1 /*
2 * Copyright 1995-2024 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 #ifndef _GNU_SOURCE
11 # define _GNU_SOURCE
12 #endif
13 #include "internal/e_os.h"
14 #include <stdio.h>
15 #include "internal/cryptlib.h"
16 #include <openssl/rand.h>
17 #include <openssl/crypto.h>
18 #include "crypto/rand_pool.h"
19 #include "crypto/rand.h"
20 #include "internal/dso.h"
21 #include "internal/nelem.h"
22 #include "prov/seeding.h"
23
24 #ifdef __linux
25 # include <sys/syscall.h>
26 # ifdef DEVRANDOM_WAIT
27 # include <sys/shm.h>
28 # include <sys/utsname.h>
29 # endif
30 #endif
31 #if (defined(__FreeBSD__) || defined(__NetBSD__)) && !defined(OPENSSL_SYS_UEFI)
32 # include <sys/types.h>
33 # include <sys/sysctl.h>
34 # include <sys/param.h>
35 #endif
36 #if defined(__OpenBSD__)
37 # include <sys/param.h>
38 #endif
39 #if defined(__DragonFly__)
40 # include <sys/param.h>
41 # include <sys/random.h>
42 #endif
43
44 #if (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS)) \
45 || defined(__DJGPP__)
46 # include <sys/types.h>
47 # include <sys/stat.h>
48 # include <fcntl.h>
49 # include <unistd.h>
50 # include <sys/time.h>
51
52 static uint64_t get_time_stamp(void);
53
54 /* Macro to convert two thirty two bit values into a sixty four bit one */
55 # define TWO32TO64(a, b) ((((uint64_t)(a)) << 32) + (b))
56
57 /*
58 * Check for the existence and support of POSIX timers. The standard
59 * says that the _POSIX_TIMERS macro will have a positive value if they
60 * are available.
61 *
62 * However, we want an additional constraint: that the timer support does
63 * not require an extra library dependency. Early versions of glibc
64 * require -lrt to be specified on the link line to access the timers,
65 * so this needs to be checked for.
66 *
67 * It is worse because some libraries define __GLIBC__ but don't
68 * support the version testing macro (e.g. uClibc). This means
69 * an extra check is needed.
70 *
71 * The final condition is:
72 * "have posix timers and either not glibc or glibc without -lrt"
73 *
74 * The nested #if sequences are required to avoid using a parameterised
75 * macro that might be undefined.
76 */
77 # undef OSSL_POSIX_TIMER_OKAY
78 /* On some systems, _POSIX_TIMERS is defined but empty.
79 * Subtracting by 0 when comparing avoids an error in this case. */
80 # if defined(_POSIX_TIMERS) && _POSIX_TIMERS -0 > 0
81 # if defined(__GLIBC__)
82 # if defined(__GLIBC_PREREQ)
83 # if __GLIBC_PREREQ(2, 17)
84 # define OSSL_POSIX_TIMER_OKAY
85 # endif
86 # endif
87 # else
88 # define OSSL_POSIX_TIMER_OKAY
89 # endif
90 # endif
91 #endif /* (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS))
92 || defined(__DJGPP__) */
93
94 #if defined(OPENSSL_RAND_SEED_NONE)
95 /* none means none. this simplifies the following logic */
96 # undef OPENSSL_RAND_SEED_OS
97 # undef OPENSSL_RAND_SEED_GETRANDOM
98 # undef OPENSSL_RAND_SEED_DEVRANDOM
99 # undef OPENSSL_RAND_SEED_RDTSC
100 # undef OPENSSL_RAND_SEED_RDCPU
101 # undef OPENSSL_RAND_SEED_EGD
102 #endif
103
104 #if defined(OPENSSL_SYS_UEFI) && !defined(OPENSSL_RAND_SEED_NONE)
105 # error "UEFI only supports seeding NONE"
106 #endif
107
108 #if !(defined(OPENSSL_SYS_WINDOWS) || defined(OPENSSL_SYS_WIN32) \
109 || defined(OPENSSL_SYS_VMS) || defined(OPENSSL_SYS_VXWORKS) \
110 || defined(OPENSSL_SYS_UEFI))
111
112 # if defined(OPENSSL_SYS_VOS)
113
114 # ifndef OPENSSL_RAND_SEED_OS
115 # error "Unsupported seeding method configured; must be os"
116 # endif
117
118 # if defined(OPENSSL_SYS_VOS_HPPA) && defined(OPENSSL_SYS_VOS_IA32)
119 # error "Unsupported HP-PA and IA32 at the same time."
120 # endif
121 # if !defined(OPENSSL_SYS_VOS_HPPA) && !defined(OPENSSL_SYS_VOS_IA32)
122 # error "Must have one of HP-PA or IA32"
123 # endif
124
125 /*
126 * The following algorithm repeatedly samples the real-time clock (RTC) to
127 * generate a sequence of unpredictable data. The algorithm relies upon the
128 * uneven execution speed of the code (due to factors such as cache misses,
129 * interrupts, bus activity, and scheduling) and upon the rather large
130 * relative difference between the speed of the clock and the rate at which
131 * it can be read. If it is ported to an environment where execution speed
132 * is more constant or where the RTC ticks at a much slower rate, or the
133 * clock can be read with fewer instructions, it is likely that the results
134 * would be far more predictable. This should only be used for legacy
135 * platforms.
136 *
137 * As a precaution, we assume only 2 bits of entropy per byte.
138 */
ossl_pool_acquire_entropy(RAND_POOL * pool)139 size_t ossl_pool_acquire_entropy(RAND_POOL *pool)
140 {
141 short int code;
142 int i, k;
143 size_t bytes_needed;
144 struct timespec ts;
145 unsigned char v;
146 # ifdef OPENSSL_SYS_VOS_HPPA
147 long duration;
148 extern void s$sleep(long *_duration, short int *_code);
149 # else
150 long long duration;
151 extern void s$sleep2(long long *_duration, short int *_code);
152 # endif
153
154 bytes_needed = ossl_rand_pool_bytes_needed(pool, 4 /*entropy_factor*/);
155
156 for (i = 0; i < bytes_needed; i++) {
157 /*
158 * burn some cpu; hope for interrupts, cache collisions, bus
159 * interference, etc.
160 */
161 for (k = 0; k < 99; k++)
162 ts.tv_nsec = random();
163
164 # ifdef OPENSSL_SYS_VOS_HPPA
165 /* sleep for 1/1024 of a second (976 us). */
166 duration = 1;
167 s$sleep(&duration, &code);
168 # else
169 /* sleep for 1/65536 of a second (15 us). */
170 duration = 1;
171 s$sleep2(&duration, &code);
172 # endif
173
174 /* Get wall clock time, take 8 bits. */
175 clock_gettime(CLOCK_REALTIME, &ts);
176 v = (unsigned char)(ts.tv_nsec & 0xFF);
177 ossl_rand_pool_add(pool, arg, &v, sizeof(v), 2);
178 }
179 return ossl_rand_pool_entropy_available(pool);
180 }
181
ossl_rand_pool_cleanup(void)182 void ossl_rand_pool_cleanup(void)
183 {
184 }
185
ossl_rand_pool_keep_random_devices_open(int keep)186 void ossl_rand_pool_keep_random_devices_open(int keep)
187 {
188 }
189
190 # else
191
192 # if defined(OPENSSL_RAND_SEED_EGD) && \
193 (defined(OPENSSL_NO_EGD) || !defined(DEVRANDOM_EGD))
194 # error "Seeding uses EGD but EGD is turned off or no device given"
195 # endif
196
197 # if defined(OPENSSL_RAND_SEED_DEVRANDOM) && !defined(DEVRANDOM)
198 # error "Seeding uses urandom but DEVRANDOM is not configured"
199 # endif
200
201 # if defined(OPENSSL_RAND_SEED_OS)
202 # if !defined(DEVRANDOM)
203 # error "OS seeding requires DEVRANDOM to be configured"
204 # endif
205 # define OPENSSL_RAND_SEED_GETRANDOM
206 # define OPENSSL_RAND_SEED_DEVRANDOM
207 # endif
208
209 # if (defined(__FreeBSD__) || defined(__NetBSD__)) && defined(KERN_ARND)
210 /*
211 * sysctl_random(): Use sysctl() to read a random number from the kernel
212 * Returns the number of bytes returned in buf on success, -1 on failure.
213 */
sysctl_random(char * buf,size_t buflen)214 static ssize_t sysctl_random(char *buf, size_t buflen)
215 {
216 int mib[2];
217 size_t done = 0;
218 size_t len;
219
220 /*
221 * Note: sign conversion between size_t and ssize_t is safe even
222 * without a range check, see comment in syscall_random()
223 */
224
225 /*
226 * On FreeBSD old implementations returned longs, newer versions support
227 * variable sizes up to 256 byte. The code below would not work properly
228 * when the sysctl returns long and we want to request something not a
229 * multiple of longs, which should never be the case.
230 */
231 #if defined(__FreeBSD__)
232 if (!ossl_assert(buflen % sizeof(long) == 0)) {
233 errno = EINVAL;
234 return -1;
235 }
236 #endif
237
238 /*
239 * On NetBSD before 4.0 KERN_ARND was an alias for KERN_URND, and only
240 * filled in an int, leaving the rest uninitialized. Since NetBSD 4.0
241 * it returns a variable number of bytes with the current version supporting
242 * up to 256 bytes.
243 * Just return an error on older NetBSD versions.
244 */
245 #if defined(__NetBSD__) && __NetBSD_Version__ < 400000000
246 errno = ENOSYS;
247 return -1;
248 #endif
249
250 mib[0] = CTL_KERN;
251 mib[1] = KERN_ARND;
252
253 do {
254 len = buflen > 256 ? 256 : buflen;
255 if (sysctl(mib, 2, buf, &len, NULL, 0) == -1)
256 return done > 0 ? done : -1;
257 done += len;
258 buf += len;
259 buflen -= len;
260 } while (buflen > 0);
261
262 return done;
263 }
264 # endif
265
266 # if defined(OPENSSL_RAND_SEED_GETRANDOM)
267
268 # if defined(__linux) && !defined(__NR_getrandom)
269 # if defined(__arm__)
270 # define __NR_getrandom (__NR_SYSCALL_BASE+384)
271 # elif defined(__i386__)
272 # define __NR_getrandom 355
273 # elif defined(__x86_64__)
274 # if defined(__ILP32__)
275 # define __NR_getrandom (__X32_SYSCALL_BIT + 318)
276 # else
277 # define __NR_getrandom 318
278 # endif
279 # elif defined(__xtensa__)
280 # define __NR_getrandom 338
281 # elif defined(__s390__) || defined(__s390x__)
282 # define __NR_getrandom 349
283 # elif defined(__bfin__)
284 # define __NR_getrandom 389
285 # elif defined(__powerpc__)
286 # define __NR_getrandom 359
287 # elif defined(__mips__) || defined(__mips64)
288 # if _MIPS_SIM == _MIPS_SIM_ABI32
289 # define __NR_getrandom (__NR_Linux + 353)
290 # elif _MIPS_SIM == _MIPS_SIM_ABI64
291 # define __NR_getrandom (__NR_Linux + 313)
292 # elif _MIPS_SIM == _MIPS_SIM_NABI32
293 # define __NR_getrandom (__NR_Linux + 317)
294 # endif
295 # elif defined(__hppa__)
296 # define __NR_getrandom (__NR_Linux + 339)
297 # elif defined(__sparc__)
298 # define __NR_getrandom 347
299 # elif defined(__ia64__)
300 # define __NR_getrandom 1339
301 # elif defined(__alpha__)
302 # define __NR_getrandom 511
303 # elif defined(__sh__)
304 # if defined(__SH5__)
305 # define __NR_getrandom 373
306 # else
307 # define __NR_getrandom 384
308 # endif
309 # elif defined(__avr32__)
310 # define __NR_getrandom 317
311 # elif defined(__microblaze__)
312 # define __NR_getrandom 385
313 # elif defined(__m68k__)
314 # define __NR_getrandom 352
315 # elif defined(__cris__)
316 # define __NR_getrandom 356
317 # else /* generic (f.e. aarch64, loongarch, loongarch64) */
318 # define __NR_getrandom 278
319 # endif
320 # endif
321
322 /*
323 * syscall_random(): Try to get random data using a system call
324 * returns the number of bytes returned in buf, or < 0 on error.
325 */
syscall_random(void * buf,size_t buflen)326 static ssize_t syscall_random(void *buf, size_t buflen)
327 {
328 /*
329 * Note: 'buflen' equals the size of the buffer which is used by the
330 * get_entropy() callback of the RAND_DRBG. It is roughly bounded by
331 *
332 * 2 * RAND_POOL_FACTOR * (RAND_DRBG_STRENGTH / 8) = 2^14
333 *
334 * which is way below the OSSL_SSIZE_MAX limit. Therefore sign conversion
335 * between size_t and ssize_t is safe even without a range check.
336 */
337
338 /*
339 * Do runtime detection to find getentropy().
340 *
341 * Known OSs that should support this:
342 * - Darwin since 16 (OSX 10.12, IOS 10.0).
343 * - Solaris since 11.3
344 * - OpenBSD since 5.6
345 * - Linux since 3.17 with glibc 2.25
346 * - FreeBSD since 12.0 (1200061)
347 *
348 * Note: Sometimes getentropy() can be provided but not implemented
349 * internally. So we need to check errno for ENOSYS
350 */
351 # if !defined(__DragonFly__) && !defined(__NetBSD__)
352 # if defined(__GNUC__) && __GNUC__>=2 && defined(__ELF__) && !defined(__hpux)
353 extern int getentropy(void *buffer, size_t length) __attribute__((weak));
354
355 if (getentropy != NULL) {
356 if (getentropy(buf, buflen) == 0)
357 return (ssize_t)buflen;
358 if (errno != ENOSYS)
359 return -1;
360 }
361 # elif defined(OPENSSL_APPLE_CRYPTO_RANDOM)
362
363 if (CCRandomGenerateBytes(buf, buflen) == kCCSuccess)
364 return (ssize_t)buflen;
365
366 return -1;
367 # else
368 union {
369 void *p;
370 int (*f)(void *buffer, size_t length);
371 } p_getentropy;
372
373 /*
374 * We could cache the result of the lookup, but we normally don't
375 * call this function often.
376 */
377 ERR_set_mark();
378 p_getentropy.p = DSO_global_lookup("getentropy");
379 ERR_pop_to_mark();
380 if (p_getentropy.p != NULL)
381 return p_getentropy.f(buf, buflen) == 0 ? (ssize_t)buflen : -1;
382 # endif
383 # endif /* !__DragonFly__ */
384
385 /* Linux supports this since version 3.17 */
386 # if defined(__linux) && defined(__NR_getrandom)
387 return syscall(__NR_getrandom, buf, buflen, 0);
388 # elif (defined(__FreeBSD__) || defined(__NetBSD__)) && defined(KERN_ARND)
389 return sysctl_random(buf, buflen);
390 # elif (defined(__DragonFly__) && __DragonFly_version >= 500700) \
391 || (defined(__NetBSD__) && __NetBSD_Version >= 1000000000)
392 return getrandom(buf, buflen, 0);
393 # elif defined(__wasi__)
394 if (getentropy(buf, buflen) == 0)
395 return (ssize_t)buflen;
396 return -1;
397 # else
398 errno = ENOSYS;
399 return -1;
400 # endif
401 }
402 # endif /* defined(OPENSSL_RAND_SEED_GETRANDOM) */
403
404 # if defined(OPENSSL_RAND_SEED_DEVRANDOM)
405 static const char *random_device_paths[] = { DEVRANDOM };
406 static struct random_device {
407 int fd;
408 dev_t dev;
409 ino_t ino;
410 mode_t mode;
411 dev_t rdev;
412 } random_devices[OSSL_NELEM(random_device_paths)];
413 static int keep_random_devices_open = 1;
414
415 # if defined(__linux) && defined(DEVRANDOM_WAIT) \
416 && defined(OPENSSL_RAND_SEED_GETRANDOM)
417 static void *shm_addr;
418
cleanup_shm(void)419 static void cleanup_shm(void)
420 {
421 shmdt(shm_addr);
422 }
423
424 /*
425 * Ensure that the system randomness source has been adequately seeded.
426 * This is done by having the first start of libcrypto, wait until the device
427 * /dev/random becomes able to supply a byte of entropy. Subsequent starts
428 * of the library and later reseedings do not need to do this.
429 */
wait_random_seeded(void)430 static int wait_random_seeded(void)
431 {
432 static int seeded = OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID < 0;
433 static const int kernel_version[] = { DEVRANDOM_SAFE_KERNEL };
434 int kernel[2];
435 int shm_id, fd, r;
436 char c, *p;
437 struct utsname un;
438 fd_set fds;
439
440 if (!seeded) {
441 /* See if anything has created the global seeded indication */
442 if ((shm_id = shmget(OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID, 1, 0)) == -1) {
443 /*
444 * Check the kernel's version and fail if it is too recent.
445 *
446 * Linux kernels from 4.8 onwards do not guarantee that
447 * /dev/urandom is properly seeded when /dev/random becomes
448 * readable. However, such kernels support the getentropy(2)
449 * system call and this should always succeed which renders
450 * this alternative but essentially identical source moot.
451 */
452 if (uname(&un) == 0) {
453 kernel[0] = atoi(un.release);
454 p = strchr(un.release, '.');
455 kernel[1] = p == NULL ? 0 : atoi(p + 1);
456 if (kernel[0] > kernel_version[0]
457 || (kernel[0] == kernel_version[0]
458 && kernel[1] >= kernel_version[1])) {
459 return 0;
460 }
461 }
462 /* Open /dev/random and wait for it to be readable */
463 if ((fd = open(DEVRANDOM_WAIT, O_RDONLY)) != -1) {
464 if (DEVRANDM_WAIT_USE_SELECT && fd < FD_SETSIZE) {
465 FD_ZERO(&fds);
466 FD_SET(fd, &fds);
467 while ((r = select(fd + 1, &fds, NULL, NULL, NULL)) < 0
468 && errno == EINTR);
469 } else {
470 while ((r = read(fd, &c, 1)) < 0 && errno == EINTR);
471 }
472 close(fd);
473 if (r == 1) {
474 seeded = 1;
475 /* Create the shared memory indicator */
476 shm_id = shmget(OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID, 1,
477 IPC_CREAT | S_IRUSR | S_IRGRP | S_IROTH);
478 }
479 }
480 }
481 if (shm_id != -1) {
482 seeded = 1;
483 /*
484 * Map the shared memory to prevent its premature destruction.
485 * If this call fails, it isn't a big problem.
486 */
487 shm_addr = shmat(shm_id, NULL, SHM_RDONLY);
488 if (shm_addr != (void *)-1)
489 OPENSSL_atexit(&cleanup_shm);
490 }
491 }
492 return seeded;
493 }
494 # else /* defined __linux && DEVRANDOM_WAIT && OPENSSL_RAND_SEED_GETRANDOM */
wait_random_seeded(void)495 static int wait_random_seeded(void)
496 {
497 return 1;
498 }
499 # endif
500
501 /*
502 * Verify that the file descriptor associated with the random source is
503 * still valid. The rationale for doing this is the fact that it is not
504 * uncommon for daemons to close all open file handles when daemonizing.
505 * So the handle might have been closed or even reused for opening
506 * another file.
507 */
check_random_device(struct random_device * rd)508 static int check_random_device(struct random_device *rd)
509 {
510 struct stat st;
511
512 return rd->fd != -1
513 && fstat(rd->fd, &st) != -1
514 && rd->dev == st.st_dev
515 && rd->ino == st.st_ino
516 && ((rd->mode ^ st.st_mode) & ~(S_IRWXU | S_IRWXG | S_IRWXO)) == 0
517 && rd->rdev == st.st_rdev;
518 }
519
520 /*
521 * Open a random device if required and return its file descriptor or -1 on error
522 */
get_random_device(size_t n)523 static int get_random_device(size_t n)
524 {
525 struct stat st;
526 struct random_device *rd = &random_devices[n];
527
528 /* reuse existing file descriptor if it is (still) valid */
529 if (check_random_device(rd))
530 return rd->fd;
531
532 /* open the random device ... */
533 if ((rd->fd = open(random_device_paths[n], O_RDONLY)) == -1)
534 return rd->fd;
535
536 /* ... and cache its relevant stat(2) data */
537 if (fstat(rd->fd, &st) != -1) {
538 rd->dev = st.st_dev;
539 rd->ino = st.st_ino;
540 rd->mode = st.st_mode;
541 rd->rdev = st.st_rdev;
542 } else {
543 close(rd->fd);
544 rd->fd = -1;
545 }
546
547 return rd->fd;
548 }
549
550 /*
551 * Close a random device making sure it is a random device
552 */
close_random_device(size_t n)553 static void close_random_device(size_t n)
554 {
555 struct random_device *rd = &random_devices[n];
556
557 if (check_random_device(rd))
558 close(rd->fd);
559 rd->fd = -1;
560 }
561
ossl_rand_pool_init(void)562 int ossl_rand_pool_init(void)
563 {
564 size_t i;
565
566 for (i = 0; i < OSSL_NELEM(random_devices); i++)
567 random_devices[i].fd = -1;
568
569 return 1;
570 }
571
ossl_rand_pool_cleanup(void)572 void ossl_rand_pool_cleanup(void)
573 {
574 size_t i;
575
576 for (i = 0; i < OSSL_NELEM(random_devices); i++)
577 close_random_device(i);
578 }
579
ossl_rand_pool_keep_random_devices_open(int keep)580 void ossl_rand_pool_keep_random_devices_open(int keep)
581 {
582 if (!keep)
583 ossl_rand_pool_cleanup();
584
585 keep_random_devices_open = keep;
586 }
587
588 # else /* !defined(OPENSSL_RAND_SEED_DEVRANDOM) */
589
ossl_rand_pool_init(void)590 int ossl_rand_pool_init(void)
591 {
592 return 1;
593 }
594
ossl_rand_pool_cleanup(void)595 void ossl_rand_pool_cleanup(void)
596 {
597 }
598
ossl_rand_pool_keep_random_devices_open(int keep)599 void ossl_rand_pool_keep_random_devices_open(int keep)
600 {
601 }
602
603 # endif /* defined(OPENSSL_RAND_SEED_DEVRANDOM) */
604
605 /*
606 * Try the various seeding methods in turn, exit when successful.
607 *
608 * If more than one entropy source is available, is it
609 * preferable to stop as soon as enough entropy has been collected
610 * (as favored by @rsalz) or should one rather be defensive and add
611 * more entropy than requested and/or from different sources?
612 *
613 * Currently, the user can select multiple entropy sources in the
614 * configure step, yet in practice only the first available source
615 * will be used. A more flexible solution has been requested, but
616 * currently it is not clear how this can be achieved without
617 * overengineering the problem. There are many parameters which
618 * could be taken into account when selecting the order and amount
619 * of input from the different entropy sources (trust, quality,
620 * possibility of blocking).
621 */
ossl_pool_acquire_entropy(RAND_POOL * pool)622 size_t ossl_pool_acquire_entropy(RAND_POOL *pool)
623 {
624 # if defined(OPENSSL_RAND_SEED_NONE)
625 return ossl_rand_pool_entropy_available(pool);
626 # else
627 size_t entropy_available = 0;
628
629 (void)entropy_available; /* avoid compiler warning */
630
631 # if defined(OPENSSL_RAND_SEED_GETRANDOM)
632 {
633 size_t bytes_needed;
634 unsigned char *buffer;
635 ssize_t bytes;
636 /* Maximum allowed number of consecutive unsuccessful attempts */
637 int attempts = 3;
638
639 bytes_needed = ossl_rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
640 while (bytes_needed != 0 && attempts-- > 0) {
641 buffer = ossl_rand_pool_add_begin(pool, bytes_needed);
642 bytes = syscall_random(buffer, bytes_needed);
643 if (bytes > 0) {
644 ossl_rand_pool_add_end(pool, bytes, 8 * bytes);
645 bytes_needed -= bytes;
646 attempts = 3; /* reset counter after successful attempt */
647 } else if (bytes < 0 && errno != EINTR) {
648 break;
649 }
650 }
651 }
652 entropy_available = ossl_rand_pool_entropy_available(pool);
653 if (entropy_available > 0)
654 return entropy_available;
655 # endif
656
657 # if defined(OPENSSL_RAND_SEED_DEVRANDOM)
658 if (wait_random_seeded()) {
659 size_t bytes_needed;
660 unsigned char *buffer;
661 size_t i;
662
663 bytes_needed = ossl_rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
664 for (i = 0; bytes_needed > 0 && i < OSSL_NELEM(random_device_paths);
665 i++) {
666 ssize_t bytes = 0;
667 /* Maximum number of consecutive unsuccessful attempts */
668 int attempts = 3;
669 const int fd = get_random_device(i);
670
671 if (fd == -1)
672 continue;
673
674 while (bytes_needed != 0 && attempts-- > 0) {
675 buffer = ossl_rand_pool_add_begin(pool, bytes_needed);
676 bytes = read(fd, buffer, bytes_needed);
677
678 if (bytes > 0) {
679 ossl_rand_pool_add_end(pool, bytes, 8 * bytes);
680 bytes_needed -= bytes;
681 attempts = 3; /* reset counter on successful attempt */
682 } else if (bytes < 0 && errno != EINTR) {
683 break;
684 }
685 }
686 if (bytes < 0 || !keep_random_devices_open)
687 close_random_device(i);
688
689 bytes_needed = ossl_rand_pool_bytes_needed(pool, 1);
690 }
691 entropy_available = ossl_rand_pool_entropy_available(pool);
692 if (entropy_available > 0)
693 return entropy_available;
694 }
695 # endif
696
697 # if defined(OPENSSL_RAND_SEED_RDTSC)
698 entropy_available = ossl_prov_acquire_entropy_from_tsc(pool);
699 if (entropy_available > 0)
700 return entropy_available;
701 # endif
702
703 # if defined(OPENSSL_RAND_SEED_RDCPU)
704 entropy_available = ossl_prov_acquire_entropy_from_cpu(pool);
705 if (entropy_available > 0)
706 return entropy_available;
707 # endif
708
709 # if defined(OPENSSL_RAND_SEED_EGD)
710 {
711 static const char *paths[] = { DEVRANDOM_EGD, NULL };
712 size_t bytes_needed;
713 unsigned char *buffer;
714 int i;
715
716 bytes_needed = ossl_rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
717 for (i = 0; bytes_needed > 0 && paths[i] != NULL; i++) {
718 size_t bytes = 0;
719 int num;
720
721 buffer = ossl_rand_pool_add_begin(pool, bytes_needed);
722 num = RAND_query_egd_bytes(paths[i],
723 buffer, (int)bytes_needed);
724 if (num == (int)bytes_needed)
725 bytes = bytes_needed;
726
727 ossl_rand_pool_add_end(pool, bytes, 8 * bytes);
728 bytes_needed = ossl_rand_pool_bytes_needed(pool, 1);
729 }
730 entropy_available = ossl_rand_pool_entropy_available(pool);
731 if (entropy_available > 0)
732 return entropy_available;
733 }
734 # endif
735
736 return ossl_rand_pool_entropy_available(pool);
737 # endif
738 }
739 # endif
740 #endif
741
742 #if (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS)) \
743 || defined(__DJGPP__)
ossl_pool_add_nonce_data(RAND_POOL * pool)744 int ossl_pool_add_nonce_data(RAND_POOL *pool)
745 {
746 struct {
747 pid_t pid;
748 CRYPTO_THREAD_ID tid;
749 uint64_t time;
750 } data;
751
752 /* Erase the entire structure including any padding */
753 memset(&data, 0, sizeof(data));
754
755 /*
756 * Add process id, thread id, and a high resolution timestamp to
757 * ensure that the nonce is unique with high probability for
758 * different process instances.
759 */
760 data.pid = getpid();
761 data.tid = CRYPTO_THREAD_get_current_id();
762 data.time = get_time_stamp();
763
764 return ossl_rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0);
765 }
766
767 /*
768 * Get the current time with the highest possible resolution
769 *
770 * The time stamp is added to the nonce, so it is optimized for not repeating.
771 * The current time is ideal for this purpose, provided the computer's clock
772 * is synchronized.
773 */
get_time_stamp(void)774 static uint64_t get_time_stamp(void)
775 {
776 # if defined(OSSL_POSIX_TIMER_OKAY)
777 {
778 struct timespec ts;
779
780 if (clock_gettime(CLOCK_REALTIME, &ts) == 0)
781 return TWO32TO64(ts.tv_sec, ts.tv_nsec);
782 }
783 # endif
784 # if defined(__unix__) \
785 || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
786 {
787 struct timeval tv;
788
789 if (gettimeofday(&tv, NULL) == 0)
790 return TWO32TO64(tv.tv_sec, tv.tv_usec);
791 }
792 # endif
793 return time(NULL);
794 }
795
796 #endif /* (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS))
797 || defined(__DJGPP__) */
798
