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bcec03c33c
Fixes CVE-2023-0217 When attempting to do a BN_Copy of params->p there was no NULL check. Since BN_copy does not check for NULL this is a NULL reference. As an aside BN_cmp() does do a NULL check, so there are other checks that fail because a NULL is passed. A more general check for NULL params has been added for both FFC public and private key validation instead. Reviewed-by: Paul Dale <pauli@openssl.org> Reviewed-by: Matt Caswell <matt@openssl.org> Reviewed-by: Tomas Mraz <tomas@openssl.org>
131 lines
3.4 KiB
C
131 lines
3.4 KiB
C
/*
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* Copyright 2019-2020 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License 2.0 (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include "internal/ffc.h"
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/*
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* See SP800-56Ar3 Section 5.6.2.3.1 : FFC Partial public key validation.
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* To only be used with ephemeral FFC public keys generated using the approved
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* safe-prime groups. (Checks that the public key is in the range [2, p - 1]
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*
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* ret contains 0 on success, or error flags (see FFC_ERROR_PUBKEY_TOO_SMALL)
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*/
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int ossl_ffc_validate_public_key_partial(const FFC_PARAMS *params,
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const BIGNUM *pub_key, int *ret)
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{
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int ok = 0;
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BIGNUM *tmp = NULL;
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BN_CTX *ctx = NULL;
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*ret = 0;
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if (params == NULL || pub_key == NULL || params->p == NULL) {
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*ret = FFC_ERROR_PASSED_NULL_PARAM;
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return 0;
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}
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ctx = BN_CTX_new_ex(NULL);
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if (ctx == NULL)
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goto err;
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BN_CTX_start(ctx);
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tmp = BN_CTX_get(ctx);
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/* Step(1): Verify pub_key >= 2 */
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if (tmp == NULL
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|| !BN_set_word(tmp, 1))
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goto err;
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if (BN_cmp(pub_key, tmp) <= 0) {
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*ret |= FFC_ERROR_PUBKEY_TOO_SMALL;
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goto err;
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}
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/* Step(1): Verify pub_key <= p-2 */
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if (BN_copy(tmp, params->p) == NULL
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|| !BN_sub_word(tmp, 1))
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goto err;
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if (BN_cmp(pub_key, tmp) >= 0) {
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*ret |= FFC_ERROR_PUBKEY_TOO_LARGE;
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goto err;
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}
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ok = 1;
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err:
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if (ctx != NULL) {
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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}
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return ok;
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}
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/*
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* See SP800-56Ar3 Section 5.6.2.3.1 : FFC Full public key validation.
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*/
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int ossl_ffc_validate_public_key(const FFC_PARAMS *params,
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const BIGNUM *pub_key, int *ret)
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{
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int ok = 0;
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BIGNUM *tmp = NULL;
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BN_CTX *ctx = NULL;
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if (!ossl_ffc_validate_public_key_partial(params, pub_key, ret))
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return 0;
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if (params->q != NULL) {
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ctx = BN_CTX_new_ex(NULL);
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if (ctx == NULL)
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goto err;
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BN_CTX_start(ctx);
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tmp = BN_CTX_get(ctx);
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/* Check pub_key^q == 1 mod p */
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if (tmp == NULL
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|| !BN_mod_exp(tmp, pub_key, params->q, params->p, ctx))
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goto err;
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if (!BN_is_one(tmp)) {
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*ret |= FFC_ERROR_PUBKEY_INVALID;
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goto err;
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}
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}
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ok = 1;
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err:
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if (ctx != NULL) {
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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}
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return ok;
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}
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/*
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* See SP800-56Ar3 Section 5.6.2.1.2: Owner assurance of Private key validity.
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* Verifies priv_key is in the range [1..upper-1]. The passed in value of upper
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* is normally params->q but can be 2^N for approved safe prime groups.
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* Note: This assumes that the domain parameters are valid.
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*/
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int ossl_ffc_validate_private_key(const BIGNUM *upper, const BIGNUM *priv,
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int *ret)
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{
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int ok = 0;
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*ret = 0;
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if (priv == NULL || upper == NULL) {
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*ret = FFC_ERROR_PASSED_NULL_PARAM;
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goto err;
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}
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if (BN_cmp(priv, BN_value_one()) < 0) {
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*ret |= FFC_ERROR_PRIVKEY_TOO_SMALL;
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goto err;
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}
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if (BN_cmp(priv, upper) >= 0) {
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*ret |= FFC_ERROR_PRIVKEY_TOO_LARGE;
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goto err;
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}
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ok = 1;
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err:
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return ok;
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}
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