crypto/rand/rand_unix.c

   1 /*
   2  * Copyright 1995-2018 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 #define _GNU_SOURCE
  11 #include "e_os.h"
  12 #include <stdio.h>
  13 #include "internal/cryptlib.h"
  14 #include <openssl/rand.h>
  15 #include "rand_lcl.h"
  16 #include "internal/rand_int.h"
  17 #include <stdio.h>
  18 #if defined(__linux)
  19 # include <sys/syscall.h>
  20 #endif
  21 #if defined(__FreeBSD__)
  22 # include <sys/types.h>
  23 # include <sys/sysctl.h>
  24 # include <sys/param.h>
  25 #endif
  26 #if defined(__OpenBSD__)
  27 # include <sys/param.h>
  28 #endif
  29 #ifdef OPENSSL_SYS_UNIX
  30 # include <sys/types.h>
  31 # include <unistd.h>
  32 # include <sys/time.h>
  33
  34 static uint64_t get_time_stamp(void);
  35 static uint64_t get_timer_bits(void);
  36
  37 /* Macro to convert two thirty two bit values into a sixty four bit one */
  38 # define TWO32TO64(a, b) ((((uint64_t)(a)) << 32) + (b))
  39
  40 /*
  41  * Check for the existence and support of POSIX timers.  The standard
  42  * says that the _POSIX_TIMERS macro will have a positive value if they
  43  * are available.
  44  *
  45  * However, we want an additional constraint: that the timer support does
  46  * not require an extra library dependency.  Early versions of glibc
  47  * require -lrt to be specified on the link line to access the timers,
  48  * so this needs to be checked for.
  49  *
  50  * It is worse because some libraries define __GLIBC__ but don't
  51  * support the version testing macro (e.g. uClibc).  This means
  52  * an extra check is needed.
  53  *
  54  * The final condition is:
  55  *      "have posix timers and either not glibc or glibc without -lrt"
  56  *
  57  * The nested #if sequences are required to avoid using a parameterised
  58  * macro that might be undefined.
  59  */
  60 # undef OSSL_POSIX_TIMER_OKAY
  61 # if defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0
  62 #  if defined(__GLIBC__)
  63 #   if defined(__GLIBC_PREREQ)
  64 #    if __GLIBC_PREREQ(2, 17)
  65 #     define OSSL_POSIX_TIMER_OKAY
  66 #    endif
  67 #   endif
  68 #  else
  69 #   define OSSL_POSIX_TIMER_OKAY
  70 #  endif
  71 # endif
  72 #endif
  73
  74 int syscall_random(void *buf, size_t buflen);
  75
  76 #if (defined(OPENSSL_SYS_VXWORKS) || defined(OPENSSL_SYS_UEFI)) && \
  77         !defined(OPENSSL_RAND_SEED_NONE)
  78 # error "UEFI and VXWorks only support seeding NONE"
  79 #endif
  80
  81 #if !(defined(OPENSSL_SYS_WINDOWS) || defined(OPENSSL_SYS_WIN32) \
  82     || defined(OPENSSL_SYS_VMS) || defined(OPENSSL_SYS_VXWORKS) \
  83     || defined(OPENSSL_SYS_UEFI))
  84
  85 # if defined(OPENSSL_SYS_VOS)
  86
  87 #  ifndef OPENSSL_RAND_SEED_OS
  88 #   error "Unsupported seeding method configured; must be os"
  89 #  endif
  90
  91 #  if defined(OPENSSL_SYS_VOS_HPPA) && defined(OPENSSL_SYS_VOS_IA32)
  92 #   error "Unsupported HP-PA and IA32 at the same time."
  93 #  endif
  94 #  if !defined(OPENSSL_SYS_VOS_HPPA) && !defined(OPENSSL_SYS_VOS_IA32)
  95 #   error "Must have one of HP-PA or IA32"
  96 #  endif
  97
  98 /*
  99  * The following algorithm repeatedly samples the real-time clock (RTC) to
 100  * generate a sequence of unpredictable data.  The algorithm relies upon the
 101  * uneven execution speed of the code (due to factors such as cache misses,
 102  * interrupts, bus activity, and scheduling) and upon the rather large
 103  * relative difference between the speed of the clock and the rate at which
 104  * it can be read.  If it is ported to an environment where execution speed
 105  * is more constant or where the RTC ticks at a much slower rate, or the
 106  * clock can be read with fewer instructions, it is likely that the results
 107  * would be far more predictable.  This should only be used for legacy
 108  * platforms.
 109  *
 110  * As a precaution, we assume only 2 bits of entropy per byte.
 111  */
 112 size_t rand_pool_acquire_entropy(RAND_POOL *pool)
 113 {
 114     short int code;
 115     int i, k;
 116     size_t bytes_needed;
 117     struct timespec ts;
 118     unsigned char v;
 119 #  ifdef OPENSSL_SYS_VOS_HPPA
 120     long duration;
 121     extern void s$sleep(long *_duration, short int *_code);
 122 #  else
 123     long long duration;
 124     extern void s$sleep2(long long *_duration, short int *_code);
 125 #  endif
 126
 127     bytes_needed = rand_pool_bytes_needed(pool, 2 /*entropy_per_byte*/);
 128
 129     for (i = 0; i < bytes_needed; i++) {
 130         /*
 131          * burn some cpu; hope for interrupts, cache collisions, bus
 132          * interference, etc.
 133          */
 134         for (k = 0; k < 99; k++)
 135             ts.tv_nsec = random();
 136
 137 #  ifdef OPENSSL_SYS_VOS_HPPA
 138         /* sleep for 1/1024 of a second (976 us).  */
 139         duration = 1;
 140         s$sleep(&duration, &code);
 141 #  else
 142         /* sleep for 1/65536 of a second (15 us).  */
 143         duration = 1;
 144         s$sleep2(&duration, &code);
 145 #  endif
 146
 147         /* Get wall clock time, take 8 bits. */
 148         clock_gettime(CLOCK_REALTIME, &ts);
 149         v = (unsigned char)(ts.tv_nsec & 0xFF);
 150         rand_pool_add(pool, arg, &v, sizeof(v) , 2);
 151     }
 152     return rand_pool_entropy_available(pool);
 153 }
 154
 155 # else
 156
 157 #  if defined(OPENSSL_RAND_SEED_EGD) && \
 158         (defined(OPENSSL_NO_EGD) || !defined(DEVRANDOM_EGD))
 159 #   error "Seeding uses EGD but EGD is turned off or no device given"
 160 #  endif
 161
 162 #  if defined(OPENSSL_RAND_SEED_DEVRANDOM) && !defined(DEVRANDOM)
 163 #   error "Seeding uses urandom but DEVRANDOM is not configured"
 164 #  endif
 165
 166 #  if defined(__GLIBC__) && defined(__GLIBC_PREREQ)
 167 #   if __GLIBC_PREREQ(2, 25)
 168 #    define OPENSSL_HAVE_GETRANDOM
 169 #   endif
 170 #  endif
 171
 172 #  if (defined(__FreeBSD__) && __FreeBSD_version >= 1200061)
 173 #   define OPENSSL_HAVE_GETRANDOM
 174 #  endif
 175
 176 #  if defined(OPENSSL_HAVE_GETRANDOM)
 177 #   include <sys/random.h>
 178 #  endif
 179
 180 #  if defined(OPENSSL_RAND_SEED_OS)
 181 #   if !defined(DEVRANDOM)
 182 #    error "OS seeding requires DEVRANDOM to be configured"
 183 #   endif
 184 #   define OPENSSL_RAND_SEED_GETRANDOM
 185 #   define OPENSSL_RAND_SEED_DEVRANDOM
 186 #  endif
 187
 188 #  if defined(OPENSSL_RAND_SEED_LIBRANDOM)
 189 #   error "librandom not (yet) supported"
 190 #  endif
 191
 192 #  if defined(__FreeBSD__) && defined(KERN_ARND)
 193 /*
 194  * sysctl_random(): Use sysctl() to read a random number from the kernel
 195  * Returns the size on success, 0 on failure.
 196  */
 197 static size_t sysctl_random(char *buf, size_t buflen)
 198 {
 199     int mib[2];
 200     size_t done = 0;
 201     size_t len;
 202
 203     /*
 204      * Old implementations returned longs, newer versions support variable
 205      * sizes up to 256 byte. The code below would not work properly when
 206      * the sysctl returns long and we want to request something not a multiple
 207      * of longs, which should never be the case.
 208      */
 209     ossl_assert(buflen % sizeof(long) == 0);
 210
 211     mib[0] = CTL_KERN;
 212     mib[1] = KERN_ARND;
 213
 214     do {
 215         len = buflen;
 216         if (sysctl(mib, 2, buf, &len, NULL, 0) == -1)
 217             return done;
 218         done += len;
 219         buf += len;
 220         buflen -= len;
 221     } while (buflen > 0);
 222
 223     return done;
 224 }
 225 #  endif
 226
 227 /*
 228  * syscall_random(): Try to get random data using a system call
 229  * returns the number of bytes returned in buf, or <= 0 on error.
 230  */
 231 int syscall_random(void *buf, size_t buflen)
 232 {
 233 #  if defined(OPENSSL_HAVE_GETRANDOM)
 234     return (int)getrandom(buf, buflen, 0);
 235 #  endif
 236
 237 #  if defined(__linux) && defined(SYS_getrandom)
 238     return (int)syscall(SYS_getrandom, buf, buflen, 0);
 239 #  endif
 240
 241 #  if defined(__FreeBSD__) && defined(KERN_ARND)
 242     return (int)sysctl_random(buf, buflen);
 243 #  endif
 244
 245    /* Supported since OpenBSD 5.6 */
 246 #  if defined(__OpenBSD__) && OpenBSD >= 201411
 247     return getentropy(buf, buflen);
 248 #  endif
 249
 250     return -1;
 251 }
 252
 253 /*
 254  * Try the various seeding methods in turn, exit when successful.
 255  *
 256  * TODO(DRBG): If more than one entropy source is available, is it
 257  * preferable to stop as soon as enough entropy has been collected
 258  * (as favored by @rsalz) or should one rather be defensive and add
 259  * more entropy than requested and/or from different sources?
 260  *
 261  * Currently, the user can select multiple entropy sources in the
 262  * configure step, yet in practice only the first available source
 263  * will be used. A more flexible solution has been requested, but
 264  * currently it is not clear how this can be achieved without
 265  * overengineering the problem. There are many parameters which
 266  * could be taken into account when selecting the order and amount
 267  * of input from the different entropy sources (trust, quality,
 268  * possibility of blocking).
 269  */
 270 size_t rand_pool_acquire_entropy(RAND_POOL *pool)
 271 {
 272 #  ifdef OPENSSL_RAND_SEED_NONE
 273     return rand_pool_entropy_available(pool);
 274 #  else
 275     size_t bytes_needed;
 276     size_t entropy_available = 0;
 277     unsigned char *buffer;
 278
 279 #   ifdef OPENSSL_RAND_SEED_GETRANDOM
 280     bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/);
 281     buffer = rand_pool_add_begin(pool, bytes_needed);
 282     if (buffer != NULL) {
 283         size_t bytes = 0;
 284
 285         if (syscall_random(buffer, bytes_needed) == (int)bytes_needed)
 286             bytes = bytes_needed;
 287
 288         rand_pool_add_end(pool, bytes, 8 * bytes);
 289         entropy_available = rand_pool_entropy_available(pool);
 290     }
 291     if (entropy_available > 0)
 292         return entropy_available;
 293 #   endif
 294
 295 #   if defined(OPENSSL_RAND_SEED_LIBRANDOM)
 296     {
 297         /* Not yet implemented. */
 298     }
 299 #   endif
 300
 301 #   ifdef OPENSSL_RAND_SEED_DEVRANDOM
 302     bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/);
 303     if (bytes_needed > 0) {
 304         static const char *paths[] = { DEVRANDOM, NULL };
 305         FILE *fp;
 306         int i;
 307
 308         for (i = 0; paths[i] != NULL; i++) {
 309             if ((fp = fopen(paths[i], "rb")) == NULL)
 310                 continue;
 311             setbuf(fp, NULL);
 312             buffer = rand_pool_add_begin(pool, bytes_needed);
 313             if (buffer != NULL) {
 314                 size_t bytes = 0;
 315                 if (fread(buffer, 1, bytes_needed, fp) == bytes_needed)
 316                     bytes = bytes_needed;
 317
 318                 rand_pool_add_end(pool, bytes, 8 * bytes);
 319                 entropy_available = rand_pool_entropy_available(pool);
 320             }
 321             fclose(fp);
 322             if (entropy_available > 0)
 323                 return entropy_available;
 324
 325             bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/);
 326         }
 327     }
 328 #   endif
 329
 330 #   ifdef OPENSSL_RAND_SEED_RDTSC
 331     entropy_available = rand_acquire_entropy_from_tsc(pool);
 332     if (entropy_available > 0)
 333         return entropy_available;
 334 #   endif
 335
 336 #   ifdef OPENSSL_RAND_SEED_RDCPU
 337     entropy_available = rand_acquire_entropy_from_cpu(pool);
 338     if (entropy_available > 0)
 339         return entropy_available;
 340 #   endif
 341
 342 #   ifdef OPENSSL_RAND_SEED_EGD
 343     bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/);
 344     if (bytes_needed > 0) {
 345         static const char *paths[] = { DEVRANDOM_EGD, NULL };
 346         int i;
 347
 348         for (i = 0; paths[i] != NULL; i++) {
 349             buffer = rand_pool_add_begin(pool, bytes_needed);
 350             if (buffer != NULL) {
 351                 size_t bytes = 0;
 352                 int num = RAND_query_egd_bytes(paths[i],
 353                                                buffer, (int)bytes_needed);
 354                 if (num == (int)bytes_needed)
 355                     bytes = bytes_needed;
 356
 357                 rand_pool_add_end(pool, bytes, 8 * bytes);
 358                 entropy_available = rand_pool_entropy_available(pool);
 359             }
 360             if (entropy_available > 0)
 361                 return entropy_available;
 362         }
 363     }
 364 #   endif
 365
 366     return rand_pool_entropy_available(pool);
 367 #  endif
 368 }
 369 # endif
 370 #endif
 371
 372 #ifdef OPENSSL_SYS_UNIX
 373 int rand_pool_add_nonce_data(RAND_POOL *pool)
 374 {
 375     struct {
 376         pid_t pid;
 377         CRYPTO_THREAD_ID tid;
 378         uint64_t time;
 379     } data = { 0 };
 380
 381     /*
 382      * Add process id, thread id, and a high resolution timestamp to
 383      * ensure that the nonce is unique whith high probability for
 384      * different process instances.
 385      */
 386     data.pid = getpid();
 387     data.tid = CRYPTO_THREAD_get_current_id();
 388     data.time = get_time_stamp();
 389
 390     return rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0);
 391 }
 392
 393 int rand_pool_add_additional_data(RAND_POOL *pool)
 394 {
 395     struct {
 396         CRYPTO_THREAD_ID tid;
 397         uint64_t time;
 398     } data = { 0 };
 399
 400     /*
 401      * Add some noise from the thread id and a high resolution timer.
 402      * The thread id adds a little randomness if the drbg is accessed
 403      * concurrently (which is the case for the <master> drbg).
 404      */
 405     data.tid = CRYPTO_THREAD_get_current_id();
 406     data.time = get_timer_bits();
 407
 408     return rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0);
 409 }
 410
 411
 412
 413 /*
 414  * Get the current time with the highest possible resolution
 415  *
 416  * The time stamp is added to the nonce, so it is optimized for not repeating.
 417  * The current time is ideal for this purpose, provided the computer's clock
 418  * is synchronized.
 419  */
 420 static uint64_t get_time_stamp(void)
 421 {
 422 # if defined(OSSL_POSIX_TIMER_OKAY)
 423     {
 424         struct timespec ts;
 425
 426         if (clock_gettime(CLOCK_REALTIME, &ts) == 0)
 427             return TWO32TO64(ts.tv_sec, ts.tv_nsec);
 428     }
 429 # endif
 430 # if defined(__unix__) \
 431      || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
 432     {
 433         struct timeval tv;
 434
 435         if (gettimeofday(&tv, NULL) == 0)
 436             return TWO32TO64(tv.tv_sec, tv.tv_usec);
 437     }
 438 # endif
 439     return time(NULL);
 440 }
 441
 442 /*
 443  * Get an arbitrary timer value of the highest possible resolution
 444  *
 445  * The timer value is added as random noise to the additional data,
 446  * which is not considered a trusted entropy sourec, so any result
 447  * is acceptable.
 448  */
 449 static uint64_t get_timer_bits(void)
 450 {
 451     uint64_t res = OPENSSL_rdtsc();
 452
 453     if (res != 0)
 454         return res;
 455
 456 # if defined(__sun) || defined(__hpux)
 457     return gethrtime();
 458 # elif defined(_AIX)
 459     {
 460         timebasestruct_t t;
 461
 462         read_wall_time(&t, TIMEBASE_SZ);
 463         return TWO32TO64(t.tb_high, t.tb_low);
 464     }
 465 # elif defined(OSSL_POSIX_TIMER_OKAY)
 466     {
 467         struct timespec ts;
 468
 469 #  ifdef CLOCK_BOOTTIME
 470 #   define CLOCK_TYPE CLOCK_BOOTTIME
 471 #  elif defined(_POSIX_MONOTONIC_CLOCK)
 472 #   define CLOCK_TYPE CLOCK_MONOTONIC
 473 #  else
 474 #   define CLOCK_TYPE CLOCK_REALTIME
 475 #  endif
 476
 477         if (clock_gettime(CLOCK_TYPE, &ts) == 0)
 478             return TWO32TO64(ts.tv_sec, ts.tv_nsec);
 479     }
 480 # endif
 481 # if defined(__unix__) \
 482      || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
 483     {
 484         struct timeval tv;
 485
 486         if (gettimeofday(&tv, NULL) == 0)
 487             return TWO32TO64(tv.tv_sec, tv.tv_usec);
 488     }
 489 # endif
 490     return time(NULL);
 491 }
 492 #endif