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