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
  18 #if (defined(OPENSSL_SYS_VXWORKS) || defined(OPENSSL_SYS_UEFI)) && \
  19         !defined(OPENSSL_RAND_SEED_NONE)
  20 # error "UEFI and VXWorks only support seeding NONE"
  21 #endif
  22
  23 #if !(defined(OPENSSL_SYS_WINDOWS) || defined(OPENSSL_SYS_WIN32) \
  24     || defined(OPENSSL_SYS_VMS) || defined(OPENSSL_SYS_VXWORKS) \
  25     || defined(OPENSSL_SYS_UEFI))
  26
  27 # if defined(OPENSSL_SYS_VOS)
  28
  29 #  ifndef OPENSSL_RAND_SEED_OS
  30 #   error "Unsupported seeding method configured; must be os"
  31 #  endif
  32
  33 #  if defined(OPENSSL_SYS_VOS_HPPA) && defined(OPENSSL_SYS_VOS_IA32)
  34 #   error "Unsupported HP-PA and IA32 at the same time."
  35 #  endif
  36 #  if !defined(OPENSSL_SYS_VOS_HPPA) && !defined(OPENSSL_SYS_VOS_IA32)
  37 #   error "Must have one of HP-PA or IA32"
  38 #  endif
  39
  40 /*
  41  * The following algorithm repeatedly samples the real-time clock (RTC) to
  42  * generate a sequence of unpredictable data.  The algorithm relies upon the
  43  * uneven execution speed of the code (due to factors such as cache misses,
  44  * interrupts, bus activity, and scheduling) and upon the rather large
  45  * relative difference between the speed of the clock and the rate at which
  46  * it can be read.  If it is ported to an environment where execution speed
  47  * is more constant or where the RTC ticks at a much slower rate, or the
  48  * clock can be read with fewer instructions, it is likely that the results
  49  * would be far more predictable.  This should only be used for legacy
  50  * platforms.
  51  *
  52  * As a precaution, we assume only 2 bits of entropy per byte.
  53  */
  54 size_t rand_pool_acquire_entropy(RAND_POOL *pool)
  55 {
  56     short int code;
  57     gid_t curr_gid;
  58     pid_t curr_pid;
  59     uid_t curr_uid;
  60     int i, k;
  61     size_t bytes_needed;
  62     struct timespec ts;
  63     unsigned char v;
  64 #  ifdef OPENSSL_SYS_VOS_HPPA
  65     long duration;
  66     extern void s$sleep(long *_duration, short int *_code);
  67 #  else
  68     long long duration;
  69     extern void s$sleep2(long long *_duration, short int *_code);
  70 #  endif
  71
  72     /*
  73      * Seed with the gid, pid, and uid, to ensure *some* variation between
  74      * different processes.
  75      */
  76     curr_gid = getgid();
  77     rand_pool_add(pool, &curr_gid, sizeof(curr_gid), 0);
  78     curr_pid = getpid();
  79     rand_pool_add(pool, &curr_pid, sizeof(curr_pid), 0);
  80     curr_uid = getuid();
  81     rand_pool_add(pool, &curr_uid, sizeof(curr_uid), 0);
  82
  83     bytes_needed = rand_pool_bytes_needed(pool, 2 /*entropy_per_byte*/);
  84
  85     for (i = 0; i < bytes_needed; i++) {
  86         /*
  87          * burn some cpu; hope for interrupts, cache collisions, bus
  88          * interference, etc.
  89          */
  90         for (k = 0; k < 99; k++)
  91             ts.tv_nsec = random();
  92
  93 #  ifdef OPENSSL_SYS_VOS_HPPA
  94         /* sleep for 1/1024 of a second (976 us).  */
  95         duration = 1;
  96         s$sleep(&duration, &code);
  97 #  else
  98         /* sleep for 1/65536 of a second (15 us).  */
  99         duration = 1;
 100         s$sleep2(&duration, &code);
 101 #  endif
 102
 103         /* Get wall clock time, take 8 bits. */
 104         clock_gettime(CLOCK_REALTIME, &ts);
 105         v = (unsigned char)(ts.tv_nsec & 0xFF);
 106         rand_pool_add(pool, arg, &v, sizeof(v) , 2);
 107     }
 108     return rand_pool_entropy_available(pool);
 109 }
 110
 111 # else
 112
 113 #  if defined(OPENSSL_RAND_SEED_EGD) && \
 114         (defined(OPENSSL_NO_EGD) || !defined(DEVRANDOM_EGD))
 115 #   error "Seeding uses EGD but EGD is turned off or no device given"
 116 #  endif
 117
 118 #  if defined(OPENSSL_RAND_SEED_DEVRANDOM) && !defined(DEVRANDOM)
 119 #   error "Seeding uses urandom but DEVRANDOM is not configured"
 120 #  endif
 121
 122 #  if defined(OPENSSL_RAND_SEED_OS)
 123 #   if !defined(DEVRANDOM)
 124 #    error "OS seeding requires DEVRANDOM to be configured"
 125 #   endif
 126 #   define OPENSSL_RAND_SEED_DEVRANDOM
 127 #   if defined(__GLIBC__) && defined(__GLIBC_PREREQ)
 128 #    if __GLIBC_PREREQ(2, 25)
 129 #     define OPENSSL_RAND_SEED_GETRANDOM
 130 #    endif
 131 #   endif
 132 #  endif
 133
 134 #  ifdef OPENSSL_RAND_SEED_GETRANDOM
 135 #   include <sys/random.h>
 136 #  endif
 137
 138 #  if defined(OPENSSL_RAND_SEED_LIBRANDOM)
 139 #   error "librandom not (yet) supported"
 140 #  endif
 141
 142 /*
 143  * Try the various seeding methods in turn, exit when successful.
 144  *
 145  * TODO(DRBG): If more than one entropy source is available, is it
 146  * preferable to stop as soon as enough entropy has been collected
 147  * (as favored by @rsalz) or should one rather be defensive and add
 148  * more entropy than requested and/or from different sources?
 149  *
 150  * Currently, the user can select multiple entropy sources in the
 151  * configure step, yet in practice only the first available source
 152  * will be used. A more flexible solution has been requested, but
 153  * currently it is not clear how this can be achieved without
 154  * overengineering the problem. There are many parameters which
 155  * could be taken into account when selecting the order and amount
 156  * of input from the different entropy sources (trust, quality,
 157  * possibility of blocking).
 158  */
 159 size_t rand_pool_acquire_entropy(RAND_POOL *pool)
 160 {
 161 #  ifdef OPENSSL_RAND_SEED_NONE
 162     return rand_pool_entropy_available(pool);
 163 #  else
 164     size_t bytes_needed;
 165     size_t entropy_available = 0;
 166     unsigned char *buffer;
 167
 168 #   ifdef OPENSSL_RAND_SEED_GETRANDOM
 169     bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/);
 170     buffer = rand_pool_add_begin(pool, bytes_needed);
 171     if (buffer != NULL) {
 172         size_t bytes = 0;
 173
 174         if (getrandom(buffer, bytes_needed, 0) == (int)bytes_needed)
 175             bytes = bytes_needed;
 176
 177         rand_pool_add_end(pool, bytes, 8 * bytes);
 178         entropy_available = rand_pool_entropy_available(pool);
 179     }
 180     if (entropy_available > 0)
 181         return entropy_available;
 182 #   endif
 183
 184 #   if defined(OPENSSL_RAND_SEED_LIBRANDOM)
 185     {
 186         /* Not yet implemented. */
 187     }
 188 #   endif
 189
 190 #   ifdef OPENSSL_RAND_SEED_DEVRANDOM
 191     bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/);
 192     if (bytes_needed > 0) {
 193         static const char *paths[] = { DEVRANDOM, NULL };
 194         FILE *fp;
 195         int i;
 196
 197         for (i = 0; paths[i] != NULL; i++) {
 198             if ((fp = fopen(paths[i], "rb")) == NULL)
 199                 continue;
 200             setbuf(fp, NULL);
 201             buffer = rand_pool_add_begin(pool, bytes_needed);
 202             if (buffer != NULL) {
 203                 size_t bytes = 0;
 204                 if (fread(buffer, 1, bytes_needed, fp) == 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             fclose(fp);
 211             if (entropy_available > 0)
 212                 return entropy_available;
 213
 214             bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/);
 215         }
 216     }
 217 #   endif
 218
 219 #   ifdef OPENSSL_RAND_SEED_RDTSC
 220     entropy_available = rand_acquire_entropy_from_tsc(pool);
 221     if (entropy_available > 0)
 222         return entropy_available;
 223 #   endif
 224
 225 #   ifdef OPENSSL_RAND_SEED_RDCPU
 226     entropy_available = rand_acquire_entropy_from_cpu(pool);
 227     if (entropy_available > 0)
 228         return entropy_available;
 229 #   endif
 230
 231 #   ifdef OPENSSL_RAND_SEED_EGD
 232     bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/);
 233     if (bytes_needed > 0) {
 234         static const char *paths[] = { DEVRANDOM_EGD, NULL };
 235         int i;
 236
 237         for (i = 0; paths[i] != NULL; i++) {
 238             buffer = rand_pool_add_begin(pool, bytes_needed);
 239             if (buffer != NULL) {
 240                 size_t bytes = 0;
 241                 int num = RAND_query_egd_bytes(paths[i],
 242                                                buffer, (int)bytes_needed);
 243                 if (num == (int)bytes_needed)
 244                     bytes = bytes_needed;
 245
 246                 rand_pool_add_end(pool, bytes, 8 * bytes);
 247                 entropy_available = rand_pool_entropy_available(pool);
 248             }
 249             if (entropy_available > 0)
 250                 return entropy_available;
 251         }
 252     }
 253 #   endif
 254
 255     return rand_pool_entropy_available(pool);
 256 #  endif
 257 }
 258 # endif
 259
 260 #endif