1 /* $OpenBSD: getentropy_solaris.c,v 1.3 2014/07/12 14:46:31 deraadt Exp $ */
4 * Copyright (c) 2014 Theo de Raadt <deraadt@openbsd.org>
5 * Copyright (c) 2014 Bob Beck <beck@obtuse.com>
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.
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.
21 #include <sys/types.h>
22 #include <sys/param.h>
23 #include <sys/ioctl.h>
24 #include <sys/resource.h>
25 #include <sys/syscall.h>
26 #include <sys/statvfs.h>
27 #include <sys/socket.h>
28 #include <sys/mount.h>
44 #ifdef HAVE_SYS_SHA2_H
46 #define SHA512_Init SHA512Init
47 #define SHA512_Update SHA512Update
48 #define SHA512_Final SHA512Final
50 #include "openssl/sha.h"
54 #include <sys/statfs.h>
55 #include <sys/loadavg.h>
58 #define min(a, b) (((a) < (b)) ? (a) : (b))
68 #define HR(x, l) (SHA512_Update(&ctx, (char *)(x), (l)))
69 #define HD(x) (SHA512_Update(&ctx, (char *)&(x), sizeof (x)))
70 #define HF(x) (SHA512_Update(&ctx, (char *)&(x), sizeof (void*)))
72 int getentropy(void *buf, size_t len);
74 #ifdef CAN_REFERENCE_MAIN
75 extern int main(int, char *argv[]);
77 static int gotdata(char *buf, size_t len);
78 static int getentropy_urandom(void *buf, size_t len, const char *path,
80 static int getentropy_fallback(void *buf, size_t len);
83 getentropy(void *buf, size_t len)
93 * Try to get entropy with /dev/urandom
95 * Solaris provides /dev/urandom as a symbolic link to
96 * /devices/pseudo/random@0:urandom which is provided by
97 * a devfs filesystem. Best practice is to use O_NOFOLLOW,
98 * so we must try the unpublished name directly.
100 * This can fail if the process is inside a chroot which lacks
101 * the devfs mount, or if file descriptors are exhausted.
103 ret = getentropy_urandom(buf, len,
104 "/devices/pseudo/random@0:urandom", 1);
109 * Unfortunately, chroot spaces on Solaris are sometimes setup
110 * with direct device node of the well-known /dev/urandom name
111 * (perhaps to avoid dragging all of devfs into the space).
113 * This can fail if the process is inside a chroot or if file
114 * descriptors are exhausted.
116 ret = getentropy_urandom(buf, len, "/dev/urandom", 0);
121 * Entropy collection via /dev/urandom has failed.
123 * No other API exists for collecting entropy, and we have
124 * no failsafe way to get it on Solaris that is not sensitive
125 * to resource exhaustion.
127 * We have very few options:
128 * - Even syslog_r is unsafe to call at this low level, so
129 * there is no way to alert the user or program.
130 * - Cannot call abort() because some systems have unsafe
132 * - Could raise(SIGKILL) resulting in silent program termination.
133 * - Return EIO, to hint that arc4random's stir function
134 * should raise(SIGKILL)
135 * - Do the best under the circumstances....
137 * This code path exists to bring light to the issue that Solaris
138 * does not provide a failsafe API for entropy collection.
140 * We hope this demonstrates that Solaris should consider
141 * providing a new failsafe API which works in a chroot or
142 * when file descriptors are exhausted.
144 #undef FAIL_INSTEAD_OF_TRYING_FALLBACK
145 #ifdef FAIL_INSTEAD_OF_TRYING_FALLBACK
148 ret = getentropy_fallback(buf, len);
157 * Basic sanity checking; wish we could do better.
160 gotdata(char *buf, size_t len)
165 for (i = 0; i < len; ++i)
173 getentropy_urandom(void *buf, size_t len, const char *path, int devfscheck)
178 int save_errno = errno;
189 fd = open(path, flags, 0);
196 fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
199 /* Lightly verify that the device node looks sane */
200 if (fstat(fd, &st) == -1 || !S_ISCHR(st.st_mode) ||
201 (devfscheck && (strcmp(st.st_fstype, "devfs") != 0))) {
205 for (i = 0; i < len; ) {
206 size_t wanted = len - i;
207 ssize_t ret = read(fd, (char*)buf + i, wanted);
210 if (errno == EAGAIN || errno == EINTR)
218 if (gotdata(buf, len) == 0) {
220 return 0; /* satisfied */
227 static const int cl[] = {
229 #ifdef CLOCK_MONOTONIC
232 #ifdef CLOCK_MONOTONIC_RAW
244 #ifdef CLOCK_PROCESS_CPUTIME_ID
245 CLOCK_PROCESS_CPUTIME_ID,
247 #ifdef CLOCK_THREAD_CPUTIME_ID
248 CLOCK_THREAD_CPUTIME_ID,
253 getentropy_fallback(void *buf, size_t len)
255 uint8_t results[SHA512_DIGEST_LENGTH];
256 int save_errno = errno, e, pgs = getpagesize(), faster = 0, repeat;
265 static pid_t lastpid;
271 if (lastpid == pid) {
279 for (i = 0; i < len; ) {
282 for (j = 0; j < repeat; j++) {
283 HX((e = gettimeofday(&tv, NULL)) == -1, tv);
285 cnt += (int)tv.tv_sec;
286 cnt += (int)tv.tv_usec;
289 for (ii = 0; ii < sizeof(cl)/sizeof(cl[0]); ii++)
290 HX(clock_gettime(cl[ii], &ts) == -1, ts);
292 HX((pid = getpid()) == -1, pid);
293 HX((pid = getsid(pid)) == -1, pid);
294 HX((pid = getppid()) == -1, pid);
295 HX((pid = getpgid(0)) == -1, pid);
296 HX((e = getpriority(0, 0)) == -1, e);
297 HX((getloadavg(loadavg, 3) == -1), loadavg);
302 (void) nanosleep(&ts, NULL);
305 HX(sigpending(&sigset) == -1, sigset);
306 HX(sigprocmask(SIG_BLOCK, NULL, &sigset) == -1,
309 #ifdef CAN_REFERENCE_MAIN
310 HF(main); /* an addr in program */
312 HF(getentropy); /* an addr in this library */
313 HF(printf); /* an addr in libc */
315 HD(p); /* an addr on stack */
317 HD(p); /* the addr of errno */
320 struct sockaddr_storage ss;
321 struct statvfs stvfs;
327 * Prime-sized mappings encourage fragmentation;
328 * thus exposing some address entropy.
334 { 17, MAP_FAILED }, { 3, MAP_FAILED },
335 { 11, MAP_FAILED }, { 2, MAP_FAILED },
336 { 5, MAP_FAILED }, { 3, MAP_FAILED },
337 { 7, MAP_FAILED }, { 1, MAP_FAILED },
338 { 57, MAP_FAILED }, { 3, MAP_FAILED },
339 { 131, MAP_FAILED }, { 1, MAP_FAILED },
342 for (m = 0; m < sizeof mm/sizeof(mm[0]); m++) {
343 HX(mm[m].p = mmap(NULL,
345 PROT_READ|PROT_WRITE,
346 MAP_PRIVATE|MAP_ANON, -1,
348 if (mm[m].p != MAP_FAILED) {
351 /* Touch some memory... */
354 (mm[m].npg * pgs - 1);
356 cnt += (int)((long)(mm[m].p)
360 /* Check cnts and times... */
361 for (ii = 0; ii < sizeof(cl)/sizeof(cl[0]);
363 HX((e = clock_gettime(cl[ii],
366 cnt += (int)ts.tv_nsec;
369 HX((e = getrusage(RUSAGE_SELF,
372 cnt += (int)ru.ru_utime.tv_sec;
373 cnt += (int)ru.ru_utime.tv_usec;
377 for (m = 0; m < sizeof mm/sizeof(mm[0]); m++) {
378 if (mm[m].p != MAP_FAILED)
379 munmap(mm[m].p, mm[m].npg * pgs);
380 mm[m].p = MAP_FAILED;
383 HX(stat(".", &st) == -1, st);
384 HX(statvfs(".", &stvfs) == -1, stvfs);
386 HX(stat("/", &st) == -1, st);
387 HX(statvfs("/", &stvfs) == -1, stvfs);
389 HX((e = fstat(0, &st)) == -1, st);
391 if (S_ISREG(st.st_mode) ||
392 S_ISFIFO(st.st_mode) ||
393 S_ISSOCK(st.st_mode)) {
394 HX(fstatvfs(0, &stvfs) == -1,
396 HX((off = lseek(0, (off_t)0,
397 SEEK_CUR)) < 0, off);
399 if (S_ISCHR(st.st_mode)) {
400 HX(tcgetattr(0, &tios) == -1,
402 } else if (S_ISSOCK(st.st_mode)) {
403 memset(&ss, 0, sizeof ss);
406 (void *)&ss, &ssl) == -1,
411 HX((e = getrusage(RUSAGE_CHILDREN,
414 cnt += (int)ru.ru_utime.tv_sec;
415 cnt += (int)ru.ru_utime.tv_usec;
418 /* Subsequent hashes absorb previous result */
422 HX((e = gettimeofday(&tv, NULL)) == -1, tv);
424 cnt += (int)tv.tv_sec;
425 cnt += (int)tv.tv_usec;
430 SHA512_Final(results, &ctx);
431 memcpy((char*)buf + i, results, min(sizeof(results), len - i));
432 i += min(sizeof(results), len - i);
434 memset(results, 0, sizeof results);
435 if (gotdata(buf, len) == 0) {
437 return 0; /* satisfied */