contrib/bind-9.3/lib/isc/unix/entropy.c

   1 /*
   2  * Copyright (C) 2004-2006  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 2000-2003  Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  10  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  11  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  12  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  13  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  14  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  15  * PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 /* $Id: entropy.c,v 1.60.2.3.8.14 2006/03/02 23:29:17 marka Exp $ */
  19
  20 /*
  21  * This is the system depenedent part of the ISC entropy API.
  22  */
  23
  24 #include <config.h>
  25
  26 #include <sys/param.h>  /* Openserver 5.0.6A and FD_SETSIZE */
  27 #include <sys/types.h>
  28 #include <sys/time.h>
  29 #include <sys/stat.h>
  30 #include <sys/socket.h>
  31 #include <sys/un.h>
  32
  33 #include <unistd.h>
  34
  35 #include <isc/platform.h>
  36 #include <isc/strerror.h>
  37
  38 #ifdef ISC_PLATFORM_NEEDSYSSELECTH
  39 #include <sys/select.h>
  40 #endif
  41
  42 #include "errno2result.h"
  43
  44 /*
  45  * There is only one variable in the entropy data structures that is not
  46  * system independent, but pulling the structure that uses it into this file
  47  * ultimately means pulling several other independent structures here also to
  48  * resolve their interdependencies.  Thus only the problem variable's type
  49  * is defined here.
  50  */
  51 #define FILESOURCE_HANDLE_TYPE  int
  52
  53 typedef struct {
  54         int     handle;
  55         enum    {
  56                 isc_usocketsource_disconnected,
  57                 isc_usocketsource_connecting,
  58                 isc_usocketsource_connected,
  59                 isc_usocketsource_ndesired,
  60                 isc_usocketsource_wrote,
  61                 isc_usocketsource_reading
  62         } status;
  63         size_t  sz_to_recv;
  64 } isc_entropyusocketsource_t;
  65
  66 #include "../entropy.c"
  67
  68 static unsigned int
  69 get_from_filesource(isc_entropysource_t *source, isc_uint32_t desired) {
  70         isc_entropy_t *ent = source->ent;
  71         unsigned char buf[128];
  72         int fd = source->sources.file.handle;
  73         ssize_t n, ndesired;
  74         unsigned int added;
  75
  76         if (source->bad)
  77                 return (0);
  78
  79         desired = desired / 8 + (((desired & 0x07) > 0) ? 1 : 0);
  80
  81         added = 0;
  82         while (desired > 0) {
  83                 ndesired = ISC_MIN(desired, sizeof(buf));
  84                 n = read(fd, buf, ndesired);
  85                 if (n < 0) {
  86                         if (errno == EAGAIN || errno == EINTR)
  87                                 goto out;
  88                         goto err;
  89                 }
  90                 if (n == 0)
  91                         goto err;
  92
  93                 entropypool_adddata(ent, buf, n, n * 8);
  94                 added += n * 8;
  95                 desired -= n;
  96         }
  97         goto out;
  98
  99  err:
 100         (void)close(fd);
 101         source->sources.file.handle = -1;
 102         source->bad = ISC_TRUE;
 103
 104  out:
 105         return (added);
 106 }
 107
 108 static unsigned int
 109 get_from_usocketsource(isc_entropysource_t *source, isc_uint32_t desired) {
 110         isc_entropy_t *ent = source->ent;
 111         unsigned char buf[128];
 112         int fd = source->sources.usocket.handle;
 113         ssize_t n = 0, ndesired;
 114         unsigned int added;
 115         size_t sz_to_recv = source->sources.usocket.sz_to_recv;
 116
 117         if (source->bad)
 118                 return (0);
 119
 120         desired = desired / 8 + (((desired & 0x07) > 0) ? 1 : 0);
 121
 122         added = 0;
 123         while (desired > 0) {
 124                 ndesired = ISC_MIN(desired, sizeof(buf));
 125  eagain_loop:
 126
 127                 switch ( source->sources.usocket.status ) {
 128                 case isc_usocketsource_ndesired:
 129                         buf[0] = ndesired;
 130                         if ((n = sendto(fd, buf, 1, 0, NULL, 0)) < 0) {
 131                                 if (errno == EWOULDBLOCK || errno == EINTR ||
 132                                     errno == ECONNRESET)
 133                                         goto out;
 134                                 goto err;
 135                         }
 136                         INSIST(n == 1);
 137                         source->sources.usocket.status =
 138                                                 isc_usocketsource_wrote;
 139                         goto eagain_loop;
 140
 141                 case isc_usocketsource_connecting:
 142                 case isc_usocketsource_connected:
 143                         buf[0] = 1;
 144                         buf[1] = ndesired;
 145                         if ((n = sendto(fd, buf, 2, 0, NULL, 0)) < 0) {
 146                                 if (errno == EWOULDBLOCK || errno == EINTR ||
 147                                     errno == ECONNRESET)
 148                                         goto out;
 149                                 goto err;
 150                         }
 151                         if (n == 1) {
 152                                 source->sources.usocket.status =
 153                                         isc_usocketsource_ndesired;
 154                                 goto eagain_loop;
 155                         }
 156                         INSIST(n == 2);
 157                         source->sources.usocket.status =
 158                                                 isc_usocketsource_wrote;
 159                         /*FALLTHROUGH*/
 160
 161                 case isc_usocketsource_wrote:
 162                         if (recvfrom(fd, buf, 1, 0, NULL, NULL) != 1) {
 163                                 if (errno == EAGAIN) {
 164                                         /*
 165                                          * The problem of EAGAIN (try again
 166                                          * later) is a major issue on HP-UX.
 167                                          * Solaris actually tries the recvfrom
 168                                          * call again, while HP-UX just dies.
 169                                          * This code is an attempt to let the
 170                                          * entropy pool fill back up (at least
 171                                          * that's what I think the problem is.)
 172                                          * We go to eagain_loop because if we
 173                                          * just "break", then the "desired"
 174                                          * amount gets borked.
 175                                          */
 176                                         usleep(1000);
 177                                         goto eagain_loop;
 178                                 }
 179                                 if (errno == EWOULDBLOCK || errno == EINTR)
 180                                         goto out;
 181                                 goto err;
 182                         }
 183                         source->sources.usocket.status =
 184                                         isc_usocketsource_reading;
 185                         sz_to_recv = buf[0];
 186                         source->sources.usocket.sz_to_recv = sz_to_recv;
 187                         if (sz_to_recv > sizeof(buf))
 188                                 goto err;
 189                         /*FALLTHROUGH*/
 190
 191                 case isc_usocketsource_reading:
 192                         if (sz_to_recv != 0U) {
 193                                 n = recv(fd, buf, sz_to_recv, 0);
 194                                 if (n < 0) {
 195                                         if (errno == EWOULDBLOCK ||
 196                                             errno == EINTR)
 197                                                 goto out;
 198                                         goto err;
 199                                 }
 200                         } else
 201                                 n = 0;
 202                         break;
 203
 204                 default:
 205                         goto err;
 206                 }
 207
 208                 if ((size_t)n != sz_to_recv)
 209                         source->sources.usocket.sz_to_recv -= n;
 210                 else
 211                         source->sources.usocket.status =
 212                                 isc_usocketsource_connected;
 213
 214                 if (n == 0)
 215                         goto out;
 216
 217                 entropypool_adddata(ent, buf, n, n * 8);
 218                 added += n * 8;
 219                 desired -= n;
 220         }
 221         goto out;
 222
 223  err:
 224         close(fd);
 225         source->bad = ISC_TRUE;
 226         source->sources.usocket.status = isc_usocketsource_disconnected;
 227         source->sources.usocket.handle = -1;
 228
 229  out:
 230         return (added);
 231 }
 232
 233 /*
 234  * Poll each source, trying to get data from it to stuff into the entropy
 235  * pool.
 236  */
 237 static void
 238 fillpool(isc_entropy_t *ent, unsigned int desired, isc_boolean_t blocking) {
 239         unsigned int added;
 240         unsigned int remaining;
 241         unsigned int needed;
 242         unsigned int nsource;
 243         isc_entropysource_t *source;
 244
 245         REQUIRE(VALID_ENTROPY(ent));
 246
 247         needed = desired;
 248
 249         /*
 250          * This logic is a little strange, so an explanation is in order.
 251          *
 252          * If needed is 0, it means we are being asked to "fill to whatever
 253          * we think is best."  This means that if we have at least a
 254          * partially full pool (say, > 1/4th of the pool) we probably don't
 255          * need to add anything.
 256          *
 257          * Also, we will check to see if the "pseudo" count is too high.
 258          * If it is, try to mix in better data.  Too high is currently
 259          * defined as 1/4th of the pool.
 260          *
 261          * Next, if we are asked to add a specific bit of entropy, make
 262          * certain that we will do so.  Clamp how much we try to add to
 263          * (DIGEST_SIZE * 8 < needed < POOLBITS - entropy).
 264          *
 265          * Note that if we are in a blocking mode, we will only try to
 266          * get as much data as we need, not as much as we might want
 267          * to build up.
 268          */
 269         if (needed == 0) {
 270                 REQUIRE(!blocking);
 271
 272                 if ((ent->pool.entropy >= RND_POOLBITS / 4)
 273                     && (ent->pool.pseudo <= RND_POOLBITS / 4))
 274                         return;
 275
 276                 needed = THRESHOLD_BITS * 4;
 277         } else {
 278                 needed = ISC_MAX(needed, THRESHOLD_BITS);
 279                 needed = ISC_MIN(needed, RND_POOLBITS);
 280         }
 281
 282         /*
 283          * In any case, clamp how much we need to how much we can add.
 284          */
 285         needed = ISC_MIN(needed, RND_POOLBITS - ent->pool.entropy);
 286
 287         /*
 288          * But wait!  If we're not yet initialized, we need at least
 289          *      THRESHOLD_BITS
 290          * of randomness.
 291          */
 292         if (ent->initialized < THRESHOLD_BITS)
 293                 needed = ISC_MAX(needed, THRESHOLD_BITS - ent->initialized);
 294
 295         /*
 296          * Poll each file source to see if we can read anything useful from
 297          * it.  XXXMLG When where are multiple sources, we should keep a
 298          * record of which one we last used so we can start from it (or the
 299          * next one) to avoid letting some sources build up entropy while
 300          * others are always drained.
 301          */
 302
 303         added = 0;
 304         remaining = needed;
 305         if (ent->nextsource == NULL) {
 306                 ent->nextsource = ISC_LIST_HEAD(ent->sources);
 307                 if (ent->nextsource == NULL)
 308                         return;
 309         }
 310         source = ent->nextsource;
 311  again_file:
 312         for (nsource = 0; nsource < ent->nsources; nsource++) {
 313                 unsigned int got;
 314
 315                 if (remaining == 0)
 316                         break;
 317
 318                 got = 0;
 319
 320                 switch ( source->type ) {
 321                 case ENTROPY_SOURCETYPE_FILE:
 322                         got = get_from_filesource(source, remaining);
 323                         break;
 324
 325                 case ENTROPY_SOURCETYPE_USOCKET:
 326                         got = get_from_usocketsource(source, remaining);
 327                         break;
 328                 }
 329
 330                 added += got;
 331
 332                 remaining -= ISC_MIN(remaining, got);
 333
 334                 source = ISC_LIST_NEXT(source, link);
 335                 if (source == NULL)
 336                         source = ISC_LIST_HEAD(ent->sources);
 337         }
 338         ent->nextsource = source;
 339
 340         if (blocking && remaining != 0) {
 341                 int fds;
 342
 343                 fds = wait_for_sources(ent);
 344                 if (fds > 0)
 345                         goto again_file;
 346         }
 347
 348         /*
 349          * Here, if there are bits remaining to be had and we can block,
 350          * check to see if we have a callback source.  If so, call them.
 351          */
 352         source = ISC_LIST_HEAD(ent->sources);
 353         while ((remaining != 0) && (source != NULL)) {
 354                 unsigned int got;
 355
 356                 got = 0;
 357
 358                 if (source->type == ENTROPY_SOURCETYPE_CALLBACK)
 359                         got = get_from_callback(source, remaining, blocking);
 360
 361                 added += got;
 362                 remaining -= ISC_MIN(remaining, got);
 363
 364                 if (added >= needed)
 365                         break;
 366
 367                 source = ISC_LIST_NEXT(source, link);
 368         }
 369
 370         /*
 371          * Mark as initialized if we've added enough data.
 372          */
 373         if (ent->initialized < THRESHOLD_BITS)
 374                 ent->initialized += added;
 375 }
 376
 377 static int
 378 wait_for_sources(isc_entropy_t *ent) {
 379         isc_entropysource_t *source;
 380         int maxfd, fd;
 381         int cc;
 382         fd_set reads;
 383         fd_set writes;
 384
 385         maxfd = -1;
 386         FD_ZERO(&reads);
 387         FD_ZERO(&writes);
 388
 389         source = ISC_LIST_HEAD(ent->sources);
 390         while (source != NULL) {
 391                 if (source->type == ENTROPY_SOURCETYPE_FILE) {
 392                         fd = source->sources.file.handle;
 393                         if (fd >= 0) {
 394                                 maxfd = ISC_MAX(maxfd, fd);
 395                                 FD_SET(fd, &reads);
 396                         }
 397                 }
 398                 if (source->type == ENTROPY_SOURCETYPE_USOCKET) {
 399                         fd = source->sources.usocket.handle;
 400                         if (fd >= 0) {
 401                                 switch (source->sources.usocket.status) {
 402                                 case isc_usocketsource_disconnected:
 403                                         break;
 404                                 case isc_usocketsource_connecting:
 405                                 case isc_usocketsource_connected:
 406                                 case isc_usocketsource_ndesired:
 407                                         maxfd = ISC_MAX(maxfd, fd);
 408                                         FD_SET(fd, &writes);
 409                                         break;
 410                                 case isc_usocketsource_wrote:
 411                                 case isc_usocketsource_reading:
 412                                         maxfd = ISC_MAX(maxfd, fd);
 413                                         FD_SET(fd, &reads);
 414                                         break;
 415                                 }
 416                         }
 417                 }
 418                 source = ISC_LIST_NEXT(source, link);
 419         }
 420
 421         if (maxfd < 0)
 422                 return (-1);
 423
 424         cc = select(maxfd + 1, &reads, &writes, NULL, NULL);
 425         if (cc < 0)
 426                 return (-1);
 427
 428         return (cc);
 429 }
 430
 431 static void
 432 destroyfilesource(isc_entropyfilesource_t *source) {
 433         (void)close(source->handle);
 434 }
 435
 436 static void
 437 destroyusocketsource(isc_entropyusocketsource_t *source) {
 438         close(source->handle);
 439 }
 440
 441 /*
 442  * Make a fd non-blocking
 443  */
 444 static isc_result_t
 445 make_nonblock(int fd) {
 446         int ret;
 447         int flags;
 448         char strbuf[ISC_STRERRORSIZE];
 449 #ifdef USE_FIONBIO_IOCTL
 450         int on = 1;
 451
 452         ret = ioctl(fd, FIONBIO, (char *)&on);
 453 #else
 454         flags = fcntl(fd, F_GETFL, 0);
 455         flags |= PORT_NONBLOCK;
 456         ret = fcntl(fd, F_SETFL, flags);
 457 #endif
 458
 459         if (ret == -1) {
 460                 isc__strerror(errno, strbuf, sizeof(strbuf));
 461                 UNEXPECTED_ERROR(__FILE__, __LINE__,
 462 #ifdef USE_FIONBIO_IOCTL
 463                                  "ioctl(%d, FIONBIO, &on): %s", fd,
 464 #else
 465                                  "fcntl(%d, F_SETFL, %d): %s", fd, flags,
 466 #endif
 467                                  strbuf);
 468
 469                 return (ISC_R_UNEXPECTED);
 470         }
 471
 472         return (ISC_R_SUCCESS);
 473 }
 474
 475 isc_result_t
 476 isc_entropy_createfilesource(isc_entropy_t *ent, const char *fname) {
 477         int fd;
 478         struct stat _stat;
 479         isc_boolean_t is_usocket = ISC_FALSE;
 480         isc_boolean_t is_connected = ISC_FALSE;
 481         isc_result_t ret;
 482         isc_entropysource_t *source;
 483
 484         REQUIRE(VALID_ENTROPY(ent));
 485         REQUIRE(fname != NULL);
 486
 487         LOCK(&ent->lock);
 488
 489         source = NULL;
 490
 491         if (stat(fname, &_stat) < 0) {
 492                 ret = isc__errno2result(errno);
 493                 goto errout;
 494         }
 495         /*
 496          * Solaris 2.5.1 does not have support for sockets (S_IFSOCK),
 497          * but it does return type S_IFIFO (the OS believes that
 498          * the socket is a fifo).  This may be an issue if we tell
 499          * the program to look at an actual FIFO as its source of
 500          * entropy.
 501          */
 502 #if defined(S_ISSOCK)
 503         if (S_ISSOCK(_stat.st_mode))
 504                 is_usocket = ISC_TRUE;
 505 #endif
 506 #if defined(S_ISFIFO) && defined(sun)
 507         if (S_ISFIFO(_stat.st_mode))
 508                 is_usocket = ISC_TRUE;
 509 #endif
 510         if (is_usocket)
 511                 fd = socket(PF_UNIX, SOCK_STREAM, 0);
 512         else
 513                 fd = open(fname, O_RDONLY | PORT_NONBLOCK, 0);
 514
 515         if (fd < 0) {
 516                 ret = isc__errno2result(errno);
 517                 goto errout;
 518         }
 519
 520         ret = make_nonblock(fd);
 521         if (ret != ISC_R_SUCCESS)
 522                 goto closefd;
 523
 524         if (is_usocket) {
 525                 struct sockaddr_un sname;
 526
 527                 memset(&sname, 0, sizeof(sname));
 528                 sname.sun_family = AF_UNIX;
 529                 strncpy(sname.sun_path, fname, sizeof(sname.sun_path));
 530                 sname.sun_path[sizeof(sname.sun_path)-1] = '0';
 531 #ifdef ISC_PLATFORM_HAVESALEN
 532 #if !defined(SUN_LEN)
 533 #define SUN_LEN(su) \
 534         (sizeof(*(su)) - sizeof((su)->sun_path) + strlen((su)->sun_path))
 535 #endif
 536                 sname.sun_len = SUN_LEN(&sname);
 537 #endif
 538
 539                 if (connect(fd, (struct sockaddr *) &sname,
 540                             sizeof(struct sockaddr_un)) < 0) {
 541                         if (errno != EINPROGRESS) {
 542                                 ret = isc__errno2result(errno);
 543                                 goto closefd;
 544                         }
 545                 } else
 546                         is_connected = ISC_TRUE;
 547         }
 548
 549         source = isc_mem_get(ent->mctx, sizeof(isc_entropysource_t));
 550         if (source == NULL) {
 551                 ret = ISC_R_NOMEMORY;
 552                 goto closefd;
 553         }
 554
 555         /*
 556          * From here down, no failures can occur.
 557          */
 558         source->magic = SOURCE_MAGIC;
 559         source->ent = ent;
 560         source->total = 0;
 561         source->bad = ISC_FALSE;
 562         memset(source->name, 0, sizeof(source->name));
 563         ISC_LINK_INIT(source, link);
 564         if (is_usocket) {
 565                 source->sources.usocket.handle = fd;
 566                 if (is_connected)
 567                         source->sources.usocket.status =
 568                                         isc_usocketsource_connected;
 569                 else
 570                         source->sources.usocket.status =
 571                                         isc_usocketsource_connecting;
 572                 source->sources.usocket.sz_to_recv = 0;
 573                 source->type = ENTROPY_SOURCETYPE_USOCKET;
 574         } else {
 575                 source->sources.file.handle = fd;
 576                 source->type = ENTROPY_SOURCETYPE_FILE;
 577         }
 578
 579         /*
 580          * Hook it into the entropy system.
 581          */
 582         ISC_LIST_APPEND(ent->sources, source, link);
 583         ent->nsources++;
 584
 585         UNLOCK(&ent->lock);
 586         return (ISC_R_SUCCESS);
 587
 588  closefd:
 589         (void)close(fd);
 590
 591  errout:
 592         if (source != NULL)
 593                 isc_mem_put(ent->mctx, source, sizeof(isc_entropysource_t));
 594
 595         UNLOCK(&ent->lock);
 596
 597         return (ret);
 598 }