dummy_rng.c revision 256414
1/*- 2 * Copyright (c) 2013 Arthur Mesh <arthurmesh@gmail.com> 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#include <sys/cdefs.h> 28__FBSDID("$FreeBSD: stable/10/sys/dev/random/dummy_rng.c 256414 2013-10-13 00:13:57Z markm $"); 29 30#include <sys/param.h> 31#include <sys/fcntl.h> 32#include <sys/kernel.h> 33#include <sys/malloc.h> 34#include <sys/module.h> 35#include <sys/random.h> 36#include <sys/selinfo.h> 37#include <sys/systm.h> 38#include <sys/time.h> 39 40#include <dev/random/random_adaptors.h> 41#include <dev/random/randomdev.h> 42 43static struct mtx dummy_random_mtx; 44 45/* Used to fake out unused random calls in random_adaptor */ 46static void 47random_null_func(void) 48{ 49} 50 51static int 52dummy_random_poll(int events __unused, struct thread *td __unused) 53{ 54 55 return (0); 56} 57 58static int 59dummy_random_block(int flag) 60{ 61 int error = 0; 62 63 mtx_lock(&dummy_random_mtx); 64 65 /* Blocking logic */ 66 while (!error) { 67 if (flag & O_NONBLOCK) 68 error = EWOULDBLOCK; 69 else { 70 printf("random: dummy device blocking on read.\n"); 71 error = msleep(&dummy_random_block, 72 &dummy_random_mtx, 73 PUSER | PCATCH, "block", 0); 74 } 75 } 76 mtx_unlock(&dummy_random_mtx); 77 78 return (error); 79} 80 81static void 82dummy_random_init(void) 83{ 84 85 mtx_init(&dummy_random_mtx, "sleep mtx for dummy_random", 86 NULL, MTX_DEF); 87} 88 89static void 90dummy_random_deinit(void) 91{ 92 93 mtx_destroy(&dummy_random_mtx); 94} 95 96struct random_adaptor dummy_random = { 97 .ident = "Dummy entropy device that always blocks", 98 .init = dummy_random_init, 99 .deinit = dummy_random_deinit, 100 .block = dummy_random_block, 101 .poll = dummy_random_poll, 102 .read = (random_read_func_t *)random_null_func, 103 .reseed = (random_reseed_func_t *)random_null_func, 104 .seeded = 0, /* This device can never be seeded */ 105 .priority = 1, /* Bottom priority, so goes to last position */ 106}; 107 108static int 109dummy_random_modevent(module_t mod __unused, int type, void *unused __unused) 110{ 111 112 switch (type) { 113 case MOD_LOAD: 114 random_adaptor_register("dummy", &dummy_random); 115 EVENTHANDLER_INVOKE(random_adaptor_attach, 116 &dummy_random); 117 118 return (0); 119 } 120 121 return (EINVAL); 122} 123 124RANDOM_ADAPTOR_MODULE(dummy, dummy_random_modevent, 1); 125