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