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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.
*/
#pragma once
#include <openssl/x509v3.h>
#include "api/s2n.h"
#include "tls/s2n_signature_scheme.h"
/* one day, BoringSSL may add ocsp stapling support. Let's future proof this a bit by grabbing a definition
* that would have to be there when they add support */
#if defined(OPENSSL_IS_BORINGSSL) && !defined(OCSP_RESPONSE_STATUS_SUCCESSFUL)
#define S2N_OCSP_STAPLING_SUPPORTED 0
#else
#define S2N_OCSP_STAPLING_SUPPORTED 1
#endif /* defined(OPENSSL_IS_BORINGSSL) && !defined(OCSP_RESPONSE_STATUS_SUCCESSFUL) */
typedef enum {
UNINIT,
INIT,
READY_TO_VERIFY,
AWAITING_CRL_CALLBACK,
VALIDATED,
OCSP_VALIDATED,
} validator_state;
/** Return TRUE for trusted, FALSE for untrusted **/
typedef uint8_t (*verify_host)(const char *host_name, size_t host_name_len, void *data);
struct s2n_connection;
/**
* Trust store simply contains the trust store each connection should validate certs against.
* For most use cases, you only need one of these per application.
*/
struct s2n_x509_trust_store {
X509_STORE *trust_store;
/* Indicates whether system default certs have been loaded into the trust store */
unsigned loaded_system_certs : 1;
};
/**
* You should have one instance of this per connection.
*/
struct s2n_x509_validator {
struct s2n_x509_trust_store *trust_store;
X509_STORE_CTX *store_ctx;
uint8_t skip_cert_validation;
uint8_t check_stapled_ocsp;
uint16_t max_chain_depth;
STACK_OF(X509) *cert_chain_from_wire;
int state;
struct s2n_array *crl_lookup_list;
};
struct s2n_cert_validation_info {
unsigned finished : 1;
unsigned accepted : 1;
};
/** Some libcrypto implementations do not support OCSP validation. Returns 1 if supported, 0 otherwise. */
uint8_t s2n_x509_ocsp_stapling_supported(void);
/** Initialize the trust store to empty defaults (no allocations happen here) */
void s2n_x509_trust_store_init_empty(struct s2n_x509_trust_store *store);
/** Returns TRUE if the trust store has certificates installed, FALSE otherwise */
uint8_t s2n_x509_trust_store_has_certs(struct s2n_x509_trust_store *store);
/** Initialize trust store from a PEM. This will allocate memory, and load PEM into the Trust Store **/
int s2n_x509_trust_store_add_pem(struct s2n_x509_trust_store *store, const char *pem);
/** Initialize trust store from a CA file. This will allocate memory, and load each cert in the file into the trust store
* Returns 0 on success, or S2N error codes on failure. */
int s2n_x509_trust_store_from_ca_file(struct s2n_x509_trust_store *store, const char *ca_pem_filename, const char *ca_dir);
/** Cleans up, and frees any underlying memory in the trust store. */
void s2n_x509_trust_store_wipe(struct s2n_x509_trust_store *store);
/** Initialize the validator in unsafe mode. No validity checks for OCSP, host checks, or X.509 will be performed. */
int s2n_x509_validator_init_no_x509_validation(struct s2n_x509_validator *validator);
/** Initialize the validator in safe mode. Will use trust store to validate x.509 certificates, ocsp responses, and will call
* the verify host callback to determine if a subject name or alternative name from the cert should be trusted.
* Returns 0 on success, and an S2N_ERR_* on failure.
*/
int s2n_x509_validator_init(struct s2n_x509_validator *validator, struct s2n_x509_trust_store *trust_store, uint8_t check_ocsp);
/**
* Sets the maximum depth for a cert chain that can be used at validation.
*/
int s2n_x509_validator_set_max_chain_depth(struct s2n_x509_validator *validator, uint16_t max_depth);
/** Cleans up underlying memory and data members. Struct can be reused afterwards. */
int s2n_x509_validator_wipe(struct s2n_x509_validator *validator);
/**
* Validates a certificate chain against the configured trust store in safe mode. In unsafe mode, it will find the public key
* and return it but not validate the certificates. Alternative Names and Subject Name will be passed to the host verification callback.
* The verification callback will be possibly called multiple times depending on how many names are found.
* If any of those calls return TRUE, that stage of the validation will continue, otherwise once all names are tried and none matched as
* trusted, the chain will be considered UNTRUSTED.
*
* This function can only be called once per instance of an s2n_x509_validator. If must be called prior to calling
* s2n_x509_validator_validate_cert_stapled_ocsp_response().
*/
S2N_RESULT s2n_x509_validator_validate_cert_chain(struct s2n_x509_validator *validator, struct s2n_connection *conn,
uint8_t *cert_chain_in, uint32_t cert_chain_len, s2n_pkey_type *pkey_type,
struct s2n_pkey *public_key_out);
/**
* Validates an ocsp response against the most recent certificate chain. Also verifies the timestamps on the response. This function can only be
* called once per instance of an s2n_x509_validator and only after a successful call to s2n_x509_validator_validate_cert_chain().
*/
S2N_RESULT s2n_x509_validator_validate_cert_stapled_ocsp_response(struct s2n_x509_validator *validator, struct s2n_connection *conn,
const uint8_t *ocsp_response, uint32_t size);
/**
* Checks whether the peer's certificate chain has been received and validated.
* Should be verified before any use of the peer's certificate data.
*/
bool s2n_x509_validator_is_cert_chain_validated(const struct s2n_x509_validator *validator);
/**
* Validates that each certificate in a peer's cert chain contains only signature algorithms in a security policy's
* certificate_signatures_preference list.
*/
S2N_RESULT s2n_validate_certificate_signature(struct s2n_connection *conn, X509 *x509_cert);
/* Checks to see if a certificate has a signature algorithm that's in our certificate_signature_preferences list */
S2N_RESULT s2n_validate_sig_scheme_supported(struct s2n_connection *conn, X509 *x509_cert,
const struct s2n_signature_preferences *cert_sig_preferences);
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