2 * random.c -- A strong random number generator
4 * Version 1.89, last modified 19-Sep-99
6 * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
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
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.)
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
43 * (now, with legal B.S. out of the way.....)
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.
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.
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.
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.
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
98 * Exported interfaces ---- output
99 * ===============================
101 * There are three exported interfaces; the first is one designed to
102 * be used from within the kernel:
104 * void get_random_bytes(void *buf, int nbytes);
106 * This interface will return the requested number of random bytes,
107 * and place it in the requested buffer.
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.
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.
122 * Exported interfaces ---- input
123 * ==============================
125 * The current exported interfaces for gathering environmental noise
126 * from the devices are:
128 * void add_keyboard_randomness(unsigned char scancode);
129 * void add_mouse_randomness(__u32 mouse_data);
130 * void add_interrupt_randomness(int irq);
132 * add_keyboard_randomness() uses the inter-keypress timing, as well as the
133 * scancode as random inputs into the "entropy pool".
135 * add_mouse_randomness() uses the mouse interrupt timing, as well as
136 * the reported position of the mouse from the hardware.
138 * add_interrupt_randomness() uses the inter-interrupt timing as random
139 * inputs to the entropy pool. Note that not all interrupts are good
140 * sources of randomness! For example, the timer interrupts is not a
141 * good choice, because the periodicity of the interrupts is too
142 * regular, and hence predictable to an attacker. Disk interrupts are
143 * a better measure, since the timing of the disk interrupts are more
146 * All of these routines try to estimate how many bits of randomness a
147 * particular randomness source. They do this by keeping track of the
148 * first and second order deltas of the event timings.
150 * Ensuring unpredictability at system startup
151 * ============================================
153 * When any operating system starts up, it will go through a sequence
154 * of actions that are fairly predictable by an adversary, especially
155 * if the start-up does not involve interaction with a human operator.
156 * This reduces the actual number of bits of unpredictability in the
157 * entropy pool below the value in entropy_count. In order to
158 * counteract this effect, it helps to carry information in the
159 * entropy pool across shut-downs and start-ups. To do this, put the
160 * following lines an appropriate script which is run during the boot
163 * echo "Initializing random number generator..."
164 * random_seed=/var/run/random-seed
165 * # Carry a random seed from start-up to start-up
166 * # Load and then save the whole entropy pool
167 * if [ -f $random_seed ]; then
168 * cat $random_seed >/dev/urandom
172 * chmod 600 $random_seed
173 * poolfile=/proc/sys/kernel/random/poolsize
174 * [ -r $poolfile ] && bytes=`cat $poolfile` || bytes=512
175 * dd if=/dev/urandom of=$random_seed count=1 bs=$bytes
177 * and the following lines in an appropriate script which is run as
178 * the system is shutdown:
180 * # Carry a random seed from shut-down to start-up
181 * # Save the whole entropy pool
182 * echo "Saving random seed..."
183 * random_seed=/var/run/random-seed
185 * chmod 600 $random_seed
186 * poolfile=/proc/sys/kernel/random/poolsize
187 * [ -r $poolfile ] && bytes=`cat $poolfile` || bytes=512
188 * dd if=/dev/urandom of=$random_seed count=1 bs=$bytes
190 * For example, on most modern systems using the System V init
191 * scripts, such code fragments would be found in
192 * /etc/rc.d/init.d/random. On older Linux systems, the correct script
193 * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0.
195 * Effectively, these commands cause the contents of the entropy pool
196 * to be saved at shut-down time and reloaded into the entropy pool at
197 * start-up. (The 'dd' in the addition to the bootup script is to
198 * make sure that /etc/random-seed is different for every start-up,
199 * even if the system crashes without executing rc.0.) Even with
200 * complete knowledge of the start-up activities, predicting the state
201 * of the entropy pool requires knowledge of the previous history of
204 * Configuring the /dev/random driver under Linux
205 * ==============================================
207 * The /dev/random driver under Linux uses minor numbers 8 and 9 of
208 * the /dev/mem major number (#1). So if your system does not have
209 * /dev/random and /dev/urandom created already, they can be created
210 * by using the commands:
212 * mknod /dev/random c 1 8
213 * mknod /dev/urandom c 1 9
218 * Ideas for constructing this random number generator were derived
219 * from Pretty Good Privacy's random number generator, and from private
220 * discussions with Phil Karn. Colin Plumb provided a faster random
221 * number generator, which speed up the mixing function of the entropy
222 * pool, taken from PGPfone. Dale Worley has also contributed many
223 * useful ideas and suggestions to improve this driver.
225 * Any flaws in the design are solely my responsibility, and should
226 * not be attributed to the Phil, Colin, or any of authors of PGP.
228 * The code for SHA transform was taken from Peter Gutmann's
229 * implementation, which has been placed in the public domain.
230 * The code for MD5 transform was taken from Colin Plumb's
231 * implementation, which has been placed in the public domain.
232 * The MD5 cryptographic checksum was devised by Ronald Rivest, and is
233 * documented in RFC 1321, "The MD5 Message Digest Algorithm".
235 * Further background information on this topic may be obtained from
236 * RFC 1750, "Randomness Recommendations for Security", by Donald
237 * Eastlake, Steve Crocker, and Jeff Schiller.
240 #include <linux/utsname.h>
241 #include <linux/config.h>
242 #include <linux/module.h>
243 #include <linux/kernel.h>
244 #include <linux/major.h>
245 #include <linux/string.h>
246 #include <linux/fcntl.h>
247 #include <linux/slab.h>
248 #include <linux/random.h>
249 #include <linux/poll.h>
250 #include <linux/init.h>
251 #include <linux/fs.h>
252 #include <linux/workqueue.h>
253 #include <linux/genhd.h>
254 #include <linux/interrupt.h>
255 #include <linux/spinlock.h>
256 #include <linux/percpu.h>
258 #include <asm/processor.h>
259 #include <asm/uaccess.h>
264 * Configuration information
266 #define DEFAULT_POOL_SIZE 512
267 #define SECONDARY_POOL_SIZE 128
268 #define BATCH_ENTROPY_SIZE 256
272 * The minimum number of bits of entropy before we wake up a read on
273 * /dev/random. Should be enough to do a significant reseed.
275 static int random_read_wakeup_thresh = 64;
278 * If the entropy count falls under this number of bits, then we
279 * should wake up processes which are selecting or polling on write
280 * access to /dev/random.
282 static int random_write_wakeup_thresh = 128;
285 * When the input pool goes over trickle_thresh, start dropping most
286 * samples to avoid wasting CPU time and reduce lock contention.
289 static int trickle_thresh = DEFAULT_POOL_SIZE * 7;
291 static DEFINE_PER_CPU(int, trickle_count) = 0;
294 * A pool of size .poolwords is stirred with a primitive polynomial
295 * of degree .poolwords over GF(2). The taps for various sizes are
296 * defined below. They are chosen to be evenly spaced (minimum RMS
297 * distance from evenly spaced; the numbers in the comments are a
298 * scaled squared error sum) except for the last tap, which is 1 to
299 * get the twisting happening as fast as possible.
301 static struct poolinfo {
303 int tap1, tap2, tap3, tap4, tap5;
304 } poolinfo_table[] = {
305 /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */
306 { 2048, 1638, 1231, 819, 411, 1 },
308 /* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */
309 { 1024, 817, 615, 412, 204, 1 },
310 #if 0 /* Alternate polynomial */
311 /* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */
312 { 1024, 819, 616, 410, 207, 2 },
315 /* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */
316 { 512, 411, 308, 208, 104, 1 },
317 #if 0 /* Alternates */
318 /* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */
319 { 512, 409, 307, 206, 102, 2 },
320 /* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */
321 { 512, 409, 309, 205, 103, 2 },
324 /* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */
325 { 256, 205, 155, 101, 52, 1 },
327 /* x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 -- 105 */
328 { 128, 103, 76, 51, 25, 1 },
329 #if 0 /* Alternate polynomial */
330 /* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */
331 { 128, 103, 78, 51, 27, 2 },
334 /* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */
335 { 64, 52, 39, 26, 14, 1 },
337 /* x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 -- 15 */
338 { 32, 26, 20, 14, 7, 1 },
340 { 0, 0, 0, 0, 0, 0 },
343 #define POOLBITS poolwords*32
344 #define POOLBYTES poolwords*4
347 * For the purposes of better mixing, we use the CRC-32 polynomial as
348 * well to make a twisted Generalized Feedback Shift Reigster
350 * (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR generators. ACM
351 * Transactions on Modeling and Computer Simulation 2(3):179-194.
352 * Also see M. Matsumoto & Y. Kurita, 1994. Twisted GFSR generators
353 * II. ACM Transactions on Mdeling and Computer Simulation 4:254-266)
355 * Thanks to Colin Plumb for suggesting this.
357 * We have not analyzed the resultant polynomial to prove it primitive;
358 * in fact it almost certainly isn't. Nonetheless, the irreducible factors
359 * of a random large-degree polynomial over GF(2) are more than large enough
360 * that periodicity is not a concern.
362 * The input hash is much less sensitive than the output hash. All
363 * that we want of it is that it be a good non-cryptographic hash;
364 * i.e. it not produce collisions when fed "random" data of the sort
365 * we expect to see. As long as the pool state differs for different
366 * inputs, we have preserved the input entropy and done a good job.
367 * The fact that an intelligent attacker can construct inputs that
368 * will produce controlled alterations to the pool's state is not
369 * important because we don't consider such inputs to contribute any
370 * randomness. The only property we need with respect to them is that
371 * the attacker can't increase his/her knowledge of the pool's state.
372 * Since all additions are reversible (knowing the final state and the
373 * input, you can reconstruct the initial state), if an attacker has
374 * any uncertainty about the initial state, he/she can only shuffle
375 * that uncertainty about, but never cause any collisions (which would
376 * decrease the uncertainty).
378 * The chosen system lets the state of the pool be (essentially) the input
379 * modulo the generator polymnomial. Now, for random primitive polynomials,
380 * this is a universal class of hash functions, meaning that the chance
381 * of a collision is limited by the attacker's knowledge of the generator
382 * polynomail, so if it is chosen at random, an attacker can never force
383 * a collision. Here, we use a fixed polynomial, but we *can* assume that
384 * ###--> it is unknown to the processes generating the input entropy. <-###
385 * Because of this important property, this is a good, collision-resistant
386 * hash; hash collisions will occur no more often than chance.
390 * Linux 2.2 compatibility
392 #ifndef DECLARE_WAITQUEUE
393 #define DECLARE_WAITQUEUE(WAIT, PTR) struct wait_queue WAIT = { PTR, NULL }
395 #ifndef DECLARE_WAIT_QUEUE_HEAD
396 #define DECLARE_WAIT_QUEUE_HEAD(WAIT) struct wait_queue *WAIT
400 * Static global variables
402 static struct entropy_store *random_state; /* The default global store */
403 static struct entropy_store *sec_random_state; /* secondary store */
404 static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
405 static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
408 * Forward procedure declarations
411 static void sysctl_init_random(struct entropy_store *random_state);
414 /*****************************************************************
416 * Utility functions, with some ASM defined functions for speed
419 *****************************************************************/
422 * Unfortunately, while the GCC optimizer for the i386 understands how
423 * to optimize a static rotate left of x bits, it doesn't know how to
424 * deal with a variable rotate of x bits. So we use a bit of asm magic.
426 #if (!defined (__i386__))
427 static inline __u32 rotate_left(int i, __u32 word)
429 return (word << i) | (word >> (32 - i));
433 static inline __u32 rotate_left(int i, __u32 word)
435 __asm__("roll %%cl,%0"
437 :"0" (word),"c" (i));
445 * For entropy estimation, we need to do an integral base 2
448 * Note the "12bits" suffix - this is used for numbers between
449 * 0 and 4095 only. This allows a few shortcuts.
451 #if 0 /* Slow but clear version */
452 static inline __u32 int_ln_12bits(__u32 word)
460 #else /* Faster (more clever) version, courtesy Colin Plumb */
461 static inline __u32 int_ln_12bits(__u32 word)
463 /* Smear msbit right to make an n-bit mask */
468 /* Remove one bit to make this a logarithm */
470 /* Count the bits set in the word */
471 word -= (word >> 1) & 0x555;
472 word = (word & 0x333) + ((word >> 2) & 0x333);
480 #define DEBUG_ENT(fmt, arg...) printk(KERN_DEBUG "random: " fmt, ## arg)
482 #define DEBUG_ENT(fmt, arg...) do {} while (0)
485 /**********************************************************************
487 * OS independent entropy store. Here are the functions which handle
488 * storing entropy in an entropy pool.
490 **********************************************************************/
492 struct entropy_store {
493 /* mostly-read data: */
494 struct poolinfo poolinfo;
497 /* read-write data: */
498 spinlock_t lock ____cacheline_aligned_in_smp;
505 * Initialize the entropy store. The input argument is the size of
508 * Returns an negative error if there is a problem.
510 static int create_entropy_store(int size, struct entropy_store **ret_bucket)
512 struct entropy_store *r;
516 poolwords = (size + 3) / 4; /* Convert bytes->words */
517 /* The pool size must be a multiple of 16 32-bit words */
518 poolwords = ((poolwords + 15) / 16) * 16;
520 for (p = poolinfo_table; p->poolwords; p++) {
521 if (poolwords == p->poolwords)
524 if (p->poolwords == 0)
527 r = kmalloc(sizeof(struct entropy_store), GFP_KERNEL);
531 memset (r, 0, sizeof(struct entropy_store));
534 r->pool = kmalloc(POOLBYTES, GFP_KERNEL);
539 memset(r->pool, 0, POOLBYTES);
540 r->lock = SPIN_LOCK_UNLOCKED;
545 /* Clear the entropy pool and associated counters. */
546 static void clear_entropy_store(struct entropy_store *r)
549 r->entropy_count = 0;
551 memset(r->pool, 0, r->poolinfo.POOLBYTES);
554 static void free_entropy_store(struct entropy_store *r)
562 * This function adds a byte into the entropy "pool". It does not
563 * update the entropy estimate. The caller should call
564 * credit_entropy_store if this is appropriate.
566 * The pool is stirred with a primitive polynomial of the appropriate
567 * degree, and then twisted. We twist by three bits at a time because
568 * it's cheap to do so and helps slightly in the expected case where
569 * the entropy is concentrated in the low-order bits.
571 static void add_entropy_words(struct entropy_store *r, const __u32 *in,
574 static __u32 const twist_table[8] = {
575 0, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
576 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
577 unsigned long i, add_ptr, tap1, tap2, tap3, tap4, tap5;
578 int new_rotate, input_rotate;
579 int wordmask = r->poolinfo.poolwords - 1;
583 /* Taps are constant, so we can load them without holding r->lock. */
584 tap1 = r->poolinfo.tap1;
585 tap2 = r->poolinfo.tap2;
586 tap3 = r->poolinfo.tap3;
587 tap4 = r->poolinfo.tap4;
588 tap5 = r->poolinfo.tap5;
591 spin_lock_irqsave(&r->lock, flags);
592 prefetch_range(r->pool, wordmask);
593 input_rotate = r->input_rotate;
594 add_ptr = r->add_ptr;
597 w = rotate_left(input_rotate, next_w);
600 i = add_ptr = (add_ptr - 1) & wordmask;
602 * Normally, we add 7 bits of rotation to the pool.
603 * At the beginning of the pool, add an extra 7 bits
604 * rotation, so that successive passes spread the
605 * input bits across the pool evenly.
607 new_rotate = input_rotate + 14;
609 new_rotate = input_rotate + 7;
610 input_rotate = new_rotate & 31;
612 /* XOR in the various taps */
613 w ^= r->pool[(i + tap1) & wordmask];
614 w ^= r->pool[(i + tap2) & wordmask];
615 w ^= r->pool[(i + tap3) & wordmask];
616 w ^= r->pool[(i + tap4) & wordmask];
617 w ^= r->pool[(i + tap5) & wordmask];
619 r->pool[i] = (w >> 3) ^ twist_table[w & 7];
622 r->input_rotate = input_rotate;
623 r->add_ptr = add_ptr;
625 spin_unlock_irqrestore(&r->lock, flags);
629 * Credit (or debit) the entropy store with n bits of entropy
631 static void credit_entropy_store(struct entropy_store *r, int nbits)
635 spin_lock_irqsave(&r->lock, flags);
637 if (r->entropy_count + nbits < 0) {
638 DEBUG_ENT("negative entropy/overflow (%d+%d)\n",
639 r->entropy_count, nbits);
640 r->entropy_count = 0;
641 } else if (r->entropy_count + nbits > r->poolinfo.POOLBITS) {
642 r->entropy_count = r->poolinfo.POOLBITS;
644 r->entropy_count += nbits;
646 DEBUG_ENT("%04d %04d : added %d bits to %s\n",
647 random_state->entropy_count,
648 sec_random_state->entropy_count,
650 r == sec_random_state ? "secondary" :
651 r == random_state ? "primary" : "unknown");
654 spin_unlock_irqrestore(&r->lock, flags);
657 /**********************************************************************
659 * Entropy batch input management
661 * We batch entropy to be added to avoid increasing interrupt latency
663 **********************************************************************/
670 static struct sample *batch_entropy_pool, *batch_entropy_copy;
671 static int batch_head, batch_tail;
672 static spinlock_t batch_lock = SPIN_LOCK_UNLOCKED;
674 static int batch_max;
675 static void batch_entropy_process(void *private_);
676 static DECLARE_WORK(batch_work, batch_entropy_process, NULL);
678 /* note: the size must be a power of 2 */
679 static int __init batch_entropy_init(int size, struct entropy_store *r)
681 batch_entropy_pool = kmalloc(size*sizeof(struct sample), GFP_KERNEL);
682 if (!batch_entropy_pool)
684 batch_entropy_copy = kmalloc(size*sizeof(struct sample), GFP_KERNEL);
685 if (!batch_entropy_copy) {
686 kfree(batch_entropy_pool);
689 batch_head = batch_tail = 0;
696 * Changes to the entropy data is put into a queue rather than being added to
697 * the entropy counts directly. This is presumably to avoid doing heavy
698 * hashing calculations during an interrupt in add_timer_randomness().
699 * Instead, the entropy is only added to the pool by keventd.
701 void batch_entropy_store(u32 a, u32 b, int num)
709 spin_lock_irqsave(&batch_lock, flags);
711 batch_entropy_pool[batch_head].data[0] = a;
712 batch_entropy_pool[batch_head].data[1] = b;
713 batch_entropy_pool[batch_head].credit = num;
715 if (((batch_head - batch_tail) & (batch_max-1)) >= (batch_max / 2)) {
717 * Schedule it for the next timer tick:
719 schedule_delayed_work(&batch_work, 1);
722 new = (batch_head+1) & (batch_max-1);
723 if (new == batch_tail) {
724 DEBUG_ENT("batch entropy buffer full\n");
729 spin_unlock_irqrestore(&batch_lock, flags);
732 EXPORT_SYMBOL(batch_entropy_store);
735 * Flush out the accumulated entropy operations, adding entropy to the passed
736 * store (normally random_state). If that store has enough entropy, alternate
737 * between randomizing the data of the primary and secondary stores.
739 static void batch_entropy_process(void *private_)
741 struct entropy_store *r = (struct entropy_store *) private_, *p;
742 int max_entropy = r->poolinfo.POOLBITS;
745 /* Mixing into the pool is expensive, so copy over the batch
746 * data and release the batch lock. The pool is at least half
747 * full, so don't worry too much about copying only the used
750 spin_lock_irq(&batch_lock);
752 memcpy(batch_entropy_copy, batch_entropy_pool,
753 batch_max*sizeof(struct sample));
757 batch_tail = batch_head;
759 spin_unlock_irq(&batch_lock);
762 while (head != tail) {
763 if (r->entropy_count >= max_entropy) {
764 r = (r == sec_random_state) ? random_state :
766 max_entropy = r->poolinfo.POOLBITS;
768 add_entropy_words(r, batch_entropy_copy[tail].data, 2);
769 credit_entropy_store(r, batch_entropy_copy[tail].credit);
770 tail = (tail+1) & (batch_max-1);
772 if (p->entropy_count >= random_read_wakeup_thresh)
773 wake_up_interruptible(&random_read_wait);
776 /*********************************************************************
778 * Entropy input management
780 *********************************************************************/
782 /* There is one of these per entropy source */
783 struct timer_rand_state {
785 __s32 last_delta,last_delta2;
786 int dont_count_entropy:1;
789 static struct timer_rand_state keyboard_timer_state;
790 static struct timer_rand_state mouse_timer_state;
791 static struct timer_rand_state extract_timer_state;
792 static struct timer_rand_state *irq_timer_state[NR_IRQS];
795 * This function adds entropy to the entropy "pool" by using timing
796 * delays. It uses the timer_rand_state structure to make an estimate
797 * of how many bits of entropy this call has added to the pool.
799 * The number "num" is also added to the pool - it should somehow describe
800 * the type of event which just happened. This is currently 0-255 for
801 * keyboard scan codes, and 256 upwards for interrupts.
802 * On the i386, this is assumed to be at most 16 bits, and the high bits
803 * are used for a high-resolution timer.
806 static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
809 __s32 delta, delta2, delta3;
812 /* if over the trickle threshold, use only 1 in 4096 samples */
813 if ( random_state->entropy_count > trickle_thresh &&
814 (__get_cpu_var(trickle_count)++ & 0xfff))
817 #if defined (__i386__) || defined (__x86_64__)
825 #elif defined (__sparc_v9__)
826 unsigned long tick = tick_ops->get_tick();
828 time = (unsigned int) tick;
829 num ^= (tick >> 32UL);
835 * Calculate number of bits of randomness we probably added.
836 * We take into account the first, second and third-order deltas
837 * in order to make our estimate.
839 if (!state->dont_count_entropy) {
840 delta = time - state->last_time;
841 state->last_time = time;
843 delta2 = delta - state->last_delta;
844 state->last_delta = delta;
846 delta3 = delta2 - state->last_delta2;
847 state->last_delta2 = delta2;
861 * delta is now minimum absolute delta.
862 * Round down by 1 bit on general principles,
863 * and limit entropy entimate to 12 bits.
866 delta &= (1 << 12) - 1;
868 entropy = int_ln_12bits(delta);
870 batch_entropy_store(num, time, entropy);
873 void add_keyboard_randomness(unsigned char scancode)
875 static unsigned char last_scancode;
876 /* ignore autorepeat (multiple key down w/o key up) */
877 if (scancode != last_scancode) {
878 last_scancode = scancode;
879 add_timer_randomness(&keyboard_timer_state, scancode);
883 EXPORT_SYMBOL(add_keyboard_randomness);
885 void add_mouse_randomness(__u32 mouse_data)
887 add_timer_randomness(&mouse_timer_state, mouse_data);
890 EXPORT_SYMBOL(add_mouse_randomness);
892 void add_interrupt_randomness(int irq)
894 if (irq >= NR_IRQS || irq_timer_state[irq] == 0)
897 add_timer_randomness(irq_timer_state[irq], 0x100+irq);
900 EXPORT_SYMBOL(add_interrupt_randomness);
902 void add_disk_randomness(struct gendisk *disk)
904 if (!disk || !disk->random)
906 /* first major is 1, so we get >= 0x200 here */
907 add_timer_randomness(disk->random, 0x100+MKDEV(disk->major, disk->first_minor));
910 EXPORT_SYMBOL(add_disk_randomness);
912 /******************************************************************
914 * Hash function definition
916 *******************************************************************/
919 * This chunk of code defines a function
920 * void HASH_TRANSFORM(__u32 digest[HASH_BUFFER_SIZE + HASH_EXTRA_SIZE],
921 * __u32 const data[16])
923 * The function hashes the input data to produce a digest in the first
924 * HASH_BUFFER_SIZE words of the digest[] array, and uses HASH_EXTRA_SIZE
925 * more words for internal purposes. (This buffer is exported so the
926 * caller can wipe it once rather than this code doing it each call,
927 * and tacking it onto the end of the digest[] array is the quick and
928 * dirty way of doing it.)
930 * It so happens that MD5 and SHA share most of the initial vector
931 * used to initialize the digest[] array before the first call:
936 * 5) 0xc3d2e1f0 (SHA only)
938 * For /dev/random purposes, the length of the data being hashed is
939 * fixed in length, so appending a bit count in the usual way is not
940 * cryptographically necessary.
945 #define HASH_BUFFER_SIZE 5
946 #define HASH_EXTRA_SIZE 80
947 #define HASH_TRANSFORM SHATransform
949 /* Various size/speed tradeoffs are available. Choose 0..3. */
950 #define SHA_CODE_SIZE 0
953 * SHA transform algorithm, taken from code written by Peter Gutmann,
954 * and placed in the public domain.
957 /* The SHA f()-functions. */
959 #define f1(x,y,z) ( z ^ (x & (y^z)) ) /* Rounds 0-19: x ? y : z */
960 #define f2(x,y,z) (x ^ y ^ z) /* Rounds 20-39: XOR */
961 #define f3(x,y,z) ( (x & y) + (z & (x ^ y)) ) /* Rounds 40-59: majority */
962 #define f4(x,y,z) (x ^ y ^ z) /* Rounds 60-79: XOR */
964 /* The SHA Mysterious Constants */
966 #define K1 0x5A827999L /* Rounds 0-19: sqrt(2) * 2^30 */
967 #define K2 0x6ED9EBA1L /* Rounds 20-39: sqrt(3) * 2^30 */
968 #define K3 0x8F1BBCDCL /* Rounds 40-59: sqrt(5) * 2^30 */
969 #define K4 0xCA62C1D6L /* Rounds 60-79: sqrt(10) * 2^30 */
971 #define ROTL(n,X) ( ( ( X ) << n ) | ( ( X ) >> ( 32 - n ) ) )
973 #define subRound(a, b, c, d, e, f, k, data) \
974 ( e += ROTL( 5, a ) + f( b, c, d ) + k + data, b = ROTL( 30, b ) )
977 static void SHATransform(__u32 digest[85], __u32 const data[16])
979 __u32 A, B, C, D, E; /* Local vars */
982 #define W (digest + HASH_BUFFER_SIZE) /* Expanded data array */
985 * Do the preliminary expansion of 16 to 80 words. Doing it
986 * out-of-line line this is faster than doing it in-line on
987 * register-starved machines like the x86, and not really any
988 * slower on real processors.
990 memcpy(W, data, 16*sizeof(__u32));
991 for (i = 0; i < 64; i++) {
992 TEMP = W[i] ^ W[i+2] ^ W[i+8] ^ W[i+13];
993 W[i+16] = ROTL(1, TEMP);
996 /* Set up first buffer and local data buffer */
1003 /* Heavy mangling, in 4 sub-rounds of 20 iterations each. */
1004 #if SHA_CODE_SIZE == 0
1006 * Approximately 50% of the speed of the largest version, but
1007 * takes up 1/16 the space. Saves about 6k on an i386 kernel.
1009 for (i = 0; i < 80; i++) {
1012 TEMP = f1(B, C, D) + K1;
1014 TEMP = f2(B, C, D) + K2;
1017 TEMP = f3(B, C, D) + K3;
1019 TEMP = f4(B, C, D) + K4;
1021 TEMP += ROTL(5, A) + E + W[i];
1022 E = D; D = C; C = ROTL(30, B); B = A; A = TEMP;
1024 #elif SHA_CODE_SIZE == 1
1025 for (i = 0; i < 20; i++) {
1026 TEMP = f1(B, C, D) + K1 + ROTL(5, A) + E + W[i];
1027 E = D; D = C; C = ROTL(30, B); B = A; A = TEMP;
1029 for (; i < 40; i++) {
1030 TEMP = f2(B, C, D) + K2 + ROTL(5, A) + E + W[i];
1031 E = D; D = C; C = ROTL(30, B); B = A; A = TEMP;
1033 for (; i < 60; i++) {
1034 TEMP = f3(B, C, D) + K3 + ROTL(5, A) + E + W[i];
1035 E = D; D = C; C = ROTL(30, B); B = A; A = TEMP;
1037 for (; i < 80; i++) {
1038 TEMP = f4(B, C, D) + K4 + ROTL(5, A) + E + W[i];
1039 E = D; D = C; C = ROTL(30, B); B = A; A = TEMP;
1041 #elif SHA_CODE_SIZE == 2
1042 for (i = 0; i < 20; i += 5) {
1043 subRound( A, B, C, D, E, f1, K1, W[ i ] );
1044 subRound( E, A, B, C, D, f1, K1, W[ i+1 ] );
1045 subRound( D, E, A, B, C, f1, K1, W[ i+2 ] );
1046 subRound( C, D, E, A, B, f1, K1, W[ i+3 ] );
1047 subRound( B, C, D, E, A, f1, K1, W[ i+4 ] );
1049 for (; i < 40; i += 5) {
1050 subRound( A, B, C, D, E, f2, K2, W[ i ] );
1051 subRound( E, A, B, C, D, f2, K2, W[ i+1 ] );
1052 subRound( D, E, A, B, C, f2, K2, W[ i+2 ] );
1053 subRound( C, D, E, A, B, f2, K2, W[ i+3 ] );
1054 subRound( B, C, D, E, A, f2, K2, W[ i+4 ] );
1056 for (; i < 60; i += 5) {
1057 subRound( A, B, C, D, E, f3, K3, W[ i ] );
1058 subRound( E, A, B, C, D, f3, K3, W[ i+1 ] );
1059 subRound( D, E, A, B, C, f3, K3, W[ i+2 ] );
1060 subRound( C, D, E, A, B, f3, K3, W[ i+3 ] );
1061 subRound( B, C, D, E, A, f3, K3, W[ i+4 ] );
1063 for (; i < 80; i += 5) {
1064 subRound( A, B, C, D, E, f4, K4, W[ i ] );
1065 subRound( E, A, B, C, D, f4, K4, W[ i+1 ] );
1066 subRound( D, E, A, B, C, f4, K4, W[ i+2 ] );
1067 subRound( C, D, E, A, B, f4, K4, W[ i+3 ] );
1068 subRound( B, C, D, E, A, f4, K4, W[ i+4 ] );
1070 #elif SHA_CODE_SIZE == 3 /* Really large version */
1071 subRound( A, B, C, D, E, f1, K1, W[ 0 ] );
1072 subRound( E, A, B, C, D, f1, K1, W[ 1 ] );
1073 subRound( D, E, A, B, C, f1, K1, W[ 2 ] );
1074 subRound( C, D, E, A, B, f1, K1, W[ 3 ] );
1075 subRound( B, C, D, E, A, f1, K1, W[ 4 ] );
1076 subRound( A, B, C, D, E, f1, K1, W[ 5 ] );
1077 subRound( E, A, B, C, D, f1, K1, W[ 6 ] );
1078 subRound( D, E, A, B, C, f1, K1, W[ 7 ] );
1079 subRound( C, D, E, A, B, f1, K1, W[ 8 ] );
1080 subRound( B, C, D, E, A, f1, K1, W[ 9 ] );
1081 subRound( A, B, C, D, E, f1, K1, W[ 10 ] );
1082 subRound( E, A, B, C, D, f1, K1, W[ 11 ] );
1083 subRound( D, E, A, B, C, f1, K1, W[ 12 ] );
1084 subRound( C, D, E, A, B, f1, K1, W[ 13 ] );
1085 subRound( B, C, D, E, A, f1, K1, W[ 14 ] );
1086 subRound( A, B, C, D, E, f1, K1, W[ 15 ] );
1087 subRound( E, A, B, C, D, f1, K1, W[ 16 ] );
1088 subRound( D, E, A, B, C, f1, K1, W[ 17 ] );
1089 subRound( C, D, E, A, B, f1, K1, W[ 18 ] );
1090 subRound( B, C, D, E, A, f1, K1, W[ 19 ] );
1092 subRound( A, B, C, D, E, f2, K2, W[ 20 ] );
1093 subRound( E, A, B, C, D, f2, K2, W[ 21 ] );
1094 subRound( D, E, A, B, C, f2, K2, W[ 22 ] );
1095 subRound( C, D, E, A, B, f2, K2, W[ 23 ] );
1096 subRound( B, C, D, E, A, f2, K2, W[ 24 ] );
1097 subRound( A, B, C, D, E, f2, K2, W[ 25 ] );
1098 subRound( E, A, B, C, D, f2, K2, W[ 26 ] );
1099 subRound( D, E, A, B, C, f2, K2, W[ 27 ] );
1100 subRound( C, D, E, A, B, f2, K2, W[ 28 ] );
1101 subRound( B, C, D, E, A, f2, K2, W[ 29 ] );
1102 subRound( A, B, C, D, E, f2, K2, W[ 30 ] );
1103 subRound( E, A, B, C, D, f2, K2, W[ 31 ] );
1104 subRound( D, E, A, B, C, f2, K2, W[ 32 ] );
1105 subRound( C, D, E, A, B, f2, K2, W[ 33 ] );
1106 subRound( B, C, D, E, A, f2, K2, W[ 34 ] );
1107 subRound( A, B, C, D, E, f2, K2, W[ 35 ] );
1108 subRound( E, A, B, C, D, f2, K2, W[ 36 ] );
1109 subRound( D, E, A, B, C, f2, K2, W[ 37 ] );
1110 subRound( C, D, E, A, B, f2, K2, W[ 38 ] );
1111 subRound( B, C, D, E, A, f2, K2, W[ 39 ] );
1113 subRound( A, B, C, D, E, f3, K3, W[ 40 ] );
1114 subRound( E, A, B, C, D, f3, K3, W[ 41 ] );
1115 subRound( D, E, A, B, C, f3, K3, W[ 42 ] );
1116 subRound( C, D, E, A, B, f3, K3, W[ 43 ] );
1117 subRound( B, C, D, E, A, f3, K3, W[ 44 ] );
1118 subRound( A, B, C, D, E, f3, K3, W[ 45 ] );
1119 subRound( E, A, B, C, D, f3, K3, W[ 46 ] );
1120 subRound( D, E, A, B, C, f3, K3, W[ 47 ] );
1121 subRound( C, D, E, A, B, f3, K3, W[ 48 ] );
1122 subRound( B, C, D, E, A, f3, K3, W[ 49 ] );
1123 subRound( A, B, C, D, E, f3, K3, W[ 50 ] );
1124 subRound( E, A, B, C, D, f3, K3, W[ 51 ] );
1125 subRound( D, E, A, B, C, f3, K3, W[ 52 ] );
1126 subRound( C, D, E, A, B, f3, K3, W[ 53 ] );
1127 subRound( B, C, D, E, A, f3, K3, W[ 54 ] );
1128 subRound( A, B, C, D, E, f3, K3, W[ 55 ] );
1129 subRound( E, A, B, C, D, f3, K3, W[ 56 ] );
1130 subRound( D, E, A, B, C, f3, K3, W[ 57 ] );
1131 subRound( C, D, E, A, B, f3, K3, W[ 58 ] );
1132 subRound( B, C, D, E, A, f3, K3, W[ 59 ] );
1134 subRound( A, B, C, D, E, f4, K4, W[ 60 ] );
1135 subRound( E, A, B, C, D, f4, K4, W[ 61 ] );
1136 subRound( D, E, A, B, C, f4, K4, W[ 62 ] );
1137 subRound( C, D, E, A, B, f4, K4, W[ 63 ] );
1138 subRound( B, C, D, E, A, f4, K4, W[ 64 ] );
1139 subRound( A, B, C, D, E, f4, K4, W[ 65 ] );
1140 subRound( E, A, B, C, D, f4, K4, W[ 66 ] );
1141 subRound( D, E, A, B, C, f4, K4, W[ 67 ] );
1142 subRound( C, D, E, A, B, f4, K4, W[ 68 ] );
1143 subRound( B, C, D, E, A, f4, K4, W[ 69 ] );
1144 subRound( A, B, C, D, E, f4, K4, W[ 70 ] );
1145 subRound( E, A, B, C, D, f4, K4, W[ 71 ] );
1146 subRound( D, E, A, B, C, f4, K4, W[ 72 ] );
1147 subRound( C, D, E, A, B, f4, K4, W[ 73 ] );
1148 subRound( B, C, D, E, A, f4, K4, W[ 74 ] );
1149 subRound( A, B, C, D, E, f4, K4, W[ 75 ] );
1150 subRound( E, A, B, C, D, f4, K4, W[ 76 ] );
1151 subRound( D, E, A, B, C, f4, K4, W[ 77 ] );
1152 subRound( C, D, E, A, B, f4, K4, W[ 78 ] );
1153 subRound( B, C, D, E, A, f4, K4, W[ 79 ] );
1155 #error Illegal SHA_CODE_SIZE
1158 /* Build message digest */
1165 /* W is wiped by the caller */
1180 #else /* !USE_SHA - Use MD5 */
1182 #define HASH_BUFFER_SIZE 4
1183 #define HASH_EXTRA_SIZE 0
1184 #define HASH_TRANSFORM MD5Transform
1187 * MD5 transform algorithm, taken from code written by Colin Plumb,
1188 * and put into the public domain
1191 /* The four core functions - F1 is optimized somewhat */
1193 /* #define F1(x, y, z) (x & y | ~x & z) */
1194 #define F1(x, y, z) (z ^ (x & (y ^ z)))
1195 #define F2(x, y, z) F1(z, x, y)
1196 #define F3(x, y, z) (x ^ y ^ z)
1197 #define F4(x, y, z) (y ^ (x | ~z))
1199 /* This is the central step in the MD5 algorithm. */
1200 #define MD5STEP(f, w, x, y, z, data, s) \
1201 ( w += f(x, y, z) + data, w = w<<s | w>>(32-s), w += x )
1204 * The core of the MD5 algorithm, this alters an existing MD5 hash to
1205 * reflect the addition of 16 longwords of new data. MD5Update blocks
1206 * the data and converts bytes into longwords for this routine.
1208 static void MD5Transform(__u32 buf[HASH_BUFFER_SIZE], __u32 const in[16])
1217 MD5STEP(F1, a, b, c, d, in[ 0]+0xd76aa478, 7);
1218 MD5STEP(F1, d, a, b, c, in[ 1]+0xe8c7b756, 12);
1219 MD5STEP(F1, c, d, a, b, in[ 2]+0x242070db, 17);
1220 MD5STEP(F1, b, c, d, a, in[ 3]+0xc1bdceee, 22);
1221 MD5STEP(F1, a, b, c, d, in[ 4]+0xf57c0faf, 7);
1222 MD5STEP(F1, d, a, b, c, in[ 5]+0x4787c62a, 12);
1223 MD5STEP(F1, c, d, a, b, in[ 6]+0xa8304613, 17);
1224 MD5STEP(F1, b, c, d, a, in[ 7]+0xfd469501, 22);
1225 MD5STEP(F1, a, b, c, d, in[ 8]+0x698098d8, 7);
1226 MD5STEP(F1, d, a, b, c, in[ 9]+0x8b44f7af, 12);
1227 MD5STEP(F1, c, d, a, b, in[10]+0xffff5bb1, 17);
1228 MD5STEP(F1, b, c, d, a, in[11]+0x895cd7be, 22);
1229 MD5STEP(F1, a, b, c, d, in[12]+0x6b901122, 7);
1230 MD5STEP(F1, d, a, b, c, in[13]+0xfd987193, 12);
1231 MD5STEP(F1, c, d, a, b, in[14]+0xa679438e, 17);
1232 MD5STEP(F1, b, c, d, a, in[15]+0x49b40821, 22);
1234 MD5STEP(F2, a, b, c, d, in[ 1]+0xf61e2562, 5);
1235 MD5STEP(F2, d, a, b, c, in[ 6]+0xc040b340, 9);
1236 MD5STEP(F2, c, d, a, b, in[11]+0x265e5a51, 14);
1237 MD5STEP(F2, b, c, d, a, in[ 0]+0xe9b6c7aa, 20);
1238 MD5STEP(F2, a, b, c, d, in[ 5]+0xd62f105d, 5);
1239 MD5STEP(F2, d, a, b, c, in[10]+0x02441453, 9);
1240 MD5STEP(F2, c, d, a, b, in[15]+0xd8a1e681, 14);
1241 MD5STEP(F2, b, c, d, a, in[ 4]+0xe7d3fbc8, 20);
1242 MD5STEP(F2, a, b, c, d, in[ 9]+0x21e1cde6, 5);
1243 MD5STEP(F2, d, a, b, c, in[14]+0xc33707d6, 9);
1244 MD5STEP(F2, c, d, a, b, in[ 3]+0xf4d50d87, 14);
1245 MD5STEP(F2, b, c, d, a, in[ 8]+0x455a14ed, 20);
1246 MD5STEP(F2, a, b, c, d, in[13]+0xa9e3e905, 5);
1247 MD5STEP(F2, d, a, b, c, in[ 2]+0xfcefa3f8, 9);
1248 MD5STEP(F2, c, d, a, b, in[ 7]+0x676f02d9, 14);
1249 MD5STEP(F2, b, c, d, a, in[12]+0x8d2a4c8a, 20);
1251 MD5STEP(F3, a, b, c, d, in[ 5]+0xfffa3942, 4);
1252 MD5STEP(F3, d, a, b, c, in[ 8]+0x8771f681, 11);
1253 MD5STEP(F3, c, d, a, b, in[11]+0x6d9d6122, 16);
1254 MD5STEP(F3, b, c, d, a, in[14]+0xfde5380c, 23);
1255 MD5STEP(F3, a, b, c, d, in[ 1]+0xa4beea44, 4);
1256 MD5STEP(F3, d, a, b, c, in[ 4]+0x4bdecfa9, 11);
1257 MD5STEP(F3, c, d, a, b, in[ 7]+0xf6bb4b60, 16);
1258 MD5STEP(F3, b, c, d, a, in[10]+0xbebfbc70, 23);
1259 MD5STEP(F3, a, b, c, d, in[13]+0x289b7ec6, 4);
1260 MD5STEP(F3, d, a, b, c, in[ 0]+0xeaa127fa, 11);
1261 MD5STEP(F3, c, d, a, b, in[ 3]+0xd4ef3085, 16);
1262 MD5STEP(F3, b, c, d, a, in[ 6]+0x04881d05, 23);
1263 MD5STEP(F3, a, b, c, d, in[ 9]+0xd9d4d039, 4);
1264 MD5STEP(F3, d, a, b, c, in[12]+0xe6db99e5, 11);
1265 MD5STEP(F3, c, d, a, b, in[15]+0x1fa27cf8, 16);
1266 MD5STEP(F3, b, c, d, a, in[ 2]+0xc4ac5665, 23);
1268 MD5STEP(F4, a, b, c, d, in[ 0]+0xf4292244, 6);
1269 MD5STEP(F4, d, a, b, c, in[ 7]+0x432aff97, 10);
1270 MD5STEP(F4, c, d, a, b, in[14]+0xab9423a7, 15);
1271 MD5STEP(F4, b, c, d, a, in[ 5]+0xfc93a039, 21);
1272 MD5STEP(F4, a, b, c, d, in[12]+0x655b59c3, 6);
1273 MD5STEP(F4, d, a, b, c, in[ 3]+0x8f0ccc92, 10);
1274 MD5STEP(F4, c, d, a, b, in[10]+0xffeff47d, 15);
1275 MD5STEP(F4, b, c, d, a, in[ 1]+0x85845dd1, 21);
1276 MD5STEP(F4, a, b, c, d, in[ 8]+0x6fa87e4f, 6);
1277 MD5STEP(F4, d, a, b, c, in[15]+0xfe2ce6e0, 10);
1278 MD5STEP(F4, c, d, a, b, in[ 6]+0xa3014314, 15);
1279 MD5STEP(F4, b, c, d, a, in[13]+0x4e0811a1, 21);
1280 MD5STEP(F4, a, b, c, d, in[ 4]+0xf7537e82, 6);
1281 MD5STEP(F4, d, a, b, c, in[11]+0xbd3af235, 10);
1282 MD5STEP(F4, c, d, a, b, in[ 2]+0x2ad7d2bb, 15);
1283 MD5STEP(F4, b, c, d, a, in[ 9]+0xeb86d391, 21);
1297 #endif /* !USE_SHA */
1299 /*********************************************************************
1301 * Entropy extraction routines
1303 *********************************************************************/
1305 #define EXTRACT_ENTROPY_USER 1
1306 #define EXTRACT_ENTROPY_SECONDARY 2
1307 #define EXTRACT_ENTROPY_LIMIT 4
1308 #define TMP_BUF_SIZE (HASH_BUFFER_SIZE + HASH_EXTRA_SIZE)
1309 #define SEC_XFER_SIZE (TMP_BUF_SIZE*4)
1311 static ssize_t extract_entropy(struct entropy_store *r, void * buf,
1312 size_t nbytes, int flags);
1315 * This utility inline function is responsible for transfering entropy
1316 * from the primary pool to the secondary extraction pool. We make
1317 * sure we pull enough for a 'catastrophic reseed'.
1319 static inline void xfer_secondary_pool(struct entropy_store *r,
1320 size_t nbytes, __u32 *tmp)
1322 if (r->entropy_count < nbytes * 8 &&
1323 r->entropy_count < r->poolinfo.POOLBITS) {
1324 int bytes = max_t(int, random_read_wakeup_thresh / 8,
1325 min_t(int, nbytes, TMP_BUF_SIZE));
1327 DEBUG_ENT("%04d %04d : going to reseed %s with %d bits "
1328 "(%d of %d requested)\n",
1329 random_state->entropy_count,
1330 sec_random_state->entropy_count,
1331 r == sec_random_state ? "secondary" : "unknown",
1332 bytes * 8, nbytes * 8, r->entropy_count);
1334 bytes=extract_entropy(random_state, tmp, bytes,
1335 EXTRACT_ENTROPY_LIMIT);
1336 add_entropy_words(r, tmp, bytes);
1337 credit_entropy_store(r, bytes*8);
1342 * This function extracts randomness from the "entropy pool", and
1343 * returns it in a buffer. This function computes how many remaining
1344 * bits of entropy are left in the pool, but it does not restrict the
1345 * number of bytes that are actually obtained. If the EXTRACT_ENTROPY_USER
1346 * flag is given, then the buf pointer is assumed to be in user space.
1348 * If the EXTRACT_ENTROPY_SECONDARY flag is given, then we are actually
1349 * extracting entropy from the secondary pool, and can refill from the
1350 * primary pool if needed.
1352 * Note: extract_entropy() assumes that .poolwords is a multiple of 16 words.
1354 static ssize_t extract_entropy(struct entropy_store *r, void * buf,
1355 size_t nbytes, int flags)
1358 __u32 tmp[TMP_BUF_SIZE];
1360 unsigned long cpuflags;
1363 /* Redundant, but just in case... */
1364 if (r->entropy_count > r->poolinfo.POOLBITS)
1365 r->entropy_count = r->poolinfo.POOLBITS;
1367 if (flags & EXTRACT_ENTROPY_SECONDARY)
1368 xfer_secondary_pool(r, nbytes, tmp);
1370 /* Hold lock while accounting */
1371 spin_lock_irqsave(&r->lock, cpuflags);
1373 DEBUG_ENT("%04d %04d : trying to extract %d bits from %s\n",
1374 random_state->entropy_count,
1375 sec_random_state->entropy_count,
1377 r == sec_random_state ? "secondary" :
1378 r == random_state ? "primary" : "unknown");
1380 if (flags & EXTRACT_ENTROPY_LIMIT && nbytes >= r->entropy_count / 8)
1381 nbytes = r->entropy_count / 8;
1383 if (r->entropy_count / 8 >= nbytes)
1384 r->entropy_count -= nbytes*8;
1386 r->entropy_count = 0;
1388 if (r->entropy_count < random_write_wakeup_thresh)
1389 wake_up_interruptible(&random_write_wait);
1391 DEBUG_ENT("%04d %04d : debiting %d bits from %s%s\n",
1392 random_state->entropy_count,
1393 sec_random_state->entropy_count,
1395 r == sec_random_state ? "secondary" :
1396 r == random_state ? "primary" : "unknown",
1397 flags & EXTRACT_ENTROPY_LIMIT ? "" : " (unlimited)");
1399 spin_unlock_irqrestore(&r->lock, cpuflags);
1404 * Check if we need to break out or reschedule....
1406 if ((flags & EXTRACT_ENTROPY_USER) && need_resched()) {
1407 if (signal_pending(current)) {
1413 DEBUG_ENT("%04d %04d : extract feeling sleepy (%d bytes left)\n",
1414 random_state->entropy_count,
1415 sec_random_state->entropy_count, nbytes);
1419 DEBUG_ENT("%04d %04d : extract woke up\n",
1420 random_state->entropy_count,
1421 sec_random_state->entropy_count);
1424 /* Hash the pool to get the output */
1425 tmp[0] = 0x67452301;
1426 tmp[1] = 0xefcdab89;
1427 tmp[2] = 0x98badcfe;
1428 tmp[3] = 0x10325476;
1430 tmp[4] = 0xc3d2e1f0;
1433 * As we hash the pool, we mix intermediate values of
1434 * the hash back into the pool. This eliminates
1435 * backtracking attacks (where the attacker knows
1436 * the state of the pool plus the current outputs, and
1437 * attempts to find previous ouputs), unless the hash
1438 * function can be inverted.
1440 for (i = 0, x = 0; i < r->poolinfo.poolwords; i += 16, x+=2) {
1441 HASH_TRANSFORM(tmp, r->pool+i);
1442 add_entropy_words(r, &tmp[x%HASH_BUFFER_SIZE], 1);
1446 * In case the hash function has some recognizable
1447 * output pattern, we fold it in half.
1449 for (i = 0; i < HASH_BUFFER_SIZE/2; i++)
1450 tmp[i] ^= tmp[i + (HASH_BUFFER_SIZE+1)/2];
1451 #if HASH_BUFFER_SIZE & 1 /* There's a middle word to deal with */
1452 x = tmp[HASH_BUFFER_SIZE/2];
1453 x ^= (x >> 16); /* Fold it in half */
1454 ((__u16 *)tmp)[HASH_BUFFER_SIZE-1] = (__u16)x;
1457 /* Copy data to destination buffer */
1458 i = min(nbytes, HASH_BUFFER_SIZE*sizeof(__u32)/2);
1459 if (flags & EXTRACT_ENTROPY_USER) {
1460 i -= copy_to_user(buf, (__u8 const *)tmp, i);
1466 memcpy(buf, (__u8 const *)tmp, i);
1472 /* Wipe data just returned from memory */
1473 memset(tmp, 0, sizeof(tmp));
1479 * This function is the exported kernel interface. It returns some
1480 * number of good random numbers, suitable for seeding TCP sequence
1483 void get_random_bytes(void *buf, int nbytes)
1485 if (sec_random_state)
1486 extract_entropy(sec_random_state, (char *) buf, nbytes,
1487 EXTRACT_ENTROPY_SECONDARY);
1488 else if (random_state)
1489 extract_entropy(random_state, (char *) buf, nbytes, 0);
1491 printk(KERN_NOTICE "get_random_bytes called before "
1492 "random driver initialization\n");
1495 EXPORT_SYMBOL(get_random_bytes);
1497 /*********************************************************************
1499 * Functions to interface with Linux
1501 *********************************************************************/
1504 * Initialize the random pool with standard stuff.
1506 * NOTE: This is an OS-dependent function.
1508 static void init_std_data(struct entropy_store *r)
1515 do_gettimeofday(&tv);
1516 words[0] = tv.tv_sec;
1517 words[1] = tv.tv_usec;
1518 add_entropy_words(r, words, 2);
1521 * This doesn't lock system.utsname. However, we are generating
1522 * entropy so a race with a name set here is fine.
1524 p = (char *) &system_utsname;
1525 for (i = sizeof(system_utsname) / sizeof(words); i; i--) {
1526 memcpy(words, p, sizeof(words));
1527 add_entropy_words(r, words, sizeof(words)/4);
1532 static int __init rand_initialize(void)
1536 if (create_entropy_store(DEFAULT_POOL_SIZE, &random_state))
1538 if (batch_entropy_init(BATCH_ENTROPY_SIZE, random_state))
1540 if (create_entropy_store(SECONDARY_POOL_SIZE, &sec_random_state))
1542 clear_entropy_store(random_state);
1543 clear_entropy_store(sec_random_state);
1544 init_std_data(random_state);
1545 #ifdef CONFIG_SYSCTL
1546 sysctl_init_random(random_state);
1548 for (i = 0; i < NR_IRQS; i++)
1549 irq_timer_state[i] = NULL;
1550 memset(&keyboard_timer_state, 0, sizeof(struct timer_rand_state));
1551 memset(&mouse_timer_state, 0, sizeof(struct timer_rand_state));
1552 memset(&extract_timer_state, 0, sizeof(struct timer_rand_state));
1553 extract_timer_state.dont_count_entropy = 1;
1558 module_init(rand_initialize);
1560 void rand_initialize_irq(int irq)
1562 struct timer_rand_state *state;
1564 if (irq >= NR_IRQS || irq_timer_state[irq])
1568 * If kmalloc returns null, we just won't use that entropy
1571 state = kmalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
1573 memset(state, 0, sizeof(struct timer_rand_state));
1574 irq_timer_state[irq] = state;
1578 void rand_initialize_disk(struct gendisk *disk)
1580 struct timer_rand_state *state;
1583 * If kmalloc returns null, we just won't use that entropy
1586 state = kmalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
1588 memset(state, 0, sizeof(struct timer_rand_state));
1589 disk->random = state;
1594 random_read(struct file * file, char __user * buf, size_t nbytes, loff_t *ppos)
1596 DECLARE_WAITQUEUE(wait, current);
1597 ssize_t n, retval = 0, count = 0;
1602 while (nbytes > 0) {
1604 if (n > SEC_XFER_SIZE)
1607 DEBUG_ENT("%04d %04d : reading %d bits, p: %d s: %d\n",
1608 random_state->entropy_count,
1609 sec_random_state->entropy_count,
1610 n*8, random_state->entropy_count,
1611 sec_random_state->entropy_count);
1613 n = extract_entropy(sec_random_state, buf, n,
1614 EXTRACT_ENTROPY_USER |
1615 EXTRACT_ENTROPY_LIMIT |
1616 EXTRACT_ENTROPY_SECONDARY);
1618 DEBUG_ENT("%04d %04d : read got %d bits (%d still needed)\n",
1619 random_state->entropy_count,
1620 sec_random_state->entropy_count,
1624 if (file->f_flags & O_NONBLOCK) {
1628 if (signal_pending(current)) {
1629 retval = -ERESTARTSYS;
1633 DEBUG_ENT("%04d %04d : sleeping?\n",
1634 random_state->entropy_count,
1635 sec_random_state->entropy_count);
1637 set_current_state(TASK_INTERRUPTIBLE);
1638 add_wait_queue(&random_read_wait, &wait);
1640 if (sec_random_state->entropy_count / 8 == 0)
1643 set_current_state(TASK_RUNNING);
1644 remove_wait_queue(&random_read_wait, &wait);
1646 DEBUG_ENT("%04d %04d : waking up\n",
1647 random_state->entropy_count,
1648 sec_random_state->entropy_count);
1660 break; /* This break makes the device work */
1661 /* like a named pipe */
1665 * If we gave the user some bytes, update the access time.
1668 file_accessed(file);
1670 return (count ? count : retval);
1674 urandom_read(struct file * file, char __user * buf,
1675 size_t nbytes, loff_t *ppos)
1677 return extract_entropy(sec_random_state, buf, nbytes,
1678 EXTRACT_ENTROPY_USER |
1679 EXTRACT_ENTROPY_SECONDARY);
1683 random_poll(struct file *file, poll_table * wait)
1687 poll_wait(file, &random_read_wait, wait);
1688 poll_wait(file, &random_write_wait, wait);
1690 if (random_state->entropy_count >= random_read_wakeup_thresh)
1691 mask |= POLLIN | POLLRDNORM;
1692 if (random_state->entropy_count < random_write_wakeup_thresh)
1693 mask |= POLLOUT | POLLWRNORM;
1698 random_write(struct file * file, const char __user * buffer,
1699 size_t count, loff_t *ppos)
1704 const char __user *p = buffer;
1708 bytes = min(c, sizeof(buf));
1710 bytes -= copy_from_user(&buf, p, bytes);
1718 add_entropy_words(random_state, buf, (bytes + 3) / 4);
1721 return (ssize_t)ret;
1723 file->f_dentry->d_inode->i_mtime = CURRENT_TIME;
1724 mark_inode_dirty(file->f_dentry->d_inode);
1725 return (ssize_t)(p - buffer);
1730 random_ioctl(struct inode * inode, struct file * file,
1731 unsigned int cmd, unsigned long arg)
1733 int *tmp, size, ent_count;
1734 int __user *p = (int __user *)arg;
1736 unsigned long flags;
1740 ent_count = random_state->entropy_count;
1741 if (put_user(ent_count, p))
1744 case RNDADDTOENTCNT:
1745 if (!capable(CAP_SYS_ADMIN))
1747 if (get_user(ent_count, p))
1749 credit_entropy_store(random_state, ent_count);
1751 * Wake up waiting processes if we have enough
1754 if (random_state->entropy_count >= random_read_wakeup_thresh)
1755 wake_up_interruptible(&random_read_wait);
1758 if (!capable(CAP_SYS_ADMIN))
1760 if (get_user(size, p) ||
1761 put_user(random_state->poolinfo.poolwords, p++))
1765 if (size > random_state->poolinfo.poolwords)
1766 size = random_state->poolinfo.poolwords;
1768 /* prepare to atomically snapshot pool */
1770 tmp = kmalloc(size * sizeof(__u32), GFP_KERNEL);
1775 spin_lock_irqsave(&random_state->lock, flags);
1776 ent_count = random_state->entropy_count;
1777 memcpy(tmp, random_state->pool, size * sizeof(__u32));
1778 spin_unlock_irqrestore(&random_state->lock, flags);
1780 if (!copy_to_user(p, tmp, size * sizeof(__u32))) {
1787 if(put_user(ent_count, p++))
1792 if (!capable(CAP_SYS_ADMIN))
1794 if (get_user(ent_count, p++))
1798 if (get_user(size, p++))
1800 retval = random_write(file, (const char __user *) p,
1801 size, &file->f_pos);
1804 credit_entropy_store(random_state, ent_count);
1806 * Wake up waiting processes if we have enough
1809 if (random_state->entropy_count >= random_read_wakeup_thresh)
1810 wake_up_interruptible(&random_read_wait);
1813 if (!capable(CAP_SYS_ADMIN))
1815 random_state->entropy_count = 0;
1818 /* Clear the entropy pool and associated counters. */
1819 if (!capable(CAP_SYS_ADMIN))
1821 clear_entropy_store(random_state);
1822 init_std_data(random_state);
1829 struct file_operations random_fops = {
1830 .read = random_read,
1831 .write = random_write,
1832 .poll = random_poll,
1833 .ioctl = random_ioctl,
1836 struct file_operations urandom_fops = {
1837 .read = urandom_read,
1838 .write = random_write,
1839 .ioctl = random_ioctl,
1842 /***************************************************************
1843 * Random UUID interface
1845 * Used here for a Boot ID, but can be useful for other kernel
1847 ***************************************************************/
1850 * Generate random UUID
1852 void generate_random_uuid(unsigned char uuid_out[16])
1854 get_random_bytes(uuid_out, 16);
1855 /* Set UUID version to 4 --- truely random generation */
1856 uuid_out[6] = (uuid_out[6] & 0x0F) | 0x40;
1857 /* Set the UUID variant to DCE */
1858 uuid_out[8] = (uuid_out[8] & 0x3F) | 0x80;
1861 EXPORT_SYMBOL(generate_random_uuid);
1863 /********************************************************************
1867 ********************************************************************/
1869 #ifdef CONFIG_SYSCTL
1871 #include <linux/sysctl.h>
1873 static int sysctl_poolsize;
1874 static int min_read_thresh, max_read_thresh;
1875 static int min_write_thresh, max_write_thresh;
1876 static char sysctl_bootid[16];
1879 * This function handles a request from the user to change the pool size
1880 * of the primary entropy store.
1882 static int change_poolsize(int poolsize)
1884 struct entropy_store *new_store, *old_store;
1887 if ((ret = create_entropy_store(poolsize, &new_store)))
1890 add_entropy_words(new_store, random_state->pool,
1891 random_state->poolinfo.poolwords);
1892 credit_entropy_store(new_store, random_state->entropy_count);
1894 sysctl_init_random(new_store);
1895 old_store = random_state;
1896 random_state = batch_work.data = new_store;
1897 free_entropy_store(old_store);
1901 static int proc_do_poolsize(ctl_table *table, int write, struct file *filp,
1902 void __user *buffer, size_t *lenp, loff_t *ppos)
1906 sysctl_poolsize = random_state->poolinfo.POOLBYTES;
1908 ret = proc_dointvec(table, write, filp, buffer, lenp, ppos);
1909 if (ret || !write ||
1910 (sysctl_poolsize == random_state->poolinfo.POOLBYTES))
1913 return change_poolsize(sysctl_poolsize);
1916 static int poolsize_strategy(ctl_table *table, int __user *name, int nlen,
1917 void __user *oldval, size_t __user *oldlenp,
1918 void __user *newval, size_t newlen, void **context)
1922 sysctl_poolsize = random_state->poolinfo.POOLBYTES;
1925 * We only handle the write case, since the read case gets
1926 * handled by the default handler (and we don't care if the
1927 * write case happens twice; it's harmless).
1929 if (newval && newlen) {
1931 if (len > table->maxlen)
1932 len = table->maxlen;
1933 if (copy_from_user(table->data, newval, len))
1937 if (sysctl_poolsize != random_state->poolinfo.POOLBYTES)
1938 return change_poolsize(sysctl_poolsize);
1944 * These functions is used to return both the bootid UUID, and random
1945 * UUID. The difference is in whether table->data is NULL; if it is,
1946 * then a new UUID is generated and returned to the user.
1948 * If the user accesses this via the proc interface, it will be returned
1949 * as an ASCII string in the standard UUID format. If accesses via the
1950 * sysctl system call, it is returned as 16 bytes of binary data.
1952 static int proc_do_uuid(ctl_table *table, int write, struct file *filp,
1953 void __user *buffer, size_t *lenp, loff_t *ppos)
1955 ctl_table fake_table;
1956 unsigned char buf[64], tmp_uuid[16], *uuid;
1964 generate_random_uuid(uuid);
1966 sprintf(buf, "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-"
1967 "%02x%02x%02x%02x%02x%02x",
1968 uuid[0], uuid[1], uuid[2], uuid[3],
1969 uuid[4], uuid[5], uuid[6], uuid[7],
1970 uuid[8], uuid[9], uuid[10], uuid[11],
1971 uuid[12], uuid[13], uuid[14], uuid[15]);
1972 fake_table.data = buf;
1973 fake_table.maxlen = sizeof(buf);
1975 return proc_dostring(&fake_table, write, filp, buffer, lenp, ppos);
1978 static int uuid_strategy(ctl_table *table, int __user *name, int nlen,
1979 void __user *oldval, size_t __user *oldlenp,
1980 void __user *newval, size_t newlen, void **context)
1982 unsigned char tmp_uuid[16], *uuid;
1985 if (!oldval || !oldlenp)
1994 generate_random_uuid(uuid);
1996 if (get_user(len, oldlenp))
2001 if (copy_to_user(oldval, uuid, len) ||
2002 put_user(len, oldlenp))
2008 ctl_table random_table[] = {
2010 .ctl_name = RANDOM_POOLSIZE,
2011 .procname = "poolsize",
2012 .data = &sysctl_poolsize,
2013 .maxlen = sizeof(int),
2015 .proc_handler = &proc_do_poolsize,
2016 .strategy = &poolsize_strategy,
2019 .ctl_name = RANDOM_ENTROPY_COUNT,
2020 .procname = "entropy_avail",
2021 .maxlen = sizeof(int),
2023 .proc_handler = &proc_dointvec,
2026 .ctl_name = RANDOM_READ_THRESH,
2027 .procname = "read_wakeup_threshold",
2028 .data = &random_read_wakeup_thresh,
2029 .maxlen = sizeof(int),
2031 .proc_handler = &proc_dointvec_minmax,
2032 .strategy = &sysctl_intvec,
2033 .extra1 = &min_read_thresh,
2034 .extra2 = &max_read_thresh,
2037 .ctl_name = RANDOM_WRITE_THRESH,
2038 .procname = "write_wakeup_threshold",
2039 .data = &random_write_wakeup_thresh,
2040 .maxlen = sizeof(int),
2042 .proc_handler = &proc_dointvec_minmax,
2043 .strategy = &sysctl_intvec,
2044 .extra1 = &min_write_thresh,
2045 .extra2 = &max_write_thresh,
2048 .ctl_name = RANDOM_BOOT_ID,
2049 .procname = "boot_id",
2050 .data = &sysctl_bootid,
2053 .proc_handler = &proc_do_uuid,
2054 .strategy = &uuid_strategy,
2057 .ctl_name = RANDOM_UUID,
2061 .proc_handler = &proc_do_uuid,
2062 .strategy = &uuid_strategy,
2067 static void sysctl_init_random(struct entropy_store *random_state)
2069 min_read_thresh = 8;
2070 min_write_thresh = 0;
2071 max_read_thresh = max_write_thresh = random_state->poolinfo.POOLBITS;
2072 random_table[1].data = &random_state->entropy_count;
2074 #endif /* CONFIG_SYSCTL */
2076 /********************************************************************
2078 * Random funtions for networking
2080 ********************************************************************/
2083 * TCP initial sequence number picking. This uses the random number
2084 * generator to pick an initial secret value. This value is hashed
2085 * along with the TCP endpoint information to provide a unique
2086 * starting point for each pair of TCP endpoints. This defeats
2087 * attacks which rely on guessing the initial TCP sequence number.
2088 * This algorithm was suggested by Steve Bellovin.
2090 * Using a very strong hash was taking an appreciable amount of the total
2091 * TCP connection establishment time, so this is a weaker hash,
2092 * compensated for by changing the secret periodically.
2095 /* F, G and H are basic MD4 functions: selection, majority, parity */
2096 #define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
2097 #define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
2098 #define H(x, y, z) ((x) ^ (y) ^ (z))
2101 * The generic round function. The application is so specific that
2102 * we don't bother protecting all the arguments with parens, as is generally
2103 * good macro practice, in favor of extra legibility.
2104 * Rotation is separate from addition to prevent recomputation
2106 #define ROUND(f, a, b, c, d, x, s) \
2107 (a += f(b, c, d) + x, a = (a << s) | (a >> (32-s)))
2109 #define K2 013240474631UL
2110 #define K3 015666365641UL
2113 * Basic cut-down MD4 transform. Returns only 32 bits of result.
2115 static __u32 halfMD4Transform (__u32 const buf[4], __u32 const in[8])
2117 __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
2120 ROUND(F, a, b, c, d, in[0] + K1, 3);
2121 ROUND(F, d, a, b, c, in[1] + K1, 7);
2122 ROUND(F, c, d, a, b, in[2] + K1, 11);
2123 ROUND(F, b, c, d, a, in[3] + K1, 19);
2124 ROUND(F, a, b, c, d, in[4] + K1, 3);
2125 ROUND(F, d, a, b, c, in[5] + K1, 7);
2126 ROUND(F, c, d, a, b, in[6] + K1, 11);
2127 ROUND(F, b, c, d, a, in[7] + K1, 19);
2130 ROUND(G, a, b, c, d, in[1] + K2, 3);
2131 ROUND(G, d, a, b, c, in[3] + K2, 5);
2132 ROUND(G, c, d, a, b, in[5] + K2, 9);
2133 ROUND(G, b, c, d, a, in[7] + K2, 13);
2134 ROUND(G, a, b, c, d, in[0] + K2, 3);
2135 ROUND(G, d, a, b, c, in[2] + K2, 5);
2136 ROUND(G, c, d, a, b, in[4] + K2, 9);
2137 ROUND(G, b, c, d, a, in[6] + K2, 13);
2140 ROUND(H, a, b, c, d, in[3] + K3, 3);
2141 ROUND(H, d, a, b, c, in[7] + K3, 9);
2142 ROUND(H, c, d, a, b, in[2] + K3, 11);
2143 ROUND(H, b, c, d, a, in[6] + K3, 15);
2144 ROUND(H, a, b, c, d, in[1] + K3, 3);
2145 ROUND(H, d, a, b, c, in[5] + K3, 9);
2146 ROUND(H, c, d, a, b, in[0] + K3, 11);
2147 ROUND(H, b, c, d, a, in[4] + K3, 15);
2149 return buf[1] + b; /* "most hashed" word */
2150 /* Alternative: return sum of all words? */
2153 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
2155 static __u32 twothirdsMD4Transform (__u32 const buf[4], __u32 const in[12])
2157 __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
2160 ROUND(F, a, b, c, d, in[ 0] + K1, 3);
2161 ROUND(F, d, a, b, c, in[ 1] + K1, 7);
2162 ROUND(F, c, d, a, b, in[ 2] + K1, 11);
2163 ROUND(F, b, c, d, a, in[ 3] + K1, 19);
2164 ROUND(F, a, b, c, d, in[ 4] + K1, 3);
2165 ROUND(F, d, a, b, c, in[ 5] + K1, 7);
2166 ROUND(F, c, d, a, b, in[ 6] + K1, 11);
2167 ROUND(F, b, c, d, a, in[ 7] + K1, 19);
2168 ROUND(F, a, b, c, d, in[ 8] + K1, 3);
2169 ROUND(F, d, a, b, c, in[ 9] + K1, 7);
2170 ROUND(F, c, d, a, b, in[10] + K1, 11);
2171 ROUND(F, b, c, d, a, in[11] + K1, 19);
2174 ROUND(G, a, b, c, d, in[ 1] + K2, 3);
2175 ROUND(G, d, a, b, c, in[ 3] + K2, 5);
2176 ROUND(G, c, d, a, b, in[ 5] + K2, 9);
2177 ROUND(G, b, c, d, a, in[ 7] + K2, 13);
2178 ROUND(G, a, b, c, d, in[ 9] + K2, 3);
2179 ROUND(G, d, a, b, c, in[11] + K2, 5);
2180 ROUND(G, c, d, a, b, in[ 0] + K2, 9);
2181 ROUND(G, b, c, d, a, in[ 2] + K2, 13);
2182 ROUND(G, a, b, c, d, in[ 4] + K2, 3);
2183 ROUND(G, d, a, b, c, in[ 6] + K2, 5);
2184 ROUND(G, c, d, a, b, in[ 8] + K2, 9);
2185 ROUND(G, b, c, d, a, in[10] + K2, 13);
2188 ROUND(H, a, b, c, d, in[ 3] + K3, 3);
2189 ROUND(H, d, a, b, c, in[ 7] + K3, 9);
2190 ROUND(H, c, d, a, b, in[11] + K3, 11);
2191 ROUND(H, b, c, d, a, in[ 2] + K3, 15);
2192 ROUND(H, a, b, c, d, in[ 6] + K3, 3);
2193 ROUND(H, d, a, b, c, in[10] + K3, 9);
2194 ROUND(H, c, d, a, b, in[ 1] + K3, 11);
2195 ROUND(H, b, c, d, a, in[ 5] + K3, 15);
2196 ROUND(H, a, b, c, d, in[ 9] + K3, 3);
2197 ROUND(H, d, a, b, c, in[ 0] + K3, 9);
2198 ROUND(H, c, d, a, b, in[ 4] + K3, 11);
2199 ROUND(H, b, c, d, a, in[ 8] + K3, 15);
2201 return buf[1] + b; /* "most hashed" word */
2202 /* Alternative: return sum of all words? */
2214 /* This should not be decreased so low that ISNs wrap too fast. */
2215 #define REKEY_INTERVAL 300
2217 * Bit layout of the tcp sequence numbers (before adding current time):
2218 * bit 24-31: increased after every key exchange
2219 * bit 0-23: hash(source,dest)
2221 * The implementation is similar to the algorithm described
2222 * in the Appendix of RFC 1185, except that
2223 * - it uses a 1 MHz clock instead of a 250 kHz clock
2224 * - it performs a rekey every 5 minutes, which is equivalent
2225 * to a (source,dest) tulple dependent forward jump of the
2226 * clock by 0..2^(HASH_BITS+1)
2228 * Thus the average ISN wraparound time is 68 minutes instead of
2231 * SMP cleanup and lock avoidance with poor man's RCU.
2232 * Manfred Spraul <manfred@colorfullife.com>
2235 #define COUNT_BITS 8
2236 #define COUNT_MASK ( (1<<COUNT_BITS)-1)
2237 #define HASH_BITS 24
2238 #define HASH_MASK ( (1<<HASH_BITS)-1 )
2240 static struct keydata {
2242 __u32 count; // already shifted to the final position
2244 } ____cacheline_aligned ip_keydata[2];
2246 static spinlock_t ip_lock = SPIN_LOCK_UNLOCKED;
2247 static unsigned int ip_cnt;
2249 static struct keydata *__check_and_rekey(time_t time)
2251 struct keydata *keyptr;
2252 spin_lock_bh(&ip_lock);
2253 keyptr = &ip_keydata[ip_cnt&1];
2254 if (!keyptr->rekey_time || (time - keyptr->rekey_time) > REKEY_INTERVAL) {
2255 keyptr = &ip_keydata[1^(ip_cnt&1)];
2256 keyptr->rekey_time = time;
2257 get_random_bytes(keyptr->secret, sizeof(keyptr->secret));
2258 keyptr->count = (ip_cnt&COUNT_MASK)<<HASH_BITS;
2262 spin_unlock_bh(&ip_lock);
2266 static inline struct keydata *check_and_rekey(time_t time)
2268 struct keydata *keyptr = &ip_keydata[ip_cnt&1];
2271 if (!keyptr->rekey_time || (time - keyptr->rekey_time) > REKEY_INTERVAL) {
2272 keyptr = __check_and_rekey(time);
2278 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
2279 __u32 secure_tcpv6_sequence_number(__u32 *saddr, __u32 *daddr,
2280 __u16 sport, __u16 dport)
2285 struct keydata *keyptr;
2287 /* The procedure is the same as for IPv4, but addresses are longer.
2288 * Thus we must use twothirdsMD4Transform.
2291 do_gettimeofday(&tv); /* We need the usecs below... */
2292 keyptr = check_and_rekey(tv.tv_sec);
2294 memcpy(hash, saddr, 16);
2295 hash[4]=(sport << 16) + dport;
2296 memcpy(&hash[5],keyptr->secret,sizeof(__u32)*7);
2298 seq = twothirdsMD4Transform(daddr, hash) & HASH_MASK;
2299 seq += keyptr->count;
2300 seq += tv.tv_usec + tv.tv_sec*1000000;
2304 EXPORT_SYMBOL(secure_tcpv6_sequence_number);
2306 __u32 secure_ipv6_id(__u32 *daddr)
2308 struct keydata *keyptr;
2310 keyptr = check_and_rekey(get_seconds());
2312 return halfMD4Transform(daddr, keyptr->secret);
2315 EXPORT_SYMBOL(secure_ipv6_id);
2319 __u32 secure_tcp_sequence_number(__u32 saddr, __u32 daddr,
2320 __u16 sport, __u16 dport)
2325 struct keydata *keyptr;
2328 * Pick a random secret every REKEY_INTERVAL seconds.
2330 do_gettimeofday(&tv); /* We need the usecs below... */
2331 keyptr = check_and_rekey(tv.tv_sec);
2334 * Pick a unique starting offset for each TCP connection endpoints
2335 * (saddr, daddr, sport, dport).
2336 * Note that the words are placed into the starting vector, which is
2337 * then mixed with a partial MD4 over random data.
2341 hash[2]=(sport << 16) + dport;
2342 hash[3]=keyptr->secret[11];
2344 seq = halfMD4Transform(hash, keyptr->secret) & HASH_MASK;
2345 seq += keyptr->count;
2347 * As close as possible to RFC 793, which
2348 * suggests using a 250 kHz clock.
2349 * Further reading shows this assumes 2 Mb/s networks.
2350 * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
2351 * That's funny, Linux has one built in! Use it!
2352 * (Networks are faster now - should this be increased?)
2354 seq += tv.tv_usec + tv.tv_sec*1000000;
2356 printk("init_seq(%lx, %lx, %d, %d) = %d\n",
2357 saddr, daddr, sport, dport, seq);
2362 EXPORT_SYMBOL(secure_tcp_sequence_number);
2364 /* The code below is shamelessly stolen from secure_tcp_sequence_number().
2365 * All blames to Andrey V. Savochkin <saw@msu.ru>.
2367 __u32 secure_ip_id(__u32 daddr)
2369 struct keydata *keyptr;
2372 keyptr = check_and_rekey(get_seconds());
2375 * Pick a unique starting offset for each IP destination.
2376 * The dest ip address is placed in the starting vector,
2377 * which is then hashed with random data.
2380 hash[1] = keyptr->secret[9];
2381 hash[2] = keyptr->secret[10];
2382 hash[3] = keyptr->secret[11];
2384 return halfMD4Transform(hash, keyptr->secret);
2387 #ifdef CONFIG_SYN_COOKIES
2389 * Secure SYN cookie computation. This is the algorithm worked out by
2390 * Dan Bernstein and Eric Schenk.
2392 * For linux I implement the 1 minute counter by looking at the jiffies clock.
2393 * The count is passed in as a parameter, so this code doesn't much care.
2396 #define COOKIEBITS 24 /* Upper bits store count */
2397 #define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
2399 static int syncookie_init;
2400 static __u32 syncookie_secret[2][16-3+HASH_BUFFER_SIZE];
2402 __u32 secure_tcp_syn_cookie(__u32 saddr, __u32 daddr, __u16 sport,
2403 __u16 dport, __u32 sseq, __u32 count, __u32 data)
2405 __u32 tmp[16 + HASH_BUFFER_SIZE + HASH_EXTRA_SIZE];
2409 * Pick two random secrets the first time we need a cookie.
2411 if (syncookie_init == 0) {
2412 get_random_bytes(syncookie_secret, sizeof(syncookie_secret));
2417 * Compute the secure sequence number.
2418 * The output should be:
2419 * HASH(sec1,saddr,sport,daddr,dport,sec1) + sseq + (count * 2^24)
2420 * + (HASH(sec2,saddr,sport,daddr,dport,count,sec2) % 2^24).
2421 * Where sseq is their sequence number and count increases every
2423 * As an extra hack, we add a small "data" value that encodes the
2424 * MSS into the second hash value.
2427 memcpy(tmp+3, syncookie_secret[0], sizeof(syncookie_secret[0]));
2430 tmp[2]=(sport << 16) + dport;
2431 HASH_TRANSFORM(tmp+16, tmp);
2432 seq = tmp[17] + sseq + (count << COOKIEBITS);
2434 memcpy(tmp+3, syncookie_secret[1], sizeof(syncookie_secret[1]));
2437 tmp[2]=(sport << 16) + dport;
2438 tmp[3] = count; /* minute counter */
2439 HASH_TRANSFORM(tmp+16, tmp);
2441 /* Add in the second hash and the data */
2442 return seq + ((tmp[17] + data) & COOKIEMASK);
2446 * This retrieves the small "data" value from the syncookie.
2447 * If the syncookie is bad, the data returned will be out of
2448 * range. This must be checked by the caller.
2450 * The count value used to generate the cookie must be within
2451 * "maxdiff" if the current (passed-in) "count". The return value
2452 * is (__u32)-1 if this test fails.
2454 __u32 check_tcp_syn_cookie(__u32 cookie, __u32 saddr, __u32 daddr, __u16 sport,
2455 __u16 dport, __u32 sseq, __u32 count, __u32 maxdiff)
2457 __u32 tmp[16 + HASH_BUFFER_SIZE + HASH_EXTRA_SIZE];
2460 if (syncookie_init == 0)
2461 return (__u32)-1; /* Well, duh! */
2463 /* Strip away the layers from the cookie */
2464 memcpy(tmp+3, syncookie_secret[0], sizeof(syncookie_secret[0]));
2467 tmp[2]=(sport << 16) + dport;
2468 HASH_TRANSFORM(tmp+16, tmp);
2469 cookie -= tmp[17] + sseq;
2470 /* Cookie is now reduced to (count * 2^24) ^ (hash % 2^24) */
2472 diff = (count - (cookie >> COOKIEBITS)) & ((__u32)-1 >> COOKIEBITS);
2473 if (diff >= maxdiff)
2476 memcpy(tmp+3, syncookie_secret[1], sizeof(syncookie_secret[1]));
2479 tmp[2] = (sport << 16) + dport;
2480 tmp[3] = count - diff; /* minute counter */
2481 HASH_TRANSFORM(tmp+16, tmp);
2483 return (cookie - tmp[17]) & COOKIEMASK; /* Leaving the data behind */