lib/libcrypto/arc4random/getentropy_hpux.c

   1 /*      $OpenBSD: getentropy_hpux.c,v 1.5 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 #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 min(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 gotdata(char *buf, size_t len);
  68 static int getentropy_urandom(void *buf, size_t len, const char *path,
  69     int devfscheck);
  70 static int getentropy_fallback(void *buf, size_t len);
  71
  72 int
  73 getentropy(void *buf, size_t len)
  74 {
  75         int ret = -1;
  76
  77         if (len > 256) {
  78                 errno = EIO;
  79                 return (-1);
  80         }
  81
  82         /*
  83          * Try to get entropy with /dev/urandom
  84          */
  85         ret = getentropy_urandom(buf, len, "/dev/urandom", 0);
  86         if (ret != -1)
  87                 return (ret);
  88
  89         /*
  90          * Entropy collection via /dev/urandom has failed.
  91          *
  92          * No other API exists for collecting entropy, and we have
  93          * no failsafe way to get it on hpux that is not sensitive
  94          * to resource exhaustion.
  95          *
  96          * We have very few options:
  97          *     - Even syslog_r is unsafe to call at this low level, so
  98          *       there is no way to alert the user or program.
  99          *     - Cannot call abort() because some systems have unsafe
 100          *       corefiles.
 101          *     - Could raise(SIGKILL) resulting in silent program termination.
 102          *     - Return EIO, to hint that arc4random's stir function
 103          *       should raise(SIGKILL)
 104          *     - Do the best under the circumstances....
 105          *
 106          * This code path exists to bring light to the issue that hpux
 107          * does not provide a failsafe API for entropy collection.
 108          *
 109          * We hope this demonstrates that hpux should consider
 110          * providing a new failsafe API which works in a chroot or
 111          * when file descriptors are exhausted.
 112          */
 113 #undef FAIL_INSTEAD_OF_TRYING_FALLBACK
 114 #ifdef FAIL_INSTEAD_OF_TRYING_FALLBACK
 115         raise(SIGKILL);
 116 #endif
 117         ret = getentropy_fallback(buf, len);
 118         if (ret != -1)
 119                 return (ret);
 120
 121         errno = EIO;
 122         return (ret);
 123 }
 124
 125 /*
 126  * Basic sanity checking; wish we could do better.
 127  */
 128 static int
 129 gotdata(char *buf, size_t len)
 130 {
 131         char    any_set = 0;
 132         size_t  i;
 133
 134         for (i = 0; i < len; ++i)
 135                 any_set |= buf[i];
 136         if (any_set == 0)
 137                 return (-1);
 138         return (0);
 139 }
 140
 141 static int
 142 getentropy_urandom(void *buf, size_t len, const char *path, int devfscheck)
 143 {
 144         struct stat st;
 145         size_t i;
 146         int fd, flags;
 147         int save_errno = errno;
 148
 149 start:
 150
 151         flags = O_RDONLY;
 152 #ifdef O_NOFOLLOW
 153         flags |= O_NOFOLLOW;
 154 #endif
 155 #ifdef O_CLOEXEC
 156         flags |= O_CLOEXEC;
 157 #endif
 158         fd = open(path, flags, 0);
 159         if (fd == -1) {
 160                 if (errno == EINTR)
 161                         goto start;
 162                 goto nodevrandom;
 163         }
 164 #ifndef O_CLOEXEC
 165         fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
 166 #endif
 167
 168         /* Lightly verify that the device node looks sane */
 169         if (fstat(fd, &st) == -1 || !S_ISCHR(st.st_mode)) {
 170                 close(fd);
 171                 goto nodevrandom;
 172         }
 173         for (i = 0; i < len; ) {
 174                 size_t wanted = len - i;
 175                 ssize_t ret = read(fd, (char *)buf + i, wanted);
 176
 177                 if (ret == -1) {
 178                         if (errno == EAGAIN || errno == EINTR)
 179                                 continue;
 180                         close(fd);
 181                         goto nodevrandom;
 182                 }
 183                 i += ret;
 184         }
 185         close(fd);
 186         if (gotdata(buf, len) == 0) {
 187                 errno = save_errno;
 188                 return (0);             /* satisfied */
 189         }
 190 nodevrandom:
 191         errno = EIO;
 192         return (-1);
 193 }
 194
 195 static const int cl[] = {
 196         CLOCK_REALTIME,
 197 #ifdef CLOCK_MONOTONIC
 198         CLOCK_MONOTONIC,
 199 #endif
 200 #ifdef CLOCK_MONOTONIC_RAW
 201         CLOCK_MONOTONIC_RAW,
 202 #endif
 203 #ifdef CLOCK_TAI
 204         CLOCK_TAI,
 205 #endif
 206 #ifdef CLOCK_VIRTUAL
 207         CLOCK_VIRTUAL,
 208 #endif
 209 #ifdef CLOCK_UPTIME
 210         CLOCK_UPTIME,
 211 #endif
 212 #ifdef CLOCK_PROCESS_CPUTIME_ID
 213         CLOCK_PROCESS_CPUTIME_ID,
 214 #endif
 215 #ifdef CLOCK_THREAD_CPUTIME_ID
 216         CLOCK_THREAD_CPUTIME_ID,
 217 #endif
 218 };
 219
 220 static int
 221 getentropy_fallback(void *buf, size_t len)
 222 {
 223         uint8_t results[SHA512_DIGEST_LENGTH];
 224         int save_errno = errno, e, pgs = sysconf(_SC_PAGESIZE), faster = 0, repeat;
 225         static int cnt;
 226         struct timespec ts;
 227         struct timeval tv;
 228         struct pst_vminfo pvi;
 229         struct pst_vm_status pvs;
 230         struct pst_dynamic pdy;
 231         struct rusage ru;
 232         sigset_t sigset;
 233         struct stat st;
 234         SHA512_CTX ctx;
 235         static pid_t lastpid;
 236         pid_t pid;
 237         size_t i, ii, m;
 238         char *p;
 239
 240         pid = getpid();
 241         if (lastpid == pid) {
 242                 faster = 1;
 243                 repeat = 2;
 244         } else {
 245                 faster = 0;
 246                 lastpid = pid;
 247                 repeat = REPEAT;
 248         }
 249         for (i = 0; i < len; ) {
 250                 int j;
 251                 SHA512_Init(&ctx);
 252                 for (j = 0; j < repeat; j++) {
 253                         HX((e = gettimeofday(&tv, NULL)) == -1, tv);
 254                         if (e != -1) {
 255                                 cnt += (int)tv.tv_sec;
 256                                 cnt += (int)tv.tv_usec;
 257                         }
 258
 259                         HX(pstat_getvminfo(&pvi, sizeof(pvi), 1, 0) != 1, pvi);
 260                         HX(pstat_getprocvm(&pvs, sizeof(pvs), 0, 0) != 1, pvs);
 261
 262                         for (ii = 0; ii < sizeof(cl)/sizeof(cl[0]); ii++)
 263                                 HX(clock_gettime(cl[ii], &ts) == -1, ts);
 264
 265                         HX((pid = getpid()) == -1, pid);
 266                         HX((pid = getsid(pid)) == -1, pid);
 267                         HX((pid = getppid()) == -1, pid);
 268                         HX((pid = getpgid(0)) == -1, pid);
 269                         HX((e = getpriority(0, 0)) == -1, e);
 270
 271                         if(pstat_getdynamic(&pdy, sizeof(pdy), 1, 0) != 1) {
 272                                 HD(errno);
 273                         } else {
 274                                 HD(pdy.psd_avg_1_min);
 275                                 HD(pdy.psd_avg_5_min);
 276                                 HD(pdy.psd_avg_15_min);
 277                         }
 278
 279                         if (!faster) {
 280                                 ts.tv_sec = 0;
 281                                 ts.tv_nsec = 1;
 282                                 (void) nanosleep(&ts, NULL);
 283                         }
 284
 285                         HX(sigpending(&sigset) == -1, sigset);
 286                         HX(sigprocmask(SIG_BLOCK, NULL, &sigset) == -1,
 287                             sigset);
 288
 289                         HF(getentropy); /* an addr in this library */
 290                         HF(printf);             /* an addr in libc */
 291                         p = (char *)&p;
 292                         HD(p);          /* an addr on stack */
 293                         p = (char *)&errno;
 294                         HD(p);          /* the addr of errno */
 295
 296                         if (i == 0) {
 297                                 struct sockaddr_storage ss;
 298                                 struct statvfs stvfs;
 299                                 struct termios tios;
 300                                 socklen_t ssl;
 301                                 off_t off;
 302
 303                                 /*
 304                                  * Prime-sized mappings encourage fragmentation;
 305                                  * thus exposing some address entropy.
 306                                  */
 307                                 struct mm {
 308                                         size_t  npg;
 309                                         void    *p;
 310                                 } mm[] =         {
 311                                         { 17, MAP_FAILED }, { 3, MAP_FAILED },
 312                                         { 11, MAP_FAILED }, { 2, MAP_FAILED },
 313                                         { 5, MAP_FAILED }, { 3, MAP_FAILED },
 314                                         { 7, MAP_FAILED }, { 1, MAP_FAILED },
 315                                         { 57, MAP_FAILED }, { 3, MAP_FAILED },
 316                                         { 131, MAP_FAILED }, { 1, MAP_FAILED },
 317                                 };
 318
 319                                 for (m = 0; m < sizeof mm/sizeof(mm[0]); m++) {
 320                                         HX(mm[m].p = mmap(NULL,
 321                                             mm[m].npg * pgs,
 322                                             PROT_READ|PROT_WRITE,
 323                                             MAP_PRIVATE|MAP_ANON, -1,
 324                                             (off_t)0), mm[m].p);
 325                                         if (mm[m].p != MAP_FAILED) {
 326                                                 size_t mo;
 327
 328                                                 /* Touch some memory... */
 329                                                 p = mm[m].p;
 330                                                 mo = cnt %
 331                                                     (mm[m].npg * pgs - 1);
 332                                                 p[mo] = 1;
 333                                                 cnt += (int)((long)(mm[m].p)
 334                                                     / pgs);
 335                                         }
 336
 337                                         /* Check cnts and times... */
 338                                         for (ii = 0; ii < sizeof(cl)/sizeof(cl[0]);
 339                                             ii++) {
 340                                                 HX((e = clock_gettime(cl[ii],
 341                                                     &ts)) == -1, ts);
 342                                                 if (e != -1)
 343                                                         cnt += (int)ts.tv_nsec;
 344                                         }
 345
 346                                         HX((e = getrusage(RUSAGE_SELF,
 347                                             &ru)) == -1, ru);
 348                                         if (e != -1) {
 349                                                 cnt += (int)ru.ru_utime.tv_sec;
 350                                                 cnt += (int)ru.ru_utime.tv_usec;
 351                                         }
 352                                 }
 353
 354                                 for (m = 0; m < sizeof mm/sizeof(mm[0]); m++) {
 355                                         if (mm[m].p != MAP_FAILED)
 356                                                 munmap(mm[m].p, mm[m].npg * pgs);
 357                                         mm[m].p = MAP_FAILED;
 358                                 }
 359
 360                                 HX(stat(".", &st) == -1, st);
 361                                 HX(statvfs(".", &stvfs) == -1, stvfs);
 362
 363                                 HX(stat("/", &st) == -1, st);
 364                                 HX(statvfs("/", &stvfs) == -1, stvfs);
 365
 366                                 HX((e = fstat(0, &st)) == -1, st);
 367                                 if (e == -1) {
 368                                         if (S_ISREG(st.st_mode) ||
 369                                             S_ISFIFO(st.st_mode) ||
 370                                             S_ISSOCK(st.st_mode)) {
 371                                                 HX(fstatvfs(0, &stvfs) == -1,
 372                                                     stvfs);
 373                                                 HX((off = lseek(0, (off_t)0,
 374                                                     SEEK_CUR)) < 0, off);
 375                                         }
 376                                         if (S_ISCHR(st.st_mode)) {
 377                                                 HX(tcgetattr(0, &tios) == -1,
 378                                                     tios);
 379                                         } else if (S_ISSOCK(st.st_mode)) {
 380                                                 memset(&ss, 0, sizeof ss);
 381                                                 ssl = sizeof(ss);
 382                                                 HX(getpeername(0,
 383                                                     (void *)&ss, &ssl) == -1,
 384                                                     ss);
 385                                         }
 386                                 }
 387
 388                                 HX((e = getrusage(RUSAGE_CHILDREN,
 389                                     &ru)) == -1, ru);
 390                                 if (e != -1) {
 391                                         cnt += (int)ru.ru_utime.tv_sec;
 392                                         cnt += (int)ru.ru_utime.tv_usec;
 393                                 }
 394                         } else {
 395                                 /* Subsequent hashes absorb previous result */
 396                                 HD(results);
 397                         }
 398
 399                         HX((e = gettimeofday(&tv, NULL)) == -1, tv);
 400                         if (e != -1) {
 401                                 cnt += (int)tv.tv_sec;
 402                                 cnt += (int)tv.tv_usec;
 403                         }
 404
 405                         HD(cnt);
 406                 }
 407                 SHA512_Final(results, &ctx);
 408                 memcpy((char *)buf + i, results, min(sizeof(results), len - i));
 409                 i += min(sizeof(results), len - i);
 410         }
 411         explicit_bzero(&ctx, sizeof ctx);
 412         explicit_bzero(results, sizeof results);
 413         if (gotdata(buf, len) == 0) {
 414                 errno = save_errno;
 415                 return (0);             /* satisfied */
 416         }
 417         errno = EIO;
 418         return (-1);
 419 }