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Diffstat (limited to 'src/lib/libcrypto/crypto/getentropy_linux.c')
-rw-r--r--src/lib/libcrypto/crypto/getentropy_linux.c547
1 files changed, 0 insertions, 547 deletions
diff --git a/src/lib/libcrypto/crypto/getentropy_linux.c b/src/lib/libcrypto/crypto/getentropy_linux.c
deleted file mode 100644
index ac97658efe..0000000000
--- a/src/lib/libcrypto/crypto/getentropy_linux.c
+++ /dev/null
@@ -1,547 +0,0 @@
1/* $OpenBSD: getentropy_linux.c,v 1.43 2016/08/07 03:27:21 tb 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://man.openbsd.org/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 SYS__sysctl
31#include <linux/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#ifdef HAVE_GETAUXVAL
55#include <sys/auxv.h>
56#endif
57#include <sys/vfs.h>
58
59#define REPEAT 5
60#define min(a, b) (((a) < (b)) ? (a) : (b))
61
62#define HX(a, b) \
63 do { \
64 if ((a)) \
65 HD(errno); \
66 else \
67 HD(b); \
68 } while (0)
69
70#define HR(x, l) (SHA512_Update(&ctx, (char *)(x), (l)))
71#define HD(x) (SHA512_Update(&ctx, (char *)&(x), sizeof (x)))
72#define HF(x) (SHA512_Update(&ctx, (char *)&(x), sizeof (void*)))
73
74int getentropy(void *buf, size_t len);
75
76static int gotdata(char *buf, size_t len);
77#ifdef SYS_getrandom
78static int getentropy_getrandom(void *buf, size_t len);
79#endif
80static int getentropy_urandom(void *buf, size_t len);
81#ifdef SYS__sysctl
82static int getentropy_sysctl(void *buf, size_t len);
83#endif
84static int getentropy_fallback(void *buf, size_t len);
85static int getentropy_phdr(struct dl_phdr_info *info, size_t size, void *data);
86
87int
88getentropy(void *buf, size_t len)
89{
90 int ret = -1;
91
92 if (len > 256) {
93 errno = EIO;
94 return (-1);
95 }
96
97#ifdef SYS_getrandom
98 /*
99 * Try descriptor-less getrandom()
100 */
101 ret = getentropy_getrandom(buf, len);
102 if (ret != -1)
103 return (ret);
104 if (errno != ENOSYS)
105 return (-1);
106#endif
107
108 /*
109 * Try to get entropy with /dev/urandom
110 *
111 * This can fail if the process is inside a chroot or if file
112 * descriptors are exhausted.
113 */
114 ret = getentropy_urandom(buf, len);
115 if (ret != -1)
116 return (ret);
117
118#ifdef SYS__sysctl
119 /*
120 * Try to use sysctl CTL_KERN, KERN_RANDOM, RANDOM_UUID.
121 * sysctl is a failsafe API, so it guarantees a result. This
122 * should work inside a chroot, or when file descriptors are
123 * exhausted.
124 *
125 * However this can fail if the Linux kernel removes support
126 * for sysctl. Starting in 2007, there have been efforts to
127 * deprecate the sysctl API/ABI, and push callers towards use
128 * of the chroot-unavailable fd-using /proc mechanism --
129 * essentially the same problems as /dev/urandom.
130 *
131 * Numerous setbacks have been encountered in their deprecation
132 * schedule, so as of June 2014 the kernel ABI still exists on
133 * most Linux architectures. The sysctl() stub in libc is missing
134 * on some systems. There are also reports that some kernels
135 * spew messages to the console.
136 */
137 ret = getentropy_sysctl(buf, len);
138 if (ret != -1)
139 return (ret);
140#endif /* SYS__sysctl */
141
142 /*
143 * Entropy collection via /dev/urandom and sysctl have failed.
144 *
145 * No other API exists for collecting entropy. See the large
146 * comment block above.
147 *
148 * We have very few options:
149 * - Even syslog_r is unsafe to call at this low level, so
150 * there is no way to alert the user or program.
151 * - Cannot call abort() because some systems have unsafe
152 * corefiles.
153 * - Could raise(SIGKILL) resulting in silent program termination.
154 * - Return EIO, to hint that arc4random's stir function
155 * should raise(SIGKILL)
156 * - Do the best under the circumstances....
157 *
158 * This code path exists to bring light to the issue that Linux
159 * does not provide a failsafe API for entropy collection.
160 *
161 * We hope this demonstrates that Linux should either retain their
162 * sysctl ABI, or consider providing a new failsafe API which
163 * works in a chroot or when file descriptors are exhausted.
164 */
165#undef FAIL_INSTEAD_OF_TRYING_FALLBACK
166#ifdef FAIL_INSTEAD_OF_TRYING_FALLBACK
167 raise(SIGKILL);
168#endif
169 ret = getentropy_fallback(buf, len);
170 if (ret != -1)
171 return (ret);
172
173 errno = EIO;
174 return (ret);
175}
176
177/*
178 * Basic sanity checking; wish we could do better.
179 */
180static int
181gotdata(char *buf, size_t len)
182{
183 char any_set = 0;
184 size_t i;
185
186 for (i = 0; i < len; ++i)
187 any_set |= buf[i];
188 if (any_set == 0)
189 return (-1);
190 return (0);
191}
192
193#ifdef SYS_getrandom
194static int
195getentropy_getrandom(void *buf, size_t len)
196{
197 int pre_errno = errno;
198 int ret;
199 if (len > 256)
200 return (-1);
201 do {
202 ret = syscall(SYS_getrandom, buf, len, 0);
203 } while (ret == -1 && errno == EINTR);
204
205 if (ret != len)
206 return (-1);
207 errno = pre_errno;
208 return (0);
209}
210#endif
211
212static int
213getentropy_urandom(void *buf, size_t len)
214{
215 struct stat st;
216 size_t i;
217 int fd, cnt, flags;
218 int save_errno = errno;
219
220start:
221
222 flags = O_RDONLY;
223#ifdef O_NOFOLLOW
224 flags |= O_NOFOLLOW;
225#endif
226#ifdef O_CLOEXEC
227 flags |= O_CLOEXEC;
228#endif
229 fd = open("/dev/urandom", flags, 0);
230 if (fd == -1) {
231 if (errno == EINTR)
232 goto start;
233 goto nodevrandom;
234 }
235#ifndef O_CLOEXEC
236 fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
237#endif
238
239 /* Lightly verify that the device node looks sane */
240 if (fstat(fd, &st) == -1 || !S_ISCHR(st.st_mode)) {
241 close(fd);
242 goto nodevrandom;
243 }
244 if (ioctl(fd, RNDGETENTCNT, &cnt) == -1) {
245 close(fd);
246 goto nodevrandom;
247 }
248 for (i = 0; i < len; ) {
249 size_t wanted = len - i;
250 ssize_t ret = read(fd, (char *)buf + i, wanted);
251
252 if (ret == -1) {
253 if (errno == EAGAIN || errno == EINTR)
254 continue;
255 close(fd);
256 goto nodevrandom;
257 }
258 i += ret;
259 }
260 close(fd);
261 if (gotdata(buf, len) == 0) {
262 errno = save_errno;
263 return (0); /* satisfied */
264 }
265nodevrandom:
266 errno = EIO;
267 return (-1);
268}
269
270#ifdef SYS__sysctl
271static int
272getentropy_sysctl(void *buf, size_t len)
273{
274 static int mib[] = { CTL_KERN, KERN_RANDOM, RANDOM_UUID };
275 size_t i;
276 int save_errno = errno;
277
278 for (i = 0; i < len; ) {
279 size_t chunk = min(len - i, 16);
280
281 /* SYS__sysctl because some systems already removed sysctl() */
282 struct __sysctl_args args = {
283 .name = mib,
284 .nlen = 3,
285 .oldval = (char *)buf + i,
286 .oldlenp = &chunk,
287 };
288 if (syscall(SYS__sysctl, &args) != 0)
289 goto sysctlfailed;
290 i += chunk;
291 }
292 if (gotdata(buf, len) == 0) {
293 errno = save_errno;
294 return (0); /* satisfied */
295 }
296sysctlfailed:
297 errno = EIO;
298 return (-1);
299}
300#endif /* SYS__sysctl */
301
302static const int cl[] = {
303 CLOCK_REALTIME,
304#ifdef CLOCK_MONOTONIC
305 CLOCK_MONOTONIC,
306#endif
307#ifdef CLOCK_MONOTONIC_RAW
308 CLOCK_MONOTONIC_RAW,
309#endif
310#ifdef CLOCK_TAI
311 CLOCK_TAI,
312#endif
313#ifdef CLOCK_VIRTUAL
314 CLOCK_VIRTUAL,
315#endif
316#ifdef CLOCK_UPTIME
317 CLOCK_UPTIME,
318#endif
319#ifdef CLOCK_PROCESS_CPUTIME_ID
320 CLOCK_PROCESS_CPUTIME_ID,
321#endif
322#ifdef CLOCK_THREAD_CPUTIME_ID
323 CLOCK_THREAD_CPUTIME_ID,
324#endif
325};
326
327static int
328getentropy_phdr(struct dl_phdr_info *info, size_t size, void *data)
329{
330 SHA512_CTX *ctx = data;
331
332 SHA512_Update(ctx, &info->dlpi_addr, sizeof (info->dlpi_addr));
333 return (0);
334}
335
336static int
337getentropy_fallback(void *buf, size_t len)
338{
339 uint8_t results[SHA512_DIGEST_LENGTH];
340 int save_errno = errno, e, pgs = getpagesize(), faster = 0, repeat;
341 static int cnt;
342 struct timespec ts;
343 struct timeval tv;
344 struct rusage ru;
345 sigset_t sigset;
346 struct stat st;
347 SHA512_CTX ctx;
348 static pid_t lastpid;
349 pid_t pid;
350 size_t i, ii, m;
351 char *p;
352
353 pid = getpid();
354 if (lastpid == pid) {
355 faster = 1;
356 repeat = 2;
357 } else {
358 faster = 0;
359 lastpid = pid;
360 repeat = REPEAT;
361 }
362 for (i = 0; i < len; ) {
363 int j;
364 SHA512_Init(&ctx);
365 for (j = 0; j < repeat; j++) {
366 HX((e = gettimeofday(&tv, NULL)) == -1, tv);
367 if (e != -1) {
368 cnt += (int)tv.tv_sec;
369 cnt += (int)tv.tv_usec;
370 }
371
372 dl_iterate_phdr(getentropy_phdr, &ctx);
373
374 for (ii = 0; ii < sizeof(cl)/sizeof(cl[0]); ii++)
375 HX(clock_gettime(cl[ii], &ts) == -1, ts);
376
377 HX((pid = getpid()) == -1, pid);
378 HX((pid = getsid(pid)) == -1, pid);
379 HX((pid = getppid()) == -1, pid);
380 HX((pid = getpgid(0)) == -1, pid);
381 HX((e = getpriority(0, 0)) == -1, e);
382
383 if (!faster) {
384 ts.tv_sec = 0;
385 ts.tv_nsec = 1;
386 (void) nanosleep(&ts, NULL);
387 }
388
389 HX(sigpending(&sigset) == -1, sigset);
390 HX(sigprocmask(SIG_BLOCK, NULL, &sigset) == -1,
391 sigset);
392
393 HF(getentropy); /* an addr in this library */
394 HF(printf); /* an addr in libc */
395 p = (char *)&p;
396 HD(p); /* an addr on stack */
397 p = (char *)&errno;
398 HD(p); /* the addr of errno */
399
400 if (i == 0) {
401 struct sockaddr_storage ss;
402 struct statvfs stvfs;
403 struct termios tios;
404 struct statfs stfs;
405 socklen_t ssl;
406 off_t off;
407
408 /*
409 * Prime-sized mappings encourage fragmentation;
410 * thus exposing some address entropy.
411 */
412 struct mm {
413 size_t npg;
414 void *p;
415 } mm[] = {
416 { 17, MAP_FAILED }, { 3, MAP_FAILED },
417 { 11, MAP_FAILED }, { 2, MAP_FAILED },
418 { 5, MAP_FAILED }, { 3, MAP_FAILED },
419 { 7, MAP_FAILED }, { 1, MAP_FAILED },
420 { 57, MAP_FAILED }, { 3, MAP_FAILED },
421 { 131, MAP_FAILED }, { 1, MAP_FAILED },
422 };
423
424 for (m = 0; m < sizeof mm/sizeof(mm[0]); m++) {
425 HX(mm[m].p = mmap(NULL,
426 mm[m].npg * pgs,
427 PROT_READ|PROT_WRITE,
428 MAP_PRIVATE|MAP_ANON, -1,
429 (off_t)0), mm[m].p);
430 if (mm[m].p != MAP_FAILED) {
431 size_t mo;
432
433 /* Touch some memory... */
434 p = mm[m].p;
435 mo = cnt %
436 (mm[m].npg * pgs - 1);
437 p[mo] = 1;
438 cnt += (int)((long)(mm[m].p)
439 / pgs);
440 }
441
442 /* Check cnts and times... */
443 for (ii = 0; ii < sizeof(cl)/sizeof(cl[0]);
444 ii++) {
445 HX((e = clock_gettime(cl[ii],
446 &ts)) == -1, ts);
447 if (e != -1)
448 cnt += (int)ts.tv_nsec;
449 }
450
451 HX((e = getrusage(RUSAGE_SELF,
452 &ru)) == -1, ru);
453 if (e != -1) {
454 cnt += (int)ru.ru_utime.tv_sec;
455 cnt += (int)ru.ru_utime.tv_usec;
456 }
457 }
458
459 for (m = 0; m < sizeof mm/sizeof(mm[0]); m++) {
460 if (mm[m].p != MAP_FAILED)
461 munmap(mm[m].p, mm[m].npg * pgs);
462 mm[m].p = MAP_FAILED;
463 }
464
465 HX(stat(".", &st) == -1, st);
466 HX(statvfs(".", &stvfs) == -1, stvfs);
467 HX(statfs(".", &stfs) == -1, stfs);
468
469 HX(stat("/", &st) == -1, st);
470 HX(statvfs("/", &stvfs) == -1, stvfs);
471 HX(statfs("/", &stfs) == -1, stfs);
472
473 HX((e = fstat(0, &st)) == -1, st);
474 if (e == -1) {
475 if (S_ISREG(st.st_mode) ||
476 S_ISFIFO(st.st_mode) ||
477 S_ISSOCK(st.st_mode)) {
478 HX(fstatvfs(0, &stvfs) == -1,
479 stvfs);
480 HX(fstatfs(0, &stfs) == -1,
481 stfs);
482 HX((off = lseek(0, (off_t)0,
483 SEEK_CUR)) < 0, off);
484 }
485 if (S_ISCHR(st.st_mode)) {
486 HX(tcgetattr(0, &tios) == -1,
487 tios);
488 } else if (S_ISSOCK(st.st_mode)) {
489 memset(&ss, 0, sizeof ss);
490 ssl = sizeof(ss);
491 HX(getpeername(0,
492 (void *)&ss, &ssl) == -1,
493 ss);
494 }
495 }
496
497 HX((e = getrusage(RUSAGE_CHILDREN,
498 &ru)) == -1, ru);
499 if (e != -1) {
500 cnt += (int)ru.ru_utime.tv_sec;
501 cnt += (int)ru.ru_utime.tv_usec;
502 }
503 } else {
504 /* Subsequent hashes absorb previous result */
505 HD(results);
506 }
507
508 HX((e = gettimeofday(&tv, NULL)) == -1, tv);
509 if (e != -1) {
510 cnt += (int)tv.tv_sec;
511 cnt += (int)tv.tv_usec;
512 }
513
514 HD(cnt);
515 }
516#ifdef HAVE_GETAUXVAL
517#ifdef AT_RANDOM
518 /* Not as random as you think but we take what we are given */
519 p = (char *) getauxval(AT_RANDOM);
520 if (p)
521 HR(p, 16);
522#endif
523#ifdef AT_SYSINFO_EHDR
524 p = (char *) getauxval(AT_SYSINFO_EHDR);
525 if (p)
526 HR(p, pgs);
527#endif
528#ifdef AT_BASE
529 p = (char *) getauxval(AT_BASE);
530 if (p)
531 HD(p);
532#endif
533#endif
534
535 SHA512_Final(results, &ctx);
536 memcpy((char *)buf + i, results, min(sizeof(results), len - i));
537 i += min(sizeof(results), len - i);
538 }
539 explicit_bzero(&ctx, sizeof ctx);
540 explicit_bzero(results, sizeof results);
541 if (gotdata(buf, len) == 0) {
542 errno = save_errno;
543 return (0); /* satisfied */
544 }
545 errno = EIO;
546 return (-1);
547}
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