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-rw-r--r--sys/kern/kern_random.c515
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diff --git a/sys/kern/kern_random.c b/sys/kern/kern_random.c
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+/*
+ * random_machdep.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 "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;
+}
+
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