crypto/rand/randfile.c

   1 /*
   2  * Copyright 1995-2016 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
  12 #include <errno.h>
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16
  17 #include <openssl/crypto.h>
  18 #include <openssl/rand.h>
  19 #include <openssl/buffer.h>
  20
  21 #ifdef OPENSSL_SYS_VMS
  22 # include <unixio.h>
  23 #endif
  24 #ifndef NO_SYS_TYPES_H
  25 # include <sys/types.h>
  26 #endif
  27 #ifndef OPENSSL_NO_POSIX_IO
  28 # include <sys/stat.h>
  29 # include <fcntl.h>
  30 /*
  31  * Following should not be needed, and we could have been stricter
  32  * and demand S_IS*. But some systems just don't comply... Formally
  33  * below macros are "anatomically incorrect", because normally they
  34  * would look like ((m) & MASK == TYPE), but since MASK availability
  35  * is as questionable, we settle for this poor-man fallback...
  36  */
  37 # if !defined(S_ISBLK)
  38 #  if defined(_S_IFBLK)
  39 #   define S_ISBLK(m) ((m) & _S_IFBLK)
  40 #  elif defined(S_IFBLK)
  41 #   define S_ISBLK(m) ((m) & S_IFBLK)
  42 #  elif defined(_WIN32)
  43 #   define S_ISBLK(m) 0 /* no concept of block devices on Windows */
  44 #  endif
  45 # endif
  46 # if !defined(S_ISCHR)
  47 #  if defined(_S_IFCHR)
  48 #   define S_ISCHR(m) ((m) & _S_IFCHR)
  49 #  elif defined(S_IFCHR)
  50 #   define S_ISCHR(m) ((m) & S_IFCHR)
  51 #  endif
  52 # endif
  53 #endif
  54
  55 #ifdef _WIN32
  56 # define stat    _stat
  57 # define chmod   _chmod
  58 # define open    _open
  59 # define fdopen  _fdopen
  60 #endif
  61
  62 #undef BUFSIZE
  63 #define BUFSIZE 1024
  64 #define RAND_DATA 1024
  65
  66 #ifdef OPENSSL_SYS_VMS
  67 /*
  68  * Misc hacks needed for specific cases.
  69  *
  70  * __FILE_ptr32 is a type provided by DEC C headers (types.h specifically)
  71  * to make sure the FILE* is a 32-bit pointer no matter what.  We know that
  72  * stdio function return this type (a study of stdio.h proves it).
  73  * Additionally, we create a similar char pointer type for the sake of
  74  * vms_setbuf below.
  75  */
  76 # if __INITIAL_POINTER_SIZE == 64
  77 #  pragma pointer_size save
  78 #  pragma pointer_size 32
  79 # endif
  80 typedef char *char_ptr32;
  81 # if __INITIAL_POINTER_SIZE == 64
  82 #  pragma pointer_size restore
  83 # endif
  84
  85 /*
  86  * On VMS, setbuf() will only take 32-bit pointers, and a compilation
  87  * with /POINTER_SIZE=64 will give off a MAYLOSEDATA2 warning here.
  88  * Since we know that the FILE* really is a 32-bit pointer expanded to
  89  * 64 bits, we also know it's safe to convert it back to a 32-bit pointer.
  90  * As for the buffer parameter, we only use NULL here, so that passes as
  91  * well...
  92  */
  93 static void vms_setbuf(FILE *fp, char *buf)
  94 {
  95     setbuf((__FILE_ptr32)fp, (char_ptr32)buf);
  96 }
  97 /*
  98  * This declaration is a nasty hack to get around vms' extension to fopen for
  99  * passing in sharing options being disabled by /STANDARD=ANSI89
 100  */
 101 static __FILE_ptr32 (*const vms_fopen)(const char *, const char *, ...) =
 102     (__FILE_ptr32 (*)(const char *, const char *, ...))fopen;
 103 # define VMS_OPEN_ATTRS "shr=get,put,upd,del","ctx=bin,stm","rfm=stm","rat=none","mrs=0"
 104
 105 # define fopen(fname,mode) vms_fopen((fname), (mode), VMS_OPEN_ATTRS)
 106 # define setbuf(fp,buf) vms_setbuf((fp), (buf))
 107 #endif
 108
 109 #define RFILE ".rnd"
 110
 111 /*
 112  * Note that these functions are intended for seed files only. Entropy
 113  * devices and EGD sockets are handled in rand_unix.c
 114  */
 115
 116 int RAND_load_file(const char *file, long bytes)
 117 {
 118     /*-
 119      * If bytes >= 0, read up to 'bytes' bytes.
 120      * if bytes == -1, read complete file.
 121      */
 122
 123     unsigned char buf[BUFSIZE];
 124 #ifndef OPENSSL_NO_POSIX_IO
 125     struct stat sb;
 126 #endif
 127     int i, ret = 0, n;
 128     FILE *in;
 129
 130     if (file == NULL)
 131         return (0);
 132
 133 #ifndef OPENSSL_NO_POSIX_IO
 134     /*
 135      * struct stat can have padding and unused fields that may not be
 136      * initialized in the call to stat(). We need to clear the entire
 137      * structure before calling RAND_add() to avoid complaints from
 138      * applications such as Valgrind.
 139      */
 140     memset(&sb, 0, sizeof(sb));
 141     if (stat(file, &sb) < 0)
 142         return (0);
 143     RAND_add(&sb, sizeof(sb), 0.0);
 144 #endif
 145     if (bytes == 0)
 146         return (ret);
 147
 148     in = fopen(file, "rb");
 149     if (in == NULL)
 150         goto err;
 151 #if defined(S_ISBLK) && defined(S_ISCHR) && !defined(OPENSSL_NO_POSIX_IO)
 152     if (S_ISBLK(sb.st_mode) || S_ISCHR(sb.st_mode)) {
 153         /*
 154          * this file is a device. we don't want read an infinite number of
 155          * bytes from a random device, nor do we want to use buffered I/O
 156          * because we will waste system entropy.
 157          */
 158         bytes = (bytes == -1) ? 2048 : bytes; /* ok, is 2048 enough? */
 159         setbuf(in, NULL); /* don't do buffered reads */
 160     }
 161 #endif
 162     for (;;) {
 163         if (bytes > 0)
 164             n = (bytes < BUFSIZE) ? (int)bytes : BUFSIZE;
 165         else
 166             n = BUFSIZE;
 167         i = fread(buf, 1, n, in);
 168         if (i <= 0)
 169             break;
 170
 171         RAND_add(buf, i, (double)i);
 172         ret += i;
 173         if (bytes > 0) {
 174             bytes -= n;
 175             if (bytes <= 0)
 176                 break;
 177         }
 178     }
 179     fclose(in);
 180     OPENSSL_cleanse(buf, BUFSIZE);
 181  err:
 182     return (ret);
 183 }
 184
 185 int RAND_write_file(const char *file)
 186 {
 187     unsigned char buf[BUFSIZE];
 188     int i, ret = 0, rand_err = 0;
 189     FILE *out = NULL;
 190     int n;
 191 #ifndef OPENSSL_NO_POSIX_IO
 192     struct stat sb;
 193
 194     i = stat(file, &sb);
 195     if (i != -1) {
 196 # if defined(S_ISBLK) && defined(S_ISCHR)
 197         if (S_ISBLK(sb.st_mode) || S_ISCHR(sb.st_mode)) {
 198             /*
 199              * this file is a device. we don't write back to it. we
 200              * "succeed" on the assumption this is some sort of random
 201              * device. Otherwise attempting to write to and chmod the device
 202              * causes problems.
 203              */
 204             return (1);
 205         }
 206 # endif
 207     }
 208 #endif
 209
 210 #if defined(O_CREAT) && !defined(OPENSSL_NO_POSIX_IO) && !defined(OPENSSL_SYS_VMS)
 211     {
 212 # ifndef O_BINARY
 213 #  define O_BINARY 0
 214 # endif
 215         /*
 216          * chmod(..., 0600) is too late to protect the file, permissions
 217          * should be restrictive from the start
 218          */
 219         int fd = open(file, O_WRONLY | O_CREAT | O_BINARY, 0600);
 220         if (fd != -1)
 221             out = fdopen(fd, "wb");
 222     }
 223 #endif
 224
 225 #ifdef OPENSSL_SYS_VMS
 226     /*
 227      * VMS NOTE: Prior versions of this routine created a _new_ version of
 228      * the rand file for each call into this routine, then deleted all
 229      * existing versions named ;-1, and finally renamed the current version
 230      * as ';1'. Under concurrent usage, this resulted in an RMS race
 231      * condition in rename() which could orphan files (see vms message help
 232      * for RMS$_REENT). With the fopen() calls below, openssl/VMS now shares
 233      * the top-level version of the rand file. Note that there may still be
 234      * conditions where the top-level rand file is locked. If so, this code
 235      * will then create a new version of the rand file. Without the delete
 236      * and rename code, this can result in ascending file versions that stop
 237      * at version 32767, and this routine will then return an error. The
 238      * remedy for this is to recode the calling application to avoid
 239      * concurrent use of the rand file, or synchronize usage at the
 240      * application level. Also consider whether or not you NEED a persistent
 241      * rand file in a concurrent use situation.
 242      */
 243
 244     out = fopen(file, "rb+");
 245 #endif
 246     if (out == NULL)
 247         out = fopen(file, "wb");
 248     if (out == NULL)
 249         goto err;
 250
 251 #if !defined(NO_CHMOD) && !defined(OPENSSL_NO_POSIX_IO)
 252     chmod(file, 0600);
 253 #endif
 254     n = RAND_DATA;
 255     for (;;) {
 256         i = (n > BUFSIZE) ? BUFSIZE : n;
 257         n -= BUFSIZE;
 258         if (RAND_bytes(buf, i) <= 0)
 259             rand_err = 1;
 260         i = fwrite(buf, 1, i, out);
 261         if (i <= 0) {
 262             ret = 0;
 263             break;
 264         }
 265         ret += i;
 266         if (n <= 0)
 267             break;
 268     }
 269
 270     fclose(out);
 271     OPENSSL_cleanse(buf, BUFSIZE);
 272  err:
 273     return (rand_err ? -1 : ret);
 274 }
 275
 276 const char *RAND_file_name(char *buf, size_t size)
 277 {
 278     char *s = NULL;
 279 #ifdef __OpenBSD__
 280     struct stat sb;
 281 #endif
 282
 283     if (OPENSSL_issetugid() == 0)
 284         s = getenv("RANDFILE");
 285     if (s != NULL && *s && strlen(s) + 1 < size) {
 286         if (OPENSSL_strlcpy(buf, s, size) >= size)
 287             return NULL;
 288     } else {
 289         if (OPENSSL_issetugid() == 0)
 290             s = getenv("HOME");
 291 #ifdef DEFAULT_HOME
 292         if (s == NULL) {
 293             s = DEFAULT_HOME;
 294         }
 295 #endif
 296         if (s && *s && strlen(s) + strlen(RFILE) + 2 < size) {
 297             OPENSSL_strlcpy(buf, s, size);
 298 #ifndef OPENSSL_SYS_VMS
 299             OPENSSL_strlcat(buf, "/", size);
 300 #endif
 301             OPENSSL_strlcat(buf, RFILE, size);
 302         } else
 303             buf[0] = '\0';      /* no file name */
 304     }
 305
 306 #ifdef __OpenBSD__
 307     /*
 308      * given that all random loads just fail if the file can't be seen on a
 309      * stat, we stat the file we're returning, if it fails, use /dev/arandom
 310      * instead. this allows the user to use their own source for good random
 311      * data, but defaults to something hopefully decent if that isn't
 312      * available.
 313      */
 314
 315     if (!buf[0])
 316         if (OPENSSL_strlcpy(buf, "/dev/arandom", size) >= size) {
 317             return (NULL);
 318         }
 319     if (stat(buf, &sb) == -1)
 320         if (OPENSSL_strlcpy(buf, "/dev/arandom", size) >= size) {
 321             return (NULL);
 322         }
 323 #endif
 324     return (buf);
 325 }