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a6278a2a42
now in dirs called sys/*/random/ instead of sys/*/randomdev/*. Introduce blocking, but only at startup; the random device will block until the first reseed happens to prevent clients from using untrustworthy output. Provide a read_random() call for the rest of the kernel so that the entropy device does not need to be present. This means that things like IPX no longer need to have "device random" hardcoded into thir kernel config. The downside is that read_random() will provide very poor output until the entropy device is loaded and reseeded. It is recommended that developers do NOT use the read_random() call; instead, they should use arc4random() which internally uses read_random(). Clean up the mutex and locking code a bit; this makes it possible to unload the module again.
135 lines
4.0 KiB
C
135 lines
4.0 KiB
C
/*-
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* Copyright (c) 2000 Mark R V Murray
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer
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* in this position and unchanged.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/types.h>
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#include <sys/queue.h>
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#include <sys/kthread.h>
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#include <sys/poll.h>
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#include <sys/select.h>
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#include <sys/random.h>
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#include <sys/time.h>
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#include <machine/mutex.h>
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#include <crypto/blowfish/blowfish.h>
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#include <dev/random/hash.h>
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#include <dev/random/yarrow.h>
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static u_int read_random_phony(void *, u_int);
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/* hold the address of the routine which is actually called if
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* the ramdomdev is loaded
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*/
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static void (*reap_func)(struct timespec *, void *, u_int, u_int, u_int, u_int) = NULL;
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static u_int (*read_func)(void *, u_int) = read_random_phony;
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/* Initialise the harvester at load time */
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void
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random_init_harvester(void (*reaper)(struct timespec *, void *, u_int, u_int, u_int, u_int), u_int (*reader)(void *, u_int))
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{
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reap_func = reaper;
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read_func = reader;
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}
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/* Deinitialise the harvester at unload time */
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void
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random_deinit_harvester(void)
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{
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reap_func = NULL;
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read_func = read_random_phony;
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}
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/* Entropy harvesting routine. This is supposed to be fast; do
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* not do anything slow in here!
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* Implemented as in indirect call to allow non-inclusion of
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* the entropy device.
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*/
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void
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random_harvest(void *entropy, u_int count, u_int bits, u_int frac, u_int origin)
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{
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struct timespec timebuf;
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if (reap_func) {
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nanotime(&timebuf);
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(*reap_func)(&timebuf, entropy, count, bits, frac, origin);
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}
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}
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/* Userland-visible version of read_random */
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u_int
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read_random(void *buf, u_int count)
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{
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return (*read_func)(buf, count);
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}
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/* If the entropy device is not loaded, make a token effort to
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* provide _some_ kind of randomness. This should only be used
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* inside other RNG's, like arc4random(9).
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*/
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static u_int
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read_random_phony(void *buf, u_int count)
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{
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struct timespec timebuf;
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u_long randval;
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int size, i;
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static int initialised = 0;
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/* Try to give random(9) a half decent initialisation
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* DO not make the mistake of thinking this is secure!!
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*/
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if (!initialised) {
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nanotime(&timebuf);
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srandom((u_long)(timebuf.tv_sec ^ timebuf.tv_nsec));
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}
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/* Fill buf[] with random(9) output */
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for (i = 0; i < count; i+= sizeof(u_long)) {
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randval = random();
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size = (count - i) < sizeof(u_long) ? (count - i) : sizeof(u_long);
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memcpy(&((char *)buf)[i], &randval, size);
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}
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return count;
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}
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/* Helper routine to enable kthread_exit() to work while the module is
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* being (or has been) unloaded.
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* This routine is in this file because it is always linked into the kernel,
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* and will thus never be unloaded. This is critical for unloadable modules
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* that have threads.
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*/
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void
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random_set_wakeup_exit(void *control)
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{
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wakeup(control);
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mtx_enter(&Giant, MTX_DEF);
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kthread_exit(0);
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/* NOTREACHED */
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}
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