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>
16 #if defined(OPENSSL_SYS_LINUX) || defined(OPENSSL_SYS_UNIX)
22 # include <sys/types.h>
23 # include <sys/mman.h>
24 # include <sys/param.h>
25 # include <sys/stat.h>
29 #define LOCK() CRYPTO_w_lock(CRYPTO_LOCK_MALLOC)
30 #define UNLOCK() CRYPTO_w_unlock(CRYPTO_LOCK_MALLOC)
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;
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 int sh_actual_size(char *ptr);
50 static int sh_allocated(const char *ptr);
53 int CRYPTO_secure_malloc_init(size_t size, int minsize)
61 OPENSSL_assert(!secure_mem_initialized);
62 if (!secure_mem_initialized) {
63 ret = sh_init(size, minsize);
64 secure_mem_initialized = 1;
70 #endif /* IMPLEMENTED */
73 void CRYPTO_secure_malloc_done()
78 secure_mem_initialized = 0;
80 #endif /* IMPLEMENTED */
83 int CRYPTO_secure_malloc_initialized()
86 return secure_mem_initialized;
89 #endif /* IMPLEMENTED */
92 void *CRYPTO_secure_malloc(int num, const char *file, int line)
98 if (!secure_mem_initialized) {
100 return CRYPTO_malloc(num, file, line);
103 ret = sh_malloc(num);
104 actual_size = ret ? sh_actual_size(ret) : 0;
105 secure_mem_used += actual_size;
109 return CRYPTO_malloc(num, file, line);
110 #endif /* IMPLEMENTED */
113 void CRYPTO_secure_free(void *ptr)
120 if (!secure_mem_initialized) {
125 actual_size = sh_actual_size(ptr);
126 CLEAR(ptr, actual_size);
127 secure_mem_used -= actual_size;
132 #endif /* IMPLEMENTED */
135 int CRYPTO_secure_allocated(const void *ptr)
140 if (!secure_mem_initialized)
143 ret = sh_allocated(ptr);
148 #endif /* IMPLEMENTED */
156 * SECURE HEAP IMPLEMENTATION
162 * The implementation provided here uses a fixed-sized mmap() heap,
163 * which is locked into memory, not written to core files, and protected
164 * on either side by an unmapped page, which will catch pointer overruns
165 * (or underruns) and an attempt to read data out of the secure heap.
166 * Free'd memory is zero'd or otherwise cleansed.
168 * This is a pretty standard buddy allocator. We keep areas in a multiple
169 * of "sh.minsize" units. The freelist and bitmaps are kept separately,
170 * so all (and only) data is kept in the mmap'd heap.
172 * This code assumes eight-bit bytes. The numbers 3 and 7 are all over the
176 # define TESTBIT(t, b) (t[(b) >> 3] & (1 << ((b) & 7)))
177 # define SETBIT(t, b) (t[(b) >> 3] |= (1 << ((b) & 7)))
178 # define CLEARBIT(t, b) (t[(b) >> 3] &= (0xFF & ~(1 << ((b) & 7))))
180 #define WITHIN_ARENA(p) \
181 ((char*)(p) >= sh.arena && (char*)(p) < &sh.arena[sh.arena_size])
182 #define WITHIN_FREELIST(p) \
183 ((char*)(p) >= (char*)sh.freelist && (char*)(p) < (char*)&sh.freelist[sh.freelist_size])
186 typedef struct sh_list_st
188 struct sh_list_st *next;
189 struct sh_list_st **p_next;
201 unsigned char *bittable;
202 unsigned char *bitmalloc;
203 int bittable_size; /* size in bits */
208 static int sh_getlist(char *ptr)
210 int list = sh.freelist_size - 1;
211 int bit = (sh.arena_size + ptr - sh.arena) / sh.minsize;
213 for (; bit; bit >>= 1, list--) {
214 if (TESTBIT(sh.bittable, bit))
216 OPENSSL_assert((bit & 1) == 0);
223 static int sh_testbit(char *ptr, int list, unsigned char *table)
227 OPENSSL_assert(list >= 0 && list < sh.freelist_size);
228 OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
229 bit = (1 << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
230 OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
231 return TESTBIT(table, bit);
234 static void sh_clearbit(char *ptr, int list, unsigned char *table)
238 OPENSSL_assert(list >= 0 && list < sh.freelist_size);
239 OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
240 bit = (1 << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
241 OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
242 OPENSSL_assert(TESTBIT(table, bit));
243 CLEARBIT(table, bit);
246 static void sh_setbit(char *ptr, int list, unsigned char *table)
250 OPENSSL_assert(list >= 0 && list < sh.freelist_size);
251 OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
252 bit = (1 << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
253 OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
254 OPENSSL_assert(!TESTBIT(table, bit));
258 static void sh_add_to_list(char **list, char *ptr)
262 OPENSSL_assert(WITHIN_FREELIST(list));
263 OPENSSL_assert(WITHIN_ARENA(ptr));
265 temp = (SH_LIST *)ptr;
266 temp->next = *(SH_LIST **)list;
267 OPENSSL_assert(temp->next == NULL || WITHIN_ARENA(temp->next));
268 temp->p_next = (SH_LIST **)list;
270 if (temp->next != NULL) {
271 OPENSSL_assert((char **)temp->next->p_next == list);
272 temp->next->p_next = &(temp->next);
278 static void sh_remove_from_list(char *ptr, char *list)
280 SH_LIST *temp, *temp2;
282 temp = (SH_LIST *)ptr;
283 if (temp->next != NULL)
284 temp->next->p_next = temp->p_next;
285 *temp->p_next = temp->next;
286 if (temp->next == NULL)
290 OPENSSL_assert(WITHIN_FREELIST(temp2->p_next) || WITHIN_ARENA(temp2->p_next));
294 static int sh_init(size_t size, int minsize)
300 memset(&sh, 0, sizeof sh);
302 /* make sure size and minsize are powers of 2 */
303 OPENSSL_assert(size > 0);
304 OPENSSL_assert((size & (size - 1)) == 0);
305 OPENSSL_assert(minsize > 0);
306 OPENSSL_assert((minsize & (minsize - 1)) == 0);
307 if (size <= 0 || (size & (size - 1)) != 0)
309 if (minsize <= 0 || (minsize & (minsize - 1)) != 0)
312 sh.arena_size = size;
313 sh.minsize = minsize;
314 sh.bittable_size = (sh.arena_size / sh.minsize) * 2;
316 sh.freelist_size = -1;
317 for (i = sh.bittable_size; i; i >>= 1)
320 sh.freelist = OPENSSL_zalloc(sh.freelist_size * sizeof (char *));
321 OPENSSL_assert(sh.freelist != NULL);
322 if (sh.freelist == NULL)
325 sh.bittable = OPENSSL_zalloc(sh.bittable_size >> 3);
326 OPENSSL_assert(sh.bittable != NULL);
327 if (sh.bittable == NULL)
330 sh.bitmalloc = OPENSSL_zalloc(sh.bittable_size >> 3);
331 OPENSSL_assert(sh.bitmalloc != NULL);
332 if (sh.bitmalloc == NULL)
335 /* Allocate space for heap, and two extra pages as guards */
336 #if defined(_SC_PAGE_SIZE) || defined (_SC_PAGESIZE)
338 # if defined(_SC_PAGE_SIZE)
339 long tmppgsize = sysconf(_SC_PAGE_SIZE);
341 long tmppgsize = sysconf(_SC_PAGESIZE);
346 pgsize = (size_t)tmppgsize;
351 sh.map_size = pgsize + sh.arena_size + pgsize;
354 sh.map_result = mmap(NULL, sh.map_size,
355 PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
360 sh.map_result = MAP_FAILED;
361 if ((fd = open("/dev/zero", O_RDWR)) >= 0) {
362 sh.map_result = mmap(NULL, sh.map_size,
363 PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
367 OPENSSL_assert(sh.map_result != MAP_FAILED);
368 if (sh.map_result == MAP_FAILED)
370 sh.arena = (char *)(sh.map_result + pgsize);
371 sh_setbit(sh.arena, 0, sh.bittable);
372 sh_add_to_list(&sh.freelist[0], sh.arena);
374 /* Now try to add guard pages and lock into memory. */
377 /* Starting guard is already aligned from mmap. */
378 if (mprotect(sh.map_result, pgsize, PROT_NONE) < 0)
381 /* Ending guard page - need to round up to page boundary */
382 aligned = (pgsize + sh.arena_size + (pgsize - 1)) & ~(pgsize - 1);
383 if (mprotect(sh.map_result + aligned, pgsize, PROT_NONE) < 0)
386 if (mlock(sh.arena, sh.arena_size) < 0)
389 if (madvise(sh.arena, sh.arena_size, MADV_DONTDUMP) < 0)
400 static void sh_done()
402 OPENSSL_free(sh.freelist);
403 OPENSSL_free(sh.bittable);
404 OPENSSL_free(sh.bitmalloc);
405 if (sh.map_result != NULL && sh.map_size)
406 munmap(sh.map_result, sh.map_size);
407 memset(&sh, 0, sizeof sh);
410 static int sh_allocated(const char *ptr)
412 return WITHIN_ARENA(ptr) ? 1 : 0;
415 static char *sh_find_my_buddy(char *ptr, int list)
420 bit = (1 << list) + (ptr - sh.arena) / (sh.arena_size >> list);
423 if (TESTBIT(sh.bittable, bit) && !TESTBIT(sh.bitmalloc, bit))
424 chunk = sh.arena + ((bit & ((1 << list) - 1)) * (sh.arena_size >> list));
429 static char *sh_malloc(size_t size)
435 list = sh.freelist_size - 1;
436 for (i = sh.minsize; i < size; i <<= 1)
441 /* try to find a larger entry to split */
442 for (slist = list; slist >= 0; slist--)
443 if (sh.freelist[slist] != NULL)
448 /* split larger entry */
449 while (slist != list) {
450 char *temp = sh.freelist[slist];
452 /* remove from bigger list */
453 OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
454 sh_clearbit(temp, slist, sh.bittable);
455 sh_remove_from_list(temp, sh.freelist[slist]);
456 OPENSSL_assert(temp != sh.freelist[slist]);
458 /* done with bigger list */
461 /* add to smaller list */
462 OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
463 sh_setbit(temp, slist, sh.bittable);
464 sh_add_to_list(&sh.freelist[slist], temp);
465 OPENSSL_assert(sh.freelist[slist] == temp);
468 temp += sh.arena_size >> slist;
469 OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
470 sh_setbit(temp, slist, sh.bittable);
471 sh_add_to_list(&sh.freelist[slist], temp);
472 OPENSSL_assert(sh.freelist[slist] == temp);
474 OPENSSL_assert(temp-(sh.arena_size >> slist) == sh_find_my_buddy(temp, slist));
477 /* peel off memory to hand back */
478 chunk = sh.freelist[list];
479 OPENSSL_assert(sh_testbit(chunk, list, sh.bittable));
480 sh_setbit(chunk, list, sh.bitmalloc);
481 sh_remove_from_list(chunk, sh.freelist[list]);
483 OPENSSL_assert(WITHIN_ARENA(chunk));
488 static void sh_free(char *ptr)
495 OPENSSL_assert(WITHIN_ARENA(ptr));
496 if (!WITHIN_ARENA(ptr))
499 list = sh_getlist(ptr);
500 OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
501 sh_clearbit(ptr, list, sh.bitmalloc);
502 sh_add_to_list(&sh.freelist[list], ptr);
504 /* Try to coalesce two adjacent free areas. */
505 while ((buddy = sh_find_my_buddy(ptr, list)) != NULL) {
506 OPENSSL_assert(ptr == sh_find_my_buddy(buddy, list));
507 OPENSSL_assert(ptr != NULL);
508 OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
509 sh_clearbit(ptr, list, sh.bittable);
510 sh_remove_from_list(ptr, sh.freelist[list]);
511 OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
512 sh_clearbit(buddy, list, sh.bittable);
513 sh_remove_from_list(buddy, sh.freelist[list]);
520 OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
521 sh_setbit(ptr, list, sh.bittable);
522 sh_add_to_list(&sh.freelist[list], ptr);
523 OPENSSL_assert(sh.freelist[list] == ptr);
527 static int sh_actual_size(char *ptr)
531 OPENSSL_assert(WITHIN_ARENA(ptr));
532 if (!WITHIN_ARENA(ptr))
534 list = sh_getlist(ptr);
535 OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
536 return sh.arena_size / (1 << list);
538 #endif /* IMPLEMENTED */