACT_SIZE];
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001212 int large_request = (nbytes > 256);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001213
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001214 trace_extract_entropy_user(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001215 xfer_secondary_pool(r, nbytes);
1216 nbytes = account(r, nbytes, 0, 0);
1217
1218 while (nbytes) {
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001219 if (large_request && need_resched()) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220 if (signal_pending(current)) {
1221 if (ret == 0)
1222 ret = -ERESTARTSYS;
1223 break;
1224 }
1225 schedule();
1226 }
1227
1228 extract_buf(r, tmp);
1229 i = min_t(int, nbytes, EXTRACT_SIZE);
1230 if (copy_to_user(buf, tmp, i)) {
1231 ret = -EFAULT;
1232 break;
1233 }
1234
1235 nbytes -= i;
1236 buf += i;
1237 ret += i;
1238 }
1239
1240 /* Wipe data just returned from memory */
Daniel Borkmannd4c5efd2014-08-26 23:16:35 -04001241 memzero_explicit(tmp, sizeof(tmp));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242
1243 return ret;
1244}
1245
1246/*
1247 * This function is the exported kernel interface. It returns some
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001248 * number of good random numbers, suitable for key generation, seeding
Greg Price18e9cea2013-11-29 14:59:45 -05001249 * TCP sequence numbers, etc. It does not rely on the hardware random
1250 * number generator. For random bytes direct from the hardware RNG
1251 * (when available), use get_random_bytes_arch().
Linus Torvalds1da177e2005-04-16 15:20:36 -07001252 */
1253void get_random_bytes(void *buf, int nbytes)
1254{
Theodore Ts'o392a5462013-11-03 18:24:08 -05001255#if DEBUG_RANDOM_BOOT > 0
1256 if (unlikely(nonblocking_pool.initialized == 0))
1257 printk(KERN_NOTICE "random: %pF get_random_bytes called "
1258 "with %d bits of entropy available\n",
1259 (void *) _RET_IP_,
1260 nonblocking_pool.entropy_total);
1261#endif
Theodore Ts'o59108952013-09-12 14:10:25 -04001262 trace_get_random_bytes(nbytes, _RET_IP_);
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001263 extract_entropy(&nonblocking_pool, buf, nbytes, 0, 0);
1264}
1265EXPORT_SYMBOL(get_random_bytes);
1266
1267/*
Herbert Xu205a5252015-06-09 18:19:39 +08001268 * Add a callback function that will be invoked when the nonblocking
1269 * pool is initialised.
1270 *
1271 * returns: 0 if callback is successfully added
1272 * -EALREADY if pool is already initialised (callback not called)
1273 * -ENOENT if module for callback is not alive
1274 */
1275int add_random_ready_callback(struct random_ready_callback *rdy)
1276{
1277 struct module *owner;
1278 unsigned long flags;
1279 int err = -EALREADY;
1280
1281 if (likely(nonblocking_pool.initialized))
1282 return err;
1283
1284 owner = rdy->owner;
1285 if (!try_module_get(owner))
1286 return -ENOENT;
1287
1288 spin_lock_irqsave(&random_ready_list_lock, flags);
1289 if (nonblocking_pool.initialized)
1290 goto out;
1291
1292 owner = NULL;
1293
1294 list_add(&rdy->list, &random_ready_list);
1295 err = 0;
1296
1297out:
1298 spin_unlock_irqrestore(&random_ready_list_lock, flags);
1299
1300 module_put(owner);
1301
1302 return err;
1303}
1304EXPORT_SYMBOL(add_random_ready_callback);
1305
1306/*
1307 * Delete a previously registered readiness callback function.
1308 */
1309void del_random_ready_callback(struct random_ready_callback *rdy)
1310{
1311 unsigned long flags;
1312 struct module *owner = NULL;
1313
1314 spin_lock_irqsave(&random_ready_list_lock, flags);
1315 if (!list_empty(&rdy->list)) {
1316 list_del_init(&rdy->list);
1317 owner = rdy->owner;
1318 }
1319 spin_unlock_irqrestore(&random_ready_list_lock, flags);
1320
1321 module_put(owner);
1322}
1323EXPORT_SYMBOL(del_random_ready_callback);
1324
1325/*
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001326 * This function will use the architecture-specific hardware random
1327 * number generator if it is available. The arch-specific hw RNG will
1328 * almost certainly be faster than what we can do in software, but it
1329 * is impossible to verify that it is implemented securely (as
1330 * opposed, to, say, the AES encryption of a sequence number using a
1331 * key known by the NSA). So it's useful if we need the speed, but
1332 * only if we're willing to trust the hardware manufacturer not to
1333 * have put in a back door.
1334 */
1335void get_random_bytes_arch(void *buf, int nbytes)
1336{
H. Peter Anvin63d77172011-07-31 13:54:50 -07001337 char *p = buf;
1338
Theodore Ts'o59108952013-09-12 14:10:25 -04001339 trace_get_random_bytes_arch(nbytes, _RET_IP_);
H. Peter Anvin63d77172011-07-31 13:54:50 -07001340 while (nbytes) {
1341 unsigned long v;
1342 int chunk = min(nbytes, (int)sizeof(unsigned long));
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001343
H. Peter Anvin63d77172011-07-31 13:54:50 -07001344 if (!arch_get_random_long(&v))
1345 break;
1346
Luck, Tonybd29e562011-11-16 10:50:56 -08001347 memcpy(p, &v, chunk);
H. Peter Anvin63d77172011-07-31 13:54:50 -07001348 p += chunk;
1349 nbytes -= chunk;
1350 }
1351
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001352 if (nbytes)
1353 extract_entropy(&nonblocking_pool, p, nbytes, 0, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354}
Theodore Ts'oc2557a32012-07-05 10:35:23 -04001355EXPORT_SYMBOL(get_random_bytes_arch);
1356
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357
1358/*
1359 * init_std_data - initialize pool with system data
1360 *
1361 * @r: pool to initialize
1362 *
1363 * This function clears the pool's entropy count and mixes some system
1364 * data into the pool to prepare it for use. The pool is not cleared
1365 * as that can only decrease the entropy in the pool.
1366 */
1367static void init_std_data(struct entropy_store *r)
1368{
Theodore Ts'o3e88bdf2011-12-22 16:28:01 -05001369 int i;
Theodore Ts'o902c0982012-07-04 10:38:30 -04001370 ktime_t now = ktime_get_real();
1371 unsigned long rv;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372
Theodore Ts'of5c27422013-09-22 15:14:32 -04001373 r->last_pulled = jiffies;
Theodore Ts'o85608f82014-06-10 23:09:20 -04001374 mix_pool_bytes(r, &now, sizeof(now));
H. Peter Anvin9ed17b72013-09-10 23:16:17 -04001375 for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) {
H. Peter Anvin83664a62014-03-17 16:36:28 -07001376 if (!arch_get_random_seed_long(&rv) &&
1377 !arch_get_random_long(&rv))
Theodore Ts'oae9ecd92013-11-03 07:56:17 -05001378 rv = random_get_entropy();
Theodore Ts'o85608f82014-06-10 23:09:20 -04001379 mix_pool_bytes(r, &rv, sizeof(rv));
Theodore Ts'o3e88bdf2011-12-22 16:28:01 -05001380 }
Theodore Ts'o85608f82014-06-10 23:09:20 -04001381 mix_pool_bytes(r, utsname(), sizeof(*(utsname())));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382}
1383
Tony Luckcbc96b72012-07-23 09:47:57 -07001384/*
1385 * Note that setup_arch() may call add_device_randomness()
1386 * long before we get here. This allows seeding of the pools
1387 * with some platform dependent data very early in the boot
1388 * process. But it limits our options here. We must use
1389 * statically allocated structures that already have all
1390 * initializations complete at compile time. We should also
1391 * take care not to overwrite the precious per platform data
1392 * we were given.
1393 */
Matt Mackall53c3f632008-04-29 01:02:58 -07001394static int rand_initialize(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395{
1396 init_std_data(&input_pool);
1397 init_std_data(&blocking_pool);
1398 init_std_data(&nonblocking_pool);
1399 return 0;
1400}
Theodore Ts'oae9ecd92013-11-03 07:56:17 -05001401early_initcall(rand_initialize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001402
David Howells93614012006-09-30 20:45:40 +02001403#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07001404void rand_initialize_disk(struct gendisk *disk)
1405{
1406 struct timer_rand_state *state;
1407
1408 /*
Eric Dumazetf8595812007-03-28 14:22:33 -07001409 * If kzalloc returns null, we just won't use that entropy
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410 * source.
1411 */
Eric Dumazetf8595812007-03-28 14:22:33 -07001412 state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
Theodore Ts'o644008d2013-11-03 16:40:53 -05001413 if (state) {
1414 state->last_time = INITIAL_JIFFIES;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001415 disk->random = state;
Theodore Ts'o644008d2013-11-03 16:40:53 -05001416 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001417}
David Howells93614012006-09-30 20:45:40 +02001418#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419
1420static ssize_t
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001421_random_read(int nonblock, char __user *buf, size_t nbytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001422{
Greg Price12ff3a52013-11-29 15:02:33 -05001423 ssize_t n;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424
1425 if (nbytes == 0)
1426 return 0;
1427
Greg Price12ff3a52013-11-29 15:02:33 -05001428 nbytes = min_t(size_t, nbytes, SEC_XFER_SIZE);
1429 while (1) {
1430 n = extract_entropy_user(&blocking_pool, buf, nbytes);
1431 if (n < 0)
1432 return n;
Theodore Ts'of80bbd82013-10-03 12:02:37 -04001433 trace_random_read(n*8, (nbytes-n)*8,
1434 ENTROPY_BITS(&blocking_pool),
1435 ENTROPY_BITS(&input_pool));
Greg Price12ff3a52013-11-29 15:02:33 -05001436 if (n > 0)
1437 return n;
H. Peter Anvin331c6492014-03-17 16:36:29 -07001438
Greg Price12ff3a52013-11-29 15:02:33 -05001439 /* Pool is (near) empty. Maybe wait and retry. */
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001440 if (nonblock)
Greg Price12ff3a52013-11-29 15:02:33 -05001441 return -EAGAIN;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001442
Greg Price12ff3a52013-11-29 15:02:33 -05001443 wait_event_interruptible(random_read_wait,
1444 ENTROPY_BITS(&input_pool) >=
Greg Price2132a962013-12-06 21:28:03 -05001445 random_read_wakeup_bits);
Greg Price12ff3a52013-11-29 15:02:33 -05001446 if (signal_pending(current))
1447 return -ERESTARTSYS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001449}
1450
1451static ssize_t
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001452random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
1453{
1454 return _random_read(file->f_flags & O_NONBLOCK, buf, nbytes);
1455}
1456
1457static ssize_t
Matt Mackall90b75ee2008-04-29 01:02:55 -07001458urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001459{
Theodore Ts'o301f0592013-11-03 06:54:51 -05001460 int ret;
1461
1462 if (unlikely(nonblocking_pool.initialized == 0))
1463 printk_once(KERN_NOTICE "random: %s urandom read "
1464 "with %d bits of entropy available\n",
1465 current->comm, nonblocking_pool.entropy_total);
1466
Hannes Frederic Sowa79a84682014-07-18 17:26:41 -04001467 nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));
Theodore Ts'o301f0592013-11-03 06:54:51 -05001468 ret = extract_entropy_user(&nonblocking_pool, buf, nbytes);
Theodore Ts'of80bbd82013-10-03 12:02:37 -04001469
1470 trace_urandom_read(8 * nbytes, ENTROPY_BITS(&nonblocking_pool),
1471 ENTROPY_BITS(&input_pool));
1472 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001473}
1474
1475static unsigned int
1476random_poll(struct file *file, poll_table * wait)
1477{
1478 unsigned int mask;
1479
1480 poll_wait(file, &random_read_wait, wait);
1481 poll_wait(file, &random_write_wait, wait);
1482 mask = 0;
Greg Price2132a962013-12-06 21:28:03 -05001483 if (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001484 mask |= POLLIN | POLLRDNORM;
Greg Price2132a962013-12-06 21:28:03 -05001485 if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001486 mask |= POLLOUT | POLLWRNORM;
1487 return mask;
1488}
1489
Matt Mackall7f397dc2007-05-29 21:58:10 -05001490static int
1491write_pool(struct entropy_store *r, const char __user *buffer, size_t count)
1492{
1493 size_t bytes;
1494 __u32 buf[16];
1495 const char __user *p = buffer;
1496
1497 while (count > 0) {
1498 bytes = min(count, sizeof(buf));
1499 if (copy_from_user(&buf, p, bytes))
1500 return -EFAULT;
1501
1502 count -= bytes;
1503 p += bytes;
1504
Theodore Ts'o85608f82014-06-10 23:09:20 -04001505 mix_pool_bytes(r, buf, bytes);
Matt Mackall91f3f1e2008-02-06 01:37:20 -08001506 cond_resched();
Matt Mackall7f397dc2007-05-29 21:58:10 -05001507 }
1508
1509 return 0;
1510}
1511
Matt Mackall90b75ee2008-04-29 01:02:55 -07001512static ssize_t random_write(struct file *file, const char __user *buffer,
1513 size_t count, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001514{
Matt Mackall7f397dc2007-05-29 21:58:10 -05001515 size_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001516
Matt Mackall7f397dc2007-05-29 21:58:10 -05001517 ret = write_pool(&blocking_pool, buffer, count);
1518 if (ret)
1519 return ret;
1520 ret = write_pool(&nonblocking_pool, buffer, count);
1521 if (ret)
1522 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001523
Matt Mackall7f397dc2007-05-29 21:58:10 -05001524 return (ssize_t)count;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525}
1526
Matt Mackall43ae4862008-04-29 01:02:58 -07001527static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001528{
1529 int size, ent_count;
1530 int __user *p = (int __user *)arg;
1531 int retval;
1532
1533 switch (cmd) {
1534 case RNDGETENTCNT:
Matt Mackall43ae4862008-04-29 01:02:58 -07001535 /* inherently racy, no point locking */
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001536 ent_count = ENTROPY_BITS(&input_pool);
1537 if (put_user(ent_count, p))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001538 return -EFAULT;
1539 return 0;
1540 case RNDADDTOENTCNT:
1541 if (!capable(CAP_SYS_ADMIN))
1542 return -EPERM;
1543 if (get_user(ent_count, p))
1544 return -EFAULT;
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001545 credit_entropy_bits_safe(&input_pool, ent_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001546 return 0;
1547 case RNDADDENTROPY:
1548 if (!capable(CAP_SYS_ADMIN))
1549 return -EPERM;
1550 if (get_user(ent_count, p++))
1551 return -EFAULT;
1552 if (ent_count < 0)
1553 return -EINVAL;
1554 if (get_user(size, p++))
1555 return -EFAULT;
Matt Mackall7f397dc2007-05-29 21:58:10 -05001556 retval = write_pool(&input_pool, (const char __user *)p,
1557 size);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001558 if (retval < 0)
1559 return retval;
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001560 credit_entropy_bits_safe(&input_pool, ent_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001561 return 0;
1562 case RNDZAPENTCNT:
1563 case RNDCLEARPOOL:
Theodore Ts'oae9ecd92013-11-03 07:56:17 -05001564 /*
1565 * Clear the entropy pool counters. We no longer clear
1566 * the entropy pool, as that's silly.
1567 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001568 if (!capable(CAP_SYS_ADMIN))
1569 return -EPERM;
Theodore Ts'oae9ecd92013-11-03 07:56:17 -05001570 input_pool.entropy_count = 0;
1571 nonblocking_pool.entropy_count = 0;
1572 blocking_pool.entropy_count = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001573 return 0;
1574 default:
1575 return -EINVAL;
1576 }
1577}
1578
Jeff Dike9a6f70b2008-04-29 01:03:08 -07001579static int random_fasync(int fd, struct file *filp, int on)
1580{
1581 return fasync_helper(fd, filp, on, &fasync);
1582}
1583
Arjan van de Ven2b8693c2007-02-12 00:55:32 -08001584const struct file_operations random_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001585 .read = random_read,
1586 .write = random_write,
1587 .poll = random_poll,
Matt Mackall43ae4862008-04-29 01:02:58 -07001588 .unlocked_ioctl = random_ioctl,
Jeff Dike9a6f70b2008-04-29 01:03:08 -07001589 .fasync = random_fasync,
Arnd Bergmann6038f372010-08-15 18:52:59 +02001590 .llseek = noop_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001591};
1592
Arjan van de Ven2b8693c2007-02-12 00:55:32 -08001593const struct file_operations urandom_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001594 .read = urandom_read,
1595 .write = random_write,
Matt Mackall43ae4862008-04-29 01:02:58 -07001596 .unlocked_ioctl = random_ioctl,
Jeff Dike9a6f70b2008-04-29 01:03:08 -07001597 .fasync = random_fasync,
Arnd Bergmann6038f372010-08-15 18:52:59 +02001598 .llseek = noop_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001599};
1600
Theodore Ts'oc6e9d6f2014-07-17 04:13:05 -04001601SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
1602 unsigned int, flags)
1603{
1604 if (flags & ~(GRND_NONBLOCK|GRND_RANDOM))
1605 return -EINVAL;
1606
1607 if (count > INT_MAX)
1608 count = INT_MAX;
1609
1610 if (flags & GRND_RANDOM)
1611 return _random_read(flags & GRND_NONBLOCK, buf, count);
1612
1613 if (unlikely(nonblocking_pool.initialized == 0)) {
1614 if (flags & GRND_NONBLOCK)
1615 return -EAGAIN;
1616 wait_event_interruptible(urandom_init_wait,
1617 nonblocking_pool.initialized);
1618 if (signal_pending(current))
1619 return -ERESTARTSYS;
1620 }
1621 return urandom_read(NULL, buf, count, NULL);
1622}
1623
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624/***************************************************************
1625 * Random UUID interface
1626 *
1627 * Used here for a Boot ID, but can be useful for other kernel
1628 * drivers.
1629 ***************************************************************/
1630
1631/*
1632 * Generate random UUID
1633 */
1634void generate_random_uuid(unsigned char uuid_out[16])
1635{
1636 get_random_bytes(uuid_out, 16);
Adam Buchbinderc41b20e2009-12-11 16:35:39 -05001637 /* Set UUID version to 4 --- truly random generation */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001638 uuid_out[6] = (uuid_out[6] & 0x0F) | 0x40;
1639 /* Set the UUID variant to DCE */
1640 uuid_out[8] = (uuid_out[8] & 0x3F) | 0x80;
1641}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001642EXPORT_SYMBOL(generate_random_uuid);
1643
1644/********************************************************************
1645 *
1646 * Sysctl interface
1647 *
1648 ********************************************************************/
1649
1650#ifdef CONFIG_SYSCTL
1651
1652#include <linux/sysctl.h>
1653
1654static int min_read_thresh = 8, min_write_thresh;
Greg Price8c2aa332013-12-05 19:19:29 -05001655static int max_read_thresh = OUTPUT_POOL_WORDS * 32;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001656static int max_write_thresh = INPUT_POOL_WORDS * 32;
1657static char sysctl_bootid[16];
1658
1659/*
Greg Pricef22052b2013-11-29 14:58:16 -05001660 * This function is used to return both the bootid UUID, and random
Linus Torvalds1da177e2005-04-16 15:20:36 -07001661 * UUID. The difference is in whether table->data is NULL; if it is,
1662 * then a new UUID is generated and returned to the user.
1663 *
Greg Pricef22052b2013-11-29 14:58:16 -05001664 * If the user accesses this via the proc interface, the UUID will be
1665 * returned as an ASCII string in the standard UUID format; if via the
1666 * sysctl system call, as 16 bytes of binary data.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001667 */
Joe Perchesa1514272013-06-13 19:37:35 -07001668static int proc_do_uuid(struct ctl_table *table, int write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001669 void __user *buffer, size_t *lenp, loff_t *ppos)
1670{
Joe Perchesa1514272013-06-13 19:37:35 -07001671 struct ctl_table fake_table;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001672 unsigned char buf[64], tmp_uuid[16], *uuid;
1673
1674 uuid = table->data;
1675 if (!uuid) {
1676 uuid = tmp_uuid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001677 generate_random_uuid(uuid);
Mathieu Desnoyers44e43602012-04-12 12:49:12 -07001678 } else {
1679 static DEFINE_SPINLOCK(bootid_spinlock);
1680
1681 spin_lock(&bootid_spinlock);
1682 if (!uuid[8])
1683 generate_random_uuid(uuid);
1684 spin_unlock(&bootid_spinlock);
1685 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001686
Joe Perches35900772009-12-14 18:01:11 -08001687 sprintf(buf, "%pU", uuid);
1688
Linus Torvalds1da177e2005-04-16 15:20:36 -07001689 fake_table.data = buf;
1690 fake_table.maxlen = sizeof(buf);
1691
Alexey Dobriyan8d65af72009-09-23 15:57:19 -07001692 return proc_dostring(&fake_table, write, buffer, lenp, ppos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001693}
1694
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001695/*
1696 * Return entropy available scaled to integral bits
1697 */
Joe Perches5eb10d92014-06-06 14:37:58 -07001698static int proc_do_entropy(struct ctl_table *table, int write,
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001699 void __user *buffer, size_t *lenp, loff_t *ppos)
1700{
Joe Perches5eb10d92014-06-06 14:37:58 -07001701 struct ctl_table fake_table;
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001702 int entropy_count;
1703
1704 entropy_count = *(int *)table->data >> ENTROPY_SHIFT;
1705
1706 fake_table.data = &entropy_count;
1707 fake_table.maxlen = sizeof(entropy_count);
1708
1709 return proc_dointvec(&fake_table, write, buffer, lenp, ppos);
1710}
1711
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712static int sysctl_poolsize = INPUT_POOL_WORDS * 32;
Joe Perchesa1514272013-06-13 19:37:35 -07001713extern struct ctl_table random_table[];
1714struct ctl_table random_table[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001715 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716 .procname = "poolsize",
1717 .data = &sysctl_poolsize,
1718 .maxlen = sizeof(int),
1719 .mode = 0444,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001720 .proc_handler = proc_dointvec,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001721 },
1722 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001723 .procname = "entropy_avail",
1724 .maxlen = sizeof(int),
1725 .mode = 0444,
H. Peter Anvina283b5c2013-09-10 23:16:17 -04001726 .proc_handler = proc_do_entropy,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001727 .data = &input_pool.entropy_count,
1728 },
1729 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730 .procname = "read_wakeup_threshold",
Greg Price2132a962013-12-06 21:28:03 -05001731 .data = &random_read_wakeup_bits,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001732 .maxlen = sizeof(int),
1733 .mode = 0644,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001734 .proc_handler = proc_dointvec_minmax,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001735 .extra1 = &min_read_thresh,
1736 .extra2 = &max_read_thresh,
1737 },
1738 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001739 .procname = "write_wakeup_threshold",
Greg Price2132a962013-12-06 21:28:03 -05001740 .data = &random_write_wakeup_bits,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741 .maxlen = sizeof(int),
1742 .mode = 0644,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001743 .proc_handler = proc_dointvec_minmax,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744 .extra1 = &min_write_thresh,
1745 .extra2 = &max_write_thresh,
1746 },
1747 {
Theodore Ts'of5c27422013-09-22 15:14:32 -04001748 .procname = "urandom_min_reseed_secs",
1749 .data = &random_min_urandom_seed,
1750 .maxlen = sizeof(int),
1751 .mode = 0644,
1752 .proc_handler = proc_dointvec,
1753 },
1754 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001755 .procname = "boot_id",
1756 .data = &sysctl_bootid,
1757 .maxlen = 16,
1758 .mode = 0444,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001759 .proc_handler = proc_do_uuid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001760 },
1761 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001762 .procname = "uuid",
1763 .maxlen = 16,
1764 .mode = 0444,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001765 .proc_handler = proc_do_uuid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001766 },
Theodore Ts'o43759d42014-06-14 21:43:13 -04001767#ifdef ADD_INTERRUPT_BENCH
1768 {
1769 .procname = "add_interrupt_avg_cycles",
1770 .data = &avg_cycles,
1771 .maxlen = sizeof(avg_cycles),
1772 .mode = 0444,
1773 .proc_handler = proc_doulongvec_minmax,
1774 },
1775 {
1776 .procname = "add_interrupt_avg_deviation",
1777 .data = &avg_deviation,
1778 .maxlen = sizeof(avg_deviation),
1779 .mode = 0444,
1780 .proc_handler = proc_doulongvec_minmax,
1781 },
1782#endif
Eric W. Biederman894d2492009-11-05 14:34:02 -08001783 { }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001784};
1785#endif /* CONFIG_SYSCTL */
1786
David S. Miller6e5714e2011-08-03 20:50:44 -07001787static u32 random_int_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001788
Theodore Ts'o47d06e52013-09-10 10:52:35 -04001789int random_int_secret_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001790{
David S. Miller6e5714e2011-08-03 20:50:44 -07001791 get_random_bytes(random_int_secret, sizeof(random_int_secret));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001792 return 0;
1793}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001794
1795/*
1796 * Get a random word for internal kernel use only. Similar to urandom but
1797 * with the goal of minimal entropy pool depletion. As a result, the random
1798 * value is not cryptographically secure but for several uses the cost of
1799 * depleting entropy is too high
1800 */
Theodore Ts'o74feec52012-07-06 14:03:18 -04001801static DEFINE_PER_CPU(__u32 [MD5_DIGEST_WORDS], get_random_int_hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001802unsigned int get_random_int(void)
1803{
H. Peter Anvin63d77172011-07-31 13:54:50 -07001804 __u32 *hash;
David S. Miller6e5714e2011-08-03 20:50:44 -07001805 unsigned int ret;
Linus Torvalds8a0a9bd2009-05-05 08:17:43 -07001806
H. Peter Anvin63d77172011-07-31 13:54:50 -07001807 if (arch_get_random_int(&ret))
1808 return ret;
1809
1810 hash = get_cpu_var(get_random_int_hash);
Linus Torvalds8a0a9bd2009-05-05 08:17:43 -07001811
Theodore Ts'o61875f32013-09-21 13:58:22 -04001812 hash[0] += current->pid + jiffies + random_get_entropy();
David S. Miller6e5714e2011-08-03 20:50:44 -07001813 md5_transform(hash, random_int_secret);
1814 ret = hash[0];
Linus Torvalds8a0a9bd2009-05-05 08:17:43 -07001815 put_cpu_var(get_random_int_hash);
1816
1817 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001818}
Andy Shevchenko16c7fa02013-04-30 15:27:30 -07001819EXPORT_SYMBOL(get_random_int);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001820
1821/*
1822 * randomize_range() returns a start address such that
1823 *
1824 * [...... <range> .....]
1825 * start end
1826 *
1827 * a <range> with size "len" starting at the return value is inside in the
1828 * area defined by [start, end], but is otherwise randomized.
1829 */
1830unsigned long
1831randomize_range(unsigned long start, unsigned long end, unsigned long len)
1832{
1833 unsigned long range = end - len - start;
1834
1835 if (end <= start + len)
1836 return 0;
1837 return PAGE_ALIGN(get_random_int() % range + start);
1838}
Torsten Duwec84dbf62014-06-14 23:38:36 -04001839
1840/* Interface for in-kernel drivers of true hardware RNGs.
1841 * Those devices may produce endless random bits and will be throttled
1842 * when our pool is full.
1843 */
1844void add_hwgenerator_randomness(const char *buffer, size_t count,
1845 size_t entropy)
1846{
1847 struct entropy_store *poolp = &input_pool;
1848
1849 /* Suspend writing if we're above the trickle threshold.
1850 * We'll be woken up again once below random_write_wakeup_thresh,
1851 * or when the calling thread is about to terminate.
1852 */
1853 wait_event_interruptible(random_write_wait, kthread_should_stop() ||
1854 ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits);
1855 mix_pool_bytes(poolp, buffer, count);
1856 credit_entropy_bits(poolp, entropy);
1857}
1858EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);