freebsd-dev/sys/kern/kern_random.c
1997-05-04 14:28:22 +00:00

516 lines
15 KiB
C

/*
* random_machdep.c -- A strong random number generator
*
* $Id: random_machdep.c,v 1.16 1997/04/26 11:46:03 peter Exp $
*
* Version 0.95, last modified 18-Oct-95
*
* Copyright Theodore Ts'o, 1994, 1995. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, and the entire permission notice in its entirety,
* including the disclaimer of warranties.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* ALTERNATIVELY, this product may be distributed under the terms of
* the GNU Public License, in which case the provisions of the GPL are
* required INSTEAD OF the above restrictions. (This clause is
* necessary due to a potential bad interaction between the GPL and
* the restrictions contained in a BSD-style copyright.)
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "opt_cpu.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/select.h>
#include <sys/fcntl.h>
#include <machine/clock.h>
#include <machine/random.h>
#include <i386/isa/icu.h>
#ifdef PC98
#include <pc98/pc98/pc98.h>
#else
#include <i386/isa/isa.h>
#endif
#include <i386/isa/timerreg.h>
#define MAX_BLKDEV 4
/*
* The pool is stirred with a primitive polynomial of degree 128
* over GF(2), namely x^128 + x^99 + x^59 + x^31 + x^9 + x^7 + 1.
* For a pool of size 64, try x^64+x^62+x^38+x^10+x^6+x+1.
*/
#define POOLWORDS 128 /* Power of 2 - note that this is 32-bit words */
#define POOLBITS (POOLWORDS*32)
#if POOLWORDS == 128
#define TAP1 99 /* The polynomial taps */
#define TAP2 59
#define TAP3 31
#define TAP4 9
#define TAP5 7
#elif POOLWORDS == 64
#define TAP1 62 /* The polynomial taps */
#define TAP2 38
#define TAP3 10
#define TAP4 6
#define TAP5 1
#else
#error No primitive polynomial available for chosen POOLWORDS
#endif
#define WRITEBUFFER 512 /* size in bytes */
/* There is actually only one of these, globally. */
struct random_bucket {
u_int add_ptr;
u_int entropy_count;
int input_rotate;
u_int32_t *pool;
struct selinfo rsel;
};
/* There is one of these per entropy source */
struct timer_rand_state {
u_long last_time;
int last_delta;
int nbits;
};
static struct random_bucket random_state;
static u_int32_t random_pool[POOLWORDS];
static struct timer_rand_state keyboard_timer_state;
static struct timer_rand_state extract_timer_state;
static struct timer_rand_state irq_timer_state[ICU_LEN];
#ifdef notyet
static struct timer_rand_state blkdev_timer_state[MAX_BLKDEV];
#endif
static struct wait_queue *random_wait;
inthand2_t *sec_intr_handler[ICU_LEN];
int sec_intr_unit[ICU_LEN];
#ifndef MIN
#define MIN(a,b) (((a) < (b)) ? (a) : (b))
#endif
void
rand_initialize(void)
{
random_state.add_ptr = 0;
random_state.entropy_count = 0;
random_state.pool = random_pool;
random_wait = NULL;
random_state.rsel.si_flags = 0;
random_state.rsel.si_pid = 0;
}
/*
* This function adds an int into the entropy "pool". It does not
* update the entropy estimate. The caller must do this if appropriate.
*
* The pool is stirred with a primitive polynomial of degree 128
* over GF(2), namely x^128 + x^99 + x^59 + x^31 + x^9 + x^7 + 1.
* For a pool of size 64, try x^64+x^62+x^38+x^10+x^6+x+1.
*
* We rotate the input word by a changing number of bits, to help
* assure that all bits in the entropy get toggled. Otherwise, if we
* consistently feed the entropy pool small numbers (like ticks and
* scancodes, for example), the upper bits of the entropy pool don't
* get affected. --- TYT, 10/11/95
*/
static inline void
add_entropy_word(struct random_bucket *r, const u_int32_t input)
{
u_int i;
u_int32_t w;
w = (input << r->input_rotate) | (input >> (32 - r->input_rotate));
i = r->add_ptr = (r->add_ptr - 1) & (POOLWORDS-1);
if (i)
r->input_rotate = (r->input_rotate + 7) & 31;
else
/*
* At the beginning of the pool, add an extra 7 bits
* rotation, so that successive passes spread the
* input bits across the pool evenly.
*/
r->input_rotate = (r->input_rotate + 14) & 31;
/* XOR in the various taps */
w ^= r->pool[(i+TAP1)&(POOLWORDS-1)];
w ^= r->pool[(i+TAP2)&(POOLWORDS-1)];
w ^= r->pool[(i+TAP3)&(POOLWORDS-1)];
w ^= r->pool[(i+TAP4)&(POOLWORDS-1)];
w ^= r->pool[(i+TAP5)&(POOLWORDS-1)];
w ^= r->pool[i];
/* Rotate w left 1 bit (stolen from SHA) and store */
r->pool[i] = (w << 1) | (w >> 31);
}
/*
* This function adds entropy to the entropy "pool" by using timing
* delays. It uses the timer_rand_state structure to make an estimate
* of how any bits of entropy this call has added to the pool.
*
* The number "num" is also added to the pool - it should somehow describe
* the type of event which just happened. This is currently 0-255 for
* keyboard scan codes, and 256 upwards for interrupts.
* On the i386, this is assumed to be at most 16 bits, and the high bits
* are used for a high-resolution timer.
*/
static void
add_timer_randomness(struct random_bucket *r, struct timer_rand_state *state,
u_int num)
{
int delta, delta2;
u_int nbits;
u_int32_t time;
#if defined(I586_CPU) || defined(I686_CPU)
if (i586_ctr_freq != 0) {
num ^= (u_int32_t) rdtsc() << 16;
r->entropy_count += 2;
} else {
#endif
disable_intr();
outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
num ^= inb(TIMER_CNTR0) << 16;
num ^= inb(TIMER_CNTR0) << 24;
enable_intr();
r->entropy_count += 2;
#if defined(I586_CPU) || defined(I686_CPU)
}
#endif
time = ticks;
add_entropy_word(r, (u_int32_t) num);
add_entropy_word(r, time);
/*
* Calculate number of bits of randomness we probably
* added. We take into account the first and second order
* deltas in order to make our estimate.
*/
delta = time - state->last_time;
state->last_time = time;
delta2 = delta - state->last_delta;
state->last_delta = delta;
if (delta < 0) delta = -delta;
if (delta2 < 0) delta2 = -delta2;
delta = MIN(delta, delta2) >> 1;
for (nbits = 0; delta; nbits++)
delta >>= 1;
r->entropy_count += nbits;
/* Prevent overflow */
if (r->entropy_count > POOLBITS)
r->entropy_count = POOLBITS;
if (r->entropy_count >= 8)
selwakeup(&random_state.rsel);
}
void
add_keyboard_randomness(u_char scancode)
{
add_timer_randomness(&random_state, &keyboard_timer_state, scancode);
}
void
add_interrupt_randomness(int irq)
{
(sec_intr_handler[irq])(sec_intr_unit[irq]);
add_timer_randomness(&random_state, &irq_timer_state[irq], irq);
}
#ifdef notused
void
add_blkdev_randomness(int major)
{
if (major >= MAX_BLKDEV)
return;
add_timer_randomness(&random_state, &blkdev_timer_state[major],
0x200+major);
}
#endif /* notused */
/*
* MD5 transform algorithm, taken from code written by Colin Plumb,
* and put into the public domain
*
* QUESTION: Replace this with SHA, which as generally received better
* reviews from the cryptographic community?
*/
/* The four core functions - F1 is optimized somewhat */
/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))
/* This is the central step in the MD5 algorithm. */
#define MD5STEP(f, w, x, y, z, data, s) \
( w += f(x, y, z) + data, w = w<<s | w>>(32-s), w += x )
/*
* The core of the MD5 algorithm, this alters an existing MD5 hash to
* reflect the addition of 16 longwords of new data. MD5Update blocks
* the data and converts bytes into longwords for this routine.
*/
static void
MD5Transform(u_int32_t buf[4],
u_int32_t const in[16])
{
u_int32_t a, b, c, d;
a = buf[0];
b = buf[1];
c = buf[2];
d = buf[3];
MD5STEP(F1, a, b, c, d, in[ 0]+0xd76aa478, 7);
MD5STEP(F1, d, a, b, c, in[ 1]+0xe8c7b756, 12);
MD5STEP(F1, c, d, a, b, in[ 2]+0x242070db, 17);
MD5STEP(F1, b, c, d, a, in[ 3]+0xc1bdceee, 22);
MD5STEP(F1, a, b, c, d, in[ 4]+0xf57c0faf, 7);
MD5STEP(F1, d, a, b, c, in[ 5]+0x4787c62a, 12);
MD5STEP(F1, c, d, a, b, in[ 6]+0xa8304613, 17);
MD5STEP(F1, b, c, d, a, in[ 7]+0xfd469501, 22);
MD5STEP(F1, a, b, c, d, in[ 8]+0x698098d8, 7);
MD5STEP(F1, d, a, b, c, in[ 9]+0x8b44f7af, 12);
MD5STEP(F1, c, d, a, b, in[10]+0xffff5bb1, 17);
MD5STEP(F1, b, c, d, a, in[11]+0x895cd7be, 22);
MD5STEP(F1, a, b, c, d, in[12]+0x6b901122, 7);
MD5STEP(F1, d, a, b, c, in[13]+0xfd987193, 12);
MD5STEP(F1, c, d, a, b, in[14]+0xa679438e, 17);
MD5STEP(F1, b, c, d, a, in[15]+0x49b40821, 22);
MD5STEP(F2, a, b, c, d, in[ 1]+0xf61e2562, 5);
MD5STEP(F2, d, a, b, c, in[ 6]+0xc040b340, 9);
MD5STEP(F2, c, d, a, b, in[11]+0x265e5a51, 14);
MD5STEP(F2, b, c, d, a, in[ 0]+0xe9b6c7aa, 20);
MD5STEP(F2, a, b, c, d, in[ 5]+0xd62f105d, 5);
MD5STEP(F2, d, a, b, c, in[10]+0x02441453, 9);
MD5STEP(F2, c, d, a, b, in[15]+0xd8a1e681, 14);
MD5STEP(F2, b, c, d, a, in[ 4]+0xe7d3fbc8, 20);
MD5STEP(F2, a, b, c, d, in[ 9]+0x21e1cde6, 5);
MD5STEP(F2, d, a, b, c, in[14]+0xc33707d6, 9);
MD5STEP(F2, c, d, a, b, in[ 3]+0xf4d50d87, 14);
MD5STEP(F2, b, c, d, a, in[ 8]+0x455a14ed, 20);
MD5STEP(F2, a, b, c, d, in[13]+0xa9e3e905, 5);
MD5STEP(F2, d, a, b, c, in[ 2]+0xfcefa3f8, 9);
MD5STEP(F2, c, d, a, b, in[ 7]+0x676f02d9, 14);
MD5STEP(F2, b, c, d, a, in[12]+0x8d2a4c8a, 20);
MD5STEP(F3, a, b, c, d, in[ 5]+0xfffa3942, 4);
MD5STEP(F3, d, a, b, c, in[ 8]+0x8771f681, 11);
MD5STEP(F3, c, d, a, b, in[11]+0x6d9d6122, 16);
MD5STEP(F3, b, c, d, a, in[14]+0xfde5380c, 23);
MD5STEP(F3, a, b, c, d, in[ 1]+0xa4beea44, 4);
MD5STEP(F3, d, a, b, c, in[ 4]+0x4bdecfa9, 11);
MD5STEP(F3, c, d, a, b, in[ 7]+0xf6bb4b60, 16);
MD5STEP(F3, b, c, d, a, in[10]+0xbebfbc70, 23);
MD5STEP(F3, a, b, c, d, in[13]+0x289b7ec6, 4);
MD5STEP(F3, d, a, b, c, in[ 0]+0xeaa127fa, 11);
MD5STEP(F3, c, d, a, b, in[ 3]+0xd4ef3085, 16);
MD5STEP(F3, b, c, d, a, in[ 6]+0x04881d05, 23);
MD5STEP(F3, a, b, c, d, in[ 9]+0xd9d4d039, 4);
MD5STEP(F3, d, a, b, c, in[12]+0xe6db99e5, 11);
MD5STEP(F3, c, d, a, b, in[15]+0x1fa27cf8, 16);
MD5STEP(F3, b, c, d, a, in[ 2]+0xc4ac5665, 23);
MD5STEP(F4, a, b, c, d, in[ 0]+0xf4292244, 6);
MD5STEP(F4, d, a, b, c, in[ 7]+0x432aff97, 10);
MD5STEP(F4, c, d, a, b, in[14]+0xab9423a7, 15);
MD5STEP(F4, b, c, d, a, in[ 5]+0xfc93a039, 21);
MD5STEP(F4, a, b, c, d, in[12]+0x655b59c3, 6);
MD5STEP(F4, d, a, b, c, in[ 3]+0x8f0ccc92, 10);
MD5STEP(F4, c, d, a, b, in[10]+0xffeff47d, 15);
MD5STEP(F4, b, c, d, a, in[ 1]+0x85845dd1, 21);
MD5STEP(F4, a, b, c, d, in[ 8]+0x6fa87e4f, 6);
MD5STEP(F4, d, a, b, c, in[15]+0xfe2ce6e0, 10);
MD5STEP(F4, c, d, a, b, in[ 6]+0xa3014314, 15);
MD5STEP(F4, b, c, d, a, in[13]+0x4e0811a1, 21);
MD5STEP(F4, a, b, c, d, in[ 4]+0xf7537e82, 6);
MD5STEP(F4, d, a, b, c, in[11]+0xbd3af235, 10);
MD5STEP(F4, c, d, a, b, in[ 2]+0x2ad7d2bb, 15);
MD5STEP(F4, b, c, d, a, in[ 9]+0xeb86d391, 21);
buf[0] += a;
buf[1] += b;
buf[2] += c;
buf[3] += d;
}
#undef F1
#undef F2
#undef F3
#undef F4
#undef MD5STEP
#if POOLWORDS % 16
#error extract_entropy() assumes that POOLWORDS is a multiple of 16 words.
#endif
/*
* This function extracts randomness from the "entropy pool", and
* returns it in a buffer. This function computes how many remaining
* bits of entropy are left in the pool, but it does not restrict the
* number of bytes that are actually obtained.
*/
static inline int
extract_entropy(struct random_bucket *r, char *buf, int nbytes)
{
int ret, i;
u_int32_t tmp[4];
add_timer_randomness(r, &extract_timer_state, nbytes);
/* Redundant, but just in case... */
if (r->entropy_count > POOLBITS)
r->entropy_count = POOLBITS;
/* Why is this here? Left in from Ted Ts'o. Perhaps to limit time. */
if (nbytes > 32768)
nbytes = 32768;
ret = nbytes;
if (r->entropy_count / 8 >= nbytes)
r->entropy_count -= nbytes*8;
else
r->entropy_count = 0;
while (nbytes) {
/* Hash the pool to get the output */
tmp[0] = 0x67452301;
tmp[1] = 0xefcdab89;
tmp[2] = 0x98badcfe;
tmp[3] = 0x10325476;
for (i = 0; i < POOLWORDS; i += 16)
MD5Transform(tmp, r->pool+i);
/* Modify pool so next hash will produce different results */
add_entropy_word(r, tmp[0]);
add_entropy_word(r, tmp[1]);
add_entropy_word(r, tmp[2]);
add_entropy_word(r, tmp[3]);
/*
* Run the MD5 Transform one more time, since we want
* to add at least minimal obscuring of the inputs to
* add_entropy_word(). --- TYT
*/
MD5Transform(tmp, r->pool);
/* Copy data to destination buffer */
i = MIN(nbytes, 16);
bcopy(tmp, buf, i);
nbytes -= i;
buf += i;
}
/* Wipe data from memory */
bzero(tmp, sizeof(tmp));
return ret;
}
#ifdef notused /* XXX NOT the exported kernel interface */
/*
* This function is the exported kernel interface. It returns some
* number of good random numbers, suitable for seeding TCP sequence
* numbers, etc.
*/
void
get_random_bytes(void *buf, u_int nbytes)
{
extract_entropy(&random_state, (char *) buf, nbytes);
}
#endif /* notused */
u_int
read_random(char *buf, u_int nbytes)
{
if ((nbytes * 8) > random_state.entropy_count)
nbytes = random_state.entropy_count / 8;
return extract_entropy(&random_state, buf, nbytes);
}
u_int
read_random_unlimited(char *buf, u_int nbytes)
{
return extract_entropy(&random_state, buf, nbytes);
}
#ifdef notused
u_int
write_random(const char *buf, u_int nbytes)
{
u_int i;
u_int32_t word, *p;
for (i = nbytes, p = (u_int32_t *)buf;
i >= sizeof(u_int32_t);
i-= sizeof(u_int32_t), p++)
add_entropy_word(&random_state, *p);
if (i) {
word = 0;
bcopy(p, &word, i);
add_entropy_word(&random_state, word);
}
return nbytes;
}
#endif /* notused */
int
random_select(dev_t dev, int rw, struct proc *p)
{
int s, ret;
if (rw == FWRITE)
return 1; /* heh. */
s = splhigh();
if (random_state.entropy_count >= 8)
ret = 1;
else {
selrecord(p, &random_state.rsel);
ret = 0;
}
splx(s);
return ret;
}