crypto/mem_sec.c

   1 /*
   2  * Copyright 2015-2018 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 /*
  11  * Copyright 2004-2014, Akamai Technologies. All Rights Reserved.
  12  * This file is distributed under the terms of the OpenSSL license.
  13  */
  14
  15 /*
  16  * This file is in two halves. The first half implements the public API
  17  * to be used by external consumers, and to be used by OpenSSL to store
  18  * data in a "secure arena." The second half implements the secure arena.
  19  * For details on that implementation, see below (look for uppercase
  20  * "SECURE HEAP IMPLEMENTATION").
  21  */
  22 #include <openssl/crypto.h>
  23 #include <e_os.h>
  24
  25 #include <string.h>
  26
  27 /* e_os.h includes unistd.h, which defines _POSIX_VERSION */
  28 #if !defined(OPENSSL_NO_SECURE_MEMORY) && defined(OPENSSL_SYS_UNIX) \
  29     && ( (defined(_POSIX_VERSION) && _POSIX_VERSION >= 200112L) \
  30          || defined(__sun) || defined(__hpux) || defined(__sgi) \
  31          || defined(__osf__) )
  32 # define IMPLEMENTED
  33 # include <stdlib.h>
  34 # include <assert.h>
  35 # include <unistd.h>
  36 # include <sys/types.h>
  37 # include <sys/mman.h>
  38 # include <sys/param.h>
  39 # include <sys/stat.h>
  40 # include <fcntl.h>
  41 #endif
  42
  43 #define CLEAR(p, s) OPENSSL_cleanse(p, s)
  44 #ifndef PAGE_SIZE
  45 # define PAGE_SIZE    4096
  46 #endif
  47 #if !defined(MAP_ANON) && defined(MAP_ANONYMOUS)
  48 # define MAP_ANON MAP_ANONYMOUS
  49 #endif
  50
  51 #ifdef IMPLEMENTED
  52 static size_t secure_mem_used;
  53
  54 static int secure_mem_initialized;
  55
  56 static CRYPTO_RWLOCK *sec_malloc_lock = NULL;
  57
  58 /*
  59  * These are the functions that must be implemented by a secure heap (sh).
  60  */
  61 static int sh_init(size_t size, int minsize);
  62 static char *sh_malloc(size_t size);
  63 static void sh_free(char *ptr);
  64 static void sh_done(void);
  65 static size_t sh_actual_size(char *ptr);
  66 static int sh_allocated(const char *ptr);
  67 #endif
  68
  69 int CRYPTO_secure_malloc_init(size_t size, int minsize)
  70 {
  71 #ifdef IMPLEMENTED
  72     int ret = 0;
  73
  74     if (!secure_mem_initialized) {
  75         sec_malloc_lock = CRYPTO_THREAD_lock_new();
  76         if (sec_malloc_lock == NULL)
  77             return 0;
  78         if ((ret = sh_init(size, minsize)) != 0) {
  79             secure_mem_initialized = 1;
  80         } else {
  81             CRYPTO_THREAD_lock_free(sec_malloc_lock);
  82             sec_malloc_lock = NULL;
  83         }
  84     }
  85
  86     return ret;
  87 #else
  88     return 0;
  89 #endif /* IMPLEMENTED */
  90 }
  91
  92 int CRYPTO_secure_malloc_done()
  93 {
  94 #ifdef IMPLEMENTED
  95     if (secure_mem_used == 0) {
  96         sh_done();
  97         secure_mem_initialized = 0;
  98         CRYPTO_THREAD_lock_free(sec_malloc_lock);
  99         sec_malloc_lock = NULL;
 100         return 1;
 101     }
 102 #endif /* IMPLEMENTED */
 103     return 0;
 104 }
 105
 106 int CRYPTO_secure_malloc_initialized()
 107 {
 108 #ifdef IMPLEMENTED
 109     return secure_mem_initialized;
 110 #else
 111     return 0;
 112 #endif /* IMPLEMENTED */
 113 }
 114
 115 void *CRYPTO_secure_malloc(size_t num, const char *file, int line)
 116 {
 117 #ifdef IMPLEMENTED
 118     void *ret;
 119     size_t actual_size;
 120
 121     if (!secure_mem_initialized) {
 122         return CRYPTO_malloc(num, file, line);
 123     }
 124     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 125     ret = sh_malloc(num);
 126     actual_size = ret ? sh_actual_size(ret) : 0;
 127     secure_mem_used += actual_size;
 128     CRYPTO_THREAD_unlock(sec_malloc_lock);
 129     return ret;
 130 #else
 131     return CRYPTO_malloc(num, file, line);
 132 #endif /* IMPLEMENTED */
 133 }
 134
 135 void *CRYPTO_secure_zalloc(size_t num, const char *file, int line)
 136 {
 137 #ifdef IMPLEMENTED
 138     if (secure_mem_initialized)
 139         /* CRYPTO_secure_malloc() zeroes allocations when it is implemented */
 140         return CRYPTO_secure_malloc(num, file, line);
 141 #endif
 142     return CRYPTO_zalloc(num, file, line);
 143 }
 144
 145 void CRYPTO_secure_free(void *ptr, const char *file, int line)
 146 {
 147 #ifdef IMPLEMENTED
 148     size_t actual_size;
 149
 150     if (ptr == NULL)
 151         return;
 152     if (!CRYPTO_secure_allocated(ptr)) {
 153         CRYPTO_free(ptr, file, line);
 154         return;
 155     }
 156     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 157     actual_size = sh_actual_size(ptr);
 158     CLEAR(ptr, actual_size);
 159     secure_mem_used -= actual_size;
 160     sh_free(ptr);
 161     CRYPTO_THREAD_unlock(sec_malloc_lock);
 162 #else
 163     CRYPTO_free(ptr, file, line);
 164 #endif /* IMPLEMENTED */
 165 }
 166
 167 void CRYPTO_secure_clear_free(void *ptr, size_t num,
 168                               const char *file, int line)
 169 {
 170 #ifdef IMPLEMENTED
 171     size_t actual_size;
 172
 173     if (ptr == NULL)
 174         return;
 175     if (!CRYPTO_secure_allocated(ptr)) {
 176         OPENSSL_cleanse(ptr, num);
 177         CRYPTO_free(ptr, file, line);
 178         return;
 179     }
 180     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 181     actual_size = sh_actual_size(ptr);
 182     CLEAR(ptr, actual_size);
 183     secure_mem_used -= actual_size;
 184     sh_free(ptr);
 185     CRYPTO_THREAD_unlock(sec_malloc_lock);
 186 #else
 187     if (ptr == NULL)
 188         return;
 189     OPENSSL_cleanse(ptr, num);
 190     CRYPTO_free(ptr, file, line);
 191 #endif /* IMPLEMENTED */
 192 }
 193
 194 int CRYPTO_secure_allocated(const void *ptr)
 195 {
 196 #ifdef IMPLEMENTED
 197     int ret;
 198
 199     if (!secure_mem_initialized)
 200         return 0;
 201     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 202     ret = sh_allocated(ptr);
 203     CRYPTO_THREAD_unlock(sec_malloc_lock);
 204     return ret;
 205 #else
 206     return 0;
 207 #endif /* IMPLEMENTED */
 208 }
 209
 210 size_t CRYPTO_secure_used()
 211 {
 212 #ifdef IMPLEMENTED
 213     return secure_mem_used;
 214 #else
 215     return 0;
 216 #endif /* IMPLEMENTED */
 217 }
 218
 219 size_t CRYPTO_secure_actual_size(void *ptr)
 220 {
 221 #ifdef IMPLEMENTED
 222     size_t actual_size;
 223
 224     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 225     actual_size = sh_actual_size(ptr);
 226     CRYPTO_THREAD_unlock(sec_malloc_lock);
 227     return actual_size;
 228 #else
 229     return 0;
 230 #endif
 231 }
 232 /* END OF PAGE ...
 233
 234    ... START OF PAGE */
 235
 236 /*
 237  * SECURE HEAP IMPLEMENTATION
 238  */
 239 #ifdef IMPLEMENTED
 240
 241
 242 /*
 243  * The implementation provided here uses a fixed-sized mmap() heap,
 244  * which is locked into memory, not written to core files, and protected
 245  * on either side by an unmapped page, which will catch pointer overruns
 246  * (or underruns) and an attempt to read data out of the secure heap.
 247  * Free'd memory is zero'd or otherwise cleansed.
 248  *
 249  * This is a pretty standard buddy allocator.  We keep areas in a multiple
 250  * of "sh.minsize" units.  The freelist and bitmaps are kept separately,
 251  * so all (and only) data is kept in the mmap'd heap.
 252  *
 253  * This code assumes eight-bit bytes.  The numbers 3 and 7 are all over the
 254  * place.
 255  */
 256
 257 #define ONE ((size_t)1)
 258
 259 # define TESTBIT(t, b)  (t[(b) >> 3] &  (ONE << ((b) & 7)))
 260 # define SETBIT(t, b)   (t[(b) >> 3] |= (ONE << ((b) & 7)))
 261 # define CLEARBIT(t, b) (t[(b) >> 3] &= (0xFF & ~(ONE << ((b) & 7))))
 262
 263 #define WITHIN_ARENA(p) \
 264     ((char*)(p) >= sh.arena && (char*)(p) < &sh.arena[sh.arena_size])
 265 #define WITHIN_FREELIST(p) \
 266     ((char*)(p) >= (char*)sh.freelist && (char*)(p) < (char*)&sh.freelist[sh.freelist_size])
 267
 268
 269 typedef struct sh_list_st
 270 {
 271     struct sh_list_st *next;
 272     struct sh_list_st **p_next;
 273 } SH_LIST;
 274
 275 typedef struct sh_st
 276 {
 277     char* map_result;
 278     size_t map_size;
 279     char *arena;
 280     size_t arena_size;
 281     char **freelist;
 282     ossl_ssize_t freelist_size;
 283     size_t minsize;
 284     unsigned char *bittable;
 285     unsigned char *bitmalloc;
 286     size_t bittable_size; /* size in bits */
 287 } SH;
 288
 289 static SH sh;
 290
 291 static size_t sh_getlist(char *ptr)
 292 {
 293     ossl_ssize_t list = sh.freelist_size - 1;
 294     size_t bit = (sh.arena_size + ptr - sh.arena) / sh.minsize;
 295
 296     for (; bit; bit >>= 1, list--) {
 297         if (TESTBIT(sh.bittable, bit))
 298             break;
 299         OPENSSL_assert((bit & 1) == 0);
 300     }
 301
 302     return list;
 303 }
 304
 305
 306 static int sh_testbit(char *ptr, int list, unsigned char *table)
 307 {
 308     size_t bit;
 309
 310     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 311     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 312     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 313     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 314     return TESTBIT(table, bit);
 315 }
 316
 317 static void sh_clearbit(char *ptr, int list, unsigned char *table)
 318 {
 319     size_t bit;
 320
 321     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 322     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 323     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 324     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 325     OPENSSL_assert(TESTBIT(table, bit));
 326     CLEARBIT(table, bit);
 327 }
 328
 329 static void sh_setbit(char *ptr, int list, unsigned char *table)
 330 {
 331     size_t bit;
 332
 333     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 334     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 335     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 336     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 337     OPENSSL_assert(!TESTBIT(table, bit));
 338     SETBIT(table, bit);
 339 }
 340
 341 static void sh_add_to_list(char **list, char *ptr)
 342 {
 343     SH_LIST *temp;
 344
 345     OPENSSL_assert(WITHIN_FREELIST(list));
 346     OPENSSL_assert(WITHIN_ARENA(ptr));
 347
 348     temp = (SH_LIST *)ptr;
 349     temp->next = *(SH_LIST **)list;
 350     OPENSSL_assert(temp->next == NULL || WITHIN_ARENA(temp->next));
 351     temp->p_next = (SH_LIST **)list;
 352
 353     if (temp->next != NULL) {
 354         OPENSSL_assert((char **)temp->next->p_next == list);
 355         temp->next->p_next = &(temp->next);
 356     }
 357
 358     *list = ptr;
 359 }
 360
 361 static void sh_remove_from_list(char *ptr)
 362 {
 363     SH_LIST *temp, *temp2;
 364
 365     temp = (SH_LIST *)ptr;
 366     if (temp->next != NULL)
 367         temp->next->p_next = temp->p_next;
 368     *temp->p_next = temp->next;
 369     if (temp->next == NULL)
 370         return;
 371
 372     temp2 = temp->next;
 373     OPENSSL_assert(WITHIN_FREELIST(temp2->p_next) || WITHIN_ARENA(temp2->p_next));
 374 }
 375
 376
 377 static int sh_init(size_t size, int minsize)
 378 {
 379     int ret;
 380     size_t i;
 381     size_t pgsize;
 382     size_t aligned;
 383
 384     memset(&sh, 0, sizeof(sh));
 385
 386     /* make sure size and minsize are powers of 2 */
 387     OPENSSL_assert(size > 0);
 388     OPENSSL_assert((size & (size - 1)) == 0);
 389     OPENSSL_assert(minsize > 0);
 390     OPENSSL_assert((minsize & (minsize - 1)) == 0);
 391     if (size <= 0 || (size & (size - 1)) != 0)
 392         goto err;
 393     if (minsize <= 0 || (minsize & (minsize - 1)) != 0)
 394         goto err;
 395
 396     while (minsize < (int)sizeof(SH_LIST))
 397         minsize *= 2;
 398
 399     sh.arena_size = size;
 400     sh.minsize = minsize;
 401     sh.bittable_size = (sh.arena_size / sh.minsize) * 2;
 402
 403     /* Prevent allocations of size 0 later on */
 404     if (sh.bittable_size >> 3 == 0)
 405         goto err;
 406
 407     sh.freelist_size = -1;
 408     for (i = sh.bittable_size; i; i >>= 1)
 409         sh.freelist_size++;
 410
 411     sh.freelist = OPENSSL_zalloc(sh.freelist_size * sizeof(char *));
 412     OPENSSL_assert(sh.freelist != NULL);
 413     if (sh.freelist == NULL)
 414         goto err;
 415
 416     sh.bittable = OPENSSL_zalloc(sh.bittable_size >> 3);
 417     OPENSSL_assert(sh.bittable != NULL);
 418     if (sh.bittable == NULL)
 419         goto err;
 420
 421     sh.bitmalloc = OPENSSL_zalloc(sh.bittable_size >> 3);
 422     OPENSSL_assert(sh.bitmalloc != NULL);
 423     if (sh.bitmalloc == NULL)
 424         goto err;
 425
 426     /* Allocate space for heap, and two extra pages as guards */
 427 #if defined(_SC_PAGE_SIZE) || defined (_SC_PAGESIZE)
 428     {
 429 # if defined(_SC_PAGE_SIZE)
 430         long tmppgsize = sysconf(_SC_PAGE_SIZE);
 431 # else
 432         long tmppgsize = sysconf(_SC_PAGESIZE);
 433 # endif
 434         if (tmppgsize < 1)
 435             pgsize = PAGE_SIZE;
 436         else
 437             pgsize = (size_t)tmppgsize;
 438     }
 439 #else
 440     pgsize = PAGE_SIZE;
 441 #endif
 442     sh.map_size = pgsize + sh.arena_size + pgsize;
 443     if (1) {
 444 #ifdef MAP_ANON
 445         sh.map_result = mmap(NULL, sh.map_size,
 446                              PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
 447     } else {
 448 #endif
 449         int fd;
 450
 451         sh.map_result = MAP_FAILED;
 452         if ((fd = open("/dev/zero", O_RDWR)) >= 0) {
 453             sh.map_result = mmap(NULL, sh.map_size,
 454                                  PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
 455             close(fd);
 456         }
 457     }
 458     if (sh.map_result == MAP_FAILED)
 459         goto err;
 460     sh.arena = (char *)(sh.map_result + pgsize);
 461     sh_setbit(sh.arena, 0, sh.bittable);
 462     sh_add_to_list(&sh.freelist[0], sh.arena);
 463
 464     /* Now try to add guard pages and lock into memory. */
 465     ret = 1;
 466
 467     /* Starting guard is already aligned from mmap. */
 468     if (mprotect(sh.map_result, pgsize, PROT_NONE) < 0)
 469         ret = 2;
 470
 471     /* Ending guard page - need to round up to page boundary */
 472     aligned = (pgsize + sh.arena_size + (pgsize - 1)) & ~(pgsize - 1);
 473     if (mprotect(sh.map_result + aligned, pgsize, PROT_NONE) < 0)
 474         ret = 2;
 475
 476     if (mlock(sh.arena, sh.arena_size) < 0)
 477         ret = 2;
 478 #ifdef MADV_DONTDUMP
 479     if (madvise(sh.arena, sh.arena_size, MADV_DONTDUMP) < 0)
 480         ret = 2;
 481 #endif
 482
 483     return ret;
 484
 485  err:
 486     sh_done();
 487     return 0;
 488 }
 489
 490 static void sh_done()
 491 {
 492     OPENSSL_free(sh.freelist);
 493     OPENSSL_free(sh.bittable);
 494     OPENSSL_free(sh.bitmalloc);
 495     if (sh.map_result != NULL && sh.map_size)
 496         munmap(sh.map_result, sh.map_size);
 497     memset(&sh, 0, sizeof(sh));
 498 }
 499
 500 static int sh_allocated(const char *ptr)
 501 {
 502     return WITHIN_ARENA(ptr) ? 1 : 0;
 503 }
 504
 505 static char *sh_find_my_buddy(char *ptr, int list)
 506 {
 507     size_t bit;
 508     char *chunk = NULL;
 509
 510     bit = (ONE << list) + (ptr - sh.arena) / (sh.arena_size >> list);
 511     bit ^= 1;
 512
 513     if (TESTBIT(sh.bittable, bit) && !TESTBIT(sh.bitmalloc, bit))
 514         chunk = sh.arena + ((bit & ((ONE << list) - 1)) * (sh.arena_size >> list));
 515
 516     return chunk;
 517 }
 518
 519 static char *sh_malloc(size_t size)
 520 {
 521     ossl_ssize_t list, slist;
 522     size_t i;
 523     char *chunk;
 524
 525     if (size > sh.arena_size)
 526         return NULL;
 527
 528     list = sh.freelist_size - 1;
 529     for (i = sh.minsize; i < size; i <<= 1)
 530         list--;
 531     if (list < 0)
 532         return NULL;
 533
 534     /* try to find a larger entry to split */
 535     for (slist = list; slist >= 0; slist--)
 536         if (sh.freelist[slist] != NULL)
 537             break;
 538     if (slist < 0)
 539         return NULL;
 540
 541     /* split larger entry */
 542     while (slist != list) {
 543         char *temp = sh.freelist[slist];
 544
 545         /* remove from bigger list */
 546         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 547         sh_clearbit(temp, slist, sh.bittable);
 548         sh_remove_from_list(temp);
 549         OPENSSL_assert(temp != sh.freelist[slist]);
 550
 551         /* done with bigger list */
 552         slist++;
 553
 554         /* add to smaller list */
 555         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 556         sh_setbit(temp, slist, sh.bittable);
 557         sh_add_to_list(&sh.freelist[slist], temp);
 558         OPENSSL_assert(sh.freelist[slist] == temp);
 559
 560         /* split in 2 */
 561         temp += sh.arena_size >> slist;
 562         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 563         sh_setbit(temp, slist, sh.bittable);
 564         sh_add_to_list(&sh.freelist[slist], temp);
 565         OPENSSL_assert(sh.freelist[slist] == temp);
 566
 567         OPENSSL_assert(temp-(sh.arena_size >> slist) == sh_find_my_buddy(temp, slist));
 568     }
 569
 570     /* peel off memory to hand back */
 571     chunk = sh.freelist[list];
 572     OPENSSL_assert(sh_testbit(chunk, list, sh.bittable));
 573     sh_setbit(chunk, list, sh.bitmalloc);
 574     sh_remove_from_list(chunk);
 575
 576     OPENSSL_assert(WITHIN_ARENA(chunk));
 577
 578     /* zero the free list header as a precaution against information leakage */
 579     memset(chunk, 0, sizeof(SH_LIST));
 580
 581     return chunk;
 582 }
 583
 584 static void sh_free(char *ptr)
 585 {
 586     size_t list;
 587     char *buddy;
 588
 589     if (ptr == NULL)
 590         return;
 591     OPENSSL_assert(WITHIN_ARENA(ptr));
 592     if (!WITHIN_ARENA(ptr))
 593         return;
 594
 595     list = sh_getlist(ptr);
 596     OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
 597     sh_clearbit(ptr, list, sh.bitmalloc);
 598     sh_add_to_list(&sh.freelist[list], ptr);
 599
 600     /* Try to coalesce two adjacent free areas. */
 601     while ((buddy = sh_find_my_buddy(ptr, list)) != NULL) {
 602         OPENSSL_assert(ptr == sh_find_my_buddy(buddy, list));
 603         OPENSSL_assert(ptr != NULL);
 604         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 605         sh_clearbit(ptr, list, sh.bittable);
 606         sh_remove_from_list(ptr);
 607         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 608         sh_clearbit(buddy, list, sh.bittable);
 609         sh_remove_from_list(buddy);
 610
 611         list--;
 612
 613         /* Zero the higher addressed block's free list pointers */
 614         memset(ptr > buddy ? ptr : buddy, 0, sizeof(SH_LIST));
 615         if (ptr > buddy)
 616             ptr = buddy;
 617
 618         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 619         sh_setbit(ptr, list, sh.bittable);
 620         sh_add_to_list(&sh.freelist[list], ptr);
 621         OPENSSL_assert(sh.freelist[list] == ptr);
 622     }
 623 }
 624
 625 static size_t sh_actual_size(char *ptr)
 626 {
 627     int list;
 628
 629     OPENSSL_assert(WITHIN_ARENA(ptr));
 630     if (!WITHIN_ARENA(ptr))
 631         return 0;
 632     list = sh_getlist(ptr);
 633     OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
 634     return sh.arena_size / (ONE << list);
 635 }
 636 #endif /* IMPLEMENTED */