crypto/rand/rand_unix.c

   1 /*
   2  * Copyright 1995-2018 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_lcl.h"
  19 #include "internal/rand_int.h"
  20 #include <stdio.h>
  21 #include "internal/dso.h"
  22 #if defined(__linux)
  23 # include <asm/unistd.h>
  24 # include <sys/ipc.h>
  25 # include <sys/shm.h>
  26 # include <sys/utsname.h>
  27 #endif
  28 #if defined(__FreeBSD__) && !defined(OPENSSL_SYS_UEFI)
  29 # include <sys/types.h>
  30 # include <sys/sysctl.h>
  31 # include <sys/param.h>
  32 #endif
  33 #if defined(__OpenBSD__) || defined(__NetBSD__)
  34 # include <sys/param.h>
  35 #endif
  36
  37 #if (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS)) \
  38      || 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(__DJGPP__) */
  84
  85 #if defined(OPENSSL_RAND_SEED_NONE)
  86 /* none means none. this simplifies the following logic */
  87 # undef OPENSSL_RAND_SEED_OS
  88 # undef OPENSSL_RAND_SEED_GETRANDOM
  89 # undef OPENSSL_RAND_SEED_LIBRANDOM
  90 # undef OPENSSL_RAND_SEED_DEVRANDOM
  91 # undef OPENSSL_RAND_SEED_RDTSC
  92 # undef OPENSSL_RAND_SEED_RDCPU
  93 # undef OPENSSL_RAND_SEED_EGD
  94 #endif
  95
  96 #if defined(OPENSSL_SYS_UEFI) && !defined(OPENSSL_RAND_SEED_NONE)
  97 # error "UEFI only supports seeding NONE"
  98 #endif
  99
 100 #if !(defined(OPENSSL_SYS_WINDOWS) || defined(OPENSSL_SYS_WIN32) \
 101     || defined(OPENSSL_SYS_VMS) || defined(OPENSSL_SYS_VXWORKS) \
 102     || defined(OPENSSL_SYS_UEFI))
 103
 104 # if defined(OPENSSL_SYS_VOS)
 105
 106 #  ifndef OPENSSL_RAND_SEED_OS
 107 #   error "Unsupported seeding method configured; must be os"
 108 #  endif
 109
 110 #  if defined(OPENSSL_SYS_VOS_HPPA) && defined(OPENSSL_SYS_VOS_IA32)
 111 #   error "Unsupported HP-PA and IA32 at the same time."
 112 #  endif
 113 #  if !defined(OPENSSL_SYS_VOS_HPPA) && !defined(OPENSSL_SYS_VOS_IA32)
 114 #   error "Must have one of HP-PA or IA32"
 115 #  endif
 116
 117 /*
 118  * The following algorithm repeatedly samples the real-time clock (RTC) to
 119  * generate a sequence of unpredictable data.  The algorithm relies upon the
 120  * uneven execution speed of the code (due to factors such as cache misses,
 121  * interrupts, bus activity, and scheduling) and upon the rather large
 122  * relative difference between the speed of the clock and the rate at which
 123  * it can be read.  If it is ported to an environment where execution speed
 124  * is more constant or where the RTC ticks at a much slower rate, or the
 125  * clock can be read with fewer instructions, it is likely that the results
 126  * would be far more predictable.  This should only be used for legacy
 127  * platforms.
 128  *
 129  * As a precaution, we assume only 2 bits of entropy per byte.
 130  */
 131 size_t rand_pool_acquire_entropy(RAND_POOL *pool)
 132 {
 133     short int code;
 134     int i, k;
 135     size_t bytes_needed;
 136     struct timespec ts;
 137     unsigned char v;
 138 #  ifdef OPENSSL_SYS_VOS_HPPA
 139     long duration;
 140     extern void s$sleep(long *_duration, short int *_code);
 141 #  else
 142     long long duration;
 143     extern void s$sleep2(long long *_duration, short int *_code);
 144 #  endif
 145
 146     bytes_needed = rand_pool_bytes_needed(pool, 4 /*entropy_factor*/);
 147
 148     for (i = 0; i < bytes_needed; i++) {
 149         /*
 150          * burn some cpu; hope for interrupts, cache collisions, bus
 151          * interference, etc.
 152          */
 153         for (k = 0; k < 99; k++)
 154             ts.tv_nsec = random();
 155
 156 #  ifdef OPENSSL_SYS_VOS_HPPA
 157         /* sleep for 1/1024 of a second (976 us).  */
 158         duration = 1;
 159         s$sleep(&duration, &code);
 160 #  else
 161         /* sleep for 1/65536 of a second (15 us).  */
 162         duration = 1;
 163         s$sleep2(&duration, &code);
 164 #  endif
 165
 166         /* Get wall clock time, take 8 bits. */
 167         clock_gettime(CLOCK_REALTIME, &ts);
 168         v = (unsigned char)(ts.tv_nsec & 0xFF);
 169         rand_pool_add(pool, arg, &v, sizeof(v) , 2);
 170     }
 171     return rand_pool_entropy_available(pool);
 172 }
 173
 174 void rand_pool_cleanup(void)
 175 {
 176 }
 177
 178 void rand_pool_keep_random_devices_open(int keep)
 179 {
 180 }
 181
 182 # else
 183
 184 #  if defined(OPENSSL_RAND_SEED_EGD) && \
 185         (defined(OPENSSL_NO_EGD) || !defined(DEVRANDOM_EGD))
 186 #   error "Seeding uses EGD but EGD is turned off or no device given"
 187 #  endif
 188
 189 #  if defined(OPENSSL_RAND_SEED_DEVRANDOM) && !defined(DEVRANDOM)
 190 #   error "Seeding uses urandom but DEVRANDOM is not configured"
 191 #  endif
 192
 193 #  if defined(OPENSSL_RAND_SEED_OS)
 194 #   if !defined(DEVRANDOM)
 195 #    error "OS seeding requires DEVRANDOM to be configured"
 196 #   endif
 197 #   define OPENSSL_RAND_SEED_GETRANDOM
 198 #   define OPENSSL_RAND_SEED_DEVRANDOM
 199 #  endif
 200
 201 #  if defined(OPENSSL_RAND_SEED_LIBRANDOM)
 202 #   error "librandom not (yet) supported"
 203 #  endif
 204
 205 #  if (defined(__FreeBSD__) || defined(__NetBSD__)) && defined(KERN_ARND)
 206 /*
 207  * sysctl_random(): Use sysctl() to read a random number from the kernel
 208  * Returns the number of bytes returned in buf on success, -1 on failure.
 209  */
 210 static ssize_t sysctl_random(char *buf, size_t buflen)
 211 {
 212     int mib[2];
 213     size_t done = 0;
 214     size_t len;
 215
 216     /*
 217      * Note: sign conversion between size_t and ssize_t is safe even
 218      * without a range check, see comment in syscall_random()
 219      */
 220
 221     /*
 222      * On FreeBSD old implementations returned longs, newer versions support
 223      * variable sizes up to 256 byte. The code below would not work properly
 224      * when the sysctl returns long and we want to request something not a
 225      * multiple of longs, which should never be the case.
 226      */
 227     if (!ossl_assert(buflen % sizeof(long) == 0)) {
 228         errno = EINVAL;
 229         return -1;
 230     }
 231
 232     /*
 233      * On NetBSD before 4.0 KERN_ARND was an alias for KERN_URND, and only
 234      * filled in an int, leaving the rest uninitialized. Since NetBSD 4.0
 235      * it returns a variable number of bytes with the current version supporting
 236      * up to 256 bytes.
 237      * Just return an error on older NetBSD versions.
 238      */
 239 #if   defined(__NetBSD__) && __NetBSD_Version__ < 400000000
 240     errno = ENOSYS;
 241     return -1;
 242 #endif
 243
 244     mib[0] = CTL_KERN;
 245     mib[1] = KERN_ARND;
 246
 247     do {
 248         len = buflen;
 249         if (sysctl(mib, 2, buf, &len, NULL, 0) == -1)
 250             return done > 0 ? done : -1;
 251         done += len;
 252         buf += len;
 253         buflen -= len;
 254     } while (buflen > 0);
 255
 256     return done;
 257 }
 258 #  endif
 259
 260 #  if defined(OPENSSL_RAND_SEED_GETRANDOM)
 261
 262 #   if defined(__linux) && !defined(__NR_getrandom)
 263 #    if defined(__arm__) && defined(__NR_SYSCALL_BASE)
 264 #     define __NR_getrandom    (__NR_SYSCALL_BASE+384)
 265 #    elif defined(__i386__)
 266 #     define __NR_getrandom    355
 267 #    elif defined(__x86_64__) && !defined(__ILP32__)
 268 #     define __NR_getrandom    318
 269 #    endif
 270 #   endif
 271
 272 /*
 273  * syscall_random(): Try to get random data using a system call
 274  * returns the number of bytes returned in buf, or < 0 on error.
 275  */
 276 static ssize_t syscall_random(void *buf, size_t buflen)
 277 {
 278     /*
 279      * Note: 'buflen' equals the size of the buffer which is used by the
 280      * get_entropy() callback of the RAND_DRBG. It is roughly bounded by
 281      *
 282      *   2 * RAND_POOL_FACTOR * (RAND_DRBG_STRENGTH / 8) = 2^14
 283      *
 284      * which is way below the OSSL_SSIZE_MAX limit. Therefore sign conversion
 285      * between size_t and ssize_t is safe even without a range check.
 286      */
 287
 288     /*
 289      * Do runtime detection to find getentropy().
 290      *
 291      * Known OSs that should support this:
 292      * - Darwin since 16 (OSX 10.12, IOS 10.0).
 293      * - Solaris since 11.3
 294      * - OpenBSD since 5.6
 295      * - Linux since 3.17 with glibc 2.25
 296      * - FreeBSD since 12.0 (1200061)
 297      */
 298 #  if defined(__GNUC__) && __GNUC__>=2 && defined(__ELF__) && !defined(__hpux)
 299     extern int getentropy(void *buffer, size_t length) __attribute__((weak));
 300
 301     if (getentropy != NULL)
 302         return getentropy(buf, buflen) == 0 ? (ssize_t)buflen : -1;
 303 #  elif !defined(FIPS_MODE)
 304     union {
 305         void *p;
 306         int (*f)(void *buffer, size_t length);
 307     } p_getentropy;
 308
 309     /*
 310      * We could cache the result of the lookup, but we normally don't
 311      * call this function often.
 312      */
 313     ERR_set_mark();
 314     p_getentropy.p = DSO_global_lookup("getentropy");
 315     ERR_pop_to_mark();
 316     if (p_getentropy.p != NULL)
 317         return p_getentropy.f(buf, buflen) == 0 ? (ssize_t)buflen : -1;
 318 #  endif
 319
 320     /* Linux supports this since version 3.17 */
 321 #  if defined(__linux) && defined(__NR_getrandom)
 322     return syscall(__NR_getrandom, buf, buflen, 0);
 323 #  elif (defined(__FreeBSD__) || defined(__NetBSD__)) && defined(KERN_ARND)
 324     return sysctl_random(buf, buflen);
 325 #  else
 326     errno = ENOSYS;
 327     return -1;
 328 #  endif
 329 }
 330 #  endif    /* defined(OPENSSL_RAND_SEED_GETRANDOM) */
 331
 332 #  if defined(OPENSSL_RAND_SEED_DEVRANDOM)
 333 static const char *random_device_paths[] = { DEVRANDOM };
 334 static struct random_device {
 335     int fd;
 336     dev_t dev;
 337     ino_t ino;
 338     mode_t mode;
 339     dev_t rdev;
 340 } random_devices[OSSL_NELEM(random_device_paths)];
 341 static int keep_random_devices_open = 1;
 342
 343 #   if defined(__linux) && defined(DEVRANDOM_WAIT)
 344 static void *shm_addr;
 345
 346 #    if !defined(FIPS_MODE)
 347 static void cleanup_shm(void)
 348 {
 349     shmdt(shm_addr);
 350 }
 351 #    endif
 352
 353 /*
 354  * Ensure that the system randomness source has been adequately seeded.
 355  * This is done by having the first start of libcrypto, wait until the device
 356  * /dev/random becomes able to supply a byte of entropy.  Subsequent starts
 357  * of the library and later reseedings do not need to do this.
 358  */
 359 static int wait_random_seeded(void)
 360 {
 361     static int seeded = OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID < 0;
 362     static const int kernel_version[] = { DEVRANDOM_SAFE_KERNEL };
 363     int kernel[2];
 364     int shm_id, fd, r;
 365     char c, *p;
 366     struct utsname un;
 367     fd_set fds;
 368
 369     if (!seeded) {
 370         /* See if anthing has created the global seeded indication */
 371         if ((shm_id = shmget(OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID, 1, 0)) == -1) {
 372             /*
 373              * Check the kernel's version and fail if it is too recent.
 374              *
 375              * Linux kernels from 4.8 onwards do not guarantee that
 376              * /dev/urandom is properly seeded when /dev/random becomes
 377              * readable.  However, such kernels support the getentropy(2)
 378              * system call and this should always succeed which renders
 379              * this alternative but essentially identical source moot.
 380              */
 381             if (uname(&un) == 0) {
 382                 kernel[0] = atoi(un.release);
 383                 p = strchr(un.release, '.');
 384                 kernel[1] = p == NULL ? 0 : atoi(p + 1);
 385                 if (kernel[0] > kernel_version[0]
 386                     || (kernel[0] == kernel_version[0]
 387                         && kernel[1] >= kernel_version[1])) {
 388                     return 0;
 389                 }
 390             }
 391             /* Open /dev/random and wait for it to be readable */
 392             if ((fd = open(DEVRANDOM_WAIT, O_RDONLY)) != -1) {
 393                 if (DEVRANDM_WAIT_USE_SELECT && fd < FD_SETSIZE) {
 394                     FD_ZERO(&fds);
 395                     FD_SET(fd, &fds);
 396                     while ((r = select(fd + 1, &fds, NULL, NULL, NULL)) < 0
 397                            && errno == EINTR);
 398                 } else {
 399                     while ((r = read(fd, &c, 1)) < 0 && errno == EINTR);
 400                 }
 401                 close(fd);
 402                 if (r == 1) {
 403                     seeded = 1;
 404                     /* Craete the shared memory indicator */
 405                     shm_id = shmget(OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID, 1,
 406                                     IPC_CREAT | S_IRUSR | S_IRGRP | S_IROTH);
 407                 }
 408             }
 409         }
 410         if (shm_id != -1) {
 411             seeded = 1;
 412             /*
 413              * Map the shared memory to prevent its premature destruction.
 414              * If this call fails, it isn't a big problem.
 415              */
 416             shm_addr = shmat(shm_id, NULL, SHM_RDONLY);
 417 #    ifndef FIPS_MODE
 418             /* TODO 3.0: The FIPS provider doesn't have OPENSSL_atexit */
 419             if (shm_addr != (void *)-1)
 420                 OPENSSL_atexit(&cleanup_shm);
 421 #    endif
 422         }
 423     }
 424     return seeded;
 425 }
 426 #   else /* defined __linux */
 427 static int wait_random_seeded(void)
 428 {
 429     return 1;
 430 }
 431 #   endif
 432
 433 /*
 434  * Verify that the file descriptor associated with the random source is
 435  * still valid. The rationale for doing this is the fact that it is not
 436  * uncommon for daemons to close all open file handles when daemonizing.
 437  * So the handle might have been closed or even reused for opening
 438  * another file.
 439  */
 440 static int check_random_device(struct random_device * rd)
 441 {
 442     struct stat st;
 443
 444     return rd->fd != -1
 445            && fstat(rd->fd, &st) != -1
 446            && rd->dev == st.st_dev
 447            && rd->ino == st.st_ino
 448            && ((rd->mode ^ st.st_mode) & ~(S_IRWXU | S_IRWXG | S_IRWXO)) == 0
 449            && rd->rdev == st.st_rdev;
 450 }
 451
 452 /*
 453  * Open a random device if required and return its file descriptor or -1 on error
 454  */
 455 static int get_random_device(size_t n)
 456 {
 457     struct stat st;
 458     struct random_device * rd = &random_devices[n];
 459
 460     /* reuse existing file descriptor if it is (still) valid */
 461     if (check_random_device(rd))
 462         return rd->fd;
 463
 464     /* open the random device ... */
 465     if ((rd->fd = open(random_device_paths[n], O_RDONLY)) == -1)
 466         return rd->fd;
 467
 468     /* ... and cache its relevant stat(2) data */
 469     if (fstat(rd->fd, &st) != -1) {
 470         rd->dev = st.st_dev;
 471         rd->ino = st.st_ino;
 472         rd->mode = st.st_mode;
 473         rd->rdev = st.st_rdev;
 474     } else {
 475         close(rd->fd);
 476         rd->fd = -1;
 477     }
 478
 479     return rd->fd;
 480 }
 481
 482 /*
 483  * Close a random device making sure it is a random device
 484  */
 485 static void close_random_device(size_t n)
 486 {
 487     struct random_device * rd = &random_devices[n];
 488
 489     if (check_random_device(rd))
 490         close(rd->fd);
 491     rd->fd = -1;
 492 }
 493
 494 int rand_pool_init(void)
 495 {
 496     size_t i;
 497
 498     for (i = 0; i < OSSL_NELEM(random_devices); i++)
 499         random_devices[i].fd = -1;
 500
 501     return 1;
 502 }
 503
 504 void rand_pool_cleanup(void)
 505 {
 506     size_t i;
 507
 508     for (i = 0; i < OSSL_NELEM(random_devices); i++)
 509         close_random_device(i);
 510 }
 511
 512 void rand_pool_keep_random_devices_open(int keep)
 513 {
 514     if (!keep)
 515         rand_pool_cleanup();
 516
 517     keep_random_devices_open = keep;
 518 }
 519
 520 #  else     /* !defined(OPENSSL_RAND_SEED_DEVRANDOM) */
 521
 522 int rand_pool_init(void)
 523 {
 524     return 1;
 525 }
 526
 527 void rand_pool_cleanup(void)
 528 {
 529 }
 530
 531 void rand_pool_keep_random_devices_open(int keep)
 532 {
 533 }
 534
 535 #  endif    /* defined(OPENSSL_RAND_SEED_DEVRANDOM) */
 536
 537 /*
 538  * Try the various seeding methods in turn, exit when successful.
 539  *
 540  * TODO(DRBG): If more than one entropy source is available, is it
 541  * preferable to stop as soon as enough entropy has been collected
 542  * (as favored by @rsalz) or should one rather be defensive and add
 543  * more entropy than requested and/or from different sources?
 544  *
 545  * Currently, the user can select multiple entropy sources in the
 546  * configure step, yet in practice only the first available source
 547  * will be used. A more flexible solution has been requested, but
 548  * currently it is not clear how this can be achieved without
 549  * overengineering the problem. There are many parameters which
 550  * could be taken into account when selecting the order and amount
 551  * of input from the different entropy sources (trust, quality,
 552  * possibility of blocking).
 553  */
 554 size_t rand_pool_acquire_entropy(RAND_POOL *pool)
 555 {
 556 #  if defined(OPENSSL_RAND_SEED_NONE)
 557     return rand_pool_entropy_available(pool);
 558 #  else
 559     size_t bytes_needed;
 560     size_t entropy_available = 0;
 561     unsigned char *buffer;
 562
 563 #   if defined(OPENSSL_RAND_SEED_GETRANDOM)
 564     {
 565         ssize_t bytes;
 566         /* Maximum allowed number of consecutive unsuccessful attempts */
 567         int attempts = 3;
 568
 569         bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
 570         while (bytes_needed != 0 && attempts-- > 0) {
 571             buffer = rand_pool_add_begin(pool, bytes_needed);
 572             bytes = syscall_random(buffer, bytes_needed);
 573             if (bytes > 0) {
 574                 rand_pool_add_end(pool, bytes, 8 * bytes);
 575                 bytes_needed -= bytes;
 576                 attempts = 3; /* reset counter after successful attempt */
 577             } else if (bytes < 0 && errno != EINTR) {
 578                 break;
 579             }
 580         }
 581     }
 582     entropy_available = rand_pool_entropy_available(pool);
 583     if (entropy_available > 0)
 584         return entropy_available;
 585 #   endif
 586
 587 #   if defined(OPENSSL_RAND_SEED_LIBRANDOM)
 588     {
 589         /* Not yet implemented. */
 590     }
 591 #   endif
 592
 593 #   if defined(OPENSSL_RAND_SEED_DEVRANDOM)
 594     if (wait_random_seeded()) {
 595         size_t i;
 596
 597         bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
 598         for (i = 0; bytes_needed > 0 && i < OSSL_NELEM(random_device_paths);
 599              i++) {
 600             ssize_t bytes = 0;
 601             /* Maximum number of consecutive unsuccessful attempts */
 602             int attempts = 3;
 603             const int fd = get_random_device(i);
 604
 605             if (fd == -1)
 606                 continue;
 607
 608             while (bytes_needed != 0 && attempts-- > 0) {
 609                 buffer = rand_pool_add_begin(pool, bytes_needed);
 610                 bytes = read(fd, buffer, bytes_needed);
 611
 612                 if (bytes > 0) {
 613                     rand_pool_add_end(pool, bytes, 8 * bytes);
 614                     bytes_needed -= bytes;
 615                     attempts = 3; /* reset counter on successful attempt */
 616                 } else if (bytes < 0 && errno != EINTR) {
 617                     break;
 618                 }
 619             }
 620             if (bytes < 0 || !keep_random_devices_open)
 621                 close_random_device(i);
 622
 623             bytes_needed = rand_pool_bytes_needed(pool, 1);
 624         }
 625         entropy_available = rand_pool_entropy_available(pool);
 626         if (entropy_available > 0)
 627             return entropy_available;
 628     }
 629 #   endif
 630
 631 #   if defined(OPENSSL_RAND_SEED_RDTSC)
 632     entropy_available = rand_acquire_entropy_from_tsc(pool);
 633     if (entropy_available > 0)
 634         return entropy_available;
 635 #   endif
 636
 637 #   if defined(OPENSSL_RAND_SEED_RDCPU)
 638     entropy_available = rand_acquire_entropy_from_cpu(pool);
 639     if (entropy_available > 0)
 640         return entropy_available;
 641 #   endif
 642
 643 #   if defined(OPENSSL_RAND_SEED_EGD)
 644     bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
 645     if (bytes_needed > 0) {
 646         static const char *paths[] = { DEVRANDOM_EGD, NULL };
 647         int i;
 648
 649         for (i = 0; paths[i] != NULL; i++) {
 650             buffer = rand_pool_add_begin(pool, bytes_needed);
 651             if (buffer != NULL) {
 652                 size_t bytes = 0;
 653                 int num = RAND_query_egd_bytes(paths[i],
 654                                                buffer, (int)bytes_needed);
 655                 if (num == (int)bytes_needed)
 656                     bytes = bytes_needed;
 657
 658                 rand_pool_add_end(pool, bytes, 8 * bytes);
 659                 entropy_available = rand_pool_entropy_available(pool);
 660             }
 661             if (entropy_available > 0)
 662                 return entropy_available;
 663         }
 664     }
 665 #   endif
 666
 667     return rand_pool_entropy_available(pool);
 668 #  endif
 669 }
 670 # endif
 671 #endif
 672
 673 #if (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS)) \
 674      || defined(__DJGPP__)
 675 int rand_pool_add_nonce_data(RAND_POOL *pool)
 676 {
 677     struct {
 678         pid_t pid;
 679         CRYPTO_THREAD_ID tid;
 680         uint64_t time;
 681     } data;
 682
 683     /* Erase the entire structure including any padding */
 684     memset(&data, 0, sizeof(data));
 685
 686     /*
 687      * Add process id, thread id, and a high resolution timestamp to
 688      * ensure that the nonce is unique with high probability for
 689      * different process instances.
 690      */
 691     data.pid = getpid();
 692     data.tid = CRYPTO_THREAD_get_current_id();
 693     data.time = get_time_stamp();
 694
 695     return rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0);
 696 }
 697
 698 int rand_pool_add_additional_data(RAND_POOL *pool)
 699 {
 700     struct {
 701         CRYPTO_THREAD_ID tid;
 702         uint64_t time;
 703     } data;
 704
 705     /* Erase the entire structure including any padding */
 706     memset(&data, 0, sizeof(data));
 707
 708     /*
 709      * Add some noise from the thread id and a high resolution timer.
 710      * The thread id adds a little randomness if the drbg is accessed
 711      * concurrently (which is the case for the <master> drbg).
 712      */
 713     data.tid = CRYPTO_THREAD_get_current_id();
 714     data.time = get_timer_bits();
 715
 716     return rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0);
 717 }
 718
 719
 720 /*
 721  * Get the current time with the highest possible resolution
 722  *
 723  * The time stamp is added to the nonce, so it is optimized for not repeating.
 724  * The current time is ideal for this purpose, provided the computer's clock
 725  * is synchronized.
 726  */
 727 static uint64_t get_time_stamp(void)
 728 {
 729 # if defined(OSSL_POSIX_TIMER_OKAY)
 730     {
 731         struct timespec ts;
 732
 733         if (clock_gettime(CLOCK_REALTIME, &ts) == 0)
 734             return TWO32TO64(ts.tv_sec, ts.tv_nsec);
 735     }
 736 # endif
 737 # if defined(__unix__) \
 738      || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
 739     {
 740         struct timeval tv;
 741
 742         if (gettimeofday(&tv, NULL) == 0)
 743             return TWO32TO64(tv.tv_sec, tv.tv_usec);
 744     }
 745 # endif
 746     return time(NULL);
 747 }
 748
 749 /*
 750  * Get an arbitrary timer value of the highest possible resolution
 751  *
 752  * The timer value is added as random noise to the additional data,
 753  * which is not considered a trusted entropy sourec, so any result
 754  * is acceptable.
 755  */
 756 static uint64_t get_timer_bits(void)
 757 {
 758     uint64_t res = OPENSSL_rdtsc();
 759
 760     if (res != 0)
 761         return res;
 762
 763 # if defined(__sun) || defined(__hpux)
 764     return gethrtime();
 765 # elif defined(_AIX)
 766     {
 767         timebasestruct_t t;
 768
 769         read_wall_time(&t, TIMEBASE_SZ);
 770         return TWO32TO64(t.tb_high, t.tb_low);
 771     }
 772 # elif defined(OSSL_POSIX_TIMER_OKAY)
 773     {
 774         struct timespec ts;
 775
 776 #  ifdef CLOCK_BOOTTIME
 777 #   define CLOCK_TYPE CLOCK_BOOTTIME
 778 #  elif defined(_POSIX_MONOTONIC_CLOCK)
 779 #   define CLOCK_TYPE CLOCK_MONOTONIC
 780 #  else
 781 #   define CLOCK_TYPE CLOCK_REALTIME
 782 #  endif
 783
 784         if (clock_gettime(CLOCK_TYPE, &ts) == 0)
 785             return TWO32TO64(ts.tv_sec, ts.tv_nsec);
 786     }
 787 # endif
 788 # if defined(__unix__) \
 789      || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
 790     {
 791         struct timeval tv;
 792
 793         if (gettimeofday(&tv, NULL) == 0)
 794             return TWO32TO64(tv.tv_sec, tv.tv_usec);
 795     }
 796 # endif
 797     return time(NULL);
 798 }
 799 #endif /* defined(OPENSSL_SYS_UNIX) || defined(__DJGPP__) */