2 * Copyright 2015-2017 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the OpenSSL license (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
11 * Copyright 2004-2014, Akamai Technologies. All Rights Reserved.
12 * This file is distributed under the terms of the OpenSSL license.
16 * This file is in two halves. The first half implements the public API
17 * to be used by external consumers, and to be used by OpenSSL to store
18 * data in a "secure arena." The second half implements the secure arena.
19 * For details on that implementation, see below (look for uppercase
20 * "SECURE HEAP IMPLEMENTATION").
22 #include <openssl/crypto.h>
27 #if defined(OPENSSL_SYS_LINUX) || defined(OPENSSL_SYS_UNIX)
32 # include <sys/types.h>
33 # include <sys/mman.h>
34 # include <sys/param.h>
35 # include <sys/stat.h>
39 #define CLEAR(p, s) OPENSSL_cleanse(p, s)
41 # define PAGE_SIZE 4096
45 static size_t secure_mem_used;
47 static int secure_mem_initialized;
49 static CRYPTO_RWLOCK *sec_malloc_lock = NULL;
52 * These are the functions that must be implemented by a secure heap (sh).
54 static int sh_init(size_t size, int minsize);
55 static char *sh_malloc(size_t size);
56 static void sh_free(char *ptr);
57 static void sh_done(void);
58 static size_t sh_actual_size(char *ptr);
59 static int sh_allocated(const char *ptr);
62 int CRYPTO_secure_malloc_init(size_t size, int minsize)
67 if (!secure_mem_initialized) {
68 sec_malloc_lock = CRYPTO_THREAD_lock_new();
69 if (sec_malloc_lock == NULL)
71 ret = sh_init(size, minsize);
72 secure_mem_initialized = 1;
78 #endif /* IMPLEMENTED */
81 int CRYPTO_secure_malloc_done()
84 if (secure_mem_used == 0) {
86 secure_mem_initialized = 0;
87 CRYPTO_THREAD_lock_free(sec_malloc_lock);
90 #endif /* IMPLEMENTED */
94 int CRYPTO_secure_malloc_initialized()
97 return secure_mem_initialized;
100 #endif /* IMPLEMENTED */
103 void *CRYPTO_secure_malloc(size_t num, const char *file, int line)
109 if (!secure_mem_initialized) {
110 return CRYPTO_malloc(num, file, line);
112 CRYPTO_THREAD_write_lock(sec_malloc_lock);
113 ret = sh_malloc(num);
114 actual_size = ret ? sh_actual_size(ret) : 0;
115 secure_mem_used += actual_size;
116 CRYPTO_THREAD_unlock(sec_malloc_lock);
119 return CRYPTO_malloc(num, file, line);
120 #endif /* IMPLEMENTED */
123 void *CRYPTO_secure_zalloc(size_t num, const char *file, int line)
125 void *ret = CRYPTO_secure_malloc(num, file, line);
132 void CRYPTO_secure_free(void *ptr, const char *file, int line)
139 if (!CRYPTO_secure_allocated(ptr)) {
140 CRYPTO_free(ptr, file, line);
143 CRYPTO_THREAD_write_lock(sec_malloc_lock);
144 actual_size = sh_actual_size(ptr);
145 CLEAR(ptr, actual_size);
146 secure_mem_used -= actual_size;
148 CRYPTO_THREAD_unlock(sec_malloc_lock);
150 CRYPTO_free(ptr, file, line);
151 #endif /* IMPLEMENTED */
154 int CRYPTO_secure_allocated(const void *ptr)
159 if (!secure_mem_initialized)
161 CRYPTO_THREAD_write_lock(sec_malloc_lock);
162 ret = sh_allocated(ptr);
163 CRYPTO_THREAD_unlock(sec_malloc_lock);
167 #endif /* IMPLEMENTED */
170 size_t CRYPTO_secure_used()
173 return secure_mem_used;
176 #endif /* IMPLEMENTED */
179 size_t CRYPTO_secure_actual_size(void *ptr)
184 CRYPTO_THREAD_write_lock(sec_malloc_lock);
185 actual_size = sh_actual_size(ptr);
186 CRYPTO_THREAD_unlock(sec_malloc_lock);
197 * SECURE HEAP IMPLEMENTATION
203 * The implementation provided here uses a fixed-sized mmap() heap,
204 * which is locked into memory, not written to core files, and protected
205 * on either side by an unmapped page, which will catch pointer overruns
206 * (or underruns) and an attempt to read data out of the secure heap.
207 * Free'd memory is zero'd or otherwise cleansed.
209 * This is a pretty standard buddy allocator. We keep areas in a multiple
210 * of "sh.minsize" units. The freelist and bitmaps are kept separately,
211 * so all (and only) data is kept in the mmap'd heap.
213 * This code assumes eight-bit bytes. The numbers 3 and 7 are all over the
217 #define ONE ((size_t)1)
219 # define TESTBIT(t, b) (t[(b) >> 3] & (ONE << ((b) & 7)))
220 # define SETBIT(t, b) (t[(b) >> 3] |= (ONE << ((b) & 7)))
221 # define CLEARBIT(t, b) (t[(b) >> 3] &= (0xFF & ~(ONE << ((b) & 7))))
223 #define WITHIN_ARENA(p) \
224 ((char*)(p) >= sh.arena && (char*)(p) < &sh.arena[sh.arena_size])
225 #define WITHIN_FREELIST(p) \
226 ((char*)(p) >= (char*)sh.freelist && (char*)(p) < (char*)&sh.freelist[sh.freelist_size])
229 typedef struct sh_list_st
231 struct sh_list_st *next;
232 struct sh_list_st **p_next;
242 ossl_ssize_t freelist_size;
244 unsigned char *bittable;
245 unsigned char *bitmalloc;
246 size_t bittable_size; /* size in bits */
251 static size_t sh_getlist(char *ptr)
253 ossl_ssize_t list = sh.freelist_size - 1;
254 size_t bit = (sh.arena_size + ptr - sh.arena) / sh.minsize;
256 for (; bit; bit >>= 1, list--) {
257 if (TESTBIT(sh.bittable, bit))
259 OPENSSL_assert((bit & 1) == 0);
266 static int sh_testbit(char *ptr, int list, unsigned char *table)
270 OPENSSL_assert(list >= 0 && list < sh.freelist_size);
271 OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
272 bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
273 OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
274 return TESTBIT(table, bit);
277 static void sh_clearbit(char *ptr, int list, unsigned char *table)
281 OPENSSL_assert(list >= 0 && list < sh.freelist_size);
282 OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
283 bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
284 OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
285 OPENSSL_assert(TESTBIT(table, bit));
286 CLEARBIT(table, bit);
289 static void sh_setbit(char *ptr, int list, unsigned char *table)
293 OPENSSL_assert(list >= 0 && list < sh.freelist_size);
294 OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
295 bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
296 OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
297 OPENSSL_assert(!TESTBIT(table, bit));
301 static void sh_add_to_list(char **list, char *ptr)
305 OPENSSL_assert(WITHIN_FREELIST(list));
306 OPENSSL_assert(WITHIN_ARENA(ptr));
308 temp = (SH_LIST *)ptr;
309 temp->next = *(SH_LIST **)list;
310 OPENSSL_assert(temp->next == NULL || WITHIN_ARENA(temp->next));
311 temp->p_next = (SH_LIST **)list;
313 if (temp->next != NULL) {
314 OPENSSL_assert((char **)temp->next->p_next == list);
315 temp->next->p_next = &(temp->next);
321 static void sh_remove_from_list(char *ptr)
323 SH_LIST *temp, *temp2;
325 temp = (SH_LIST *)ptr;
326 if (temp->next != NULL)
327 temp->next->p_next = temp->p_next;
328 *temp->p_next = temp->next;
329 if (temp->next == NULL)
333 OPENSSL_assert(WITHIN_FREELIST(temp2->p_next) || WITHIN_ARENA(temp2->p_next));
337 static int sh_init(size_t size, int minsize)
343 memset(&sh, 0, sizeof sh);
345 /* make sure size and minsize are powers of 2 */
346 OPENSSL_assert(size > 0);
347 OPENSSL_assert((size & (size - 1)) == 0);
348 OPENSSL_assert(minsize > 0);
349 OPENSSL_assert((minsize & (minsize - 1)) == 0);
350 if (size <= 0 || (size & (size - 1)) != 0)
352 if (minsize <= 0 || (minsize & (minsize - 1)) != 0)
355 while (minsize < (int)sizeof(SH_LIST))
358 sh.arena_size = size;
359 sh.minsize = minsize;
360 sh.bittable_size = (sh.arena_size / sh.minsize) * 2;
362 /* Prevent allocations of size 0 later on */
363 if (sh.bittable_size >> 3 == 0)
366 sh.freelist_size = -1;
367 for (i = sh.bittable_size; i; i >>= 1)
370 sh.freelist = OPENSSL_zalloc(sh.freelist_size * sizeof (char *));
371 OPENSSL_assert(sh.freelist != NULL);
372 if (sh.freelist == NULL)
375 sh.bittable = OPENSSL_zalloc(sh.bittable_size >> 3);
376 OPENSSL_assert(sh.bittable != NULL);
377 if (sh.bittable == NULL)
380 sh.bitmalloc = OPENSSL_zalloc(sh.bittable_size >> 3);
381 OPENSSL_assert(sh.bitmalloc != NULL);
382 if (sh.bitmalloc == NULL)
385 /* Allocate space for heap, and two extra pages as guards */
386 #if defined(_SC_PAGE_SIZE) || defined (_SC_PAGESIZE)
388 # if defined(_SC_PAGE_SIZE)
389 long tmppgsize = sysconf(_SC_PAGE_SIZE);
391 long tmppgsize = sysconf(_SC_PAGESIZE);
396 pgsize = (size_t)tmppgsize;
401 sh.map_size = pgsize + sh.arena_size + pgsize;
404 sh.map_result = mmap(NULL, sh.map_size,
405 PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
410 sh.map_result = MAP_FAILED;
411 if ((fd = open("/dev/zero", O_RDWR)) >= 0) {
412 sh.map_result = mmap(NULL, sh.map_size,
413 PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
417 OPENSSL_assert(sh.map_result != MAP_FAILED);
418 if (sh.map_result == MAP_FAILED)
420 sh.arena = (char *)(sh.map_result + pgsize);
421 sh_setbit(sh.arena, 0, sh.bittable);
422 sh_add_to_list(&sh.freelist[0], sh.arena);
424 /* Now try to add guard pages and lock into memory. */
427 /* Starting guard is already aligned from mmap. */
428 if (mprotect(sh.map_result, pgsize, PROT_NONE) < 0)
431 /* Ending guard page - need to round up to page boundary */
432 aligned = (pgsize + sh.arena_size + (pgsize - 1)) & ~(pgsize - 1);
433 if (mprotect(sh.map_result + aligned, pgsize, PROT_NONE) < 0)
436 if (mlock(sh.arena, sh.arena_size) < 0)
439 if (madvise(sh.arena, sh.arena_size, MADV_DONTDUMP) < 0)
450 static void sh_done()
452 OPENSSL_free(sh.freelist);
453 OPENSSL_free(sh.bittable);
454 OPENSSL_free(sh.bitmalloc);
455 if (sh.map_result != NULL && sh.map_size)
456 munmap(sh.map_result, sh.map_size);
457 memset(&sh, 0, sizeof sh);
460 static int sh_allocated(const char *ptr)
462 return WITHIN_ARENA(ptr) ? 1 : 0;
465 static char *sh_find_my_buddy(char *ptr, int list)
470 bit = (ONE << list) + (ptr - sh.arena) / (sh.arena_size >> list);
473 if (TESTBIT(sh.bittable, bit) && !TESTBIT(sh.bitmalloc, bit))
474 chunk = sh.arena + ((bit & ((ONE << list) - 1)) * (sh.arena_size >> list));
479 static char *sh_malloc(size_t size)
481 ossl_ssize_t list, slist;
485 list = sh.freelist_size - 1;
486 for (i = sh.minsize; i < size; i <<= 1)
491 /* try to find a larger entry to split */
492 for (slist = list; slist >= 0; slist--)
493 if (sh.freelist[slist] != NULL)
498 /* split larger entry */
499 while (slist != list) {
500 char *temp = sh.freelist[slist];
502 /* remove from bigger list */
503 OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
504 sh_clearbit(temp, slist, sh.bittable);
505 sh_remove_from_list(temp);
506 OPENSSL_assert(temp != sh.freelist[slist]);
508 /* done with bigger list */
511 /* add to smaller list */
512 OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
513 sh_setbit(temp, slist, sh.bittable);
514 sh_add_to_list(&sh.freelist[slist], temp);
515 OPENSSL_assert(sh.freelist[slist] == temp);
518 temp += sh.arena_size >> slist;
519 OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
520 sh_setbit(temp, slist, sh.bittable);
521 sh_add_to_list(&sh.freelist[slist], temp);
522 OPENSSL_assert(sh.freelist[slist] == temp);
524 OPENSSL_assert(temp-(sh.arena_size >> slist) == sh_find_my_buddy(temp, slist));
527 /* peel off memory to hand back */
528 chunk = sh.freelist[list];
529 OPENSSL_assert(sh_testbit(chunk, list, sh.bittable));
530 sh_setbit(chunk, list, sh.bitmalloc);
531 sh_remove_from_list(chunk);
533 OPENSSL_assert(WITHIN_ARENA(chunk));
538 static void sh_free(char *ptr)
545 OPENSSL_assert(WITHIN_ARENA(ptr));
546 if (!WITHIN_ARENA(ptr))
549 list = sh_getlist(ptr);
550 OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
551 sh_clearbit(ptr, list, sh.bitmalloc);
552 sh_add_to_list(&sh.freelist[list], ptr);
554 /* Try to coalesce two adjacent free areas. */
555 while ((buddy = sh_find_my_buddy(ptr, list)) != NULL) {
556 OPENSSL_assert(ptr == sh_find_my_buddy(buddy, list));
557 OPENSSL_assert(ptr != NULL);
558 OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
559 sh_clearbit(ptr, list, sh.bittable);
560 sh_remove_from_list(ptr);
561 OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
562 sh_clearbit(buddy, list, sh.bittable);
563 sh_remove_from_list(buddy);
570 OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
571 sh_setbit(ptr, list, sh.bittable);
572 sh_add_to_list(&sh.freelist[list], ptr);
573 OPENSSL_assert(sh.freelist[list] == ptr);
577 static size_t sh_actual_size(char *ptr)
581 OPENSSL_assert(WITHIN_ARENA(ptr));
582 if (!WITHIN_ARENA(ptr))
584 list = sh_getlist(ptr);
585 OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
586 return sh.arena_size / (ONE << list);
588 #endif /* IMPLEMENTED */