crypto/mem_sec.c

   1 /*
   2  * Copyright 2015-2017 The OpenSSL Project Authors. All Rights Reserved.
   3  * Copyright 2004-2014, Akamai Technologies. All Rights Reserved.
   4  *
   5  * Licensed under the OpenSSL license (the "License").  You may not use
   6  * this file except in compliance with the License.  You can obtain a copy
   7  * in the file LICENSE in the source distribution or at
   8  * https://www.openssl.org/source/license.html
   9  */
  10
  11 /*
  12  * This file is in two halves. The first half implements the public API
  13  * to be used by external consumers, and to be used by OpenSSL to store
  14  * data in a "secure arena." The second half implements the secure arena.
  15  * For details on that implementation, see below (look for uppercase
  16  * "SECURE HEAP IMPLEMENTATION").
  17  */
  18 #include <openssl/crypto.h>
  19 #include <e_os.h>
  20
  21 #include <string.h>
  22
  23 #if defined(OPENSSL_SYS_LINUX) || defined(OPENSSL_SYS_UNIX)
  24 # define IMPLEMENTED
  25 # include <stdlib.h>
  26 # include <assert.h>
  27 # include <unistd.h>
  28 # include <sys/types.h>
  29 # include <sys/mman.h>
  30 # if defined(OPENSSL_SYS_LINUX)
  31 #  include <sys/syscall.h>
  32 #  include <linux/mman.h>
  33 #  include <errno.h>
  34 # endif
  35 # include <sys/param.h>
  36 # include <sys/stat.h>
  37 # include <fcntl.h>
  38 #endif
  39
  40 #define CLEAR(p, s) OPENSSL_cleanse(p, s)
  41 #ifndef PAGE_SIZE
  42 # define PAGE_SIZE    4096
  43 #endif
  44
  45 #ifdef IMPLEMENTED
  46 static size_t secure_mem_used;
  47
  48 static int secure_mem_initialized;
  49
  50 static CRYPTO_RWLOCK *sec_malloc_lock = NULL;
  51
  52 /*
  53  * These are the functions that must be implemented by a secure heap (sh).
  54  */
  55 static int sh_init(size_t size, int minsize);
  56 static void *sh_malloc(size_t size);
  57 static void sh_free(void *ptr);
  58 static void sh_done(void);
  59 static size_t sh_actual_size(char *ptr);
  60 static int sh_allocated(const char *ptr);
  61 #endif
  62
  63 int CRYPTO_secure_malloc_init(size_t size, int minsize)
  64 {
  65 #ifdef IMPLEMENTED
  66     int ret = 0;
  67
  68     if (!secure_mem_initialized) {
  69         sec_malloc_lock = CRYPTO_THREAD_lock_new();
  70         if (sec_malloc_lock == NULL)
  71             return 0;
  72         if ((ret = sh_init(size, minsize)) != 0) {
  73             secure_mem_initialized = 1;
  74         } else {
  75             CRYPTO_THREAD_lock_free(sec_malloc_lock);
  76             sec_malloc_lock = NULL;
  77         }
  78     }
  79
  80     return ret;
  81 #else
  82     return 0;
  83 #endif /* IMPLEMENTED */
  84 }
  85
  86 int CRYPTO_secure_malloc_done()
  87 {
  88 #ifdef IMPLEMENTED
  89     if (secure_mem_used == 0) {
  90         sh_done();
  91         secure_mem_initialized = 0;
  92         CRYPTO_THREAD_lock_free(sec_malloc_lock);
  93         sec_malloc_lock = NULL;
  94         return 1;
  95     }
  96 #endif /* IMPLEMENTED */
  97     return 0;
  98 }
  99
 100 int CRYPTO_secure_malloc_initialized()
 101 {
 102 #ifdef IMPLEMENTED
 103     return secure_mem_initialized;
 104 #else
 105     return 0;
 106 #endif /* IMPLEMENTED */
 107 }
 108
 109 void *CRYPTO_secure_malloc(size_t num, const char *file, int line)
 110 {
 111 #ifdef IMPLEMENTED
 112     void *ret;
 113     size_t actual_size;
 114
 115     if (!secure_mem_initialized) {
 116         return CRYPTO_malloc(num, file, line);
 117     }
 118     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 119     ret = sh_malloc(num);
 120     actual_size = ret ? sh_actual_size(ret) : 0;
 121     secure_mem_used += actual_size;
 122     CRYPTO_THREAD_unlock(sec_malloc_lock);
 123     return ret;
 124 #else
 125     return CRYPTO_malloc(num, file, line);
 126 #endif /* IMPLEMENTED */
 127 }
 128
 129 void *CRYPTO_secure_zalloc(size_t num, const char *file, int line)
 130 {
 131     void *ret = CRYPTO_secure_malloc(num, file, line);
 132
 133     if (ret != NULL)
 134         memset(ret, 0, num);
 135     return ret;
 136 }
 137
 138 void CRYPTO_secure_free(void *ptr, const char *file, int line)
 139 {
 140 #ifdef IMPLEMENTED
 141     size_t actual_size;
 142
 143     if (ptr == NULL)
 144         return;
 145     if (!CRYPTO_secure_allocated(ptr)) {
 146         CRYPTO_free(ptr, file, line);
 147         return;
 148     }
 149     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 150     actual_size = sh_actual_size(ptr);
 151     CLEAR(ptr, actual_size);
 152     secure_mem_used -= actual_size;
 153     sh_free(ptr);
 154     CRYPTO_THREAD_unlock(sec_malloc_lock);
 155 #else
 156     CRYPTO_free(ptr, file, line);
 157 #endif /* IMPLEMENTED */
 158 }
 159
 160 void CRYPTO_secure_clear_free(void *ptr, size_t num,
 161                               const char *file, int line)
 162 {
 163 #ifdef IMPLEMENTED
 164     size_t actual_size;
 165
 166     if (ptr == NULL)
 167         return;
 168     if (!CRYPTO_secure_allocated(ptr)) {
 169         OPENSSL_cleanse(ptr, num);
 170         CRYPTO_free(ptr, file, line);
 171         return;
 172     }
 173     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 174     actual_size = sh_actual_size(ptr);
 175     CLEAR(ptr, actual_size);
 176     secure_mem_used -= actual_size;
 177     sh_free(ptr);
 178     CRYPTO_THREAD_unlock(sec_malloc_lock);
 179 #else
 180     if (ptr == NULL)
 181         return;
 182     OPENSSL_cleanse(ptr, num);
 183     CRYPTO_free(ptr, file, line);
 184 #endif /* IMPLEMENTED */
 185 }
 186
 187 int CRYPTO_secure_allocated(const void *ptr)
 188 {
 189 #ifdef IMPLEMENTED
 190     int ret;
 191
 192     if (!secure_mem_initialized)
 193         return 0;
 194     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 195     ret = sh_allocated(ptr);
 196     CRYPTO_THREAD_unlock(sec_malloc_lock);
 197     return ret;
 198 #else
 199     return 0;
 200 #endif /* IMPLEMENTED */
 201 }
 202
 203 size_t CRYPTO_secure_used()
 204 {
 205 #ifdef IMPLEMENTED
 206     return secure_mem_used;
 207 #else
 208     return 0;
 209 #endif /* IMPLEMENTED */
 210 }
 211
 212 size_t CRYPTO_secure_actual_size(void *ptr)
 213 {
 214 #ifdef IMPLEMENTED
 215     size_t actual_size;
 216
 217     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 218     actual_size = sh_actual_size(ptr);
 219     CRYPTO_THREAD_unlock(sec_malloc_lock);
 220     return actual_size;
 221 #else
 222     return 0;
 223 #endif
 224 }
 225 /* END OF PAGE ...
 226
 227    ... START OF PAGE */
 228
 229 /*
 230  * SECURE HEAP IMPLEMENTATION
 231  */
 232 #ifdef IMPLEMENTED
 233
 234
 235 /*
 236  * The implementation provided here uses a fixed-sized mmap() heap,
 237  * which is locked into memory, not written to core files, and protected
 238  * on either side by an unmapped page, which will catch pointer overruns
 239  * (or underruns) and an attempt to read data out of the secure heap.
 240  * Free'd memory is zero'd or otherwise cleansed.
 241  *
 242  * This is a pretty standard buddy allocator.  We keep areas in a multiple
 243  * of "sh.minsize" units.  The freelist and bitmaps are kept separately,
 244  * so all (and only) data is kept in the mmap'd heap.
 245  *
 246  * This code assumes eight-bit bytes.  The numbers 3 and 7 are all over the
 247  * place.
 248  */
 249
 250 #define ONE ((size_t)1)
 251
 252 # define TESTBIT(t, b)  (t[(b) >> 3] &  (ONE << ((b) & 7)))
 253 # define SETBIT(t, b)   (t[(b) >> 3] |= (ONE << ((b) & 7)))
 254 # define CLEARBIT(t, b) (t[(b) >> 3] &= (0xFF & ~(ONE << ((b) & 7))))
 255
 256 #define WITHIN_ARENA(p) \
 257     ((char*)(p) >= sh.arena && (char*)(p) < &sh.arena[sh.arena_size])
 258 #define WITHIN_FREELIST(p) \
 259     ((char*)(p) >= (char*)sh.freelist && (char*)(p) < (char*)&sh.freelist[sh.freelist_size])
 260
 261
 262 typedef struct sh_list_st
 263 {
 264     struct sh_list_st *next;
 265     struct sh_list_st **p_next;
 266 } SH_LIST;
 267
 268 typedef struct sh_st
 269 {
 270     char* map_result;
 271     size_t map_size;
 272     char *arena;
 273     size_t arena_size;
 274     char **freelist;
 275     ossl_ssize_t freelist_size;
 276     size_t minsize;
 277     unsigned char *bittable;
 278     unsigned char *bitmalloc;
 279     size_t bittable_size; /* size in bits */
 280 } SH;
 281
 282 static SH sh;
 283
 284 static size_t sh_getlist(char *ptr)
 285 {
 286     ossl_ssize_t list = sh.freelist_size - 1;
 287     size_t bit = (sh.arena_size + ptr - sh.arena) / sh.minsize;
 288
 289     for (; bit; bit >>= 1, list--) {
 290         if (TESTBIT(sh.bittable, bit))
 291             break;
 292         OPENSSL_assert((bit & 1) == 0);
 293     }
 294
 295     return list;
 296 }
 297
 298
 299 static int sh_testbit(char *ptr, int list, unsigned char *table)
 300 {
 301     size_t bit;
 302
 303     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 304     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 305     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 306     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 307     return TESTBIT(table, bit);
 308 }
 309
 310 static void sh_clearbit(char *ptr, int list, unsigned char *table)
 311 {
 312     size_t bit;
 313
 314     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 315     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 316     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 317     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 318     OPENSSL_assert(TESTBIT(table, bit));
 319     CLEARBIT(table, bit);
 320 }
 321
 322 static void sh_setbit(char *ptr, int list, unsigned char *table)
 323 {
 324     size_t bit;
 325
 326     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 327     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 328     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 329     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 330     OPENSSL_assert(!TESTBIT(table, bit));
 331     SETBIT(table, bit);
 332 }
 333
 334 static void sh_add_to_list(char **list, char *ptr)
 335 {
 336     SH_LIST *temp;
 337
 338     OPENSSL_assert(WITHIN_FREELIST(list));
 339     OPENSSL_assert(WITHIN_ARENA(ptr));
 340
 341     temp = (SH_LIST *)ptr;
 342     temp->next = *(SH_LIST **)list;
 343     OPENSSL_assert(temp->next == NULL || WITHIN_ARENA(temp->next));
 344     temp->p_next = (SH_LIST **)list;
 345
 346     if (temp->next != NULL) {
 347         OPENSSL_assert((char **)temp->next->p_next == list);
 348         temp->next->p_next = &(temp->next);
 349     }
 350
 351     *list = ptr;
 352 }
 353
 354 static void sh_remove_from_list(char *ptr)
 355 {
 356     SH_LIST *temp, *temp2;
 357
 358     temp = (SH_LIST *)ptr;
 359     if (temp->next != NULL)
 360         temp->next->p_next = temp->p_next;
 361     *temp->p_next = temp->next;
 362     if (temp->next == NULL)
 363         return;
 364
 365     temp2 = temp->next;
 366     OPENSSL_assert(WITHIN_FREELIST(temp2->p_next) || WITHIN_ARENA(temp2->p_next));
 367 }
 368
 369
 370 static int sh_init(size_t size, int minsize)
 371 {
 372     int ret;
 373     size_t i;
 374     size_t pgsize;
 375     size_t aligned;
 376
 377     memset(&sh, 0, sizeof sh);
 378
 379     /* make sure size and minsize are powers of 2 */
 380     OPENSSL_assert(size > 0);
 381     OPENSSL_assert((size & (size - 1)) == 0);
 382     OPENSSL_assert(minsize > 0);
 383     OPENSSL_assert((minsize & (minsize - 1)) == 0);
 384     if (size <= 0 || (size & (size - 1)) != 0)
 385         goto err;
 386     if (minsize <= 0 || (minsize & (minsize - 1)) != 0)
 387         goto err;
 388
 389     while (minsize < (int)sizeof(SH_LIST))
 390         minsize *= 2;
 391
 392     sh.arena_size = size;
 393     sh.minsize = minsize;
 394     sh.bittable_size = (sh.arena_size / sh.minsize) * 2;
 395
 396     /* Prevent allocations of size 0 later on */
 397     if (sh.bittable_size >> 3 == 0)
 398         goto err;
 399
 400     sh.freelist_size = -1;
 401     for (i = sh.bittable_size; i; i >>= 1)
 402         sh.freelist_size++;
 403
 404     sh.freelist = OPENSSL_zalloc(sh.freelist_size * sizeof (char *));
 405     OPENSSL_assert(sh.freelist != NULL);
 406     if (sh.freelist == NULL)
 407         goto err;
 408
 409     sh.bittable = OPENSSL_zalloc(sh.bittable_size >> 3);
 410     OPENSSL_assert(sh.bittable != NULL);
 411     if (sh.bittable == NULL)
 412         goto err;
 413
 414     sh.bitmalloc = OPENSSL_zalloc(sh.bittable_size >> 3);
 415     OPENSSL_assert(sh.bitmalloc != NULL);
 416     if (sh.bitmalloc == NULL)
 417         goto err;
 418
 419     /* Allocate space for heap, and two extra pages as guards */
 420 #if defined(_SC_PAGE_SIZE) || defined (_SC_PAGESIZE)
 421     {
 422 # if defined(_SC_PAGE_SIZE)
 423         long tmppgsize = sysconf(_SC_PAGE_SIZE);
 424 # else
 425         long tmppgsize = sysconf(_SC_PAGESIZE);
 426 # endif
 427         if (tmppgsize < 1)
 428             pgsize = PAGE_SIZE;
 429         else
 430             pgsize = (size_t)tmppgsize;
 431     }
 432 #else
 433     pgsize = PAGE_SIZE;
 434 #endif
 435     sh.map_size = pgsize + sh.arena_size + pgsize;
 436     if (1) {
 437 #ifdef MAP_ANON
 438         sh.map_result = mmap(NULL, sh.map_size,
 439                              PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
 440     } else {
 441 #endif
 442         int fd;
 443
 444         sh.map_result = MAP_FAILED;
 445         if ((fd = open("/dev/zero", O_RDWR)) >= 0) {
 446             sh.map_result = mmap(NULL, sh.map_size,
 447                                  PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
 448             close(fd);
 449         }
 450     }
 451     if (sh.map_result == MAP_FAILED)
 452         goto err;
 453     sh.arena = (char *)(sh.map_result + pgsize);
 454     sh_setbit(sh.arena, 0, sh.bittable);
 455     sh_add_to_list(&sh.freelist[0], sh.arena);
 456
 457     /* Now try to add guard pages and lock into memory. */
 458     ret = 1;
 459
 460     /* Starting guard is already aligned from mmap. */
 461     if (mprotect(sh.map_result, pgsize, PROT_NONE) < 0)
 462         ret = 2;
 463
 464     /* Ending guard page - need to round up to page boundary */
 465     aligned = (pgsize + sh.arena_size + (pgsize - 1)) & ~(pgsize - 1);
 466     if (mprotect(sh.map_result + aligned, pgsize, PROT_NONE) < 0)
 467         ret = 2;
 468
 469 #if defined(OPENSSL_SYS_LINUX) && defined(MLOCK_ONFAULT) && defined(SYS_mlock2)
 470     if (syscall(SYS_mlock2, sh.arena, sh.arena_size, MLOCK_ONFAULT) < 0) {
 471         if (errno == ENOSYS) {
 472             if (mlock(sh.arena, sh.arena_size) < 0)
 473                 ret = 2;
 474         } else {
 475             ret = 2;
 476         }
 477     }
 478 #else
 479     if (mlock(sh.arena, sh.arena_size) < 0)
 480         ret = 2;
 481 #endif
 482 #ifdef MADV_DONTDUMP
 483     if (madvise(sh.arena, sh.arena_size, MADV_DONTDUMP) < 0)
 484         ret = 2;
 485 #endif
 486
 487     return ret;
 488
 489  err:
 490     sh_done();
 491     return 0;
 492 }
 493
 494 static void sh_done()
 495 {
 496     OPENSSL_free(sh.freelist);
 497     OPENSSL_free(sh.bittable);
 498     OPENSSL_free(sh.bitmalloc);
 499     if (sh.map_result != NULL && sh.map_size)
 500         munmap(sh.map_result, sh.map_size);
 501     memset(&sh, 0, sizeof sh);
 502 }
 503
 504 static int sh_allocated(const char *ptr)
 505 {
 506     return WITHIN_ARENA(ptr) ? 1 : 0;
 507 }
 508
 509 static char *sh_find_my_buddy(char *ptr, int list)
 510 {
 511     size_t bit;
 512     char *chunk = NULL;
 513
 514     bit = (ONE << list) + (ptr - sh.arena) / (sh.arena_size >> list);
 515     bit ^= 1;
 516
 517     if (TESTBIT(sh.bittable, bit) && !TESTBIT(sh.bitmalloc, bit))
 518         chunk = sh.arena + ((bit & ((ONE << list) - 1)) * (sh.arena_size >> list));
 519
 520     return chunk;
 521 }
 522
 523 static void *sh_malloc(size_t size)
 524 {
 525     ossl_ssize_t list, slist;
 526     size_t i;
 527     char *chunk;
 528
 529     if (size > sh.arena_size)
 530         return NULL;
 531
 532     list = sh.freelist_size - 1;
 533     for (i = sh.minsize; i < size; i <<= 1)
 534         list--;
 535     if (list < 0)
 536         return NULL;
 537
 538     /* try to find a larger entry to split */
 539     for (slist = list; slist >= 0; slist--)
 540         if (sh.freelist[slist] != NULL)
 541             break;
 542     if (slist < 0)
 543         return NULL;
 544
 545     /* split larger entry */
 546     while (slist != list) {
 547         char *temp = sh.freelist[slist];
 548
 549         /* remove from bigger list */
 550         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 551         sh_clearbit(temp, slist, sh.bittable);
 552         sh_remove_from_list(temp);
 553         OPENSSL_assert(temp != sh.freelist[slist]);
 554
 555         /* done with bigger list */
 556         slist++;
 557
 558         /* add to smaller list */
 559         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 560         sh_setbit(temp, slist, sh.bittable);
 561         sh_add_to_list(&sh.freelist[slist], temp);
 562         OPENSSL_assert(sh.freelist[slist] == temp);
 563
 564         /* split in 2 */
 565         temp += sh.arena_size >> slist;
 566         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 567         sh_setbit(temp, slist, sh.bittable);
 568         sh_add_to_list(&sh.freelist[slist], temp);
 569         OPENSSL_assert(sh.freelist[slist] == temp);
 570
 571         OPENSSL_assert(temp-(sh.arena_size >> slist) == sh_find_my_buddy(temp, slist));
 572     }
 573
 574     /* peel off memory to hand back */
 575     chunk = sh.freelist[list];
 576     OPENSSL_assert(sh_testbit(chunk, list, sh.bittable));
 577     sh_setbit(chunk, list, sh.bitmalloc);
 578     sh_remove_from_list(chunk);
 579
 580     OPENSSL_assert(WITHIN_ARENA(chunk));
 581
 582     return chunk;
 583 }
 584
 585 static void sh_free(void *ptr)
 586 {
 587     size_t list;
 588     void *buddy;
 589
 590     if (ptr == NULL)
 591         return;
 592     OPENSSL_assert(WITHIN_ARENA(ptr));
 593     if (!WITHIN_ARENA(ptr))
 594         return;
 595
 596     list = sh_getlist(ptr);
 597     OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
 598     sh_clearbit(ptr, list, sh.bitmalloc);
 599     sh_add_to_list(&sh.freelist[list], ptr);
 600
 601     /* Try to coalesce two adjacent free areas. */
 602     while ((buddy = sh_find_my_buddy(ptr, list)) != NULL) {
 603         OPENSSL_assert(ptr == sh_find_my_buddy(buddy, list));
 604         OPENSSL_assert(ptr != NULL);
 605         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 606         sh_clearbit(ptr, list, sh.bittable);
 607         sh_remove_from_list(ptr);
 608         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 609         sh_clearbit(buddy, list, sh.bittable);
 610         sh_remove_from_list(buddy);
 611
 612         list--;
 613
 614         if (ptr > buddy)
 615             ptr = buddy;
 616
 617         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 618         sh_setbit(ptr, list, sh.bittable);
 619         sh_add_to_list(&sh.freelist[list], ptr);
 620         OPENSSL_assert(sh.freelist[list] == ptr);
 621     }
 622 }
 623
 624 static size_t sh_actual_size(char *ptr)
 625 {
 626     int list;
 627
 628     OPENSSL_assert(WITHIN_ARENA(ptr));
 629     if (!WITHIN_ARENA(ptr))
 630         return 0;
 631     list = sh_getlist(ptr);
 632     OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
 633     return sh.arena_size / (ONE << list);
 634 }
 635 #endif /* IMPLEMENTED */