xref: /src/crypto/openssl/crypto/rand/randfile.c (revision f25b8c9fb4f58cf61adb47d7570abe7caa6d385d)
1 /*
2  * Copyright 1995-2025 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 #if defined(__TANDEM) && defined(_SPT_MODEL_)
11 /*
12  * These definitions have to come first in SPT due to scoping of the
13  * declarations in c99 associated with SPT use of stat.
14  */
15 #include <sys/types.h>
16 #include <sys/stat.h>
17 #endif
18 
19 #include "internal/e_os.h"
20 #include "internal/cryptlib.h"
21 
22 #include <errno.h>
23 #include <stdio.h>
24 #include <stdlib.h>
25 #include <string.h>
26 
27 #include <openssl/crypto.h>
28 #include <openssl/rand.h>
29 #include <openssl/buffer.h>
30 
31 #ifdef OPENSSL_SYS_VMS
32 #include <unixio.h>
33 #endif
34 #include <sys/types.h>
35 #ifndef OPENSSL_NO_POSIX_IO
36 #include <sys/stat.h>
37 #include <fcntl.h>
38 #if defined(_WIN32) && !defined(_WIN32_WCE)
39 #include <windows.h>
40 #include <io.h>
41 #define stat _stat
42 #define chmod _chmod
43 #define open _open
44 #define fdopen _fdopen
45 #define fstat _fstat
46 #define fileno _fileno
47 #endif
48 #endif
49 
50 /*
51  * Following should not be needed, and we could have been stricter
52  * and demand S_IS*. But some systems just don't comply... Formally
53  * below macros are "anatomically incorrect", because normally they
54  * would look like ((m) & MASK == TYPE), but since MASK availability
55  * is as questionable, we settle for this poor-man fallback...
56  */
57 #if !defined(S_ISREG)
58 #define S_ISREG(m) ((m) & S_IFREG)
59 #endif
60 
61 #define RAND_BUF_SIZE 1024
62 #define RFILE ".rnd"
63 
64 #ifdef OPENSSL_SYS_VMS
65 /*
66  * __FILE_ptr32 is a type provided by DEC C headers (types.h specifically)
67  * to make sure the FILE* is a 32-bit pointer no matter what.  We know that
68  * stdio functions return this type (a study of stdio.h proves it).
69  *
70  * This declaration is a nasty hack to get around vms' extension to fopen for
71  * passing in sharing options being disabled by /STANDARD=ANSI89
72  */
73 static __FILE_ptr32 (*const vms_fopen)(const char *, const char *, ...) = (__FILE_ptr32 (*)(const char *, const char *, ...))fopen;
74 #define VMS_OPEN_ATTRS \
75     "shr=get,put,upd,del", "ctx=bin,stm", "rfm=stm", "rat=none", "mrs=0"
76 #define openssl_fopen(fname, mode) vms_fopen((fname), (mode), VMS_OPEN_ATTRS)
77 #endif
78 
79 /*
80  * Note that these functions are intended for seed files only. Entropy
81  * devices and EGD sockets are handled in rand_unix.c  If |bytes| is
82  * -1 read the complete file; otherwise read the specified amount.
83  */
RAND_load_file(const char * file,long bytes)84 int RAND_load_file(const char *file, long bytes)
85 {
86     /*
87      * The load buffer size exceeds the chunk size by the comfortable amount
88      * of 'RAND_DRBG_STRENGTH' bytes (not bits!). This is done on purpose
89      * to avoid calling RAND_add() with a small final chunk. Instead, such
90      * a small final chunk will be added together with the previous chunk
91      * (unless it's the only one).
92      */
93 #define RAND_LOAD_BUF_SIZE (RAND_BUF_SIZE + RAND_DRBG_STRENGTH)
94     unsigned char buf[RAND_LOAD_BUF_SIZE];
95 
96 #ifndef OPENSSL_NO_POSIX_IO
97     struct stat sb;
98 #endif
99     int i, n, ret = 0;
100     FILE *in;
101 
102     if (bytes == 0)
103         return 0;
104 
105     if ((in = openssl_fopen(file, "rb")) == NULL) {
106         ERR_raise_data(ERR_LIB_RAND, RAND_R_CANNOT_OPEN_FILE,
107             "Filename=%s", file);
108         return -1;
109     }
110 
111 #ifndef OPENSSL_NO_POSIX_IO
112     if (fstat(fileno(in), &sb) < 0) {
113         ERR_raise_data(ERR_LIB_RAND, RAND_R_INTERNAL_ERROR,
114             "Filename=%s", file);
115         fclose(in);
116         return -1;
117     }
118 
119     if (bytes < 0) {
120         if (S_ISREG(sb.st_mode))
121             bytes = sb.st_size;
122         else
123             bytes = RAND_DRBG_STRENGTH;
124     }
125 #endif
126     /*
127      * On VMS, setbuf() will only take 32-bit pointers, and a compilation
128      * with /POINTER_SIZE=64 will give off a MAYLOSEDATA2 warning here.
129      * However, we trust that the C RTL will never give us a FILE pointer
130      * above the first 4 GB of memory, so we simply turn off the warning
131      * temporarily.
132      */
133 #if defined(OPENSSL_SYS_VMS) && defined(__DECC)
134 #pragma environment save
135 #pragma message disable maylosedata2
136 #endif
137     /*
138      * Don't buffer, because even if |file| is regular file, we have
139      * no control over the buffer, so why would we want a copy of its
140      * contents lying around?
141      */
142     setbuf(in, NULL);
143 #if defined(OPENSSL_SYS_VMS) && defined(__DECC)
144 #pragma environment restore
145 #endif
146 
147     for (;;) {
148         if (bytes > 0)
149             n = (bytes <= RAND_LOAD_BUF_SIZE) ? (int)bytes : RAND_BUF_SIZE;
150         else
151             n = RAND_LOAD_BUF_SIZE;
152         i = fread(buf, 1, n, in);
153 #ifdef EINTR
154         if (ferror(in) && errno == EINTR) {
155             clearerr(in);
156             if (i == 0)
157                 continue;
158         }
159 #endif
160         if (i == 0)
161             break;
162 
163         RAND_add(buf, i, (double)i);
164         ret += i;
165 
166         /* If given a bytecount, and we did it, break. */
167         if (bytes > 0 && (bytes -= i) <= 0)
168             break;
169 
170         /* We can hit a signed integer overflow on the next iteration */
171         if (ret > INT_MAX - RAND_LOAD_BUF_SIZE)
172             break;
173     }
174 
175     OPENSSL_cleanse(buf, sizeof(buf));
176     fclose(in);
177     if (!RAND_status()) {
178         ERR_raise_data(ERR_LIB_RAND, RAND_R_RESEED_ERROR, "Filename=%s", file);
179         return -1;
180     }
181 
182     return ret;
183 }
184 
RAND_write_file(const char * file)185 int RAND_write_file(const char *file)
186 {
187     unsigned char buf[RAND_BUF_SIZE];
188     int ret = -1;
189     FILE *out = NULL;
190 #ifndef OPENSSL_NO_POSIX_IO
191     struct stat sb;
192 
193     if (stat(file, &sb) >= 0 && !S_ISREG(sb.st_mode)) {
194         ERR_raise_data(ERR_LIB_RAND, RAND_R_NOT_A_REGULAR_FILE,
195             "Filename=%s", file);
196         return -1;
197     }
198 #endif
199 
200     /* Collect enough random data. */
201     if (RAND_priv_bytes(buf, (int)sizeof(buf)) != 1)
202         return -1;
203 
204 #if defined(O_CREAT) && !defined(OPENSSL_NO_POSIX_IO) && !defined(OPENSSL_SYS_VMS) && !defined(OPENSSL_SYS_WINDOWS)
205     {
206 #ifndef O_BINARY
207 #define O_BINARY 0
208 #endif
209         /*
210          * chmod(..., 0600) is too late to protect the file, permissions
211          * should be restrictive from the start
212          */
213         int fd = open(file, O_WRONLY | O_CREAT | O_BINARY, 0600);
214 
215         if (fd != -1) {
216             out = fdopen(fd, "wb");
217             if (out == NULL) {
218                 close(fd);
219                 ERR_raise_data(ERR_LIB_RAND, RAND_R_CANNOT_OPEN_FILE,
220                     "Filename=%s", file);
221                 return -1;
222             }
223         }
224     }
225 #endif
226 
227 #ifdef OPENSSL_SYS_VMS
228     /*
229      * VMS NOTE: Prior versions of this routine created a _new_ version of
230      * the rand file for each call into this routine, then deleted all
231      * existing versions named ;-1, and finally renamed the current version
232      * as ';1'. Under concurrent usage, this resulted in an RMS race
233      * condition in rename() which could orphan files (see vms message help
234      * for RMS$_REENT). With the fopen() calls below, openssl/VMS now shares
235      * the top-level version of the rand file. Note that there may still be
236      * conditions where the top-level rand file is locked. If so, this code
237      * will then create a new version of the rand file. Without the delete
238      * and rename code, this can result in ascending file versions that stop
239      * at version 32767, and this routine will then return an error. The
240      * remedy for this is to recode the calling application to avoid
241      * concurrent use of the rand file, or synchronize usage at the
242      * application level. Also consider whether or not you NEED a persistent
243      * rand file in a concurrent use situation.
244      */
245     out = openssl_fopen(file, "rb+");
246 #endif
247 
248     if (out == NULL)
249         out = openssl_fopen(file, "wb");
250     if (out == NULL) {
251         ERR_raise_data(ERR_LIB_RAND, RAND_R_CANNOT_OPEN_FILE,
252             "Filename=%s", file);
253         return -1;
254     }
255 
256 #if !defined(NO_CHMOD) && !defined(OPENSSL_NO_POSIX_IO)
257     /*
258      * Yes it's late to do this (see above comment), but better than nothing.
259      */
260     chmod(file, 0600);
261 #endif
262 
263     ret = fwrite(buf, 1, RAND_BUF_SIZE, out);
264     fclose(out);
265     OPENSSL_cleanse(buf, RAND_BUF_SIZE);
266     return ret;
267 }
268 
RAND_file_name(char * buf,size_t size)269 const char *RAND_file_name(char *buf, size_t size)
270 {
271     char *s = NULL;
272     size_t len;
273     int use_randfile = 1;
274 
275 #if defined(_WIN32) && defined(CP_UTF8) && !defined(_WIN32_WCE)
276     DWORD envlen;
277     WCHAR *var;
278 
279     /* Look up various environment variables. */
280     if ((envlen = GetEnvironmentVariableW(var = L"RANDFILE", NULL, 0)) == 0) {
281         use_randfile = 0;
282         if ((envlen = GetEnvironmentVariableW(var = L"HOME", NULL, 0)) == 0
283             && (envlen = GetEnvironmentVariableW(var = L"USERPROFILE",
284                     NULL, 0))
285                 == 0)
286             envlen = GetEnvironmentVariableW(var = L"SYSTEMROOT", NULL, 0);
287     }
288 
289     /* If we got a value, allocate space to hold it and then get it. */
290     if (envlen != 0) {
291         int sz;
292         WCHAR *val = _alloca(envlen * sizeof(WCHAR));
293 
294         if (GetEnvironmentVariableW(var, val, envlen) < envlen
295             && (sz = WideCharToMultiByte(CP_UTF8, 0, val, -1, NULL, 0,
296                     NULL, NULL))
297                 != 0) {
298             s = _alloca(sz);
299             if (WideCharToMultiByte(CP_UTF8, 0, val, -1, s, sz,
300                     NULL, NULL)
301                 == 0)
302                 s = NULL;
303         }
304     }
305 #else
306     if ((s = ossl_safe_getenv("RANDFILE")) == NULL || *s == '\0') {
307         use_randfile = 0;
308         s = ossl_safe_getenv("HOME");
309     }
310 #endif
311 
312 #ifdef DEFAULT_HOME
313     if (!use_randfile && s == NULL)
314         s = DEFAULT_HOME;
315 #endif
316     if (s == NULL || *s == '\0')
317         return NULL;
318 
319     len = strlen(s);
320     if (use_randfile) {
321         if (len + 1 >= size)
322             return NULL;
323         strcpy(buf, s);
324     } else {
325         if (len + 1 + strlen(RFILE) + 1 >= size)
326             return NULL;
327         strcpy(buf, s);
328 #ifndef OPENSSL_SYS_VMS
329         strcat(buf, "/");
330 #endif
331         strcat(buf, RFILE);
332     }
333 
334     return buf;
335 }
336