| 1 | /* $NetBSD: subr_cprng.c,v 1.27 2015/04/13 22:43:41 riastradh Exp $ */ |
| 2 | |
| 3 | /*- |
| 4 | * Copyright (c) 2011-2013 The NetBSD Foundation, Inc. |
| 5 | * All rights reserved. |
| 6 | * |
| 7 | * This code is derived from software contributed to The NetBSD Foundation |
| 8 | * by Thor Lancelot Simon and Taylor R. Campbell. |
| 9 | * |
| 10 | * Redistribution and use in source and binary forms, with or without |
| 11 | * modification, are permitted provided that the following conditions |
| 12 | * are met: |
| 13 | * 1. Redistributions of source code must retain the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer. |
| 15 | * 2. Redistributions in binary form must reproduce the above copyright |
| 16 | * notice, this list of conditions and the following disclaimer in the |
| 17 | * documentation and/or other materials provided with the distribution. |
| 18 | * |
| 19 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
| 20 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
| 21 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 22 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
| 23 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 24 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 25 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 26 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 27 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 28 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 29 | * POSSIBILITY OF SUCH DAMAGE. |
| 30 | */ |
| 31 | |
| 32 | #include <sys/cdefs.h> |
| 33 | __KERNEL_RCSID(0, "$NetBSD: subr_cprng.c,v 1.27 2015/04/13 22:43:41 riastradh Exp $" ); |
| 34 | |
| 35 | #include <sys/param.h> |
| 36 | #include <sys/types.h> |
| 37 | #include <sys/condvar.h> |
| 38 | #include <sys/cprng.h> |
| 39 | #include <sys/errno.h> |
| 40 | #include <sys/event.h> /* XXX struct knote */ |
| 41 | #include <sys/fcntl.h> /* XXX FNONBLOCK */ |
| 42 | #include <sys/kernel.h> |
| 43 | #include <sys/kmem.h> |
| 44 | #include <sys/lwp.h> |
| 45 | #include <sys/once.h> |
| 46 | #include <sys/percpu.h> |
| 47 | #include <sys/poll.h> /* XXX POLLIN/POLLOUT/&c. */ |
| 48 | #include <sys/select.h> |
| 49 | #include <sys/systm.h> |
| 50 | #include <sys/sysctl.h> |
| 51 | #include <sys/rndsink.h> |
| 52 | #if DIAGNOSTIC |
| 53 | #include <sys/rngtest.h> |
| 54 | #endif |
| 55 | |
| 56 | #include <crypto/nist_ctr_drbg/nist_ctr_drbg.h> |
| 57 | |
| 58 | #if defined(__HAVE_CPU_COUNTER) |
| 59 | #include <machine/cpu_counter.h> |
| 60 | #endif |
| 61 | |
| 62 | static int sysctl_kern_urnd(SYSCTLFN_PROTO); |
| 63 | static int sysctl_kern_arnd(SYSCTLFN_PROTO); |
| 64 | |
| 65 | static void cprng_strong_generate(struct cprng_strong *, void *, size_t); |
| 66 | static void cprng_strong_reseed(struct cprng_strong *); |
| 67 | static void cprng_strong_reseed_from(struct cprng_strong *, const void *, |
| 68 | size_t, bool); |
| 69 | #if DIAGNOSTIC |
| 70 | static void cprng_strong_rngtest(struct cprng_strong *); |
| 71 | #endif |
| 72 | |
| 73 | static rndsink_callback_t cprng_strong_rndsink_callback; |
| 74 | |
| 75 | void |
| 76 | cprng_init(void) |
| 77 | { |
| 78 | static struct sysctllog *random_sysctllog; |
| 79 | |
| 80 | nist_ctr_initialize(); |
| 81 | |
| 82 | sysctl_createv(&random_sysctllog, 0, NULL, NULL, |
| 83 | CTLFLAG_PERMANENT, |
| 84 | CTLTYPE_INT, "urandom" , |
| 85 | SYSCTL_DESCR("Random integer value" ), |
| 86 | sysctl_kern_urnd, 0, NULL, 0, |
| 87 | CTL_KERN, KERN_URND, CTL_EOL); |
| 88 | sysctl_createv(&random_sysctllog, 0, NULL, NULL, |
| 89 | CTLFLAG_PERMANENT, |
| 90 | CTLTYPE_INT, "arandom" , |
| 91 | SYSCTL_DESCR("n bytes of random data" ), |
| 92 | sysctl_kern_arnd, 0, NULL, 0, |
| 93 | CTL_KERN, KERN_ARND, CTL_EOL); |
| 94 | } |
| 95 | |
| 96 | static inline uint32_t |
| 97 | cprng_counter(void) |
| 98 | { |
| 99 | struct timeval tv; |
| 100 | |
| 101 | #if defined(__HAVE_CPU_COUNTER) |
| 102 | if (cpu_hascounter()) |
| 103 | return cpu_counter32(); |
| 104 | #endif |
| 105 | if (__predict_false(cold)) { |
| 106 | static int ctr; |
| 107 | /* microtime unsafe if clock not running yet */ |
| 108 | return ctr++; |
| 109 | } |
| 110 | getmicrotime(&tv); |
| 111 | return (tv.tv_sec * 1000000 + tv.tv_usec); |
| 112 | } |
| 113 | |
| 114 | struct cprng_strong { |
| 115 | char cs_name[16]; |
| 116 | int cs_flags; |
| 117 | kmutex_t cs_lock; |
| 118 | percpu_t *cs_percpu; |
| 119 | kcondvar_t cs_cv; |
| 120 | struct selinfo cs_selq; |
| 121 | struct rndsink *cs_rndsink; |
| 122 | bool cs_ready; |
| 123 | NIST_CTR_DRBG cs_drbg; |
| 124 | |
| 125 | /* XXX Kludge for /dev/random `information-theoretic' properties. */ |
| 126 | unsigned int cs_remaining; |
| 127 | }; |
| 128 | |
| 129 | struct cprng_strong * |
| 130 | cprng_strong_create(const char *name, int ipl, int flags) |
| 131 | { |
| 132 | const uint32_t cc = cprng_counter(); |
| 133 | struct cprng_strong *const cprng = kmem_alloc(sizeof(*cprng), |
| 134 | KM_SLEEP); |
| 135 | |
| 136 | /* |
| 137 | * rndsink_request takes a spin lock at IPL_VM, so we can be no |
| 138 | * higher than that. |
| 139 | */ |
| 140 | KASSERT(ipl != IPL_SCHED && ipl != IPL_HIGH); |
| 141 | |
| 142 | /* Initialize the easy fields. */ |
| 143 | (void)strlcpy(cprng->cs_name, name, sizeof(cprng->cs_name)); |
| 144 | cprng->cs_flags = flags; |
| 145 | mutex_init(&cprng->cs_lock, MUTEX_DEFAULT, ipl); |
| 146 | cv_init(&cprng->cs_cv, cprng->cs_name); |
| 147 | selinit(&cprng->cs_selq); |
| 148 | cprng->cs_rndsink = rndsink_create(NIST_BLOCK_KEYLEN_BYTES, |
| 149 | &cprng_strong_rndsink_callback, cprng); |
| 150 | |
| 151 | /* Get some initial entropy. Record whether it is full entropy. */ |
| 152 | uint8_t seed[NIST_BLOCK_KEYLEN_BYTES]; |
| 153 | mutex_enter(&cprng->cs_lock); |
| 154 | cprng->cs_ready = rndsink_request(cprng->cs_rndsink, seed, |
| 155 | sizeof(seed)); |
| 156 | if (nist_ctr_drbg_instantiate(&cprng->cs_drbg, seed, sizeof(seed), |
| 157 | &cc, sizeof(cc), cprng->cs_name, sizeof(cprng->cs_name))) |
| 158 | /* XXX Fix nist_ctr_drbg API so this can't happen. */ |
| 159 | panic("cprng %s: NIST CTR_DRBG instantiation failed" , |
| 160 | cprng->cs_name); |
| 161 | explicit_memset(seed, 0, sizeof(seed)); |
| 162 | |
| 163 | if (ISSET(flags, CPRNG_HARD)) |
| 164 | cprng->cs_remaining = NIST_BLOCK_KEYLEN_BYTES; |
| 165 | else |
| 166 | cprng->cs_remaining = 0; |
| 167 | |
| 168 | if (!cprng->cs_ready && !ISSET(flags, CPRNG_INIT_ANY)) |
| 169 | printf("cprng %s: creating with partial entropy\n" , |
| 170 | cprng->cs_name); |
| 171 | mutex_exit(&cprng->cs_lock); |
| 172 | |
| 173 | return cprng; |
| 174 | } |
| 175 | |
| 176 | void |
| 177 | cprng_strong_destroy(struct cprng_strong *cprng) |
| 178 | { |
| 179 | |
| 180 | /* |
| 181 | * Destroy the rndsink first to prevent calls to the callback. |
| 182 | */ |
| 183 | rndsink_destroy(cprng->cs_rndsink); |
| 184 | |
| 185 | KASSERT(!cv_has_waiters(&cprng->cs_cv)); |
| 186 | #if 0 |
| 187 | KASSERT(!select_has_waiters(&cprng->cs_selq)) /* XXX ? */ |
| 188 | #endif |
| 189 | |
| 190 | nist_ctr_drbg_destroy(&cprng->cs_drbg); |
| 191 | seldestroy(&cprng->cs_selq); |
| 192 | cv_destroy(&cprng->cs_cv); |
| 193 | mutex_destroy(&cprng->cs_lock); |
| 194 | |
| 195 | explicit_memset(cprng, 0, sizeof(*cprng)); /* paranoia */ |
| 196 | kmem_free(cprng, sizeof(*cprng)); |
| 197 | } |
| 198 | |
| 199 | /* |
| 200 | * Generate some data from cprng. Block or return zero bytes, |
| 201 | * depending on flags & FNONBLOCK, if cprng was created without |
| 202 | * CPRNG_REKEY_ANY. |
| 203 | */ |
| 204 | size_t |
| 205 | cprng_strong(struct cprng_strong *cprng, void *buffer, size_t bytes, int flags) |
| 206 | { |
| 207 | size_t result; |
| 208 | |
| 209 | /* Caller must loop for more than CPRNG_MAX_LEN bytes. */ |
| 210 | bytes = MIN(bytes, CPRNG_MAX_LEN); |
| 211 | |
| 212 | mutex_enter(&cprng->cs_lock); |
| 213 | |
| 214 | if (ISSET(cprng->cs_flags, CPRNG_REKEY_ANY)) { |
| 215 | if (!cprng->cs_ready) |
| 216 | cprng_strong_reseed(cprng); |
| 217 | } else { |
| 218 | while (!cprng->cs_ready) { |
| 219 | if (ISSET(flags, FNONBLOCK) || |
| 220 | !ISSET(cprng->cs_flags, CPRNG_USE_CV) || |
| 221 | cv_wait_sig(&cprng->cs_cv, &cprng->cs_lock)) { |
| 222 | result = 0; |
| 223 | goto out; |
| 224 | } |
| 225 | } |
| 226 | } |
| 227 | |
| 228 | /* |
| 229 | * Debit the entropy if requested. |
| 230 | * |
| 231 | * XXX Kludge for /dev/random `information-theoretic' properties. |
| 232 | */ |
| 233 | if (__predict_false(ISSET(cprng->cs_flags, CPRNG_HARD))) { |
| 234 | KASSERT(0 < cprng->cs_remaining); |
| 235 | KASSERT(cprng->cs_remaining <= NIST_BLOCK_KEYLEN_BYTES); |
| 236 | if (bytes < cprng->cs_remaining) { |
| 237 | cprng->cs_remaining -= bytes; |
| 238 | } else { |
| 239 | bytes = cprng->cs_remaining; |
| 240 | cprng->cs_remaining = NIST_BLOCK_KEYLEN_BYTES; |
| 241 | cprng->cs_ready = false; |
| 242 | rndsink_schedule(cprng->cs_rndsink); |
| 243 | } |
| 244 | KASSERT(bytes <= NIST_BLOCK_KEYLEN_BYTES); |
| 245 | KASSERT(0 < cprng->cs_remaining); |
| 246 | KASSERT(cprng->cs_remaining <= NIST_BLOCK_KEYLEN_BYTES); |
| 247 | } |
| 248 | |
| 249 | cprng_strong_generate(cprng, buffer, bytes); |
| 250 | result = bytes; |
| 251 | |
| 252 | out: mutex_exit(&cprng->cs_lock); |
| 253 | return result; |
| 254 | } |
| 255 | |
| 256 | static void filt_cprng_detach(struct knote *); |
| 257 | static int filt_cprng_event(struct knote *, long); |
| 258 | |
| 259 | static const struct filterops cprng_filtops = |
| 260 | { 1, NULL, filt_cprng_detach, filt_cprng_event }; |
| 261 | |
| 262 | int |
| 263 | cprng_strong_kqfilter(struct cprng_strong *cprng, struct knote *kn) |
| 264 | { |
| 265 | |
| 266 | switch (kn->kn_filter) { |
| 267 | case EVFILT_READ: |
| 268 | kn->kn_fop = &cprng_filtops; |
| 269 | kn->kn_hook = cprng; |
| 270 | mutex_enter(&cprng->cs_lock); |
| 271 | SLIST_INSERT_HEAD(&cprng->cs_selq.sel_klist, kn, kn_selnext); |
| 272 | mutex_exit(&cprng->cs_lock); |
| 273 | return 0; |
| 274 | |
| 275 | case EVFILT_WRITE: |
| 276 | default: |
| 277 | return EINVAL; |
| 278 | } |
| 279 | } |
| 280 | |
| 281 | static void |
| 282 | filt_cprng_detach(struct knote *kn) |
| 283 | { |
| 284 | struct cprng_strong *const cprng = kn->kn_hook; |
| 285 | |
| 286 | mutex_enter(&cprng->cs_lock); |
| 287 | SLIST_REMOVE(&cprng->cs_selq.sel_klist, kn, knote, kn_selnext); |
| 288 | mutex_exit(&cprng->cs_lock); |
| 289 | } |
| 290 | |
| 291 | static int |
| 292 | filt_cprng_event(struct knote *kn, long hint) |
| 293 | { |
| 294 | struct cprng_strong *const cprng = kn->kn_hook; |
| 295 | int ret; |
| 296 | |
| 297 | if (hint == NOTE_SUBMIT) |
| 298 | KASSERT(mutex_owned(&cprng->cs_lock)); |
| 299 | else |
| 300 | mutex_enter(&cprng->cs_lock); |
| 301 | if (cprng->cs_ready) { |
| 302 | kn->kn_data = CPRNG_MAX_LEN; /* XXX Too large? */ |
| 303 | ret = 1; |
| 304 | } else { |
| 305 | ret = 0; |
| 306 | } |
| 307 | if (hint == NOTE_SUBMIT) |
| 308 | KASSERT(mutex_owned(&cprng->cs_lock)); |
| 309 | else |
| 310 | mutex_exit(&cprng->cs_lock); |
| 311 | |
| 312 | return ret; |
| 313 | } |
| 314 | |
| 315 | int |
| 316 | cprng_strong_poll(struct cprng_strong *cprng, int events) |
| 317 | { |
| 318 | int revents; |
| 319 | |
| 320 | if (!ISSET(events, (POLLIN | POLLRDNORM))) |
| 321 | return 0; |
| 322 | |
| 323 | mutex_enter(&cprng->cs_lock); |
| 324 | if (cprng->cs_ready) { |
| 325 | revents = (events & (POLLIN | POLLRDNORM)); |
| 326 | } else { |
| 327 | selrecord(curlwp, &cprng->cs_selq); |
| 328 | revents = 0; |
| 329 | } |
| 330 | mutex_exit(&cprng->cs_lock); |
| 331 | |
| 332 | return revents; |
| 333 | } |
| 334 | |
| 335 | /* |
| 336 | * XXX Move nist_ctr_drbg_reseed_advised_p and |
| 337 | * nist_ctr_drbg_reseed_needed_p into the nist_ctr_drbg API and make |
| 338 | * the NIST_CTR_DRBG structure opaque. |
| 339 | */ |
| 340 | static bool |
| 341 | nist_ctr_drbg_reseed_advised_p(NIST_CTR_DRBG *drbg) |
| 342 | { |
| 343 | |
| 344 | return (drbg->reseed_counter > (NIST_CTR_DRBG_RESEED_INTERVAL / 2)); |
| 345 | } |
| 346 | |
| 347 | static bool |
| 348 | nist_ctr_drbg_reseed_needed_p(NIST_CTR_DRBG *drbg) |
| 349 | { |
| 350 | |
| 351 | return (drbg->reseed_counter >= NIST_CTR_DRBG_RESEED_INTERVAL); |
| 352 | } |
| 353 | |
| 354 | /* |
| 355 | * Generate some data from the underlying generator. |
| 356 | */ |
| 357 | static void |
| 358 | cprng_strong_generate(struct cprng_strong *cprng, void *buffer, size_t bytes) |
| 359 | { |
| 360 | const uint32_t cc = cprng_counter(); |
| 361 | |
| 362 | KASSERT(bytes <= CPRNG_MAX_LEN); |
| 363 | KASSERT(mutex_owned(&cprng->cs_lock)); |
| 364 | |
| 365 | /* |
| 366 | * Generate some data from the NIST CTR_DRBG. Caller |
| 367 | * guarantees reseed if we're not ready, and if we exhaust the |
| 368 | * generator, we mark ourselves not ready. Consequently, this |
| 369 | * call to the CTR_DRBG should not fail. |
| 370 | */ |
| 371 | if (__predict_false(nist_ctr_drbg_generate(&cprng->cs_drbg, buffer, |
| 372 | bytes, &cc, sizeof(cc)))) |
| 373 | panic("cprng %s: NIST CTR_DRBG failed" , cprng->cs_name); |
| 374 | |
| 375 | /* |
| 376 | * If we've been seeing a lot of use, ask for some fresh |
| 377 | * entropy soon. |
| 378 | */ |
| 379 | if (__predict_false(nist_ctr_drbg_reseed_advised_p(&cprng->cs_drbg))) |
| 380 | rndsink_schedule(cprng->cs_rndsink); |
| 381 | |
| 382 | /* |
| 383 | * If we just exhausted the generator, inform the next user |
| 384 | * that we need a reseed. |
| 385 | */ |
| 386 | if (__predict_false(nist_ctr_drbg_reseed_needed_p(&cprng->cs_drbg))) { |
| 387 | cprng->cs_ready = false; |
| 388 | rndsink_schedule(cprng->cs_rndsink); /* paranoia */ |
| 389 | } |
| 390 | } |
| 391 | |
| 392 | /* |
| 393 | * Reseed with whatever we can get from the system entropy pool right now. |
| 394 | */ |
| 395 | static void |
| 396 | cprng_strong_reseed(struct cprng_strong *cprng) |
| 397 | { |
| 398 | uint8_t seed[NIST_BLOCK_KEYLEN_BYTES]; |
| 399 | |
| 400 | KASSERT(mutex_owned(&cprng->cs_lock)); |
| 401 | |
| 402 | const bool full_entropy = rndsink_request(cprng->cs_rndsink, seed, |
| 403 | sizeof(seed)); |
| 404 | cprng_strong_reseed_from(cprng, seed, sizeof(seed), full_entropy); |
| 405 | explicit_memset(seed, 0, sizeof(seed)); |
| 406 | } |
| 407 | |
| 408 | /* |
| 409 | * Reseed with the given seed. If we now have full entropy, notify waiters. |
| 410 | */ |
| 411 | static void |
| 412 | cprng_strong_reseed_from(struct cprng_strong *cprng, |
| 413 | const void *seed, size_t bytes, bool full_entropy) |
| 414 | { |
| 415 | const uint32_t cc = cprng_counter(); |
| 416 | |
| 417 | KASSERT(bytes == NIST_BLOCK_KEYLEN_BYTES); |
| 418 | KASSERT(mutex_owned(&cprng->cs_lock)); |
| 419 | |
| 420 | /* |
| 421 | * Notify anyone interested in the partiality of entropy in our |
| 422 | * seed -- anyone waiting for full entropy, or any system |
| 423 | * operators interested in knowing when the entropy pool is |
| 424 | * running on fumes. |
| 425 | */ |
| 426 | if (full_entropy) { |
| 427 | if (!cprng->cs_ready) { |
| 428 | cprng->cs_ready = true; |
| 429 | cv_broadcast(&cprng->cs_cv); |
| 430 | selnotify(&cprng->cs_selq, (POLLIN | POLLRDNORM), |
| 431 | NOTE_SUBMIT); |
| 432 | } |
| 433 | } else { |
| 434 | /* |
| 435 | * XXX Is there is any harm in reseeding with partial |
| 436 | * entropy when we had full entropy before? If so, |
| 437 | * remove the conditional on this message. |
| 438 | */ |
| 439 | if (!cprng->cs_ready && |
| 440 | !ISSET(cprng->cs_flags, CPRNG_REKEY_ANY)) |
| 441 | printf("cprng %s: reseeding with partial entropy\n" , |
| 442 | cprng->cs_name); |
| 443 | } |
| 444 | |
| 445 | if (nist_ctr_drbg_reseed(&cprng->cs_drbg, seed, bytes, &cc, sizeof(cc))) |
| 446 | /* XXX Fix nist_ctr_drbg API so this can't happen. */ |
| 447 | panic("cprng %s: NIST CTR_DRBG reseed failed" , cprng->cs_name); |
| 448 | |
| 449 | #if DIAGNOSTIC |
| 450 | cprng_strong_rngtest(cprng); |
| 451 | #endif |
| 452 | } |
| 453 | |
| 454 | #if DIAGNOSTIC |
| 455 | /* |
| 456 | * Generate some output and apply a statistical RNG test to it. |
| 457 | */ |
| 458 | static void |
| 459 | cprng_strong_rngtest(struct cprng_strong *cprng) |
| 460 | { |
| 461 | |
| 462 | KASSERT(mutex_owned(&cprng->cs_lock)); |
| 463 | |
| 464 | /* XXX Switch to a pool cache instead? */ |
| 465 | rngtest_t *const rt = kmem_intr_alloc(sizeof(*rt), KM_NOSLEEP); |
| 466 | if (rt == NULL) |
| 467 | /* XXX Warn? */ |
| 468 | return; |
| 469 | |
| 470 | (void)strlcpy(rt->rt_name, cprng->cs_name, sizeof(rt->rt_name)); |
| 471 | |
| 472 | if (nist_ctr_drbg_generate(&cprng->cs_drbg, rt->rt_b, sizeof(rt->rt_b), |
| 473 | NULL, 0)) |
| 474 | panic("cprng %s: NIST CTR_DRBG failed after reseed" , |
| 475 | cprng->cs_name); |
| 476 | |
| 477 | if (rngtest(rt)) { |
| 478 | printf("cprng %s: failed statistical RNG test\n" , |
| 479 | cprng->cs_name); |
| 480 | /* XXX Not clear that this does any good... */ |
| 481 | cprng->cs_ready = false; |
| 482 | rndsink_schedule(cprng->cs_rndsink); |
| 483 | } |
| 484 | |
| 485 | explicit_memset(rt, 0, sizeof(*rt)); /* paranoia */ |
| 486 | kmem_intr_free(rt, sizeof(*rt)); |
| 487 | } |
| 488 | #endif |
| 489 | |
| 490 | /* |
| 491 | * Feed entropy from an rndsink request into the CPRNG for which the |
| 492 | * request was issued. |
| 493 | */ |
| 494 | static void |
| 495 | cprng_strong_rndsink_callback(void *context, const void *seed, size_t bytes) |
| 496 | { |
| 497 | struct cprng_strong *const cprng = context; |
| 498 | |
| 499 | mutex_enter(&cprng->cs_lock); |
| 500 | /* Assume that rndsinks provide only full-entropy output. */ |
| 501 | cprng_strong_reseed_from(cprng, seed, bytes, true); |
| 502 | mutex_exit(&cprng->cs_lock); |
| 503 | } |
| 504 | |
| 505 | static cprng_strong_t *sysctl_prng; |
| 506 | |
| 507 | static int |
| 508 | makeprng(void) |
| 509 | { |
| 510 | |
| 511 | /* can't create in cprng_init(), too early */ |
| 512 | sysctl_prng = cprng_strong_create("sysctl" , IPL_NONE, |
| 513 | CPRNG_INIT_ANY|CPRNG_REKEY_ANY); |
| 514 | return 0; |
| 515 | } |
| 516 | |
| 517 | /* |
| 518 | * sysctl helper routine for kern.urandom node. Picks a random number |
| 519 | * for you. |
| 520 | */ |
| 521 | static int |
| 522 | sysctl_kern_urnd(SYSCTLFN_ARGS) |
| 523 | { |
| 524 | static ONCE_DECL(control); |
| 525 | int v, rv; |
| 526 | |
| 527 | RUN_ONCE(&control, makeprng); |
| 528 | rv = cprng_strong(sysctl_prng, &v, sizeof(v), 0); |
| 529 | if (rv == sizeof(v)) { |
| 530 | struct sysctlnode node = *rnode; |
| 531 | node.sysctl_data = &v; |
| 532 | return (sysctl_lookup(SYSCTLFN_CALL(&node))); |
| 533 | } |
| 534 | else |
| 535 | return (EIO); /*XXX*/ |
| 536 | } |
| 537 | |
| 538 | /* |
| 539 | * sysctl helper routine for kern.arandom node. Fills the supplied |
| 540 | * structure with random data for you. |
| 541 | * |
| 542 | * This node was originally declared as type "int" but its implementation |
| 543 | * in OpenBSD, whence it came, would happily return up to 8K of data if |
| 544 | * requested. Evidently this was used to key RC4 in userspace. |
| 545 | * |
| 546 | * In NetBSD, the libc stack-smash-protection code reads 64 bytes |
| 547 | * from here at every program startup. So though it would be nice |
| 548 | * to make this node return only 32 or 64 bits, we can't. Too bad! |
| 549 | */ |
| 550 | static int |
| 551 | sysctl_kern_arnd(SYSCTLFN_ARGS) |
| 552 | { |
| 553 | int error; |
| 554 | void *v; |
| 555 | struct sysctlnode node = *rnode; |
| 556 | |
| 557 | switch (*oldlenp) { |
| 558 | case 0: |
| 559 | return 0; |
| 560 | default: |
| 561 | if (*oldlenp > 256) { |
| 562 | return E2BIG; |
| 563 | } |
| 564 | v = kmem_alloc(*oldlenp, KM_SLEEP); |
| 565 | cprng_fast(v, *oldlenp); |
| 566 | node.sysctl_data = v; |
| 567 | node.sysctl_size = *oldlenp; |
| 568 | error = sysctl_lookup(SYSCTLFN_CALL(&node)); |
| 569 | kmem_free(v, *oldlenp); |
| 570 | return error; |
| 571 | } |
| 572 | } |
| 573 | |