394 lines
10 KiB
C
394 lines
10 KiB
C
/*
|
|
* kern_random.c -- A strong random number generator
|
|
*
|
|
* $FreeBSD$
|
|
*
|
|
* 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 <sys/param.h>
|
|
#include <sys/kernel.h>
|
|
#include <sys/md5.h>
|
|
#include <sys/poll.h>
|
|
#include <sys/random.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/select.h>
|
|
#include <sys/timetc.h>
|
|
|
|
#ifdef __i386__
|
|
#include <i386/isa/icu.h>
|
|
#endif
|
|
#ifdef __alpha__
|
|
/*
|
|
XXX the below should be used. However there is too much "16"
|
|
hardcodeing in kern_random.c right now. -- obrien
|
|
#include <machine/ipl.h>
|
|
#if NHWI > 0
|
|
#define ICU_LEN (NHWI)
|
|
#else
|
|
#define ICU_LEN (NSWI)
|
|
#endif
|
|
*/
|
|
#define ICU_LEN 16
|
|
#endif
|
|
|
|
#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;
|
|
|
|
#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;
|
|
|
|
num ^= timecounter->tc_get_timecount(timecounter) << 16;
|
|
r->entropy_count += 2;
|
|
|
|
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(void *vsc)
|
|
{
|
|
int intr;
|
|
struct random_softc *sc = vsc;
|
|
|
|
(sc->sc_handler)(sc->sc_arg);
|
|
intr = sc->sc_intr;
|
|
add_timer_randomness(&random_state, &irq_timer_state[intr], intr);
|
|
}
|
|
|
|
#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 */
|
|
|
|
#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, (char *)(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, (char *)(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(void *buf, u_int nbytes)
|
|
{
|
|
if ((nbytes * 8) > random_state.entropy_count)
|
|
nbytes = random_state.entropy_count / 8;
|
|
|
|
return extract_entropy(&random_state, (char *)buf, nbytes);
|
|
}
|
|
|
|
u_int
|
|
read_random_unlimited(void *buf, u_int nbytes)
|
|
{
|
|
return extract_entropy(&random_state, (char *)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_poll(dev_t dev, int events, struct proc *p)
|
|
{
|
|
int s;
|
|
int revents = 0;
|
|
|
|
s = splhigh();
|
|
if (events & (POLLIN | POLLRDNORM)) {
|
|
if (random_state.entropy_count >= 8)
|
|
revents |= events & (POLLIN | POLLRDNORM);
|
|
else
|
|
selrecord(p, &random_state.rsel);
|
|
}
|
|
splx(s);
|
|
if (events & (POLLOUT | POLLWRNORM))
|
|
revents |= events & (POLLOUT | POLLWRNORM); /* heh */
|
|
|
|
return (revents);
|
|
}
|
|
|