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/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
#include "crypto/s2n_pkey.h"
#include <openssl/evp.h>
#include "crypto/s2n_openssl_evp.h"
#include "crypto/s2n_openssl_x509.h"
#include "crypto/s2n_rsa_pss.h"
#include "error/s2n_errno.h"
#include "utils/s2n_result.h"
#include "utils/s2n_safety.h"
#define S2N_MAX_ALLOWED_CERT_TRAILING_BYTES 3
int s2n_pkey_zero_init(struct s2n_pkey *pkey)
{
pkey->pkey = NULL;
pkey->size = NULL;
pkey->sign = NULL;
pkey->verify = NULL;
pkey->encrypt = NULL;
pkey->decrypt = NULL;
pkey->match = NULL;
pkey->free = NULL;
pkey->check_key = NULL;
return 0;
}
int s2n_pkey_setup_for_type(struct s2n_pkey *pkey, s2n_pkey_type pkey_type)
{
switch (pkey_type) {
case S2N_PKEY_TYPE_RSA:
return s2n_rsa_pkey_init(pkey);
case S2N_PKEY_TYPE_ECDSA:
return s2n_ecdsa_pkey_init(pkey);
case S2N_PKEY_TYPE_RSA_PSS:
return s2n_rsa_pss_pkey_init(pkey);
case S2N_PKEY_TYPE_SENTINEL:
case S2N_PKEY_TYPE_UNKNOWN:
POSIX_BAIL(S2N_ERR_CERT_TYPE_UNSUPPORTED);
}
POSIX_BAIL(S2N_ERR_CERT_TYPE_UNSUPPORTED);
}
int s2n_pkey_check_key_exists(const struct s2n_pkey *pkey)
{
POSIX_ENSURE_REF(pkey->pkey);
POSIX_ENSURE_REF(pkey->check_key);
return pkey->check_key(pkey);
}
S2N_RESULT s2n_pkey_size(const struct s2n_pkey *pkey, uint32_t *size_out)
{
RESULT_ENSURE_REF(pkey);
RESULT_ENSURE_REF(pkey->size);
RESULT_ENSURE_REF(size_out);
RESULT_GUARD(pkey->size(pkey, size_out));
return S2N_RESULT_OK;
}
int s2n_pkey_sign(const struct s2n_pkey *pkey, s2n_signature_algorithm sig_alg,
struct s2n_hash_state *digest, struct s2n_blob *signature)
{
POSIX_ENSURE_REF(pkey->sign);
return pkey->sign(pkey, sig_alg, digest, signature);
}
int s2n_pkey_verify(const struct s2n_pkey *pkey, s2n_signature_algorithm sig_alg,
struct s2n_hash_state *digest, struct s2n_blob *signature)
{
POSIX_ENSURE_REF(pkey);
POSIX_ENSURE_REF(pkey->verify);
return pkey->verify(pkey, sig_alg, digest, signature);
}
int s2n_pkey_encrypt(const struct s2n_pkey *pkey, struct s2n_blob *in, struct s2n_blob *out)
{
POSIX_ENSURE_REF(pkey->encrypt);
return pkey->encrypt(pkey, in, out);
}
int s2n_pkey_decrypt(const struct s2n_pkey *pkey, struct s2n_blob *in, struct s2n_blob *out)
{
POSIX_ENSURE_REF(pkey->decrypt);
return pkey->decrypt(pkey, in, out);
}
int s2n_pkey_match(const struct s2n_pkey *pub_key, const struct s2n_pkey *priv_key)
{
POSIX_ENSURE_REF(pub_key->match);
S2N_ERROR_IF(pub_key->match != priv_key->match, S2N_ERR_KEY_MISMATCH);
return pub_key->match(pub_key, priv_key);
}
int s2n_pkey_free(struct s2n_pkey *key)
{
if (key != NULL && key->free != NULL) {
POSIX_GUARD(key->free(key));
}
if (key->pkey != NULL) {
EVP_PKEY_free(key->pkey);
key->pkey = NULL;
}
return S2N_SUCCESS;
}
int s2n_asn1der_to_private_key(struct s2n_pkey *priv_key, struct s2n_blob *asn1der, int type_hint)
{
const unsigned char *key_to_parse = asn1der->data;
/* We use "d2i_AutoPrivateKey" instead of "PEM_read_bio_PrivateKey" because
* s2n-tls prefers to perform its own custom PEM parsing. Historically,
* openssl's PEM parsing tended to ignore invalid certificates rather than
* error on them. We prefer to fail early rather than continue without
* the full and correct chain intended by the application.
*/
DEFER_CLEANUP(EVP_PKEY *evp_private_key = d2i_AutoPrivateKey(NULL, &key_to_parse, asn1der->size),
EVP_PKEY_free_pointer);
/* We have found cases where d2i_AutoPrivateKey fails to detect the type of
* the key. For example, openssl fails to identify an EC key without the
* optional publicKey field.
*
* If d2i_AutoPrivateKey fails, try once more with the type we parsed from the PEM.
*/
if (evp_private_key == NULL) {
evp_private_key = d2i_PrivateKey(type_hint, NULL, &key_to_parse, asn1der->size);
}
POSIX_ENSURE(evp_private_key, S2N_ERR_DECODE_PRIVATE_KEY);
/* If key parsing is successful, d2i_AutoPrivateKey increments *key_to_parse to the byte following the parsed data */
uint32_t parsed_len = key_to_parse - asn1der->data;
if (parsed_len != asn1der->size) {
POSIX_BAIL(S2N_ERR_DECODE_PRIVATE_KEY);
}
/* Initialize s2n_pkey according to key type */
int type = EVP_PKEY_base_id(evp_private_key);
int ret;
switch (type) {
case EVP_PKEY_RSA:
ret = s2n_rsa_pkey_init(priv_key);
if (ret != 0) {
break;
}
ret = s2n_evp_pkey_to_rsa_private_key(&priv_key->key.rsa_key, evp_private_key);
break;
case EVP_PKEY_RSA_PSS:
ret = s2n_rsa_pss_pkey_init(priv_key);
if (ret != 0) {
break;
}
ret = s2n_evp_pkey_to_rsa_pss_private_key(&priv_key->key.rsa_key, evp_private_key);
break;
case EVP_PKEY_EC:
ret = s2n_ecdsa_pkey_init(priv_key);
if (ret != 0) {
break;
}
ret = s2n_evp_pkey_to_ecdsa_private_key(&priv_key->key.ecdsa_key, evp_private_key);
break;
default:
POSIX_BAIL(S2N_ERR_DECODE_PRIVATE_KEY);
}
priv_key->pkey = evp_private_key;
/* Reset to avoid DEFER_CLEANUP freeing our key */
evp_private_key = NULL;
return ret;
}
int s2n_asn1der_to_public_key_and_type(struct s2n_pkey *pub_key, s2n_pkey_type *pkey_type_out, struct s2n_blob *asn1der)
{
uint8_t *cert_to_parse = asn1der->data;
DEFER_CLEANUP(X509 *cert = NULL, X509_free_pointer);
cert = d2i_X509(NULL, (const unsigned char **) (void *) &cert_to_parse, asn1der->size);
S2N_ERROR_IF(cert == NULL, S2N_ERR_DECODE_CERTIFICATE);
/* If cert parsing is successful, d2i_X509 increments *cert_to_parse to the byte following the parsed data */
uint32_t parsed_len = cert_to_parse - asn1der->data;
/* Some TLS clients in the wild send extra trailing bytes after the Certificate.
* Allow this in s2n for backwards compatibility with existing clients. */
uint32_t trailing_bytes = asn1der->size - parsed_len;
POSIX_ENSURE(trailing_bytes <= S2N_MAX_ALLOWED_CERT_TRAILING_BYTES, S2N_ERR_DECODE_CERTIFICATE);
DEFER_CLEANUP(EVP_PKEY *evp_public_key = X509_get_pubkey(cert), EVP_PKEY_free_pointer);
S2N_ERROR_IF(evp_public_key == NULL, S2N_ERR_DECODE_CERTIFICATE);
/* Check for success in decoding certificate according to type */
int type = EVP_PKEY_base_id(evp_public_key);
int ret;
switch (type) {
case EVP_PKEY_RSA:
ret = s2n_rsa_pkey_init(pub_key);
if (ret != 0) {
break;
}
ret = s2n_evp_pkey_to_rsa_public_key(&pub_key->key.rsa_key, evp_public_key);
*pkey_type_out = S2N_PKEY_TYPE_RSA;
break;
case EVP_PKEY_RSA_PSS:
ret = s2n_rsa_pss_pkey_init(pub_key);
if (ret != 0) {
break;
}
ret = s2n_evp_pkey_to_rsa_pss_public_key(&pub_key->key.rsa_key, evp_public_key);
*pkey_type_out = S2N_PKEY_TYPE_RSA_PSS;
break;
case EVP_PKEY_EC:
ret = s2n_ecdsa_pkey_init(pub_key);
if (ret != 0) {
break;
}
ret = s2n_evp_pkey_to_ecdsa_public_key(&pub_key->key.ecdsa_key, evp_public_key);
*pkey_type_out = S2N_PKEY_TYPE_ECDSA;
break;
default:
POSIX_BAIL(S2N_ERR_DECODE_CERTIFICATE);
}
pub_key->pkey = evp_public_key;
/* Reset to avoid DEFER_CLEANUP freeing our key */
evp_public_key = NULL;
return ret;
}
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