Theodore Ts'po's random number gernerator for Linux, ported by me.

This code will only be included in your kernel if you have
'options DEVRANDOM', but that will fall away in a couple of days.
Obtained from: Theodore Ts'o, Linux

1 files changed, 452 insertions, 0 deletions

diff --git a/sys/i386/isa/random.c b/sys/i386/isa/random.c
new file mode 100644
index 000000000000..af67c56bc803
--- /dev/null
+++ b/sys/i386/isa/random.c
@@ -0,0 +1,452 @@
+/*
+ * random.c -- A strong random number generator
+ *
+ * $Id$
+ *
+ * Version 0.92, last modified 21-Sep-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.
+ *
+ */
+
+#ifdef DEVRANDOM
+
+#include <sys/param.h>
+#include <sys/cdefs.h>
+#include <sys/kernel.h>
+#include <sys/uio.h>
+#include <sys/systm.h>
+#include <i386/isa/isa.h>
+#include <i386/isa/icu.h>
+#include <i386/isa/timerreg.h>
+#include <i386/isa/isa_device.h>
+#include <machine/random.h>
+
+#define RANDPOOL 512
+
+struct random_bucket {
+	int add_ptr;
+	int entropy_count;
+	int length;
+	int bit_length;
+	int delay_mix:1;
+	u_int8_t *pool;
+};
+
+struct timer_rand_state {
+	u_int32_t	last_time;
+	int 		last_delta;
+	int 		nbits;
+};
+
+static struct random_bucket random_state;
+static u_int32_t rand_pool_key[16];
+static u_int8_t random_pool[RANDPOOL];
+static u_int32_t random_counter[16];
+static struct timer_rand_state keyboard_timer_state;
+static struct timer_rand_state irq_timer_state[ICU_LEN];
+
+inthand2_t add_interrupt_randomness;
+u_int16_t interrupt_allowed = 0;
+	
+#ifndef MIN
+#define MIN(a,b) (((a) < (b)) ? (a) : (b))
+#endif
+	
+static void
+flush_random(struct random_bucket *random_state)
+{
+	random_state->add_ptr = 0;
+	random_state->bit_length = random_state->length * 8;
+	random_state->entropy_count = 0;
+	random_state->delay_mix = 0;
+}
+
+void
+rand_initialize(void)
+{
+	int irq;
+	long interrupts;
+
+	random_state.length = RANDPOOL;
+	random_state.pool = random_pool;
+	flush_random(&random_state);
+
+#if 0
+	/* XXX Dreadful hack - should be replaced by something more elegant */
+	interrupts = RANDOM_INTERRUPTS;
+
+	for (irq = 0; irq < ICU_LEN; irq++) {
+		interrupt_allowed[irq] = interrupts & 0x0001;
+		interrupts >>= 1;
+		printf("Randomising irq %d %s\n", irq, interrupt_allowed[irq] ?
+			"on" : "off");
+	}
+#endif
+}
+
+/*
+ * MD5 transform algorithm, taken from code written by Colin Plumb,
+ * and put into the public domain
+ */
+
+/* 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
+
+static void
+mix_bucket(struct random_bucket *v)
+{
+	struct random_bucket *r = v;
+	int	i, num_passes;
+	u_int32_t *p;
+	u_int32_t iv[4];
+
+	r->delay_mix = 0;
+	
+	/* Start IV from last block of the random pool */
+	memcpy(iv, r->pool + r->length - sizeof(iv), sizeof(iv));
+
+	num_passes = r->length / 16;
+	for (i = 0, p = (u_int32_t *) r->pool; i < num_passes; i++) {
+		MD5Transform(iv, rand_pool_key);
+		iv[0] = (*p++ ^= iv[0]);
+		iv[1] = (*p++ ^= iv[1]);
+		iv[2] = (*p++ ^= iv[2]);
+		iv[3] = (*p++ ^= iv[3]);
+	}
+	memcpy(rand_pool_key, r->pool, sizeof(rand_pool_key));
+	
+	/* Wipe iv from memory */
+	bzero(iv, sizeof(iv));
+
+	r->add_ptr = 0;
+}
+
+/*
+ * This function adds a byte into the entropy "pool".  It does not
+ * update the entropy estimate.  The caller must do this if appropriate.
+ */
+static inline void
+add_entropy_byte(struct random_bucket *r, const u_int8_t ch, int delay)
+{
+	if (!delay && r->delay_mix)
+		mix_bucket(r);
+	r->pool[r->add_ptr++] ^= ch;
+	if (r->add_ptr >= r->length) {
+		if (delay) {
+			r->delay_mix = 1;
+			r->add_ptr = 0;
+		} else
+			mix_bucket(r);
+	}
+}
+
+/*
+ * This function adds some number of bytes into the entropy pool and
+ * updates the entropy count as appropriate.
+ */
+static void
+add_entropy(struct random_bucket *r, const u_int8_t *ptr, int length,
+	int entropy_level, int delay)
+{
+	while (length-- > 0)
+		add_entropy_byte(r, *ptr++, delay);
+		
+	r->entropy_count += entropy_level;
+	if (r->entropy_count > r->length*8)
+		r->entropy_count = r->length * 8;
+}
+
+/*
+ * 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 many bits of entropy this call has added to the pool.
+ */
+static void
+add_timer_randomness(struct random_bucket *r, struct timer_rand_state *state,
+	int delay)
+{
+	int	delta, delta2;
+	int	nbits;
+
+	/*
+	 * Calculate number of bits of randomness we probably
+	 * added.  We take into account the first and second order
+	 * delta's in order to make our estimate.
+	 */
+	delta = ticks - state->last_time;
+	delta2 = delta - state->last_delta;
+	state->last_time = ticks;
+	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;
+	
+	add_entropy(r, (u_int8_t *) &ticks, sizeof(ticks), nbits, delay);
+
+#if defined (__i386__)
+	/*
+	 * On a 386, read the high resolution timer.  We assume that
+	 * this gives us 2 bits of randomness.  XXX This needs
+	 * investigation.
+	 */ 
+	outb(TIMER_LATCH|TIMER_SEL0, TIMER_MODE); /* latch the count ASAP */
+	add_entropy_byte(r, inb(TIMER_CNTR0), 1);
+	add_entropy_byte(r, inb(TIMER_CNTR0), 1);
+	r->entropy_count += 2;
+	if (r->entropy_count > r->bit_length)
+		r->entropy_count = r->bit_length;
+#endif
+}
+
+void
+add_keyboard_randomness(u_char scancode)
+{
+	struct random_bucket *r = &random_state;
+
+	add_timer_randomness(r, &keyboard_timer_state, 0);
+	add_entropy_byte(r, scancode, 0);
+	r->entropy_count += 6;
+	if (r->entropy_count > r->bit_length)
+		r->entropy_count = r->bit_length;
+}
+
+void
+add_interrupt_randomness(int irq)
+{
+	static struct random_bucket *r = &random_state;
+	u_int16_t intbit = 1 << irq;
+
+/*	printf("Trapping interrupt %d\n", irq); */
+
+	if (interrupt_allowed & intbit) 
+		add_timer_randomness(r, &irq_timer_state[irq], 1);
+}
+
+/*
+ * 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 u_int
+extract_entropy(struct random_bucket *r, char *buf, u_int nbytes)
+{
+	int passes, i;
+	u_int length, ret;
+	u_int32_t tmp[4];
+	u_int8_t *cp;
+	
+	add_entropy(r, (u_int8_t *) &ticks, sizeof(ticks), 0, 0);
+	
+	if (r->entropy_count > r->bit_length) 
+		r->entropy_count = r->bit_length;
+	if (nbytes > 32768)
+		nbytes = 32768;
+	ret = nbytes;
+	r->entropy_count -= ret * 8;
+	if (r->entropy_count < 0)
+		r->entropy_count = 0;
+	passes = r->length / 64;
+	while (nbytes) {
+		length = MIN(nbytes, 16);
+		for (i=0; i < 16; i++) {
+			if (++random_counter[i] != 0)
+				break;
+		}
+		tmp[0] = 0x67452301;
+		tmp[1] = 0xefcdab89;
+		tmp[2] = 0x98badcfe;
+		tmp[3] = 0x10325476;
+		MD5Transform(tmp, random_counter);
+		for (i = 0, cp = r->pool; i < passes; i++, cp+=64)
+			MD5Transform(tmp, (u_int32_t *) cp);
+		memcpy(buf, tmp, length);
+		nbytes -= length;
+		buf += length;
+	}
+	return ret;
+}
+
+/*
+ * 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);
+}
+
+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 linux
+int
+read_random(struct inode * inode,struct file * file,char * buf,int nbytes)
+{
+	if ((nbytes * 8) > random_state.entropy_count)
+		nbytes = random_state.entropy_count / 8;
+	
+	return extract_entropy(&random_state, buf, nbytes, 1);
+}
+
+int
+read_random_unlimited(struct inode * inode,struct file * file,
+			  char * buf,int nbytes)
+{
+	return extract_entropy(&random_state, buf, nbytes, 1);
+}
+#endif
+
+#endif /* DEVRANDOM */