1 /* Written by Ulf Moeller for the OpenSSL project. */
2 /* ====================================================================
3 * Copyright (c) 1998-2004 The OpenSSL Project. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in
14 * the documentation and/or other materials provided with the
15 * distribution.
16 *
17 * 3. All advertising materials mentioning features or use of this
18 * software must display the following acknowledgment:
19 * "This product includes software developed by the OpenSSL Project
20 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
21 *
22 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
23 * endorse or promote products derived from this software without
24 * prior written permission. For written permission, please contact
25 * openssl-core@openssl.org.
26 *
27 * 5. Products derived from this software may not be called "OpenSSL"
28 * nor may "OpenSSL" appear in their names without prior written
29 * permission of the OpenSSL Project.
30 *
31 * 6. Redistributions of any form whatsoever must retain the following
32 * acknowledgment:
33 * "This product includes software developed by the OpenSSL Project
34 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
35 *
36 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
37 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
38 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
39 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
40 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
41 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
42 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
43 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
45 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
46 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
47 * OF THE POSSIBILITY OF SUCH DAMAGE.
48 * ====================================================================
49 *
50 * This product includes cryptographic software written by Eric Young
51 * (eay@cryptsoft.com). This product includes software written by Tim
52 * Hudson (tjh@cryptsoft.com). */
53
54
55 #include <openssl/bn.h>
56
57 #include <openssl/err.h>
58 #include <openssl/mem.h>
59
60
61 /* How many bignums are in each "pool item"; */
62 #define BN_CTX_POOL_SIZE 16
63 /* The stack frame info is resizing, set a first-time expansion size; */
64 #define BN_CTX_START_FRAMES 32
65
66 /* A bundle of bignums that can be linked with other bundles */
67 typedef struct bignum_pool_item {
68 /* The bignum values */
69 BIGNUM vals[BN_CTX_POOL_SIZE];
70 /* Linked-list admin */
71 struct bignum_pool_item *prev, *next;
72 } BN_POOL_ITEM;
73
74
75 typedef struct bignum_pool {
76 /* Linked-list admin */
77 BN_POOL_ITEM *head, *current, *tail;
78 /* Stack depth and allocation size */
79 unsigned used, size;
80 } BN_POOL;
81
82 static void BN_POOL_init(BN_POOL *);
83 static void BN_POOL_finish(BN_POOL *);
84 static BIGNUM *BN_POOL_get(BN_POOL *);
85 static void BN_POOL_release(BN_POOL *, unsigned int);
86
87 /************/
88 /* BN_STACK */
89 /************/
90
91 /* A wrapper to manage the "stack frames" */
92 typedef struct bignum_ctx_stack {
93 /* Array of indexes into the bignum stack */
94 unsigned int *indexes;
95 /* Number of stack frames, and the size of the allocated array */
96 unsigned int depth, size;
97 } BN_STACK;
98
99 static void BN_STACK_init(BN_STACK *);
100 static void BN_STACK_finish(BN_STACK *);
101 static int BN_STACK_push(BN_STACK *, unsigned int);
102 static unsigned int BN_STACK_pop(BN_STACK *);
103
104 /**********/
105 /* BN_CTX */
106 /**********/
107
108 /* The opaque BN_CTX type */
109 struct bignum_ctx {
110 /* The bignum bundles */
111 BN_POOL pool;
112 /* The "stack frames", if you will */
113 BN_STACK stack;
114 /* The number of bignums currently assigned */
115 unsigned int used;
116 /* Depth of stack overflow */
117 int err_stack;
118 /* Block "gets" until an "end" (compatibility behaviour) */
119 int too_many;
120 };
121
BN_CTX_new(void)122 BN_CTX *BN_CTX_new(void) {
123 BN_CTX *ret = OPENSSL_malloc(sizeof(BN_CTX));
124 if (!ret) {
125 OPENSSL_PUT_ERROR(BN, BN_CTX_new, ERR_R_MALLOC_FAILURE);
126 return NULL;
127 }
128
129 /* Initialise the structure */
130 BN_POOL_init(&ret->pool);
131 BN_STACK_init(&ret->stack);
132 ret->used = 0;
133 ret->err_stack = 0;
134 ret->too_many = 0;
135 return ret;
136 }
137
BN_CTX_free(BN_CTX * ctx)138 void BN_CTX_free(BN_CTX *ctx) {
139 if (ctx == NULL) {
140 return;
141 }
142
143 BN_STACK_finish(&ctx->stack);
144 BN_POOL_finish(&ctx->pool);
145 OPENSSL_free(ctx);
146 }
147
BN_CTX_start(BN_CTX * ctx)148 void BN_CTX_start(BN_CTX *ctx) {
149 /* If we're already overflowing ... */
150 if (ctx->err_stack || ctx->too_many) {
151 ctx->err_stack++;
152 } else if (!BN_STACK_push(&ctx->stack, ctx->used)) {
153 /* (Try to) get a new frame pointer */
154 OPENSSL_PUT_ERROR(BN, BN_CTX_start, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
155 ctx->err_stack++;
156 }
157 }
158
BN_CTX_get(BN_CTX * ctx)159 BIGNUM *BN_CTX_get(BN_CTX *ctx) {
160 BIGNUM *ret;
161 if (ctx->err_stack || ctx->too_many) {
162 return NULL;
163 }
164
165 ret = BN_POOL_get(&ctx->pool);
166 if (ret == NULL) {
167 /* Setting too_many prevents repeated "get" attempts from
168 * cluttering the error stack. */
169 ctx->too_many = 1;
170 OPENSSL_PUT_ERROR(BN, BN_CTX_get, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
171 return NULL;
172 }
173
174 /* OK, make sure the returned bignum is "zero" */
175 BN_zero(ret);
176 ctx->used++;
177 return ret;
178 }
179
BN_CTX_end(BN_CTX * ctx)180 void BN_CTX_end(BN_CTX *ctx) {
181 if (ctx->err_stack) {
182 ctx->err_stack--;
183 } else {
184 unsigned int fp = BN_STACK_pop(&ctx->stack);
185 /* Does this stack frame have anything to release? */
186 if (fp < ctx->used) {
187 BN_POOL_release(&ctx->pool, ctx->used - fp);
188 }
189
190 ctx->used = fp;
191 /* Unjam "too_many" in case "get" had failed */
192 ctx->too_many = 0;
193 }
194 }
195
196 /************/
197 /* BN_STACK */
198 /************/
199
BN_STACK_init(BN_STACK * st)200 static void BN_STACK_init(BN_STACK *st) {
201 st->indexes = NULL;
202 st->depth = st->size = 0;
203 }
204
BN_STACK_finish(BN_STACK * st)205 static void BN_STACK_finish(BN_STACK *st) {
206 if (st->size)
207 OPENSSL_free(st->indexes);
208 }
209
BN_STACK_push(BN_STACK * st,unsigned int idx)210 static int BN_STACK_push(BN_STACK *st, unsigned int idx) {
211 if (st->depth == st->size)
212 /* Need to expand */
213 {
214 unsigned int newsize =
215 (st->size ? (st->size * 3 / 2) : BN_CTX_START_FRAMES);
216 unsigned int *newitems = OPENSSL_malloc(newsize * sizeof(unsigned int));
217 if (!newitems) {
218 return 0;
219 }
220 if (st->depth) {
221 memcpy(newitems, st->indexes, st->depth * sizeof(unsigned int));
222 }
223 if (st->size) {
224 OPENSSL_free(st->indexes);
225 }
226 st->indexes = newitems;
227 st->size = newsize;
228 }
229
230 st->indexes[(st->depth)++] = idx;
231 return 1;
232 }
233
BN_STACK_pop(BN_STACK * st)234 static unsigned int BN_STACK_pop(BN_STACK *st) {
235 return st->indexes[--(st->depth)];
236 }
237
BN_POOL_init(BN_POOL * p)238 static void BN_POOL_init(BN_POOL *p) {
239 p->head = p->current = p->tail = NULL;
240 p->used = p->size = 0;
241 }
242
BN_POOL_finish(BN_POOL * p)243 static void BN_POOL_finish(BN_POOL *p) {
244 while (p->head) {
245 unsigned int loop = 0;
246 BIGNUM *bn = p->head->vals;
247 while (loop++ < BN_CTX_POOL_SIZE) {
248 if (bn->d) {
249 BN_clear_free(bn);
250 }
251 bn++;
252 }
253
254 p->current = p->head->next;
255 OPENSSL_free(p->head);
256 p->head = p->current;
257 }
258 }
259
BN_POOL_get(BN_POOL * p)260 static BIGNUM *BN_POOL_get(BN_POOL *p) {
261 if (p->used == p->size) {
262 BIGNUM *bn;
263 unsigned int loop = 0;
264 BN_POOL_ITEM *item = OPENSSL_malloc(sizeof(BN_POOL_ITEM));
265 if (!item) {
266 return NULL;
267 }
268
269 /* Initialise the structure */
270 bn = item->vals;
271 while (loop++ < BN_CTX_POOL_SIZE) {
272 BN_init(bn++);
273 }
274
275 item->prev = p->tail;
276 item->next = NULL;
277 /* Link it in */
278 if (!p->head) {
279 p->head = p->current = p->tail = item;
280 } else {
281 p->tail->next = item;
282 p->tail = item;
283 p->current = item;
284 }
285
286 p->size += BN_CTX_POOL_SIZE;
287 p->used++;
288 /* Return the first bignum from the new pool */
289 return item->vals;
290 }
291
292 if (!p->used) {
293 p->current = p->head;
294 } else if ((p->used % BN_CTX_POOL_SIZE) == 0) {
295 p->current = p->current->next;
296 }
297
298 return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE);
299 }
300
BN_POOL_release(BN_POOL * p,unsigned int num)301 static void BN_POOL_release(BN_POOL *p, unsigned int num) {
302 unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE;
303 p->used -= num;
304
305 while (num--) {
306 if (!offset) {
307 offset = BN_CTX_POOL_SIZE - 1;
308 p->current = p->current->prev;
309 } else {
310 offset--;
311 }
312 }
313 }
314