freebsd-dev/sys/dev/random/dummy_rng.c
John-Mark Gurney 601e8bcdf4 When the new random adaptor code was brought it in r273872, a call to
randomdev_init_reader to change read_random over to the newly installed
adaptor was missed.  This means both read_random and arc4random (seeded
from read_random) were not returning very random data.  This also
effects userland arc4random as it is seeded from kernel arc4random.

The random devices are uneffected and have returned good randomness
since the change.

All keys generated with a kernel of r273872 must be regenerated with
a kernel with this patch.  Keys generated may be predictable.

Remove the warning as log is too early to print anything, and it would
always get printed due to early use of arc4random...

Reviewed by:	delphij, markm
Approved by:    so (delphij)
2015-02-17 17:37:00 +00:00

112 lines
3.3 KiB
C

/*-
* Copyright (c) 2013 Arthur Mesh <arthurmesh@gmail.com>
* Copyright (c) 2013 Mark R V Murray
* 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, this list of conditions and the following disclaimer
* in this position and unchanged.
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_random.h"
#include <sys/param.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/random.h>
#include <sys/syslog.h>
#include <sys/systm.h>
#include <dev/random/randomdev.h>
#include <dev/random/random_adaptors.h>
static int
dummy_random_zero(void)
{
return (0);
}
static void
dummy_random(void)
{
}
/* ARGSUSED */
static void
dummy_random_init(void)
{
#ifdef RANDOM_DEBUG
printf("random: %s\n", __func__);
#endif
randomdev_init_reader(dummy_random_read_phony);
}
/* This is used only by the internal read_random(9) call, and then only
* if no entropy processor is loaded.
*
* Make a token effort to provide _some_ kind of output. No warranty of
* the quality of this output is made, mainly because its lousy.
*
* This is only used by the internal read_random(9) call when no other
* adaptor is active.
*
* It has external scope due to the way things work in
* randomdev_[de]init_reader() that the rest of the world doesn't need to
* know about.
*
* Caveat Emptor.
*/
void
dummy_random_read_phony(uint8_t *buf, u_int count)
{
/* If no entropy device is loaded, don't spam the console with warnings */
u_long randval;
size_t size, i;
/* srandom() is called in kern/init_main.c:proc0_post() */
/* Fill buf[] with random(9) output */
for (i = 0; i < count; i += sizeof(randval)) {
randval = random();
size = MIN(count - i, sizeof(randval));
memcpy(buf + i, &randval, (size_t)size);
}
}
struct random_adaptor randomdev_dummy = {
.ra_ident = "Dummy",
.ra_priority = 1, /* Bottom priority, so goes to last position */
.ra_reseed = dummy_random,
.ra_seeded = (random_adaptor_seeded_func_t *)dummy_random_zero,
.ra_read = (random_adaptor_read_func_t *)dummy_random_zero,
.ra_write = (random_adaptor_write_func_t *)dummy_random_zero,
.ra_init = dummy_random_init,
.ra_deinit = dummy_random,
};