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 // All |BN_CTX_start| calls must be matched with |BN_CTX_end|, otherwise the
130 // function may use more memory than expected, potentially without bound if
131 // done in a loop. Assert that all |BIGNUM|s have been released.
132 assert(ctx->used == 0 || ctx->error);
133 sk_BIGNUM_pop_free(ctx->bignums, BN_free);
134 BN_STACK_cleanup(&ctx->stack);
135 OPENSSL_free(ctx);
136 }
137
BN_CTX_start(BN_CTX * ctx)138 void BN_CTX_start(BN_CTX *ctx) {
139 if (ctx->error) {
140 // Once an operation has failed, |ctx->stack| no longer matches the number
141 // of |BN_CTX_end| calls to come. Do nothing.
142 return;
143 }
144
145 if (!BN_STACK_push(&ctx->stack, ctx->used)) {
146 ctx->error = 1;
147 // |BN_CTX_start| cannot fail, so defer the error to |BN_CTX_get|.
148 ctx->defer_error = 1;
149 }
150 }
151
BN_CTX_get(BN_CTX * ctx)152 BIGNUM *BN_CTX_get(BN_CTX *ctx) {
153 // Once any operation has failed, they all do.
154 if (ctx->error) {
155 if (ctx->defer_error) {
156 OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
157 ctx->defer_error = 0;
158 }
159 return NULL;
160 }
161
162 if (ctx->bignums == NULL) {
163 ctx->bignums = sk_BIGNUM_new_null();
164 if (ctx->bignums == NULL) {
165 OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
166 ctx->error = 1;
167 return NULL;
168 }
169 }
170
171 if (ctx->used == sk_BIGNUM_num(ctx->bignums)) {
172 BIGNUM *bn = BN_new();
173 if (bn == NULL || !sk_BIGNUM_push(ctx->bignums, bn)) {
174 OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
175 BN_free(bn);
176 ctx->error = 1;
177 return NULL;
178 }
179 }
180
181 BIGNUM *ret = sk_BIGNUM_value(ctx->bignums, ctx->used);
182 BN_zero(ret);
183 // This is bounded by |sk_BIGNUM_num|, so it cannot overflow.
184 ctx->used++;
185 return ret;
186 }
187
BN_CTX_end(BN_CTX * ctx)188 void BN_CTX_end(BN_CTX *ctx) {
189 if (ctx->error) {
190 // Once an operation has failed, |ctx->stack| no longer matches the number
191 // of |BN_CTX_end| calls to come. Do nothing.
192 return;
193 }
194
195 ctx->used = BN_STACK_pop(&ctx->stack);
196 }
197
198
199 // BN_STACK
200
BN_STACK_init(BN_STACK * st)201 static void BN_STACK_init(BN_STACK *st) {
202 st->indexes = NULL;
203 st->depth = st->size = 0;
204 }
205
BN_STACK_cleanup(BN_STACK * st)206 static void BN_STACK_cleanup(BN_STACK *st) {
207 OPENSSL_free(st->indexes);
208 }
209
BN_STACK_push(BN_STACK * st,size_t idx)210 static int BN_STACK_push(BN_STACK *st, size_t idx) {
211 if (st->depth == st->size) {
212 // This function intentionally does not push to the error queue on error.
213 // Error-reporting is deferred to |BN_CTX_get|.
214 size_t new_size = st->size != 0 ? st->size * 3 / 2 : BN_CTX_START_FRAMES;
215 if (new_size <= st->size || new_size > ((size_t)-1) / sizeof(size_t)) {
216 return 0;
217 }
218 size_t *new_indexes =
219 OPENSSL_realloc(st->indexes, new_size * sizeof(size_t));
220 if (new_indexes == NULL) {
221 return 0;
222 }
223 st->indexes = new_indexes;
224 st->size = new_size;
225 }
226
227 st->indexes[st->depth] = idx;
228 st->depth++;
229 return 1;
230 }
231
BN_STACK_pop(BN_STACK * st)232 static size_t BN_STACK_pop(BN_STACK *st) {
233 assert(st->depth > 0);
234 st->depth--;
235 return st->indexes[st->depth];
236 }
237