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freebsd/sys/dev/random/dummy_rng.c
Mark Murray 63edd2efc3 Fix a problem where the priority order of yarrow,dummy can get reversed
to dummy,yarrow and break the usability of /dev/random.

Fix the name of the tunable to something logical that 'sysctl kern.random'
emits.

Submitted by:	des@ (the idea, code by me)
2013-10-12 23:15:06 +00:00

125 lines
3.2 KiB
C

/*-
* Copyright (c) 2013 Arthur Mesh <arthurmesh@gmail.com>
* 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 <sys/param.h>
#include <sys/fcntl.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/random.h>
#include <sys/selinfo.h>
#include <sys/systm.h>
#include <sys/time.h>
#include <dev/random/random_adaptors.h>
#include <dev/random/randomdev.h>
static struct mtx dummy_random_mtx;
/* Used to fake out unused random calls in random_adaptor */
static void
random_null_func(void)
{
}
static int
dummy_random_poll(int events __unused, struct thread *td __unused)
{
return (0);
}
static int
dummy_random_block(int flag)
{
int error = 0;
mtx_lock(&dummy_random_mtx);
/* Blocking logic */
while (!error) {
if (flag & O_NONBLOCK)
error = EWOULDBLOCK;
else {
printf("random: dummy device blocking on read.\n");
error = msleep(&dummy_random_block,
&dummy_random_mtx,
PUSER | PCATCH, "block", 0);
}
}
mtx_unlock(&dummy_random_mtx);
return (error);
}
static void
dummy_random_init(void)
{
mtx_init(&dummy_random_mtx, "sleep mtx for dummy_random",
NULL, MTX_DEF);
}
static void
dummy_random_deinit(void)
{
mtx_destroy(&dummy_random_mtx);
}
struct random_adaptor dummy_random = {
.ident = "Dummy entropy device that always blocks",
.init = dummy_random_init,
.deinit = dummy_random_deinit,
.block = dummy_random_block,
.poll = dummy_random_poll,
.read = (random_read_func_t *)random_null_func,
.reseed = (random_reseed_func_t *)random_null_func,
.seeded = 0, /* This device can never be seeded */
.priority = 1, /* Bottom priority, so goes to last position */
};
static int
dummy_random_modevent(module_t mod __unused, int type, void *unused __unused)
{
switch (type) {
case MOD_LOAD:
random_adaptor_register("dummy", &dummy_random);
EVENTHANDLER_INVOKE(random_adaptor_attach,
&dummy_random);
return (0);
}
return (EINVAL);
}
RANDOM_ADAPTOR_MODULE(dummy, dummy_random_modevent, 1);