crypto/rand/rand_unix.c

   1 /*
   2  * Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (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
  23 #ifdef __linux
  24 # include <sys/syscall.h>
  25 # ifdef DEVRANDOM_WAIT
  26 #  include <sys/shm.h>
  27 #  include <sys/utsname.h>
  28 # endif
  29 #endif
  30 #if defined(__FreeBSD__) && !defined(OPENSSL_SYS_UEFI)
  31 # include <sys/types.h>
  32 # include <sys/sysctl.h>
  33 # include <sys/param.h>
  34 #endif
  35 #if defined(__OpenBSD__) || defined(__NetBSD__)
  36 # include <sys/param.h>
  37 #endif
  38
  39 #if (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS)) \
  40      || defined(__DJGPP__)
  41 # include <sys/types.h>
  42 # include <sys/stat.h>
  43 # include <fcntl.h>
  44 # include <unistd.h>
  45 # include <sys/time.h>
  46
  47 static uint64_t get_time_stamp(void);
  48 static uint64_t get_timer_bits(void);
  49
  50 /* Macro to convert two thirty two bit values into a sixty four bit one */
  51 # define TWO32TO64(a, b) ((((uint64_t)(a)) << 32) + (b))
  52
  53 /*
  54  * Check for the existence and support of POSIX timers.  The standard
  55  * says that the _POSIX_TIMERS macro will have a positive value if they
  56  * are available.
  57  *
  58  * However, we want an additional constraint: that the timer support does
  59  * not require an extra library dependency.  Early versions of glibc
  60  * require -lrt to be specified on the link line to access the timers,
  61  * so this needs to be checked for.
  62  *
  63  * It is worse because some libraries define __GLIBC__ but don't
  64  * support the version testing macro (e.g. uClibc).  This means
  65  * an extra check is needed.
  66  *
  67  * The final condition is:
  68  *      "have posix timers and either not glibc or glibc without -lrt"
  69  *
  70  * The nested #if sequences are required to avoid using a parameterised
  71  * macro that might be undefined.
  72  */
  73 # undef OSSL_POSIX_TIMER_OKAY
  74 # if defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0
  75 #  if defined(__GLIBC__)
  76 #   if defined(__GLIBC_PREREQ)
  77 #    if __GLIBC_PREREQ(2, 17)
  78 #     define OSSL_POSIX_TIMER_OKAY
  79 #    endif
  80 #   endif
  81 #  else
  82 #   define OSSL_POSIX_TIMER_OKAY
  83 #  endif
  84 # endif
  85 #endif /* (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS))
  86           || defined(__DJGPP__) */
  87
  88 #if defined(OPENSSL_RAND_SEED_NONE)
  89 /* none means none. this simplifies the following logic */
  90 # undef OPENSSL_RAND_SEED_OS
  91 # undef OPENSSL_RAND_SEED_GETRANDOM
  92 # undef OPENSSL_RAND_SEED_LIBRANDOM
  93 # undef OPENSSL_RAND_SEED_DEVRANDOM
  94 # undef OPENSSL_RAND_SEED_RDTSC
  95 # undef OPENSSL_RAND_SEED_RDCPU
  96 # undef OPENSSL_RAND_SEED_EGD
  97 #endif
  98
  99 #if defined(OPENSSL_SYS_UEFI) && !defined(OPENSSL_RAND_SEED_NONE)
 100 # error "UEFI only supports seeding NONE"
 101 #endif
 102
 103 #if !(defined(OPENSSL_SYS_WINDOWS) || defined(OPENSSL_SYS_WIN32) \
 104     || defined(OPENSSL_SYS_VMS) || defined(OPENSSL_SYS_VXWORKS) \
 105     || defined(OPENSSL_SYS_UEFI))
 106
 107 # if defined(OPENSSL_SYS_VOS)
 108
 109 #  ifndef OPENSSL_RAND_SEED_OS
 110 #   error "Unsupported seeding method configured; must be os"
 111 #  endif
 112
 113 #  if defined(OPENSSL_SYS_VOS_HPPA) && defined(OPENSSL_SYS_VOS_IA32)
 114 #   error "Unsupported HP-PA and IA32 at the same time."
 115 #  endif
 116 #  if !defined(OPENSSL_SYS_VOS_HPPA) && !defined(OPENSSL_SYS_VOS_IA32)
 117 #   error "Must have one of HP-PA or IA32"
 118 #  endif
 119
 120 /*
 121  * The following algorithm repeatedly samples the real-time clock (RTC) to
 122  * generate a sequence of unpredictable data.  The algorithm relies upon the
 123  * uneven execution speed of the code (due to factors such as cache misses,
 124  * interrupts, bus activity, and scheduling) and upon the rather large
 125  * relative difference between the speed of the clock and the rate at which
 126  * it can be read.  If it is ported to an environment where execution speed
 127  * is more constant or where the RTC ticks at a much slower rate, or the
 128  * clock can be read with fewer instructions, it is likely that the results
 129  * would be far more predictable.  This should only be used for legacy
 130  * platforms.
 131  *
 132  * As a precaution, we assume only 2 bits of entropy per byte.
 133  */
 134 size_t rand_pool_acquire_entropy(RAND_POOL *pool)
 135 {
 136     short int code;
 137     int i, k;
 138     size_t bytes_needed;
 139     struct timespec ts;
 140     unsigned char v;
 141 #  ifdef OPENSSL_SYS_VOS_HPPA
 142     long duration;
 143     extern void s$sleep(long *_duration, short int *_code);
 144 #  else
 145     long long duration;
 146     extern void s$sleep2(long long *_duration, short int *_code);
 147 #  endif
 148
 149     bytes_needed = rand_pool_bytes_needed(pool, 4 /*entropy_factor*/);
 150
 151     for (i = 0; i < bytes_needed; i++) {
 152         /*
 153          * burn some cpu; hope for interrupts, cache collisions, bus
 154          * interference, etc.
 155          */
 156         for (k = 0; k < 99; k++)
 157             ts.tv_nsec = random();
 158
 159 #  ifdef OPENSSL_SYS_VOS_HPPA
 160         /* sleep for 1/1024 of a second (976 us).  */
 161         duration = 1;
 162         s$sleep(&duration, &code);
 163 #  else
 164         /* sleep for 1/65536 of a second (15 us).  */
 165         duration = 1;
 166         s$sleep2(&duration, &code);
 167 #  endif
 168
 169         /* Get wall clock time, take 8 bits. */
 170         clock_gettime(CLOCK_REALTIME, &ts);
 171         v = (unsigned char)(ts.tv_nsec & 0xFF);
 172         rand_pool_add(pool, arg, &v, sizeof(v) , 2);
 173     }
 174     return rand_pool_entropy_available(pool);
 175 }
 176
 177 void rand_pool_cleanup(void)
 178 {
 179 }
 180
 181 void rand_pool_keep_random_devices_open(int keep)
 182 {
 183 }
 184
 185 # else
 186
 187 #  if defined(OPENSSL_RAND_SEED_EGD) && \
 188         (defined(OPENSSL_NO_EGD) || !defined(DEVRANDOM_EGD))
 189 #   error "Seeding uses EGD but EGD is turned off or no device given"
 190 #  endif
 191
 192 #  if defined(OPENSSL_RAND_SEED_DEVRANDOM) && !defined(DEVRANDOM)
 193 #   error "Seeding uses urandom but DEVRANDOM is not configured"
 194 #  endif
 195
 196 #  if defined(OPENSSL_RAND_SEED_OS)
 197 #   if !defined(DEVRANDOM)
 198 #    error "OS seeding requires DEVRANDOM to be configured"
 199 #   endif
 200 #   define OPENSSL_RAND_SEED_GETRANDOM
 201 #   define OPENSSL_RAND_SEED_DEVRANDOM
 202 #  endif
 203
 204 #  if defined(OPENSSL_RAND_SEED_LIBRANDOM)
 205 #   error "librandom not (yet) supported"
 206 #  endif
 207
 208 #  if (defined(__FreeBSD__) || defined(__NetBSD__)) && defined(KERN_ARND)
 209 /*
 210  * sysctl_random(): Use sysctl() to read a random number from the kernel
 211  * Returns the number of bytes returned in buf on success, -1 on failure.
 212  */
 213 static ssize_t sysctl_random(char *buf, size_t buflen)
 214 {
 215     int mib[2];
 216     size_t done = 0;
 217     size_t len;
 218
 219     /*
 220      * Note: sign conversion between size_t and ssize_t is safe even
 221      * without a range check, see comment in syscall_random()
 222      */
 223
 224     /*
 225      * On FreeBSD old implementations returned longs, newer versions support
 226      * variable sizes up to 256 byte. The code below would not work properly
 227      * when the sysctl returns long and we want to request something not a
 228      * multiple of longs, which should never be the case.
 229      */
 230     if (!ossl_assert(buflen % sizeof(long) == 0)) {
 231         errno = EINVAL;
 232         return -1;
 233     }
 234
 235     /*
 236      * On NetBSD before 4.0 KERN_ARND was an alias for KERN_URND, and only
 237      * filled in an int, leaving the rest uninitialized. Since NetBSD 4.0
 238      * it returns a variable number of bytes with the current version supporting
 239      * up to 256 bytes.
 240      * Just return an error on older NetBSD versions.
 241      */
 242 #if   defined(__NetBSD__) && __NetBSD_Version__ < 400000000
 243     errno = ENOSYS;
 244     return -1;
 245 #endif
 246
 247     mib[0] = CTL_KERN;
 248     mib[1] = KERN_ARND;
 249
 250     do {
 251         len = buflen;
 252         if (sysctl(mib, 2, buf, &len, NULL, 0) == -1)
 253             return done > 0 ? done : -1;
 254         done += len;
 255         buf += len;
 256         buflen -= len;
 257     } while (buflen > 0);
 258
 259     return done;
 260 }
 261 #  endif
 262
 263 #  if defined(OPENSSL_RAND_SEED_GETRANDOM)
 264
 265 #   if defined(__linux) && !defined(__NR_getrandom)
 266 #    if defined(__arm__)
 267 #     define __NR_getrandom    (__NR_SYSCALL_BASE+384)
 268 #    elif defined(__i386__)
 269 #     define __NR_getrandom    355
 270 #    elif defined(__x86_64__)
 271 #     if defined(__ILP32__)
 272 #      define __NR_getrandom   (__X32_SYSCALL_BIT + 318)
 273 #     else
 274 #      define __NR_getrandom   318
 275 #     endif
 276 #    elif defined(__xtensa__)
 277 #     define __NR_getrandom    338
 278 #    elif defined(__s390__) || defined(__s390x__)
 279 #     define __NR_getrandom    349
 280 #    elif defined(__bfin__)
 281 #     define __NR_getrandom    389
 282 #    elif defined(__powerpc__)
 283 #     define __NR_getrandom    359
 284 #    elif defined(__mips__) || defined(__mips64)
 285 #     if _MIPS_SIM == _MIPS_SIM_ABI32
 286 #      define __NR_getrandom   (__NR_Linux + 353)
 287 #     elif _MIPS_SIM == _MIPS_SIM_ABI64
 288 #      define __NR_getrandom   (__NR_Linux + 313)
 289 #     elif _MIPS_SIM == _MIPS_SIM_NABI32
 290 #      define __NR_getrandom   (__NR_Linux + 317)
 291 #     endif
 292 #    elif defined(__hppa__)
 293 #     define __NR_getrandom    (__NR_Linux + 339)
 294 #    elif defined(__sparc__)
 295 #     define __NR_getrandom    347
 296 #    elif defined(__ia64__)
 297 #     define __NR_getrandom    1339
 298 #    elif defined(__alpha__)
 299 #     define __NR_getrandom    511
 300 #    elif defined(__sh__)
 301 #     if defined(__SH5__)
 302 #      define __NR_getrandom   373
 303 #     else
 304 #      define __NR_getrandom   384
 305 #     endif
 306 #    elif defined(__avr32__)
 307 #     define __NR_getrandom    317
 308 #    elif defined(__microblaze__)
 309 #     define __NR_getrandom    385
 310 #    elif defined(__m68k__)
 311 #     define __NR_getrandom    352
 312 #    elif defined(__cris__)
 313 #     define __NR_getrandom    356
 314 #    elif defined(__aarch64__)
 315 #     define __NR_getrandom    278
 316 #    else /* generic */
 317 #     define __NR_getrandom    278
 318 #    endif
 319 #   endif
 320
 321 /*
 322  * syscall_random(): Try to get random data using a system call
 323  * returns the number of bytes returned in buf, or < 0 on error.
 324  */
 325 static ssize_t syscall_random(void *buf, size_t buflen)
 326 {
 327     /*
 328      * Note: 'buflen' equals the size of the buffer which is used by the
 329      * get_entropy() callback of the RAND_DRBG. It is roughly bounded by
 330      *
 331      *   2 * RAND_POOL_FACTOR * (RAND_DRBG_STRENGTH / 8) = 2^14
 332      *
 333      * which is way below the OSSL_SSIZE_MAX limit. Therefore sign conversion
 334      * between size_t and ssize_t is safe even without a range check.
 335      */
 336
 337     /*
 338      * Do runtime detection to find getentropy().
 339      *
 340      * Known OSs that should support this:
 341      * - Darwin since 16 (OSX 10.12, IOS 10.0).
 342      * - Solaris since 11.3
 343      * - OpenBSD since 5.6
 344      * - Linux since 3.17 with glibc 2.25
 345      * - FreeBSD since 12.0 (1200061)
 346      */
 347 #  if defined(__GNUC__) && __GNUC__>=2 && defined(__ELF__) && !defined(__hpux)
 348     extern int getentropy(void *buffer, size_t length) __attribute__((weak));
 349
 350     if (getentropy != NULL)
 351         return getentropy(buf, buflen) == 0 ? (ssize_t)buflen : -1;
 352 #  elif !defined(FIPS_MODE)
 353     union {
 354         void *p;
 355         int (*f)(void *buffer, size_t length);
 356     } p_getentropy;
 357
 358     /*
 359      * We could cache the result of the lookup, but we normally don't
 360      * call this function often.
 361      */
 362     ERR_set_mark();
 363     p_getentropy.p = DSO_global_lookup("getentropy");
 364     ERR_pop_to_mark();
 365     if (p_getentropy.p != NULL)
 366         return p_getentropy.f(buf, buflen) == 0 ? (ssize_t)buflen : -1;
 367 #  endif
 368
 369     /* Linux supports this since version 3.17 */
 370 #  if defined(__linux) && defined(__NR_getrandom)
 371     return syscall(__NR_getrandom, buf, buflen, 0);
 372 #  elif (defined(__FreeBSD__) || defined(__NetBSD__)) && defined(KERN_ARND)
 373     return sysctl_random(buf, buflen);
 374 #  else
 375     errno = ENOSYS;
 376     return -1;
 377 #  endif
 378 }
 379 #  endif    /* defined(OPENSSL_RAND_SEED_GETRANDOM) */
 380
 381 #  if defined(OPENSSL_RAND_SEED_DEVRANDOM)
 382 static const char *random_device_paths[] = { DEVRANDOM };
 383 static struct random_device {
 384     int fd;
 385     dev_t dev;
 386     ino_t ino;
 387     mode_t mode;
 388     dev_t rdev;
 389 } random_devices[OSSL_NELEM(random_device_paths)];
 390 static int keep_random_devices_open = 1;
 391
 392 #   if defined(__linux) && defined(DEVRANDOM_WAIT)
 393 static void *shm_addr;
 394
 395 #    if !defined(FIPS_MODE)
 396 static void cleanup_shm(void)
 397 {
 398     shmdt(shm_addr);
 399 }
 400 #    endif
 401
 402 /*
 403  * Ensure that the system randomness source has been adequately seeded.
 404  * This is done by having the first start of libcrypto, wait until the device
 405  * /dev/random becomes able to supply a byte of entropy.  Subsequent starts
 406  * of the library and later reseedings do not need to do this.
 407  */
 408 static int wait_random_seeded(void)
 409 {
 410     static int seeded = OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID < 0;
 411     static const int kernel_version[] = { DEVRANDOM_SAFE_KERNEL };
 412     int kernel[2];
 413     int shm_id, fd, r;
 414     char c, *p;
 415     struct utsname un;
 416     fd_set fds;
 417
 418     if (!seeded) {
 419         /* See if anything has created the global seeded indication */
 420         if ((shm_id = shmget(OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID, 1, 0)) == -1) {
 421             /*
 422              * Check the kernel's version and fail if it is too recent.
 423              *
 424              * Linux kernels from 4.8 onwards do not guarantee that
 425              * /dev/urandom is properly seeded when /dev/random becomes
 426              * readable.  However, such kernels support the getentropy(2)
 427              * system call and this should always succeed which renders
 428              * this alternative but essentially identical source moot.
 429              */
 430             if (uname(&un) == 0) {
 431                 kernel[0] = atoi(un.release);
 432                 p = strchr(un.release, '.');
 433                 kernel[1] = p == NULL ? 0 : atoi(p + 1);
 434                 if (kernel[0] > kernel_version[0]
 435                     || (kernel[0] == kernel_version[0]
 436                         && kernel[1] >= kernel_version[1])) {
 437                     return 0;
 438                 }
 439             }
 440             /* Open /dev/random and wait for it to be readable */
 441             if ((fd = open(DEVRANDOM_WAIT, O_RDONLY)) != -1) {
 442                 if (DEVRANDM_WAIT_USE_SELECT && fd < FD_SETSIZE) {
 443                     FD_ZERO(&fds);
 444                     FD_SET(fd, &fds);
 445                     while ((r = select(fd + 1, &fds, NULL, NULL, NULL)) < 0
 446                            && errno == EINTR);
 447                 } else {
 448                     while ((r = read(fd, &c, 1)) < 0 && errno == EINTR);
 449                 }
 450                 close(fd);
 451                 if (r == 1) {
 452                     seeded = 1;
 453                     /* Create the shared memory indicator */
 454                     shm_id = shmget(OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID, 1,
 455                                     IPC_CREAT | S_IRUSR | S_IRGRP | S_IROTH);
 456                 }
 457             }
 458         }
 459         if (shm_id != -1) {
 460             seeded = 1;
 461             /*
 462              * Map the shared memory to prevent its premature destruction.
 463              * If this call fails, it isn't a big problem.
 464              */
 465             shm_addr = shmat(shm_id, NULL, SHM_RDONLY);
 466 #    ifndef FIPS_MODE
 467             /* TODO 3.0: The FIPS provider doesn't have OPENSSL_atexit */
 468             if (shm_addr != (void *)-1)
 469                 OPENSSL_atexit(&cleanup_shm);
 470 #    endif
 471         }
 472     }
 473     return seeded;
 474 }
 475 #   else /* defined __linux */
 476 static int wait_random_seeded(void)
 477 {
 478     return 1;
 479 }
 480 #   endif
 481
 482 /*
 483  * Verify that the file descriptor associated with the random source is
 484  * still valid. The rationale for doing this is the fact that it is not
 485  * uncommon for daemons to close all open file handles when daemonizing.
 486  * So the handle might have been closed or even reused for opening
 487  * another file.
 488  */
 489 static int check_random_device(struct random_device * rd)
 490 {
 491     struct stat st;
 492
 493     return rd->fd != -1
 494            && fstat(rd->fd, &st) != -1
 495            && rd->dev == st.st_dev
 496            && rd->ino == st.st_ino
 497            && ((rd->mode ^ st.st_mode) & ~(S_IRWXU | S_IRWXG | S_IRWXO)) == 0
 498            && rd->rdev == st.st_rdev;
 499 }
 500
 501 /*
 502  * Open a random device if required and return its file descriptor or -1 on error
 503  */
 504 static int get_random_device(size_t n)
 505 {
 506     struct stat st;
 507     struct random_device * rd = &random_devices[n];
 508
 509     /* reuse existing file descriptor if it is (still) valid */
 510     if (check_random_device(rd))
 511         return rd->fd;
 512
 513     /* open the random device ... */
 514     if ((rd->fd = open(random_device_paths[n], O_RDONLY)) == -1)
 515         return rd->fd;
 516
 517     /* ... and cache its relevant stat(2) data */
 518     if (fstat(rd->fd, &st) != -1) {
 519         rd->dev = st.st_dev;
 520         rd->ino = st.st_ino;
 521         rd->mode = st.st_mode;
 522         rd->rdev = st.st_rdev;
 523     } else {
 524         close(rd->fd);
 525         rd->fd = -1;
 526     }
 527
 528     return rd->fd;
 529 }
 530
 531 /*
 532  * Close a random device making sure it is a random device
 533  */
 534 static void close_random_device(size_t n)
 535 {
 536     struct random_device * rd = &random_devices[n];
 537
 538     if (check_random_device(rd))
 539         close(rd->fd);
 540     rd->fd = -1;
 541 }
 542
 543 int rand_pool_init(void)
 544 {
 545     size_t i;
 546
 547     for (i = 0; i < OSSL_NELEM(random_devices); i++)
 548         random_devices[i].fd = -1;
 549
 550     return 1;
 551 }
 552
 553 void rand_pool_cleanup(void)
 554 {
 555     size_t i;
 556
 557     for (i = 0; i < OSSL_NELEM(random_devices); i++)
 558         close_random_device(i);
 559 }
 560
 561 void rand_pool_keep_random_devices_open(int keep)
 562 {
 563     if (!keep)
 564         rand_pool_cleanup();
 565
 566     keep_random_devices_open = keep;
 567 }
 568
 569 #  else     /* !defined(OPENSSL_RAND_SEED_DEVRANDOM) */
 570
 571 int rand_pool_init(void)
 572 {
 573     return 1;
 574 }
 575
 576 void rand_pool_cleanup(void)
 577 {
 578 }
 579
 580 void rand_pool_keep_random_devices_open(int keep)
 581 {
 582 }
 583
 584 #  endif    /* defined(OPENSSL_RAND_SEED_DEVRANDOM) */
 585
 586 /*
 587  * Try the various seeding methods in turn, exit when successful.
 588  *
 589  * TODO(DRBG): If more than one entropy source is available, is it
 590  * preferable to stop as soon as enough entropy has been collected
 591  * (as favored by @rsalz) or should one rather be defensive and add
 592  * more entropy than requested and/or from different sources?
 593  *
 594  * Currently, the user can select multiple entropy sources in the
 595  * configure step, yet in practice only the first available source
 596  * will be used. A more flexible solution has been requested, but
 597  * currently it is not clear how this can be achieved without
 598  * overengineering the problem. There are many parameters which
 599  * could be taken into account when selecting the order and amount
 600  * of input from the different entropy sources (trust, quality,
 601  * possibility of blocking).
 602  */
 603 size_t rand_pool_acquire_entropy(RAND_POOL *pool)
 604 {
 605 #  if defined(OPENSSL_RAND_SEED_NONE)
 606     return rand_pool_entropy_available(pool);
 607 #  else
 608     size_t entropy_available;
 609
 610 #   if defined(OPENSSL_RAND_SEED_GETRANDOM)
 611     {
 612         size_t bytes_needed;
 613         unsigned char *buffer;
 614         ssize_t bytes;
 615         /* Maximum allowed number of consecutive unsuccessful attempts */
 616         int attempts = 3;
 617
 618         bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
 619         while (bytes_needed != 0 && attempts-- > 0) {
 620             buffer = rand_pool_add_begin(pool, bytes_needed);
 621             bytes = syscall_random(buffer, bytes_needed);
 622             if (bytes > 0) {
 623                 rand_pool_add_end(pool, bytes, 8 * bytes);
 624                 bytes_needed -= bytes;
 625                 attempts = 3; /* reset counter after successful attempt */
 626             } else if (bytes < 0 && errno != EINTR) {
 627                 break;
 628             }
 629         }
 630     }
 631     entropy_available = rand_pool_entropy_available(pool);
 632     if (entropy_available > 0)
 633         return entropy_available;
 634 #   endif
 635
 636 #   if defined(OPENSSL_RAND_SEED_LIBRANDOM)
 637     {
 638         /* Not yet implemented. */
 639     }
 640 #   endif
 641
 642 #   if defined(OPENSSL_RAND_SEED_DEVRANDOM)
 643     if (wait_random_seeded()) {
 644         size_t bytes_needed;
 645         unsigned char *buffer;
 646         size_t i;
 647
 648         bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
 649         for (i = 0; bytes_needed > 0 && i < OSSL_NELEM(random_device_paths);
 650              i++) {
 651             ssize_t bytes = 0;
 652             /* Maximum number of consecutive unsuccessful attempts */
 653             int attempts = 3;
 654             const int fd = get_random_device(i);
 655
 656             if (fd == -1)
 657                 continue;
 658
 659             while (bytes_needed != 0 && attempts-- > 0) {
 660                 buffer = rand_pool_add_begin(pool, bytes_needed);
 661                 bytes = read(fd, buffer, bytes_needed);
 662
 663                 if (bytes > 0) {
 664                     rand_pool_add_end(pool, bytes, 8 * bytes);
 665                     bytes_needed -= bytes;
 666                     attempts = 3; /* reset counter on successful attempt */
 667                 } else if (bytes < 0 && errno != EINTR) {
 668                     break;
 669                 }
 670             }
 671             if (bytes < 0 || !keep_random_devices_open)
 672                 close_random_device(i);
 673
 674             bytes_needed = rand_pool_bytes_needed(pool, 1);
 675         }
 676         entropy_available = rand_pool_entropy_available(pool);
 677         if (entropy_available > 0)
 678             return entropy_available;
 679     }
 680 #   endif
 681
 682 #   if defined(OPENSSL_RAND_SEED_RDTSC)
 683     entropy_available = rand_acquire_entropy_from_tsc(pool);
 684     if (entropy_available > 0)
 685         return entropy_available;
 686 #   endif
 687
 688 #   if defined(OPENSSL_RAND_SEED_RDCPU)
 689     entropy_available = rand_acquire_entropy_from_cpu(pool);
 690     if (entropy_available > 0)
 691         return entropy_available;
 692 #   endif
 693
 694 #   if defined(OPENSSL_RAND_SEED_EGD)
 695     {
 696         static const char *paths[] = { DEVRANDOM_EGD, NULL };
 697         size_t bytes_needed;
 698         unsigned char *buffer;
 699         int i;
 700
 701         bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
 702         for (i = 0; bytes_needed > 0 && paths[i] != NULL; i++) {
 703             size_t bytes = 0;
 704             int num;
 705
 706             buffer = rand_pool_add_begin(pool, bytes_needed);
 707             num = RAND_query_egd_bytes(paths[i],
 708                                        buffer, (int)bytes_needed);
 709             if (num == (int)bytes_needed)
 710                 bytes = bytes_needed;
 711
 712             rand_pool_add_end(pool, bytes, 8 * bytes);
 713             bytes_needed = rand_pool_bytes_needed(pool, 1);
 714         }
 715         entropy_available = rand_pool_entropy_available(pool);
 716         if (entropy_available > 0)
 717             return entropy_available;
 718     }
 719 #   endif
 720
 721     return rand_pool_entropy_available(pool);
 722 #  endif
 723 }
 724 # endif
 725 #endif
 726
 727 #if (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS)) \
 728      || defined(__DJGPP__)
 729 int rand_pool_add_nonce_data(RAND_POOL *pool)
 730 {
 731     struct {
 732         pid_t pid;
 733         CRYPTO_THREAD_ID tid;
 734         uint64_t time;
 735     } data;
 736
 737     /* Erase the entire structure including any padding */
 738     memset(&data, 0, sizeof(data));
 739
 740     /*
 741      * Add process id, thread id, and a high resolution timestamp to
 742      * ensure that the nonce is unique with high probability for
 743      * different process instances.
 744      */
 745     data.pid = getpid();
 746     data.tid = CRYPTO_THREAD_get_current_id();
 747     data.time = get_time_stamp();
 748
 749     return rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0);
 750 }
 751
 752 int rand_pool_add_additional_data(RAND_POOL *pool)
 753 {
 754     struct {
 755         int fork_id;
 756         CRYPTO_THREAD_ID tid;
 757         uint64_t time;
 758     } data;
 759
 760     /* Erase the entire structure including any padding */
 761     memset(&data, 0, sizeof(data));
 762
 763     /*
 764      * Add some noise from the thread id and a high resolution timer.
 765      * The fork_id adds some extra fork-safety.
 766      * The thread id adds a little randomness if the drbg is accessed
 767      * concurrently (which is the case for the <master> drbg).
 768      */
 769     data.fork_id = openssl_get_fork_id();
 770     data.tid = CRYPTO_THREAD_get_current_id();
 771     data.time = get_timer_bits();
 772
 773     return rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0);
 774 }
 775
 776
 777 /*
 778  * Get the current time with the highest possible resolution
 779  *
 780  * The time stamp is added to the nonce, so it is optimized for not repeating.
 781  * The current time is ideal for this purpose, provided the computer's clock
 782  * is synchronized.
 783  */
 784 static uint64_t get_time_stamp(void)
 785 {
 786 # if defined(OSSL_POSIX_TIMER_OKAY)
 787     {
 788         struct timespec ts;
 789
 790         if (clock_gettime(CLOCK_REALTIME, &ts) == 0)
 791             return TWO32TO64(ts.tv_sec, ts.tv_nsec);
 792     }
 793 # endif
 794 # if defined(__unix__) \
 795      || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
 796     {
 797         struct timeval tv;
 798
 799         if (gettimeofday(&tv, NULL) == 0)
 800             return TWO32TO64(tv.tv_sec, tv.tv_usec);
 801     }
 802 # endif
 803     return time(NULL);
 804 }
 805
 806 /*
 807  * Get an arbitrary timer value of the highest possible resolution
 808  *
 809  * The timer value is added as random noise to the additional data,
 810  * which is not considered a trusted entropy sourec, so any result
 811  * is acceptable.
 812  */
 813 static uint64_t get_timer_bits(void)
 814 {
 815     uint64_t res = OPENSSL_rdtsc();
 816
 817     if (res != 0)
 818         return res;
 819
 820 # if defined(__sun) || defined(__hpux)
 821     return gethrtime();
 822 # elif defined(_AIX)
 823     {
 824         timebasestruct_t t;
 825
 826         read_wall_time(&t, TIMEBASE_SZ);
 827         return TWO32TO64(t.tb_high, t.tb_low);
 828     }
 829 # elif defined(OSSL_POSIX_TIMER_OKAY)
 830     {
 831         struct timespec ts;
 832
 833 #  ifdef CLOCK_BOOTTIME
 834 #   define CLOCK_TYPE CLOCK_BOOTTIME
 835 #  elif defined(_POSIX_MONOTONIC_CLOCK)
 836 #   define CLOCK_TYPE CLOCK_MONOTONIC
 837 #  else
 838 #   define CLOCK_TYPE CLOCK_REALTIME
 839 #  endif
 840
 841         if (clock_gettime(CLOCK_TYPE, &ts) == 0)
 842             return TWO32TO64(ts.tv_sec, ts.tv_nsec);
 843     }
 844 # endif
 845 # if defined(__unix__) \
 846      || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
 847     {
 848         struct timeval tv;
 849
 850         if (gettimeofday(&tv, NULL) == 0)
 851             return TWO32TO64(tv.tv_sec, tv.tv_usec);
 852     }
 853 # endif
 854     return time(NULL);
 855 }
 856 #endif /* (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS))
 857           || defined(__DJGPP__) */