crypto/rand/rand_unix.c

   1 /*
   2  * Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #ifndef _GNU_SOURCE
  11 # define _GNU_SOURCE
  12 #endif
  13 #include "e_os.h"
  14 #include <stdio.h>
  15 #include "internal/cryptlib.h"
  16 #include <openssl/rand.h>
  17 #include <openssl/crypto.h>
  18 #include "rand_local.h"
  19 #include "crypto/rand.h"
  20 #include <stdio.h>
  21 #include "internal/dso.h"
  22 #ifdef __linux
  23 # include <sys/syscall.h>
  24 # ifdef DEVRANDOM_WAIT
  25 #  include <sys/shm.h>
  26 #  include <sys/utsname.h>
  27 # endif
  28 #endif
  29 #if defined(__FreeBSD__) && !defined(OPENSSL_SYS_UEFI)
  30 # include <sys/types.h>
  31 # include <sys/sysctl.h>
  32 # include <sys/param.h>
  33 #endif
  34 #if defined(__OpenBSD__) || defined(__NetBSD__)
  35 # include <sys/param.h>
  36 #endif
  37
  38 #if defined(OPENSSL_SYS_UNIX) || defined(__DJGPP__)
  39 # include <sys/types.h>
  40 # include <sys/stat.h>
  41 # include <fcntl.h>
  42 # include <unistd.h>
  43 # include <sys/time.h>
  44
  45 static uint64_t get_time_stamp(void);
  46 static uint64_t get_timer_bits(void);
  47
  48 /* Macro to convert two thirty two bit values into a sixty four bit one */
  49 # define TWO32TO64(a, b) ((((uint64_t)(a)) << 32) + (b))
  50
  51 /*
  52  * Check for the existence and support of POSIX timers.  The standard
  53  * says that the _POSIX_TIMERS macro will have a positive value if they
  54  * are available.
  55  *
  56  * However, we want an additional constraint: that the timer support does
  57  * not require an extra library dependency.  Early versions of glibc
  58  * require -lrt to be specified on the link line to access the timers,
  59  * so this needs to be checked for.
  60  *
  61  * It is worse because some libraries define __GLIBC__ but don't
  62  * support the version testing macro (e.g. uClibc).  This means
  63  * an extra check is needed.
  64  *
  65  * The final condition is:
  66  *      "have posix timers and either not glibc or glibc without -lrt"
  67  *
  68  * The nested #if sequences are required to avoid using a parameterised
  69  * macro that might be undefined.
  70  */
  71 # undef OSSL_POSIX_TIMER_OKAY
  72 # if defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0
  73 #  if defined(__GLIBC__)
  74 #   if defined(__GLIBC_PREREQ)
  75 #    if __GLIBC_PREREQ(2, 17)
  76 #     define OSSL_POSIX_TIMER_OKAY
  77 #    endif
  78 #   endif
  79 #  else
  80 #   define OSSL_POSIX_TIMER_OKAY
  81 #  endif
  82 # endif
  83 #endif /* (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS))
  84           || defined(__DJGPP__) */
  85
  86 #if defined(OPENSSL_RAND_SEED_NONE)
  87 /* none means none. this simplifies the following logic */
  88 # undef OPENSSL_RAND_SEED_OS
  89 # undef OPENSSL_RAND_SEED_GETRANDOM
  90 # undef OPENSSL_RAND_SEED_LIBRANDOM
  91 # undef OPENSSL_RAND_SEED_DEVRANDOM
  92 # undef OPENSSL_RAND_SEED_RDTSC
  93 # undef OPENSSL_RAND_SEED_RDCPU
  94 # undef OPENSSL_RAND_SEED_EGD
  95 #endif
  96
  97 #if (defined(OPENSSL_SYS_VXWORKS) || defined(OPENSSL_SYS_UEFI)) && \
  98         !defined(OPENSSL_RAND_SEED_NONE)
  99 # error "UEFI and VXWorks only support seeding NONE"
 100 #endif
 101
 102 #if defined(OPENSSL_SYS_VXWORKS)
 103 /* empty implementation */
 104 int rand_pool_init(void)
 105 {
 106     return 1;
 107 }
 108
 109 void rand_pool_cleanup(void)
 110 {
 111 }
 112
 113 void rand_pool_keep_random_devices_open(int keep)
 114 {
 115 }
 116
 117 size_t rand_pool_acquire_entropy(RAND_POOL *pool)
 118 {
 119     return rand_pool_entropy_available(pool);
 120 }
 121 #endif
 122
 123 #if !(defined(OPENSSL_SYS_WINDOWS) || defined(OPENSSL_SYS_WIN32) \
 124     || defined(OPENSSL_SYS_VMS) || defined(OPENSSL_SYS_VXWORKS) \
 125     || defined(OPENSSL_SYS_UEFI))
 126
 127 # if defined(OPENSSL_SYS_VOS)
 128
 129 #  ifndef OPENSSL_RAND_SEED_OS
 130 #   error "Unsupported seeding method configured; must be os"
 131 #  endif
 132
 133 #  if defined(OPENSSL_SYS_VOS_HPPA) && defined(OPENSSL_SYS_VOS_IA32)
 134 #   error "Unsupported HP-PA and IA32 at the same time."
 135 #  endif
 136 #  if !defined(OPENSSL_SYS_VOS_HPPA) && !defined(OPENSSL_SYS_VOS_IA32)
 137 #   error "Must have one of HP-PA or IA32"
 138 #  endif
 139
 140 /*
 141  * The following algorithm repeatedly samples the real-time clock (RTC) to
 142  * generate a sequence of unpredictable data.  The algorithm relies upon the
 143  * uneven execution speed of the code (due to factors such as cache misses,
 144  * interrupts, bus activity, and scheduling) and upon the rather large
 145  * relative difference between the speed of the clock and the rate at which
 146  * it can be read.  If it is ported to an environment where execution speed
 147  * is more constant or where the RTC ticks at a much slower rate, or the
 148  * clock can be read with fewer instructions, it is likely that the results
 149  * would be far more predictable.  This should only be used for legacy
 150  * platforms.
 151  *
 152  * As a precaution, we assume only 2 bits of entropy per byte.
 153  */
 154 size_t rand_pool_acquire_entropy(RAND_POOL *pool)
 155 {
 156     short int code;
 157     int i, k;
 158     size_t bytes_needed;
 159     struct timespec ts;
 160     unsigned char v;
 161 #  ifdef OPENSSL_SYS_VOS_HPPA
 162     long duration;
 163     extern void s$sleep(long *_duration, short int *_code);
 164 #  else
 165     long long duration;
 166     extern void s$sleep2(long long *_duration, short int *_code);
 167 #  endif
 168
 169     bytes_needed = rand_pool_bytes_needed(pool, 4 /*entropy_factor*/);
 170
 171     for (i = 0; i < bytes_needed; i++) {
 172         /*
 173          * burn some cpu; hope for interrupts, cache collisions, bus
 174          * interference, etc.
 175          */
 176         for (k = 0; k < 99; k++)
 177             ts.tv_nsec = random();
 178
 179 #  ifdef OPENSSL_SYS_VOS_HPPA
 180         /* sleep for 1/1024 of a second (976 us).  */
 181         duration = 1;
 182         s$sleep(&duration, &code);
 183 #  else
 184         /* sleep for 1/65536 of a second (15 us).  */
 185         duration = 1;
 186         s$sleep2(&duration, &code);
 187 #  endif
 188
 189         /* Get wall clock time, take 8 bits. */
 190         clock_gettime(CLOCK_REALTIME, &ts);
 191         v = (unsigned char)(ts.tv_nsec & 0xFF);
 192         rand_pool_add(pool, arg, &v, sizeof(v) , 2);
 193     }
 194     return rand_pool_entropy_available(pool);
 195 }
 196
 197 void rand_pool_cleanup(void)
 198 {
 199 }
 200
 201 void rand_pool_keep_random_devices_open(int keep)
 202 {
 203 }
 204
 205 # else
 206
 207 #  if defined(OPENSSL_RAND_SEED_EGD) && \
 208         (defined(OPENSSL_NO_EGD) || !defined(DEVRANDOM_EGD))
 209 #   error "Seeding uses EGD but EGD is turned off or no device given"
 210 #  endif
 211
 212 #  if defined(OPENSSL_RAND_SEED_DEVRANDOM) && !defined(DEVRANDOM)
 213 #   error "Seeding uses urandom but DEVRANDOM is not configured"
 214 #  endif
 215
 216 #  if defined(OPENSSL_RAND_SEED_OS)
 217 #   if !defined(DEVRANDOM)
 218 #    error "OS seeding requires DEVRANDOM to be configured"
 219 #   endif
 220 #   define OPENSSL_RAND_SEED_GETRANDOM
 221 #   define OPENSSL_RAND_SEED_DEVRANDOM
 222 #  endif
 223
 224 #  if defined(OPENSSL_RAND_SEED_LIBRANDOM)
 225 #   error "librandom not (yet) supported"
 226 #  endif
 227
 228 #  if (defined(__FreeBSD__) || defined(__NetBSD__)) && defined(KERN_ARND)
 229 /*
 230  * sysctl_random(): Use sysctl() to read a random number from the kernel
 231  * Returns the number of bytes returned in buf on success, -1 on failure.
 232  */
 233 static ssize_t sysctl_random(char *buf, size_t buflen)
 234 {
 235     int mib[2];
 236     size_t done = 0;
 237     size_t len;
 238
 239     /*
 240      * Note: sign conversion between size_t and ssize_t is safe even
 241      * without a range check, see comment in syscall_random()
 242      */
 243
 244     /*
 245      * On FreeBSD old implementations returned longs, newer versions support
 246      * variable sizes up to 256 byte. The code below would not work properly
 247      * when the sysctl returns long and we want to request something not a
 248      * multiple of longs, which should never be the case.
 249      */
 250     if (!ossl_assert(buflen % sizeof(long) == 0)) {
 251         errno = EINVAL;
 252         return -1;
 253     }
 254
 255     /*
 256      * On NetBSD before 4.0 KERN_ARND was an alias for KERN_URND, and only
 257      * filled in an int, leaving the rest uninitialized. Since NetBSD 4.0
 258      * it returns a variable number of bytes with the current version supporting
 259      * up to 256 bytes.
 260      * Just return an error on older NetBSD versions.
 261      */
 262 #if   defined(__NetBSD__) && __NetBSD_Version__ < 400000000
 263     errno = ENOSYS;
 264     return -1;
 265 #endif
 266
 267     mib[0] = CTL_KERN;
 268     mib[1] = KERN_ARND;
 269
 270     do {
 271         len = buflen;
 272         if (sysctl(mib, 2, buf, &len, NULL, 0) == -1)
 273             return done > 0 ? done : -1;
 274         done += len;
 275         buf += len;
 276         buflen -= len;
 277     } while (buflen > 0);
 278
 279     return done;
 280 }
 281 #  endif
 282
 283 #  if defined(OPENSSL_RAND_SEED_GETRANDOM)
 284
 285 #   if defined(__linux) && !defined(__NR_getrandom)
 286 #    if defined(__arm__)
 287 #     define __NR_getrandom    (__NR_SYSCALL_BASE+384)
 288 #    elif defined(__i386__)
 289 #     define __NR_getrandom    355
 290 #    elif defined(__x86_64__)
 291 #     if defined(__ILP32__)
 292 #      define __NR_getrandom   (__X32_SYSCALL_BIT + 318)
 293 #     else
 294 #      define __NR_getrandom   318
 295 #     endif
 296 #    elif defined(__xtensa__)
 297 #     define __NR_getrandom    338
 298 #    elif defined(__s390__) || defined(__s390x__)
 299 #     define __NR_getrandom    349
 300 #    elif defined(__bfin__)
 301 #     define __NR_getrandom    389
 302 #    elif defined(__powerpc__)
 303 #     define __NR_getrandom    359
 304 #    elif defined(__mips__) || defined(__mips64)
 305 #     if _MIPS_SIM == _MIPS_SIM_ABI32
 306 #      define __NR_getrandom   (__NR_Linux + 353)
 307 #     elif _MIPS_SIM == _MIPS_SIM_ABI64
 308 #      define __NR_getrandom   (__NR_Linux + 313)
 309 #     elif _MIPS_SIM == _MIPS_SIM_NABI32
 310 #      define __NR_getrandom   (__NR_Linux + 317)
 311 #     endif
 312 #    elif defined(__hppa__)
 313 #     define __NR_getrandom    (__NR_Linux + 339)
 314 #    elif defined(__sparc__)
 315 #     define __NR_getrandom    347
 316 #    elif defined(__ia64__)
 317 #     define __NR_getrandom    1339
 318 #    elif defined(__alpha__)
 319 #     define __NR_getrandom    511
 320 #    elif defined(__sh__)
 321 #     if defined(__SH5__)
 322 #      define __NR_getrandom   373
 323 #     else
 324 #      define __NR_getrandom   384
 325 #     endif
 326 #    elif defined(__avr32__)
 327 #     define __NR_getrandom    317
 328 #    elif defined(__microblaze__)
 329 #     define __NR_getrandom    385
 330 #    elif defined(__m68k__)
 331 #     define __NR_getrandom    352
 332 #    elif defined(__cris__)
 333 #     define __NR_getrandom    356
 334 #    elif defined(__aarch64__)
 335 #     define __NR_getrandom    278
 336 #    else /* generic */
 337 #     define __NR_getrandom    278
 338 #    endif
 339 #   endif
 340
 341 /*
 342  * syscall_random(): Try to get random data using a system call
 343  * returns the number of bytes returned in buf, or < 0 on error.
 344  */
 345 static ssize_t syscall_random(void *buf, size_t buflen)
 346 {
 347     /*
 348      * Note: 'buflen' equals the size of the buffer which is used by the
 349      * get_entropy() callback of the RAND_DRBG. It is roughly bounded by
 350      *
 351      *   2 * RAND_POOL_FACTOR * (RAND_DRBG_STRENGTH / 8) = 2^14
 352      *
 353      * which is way below the OSSL_SSIZE_MAX limit. Therefore sign conversion
 354      * between size_t and ssize_t is safe even without a range check.
 355      */
 356
 357     /*
 358      * Do runtime detection to find getentropy().
 359      *
 360      * Known OSs that should support this:
 361      * - Darwin since 16 (OSX 10.12, IOS 10.0).
 362      * - Solaris since 11.3
 363      * - OpenBSD since 5.6
 364      * - Linux since 3.17 with glibc 2.25
 365      * - FreeBSD since 12.0 (1200061)
 366      */
 367 #  if defined(__GNUC__) && __GNUC__>=2 && defined(__ELF__) && !defined(__hpux)
 368     extern int getentropy(void *buffer, size_t length) __attribute__((weak));
 369
 370     if (getentropy != NULL)
 371         return getentropy(buf, buflen) == 0 ? (ssize_t)buflen : -1;
 372 #  else
 373     union {
 374         void *p;
 375         int (*f)(void *buffer, size_t length);
 376     } p_getentropy;
 377
 378     /*
 379      * We could cache the result of the lookup, but we normally don't
 380      * call this function often.
 381      */
 382     ERR_set_mark();
 383     p_getentropy.p = DSO_global_lookup("getentropy");
 384     ERR_pop_to_mark();
 385     if (p_getentropy.p != NULL)
 386         return p_getentropy.f(buf, buflen) == 0 ? (ssize_t)buflen : -1;
 387 #  endif
 388
 389     /* Linux supports this since version 3.17 */
 390 #  if defined(__linux) && defined(__NR_getrandom)
 391     return syscall(__NR_getrandom, buf, buflen, 0);
 392 #  elif (defined(__FreeBSD__) || defined(__NetBSD__)) && defined(KERN_ARND)
 393     return sysctl_random(buf, buflen);
 394 #  else
 395     errno = ENOSYS;
 396     return -1;
 397 #  endif
 398 }
 399 #  endif    /* defined(OPENSSL_RAND_SEED_GETRANDOM) */
 400
 401 #  if defined(OPENSSL_RAND_SEED_DEVRANDOM)
 402 static const char *random_device_paths[] = { DEVRANDOM };
 403 static struct random_device {
 404     int fd;
 405     dev_t dev;
 406     ino_t ino;
 407     mode_t mode;
 408     dev_t rdev;
 409 } random_devices[OSSL_NELEM(random_device_paths)];
 410 static int keep_random_devices_open = 1;
 411
 412 #   if defined(__linux) && defined(DEVRANDOM_WAIT)
 413 static void *shm_addr;
 414
 415 static void cleanup_shm(void)
 416 {
 417     shmdt(shm_addr);
 418 }
 419
 420 /*
 421  * Ensure that the system randomness source has been adequately seeded.
 422  * This is done by having the first start of libcrypto, wait until the device
 423  * /dev/random becomes able to supply a byte of entropy.  Subsequent starts
 424  * of the library and later reseedings do not need to do this.
 425  */
 426 static int wait_random_seeded(void)
 427 {
 428     static int seeded = OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID < 0;
 429     static const int kernel_version[] = { DEVRANDOM_SAFE_KERNEL };
 430     int kernel[2];
 431     int shm_id, fd, r;
 432     char c, *p;
 433     struct utsname un;
 434     fd_set fds;
 435
 436     if (!seeded) {
 437         /* See if anything has created the global seeded indication */
 438         if ((shm_id = shmget(OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID, 1, 0)) == -1) {
 439             /*
 440              * Check the kernel's version and fail if it is too recent.
 441              *
 442              * Linux kernels from 4.8 onwards do not guarantee that
 443              * /dev/urandom is properly seeded when /dev/random becomes
 444              * readable.  However, such kernels support the getentropy(2)
 445              * system call and this should always succeed which renders
 446              * this alternative but essentially identical source moot.
 447              */
 448             if (uname(&un) == 0) {
 449                 kernel[0] = atoi(un.release);
 450                 p = strchr(un.release, '.');
 451                 kernel[1] = p == NULL ? 0 : atoi(p + 1);
 452                 if (kernel[0] > kernel_version[0]
 453                     || (kernel[0] == kernel_version[0]
 454                         && kernel[1] >= kernel_version[1])) {
 455                     return 0;
 456                 }
 457             }
 458             /* Open /dev/random and wait for it to be readable */
 459             if ((fd = open(DEVRANDOM_WAIT, O_RDONLY)) != -1) {
 460                 if (DEVRANDM_WAIT_USE_SELECT && fd < FD_SETSIZE) {
 461                     FD_ZERO(&fds);
 462                     FD_SET(fd, &fds);
 463                     while ((r = select(fd + 1, &fds, NULL, NULL, NULL)) < 0
 464                            && errno == EINTR);
 465                 } else {
 466                     while ((r = read(fd, &c, 1)) < 0 && errno == EINTR);
 467                 }
 468                 close(fd);
 469                 if (r == 1) {
 470                     seeded = 1;
 471                     /* Create the shared memory indicator */
 472                     shm_id = shmget(OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID, 1,
 473                                     IPC_CREAT | S_IRUSR | S_IRGRP | S_IROTH);
 474                 }
 475             }
 476         }
 477         if (shm_id != -1) {
 478             seeded = 1;
 479             /*
 480              * Map the shared memory to prevent its premature destruction.
 481              * If this call fails, it isn't a big problem.
 482              */
 483             shm_addr = shmat(shm_id, NULL, SHM_RDONLY);
 484             if (shm_addr != (void *)-1)
 485                 OPENSSL_atexit(&cleanup_shm);
 486         }
 487     }
 488     return seeded;
 489 }
 490 #   else /* defined __linux */
 491 static int wait_random_seeded(void)
 492 {
 493     return 1;
 494 }
 495 #   endif
 496
 497 /*
 498  * Verify that the file descriptor associated with the random source is
 499  * still valid. The rationale for doing this is the fact that it is not
 500  * uncommon for daemons to close all open file handles when daemonizing.
 501  * So the handle might have been closed or even reused for opening
 502  * another file.
 503  */
 504 static int check_random_device(struct random_device * rd)
 505 {
 506     struct stat st;
 507
 508     return rd->fd != -1
 509            && fstat(rd->fd, &st) != -1
 510            && rd->dev == st.st_dev
 511            && rd->ino == st.st_ino
 512            && ((rd->mode ^ st.st_mode) & ~(S_IRWXU | S_IRWXG | S_IRWXO)) == 0
 513            && rd->rdev == st.st_rdev;
 514 }
 515
 516 /*
 517  * Open a random device if required and return its file descriptor or -1 on error
 518  */
 519 static int get_random_device(size_t n)
 520 {
 521     struct stat st;
 522     struct random_device * rd = &random_devices[n];
 523
 524     /* reuse existing file descriptor if it is (still) valid */
 525     if (check_random_device(rd))
 526         return rd->fd;
 527
 528     /* open the random device ... */
 529     if ((rd->fd = open(random_device_paths[n], O_RDONLY)) == -1)
 530         return rd->fd;
 531
 532     /* ... and cache its relevant stat(2) data */
 533     if (fstat(rd->fd, &st) != -1) {
 534         rd->dev = st.st_dev;
 535         rd->ino = st.st_ino;
 536         rd->mode = st.st_mode;
 537         rd->rdev = st.st_rdev;
 538     } else {
 539         close(rd->fd);
 540         rd->fd = -1;
 541     }
 542
 543     return rd->fd;
 544 }
 545
 546 /*
 547  * Close a random device making sure it is a random device
 548  */
 549 static void close_random_device(size_t n)
 550 {
 551     struct random_device * rd = &random_devices[n];
 552
 553     if (check_random_device(rd))
 554         close(rd->fd);
 555     rd->fd = -1;
 556 }
 557
 558 int rand_pool_init(void)
 559 {
 560     size_t i;
 561
 562     for (i = 0; i < OSSL_NELEM(random_devices); i++)
 563         random_devices[i].fd = -1;
 564
 565     return 1;
 566 }
 567
 568 void rand_pool_cleanup(void)
 569 {
 570     size_t i;
 571
 572     for (i = 0; i < OSSL_NELEM(random_devices); i++)
 573         close_random_device(i);
 574 }
 575
 576 void rand_pool_keep_random_devices_open(int keep)
 577 {
 578     if (!keep)
 579         rand_pool_cleanup();
 580
 581     keep_random_devices_open = keep;
 582 }
 583
 584 #  else     /* !defined(OPENSSL_RAND_SEED_DEVRANDOM) */
 585
 586 int rand_pool_init(void)
 587 {
 588     return 1;
 589 }
 590
 591 void rand_pool_cleanup(void)
 592 {
 593 }
 594
 595 void rand_pool_keep_random_devices_open(int keep)
 596 {
 597 }
 598
 599 #  endif    /* defined(OPENSSL_RAND_SEED_DEVRANDOM) */
 600
 601 /*
 602  * Try the various seeding methods in turn, exit when successful.
 603  *
 604  * TODO(DRBG): If more than one entropy source is available, is it
 605  * preferable to stop as soon as enough entropy has been collected
 606  * (as favored by @rsalz) or should one rather be defensive and add
 607  * more entropy than requested and/or from different sources?
 608  *
 609  * Currently, the user can select multiple entropy sources in the
 610  * configure step, yet in practice only the first available source
 611  * will be used. A more flexible solution has been requested, but
 612  * currently it is not clear how this can be achieved without
 613  * overengineering the problem. There are many parameters which
 614  * could be taken into account when selecting the order and amount
 615  * of input from the different entropy sources (trust, quality,
 616  * possibility of blocking).
 617  */
 618 size_t rand_pool_acquire_entropy(RAND_POOL *pool)
 619 {
 620 #  if defined(OPENSSL_RAND_SEED_NONE)
 621     return rand_pool_entropy_available(pool);
 622 #  else
 623     size_t entropy_available;
 624
 625 #   if defined(OPENSSL_RAND_SEED_GETRANDOM)
 626     {
 627         size_t bytes_needed;
 628         unsigned char *buffer;
 629         ssize_t bytes;
 630         /* Maximum allowed number of consecutive unsuccessful attempts */
 631         int attempts = 3;
 632
 633         bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
 634         while (bytes_needed != 0 && attempts-- > 0) {
 635             buffer = rand_pool_add_begin(pool, bytes_needed);
 636             bytes = syscall_random(buffer, bytes_needed);
 637             if (bytes > 0) {
 638                 rand_pool_add_end(pool, bytes, 8 * bytes);
 639                 bytes_needed -= bytes;
 640                 attempts = 3; /* reset counter after successful attempt */
 641             } else if (bytes < 0 && errno != EINTR) {
 642                 break;
 643             }
 644         }
 645     }
 646     entropy_available = rand_pool_entropy_available(pool);
 647     if (entropy_available > 0)
 648         return entropy_available;
 649 #   endif
 650
 651 #   if defined(OPENSSL_RAND_SEED_LIBRANDOM)
 652     {
 653         /* Not yet implemented. */
 654     }
 655 #   endif
 656
 657 #   if defined(OPENSSL_RAND_SEED_DEVRANDOM)
 658     if (wait_random_seeded()) {
 659         size_t bytes_needed;
 660         unsigned char *buffer;
 661         size_t i;
 662
 663         bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
 664         for (i = 0; bytes_needed > 0 && i < OSSL_NELEM(random_device_paths);
 665              i++) {
 666             ssize_t bytes = 0;
 667             /* Maximum number of consecutive unsuccessful attempts */
 668             int attempts = 3;
 669             const int fd = get_random_device(i);
 670
 671             if (fd == -1)
 672                 continue;
 673
 674             while (bytes_needed != 0 && attempts-- > 0) {
 675                 buffer = rand_pool_add_begin(pool, bytes_needed);
 676                 bytes = read(fd, buffer, bytes_needed);
 677
 678                 if (bytes > 0) {
 679                     rand_pool_add_end(pool, bytes, 8 * bytes);
 680                     bytes_needed -= bytes;
 681                     attempts = 3; /* reset counter on successful attempt */
 682                 } else if (bytes < 0 && errno != EINTR) {
 683                     break;
 684                 }
 685             }
 686             if (bytes < 0 || !keep_random_devices_open)
 687                 close_random_device(i);
 688
 689             bytes_needed = rand_pool_bytes_needed(pool, 1);
 690         }
 691         entropy_available = rand_pool_entropy_available(pool);
 692         if (entropy_available > 0)
 693             return entropy_available;
 694     }
 695 #   endif
 696
 697 #   if defined(OPENSSL_RAND_SEED_RDTSC)
 698     entropy_available = rand_acquire_entropy_from_tsc(pool);
 699     if (entropy_available > 0)
 700         return entropy_available;
 701 #   endif
 702
 703 #   if defined(OPENSSL_RAND_SEED_RDCPU)
 704     entropy_available = rand_acquire_entropy_from_cpu(pool);
 705     if (entropy_available > 0)
 706         return entropy_available;
 707 #   endif
 708
 709 #   if defined(OPENSSL_RAND_SEED_EGD)
 710     {
 711         static const char *paths[] = { DEVRANDOM_EGD, NULL };
 712         size_t bytes_needed;
 713         unsigned char *buffer;
 714         int i;
 715
 716         bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
 717         for (i = 0; bytes_needed > 0 && paths[i] != NULL; i++) {
 718             size_t bytes = 0;
 719             int num;
 720
 721             buffer = rand_pool_add_begin(pool, bytes_needed);
 722             num = RAND_query_egd_bytes(paths[i],
 723                                        buffer, (int)bytes_needed);
 724             if (num == (int)bytes_needed)
 725                 bytes = bytes_needed;
 726
 727             rand_pool_add_end(pool, bytes, 8 * bytes);
 728             bytes_needed = rand_pool_bytes_needed(pool, 1);
 729         }
 730         entropy_available = rand_pool_entropy_available(pool);
 731         if (entropy_available > 0)
 732             return entropy_available;
 733     }
 734 #   endif
 735
 736     return rand_pool_entropy_available(pool);
 737 #  endif
 738 }
 739 # endif
 740 #endif
 741
 742 #if defined(OPENSSL_SYS_UNIX) || defined(__DJGPP__)
 743 int rand_pool_add_nonce_data(RAND_POOL *pool)
 744 {
 745     struct {
 746         pid_t pid;
 747         CRYPTO_THREAD_ID tid;
 748         uint64_t time;
 749     } data = { 0 };
 750
 751     /*
 752      * Add process id, thread id, and a high resolution timestamp to
 753      * ensure that the nonce is unique with high probability for
 754      * different process instances.
 755      */
 756     data.pid = getpid();
 757     data.tid = CRYPTO_THREAD_get_current_id();
 758     data.time = get_time_stamp();
 759
 760     return rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0);
 761 }
 762
 763 int rand_pool_add_additional_data(RAND_POOL *pool)
 764 {
 765     struct {
 766         int fork_id;
 767         CRYPTO_THREAD_ID tid;
 768         uint64_t time;
 769     } data = { 0 };
 770
 771     /*
 772      * Add some noise from the thread id and a high resolution timer.
 773      * The fork_id adds some extra fork-safety.
 774      * The thread id adds a little randomness if the drbg is accessed
 775      * concurrently (which is the case for the <master> drbg).
 776      */
 777     data.fork_id = openssl_get_fork_id();
 778     data.tid = CRYPTO_THREAD_get_current_id();
 779     data.time = get_timer_bits();
 780
 781     return rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0);
 782 }
 783
 784
 785 /*
 786  * Get the current time with the highest possible resolution
 787  *
 788  * The time stamp is added to the nonce, so it is optimized for not repeating.
 789  * The current time is ideal for this purpose, provided the computer's clock
 790  * is synchronized.
 791  */
 792 static uint64_t get_time_stamp(void)
 793 {
 794 # if defined(OSSL_POSIX_TIMER_OKAY)
 795     {
 796         struct timespec ts;
 797
 798         if (clock_gettime(CLOCK_REALTIME, &ts) == 0)
 799             return TWO32TO64(ts.tv_sec, ts.tv_nsec);
 800     }
 801 # endif
 802 # if defined(__unix__) \
 803      || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
 804     {
 805         struct timeval tv;
 806
 807         if (gettimeofday(&tv, NULL) == 0)
 808             return TWO32TO64(tv.tv_sec, tv.tv_usec);
 809     }
 810 # endif
 811     return time(NULL);
 812 }
 813
 814 /*
 815  * Get an arbitrary timer value of the highest possible resolution
 816  *
 817  * The timer value is added as random noise to the additional data,
 818  * which is not considered a trusted entropy sourec, so any result
 819  * is acceptable.
 820  */
 821 static uint64_t get_timer_bits(void)
 822 {
 823     uint64_t res = OPENSSL_rdtsc();
 824
 825     if (res != 0)
 826         return res;
 827
 828 # if defined(__sun) || defined(__hpux)
 829     return gethrtime();
 830 # elif defined(_AIX)
 831     {
 832         timebasestruct_t t;
 833
 834         read_wall_time(&t, TIMEBASE_SZ);
 835         return TWO32TO64(t.tb_high, t.tb_low);
 836     }
 837 # elif defined(OSSL_POSIX_TIMER_OKAY)
 838     {
 839         struct timespec ts;
 840
 841 #  ifdef CLOCK_BOOTTIME
 842 #   define CLOCK_TYPE CLOCK_BOOTTIME
 843 #  elif defined(_POSIX_MONOTONIC_CLOCK)
 844 #   define CLOCK_TYPE CLOCK_MONOTONIC
 845 #  else
 846 #   define CLOCK_TYPE CLOCK_REALTIME
 847 #  endif
 848
 849         if (clock_gettime(CLOCK_TYPE, &ts) == 0)
 850             return TWO32TO64(ts.tv_sec, ts.tv_nsec);
 851     }
 852 # endif
 853 # if defined(__unix__) \
 854      || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
 855     {
 856         struct timeval tv;
 857
 858         if (gettimeofday(&tv, NULL) == 0)
 859             return TWO32TO64(tv.tv_sec, tv.tv_usec);
 860     }
 861 # endif
 862     return time(NULL);
 863 }
 864 #endif /* (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS))
 865           || defined(__DJGPP__) */