ref: 2bbc75bddc6f2a07056ff017108e35f14061041b
dir: /third_party/boringssl/src/crypto/fipsmodule/bn/ctx.c/
/* Written by Ulf Moeller for the OpenSSL project. */
/* ====================================================================
* Copyright (c) 1998-2004 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@openssl.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com). */
#include <openssl/bn.h>
#include <assert.h>
#include <string.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include "../../internal.h"
// The stack frame info is resizing, set a first-time expansion size;
#define BN_CTX_START_FRAMES 32
// BN_STACK
// A |BN_STACK| is a stack of |size_t| values.
typedef struct {
// Array of indexes into |ctx->bignums|.
size_t *indexes;
// Number of stack frames, and the size of the allocated array
size_t depth, size;
} BN_STACK;
static void BN_STACK_init(BN_STACK *);
static void BN_STACK_cleanup(BN_STACK *);
static int BN_STACK_push(BN_STACK *, size_t idx);
static size_t BN_STACK_pop(BN_STACK *);
// BN_CTX
DEFINE_STACK_OF(BIGNUM)
// The opaque BN_CTX type
struct bignum_ctx {
// bignums is the stack of |BIGNUM|s managed by this |BN_CTX|.
STACK_OF(BIGNUM) *bignums;
// stack is the stack of |BN_CTX_start| frames. It is the value of |used| at
// the time |BN_CTX_start| was called.
BN_STACK stack;
// used is the number of |BIGNUM|s from |bignums| that have been used.
size_t used;
// error is one if any operation on this |BN_CTX| failed. All subsequent
// operations will fail.
char error;
// defer_error is one if an operation on this |BN_CTX| has failed, but no
// error has been pushed to the queue yet. This is used to defer errors from
// |BN_CTX_start| to |BN_CTX_get|.
char defer_error;
};
BN_CTX *BN_CTX_new(void) {
BN_CTX *ret = OPENSSL_malloc(sizeof(BN_CTX));
if (!ret) {
OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
return NULL;
}
// Initialise the structure
ret->bignums = NULL;
BN_STACK_init(&ret->stack);
ret->used = 0;
ret->error = 0;
ret->defer_error = 0;
return ret;
}
void BN_CTX_free(BN_CTX *ctx) {
if (ctx == NULL) {
return;
}
// All |BN_CTX_start| calls must be matched with |BN_CTX_end|, otherwise the
// function may use more memory than expected, potentially without bound if
// done in a loop. Assert that all |BIGNUM|s have been released.
assert(ctx->used == 0 || ctx->error);
sk_BIGNUM_pop_free(ctx->bignums, BN_free);
BN_STACK_cleanup(&ctx->stack);
OPENSSL_free(ctx);
}
void BN_CTX_start(BN_CTX *ctx) {
if (ctx->error) {
// Once an operation has failed, |ctx->stack| no longer matches the number
// of |BN_CTX_end| calls to come. Do nothing.
return;
}
if (!BN_STACK_push(&ctx->stack, ctx->used)) {
ctx->error = 1;
// |BN_CTX_start| cannot fail, so defer the error to |BN_CTX_get|.
ctx->defer_error = 1;
}
}
BIGNUM *BN_CTX_get(BN_CTX *ctx) {
// Once any operation has failed, they all do.
if (ctx->error) {
if (ctx->defer_error) {
OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
ctx->defer_error = 0;
}
return NULL;
}
if (ctx->bignums == NULL) {
ctx->bignums = sk_BIGNUM_new_null();
if (ctx->bignums == NULL) {
OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
ctx->error = 1;
return NULL;
}
}
if (ctx->used == sk_BIGNUM_num(ctx->bignums)) {
BIGNUM *bn = BN_new();
if (bn == NULL || !sk_BIGNUM_push(ctx->bignums, bn)) {
OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_TEMPORARY_VARIABLES);
BN_free(bn);
ctx->error = 1;
return NULL;
}
}
BIGNUM *ret = sk_BIGNUM_value(ctx->bignums, ctx->used);
BN_zero(ret);
// This is bounded by |sk_BIGNUM_num|, so it cannot overflow.
ctx->used++;
return ret;
}
void BN_CTX_end(BN_CTX *ctx) {
if (ctx->error) {
// Once an operation has failed, |ctx->stack| no longer matches the number
// of |BN_CTX_end| calls to come. Do nothing.
return;
}
ctx->used = BN_STACK_pop(&ctx->stack);
}
// BN_STACK
static void BN_STACK_init(BN_STACK *st) {
st->indexes = NULL;
st->depth = st->size = 0;
}
static void BN_STACK_cleanup(BN_STACK *st) {
OPENSSL_free(st->indexes);
}
static int BN_STACK_push(BN_STACK *st, size_t idx) {
if (st->depth == st->size) {
// This function intentionally does not push to the error queue on error.
// Error-reporting is deferred to |BN_CTX_get|.
size_t new_size = st->size != 0 ? st->size * 3 / 2 : BN_CTX_START_FRAMES;
if (new_size <= st->size || new_size > ((size_t)-1) / sizeof(size_t)) {
return 0;
}
size_t *new_indexes =
OPENSSL_realloc(st->indexes, new_size * sizeof(size_t));
if (new_indexes == NULL) {
return 0;
}
st->indexes = new_indexes;
st->size = new_size;
}
st->indexes[st->depth] = idx;
st->depth++;
return 1;
}
static size_t BN_STACK_pop(BN_STACK *st) {
assert(st->depth > 0);
st->depth--;
return st->indexes[st->depth];
}