summaryrefslogtreecommitdiff
path: root/src/lib/libcrypto/arc4random/getentropy_linux.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/lib/libcrypto/arc4random/getentropy_linux.c')
-rw-r--r--src/lib/libcrypto/arc4random/getentropy_linux.c548
1 files changed, 0 insertions, 548 deletions
diff --git a/src/lib/libcrypto/arc4random/getentropy_linux.c b/src/lib/libcrypto/arc4random/getentropy_linux.c
deleted file mode 100644
index 37e03ed590..0000000000
--- a/src/lib/libcrypto/arc4random/getentropy_linux.c
+++ /dev/null
@@ -1,548 +0,0 @@
1/* $OpenBSD: getentropy_linux.c,v 1.36 2014/10/11 16:44:05 bcook Exp $ */
2
3/*
4 * Copyright (c) 2014 Theo de Raadt <deraadt@openbsd.org>
5 * Copyright (c) 2014 Bob Beck <beck@obtuse.com>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 *
19 * Emulation of getentropy(2) as documented at:
20 * http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man2/getentropy.2
21 */
22
23#define _POSIX_C_SOURCE 199309L
24#define _GNU_SOURCE 1
25#include <sys/types.h>
26#include <sys/param.h>
27#include <sys/ioctl.h>
28#include <sys/resource.h>
29#include <sys/syscall.h>
30#ifdef HAVE_SYS_SYSCTL_H
31#include <sys/sysctl.h>
32#endif
33#include <sys/statvfs.h>
34#include <sys/socket.h>
35#include <sys/mount.h>
36#include <sys/mman.h>
37#include <sys/stat.h>
38#include <sys/time.h>
39#include <stdlib.h>
40#include <stdint.h>
41#include <stdio.h>
42#include <link.h>
43#include <termios.h>
44#include <fcntl.h>
45#include <signal.h>
46#include <string.h>
47#include <errno.h>
48#include <unistd.h>
49#include <time.h>
50#include <openssl/sha.h>
51
52#include <linux/types.h>
53#include <linux/random.h>
54#include <linux/sysctl.h>
55#ifdef HAVE_GETAUXVAL
56#include <sys/auxv.h>
57#endif
58#include <sys/vfs.h>
59
60#define REPEAT 5
61#define min(a, b) (((a) < (b)) ? (a) : (b))
62
63#define HX(a, b) \
64 do { \
65 if ((a)) \
66 HD(errno); \
67 else \
68 HD(b); \
69 } while (0)
70
71#define HR(x, l) (SHA512_Update(&ctx, (char *)(x), (l)))
72#define HD(x) (SHA512_Update(&ctx, (char *)&(x), sizeof (x)))
73#define HF(x) (SHA512_Update(&ctx, (char *)&(x), sizeof (void*)))
74
75int getentropy(void *buf, size_t len);
76
77static int gotdata(char *buf, size_t len);
78#ifdef SYS_getrandom
79static int getentropy_getrandom(void *buf, size_t len);
80#endif
81static int getentropy_urandom(void *buf, size_t len);
82#ifdef SYS__sysctl
83static int getentropy_sysctl(void *buf, size_t len);
84#endif
85static int getentropy_fallback(void *buf, size_t len);
86static int getentropy_phdr(struct dl_phdr_info *info, size_t size, void *data);
87
88int
89getentropy(void *buf, size_t len)
90{
91 int ret = -1;
92
93 if (len > 256) {
94 errno = EIO;
95 return -1;
96 }
97
98#ifdef SYS_getrandom
99 /*
100 * Try descriptor-less getrandom()
101 */
102 ret = getentropy_getrandom(buf, len);
103 if (ret != -1)
104 return (ret);
105 if (errno != ENOSYS)
106 return (-1);
107#endif
108
109 /*
110 * Try to get entropy with /dev/urandom
111 *
112 * This can fail if the process is inside a chroot or if file
113 * descriptors are exhausted.
114 */
115 ret = getentropy_urandom(buf, len);
116 if (ret != -1)
117 return (ret);
118
119#ifdef SYS__sysctl
120 /*
121 * Try to use sysctl CTL_KERN, KERN_RANDOM, RANDOM_UUID.
122 * sysctl is a failsafe API, so it guarantees a result. This
123 * should work inside a chroot, or when file descriptors are
124 * exhuasted.
125 *
126 * However this can fail if the Linux kernel removes support
127 * for sysctl. Starting in 2007, there have been efforts to
128 * deprecate the sysctl API/ABI, and push callers towards use
129 * of the chroot-unavailable fd-using /proc mechanism --
130 * essentially the same problems as /dev/urandom.
131 *
132 * Numerous setbacks have been encountered in their deprecation
133 * schedule, so as of June 2014 the kernel ABI still exists on
134 * most Linux architectures. The sysctl() stub in libc is missing
135 * on some systems. There are also reports that some kernels
136 * spew messages to the console.
137 */
138 ret = getentropy_sysctl(buf, len);
139 if (ret != -1)
140 return (ret);
141#endif /* SYS__sysctl */
142
143 /*
144 * Entropy collection via /dev/urandom and sysctl have failed.
145 *
146 * No other API exists for collecting entropy. See the large
147 * comment block above.
148 *
149 * We have very few options:
150 * - Even syslog_r is unsafe to call at this low level, so
151 * there is no way to alert the user or program.
152 * - Cannot call abort() because some systems have unsafe
153 * corefiles.
154 * - Could raise(SIGKILL) resulting in silent program termination.
155 * - Return EIO, to hint that arc4random's stir function
156 * should raise(SIGKILL)
157 * - Do the best under the circumstances....
158 *
159 * This code path exists to bring light to the issue that Linux
160 * does not provide a failsafe API for entropy collection.
161 *
162 * We hope this demonstrates that Linux should either retain their
163 * sysctl ABI, or consider providing a new failsafe API which
164 * works in a chroot or when file descriptors are exhausted.
165 */
166#undef FAIL_INSTEAD_OF_TRYING_FALLBACK
167#ifdef FAIL_INSTEAD_OF_TRYING_FALLBACK
168 raise(SIGKILL);
169#endif
170 ret = getentropy_fallback(buf, len);
171 if (ret != -1)
172 return (ret);
173
174 errno = EIO;
175 return (ret);
176}
177
178/*
179 * Basic sanity checking; wish we could do better.
180 */
181static int
182gotdata(char *buf, size_t len)
183{
184 char any_set = 0;
185 size_t i;
186
187 for (i = 0; i < len; ++i)
188 any_set |= buf[i];
189 if (any_set == 0)
190 return -1;
191 return 0;
192}
193
194#ifdef SYS_getrandom
195static int
196getentropy_getrandom(void *buf, size_t len)
197{
198 int pre_errno = errno;
199 int ret;
200 if (len > 256)
201 return (-1);
202 do {
203 ret = syscall(SYS_getrandom, buf, len, 0);
204 } while (ret == -1 && errno == EINTR);
205
206 if (ret != len)
207 return (-1);
208 errno = pre_errno;
209 return (0);
210}
211#endif
212
213static int
214getentropy_urandom(void *buf, size_t len)
215{
216 struct stat st;
217 size_t i;
218 int fd, cnt, flags;
219 int save_errno = errno;
220
221start:
222
223 flags = O_RDONLY;
224#ifdef O_NOFOLLOW
225 flags |= O_NOFOLLOW;
226#endif
227#ifdef O_CLOEXEC
228 flags |= O_CLOEXEC;
229#endif
230 fd = open("/dev/urandom", flags, 0);
231 if (fd == -1) {
232 if (errno == EINTR)
233 goto start;
234 goto nodevrandom;
235 }
236#ifndef O_CLOEXEC
237 fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
238#endif
239
240 /* Lightly verify that the device node looks sane */
241 if (fstat(fd, &st) == -1 || !S_ISCHR(st.st_mode)) {
242 close(fd);
243 goto nodevrandom;
244 }
245 if (ioctl(fd, RNDGETENTCNT, &cnt) == -1) {
246 close(fd);
247 goto nodevrandom;
248 }
249 for (i = 0; i < len; ) {
250 size_t wanted = len - i;
251 ssize_t ret = read(fd, (char *)buf + i, wanted);
252
253 if (ret == -1) {
254 if (errno == EAGAIN || errno == EINTR)
255 continue;
256 close(fd);
257 goto nodevrandom;
258 }
259 i += ret;
260 }
261 close(fd);
262 if (gotdata(buf, len) == 0) {
263 errno = save_errno;
264 return 0; /* satisfied */
265 }
266nodevrandom:
267 errno = EIO;
268 return -1;
269}
270
271#ifdef SYS__sysctl
272static int
273getentropy_sysctl(void *buf, size_t len)
274{
275 static int mib[] = { CTL_KERN, KERN_RANDOM, RANDOM_UUID };
276 size_t i;
277 int save_errno = errno;
278
279 for (i = 0; i < len; ) {
280 size_t chunk = min(len - i, 16);
281
282 /* SYS__sysctl because some systems already removed sysctl() */
283 struct __sysctl_args args = {
284 .name = mib,
285 .nlen = 3,
286 .oldval = (char *)buf + i,
287 .oldlenp = &chunk,
288 };
289 if (syscall(SYS__sysctl, &args) != 0)
290 goto sysctlfailed;
291 i += chunk;
292 }
293 if (gotdata(buf, len) == 0) {
294 errno = save_errno;
295 return (0); /* satisfied */
296 }
297sysctlfailed:
298 errno = EIO;
299 return -1;
300}
301#endif /* SYS__sysctl */
302
303static int cl[] = {
304 CLOCK_REALTIME,
305#ifdef CLOCK_MONOTONIC
306 CLOCK_MONOTONIC,
307#endif
308#ifdef CLOCK_MONOTONIC_RAW
309 CLOCK_MONOTONIC_RAW,
310#endif
311#ifdef CLOCK_TAI
312 CLOCK_TAI,
313#endif
314#ifdef CLOCK_VIRTUAL
315 CLOCK_VIRTUAL,
316#endif
317#ifdef CLOCK_UPTIME
318 CLOCK_UPTIME,
319#endif
320#ifdef CLOCK_PROCESS_CPUTIME_ID
321 CLOCK_PROCESS_CPUTIME_ID,
322#endif
323#ifdef CLOCK_THREAD_CPUTIME_ID
324 CLOCK_THREAD_CPUTIME_ID,
325#endif
326};
327
328static int
329getentropy_phdr(struct dl_phdr_info *info, size_t size, void *data)
330{
331 SHA512_CTX *ctx = data;
332
333 SHA512_Update(ctx, &info->dlpi_addr, sizeof (info->dlpi_addr));
334 return 0;
335}
336
337static int
338getentropy_fallback(void *buf, size_t len)
339{
340 uint8_t results[SHA512_DIGEST_LENGTH];
341 int save_errno = errno, e, pgs = getpagesize(), faster = 0, repeat;
342 static int cnt;
343 struct timespec ts;
344 struct timeval tv;
345 struct rusage ru;
346 sigset_t sigset;
347 struct stat st;
348 SHA512_CTX ctx;
349 static pid_t lastpid;
350 pid_t pid;
351 size_t i, ii, m;
352 char *p;
353
354 pid = getpid();
355 if (lastpid == pid) {
356 faster = 1;
357 repeat = 2;
358 } else {
359 faster = 0;
360 lastpid = pid;
361 repeat = REPEAT;
362 }
363 for (i = 0; i < len; ) {
364 int j;
365 SHA512_Init(&ctx);
366 for (j = 0; j < repeat; j++) {
367 HX((e = gettimeofday(&tv, NULL)) == -1, tv);
368 if (e != -1) {
369 cnt += (int)tv.tv_sec;
370 cnt += (int)tv.tv_usec;
371 }
372
373 dl_iterate_phdr(getentropy_phdr, &ctx);
374
375 for (ii = 0; ii < sizeof(cl)/sizeof(cl[0]); ii++)
376 HX(clock_gettime(cl[ii], &ts) == -1, ts);
377
378 HX((pid = getpid()) == -1, pid);
379 HX((pid = getsid(pid)) == -1, pid);
380 HX((pid = getppid()) == -1, pid);
381 HX((pid = getpgid(0)) == -1, pid);
382 HX((e = getpriority(0, 0)) == -1, e);
383
384 if (!faster) {
385 ts.tv_sec = 0;
386 ts.tv_nsec = 1;
387 (void) nanosleep(&ts, NULL);
388 }
389
390 HX(sigpending(&sigset) == -1, sigset);
391 HX(sigprocmask(SIG_BLOCK, NULL, &sigset) == -1,
392 sigset);
393
394 HF(getentropy); /* an addr in this library */
395 HF(printf); /* an addr in libc */
396 p = (char *)&p;
397 HD(p); /* an addr on stack */
398 p = (char *)&errno;
399 HD(p); /* the addr of errno */
400
401 if (i == 0) {
402 struct sockaddr_storage ss;
403 struct statvfs stvfs;
404 struct termios tios;
405 struct statfs stfs;
406 socklen_t ssl;
407 off_t off;
408
409 /*
410 * Prime-sized mappings encourage fragmentation;
411 * thus exposing some address entropy.
412 */
413 struct mm {
414 size_t npg;
415 void *p;
416 } mm[] = {
417 { 17, MAP_FAILED }, { 3, MAP_FAILED },
418 { 11, MAP_FAILED }, { 2, MAP_FAILED },
419 { 5, MAP_FAILED }, { 3, MAP_FAILED },
420 { 7, MAP_FAILED }, { 1, MAP_FAILED },
421 { 57, MAP_FAILED }, { 3, MAP_FAILED },
422 { 131, MAP_FAILED }, { 1, MAP_FAILED },
423 };
424
425 for (m = 0; m < sizeof mm/sizeof(mm[0]); m++) {
426 HX(mm[m].p = mmap(NULL,
427 mm[m].npg * pgs,
428 PROT_READ|PROT_WRITE,
429 MAP_PRIVATE|MAP_ANON, -1,
430 (off_t)0), mm[m].p);
431 if (mm[m].p != MAP_FAILED) {
432 size_t mo;
433
434 /* Touch some memory... */
435 p = mm[m].p;
436 mo = cnt %
437 (mm[m].npg * pgs - 1);
438 p[mo] = 1;
439 cnt += (int)((long)(mm[m].p)
440 / pgs);
441 }
442
443 /* Check cnts and times... */
444 for (ii = 0; ii < sizeof(cl)/sizeof(cl[0]);
445 ii++) {
446 HX((e = clock_gettime(cl[ii],
447 &ts)) == -1, ts);
448 if (e != -1)
449 cnt += (int)ts.tv_nsec;
450 }
451
452 HX((e = getrusage(RUSAGE_SELF,
453 &ru)) == -1, ru);
454 if (e != -1) {
455 cnt += (int)ru.ru_utime.tv_sec;
456 cnt += (int)ru.ru_utime.tv_usec;
457 }
458 }
459
460 for (m = 0; m < sizeof mm/sizeof(mm[0]); m++) {
461 if (mm[m].p != MAP_FAILED)
462 munmap(mm[m].p, mm[m].npg * pgs);
463 mm[m].p = MAP_FAILED;
464 }
465
466 HX(stat(".", &st) == -1, st);
467 HX(statvfs(".", &stvfs) == -1, stvfs);
468 HX(statfs(".", &stfs) == -1, stfs);
469
470 HX(stat("/", &st) == -1, st);
471 HX(statvfs("/", &stvfs) == -1, stvfs);
472 HX(statfs("/", &stfs) == -1, stfs);
473
474 HX((e = fstat(0, &st)) == -1, st);
475 if (e == -1) {
476 if (S_ISREG(st.st_mode) ||
477 S_ISFIFO(st.st_mode) ||
478 S_ISSOCK(st.st_mode)) {
479 HX(fstatvfs(0, &stvfs) == -1,
480 stvfs);
481 HX(fstatfs(0, &stfs) == -1,
482 stfs);
483 HX((off = lseek(0, (off_t)0,
484 SEEK_CUR)) < 0, off);
485 }
486 if (S_ISCHR(st.st_mode)) {
487 HX(tcgetattr(0, &tios) == -1,
488 tios);
489 } else if (S_ISSOCK(st.st_mode)) {
490 memset(&ss, 0, sizeof ss);
491 ssl = sizeof(ss);
492 HX(getpeername(0,
493 (void *)&ss, &ssl) == -1,
494 ss);
495 }
496 }
497
498 HX((e = getrusage(RUSAGE_CHILDREN,
499 &ru)) == -1, ru);
500 if (e != -1) {
501 cnt += (int)ru.ru_utime.tv_sec;
502 cnt += (int)ru.ru_utime.tv_usec;
503 }
504 } else {
505 /* Subsequent hashes absorb previous result */
506 HD(results);
507 }
508
509 HX((e = gettimeofday(&tv, NULL)) == -1, tv);
510 if (e != -1) {
511 cnt += (int)tv.tv_sec;
512 cnt += (int)tv.tv_usec;
513 }
514
515 HD(cnt);
516 }
517#ifdef HAVE_GETAUXVAL
518#ifdef AT_RANDOM
519 /* Not as random as you think but we take what we are given */
520 p = (char *) getauxval(AT_RANDOM);
521 if (p)
522 HR(p, 16);
523#endif
524#ifdef AT_SYSINFO_EHDR
525 p = (char *) getauxval(AT_SYSINFO_EHDR);
526 if (p)
527 HR(p, pgs);
528#endif
529#ifdef AT_BASE
530 p = (char *) getauxval(AT_BASE);
531 if (p)
532 HD(p);
533#endif
534#endif
535
536 SHA512_Final(results, &ctx);
537 memcpy((char *)buf + i, results, min(sizeof(results), len - i));
538 i += min(sizeof(results), len - i);
539 }
540 explicit_bzero(&ctx, sizeof ctx);
541 explicit_bzero(results, sizeof results);
542 if (gotdata(buf, len) == 0) {
543 errno = save_errno;
544 return 0; /* satisfied */
545 }
546 errno = EIO;
547 return -1;
548}
generated by cgit v1.2.3-55-g6feb (git 2.39.1) at 2025-08-15 01:59:57 +0000