38c9c1708b
full, avoiding the cost of mutex operations if it is. We re-test once the mutex is acquired to make sure it's still true before doing the -modify-write part of the read-modify-write. Note that due to the maximum fifo depth being pretty deep, this is unlikely to improve harvesting performance yet. Approved by: markm
374 lines
9.8 KiB
C
374 lines
9.8 KiB
C
/*-
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* Copyright (c) 2000-2004 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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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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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/kernel.h>
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#include <sys/kthread.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mutex.h>
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#include <sys/poll.h>
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#include <sys/proc.h>
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#include <sys/random.h>
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#include <sys/selinfo.h>
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#include <sys/sysctl.h>
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#include <sys/uio.h>
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#include <sys/unistd.h>
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#include <sys/vnode.h>
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#include <machine/bus.h>
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#include <machine/cpu.h>
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#include <dev/random/randomdev.h>
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#include <dev/random/randomdev_soft.h>
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#define RANDOM_FIFO_MAX 256 /* How many events to queue up */
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static void random_kthread(void *);
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static void
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random_harvest_internal(u_int64_t, const void *, u_int,
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u_int, u_int, enum esource);
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struct random_systat random_yarrow = {
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.ident = "Software, Yarrow",
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.init = random_yarrow_init,
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.deinit = random_yarrow_deinit,
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.read = random_yarrow_read,
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.write = random_yarrow_write,
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.reseed = random_yarrow_reseed,
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.seeded = 1,
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};
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MALLOC_DEFINE(M_ENTROPY, "entropy", "Entropy harvesting buffers");
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/* Lockable FIFO queue holding entropy buffers */
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struct entropyfifo {
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struct mtx lock;
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int count;
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STAILQ_HEAD(harvestlist, harvest) head;
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};
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/* Empty entropy buffers */
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static struct entropyfifo emptyfifo;
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#define EMPTYBUFFERS 1024
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/* Harvested entropy */
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static struct entropyfifo harvestfifo[ENTROPYSOURCE];
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/* <0 to end the kthread, 0 to let it run */
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static int random_kthread_control = 0;
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static struct proc *random_kthread_proc;
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/* List for the dynamic sysctls */
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struct sysctl_ctx_list random_clist;
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/* ARGSUSED */
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static int
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random_check_boolean(SYSCTL_HANDLER_ARGS)
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{
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if (oidp->oid_arg1 != NULL && *(u_int *)(oidp->oid_arg1) != 0)
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*(u_int *)(oidp->oid_arg1) = 1;
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return sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
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}
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/* ARGSUSED */
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void
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random_yarrow_init(void)
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{
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int error, i;
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struct harvest *np;
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struct sysctl_oid *o, *random_o, *random_sys_o, *random_sys_harvest_o;
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enum esource e;
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o = SYSCTL_ADD_NODE(&random_clist,
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SYSCTL_STATIC_CHILDREN(_kern),
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OID_AUTO, "random", CTLFLAG_RW, 0,
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"Software Random Number Generator");
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random_o = o;
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random_yarrow_init_alg(&random_clist, random_o);
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o = SYSCTL_ADD_NODE(&random_clist,
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SYSCTL_CHILDREN(random_o),
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OID_AUTO, "sys", CTLFLAG_RW, 0,
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"Entropy Device Parameters");
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random_sys_o = o;
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o = SYSCTL_ADD_PROC(&random_clist,
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SYSCTL_CHILDREN(random_sys_o),
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OID_AUTO, "seeded", CTLTYPE_INT | CTLFLAG_RW,
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&random_systat.seeded, 1, random_check_boolean, "I",
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"Seeded State");
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o = SYSCTL_ADD_NODE(&random_clist,
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SYSCTL_CHILDREN(random_sys_o),
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OID_AUTO, "harvest", CTLFLAG_RW, 0,
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"Entropy Sources");
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random_sys_harvest_o = o;
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o = SYSCTL_ADD_PROC(&random_clist,
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SYSCTL_CHILDREN(random_sys_harvest_o),
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OID_AUTO, "ethernet", CTLTYPE_INT | CTLFLAG_RW,
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&harvest.ethernet, 1, random_check_boolean, "I",
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"Harvest NIC entropy");
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o = SYSCTL_ADD_PROC(&random_clist,
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SYSCTL_CHILDREN(random_sys_harvest_o),
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OID_AUTO, "point_to_point", CTLTYPE_INT | CTLFLAG_RW,
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&harvest.point_to_point, 1, random_check_boolean, "I",
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"Harvest serial net entropy");
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o = SYSCTL_ADD_PROC(&random_clist,
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SYSCTL_CHILDREN(random_sys_harvest_o),
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OID_AUTO, "interrupt", CTLTYPE_INT | CTLFLAG_RW,
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&harvest.interrupt, 1, random_check_boolean, "I",
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"Harvest IRQ entropy");
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o = SYSCTL_ADD_PROC(&random_clist,
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SYSCTL_CHILDREN(random_sys_harvest_o),
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OID_AUTO, "swi", CTLTYPE_INT | CTLFLAG_RW,
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&harvest.swi, 0, random_check_boolean, "I",
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"Harvest SWI entropy");
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/* Initialise the harvest fifos */
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STAILQ_INIT(&emptyfifo.head);
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emptyfifo.count = 0;
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mtx_init(&emptyfifo.lock, "entropy harvest buffers", NULL, MTX_SPIN);
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for (i = 0; i < EMPTYBUFFERS; i++) {
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np = malloc(sizeof(struct harvest), M_ENTROPY, M_WAITOK);
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STAILQ_INSERT_TAIL(&emptyfifo.head, np, next);
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}
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for (e = RANDOM_START; e < ENTROPYSOURCE; e++) {
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STAILQ_INIT(&harvestfifo[e].head);
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harvestfifo[e].count = 0;
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mtx_init(&harvestfifo[e].lock, "entropy harvest", NULL,
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MTX_SPIN);
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}
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/* Start the hash/reseed thread */
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error = kthread_create(random_kthread, NULL,
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&random_kthread_proc, RFHIGHPID, 0, "yarrow");
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if (error != 0)
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panic("Cannot create entropy maintenance thread.");
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/* Register the randomness harvesting routine */
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random_yarrow_init_harvester(random_harvest_internal,
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random_yarrow_read);
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}
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/* ARGSUSED */
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void
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random_yarrow_deinit(void)
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{
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struct harvest *np;
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enum esource e;
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/* Deregister the randomness harvesting routine */
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random_yarrow_deinit_harvester();
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/*
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* Command the hash/reseed thread to end and wait for it to finish
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*/
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random_kthread_control = -1;
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tsleep((void *)&random_kthread_control, PUSER, "term", 0);
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/* Destroy the harvest fifos */
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while (!STAILQ_EMPTY(&emptyfifo.head)) {
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np = STAILQ_FIRST(&emptyfifo.head);
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STAILQ_REMOVE_HEAD(&emptyfifo.head, next);
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free(np, M_ENTROPY);
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}
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mtx_destroy(&emptyfifo.lock);
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for (e = RANDOM_START; e < ENTROPYSOURCE; e++) {
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while (!STAILQ_EMPTY(&harvestfifo[e].head)) {
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np = STAILQ_FIRST(&harvestfifo[e].head);
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STAILQ_REMOVE_HEAD(&harvestfifo[e].head, next);
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free(np, M_ENTROPY);
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}
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mtx_destroy(&harvestfifo[e].lock);
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}
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random_yarrow_deinit_alg();
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sysctl_ctx_free(&random_clist);
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}
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/* ARGSUSED */
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static void
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random_kthread(void *arg __unused)
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{
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struct harvest *event = NULL;
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int found, active;
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enum esource source;
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/* Process until told to stop */
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for (; random_kthread_control == 0;) {
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active = 0;
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/* Cycle through all the entropy sources */
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for (source = RANDOM_START; source < ENTROPYSOURCE; source++) {
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found = 0;
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/* Lock up queue draining */
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mtx_lock_spin(&harvestfifo[source].lock);
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if (!STAILQ_EMPTY(&harvestfifo[source].head)) {
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/* Get a harvested entropy event */
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harvestfifo[source].count--;
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event = STAILQ_FIRST(&harvestfifo[source].head);
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STAILQ_REMOVE_HEAD(&harvestfifo[source].head,
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next);
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active = found = 1;
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}
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/* Unlock the queue */
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mtx_unlock_spin(&harvestfifo[source].lock);
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/* Deal with the event and dispose of it */
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if (found) {
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random_process_event(event);
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/* Lock the empty event buffer fifo */
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mtx_lock_spin(&emptyfifo.lock);
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STAILQ_INSERT_TAIL(&emptyfifo.head, event,
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next);
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mtx_unlock_spin(&emptyfifo.lock);
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}
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}
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/* Found nothing, so don't belabour the issue */
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if (!active)
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tsleep(&harvestfifo, PUSER, "-", hz / 10);
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}
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random_set_wakeup_exit(&random_kthread_control);
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/* NOTREACHED */
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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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*/
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static void
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random_harvest_internal(u_int64_t somecounter, const void *entropy,
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u_int count, u_int bits, u_int frac, enum esource origin)
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{
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struct harvest *event;
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/* Lockless read to avoid lock operations if fifo is full. */
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if (harvestfifo[origin].count >= RANDOM_FIFO_MAX)
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return;
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/* Lock the particular fifo */
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mtx_lock_spin(&harvestfifo[origin].lock);
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/*
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* Don't make the harvest queues too big - help to prevent low-grade
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* entropy swamping
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*/
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if (harvestfifo[origin].count < RANDOM_FIFO_MAX) {
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/* Lock the empty event buffer fifo */
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mtx_lock_spin(&emptyfifo.lock);
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if (!STAILQ_EMPTY(&emptyfifo.head)) {
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event = STAILQ_FIRST(&emptyfifo.head);
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STAILQ_REMOVE_HEAD(&emptyfifo.head, next);
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} else
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event = NULL;
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mtx_unlock_spin(&emptyfifo.lock);
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/* If we didn't obtain a buffer, tough */
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if (event) {
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/* Add the harvested data to the fifo */
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harvestfifo[origin].count++;
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event->somecounter = somecounter;
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event->size = count;
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event->bits = bits;
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event->frac = frac;
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event->source = origin;
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/* XXXX Come back and make this dynamic! */
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count = MIN(count, HARVESTSIZE);
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memcpy(event->entropy, entropy, count);
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STAILQ_INSERT_TAIL(&harvestfifo[origin].head,
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event, next);
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}
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}
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mtx_unlock_spin(&harvestfifo[origin].lock);
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}
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void
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random_yarrow_write(void *buf, int count)
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{
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int i;
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u_int chunk;
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/*
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* Break the input up into HARVESTSIZE chunks. The writer has too
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* much control here, so "estimate" the the entropy as zero.
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*/
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for (i = 0; i < count; i += HARVESTSIZE) {
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chunk = HARVESTSIZE;
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if (i + chunk >= count)
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chunk = (u_int)(count - i);
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random_harvest_internal(get_cyclecount(), (char *)buf + i,
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chunk, 0, 0, RANDOM_WRITE);
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}
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}
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void
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random_yarrow_unblock(void)
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{
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if (!random_systat.seeded) {
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random_systat.seeded = 1;
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selwakeuppri(&random_systat.rsel, PUSER);
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wakeup(&random_systat);
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}
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}
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