crypto/mem_sec.c

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