ssl/tls13_both.cc - boringssl - Git at Google

 /* Copyright (c) 2016, Google Inc.
  *
  * Permission to use, copy, modify, and/or 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 <openssl/ssl.h>

 #include <assert.h>
 #include <string.h>

 #include <utility>

 #include <openssl/bytestring.h>
 #include <openssl/err.h>
 #include <openssl/hkdf.h>
 #include <openssl/mem.h>
 #include <openssl/stack.h>
 #include <openssl/x509.h>

 #include "../crypto/internal.h"
 #include "internal.h"


 namespace bssl {

 // kMaxKeyUpdates is the number of consecutive KeyUpdates that will be
 // processed. Without this limit an attacker could force unbounded processing
 // without being able to return application data.
 static const uint8_t kMaxKeyUpdates = 32;

 const uint8_t kHelloRetryRequest[SSL3_RANDOM_SIZE] = {
     0xcf, 0x21, 0xad, 0x74, 0xe5, 0x9a, 0x61, 0x11, 0xbe, 0x1d, 0x8c,
     0x02, 0x1e, 0x65, 0xb8, 0x91, 0xc2, 0xa2, 0x11, 0x16, 0x7a, 0xbb,
     0x8c, 0x5e, 0x07, 0x9e, 0x09, 0xe2, 0xc8, 0xa8, 0x33, 0x9c,
 };

 bool tls13_get_cert_verify_signature_input(
     SSL_HANDSHAKE *hs, Array<uint8_t> *out,
     enum ssl_cert_verify_context_t cert_verify_context) {
   ScopedCBB cbb;
   if (!CBB_init(cbb.get(), 64 + 33 + 1 + 2 * EVP_MAX_MD_SIZE)) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
     return false;
   }

   for (size_t i = 0; i < 64; i++) {
     if (!CBB_add_u8(cbb.get(), 0x20)) {
       OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
       return false;
     }
   }

   Span<const char> context;
   if (cert_verify_context == ssl_cert_verify_server) {
     static const char kContext[] = "TLS 1.3, server CertificateVerify";
     context = kContext;
   } else if (cert_verify_context == ssl_cert_verify_client) {
     static const char kContext[] = "TLS 1.3, client CertificateVerify";
     context = kContext;
   } else if (cert_verify_context == ssl_cert_verify_channel_id) {
     static const char kContext[] = "TLS 1.3, Channel ID";
     context = kContext;
   } else {
     OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
     return false;
   }

   // Note |context| includes the NUL byte separator.
   if (!CBB_add_bytes(cbb.get(),
                      reinterpret_cast<const uint8_t *>(context.data()),
                      context.size())) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
     return false;
   }

   uint8_t context_hash[EVP_MAX_MD_SIZE];
   size_t context_hash_len;
   if (!hs->transcript.GetHash(context_hash, &context_hash_len) ||
       !CBB_add_bytes(cbb.get(), context_hash, context_hash_len) ||
       !CBBFinishArray(cbb.get(), out)) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
     return false;
   }

   return true;
 }

 int tls13_process_certificate(SSL_HANDSHAKE *hs, const SSLMessage &msg,
                               int allow_anonymous) {
   SSL *const ssl = hs->ssl;
   CBS body = msg.body, context, certificate_list;
   if (!CBS_get_u8_length_prefixed(&body, &context) ||
       CBS_len(&context) != 0 ||
       !CBS_get_u24_length_prefixed(&body, &certificate_list) ||
       CBS_len(&body) != 0) {
     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
     return 0;
   }

   UniquePtr<STACK_OF(CRYPTO_BUFFER)> certs(sk_CRYPTO_BUFFER_new_null());
   if (!certs) {
     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
     OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
     return 0;
   }

   const bool retain_sha256 =
       ssl->server && ssl->retain_only_sha256_of_client_certs;
   UniquePtr<EVP_PKEY> pkey;
   while (CBS_len(&certificate_list) > 0) {
     CBS certificate, extensions;
     if (!CBS_get_u24_length_prefixed(&certificate_list, &certificate) ||
         !CBS_get_u16_length_prefixed(&certificate_list, &extensions) ||
         CBS_len(&certificate) == 0) {
       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
       OPENSSL_PUT_ERROR(SSL, SSL_R_CERT_LENGTH_MISMATCH);
       return 0;
     }

     if (sk_CRYPTO_BUFFER_num(certs.get()) == 0) {
       pkey = ssl_cert_parse_pubkey(&certificate);
       if (!pkey) {
         ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
         OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
         return 0;
       }
       // TLS 1.3 always uses certificate keys for signing thus the correct
       // keyUsage is enforced.
       if (!ssl_cert_check_digital_signature_key_usage(&certificate)) {
         ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
         return 0;
       }

       if (retain_sha256) {
         // Retain the hash of the leaf certificate if requested.
         SHA256(CBS_data(&certificate), CBS_len(&certificate),
                hs->new_session->peer_sha256);
       }
     }

     UniquePtr<CRYPTO_BUFFER> buf(
         CRYPTO_BUFFER_new_from_CBS(&certificate, ssl->ctx->pool));
     if (!buf ||
         !PushToStack(certs.get(), std::move(buf))) {
       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
       OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
       return 0;
     }

     // Parse out the extensions.
     bool have_status_request = false, have_sct = false;
     CBS status_request, sct;
     const SSL_EXTENSION_TYPE ext_types[] = {
         {TLSEXT_TYPE_status_request, &have_status_request, &status_request},
         {TLSEXT_TYPE_certificate_timestamp, &have_sct, &sct},
     };

     uint8_t alert = SSL_AD_DECODE_ERROR;
     if (!ssl_parse_extensions(&extensions, &alert, ext_types,
                               OPENSSL_ARRAY_SIZE(ext_types),
                               0 /* reject unknown */)) {
       ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
       return 0;
     }

     // All Certificate extensions are parsed, but only the leaf extensions are
     // stored.
     if (have_status_request) {
       if (ssl->server || !ssl->ocsp_stapling_enabled) {
         OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
         ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNSUPPORTED_EXTENSION);
         return 0;
       }

       uint8_t status_type;
       CBS ocsp_response;
       if (!CBS_get_u8(&status_request, &status_type) ||
           status_type != TLSEXT_STATUSTYPE_ocsp ||
           !CBS_get_u24_length_prefixed(&status_request, &ocsp_response) ||
           CBS_len(&ocsp_response) == 0 ||
           CBS_len(&status_request) != 0) {
         ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
         return 0;
       }

       if (sk_CRYPTO_BUFFER_num(certs.get()) == 1) {
         CRYPTO_BUFFER_free(hs->new_session->ocsp_response);
         hs->new_session->ocsp_response =
             CRYPTO_BUFFER_new_from_CBS(&ocsp_response, ssl->ctx->pool);
         if (hs->new_session->ocsp_response == nullptr) {
           ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
           return 0;
         }
       }
     }

     if (have_sct) {
       if (ssl->server || !ssl->signed_cert_timestamps_enabled) {
         OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
         ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNSUPPORTED_EXTENSION);
         return 0;
       }

       if (!ssl_is_sct_list_valid(&sct)) {
         OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION);
         ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
         return 0;
       }

       if (sk_CRYPTO_BUFFER_num(certs.get()) == 1) {
         CRYPTO_BUFFER_free(hs->new_session->signed_cert_timestamp_list);
         hs->new_session->signed_cert_timestamp_list =
             CRYPTO_BUFFER_new_from_CBS(&sct, ssl->ctx->pool);
         if (hs->new_session->signed_cert_timestamp_list == nullptr) {
           ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
           return 0;
         }
       }
     }
   }

   // Store a null certificate list rather than an empty one if the peer didn't
   // send certificates.
   if (sk_CRYPTO_BUFFER_num(certs.get()) == 0) {
     certs.reset();
   }

   hs->peer_pubkey = std::move(pkey);

   sk_CRYPTO_BUFFER_pop_free(hs->new_session->certs, CRYPTO_BUFFER_free);
   hs->new_session->certs = certs.release();

   if (!ssl->ctx->x509_method->session_cache_objects(hs->new_session.get())) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
     return 0;
   }

   if (sk_CRYPTO_BUFFER_num(hs->new_session->certs) == 0) {
     if (!allow_anonymous) {
       OPENSSL_PUT_ERROR(SSL, SSL_R_PEER_DID_NOT_RETURN_A_CERTIFICATE);
       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_CERTIFICATE_REQUIRED);
       return 0;
     }

     // OpenSSL returns X509_V_OK when no certificates are requested. This is
     // classed by them as a bug, but it's assumed by at least NGINX.
     hs->new_session->verify_result = X509_V_OK;

     // No certificate, so nothing more to do.
     return 1;
   }

   hs->new_session->peer_sha256_valid = retain_sha256;
   return 1;
 }

 int tls13_process_certificate_verify(SSL_HANDSHAKE *hs, const SSLMessage &msg) {
   SSL *const ssl = hs->ssl;
   if (hs->peer_pubkey == NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
     return 0;
   }

   CBS body = msg.body, signature;
   uint16_t signature_algorithm;
   if (!CBS_get_u16(&body, &signature_algorithm) ||
       !CBS_get_u16_length_prefixed(&body, &signature) ||
       CBS_len(&body) != 0) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
     return 0;
   }

   uint8_t alert = SSL_AD_DECODE_ERROR;
   if (!tls12_check_peer_sigalg(ssl, &alert, signature_algorithm)) {
     ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
     return 0;
   }
   hs->new_session->peer_signature_algorithm = signature_algorithm;

   Array<uint8_t> input;
   if (!tls13_get_cert_verify_signature_input(
           hs, &input,
           ssl->server ? ssl_cert_verify_client : ssl_cert_verify_server)) {
     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
     return 0;
   }

   bool sig_ok = ssl_public_key_verify(ssl, signature, signature_algorithm,
                                       hs->peer_pubkey.get(), input);
 #if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
   sig_ok = true;
   ERR_clear_error();
 #endif
   if (!sig_ok) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SIGNATURE);
     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
     return 0;
   }

   return 1;
 }

 int tls13_process_finished(SSL_HANDSHAKE *hs, const SSLMessage &msg,
                            int use_saved_value) {
   SSL *const ssl = hs->ssl;
   uint8_t verify_data_buf[EVP_MAX_MD_SIZE];
   const uint8_t *verify_data;
   size_t verify_data_len;
   if (use_saved_value) {
     assert(ssl->server);
     verify_data = hs->expected_client_finished;
     verify_data_len = hs->hash_len;
   } else {
     if (!tls13_finished_mac(hs, verify_data_buf, &verify_data_len,
                             !ssl->server)) {
       return 0;
     }
     verify_data = verify_data_buf;
   }

   int finished_ok = CBS_mem_equal(&msg.body, verify_data, verify_data_len);
 #if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
   finished_ok = 1;
 #endif
   if (!finished_ok) {
     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
     OPENSSL_PUT_ERROR(SSL, SSL_R_DIGEST_CHECK_FAILED);
     return 0;
   }

   return 1;
 }

 int tls13_add_certificate(SSL_HANDSHAKE *hs) {
   SSL *const ssl = hs->ssl;
   ScopedCBB cbb;
   CBB body, certificate_list;
   if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_CERTIFICATE) ||
       // The request context is always empty in the handshake.
       !CBB_add_u8(&body, 0) ||
       !CBB_add_u24_length_prefixed(&body, &certificate_list)) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
     return 0;
   }

   if (!ssl_has_certificate(ssl)) {
     return ssl_add_message_cbb(ssl, cbb.get());
   }

   CERT *cert = ssl->cert;
   CRYPTO_BUFFER *leaf_buf = sk_CRYPTO_BUFFER_value(cert->chain, 0);
   CBB leaf, extensions;
   if (!CBB_add_u24_length_prefixed(&certificate_list, &leaf) ||
       !CBB_add_bytes(&leaf, CRYPTO_BUFFER_data(leaf_buf),
                      CRYPTO_BUFFER_len(leaf_buf)) ||
       !CBB_add_u16_length_prefixed(&certificate_list, &extensions)) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
     return 0;
   }

   if (hs->scts_requested && ssl->cert->signed_cert_timestamp_list != NULL) {
     CBB contents;
     if (!CBB_add_u16(&extensions, TLSEXT_TYPE_certificate_timestamp) ||
         !CBB_add_u16_length_prefixed(&extensions, &contents) ||
         !CBB_add_bytes(
             &contents,
             CRYPTO_BUFFER_data(ssl->cert->signed_cert_timestamp_list),
             CRYPTO_BUFFER_len(ssl->cert->signed_cert_timestamp_list)) ||
         !CBB_flush(&extensions)) {
       OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
       return 0;
     }
   }

   if (hs->ocsp_stapling_requested &&
       ssl->cert->ocsp_response != NULL) {
     CBB contents, ocsp_response;
     if (!CBB_add_u16(&extensions, TLSEXT_TYPE_status_request) ||
         !CBB_add_u16_length_prefixed(&extensions, &contents) ||
         !CBB_add_u8(&contents, TLSEXT_STATUSTYPE_ocsp) ||
         !CBB_add_u24_length_prefixed(&contents, &ocsp_response) ||
         !CBB_add_bytes(&ocsp_response,
                        CRYPTO_BUFFER_data(ssl->cert->ocsp_response),
                        CRYPTO_BUFFER_len(ssl->cert->ocsp_response)) ||
         !CBB_flush(&extensions)) {
       OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
       return 0;
     }
   }

   for (size_t i = 1; i < sk_CRYPTO_BUFFER_num(cert->chain); i++) {
     CRYPTO_BUFFER *cert_buf = sk_CRYPTO_BUFFER_value(cert->chain, i);
     CBB child;
     if (!CBB_add_u24_length_prefixed(&certificate_list, &child) ||
         !CBB_add_bytes(&child, CRYPTO_BUFFER_data(cert_buf),
                        CRYPTO_BUFFER_len(cert_buf)) ||
         !CBB_add_u16(&certificate_list, 0 /* no extensions */)) {
       OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
       return 0;
     }
   }

   return ssl_add_message_cbb(ssl, cbb.get());
 }

 enum ssl_private_key_result_t tls13_add_certificate_verify(SSL_HANDSHAKE *hs) {
   SSL *const ssl = hs->ssl;
   uint16_t signature_algorithm;
   if (!tls1_choose_signature_algorithm(hs, &signature_algorithm)) {
     return ssl_private_key_failure;
   }

   ScopedCBB cbb;
   CBB body;
   if (!ssl->method->init_message(ssl, cbb.get(), &body,
                                  SSL3_MT_CERTIFICATE_VERIFY) ||
       !CBB_add_u16(&body, signature_algorithm)) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
     return ssl_private_key_failure;
   }

   // Sign the digest.
   CBB child;
   const size_t max_sig_len = EVP_PKEY_size(hs->local_pubkey.get());
   uint8_t *sig;
   size_t sig_len;
   if (!CBB_add_u16_length_prefixed(&body, &child) ||
       !CBB_reserve(&child, &sig, max_sig_len)) {
     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
     return ssl_private_key_failure;
   }

   Array<uint8_t> msg;
   if (!tls13_get_cert_verify_signature_input(
           hs, &msg,
           ssl->server ? ssl_cert_verify_server : ssl_cert_verify_client)) {
     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
     return ssl_private_key_failure;
   }

   enum ssl_private_key_result_t sign_result = ssl_private_key_sign(
       hs, sig, &sig_len, max_sig_len, signature_algorithm, msg);
   if (sign_result != ssl_private_key_success) {
     return sign_result;
   }

   if (!CBB_did_write(&child, sig_len) ||
       !ssl_add_message_cbb(ssl, cbb.get())) {
     return ssl_private_key_failure;
   }

   return ssl_private_key_success;
 }

 int tls13_add_finished(SSL_HANDSHAKE *hs) {
   SSL *const ssl = hs->ssl;
   size_t verify_data_len;
   uint8_t verify_data[EVP_MAX_MD_SIZE];

   if (!tls13_finished_mac(hs, verify_data, &verify_data_len, ssl->server)) {
     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
     OPENSSL_PUT_ERROR(SSL, SSL_R_DIGEST_CHECK_FAILED);
     return 0;
   }

   ScopedCBB cbb;
   CBB body;
   if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_FINISHED) ||
       !CBB_add_bytes(&body, verify_data, verify_data_len) ||
       !ssl_add_message_cbb(ssl, cbb.get())) {
     return 0;
   }

   return 1;
 }

 static int tls13_receive_key_update(SSL *ssl, const SSLMessage &msg) {
   CBS body = msg.body;
   uint8_t key_update_request;
   if (!CBS_get_u8(&body, &key_update_request) ||
       CBS_len(&body) != 0 ||
       (key_update_request != SSL_KEY_UPDATE_NOT_REQUESTED &&
        key_update_request != SSL_KEY_UPDATE_REQUESTED)) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
     return 0;
   }

   if (!tls13_rotate_traffic_key(ssl, evp_aead_open)) {
     return 0;
   }

   // Acknowledge the KeyUpdate
   if (key_update_request == SSL_KEY_UPDATE_REQUESTED &&
       !ssl->s3->key_update_pending) {
     ScopedCBB cbb;
     CBB body_cbb;
     if (!ssl->method->init_message(ssl, cbb.get(), &body_cbb,
                                    SSL3_MT_KEY_UPDATE) ||
         !CBB_add_u8(&body_cbb, SSL_KEY_UPDATE_NOT_REQUESTED) ||
         !ssl_add_message_cbb(ssl, cbb.get()) ||
         !tls13_rotate_traffic_key(ssl, evp_aead_seal)) {
       return 0;
     }

     // Suppress KeyUpdate acknowledgments until this change is written to the
     // wire. This prevents us from accumulating write obligations when read and
     // write progress at different rates. See draft-ietf-tls-tls13-18, section
     // 4.5.3.
     ssl->s3->key_update_pending = true;
   }

   return 1;
 }

 int tls13_post_handshake(SSL *ssl, const SSLMessage &msg) {
   if (msg.type == SSL3_MT_KEY_UPDATE) {
     ssl->s3->key_update_count++;
     if (ssl->s3->key_update_count > kMaxKeyUpdates) {
       OPENSSL_PUT_ERROR(SSL, SSL_R_TOO_MANY_KEY_UPDATES);
       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
       return 0;
     }

     return tls13_receive_key_update(ssl, msg);
   }

   ssl->s3->key_update_count = 0;

   if (msg.type == SSL3_MT_NEW_SESSION_TICKET && !ssl->server) {
     return tls13_process_new_session_ticket(ssl, msg);
   }

   ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
   OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_MESSAGE);
   return 0;
 }

 }  // namespace bssl
	/* Copyright (c) 2016, Google Inc.
	*
	* Permission to use, copy, modify, and/or 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 <openssl/ssl.h>

	#include <assert.h>
	#include <string.h>

	#include <utility>

	#include <openssl/bytestring.h>
	#include <openssl/err.h>
	#include <openssl/hkdf.h>
	#include <openssl/mem.h>
	#include <openssl/stack.h>
	#include <openssl/x509.h>

	#include "../crypto/internal.h"
	#include "internal.h"


	namespace bssl {

	// kMaxKeyUpdates is the number of consecutive KeyUpdates that will be
	// processed. Without this limit an attacker could force unbounded processing
	// without being able to return application data.
	static const uint8_t kMaxKeyUpdates = 32;

	const uint8_t kHelloRetryRequest[SSL3_RANDOM_SIZE] = {
	0xcf, 0x21, 0xad, 0x74, 0xe5, 0x9a, 0x61, 0x11, 0xbe, 0x1d, 0x8c,
	0x02, 0x1e, 0x65, 0xb8, 0x91, 0xc2, 0xa2, 0x11, 0x16, 0x7a, 0xbb,
	0x8c, 0x5e, 0x07, 0x9e, 0x09, 0xe2, 0xc8, 0xa8, 0x33, 0x9c,
	};

	bool tls13_get_cert_verify_signature_input(
	SSL_HANDSHAKE hs, Array<uint8_t> out,
	enum ssl_cert_verify_context_t cert_verify_context) {
	ScopedCBB cbb;
	if (!CBB_init(cbb.get(), 64 + 33 + 1 + 2 * EVP_MAX_MD_SIZE)) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
	return false;
	}

	for (size_t i = 0; i < 64; i++) {
	if (!CBB_add_u8(cbb.get(), 0x20)) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
	return false;
	}
	}

	Span<const char> context;
	if (cert_verify_context == ssl_cert_verify_server) {
	static const char kContext[] = "TLS 1.3, server CertificateVerify";
	context = kContext;
	} else if (cert_verify_context == ssl_cert_verify_client) {
	static const char kContext[] = "TLS 1.3, client CertificateVerify";
	context = kContext;
	} else if (cert_verify_context == ssl_cert_verify_channel_id) {
	static const char kContext[] = "TLS 1.3, Channel ID";
	context = kContext;
	} else {
	OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
	return false;
	}

	// Note \|context\| includes the NUL byte separator.
	if (!CBB_add_bytes(cbb.get(),
	reinterpret_cast<const uint8_t *>(context.data()),
	context.size())) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
	return false;
	}

	uint8_t context_hash[EVP_MAX_MD_SIZE];
	size_t context_hash_len;
	if (!hs->transcript.GetHash(context_hash, &context_hash_len) \|\|
	!CBB_add_bytes(cbb.get(), context_hash, context_hash_len) \|\|
	!CBBFinishArray(cbb.get(), out)) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
	return false;
	}

	return true;
	}

	int tls13_process_certificate(SSL_HANDSHAKE *hs, const SSLMessage &msg,
	int allow_anonymous) {
	SSL *const ssl = hs->ssl;
	CBS body = msg.body, context, certificate_list;
	if (!CBS_get_u8_length_prefixed(&body, &context) \|\|
	CBS_len(&context) != 0 \|\|
	!CBS_get_u24_length_prefixed(&body, &certificate_list) \|\|
	CBS_len(&body) != 0) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
	return 0;
	}

	UniquePtr<STACK_OF(CRYPTO_BUFFER)> certs(sk_CRYPTO_BUFFER_new_null());
	if (!certs) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
	return 0;
	}

	const bool retain_sha256 =
	ssl->server && ssl->retain_only_sha256_of_client_certs;
	UniquePtr<EVP_PKEY> pkey;
	while (CBS_len(&certificate_list) > 0) {
	CBS certificate, extensions;
	if (!CBS_get_u24_length_prefixed(&certificate_list, &certificate) \|\|
	!CBS_get_u16_length_prefixed(&certificate_list, &extensions) \|\|
	CBS_len(&certificate) == 0) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	OPENSSL_PUT_ERROR(SSL, SSL_R_CERT_LENGTH_MISMATCH);
	return 0;
	}

	if (sk_CRYPTO_BUFFER_num(certs.get()) == 0) {
	pkey = ssl_cert_parse_pubkey(&certificate);
	if (!pkey) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
	return 0;
	}
	// TLS 1.3 always uses certificate keys for signing thus the correct
	// keyUsage is enforced.
	if (!ssl_cert_check_digital_signature_key_usage(&certificate)) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
	return 0;
	}

	if (retain_sha256) {
	// Retain the hash of the leaf certificate if requested.
	SHA256(CBS_data(&certificate), CBS_len(&certificate),
	hs->new_session->peer_sha256);
	}
	}

	UniquePtr<CRYPTO_BUFFER> buf(
	CRYPTO_BUFFER_new_from_CBS(&certificate, ssl->ctx->pool));
	if (!buf \|\|
	!PushToStack(certs.get(), std::move(buf))) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
	return 0;
	}

	// Parse out the extensions.
	bool have_status_request = false, have_sct = false;
	CBS status_request, sct;
	const SSL_EXTENSION_TYPE ext_types[] = {
	{TLSEXT_TYPE_status_request, &have_status_request, &status_request},
	{TLSEXT_TYPE_certificate_timestamp, &have_sct, &sct},
	};

	uint8_t alert = SSL_AD_DECODE_ERROR;
	if (!ssl_parse_extensions(&extensions, &alert, ext_types,
	OPENSSL_ARRAY_SIZE(ext_types),
	0 /* reject unknown */)) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
	return 0;
	}

	// All Certificate extensions are parsed, but only the leaf extensions are
	// stored.
	if (have_status_request) {
	if (ssl->server \|\| !ssl->ocsp_stapling_enabled) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNSUPPORTED_EXTENSION);
	return 0;
	}

	uint8_t status_type;
	CBS ocsp_response;
	if (!CBS_get_u8(&status_request, &status_type) \|\|
	status_type != TLSEXT_STATUSTYPE_ocsp \|\|
	!CBS_get_u24_length_prefixed(&status_request, &ocsp_response) \|\|
	CBS_len(&ocsp_response) == 0 \|\|
	CBS_len(&status_request) != 0) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	return 0;
	}

	if (sk_CRYPTO_BUFFER_num(certs.get()) == 1) {
	CRYPTO_BUFFER_free(hs->new_session->ocsp_response);
	hs->new_session->ocsp_response =
	CRYPTO_BUFFER_new_from_CBS(&ocsp_response, ssl->ctx->pool);
	if (hs->new_session->ocsp_response == nullptr) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	return 0;
	}
	}
	}

	if (have_sct) {
	if (ssl->server \|\| !ssl->signed_cert_timestamps_enabled) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNSUPPORTED_EXTENSION);
	return 0;
	}

	if (!ssl_is_sct_list_valid(&sct)) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION);
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	return 0;
	}

	if (sk_CRYPTO_BUFFER_num(certs.get()) == 1) {
	CRYPTO_BUFFER_free(hs->new_session->signed_cert_timestamp_list);
	hs->new_session->signed_cert_timestamp_list =
	CRYPTO_BUFFER_new_from_CBS(&sct, ssl->ctx->pool);
	if (hs->new_session->signed_cert_timestamp_list == nullptr) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	return 0;
	}
	}
	}
	}

	// Store a null certificate list rather than an empty one if the peer didn't
	// send certificates.
	if (sk_CRYPTO_BUFFER_num(certs.get()) == 0) {
	certs.reset();
	}

	hs->peer_pubkey = std::move(pkey);

	sk_CRYPTO_BUFFER_pop_free(hs->new_session->certs, CRYPTO_BUFFER_free);
	hs->new_session->certs = certs.release();

	if (!ssl->ctx->x509_method->session_cache_objects(hs->new_session.get())) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	return 0;
	}

	if (sk_CRYPTO_BUFFER_num(hs->new_session->certs) == 0) {
	if (!allow_anonymous) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_PEER_DID_NOT_RETURN_A_CERTIFICATE);
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_CERTIFICATE_REQUIRED);
	return 0;
	}

	// OpenSSL returns X509_V_OK when no certificates are requested. This is
	// classed by them as a bug, but it's assumed by at least NGINX.
	hs->new_session->verify_result = X509_V_OK;

	// No certificate, so nothing more to do.
	return 1;
	}

	hs->new_session->peer_sha256_valid = retain_sha256;
	return 1;
	}

	int tls13_process_certificate_verify(SSL_HANDSHAKE *hs, const SSLMessage &msg) {
	SSL *const ssl = hs->ssl;
	if (hs->peer_pubkey == NULL) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	return 0;
	}

	CBS body = msg.body, signature;
	uint16_t signature_algorithm;
	if (!CBS_get_u16(&body, &signature_algorithm) \|\|
	!CBS_get_u16_length_prefixed(&body, &signature) \|\|
	CBS_len(&body) != 0) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	return 0;
	}

	uint8_t alert = SSL_AD_DECODE_ERROR;
	if (!tls12_check_peer_sigalg(ssl, &alert, signature_algorithm)) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
	return 0;
	}
	hs->new_session->peer_signature_algorithm = signature_algorithm;

	Array<uint8_t> input;
	if (!tls13_get_cert_verify_signature_input(
	hs, &input,
	ssl->server ? ssl_cert_verify_client : ssl_cert_verify_server)) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	return 0;
	}

	bool sig_ok = ssl_public_key_verify(ssl, signature, signature_algorithm,
	hs->peer_pubkey.get(), input);
	#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
	sig_ok = true;
	ERR_clear_error();
	#endif
	if (!sig_ok) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SIGNATURE);
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
	return 0;
	}

	return 1;
	}

	int tls13_process_finished(SSL_HANDSHAKE *hs, const SSLMessage &msg,
	int use_saved_value) {
	SSL *const ssl = hs->ssl;
	uint8_t verify_data_buf[EVP_MAX_MD_SIZE];
	const uint8_t *verify_data;
	size_t verify_data_len;
	if (use_saved_value) {
	assert(ssl->server);
	verify_data = hs->expected_client_finished;
	verify_data_len = hs->hash_len;
	} else {
	if (!tls13_finished_mac(hs, verify_data_buf, &verify_data_len,
	!ssl->server)) {
	return 0;
	}
	verify_data = verify_data_buf;
	}

	int finished_ok = CBS_mem_equal(&msg.body, verify_data, verify_data_len);
	#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
	finished_ok = 1;
	#endif
	if (!finished_ok) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
	OPENSSL_PUT_ERROR(SSL, SSL_R_DIGEST_CHECK_FAILED);
	return 0;
	}

	return 1;
	}

	int tls13_add_certificate(SSL_HANDSHAKE *hs) {
	SSL *const ssl = hs->ssl;
	ScopedCBB cbb;
	CBB body, certificate_list;
	if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_CERTIFICATE) \|\|
	// The request context is always empty in the handshake.
	!CBB_add_u8(&body, 0) \|\|
	!CBB_add_u24_length_prefixed(&body, &certificate_list)) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	return 0;
	}

	if (!ssl_has_certificate(ssl)) {
	return ssl_add_message_cbb(ssl, cbb.get());
	}

	CERT *cert = ssl->cert;
	CRYPTO_BUFFER *leaf_buf = sk_CRYPTO_BUFFER_value(cert->chain, 0);
	CBB leaf, extensions;
	if (!CBB_add_u24_length_prefixed(&certificate_list, &leaf) \|\|
	!CBB_add_bytes(&leaf, CRYPTO_BUFFER_data(leaf_buf),
	CRYPTO_BUFFER_len(leaf_buf)) \|\|
	!CBB_add_u16_length_prefixed(&certificate_list, &extensions)) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	return 0;
	}

	if (hs->scts_requested && ssl->cert->signed_cert_timestamp_list != NULL) {
	CBB contents;
	if (!CBB_add_u16(&extensions, TLSEXT_TYPE_certificate_timestamp) \|\|
	!CBB_add_u16_length_prefixed(&extensions, &contents) \|\|
	!CBB_add_bytes(
	&contents,
	CRYPTO_BUFFER_data(ssl->cert->signed_cert_timestamp_list),
	CRYPTO_BUFFER_len(ssl->cert->signed_cert_timestamp_list)) \|\|
	!CBB_flush(&extensions)) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	return 0;
	}
	}

	if (hs->ocsp_stapling_requested &&
	ssl->cert->ocsp_response != NULL) {
	CBB contents, ocsp_response;
	if (!CBB_add_u16(&extensions, TLSEXT_TYPE_status_request) \|\|
	!CBB_add_u16_length_prefixed(&extensions, &contents) \|\|
	!CBB_add_u8(&contents, TLSEXT_STATUSTYPE_ocsp) \|\|
	!CBB_add_u24_length_prefixed(&contents, &ocsp_response) \|\|
	!CBB_add_bytes(&ocsp_response,
	CRYPTO_BUFFER_data(ssl->cert->ocsp_response),
	CRYPTO_BUFFER_len(ssl->cert->ocsp_response)) \|\|
	!CBB_flush(&extensions)) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	return 0;
	}
	}

	for (size_t i = 1; i < sk_CRYPTO_BUFFER_num(cert->chain); i++) {
	CRYPTO_BUFFER *cert_buf = sk_CRYPTO_BUFFER_value(cert->chain, i);
	CBB child;
	if (!CBB_add_u24_length_prefixed(&certificate_list, &child) \|\|
	!CBB_add_bytes(&child, CRYPTO_BUFFER_data(cert_buf),
	CRYPTO_BUFFER_len(cert_buf)) \|\|
	!CBB_add_u16(&certificate_list, 0 /* no extensions */)) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	return 0;
	}
	}

	return ssl_add_message_cbb(ssl, cbb.get());
	}

	enum ssl_private_key_result_t tls13_add_certificate_verify(SSL_HANDSHAKE *hs) {
	SSL *const ssl = hs->ssl;
	uint16_t signature_algorithm;
	if (!tls1_choose_signature_algorithm(hs, &signature_algorithm)) {
	return ssl_private_key_failure;
	}

	ScopedCBB cbb;
	CBB body;
	if (!ssl->method->init_message(ssl, cbb.get(), &body,
	SSL3_MT_CERTIFICATE_VERIFY) \|\|
	!CBB_add_u16(&body, signature_algorithm)) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	return ssl_private_key_failure;
	}

	// Sign the digest.
	CBB child;
	const size_t max_sig_len = EVP_PKEY_size(hs->local_pubkey.get());
	uint8_t *sig;
	size_t sig_len;
	if (!CBB_add_u16_length_prefixed(&body, &child) \|\|
	!CBB_reserve(&child, &sig, max_sig_len)) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	return ssl_private_key_failure;
	}

	Array<uint8_t> msg;
	if (!tls13_get_cert_verify_signature_input(
	hs, &msg,
	ssl->server ? ssl_cert_verify_server : ssl_cert_verify_client)) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	return ssl_private_key_failure;
	}

	enum ssl_private_key_result_t sign_result = ssl_private_key_sign(
	hs, sig, &sig_len, max_sig_len, signature_algorithm, msg);
	if (sign_result != ssl_private_key_success) {
	return sign_result;
	}

	if (!CBB_did_write(&child, sig_len) \|\|
	!ssl_add_message_cbb(ssl, cbb.get())) {
	return ssl_private_key_failure;
	}

	return ssl_private_key_success;
	}

	int tls13_add_finished(SSL_HANDSHAKE *hs) {
	SSL *const ssl = hs->ssl;
	size_t verify_data_len;
	uint8_t verify_data[EVP_MAX_MD_SIZE];

	if (!tls13_finished_mac(hs, verify_data, &verify_data_len, ssl->server)) {
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	OPENSSL_PUT_ERROR(SSL, SSL_R_DIGEST_CHECK_FAILED);
	return 0;
	}

	ScopedCBB cbb;
	CBB body;
	if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_FINISHED) \|\|
	!CBB_add_bytes(&body, verify_data, verify_data_len) \|\|
	!ssl_add_message_cbb(ssl, cbb.get())) {
	return 0;
	}

	return 1;
	}

	static int tls13_receive_key_update(SSL *ssl, const SSLMessage &msg) {
	CBS body = msg.body;
	uint8_t key_update_request;
	if (!CBS_get_u8(&body, &key_update_request) \|\|
	CBS_len(&body) != 0 \|\|
	(key_update_request != SSL_KEY_UPDATE_NOT_REQUESTED &&
	key_update_request != SSL_KEY_UPDATE_REQUESTED)) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	return 0;
	}

	if (!tls13_rotate_traffic_key(ssl, evp_aead_open)) {
	return 0;
	}

	// Acknowledge the KeyUpdate
	if (key_update_request == SSL_KEY_UPDATE_REQUESTED &&
	!ssl->s3->key_update_pending) {
	ScopedCBB cbb;
	CBB body_cbb;
	if (!ssl->method->init_message(ssl, cbb.get(), &body_cbb,
	SSL3_MT_KEY_UPDATE) \|\|
	!CBB_add_u8(&body_cbb, SSL_KEY_UPDATE_NOT_REQUESTED) \|\|
	!ssl_add_message_cbb(ssl, cbb.get()) \|\|
	!tls13_rotate_traffic_key(ssl, evp_aead_seal)) {
	return 0;
	}

	// Suppress KeyUpdate acknowledgments until this change is written to the
	// wire. This prevents us from accumulating write obligations when read and
	// write progress at different rates. See draft-ietf-tls-tls13-18, section
	// 4.5.3.
	ssl->s3->key_update_pending = true;
	}

	return 1;
	}

	int tls13_post_handshake(SSL *ssl, const SSLMessage &msg) {
	if (msg.type == SSL3_MT_KEY_UPDATE) {
	ssl->s3->key_update_count++;
	if (ssl->s3->key_update_count > kMaxKeyUpdates) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_TOO_MANY_KEY_UPDATES);
	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
	return 0;
	}

	return tls13_receive_key_update(ssl, msg);
	}

	ssl->s3->key_update_count = 0;

	if (msg.type == SSL3_MT_NEW_SESSION_TICKET && !ssl->server) {
	return tls13_process_new_session_ticket(ssl, msg);
	}

	ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
	OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_MESSAGE);
	return 0;
	}

	} // namespace bssl