First Commit

externals/libressl/crypto/bn/bn_ctx.c

@@ -0,0 +1,156 @@
+/*	$OpenBSD: bn_ctx.c,v 1.21 2023/04/25 16:41:29 tb Exp $ */
+/*
+ * Copyright (c) 2023 Joel Sing <jsing@openbsd.org>
+ *
+ * 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 <stddef.h>
+#include <string.h>
+
+#include <openssl/opensslconf.h>
+#include <openssl/err.h>
+
+#include "bn_local.h"
+
+#define BN_CTX_INITIAL_LEN	8
+
+struct bignum_ctx {
+	BIGNUM **bignums;
+	uint8_t *groups;
+	uint8_t group;
+	size_t index;
+	size_t len;
+
+	int error;
+};
+
+static int
+bn_ctx_grow(BN_CTX *bctx)
+{
+	BIGNUM **bignums = NULL;
+	uint8_t *groups = NULL;
+	size_t len;
+
+	if ((len = bctx->len) == 0) {
+		len = BN_CTX_INITIAL_LEN;
+	} else {
+		if (SIZE_MAX - len < len)
+			return 0;
+		len *= 2;
+	}
+
+	if ((bignums = recallocarray(bctx->bignums, bctx->len, len,
+	    sizeof(bctx->bignums[0]))) == NULL)
+		return 0;
+	bctx->bignums = bignums;
+
+	if ((groups = reallocarray(bctx->groups, len,
+	    sizeof(bctx->groups[0]))) == NULL)
+		return 0;
+	bctx->groups = groups;
+
+	bctx->len = len;
+
+	return 1;
+}
+
+BN_CTX *
+BN_CTX_new(void)
+{
+	return calloc(1, sizeof(struct bignum_ctx));
+}
+
+void
+BN_CTX_free(BN_CTX *bctx)
+{
+	size_t i;
+
+	if (bctx == NULL)
+		return;
+
+	for (i = 0; i < bctx->len; i++) {
+		BN_free(bctx->bignums[i]);
+		bctx->bignums[i] = NULL;
+	}
+
+	free(bctx->bignums);
+	free(bctx->groups);
+
+	freezero(bctx, sizeof(*bctx));
+}
+
+void
+BN_CTX_start(BN_CTX *bctx)
+{
+	bctx->group++;
+
+	if (bctx->group == 0) {
+		BNerror(BN_R_TOO_MANY_TEMPORARY_VARIABLES);
+		bctx->error = 1;
+		return;
+	}
+}
+
+BIGNUM *
+BN_CTX_get(BN_CTX *bctx)
+{
+	BIGNUM *bn = NULL;
+
+	if (bctx->error)
+		return NULL;
+
+	if (bctx->group == 0) {
+		BNerror(ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
+		bctx->error = 1;
+		return NULL;
+	}
+
+	if (bctx->index == bctx->len) {
+		if (!bn_ctx_grow(bctx)) {
+			BNerror(BN_R_TOO_MANY_TEMPORARY_VARIABLES);
+			bctx->error = 1;
+			return NULL;
+		}
+	}
+
+	if ((bn = bctx->bignums[bctx->index]) == NULL) {
+		if ((bn = BN_new()) == NULL) {
+			BNerror(BN_R_TOO_MANY_TEMPORARY_VARIABLES);
+			bctx->error = 1;
+			return NULL;
+		}
+		bctx->bignums[bctx->index] = bn;
+	}
+	bctx->groups[bctx->index] = bctx->group;
+	bctx->index++;
+
+	BN_zero(bn);
+
+	return bn;
+}
+
+void
+BN_CTX_end(BN_CTX *bctx)
+{
+	if (bctx == NULL || bctx->error || bctx->group == 0)
+		return;
+
+	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--;
+}