10cb24248a
This code has had an extensive rewrite and a good series of reviews, both by the author and other parties. This means a lot of code has been simplified. Pluggable structures for high-rate entropy generators are available, and it is most definitely not the case that /dev/random can be driven by only a hardware souce any more. This has been designed out of the device. Hardware sources are stirred into the CSPRNG (Yarrow, Fortuna) like any other entropy source. Pluggable modules may be written by third parties for additional sources. The harvesting structures and consequently the locking have been simplified. Entropy harvesting is done in a more general way (the documentation for this will follow). There is some GREAT entropy to be had in the UMA allocator, but it is disabled for now as messing with that is likely to annoy many people. The venerable (but effective) Yarrow algorithm, which is no longer supported by its authors now has an alternative, Fortuna. For now, Yarrow is retained as the default algorithm, but this may be changed using a kernel option. It is intended to make Fortuna the default algorithm for 11.0. Interested parties are encouraged to read ISBN 978-0-470-47424-2 "Cryptography Engineering" By Ferguson, Schneier and Kohno for Fortuna's gory details. Heck, read it anyway. Many thanks to Arthur Mesh who did early grunt work, and who got caught in the crossfire rather more than he deserved to. My thanks also to folks who helped me thresh this out on whiteboards and in the odd "Hallway track", or otherwise. My Nomex pants are on. Let the feedback commence! Reviewed by: trasz,des(partial),imp(partial?),rwatson(partial?) Approved by: so(des)
253 lines
6.4 KiB
C
253 lines
6.4 KiB
C
/*-
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* Copyright (c) 2000-2013 Mark R V Murray
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* Copyright (c) 2013 Arthur Mesh <arthurmesh@gmail.com>
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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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*/
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/*
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* NOTE NOTE NOTE
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*
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* This file is compiled into the kernel unconditionally. Any random(4)
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* infrastructure that needs to be in the kernel by default goes here!
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*
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* Except ...
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*
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* The adaptor code all goes into random_adaptor.c, which is also compiled
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* the kernel by default. The module in that file is initialised before
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* this one.
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*
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* Other modules must be initialised after the above two, and are
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* software random processors which plug into random_adaptor.c.
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*
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_random.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/bus.h>
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#include <sys/conf.h>
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#include <sys/fcntl.h>
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#include <sys/filio.h>
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#include <sys/kernel.h>
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#include <sys/kthread.h>
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#include <sys/lock.h>
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#include <sys/module.h>
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#include <sys/malloc.h>
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#include <sys/proc.h>
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#include <sys/random.h>
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#include <sys/sysctl.h>
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#include <sys/systm.h>
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#include <sys/uio.h>
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#include <sys/unistd.h>
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#include <dev/random/randomdev.h>
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#include <dev/random/random_adaptors.h>
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#include <dev/random/random_harvestq.h>
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#define RANDOM_MINOR 0
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static d_ioctl_t randomdev_ioctl;
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static struct cdevsw random_cdevsw = {
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.d_name = "random",
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.d_version = D_VERSION,
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.d_read = random_adaptor_read,
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.d_write = random_adaptor_write,
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.d_poll = random_adaptor_poll,
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.d_ioctl = randomdev_ioctl,
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};
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/* For use with make_dev(9)/destroy_dev(9). */
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static struct cdev *random_dev;
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/* Set up the sysctl root node for the entropy device */
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SYSCTL_NODE(_kern, OID_AUTO, random, CTLFLAG_RW, 0, "Random Number Generator");
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MALLOC_DEFINE(M_ENTROPY, "entropy", "Entropy harvesting buffers and data structures");
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/* ARGSUSED */
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static int
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randomdev_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t addr __unused,
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int flags __unused, struct thread *td __unused)
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{
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int error = 0;
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switch (cmd) {
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/* Really handled in upper layer */
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case FIOASYNC:
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case FIONBIO:
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break;
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default:
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error = ENOTTY;
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}
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return (error);
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}
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/* Helper routine to enable kproc_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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randomdev_set_wakeup_exit(void *control)
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{
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wakeup(control);
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kproc_exit(0);
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/* NOTREACHED */
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}
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/* ARGSUSED */
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static int
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randomdev_modevent(module_t mod __unused, int type, void *data __unused)
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{
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int error = 0;
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switch (type) {
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case MOD_LOAD:
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printf("random: entropy device infrastructure driver\n");
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random_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &random_cdevsw,
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RANDOM_MINOR, NULL, UID_ROOT, GID_WHEEL, 0644, "random");
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make_dev_alias(random_dev, "urandom"); /* compatibility */
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random_adaptors_init();
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break;
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case MOD_UNLOAD:
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random_adaptors_deinit();
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destroy_dev(random_dev);
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break;
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case MOD_SHUTDOWN:
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break;
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default:
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error = EOPNOTSUPP;
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break;
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}
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return (error);
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}
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#define EARLY_2_DEV_MODULE(name, evh, arg) \
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static moduledata_t name##_mod = { \
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#name, \
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evh, \
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arg \
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}; \
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DECLARE_MODULE(name, name##_mod, SI_SUB_DRIVERS, SI_ORDER_SECOND)
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EARLY_2_DEV_MODULE(randomdev, randomdev_modevent, NULL);
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MODULE_VERSION(randomdev, 1);
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/* ================
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* Harvesting stubs
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* ================
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*/
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/* Internal stub/fake routine for when no entropy processor is loaded.
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* If the entropy device is not loaded, don't act on harvesting calls
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* and just return.
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*/
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/* ARGSUSED */
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static void
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random_harvest_phony(const void *entropy __unused, u_int count __unused,
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u_int bits __unused, enum random_entropy_source origin __unused)
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{
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}
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/* Hold the address of the routine which is actually called */
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static void (*reap_func)(const void *, u_int, u_int, enum random_entropy_source) = random_harvest_phony;
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/* Initialise the harvester when/if it is loaded */
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void
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randomdev_init_harvester(void (*reaper)(const void *, u_int, u_int, enum random_entropy_source))
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{
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reap_func = reaper;
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}
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/* Deinitialise the harvester when/if it is unloaded */
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void
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randomdev_deinit_harvester(void)
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{
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reap_func = random_harvest_phony;
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}
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/* Entropy harvesting routine.
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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(const void *entropy, u_int count, u_int bits, enum random_entropy_source origin)
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{
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(*reap_func)(entropy, count, bits, origin);
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}
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/* ================================
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* Internal reading stubs and fakes
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* ================================
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*/
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/* Hold the address of the routine which is actually called */
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static u_int (*read_func)(uint8_t *, u_int) = dummy_random_read_phony;
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/* Initialise the reader when/if it is loaded */
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void
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randomdev_init_reader(u_int (*reader)(uint8_t *, u_int))
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{
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read_func = reader;
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}
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/* Deinitialise the reader when/if it is unloaded */
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void
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randomdev_deinit_reader(void)
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{
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read_func = dummy_random_read_phony;
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}
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/* Kernel API version of read_random().
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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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int
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read_random(void *buf, int count)
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{
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return ((int)(*read_func)(buf, (u_int)count));
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}
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