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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 *
128 * void add_input_randomness(unsigned int type, unsigned int code,
129 * unsigned int value);
130 * void add_interrupt_randomness(int irq);
131 *
132 * add_input_randomness() uses the input layer interrupt timing, as well as
133 * the event type information from the hardware.
134 *
135 * add_interrupt_randomness() uses the inter-interrupt timing as random
136 * inputs to the entropy pool. Note that not all interrupts are good
137 * sources of randomness! For example, the timer interrupts is not a
138 * good choice, because the periodicity of the interrupts is too
139 * regular, and hence predictable to an attacker. Disk interrupts are
140 * a better measure, since the timing of the disk interrupts are more
141 * unpredictable.
142 *
143 * All of these routines try to estimate how many bits of randomness a
144 * particular randomness source. They do this by keeping track of the
145 * first and second order deltas of the event timings.
146 *
147 * Ensuring unpredictability at system startup
148 * ============================================
149 *
150 * When any operating system starts up, it will go through a sequence
151 * of actions that are fairly predictable by an adversary, especially
152 * if the start-up does not involve interaction with a human operator.
153 * This reduces the actual number of bits of unpredictability in the
154 * entropy pool below the value in entropy_count. In order to
155 * counteract this effect, it helps to carry information in the
156 * entropy pool across shut-downs and start-ups. To do this, put the
157 * following lines an appropriate script which is run during the boot
158 * sequence:
159 *
160 * echo "Initializing random number generator..."
161 * random_seed=/var/run/random-seed
162 * # Carry a random seed from start-up to start-up
163 * # Load and then save the whole entropy pool
164 * if [ -f $random_seed ]; then
165 * cat $random_seed >/dev/urandom
166 * else
167 * touch $random_seed
168 * fi
169 * chmod 600 $random_seed
170 * dd if=/dev/urandom of=$random_seed count=1 bs=512
171 *
172 * and the following lines in an appropriate script which is run as
173 * the system is shutdown:
174 *
175 * # Carry a random seed from shut-down to start-up
176 * # Save the whole entropy pool
177 * echo "Saving random seed..."
178 * random_seed=/var/run/random-seed
179 * touch $random_seed
180 * chmod 600 $random_seed
181 * dd if=/dev/urandom of=$random_seed count=1 bs=512
182 *
183 * For example, on most modern systems using the System V init
184 * scripts, such code fragments would be found in
185 * /etc/rc.d/init.d/random. On older Linux systems, the correct script
186 * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0.
187 *
188 * Effectively, these commands cause the contents of the entropy pool
189 * to be saved at shut-down time and reloaded into the entropy pool at
190 * start-up. (The 'dd' in the addition to the bootup script is to
191 * make sure that /etc/random-seed is different for every start-up,
192 * even if the system crashes without executing rc.0.) Even with
193 * complete knowledge of the start-up activities, predicting the state
194 * of the entropy pool requires knowledge of the previous history of
195 * the system.
196 *
197 * Configuring the /dev/random driver under Linux
198 * ==============================================
199 *
200 * The /dev/random driver under Linux uses minor numbers 8 and 9 of
201 * the /dev/mem major number (#1). So if your system does not have
202 * /dev/random and /dev/urandom created already, they can be created
203 * by using the commands:
204 *
205 * mknod /dev/random c 1 8
206 * mknod /dev/urandom c 1 9
207 *
208 * Acknowledgements:
209 * =================
210 *
211 * Ideas for constructing this random number generator were derived
212 * from Pretty Good Privacy's random number generator, and from private
213 * discussions with Phil Karn. Colin Plumb provided a faster random
214 * number generator, which speed up the mixing function of the entropy
215 * pool, taken from PGPfone. Dale Worley has also contributed many
216 * useful ideas and suggestions to improve this driver.
217 *
218 * Any flaws in the design are solely my responsibility, and should
219 * not be attributed to the Phil, Colin, or any of authors of PGP.
220 *
221 * Further background information on this topic may be obtained from
222 * RFC 1750, "Randomness Recommendations for Security", by Donald
223 * Eastlake, Steve Crocker, and Jeff Schiller.
224 */
225
226#include <linux/utsname.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227#include <linux/module.h>
228#include <linux/kernel.h>
229#include <linux/major.h>
230#include <linux/string.h>
231#include <linux/fcntl.h>
232#include <linux/slab.h>
233#include <linux/random.h>
234#include <linux/poll.h>
235#include <linux/init.h>
236#include <linux/fs.h>
237#include <linux/genhd.h>
238#include <linux/interrupt.h>
Andrea Righi27ac7922008-07-23 21:28:13 -0700239#include <linux/mm.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240#include <linux/spinlock.h>
241#include <linux/percpu.h>
242#include <linux/cryptohash.h>
Neil Horman5b739ef2009-06-18 19:50:21 +0800243#include <linux/fips.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244
Yinghai Lud178a1e2009-01-11 00:35:42 -0800245#ifdef CONFIG_GENERIC_HARDIRQS
246# include <linux/irq.h>
247#endif
248
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249#include <asm/processor.h>
250#include <asm/uaccess.h>
251#include <asm/irq.h>
252#include <asm/io.h>
253
254/*
255 * Configuration information
256 */
257#define INPUT_POOL_WORDS 128
258#define OUTPUT_POOL_WORDS 32
259#define SEC_XFER_SIZE 512
Matt Mackalle954bc92010-05-20 19:55:01 +1000260#define EXTRACT_SIZE 10
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261
262/*
263 * The minimum number of bits of entropy before we wake up a read on
264 * /dev/random. Should be enough to do a significant reseed.
265 */
266static int random_read_wakeup_thresh = 64;
267
268/*
269 * If the entropy count falls under this number of bits, then we
270 * should wake up processes which are selecting or polling on write
271 * access to /dev/random.
272 */
273static int random_write_wakeup_thresh = 128;
274
275/*
276 * When the input pool goes over trickle_thresh, start dropping most
277 * samples to avoid wasting CPU time and reduce lock contention.
278 */
279
Christoph Lameter6c036522005-07-07 17:56:59 -0700280static int trickle_thresh __read_mostly = INPUT_POOL_WORDS * 28;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281
Matt Mackall90b75ee2008-04-29 01:02:55 -0700282static DEFINE_PER_CPU(int, trickle_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283
284/*
285 * A pool of size .poolwords is stirred with a primitive polynomial
286 * of degree .poolwords over GF(2). The taps for various sizes are
287 * defined below. They are chosen to be evenly spaced (minimum RMS
288 * distance from evenly spaced; the numbers in the comments are a
289 * scaled squared error sum) except for the last tap, which is 1 to
290 * get the twisting happening as fast as possible.
291 */
292static struct poolinfo {
293 int poolwords;
294 int tap1, tap2, tap3, tap4, tap5;
295} poolinfo_table[] = {
296 /* x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 -- 105 */
297 { 128, 103, 76, 51, 25, 1 },
298 /* x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 -- 15 */
299 { 32, 26, 20, 14, 7, 1 },
300#if 0
301 /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */
302 { 2048, 1638, 1231, 819, 411, 1 },
303
304 /* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */
305 { 1024, 817, 615, 412, 204, 1 },
306
307 /* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */
308 { 1024, 819, 616, 410, 207, 2 },
309
310 /* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */
311 { 512, 411, 308, 208, 104, 1 },
312
313 /* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */
314 { 512, 409, 307, 206, 102, 2 },
315 /* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */
316 { 512, 409, 309, 205, 103, 2 },
317
318 /* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */
319 { 256, 205, 155, 101, 52, 1 },
320
321 /* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */
322 { 128, 103, 78, 51, 27, 2 },
323
324 /* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */
325 { 64, 52, 39, 26, 14, 1 },
326#endif
327};
328
329#define POOLBITS poolwords*32
330#define POOLBYTES poolwords*4
331
332/*
333 * For the purposes of better mixing, we use the CRC-32 polynomial as
334 * well to make a twisted Generalized Feedback Shift Reigster
335 *
336 * (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR generators. ACM
337 * Transactions on Modeling and Computer Simulation 2(3):179-194.
338 * Also see M. Matsumoto & Y. Kurita, 1994. Twisted GFSR generators
339 * II. ACM Transactions on Mdeling and Computer Simulation 4:254-266)
340 *
341 * Thanks to Colin Plumb for suggesting this.
342 *
343 * We have not analyzed the resultant polynomial to prove it primitive;
344 * in fact it almost certainly isn't. Nonetheless, the irreducible factors
345 * of a random large-degree polynomial over GF(2) are more than large enough
346 * that periodicity is not a concern.
347 *
348 * The input hash is much less sensitive than the output hash. All
349 * that we want of it is that it be a good non-cryptographic hash;
350 * i.e. it not produce collisions when fed "random" data of the sort
351 * we expect to see. As long as the pool state differs for different
352 * inputs, we have preserved the input entropy and done a good job.
353 * The fact that an intelligent attacker can construct inputs that
354 * will produce controlled alterations to the pool's state is not
355 * important because we don't consider such inputs to contribute any
356 * randomness. The only property we need with respect to them is that
357 * the attacker can't increase his/her knowledge of the pool's state.
358 * Since all additions are reversible (knowing the final state and the
359 * input, you can reconstruct the initial state), if an attacker has
360 * any uncertainty about the initial state, he/she can only shuffle
361 * that uncertainty about, but never cause any collisions (which would
362 * decrease the uncertainty).
363 *
364 * The chosen system lets the state of the pool be (essentially) the input
365 * modulo the generator polymnomial. Now, for random primitive polynomials,
366 * this is a universal class of hash functions, meaning that the chance
367 * of a collision is limited by the attacker's knowledge of the generator
368 * polynomail, so if it is chosen at random, an attacker can never force
369 * a collision. Here, we use a fixed polynomial, but we *can* assume that
370 * ###--> it is unknown to the processes generating the input entropy. <-###
371 * Because of this important property, this is a good, collision-resistant
372 * hash; hash collisions will occur no more often than chance.
373 */
374
375/*
376 * Static global variables
377 */
378static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
379static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
Jeff Dike9a6f70b2008-04-29 01:03:08 -0700380static struct fasync_struct *fasync;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381
382#if 0
Matt Mackall90b75ee2008-04-29 01:02:55 -0700383static int debug;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384module_param(debug, bool, 0644);
Matt Mackall90b75ee2008-04-29 01:02:55 -0700385#define DEBUG_ENT(fmt, arg...) do { \
386 if (debug) \
387 printk(KERN_DEBUG "random %04d %04d %04d: " \
388 fmt,\
389 input_pool.entropy_count,\
390 blocking_pool.entropy_count,\
391 nonblocking_pool.entropy_count,\
392 ## arg); } while (0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393#else
394#define DEBUG_ENT(fmt, arg...) do {} while (0)
395#endif
396
397/**********************************************************************
398 *
399 * OS independent entropy store. Here are the functions which handle
400 * storing entropy in an entropy pool.
401 *
402 **********************************************************************/
403
404struct entropy_store;
405struct entropy_store {
Matt Mackall43358202008-04-29 01:03:01 -0700406 /* read-only data: */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407 struct poolinfo *poolinfo;
408 __u32 *pool;
409 const char *name;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 struct entropy_store *pull;
Richard Kennedy4015d9a2010-07-31 19:58:00 +0800411 int limit;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412
413 /* read-write data: */
Matt Mackall43358202008-04-29 01:03:01 -0700414 spinlock_t lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 unsigned add_ptr;
Matt Mackallcda796a2009-01-06 14:42:55 -0800416 int entropy_count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 int input_rotate;
Matt Mackalle954bc92010-05-20 19:55:01 +1000418 __u8 last_data[EXTRACT_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419};
420
421static __u32 input_pool_data[INPUT_POOL_WORDS];
422static __u32 blocking_pool_data[OUTPUT_POOL_WORDS];
423static __u32 nonblocking_pool_data[OUTPUT_POOL_WORDS];
424
425static struct entropy_store input_pool = {
426 .poolinfo = &poolinfo_table[0],
427 .name = "input",
428 .limit = 1,
Ingo Molnare4d91912006-07-03 00:24:34 -0700429 .lock = __SPIN_LOCK_UNLOCKED(&input_pool.lock),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430 .pool = input_pool_data
431};
432
433static struct entropy_store blocking_pool = {
434 .poolinfo = &poolinfo_table[1],
435 .name = "blocking",
436 .limit = 1,
437 .pull = &input_pool,
Ingo Molnare4d91912006-07-03 00:24:34 -0700438 .lock = __SPIN_LOCK_UNLOCKED(&blocking_pool.lock),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439 .pool = blocking_pool_data
440};
441
442static struct entropy_store nonblocking_pool = {
443 .poolinfo = &poolinfo_table[1],
444 .name = "nonblocking",
445 .pull = &input_pool,
Ingo Molnare4d91912006-07-03 00:24:34 -0700446 .lock = __SPIN_LOCK_UNLOCKED(&nonblocking_pool.lock),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447 .pool = nonblocking_pool_data
448};
449
450/*
Matt Mackalle68e5b62008-04-29 01:03:05 -0700451 * This function adds bytes into the entropy "pool". It does not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 * update the entropy estimate. The caller should call
Matt Mackalladc782d2008-04-29 01:03:07 -0700453 * credit_entropy_bits if this is appropriate.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454 *
455 * The pool is stirred with a primitive polynomial of the appropriate
456 * degree, and then twisted. We twist by three bits at a time because
457 * it's cheap to do so and helps slightly in the expected case where
458 * the entropy is concentrated in the low-order bits.
459 */
Matt Mackalle68e5b62008-04-29 01:03:05 -0700460static void mix_pool_bytes_extract(struct entropy_store *r, const void *in,
461 int nbytes, __u8 out[64])
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462{
463 static __u32 const twist_table[8] = {
464 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
465 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
Matt Mackall993ba212008-04-29 01:03:04 -0700466 unsigned long i, j, tap1, tap2, tap3, tap4, tap5;
Matt Mackallfeee7692008-04-29 01:03:02 -0700467 int input_rotate;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468 int wordmask = r->poolinfo->poolwords - 1;
Matt Mackalle68e5b62008-04-29 01:03:05 -0700469 const char *bytes = in;
Matt Mackall6d38b822008-04-29 01:03:03 -0700470 __u32 w;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 unsigned long flags;
472
473 /* Taps are constant, so we can load them without holding r->lock. */
474 tap1 = r->poolinfo->tap1;
475 tap2 = r->poolinfo->tap2;
476 tap3 = r->poolinfo->tap3;
477 tap4 = r->poolinfo->tap4;
478 tap5 = r->poolinfo->tap5;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479
480 spin_lock_irqsave(&r->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481 input_rotate = r->input_rotate;
Matt Mackall993ba212008-04-29 01:03:04 -0700482 i = r->add_ptr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483
Matt Mackalle68e5b62008-04-29 01:03:05 -0700484 /* mix one byte at a time to simplify size handling and churn faster */
485 while (nbytes--) {
486 w = rol32(*bytes++, input_rotate & 31);
Matt Mackall993ba212008-04-29 01:03:04 -0700487 i = (i - 1) & wordmask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488
489 /* XOR in the various taps */
Matt Mackall993ba212008-04-29 01:03:04 -0700490 w ^= r->pool[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491 w ^= r->pool[(i + tap1) & wordmask];
492 w ^= r->pool[(i + tap2) & wordmask];
493 w ^= r->pool[(i + tap3) & wordmask];
494 w ^= r->pool[(i + tap4) & wordmask];
495 w ^= r->pool[(i + tap5) & wordmask];
Matt Mackall993ba212008-04-29 01:03:04 -0700496
497 /* Mix the result back in with a twist */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498 r->pool[i] = (w >> 3) ^ twist_table[w & 7];
Matt Mackallfeee7692008-04-29 01:03:02 -0700499
500 /*
501 * Normally, we add 7 bits of rotation to the pool.
502 * At the beginning of the pool, add an extra 7 bits
503 * rotation, so that successive passes spread the
504 * input bits across the pool evenly.
505 */
506 input_rotate += i ? 7 : 14;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507 }
508
509 r->input_rotate = input_rotate;
Matt Mackall993ba212008-04-29 01:03:04 -0700510 r->add_ptr = i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511
Matt Mackall993ba212008-04-29 01:03:04 -0700512 if (out)
513 for (j = 0; j < 16; j++)
Matt Mackalle68e5b62008-04-29 01:03:05 -0700514 ((__u32 *)out)[j] = r->pool[(i - j) & wordmask];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515
516 spin_unlock_irqrestore(&r->lock, flags);
517}
518
Matt Mackalle68e5b62008-04-29 01:03:05 -0700519static void mix_pool_bytes(struct entropy_store *r, const void *in, int bytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520{
Matt Mackalle68e5b62008-04-29 01:03:05 -0700521 mix_pool_bytes_extract(r, in, bytes, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522}
523
524/*
525 * Credit (or debit) the entropy store with n bits of entropy
526 */
Matt Mackalladc782d2008-04-29 01:03:07 -0700527static void credit_entropy_bits(struct entropy_store *r, int nbits)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528{
529 unsigned long flags;
Andrew Morton8b76f462008-09-02 14:36:14 -0700530 int entropy_count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531
Matt Mackalladc782d2008-04-29 01:03:07 -0700532 if (!nbits)
533 return;
534
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 spin_lock_irqsave(&r->lock, flags);
536
Matt Mackalladc782d2008-04-29 01:03:07 -0700537 DEBUG_ENT("added %d entropy credits to %s\n", nbits, r->name);
Andrew Morton8b76f462008-09-02 14:36:14 -0700538 entropy_count = r->entropy_count;
539 entropy_count += nbits;
540 if (entropy_count < 0) {
Matt Mackalladc782d2008-04-29 01:03:07 -0700541 DEBUG_ENT("negative entropy/overflow\n");
Andrew Morton8b76f462008-09-02 14:36:14 -0700542 entropy_count = 0;
543 } else if (entropy_count > r->poolinfo->POOLBITS)
544 entropy_count = r->poolinfo->POOLBITS;
545 r->entropy_count = entropy_count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546
Matt Mackall88c730d2008-04-29 01:02:56 -0700547 /* should we wake readers? */
Andrew Morton8b76f462008-09-02 14:36:14 -0700548 if (r == &input_pool && entropy_count >= random_read_wakeup_thresh) {
Matt Mackall88c730d2008-04-29 01:02:56 -0700549 wake_up_interruptible(&random_read_wait);
Jeff Dike9a6f70b2008-04-29 01:03:08 -0700550 kill_fasync(&fasync, SIGIO, POLL_IN);
551 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552 spin_unlock_irqrestore(&r->lock, flags);
553}
554
555/*********************************************************************
556 *
557 * Entropy input management
558 *
559 *********************************************************************/
560
561/* There is one of these per entropy source */
562struct timer_rand_state {
563 cycles_t last_time;
Matt Mackall90b75ee2008-04-29 01:02:55 -0700564 long last_delta, last_delta2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565 unsigned dont_count_entropy:1;
566};
567
Yinghai Lud7e51e62009-01-07 15:03:13 -0800568#ifndef CONFIG_GENERIC_HARDIRQS
Yinghai Lu2f983572009-01-03 00:06:34 -0800569
570static struct timer_rand_state *irq_timer_state[NR_IRQS];
571
572static struct timer_rand_state *get_timer_rand_state(unsigned int irq)
573{
574 return irq_timer_state[irq];
575}
576
577static void set_timer_rand_state(unsigned int irq,
578 struct timer_rand_state *state)
579{
580 irq_timer_state[irq] = state;
581}
582
583#else
584
585static struct timer_rand_state *get_timer_rand_state(unsigned int irq)
586{
587 struct irq_desc *desc;
588
589 desc = irq_to_desc(irq);
590
591 return desc->timer_rand_state;
592}
593
594static void set_timer_rand_state(unsigned int irq,
595 struct timer_rand_state *state)
596{
597 struct irq_desc *desc;
598
599 desc = irq_to_desc(irq);
600
601 desc->timer_rand_state = state;
602}
Yinghai Lu0b8f1ef2008-12-05 18:58:31 -0800603#endif
Yinghai Lu3060d6f2008-08-19 20:50:08 -0700604
Yinghai Lu3060d6f2008-08-19 20:50:08 -0700605static struct timer_rand_state input_timer_state;
606
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607/*
608 * This function adds entropy to the entropy "pool" by using timing
609 * delays. It uses the timer_rand_state structure to make an estimate
610 * of how many bits of entropy this call has added to the pool.
611 *
612 * The number "num" is also added to the pool - it should somehow describe
613 * the type of event which just happened. This is currently 0-255 for
614 * keyboard scan codes, and 256 upwards for interrupts.
615 *
616 */
617static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
618{
619 struct {
620 cycles_t cycles;
621 long jiffies;
622 unsigned num;
623 } sample;
624 long delta, delta2, delta3;
625
626 preempt_disable();
627 /* if over the trickle threshold, use only 1 in 4096 samples */
628 if (input_pool.entropy_count > trickle_thresh &&
629 (__get_cpu_var(trickle_count)++ & 0xfff))
630 goto out;
631
632 sample.jiffies = jiffies;
633 sample.cycles = get_cycles();
634 sample.num = num;
Matt Mackalle68e5b62008-04-29 01:03:05 -0700635 mix_pool_bytes(&input_pool, &sample, sizeof(sample));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636
637 /*
638 * Calculate number of bits of randomness we probably added.
639 * We take into account the first, second and third-order deltas
640 * in order to make our estimate.
641 */
642
643 if (!state->dont_count_entropy) {
644 delta = sample.jiffies - state->last_time;
645 state->last_time = sample.jiffies;
646
647 delta2 = delta - state->last_delta;
648 state->last_delta = delta;
649
650 delta3 = delta2 - state->last_delta2;
651 state->last_delta2 = delta2;
652
653 if (delta < 0)
654 delta = -delta;
655 if (delta2 < 0)
656 delta2 = -delta2;
657 if (delta3 < 0)
658 delta3 = -delta3;
659 if (delta > delta2)
660 delta = delta2;
661 if (delta > delta3)
662 delta = delta3;
663
664 /*
665 * delta is now minimum absolute delta.
666 * Round down by 1 bit on general principles,
667 * and limit entropy entimate to 12 bits.
668 */
Matt Mackalladc782d2008-04-29 01:03:07 -0700669 credit_entropy_bits(&input_pool,
670 min_t(int, fls(delta>>1), 11));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672out:
673 preempt_enable();
674}
675
Stephen Hemmingerd2515752006-01-11 12:17:38 -0800676void add_input_randomness(unsigned int type, unsigned int code,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677 unsigned int value)
678{
679 static unsigned char last_value;
680
681 /* ignore autorepeat and the like */
682 if (value == last_value)
683 return;
684
685 DEBUG_ENT("input event\n");
686 last_value = value;
687 add_timer_randomness(&input_timer_state,
688 (type << 4) ^ code ^ (code >> 4) ^ value);
689}
Dmitry Torokhov80fc9f52006-10-11 01:43:58 -0400690EXPORT_SYMBOL_GPL(add_input_randomness);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700691
692void add_interrupt_randomness(int irq)
693{
Yinghai Lu3060d6f2008-08-19 20:50:08 -0700694 struct timer_rand_state *state;
695
696 state = get_timer_rand_state(irq);
697
698 if (state == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699 return;
700
701 DEBUG_ENT("irq event %d\n", irq);
Yinghai Lu3060d6f2008-08-19 20:50:08 -0700702 add_timer_randomness(state, 0x100 + irq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703}
704
David Howells93614012006-09-30 20:45:40 +0200705#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706void add_disk_randomness(struct gendisk *disk)
707{
708 if (!disk || !disk->random)
709 return;
710 /* first major is 1, so we get >= 0x200 here */
Tejun Heof331c022008-09-03 09:01:48 +0200711 DEBUG_ENT("disk event %d:%d\n",
712 MAJOR(disk_devt(disk)), MINOR(disk_devt(disk)));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700713
Tejun Heof331c022008-09-03 09:01:48 +0200714 add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715}
David Howells93614012006-09-30 20:45:40 +0200716#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700717
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718/*********************************************************************
719 *
720 * Entropy extraction routines
721 *
722 *********************************************************************/
723
Matt Mackall90b75ee2008-04-29 01:02:55 -0700724static ssize_t extract_entropy(struct entropy_store *r, void *buf,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 size_t nbytes, int min, int rsvd);
726
727/*
728 * This utility inline function is responsible for transfering entropy
729 * from the primary pool to the secondary extraction pool. We make
730 * sure we pull enough for a 'catastrophic reseed'.
731 */
732static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
733{
734 __u32 tmp[OUTPUT_POOL_WORDS];
735
736 if (r->pull && r->entropy_count < nbytes * 8 &&
737 r->entropy_count < r->poolinfo->POOLBITS) {
Matt Mackall5a021e92007-07-19 11:30:14 -0700738 /* If we're limited, always leave two wakeup worth's BITS */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739 int rsvd = r->limit ? 0 : random_read_wakeup_thresh/4;
Matt Mackall5a021e92007-07-19 11:30:14 -0700740 int bytes = nbytes;
741
742 /* pull at least as many as BYTES as wakeup BITS */
743 bytes = max_t(int, bytes, random_read_wakeup_thresh / 8);
744 /* but never more than the buffer size */
745 bytes = min_t(int, bytes, sizeof(tmp));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746
747 DEBUG_ENT("going to reseed %s with %d bits "
748 "(%d of %d requested)\n",
749 r->name, bytes * 8, nbytes * 8, r->entropy_count);
750
Matt Mackall90b75ee2008-04-29 01:02:55 -0700751 bytes = extract_entropy(r->pull, tmp, bytes,
752 random_read_wakeup_thresh / 8, rsvd);
Matt Mackalle68e5b62008-04-29 01:03:05 -0700753 mix_pool_bytes(r, tmp, bytes);
Matt Mackalladc782d2008-04-29 01:03:07 -0700754 credit_entropy_bits(r, bytes*8);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755 }
756}
757
758/*
759 * These functions extracts randomness from the "entropy pool", and
760 * returns it in a buffer.
761 *
762 * The min parameter specifies the minimum amount we can pull before
763 * failing to avoid races that defeat catastrophic reseeding while the
764 * reserved parameter indicates how much entropy we must leave in the
765 * pool after each pull to avoid starving other readers.
766 *
767 * Note: extract_entropy() assumes that .poolwords is a multiple of 16 words.
768 */
769
770static size_t account(struct entropy_store *r, size_t nbytes, int min,
771 int reserved)
772{
773 unsigned long flags;
774
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775 /* Hold lock while accounting */
776 spin_lock_irqsave(&r->lock, flags);
777
Matt Mackallcda796a2009-01-06 14:42:55 -0800778 BUG_ON(r->entropy_count > r->poolinfo->POOLBITS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779 DEBUG_ENT("trying to extract %d bits from %s\n",
780 nbytes * 8, r->name);
781
782 /* Can we pull enough? */
783 if (r->entropy_count / 8 < min + reserved) {
784 nbytes = 0;
785 } else {
786 /* If limited, never pull more than available */
787 if (r->limit && nbytes + reserved >= r->entropy_count / 8)
788 nbytes = r->entropy_count/8 - reserved;
789
Matt Mackall90b75ee2008-04-29 01:02:55 -0700790 if (r->entropy_count / 8 >= nbytes + reserved)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700791 r->entropy_count -= nbytes*8;
792 else
793 r->entropy_count = reserved;
794
Jeff Dike9a6f70b2008-04-29 01:03:08 -0700795 if (r->entropy_count < random_write_wakeup_thresh) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700796 wake_up_interruptible(&random_write_wait);
Jeff Dike9a6f70b2008-04-29 01:03:08 -0700797 kill_fasync(&fasync, SIGIO, POLL_OUT);
798 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799 }
800
801 DEBUG_ENT("debiting %d entropy credits from %s%s\n",
802 nbytes * 8, r->name, r->limit ? "" : " (unlimited)");
803
804 spin_unlock_irqrestore(&r->lock, flags);
805
806 return nbytes;
807}
808
809static void extract_buf(struct entropy_store *r, __u8 *out)
810{
Matt Mackall602b6ae2007-05-29 21:54:27 -0500811 int i;
Matt Mackalle68e5b62008-04-29 01:03:05 -0700812 __u32 hash[5], workspace[SHA_WORKSPACE_WORDS];
813 __u8 extract[64];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700814
Matt Mackall1c0ad3d2008-04-29 01:03:00 -0700815 /* Generate a hash across the pool, 16 words (512 bits) at a time */
Matt Mackallffd8d3f2008-04-29 01:02:59 -0700816 sha_init(hash);
Matt Mackall1c0ad3d2008-04-29 01:03:00 -0700817 for (i = 0; i < r->poolinfo->poolwords; i += 16)
Matt Mackallffd8d3f2008-04-29 01:02:59 -0700818 sha_transform(hash, (__u8 *)(r->pool + i), workspace);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819
820 /*
Matt Mackall1c0ad3d2008-04-29 01:03:00 -0700821 * We mix the hash back into the pool to prevent backtracking
822 * attacks (where the attacker knows the state of the pool
823 * plus the current outputs, and attempts to find previous
824 * ouputs), unless the hash function can be inverted. By
825 * mixing at least a SHA1 worth of hash data back, we make
826 * brute-forcing the feedback as hard as brute-forcing the
827 * hash.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828 */
Matt Mackalle68e5b62008-04-29 01:03:05 -0700829 mix_pool_bytes_extract(r, hash, sizeof(hash), extract);
Matt Mackall1c0ad3d2008-04-29 01:03:00 -0700830
831 /*
832 * To avoid duplicates, we atomically extract a portion of the
833 * pool while mixing, and hash one final time.
834 */
Matt Mackalle68e5b62008-04-29 01:03:05 -0700835 sha_transform(hash, extract, workspace);
Matt Mackallffd8d3f2008-04-29 01:02:59 -0700836 memset(extract, 0, sizeof(extract));
837 memset(workspace, 0, sizeof(workspace));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838
839 /*
Matt Mackall1c0ad3d2008-04-29 01:03:00 -0700840 * In case the hash function has some recognizable output
841 * pattern, we fold it in half. Thus, we always feed back
842 * twice as much data as we output.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843 */
Matt Mackallffd8d3f2008-04-29 01:02:59 -0700844 hash[0] ^= hash[3];
845 hash[1] ^= hash[4];
846 hash[2] ^= rol32(hash[2], 16);
847 memcpy(out, hash, EXTRACT_SIZE);
848 memset(hash, 0, sizeof(hash));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700849}
850
Matt Mackall90b75ee2008-04-29 01:02:55 -0700851static ssize_t extract_entropy(struct entropy_store *r, void *buf,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700852 size_t nbytes, int min, int reserved)
853{
854 ssize_t ret = 0, i;
855 __u8 tmp[EXTRACT_SIZE];
Neil Horman5b739ef2009-06-18 19:50:21 +0800856 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857
858 xfer_secondary_pool(r, nbytes);
859 nbytes = account(r, nbytes, min, reserved);
860
861 while (nbytes) {
862 extract_buf(r, tmp);
Neil Horman5b739ef2009-06-18 19:50:21 +0800863
Matt Mackalle954bc92010-05-20 19:55:01 +1000864 if (fips_enabled) {
Neil Horman5b739ef2009-06-18 19:50:21 +0800865 spin_lock_irqsave(&r->lock, flags);
866 if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
867 panic("Hardware RNG duplicated output!\n");
868 memcpy(r->last_data, tmp, EXTRACT_SIZE);
869 spin_unlock_irqrestore(&r->lock, flags);
870 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700871 i = min_t(int, nbytes, EXTRACT_SIZE);
872 memcpy(buf, tmp, i);
873 nbytes -= i;
874 buf += i;
875 ret += i;
876 }
877
878 /* Wipe data just returned from memory */
879 memset(tmp, 0, sizeof(tmp));
880
881 return ret;
882}
883
884static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
885 size_t nbytes)
886{
887 ssize_t ret = 0, i;
888 __u8 tmp[EXTRACT_SIZE];
889
890 xfer_secondary_pool(r, nbytes);
891 nbytes = account(r, nbytes, 0, 0);
892
893 while (nbytes) {
894 if (need_resched()) {
895 if (signal_pending(current)) {
896 if (ret == 0)
897 ret = -ERESTARTSYS;
898 break;
899 }
900 schedule();
901 }
902
903 extract_buf(r, tmp);
904 i = min_t(int, nbytes, EXTRACT_SIZE);
905 if (copy_to_user(buf, tmp, i)) {
906 ret = -EFAULT;
907 break;
908 }
909
910 nbytes -= i;
911 buf += i;
912 ret += i;
913 }
914
915 /* Wipe data just returned from memory */
916 memset(tmp, 0, sizeof(tmp));
917
918 return ret;
919}
920
921/*
922 * This function is the exported kernel interface. It returns some
923 * number of good random numbers, suitable for seeding TCP sequence
924 * numbers, etc.
925 */
926void get_random_bytes(void *buf, int nbytes)
927{
928 extract_entropy(&nonblocking_pool, buf, nbytes, 0, 0);
929}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930EXPORT_SYMBOL(get_random_bytes);
931
932/*
933 * init_std_data - initialize pool with system data
934 *
935 * @r: pool to initialize
936 *
937 * This function clears the pool's entropy count and mixes some system
938 * data into the pool to prepare it for use. The pool is not cleared
939 * as that can only decrease the entropy in the pool.
940 */
941static void init_std_data(struct entropy_store *r)
942{
Eric Dumazetf8595812007-03-28 14:22:33 -0700943 ktime_t now;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944 unsigned long flags;
945
946 spin_lock_irqsave(&r->lock, flags);
947 r->entropy_count = 0;
948 spin_unlock_irqrestore(&r->lock, flags);
949
Eric Dumazetf8595812007-03-28 14:22:33 -0700950 now = ktime_get_real();
Matt Mackalle68e5b62008-04-29 01:03:05 -0700951 mix_pool_bytes(r, &now, sizeof(now));
952 mix_pool_bytes(r, utsname(), sizeof(*(utsname())));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700953}
954
Matt Mackall53c3f632008-04-29 01:02:58 -0700955static int rand_initialize(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700956{
957 init_std_data(&input_pool);
958 init_std_data(&blocking_pool);
959 init_std_data(&nonblocking_pool);
960 return 0;
961}
962module_init(rand_initialize);
963
964void rand_initialize_irq(int irq)
965{
966 struct timer_rand_state *state;
967
Yinghai Lu3060d6f2008-08-19 20:50:08 -0700968 state = get_timer_rand_state(irq);
969
970 if (state)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700971 return;
972
973 /*
Eric Dumazetf8595812007-03-28 14:22:33 -0700974 * If kzalloc returns null, we just won't use that entropy
Linus Torvalds1da177e2005-04-16 15:20:36 -0700975 * source.
976 */
Eric Dumazetf8595812007-03-28 14:22:33 -0700977 state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
978 if (state)
Yinghai Lu3060d6f2008-08-19 20:50:08 -0700979 set_timer_rand_state(irq, state);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980}
981
David Howells93614012006-09-30 20:45:40 +0200982#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983void rand_initialize_disk(struct gendisk *disk)
984{
985 struct timer_rand_state *state;
986
987 /*
Eric Dumazetf8595812007-03-28 14:22:33 -0700988 * If kzalloc returns null, we just won't use that entropy
Linus Torvalds1da177e2005-04-16 15:20:36 -0700989 * source.
990 */
Eric Dumazetf8595812007-03-28 14:22:33 -0700991 state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
992 if (state)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700993 disk->random = state;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700994}
David Howells93614012006-09-30 20:45:40 +0200995#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700996
997static ssize_t
Matt Mackall90b75ee2008-04-29 01:02:55 -0700998random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999{
1000 ssize_t n, retval = 0, count = 0;
1001
1002 if (nbytes == 0)
1003 return 0;
1004
1005 while (nbytes > 0) {
1006 n = nbytes;
1007 if (n > SEC_XFER_SIZE)
1008 n = SEC_XFER_SIZE;
1009
1010 DEBUG_ENT("reading %d bits\n", n*8);
1011
1012 n = extract_entropy_user(&blocking_pool, buf, n);
1013
1014 DEBUG_ENT("read got %d bits (%d still needed)\n",
1015 n*8, (nbytes-n)*8);
1016
1017 if (n == 0) {
1018 if (file->f_flags & O_NONBLOCK) {
1019 retval = -EAGAIN;
1020 break;
1021 }
1022
1023 DEBUG_ENT("sleeping?\n");
1024
1025 wait_event_interruptible(random_read_wait,
1026 input_pool.entropy_count >=
1027 random_read_wakeup_thresh);
1028
1029 DEBUG_ENT("awake\n");
1030
1031 if (signal_pending(current)) {
1032 retval = -ERESTARTSYS;
1033 break;
1034 }
1035
1036 continue;
1037 }
1038
1039 if (n < 0) {
1040 retval = n;
1041 break;
1042 }
1043 count += n;
1044 buf += n;
1045 nbytes -= n;
1046 break; /* This break makes the device work */
1047 /* like a named pipe */
1048 }
1049
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050 return (count ? count : retval);
1051}
1052
1053static ssize_t
Matt Mackall90b75ee2008-04-29 01:02:55 -07001054urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055{
1056 return extract_entropy_user(&nonblocking_pool, buf, nbytes);
1057}
1058
1059static unsigned int
1060random_poll(struct file *file, poll_table * wait)
1061{
1062 unsigned int mask;
1063
1064 poll_wait(file, &random_read_wait, wait);
1065 poll_wait(file, &random_write_wait, wait);
1066 mask = 0;
1067 if (input_pool.entropy_count >= random_read_wakeup_thresh)
1068 mask |= POLLIN | POLLRDNORM;
1069 if (input_pool.entropy_count < random_write_wakeup_thresh)
1070 mask |= POLLOUT | POLLWRNORM;
1071 return mask;
1072}
1073
Matt Mackall7f397dc2007-05-29 21:58:10 -05001074static int
1075write_pool(struct entropy_store *r, const char __user *buffer, size_t count)
1076{
1077 size_t bytes;
1078 __u32 buf[16];
1079 const char __user *p = buffer;
1080
1081 while (count > 0) {
1082 bytes = min(count, sizeof(buf));
1083 if (copy_from_user(&buf, p, bytes))
1084 return -EFAULT;
1085
1086 count -= bytes;
1087 p += bytes;
1088
Matt Mackalle68e5b62008-04-29 01:03:05 -07001089 mix_pool_bytes(r, buf, bytes);
Matt Mackall91f3f1e2008-02-06 01:37:20 -08001090 cond_resched();
Matt Mackall7f397dc2007-05-29 21:58:10 -05001091 }
1092
1093 return 0;
1094}
1095
Matt Mackall90b75ee2008-04-29 01:02:55 -07001096static ssize_t random_write(struct file *file, const char __user *buffer,
1097 size_t count, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001098{
Matt Mackall7f397dc2007-05-29 21:58:10 -05001099 size_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001100
Matt Mackall7f397dc2007-05-29 21:58:10 -05001101 ret = write_pool(&blocking_pool, buffer, count);
1102 if (ret)
1103 return ret;
1104 ret = write_pool(&nonblocking_pool, buffer, count);
1105 if (ret)
1106 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001107
Matt Mackall7f397dc2007-05-29 21:58:10 -05001108 return (ssize_t)count;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001109}
1110
Matt Mackall43ae4862008-04-29 01:02:58 -07001111static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001112{
1113 int size, ent_count;
1114 int __user *p = (int __user *)arg;
1115 int retval;
1116
1117 switch (cmd) {
1118 case RNDGETENTCNT:
Matt Mackall43ae4862008-04-29 01:02:58 -07001119 /* inherently racy, no point locking */
1120 if (put_user(input_pool.entropy_count, p))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001121 return -EFAULT;
1122 return 0;
1123 case RNDADDTOENTCNT:
1124 if (!capable(CAP_SYS_ADMIN))
1125 return -EPERM;
1126 if (get_user(ent_count, p))
1127 return -EFAULT;
Matt Mackalladc782d2008-04-29 01:03:07 -07001128 credit_entropy_bits(&input_pool, ent_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129 return 0;
1130 case RNDADDENTROPY:
1131 if (!capable(CAP_SYS_ADMIN))
1132 return -EPERM;
1133 if (get_user(ent_count, p++))
1134 return -EFAULT;
1135 if (ent_count < 0)
1136 return -EINVAL;
1137 if (get_user(size, p++))
1138 return -EFAULT;
Matt Mackall7f397dc2007-05-29 21:58:10 -05001139 retval = write_pool(&input_pool, (const char __user *)p,
1140 size);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141 if (retval < 0)
1142 return retval;
Matt Mackalladc782d2008-04-29 01:03:07 -07001143 credit_entropy_bits(&input_pool, ent_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001144 return 0;
1145 case RNDZAPENTCNT:
1146 case RNDCLEARPOOL:
1147 /* Clear the entropy pool counters. */
1148 if (!capable(CAP_SYS_ADMIN))
1149 return -EPERM;
Matt Mackall53c3f632008-04-29 01:02:58 -07001150 rand_initialize();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001151 return 0;
1152 default:
1153 return -EINVAL;
1154 }
1155}
1156
Jeff Dike9a6f70b2008-04-29 01:03:08 -07001157static int random_fasync(int fd, struct file *filp, int on)
1158{
1159 return fasync_helper(fd, filp, on, &fasync);
1160}
1161
Arjan van de Ven2b8693c2007-02-12 00:55:32 -08001162const struct file_operations random_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163 .read = random_read,
1164 .write = random_write,
1165 .poll = random_poll,
Matt Mackall43ae4862008-04-29 01:02:58 -07001166 .unlocked_ioctl = random_ioctl,
Jeff Dike9a6f70b2008-04-29 01:03:08 -07001167 .fasync = random_fasync,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001168};
1169
Arjan van de Ven2b8693c2007-02-12 00:55:32 -08001170const struct file_operations urandom_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001171 .read = urandom_read,
1172 .write = random_write,
Matt Mackall43ae4862008-04-29 01:02:58 -07001173 .unlocked_ioctl = random_ioctl,
Jeff Dike9a6f70b2008-04-29 01:03:08 -07001174 .fasync = random_fasync,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175};
1176
1177/***************************************************************
1178 * Random UUID interface
1179 *
1180 * Used here for a Boot ID, but can be useful for other kernel
1181 * drivers.
1182 ***************************************************************/
1183
1184/*
1185 * Generate random UUID
1186 */
1187void generate_random_uuid(unsigned char uuid_out[16])
1188{
1189 get_random_bytes(uuid_out, 16);
Adam Buchbinderc41b20e2009-12-11 16:35:39 -05001190 /* Set UUID version to 4 --- truly random generation */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191 uuid_out[6] = (uuid_out[6] & 0x0F) | 0x40;
1192 /* Set the UUID variant to DCE */
1193 uuid_out[8] = (uuid_out[8] & 0x3F) | 0x80;
1194}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195EXPORT_SYMBOL(generate_random_uuid);
1196
1197/********************************************************************
1198 *
1199 * Sysctl interface
1200 *
1201 ********************************************************************/
1202
1203#ifdef CONFIG_SYSCTL
1204
1205#include <linux/sysctl.h>
1206
1207static int min_read_thresh = 8, min_write_thresh;
1208static int max_read_thresh = INPUT_POOL_WORDS * 32;
1209static int max_write_thresh = INPUT_POOL_WORDS * 32;
1210static char sysctl_bootid[16];
1211
1212/*
1213 * These functions is used to return both the bootid UUID, and random
1214 * UUID. The difference is in whether table->data is NULL; if it is,
1215 * then a new UUID is generated and returned to the user.
1216 *
1217 * If the user accesses this via the proc interface, it will be returned
1218 * as an ASCII string in the standard UUID format. If accesses via the
1219 * sysctl system call, it is returned as 16 bytes of binary data.
1220 */
Alexey Dobriyan8d65af72009-09-23 15:57:19 -07001221static int proc_do_uuid(ctl_table *table, int write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001222 void __user *buffer, size_t *lenp, loff_t *ppos)
1223{
1224 ctl_table fake_table;
1225 unsigned char buf[64], tmp_uuid[16], *uuid;
1226
1227 uuid = table->data;
1228 if (!uuid) {
1229 uuid = tmp_uuid;
1230 uuid[8] = 0;
1231 }
1232 if (uuid[8] == 0)
1233 generate_random_uuid(uuid);
1234
Joe Perches35900772009-12-14 18:01:11 -08001235 sprintf(buf, "%pU", uuid);
1236
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237 fake_table.data = buf;
1238 fake_table.maxlen = sizeof(buf);
1239
Alexey Dobriyan8d65af72009-09-23 15:57:19 -07001240 return proc_dostring(&fake_table, write, buffer, lenp, ppos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001241}
1242
Linus Torvalds1da177e2005-04-16 15:20:36 -07001243static int sysctl_poolsize = INPUT_POOL_WORDS * 32;
1244ctl_table random_table[] = {
1245 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001246 .procname = "poolsize",
1247 .data = &sysctl_poolsize,
1248 .maxlen = sizeof(int),
1249 .mode = 0444,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001250 .proc_handler = proc_dointvec,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001251 },
1252 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001253 .procname = "entropy_avail",
1254 .maxlen = sizeof(int),
1255 .mode = 0444,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001256 .proc_handler = proc_dointvec,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001257 .data = &input_pool.entropy_count,
1258 },
1259 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001260 .procname = "read_wakeup_threshold",
1261 .data = &random_read_wakeup_thresh,
1262 .maxlen = sizeof(int),
1263 .mode = 0644,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001264 .proc_handler = proc_dointvec_minmax,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001265 .extra1 = &min_read_thresh,
1266 .extra2 = &max_read_thresh,
1267 },
1268 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001269 .procname = "write_wakeup_threshold",
1270 .data = &random_write_wakeup_thresh,
1271 .maxlen = sizeof(int),
1272 .mode = 0644,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001273 .proc_handler = proc_dointvec_minmax,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001274 .extra1 = &min_write_thresh,
1275 .extra2 = &max_write_thresh,
1276 },
1277 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001278 .procname = "boot_id",
1279 .data = &sysctl_bootid,
1280 .maxlen = 16,
1281 .mode = 0444,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001282 .proc_handler = proc_do_uuid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001283 },
1284 {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285 .procname = "uuid",
1286 .maxlen = 16,
1287 .mode = 0444,
Eric W. Biederman6d456112009-11-16 03:11:48 -08001288 .proc_handler = proc_do_uuid,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289 },
Eric W. Biederman894d2492009-11-05 14:34:02 -08001290 { }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001291};
1292#endif /* CONFIG_SYSCTL */
1293
1294/********************************************************************
1295 *
Joe Perches35900772009-12-14 18:01:11 -08001296 * Random functions for networking
Linus Torvalds1da177e2005-04-16 15:20:36 -07001297 *
1298 ********************************************************************/
1299
1300/*
1301 * TCP initial sequence number picking. This uses the random number
1302 * generator to pick an initial secret value. This value is hashed
1303 * along with the TCP endpoint information to provide a unique
1304 * starting point for each pair of TCP endpoints. This defeats
1305 * attacks which rely on guessing the initial TCP sequence number.
1306 * This algorithm was suggested by Steve Bellovin.
1307 *
1308 * Using a very strong hash was taking an appreciable amount of the total
1309 * TCP connection establishment time, so this is a weaker hash,
1310 * compensated for by changing the secret periodically.
1311 */
1312
1313/* F, G and H are basic MD4 functions: selection, majority, parity */
1314#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
1315#define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
1316#define H(x, y, z) ((x) ^ (y) ^ (z))
1317
1318/*
1319 * The generic round function. The application is so specific that
1320 * we don't bother protecting all the arguments with parens, as is generally
1321 * good macro practice, in favor of extra legibility.
1322 * Rotation is separate from addition to prevent recomputation
1323 */
1324#define ROUND(f, a, b, c, d, x, s) \
1325 (a += f(b, c, d) + x, a = (a << s) | (a >> (32 - s)))
1326#define K1 0
1327#define K2 013240474631UL
1328#define K3 015666365641UL
1329
1330#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
1331
Matt Mackall90b75ee2008-04-29 01:02:55 -07001332static __u32 twothirdsMD4Transform(__u32 const buf[4], __u32 const in[12])
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333{
1334 __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
1335
1336 /* Round 1 */
1337 ROUND(F, a, b, c, d, in[ 0] + K1, 3);
1338 ROUND(F, d, a, b, c, in[ 1] + K1, 7);
1339 ROUND(F, c, d, a, b, in[ 2] + K1, 11);
1340 ROUND(F, b, c, d, a, in[ 3] + K1, 19);
1341 ROUND(F, a, b, c, d, in[ 4] + K1, 3);
1342 ROUND(F, d, a, b, c, in[ 5] + K1, 7);
1343 ROUND(F, c, d, a, b, in[ 6] + K1, 11);
1344 ROUND(F, b, c, d, a, in[ 7] + K1, 19);
1345 ROUND(F, a, b, c, d, in[ 8] + K1, 3);
1346 ROUND(F, d, a, b, c, in[ 9] + K1, 7);
1347 ROUND(F, c, d, a, b, in[10] + K1, 11);
1348 ROUND(F, b, c, d, a, in[11] + K1, 19);
1349
1350 /* Round 2 */
1351 ROUND(G, a, b, c, d, in[ 1] + K2, 3);
1352 ROUND(G, d, a, b, c, in[ 3] + K2, 5);
1353 ROUND(G, c, d, a, b, in[ 5] + K2, 9);
1354 ROUND(G, b, c, d, a, in[ 7] + K2, 13);
1355 ROUND(G, a, b, c, d, in[ 9] + K2, 3);
1356 ROUND(G, d, a, b, c, in[11] + K2, 5);
1357 ROUND(G, c, d, a, b, in[ 0] + K2, 9);
1358 ROUND(G, b, c, d, a, in[ 2] + K2, 13);
1359 ROUND(G, a, b, c, d, in[ 4] + K2, 3);
1360 ROUND(G, d, a, b, c, in[ 6] + K2, 5);
1361 ROUND(G, c, d, a, b, in[ 8] + K2, 9);
1362 ROUND(G, b, c, d, a, in[10] + K2, 13);
1363
1364 /* Round 3 */
1365 ROUND(H, a, b, c, d, in[ 3] + K3, 3);
1366 ROUND(H, d, a, b, c, in[ 7] + K3, 9);
1367 ROUND(H, c, d, a, b, in[11] + K3, 11);
1368 ROUND(H, b, c, d, a, in[ 2] + K3, 15);
1369 ROUND(H, a, b, c, d, in[ 6] + K3, 3);
1370 ROUND(H, d, a, b, c, in[10] + K3, 9);
1371 ROUND(H, c, d, a, b, in[ 1] + K3, 11);
1372 ROUND(H, b, c, d, a, in[ 5] + K3, 15);
1373 ROUND(H, a, b, c, d, in[ 9] + K3, 3);
1374 ROUND(H, d, a, b, c, in[ 0] + K3, 9);
1375 ROUND(H, c, d, a, b, in[ 4] + K3, 11);
1376 ROUND(H, b, c, d, a, in[ 8] + K3, 15);
1377
1378 return buf[1] + b; /* "most hashed" word */
1379 /* Alternative: return sum of all words? */
1380}
1381#endif
1382
1383#undef ROUND
1384#undef F
1385#undef G
1386#undef H
1387#undef K1
1388#undef K2
1389#undef K3
1390
1391/* This should not be decreased so low that ISNs wrap too fast. */
1392#define REKEY_INTERVAL (300 * HZ)
1393/*
1394 * Bit layout of the tcp sequence numbers (before adding current time):
1395 * bit 24-31: increased after every key exchange
1396 * bit 0-23: hash(source,dest)
1397 *
1398 * The implementation is similar to the algorithm described
1399 * in the Appendix of RFC 1185, except that
1400 * - it uses a 1 MHz clock instead of a 250 kHz clock
1401 * - it performs a rekey every 5 minutes, which is equivalent
1402 * to a (source,dest) tulple dependent forward jump of the
1403 * clock by 0..2^(HASH_BITS+1)
1404 *
1405 * Thus the average ISN wraparound time is 68 minutes instead of
1406 * 4.55 hours.
1407 *
1408 * SMP cleanup and lock avoidance with poor man's RCU.
1409 * Manfred Spraul <manfred@colorfullife.com>
1410 *
1411 */
1412#define COUNT_BITS 8
1413#define COUNT_MASK ((1 << COUNT_BITS) - 1)
1414#define HASH_BITS 24
1415#define HASH_MASK ((1 << HASH_BITS) - 1)
1416
1417static struct keydata {
1418 __u32 count; /* already shifted to the final position */
1419 __u32 secret[12];
1420} ____cacheline_aligned ip_keydata[2];
1421
1422static unsigned int ip_cnt;
1423
David Howells65f27f32006-11-22 14:55:48 +00001424static void rekey_seq_generator(struct work_struct *work);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425
David Howells65f27f32006-11-22 14:55:48 +00001426static DECLARE_DELAYED_WORK(rekey_work, rekey_seq_generator);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001427
1428/*
1429 * Lock avoidance:
1430 * The ISN generation runs lockless - it's just a hash over random data.
1431 * State changes happen every 5 minutes when the random key is replaced.
1432 * Synchronization is performed by having two copies of the hash function
1433 * state and rekey_seq_generator always updates the inactive copy.
1434 * The copy is then activated by updating ip_cnt.
1435 * The implementation breaks down if someone blocks the thread
1436 * that processes SYN requests for more than 5 minutes. Should never
1437 * happen, and even if that happens only a not perfectly compliant
1438 * ISN is generated, nothing fatal.
1439 */
David Howells65f27f32006-11-22 14:55:48 +00001440static void rekey_seq_generator(struct work_struct *work)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001441{
1442 struct keydata *keyptr = &ip_keydata[1 ^ (ip_cnt & 1)];
1443
1444 get_random_bytes(keyptr->secret, sizeof(keyptr->secret));
1445 keyptr->count = (ip_cnt & COUNT_MASK) << HASH_BITS;
1446 smp_wmb();
1447 ip_cnt++;
Anton Blanchard417b43d2009-04-02 16:56:39 -07001448 schedule_delayed_work(&rekey_work,
1449 round_jiffies_relative(REKEY_INTERVAL));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001450}
1451
1452static inline struct keydata *get_keyptr(void)
1453{
1454 struct keydata *keyptr = &ip_keydata[ip_cnt & 1];
1455
1456 smp_rmb();
1457
1458 return keyptr;
1459}
1460
1461static __init int seqgen_init(void)
1462{
1463 rekey_seq_generator(NULL);
1464 return 0;
1465}
1466late_initcall(seqgen_init);
1467
1468#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
Al Virob09b845c2006-11-14 20:52:19 -08001469__u32 secure_tcpv6_sequence_number(__be32 *saddr, __be32 *daddr,
1470 __be16 sport, __be16 dport)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001472 __u32 seq;
1473 __u32 hash[12];
1474 struct keydata *keyptr = get_keyptr();
1475
1476 /* The procedure is the same as for IPv4, but addresses are longer.
1477 * Thus we must use twothirdsMD4Transform.
1478 */
1479
1480 memcpy(hash, saddr, 16);
Matt Mackall90b75ee2008-04-29 01:02:55 -07001481 hash[4] = ((__force u16)sport << 16) + (__force u16)dport;
1482 memcpy(&hash[5], keyptr->secret, sizeof(__u32) * 7);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001483
Al Virob09b845c2006-11-14 20:52:19 -08001484 seq = twothirdsMD4Transform((const __u32 *)daddr, hash) & HASH_MASK;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001485 seq += keyptr->count;
1486
Eric Dumazet6dd10a62007-11-13 21:12:14 -08001487 seq += ktime_to_ns(ktime_get_real());
Linus Torvalds1da177e2005-04-16 15:20:36 -07001488
1489 return seq;
1490}
1491EXPORT_SYMBOL(secure_tcpv6_sequence_number);
1492#endif
1493
1494/* The code below is shamelessly stolen from secure_tcp_sequence_number().
1495 * All blames to Andrey V. Savochkin <saw@msu.ru>.
1496 */
Al Virob09b845c2006-11-14 20:52:19 -08001497__u32 secure_ip_id(__be32 daddr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001498{
1499 struct keydata *keyptr;
1500 __u32 hash[4];
1501
1502 keyptr = get_keyptr();
1503
1504 /*
1505 * Pick a unique starting offset for each IP destination.
1506 * The dest ip address is placed in the starting vector,
1507 * which is then hashed with random data.
1508 */
Al Virob09b845c2006-11-14 20:52:19 -08001509 hash[0] = (__force __u32)daddr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001510 hash[1] = keyptr->secret[9];
1511 hash[2] = keyptr->secret[10];
1512 hash[3] = keyptr->secret[11];
1513
1514 return half_md4_transform(hash, keyptr->secret);
1515}
1516
1517#ifdef CONFIG_INET
1518
Al Virob09b845c2006-11-14 20:52:19 -08001519__u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
1520 __be16 sport, __be16 dport)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001521{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001522 __u32 seq;
1523 __u32 hash[4];
1524 struct keydata *keyptr = get_keyptr();
1525
1526 /*
1527 * Pick a unique starting offset for each TCP connection endpoints
1528 * (saddr, daddr, sport, dport).
1529 * Note that the words are placed into the starting vector, which is
1530 * then mixed with a partial MD4 over random data.
1531 */
Matt Mackall90b75ee2008-04-29 01:02:55 -07001532 hash[0] = (__force u32)saddr;
1533 hash[1] = (__force u32)daddr;
1534 hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
1535 hash[3] = keyptr->secret[11];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536
1537 seq = half_md4_transform(hash, keyptr->secret) & HASH_MASK;
1538 seq += keyptr->count;
1539 /*
1540 * As close as possible to RFC 793, which
1541 * suggests using a 250 kHz clock.
1542 * Further reading shows this assumes 2 Mb/s networks.
Eric Dumazet9b42c332007-10-01 13:58:36 -07001543 * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
1544 * For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but
1545 * we also need to limit the resolution so that the u32 seq
1546 * overlaps less than one time per MSL (2 minutes).
1547 * Choosing a clock of 64 ns period is OK. (period of 274 s)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548 */
Eric Dumazet6dd10a62007-11-13 21:12:14 -08001549 seq += ktime_to_ns(ktime_get_real()) >> 6;
Matt Mackall90b75ee2008-04-29 01:02:55 -07001550
Linus Torvalds1da177e2005-04-16 15:20:36 -07001551 return seq;
1552}
1553
Arnaldo Carvalho de Meloa7f5e7f2005-12-13 23:25:31 -08001554/* Generate secure starting point for ephemeral IPV4 transport port search */
Al Virob09b845c2006-11-14 20:52:19 -08001555u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556{
1557 struct keydata *keyptr = get_keyptr();
1558 u32 hash[4];
1559
1560 /*
1561 * Pick a unique starting offset for each ephemeral port search
1562 * (saddr, daddr, dport) and 48bits of random data.
1563 */
Al Virob09b845c2006-11-14 20:52:19 -08001564 hash[0] = (__force u32)saddr;
1565 hash[1] = (__force u32)daddr;
1566 hash[2] = (__force u32)dport ^ keyptr->secret[10];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001567 hash[3] = keyptr->secret[11];
1568
1569 return half_md4_transform(hash, keyptr->secret);
1570}
Stephen Hemminger9f593652008-08-18 21:32:32 -07001571EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001572
1573#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
Matt Mackall90b75ee2008-04-29 01:02:55 -07001574u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
1575 __be16 dport)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001576{
1577 struct keydata *keyptr = get_keyptr();
1578 u32 hash[12];
1579
1580 memcpy(hash, saddr, 16);
Al Virob09b845c2006-11-14 20:52:19 -08001581 hash[4] = (__force u32)dport;
Matt Mackall90b75ee2008-04-29 01:02:55 -07001582 memcpy(&hash[5], keyptr->secret, sizeof(__u32) * 7);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001583
Al Virob09b845c2006-11-14 20:52:19 -08001584 return twothirdsMD4Transform((const __u32 *)daddr, hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001585}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001586#endif
1587
Arnaldo Carvalho de Meloc4365c92005-08-09 20:12:30 -07001588#if defined(CONFIG_IP_DCCP) || defined(CONFIG_IP_DCCP_MODULE)
1589/* Similar to secure_tcp_sequence_number but generate a 48 bit value
1590 * bit's 32-47 increase every key exchange
1591 * 0-31 hash(source, dest)
1592 */
Al Virob09b845c2006-11-14 20:52:19 -08001593u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
1594 __be16 sport, __be16 dport)
Arnaldo Carvalho de Meloc4365c92005-08-09 20:12:30 -07001595{
Arnaldo Carvalho de Meloc4365c92005-08-09 20:12:30 -07001596 u64 seq;
1597 __u32 hash[4];
1598 struct keydata *keyptr = get_keyptr();
1599
Al Virob09b845c2006-11-14 20:52:19 -08001600 hash[0] = (__force u32)saddr;
1601 hash[1] = (__force u32)daddr;
1602 hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
Arnaldo Carvalho de Meloc4365c92005-08-09 20:12:30 -07001603 hash[3] = keyptr->secret[11];
1604
1605 seq = half_md4_transform(hash, keyptr->secret);
1606 seq |= ((u64)keyptr->count) << (32 - HASH_BITS);
1607
Eric Dumazet6dd10a62007-11-13 21:12:14 -08001608 seq += ktime_to_ns(ktime_get_real());
Arnaldo Carvalho de Meloc4365c92005-08-09 20:12:30 -07001609 seq &= (1ull << 48) - 1;
Matt Mackall90b75ee2008-04-29 01:02:55 -07001610
Arnaldo Carvalho de Meloc4365c92005-08-09 20:12:30 -07001611 return seq;
1612}
Arnaldo Carvalho de Meloc4365c92005-08-09 20:12:30 -07001613EXPORT_SYMBOL(secure_dccp_sequence_number);
1614#endif
1615
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616#endif /* CONFIG_INET */
1617
1618
1619/*
1620 * Get a random word for internal kernel use only. Similar to urandom but
1621 * with the goal of minimal entropy pool depletion. As a result, the random
1622 * value is not cryptographically secure but for several uses the cost of
1623 * depleting entropy is too high
1624 */
Linus Torvalds8a0a9bd2009-05-05 08:17:43 -07001625DEFINE_PER_CPU(__u32 [4], get_random_int_hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626unsigned int get_random_int(void)
1627{
Linus Torvalds8a0a9bd2009-05-05 08:17:43 -07001628 struct keydata *keyptr;
1629 __u32 *hash = get_cpu_var(get_random_int_hash);
1630 int ret;
1631
1632 keyptr = get_keyptr();
Linus Torvalds26a9a412009-05-19 11:25:35 -07001633 hash[0] += current->pid + jiffies + get_cycles();
Linus Torvalds8a0a9bd2009-05-05 08:17:43 -07001634
1635 ret = half_md4_transform(hash, keyptr->secret);
1636 put_cpu_var(get_random_int_hash);
1637
1638 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001639}
1640
1641/*
1642 * randomize_range() returns a start address such that
1643 *
1644 * [...... <range> .....]
1645 * start end
1646 *
1647 * a <range> with size "len" starting at the return value is inside in the
1648 * area defined by [start, end], but is otherwise randomized.
1649 */
1650unsigned long
1651randomize_range(unsigned long start, unsigned long end, unsigned long len)
1652{
1653 unsigned long range = end - len - start;
1654
1655 if (end <= start + len)
1656 return 0;
1657 return PAGE_ALIGN(get_random_int() % range + start);
1658}