1/*- 2 * Copyright (c) 2000-2013 Mark R V Murray 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer 10 * in this position and unchanged. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 */ 27 28#include <sys/cdefs.h> 29__FBSDID("$FreeBSD$"); 30 31#include <sys/param.h> 32#include <sys/kthread.h> 33#include <sys/lock.h> 34#include <sys/malloc.h> 35#include <sys/mutex.h> 36#include <sys/poll.h> 37#include <sys/queue.h> 38#include <sys/random.h> 39#include <sys/selinfo.h> 40#include <sys/syslog.h> 41#include <sys/systm.h> 42#include <sys/sysctl.h> 43 44#include <machine/cpu.h> 45 46#include <dev/random/randomdev_soft.h> 47 48static int read_random_phony(void *, int); 49 50/* Structure holding the desired entropy sources */ 51struct harvest_select harvest = { 1, 1, 1, 1 }; 52static int warned = 0; 53 54/* hold the address of the routine which is actually called if 55 * the randomdev is loaded 56 */ 57static void (*reap_func)(u_int64_t, const void *, u_int, u_int, 58 enum esource) = NULL; 59static int (*read_func)(void *, int) = read_random_phony; 60 61/* Initialise the harvester at load time */ 62void 63randomdev_init_harvester(void (*reaper)(u_int64_t, const void *, u_int, 64 u_int, enum esource), int (*reader)(void *, int)) 65{ 66 reap_func = reaper; 67 read_func = reader; 68} 69 70/* Deinitialise the harvester at unload time */ 71void 72randomdev_deinit_harvester(void) 73{ 74 reap_func = NULL; 75 read_func = read_random_phony; 76 warned = 0; 77} 78 79/* Entropy harvesting routine. This is supposed to be fast; do 80 * not do anything slow in here! 81 * Implemented as in indirect call to allow non-inclusion of 82 * the entropy device. 83 * 84 * XXXRW: get_cyclecount() is cheap on most modern hardware, where cycle 85 * counters are built in, but on older hardware it will do a real time clock 86 * read which can be quite expensive. 87 */ 88void 89random_harvest(void *entropy, u_int count, u_int bits, enum esource origin) 90{ 91 if (reap_func) 92 (*reap_func)(get_cyclecount(), entropy, count, bits, origin); 93} 94 95/* Userland-visible version of read_random */ 96int 97read_random(void *buf, int count) 98{ 99 return ((*read_func)(buf, count)); 100} 101 102/* If the entropy device is not loaded, make a token effort to 103 * provide _some_ kind of randomness. This should only be used 104 * inside other RNG's, like arc4random(9). 105 */ 106static int 107read_random_phony(void *buf, int count) 108{ 109 u_long randval; 110 int size, i; 111 112 if (!warned) { 113 log(LOG_WARNING, "random device not loaded; using insecure entropy\n"); 114 warned = 1; 115 } 116 117 /* srandom() is called in kern/init_main.c:proc0_post() */ 118 119 /* Fill buf[] with random(9) output */ 120 for (i = 0; i < count; i+= (int)sizeof(u_long)) { 121 randval = random(); 122 size = MIN(count - i, sizeof(u_long)); 123 memcpy(&((char *)buf)[i], &randval, (size_t)size); 124 } 125 126 return (count); 127} 128 129/* Helper routine to enable kproc_exit() to work while the module is 130 * being (or has been) unloaded. 131 * This routine is in this file because it is always linked into the kernel, 132 * and will thus never be unloaded. This is critical for unloadable modules 133 * that have threads. 134 */ 135void 136random_set_wakeup_exit(void *control) 137{ 138 wakeup(control); 139 kproc_exit(0); 140 /* NOTREACHED */ 141} 142