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(size_t 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 */
151 size_t CRYPTO_secure_used()
154 return secure_mem_used;
157 #endif /* IMPLEMENTED */
165 * SECURE HEAP IMPLEMENTATION
171 * The implementation provided here uses a fixed-sized mmap() heap,
172 * which is locked into memory, not written to core files, and protected
173 * on either side by an unmapped page, which will catch pointer overruns
174 * (or underruns) and an attempt to read data out of the secure heap.
175 * Free'd memory is zero'd or otherwise cleansed.
177 * This is a pretty standard buddy allocator. We keep areas in a multiple
178 * of "sh.minsize" units. The freelist and bitmaps are kept separately,
179 * so all (and only) data is kept in the mmap'd heap.
181 * This code assumes eight-bit bytes. The numbers 3 and 7 are all over the
185 # define TESTBIT(t, b) (t[(b) >> 3] & (1 << ((b) & 7)))
186 # define SETBIT(t, b) (t[(b) >> 3] |= (1 << ((b) & 7)))
187 # define CLEARBIT(t, b) (t[(b) >> 3] &= (0xFF & ~(1 << ((b) & 7))))
189 #define WITHIN_ARENA(p) \
190 ((char*)(p) >= sh.arena && (char*)(p) < &sh.arena[sh.arena_size])
191 #define WITHIN_FREELIST(p) \
192 ((char*)(p) >= (char*)sh.freelist && (char*)(p) < (char*)&sh.freelist[sh.freelist_size])
195 typedef struct sh_list_st
197 struct sh_list_st *next;
198 struct sh_list_st **p_next;
210 unsigned char *bittable;
211 unsigned char *bitmalloc;
212 int bittable_size; /* size in bits */
217 static int sh_getlist(char *ptr)
219 int list = sh.freelist_size - 1;
220 int bit = (sh.arena_size + ptr - sh.arena) / sh.minsize;
222 for (; bit; bit >>= 1, list--) {
223 if (TESTBIT(sh.bittable, bit))
225 OPENSSL_assert((bit & 1) == 0);
232 static int sh_testbit(char *ptr, int list, unsigned char *table)
236 OPENSSL_assert(list >= 0 && list < sh.freelist_size);
237 OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
238 bit = (1 << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
239 OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
240 return TESTBIT(table, bit);
243 static void sh_clearbit(char *ptr, int list, unsigned char *table)
247 OPENSSL_assert(list >= 0 && list < sh.freelist_size);
248 OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
249 bit = (1 << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
250 OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
251 OPENSSL_assert(TESTBIT(table, bit));
252 CLEARBIT(table, bit);
255 static void sh_setbit(char *ptr, int list, unsigned char *table)
259 OPENSSL_assert(list >= 0 && list < sh.freelist_size);
260 OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
261 bit = (1 << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
262 OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
263 OPENSSL_assert(!TESTBIT(table, bit));
267 static void sh_add_to_list(char **list, char *ptr)
271 OPENSSL_assert(WITHIN_FREELIST(list));
272 OPENSSL_assert(WITHIN_ARENA(ptr));
274 temp = (SH_LIST *)ptr;
275 temp->next = *(SH_LIST **)list;
276 OPENSSL_assert(temp->next == NULL || WITHIN_ARENA(temp->next));
277 temp->p_next = (SH_LIST **)list;
279 if (temp->next != NULL) {
280 OPENSSL_assert((char **)temp->next->p_next == list);
281 temp->next->p_next = &(temp->next);
287 static void sh_remove_from_list(char *ptr, char *list)
289 SH_LIST *temp, *temp2;
291 temp = (SH_LIST *)ptr;
292 if (temp->next != NULL)
293 temp->next->p_next = temp->p_next;
294 *temp->p_next = temp->next;
295 if (temp->next == NULL)
299 OPENSSL_assert(WITHIN_FREELIST(temp2->p_next) || WITHIN_ARENA(temp2->p_next));
303 static int sh_init(size_t size, int minsize)
309 memset(&sh, 0, sizeof sh);
311 /* make sure size and minsize are powers of 2 */
312 OPENSSL_assert(size > 0);
313 OPENSSL_assert((size & (size - 1)) == 0);
314 OPENSSL_assert(minsize > 0);
315 OPENSSL_assert((minsize & (minsize - 1)) == 0);
316 if (size <= 0 || (size & (size - 1)) != 0)
318 if (minsize <= 0 || (minsize & (minsize - 1)) != 0)
321 sh.arena_size = size;
322 sh.minsize = minsize;
323 sh.bittable_size = (sh.arena_size / sh.minsize) * 2;
325 sh.freelist_size = -1;
326 for (i = sh.bittable_size; i; i >>= 1)
329 sh.freelist = OPENSSL_zalloc(sh.freelist_size * sizeof (char *));
330 OPENSSL_assert(sh.freelist != NULL);
331 if (sh.freelist == NULL)
334 sh.bittable = OPENSSL_zalloc(sh.bittable_size >> 3);
335 OPENSSL_assert(sh.bittable != NULL);
336 if (sh.bittable == NULL)
339 sh.bitmalloc = OPENSSL_zalloc(sh.bittable_size >> 3);
340 OPENSSL_assert(sh.bitmalloc != NULL);
341 if (sh.bitmalloc == NULL)
344 /* Allocate space for heap, and two extra pages as guards */
345 #if defined(_SC_PAGE_SIZE) || defined (_SC_PAGESIZE)
347 # if defined(_SC_PAGE_SIZE)
348 long tmppgsize = sysconf(_SC_PAGE_SIZE);
350 long tmppgsize = sysconf(_SC_PAGESIZE);
355 pgsize = (size_t)tmppgsize;
360 sh.map_size = pgsize + sh.arena_size + pgsize;
363 sh.map_result = mmap(NULL, sh.map_size,
364 PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
369 sh.map_result = MAP_FAILED;
370 if ((fd = open("/dev/zero", O_RDWR)) >= 0) {
371 sh.map_result = mmap(NULL, sh.map_size,
372 PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
376 OPENSSL_assert(sh.map_result != MAP_FAILED);
377 if (sh.map_result == MAP_FAILED)
379 sh.arena = (char *)(sh.map_result + pgsize);
380 sh_setbit(sh.arena, 0, sh.bittable);
381 sh_add_to_list(&sh.freelist[0], sh.arena);
383 /* Now try to add guard pages and lock into memory. */
386 /* Starting guard is already aligned from mmap. */
387 if (mprotect(sh.map_result, pgsize, PROT_NONE) < 0)
390 /* Ending guard page - need to round up to page boundary */
391 aligned = (pgsize + sh.arena_size + (pgsize - 1)) & ~(pgsize - 1);
392 if (mprotect(sh.map_result + aligned, pgsize, PROT_NONE) < 0)
395 if (mlock(sh.arena, sh.arena_size) < 0)
398 if (madvise(sh.arena, sh.arena_size, MADV_DONTDUMP) < 0)
409 static void sh_done()
411 OPENSSL_free(sh.freelist);
412 OPENSSL_free(sh.bittable);
413 OPENSSL_free(sh.bitmalloc);
414 if (sh.map_result != NULL && sh.map_size)
415 munmap(sh.map_result, sh.map_size);
416 memset(&sh, 0, sizeof sh);
419 static int sh_allocated(const char *ptr)
421 return WITHIN_ARENA(ptr) ? 1 : 0;
424 static char *sh_find_my_buddy(char *ptr, int list)
429 bit = (1 << list) + (ptr - sh.arena) / (sh.arena_size >> list);
432 if (TESTBIT(sh.bittable, bit) && !TESTBIT(sh.bitmalloc, bit))
433 chunk = sh.arena + ((bit & ((1 << list) - 1)) * (sh.arena_size >> list));
438 static char *sh_malloc(size_t size)
444 list = sh.freelist_size - 1;
445 for (i = sh.minsize; i < size; i <<= 1)
450 /* try to find a larger entry to split */
451 for (slist = list; slist >= 0; slist--)
452 if (sh.freelist[slist] != NULL)
457 /* split larger entry */
458 while (slist != list) {
459 char *temp = sh.freelist[slist];
461 /* remove from bigger list */
462 OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
463 sh_clearbit(temp, slist, sh.bittable);
464 sh_remove_from_list(temp, sh.freelist[slist]);
465 OPENSSL_assert(temp != sh.freelist[slist]);
467 /* done with bigger list */
470 /* add to smaller list */
471 OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
472 sh_setbit(temp, slist, sh.bittable);
473 sh_add_to_list(&sh.freelist[slist], temp);
474 OPENSSL_assert(sh.freelist[slist] == temp);
477 temp += sh.arena_size >> slist;
478 OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
479 sh_setbit(temp, slist, sh.bittable);
480 sh_add_to_list(&sh.freelist[slist], temp);
481 OPENSSL_assert(sh.freelist[slist] == temp);
483 OPENSSL_assert(temp-(sh.arena_size >> slist) == sh_find_my_buddy(temp, slist));
486 /* peel off memory to hand back */
487 chunk = sh.freelist[list];
488 OPENSSL_assert(sh_testbit(chunk, list, sh.bittable));
489 sh_setbit(chunk, list, sh.bitmalloc);
490 sh_remove_from_list(chunk, sh.freelist[list]);
492 OPENSSL_assert(WITHIN_ARENA(chunk));
497 static void sh_free(char *ptr)
504 OPENSSL_assert(WITHIN_ARENA(ptr));
505 if (!WITHIN_ARENA(ptr))
508 list = sh_getlist(ptr);
509 OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
510 sh_clearbit(ptr, list, sh.bitmalloc);
511 sh_add_to_list(&sh.freelist[list], ptr);
513 /* Try to coalesce two adjacent free areas. */
514 while ((buddy = sh_find_my_buddy(ptr, list)) != NULL) {
515 OPENSSL_assert(ptr == sh_find_my_buddy(buddy, list));
516 OPENSSL_assert(ptr != NULL);
517 OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
518 sh_clearbit(ptr, list, sh.bittable);
519 sh_remove_from_list(ptr, sh.freelist[list]);
520 OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
521 sh_clearbit(buddy, list, sh.bittable);
522 sh_remove_from_list(buddy, sh.freelist[list]);
529 OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
530 sh_setbit(ptr, list, sh.bittable);
531 sh_add_to_list(&sh.freelist[list], ptr);
532 OPENSSL_assert(sh.freelist[list] == ptr);
536 static int sh_actual_size(char *ptr)
540 OPENSSL_assert(WITHIN_ARENA(ptr));
541 if (!WITHIN_ARENA(ptr))
543 list = sh_getlist(ptr);
544 OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
545 return sh.arena_size / (1 << list);
547 #endif /* IMPLEMENTED */