randomdev.c revision 255362
1/*- 2 * Copyright (c) 2013 Arthur Mesh <arthurmesh@gmail.com> 3 * Copyright (c) 2000-2004 Mark R V Murray 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer 11 * in this position and unchanged. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 */ 28 29#include <sys/cdefs.h> 30__FBSDID("$FreeBSD: head/sys/dev/random/randomdev.c 255362 2013-09-07 14:15:13Z markm $"); 31 32#include <sys/param.h> 33#include <sys/systm.h> 34#include <sys/bus.h> 35#include <sys/conf.h> 36#include <sys/fcntl.h> 37#include <sys/filio.h> 38#include <sys/kernel.h> 39#include <sys/kthread.h> 40#include <sys/lock.h> 41#include <sys/malloc.h> 42#include <sys/module.h> 43#include <sys/mutex.h> 44#include <sys/poll.h> 45#include <sys/priv.h> 46#include <sys/proc.h> 47#include <sys/selinfo.h> 48#include <sys/uio.h> 49#include <sys/unistd.h> 50 51#include <machine/bus.h> 52#include <machine/cpu.h> 53 54#include <dev/random/random_adaptors.h> 55#include <dev/random/randomdev.h> 56 57#define RANDOM_MINOR 0 58 59static d_close_t random_close; 60static d_read_t random_read; 61static d_write_t random_write; 62static d_ioctl_t random_ioctl; 63static d_poll_t random_poll; 64 65static struct cdevsw random_cdevsw = { 66 .d_version = D_VERSION, 67 .d_close = random_close, 68 .d_read = random_read, 69 .d_write = random_write, 70 .d_ioctl = random_ioctl, 71 .d_poll = random_poll, 72 .d_name = "random", 73}; 74 75static struct random_adaptor *random_adaptor; 76static eventhandler_tag attach_tag; 77static int random_inited; 78 79 80/* For use with make_dev(9)/destroy_dev(9). */ 81static struct cdev *random_dev; 82 83/* Used to fake out unused random calls in random_adaptor */ 84void 85random_null_func(void) 86{ 87} 88 89struct random_adaptor * 90random_get_active_adaptor(void) 91{ 92 93 return (random_adaptor); 94} 95 96/* ARGSUSED */ 97static int 98random_close(struct cdev *dev __unused, int flags, int fmt __unused, 99 struct thread *td) 100{ 101 if ((flags & FWRITE) && (priv_check(td, PRIV_RANDOM_RESEED) == 0) 102 && (securelevel_gt(td->td_ucred, 0) == 0)) { 103 (*random_adaptor->reseed)(); 104 random_adaptor->seeded = 1; 105 arc4rand(NULL, 0, 1); /* Reseed arc4random as well. */ 106 } 107 108 return (0); 109} 110 111/* ARGSUSED */ 112static int 113random_read(struct cdev *dev __unused, struct uio *uio, int flag) 114{ 115 int c, error = 0; 116 void *random_buf; 117 118 /* Blocking logic */ 119 if (!random_adaptor->seeded) 120 error = (*random_adaptor->block)(flag); 121 122 /* The actual read */ 123 if (!error) { 124 125 random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK); 126 127 while (uio->uio_resid > 0 && !error) { 128 c = MIN(uio->uio_resid, PAGE_SIZE); 129 c = (*random_adaptor->read)(random_buf, c); 130 error = uiomove(random_buf, c, uio); 131 } 132 133 free(random_buf, M_TEMP); 134 135 } 136 137 return (error); 138} 139 140/* ARGSUSED */ 141static int 142random_write(struct cdev *dev __unused, struct uio *uio, int flag __unused) 143{ 144 int c, error = 0; 145 void *random_buf; 146 147 random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK); 148 149 while (uio->uio_resid > 0) { 150 c = MIN((int)uio->uio_resid, PAGE_SIZE); 151 error = uiomove(random_buf, c, uio); 152 if (error) 153 break; 154 (*random_adaptor->write)(random_buf, c); 155 } 156 157 free(random_buf, M_TEMP); 158 159 return (error); 160} 161 162/* ARGSUSED */ 163static int 164random_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t addr __unused, 165 int flags __unused, struct thread *td __unused) 166{ 167 int error = 0; 168 169 switch (cmd) { 170 /* Really handled in upper layer */ 171 case FIOASYNC: 172 case FIONBIO: 173 break; 174 default: 175 error = ENOTTY; 176 } 177 return (error); 178} 179 180/* ARGSUSED */ 181static int 182random_poll(struct cdev *dev __unused, int events, struct thread *td) 183{ 184 int revents = 0; 185 186 if (events & (POLLIN | POLLRDNORM)) { 187 if (random_adaptor->seeded) 188 revents = events & (POLLIN | POLLRDNORM); 189 else 190 revents = (*random_adaptor->poll) (events,td); 191 } 192 return (revents); 193} 194 195static void 196random_initialize(void *p, struct random_adaptor *s) 197{ 198 if (random_inited) { 199 printf("random: <%s> already initialized\n", 200 random_adaptor->ident); 201 return; 202 } 203 204 random_adaptor = s; 205 206 (s->init)(); 207 208 printf("random: <%s> initialized\n", s->ident); 209 210 random_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &random_cdevsw, 211 RANDOM_MINOR, NULL, UID_ROOT, GID_WHEEL, 0666, "random"); 212 make_dev_alias(random_dev, "urandom"); /* XXX Deprecated */ 213 214 /* mark random(4) as initialized, to avoid being called again */ 215 random_inited = 1; 216} 217 218/* ARGSUSED */ 219static int 220random_modevent(module_t mod __unused, int type, void *data __unused) 221{ 222 int error = 0; 223 224 switch (type) { 225 case MOD_LOAD: 226 random_adaptor_choose(&random_adaptor); 227 228 if (random_adaptor == NULL) { 229 printf( 230 "random: No random adaptor attached, postponing initialization\n"); 231 attach_tag = EVENTHANDLER_REGISTER(random_adaptor_attach, 232 random_initialize, NULL, EVENTHANDLER_PRI_ANY); 233 } else { 234 random_initialize(NULL, random_adaptor); 235 } 236 237 break; 238 239 case MOD_UNLOAD: 240 if (random_adaptor != NULL) { 241 (*random_adaptor->deinit)(); 242 destroy_dev(random_dev); 243 } 244 /* Unregister the event handler */ 245 if (attach_tag != NULL) { 246 EVENTHANDLER_DEREGISTER(random_adaptor_attach, 247 attach_tag); 248 } 249 250 break; 251 252 case MOD_SHUTDOWN: 253 break; 254 255 default: 256 error = EOPNOTSUPP; 257 break; 258 259 } 260 return (error); 261} 262 263DEV_MODULE(random, random_modevent, NULL); 264MODULE_VERSION(random, 1); 265