Line data Source code
1 : /* random.c - Random number switch
2 : * Copyright (C) 2003, 2006, 2008, 2012 Free Software Foundation, Inc.
3 : *
4 : * This file is part of Libgcrypt.
5 : *
6 : * Libgcrypt is free software; you can redistribute it and/or modify
7 : * it under the terms of the GNU Lesser General Public License as
8 : * published by the Free Software Foundation; either version 2.1 of
9 : * the License, or (at your option) any later version.
10 : *
11 : * Libgcrypt is distributed in the hope that it will be useful,
12 : * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 : * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 : * GNU Lesser General Public License for more details.
15 : *
16 : * You should have received a copy of the GNU Lesser General Public
17 : * License along with this program; if not, see <http://www.gnu.org/licenses/>.
18 : */
19 :
20 : /*
21 : This module switches between different implementations of random
22 : number generators and provides a few help functions.
23 : */
24 :
25 : #include <config.h>
26 : #include <stdio.h>
27 : #include <stdlib.h>
28 : #include <errno.h>
29 : #include <time.h>
30 : #include <sys/types.h>
31 : #include <unistd.h>
32 :
33 : #include "g10lib.h"
34 : #include "random.h"
35 : #include "rand-internal.h"
36 : #include "cipher.h" /* For _gcry_sha1_hash_buffer(). */
37 :
38 :
39 : /* If not NULL a progress function called from certain places and the
40 : opaque value passed along. Registered by
41 : _gcry_register_random_progress (). */
42 : static void (*progress_cb) (void *,const char*,int,int, int );
43 : static void *progress_cb_data;
44 :
45 : /* Flags indicating the requested RNG types. */
46 : static struct
47 : {
48 : int standard;
49 : int fips;
50 : int system;
51 : } rng_types;
52 :
53 :
54 : /* This is the lock we use to protect the buffer used by the nonce
55 : generation. */
56 : GPGRT_LOCK_DEFINE (nonce_buffer_lock);
57 :
58 :
59 :
60 : /* --- Functions --- */
61 :
62 :
63 : /* Used to register a progress callback. This needs to be called
64 : before any threads are created. */
65 : void
66 0 : _gcry_register_random_progress (void (*cb)(void *,const char*,int,int,int),
67 : void *cb_data )
68 : {
69 0 : progress_cb = cb;
70 0 : progress_cb_data = cb_data;
71 0 : }
72 :
73 :
74 : /* This progress function is currently used by the random modules to
75 : give hints on how much more entropy is required. */
76 : void
77 0 : _gcry_random_progress (const char *what, int printchar, int current, int total)
78 : {
79 0 : if (progress_cb)
80 0 : progress_cb (progress_cb_data, what, printchar, current, total);
81 0 : }
82 :
83 :
84 : /* Set the preferred RNG type. This may be called at any time even
85 : before gcry_check_version. Thus we can't assume any thread system
86 : initialization. A type of 0 is used to indicate that any Libgcrypt
87 : initialization has been done.*/
88 : void
89 0 : _gcry_set_preferred_rng_type (int type)
90 : {
91 : static int any_init;
92 :
93 0 : if (!type)
94 : {
95 0 : any_init = 1;
96 : }
97 0 : else if (type == GCRY_RNG_TYPE_STANDARD)
98 : {
99 0 : rng_types.standard = 1;
100 : }
101 0 : else if (any_init)
102 : {
103 : /* After any initialization has been done we only allow to
104 : upgrade to the standard RNG (handled above). All other
105 : requests are ignored. The idea is that the application needs
106 : to declare a preference for a weaker RNG as soon as possible
107 : and before any library sets a preference. We assume that a
108 : library which uses Libgcrypt calls an init function very
109 : early. This way --- even if the library gets initialized
110 : early by the application --- it is unlikely that it can
111 : select a lower priority RNG.
112 :
113 : This scheme helps to ensure that existing unmodified
114 : applications (e.g. gpg2), which don't known about the new RNG
115 : selection system, will continue to use the standard RNG and
116 : not be tricked by some library to use a lower priority RNG.
117 : There are some loopholes here but at least most GnuPG stuff
118 : should be save because it calls src_c{gcry_control
119 : (GCRYCTL_SUSPEND_SECMEM_WARN);} quite early and thus inhibits
120 : switching to a low priority RNG.
121 : */
122 : }
123 0 : else if (type == GCRY_RNG_TYPE_FIPS)
124 : {
125 0 : rng_types.fips = 1;
126 : }
127 0 : else if (type == GCRY_RNG_TYPE_SYSTEM)
128 : {
129 0 : rng_types.system = 1;
130 : }
131 0 : }
132 :
133 :
134 : /* Initialize this random subsystem. If FULL is false, this function
135 : merely calls the basic initialization of the module and does not do
136 : anything more. Doing this is not really required but when running
137 : in a threaded environment we might get a race condition
138 : otherwise. */
139 : void
140 0 : _gcry_random_initialize (int full)
141 : {
142 0 : if (fips_mode ())
143 0 : _gcry_rngdrbg_inititialize (full);
144 0 : else if (rng_types.standard)
145 0 : _gcry_rngcsprng_initialize (full);
146 0 : else if (rng_types.fips)
147 0 : _gcry_rngdrbg_inititialize (full);
148 0 : else if (rng_types.system)
149 0 : _gcry_rngsystem_initialize (full);
150 : else
151 0 : _gcry_rngcsprng_initialize (full);
152 0 : }
153 :
154 :
155 : /* If possible close file descriptors used by the RNG. */
156 : void
157 0 : _gcry_random_close_fds (void)
158 : {
159 : /* Note that we can't do that directly because each random system
160 : has its own lock functions which need to be used for accessing
161 : the entropy gatherer. */
162 :
163 0 : if (fips_mode ())
164 0 : _gcry_rngdrbg_close_fds ();
165 0 : else if (rng_types.standard)
166 0 : _gcry_rngcsprng_close_fds ();
167 0 : else if (rng_types.fips)
168 0 : _gcry_rngdrbg_close_fds ();
169 0 : else if (rng_types.system)
170 0 : _gcry_rngsystem_close_fds ();
171 : else
172 0 : _gcry_rngcsprng_close_fds ();
173 0 : }
174 :
175 :
176 : /* Return the current RNG type. IGNORE_FIPS_MODE is a flag used to
177 : skip the test for FIPS. This is useful, so that we are able to
178 : return the type of the RNG even before we have setup FIPS mode
179 : (note that FIPS mode is enabled by default until it is switched off
180 : by the initialization). This is mostly useful for the regression
181 : test. */
182 : int
183 0 : _gcry_get_rng_type (int ignore_fips_mode)
184 : {
185 0 : if (!ignore_fips_mode && fips_mode ())
186 0 : return GCRY_RNG_TYPE_FIPS;
187 0 : else if (rng_types.standard)
188 0 : return GCRY_RNG_TYPE_STANDARD;
189 0 : else if (rng_types.fips)
190 0 : return GCRY_RNG_TYPE_FIPS;
191 0 : else if (rng_types.system)
192 0 : return GCRY_RNG_TYPE_SYSTEM;
193 : else
194 0 : return GCRY_RNG_TYPE_STANDARD;
195 : }
196 :
197 :
198 : void
199 0 : _gcry_random_dump_stats (void)
200 : {
201 0 : if (fips_mode ())
202 0 : _gcry_rngdrbg_dump_stats ();
203 : else
204 0 : _gcry_rngcsprng_dump_stats ();
205 0 : }
206 :
207 :
208 : /* This function should be called during initialization and before
209 : initialization of this module to place the random pools into secure
210 : memory. */
211 : void
212 0 : _gcry_secure_random_alloc (void)
213 : {
214 0 : if (fips_mode ())
215 : ; /* Not used; the FIPS RNG is always in secure mode. */
216 : else
217 0 : _gcry_rngcsprng_secure_alloc ();
218 0 : }
219 :
220 :
221 : /* This may be called before full initialization to degrade the
222 : quality of the RNG for the sake of a faster running test suite. */
223 : void
224 0 : _gcry_enable_quick_random_gen (void)
225 : {
226 0 : if (fips_mode ())
227 : ; /* Not used. */
228 : else
229 0 : _gcry_rngcsprng_enable_quick_gen ();
230 0 : }
231 :
232 :
233 : void
234 0 : _gcry_set_random_daemon_socket (const char *socketname)
235 : {
236 0 : if (fips_mode ())
237 : ; /* Not used. */
238 : else
239 0 : _gcry_rngcsprng_set_daemon_socket (socketname);
240 0 : }
241 :
242 : /* With ONOFF set to 1, enable the use of the daemon. With ONOFF set
243 : to 0, disable the use of the daemon. With ONOF set to -1, return
244 : whether the daemon has been enabled. */
245 : int
246 0 : _gcry_use_random_daemon (int onoff)
247 : {
248 0 : if (fips_mode ())
249 0 : return 0; /* Never enabled in fips mode. */
250 : else
251 0 : return _gcry_rngcsprng_use_daemon (onoff);
252 : }
253 :
254 :
255 : /* This function returns true if no real RNG is available or the
256 : quality of the RNG has been degraded for test purposes. */
257 : int
258 0 : _gcry_random_is_faked (void)
259 : {
260 0 : if (fips_mode ())
261 0 : return _gcry_rngdrbg_is_faked ();
262 : else
263 0 : return _gcry_rngcsprng_is_faked ();
264 : }
265 :
266 :
267 : /* Add BUFLEN bytes from BUF to the internal random pool. QUALITY
268 : should be in the range of 0..100 to indicate the goodness of the
269 : entropy added, or -1 for goodness not known. */
270 : gcry_err_code_t
271 0 : _gcry_random_add_bytes (const void *buf, size_t buflen, int quality)
272 : {
273 0 : if (fips_mode ())
274 0 : return 0; /* No need for this in fips mode. */
275 0 : else if (rng_types.standard)
276 0 : return gpg_err_code (_gcry_rngcsprng_add_bytes (buf, buflen, quality));
277 0 : else if (rng_types.fips)
278 0 : return 0;
279 0 : else if (rng_types.system)
280 0 : return 0;
281 : else /* default */
282 0 : return gpg_err_code (_gcry_rngcsprng_add_bytes (buf, buflen, quality));
283 : }
284 :
285 :
286 : /* Helper function. */
287 : static void
288 0 : do_randomize (void *buffer, size_t length, enum gcry_random_level level)
289 : {
290 0 : if (fips_mode ())
291 0 : _gcry_rngdrbg_randomize (buffer, length, level);
292 0 : else if (rng_types.standard)
293 0 : _gcry_rngcsprng_randomize (buffer, length, level);
294 0 : else if (rng_types.fips)
295 0 : _gcry_rngdrbg_randomize (buffer, length, level);
296 0 : else if (rng_types.system)
297 0 : _gcry_rngsystem_randomize (buffer, length, level);
298 : else /* default */
299 0 : _gcry_rngcsprng_randomize (buffer, length, level);
300 0 : }
301 :
302 : /* The public function to return random data of the quality LEVEL.
303 : Returns a pointer to a newly allocated and randomized buffer of
304 : LEVEL and NBYTES length. Caller must free the buffer. */
305 : void *
306 0 : _gcry_random_bytes (size_t nbytes, enum gcry_random_level level)
307 : {
308 : void *buffer;
309 :
310 0 : buffer = xmalloc (nbytes);
311 0 : do_randomize (buffer, nbytes, level);
312 0 : return buffer;
313 : }
314 :
315 :
316 : /* The public function to return random data of the quality LEVEL;
317 : this version of the function returns the random in a buffer allocated
318 : in secure memory. Caller must free the buffer. */
319 : void *
320 0 : _gcry_random_bytes_secure (size_t nbytes, enum gcry_random_level level)
321 : {
322 : void *buffer;
323 :
324 : /* Historical note (1.3.0--1.4.1): The buffer was only allocated
325 : in secure memory if the pool in random-csprng.c was also set to
326 : use secure memory. */
327 0 : buffer = xmalloc_secure (nbytes);
328 0 : do_randomize (buffer, nbytes, level);
329 0 : return buffer;
330 : }
331 :
332 :
333 : /* Public function to fill the buffer with LENGTH bytes of
334 : cryptographically strong random bytes. Level GCRY_WEAK_RANDOM is
335 : not very strong, GCRY_STRONG_RANDOM is strong enough for most
336 : usage, GCRY_VERY_STRONG_RANDOM is good for key generation stuff but
337 : may be very slow. */
338 : void
339 0 : _gcry_randomize (void *buffer, size_t length, enum gcry_random_level level)
340 : {
341 0 : do_randomize (buffer, length, level);
342 0 : }
343 :
344 :
345 : /* This function may be used to specify the file to be used as a seed
346 : file for the PRNG. This function should be called prior to the
347 : initialization of the random module. NAME may not be NULL. */
348 : void
349 0 : _gcry_set_random_seed_file (const char *name)
350 : {
351 0 : if (fips_mode ())
352 : ; /* No need for this in fips mode. */
353 0 : else if (rng_types.standard)
354 0 : _gcry_rngcsprng_set_seed_file (name);
355 0 : else if (rng_types.fips)
356 : ;
357 0 : else if (rng_types.system)
358 : ;
359 : else /* default */
360 0 : _gcry_rngcsprng_set_seed_file (name);
361 0 : }
362 :
363 :
364 : /* If a seed file has been setup, this function may be used to write
365 : back the random numbers entropy pool. */
366 : void
367 0 : _gcry_update_random_seed_file (void)
368 : {
369 0 : if (fips_mode ())
370 : ; /* No need for this in fips mode. */
371 0 : else if (rng_types.standard)
372 0 : _gcry_rngcsprng_update_seed_file ();
373 0 : else if (rng_types.fips)
374 : ;
375 0 : else if (rng_types.system)
376 : ;
377 : else /* default */
378 0 : _gcry_rngcsprng_update_seed_file ();
379 0 : }
380 :
381 :
382 :
383 : /* The fast random pool function as called at some places in
384 : libgcrypt. This is merely a wrapper to make sure that this module
385 : is initialized and to lock the pool. Note, that this function is a
386 : NOP unless a random function has been used or _gcry_initialize (1)
387 : has been used. We use this hack so that the internal use of this
388 : function in cipher_open and md_open won't start filling up the
389 : random pool, even if no random will be required by the process. */
390 : void
391 0 : _gcry_fast_random_poll (void)
392 : {
393 0 : if (fips_mode ())
394 : ; /* No need for this in fips mode. */
395 0 : else if (rng_types.standard)
396 0 : _gcry_rngcsprng_fast_poll ();
397 0 : else if (rng_types.fips)
398 : ;
399 0 : else if (rng_types.system)
400 : ;
401 : else /* default */
402 0 : _gcry_rngcsprng_fast_poll ();
403 0 : }
404 :
405 :
406 :
407 : /* Create an unpredicable nonce of LENGTH bytes in BUFFER. */
408 : void
409 0 : _gcry_create_nonce (void *buffer, size_t length)
410 : {
411 : static unsigned char nonce_buffer[20+8];
412 : static int nonce_buffer_initialized = 0;
413 : static volatile pid_t my_pid; /* The volatile is there to make sure the
414 : compiler does not optimize the code away
415 : in case the getpid function is badly
416 : attributed. */
417 : volatile pid_t apid;
418 : unsigned char *p;
419 : size_t n;
420 : int err;
421 :
422 : /* First check whether we shall use the FIPS nonce generator. This
423 : is only done in FIPS mode, in all other modes, we use our own
424 : nonce generator which is seeded by the RNG actual in use. */
425 0 : if (fips_mode ())
426 : {
427 0 : _gcry_rngdrbg_randomize (buffer, length, GCRY_WEAK_RANDOM);
428 0 : return;
429 : }
430 :
431 : /* This is the nonce generator, which formerly lived in
432 : random-csprng.c. It is now used by all RNG types except when in
433 : FIPS mode (not that this means it is also used if the FIPS RNG
434 : has been selected but we are not in fips mode). */
435 :
436 : /* Make sure we are initialized. */
437 0 : _gcry_random_initialize (1);
438 :
439 : /* Acquire the nonce buffer lock. */
440 0 : err = gpgrt_lock_lock (&nonce_buffer_lock);
441 0 : if (err)
442 0 : log_fatal ("failed to acquire the nonce buffer lock: %s\n",
443 : gpg_strerror (err));
444 :
445 0 : apid = getpid ();
446 : /* The first time initialize our buffer. */
447 0 : if (!nonce_buffer_initialized)
448 : {
449 0 : time_t atime = time (NULL);
450 0 : pid_t xpid = apid;
451 :
452 0 : my_pid = apid;
453 :
454 : if ((sizeof apid + sizeof atime) > sizeof nonce_buffer)
455 : BUG ();
456 :
457 : /* Initialize the first 20 bytes with a reasonable value so that
458 : a failure of gcry_randomize won't affect us too much. Don't
459 : care about the uninitialized remaining bytes. */
460 0 : p = nonce_buffer;
461 0 : memcpy (p, &xpid, sizeof xpid);
462 0 : p += sizeof xpid;
463 0 : memcpy (p, &atime, sizeof atime);
464 :
465 : /* Initialize the never changing private part of 64 bits. */
466 0 : _gcry_randomize (nonce_buffer+20, 8, GCRY_WEAK_RANDOM);
467 :
468 0 : nonce_buffer_initialized = 1;
469 : }
470 0 : else if ( my_pid != apid )
471 : {
472 : /* We forked. Need to reseed the buffer - doing this for the
473 : private part should be sufficient. */
474 0 : do_randomize (nonce_buffer+20, 8, GCRY_WEAK_RANDOM);
475 : /* Update the pid so that we won't run into here again and
476 : again. */
477 0 : my_pid = apid;
478 : }
479 :
480 : /* Create the nonce by hashing the entire buffer, returning the hash
481 : and updating the first 20 bytes of the buffer with this hash. */
482 0 : for (p = buffer; length > 0; length -= n, p += n)
483 : {
484 0 : _gcry_sha1_hash_buffer (nonce_buffer,
485 : nonce_buffer, sizeof nonce_buffer);
486 0 : n = length > 20? 20 : length;
487 0 : memcpy (p, nonce_buffer, n);
488 : }
489 :
490 : /* Release the nonce buffer lock. */
491 0 : err = gpgrt_lock_unlock (&nonce_buffer_lock);
492 0 : if (err)
493 0 : log_fatal ("failed to release the nonce buffer lock: %s\n",
494 : gpg_strerror (err));
495 : }
496 :
497 :
498 : /* Run the self-tests for the RNG. This is currently only implemented
499 : for the FIPS generator. */
500 : gpg_error_t
501 0 : _gcry_random_selftest (selftest_report_func_t report)
502 : {
503 0 : if (fips_mode ())
504 0 : return _gcry_rngdrbg_selftest (report);
505 : else
506 0 : return 0; /* No selftests yet. */
507 : }
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