Damien Miller | 62116dc | 2001-12-24 01:41:47 +1100 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (c) 2001 Damien Miller. All rights reserved. |
| 3 | * |
| 4 | * Redistribution and use in source and binary forms, with or without |
| 5 | * modification, are permitted provided that the following conditions |
| 6 | * are met: |
| 7 | * 1. Redistributions of source code must retain the above copyright |
| 8 | * notice, this list of conditions and the following disclaimer. |
| 9 | * 2. Redistributions in binary form must reproduce the above copyright |
| 10 | * notice, this list of conditions and the following disclaimer in the |
| 11 | * documentation and/or other materials provided with the distribution. |
| 12 | * |
| 13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 23 | */ |
| 24 | |
| 25 | #include "includes.h" |
| 26 | |
| 27 | #include <openssl/rand.h> |
| 28 | #include <openssl/sha.h> |
| 29 | #include <openssl/crypto.h> |
| 30 | |
| 31 | /* SunOS 4.4.4 needs this */ |
| 32 | #ifdef HAVE_FLOATINGPOINT_H |
| 33 | # include <floatingpoint.h> |
| 34 | #endif /* HAVE_FLOATINGPOINT_H */ |
| 35 | |
| 36 | #include "misc.h" |
| 37 | #include "xmalloc.h" |
| 38 | #include "atomicio.h" |
| 39 | #include "pathnames.h" |
| 40 | #include "log.h" |
| 41 | |
| 42 | RCSID("$Id: ssh-rand-helper.c,v 1.1 2001/12/23 14:41:48 djm Exp $"); |
| 43 | |
| 44 | #define RANDOM_SEED_SIZE 48 |
| 45 | |
| 46 | #ifndef SSH_PRNG_SEED_FILE |
| 47 | # define SSH_PRNG_SEED_FILE _PATH_SSH_USER_DIR"/prng_seed" |
| 48 | #endif /* SSH_PRNG_SEED_FILE */ |
| 49 | #ifndef SSH_PRNG_COMMAND_FILE |
| 50 | # define SSH_PRNG_COMMAND_FILE ETCDIR "/ssh_prng_cmds" |
| 51 | #endif /* SSH_PRNG_COMMAND_FILE */ |
| 52 | |
| 53 | |
| 54 | #ifndef offsetof |
| 55 | # define offsetof(type, member) ((size_t) &((type *)0)->member) |
| 56 | #endif |
| 57 | |
| 58 | /* Number of times to pass through command list gathering entropy */ |
| 59 | #define NUM_ENTROPY_RUNS 1 |
| 60 | |
| 61 | /* Scale entropy estimates back by this amount on subsequent runs */ |
| 62 | #define SCALE_PER_RUN 10.0 |
| 63 | |
| 64 | /* Minimum number of commands to be considered valid */ |
| 65 | #define MIN_ENTROPY_SOURCES 16 |
| 66 | |
| 67 | #define WHITESPACE " \t\n" |
| 68 | |
| 69 | #ifndef RUSAGE_SELF |
| 70 | # define RUSAGE_SELF 0 |
| 71 | #endif |
| 72 | #ifndef RUSAGE_CHILDREN |
| 73 | # define RUSAGE_CHILDREN 0 |
| 74 | #endif |
| 75 | |
| 76 | #if defined(PRNGD_SOCKET) || defined(PRNGD_PORT) |
| 77 | # define USE_PRNGD |
| 78 | #endif |
| 79 | |
| 80 | #ifdef USE_PRNGD |
| 81 | /* Collect entropy from PRNGD/EGD */ |
| 82 | int |
| 83 | get_random_bytes(unsigned char *buf, int len) |
| 84 | { |
| 85 | int fd; |
| 86 | char msg[2]; |
| 87 | #ifdef PRNGD_PORT |
| 88 | struct sockaddr_in addr; |
| 89 | #else |
| 90 | struct sockaddr_un addr; |
| 91 | #endif |
| 92 | int addr_len, rval, errors; |
| 93 | mysig_t old_sigpipe; |
| 94 | |
| 95 | if (len > 255) |
| 96 | fatal("Too many bytes to read from PRNGD"); |
| 97 | |
| 98 | memset(&addr, '\0', sizeof(addr)); |
| 99 | |
| 100 | #ifdef PRNGD_PORT |
| 101 | addr.sin_family = AF_INET; |
| 102 | addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK); |
| 103 | addr.sin_port = htons(PRNGD_PORT); |
| 104 | addr_len = sizeof(struct sockaddr_in); |
| 105 | #else /* use IP socket PRNGD_SOCKET instead */ |
| 106 | /* Sanity checks */ |
| 107 | if (sizeof(PRNGD_SOCKET) > sizeof(addr.sun_path)) |
| 108 | fatal("Random pool path is too long"); |
| 109 | |
| 110 | addr.sun_family = AF_UNIX; |
| 111 | strlcpy(addr.sun_path, PRNGD_SOCKET, sizeof(addr.sun_path)); |
| 112 | addr_len = offsetof(struct sockaddr_un, sun_path) + |
| 113 | sizeof(PRNGD_SOCKET); |
| 114 | #endif |
| 115 | |
| 116 | old_sigpipe = mysignal(SIGPIPE, SIG_IGN); |
| 117 | |
| 118 | errors = rval = 0; |
| 119 | reopen: |
| 120 | #ifdef PRNGD_PORT |
| 121 | fd = socket(addr.sin_family, SOCK_STREAM, 0); |
| 122 | if (fd == -1) { |
| 123 | error("Couldn't create AF_INET socket: %s", strerror(errno)); |
| 124 | goto done; |
| 125 | } |
| 126 | #else |
| 127 | fd = socket(addr.sun_family, SOCK_STREAM, 0); |
| 128 | if (fd == -1) { |
| 129 | error("Couldn't create AF_UNIX socket: %s", strerror(errno)); |
| 130 | goto done; |
| 131 | } |
| 132 | #endif |
| 133 | |
| 134 | if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) { |
| 135 | #ifdef PRNGD_PORT |
| 136 | error("Couldn't connect to PRNGD port %d: %s", |
| 137 | PRNGD_PORT, strerror(errno)); |
| 138 | #else |
| 139 | error("Couldn't connect to PRNGD socket \"%s\": %s", |
| 140 | addr.sun_path, strerror(errno)); |
| 141 | #endif |
| 142 | goto done; |
| 143 | } |
| 144 | |
| 145 | /* Send blocking read request to PRNGD */ |
| 146 | msg[0] = 0x02; |
| 147 | msg[1] = len; |
| 148 | |
| 149 | if (atomicio(write, fd, msg, sizeof(msg)) != sizeof(msg)) { |
| 150 | if (errno == EPIPE && errors < 10) { |
| 151 | close(fd); |
| 152 | errors++; |
| 153 | goto reopen; |
| 154 | } |
| 155 | error("Couldn't write to PRNGD socket: %s", |
| 156 | strerror(errno)); |
| 157 | goto done; |
| 158 | } |
| 159 | |
| 160 | if (atomicio(read, fd, buf, len) != len) { |
| 161 | if (errno == EPIPE && errors < 10) { |
| 162 | close(fd); |
| 163 | errors++; |
| 164 | goto reopen; |
| 165 | } |
| 166 | error("Couldn't read from PRNGD socket: %s", |
| 167 | strerror(errno)); |
| 168 | goto done; |
| 169 | } |
| 170 | |
| 171 | rval = 1; |
| 172 | done: |
| 173 | mysignal(SIGPIPE, old_sigpipe); |
| 174 | if (fd != -1) |
| 175 | close(fd); |
| 176 | return(rval); |
| 177 | } |
| 178 | |
| 179 | static void |
| 180 | seed_openssl_rng(void) |
| 181 | { |
| 182 | unsigned char buf[RANDOM_SEED_SIZE]; |
| 183 | |
| 184 | if (!get_random_bytes(buf, sizeof(buf))) |
| 185 | fatal("Entropy collection failed"); |
| 186 | |
| 187 | RAND_add(buf, sizeof(buf), sizeof(buf)); |
| 188 | memset(buf, '\0', sizeof(buf)); |
| 189 | } |
| 190 | |
| 191 | #else /* USE_PRNGD */ |
| 192 | |
| 193 | /* |
| 194 | * FIXME: proper entropy estimations. All current values are guesses |
| 195 | * FIXME: (ATL) do estimates at compile time? |
| 196 | * FIXME: More entropy sources |
| 197 | */ |
| 198 | |
| 199 | /* slow command timeouts (all in milliseconds) */ |
| 200 | /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */ |
| 201 | static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC; |
| 202 | |
| 203 | typedef struct |
| 204 | { |
| 205 | /* Proportion of data that is entropy */ |
| 206 | double rate; |
| 207 | /* Counter goes positive if this command times out */ |
| 208 | unsigned int badness; |
| 209 | /* Increases by factor of two each timeout */ |
| 210 | unsigned int sticky_badness; |
| 211 | /* Path to executable */ |
| 212 | char *path; |
| 213 | /* argv to pass to executable */ |
| 214 | char *args[5]; |
| 215 | /* full command string (debug) */ |
| 216 | char *cmdstring; |
| 217 | } entropy_source_t; |
| 218 | |
| 219 | double stir_from_system(void); |
| 220 | double stir_from_programs(void); |
| 221 | double stir_gettimeofday(double entropy_estimate); |
| 222 | double stir_clock(double entropy_estimate); |
| 223 | double stir_rusage(int who, double entropy_estimate); |
| 224 | double hash_output_from_command(entropy_source_t *src, char *hash); |
| 225 | |
| 226 | /* this is initialised from a file, by prng_read_commands() */ |
| 227 | entropy_source_t *entropy_sources = NULL; |
| 228 | |
| 229 | double |
| 230 | stir_from_system(void) |
| 231 | { |
| 232 | double total_entropy_estimate; |
| 233 | long int i; |
| 234 | |
| 235 | total_entropy_estimate = 0; |
| 236 | |
| 237 | i = getpid(); |
| 238 | RAND_add(&i, sizeof(i), 0.5); |
| 239 | total_entropy_estimate += 0.1; |
| 240 | |
| 241 | i = getppid(); |
| 242 | RAND_add(&i, sizeof(i), 0.5); |
| 243 | total_entropy_estimate += 0.1; |
| 244 | |
| 245 | i = getuid(); |
| 246 | RAND_add(&i, sizeof(i), 0.0); |
| 247 | i = getgid(); |
| 248 | RAND_add(&i, sizeof(i), 0.0); |
| 249 | |
| 250 | total_entropy_estimate += stir_gettimeofday(1.0); |
| 251 | total_entropy_estimate += stir_clock(0.5); |
| 252 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0); |
| 253 | |
| 254 | return(total_entropy_estimate); |
| 255 | } |
| 256 | |
| 257 | double |
| 258 | stir_from_programs(void) |
| 259 | { |
| 260 | int i; |
| 261 | int c; |
| 262 | double entropy_estimate; |
| 263 | double total_entropy_estimate; |
| 264 | char hash[SHA_DIGEST_LENGTH]; |
| 265 | |
| 266 | total_entropy_estimate = 0; |
| 267 | for(i = 0; i < NUM_ENTROPY_RUNS; i++) { |
| 268 | c = 0; |
| 269 | while (entropy_sources[c].path != NULL) { |
| 270 | |
| 271 | if (!entropy_sources[c].badness) { |
| 272 | /* Hash output from command */ |
| 273 | entropy_estimate = hash_output_from_command(&entropy_sources[c], hash); |
| 274 | |
| 275 | /* Scale back entropy estimate according to command's rate */ |
| 276 | entropy_estimate *= entropy_sources[c].rate; |
| 277 | |
| 278 | /* Upper bound of entropy estimate is SHA_DIGEST_LENGTH */ |
| 279 | if (entropy_estimate > SHA_DIGEST_LENGTH) |
| 280 | entropy_estimate = SHA_DIGEST_LENGTH; |
| 281 | |
| 282 | /* Scale back estimates for subsequent passes through list */ |
| 283 | entropy_estimate /= SCALE_PER_RUN * (i + 1.0); |
| 284 | |
| 285 | /* Stir it in */ |
| 286 | RAND_add(hash, sizeof(hash), entropy_estimate); |
| 287 | |
| 288 | debug3("Got %0.2f bytes of entropy from '%s'", entropy_estimate, |
| 289 | entropy_sources[c].cmdstring); |
| 290 | |
| 291 | total_entropy_estimate += entropy_estimate; |
| 292 | |
| 293 | /* Execution times should be a little unpredictable */ |
| 294 | total_entropy_estimate += stir_gettimeofday(0.05); |
| 295 | total_entropy_estimate += stir_clock(0.05); |
| 296 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 0.1); |
| 297 | total_entropy_estimate += stir_rusage(RUSAGE_CHILDREN, 0.1); |
| 298 | } else { |
| 299 | debug2("Command '%s' disabled (badness %d)", |
| 300 | entropy_sources[c].cmdstring, entropy_sources[c].badness); |
| 301 | |
| 302 | if (entropy_sources[c].badness > 0) |
| 303 | entropy_sources[c].badness--; |
| 304 | } |
| 305 | |
| 306 | c++; |
| 307 | } |
| 308 | } |
| 309 | |
| 310 | return(total_entropy_estimate); |
| 311 | } |
| 312 | |
| 313 | double |
| 314 | stir_gettimeofday(double entropy_estimate) |
| 315 | { |
| 316 | struct timeval tv; |
| 317 | |
| 318 | if (gettimeofday(&tv, NULL) == -1) |
| 319 | fatal("Couldn't gettimeofday: %s", strerror(errno)); |
| 320 | |
| 321 | RAND_add(&tv, sizeof(tv), entropy_estimate); |
| 322 | |
| 323 | return(entropy_estimate); |
| 324 | } |
| 325 | |
| 326 | double |
| 327 | stir_clock(double entropy_estimate) |
| 328 | { |
| 329 | #ifdef HAVE_CLOCK |
| 330 | clock_t c; |
| 331 | |
| 332 | c = clock(); |
| 333 | RAND_add(&c, sizeof(c), entropy_estimate); |
| 334 | |
| 335 | return(entropy_estimate); |
| 336 | #else /* _HAVE_CLOCK */ |
| 337 | return(0); |
| 338 | #endif /* _HAVE_CLOCK */ |
| 339 | } |
| 340 | |
| 341 | double |
| 342 | stir_rusage(int who, double entropy_estimate) |
| 343 | { |
| 344 | #ifdef HAVE_GETRUSAGE |
| 345 | struct rusage ru; |
| 346 | |
| 347 | if (getrusage(who, &ru) == -1) |
| 348 | return(0); |
| 349 | |
| 350 | RAND_add(&ru, sizeof(ru), entropy_estimate); |
| 351 | |
| 352 | return(entropy_estimate); |
| 353 | #else /* _HAVE_GETRUSAGE */ |
| 354 | return(0); |
| 355 | #endif /* _HAVE_GETRUSAGE */ |
| 356 | } |
| 357 | |
| 358 | |
| 359 | static int |
| 360 | _get_timeval_msec_difference(struct timeval *t1, struct timeval *t2) { |
| 361 | int secdiff, usecdiff; |
| 362 | |
| 363 | secdiff = t2->tv_sec - t1->tv_sec; |
| 364 | usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec); |
| 365 | return (int)(usecdiff / 1000); |
| 366 | } |
| 367 | |
| 368 | double |
| 369 | hash_output_from_command(entropy_source_t *src, char *hash) |
| 370 | { |
| 371 | static int devnull = -1; |
| 372 | int p[2]; |
| 373 | fd_set rdset; |
| 374 | int cmd_eof = 0, error_abort = 0; |
| 375 | struct timeval tv_start, tv_current; |
| 376 | int msec_elapsed = 0; |
| 377 | pid_t pid; |
| 378 | int status; |
| 379 | char buf[16384]; |
| 380 | int bytes_read; |
| 381 | int total_bytes_read; |
| 382 | SHA_CTX sha; |
| 383 | |
| 384 | debug3("Reading output from \'%s\'", src->cmdstring); |
| 385 | |
| 386 | if (devnull == -1) { |
| 387 | devnull = open("/dev/null", O_RDWR); |
| 388 | if (devnull == -1) |
| 389 | fatal("Couldn't open /dev/null: %s", strerror(errno)); |
| 390 | } |
| 391 | |
| 392 | if (pipe(p) == -1) |
| 393 | fatal("Couldn't open pipe: %s", strerror(errno)); |
| 394 | |
| 395 | (void)gettimeofday(&tv_start, NULL); /* record start time */ |
| 396 | |
| 397 | switch (pid = fork()) { |
| 398 | case -1: /* Error */ |
| 399 | close(p[0]); |
| 400 | close(p[1]); |
| 401 | fatal("Couldn't fork: %s", strerror(errno)); |
| 402 | /* NOTREACHED */ |
| 403 | case 0: /* Child */ |
| 404 | dup2(devnull, STDIN_FILENO); |
| 405 | dup2(p[1], STDOUT_FILENO); |
| 406 | dup2(p[1], STDERR_FILENO); |
| 407 | close(p[0]); |
| 408 | close(p[1]); |
| 409 | close(devnull); |
| 410 | |
| 411 | execv(src->path, (char**)(src->args)); |
| 412 | debug("(child) Couldn't exec '%s': %s", src->cmdstring, |
| 413 | strerror(errno)); |
| 414 | _exit(-1); |
| 415 | default: /* Parent */ |
| 416 | break; |
| 417 | } |
| 418 | |
| 419 | RAND_add(&pid, sizeof(&pid), 0.0); |
| 420 | |
| 421 | close(p[1]); |
| 422 | |
| 423 | /* Hash output from child */ |
| 424 | SHA1_Init(&sha); |
| 425 | total_bytes_read = 0; |
| 426 | |
| 427 | while (!error_abort && !cmd_eof) { |
| 428 | int ret; |
| 429 | struct timeval tv; |
| 430 | int msec_remaining; |
| 431 | |
| 432 | (void) gettimeofday(&tv_current, 0); |
| 433 | msec_elapsed = _get_timeval_msec_difference(&tv_start, &tv_current); |
| 434 | if (msec_elapsed >= entropy_timeout_current) { |
| 435 | error_abort=1; |
| 436 | continue; |
| 437 | } |
| 438 | msec_remaining = entropy_timeout_current - msec_elapsed; |
| 439 | |
| 440 | FD_ZERO(&rdset); |
| 441 | FD_SET(p[0], &rdset); |
| 442 | tv.tv_sec = msec_remaining / 1000; |
| 443 | tv.tv_usec = (msec_remaining % 1000) * 1000; |
| 444 | |
| 445 | ret = select(p[0]+1, &rdset, NULL, NULL, &tv); |
| 446 | |
| 447 | RAND_add(&tv, sizeof(tv), 0.0); |
| 448 | |
| 449 | switch (ret) { |
| 450 | case 0: |
| 451 | /* timer expired */ |
| 452 | error_abort = 1; |
| 453 | break; |
| 454 | case 1: |
| 455 | /* command input */ |
| 456 | do { |
| 457 | bytes_read = read(p[0], buf, sizeof(buf)); |
| 458 | } while (bytes_read == -1 && errno == EINTR); |
| 459 | RAND_add(&bytes_read, sizeof(&bytes_read), 0.0); |
| 460 | if (bytes_read == -1) { |
| 461 | error_abort = 1; |
| 462 | break; |
| 463 | } else if (bytes_read) { |
| 464 | SHA1_Update(&sha, buf, bytes_read); |
| 465 | total_bytes_read += bytes_read; |
| 466 | } else { |
| 467 | cmd_eof = 1; |
| 468 | } |
| 469 | break; |
| 470 | case -1: |
| 471 | default: |
| 472 | /* error */ |
| 473 | debug("Command '%s': select() failed: %s", src->cmdstring, |
| 474 | strerror(errno)); |
| 475 | error_abort = 1; |
| 476 | break; |
| 477 | } |
| 478 | } |
| 479 | |
| 480 | SHA1_Final(hash, &sha); |
| 481 | |
| 482 | close(p[0]); |
| 483 | |
| 484 | debug3("Time elapsed: %d msec", msec_elapsed); |
| 485 | |
| 486 | if (waitpid(pid, &status, 0) == -1) { |
| 487 | error("Couldn't wait for child '%s' completion: %s", src->cmdstring, |
| 488 | strerror(errno)); |
| 489 | return(0.0); |
| 490 | } |
| 491 | |
| 492 | RAND_add(&status, sizeof(&status), 0.0); |
| 493 | |
| 494 | if (error_abort) { |
| 495 | /* closing p[0] on timeout causes the entropy command to |
| 496 | * SIGPIPE. Take whatever output we got, and mark this command |
| 497 | * as slow */ |
| 498 | debug2("Command '%s' timed out", src->cmdstring); |
| 499 | src->sticky_badness *= 2; |
| 500 | src->badness = src->sticky_badness; |
| 501 | return(total_bytes_read); |
| 502 | } |
| 503 | |
| 504 | if (WIFEXITED(status)) { |
| 505 | if (WEXITSTATUS(status)==0) { |
| 506 | return(total_bytes_read); |
| 507 | } else { |
| 508 | debug2("Command '%s' exit status was %d", src->cmdstring, |
| 509 | WEXITSTATUS(status)); |
| 510 | src->badness = src->sticky_badness = 128; |
| 511 | return (0.0); |
| 512 | } |
| 513 | } else if (WIFSIGNALED(status)) { |
| 514 | debug2("Command '%s' returned on uncaught signal %d !", src->cmdstring, |
| 515 | status); |
| 516 | src->badness = src->sticky_badness = 128; |
| 517 | return(0.0); |
| 518 | } else |
| 519 | return(0.0); |
| 520 | } |
| 521 | |
| 522 | /* |
| 523 | * prng seedfile functions |
| 524 | */ |
| 525 | int |
| 526 | prng_check_seedfile(char *filename) { |
| 527 | |
| 528 | struct stat st; |
| 529 | |
| 530 | /* FIXME raceable: eg replace seed between this stat and subsequent open */ |
| 531 | /* Not such a problem because we don't trust the seed file anyway */ |
| 532 | if (lstat(filename, &st) == -1) { |
| 533 | /* Give up on hard errors */ |
| 534 | if (errno != ENOENT) |
| 535 | debug("WARNING: Couldn't stat random seed file \"%s\": %s", |
| 536 | filename, strerror(errno)); |
| 537 | |
| 538 | return(0); |
| 539 | } |
| 540 | |
| 541 | /* regular file? */ |
| 542 | if (!S_ISREG(st.st_mode)) |
| 543 | fatal("PRNG seedfile %.100s is not a regular file", filename); |
| 544 | |
| 545 | /* mode 0600, owned by root or the current user? */ |
| 546 | if (((st.st_mode & 0177) != 0) || !(st.st_uid == getuid())) { |
| 547 | debug("WARNING: PRNG seedfile %.100s must be mode 0600, owned by uid %d", |
| 548 | filename, getuid()); |
| 549 | return(0); |
| 550 | } |
| 551 | |
| 552 | return(1); |
| 553 | } |
| 554 | |
| 555 | void |
| 556 | prng_write_seedfile(void) { |
| 557 | int fd; |
| 558 | char seed[1024]; |
| 559 | char filename[1024]; |
| 560 | struct passwd *pw; |
| 561 | |
| 562 | pw = getpwuid(getuid()); |
| 563 | if (pw == NULL) |
| 564 | fatal("Couldn't get password entry for current user (%i): %s", |
| 565 | getuid(), strerror(errno)); |
| 566 | |
| 567 | /* Try to ensure that the parent directory is there */ |
| 568 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, |
| 569 | _PATH_SSH_USER_DIR); |
| 570 | mkdir(filename, 0700); |
| 571 | |
| 572 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, |
| 573 | SSH_PRNG_SEED_FILE); |
| 574 | |
| 575 | debug("writing PRNG seed to file %.100s", filename); |
| 576 | |
| 577 | RAND_bytes(seed, sizeof(seed)); |
| 578 | |
| 579 | /* Don't care if the seed doesn't exist */ |
| 580 | prng_check_seedfile(filename); |
| 581 | |
| 582 | if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1) { |
| 583 | debug("WARNING: couldn't access PRNG seedfile %.100s (%.100s)", |
| 584 | filename, strerror(errno)); |
| 585 | } else { |
| 586 | if (atomicio(write, fd, &seed, sizeof(seed)) != sizeof(seed)) |
| 587 | fatal("problem writing PRNG seedfile %.100s (%.100s)", filename, |
| 588 | strerror(errno)); |
| 589 | close(fd); |
| 590 | } |
| 591 | } |
| 592 | |
| 593 | void |
| 594 | prng_read_seedfile(void) { |
| 595 | int fd; |
| 596 | char seed[1024]; |
| 597 | char filename[1024]; |
| 598 | struct passwd *pw; |
| 599 | |
| 600 | pw = getpwuid(getuid()); |
| 601 | if (pw == NULL) |
| 602 | fatal("Couldn't get password entry for current user (%i): %s", |
| 603 | getuid(), strerror(errno)); |
| 604 | |
| 605 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, |
| 606 | SSH_PRNG_SEED_FILE); |
| 607 | |
| 608 | debug("loading PRNG seed from file %.100s", filename); |
| 609 | |
| 610 | if (!prng_check_seedfile(filename)) { |
| 611 | verbose("Random seed file not found or not valid, ignoring."); |
| 612 | return; |
| 613 | } |
| 614 | |
| 615 | /* open the file and read in the seed */ |
| 616 | fd = open(filename, O_RDONLY); |
| 617 | if (fd == -1) |
| 618 | fatal("could not open PRNG seedfile %.100s (%.100s)", filename, |
| 619 | strerror(errno)); |
| 620 | |
| 621 | if (atomicio(read, fd, &seed, sizeof(seed)) != sizeof(seed)) { |
| 622 | verbose("invalid or short read from PRNG seedfile %.100s - ignoring", |
| 623 | filename); |
| 624 | memset(seed, '\0', sizeof(seed)); |
| 625 | } |
| 626 | close(fd); |
| 627 | |
| 628 | /* stir in the seed, with estimated entropy zero */ |
| 629 | RAND_add(&seed, sizeof(seed), 0.0); |
| 630 | } |
| 631 | |
| 632 | |
| 633 | /* |
| 634 | * entropy command initialisation functions |
| 635 | */ |
| 636 | int |
| 637 | prng_read_commands(char *cmdfilename) |
| 638 | { |
| 639 | FILE *f; |
| 640 | char *cp; |
| 641 | char line[1024]; |
| 642 | char cmd[1024]; |
| 643 | char path[256]; |
| 644 | int linenum; |
| 645 | int num_cmds = 64; |
| 646 | int cur_cmd = 0; |
| 647 | double est; |
| 648 | entropy_source_t *entcmd; |
| 649 | |
| 650 | f = fopen(cmdfilename, "r"); |
| 651 | if (!f) { |
| 652 | fatal("couldn't read entropy commands file %.100s: %.100s", |
| 653 | cmdfilename, strerror(errno)); |
| 654 | } |
| 655 | |
| 656 | entcmd = (entropy_source_t *)xmalloc(num_cmds * sizeof(entropy_source_t)); |
| 657 | memset(entcmd, '\0', num_cmds * sizeof(entropy_source_t)); |
| 658 | |
| 659 | /* Read in file */ |
| 660 | linenum = 0; |
| 661 | while (fgets(line, sizeof(line), f)) { |
| 662 | int arg; |
| 663 | char *argv; |
| 664 | |
| 665 | linenum++; |
| 666 | |
| 667 | /* skip leading whitespace, test for blank line or comment */ |
| 668 | cp = line + strspn(line, WHITESPACE); |
| 669 | if ((*cp == 0) || (*cp == '#')) |
| 670 | continue; /* done with this line */ |
| 671 | |
| 672 | /* First non-whitespace char should be double quote delimiting */ |
| 673 | /* commandline */ |
| 674 | if (*cp != '"') { |
| 675 | error("bad entropy command, %.100s line %d", cmdfilename, |
| 676 | linenum); |
| 677 | continue; |
| 678 | } |
| 679 | |
| 680 | /* first token, command args (incl. argv[0]) in double quotes */ |
| 681 | cp = strtok(cp, "\""); |
| 682 | if (cp == NULL) { |
| 683 | error("missing or bad command string, %.100s line %d -- ignored", |
| 684 | cmdfilename, linenum); |
| 685 | continue; |
| 686 | } |
| 687 | strlcpy(cmd, cp, sizeof(cmd)); |
| 688 | |
| 689 | /* second token, full command path */ |
| 690 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { |
| 691 | error("missing command path, %.100s line %d -- ignored", |
| 692 | cmdfilename, linenum); |
| 693 | continue; |
| 694 | } |
| 695 | |
| 696 | /* did configure mark this as dead? */ |
| 697 | if (strncmp("undef", cp, 5) == 0) |
| 698 | continue; |
| 699 | |
| 700 | strlcpy(path, cp, sizeof(path)); |
| 701 | |
| 702 | /* third token, entropy rate estimate for this command */ |
| 703 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { |
| 704 | error("missing entropy estimate, %.100s line %d -- ignored", |
| 705 | cmdfilename, linenum); |
| 706 | continue; |
| 707 | } |
| 708 | est = strtod(cp, &argv); |
| 709 | |
| 710 | /* end of line */ |
| 711 | if ((cp = strtok(NULL, WHITESPACE)) != NULL) { |
| 712 | error("garbage at end of line %d in %.100s -- ignored", linenum, |
| 713 | cmdfilename); |
| 714 | continue; |
| 715 | } |
| 716 | |
| 717 | /* save the command for debug messages */ |
| 718 | entcmd[cur_cmd].cmdstring = xstrdup(cmd); |
| 719 | |
| 720 | /* split the command args */ |
| 721 | cp = strtok(cmd, WHITESPACE); |
| 722 | arg = 0; |
| 723 | argv = NULL; |
| 724 | do { |
| 725 | char *s = (char*)xmalloc(strlen(cp) + 1); |
| 726 | strncpy(s, cp, strlen(cp) + 1); |
| 727 | entcmd[cur_cmd].args[arg] = s; |
| 728 | arg++; |
| 729 | } while ((arg < 5) && (cp = strtok(NULL, WHITESPACE))); |
| 730 | |
| 731 | if (strtok(NULL, WHITESPACE)) |
| 732 | error("ignored extra command elements (max 5), %.100s line %d", |
| 733 | cmdfilename, linenum); |
| 734 | |
| 735 | /* Copy the command path and rate estimate */ |
| 736 | entcmd[cur_cmd].path = xstrdup(path); |
| 737 | entcmd[cur_cmd].rate = est; |
| 738 | |
| 739 | /* Initialise other values */ |
| 740 | entcmd[cur_cmd].sticky_badness = 1; |
| 741 | |
| 742 | cur_cmd++; |
| 743 | |
| 744 | /* If we've filled the array, reallocate it twice the size */ |
| 745 | /* Do this now because even if this we're on the last command, |
| 746 | we need another slot to mark the last entry */ |
| 747 | if (cur_cmd == num_cmds) { |
| 748 | num_cmds *= 2; |
| 749 | entcmd = xrealloc(entcmd, num_cmds * sizeof(entropy_source_t)); |
| 750 | } |
| 751 | } |
| 752 | |
| 753 | /* zero the last entry */ |
| 754 | memset(&entcmd[cur_cmd], '\0', sizeof(entropy_source_t)); |
| 755 | |
| 756 | /* trim to size */ |
| 757 | entropy_sources = xrealloc(entcmd, (cur_cmd+1) * sizeof(entropy_source_t)); |
| 758 | |
| 759 | debug("Loaded %d entropy commands from %.100s", cur_cmd, cmdfilename); |
| 760 | |
| 761 | return (cur_cmd >= MIN_ENTROPY_SOURCES); |
| 762 | } |
| 763 | |
| 764 | static void |
| 765 | seed_openssl_rng(void) |
| 766 | { |
| 767 | /* Read in collection commands */ |
| 768 | if (!prng_read_commands(SSH_PRNG_COMMAND_FILE)) |
| 769 | fatal("PRNG initialisation failed -- exiting."); |
| 770 | |
| 771 | prng_read_seedfile(); |
| 772 | |
| 773 | debug("Seeded RNG with %i bytes from programs", |
| 774 | (int)stir_from_programs()); |
| 775 | debug("Seeded RNG with %i bytes from system calls", |
| 776 | (int)stir_from_system()); |
| 777 | |
| 778 | prng_write_seedfile(); |
| 779 | } |
| 780 | |
| 781 | #endif /* USE_PRNGD */ |
| 782 | |
| 783 | int |
| 784 | main(int argc, char **argv) |
| 785 | { |
| 786 | unsigned char buf[48]; |
| 787 | int ret; |
| 788 | |
| 789 | /* XXX: need some debugging mode */ |
| 790 | log_init(argv[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1); |
| 791 | |
| 792 | seed_openssl_rng(); |
| 793 | |
| 794 | if (!RAND_status()) |
| 795 | fatal("Not enough entropy in RNG"); |
| 796 | |
| 797 | RAND_bytes(buf, sizeof(buf)); |
| 798 | |
| 799 | ret = atomicio(write, STDOUT_FILENO, buf, sizeof(buf)); |
| 800 | |
| 801 | memset(buf, '\0', sizeof(buf)); |
| 802 | |
| 803 | return ret == sizeof(buf) ? 0 : 1; |
| 804 | } |
| 805 | |