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|
/* $OpenBSD: rnd.c,v 1.15 1997/01/15 02:03:53 kstailey Exp $ */
/*
* random.c -- A strong random number generator
*
* Copyright (c) 1996 Michael Shalayeff.
*
* Version 1.00, last modified 26-May-96
*
* Copyright Theodore Ts'o, 1994, 1995, 1996. 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.
*/
/*
* (now, with legal B.S. out of the way.....)
*
* This routine gathers environmental noise from device drivers, etc.,
* and returns good random numbers, suitable for cryptographic use.
* Besides the obvious cryptographic uses, these numbers are also good
* for seeding TCP sequence numbers, and other places where it is
* desirable to have numbers which are not only random, but hard to
* predict by an attacker.
*
* Theory of operation
* ===================
*
* Computers are very predictable devices. Hence it is extremely hard
* to produce truly random numbers on a computer --- as opposed to
* pseudo-random numbers, which can easily generated by using a
* algorithm. Unfortunately, it is very easy for attackers to guess
* the sequence of pseudo-random number generators, and for some
* applications this is not acceptable. So instead, we must try to
* gather "environmental noise" from the computer's environment, which
* must be hard for outside attackers to observe, and use that to
* generate random numbers. In a Unix environment, this is best done
* from inside the kernel.
*
* Sources of randomness from the environment include inter-keyboard
* timings, inter-interrupt timings from some interrupts, and other
* events which are both (a) non-deterministic and (b) hard for an
* outside observer to measure. Randomness from these sources are
* added to an "entropy pool", which is mixed using a CRC-like function.
* This is not cryptographically strong, but it is adequate assuming
* the randomness is not chosen maliciously, and it is fast enough that
* the overhead of doing it on every interrupt is very reasonable.
* As random bytes are mixed into the entropy pool, the routines keep
* an *estimate* of how many bits of randomness have been stored into
* the random number generator's internal state.
*
* When random bytes are desired, they are obtained by taking the MD5
* hash of the contents of the "entropy pool". The MD5 hash avoids
* exposing the internal state of the entropy pool. It is believed to
* be computationally infeasible to derive any useful information
* about the input of MD5 from its output. Even if it is possible to
* analyze MD5 in some clever way, as long as the amount of data
* returned from the generator is less than the inherent entropy in
* the pool, the output data is totally unpredictable. For this
* reason, the routine decreases its internal estimate of how many
* bits of "true randomness" are contained in the entropy pool as it
* outputs random numbers.
*
* If this estimate goes to zero, the routine can still generate
* random numbers; however, an attacker may (at least in theory) be
* able to infer the future output of the generator from prior
* outputs. This requires successful cryptanalysis of MD5, which is
* not believed to be feasible, but there is a remote possibility.
* Nonetheless, these numbers should be useful for the vast majority
* of purposes.
*
* Exported interfaces ---- output
* ===============================
*
* There are three exported interfaces; the first is one designed to
* be used from within the kernel:
*
* void get_random_bytes(void *buf, int nbytes);
*
* This interface will return the requested number of random bytes,
* and place it in the requested buffer.
*
* The two other interfaces are two character devices /dev/random and
* /dev/urandom. /dev/random is suitable for use when very high
* quality randomness is desired (for example, for key generation or
* one-time pads), as it will only return a maximum of the number of
* bits of randomness (as estimated by the random number generator)
* contained in the entropy pool.
*
* The /dev/urandom device does not have this limit, and will return
* as many bytes as are requested. As more and more random bytes are
* requested without giving time for the entropy pool to recharge,
* this will result in random numbers that are merely cryptographically
* strong. For many applications, however, this is acceptable.
*
* Exported interfaces ---- input
* ==============================
*
* The current exported interfaces for gathering environmental noise
* from the devices are:
*
* void add_mouse_randomness(u_int32_t mouse_data);
* void add_net_randomness(int isr);
* void add_tty_randomness(int c);
* void add_disk_randomness(u_int32_t n);
*
* add_mouse_randomness() uses the mouse interrupt timing, as well as
* the reported position of the mouse from the hardware.
*
* add_net_randomness() times the finishing time of net input.
*
* add_tty_randomness() uses the inter-keypress timing, as well as the
* character as random inputs into the "entropy pool".
*
* add_disk_randomness() times the finishing time of disk requests as well
* as feeding both xfer size & time into the entropy pool.
*
* All of these routines try to estimate how many bits of randomness a
* particular randomness source. They do this by keeping track of the
* first and second order deltas of the event timings.
*
* Ensuring unpredictability at system startup
* ============================================
*
* When any operating system starts up, it will go through a sequence
* of actions that are fairly predictable by an adversary, especially
* if the start-up does not involve interaction with a human operator.
* This reduces the actual number of bits of unpredictability in the
* entropy pool below the value in entropy_count. In order to
* counteract this effect, it helps to carry information in the
* entropy pool across shut-downs and start-ups. To do this, put the
* following lines an appropriate script which is run during the boot
* sequence:
*
* echo "Initializing random number generator..."
* # Carry a random seed from start-up to start-up
* # Load and then save 512 bytes, which is the size of the entropy pool
* if [ -f /etc/random-seed ]; then
* cat /etc/random-seed >/dev/urandom
* fi
* dd if=/dev/urandom of=/etc/random-seed count=1
*
* and the following lines in an appropriate script which is run as
* the system is shutdown:
*
* # Carry a random seed from shut-down to start-up
* # Save 512 bytes, which is the size of the entropy pool
* echo "Saving random seed..."
* dd if=/dev/urandom of=/etc/random-seed count=1
*
* For example, on many Linux systems, the appropriate scripts are
* usually /etc/rc.d/rc.local and /etc/rc.d/rc.0, respectively.
*
* Effectively, these commands cause the contents of the entropy pool
* to be saved at shut-down time and reloaded into the entropy pool at
* start-up. (The 'dd' in the addition to the bootup script is to
* make sure that /etc/random-seed is different for every start-up,
* even if the system crashes without executing rc.0.) Even with
* complete knowledge of the start-up activities, predicting the state
* of the entropy pool requires knowledge of the previous history of
* the system.
*
* Configuring the /dev/random driver under Linux
* ==============================================
*
* The /dev/random driver under Linux uses minor numbers 8 and 9 of
* the /dev/mem major number (#1). So if your system does not have
* /dev/random and /dev/urandom created already, they can be created
* by using the commands:
*
* mknod /dev/random c 1 8
* mknod /dev/urandom c 1 9
*
* Acknowledgements:
* =================
*
* Ideas for constructing this random number generator were derived
* from the Pretty Good Privacy's random number generator, and from
* private discussions with Phil Karn. Colin Plumb provided a faster
* random number generator, which speed up the mixing function of the
* entropy pool, taken from PGP 3.0 (under development). It has since
* been modified by myself to provide better mixing in the case where
* the input values to add_entropy_word() are mostly small numbers.
* Dale Worley has also contributed many useful ideas and suggestions
* to improve this driver.
*
* Any flaws in the design are solely my responsibility, and should
* not be attributed to the Phil, Colin, or any of authors of PGP.
*
* The code for MD5 transform was taken from Colin Plumb's
* implementation, which has been placed in the public domain. The
* MD5 cryptographic checksum was devised by Ronald Rivest, and is
* documented in RFC 1321, "The MD5 Message Digest Algorithm".
*
* Further background information on this topic may be obtained from
* RFC 1750, "Randomness Recommendations for Security", by Donald
* Eastlake, Steve Crocker, and Jeff Schiller.
*/
#include <sys/param.h>
#include <sys/types.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/conf.h>
#include <sys/device.h>
#include <sys/disk.h>
#include <sys/ioctl.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/user.h>
#include <sys/fcntl.h>
#include <sys/vnode.h>
#include <net/netisr.h>
#include <dev/rndvar.h>
#include <dev/rndioctl.h>
#ifdef DEBUG
int rnd_debug = 0x0000;
#define RD_INPUT 0x000f /* input data */
#define RD_OUTPUT 0x00f0 /* output data */
#define RD_WAIT 0x0100 /* sleep/wakeup for good data */
#endif
#ifdef RND_USE_SHA
#define HASH_BUFFER_SIZE 5
#define HASH_TRANSFORM SHATransform
#else /* RND_USE_MD5 */
#ifndef RND_USE_MD5
#define RND_USE_MD5
#endif
#define HASH_BUFFER_SIZE 4
#define HASH_TRANSFORM MD5Transform
#endif
/*
* 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 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
/* 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;
};
/* There is one of these per entropy source */
struct timer_rand_state {
u_long last_time;
int last_delta;
int dont_count_entropy:1;
};
struct arc4_stream {
u_char i;
u_char j;
u_char s[256];
};
/* tags for different random sources */
#define ENT_NET 0x100
#define ENT_DISK 0x200
#define ENT_TTY 0x300
static struct random_bucket random_state;
struct arc4_stream arc4random_state;
static u_int32_t random_pool[POOLWORDS];
static struct timer_rand_state mouse_timer_state;
static struct timer_rand_state extract_timer_state;
static struct timer_rand_state disk_timer_state;
static struct timer_rand_state net_timer_state;
static struct timer_rand_state tty_timer_state;
static int rnd_sleep = 0;
#ifndef MIN
#define MIN(a,b) (((a) < (b)) ? (a) : (b))
#endif
static __inline void add_entropy_word __P((struct random_bucket *,
const u_int32_t));
void add_timer_randomness __P((struct random_bucket *,
struct timer_rand_state *, u_int));
static __inline int extract_entropy __P((struct random_bucket *, char *, int));
void arc4_init __P((struct arc4_stream *, u_char *, int));
static __inline u_char arc4_getbyte __P((struct arc4_stream *));
/* Arcfour random stream generator. This code is derived from section
* 17.1 of Applied Cryptography, second edition, which describes a
* stream cipher allegedly compatible with RSA Labs "RC4" cipher (the
* actual description of which is a trade secret). The same algorithm
* is used as a stream cipher called "arcfour" in Tatu Ylonen's ssh
* package.
*
* The initialization function here has been modified not to discard
* old state, and its input always includes the time of day in
* microseconds. Moreover, bytes from the stream may at any point be
* diverted to multiple processes or even kernel functions desiring
* random numbers. This increases the strenght of the random stream,
* but makes it impossible to use this code for encryption--There is
* no way ever to reproduce the same stream of random bytes.
*
* RC4 is a registered trademark of RSA Laboratories.
*/
void
arc4_init (struct arc4_stream *as, u_char *data, int len)
{
int n;
u_char si;
as->i--;
for (n = 0; n < 256; n++) {
as->i = (as->i + 1) & 0xff;
si = as->s[as->i];
as->j = (as->j + si + data[n % len]) & 0xff;
as->s[as->i] = as->s[as->j];
as->s[as->j] = si;
}
}
static __inline u_char
arc4_getbyte (struct arc4_stream *as)
{
u_char si, sj;
as->i = (as->i + 1) & 0xff;
si = as->s[as->i];
as->j = (as->j + si) & 0xff;
sj = as->s[as->j];
as->s[as->i] = sj;
as->s[as->j] = si;
return (as->s[(si + sj) & 0xff]);
}
u_int32_t
arc4random (void)
{
return ((arc4_getbyte (&arc4random_state) << 24)
| (arc4_getbyte (&arc4random_state) << 16)
| (arc4_getbyte (&arc4random_state) << 8)
| arc4_getbyte (&arc4random_state));
}
void
randomattach(void)
{
int i;
struct timeval tv;
random_state.add_ptr = 0;
random_state.entropy_count = 0;
random_state.pool = random_pool;
extract_timer_state.dont_count_entropy = 1;
for (i = 0; i < 256; i++)
arc4random_state.s[i] = i;
microtime (&tv);
arc4_init (&arc4random_state, (u_char *) &tv, sizeof (tv));
}
int
randomopen(dev, flag, mode, p)
dev_t dev;
int flag;
int mode;
struct proc *p;
{
return (minor (dev) < RND_NODEV) ? 0 : ENXIO;
}
int
randomclose(dev, flag, mode, p)
dev_t dev;
int flag;
int mode;
struct proc *p;
{
return 0;
}
/*
* This function adds a byte 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 jiffies 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(r, input)
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 many 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.
*
*/
void
add_timer_randomness(r, state, num)
struct random_bucket *r;
struct timer_rand_state *state;
u_int num;
{
int delta, delta2;
u_int nbits;
u_long time;
struct timeval tv;
microtime(&tv);
time = tv.tv_usec ^ tv.tv_sec;
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.
*/
if (!state->dont_count_entropy) {
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 && rnd_sleep != 0) {
rnd_sleep--;
#ifdef DEBUG
if (rnd_debug & RD_WAIT)
printf("rnd: wakeup[%d]{%u}\n",
rnd_sleep, r->entropy_count);
#endif
wakeup(&rnd_sleep);
}
}
void
add_mouse_randomness(mouse_data)
u_int32_t mouse_data;
{
add_timer_randomness(&random_state, &mouse_timer_state, mouse_data);
}
void
add_net_randomness(isr)
int isr;
{
add_timer_randomness(&random_state, &net_timer_state, ENT_NET + isr);
}
void
add_disk_randomness(n)
u_int32_t n;
{
u_int8_t c;
/* Has randomattach run yet? */
if (random_state.pool == NULL)
return;
c = n & 0xff;
n >>= 8;
c ^= n & 0xff;
n >>= 8;
c ^= n & 0xff;
n >>= 8;
c ^= n & 0xff;
add_timer_randomness(&random_state, &disk_timer_state, ENT_DISK + c);
}
void
add_tty_randomness(c)
int c;
{
/* Has randomattach run yet? */
if (random_state.pool == NULL)
return;
add_timer_randomness(&random_state, &tty_timer_state, ENT_TTY + c);
}
#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(r, buf, nbytes)
struct random_bucket *r;
char *buf;
int nbytes;
{
int ret, i;
u_int32_t tmp[HASH_BUFFER_SIZE];
add_timer_randomness(r, &extract_timer_state, nbytes);
/* Redundant, but just in case... */
if (r->entropy_count > POOLBITS)
r->entropy_count = POOLBITS;
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 */
#ifdef RND_USE_MD5
MD5Init(tmp);
#endif
for (i = 0; i < POOLWORDS; i += 16)
HASH_TRANSFORM(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]);
#ifdef RND_USE_SHA
add_entropy_word(r, tmp[5]);
#endif
/*
* Run the MD5 Transform one more time, since we want
* to add at least minimal obscuring of the inputs to
* add_entropy_word(). --- TYT
*/
HASH_TRANSFORM(tmp, r->pool);
/*
* In case the hash function has some recognizable
* output pattern, we fold it in half.
*/
{
register u_int8_t *cp, *dp;
cp = (u_int8_t *) tmp;
dp = cp + (HASH_BUFFER_SIZE*sizeof(tmp[0])) - 1;
for (i=0; i < HASH_BUFFER_SIZE*sizeof(tmp[0])/2; i++) {
*cp ^= *dp;
cp++; dp--;
}
}
/* Copy data to destination buffer */
i = MIN(nbytes, HASH_BUFFER_SIZE*sizeof(tmp[0]));
bcopy((caddr_t)tmp, buf, i);
nbytes -= i;
buf += i;
add_timer_randomness(r, &extract_timer_state, nbytes);
}
/* Wipe data from memory */
bzero(tmp, sizeof(tmp));
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(buf, nbytes)
void *buf;
size_t nbytes;
{
extract_entropy(&random_state, (char *) buf, nbytes);
}
int
randomread(dev, uio, ioflag)
dev_t dev;
struct uio *uio;
int ioflag;
{
int ret = 0;
int s, i;
if (uio->uio_resid == 0)
return 0;
while (!ret && uio->uio_resid > 0) {
u_int32_t buf[ POOLWORDS ];
int n = min(sizeof(buf), uio->uio_resid);
s = splhigh();
switch(minor(dev)) {
case RND_RND:
ret = EIO; /* no chip -- error */
break;
case RND_SRND:
if (random_state.entropy_count < 8) {
if (ioflag & IO_NDELAY) {
ret = EWOULDBLOCK;
break;
}
#ifdef DEBUG
if (rnd_debug & RD_WAIT)
printf("rnd: sleep[%d]\n",
rnd_sleep);
#endif
rnd_sleep++;
ret = tsleep(&rnd_sleep, PWAIT | PCATCH,
"rndrd", 0);
#ifdef DEBUG
if (rnd_debug & RD_WAIT)
printf("rnd: awakened(%d)\n", ret);
#endif
if (ret)
break;
}
n = min(n, random_state.entropy_count / 8);
#ifdef DEBUG
if (rnd_debug & RD_OUTPUT)
printf("rnd: %u possible output\n", n);
#endif
case RND_URND:
n = extract_entropy(&random_state, (char *)buf, n);
#ifdef DEBUG
if (rnd_debug & RD_OUTPUT)
printf("rnd: %u bytes for output\n", n);
#endif
break;
case RND_PRND:
i = (n + 3) / 4;
while (i--)
buf[i] = random();
break;
case RND_ARND:
{
u_char *cp = (u_char *) buf;
u_char *end = cp + n;
while (cp < end)
*cp++ = arc4_getbyte (&arc4random_state);
break;
}
}
splx(s);
if (n != 0 && ret == 0)
ret = uiomove((caddr_t)buf, n, uio);
}
return ret;
}
int
randomselect(dev, rw, p)
dev_t dev;
int rw;
struct proc *p;
{
switch (rw) {
case FREAD:
return random_state.entropy_count > 0;
case FWRITE:
return 1;
}
return 0;
}
static __inline void
arc4_stir (struct arc4_stream *as)
{
int rsec = random_state.entropy_count >> 3;
u_int buf[2 + POOLWORDS];
int n = min (sizeof(buf) - 2 * sizeof (u_int), rsec);
microtime ((struct timeval *) buf);
get_random_bytes (buf + 2, n);
arc4_init (&arc4random_state, (u_char *) buf,
2 * sizeof (u_int) + n);
}
int
randomwrite(dev, uio, flags)
dev_t dev;
struct uio *uio;
int flags;
{
int ret = 0;
if (minor(dev) == RND_RND || minor(dev) == RND_PRND)
return ENXIO;
if (uio->uio_resid == 0)
return 0;
while (!ret && uio->uio_resid > 0) {
u_int32_t buf[ POOLWORDS ];
u_short n = min(sizeof(buf),uio->uio_resid);
ret = uiomove((caddr_t)buf, n, uio);
if (!ret) {
int i;
while (n % sizeof(u_int32_t))
((u_char *) buf)[n++] = 0;
n >>= 2;
for (i = 0; i < n; i++)
add_entropy_word(&random_state, buf[i]);
}
}
if (minor(dev) == RND_ARND && !ret)
arc4_stir (&arc4random_state);
return ret;
}
int
randomioctl(dev, cmd, data, flag, p)
dev_t dev;
u_long cmd;
caddr_t data;
int flag;
struct proc *p;
{
int ret = 0;
u_int cnt;
switch (cmd) {
case RNDGETENTCNT:
ret = copyout(&random_state.entropy_count, data,
sizeof(random_state.entropy_count));
break;
case RNDADDTOENTCNT:
if (suser(p->p_ucred, &p->p_acflag) != 0)
return EPERM;
copyin(&cnt, data, sizeof(cnt));
random_state.entropy_count += cnt;
if (random_state.entropy_count > POOLBITS)
random_state.entropy_count = POOLBITS;
break;
case RNDZAPENTCNT:
if (suser(p->p_ucred, &p->p_acflag) != 0)
return EPERM;
random_state.entropy_count = 0;
ret = 0;
break;
case RNDSTIRARC4:
if (suser(p->p_ucred, &p->p_acflag) != 0)
return EPERM;
if (random_state.entropy_count < 64)
return EAGAIN;
arc4_stir (&arc4random_state);
ret = 0;
break;
default:
ret = EINVAL;
}
return ret;
}
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