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>
28 # include "internal/threads.h"
31 #define CLEAR(p, s) OPENSSL_cleanse(p, s)
33 # define PAGE_SIZE 4096
37 static size_t secure_mem_used;
39 static int secure_mem_initialized;
41 static CRYPTO_RWLOCK *sec_malloc_lock = NULL;
44 * These are the functions that must be implemented by a secure heap (sh).
46 static int sh_init(size_t size, int minsize);
47 static char *sh_malloc(size_t size);
48 static void sh_free(char *ptr);
49 static void sh_done(void);
50 static size_t sh_actual_size(char *ptr);
51 static int sh_allocated(const char *ptr);
54 int CRYPTO_secure_malloc_init(size_t size, int minsize)
59 if (!secure_mem_initialized) {
60 sec_malloc_lock = CRYPTO_THREAD_lock_new();
61 if (sec_malloc_lock == NULL)
63 ret = sh_init(size, minsize);
64 secure_mem_initialized = 1;
70 #endif /* IMPLEMENTED */
73 int CRYPTO_secure_malloc_done()
76 if (secure_mem_used == 0) {
78 secure_mem_initialized = 0;
79 CRYPTO_THREAD_lock_free(sec_malloc_lock);
82 #endif /* IMPLEMENTED */
86 int CRYPTO_secure_malloc_initialized()
89 return secure_mem_initialized;
92 #endif /* IMPLEMENTED */
95 void *CRYPTO_secure_malloc(size_t num, const char *file, int line)
101 if (!secure_mem_initialized) {
102 return CRYPTO_malloc(num, file, line);
104 CRYPTO_THREAD_write_lock(sec_malloc_lock);
105 ret = sh_malloc(num);
106 actual_size = ret ? sh_actual_size(ret) : 0;
107 secure_mem_used += actual_size;
108 CRYPTO_THREAD_unlock(sec_malloc_lock);
111 return CRYPTO_malloc(num, file, line);
112 #endif /* IMPLEMENTED */
115 void *CRYPTO_secure_zalloc(size_t num, const char *file, int line)
117 void *ret = CRYPTO_secure_malloc(num, file, line);
124 void CRYPTO_secure_free(void *ptr, const char *file, int line)
131 if (!CRYPTO_secure_allocated(ptr)) {
132 CRYPTO_free(ptr, file, line);
135 CRYPTO_THREAD_write_lock(sec_malloc_lock);
136 actual_size = sh_actual_size(ptr);
137 CLEAR(ptr, actual_size);
138 secure_mem_used -= actual_size;
140 CRYPTO_THREAD_unlock(sec_malloc_lock);
142 CRYPTO_free(ptr, file, line);
143 #endif /* IMPLEMENTED */
146 int CRYPTO_secure_allocated(const void *ptr)
151 if (!secure_mem_initialized)
153 CRYPTO_THREAD_write_lock(sec_malloc_lock);
154 ret = sh_allocated(ptr);
155 CRYPTO_THREAD_unlock(sec_malloc_lock);
159 #endif /* IMPLEMENTED */
162 size_t CRYPTO_secure_used()
165 return secure_mem_used;
168 #endif /* IMPLEMENTED */
171 size_t CRYPTO_secure_actual_size(void *ptr)
176 CRYPTO_THREAD_write_lock(sec_malloc_lock);
177 actual_size = sh_actual_size(ptr);
178 CRYPTO_THREAD_unlock(sec_malloc_lock);
189 * SECURE HEAP IMPLEMENTATION
195 * The implementation provided here uses a fixed-sized mmap() heap,
196 * which is locked into memory, not written to core files, and protected
197 * on either side by an unmapped page, which will catch pointer overruns
198 * (or underruns) and an attempt to read data out of the secure heap.
199 * Free'd memory is zero'd or otherwise cleansed.
201 * This is a pretty standard buddy allocator. We keep areas in a multiple
202 * of "sh.minsize" units. The freelist and bitmaps are kept separately,
203 * so all (and only) data is kept in the mmap'd heap.
205 * This code assumes eight-bit bytes. The numbers 3 and 7 are all over the
209 #define ONE ((size_t)1)
211 # define TESTBIT(t, b) (t[(b) >> 3] & (ONE << ((b) & 7)))
212 # define SETBIT(t, b) (t[(b) >> 3] |= (ONE << ((b) & 7)))
213 # define CLEARBIT(t, b) (t[(b) >> 3] &= (0xFF & ~(ONE << ((b) & 7))))
215 #define WITHIN_ARENA(p) \
216 ((char*)(p) >= sh.arena && (char*)(p) < &sh.arena[sh.arena_size])
217 #define WITHIN_FREELIST(p) \
218 ((char*)(p) >= (char*)sh.freelist && (char*)(p) < (char*)&sh.freelist[sh.freelist_size])
221 typedef struct sh_list_st
223 struct sh_list_st *next;
224 struct sh_list_st **p_next;
234 ossl_ssize_t freelist_size;
236 unsigned char *bittable;
237 unsigned char *bitmalloc;
238 size_t bittable_size; /* size in bits */
243 static size_t sh_getlist(char *ptr)
245 ossl_ssize_t list = sh.freelist_size - 1;
246 size_t bit = (sh.arena_size + ptr - sh.arena) / sh.minsize;
248 for (; bit; bit >>= 1, list--) {
249 if (TESTBIT(sh.bittable, bit))
251 OPENSSL_assert((bit & 1) == 0);
258 static int sh_testbit(char *ptr, int list, unsigned char *table)
262 OPENSSL_assert(list >= 0 && list < sh.freelist_size);
263 OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
264 bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
265 OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
266 return TESTBIT(table, bit);
269 static void sh_clearbit(char *ptr, int list, unsigned char *table)
273 OPENSSL_assert(list >= 0 && list < sh.freelist_size);
274 OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
275 bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
276 OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
277 OPENSSL_assert(TESTBIT(table, bit));
278 CLEARBIT(table, bit);
281 static void sh_setbit(char *ptr, int list, unsigned char *table)
285 OPENSSL_assert(list >= 0 && list < sh.freelist_size);
286 OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
287 bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
288 OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
289 OPENSSL_assert(!TESTBIT(table, bit));
293 static void sh_add_to_list(char **list, char *ptr)
297 OPENSSL_assert(WITHIN_FREELIST(list));
298 OPENSSL_assert(WITHIN_ARENA(ptr));
300 temp = (SH_LIST *)ptr;
301 temp->next = *(SH_LIST **)list;
302 OPENSSL_assert(temp->next == NULL || WITHIN_ARENA(temp->next));
303 temp->p_next = (SH_LIST **)list;
305 if (temp->next != NULL) {
306 OPENSSL_assert((char **)temp->next->p_next == list);
307 temp->next->p_next = &(temp->next);
313 static void sh_remove_from_list(char *ptr)
315 SH_LIST *temp, *temp2;
317 temp = (SH_LIST *)ptr;
318 if (temp->next != NULL)
319 temp->next->p_next = temp->p_next;
320 *temp->p_next = temp->next;
321 if (temp->next == NULL)
325 OPENSSL_assert(WITHIN_FREELIST(temp2->p_next) || WITHIN_ARENA(temp2->p_next));
329 static int sh_init(size_t size, int minsize)
335 memset(&sh, 0, sizeof sh);
337 /* make sure size and minsize are powers of 2 */
338 OPENSSL_assert(size > 0);
339 OPENSSL_assert((size & (size - 1)) == 0);
340 OPENSSL_assert(minsize > 0);
341 OPENSSL_assert((minsize & (minsize - 1)) == 0);
342 if (size <= 0 || (size & (size - 1)) != 0)
344 if (minsize <= 0 || (minsize & (minsize - 1)) != 0)
347 sh.arena_size = size;
348 sh.minsize = minsize;
349 sh.bittable_size = (sh.arena_size / sh.minsize) * 2;
351 sh.freelist_size = -1;
352 for (i = sh.bittable_size; i; i >>= 1)
355 sh.freelist = OPENSSL_zalloc(sh.freelist_size * sizeof (char *));
356 OPENSSL_assert(sh.freelist != NULL);
357 if (sh.freelist == NULL)
360 sh.bittable = OPENSSL_zalloc(sh.bittable_size >> 3);
361 OPENSSL_assert(sh.bittable != NULL);
362 if (sh.bittable == NULL)
365 sh.bitmalloc = OPENSSL_zalloc(sh.bittable_size >> 3);
366 OPENSSL_assert(sh.bitmalloc != NULL);
367 if (sh.bitmalloc == NULL)
370 /* Allocate space for heap, and two extra pages as guards */
371 #if defined(_SC_PAGE_SIZE) || defined (_SC_PAGESIZE)
373 # if defined(_SC_PAGE_SIZE)
374 long tmppgsize = sysconf(_SC_PAGE_SIZE);
376 long tmppgsize = sysconf(_SC_PAGESIZE);
381 pgsize = (size_t)tmppgsize;
386 sh.map_size = pgsize + sh.arena_size + pgsize;
389 sh.map_result = mmap(NULL, sh.map_size,
390 PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
395 sh.map_result = MAP_FAILED;
396 if ((fd = open("/dev/zero", O_RDWR)) >= 0) {
397 sh.map_result = mmap(NULL, sh.map_size,
398 PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
402 OPENSSL_assert(sh.map_result != MAP_FAILED);
403 if (sh.map_result == MAP_FAILED)
405 sh.arena = (char *)(sh.map_result + pgsize);
406 sh_setbit(sh.arena, 0, sh.bittable);
407 sh_add_to_list(&sh.freelist[0], sh.arena);
409 /* Now try to add guard pages and lock into memory. */
412 /* Starting guard is already aligned from mmap. */
413 if (mprotect(sh.map_result, pgsize, PROT_NONE) < 0)
416 /* Ending guard page - need to round up to page boundary */
417 aligned = (pgsize + sh.arena_size + (pgsize - 1)) & ~(pgsize - 1);
418 if (mprotect(sh.map_result + aligned, pgsize, PROT_NONE) < 0)
421 if (mlock(sh.arena, sh.arena_size) < 0)
424 if (madvise(sh.arena, sh.arena_size, MADV_DONTDUMP) < 0)
435 static void sh_done()
437 OPENSSL_free(sh.freelist);
438 OPENSSL_free(sh.bittable);
439 OPENSSL_free(sh.bitmalloc);
440 if (sh.map_result != NULL && sh.map_size)
441 munmap(sh.map_result, sh.map_size);
442 memset(&sh, 0, sizeof sh);
445 static int sh_allocated(const char *ptr)
447 return WITHIN_ARENA(ptr) ? 1 : 0;
450 static char *sh_find_my_buddy(char *ptr, int list)
455 bit = (ONE << list) + (ptr - sh.arena) / (sh.arena_size >> list);
458 if (TESTBIT(sh.bittable, bit) && !TESTBIT(sh.bitmalloc, bit))
459 chunk = sh.arena + ((bit & ((ONE << list) - 1)) * (sh.arena_size >> list));
464 static char *sh_malloc(size_t size)
466 ossl_ssize_t list, slist;
470 list = sh.freelist_size - 1;
471 for (i = sh.minsize; i < size; i <<= 1)
476 /* try to find a larger entry to split */
477 for (slist = list; slist >= 0; slist--)
478 if (sh.freelist[slist] != NULL)
483 /* split larger entry */
484 while (slist != list) {
485 char *temp = sh.freelist[slist];
487 /* remove from bigger list */
488 OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
489 sh_clearbit(temp, slist, sh.bittable);
490 sh_remove_from_list(temp);
491 OPENSSL_assert(temp != sh.freelist[slist]);
493 /* done with bigger list */
496 /* add to smaller list */
497 OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
498 sh_setbit(temp, slist, sh.bittable);
499 sh_add_to_list(&sh.freelist[slist], temp);
500 OPENSSL_assert(sh.freelist[slist] == temp);
503 temp += sh.arena_size >> slist;
504 OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
505 sh_setbit(temp, slist, sh.bittable);
506 sh_add_to_list(&sh.freelist[slist], temp);
507 OPENSSL_assert(sh.freelist[slist] == temp);
509 OPENSSL_assert(temp-(sh.arena_size >> slist) == sh_find_my_buddy(temp, slist));
512 /* peel off memory to hand back */
513 chunk = sh.freelist[list];
514 OPENSSL_assert(sh_testbit(chunk, list, sh.bittable));
515 sh_setbit(chunk, list, sh.bitmalloc);
516 sh_remove_from_list(chunk);
518 OPENSSL_assert(WITHIN_ARENA(chunk));
523 static void sh_free(char *ptr)
530 OPENSSL_assert(WITHIN_ARENA(ptr));
531 if (!WITHIN_ARENA(ptr))
534 list = sh_getlist(ptr);
535 OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
536 sh_clearbit(ptr, list, sh.bitmalloc);
537 sh_add_to_list(&sh.freelist[list], ptr);
539 /* Try to coalesce two adjacent free areas. */
540 while ((buddy = sh_find_my_buddy(ptr, list)) != NULL) {
541 OPENSSL_assert(ptr == sh_find_my_buddy(buddy, list));
542 OPENSSL_assert(ptr != NULL);
543 OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
544 sh_clearbit(ptr, list, sh.bittable);
545 sh_remove_from_list(ptr);
546 OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
547 sh_clearbit(buddy, list, sh.bittable);
548 sh_remove_from_list(buddy);
555 OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
556 sh_setbit(ptr, list, sh.bittable);
557 sh_add_to_list(&sh.freelist[list], ptr);
558 OPENSSL_assert(sh.freelist[list] == ptr);
562 static size_t sh_actual_size(char *ptr)
566 OPENSSL_assert(WITHIN_ARENA(ptr));
567 if (!WITHIN_ARENA(ptr))
569 list = sh_getlist(ptr);
570 OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
571 return sh.arena_size / (ONE << list);
573 #endif /* IMPLEMENTED */