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 <assert.h>
58 #include <string.h>
59
60 #include <openssl/err.h>
61 #include <openssl/mem.h>
62
63 #include "../../internal.h"
64
65
66 // The stack frame info is resizing, set a first-time expansion size;
67 #define BN_CTX_START_FRAMES 32
68
69
70 // BN_STACK
71
72 // A |BN_STACK| is a stack of |size_t| values.
73 typedef struct {
74 // Array of indexes into |ctx->bignums|.
75 size_t *indexes;
76 // Number of stack frames, and the size of the allocated array
77 size_t depth, size;
78 } BN_STACK;
79
80 static void BN_STACK_init(BN_STACK *);
81 static void BN_STACK_cleanup(BN_STACK *);
82 static int BN_STACK_push(BN_STACK *, size_t idx);
83 static size_t BN_STACK_pop(BN_STACK *);
84
85
86 // BN_CTX
87
88 DEFINE_STACK_OF(BIGNUM)
89
90 // The opaque BN_CTX type
91 struct bignum_ctx {
92 // bignums is the stack of |BIGNUM|s managed by this |BN_CTX|.
93 STACK_OF(BIGNUM) *bignums;
94 // stack is the stack of |BN_CTX_start| frames. It is the value of |used| at
95 // the time |BN_CTX_start| was called.
96 BN_STACK stack;
97 // used is the number of |BIGNUM|s from |bignums| that have been used.
98 size_t used;
99 // error is one if any operation on this |BN_CTX| failed. All subsequent
100 // operations will fail.
101 char error;
102 // defer_error is one if an operation on this |BN_CTX| has failed, but no
103 // error has been pushed to the queue yet. This is used to defer errors from
104 // |BN_CTX_start| to |BN_CTX_get|.
105 char defer_error;
106 };
107
BN_CTX_new(void)108 BN_CTX *BN_CTX_new(void) {
109 BN_CTX *ret = OPENSSL_malloc(sizeof(BN_CTX));
110 if (!ret) {
111 OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
112 return NULL;
113 }
114
115 // Initialise the structure
116 ret->bignums = NULL;
117 BN_STACK_init(&ret->stack);
118 ret->used = 0;
119 ret->error = 0;
120 ret->defer_error = 0;
121 return ret;
122 }
123
BN_CTX_free(BN_CTX * ctx)124 void BN_CTX_free(BN_CTX *ctx) {
125 if (ctx == NULL) {
126 return;
127 }
128
129 sk_BIGNUM_pop_free(ctx->bignums, BN_free);
130 BN_STACK_cleanup(&ctx->stack);
131 OPENSSL_free(ctx);
132 }
133
BN_CTX_start(BN_CTX * ctx)134 void BN_CTX_start(BN_CTX *ctx) {
135 if (ctx->error) {
136 // Once an operation has failed, |ctx->stack| no longer matches the number
137 // of |BN_CTX_end| calls to come. Do nothing.
138 return;
139 }
140
141 if (!BN_STACK_push(&ctx->stack, ctx->used)) {
142 ctx->error = 1;
143 // |BN_CTX_start| cannot fail, so defer the error to |BN_CTX_get|.
144 ctx->defer_error = 1;
145 }
146 }
147
BN_CTX_get(BN_CTX * ctx)148 BIGNUM *BN_CTX_get(BN_CTX *ctx) {
149 // Once any operation has failed, they all do.
150 if (ctx->error) {
151 if (ctx->defer_error) {
152 OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
153 ctx->defer_error = 0;
154 }
155 return NULL;
156 }
157
158 if (ctx->bignums == NULL) {
159 ctx->bignums = sk_BIGNUM_new_null();
160 if (ctx->bignums == NULL) {
161 OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
162 ctx->error = 1;
163 return NULL;
164 }
165 }
166
167 if (ctx->used == sk_BIGNUM_num(ctx->bignums)) {
168 BIGNUM *bn = BN_new();
169 if (bn == NULL || !sk_BIGNUM_push(ctx->bignums, bn)) {
170 OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
171 BN_free(bn);
172 ctx->error = 1;
173 return NULL;
174 }
175 }
176
177 BIGNUM *ret = sk_BIGNUM_value(ctx->bignums, ctx->used);
178 BN_zero(ret);
179 // This is bounded by |sk_BIGNUM_num|, so it cannot overflow.
180 ctx->used++;
181 return ret;
182 }
183
BN_CTX_end(BN_CTX * ctx)184 void BN_CTX_end(BN_CTX *ctx) {
185 if (ctx->error) {
186 // Once an operation has failed, |ctx->stack| no longer matches the number
187 // of |BN_CTX_end| calls to come. Do nothing.
188 return;
189 }
190
191 ctx->used = BN_STACK_pop(&ctx->stack);
192 }
193
194
195 // BN_STACK
196
BN_STACK_init(BN_STACK * st)197 static void BN_STACK_init(BN_STACK *st) {
198 st->indexes = NULL;
199 st->depth = st->size = 0;
200 }
201
BN_STACK_cleanup(BN_STACK * st)202 static void BN_STACK_cleanup(BN_STACK *st) {
203 OPENSSL_free(st->indexes);
204 }
205
BN_STACK_push(BN_STACK * st,size_t idx)206 static int BN_STACK_push(BN_STACK *st, size_t idx) {
207 if (st->depth == st->size) {
208 // This function intentionally does not push to the error queue on error.
209 // Error-reporting is deferred to |BN_CTX_get|.
210 size_t new_size = st->size != 0 ? st->size * 3 / 2 : BN_CTX_START_FRAMES;
211 if (new_size <= st->size || new_size > ((size_t)-1) / sizeof(size_t)) {
212 return 0;
213 }
214 size_t *new_indexes =
215 OPENSSL_realloc(st->indexes, new_size * sizeof(size_t));
216 if (new_indexes == NULL) {
217 return 0;
218 }
219 st->indexes = new_indexes;
220 st->size = new_size;
221 }
222
223 st->indexes[st->depth] = idx;
224 st->depth++;
225 return 1;
226 }
227
BN_STACK_pop(BN_STACK * st)228 static size_t BN_STACK_pop(BN_STACK *st) {
229 assert(st->depth > 0);
230 st->depth--;
231 return st->indexes[st->depth];
232 }
233