2 * Copyright 2004-2014, Akamai Technologies. All Rights Reserved.
3 * This file is distributed under the terms of the OpenSSL license.
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").
13 #include <openssl/crypto.h>
18 #if defined(OPENSSL_SYS_LINUX) || defined(OPENSSL_SYS_UNIX)
23 # include <sys/types.h>
24 # include <sys/mman.h>
25 # include <sys/param.h>
26 # include <sys/stat.h>
30 #define CLEAR(p, s) OPENSSL_cleanse(p, s)
32 # define PAGE_SIZE 4096
36 static size_t secure_mem_used;
38 static int secure_mem_initialized;
40 static CRYPTO_RWLOCK *sec_malloc_lock = NULL;
43 * These are the functions that must be implemented by a secure heap (sh).
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);
53 int CRYPTO_secure_malloc_init(size_t size, int minsize)
58 if (!secure_mem_initialized) {
59 sec_malloc_lock = CRYPTO_THREAD_lock_new();
60 if (sec_malloc_lock == NULL)
62 ret = sh_init(size, minsize);
63 secure_mem_initialized = 1;
69 #endif /* IMPLEMENTED */
72 int CRYPTO_secure_malloc_done()
75 if (secure_mem_used == 0) {
77 secure_mem_initialized = 0;
78 CRYPTO_THREAD_lock_free(sec_malloc_lock);
81 #endif /* IMPLEMENTED */
85 int CRYPTO_secure_malloc_initialized()
88 return secure_mem_initialized;
91 #endif /* IMPLEMENTED */
94 void *CRYPTO_secure_malloc(size_t num, const char *file, int line)
100 if (!secure_mem_initialized) {
101 return CRYPTO_malloc(num, file, line);
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);
110 return CRYPTO_malloc(num, file, line);
111 #endif /* IMPLEMENTED */
114 void *CRYPTO_secure_zalloc(size_t num, const char *file, int line)
116 void *ret = CRYPTO_secure_malloc(num, file, line);
123 void CRYPTO_secure_free(void *ptr, const char *file, int line)
130 if (!CRYPTO_secure_allocated(ptr)) {
131 CRYPTO_free(ptr, file, line);
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;
139 CRYPTO_THREAD_unlock(sec_malloc_lock);
141 CRYPTO_free(ptr, file, line);
142 #endif /* IMPLEMENTED */
145 int CRYPTO_secure_allocated(const void *ptr)
150 if (!secure_mem_initialized)
152 CRYPTO_THREAD_write_lock(sec_malloc_lock);
153 ret = sh_allocated(ptr);
154 CRYPTO_THREAD_unlock(sec_malloc_lock);
158 #endif /* IMPLEMENTED */
161 size_t CRYPTO_secure_used()
164 return secure_mem_used;
167 #endif /* IMPLEMENTED */
170 size_t CRYPTO_secure_actual_size(void *ptr)
175 CRYPTO_THREAD_write_lock(sec_malloc_lock);
176 actual_size = sh_actual_size(ptr);
177 CRYPTO_THREAD_unlock(sec_malloc_lock);
188 * SECURE HEAP IMPLEMENTATION
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.
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.
204 * This code assumes eight-bit bytes. The numbers 3 and 7 are all over the
208 #define ONE ((size_t)1)
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))))
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])
220 typedef struct sh_list_st
222 struct sh_list_st *next;
223 struct sh_list_st **p_next;
233 ossl_ssize_t freelist_size;
235 unsigned char *bittable;
236 unsigned char *bitmalloc;
237 size_t bittable_size; /* size in bits */
242 static size_t sh_getlist(char *ptr)
244 ossl_ssize_t list = sh.freelist_size - 1;
245 size_t bit = (sh.arena_size + ptr - sh.arena) / sh.minsize;
247 for (; bit; bit >>= 1, list--) {
248 if (TESTBIT(sh.bittable, bit))
250 OPENSSL_assert((bit & 1) == 0);
257 static int sh_testbit(char *ptr, int list, unsigned char *table)
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);
268 static void sh_clearbit(char *ptr, int list, unsigned char *table)
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);
280 static void sh_setbit(char *ptr, int list, unsigned char *table)
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));
292 static void sh_add_to_list(char **list, char *ptr)
296 OPENSSL_assert(WITHIN_FREELIST(list));
297 OPENSSL_assert(WITHIN_ARENA(ptr));
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;
304 if (temp->next != NULL) {
305 OPENSSL_assert((char **)temp->next->p_next == list);
306 temp->next->p_next = &(temp->next);
312 static void sh_remove_from_list(char *ptr)
314 SH_LIST *temp, *temp2;
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)
324 OPENSSL_assert(WITHIN_FREELIST(temp2->p_next) || WITHIN_ARENA(temp2->p_next));
328 static int sh_init(size_t size, int minsize)
334 memset(&sh, 0, sizeof sh);
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)
343 if (minsize <= 0 || (minsize & (minsize - 1)) != 0)
346 sh.arena_size = size;
347 sh.minsize = minsize;
348 sh.bittable_size = (sh.arena_size / sh.minsize) * 2;
350 sh.freelist_size = -1;
351 for (i = sh.bittable_size; i; i >>= 1)
354 sh.freelist = OPENSSL_zalloc(sh.freelist_size * sizeof (char *));
355 OPENSSL_assert(sh.freelist != NULL);
356 if (sh.freelist == NULL)
359 sh.bittable = OPENSSL_zalloc(sh.bittable_size >> 3);
360 OPENSSL_assert(sh.bittable != NULL);
361 if (sh.bittable == NULL)
364 sh.bitmalloc = OPENSSL_zalloc(sh.bittable_size >> 3);
365 OPENSSL_assert(sh.bitmalloc != NULL);
366 if (sh.bitmalloc == NULL)
369 /* Allocate space for heap, and two extra pages as guards */
370 #if defined(_SC_PAGE_SIZE) || defined (_SC_PAGESIZE)
372 # if defined(_SC_PAGE_SIZE)
373 long tmppgsize = sysconf(_SC_PAGE_SIZE);
375 long tmppgsize = sysconf(_SC_PAGESIZE);
380 pgsize = (size_t)tmppgsize;
385 sh.map_size = pgsize + sh.arena_size + pgsize;
388 sh.map_result = mmap(NULL, sh.map_size,
389 PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
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);
401 OPENSSL_assert(sh.map_result != MAP_FAILED);
402 if (sh.map_result == MAP_FAILED)
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);
408 /* Now try to add guard pages and lock into memory. */
411 /* Starting guard is already aligned from mmap. */
412 if (mprotect(sh.map_result, pgsize, PROT_NONE) < 0)
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)
420 if (mlock(sh.arena, sh.arena_size) < 0)
423 if (madvise(sh.arena, sh.arena_size, MADV_DONTDUMP) < 0)
434 static void sh_done()
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);
444 static int sh_allocated(const char *ptr)
446 return WITHIN_ARENA(ptr) ? 1 : 0;
449 static char *sh_find_my_buddy(char *ptr, int list)
454 bit = (ONE << list) + (ptr - sh.arena) / (sh.arena_size >> list);
457 if (TESTBIT(sh.bittable, bit) && !TESTBIT(sh.bitmalloc, bit))
458 chunk = sh.arena + ((bit & ((ONE << list) - 1)) * (sh.arena_size >> list));
463 static char *sh_malloc(size_t size)
465 ossl_ssize_t list, slist;
469 list = sh.freelist_size - 1;
470 for (i = sh.minsize; i < size; i <<= 1)
475 /* try to find a larger entry to split */
476 for (slist = list; slist >= 0; slist--)
477 if (sh.freelist[slist] != NULL)
482 /* split larger entry */
483 while (slist != list) {
484 char *temp = sh.freelist[slist];
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]);
492 /* done with bigger list */
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);
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);
508 OPENSSL_assert(temp-(sh.arena_size >> slist) == sh_find_my_buddy(temp, slist));
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);
517 OPENSSL_assert(WITHIN_ARENA(chunk));
522 static void sh_free(char *ptr)
529 OPENSSL_assert(WITHIN_ARENA(ptr));
530 if (!WITHIN_ARENA(ptr))
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);
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);
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);
561 static size_t sh_actual_size(char *ptr)
565 OPENSSL_assert(WITHIN_ARENA(ptr));
566 if (!WITHIN_ARENA(ptr))
568 list = sh_getlist(ptr);
569 OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
570 return sh.arena_size / (ONE << list);
572 #endif /* IMPLEMENTED */