crypto/rand/randfile.c

   1 /* crypto/rand/randfile.c */
   2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   3  * All rights reserved.
   4  *
   5  * This package is an SSL implementation written
   6  * by Eric Young (eay@cryptsoft.com).
   7  * The implementation was written so as to conform with Netscapes SSL.
   8  *
   9  * This library is free for commercial and non-commercial use as long as
  10  * the following conditions are aheared to.  The following conditions
  11  * apply to all code found in this distribution, be it the RC4, RSA,
  12  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  13  * included with this distribution is covered by the same copyright terms
  14  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  15  *
  16  * Copyright remains Eric Young's, and as such any Copyright notices in
  17  * the code are not to be removed.
  18  * If this package is used in a product, Eric Young should be given attribution
  19  * as the author of the parts of the library used.
  20  * This can be in the form of a textual message at program startup or
  21  * in documentation (online or textual) provided with the package.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 3. All advertising materials mentioning features or use of this software
  32  *    must display the following acknowledgement:
  33  *    "This product includes cryptographic software written by
  34  *     Eric Young (eay@cryptsoft.com)"
  35  *    The word 'cryptographic' can be left out if the rouines from the library
  36  *    being used are not cryptographic related :-).
  37  * 4. If you include any Windows specific code (or a derivative thereof) from
  38  *    the apps directory (application code) you must include an acknowledgement:
  39  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  *
  53  * The licence and distribution terms for any publically available version or
  54  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  55  * copied and put under another distribution licence
  56  * [including the GNU Public Licence.]
  57  */
  58
  59 /* We need to define this to get macros like S_IFBLK and S_IFCHR */
  60 #define _XOPEN_SOURCE 500
  61
  62 #include <errno.h>
  63 #include <stdio.h>
  64 #include <stdlib.h>
  65 #include <string.h>
  66
  67 #include "e_os.h"
  68 #include <openssl/crypto.h>
  69 #include <openssl/rand.h>
  70 #include <openssl/buffer.h>
  71
  72 #ifdef OPENSSL_SYS_VMS
  73 # include <unixio.h>
  74 #endif
  75 #ifndef NO_SYS_TYPES_H
  76 # include <sys/types.h>
  77 #endif
  78 #ifdef MAC_OS_pre_X
  79 # include <stat.h>
  80 #else
  81 # include <sys/stat.h>
  82 #endif
  83
  84 #ifdef _WIN32
  85 # define stat    _stat
  86 # define chmod   _chmod
  87 # define open    _open
  88 # define fdopen  _fdopen
  89 #endif
  90
  91 #undef BUFSIZE
  92 #define BUFSIZE 1024
  93 #define RAND_DATA 1024
  94
  95 #ifdef OPENSSL_SYS_VMS
  96 /*
  97  * This declaration is a nasty hack to get around vms' extension to fopen for
  98  * passing in sharing options being disabled by our /STANDARD=ANSI89
  99  */
 100 static FILE *(*const vms_fopen)(const char *, const char *, ...) =
 101     (FILE *(*)(const char *, const char *, ...))fopen;
 102 # define VMS_OPEN_ATTRS "shr=get,put,upd,del","ctx=bin,stm","rfm=stm","rat=none","mrs=0"
 103 #endif
 104
 105 /* #define RFILE ".rnd" - defined in ../../e_os.h */
 106
 107 /*
 108  * Note that these functions are intended for seed files only. Entropy
 109  * devices and EGD sockets are handled in rand_unix.c
 110  */
 111
 112 int RAND_load_file(const char *file, long bytes)
 113 {
 114         /*-
 115          * If bytes >= 0, read up to 'bytes' bytes.
 116          * if bytes == -1, read complete file.
 117          */
 118
 119     MS_STATIC unsigned char buf[BUFSIZE];
 120     struct stat sb;
 121     int i, ret = 0, n;
 122     FILE *in;
 123
 124     if (file == NULL)
 125         return (0);
 126
 127 #ifdef PURIFY
 128     /*
 129      * struct stat can have padding and unused fields that may not be
 130      * initialized in the call to stat(). We need to clear the entire
 131      * structure before calling RAND_add() to avoid complaints from
 132      * applications such as Valgrind.
 133      */
 134     memset(&sb, 0, sizeof(sb));
 135 #endif
 136
 137     if (stat(file, &sb) < 0)
 138         return (0);
 139     RAND_add(&sb, sizeof(sb), 0.0);
 140     if (bytes == 0)
 141         return (ret);
 142
 143 #ifdef OPENSSL_SYS_VMS
 144     in = vms_fopen(file, "rb", VMS_OPEN_ATTRS);
 145 #else
 146     in = fopen(file, "rb");
 147 #endif
 148     if (in == NULL)
 149         goto err;
 150 #if defined(S_ISBLK) && defined(S_ISCHR)
 151     if (S_ISBLK(sb.st_mode) || S_ISCHR(sb.st_mode)) {
 152         /*
 153          * this file is a device. we don't want read an infinite number of
 154          * bytes from a random device, nor do we want to use buffered I/O
 155          * because we will waste system entropy.
 156          */
 157         bytes = (bytes == -1) ? 2048 : bytes; /* ok, is 2048 enough? */
 158         setvbuf(in, NULL, _IONBF, 0); /* don't do buffered reads */
 159     }
 160 #endif
 161     for (;;) {
 162         if (bytes > 0)
 163             n = (bytes < BUFSIZE) ? (int)bytes : BUFSIZE;
 164         else
 165             n = BUFSIZE;
 166         i = fread(buf, 1, n, in);
 167         if (i <= 0)
 168             break;
 169 #ifdef PURIFY
 170         RAND_add(buf, i, (double)i);
 171 #else
 172         /* even if n != i, use the full array */
 173         RAND_add(buf, n, (double)i);
 174 #endif
 175         ret += i;
 176         if (bytes > 0) {
 177             bytes -= n;
 178             if (bytes <= 0)
 179                 break;
 180         }
 181     }
 182     fclose(in);
 183     OPENSSL_cleanse(buf, BUFSIZE);
 184  err:
 185     return (ret);
 186 }
 187
 188 int RAND_write_file(const char *file)
 189 {
 190     unsigned char buf[BUFSIZE];
 191     int i, ret = 0, rand_err = 0;
 192     FILE *out = NULL;
 193     int n;
 194     struct stat sb;
 195
 196     i = stat(file, &sb);
 197     if (i != -1) {
 198 #if defined(S_ISBLK) && defined(S_ISCHR)
 199         if (S_ISBLK(sb.st_mode) || S_ISCHR(sb.st_mode)) {
 200             /*
 201              * this file is a device. we don't write back to it. we
 202              * "succeed" on the assumption this is some sort of random
 203              * device. Otherwise attempting to write to and chmod the device
 204              * causes problems.
 205              */
 206             return (1);
 207         }
 208 #endif
 209     }
 210 #if defined(O_CREAT) && !defined(OPENSSL_SYS_WIN32) && !defined(OPENSSL_SYS_VMS)
 211     {
 212         /* For some reason Win32 can't write to files created this way */
 213
 214         /*
 215          * chmod(..., 0600) is too late to protect the file, permissions
 216          * should be restrictive from the start
 217          */
 218         int fd = open(file, O_CREAT, 0600);
 219         if (fd != -1)
 220             out = fdopen(fd, "wb");
 221     }
 222 #endif
 223
 224 #ifdef OPENSSL_SYS_VMS
 225     /*
 226      * VMS NOTE: Prior versions of this routine created a _new_ version of
 227      * the rand file for each call into this routine, then deleted all
 228      * existing versions named ;-1, and finally renamed the current version
 229      * as ';1'. Under concurrent usage, this resulted in an RMS race
 230      * condition in rename() which could orphan files (see vms message help
 231      * for RMS$_REENT). With the fopen() calls below, openssl/VMS now shares
 232      * the top-level version of the rand file. Note that there may still be
 233      * conditions where the top-level rand file is locked. If so, this code
 234      * will then create a new version of the rand file. Without the delete
 235      * and rename code, this can result in ascending file versions that stop
 236      * at version 32767, and this routine will then return an error. The
 237      * remedy for this is to recode the calling application to avoid
 238      * concurrent use of the rand file, or synchronize usage at the
 239      * application level. Also consider whether or not you NEED a persistent
 240      * rand file in a concurrent use situation.
 241      */
 242
 243     out = vms_fopen(file, "rb+", VMS_OPEN_ATTRS);
 244     if (out == NULL)
 245         out = vms_fopen(file, "wb", VMS_OPEN_ATTRS);
 246 #else
 247     if (out == NULL)
 248         out = fopen(file, "wb");
 249 #endif
 250     if (out == NULL)
 251         goto err;
 252
 253 #ifndef NO_CHMOD
 254     chmod(file, 0600);
 255 #endif
 256     n = RAND_DATA;
 257     for (;;) {
 258         i = (n > BUFSIZE) ? BUFSIZE : n;
 259         n -= BUFSIZE;
 260         if (RAND_bytes(buf, i) <= 0)
 261             rand_err = 1;
 262         i = fwrite(buf, 1, i, out);
 263         if (i <= 0) {
 264             ret = 0;
 265             break;
 266         }
 267         ret += i;
 268         if (n <= 0)
 269             break;
 270     }
 271
 272     fclose(out);
 273     OPENSSL_cleanse(buf, BUFSIZE);
 274  err:
 275     return (rand_err ? -1 : ret);
 276 }
 277
 278 const char *RAND_file_name(char *buf, size_t size)
 279 {
 280     char *s = NULL;
 281 #ifdef __OpenBSD__
 282     int ok = 0;
 283     struct stat sb;
 284 #endif
 285
 286     if (OPENSSL_issetugid() == 0)
 287         s = getenv("RANDFILE");
 288     if (s != NULL && *s && strlen(s) + 1 < size) {
 289         if (BUF_strlcpy(buf, s, size) >= size)
 290             return NULL;
 291     } else {
 292         if (OPENSSL_issetugid() == 0)
 293             s = getenv("HOME");
 294 #ifdef DEFAULT_HOME
 295         if (s == NULL) {
 296             s = DEFAULT_HOME;
 297         }
 298 #endif
 299         if (s && *s && strlen(s) + strlen(RFILE) + 2 < size) {
 300             BUF_strlcpy(buf, s, size);
 301 #ifndef OPENSSL_SYS_VMS
 302             BUF_strlcat(buf, "/", size);
 303 #endif
 304             BUF_strlcat(buf, RFILE, size);
 305 #ifdef __OpenBSD__
 306             ok = 1;
 307 #endif
 308         } else
 309             buf[0] = '\0';      /* no file name */
 310     }
 311
 312 #ifdef __OpenBSD__
 313     /*
 314      * given that all random loads just fail if the file can't be seen on a
 315      * stat, we stat the file we're returning, if it fails, use /dev/arandom
 316      * instead. this allows the user to use their own source for good random
 317      * data, but defaults to something hopefully decent if that isn't
 318      * available.
 319      */
 320
 321     if (!ok)
 322         if (BUF_strlcpy(buf, "/dev/arandom", size) >= size) {
 323             return (NULL);
 324         }
 325     if (stat(buf, &sb) == -1)
 326         if (BUF_strlcpy(buf, "/dev/arandom", size) >= size) {
 327             return (NULL);
 328         }
 329 #endif
 330     return (buf);
 331 }