-/* $OpenBSD: bn_ctx.c,v 1.19 2022/11/30 01:47:19 jsing Exp $ */
-/* Written by Ulf Moeller for the OpenSSL project. */
-/* ====================================================================
- * Copyright (c) 1998-2004 The OpenSSL Project. All rights reserved.
+/* $OpenBSD: bn_ctx.c,v 1.20 2023/01/14 15:23:27 jsing Exp $ */
+/*
+ * Copyright (c) 2023 Joel Sing <jsing@openbsd.org>
*
- * 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).
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
*
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
-#include <stdio.h>
+#include <stddef.h>
#include <string.h>
#include <openssl/opensslconf.h>
-
#include <openssl/err.h>
#include "bn_local.h"
-/* TODO list
- *
- * 1. Check a bunch of "(words+1)" type hacks in various bignum functions and
- * check they can be safely removed.
- * - Check +1 and other ugliness in BN_from_montgomery()
- *
- * 2. Consider allowing a BN_new_ex() that, at least, lets you specify an
- * appropriate 'block' size that will be honoured by bn_expand_internal() to
- * prevent piddly little reallocations. OTOH, profiling bignum expansions in
- * BN_CTX doesn't show this to be a big issue.
- */
-
-/* How many bignums are in each "pool item"; */
-#define BN_CTX_POOL_SIZE 16
-/* The stack frame info is resizing, set a first-time expansion size; */
-#define BN_CTX_START_FRAMES 32
-
-/***********/
-/* BN_POOL */
-/***********/
-
-/* A bundle of bignums that can be linked with other bundles */
-typedef struct bignum_pool_item {
- /* The bignum values */
- BIGNUM vals[BN_CTX_POOL_SIZE];
- /* Linked-list admin */
- struct bignum_pool_item *prev, *next;
-} BN_POOL_ITEM;
-
-/* A linked-list of bignums grouped in bundles */
-typedef struct bignum_pool {
- /* Linked-list admin */
- BN_POOL_ITEM *head, *current, *tail;
- /* Stack depth and allocation size */
- unsigned used, size;
-} BN_POOL;
-
-static void BN_POOL_init(BN_POOL *);
-static void BN_POOL_finish(BN_POOL *);
-#ifndef OPENSSL_NO_DEPRECATED
-static void BN_POOL_reset(BN_POOL *);
-#endif
-static BIGNUM * BN_POOL_get(BN_POOL *);
-static void BN_POOL_release(BN_POOL *, unsigned int);
+#define BN_CTX_INITIAL_LEN 8
-/************/
-/* BN_STACK */
-/************/
-
-/* A wrapper to manage the "stack frames" */
-typedef struct bignum_ctx_stack {
- /* Array of indexes into the bignum stack */
- unsigned int *indexes;
- /* Number of stack frames, and the size of the allocated array */
- unsigned int depth, size;
-} BN_STACK;
-
-static void BN_STACK_init(BN_STACK *);
-static void BN_STACK_finish(BN_STACK *);
-#ifndef OPENSSL_NO_DEPRECATED
-static void BN_STACK_reset(BN_STACK *);
-#endif
-static int BN_STACK_push(BN_STACK *, unsigned int);
-static unsigned int BN_STACK_pop(BN_STACK *);
-
-/**********/
-/* BN_CTX */
-/**********/
-
-/* The opaque BN_CTX type */
struct bignum_ctx {
- /* The bignum bundles */
- BN_POOL pool;
- /* The "stack frames", if you will */
- BN_STACK stack;
- /* The number of bignums currently assigned */
- unsigned int used;
- /* Depth of stack overflow */
- int err_stack;
- /* Block "gets" until an "end" (compatibility behaviour) */
- int too_many;
-};
+ BIGNUM **bignums;
+ uint8_t *groups;
+ uint8_t group;
+ size_t index;
+ size_t len;
-/* Enable this to find BN_CTX bugs */
-#ifdef BN_CTX_DEBUG
-static const char *ctxdbg_cur = NULL;
+ int error;
+};
-static void
-ctxdbg(BN_CTX *ctx)
+static int
+bn_ctx_grow(BN_CTX *bctx)
{
- unsigned int bnidx = 0, fpidx = 0;
- BN_POOL_ITEM *item = ctx->pool.head;
- BN_STACK *stack = &ctx->stack;
+ BIGNUM **bignums = NULL;
+ uint8_t *groups = NULL;
+ size_t len;
- fprintf(stderr, "(%08x): ", (unsigned int)ctx);
- while (bnidx < ctx->used) {
- fprintf(stderr, "%03x ",
- item->vals[bnidx++ % BN_CTX_POOL_SIZE].dmax);
- if (!(bnidx % BN_CTX_POOL_SIZE))
- item = item->next;
- }
- fprintf(stderr, "\n");
- bnidx = 0;
- fprintf(stderr, " : ");
- while (fpidx < stack->depth) {
- while (bnidx++ < stack->indexes[fpidx])
- fprintf(stderr, " ");
- fprintf(stderr, "^^^ ");
- bnidx++;
- fpidx++;
+ if ((len = bctx->len) == 0) {
+ len = BN_CTX_INITIAL_LEN;
+ } else {
+ if (SIZE_MAX - len < len)
+ return 0;
+ len *= 2;
}
- fprintf(stderr, "\n");
-}
-#define CTXDBG_ENTRY(str, ctx) \
- do { \
- ctxdbg_cur = (str); \
- fprintf(stderr, "Starting %s\n", ctxdbg_cur); \
- ctxdbg(ctx); \
- } while(0)
-#define CTXDBG_EXIT(ctx) \
- do { \
- fprintf(stderr, "Ending %s\n", ctxdbg_cur); \
- ctxdbg(ctx); \
- } while(0)
+ if ((bignums = recallocarray(bctx->bignums, bctx->len, len,
+ sizeof(bctx->bignums[0]))) == NULL)
+ return 0;
+ bctx->bignums = bignums;
-#define CTXDBG_RET(ctx,ret)
-#else
-#define CTXDBG_ENTRY(str, ctx)
-#define CTXDBG_EXIT(ctx)
-#define CTXDBG_RET(ctx,ret)
-#endif
+ if ((groups = reallocarray(bctx->groups, len,
+ sizeof(bctx->groups[0]))) == NULL)
+ return 0;
+ bctx->groups = groups;
-/* This function is an evil legacy and should not be used. This implementation
- * is WYSIWYG, though I've done my best. */
-#ifndef OPENSSL_NO_DEPRECATED
-void
-BN_CTX_init(BN_CTX *ctx)
-{
- /* Assume the caller obtained the context via BN_CTX_new() and so is
- * trying to reset it for use. Nothing else makes sense, least of all
- * binary compatibility from a time when they could declare a static
- * variable. */
- BN_POOL_reset(&ctx->pool);
- BN_STACK_reset(&ctx->stack);
- ctx->used = 0;
- ctx->err_stack = 0;
- ctx->too_many = 0;
+ bctx->len = len;
+
+ return 1;
}
-#endif
BN_CTX *
BN_CTX_new(void)
{
- BN_CTX *ret = malloc(sizeof(BN_CTX));
- if (!ret) {
- BNerror(ERR_R_MALLOC_FAILURE);
- return NULL;
- }
-
- /* Initialise the structure */
- BN_POOL_init(&ret->pool);
- BN_STACK_init(&ret->stack);
- ret->used = 0;
- ret->err_stack = 0;
- ret->too_many = 0;
- return ret;
+ return calloc(1, sizeof(struct bignum_ctx));
}
void
-BN_CTX_free(BN_CTX *ctx)
+BN_CTX_init(BN_CTX *bctx)
{
- if (ctx == NULL)
- return;
-#ifdef BN_CTX_DEBUG
- {
- BN_POOL_ITEM *pool = ctx->pool.head;
- fprintf(stderr, "BN_CTX_free, stack-size=%d, pool-bignums=%d\n",
- ctx->stack.size, ctx->pool.size);
- fprintf(stderr, "dmaxs: ");
- while (pool) {
- unsigned loop = 0;
- while (loop < BN_CTX_POOL_SIZE)
- fprintf(stderr, "%02x ",
- pool->vals[loop++].dmax);
- pool = pool->next;
- }
- fprintf(stderr, "\n");
- }
-#endif
- BN_STACK_finish(&ctx->stack);
- BN_POOL_finish(&ctx->pool);
- free(ctx);
+ memset(bctx, 0, sizeof(*bctx));
}
void
-BN_CTX_start(BN_CTX *ctx)
+BN_CTX_free(BN_CTX *bctx)
{
- CTXDBG_ENTRY("BN_CTX_start", ctx);
-
- /* If we're already overflowing ... */
- if (ctx->err_stack || ctx->too_many)
- ctx->err_stack++;
- /* (Try to) get a new frame pointer */
- else if (!BN_STACK_push(&ctx->stack, ctx->used)) {
- BNerror(BN_R_TOO_MANY_TEMPORARY_VARIABLES);
- ctx->err_stack++;
- }
- CTXDBG_EXIT(ctx);
-}
+ size_t i;
-void
-BN_CTX_end(BN_CTX *ctx)
-{
- if (ctx == NULL)
+ if (bctx == NULL)
return;
- CTXDBG_ENTRY("BN_CTX_end", ctx);
-
- if (ctx->err_stack)
- ctx->err_stack--;
- else {
- unsigned int fp = BN_STACK_pop(&ctx->stack);
- /* Does this stack frame have anything to release? */
- if (fp < ctx->used)
- BN_POOL_release(&ctx->pool, ctx->used - fp);
- ctx->used = fp;
- /* Unjam "too_many" in case "get" had failed */
- ctx->too_many = 0;
- }
- CTXDBG_EXIT(ctx);
-}
-
-BIGNUM *
-BN_CTX_get(BN_CTX *ctx)
-{
- BIGNUM *ret;
-
- CTXDBG_ENTRY("BN_CTX_get", ctx);
-
- if (ctx->err_stack || ctx->too_many)
- return NULL;
- if ((ret = BN_POOL_get(&ctx->pool)) == NULL) {
- /* Setting too_many prevents repeated "get" attempts from
- * cluttering the error stack. */
- ctx->too_many = 1;
- BNerror(BN_R_TOO_MANY_TEMPORARY_VARIABLES);
- return NULL;
+ for (i = 0; i < bctx->len; i++) {
+ BN_free(bctx->bignums[i]);
+ bctx->bignums[i] = NULL;
}
- /* OK, make sure the returned bignum is "zero" */
- BN_zero(ret);
- ctx->used++;
- CTXDBG_RET(ctx, ret);
- return ret;
-}
-/************/
-/* BN_STACK */
-/************/
+ free(bctx->bignums);
+ free(bctx->groups);
-static void
-BN_STACK_init(BN_STACK *st)
-{
- st->indexes = NULL;
- st->depth = st->size = 0;
+ freezero(bctx, sizeof(*bctx));
}
-static void
-BN_STACK_finish(BN_STACK *st)
+void
+BN_CTX_start(BN_CTX *bctx)
{
- if (st->size)
- free(st->indexes);
-}
+ bctx->group++;
-#ifndef OPENSSL_NO_DEPRECATED
-static void
-BN_STACK_reset(BN_STACK *st)
-{
- st->depth = 0;
-}
-#endif
-
-static int
-BN_STACK_push(BN_STACK *st, unsigned int idx)
-{
- if (st->depth == st->size)
- /* Need to expand */
- {
- unsigned int newsize = (st->size ?
- (st->size * 3 / 2) : BN_CTX_START_FRAMES);
- unsigned int *newitems = reallocarray(NULL,
- newsize, sizeof(unsigned int));
- if (!newitems)
- return 0;
- if (st->depth)
- memcpy(newitems, st->indexes, st->depth *
- sizeof(unsigned int));
- if (st->size)
- free(st->indexes);
- st->indexes = newitems;
- st->size = newsize;
+ if (bctx->group == 0) {
+ BNerror(BN_R_TOO_MANY_TEMPORARY_VARIABLES);
+ bctx->error = 1;
+ return;
}
- st->indexes[(st->depth)++] = idx;
- return 1;
}
-static unsigned int
-BN_STACK_pop(BN_STACK *st)
+BIGNUM *
+BN_CTX_get(BN_CTX *bctx)
{
- return st->indexes[--(st->depth)];
-}
-
-/***********/
-/* BN_POOL */
-/***********/
+ BIGNUM *bn = NULL;
-static void
-BN_POOL_init(BN_POOL *p)
-{
- p->head = p->current = p->tail = NULL;
- p->used = p->size = 0;
-}
+ if (bctx->error)
+ return NULL;
-static void
-BN_POOL_finish(BN_POOL *p)
-{
- while (p->head) {
- unsigned int loop = 0;
- BIGNUM *bn = p->head->vals;
- while (loop++ < BN_CTX_POOL_SIZE) {
- if (bn->d)
- BN_clear_free(bn);
- bn++;
- }
- p->current = p->head->next;
- free(p->head);
- p->head = p->current;
+ if (bctx->group == 0) {
+ BNerror(ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
+ bctx->error = 1;
+ return NULL;
}
-}
-#ifndef OPENSSL_NO_DEPRECATED
-static void
-BN_POOL_reset(BN_POOL *p)
-{
- BN_POOL_ITEM *item = p->head;
- while (item) {
- unsigned int loop = 0;
- BIGNUM *bn = item->vals;
- while (loop++ < BN_CTX_POOL_SIZE) {
- if (bn->d)
- BN_clear(bn);
- bn++;
+ if (bctx->index == bctx->len) {
+ if (!bn_ctx_grow(bctx)) {
+ BNerror(BN_R_TOO_MANY_TEMPORARY_VARIABLES);
+ bctx->error = 1;
+ return NULL;
}
- item = item->next;
}
- p->current = p->head;
- p->used = 0;
-}
-#endif
-static BIGNUM *
-BN_POOL_get(BN_POOL *p)
-{
- if (p->used == p->size) {
- BIGNUM *bn;
- unsigned int loop = 0;
- BN_POOL_ITEM *item = malloc(sizeof(BN_POOL_ITEM));
- if (!item)
+ if ((bn = bctx->bignums[bctx->index]) == NULL) {
+ if ((bn = BN_new()) == NULL) {
+ BNerror(BN_R_TOO_MANY_TEMPORARY_VARIABLES);
+ bctx->error = 1;
return NULL;
- /* Initialise the structure */
- bn = item->vals;
- while (loop++ < BN_CTX_POOL_SIZE)
- BN_init(bn++);
- item->prev = p->tail;
- item->next = NULL;
- /* Link it in */
- if (!p->head)
- p->head = p->current = p->tail = item;
- else {
- p->tail->next = item;
- p->tail = item;
- p->current = item;
}
- p->size += BN_CTX_POOL_SIZE;
- p->used++;
- /* Return the first bignum from the new pool */
- return item->vals;
+ bctx->bignums[bctx->index] = bn;
}
- if (!p->used)
- p->current = p->head;
- else if ((p->used % BN_CTX_POOL_SIZE) == 0)
- p->current = p->current->next;
- return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE);
+ bctx->groups[bctx->index] = bctx->group;
+ bctx->index++;
+
+ BN_zero(bn);
+
+ return bn;
}
-static void
-BN_POOL_release(BN_POOL *p, unsigned int num)
+void
+BN_CTX_end(BN_CTX *bctx)
{
- unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE;
+ if (bctx == NULL || bctx->error || bctx->group == 0)
+ return;
- p->used -= num;
- while (num--) {
- if (!offset) {
- offset = BN_CTX_POOL_SIZE - 1;
- p->current = p->current->prev;
- } else
- offset--;
+ while (bctx->index > 0 && bctx->groups[bctx->index - 1] == bctx->group) {
+ BN_zero(bctx->bignums[bctx->index - 1]);
+ bctx->groups[bctx->index - 1] = 0;
+ bctx->index--;
}
+
+ bctx->group--;
}
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