1 /* $OpenBSD: getentropy_hpux.c,v 1.7 2020/05/17 14:44:20 deraadt 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 #include <sys/types.h>
24 #include <sys/param.h>
25 #include <sys/ioctl.h>
26 #include <sys/resource.h>
27 #include <sys/syscall.h>
28 #include <sys/statvfs.h>
29 #include <sys/socket.h>
30 #include <sys/mount.h>
31 #include <sys/mman.h>
32 #include <sys/stat.h>
33 #include <sys/time.h>
34 #include <stdlib.h>
35 #include <stdint.h>
36 #include <stdio.h>
37 #include <termios.h>
38 #include <fcntl.h>
39 #include <signal.h>
40 #include <string.h>
41 #include <errno.h>
42 #include <unistd.h>
43 #include <time.h>
44 #include <openssl/sha.h>
45
46 #include <sys/vfs.h>
47
48 #include <sys/pstat.h>
49
50 #define REPEAT 5
51 #define MINIMUM(a, b) (((a) < (b)) ? (a) : (b))
52
53 #define HX(a, b) \
54 do { \
55 if ((a)) \
56 HD(errno); \
57 else \
58 HD(b); \
59 } while (0)
60
61 #define HR(x, l) (SHA512_Update(&ctx, (char *)(x), (l)))
62 #define HD(x) (SHA512_Update(&ctx, (char *)&(x), sizeof (x)))
63 #define HF(x) (SHA512_Update(&ctx, (char *)&(x), sizeof (void*)))
64
65 int getentropy(void *buf, size_t len);
66
67 static int getentropy_urandom(void *buf, size_t len, const char *path,
68 int devfscheck);
69 static int getentropy_fallback(void *buf, size_t len);
70
71 int
getentropy(void * buf,size_t len)72 getentropy(void *buf, size_t len)
73 {
74 int ret = -1;
75
76 if (len > 256) {
77 errno = EIO;
78 return (-1);
79 }
80
81 /*
82 * Try to get entropy with /dev/urandom
83 */
84 ret = getentropy_urandom(buf, len, "/dev/urandom", 0);
85 if (ret != -1)
86 return (ret);
87
88 /*
89 * Entropy collection via /dev/urandom has failed.
90 *
91 * No other API exists for collecting entropy, and we have
92 * no failsafe way to get it on hpux that is not sensitive
93 * to resource exhaustion.
94 *
95 * We have very few options:
96 * - Even syslog_r is unsafe to call at this low level, so
97 * there is no way to alert the user or program.
98 * - Cannot call abort() because some systems have unsafe
99 * corefiles.
100 * - Could raise(SIGKILL) resulting in silent program termination.
101 * - Return EIO, to hint that arc4random's stir function
102 * should raise(SIGKILL)
103 * - Do the best under the circumstances....
104 *
105 * This code path exists to bring light to the issue that hpux
106 * does not provide a failsafe API for entropy collection.
107 *
108 * We hope this demonstrates that hpux should consider
109 * providing a new failsafe API which works in a chroot or
110 * when file descriptors are exhausted.
111 */
112 #undef FAIL_INSTEAD_OF_TRYING_FALLBACK
113 #ifdef FAIL_INSTEAD_OF_TRYING_FALLBACK
114 raise(SIGKILL);
115 #endif
116 ret = getentropy_fallback(buf, len);
117 if (ret != -1)
118 return (ret);
119
120 errno = EIO;
121 return (ret);
122 }
123
124 static int
getentropy_urandom(void * buf,size_t len,const char * path,int devfscheck)125 getentropy_urandom(void *buf, size_t len, const char *path, int devfscheck)
126 {
127 struct stat st;
128 size_t i;
129 int fd, flags;
130 int save_errno = errno;
131
132 start:
133
134 flags = O_RDONLY;
135 #ifdef O_NOFOLLOW
136 flags |= O_NOFOLLOW;
137 #endif
138 #ifdef O_CLOEXEC
139 flags |= O_CLOEXEC;
140 #endif
141 fd = open(path, flags, 0);
142 if (fd == -1) {
143 if (errno == EINTR)
144 goto start;
145 goto nodevrandom;
146 }
147 #ifndef O_CLOEXEC
148 fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
149 #endif
150
151 /* Lightly verify that the device node looks sane */
152 if (fstat(fd, &st) == -1 || !S_ISCHR(st.st_mode)) {
153 close(fd);
154 goto nodevrandom;
155 }
156 for (i = 0; i < len; ) {
157 size_t wanted = len - i;
158 ssize_t ret = read(fd, (char *)buf + i, wanted);
159
160 if (ret == -1) {
161 if (errno == EAGAIN || errno == EINTR)
162 continue;
163 close(fd);
164 goto nodevrandom;
165 }
166 i += ret;
167 }
168 close(fd);
169 errno = save_errno;
170 return (0); /* satisfied */
171 nodevrandom:
172 errno = EIO;
173 return (-1);
174 }
175
176 static const int cl[] = {
177 CLOCK_REALTIME,
178 #ifdef CLOCK_MONOTONIC
179 CLOCK_MONOTONIC,
180 #endif
181 #ifdef CLOCK_MONOTONIC_RAW
182 CLOCK_MONOTONIC_RAW,
183 #endif
184 #ifdef CLOCK_TAI
185 CLOCK_TAI,
186 #endif
187 #ifdef CLOCK_VIRTUAL
188 CLOCK_VIRTUAL,
189 #endif
190 #ifdef CLOCK_UPTIME
191 CLOCK_UPTIME,
192 #endif
193 #ifdef CLOCK_PROCESS_CPUTIME_ID
194 CLOCK_PROCESS_CPUTIME_ID,
195 #endif
196 #ifdef CLOCK_THREAD_CPUTIME_ID
197 CLOCK_THREAD_CPUTIME_ID,
198 #endif
199 };
200
201 static int
getentropy_fallback(void * buf,size_t len)202 getentropy_fallback(void *buf, size_t len)
203 {
204 uint8_t results[SHA512_DIGEST_LENGTH];
205 int save_errno = errno, e, pgs = sysconf(_SC_PAGESIZE), faster = 0, repeat;
206 static int cnt;
207 struct timespec ts;
208 struct timeval tv;
209 struct pst_vminfo pvi;
210 struct pst_vm_status pvs;
211 struct pst_dynamic pdy;
212 struct rusage ru;
213 sigset_t sigset;
214 struct stat st;
215 SHA512_CTX ctx;
216 static pid_t lastpid;
217 pid_t pid;
218 size_t i, ii, m;
219 char *p;
220
221 pid = getpid();
222 if (lastpid == pid) {
223 faster = 1;
224 repeat = 2;
225 } else {
226 faster = 0;
227 lastpid = pid;
228 repeat = REPEAT;
229 }
230 for (i = 0; i < len; ) {
231 int j;
232 SHA512_Init(&ctx);
233 for (j = 0; j < repeat; j++) {
234 HX((e = gettimeofday(&tv, NULL)) == -1, tv);
235 if (e != -1) {
236 cnt += (int)tv.tv_sec;
237 cnt += (int)tv.tv_usec;
238 }
239
240 HX(pstat_getvminfo(&pvi, sizeof(pvi), 1, 0) != 1, pvi);
241 HX(pstat_getprocvm(&pvs, sizeof(pvs), 0, 0) != 1, pvs);
242
243 for (ii = 0; ii < sizeof(cl)/sizeof(cl[0]); ii++)
244 HX(clock_gettime(cl[ii], &ts) == -1, ts);
245
246 HX((pid = getpid()) == -1, pid);
247 HX((pid = getsid(pid)) == -1, pid);
248 HX((pid = getppid()) == -1, pid);
249 HX((pid = getpgid(0)) == -1, pid);
250 HX((e = getpriority(0, 0)) == -1, e);
251
252 if(pstat_getdynamic(&pdy, sizeof(pdy), 1, 0) != 1) {
253 HD(errno);
254 } else {
255 HD(pdy.psd_avg_1_min);
256 HD(pdy.psd_avg_5_min);
257 HD(pdy.psd_avg_15_min);
258 }
259
260 if (!faster) {
261 ts.tv_sec = 0;
262 ts.tv_nsec = 1;
263 (void) nanosleep(&ts, NULL);
264 }
265
266 HX(sigpending(&sigset) == -1, sigset);
267 HX(sigprocmask(SIG_BLOCK, NULL, &sigset) == -1,
268 sigset);
269
270 HF(getentropy); /* an addr in this library */
271 HF(printf); /* an addr in libc */
272 p = (char *)&p;
273 HD(p); /* an addr on stack */
274 p = (char *)&errno;
275 HD(p); /* the addr of errno */
276
277 if (i == 0) {
278 struct sockaddr_storage ss;
279 struct statvfs stvfs;
280 struct termios tios;
281 socklen_t ssl;
282 off_t off;
283
284 /*
285 * Prime-sized mappings encourage fragmentation;
286 * thus exposing some address entropy.
287 */
288 struct mm {
289 size_t npg;
290 void *p;
291 } mm[] = {
292 { 17, MAP_FAILED }, { 3, MAP_FAILED },
293 { 11, MAP_FAILED }, { 2, MAP_FAILED },
294 { 5, MAP_FAILED }, { 3, MAP_FAILED },
295 { 7, MAP_FAILED }, { 1, MAP_FAILED },
296 { 57, MAP_FAILED }, { 3, MAP_FAILED },
297 { 131, MAP_FAILED }, { 1, MAP_FAILED },
298 };
299
300 for (m = 0; m < sizeof mm/sizeof(mm[0]); m++) {
301 HX(mm[m].p = mmap(NULL,
302 mm[m].npg * pgs,
303 PROT_READ|PROT_WRITE,
304 MAP_PRIVATE|MAP_ANON, -1,
305 (off_t)0), mm[m].p);
306 if (mm[m].p != MAP_FAILED) {
307 size_t mo;
308
309 /* Touch some memory... */
310 p = mm[m].p;
311 mo = cnt %
312 (mm[m].npg * pgs - 1);
313 p[mo] = 1;
314 cnt += (int)((long)(mm[m].p)
315 / pgs);
316 }
317
318 /* Check cnts and times... */
319 for (ii = 0; ii < sizeof(cl)/sizeof(cl[0]);
320 ii++) {
321 HX((e = clock_gettime(cl[ii],
322 &ts)) == -1, ts);
323 if (e != -1)
324 cnt += (int)ts.tv_nsec;
325 }
326
327 HX((e = getrusage(RUSAGE_SELF,
328 &ru)) == -1, ru);
329 if (e != -1) {
330 cnt += (int)ru.ru_utime.tv_sec;
331 cnt += (int)ru.ru_utime.tv_usec;
332 }
333 }
334
335 for (m = 0; m < sizeof mm/sizeof(mm[0]); m++) {
336 if (mm[m].p != MAP_FAILED)
337 munmap(mm[m].p, mm[m].npg * pgs);
338 mm[m].p = MAP_FAILED;
339 }
340
341 HX(stat(".", &st) == -1, st);
342 HX(statvfs(".", &stvfs) == -1, stvfs);
343
344 HX(stat("/", &st) == -1, st);
345 HX(statvfs("/", &stvfs) == -1, stvfs);
346
347 HX((e = fstat(0, &st)) == -1, st);
348 if (e == -1) {
349 if (S_ISREG(st.st_mode) ||
350 S_ISFIFO(st.st_mode) ||
351 S_ISSOCK(st.st_mode)) {
352 HX(fstatvfs(0, &stvfs) == -1,
353 stvfs);
354 HX((off = lseek(0, (off_t)0,
355 SEEK_CUR)) < 0, off);
356 }
357 if (S_ISCHR(st.st_mode)) {
358 HX(tcgetattr(0, &tios) == -1,
359 tios);
360 } else if (S_ISSOCK(st.st_mode)) {
361 memset(&ss, 0, sizeof ss);
362 ssl = sizeof(ss);
363 HX(getpeername(0,
364 (void *)&ss, &ssl) == -1,
365 ss);
366 }
367 }
368
369 HX((e = getrusage(RUSAGE_CHILDREN,
370 &ru)) == -1, ru);
371 if (e != -1) {
372 cnt += (int)ru.ru_utime.tv_sec;
373 cnt += (int)ru.ru_utime.tv_usec;
374 }
375 } else {
376 /* Subsequent hashes absorb previous result */
377 HD(results);
378 }
379
380 HX((e = gettimeofday(&tv, NULL)) == -1, tv);
381 if (e != -1) {
382 cnt += (int)tv.tv_sec;
383 cnt += (int)tv.tv_usec;
384 }
385
386 HD(cnt);
387 }
388 SHA512_Final(results, &ctx);
389 memcpy((char *)buf + i, results, MINIMUM(sizeof(results), len - i));
390 i += MINIMUM(sizeof(results), len - i);
391 }
392 explicit_bzero(&ctx, sizeof ctx);
393 explicit_bzero(results, sizeof results);
394 errno = save_errno;
395 return (0); /* satisfied */
396 }
397