| 1 | /* $NetBSD: rndpseudo.c,v 1.35 2015/08/20 14:40:17 christos Exp $ */ |
| 2 | |
| 3 | /*- |
| 4 | * Copyright (c) 1997-2013 The NetBSD Foundation, Inc. |
| 5 | * All rights reserved. |
| 6 | * |
| 7 | * This code is derived from software contributed to The NetBSD Foundation |
| 8 | * by Michael Graff <explorer@flame.org>, Thor Lancelot Simon, and |
| 9 | * Taylor R. Campbell. |
| 10 | * |
| 11 | * Redistribution and use in source and binary forms, with or without |
| 12 | * modification, are permitted provided that the following conditions |
| 13 | * are met: |
| 14 | * 1. Redistributions of source code must retain the above copyright |
| 15 | * notice, this list of conditions and the following disclaimer. |
| 16 | * 2. Redistributions in binary form must reproduce the above copyright |
| 17 | * notice, this list of conditions and the following disclaimer in the |
| 18 | * documentation and/or other materials provided with the distribution. |
| 19 | * |
| 20 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
| 21 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
| 22 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 23 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
| 24 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 25 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 26 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 27 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 28 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 29 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 30 | * POSSIBILITY OF SUCH DAMAGE. |
| 31 | */ |
| 32 | |
| 33 | #include <sys/cdefs.h> |
| 34 | __KERNEL_RCSID(0, "$NetBSD: rndpseudo.c,v 1.35 2015/08/20 14:40:17 christos Exp $" ); |
| 35 | |
| 36 | #if defined(_KERNEL_OPT) |
| 37 | #include "opt_compat_netbsd.h" |
| 38 | #endif |
| 39 | |
| 40 | #include <sys/param.h> |
| 41 | #include <sys/atomic.h> |
| 42 | #include <sys/conf.h> |
| 43 | #include <sys/cprng.h> |
| 44 | #include <sys/cpu.h> |
| 45 | #include <sys/evcnt.h> |
| 46 | #include <sys/fcntl.h> |
| 47 | #include <sys/file.h> |
| 48 | #include <sys/filedesc.h> |
| 49 | #include <sys/ioctl.h> |
| 50 | #include <sys/kauth.h> |
| 51 | #include <sys/kernel.h> |
| 52 | #include <sys/kmem.h> |
| 53 | #include <sys/mutex.h> |
| 54 | #include <sys/percpu.h> |
| 55 | #include <sys/poll.h> |
| 56 | #include <sys/pool.h> |
| 57 | #include <sys/proc.h> |
| 58 | #include <sys/rnd.h> |
| 59 | #include <sys/rndpool.h> |
| 60 | #include <sys/rndsource.h> |
| 61 | #include <sys/select.h> |
| 62 | #include <sys/stat.h> |
| 63 | #include <sys/systm.h> |
| 64 | #include <sys/vnode.h> |
| 65 | |
| 66 | #include <dev/rnd_private.h> |
| 67 | |
| 68 | #include "ioconf.h" |
| 69 | |
| 70 | #if defined(__HAVE_CPU_COUNTER) |
| 71 | #include <machine/cpu_counter.h> |
| 72 | #endif |
| 73 | |
| 74 | #ifdef RND_DEBUG |
| 75 | #define DPRINTF(l,x) if (rnd_debug & (l)) printf x |
| 76 | #else |
| 77 | #define DPRINTF(l,x) |
| 78 | #endif |
| 79 | |
| 80 | /* |
| 81 | * list devices attached |
| 82 | */ |
| 83 | #if 0 |
| 84 | #define RND_VERBOSE |
| 85 | #endif |
| 86 | |
| 87 | /* |
| 88 | * The size of a temporary buffer for reading and writing entropy. |
| 89 | */ |
| 90 | #define RND_TEMP_BUFFER_SIZE 512 |
| 91 | |
| 92 | static pool_cache_t rnd_temp_buffer_cache __read_mostly; |
| 93 | |
| 94 | /* |
| 95 | * Per-open state -- a lazily initialized CPRNG. |
| 96 | */ |
| 97 | struct rnd_ctx { |
| 98 | struct cprng_strong *rc_cprng; |
| 99 | bool rc_hard; |
| 100 | }; |
| 101 | |
| 102 | static pool_cache_t rnd_ctx_cache __read_mostly; |
| 103 | |
| 104 | /* |
| 105 | * The per-CPU RNGs used for short requests |
| 106 | */ |
| 107 | static percpu_t *percpu_urandom_cprng __read_mostly; |
| 108 | |
| 109 | |
| 110 | dev_type_open(rndopen); |
| 111 | |
| 112 | const struct cdevsw rnd_cdevsw = { |
| 113 | .d_open = rndopen, |
| 114 | .d_close = noclose, |
| 115 | .d_read = noread, |
| 116 | .d_write = nowrite, |
| 117 | .d_ioctl = noioctl, |
| 118 | .d_stop = nostop, |
| 119 | .d_tty = notty, |
| 120 | .d_poll = nopoll, |
| 121 | .d_mmap = nommap, |
| 122 | .d_kqfilter = nokqfilter, |
| 123 | .d_discard = nodiscard, |
| 124 | .d_flag = D_OTHER | D_MPSAFE |
| 125 | }; |
| 126 | |
| 127 | static int rnd_read(struct file *, off_t *, struct uio *, kauth_cred_t, int); |
| 128 | static int rnd_write(struct file *, off_t *, struct uio *, kauth_cred_t, int); |
| 129 | static int rnd_ioctl(struct file *, u_long, void *); |
| 130 | static int rnd_poll(struct file *, int); |
| 131 | static int rnd_stat(struct file *, struct stat *); |
| 132 | static int rnd_close(struct file *); |
| 133 | static int rnd_kqfilter(struct file *, struct knote *); |
| 134 | |
| 135 | const struct fileops rnd_fileops = { |
| 136 | .fo_read = rnd_read, |
| 137 | .fo_write = rnd_write, |
| 138 | .fo_ioctl = rnd_ioctl, |
| 139 | .fo_fcntl = fnullop_fcntl, |
| 140 | .fo_poll = rnd_poll, |
| 141 | .fo_stat = rnd_stat, |
| 142 | .fo_close = rnd_close, |
| 143 | .fo_kqfilter = rnd_kqfilter, |
| 144 | .fo_restart = fnullop_restart |
| 145 | }; |
| 146 | |
| 147 | static struct evcnt rndpseudo_soft = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, |
| 148 | NULL, "rndpseudo" , "open soft" ); |
| 149 | static struct evcnt rndpseudo_hard = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, |
| 150 | NULL, "rndpseudo" , "open hard" ); |
| 151 | EVCNT_ATTACH_STATIC(rndpseudo_soft); |
| 152 | EVCNT_ATTACH_STATIC(rndpseudo_hard); |
| 153 | |
| 154 | /* |
| 155 | * Generate a 32-bit counter. |
| 156 | */ |
| 157 | static inline uint32_t |
| 158 | rndpseudo_counter(void) |
| 159 | { |
| 160 | struct bintime bt; |
| 161 | uint32_t ret; |
| 162 | |
| 163 | #if defined(__HAVE_CPU_COUNTER) |
| 164 | if (cpu_hascounter()) |
| 165 | return (cpu_counter32()); |
| 166 | #endif |
| 167 | |
| 168 | binuptime(&bt); |
| 169 | ret = bt.sec; |
| 170 | ret ^= bt.sec >> 32; |
| 171 | ret ^= bt.frac; |
| 172 | ret ^= bt.frac >> 32; |
| 173 | |
| 174 | return ret; |
| 175 | } |
| 176 | |
| 177 | /* |
| 178 | * Used by ioconf.c to attach the rnd pseudo-device. |
| 179 | * `Attach' the random device. We use the timing of this event as |
| 180 | * another potential source of initial entropy. |
| 181 | */ |
| 182 | void |
| 183 | rndattach(int num) |
| 184 | { |
| 185 | uint32_t c; |
| 186 | |
| 187 | /* Trap unwary players who don't call rnd_init() early. */ |
| 188 | KASSERT(rnd_ready); |
| 189 | |
| 190 | rnd_temp_buffer_cache = pool_cache_init(RND_TEMP_BUFFER_SIZE, 0, 0, 0, |
| 191 | "rndtemp" , NULL, IPL_NONE, NULL, NULL, NULL); |
| 192 | rnd_ctx_cache = pool_cache_init(sizeof(struct rnd_ctx), 0, 0, 0, |
| 193 | "rndctx" , NULL, IPL_NONE, NULL, NULL, NULL); |
| 194 | percpu_urandom_cprng = percpu_alloc(sizeof(struct cprng_strong *)); |
| 195 | |
| 196 | /* Mix in another counter. */ |
| 197 | c = rndpseudo_counter(); |
| 198 | rnd_add_data(NULL, &c, sizeof(c), 1); |
| 199 | } |
| 200 | |
| 201 | int |
| 202 | rndopen(dev_t dev, int flags, int fmt, struct lwp *l) |
| 203 | { |
| 204 | bool hard; |
| 205 | struct file *fp; |
| 206 | int fd; |
| 207 | int error; |
| 208 | |
| 209 | switch (minor(dev)) { |
| 210 | case RND_DEV_URANDOM: |
| 211 | hard = false; |
| 212 | rndpseudo_soft.ev_count++; |
| 213 | break; |
| 214 | |
| 215 | case RND_DEV_RANDOM: |
| 216 | hard = true; |
| 217 | rndpseudo_hard.ev_count++; |
| 218 | break; |
| 219 | |
| 220 | default: |
| 221 | return ENXIO; |
| 222 | } |
| 223 | |
| 224 | error = fd_allocfile(&fp, &fd); |
| 225 | if (error) |
| 226 | return error; |
| 227 | |
| 228 | /* |
| 229 | * Allocate a context, but don't create a CPRNG yet -- do that |
| 230 | * lazily because it consumes entropy from the system entropy |
| 231 | * pool, which (currently) has the effect of depleting it and |
| 232 | * causing readers from /dev/random to block. If this is |
| 233 | * /dev/urandom and the process is about to send only short |
| 234 | * reads to it, then we will be using a per-CPU CPRNG anyway. |
| 235 | */ |
| 236 | struct rnd_ctx *const ctx = pool_cache_get(rnd_ctx_cache, PR_WAITOK); |
| 237 | ctx->rc_cprng = NULL; |
| 238 | ctx->rc_hard = hard; |
| 239 | |
| 240 | error = fd_clone(fp, fd, flags, &rnd_fileops, ctx); |
| 241 | KASSERT(error == EMOVEFD); |
| 242 | |
| 243 | return error; |
| 244 | } |
| 245 | |
| 246 | /* |
| 247 | * Fetch a /dev/u?random context's CPRNG, or create and save one if |
| 248 | * necessary. |
| 249 | */ |
| 250 | static struct cprng_strong * |
| 251 | rnd_ctx_cprng(struct rnd_ctx *ctx) |
| 252 | { |
| 253 | struct cprng_strong *cprng, *tmp = NULL; |
| 254 | |
| 255 | /* Fast path: if someone has already allocated a CPRNG, use it. */ |
| 256 | cprng = ctx->rc_cprng; |
| 257 | if (__predict_true(cprng != NULL)) { |
| 258 | /* Make sure the CPU hasn't prefetched cprng's guts. */ |
| 259 | membar_consumer(); |
| 260 | goto out; |
| 261 | } |
| 262 | |
| 263 | /* Slow path: create a CPRNG. Allocate before taking locks. */ |
| 264 | char name[64]; |
| 265 | struct lwp *const l = curlwp; |
| 266 | (void)snprintf(name, sizeof(name), "%d %" PRIu64" %u" , |
| 267 | (int)l->l_proc->p_pid, l->l_ncsw, l->l_cpticks); |
| 268 | const int flags = (ctx->rc_hard? (CPRNG_USE_CV | CPRNG_HARD) : |
| 269 | (CPRNG_INIT_ANY | CPRNG_REKEY_ANY)); |
| 270 | tmp = cprng_strong_create(name, IPL_NONE, flags); |
| 271 | |
| 272 | /* Publish cprng's guts before the pointer to them. */ |
| 273 | membar_producer(); |
| 274 | |
| 275 | /* Attempt to publish tmp, unless someone beat us. */ |
| 276 | cprng = atomic_cas_ptr(&ctx->rc_cprng, NULL, tmp); |
| 277 | if (__predict_false(cprng != NULL)) { |
| 278 | /* Make sure the CPU hasn't prefetched cprng's guts. */ |
| 279 | membar_consumer(); |
| 280 | goto out; |
| 281 | } |
| 282 | |
| 283 | /* Published. Commit tmp. */ |
| 284 | cprng = tmp; |
| 285 | tmp = NULL; |
| 286 | |
| 287 | out: if (tmp != NULL) |
| 288 | cprng_strong_destroy(tmp); |
| 289 | KASSERT(cprng != NULL); |
| 290 | return cprng; |
| 291 | } |
| 292 | |
| 293 | /* |
| 294 | * Fetch a per-CPU CPRNG, or create and save one if necessary. |
| 295 | */ |
| 296 | static struct cprng_strong * |
| 297 | rnd_percpu_cprng(void) |
| 298 | { |
| 299 | struct cprng_strong **cprngp, *cprng, *tmp = NULL; |
| 300 | |
| 301 | /* Fast path: if there already is a CPRNG for this CPU, use it. */ |
| 302 | cprngp = percpu_getref(percpu_urandom_cprng); |
| 303 | cprng = *cprngp; |
| 304 | if (__predict_true(cprng != NULL)) |
| 305 | goto out; |
| 306 | percpu_putref(percpu_urandom_cprng); |
| 307 | |
| 308 | /* |
| 309 | * Slow path: create a CPRNG named by this CPU. |
| 310 | * |
| 311 | * XXX The CPU of the name may be different from the CPU to |
| 312 | * which it is assigned, because we need to choose a name and |
| 313 | * allocate a cprng while preemption is enabled. This could be |
| 314 | * fixed by changing the cprng_strong API (e.g., by adding a |
| 315 | * cprng_strong_setname or by separating allocation from |
| 316 | * initialization), but it's not clear that's worth the |
| 317 | * trouble. |
| 318 | */ |
| 319 | char name[32]; |
| 320 | (void)snprintf(name, sizeof(name), "urandom%u" , cpu_index(curcpu())); |
| 321 | tmp = cprng_strong_create(name, IPL_NONE, |
| 322 | (CPRNG_INIT_ANY | CPRNG_REKEY_ANY)); |
| 323 | |
| 324 | /* Try again, but we may have been preempted and lost a race. */ |
| 325 | cprngp = percpu_getref(percpu_urandom_cprng); |
| 326 | cprng = *cprngp; |
| 327 | if (__predict_false(cprng != NULL)) |
| 328 | goto out; |
| 329 | |
| 330 | /* Commit the CPRNG we just created. */ |
| 331 | cprng = tmp; |
| 332 | tmp = NULL; |
| 333 | *cprngp = cprng; |
| 334 | |
| 335 | out: percpu_putref(percpu_urandom_cprng); |
| 336 | if (tmp != NULL) |
| 337 | cprng_strong_destroy(tmp); |
| 338 | KASSERT(cprng != NULL); |
| 339 | return cprng; |
| 340 | } |
| 341 | |
| 342 | static int |
| 343 | rnd_read(struct file *fp, off_t *offp, struct uio *uio, kauth_cred_t cred, |
| 344 | int flags) |
| 345 | { |
| 346 | int error = 0; |
| 347 | |
| 348 | DPRINTF(RND_DEBUG_READ, |
| 349 | ("Random: Read of %zu requested, flags 0x%08x\n" , |
| 350 | uio->uio_resid, flags)); |
| 351 | |
| 352 | if (uio->uio_resid == 0) |
| 353 | return 0; |
| 354 | |
| 355 | struct rnd_ctx *const ctx = fp->f_rndctx; |
| 356 | uint8_t *const buf = pool_cache_get(rnd_temp_buffer_cache, PR_WAITOK); |
| 357 | |
| 358 | /* |
| 359 | * Choose a CPRNG to use -- either the per-open CPRNG, if this |
| 360 | * is /dev/random or a long read, or the per-CPU one otherwise. |
| 361 | * |
| 362 | * XXX NIST_BLOCK_KEYLEN_BYTES is a detail of the cprng(9) |
| 363 | * implementation and as such should not be mentioned here. |
| 364 | */ |
| 365 | struct cprng_strong *const cprng = |
| 366 | ((ctx->rc_hard || (uio->uio_resid > NIST_BLOCK_KEYLEN_BYTES))? |
| 367 | rnd_ctx_cprng(ctx) : rnd_percpu_cprng()); |
| 368 | |
| 369 | /* |
| 370 | * Generate the data in RND_TEMP_BUFFER_SIZE chunks. |
| 371 | */ |
| 372 | while (uio->uio_resid > 0) { |
| 373 | const size_t n_req = MIN(uio->uio_resid, RND_TEMP_BUFFER_SIZE); |
| 374 | |
| 375 | CTASSERT(RND_TEMP_BUFFER_SIZE <= CPRNG_MAX_LEN); |
| 376 | const size_t n_read = cprng_strong(cprng, buf, n_req, |
| 377 | ((ctx->rc_hard && ISSET(fp->f_flag, FNONBLOCK))? |
| 378 | FNONBLOCK : 0)); |
| 379 | |
| 380 | /* |
| 381 | * Equality will hold unless this is /dev/random, in |
| 382 | * which case we get only as many bytes as are left |
| 383 | * from the CPRNG's `information-theoretic strength' |
| 384 | * since the last rekey. |
| 385 | */ |
| 386 | KASSERT(n_read <= n_req); |
| 387 | KASSERT(ctx->rc_hard || (n_read == n_req)); |
| 388 | |
| 389 | error = uiomove(buf, n_read, uio); |
| 390 | if (error) |
| 391 | goto out; |
| 392 | |
| 393 | /* |
| 394 | * For /dev/urandom: Reads always succeed in full, no |
| 395 | * matter how many iterations that takes. (XXX But |
| 396 | * this means the computation can't be interrupted, |
| 397 | * wihch seems suboptimal.) |
| 398 | * |
| 399 | * For /dev/random, nonblocking: Reads succeed with as |
| 400 | * many bytes as a single request can return without |
| 401 | * blocking, or fail with EAGAIN if a request would |
| 402 | * block. (There is no sense in trying multiple |
| 403 | * requests because if the first one didn't fill the |
| 404 | * buffer, the second one would almost certainly |
| 405 | * block.) |
| 406 | * |
| 407 | * For /dev/random, blocking: Reads succeed with as |
| 408 | * many bytes as a single request -- which may block -- |
| 409 | * can return if uninterrupted, or fail with EINTR if |
| 410 | * the request is interrupted. |
| 411 | */ |
| 412 | KASSERT((0 < n_read) || ctx->rc_hard); |
| 413 | if (ctx->rc_hard) { |
| 414 | if (0 < n_read) |
| 415 | error = 0; |
| 416 | else if (ISSET(fp->f_flag, FNONBLOCK)) |
| 417 | error = EAGAIN; |
| 418 | else |
| 419 | error = EINTR; |
| 420 | goto out; |
| 421 | } |
| 422 | } |
| 423 | |
| 424 | out: pool_cache_put(rnd_temp_buffer_cache, buf); |
| 425 | return error; |
| 426 | } |
| 427 | |
| 428 | static int |
| 429 | rnd_write(struct file *fp, off_t *offp, struct uio *uio, |
| 430 | kauth_cred_t cred, int flags) |
| 431 | { |
| 432 | uint8_t *bf; |
| 433 | int n, ret = 0, estimate_ok = 0, estimate = 0, added = 0; |
| 434 | |
| 435 | ret = kauth_authorize_device(cred, |
| 436 | KAUTH_DEVICE_RND_ADDDATA, NULL, NULL, NULL, NULL); |
| 437 | if (ret) { |
| 438 | return (ret); |
| 439 | } |
| 440 | estimate_ok = !kauth_authorize_device(cred, |
| 441 | KAUTH_DEVICE_RND_ADDDATA_ESTIMATE, NULL, NULL, NULL, NULL); |
| 442 | |
| 443 | DPRINTF(RND_DEBUG_WRITE, |
| 444 | ("Random: Write of %zu requested\n" , uio->uio_resid)); |
| 445 | |
| 446 | if (uio->uio_resid == 0) |
| 447 | return (0); |
| 448 | ret = 0; |
| 449 | bf = pool_cache_get(rnd_temp_buffer_cache, PR_WAITOK); |
| 450 | while (uio->uio_resid > 0) { |
| 451 | /* |
| 452 | * Don't flood the pool. |
| 453 | */ |
| 454 | if (added > RND_POOLWORDS * sizeof(int)) { |
| 455 | #ifdef RND_VERBOSE |
| 456 | printf("rnd: added %d already, adding no more.\n" , |
| 457 | added); |
| 458 | #endif |
| 459 | break; |
| 460 | } |
| 461 | n = min(RND_TEMP_BUFFER_SIZE, uio->uio_resid); |
| 462 | |
| 463 | ret = uiomove((void *)bf, n, uio); |
| 464 | if (ret != 0) |
| 465 | break; |
| 466 | |
| 467 | if (estimate_ok) { |
| 468 | /* |
| 469 | * Don't cause samples to be discarded by taking |
| 470 | * the pool's entropy estimate to the max. |
| 471 | */ |
| 472 | if (added > RND_POOLWORDS / 2) |
| 473 | estimate = 0; |
| 474 | else |
| 475 | estimate = n * NBBY / 2; |
| 476 | #ifdef RND_VERBOSE |
| 477 | printf("rnd: adding on write, %d bytes, estimate %d\n" , |
| 478 | n, estimate); |
| 479 | #endif |
| 480 | } else { |
| 481 | #ifdef RND_VERBOSE |
| 482 | printf("rnd: kauth says no entropy.\n" ); |
| 483 | #endif |
| 484 | } |
| 485 | |
| 486 | /* |
| 487 | * Mix in the bytes. |
| 488 | */ |
| 489 | rnd_add_data(NULL, bf, n, estimate); |
| 490 | |
| 491 | added += n; |
| 492 | DPRINTF(RND_DEBUG_WRITE, ("Random: Copied in %d bytes\n" , n)); |
| 493 | } |
| 494 | pool_cache_put(rnd_temp_buffer_cache, bf); |
| 495 | return (ret); |
| 496 | } |
| 497 | |
| 498 | int |
| 499 | rnd_ioctl(struct file *fp, u_long cmd, void *addr) |
| 500 | { |
| 501 | |
| 502 | switch (cmd) { |
| 503 | case FIONBIO: |
| 504 | case FIOASYNC: |
| 505 | return 0; |
| 506 | default: |
| 507 | return rnd_system_ioctl(fp, cmd, addr); |
| 508 | } |
| 509 | } |
| 510 | |
| 511 | static int |
| 512 | rnd_poll(struct file *fp, int events) |
| 513 | { |
| 514 | struct rnd_ctx *const ctx = fp->f_rndctx; |
| 515 | int revents; |
| 516 | |
| 517 | /* |
| 518 | * We are always writable. |
| 519 | */ |
| 520 | revents = events & (POLLOUT | POLLWRNORM); |
| 521 | |
| 522 | /* |
| 523 | * Save some work if not checking for reads. |
| 524 | */ |
| 525 | if ((events & (POLLIN | POLLRDNORM)) == 0) |
| 526 | return revents; |
| 527 | |
| 528 | /* |
| 529 | * For /dev/random, ask the CPRNG, which may require creating |
| 530 | * one. For /dev/urandom, we're always readable. |
| 531 | */ |
| 532 | if (ctx->rc_hard) |
| 533 | revents |= cprng_strong_poll(rnd_ctx_cprng(ctx), events); |
| 534 | else |
| 535 | revents |= (events & (POLLIN | POLLRDNORM)); |
| 536 | |
| 537 | return revents; |
| 538 | } |
| 539 | |
| 540 | static int |
| 541 | rnd_stat(struct file *fp, struct stat *st) |
| 542 | { |
| 543 | struct rnd_ctx *const ctx = fp->f_rndctx; |
| 544 | |
| 545 | /* XXX lock, if cprng allocated? why? */ |
| 546 | memset(st, 0, sizeof(*st)); |
| 547 | st->st_dev = makedev(cdevsw_lookup_major(&rnd_cdevsw), |
| 548 | (ctx->rc_hard? RND_DEV_RANDOM : RND_DEV_URANDOM)); |
| 549 | /* XXX leave atimespect, mtimespec, ctimespec = 0? */ |
| 550 | |
| 551 | st->st_uid = kauth_cred_geteuid(fp->f_cred); |
| 552 | st->st_gid = kauth_cred_getegid(fp->f_cred); |
| 553 | st->st_mode = S_IFCHR; |
| 554 | return 0; |
| 555 | } |
| 556 | |
| 557 | static int |
| 558 | rnd_close(struct file *fp) |
| 559 | { |
| 560 | struct rnd_ctx *const ctx = fp->f_rndctx; |
| 561 | |
| 562 | if (ctx->rc_cprng != NULL) |
| 563 | cprng_strong_destroy(ctx->rc_cprng); |
| 564 | fp->f_rndctx = NULL; |
| 565 | pool_cache_put(rnd_ctx_cache, ctx); |
| 566 | |
| 567 | return 0; |
| 568 | } |
| 569 | |
| 570 | static int |
| 571 | rnd_kqfilter(struct file *fp, struct knote *kn) |
| 572 | { |
| 573 | struct rnd_ctx *const ctx = fp->f_rndctx; |
| 574 | |
| 575 | return cprng_strong_kqfilter(rnd_ctx_cprng(ctx), kn); |
| 576 | } |
| 577 | |