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a20e535fb1
boringssl/ssl/tls13_server.c
David Benjamin cec7344bba Add a CBS version of SSL_early_callback_ctx_extension_get. 
Save a little bit of typing at the call site.

Change-Id: I818535409b57a694e5e0ea0e9741d89f2be89375
Reviewed-on: https://boringssl-review.googlesource.com/9090
Reviewed-by: Adam Langley <agl@google.com>
2016-08-03 20:47:05 +00:00

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/* 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 <openssl/bytestring.h>
#include <openssl/digest.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include <openssl/rand.h>
#include <openssl/stack.h>
#include "internal.h"
enum server_hs_state_t {
state_process_client_hello = 0,
state_send_hello_retry_request,
state_flush_hello_retry_request,
state_process_second_client_hello,
state_send_server_hello,
state_send_encrypted_extensions,
state_send_certificate_request,
state_send_server_certificate,
state_send_server_certificate_verify,
state_complete_server_certificate_verify,
state_send_server_finished,
state_flush,
state_process_client_certificate,
state_process_client_certificate_verify,
state_process_client_finished,
state_send_new_session_ticket,
state_flush_new_session_ticket,
state_done,
};
static const uint8_t kZeroes[EVP_MAX_MD_SIZE] = {0};
static int resolve_psk_secret(SSL *ssl) {
SSL_HANDSHAKE *hs = ssl->s3->hs;
if (ssl->s3->tmp.new_cipher->algorithm_auth != SSL_aPSK) {
return tls13_advance_key_schedule(ssl, kZeroes, hs->hash_len);
}
/* TODO(davidben): Support PSK. */
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return 0;
}
static int resolve_ecdhe_secret(SSL *ssl, int *out_need_retry,
struct ssl_early_callback_ctx *early_ctx) {
*out_need_retry = 0;
SSL_HANDSHAKE *hs = ssl->s3->hs;
if (ssl->s3->tmp.new_cipher->algorithm_mkey != SSL_kECDHE) {
return tls13_advance_key_schedule(ssl, kZeroes, hs->hash_len);
}
CBS key_share;
if (!ssl_early_callback_get_extension(early_ctx, &key_share,
TLSEXT_TYPE_key_share)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_KEY_SHARE);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_MISSING_EXTENSION);
return ssl_hs_error;
}
int found_key_share;
uint8_t *dhe_secret;
size_t dhe_secret_len;
uint8_t alert;
if (!ssl_ext_key_share_parse_clienthello(ssl, &found_key_share, &dhe_secret,
&dhe_secret_len, &alert,
&key_share)) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, alert);
return 0;
}
if (!found_key_share) {
*out_need_retry = 1;
return 0;
}
int ok = tls13_advance_key_schedule(ssl, dhe_secret, dhe_secret_len);
OPENSSL_free(dhe_secret);
return ok;
}
static enum ssl_hs_wait_t do_process_client_hello(SSL *ssl, SSL_HANDSHAKE *hs) {
if (!tls13_check_message_type(ssl, SSL3_MT_CLIENT_HELLO)) {
return ssl_hs_error;
}
struct ssl_early_callback_ctx early_ctx;
if (!ssl_early_callback_init(ssl, &early_ctx, ssl->init_msg,
ssl->init_num)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_CLIENTHELLO_PARSE_FAILED);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
CBS cbs, client_random, session_id, cipher_suites, compression_methods;
uint16_t client_wire_version;
CBS_init(&cbs, ssl->init_msg, ssl->init_num);
if (!CBS_get_u16(&cbs, &client_wire_version) ||
!CBS_get_bytes(&cbs, &client_random, SSL3_RANDOM_SIZE) ||
!CBS_get_u8_length_prefixed(&cbs, &session_id) ||
CBS_len(&session_id) > SSL_MAX_SSL_SESSION_ID_LENGTH) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
uint16_t min_version, max_version;
if (!ssl_get_version_range(ssl, &min_version, &max_version)) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
assert(ssl->s3->have_version);
/* Load the client random. */
memcpy(ssl->s3->client_random, CBS_data(&client_random), SSL3_RANDOM_SIZE);
SSL_set_session(ssl, NULL);
if (!ssl_get_new_session(ssl, 1 /* server */)) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
if (ssl->ctx->dos_protection_cb != NULL &&
ssl->ctx->dos_protection_cb(&early_ctx) == 0) {
/* Connection rejected for DOS reasons. */
OPENSSL_PUT_ERROR(SSL, SSL_R_CONNECTION_REJECTED);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ACCESS_DENIED);
return ssl_hs_error;
}
if (!CBS_get_u16_length_prefixed(&cbs, &cipher_suites) ||
CBS_len(&cipher_suites) == 0 ||
CBS_len(&cipher_suites) % 2 != 0 ||
!CBS_get_u8_length_prefixed(&cbs, &compression_methods) ||
CBS_len(&compression_methods) == 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
/* TLS 1.3 requires the peer only advertise the null compression. */
if (CBS_len(&compression_methods) != 1 ||
CBS_data(&compression_methods)[0] != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_COMPRESSION_LIST);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
/* TLS extensions. */
if (!ssl_parse_clienthello_tlsext(ssl, &cbs)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT);
return ssl_hs_error;
}
/* There should be nothing left over in the message. */
if (CBS_len(&cbs) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_PACKET_LENGTH);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
/* Let cert callback update server certificates if required.
*
* TODO(davidben): Can this get run earlier? */
if (ssl->cert->cert_cb != NULL) {
int rv = ssl->cert->cert_cb(ssl, ssl->cert->cert_cb_arg);
if (rv == 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_CERT_CB_ERROR);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
if (rv < 0) {
hs->state = state_process_client_hello;
return ssl_hs_x509_lookup;
}
}
STACK_OF(SSL_CIPHER) *ciphers =
ssl_bytes_to_cipher_list(ssl, &cipher_suites, max_version);
if (ciphers == NULL) {
return ssl_hs_error;
}
const SSL_CIPHER *cipher =
ssl3_choose_cipher(ssl, ciphers, ssl_get_cipher_preferences(ssl));
sk_SSL_CIPHER_free(ciphers);
if (cipher == NULL) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_SHARED_CIPHER);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
return ssl_hs_error;
}
ssl->s3->new_session->cipher = cipher;
ssl->s3->tmp.new_cipher = cipher;
ssl->method->received_flight(ssl);
/* The PRF hash is now known. Set up the key schedule and hash the
* ClientHello. */
size_t hash_len =
EVP_MD_size(ssl_get_handshake_digest(ssl_get_algorithm_prf(ssl)));
if (!tls13_init_key_schedule(ssl, kZeroes, hash_len)) {
return ssl_hs_error;
}
/* Resolve PSK and incorporate it into the secret. */
if (!resolve_psk_secret(ssl)) {
return ssl_hs_error;
}
/* Resolve ECDHE and incorporate it into the secret. */
int need_retry;
if (!resolve_ecdhe_secret(ssl, &need_retry, &early_ctx)) {
if (need_retry) {
hs->state = state_send_hello_retry_request;
return ssl_hs_ok;
}
return ssl_hs_error;
}
hs->state = state_send_server_hello;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_hello_retry_request(SSL *ssl,
SSL_HANDSHAKE *hs) {
CBB cbb, body, extensions;
uint16_t group_id;
if (!ssl->method->init_message(ssl, &cbb, &body,
SSL3_MT_HELLO_RETRY_REQUEST) ||
!CBB_add_u16(&body, ssl->version) ||
!CBB_add_u16(&body, ssl_cipher_get_value(ssl->s3->tmp.new_cipher)) ||
!tls1_get_shared_group(ssl, &group_id) ||
!CBB_add_u16(&body, group_id) ||
!CBB_add_u16_length_prefixed(&body, &extensions) ||
!ssl->method->finish_message(ssl, &cbb)) {
CBB_cleanup(&cbb);
return ssl_hs_error;
}
hs->state = state_flush_hello_retry_request;
return ssl_hs_write_message;
}
static enum ssl_hs_wait_t do_flush_hello_retry_request(SSL *ssl,
SSL_HANDSHAKE *hs) {
hs->state = state_process_second_client_hello;
return ssl_hs_flush_and_read_message;
}
static enum ssl_hs_wait_t do_process_second_client_hello(SSL *ssl,
SSL_HANDSHAKE *hs) {
if (!tls13_check_message_type(ssl, SSL3_MT_CLIENT_HELLO)) {
return ssl_hs_error;
}
struct ssl_early_callback_ctx early_ctx;
if (!ssl_early_callback_init(ssl, &early_ctx, ssl->init_msg,
ssl->init_num)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_CLIENTHELLO_PARSE_FAILED);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
int need_retry;
if (!resolve_ecdhe_secret(ssl, &need_retry, &early_ctx)) {
if (need_retry) {
/* Only send one HelloRetryRequest. */
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_CURVE);
}
return ssl_hs_error;
}
if (!ssl->method->hash_current_message(ssl)) {
return ssl_hs_error;
}
ssl->method->received_flight(ssl);
hs->state = state_send_server_hello;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_server_hello(SSL *ssl, SSL_HANDSHAKE *hs) {
CBB cbb, body, extensions;
if (!ssl->method->init_message(ssl, &cbb, &body, SSL3_MT_SERVER_HELLO) ||
!CBB_add_u16(&body, ssl->version) ||
!RAND_bytes(ssl->s3->server_random, sizeof(ssl->s3->server_random)) ||
!CBB_add_bytes(&body, ssl->s3->server_random, SSL3_RANDOM_SIZE) ||
!CBB_add_u16(&body, ssl_cipher_get_value(ssl->s3->tmp.new_cipher)) ||
!CBB_add_u16_length_prefixed(&body, &extensions) ||
!ssl_ext_key_share_add_serverhello(ssl, &extensions) ||
!ssl->method->finish_message(ssl, &cbb)) {
CBB_cleanup(&cbb);
return ssl_hs_error;
}
hs->state = state_send_encrypted_extensions;
return ssl_hs_write_message;
}
static enum ssl_hs_wait_t do_send_encrypted_extensions(SSL *ssl,
SSL_HANDSHAKE *hs) {
if (!tls13_set_handshake_traffic(ssl)) {
return ssl_hs_error;
}
CBB cbb, body;
if (!ssl->method->init_message(ssl, &cbb, &body,
SSL3_MT_ENCRYPTED_EXTENSIONS) ||
!ssl_add_serverhello_tlsext(ssl, &body) ||
!ssl->method->finish_message(ssl, &cbb)) {
CBB_cleanup(&cbb);
return ssl_hs_error;
}
hs->state = state_send_certificate_request;
return ssl_hs_write_message;
}
static enum ssl_hs_wait_t do_send_certificate_request(SSL *ssl,
SSL_HANDSHAKE *hs) {
/* Determine whether to request a client certificate. */
ssl->s3->tmp.cert_request = !!(ssl->verify_mode & SSL_VERIFY_PEER);
/* CertificateRequest may only be sent in certificate-based ciphers. */
if (!ssl_cipher_uses_certificate_auth(ssl->s3->tmp.new_cipher)) {
ssl->s3->tmp.cert_request = 0;
}
if (!ssl->s3->tmp.cert_request) {
/* Skip this state. */
hs->state = state_send_server_certificate;
return ssl_hs_ok;
}
CBB cbb, body, sigalgs_cbb;
if (!ssl->method->init_message(ssl, &cbb, &body,
SSL3_MT_CERTIFICATE_REQUEST) ||
!CBB_add_u8(&body, 0 /* no certificate_request_context. */)) {
goto err;
}
const uint16_t *sigalgs;
size_t sigalgs_len = tls12_get_psigalgs(ssl, &sigalgs);
if (!CBB_add_u16_length_prefixed(&body, &sigalgs_cbb)) {
goto err;
}
for (size_t i = 0; i < sigalgs_len; i++) {
if (!CBB_add_u16(&sigalgs_cbb, sigalgs[i])) {
goto err;
}
}
if (!ssl_add_client_CA_list(ssl, &body) ||
!CBB_add_u16(&body, 0 /* empty certificate_extensions. */) ||
!ssl->method->finish_message(ssl, &cbb)) {
goto err;
}
hs->state = state_send_server_certificate;
return ssl_hs_write_message;
err:
CBB_cleanup(&cbb);
return ssl_hs_error;
}
static enum ssl_hs_wait_t do_send_server_certificate(SSL *ssl,
SSL_HANDSHAKE *hs) {
if (!ssl_cipher_uses_certificate_auth(ssl->s3->tmp.new_cipher)) {
hs->state = state_send_server_finished;
return ssl_hs_ok;
}
if (!ssl_has_certificate(ssl)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_CERTIFICATE_SET);
return ssl_hs_error;
}
if (!tls13_prepare_certificate(ssl)) {
return ssl_hs_error;
}
hs->state = state_send_server_certificate_verify;
return ssl_hs_write_message;
}
static enum ssl_hs_wait_t do_send_server_certificate_verify(SSL *ssl,
SSL_HANDSHAKE *hs,
int is_first_run) {
switch (tls13_prepare_certificate_verify(ssl, is_first_run)) {
case ssl_private_key_success:
hs->state = state_send_server_finished;
return ssl_hs_write_message;
case ssl_private_key_retry:
hs->state = state_complete_server_certificate_verify;
return ssl_hs_private_key_operation;
case ssl_private_key_failure:
return ssl_hs_error;
}
assert(0);
return ssl_hs_error;
}
static enum ssl_hs_wait_t do_send_server_finished(SSL *ssl, SSL_HANDSHAKE *hs) {
if (!tls13_prepare_finished(ssl)) {
return ssl_hs_error;
}
hs->state = state_flush;
return ssl_hs_write_message;
}
static enum ssl_hs_wait_t do_flush(SSL *ssl, SSL_HANDSHAKE *hs) {
/* Update the secret to the master secret and derive traffic keys. */
if (!tls13_advance_key_schedule(ssl, kZeroes, hs->hash_len) ||
!tls13_derive_traffic_secret_0(ssl) ||
!tls13_set_traffic_key(ssl, type_data, evp_aead_seal,
hs->traffic_secret_0, hs->hash_len)) {
return ssl_hs_error;
}
hs->state = state_process_client_certificate;
return ssl_hs_flush_and_read_message;
}
static enum ssl_hs_wait_t do_process_client_certificate(SSL *ssl,
SSL_HANDSHAKE *hs) {
if (!ssl->s3->tmp.cert_request) {
/* Skip this state. */
hs->state = state_process_client_certificate_verify;
return ssl_hs_ok;
}
if (!tls13_check_message_type(ssl, SSL3_MT_CERTIFICATE) ||
!tls13_process_certificate(ssl) ||
!ssl->method->hash_current_message(ssl)) {
return ssl_hs_error;
}
/* For historical reasons, the server's copy of the chain does not include the
* leaf while the client's does. */
if (sk_X509_num(ssl->s3->new_session->cert_chain) > 0) {
X509_free(sk_X509_shift(ssl->s3->new_session->cert_chain));
}
hs->state = state_process_client_certificate_verify;
return ssl_hs_read_message;
}
static enum ssl_hs_wait_t do_process_client_certificate_verify(
SSL *ssl, SSL_HANDSHAKE *hs) {
if (ssl->s3->new_session->peer == NULL) {
/* Skip this state. */
hs->state = state_process_client_finished;
return ssl_hs_ok;
}
if (!tls13_check_message_type(ssl, SSL3_MT_CERTIFICATE_VERIFY) ||
!tls13_process_certificate_verify(ssl) ||
!ssl->method->hash_current_message(ssl)) {
return 0;
}
hs->state = state_process_client_finished;
return ssl_hs_read_message;
}
static enum ssl_hs_wait_t do_process_client_finished(SSL *ssl,
SSL_HANDSHAKE *hs) {
if (!tls13_check_message_type(ssl, SSL3_MT_FINISHED) ||
!tls13_process_finished(ssl) ||
!ssl->method->hash_current_message(ssl) ||
/* evp_aead_seal keys have already been switched. */
!tls13_set_traffic_key(ssl, type_data, evp_aead_open,
hs->traffic_secret_0, hs->hash_len) ||
!tls13_finalize_keys(ssl)) {
return ssl_hs_error;
}
ssl->method->received_flight(ssl);
hs->state = state_send_new_session_ticket;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_new_session_ticket(SSL *ssl,
SSL_HANDSHAKE *hs) {
SSL_SESSION *session = ssl->s3->new_session;
session->ticket_lifetime_hint = session->timeout;
session->ticket_flags = SSL_TICKET_ALLOW_DHE_RESUMPTION;
if (!RAND_bytes((uint8_t *)&session->ticket_age_add,
sizeof(session->ticket_age_add))) {
return 0;
}
session->ticket_age_add_valid = 1;
CBB cbb, body, ticket;
if (!ssl->method->init_message(ssl, &cbb, &body,
SSL3_MT_NEW_SESSION_TICKET) ||
!CBB_add_u32(&body, session->ticket_lifetime_hint) ||
!CBB_add_u32(&body, session->ticket_flags) ||
!CBB_add_u32(&body, session->ticket_age_add) ||
!CBB_add_u16(&body, 0 /* no ticket extensions */) ||
!CBB_add_u16_length_prefixed(&body, &ticket) ||
!ssl_encrypt_ticket(ssl, &ticket, session) ||
!ssl->method->finish_message(ssl, &cbb)) {
CBB_cleanup(&cbb);
return ssl_hs_error;
}
hs->session_tickets_sent++;
hs->state = state_flush_new_session_ticket;
return ssl_hs_write_message;
}
/* TLS 1.3 recommends single-use tickets, so issue multiple tickets in case the
* client makes several connections before getting a renewal. */
static const int kNumTickets = 2;
static enum ssl_hs_wait_t do_flush_new_session_ticket(SSL *ssl,
SSL_HANDSHAKE *hs) {
if (hs->session_tickets_sent >= kNumTickets) {
hs->state = state_done;
} else {
hs->state = state_send_new_session_ticket;
}
return ssl_hs_flush;
}
enum ssl_hs_wait_t tls13_server_handshake(SSL *ssl) {
SSL_HANDSHAKE *hs = ssl->s3->hs;
while (hs->state != state_done) {
enum ssl_hs_wait_t ret = ssl_hs_error;
enum server_hs_state_t state = hs->state;
switch (state) {
case state_process_client_hello:
ret = do_process_client_hello(ssl, hs);
break;
case state_send_hello_retry_request:
ret = do_send_hello_retry_request(ssl, hs);
break;
case state_flush_hello_retry_request:
ret = do_flush_hello_retry_request(ssl, hs);
break;
case state_process_second_client_hello:
ret = do_process_second_client_hello(ssl, hs);
break;
case state_send_server_hello:
ret = do_send_server_hello(ssl, hs);
break;
case state_send_encrypted_extensions:
ret = do_send_encrypted_extensions(ssl, hs);
break;
case state_send_certificate_request:
ret = do_send_certificate_request(ssl, hs);
break;
case state_send_server_certificate:
ret = do_send_server_certificate(ssl, hs);
break;
case state_send_server_certificate_verify:
ret = do_send_server_certificate_verify(ssl, hs, 1 /* first run */);
break;
case state_complete_server_certificate_verify:
ret = do_send_server_certificate_verify(ssl, hs, 0 /* complete */);
break;
case state_send_server_finished:
ret = do_send_server_finished(ssl, hs);
break;
case state_flush:
ret = do_flush(ssl, hs);
break;
case state_process_client_certificate:
ret = do_process_client_certificate(ssl, hs);
break;
case state_process_client_certificate_verify:
ret = do_process_client_certificate_verify(ssl, hs);
break;
case state_process_client_finished:
ret = do_process_client_finished(ssl, hs);
break;
case state_send_new_session_ticket:
ret = do_send_new_session_ticket(ssl, hs);
break;
case state_flush_new_session_ticket:
ret = do_flush_new_session_ticket(ssl, hs);
break;
case state_done:
ret = ssl_hs_ok;
break;
}
if (ret != ssl_hs_ok) {
return ret;
}
}
return ssl_hs_ok;
}
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