crypto/mem_sec.c

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