1 /* crypto/bn/bn_ctx.c */
2 /* Written by Ulf Moeller for the OpenSSL project. */
3 /* ====================================================================
4 * Copyright (c) 1998-2004 The OpenSSL Project. All rights reserved.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
18 * 3. All advertising materials mentioning features or use of this
19 * software must display the following acknowledgment:
20 * "This product includes software developed by the OpenSSL Project
21 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
23 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
24 * endorse or promote products derived from this software without
25 * prior written permission. For written permission, please contact
26 * openssl-core@openssl.org.
28 * 5. Products derived from this software may not be called "OpenSSL"
29 * nor may "OpenSSL" appear in their names without prior written
30 * permission of the OpenSSL Project.
32 * 6. Redistributions of any form whatsoever must retain the following
34 * "This product includes software developed by the OpenSSL Project
35 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
37 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
38 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
39 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
40 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
43 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
44 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
45 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
46 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
47 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
48 * OF THE POSSIBILITY OF SUCH DAMAGE.
49 * ====================================================================
51 * This product includes cryptographic software written by Eric Young
52 * (eay@cryptsoft.com). This product includes software written by Tim
53 * Hudson (tjh@cryptsoft.com).
57 #if !defined(BN_CTX_DEBUG) && !defined(BN_DEBUG)
72 * 1. Check a bunch of "(words+1)" type hacks in various bignum functions and
73 * check they can be safely removed.
74 * - Check +1 and other ugliness in BN_from_montgomery()
76 * 2. Consider allowing a BN_new_ex() that, at least, lets you specify an
77 * appropriate 'block' size that will be honoured by bn_expand_internal() to
78 * prevent piddly little reallocations. OTOH, profiling bignum expansions in
79 * BN_CTX doesn't show this to be a big issue.
82 /* How many bignums are in each "pool item"; */
83 #define BN_CTX_POOL_SIZE 16
84 /* The stack frame info is resizing, set a first-time expansion size; */
85 #define BN_CTX_START_FRAMES 32
91 /* A bundle of bignums that can be linked with other bundles */
92 typedef struct bignum_pool_item
94 /* The bignum values */
95 BIGNUM vals
[BN_CTX_POOL_SIZE
];
96 /* Linked-list admin */
97 struct bignum_pool_item
*prev
, *next
;
99 /* A linked-list of bignums grouped in bundles */
100 typedef struct bignum_pool
102 /* Linked-list admin */
103 BN_POOL_ITEM
*head
, *current
, *tail
;
104 /* Stack depth and allocation size */
107 static void BN_POOL_init(BN_POOL
*);
108 static void BN_POOL_finish(BN_POOL
*);
109 #ifndef OPENSSL_NO_DEPRECATED
110 static void BN_POOL_reset(BN_POOL
*);
112 static BIGNUM
* BN_POOL_get(BN_POOL
*);
113 static void BN_POOL_release(BN_POOL
*, unsigned int);
119 /* A wrapper to manage the "stack frames" */
120 typedef struct bignum_ctx_stack
122 /* Array of indexes into the bignum stack */
123 unsigned int *indexes
;
124 /* Number of stack frames, and the size of the allocated array */
125 unsigned int depth
, size
;
127 static void BN_STACK_init(BN_STACK
*);
128 static void BN_STACK_finish(BN_STACK
*);
129 #ifndef OPENSSL_NO_DEPRECATED
130 static void BN_STACK_reset(BN_STACK
*);
132 static int BN_STACK_push(BN_STACK
*, unsigned int);
133 static unsigned int BN_STACK_pop(BN_STACK
*);
139 /* The opaque BN_CTX type */
142 /* The bignum bundles */
144 /* The "stack frames", if you will */
146 /* The number of bignums currently assigned */
148 /* Depth of stack overflow */
150 /* Block "gets" until an "end" (compatibility behaviour) */
154 /* Enable this to find BN_CTX bugs */
156 static const char *ctxdbg_cur
= NULL
;
157 static void ctxdbg(BN_CTX
*ctx
)
159 unsigned int bnidx
= 0, fpidx
= 0;
160 BN_POOL_ITEM
*item
= ctx
->pool
.head
;
161 BN_STACK
*stack
= &ctx
->stack
;
162 fprintf(stderr
,"(%08x): ", (unsigned int)ctx
);
163 while(bnidx
< ctx
->used
)
165 fprintf(stderr
,"%03x ", item
->vals
[bnidx
++ % BN_CTX_POOL_SIZE
].dmax
);
166 if(!(bnidx
% BN_CTX_POOL_SIZE
))
169 fprintf(stderr
,"\n");
171 fprintf(stderr
," : ");
172 while(fpidx
< stack
->depth
)
174 while(bnidx
++ < stack
->indexes
[fpidx
])
176 fprintf(stderr
,"^^^ ");
180 fprintf(stderr
,"\n");
182 #define CTXDBG_ENTRY(str, ctx) do { \
183 ctxdbg_cur = (str); \
184 fprintf(stderr,"Starting %s\n", ctxdbg_cur); \
187 #define CTXDBG_EXIT(ctx) do { \
188 fprintf(stderr,"Ending %s\n", ctxdbg_cur); \
191 #define CTXDBG_RET(ctx,ret)
193 #define CTXDBG_ENTRY(str, ctx)
194 #define CTXDBG_EXIT(ctx)
195 #define CTXDBG_RET(ctx,ret)
198 /* This function is an evil legacy and should not be used. This implementation
199 * is WYSIWYG, though I've done my best. */
200 #ifndef OPENSSL_NO_DEPRECATED
201 void BN_CTX_init(BN_CTX
*ctx
)
203 /* Assume the caller obtained the context via BN_CTX_new() and so is
204 * trying to reset it for use. Nothing else makes sense, least of all
205 * binary compatibility from a time when they could declare a static
207 BN_POOL_reset(&ctx
->pool
);
208 BN_STACK_reset(&ctx
->stack
);
215 BN_CTX
*BN_CTX_new(void)
217 BN_CTX
*ret
= OPENSSL_malloc(sizeof(BN_CTX
));
220 BNerr(BN_F_BN_CTX_NEW
,ERR_R_MALLOC_FAILURE
);
223 /* Initialise the structure */
224 BN_POOL_init(&ret
->pool
);
225 BN_STACK_init(&ret
->stack
);
232 void BN_CTX_free(BN_CTX
*ctx
)
238 BN_POOL_ITEM
*pool
= ctx
->pool
.head
;
239 fprintf(stderr
,"BN_CTX_free, stack-size=%d, pool-bignums=%d\n",
240 ctx
->stack
.size
, ctx
->pool
.size
);
241 fprintf(stderr
,"dmaxs: ");
244 while(loop
< BN_CTX_POOL_SIZE
)
245 fprintf(stderr
,"%02x ", pool
->vals
[loop
++].dmax
);
248 fprintf(stderr
,"\n");
251 BN_STACK_finish(&ctx
->stack
);
252 BN_POOL_finish(&ctx
->pool
);
256 void BN_CTX_start(BN_CTX
*ctx
)
258 CTXDBG_ENTRY("BN_CTX_start", ctx
);
259 /* If we're already overflowing ... */
260 if(ctx
->err_stack
|| ctx
->too_many
)
262 /* (Try to) get a new frame pointer */
263 else if(!BN_STACK_push(&ctx
->stack
, ctx
->used
))
265 BNerr(BN_F_BN_CTX_START
,BN_R_TOO_MANY_TEMPORARY_VARIABLES
);
271 void BN_CTX_end(BN_CTX
*ctx
)
273 CTXDBG_ENTRY("BN_CTX_end", ctx
);
278 unsigned int fp
= BN_STACK_pop(&ctx
->stack
);
279 /* Does this stack frame have anything to release? */
281 BN_POOL_release(&ctx
->pool
, ctx
->used
- fp
);
283 /* Unjam "too_many" in case "get" had failed */
289 BIGNUM
*BN_CTX_get(BN_CTX
*ctx
)
292 CTXDBG_ENTRY("BN_CTX_get", ctx
);
293 if(ctx
->err_stack
|| ctx
->too_many
) return NULL
;
294 if((ret
= BN_POOL_get(&ctx
->pool
)) == NULL
)
296 /* Setting too_many prevents repeated "get" attempts from
297 * cluttering the error stack. */
299 BNerr(BN_F_BN_CTX_GET
,BN_R_TOO_MANY_TEMPORARY_VARIABLES
);
302 /* OK, make sure the returned bignum is "zero" */
305 CTXDBG_RET(ctx
, ret
);
313 static void BN_STACK_init(BN_STACK
*st
)
316 st
->depth
= st
->size
= 0;
319 static void BN_STACK_finish(BN_STACK
*st
)
321 if(st
->size
) OPENSSL_free(st
->indexes
);
324 #ifndef OPENSSL_NO_DEPRECATED
325 static void BN_STACK_reset(BN_STACK
*st
)
331 static int BN_STACK_push(BN_STACK
*st
, unsigned int idx
)
333 if(st
->depth
== st
->size
)
336 unsigned int newsize
= (st
->size
?
337 (st
->size
* 3 / 2) : BN_CTX_START_FRAMES
);
338 unsigned int *newitems
= OPENSSL_malloc(newsize
*
339 sizeof(unsigned int));
340 if(!newitems
) return 0;
342 memcpy(newitems
, st
->indexes
, st
->depth
*
343 sizeof(unsigned int));
344 if(st
->size
) OPENSSL_free(st
->indexes
);
345 st
->indexes
= newitems
;
348 st
->indexes
[(st
->depth
)++] = idx
;
352 static unsigned int BN_STACK_pop(BN_STACK
*st
)
354 return st
->indexes
[--(st
->depth
)];
361 static void BN_POOL_init(BN_POOL
*p
)
363 p
->head
= p
->current
= p
->tail
= NULL
;
364 p
->used
= p
->size
= 0;
367 static void BN_POOL_finish(BN_POOL
*p
)
371 unsigned int loop
= 0;
372 BIGNUM
*bn
= p
->head
->vals
;
373 while(loop
++ < BN_CTX_POOL_SIZE
)
375 if(bn
->d
) BN_clear_free(bn
);
378 p
->current
= p
->head
->next
;
379 OPENSSL_free(p
->head
);
380 p
->head
= p
->current
;
384 #ifndef OPENSSL_NO_DEPRECATED
385 static void BN_POOL_reset(BN_POOL
*p
)
387 BN_POOL_ITEM
*item
= p
->head
;
390 unsigned int loop
= 0;
391 BIGNUM
*bn
= item
->vals
;
392 while(loop
++ < BN_CTX_POOL_SIZE
)
394 if(bn
->d
) BN_clear(bn
);
399 p
->current
= p
->head
;
404 static BIGNUM
*BN_POOL_get(BN_POOL
*p
)
406 if(p
->used
== p
->size
)
409 unsigned int loop
= 0;
410 BN_POOL_ITEM
*item
= OPENSSL_malloc(sizeof(BN_POOL_ITEM
));
411 if(!item
) return NULL
;
412 /* Initialise the structure */
414 while(loop
++ < BN_CTX_POOL_SIZE
)
416 item
->prev
= p
->tail
;
420 p
->head
= p
->current
= p
->tail
= item
;
423 p
->tail
->next
= item
;
427 p
->size
+= BN_CTX_POOL_SIZE
;
429 /* Return the first bignum from the new pool */
433 p
->current
= p
->head
;
434 else if((p
->used
% BN_CTX_POOL_SIZE
) == 0)
435 p
->current
= p
->current
->next
;
436 return p
->current
->vals
+ ((p
->used
++) % BN_CTX_POOL_SIZE
);
439 static void BN_POOL_release(BN_POOL
*p
, unsigned int num
)
441 unsigned int offset
= (p
->used
- 1) % BN_CTX_POOL_SIZE
;
445 bn_check_top(p
->current
->vals
+ offset
);
448 offset
= BN_CTX_POOL_SIZE
- 1;
449 p
->current
= p
->current
->prev
;