crypto/rand/randfile.c

   1 /*
   2  * Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (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 "internal/cryptlib.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 #include <sys/types.h>
  25 #ifndef OPENSSL_NO_POSIX_IO
  26 # include <sys/stat.h>
  27 # include <fcntl.h>
  28 # if defined(_WIN32) && !defined(_WIN32_WCE)
  29 #  include <windows.h>
  30 #  include <io.h>
  31 #  define stat    _stat
  32 #  define chmod   _chmod
  33 #  define open    _open
  34 #  define fdopen  _fdopen
  35 #  define fstat   _fstat
  36 #  define fileno  _fileno
  37 # endif
  38 #endif
  39
  40 /*
  41  * Following should not be needed, and we could have been stricter
  42  * and demand S_IS*. But some systems just don't comply... Formally
  43  * below macros are "anatomically incorrect", because normally they
  44  * would look like ((m) & MASK == TYPE), but since MASK availability
  45  * is as questionable, we settle for this poor-man fallback...
  46  */
  47 # if !defined(S_ISREG)
  48 #   define S_ISREG(m) ((m) & S_IFREG)
  49 # endif
  50
  51 #define RAND_BUF_SIZE 1024
  52 #define RFILE ".rnd"
  53
  54 #ifdef OPENSSL_SYS_VMS
  55 /*
  56  * __FILE_ptr32 is a type provided by DEC C headers (types.h specifically)
  57  * to make sure the FILE* is a 32-bit pointer no matter what.  We know that
  58  * stdio functions return this type (a study of stdio.h proves it).
  59  *
  60  * This declaration is a nasty hack to get around vms' extension to fopen for
  61  * passing in sharing options being disabled by /STANDARD=ANSI89
  62  */
  63 static __FILE_ptr32 (*const vms_fopen)(const char *, const char *, ...) =
  64         (__FILE_ptr32 (*)(const char *, const char *, ...))fopen;
  65 # define VMS_OPEN_ATTRS \
  66         "shr=get,put,upd,del","ctx=bin,stm","rfm=stm","rat=none","mrs=0"
  67 # define openssl_fopen(fname, mode) vms_fopen((fname), (mode), VMS_OPEN_ATTRS)
  68 #endif
  69
  70 /*
  71  * Note that these functions are intended for seed files only. Entropy
  72  * devices and EGD sockets are handled in rand_unix.c  If |bytes| is
  73  * -1 read the complete file; otherwise read the specified amount.
  74  */
  75 int RAND_load_file(const char *file, long bytes)
  76 {
  77     /*
  78      * The load buffer size exceeds the chunk size by the comfortable amount
  79      * of 'RAND_DRBG_STRENGTH' bytes (not bits!). This is done on purpose
  80      * to avoid calling RAND_add() with a small final chunk. Instead, such
  81      * a small final chunk will be added together with the previous chunk
  82      * (unless it's the only one).
  83      */
  84 #define RAND_LOAD_BUF_SIZE (RAND_BUF_SIZE + RAND_DRBG_STRENGTH)
  85     unsigned char buf[RAND_LOAD_BUF_SIZE];
  86
  87 #ifndef OPENSSL_NO_POSIX_IO
  88     struct stat sb;
  89 #endif
  90     int i, n, ret = 0;
  91     FILE *in;
  92
  93     if (bytes == 0)
  94         return 0;
  95
  96     if ((in = openssl_fopen(file, "rb")) == NULL) {
  97         RANDerr(RAND_F_RAND_LOAD_FILE, RAND_R_CANNOT_OPEN_FILE);
  98         ERR_add_error_data(2, "Filename=", file);
  99         return -1;
 100     }
 101
 102 #ifndef OPENSSL_NO_POSIX_IO
 103     if (fstat(fileno(in), &sb) < 0) {
 104         RANDerr(RAND_F_RAND_LOAD_FILE, RAND_R_INTERNAL_ERROR);
 105         ERR_add_error_data(2, "Filename=", file);
 106         fclose(in);
 107         return -1;
 108     }
 109
 110     if (bytes < 0) {
 111         if (S_ISREG(sb.st_mode))
 112             bytes = sb.st_size;
 113         else
 114             bytes = RAND_DRBG_STRENGTH;
 115     }
 116 #endif
 117     /*
 118      * On VMS, setbuf() will only take 32-bit pointers, and a compilation
 119      * with /POINTER_SIZE=64 will give off a MAYLOSEDATA2 warning here.
 120      * However, we trust that the C RTL will never give us a FILE pointer
 121      * above the first 4 GB of memory, so we simply turn off the warning
 122      * temporarily.
 123      */
 124 #if defined(OPENSSL_SYS_VMS) && defined(__DECC)
 125 # pragma environment save
 126 # pragma message disable maylosedata2
 127 #endif
 128     /*
 129      * Don't buffer, because even if |file| is regular file, we have
 130      * no control over the buffer, so why would we want a copy of its
 131      * contents lying around?
 132      */
 133     setbuf(in, NULL);
 134 #if defined(OPENSSL_SYS_VMS) && defined(__DECC)
 135 # pragma environment restore
 136 #endif
 137
 138     for ( ; ; ) {
 139         if (bytes > 0)
 140             n = (bytes <= RAND_LOAD_BUF_SIZE) ? (int)bytes : RAND_BUF_SIZE;
 141         else
 142             n = RAND_LOAD_BUF_SIZE;
 143         i = fread(buf, 1, n, in);
 144 #ifdef EINTR
 145         if (ferror(in) && errno == EINTR){
 146             clearerr(in);
 147             if (i == 0)
 148                 continue;
 149         }
 150 #endif
 151         if (i == 0)
 152             break;
 153
 154         RAND_add(buf, i, (double)i);
 155         ret += i;
 156
 157         /* If given a bytecount, and we did it, break. */
 158         if (bytes > 0 && (bytes -= i) <= 0)
 159             break;
 160     }
 161
 162     OPENSSL_cleanse(buf, sizeof(buf));
 163     fclose(in);
 164     if (!RAND_status()) {
 165         RANDerr(RAND_F_RAND_LOAD_FILE, RAND_R_RESEED_ERROR);
 166         ERR_add_error_data(2, "Filename=", file);
 167         return -1;
 168     }
 169
 170     return ret;
 171 }
 172
 173 int RAND_write_file(const char *file)
 174 {
 175     unsigned char buf[RAND_BUF_SIZE];
 176     int ret = -1;
 177     FILE *out = NULL;
 178 #ifndef OPENSSL_NO_POSIX_IO
 179     struct stat sb;
 180
 181     if (stat(file, &sb) >= 0 && !S_ISREG(sb.st_mode)) {
 182         RANDerr(RAND_F_RAND_WRITE_FILE, RAND_R_NOT_A_REGULAR_FILE);
 183         ERR_add_error_data(2, "Filename=", file);
 184         return -1;
 185     }
 186 #endif
 187
 188     /* Collect enough random data. */
 189     if (RAND_priv_bytes(buf, (int)sizeof(buf)) != 1)
 190         return  -1;
 191
 192 #if defined(O_CREAT) && !defined(OPENSSL_NO_POSIX_IO) && \
 193     !defined(OPENSSL_SYS_VMS) && !defined(OPENSSL_SYS_WINDOWS)
 194     {
 195 # ifndef O_BINARY
 196 #  define O_BINARY 0
 197 # endif
 198         /*
 199          * chmod(..., 0600) is too late to protect the file, permissions
 200          * should be restrictive from the start
 201          */
 202         int fd = open(file, O_WRONLY | O_CREAT | O_BINARY, 0600);
 203         if (fd != -1)
 204             out = fdopen(fd, "wb");
 205     }
 206 #endif
 207
 208 #ifdef OPENSSL_SYS_VMS
 209     /*
 210      * VMS NOTE: Prior versions of this routine created a _new_ version of
 211      * the rand file for each call into this routine, then deleted all
 212      * existing versions named ;-1, and finally renamed the current version
 213      * as ';1'. Under concurrent usage, this resulted in an RMS race
 214      * condition in rename() which could orphan files (see vms message help
 215      * for RMS$_REENT). With the fopen() calls below, openssl/VMS now shares
 216      * the top-level version of the rand file. Note that there may still be
 217      * conditions where the top-level rand file is locked. If so, this code
 218      * will then create a new version of the rand file. Without the delete
 219      * and rename code, this can result in ascending file versions that stop
 220      * at version 32767, and this routine will then return an error. The
 221      * remedy for this is to recode the calling application to avoid
 222      * concurrent use of the rand file, or synchronize usage at the
 223      * application level. Also consider whether or not you NEED a persistent
 224      * rand file in a concurrent use situation.
 225      */
 226     out = openssl_fopen(file, "rb+");
 227 #endif
 228
 229     if (out == NULL)
 230         out = openssl_fopen(file, "wb");
 231     if (out == NULL) {
 232         RANDerr(RAND_F_RAND_WRITE_FILE, RAND_R_CANNOT_OPEN_FILE);
 233         ERR_add_error_data(2, "Filename=", file);
 234         return -1;
 235     }
 236
 237 #if !defined(NO_CHMOD) && !defined(OPENSSL_NO_POSIX_IO)
 238     /*
 239      * Yes it's late to do this (see above comment), but better than nothing.
 240      */
 241     chmod(file, 0600);
 242 #endif
 243
 244     ret = fwrite(buf, 1, RAND_BUF_SIZE, out);
 245     fclose(out);
 246     OPENSSL_cleanse(buf, RAND_BUF_SIZE);
 247     return ret;
 248 }
 249
 250 const char *RAND_file_name(char *buf, size_t size)
 251 {
 252     char *s = NULL;
 253     size_t len;
 254     int use_randfile = 1;
 255
 256 #if defined(_WIN32) && defined(CP_UTF8) && !defined(_WIN32_WCE)
 257     DWORD envlen;
 258     WCHAR *var;
 259
 260     /* Look up various environment variables. */
 261     if ((envlen = GetEnvironmentVariableW(var = L"RANDFILE", NULL, 0)) == 0) {
 262         use_randfile = 0;
 263         if ((envlen = GetEnvironmentVariableW(var = L"HOME", NULL, 0)) == 0
 264                 && (envlen = GetEnvironmentVariableW(var = L"USERPROFILE",
 265                                                   NULL, 0)) == 0)
 266             envlen = GetEnvironmentVariableW(var = L"SYSTEMROOT", NULL, 0);
 267     }
 268
 269     /* If we got a value, allocate space to hold it and then get it. */
 270     if (envlen != 0) {
 271         int sz;
 272         WCHAR *val = _alloca(envlen * sizeof(WCHAR));
 273
 274         if (GetEnvironmentVariableW(var, val, envlen) < envlen
 275                 && (sz = WideCharToMultiByte(CP_UTF8, 0, val, -1, NULL, 0,
 276                                              NULL, NULL)) != 0) {
 277             s = _alloca(sz);
 278             if (WideCharToMultiByte(CP_UTF8, 0, val, -1, s, sz,
 279                                     NULL, NULL) == 0)
 280                 s = NULL;
 281         }
 282     }
 283 #else
 284     if ((s = ossl_safe_getenv("RANDFILE")) == NULL || *s == '\0') {
 285         use_randfile = 0;
 286         s = ossl_safe_getenv("HOME");
 287     }
 288 #endif
 289
 290 #ifdef DEFAULT_HOME
 291     if (!use_randfile && s == NULL)
 292         s = DEFAULT_HOME;
 293 #endif
 294     if (s == NULL || *s == '\0')
 295         return NULL;
 296
 297     len = strlen(s);
 298     if (use_randfile) {
 299         if (len + 1 >= size)
 300             return NULL;
 301         strcpy(buf, s);
 302     } else {
 303         if (len + 1 + strlen(RFILE) + 1 >= size)
 304             return NULL;
 305         strcpy(buf, s);
 306 #ifndef OPENSSL_SYS_VMS
 307         strcat(buf, "/");
 308 #endif
 309         strcat(buf, RFILE);
 310     }
 311
 312     return buf;
 313 }