crypto/mem_sec.c

   1 /*
   2  * Copyright 2015-2018 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 "e_os.h"
  19 #include <openssl/crypto.h>
  20
  21 #include <string.h>
  22
  23 /* e_os.h includes unistd.h, which defines _POSIX_VERSION */
  24 #if defined(OPENSSL_SYS_UNIX) \
  25     && defined(_POSIX_VERSION) && _POSIX_VERSION >= 200112L
  26 # define IMPLEMENTED
  27 # include <stdlib.h>
  28 # include <assert.h>
  29 # include <unistd.h>
  30 # include <sys/types.h>
  31 # include <sys/mman.h>
  32 # if defined(OPENSSL_SYS_LINUX)
  33 #  include <sys/syscall.h>
  34 #  include <linux/mman.h>
  35 #  include <errno.h>
  36 # endif
  37 # include <sys/param.h>
  38 # include <sys/stat.h>
  39 # include <fcntl.h>
  40 #endif
  41
  42 #define CLEAR(p, s) OPENSSL_cleanse(p, s)
  43 #ifndef PAGE_SIZE
  44 # define PAGE_SIZE    4096
  45 #endif
  46
  47 #ifdef IMPLEMENTED
  48 static size_t secure_mem_used;
  49
  50 static int secure_mem_initialized;
  51
  52 static CRYPTO_RWLOCK *sec_malloc_lock = NULL;
  53
  54 /*
  55  * These are the functions that must be implemented by a secure heap (sh).
  56  */
  57 static int sh_init(size_t size, int minsize);
  58 static void *sh_malloc(size_t size);
  59 static void sh_free(void *ptr);
  60 static void sh_done(void);
  61 static size_t sh_actual_size(char *ptr);
  62 static int sh_allocated(const char *ptr);
  63 #endif
  64
  65 int CRYPTO_secure_malloc_init(size_t size, int minsize)
  66 {
  67 #ifdef IMPLEMENTED
  68     int ret = 0;
  69
  70     if (!secure_mem_initialized) {
  71         sec_malloc_lock = CRYPTO_THREAD_glock_new("sec_malloc");
  72         if (sec_malloc_lock == NULL)
  73             return 0;
  74         if ((ret = sh_init(size, minsize)) != 0) {
  75             secure_mem_initialized = 1;
  76         } else {
  77             CRYPTO_THREAD_lock_free(sec_malloc_lock);
  78             sec_malloc_lock = NULL;
  79         }
  80     }
  81
  82     return ret;
  83 #else
  84     return 0;
  85 #endif /* IMPLEMENTED */
  86 }
  87
  88 int CRYPTO_secure_malloc_done()
  89 {
  90 #ifdef IMPLEMENTED
  91     if (secure_mem_used == 0) {
  92         sh_done();
  93         secure_mem_initialized = 0;
  94         CRYPTO_THREAD_lock_free(sec_malloc_lock);
  95         sec_malloc_lock = NULL;
  96         return 1;
  97     }
  98 #endif /* IMPLEMENTED */
  99     return 0;
 100 }
 101
 102 int CRYPTO_secure_malloc_initialized()
 103 {
 104 #ifdef IMPLEMENTED
 105     return secure_mem_initialized;
 106 #else
 107     return 0;
 108 #endif /* IMPLEMENTED */
 109 }
 110
 111 void *CRYPTO_secure_malloc(size_t num, const char *file, int line)
 112 {
 113 #ifdef IMPLEMENTED
 114     void *ret;
 115     size_t actual_size;
 116
 117     if (!secure_mem_initialized) {
 118         return CRYPTO_malloc(num, file, line);
 119     }
 120     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 121     ret = sh_malloc(num);
 122     actual_size = ret ? sh_actual_size(ret) : 0;
 123     secure_mem_used += actual_size;
 124     CRYPTO_THREAD_unlock(sec_malloc_lock);
 125     return ret;
 126 #else
 127     return CRYPTO_malloc(num, file, line);
 128 #endif /* IMPLEMENTED */
 129 }
 130
 131 void *CRYPTO_secure_zalloc(size_t num, const char *file, int line)
 132 {
 133     void *ret = CRYPTO_secure_malloc(num, file, line);
 134
 135     if (ret != NULL)
 136         memset(ret, 0, num);
 137     return ret;
 138 }
 139
 140 void CRYPTO_secure_free(void *ptr, const char *file, int line)
 141 {
 142 #ifdef IMPLEMENTED
 143     size_t actual_size;
 144
 145     if (ptr == NULL)
 146         return;
 147     if (!CRYPTO_secure_allocated(ptr)) {
 148         CRYPTO_free(ptr, file, line);
 149         return;
 150     }
 151     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 152     actual_size = sh_actual_size(ptr);
 153     CLEAR(ptr, actual_size);
 154     secure_mem_used -= actual_size;
 155     sh_free(ptr);
 156     CRYPTO_THREAD_unlock(sec_malloc_lock);
 157 #else
 158     CRYPTO_free(ptr, file, line);
 159 #endif /* IMPLEMENTED */
 160 }
 161
 162 void CRYPTO_secure_clear_free(void *ptr, size_t num,
 163                               const char *file, int line)
 164 {
 165 #ifdef IMPLEMENTED
 166     size_t actual_size;
 167
 168     if (ptr == NULL)
 169         return;
 170     if (!CRYPTO_secure_allocated(ptr)) {
 171         OPENSSL_cleanse(ptr, num);
 172         CRYPTO_free(ptr, file, line);
 173         return;
 174     }
 175     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 176     actual_size = sh_actual_size(ptr);
 177     CLEAR(ptr, actual_size);
 178     secure_mem_used -= actual_size;
 179     sh_free(ptr);
 180     CRYPTO_THREAD_unlock(sec_malloc_lock);
 181 #else
 182     if (ptr == NULL)
 183         return;
 184     OPENSSL_cleanse(ptr, num);
 185     CRYPTO_free(ptr, file, line);
 186 #endif /* IMPLEMENTED */
 187 }
 188
 189 int CRYPTO_secure_allocated(const void *ptr)
 190 {
 191 #ifdef IMPLEMENTED
 192     int ret;
 193
 194     if (!secure_mem_initialized)
 195         return 0;
 196     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 197     ret = sh_allocated(ptr);
 198     CRYPTO_THREAD_unlock(sec_malloc_lock);
 199     return ret;
 200 #else
 201     return 0;
 202 #endif /* IMPLEMENTED */
 203 }
 204
 205 size_t CRYPTO_secure_used()
 206 {
 207 #ifdef IMPLEMENTED
 208     return secure_mem_used;
 209 #else
 210     return 0;
 211 #endif /* IMPLEMENTED */
 212 }
 213
 214 size_t CRYPTO_secure_actual_size(void *ptr)
 215 {
 216 #ifdef IMPLEMENTED
 217     size_t actual_size;
 218
 219     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 220     actual_size = sh_actual_size(ptr);
 221     CRYPTO_THREAD_unlock(sec_malloc_lock);
 222     return actual_size;
 223 #else
 224     return 0;
 225 #endif
 226 }
 227 /* END OF PAGE ...
 228
 229    ... START OF PAGE */
 230
 231 /*
 232  * SECURE HEAP IMPLEMENTATION
 233  */
 234 #ifdef IMPLEMENTED
 235
 236
 237 /*
 238  * The implementation provided here uses a fixed-sized mmap() heap,
 239  * which is locked into memory, not written to core files, and protected
 240  * on either side by an unmapped page, which will catch pointer overruns
 241  * (or underruns) and an attempt to read data out of the secure heap.
 242  * Free'd memory is zero'd or otherwise cleansed.
 243  *
 244  * This is a pretty standard buddy allocator.  We keep areas in a multiple
 245  * of "sh.minsize" units.  The freelist and bitmaps are kept separately,
 246  * so all (and only) data is kept in the mmap'd heap.
 247  *
 248  * This code assumes eight-bit bytes.  The numbers 3 and 7 are all over the
 249  * place.
 250  */
 251
 252 #define ONE ((size_t)1)
 253
 254 # define TESTBIT(t, b)  (t[(b) >> 3] &  (ONE << ((b) & 7)))
 255 # define SETBIT(t, b)   (t[(b) >> 3] |= (ONE << ((b) & 7)))
 256 # define CLEARBIT(t, b) (t[(b) >> 3] &= (0xFF & ~(ONE << ((b) & 7))))
 257
 258 #define WITHIN_ARENA(p) \
 259     ((char*)(p) >= sh.arena && (char*)(p) < &sh.arena[sh.arena_size])
 260 #define WITHIN_FREELIST(p) \
 261     ((char*)(p) >= (char*)sh.freelist && (char*)(p) < (char*)&sh.freelist[sh.freelist_size])
 262
 263
 264 typedef struct sh_list_st
 265 {
 266     struct sh_list_st *next;
 267     struct sh_list_st **p_next;
 268 } SH_LIST;
 269
 270 typedef struct sh_st
 271 {
 272     char* map_result;
 273     size_t map_size;
 274     char *arena;
 275     size_t arena_size;
 276     char **freelist;
 277     ossl_ssize_t freelist_size;
 278     size_t minsize;
 279     unsigned char *bittable;
 280     unsigned char *bitmalloc;
 281     size_t bittable_size; /* size in bits */
 282 } SH;
 283
 284 static SH sh;
 285
 286 static size_t sh_getlist(char *ptr)
 287 {
 288     ossl_ssize_t list = sh.freelist_size - 1;
 289     size_t bit = (sh.arena_size + ptr - sh.arena) / sh.minsize;
 290
 291     for (; bit; bit >>= 1, list--) {
 292         if (TESTBIT(sh.bittable, bit))
 293             break;
 294         OPENSSL_assert((bit & 1) == 0);
 295     }
 296
 297     return list;
 298 }
 299
 300
 301 static int sh_testbit(char *ptr, int list, unsigned char *table)
 302 {
 303     size_t bit;
 304
 305     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 306     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 307     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 308     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 309     return TESTBIT(table, bit);
 310 }
 311
 312 static void sh_clearbit(char *ptr, int list, unsigned char *table)
 313 {
 314     size_t bit;
 315
 316     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 317     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 318     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 319     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 320     OPENSSL_assert(TESTBIT(table, bit));
 321     CLEARBIT(table, bit);
 322 }
 323
 324 static void sh_setbit(char *ptr, int list, unsigned char *table)
 325 {
 326     size_t bit;
 327
 328     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 329     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 330     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 331     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 332     OPENSSL_assert(!TESTBIT(table, bit));
 333     SETBIT(table, bit);
 334 }
 335
 336 static void sh_add_to_list(char **list, char *ptr)
 337 {
 338     SH_LIST *temp;
 339
 340     OPENSSL_assert(WITHIN_FREELIST(list));
 341     OPENSSL_assert(WITHIN_ARENA(ptr));
 342
 343     temp = (SH_LIST *)ptr;
 344     temp->next = *(SH_LIST **)list;
 345     OPENSSL_assert(temp->next == NULL || WITHIN_ARENA(temp->next));
 346     temp->p_next = (SH_LIST **)list;
 347
 348     if (temp->next != NULL) {
 349         OPENSSL_assert((char **)temp->next->p_next == list);
 350         temp->next->p_next = &(temp->next);
 351     }
 352
 353     *list = ptr;
 354 }
 355
 356 static void sh_remove_from_list(char *ptr)
 357 {
 358     SH_LIST *temp, *temp2;
 359
 360     temp = (SH_LIST *)ptr;
 361     if (temp->next != NULL)
 362         temp->next->p_next = temp->p_next;
 363     *temp->p_next = temp->next;
 364     if (temp->next == NULL)
 365         return;
 366
 367     temp2 = temp->next;
 368     OPENSSL_assert(WITHIN_FREELIST(temp2->p_next) || WITHIN_ARENA(temp2->p_next));
 369 }
 370
 371
 372 static int sh_init(size_t size, int minsize)
 373 {
 374     int ret;
 375     size_t i;
 376     size_t pgsize;
 377     size_t aligned;
 378
 379     memset(&sh, 0, sizeof(sh));
 380
 381     /* make sure size and minsize are powers of 2 */
 382     OPENSSL_assert(size > 0);
 383     OPENSSL_assert((size & (size - 1)) == 0);
 384     OPENSSL_assert(minsize > 0);
 385     OPENSSL_assert((minsize & (minsize - 1)) == 0);
 386     if (size <= 0 || (size & (size - 1)) != 0)
 387         goto err;
 388     if (minsize <= 0 || (minsize & (minsize - 1)) != 0)
 389         goto err;
 390
 391     while (minsize < (int)sizeof(SH_LIST))
 392         minsize *= 2;
 393
 394     sh.arena_size = size;
 395     sh.minsize = minsize;
 396     sh.bittable_size = (sh.arena_size / sh.minsize) * 2;
 397
 398     /* Prevent allocations of size 0 later on */
 399     if (sh.bittable_size >> 3 == 0)
 400         goto err;
 401
 402     sh.freelist_size = -1;
 403     for (i = sh.bittable_size; i; i >>= 1)
 404         sh.freelist_size++;
 405
 406     sh.freelist = OPENSSL_zalloc(sh.freelist_size * sizeof(char *));
 407     OPENSSL_assert(sh.freelist != NULL);
 408     if (sh.freelist == NULL)
 409         goto err;
 410
 411     sh.bittable = OPENSSL_zalloc(sh.bittable_size >> 3);
 412     OPENSSL_assert(sh.bittable != NULL);
 413     if (sh.bittable == NULL)
 414         goto err;
 415
 416     sh.bitmalloc = OPENSSL_zalloc(sh.bittable_size >> 3);
 417     OPENSSL_assert(sh.bitmalloc != NULL);
 418     if (sh.bitmalloc == NULL)
 419         goto err;
 420
 421     /* Allocate space for heap, and two extra pages as guards */
 422 #if defined(_SC_PAGE_SIZE) || defined (_SC_PAGESIZE)
 423     {
 424 # if defined(_SC_PAGE_SIZE)
 425         long tmppgsize = sysconf(_SC_PAGE_SIZE);
 426 # else
 427         long tmppgsize = sysconf(_SC_PAGESIZE);
 428 # endif
 429         if (tmppgsize < 1)
 430             pgsize = PAGE_SIZE;
 431         else
 432             pgsize = (size_t)tmppgsize;
 433     }
 434 #else
 435     pgsize = PAGE_SIZE;
 436 #endif
 437     sh.map_size = pgsize + sh.arena_size + pgsize;
 438     if (1) {
 439 #ifdef MAP_ANON
 440         sh.map_result = mmap(NULL, sh.map_size,
 441                              PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
 442     } else {
 443 #endif
 444         int fd;
 445
 446         sh.map_result = MAP_FAILED;
 447         if ((fd = open("/dev/zero", O_RDWR)) >= 0) {
 448             sh.map_result = mmap(NULL, sh.map_size,
 449                                  PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
 450             close(fd);
 451         }
 452     }
 453     if (sh.map_result == MAP_FAILED)
 454         goto err;
 455     sh.arena = (char *)(sh.map_result + pgsize);
 456     sh_setbit(sh.arena, 0, sh.bittable);
 457     sh_add_to_list(&sh.freelist[0], sh.arena);
 458
 459     /* Now try to add guard pages and lock into memory. */
 460     ret = 1;
 461
 462     /* Starting guard is already aligned from mmap. */
 463     if (mprotect(sh.map_result, pgsize, PROT_NONE) < 0)
 464         ret = 2;
 465
 466     /* Ending guard page - need to round up to page boundary */
 467     aligned = (pgsize + sh.arena_size + (pgsize - 1)) & ~(pgsize - 1);
 468     if (mprotect(sh.map_result + aligned, pgsize, PROT_NONE) < 0)
 469         ret = 2;
 470
 471 #if defined(OPENSSL_SYS_LINUX) && defined(MLOCK_ONFAULT) && defined(SYS_mlock2)
 472     if (syscall(SYS_mlock2, sh.arena, sh.arena_size, MLOCK_ONFAULT) < 0) {
 473         if (errno == ENOSYS) {
 474             if (mlock(sh.arena, sh.arena_size) < 0)
 475                 ret = 2;
 476         } else {
 477             ret = 2;
 478         }
 479     }
 480 #else
 481     if (mlock(sh.arena, sh.arena_size) < 0)
 482         ret = 2;
 483 #endif
 484 #ifdef MADV_DONTDUMP
 485     if (madvise(sh.arena, sh.arena_size, MADV_DONTDUMP) < 0)
 486         ret = 2;
 487 #endif
 488
 489     return ret;
 490
 491  err:
 492     sh_done();
 493     return 0;
 494 }
 495
 496 static void sh_done()
 497 {
 498     OPENSSL_free(sh.freelist);
 499     OPENSSL_free(sh.bittable);
 500     OPENSSL_free(sh.bitmalloc);
 501     if (sh.map_result != NULL && sh.map_size)
 502         munmap(sh.map_result, sh.map_size);
 503     memset(&sh, 0, sizeof(sh));
 504 }
 505
 506 static int sh_allocated(const char *ptr)
 507 {
 508     return WITHIN_ARENA(ptr) ? 1 : 0;
 509 }
 510
 511 static char *sh_find_my_buddy(char *ptr, int list)
 512 {
 513     size_t bit;
 514     char *chunk = NULL;
 515
 516     bit = (ONE << list) + (ptr - sh.arena) / (sh.arena_size >> list);
 517     bit ^= 1;
 518
 519     if (TESTBIT(sh.bittable, bit) && !TESTBIT(sh.bitmalloc, bit))
 520         chunk = sh.arena + ((bit & ((ONE << list) - 1)) * (sh.arena_size >> list));
 521
 522     return chunk;
 523 }
 524
 525 static void *sh_malloc(size_t size)
 526 {
 527     ossl_ssize_t list, slist;
 528     size_t i;
 529     char *chunk;
 530
 531     if (size > sh.arena_size)
 532         return NULL;
 533
 534     list = sh.freelist_size - 1;
 535     for (i = sh.minsize; i < size; i <<= 1)
 536         list--;
 537     if (list < 0)
 538         return NULL;
 539
 540     /* try to find a larger entry to split */
 541     for (slist = list; slist >= 0; slist--)
 542         if (sh.freelist[slist] != NULL)
 543             break;
 544     if (slist < 0)
 545         return NULL;
 546
 547     /* split larger entry */
 548     while (slist != list) {
 549         char *temp = sh.freelist[slist];
 550
 551         /* remove from bigger list */
 552         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 553         sh_clearbit(temp, slist, sh.bittable);
 554         sh_remove_from_list(temp);
 555         OPENSSL_assert(temp != sh.freelist[slist]);
 556
 557         /* done with bigger list */
 558         slist++;
 559
 560         /* add to smaller list */
 561         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 562         sh_setbit(temp, slist, sh.bittable);
 563         sh_add_to_list(&sh.freelist[slist], temp);
 564         OPENSSL_assert(sh.freelist[slist] == temp);
 565
 566         /* split in 2 */
 567         temp += sh.arena_size >> slist;
 568         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 569         sh_setbit(temp, slist, sh.bittable);
 570         sh_add_to_list(&sh.freelist[slist], temp);
 571         OPENSSL_assert(sh.freelist[slist] == temp);
 572
 573         OPENSSL_assert(temp-(sh.arena_size >> slist) == sh_find_my_buddy(temp, slist));
 574     }
 575
 576     /* peel off memory to hand back */
 577     chunk = sh.freelist[list];
 578     OPENSSL_assert(sh_testbit(chunk, list, sh.bittable));
 579     sh_setbit(chunk, list, sh.bitmalloc);
 580     sh_remove_from_list(chunk);
 581
 582     OPENSSL_assert(WITHIN_ARENA(chunk));
 583
 584     return chunk;
 585 }
 586
 587 static void sh_free(void *ptr)
 588 {
 589     size_t list;
 590     void *buddy;
 591
 592     if (ptr == NULL)
 593         return;
 594     OPENSSL_assert(WITHIN_ARENA(ptr));
 595     if (!WITHIN_ARENA(ptr))
 596         return;
 597
 598     list = sh_getlist(ptr);
 599     OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
 600     sh_clearbit(ptr, list, sh.bitmalloc);
 601     sh_add_to_list(&sh.freelist[list], ptr);
 602
 603     /* Try to coalesce two adjacent free areas. */
 604     while ((buddy = sh_find_my_buddy(ptr, list)) != NULL) {
 605         OPENSSL_assert(ptr == sh_find_my_buddy(buddy, list));
 606         OPENSSL_assert(ptr != NULL);
 607         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 608         sh_clearbit(ptr, list, sh.bittable);
 609         sh_remove_from_list(ptr);
 610         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 611         sh_clearbit(buddy, list, sh.bittable);
 612         sh_remove_from_list(buddy);
 613
 614         list--;
 615
 616         if (ptr > buddy)
 617             ptr = buddy;
 618
 619         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 620         sh_setbit(ptr, list, sh.bittable);
 621         sh_add_to_list(&sh.freelist[list], ptr);
 622         OPENSSL_assert(sh.freelist[list] == ptr);
 623     }
 624 }
 625
 626 static size_t sh_actual_size(char *ptr)
 627 {
 628     int list;
 629
 630     OPENSSL_assert(WITHIN_ARENA(ptr));
 631     if (!WITHIN_ARENA(ptr))
 632         return 0;
 633     list = sh_getlist(ptr);
 634     OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
 635     return sh.arena_size / (ONE << list);
 636 }
 637 #endif /* IMPLEMENTED */