crypto/rand/rand_unix.c

   1 /*
   2  * Copyright 1995-2017 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 <stdio.h>
  16
  17 #if (defined(OPENSSL_SYS_VXWORKS) || defined(OPENSSL_SYS_UEFI)) && \
  18         !defined(OPENSSL_RAND_SEED_NONE)
  19 # error "UEFI and VXWorks only support seeding NONE"
  20 #endif
  21
  22 #if !(defined(OPENSSL_SYS_WINDOWS) || defined(OPENSSL_SYS_WIN32) \
  23     || defined(OPENSSL_SYS_VMS) || defined(OPENSSL_SYS_VXWORKS) \
  24     || defined(OPENSSL_SYS_UEFI))
  25
  26 # if defined(OPENSSL_SYS_VOS)
  27
  28 #  ifndef OPENSSL_RAND_SEED_OS
  29 #   error "Unsupported seeding method configured; must be os"
  30 #  endif
  31
  32 #  if defined(OPENSSL_SYS_VOS_HPPA) && defined(OPENSSL_SYS_VOS_IA32)
  33 #   error "Unsupported HP-PA and IA32 at the same time."
  34 #  endif
  35 #  if !defined(OPENSSL_SYS_VOS_HPPA) && !defined(OPENSSL_SYS_VOS_IA32)
  36 #   error "Must have one of HP-PA or IA32"
  37 #  endif
  38
  39 /*
  40  * The following algorithm repeatedly samples the real-time clock (RTC) to
  41  * generate a sequence of unpredictable data.  The algorithm relies upon the
  42  * uneven execution speed of the code (due to factors such as cache misses,
  43  * interrupts, bus activity, and scheduling) and upon the rather large
  44  * relative difference between the speed of the clock and the rate at which
  45  * it can be read.  If it is ported to an environment where execution speed
  46  * is more constant or where the RTC ticks at a much slower rate, or the
  47  * clock can be read with fewer instructions, it is likely that the results
  48  * would be far more predictable.  This should only be used for legacy
  49  * platforms.
  50  *
  51  * As a precaution, we assume only 2 bits of entropy per byte.
  52  */
  53 size_t RAND_POOL_acquire_entropy(RAND_POOL *pool)
  54 {
  55     short int code;
  56     gid_t curr_gid;
  57     pid_t curr_pid;
  58     uid_t curr_uid;
  59     int i, k;
  60     size_t bytes_needed;
  61     struct timespec ts;
  62     unsigned char v;
  63 #  ifdef OPENSSL_SYS_VOS_HPPA
  64     long duration;
  65     extern void s$sleep(long *_duration, short int *_code);
  66 #  else
  67     long long duration;
  68     extern void s$sleep2(long long *_duration, short int *_code);
  69 #  endif
  70
  71     /*
  72      * Seed with the gid, pid, and uid, to ensure *some* variation between
  73      * different processes.
  74      */
  75     curr_gid = getgid();
  76     RAND_POOL_add(pool, &curr_gid, sizeof(curr_gid), 0);
  77     curr_pid = getpid();
  78     RAND_POOL_add(pool, &curr_pid, sizeof(curr_pid), 0);
  79     curr_uid = getuid();
  80     RAND_POOL_add(pool, &curr_uid, sizeof(curr_uid), 0);
  81
  82     bytes_needed = RAND_POOL_bytes_needed(pool, 2 /*entropy_per_byte*/);
  83
  84     for (i = 0; i < bytes_needed; i++) {
  85         /*
  86          * burn some cpu; hope for interrupts, cache collisions, bus
  87          * interference, etc.
  88          */
  89         for (k = 0; k < 99; k++)
  90             ts.tv_nsec = random();
  91
  92 #  ifdef OPENSSL_SYS_VOS_HPPA
  93         /* sleep for 1/1024 of a second (976 us).  */
  94         duration = 1;
  95         s$sleep(&duration, &code);
  96 #  else
  97         /* sleep for 1/65536 of a second (15 us).  */
  98         duration = 1;
  99         s$sleep2(&duration, &code);
 100 #  endif
 101
 102         /* Get wall clock time, take 8 bits. */
 103         clock_gettime(CLOCK_REALTIME, &ts);
 104         v = (unsigned char)(ts.tv_nsec & 0xFF);
 105         RAND_POOL_add(pool, arg, &v, sizeof(v) , 2);
 106     }
 107     return RAND_POOL_entropy_available(pool);
 108 }
 109
 110 # else
 111
 112 #  if defined(OPENSSL_RAND_SEED_EGD) && \
 113         (defined(OPENSSL_NO_EGD) || !defined(DEVRANDOM_EGD))
 114 #   error "Seeding uses EGD but EGD is turned off or no device given"
 115 #  endif
 116
 117 #  if defined(OPENSSL_RAND_SEED_DEVRANDOM) && !defined(DEVRANDOM)
 118 #   error "Seeding uses urandom but DEVRANDOM is not configured"
 119 #  endif
 120
 121 #  if defined(OPENSSL_RAND_SEED_OS)
 122 #   if !defined(DEVRANDOM)
 123 #    error "OS seeding requires DEVRANDOM to be configured"
 124 #   endif
 125 #   define OPENSSL_RAND_SEED_DEVRANDOM
 126 #   if defined(__GLIBC__) && defined(__GLIBC_PREREQ)
 127 #    if __GLIBC_PREREQ(2, 25)
 128 #     define OPENSSL_RAND_SEED_GETRANDOM
 129 #    endif
 130 #   endif
 131 #  endif
 132
 133 #  ifdef OPENSSL_RAND_SEED_GETRANDOM
 134 #   include <sys/random.h>
 135 #  endif
 136
 137 #  if defined(OPENSSL_RAND_SEED_LIBRANDOM)
 138 #   error "librandom not (yet) supported"
 139 #  endif
 140
 141 /*
 142  * Try the various seeding methods in turn, exit when successful.
 143  *
 144  * TODO(DRBG): If more than one entropy source is available, is it
 145  * preferable to stop as soon as enough entropy has been collected
 146  * (as favored by @rsalz) or should one rather be defensive and add
 147  * more entropy than requested and/or from different sources?
 148  *
 149  * Currently, the user can select multiple entropy sources in the
 150  * configure step, yet in practice only the first available source
 151  * will be used. A more flexible solution has been requested, but
 152  * currently it is not clear how this can be achieved without
 153  * overengineering the problem. There are many parameters which
 154  * could be taken into account when selecting the order and amount
 155  * of input from the different entropy sources (trust, quality,
 156  * possibility of blocking).
 157  */
 158 size_t RAND_POOL_acquire_entropy(RAND_POOL *pool)
 159 {
 160 #  ifdef OPENSSL_RAND_SEED_NONE
 161     return RAND_POOL_entropy_available(pool);
 162 #  else
 163     size_t bytes_needed;
 164     size_t entropy_available = 0;
 165     unsigned char *buffer;
 166
 167 #   ifdef OPENSSL_RAND_SEED_GETRANDOM
 168     bytes_needed = RAND_POOL_bytes_needed(pool, 8 /*entropy_per_byte*/);
 169     buffer = RAND_POOL_add_begin(pool, bytes_needed);
 170     if (buffer != NULL) {
 171         size_t bytes = 0;
 172
 173         if (getrandom(buffer, bytes_needed, 0) == (int)bytes_needed)
 174             bytes = bytes_needed;
 175
 176         entropy_available = RAND_POOL_add_end(pool, bytes, 8 * bytes);
 177     }
 178     if (entropy_available > 0)
 179         return entropy_available;
 180 #   endif
 181
 182 #   if defined(OPENSSL_RAND_SEED_LIBRANDOM)
 183     {
 184         /* Not yet implemented. */
 185     }
 186 #   endif
 187
 188 #   ifdef OPENSSL_RAND_SEED_DEVRANDOM
 189     bytes_needed = RAND_POOL_bytes_needed(pool, 8 /*entropy_per_byte*/);
 190     if (bytes_needed > 0) {
 191         static const char *paths[] = { DEVRANDOM, NULL };
 192         FILE *fp;
 193         int i;
 194
 195         for (i = 0; paths[i] != NULL; i++) {
 196             if ((fp = fopen(paths[i], "rb")) == NULL)
 197                 continue;
 198             setbuf(fp, NULL);
 199             buffer = RAND_POOL_add_begin(pool, bytes_needed);
 200             if (buffer != NULL) {
 201                 size_t bytes = 0;
 202                 if (fread(buffer, 1, bytes_needed, fp) == bytes_needed)
 203                     bytes = bytes_needed;
 204
 205                 entropy_available = RAND_POOL_add_end(pool, bytes, 8 * bytes);
 206             }
 207             fclose(fp);
 208             if (entropy_available > 0)
 209                 return entropy_available;
 210
 211             bytes_needed = RAND_POOL_bytes_needed(pool, 8 /*entropy_per_byte*/);
 212         }
 213     }
 214 #   endif
 215
 216 #   ifdef OPENSSL_RAND_SEED_RDTSC
 217     entropy_available = rand_acquire_entropy_from_tsc(pool);
 218     if (entropy_available > 0)
 219         return entropy_available;
 220 #   endif
 221
 222 #   ifdef OPENSSL_RAND_SEED_RDCPU
 223     entropy_available = rand_acquire_entropy_from_cpu(pool);
 224     if (entropy_available > 0)
 225         return entropy_available;
 226 #   endif
 227
 228 #   ifdef OPENSSL_RAND_SEED_EGD
 229     bytes_needed = RAND_POOL_bytes_needed(pool, 8 /*entropy_per_byte*/);
 230     if (bytes_needed > 0) {
 231         static const char *paths[] = { DEVRANDOM_EGD, NULL };
 232         int i;
 233
 234         for (i = 0; paths[i] != NULL; i++) {
 235             buffer = RAND_POOL_add_begin(pool, bytes_needed);
 236             if (buffer != NULL) {
 237                 size_t bytes = 0;
 238                 int num = RAND_query_egd_bytes(paths[i],
 239                                                buffer, (int)bytes_needed);
 240                 if (num == (int)bytes_needed)
 241                     bytes = bytes_needed;
 242
 243                 entropy_available = RAND_POOL_add_end(pool, bytes, 8 * bytes);
 244             }
 245             if (entropy_available > 0)
 246                 return entropy_available;
 247         }
 248     }
 249 #   endif
 250
 251     return RAND_POOL_entropy_available(pool);
 252 #  endif
 253 }
 254 # endif
 255
 256 #endif