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8f94c31b19
boringssl/ssl/tls13_server.cc
David Benjamin 8f94c31b19 Replace reuse_message with an explicit next_message call. 
This means that ssl_get_message (soon to be replaced with a BIO-less
version) is idempotent which avoids the SSL3_ST_SR_KEY_EXCH_B
contortion. It also eases converting the TLS 1.2 state machine. See
https://docs.google.com/a/google.com/document/d/11n7LHsT3GwE34LAJIe3EFs4165TI4UR_3CqiM9LJVpI/edit?usp=sharing
for details.

Bug: 128
Change-Id: Iddd4f951389e8766da07a9de595b552e75f8acf0
Reviewed-on: https://boringssl-review.googlesource.com/18805
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
2017-08-08 21:08:59 +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. */
/* Per C99, various stdint.h macros are unavailable in C++ unless some macros
* are defined. C++11 overruled this decision, but older Android NDKs still
* require it. */
#if !defined(__STDC_LIMIT_MACROS)
#define __STDC_LIMIT_MACROS
#endif
#include <openssl/ssl.h>
#include <assert.h>
#include <string.h>
#include <openssl/aead.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 "../crypto/internal.h"
#include "internal.h"
namespace bssl {
enum server_hs_state_t {
state_select_parameters = 0,
state_select_session,
state_send_hello_retry_request,
state_process_second_client_hello,
state_send_server_hello,
state_send_server_certificate_verify,
state_send_server_finished,
state_read_second_client_flight,
state_process_change_cipher_spec,
state_process_end_of_early_data,
state_process_client_certificate,
state_process_client_certificate_verify,
state_process_channel_id,
state_process_client_finished,
state_send_new_session_ticket,
state_done,
};
static const uint8_t kZeroes[EVP_MAX_MD_SIZE] = {0};
static int resolve_ecdhe_secret(SSL_HANDSHAKE *hs, int *out_need_retry,
SSL_CLIENT_HELLO *client_hello) {
SSL *const ssl = hs->ssl;
*out_need_retry = 0;
/* We only support connections that include an ECDHE key exchange. */
CBS key_share;
if (!ssl_client_hello_get_extension(client_hello, &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 0;
}
int found_key_share;
uint8_t *dhe_secret;
size_t dhe_secret_len;
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!ssl_ext_key_share_parse_clienthello(hs, &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(hs, dhe_secret, dhe_secret_len);
OPENSSL_free(dhe_secret);
return ok;
}
static int ssl_ext_supported_versions_add_serverhello(SSL_HANDSHAKE *hs,
CBB *out) {
CBB contents;
if (!CBB_add_u16(out, TLSEXT_TYPE_supported_versions) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16(&contents, hs->ssl->version) ||
!CBB_flush(out)) {
return 0;
}
return 1;
}
static const SSL_CIPHER *choose_tls13_cipher(
const SSL *ssl, const SSL_CLIENT_HELLO *client_hello) {
if (client_hello->cipher_suites_len % 2 != 0) {
return NULL;
}
CBS cipher_suites;
CBS_init(&cipher_suites, client_hello->cipher_suites,
client_hello->cipher_suites_len);
const int aes_is_fine = EVP_has_aes_hardware();
const uint16_t version = ssl3_protocol_version(ssl);
const SSL_CIPHER *best = NULL;
while (CBS_len(&cipher_suites) > 0) {
uint16_t cipher_suite;
if (!CBS_get_u16(&cipher_suites, &cipher_suite)) {
return NULL;
}
/* Limit to TLS 1.3 ciphers we know about. */
const SSL_CIPHER *candidate = SSL_get_cipher_by_value(cipher_suite);
if (candidate == NULL ||
SSL_CIPHER_get_min_version(candidate) > version ||
SSL_CIPHER_get_max_version(candidate) < version) {
continue;
}
/* TLS 1.3 removes legacy ciphers, so honor the client order, but prefer
* ChaCha20 if we do not have AES hardware. */
if (aes_is_fine) {
return candidate;
}
if (candidate->algorithm_enc == SSL_CHACHA20POLY1305) {
return candidate;
}
if (best == NULL) {
best = candidate;
}
}
return best;
}
static int add_new_session_tickets(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
/* 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;
/* Rebase the session timestamp so that it is measured from ticket
* issuance. */
ssl_session_rebase_time(ssl, hs->new_session.get());
for (int i = 0; i < kNumTickets; i++) {
if (!RAND_bytes((uint8_t *)&hs->new_session->ticket_age_add, 4)) {
return 0;
}
hs->new_session->ticket_age_add_valid = 1;
ScopedCBB cbb;
CBB body, ticket, extensions;
if (!ssl->method->init_message(ssl, cbb.get(), &body,
SSL3_MT_NEW_SESSION_TICKET) ||
!CBB_add_u32(&body, hs->new_session->timeout) ||
!CBB_add_u32(&body, hs->new_session->ticket_age_add) ||
!CBB_add_u16_length_prefixed(&body, &ticket) ||
!ssl_encrypt_ticket(ssl, &ticket, hs->new_session.get()) ||
!CBB_add_u16_length_prefixed(&body, &extensions)) {
return 0;
}
if (ssl->cert->enable_early_data) {
hs->new_session->ticket_max_early_data = kMaxEarlyDataAccepted;
CBB early_data_info;
if (!CBB_add_u16(&extensions, TLSEXT_TYPE_ticket_early_data_info) ||
!CBB_add_u16_length_prefixed(&extensions, &early_data_info) ||
!CBB_add_u32(&early_data_info,
hs->new_session->ticket_max_early_data) ||
!CBB_flush(&extensions)) {
return 0;
}
}
/* Add a fake extension. See draft-davidben-tls-grease-01. */
if (!CBB_add_u16(&extensions,
ssl_get_grease_value(ssl, ssl_grease_ticket_extension)) ||
!CBB_add_u16(&extensions, 0 /* empty */)) {
return 0;
}
if (!ssl_add_message_cbb(ssl, cbb.get())) {
return 0;
}
}
return 1;
}
static enum ssl_hs_wait_t do_select_parameters(SSL_HANDSHAKE *hs) {
/* At this point, most ClientHello extensions have already been processed by
* the common handshake logic. Resolve the remaining non-PSK parameters. */
SSL *const ssl = hs->ssl;
SSL_CLIENT_HELLO client_hello;
if (!ssl_client_hello_init(ssl, &client_hello, ssl->init_msg,
ssl->init_num) ||
client_hello.session_id_len > sizeof(hs->session_id)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_CLIENTHELLO_PARSE_FAILED);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
OPENSSL_memcpy(hs->session_id, client_hello.session_id,
client_hello.session_id_len);
hs->session_id_len = client_hello.session_id_len;
/* Negotiate the cipher suite. */
hs->new_cipher = choose_tls13_cipher(ssl, &client_hello);
if (hs->new_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;
}
/* HTTP/2 negotiation depends on the cipher suite, so ALPN negotiation was
* deferred. Complete it now. */
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!ssl_negotiate_alpn(hs, &alert, &client_hello)) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
/* The PRF hash is now known. Set up the key schedule and hash the
* ClientHello. */
if (!tls13_init_key_schedule(hs) ||
!ssl_hash_current_message(hs)) {
return ssl_hs_error;
}
hs->tls13_state = state_select_session;
return ssl_hs_ok;
}
static enum ssl_ticket_aead_result_t select_session(
SSL_HANDSHAKE *hs, uint8_t *out_alert, UniquePtr<SSL_SESSION> *out_session,
int32_t *out_ticket_age_skew, const SSL_CLIENT_HELLO *client_hello) {
SSL *const ssl = hs->ssl;
*out_session = NULL;
/* Decode the ticket if we agreed on a PSK key exchange mode. */
CBS pre_shared_key;
if (!hs->accept_psk_mode ||
!ssl_client_hello_get_extension(client_hello, &pre_shared_key,
TLSEXT_TYPE_pre_shared_key)) {
return ssl_ticket_aead_ignore_ticket;
}
/* Verify that the pre_shared_key extension is the last extension in
* ClientHello. */
if (CBS_data(&pre_shared_key) + CBS_len(&pre_shared_key) !=
client_hello->extensions + client_hello->extensions_len) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PRE_SHARED_KEY_MUST_BE_LAST);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return ssl_ticket_aead_error;
}
CBS ticket, binders;
uint32_t client_ticket_age;
if (!ssl_ext_pre_shared_key_parse_clienthello(hs, &ticket, &binders,
&client_ticket_age, out_alert,
&pre_shared_key)) {
return ssl_ticket_aead_error;
}
/* TLS 1.3 session tickets are renewed separately as part of the
* NewSessionTicket. */
int unused_renew;
UniquePtr<SSL_SESSION> session;
enum ssl_ticket_aead_result_t ret =
ssl_process_ticket(ssl, &session, &unused_renew, CBS_data(&ticket),
CBS_len(&ticket), NULL, 0);
switch (ret) {
case ssl_ticket_aead_success:
break;
case ssl_ticket_aead_error:
*out_alert = SSL_AD_INTERNAL_ERROR;
return ret;
default:
return ret;
}
if (!ssl_session_is_resumable(hs, session.get()) ||
/* Historically, some TLS 1.3 tickets were missing ticket_age_add. */
!session->ticket_age_add_valid) {
return ssl_ticket_aead_ignore_ticket;
}
/* Recover the client ticket age and convert to seconds. */
client_ticket_age -= session->ticket_age_add;
client_ticket_age /= 1000;
struct OPENSSL_timeval now;
ssl_get_current_time(ssl, &now);
/* Compute the server ticket age in seconds. */
assert(now.tv_sec >= session->time);
uint64_t server_ticket_age = now.tv_sec - session->time;
/* To avoid overflowing |hs->ticket_age_skew|, we will not resume
* 68-year-old sessions. */
if (server_ticket_age > INT32_MAX) {
return ssl_ticket_aead_ignore_ticket;
}
/* TODO(davidben,svaldez): Measure this value to decide on tolerance. For
* now, accept all values. https://crbug.com/boringssl/113. */
*out_ticket_age_skew =
(int32_t)client_ticket_age - (int32_t)server_ticket_age;
/* Check the PSK binder. */
if (!tls13_verify_psk_binder(hs, session.get(), &binders)) {
*out_alert = SSL_AD_DECRYPT_ERROR;
return ssl_ticket_aead_error;
}
*out_session = std::move(session);
return ssl_ticket_aead_success;
}
static enum ssl_hs_wait_t do_select_session(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
SSL_CLIENT_HELLO client_hello;
if (!ssl_client_hello_init(ssl, &client_hello, 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;
}
uint8_t alert = SSL_AD_DECODE_ERROR;
UniquePtr<SSL_SESSION> session;
switch (select_session(hs, &alert, &session, &ssl->s3->ticket_age_skew,
&client_hello)) {
case ssl_ticket_aead_ignore_ticket:
assert(!session);
if (!ssl_get_new_session(hs, 1 /* server */)) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
break;
case ssl_ticket_aead_success:
/* Carry over authentication information from the previous handshake into
* a fresh session. */
hs->new_session =
SSL_SESSION_dup(session.get(), SSL_SESSION_DUP_AUTH_ONLY);
if (/* Early data must be acceptable for this ticket. */
ssl->cert->enable_early_data &&
session->ticket_max_early_data != 0 &&
/* The client must have offered early data. */
hs->early_data_offered &&
/* Channel ID is incompatible with 0-RTT. */
!ssl->s3->tlsext_channel_id_valid &&
/* The negotiated ALPN must match the one in the ticket. */
ssl->s3->alpn_selected_len == session->early_alpn_len &&
OPENSSL_memcmp(ssl->s3->alpn_selected, session->early_alpn,
ssl->s3->alpn_selected_len) == 0) {
ssl->early_data_accepted = 1;
}
if (hs->new_session == NULL) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
ssl->s3->session_reused = 1;
/* Resumption incorporates fresh key material, so refresh the timeout. */
ssl_session_renew_timeout(ssl, hs->new_session.get(),
ssl->session_ctx->session_psk_dhe_timeout);
break;
case ssl_ticket_aead_error:
ssl3_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
case ssl_ticket_aead_retry:
hs->tls13_state = state_select_session;
return ssl_hs_pending_ticket;
}
/* Record connection properties in the new session. */
hs->new_session->cipher = hs->new_cipher;
if (hs->hostname != NULL) {
OPENSSL_free(hs->new_session->tlsext_hostname);
hs->new_session->tlsext_hostname = BUF_strdup(hs->hostname.get());
if (hs->new_session->tlsext_hostname == NULL) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
}
/* Store the initial negotiated ALPN in the session. */
if (ssl->s3->alpn_selected != NULL) {
hs->new_session->early_alpn = (uint8_t *)BUF_memdup(
ssl->s3->alpn_selected, ssl->s3->alpn_selected_len);
if (hs->new_session->early_alpn == NULL) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
hs->new_session->early_alpn_len = ssl->s3->alpn_selected_len;
}
if (ssl->ctx->dos_protection_cb != NULL &&
ssl->ctx->dos_protection_cb(&client_hello) == 0) {
/* Connection rejected for DOS reasons. */
OPENSSL_PUT_ERROR(SSL, SSL_R_CONNECTION_REJECTED);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
/* Incorporate the PSK into the running secret. */
if (ssl->s3->session_reused) {
if (!tls13_advance_key_schedule(hs, hs->new_session->master_key,
hs->new_session->master_key_length)) {
return ssl_hs_error;
}
} else if (!tls13_advance_key_schedule(hs, kZeroes, hs->hash_len)) {
return ssl_hs_error;
}
if (ssl->early_data_accepted) {
if (!tls13_derive_early_secrets(hs)) {
return ssl_hs_error;
}
} else if (hs->early_data_offered) {
ssl->s3->skip_early_data = 1;
}
/* Resolve ECDHE and incorporate it into the secret. */
int need_retry;
if (!resolve_ecdhe_secret(hs, &need_retry, &client_hello)) {
if (need_retry) {
ssl->early_data_accepted = 0;
ssl->s3->skip_early_data = 1;
ssl->method->next_message(ssl);
hs->tls13_state = state_send_hello_retry_request;
return ssl_hs_ok;
}
return ssl_hs_error;
}
ssl->method->next_message(ssl);
hs->tls13_state = state_send_server_hello;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_hello_retry_request(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
ScopedCBB cbb;
CBB body, extensions;
uint16_t group_id;
if (!ssl->method->init_message(ssl, cbb.get(), &body,
SSL3_MT_HELLO_RETRY_REQUEST) ||
!CBB_add_u16(&body, ssl->version) ||
!tls1_get_shared_group(hs, &group_id) ||
!CBB_add_u16_length_prefixed(&body, &extensions) ||
!CBB_add_u16(&extensions, TLSEXT_TYPE_key_share) ||
!CBB_add_u16(&extensions, 2 /* length */) ||
!CBB_add_u16(&extensions, group_id) ||
!ssl_add_message_cbb(ssl, cbb.get())) {
return ssl_hs_error;
}
hs->tls13_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_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (!ssl_check_message_type(ssl, SSL3_MT_CLIENT_HELLO)) {
return ssl_hs_error;
}
SSL_CLIENT_HELLO client_hello;
if (!ssl_client_hello_init(ssl, &client_hello, 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(hs, &need_retry, &client_hello)) {
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_hash_current_message(hs)) {
return ssl_hs_error;
}
ssl->method->next_message(ssl);
hs->tls13_state = state_send_server_hello;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_server_hello(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
uint16_t version = ssl->version;
if (ssl->version == TLS1_3_EXPERIMENT_VERSION) {
version = TLS1_2_VERSION;
}
/* Send a ServerHello. */
ScopedCBB cbb;
CBB body, extensions, session_id;
if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_SERVER_HELLO) ||
!CBB_add_u16(&body, version) ||
!RAND_bytes(ssl->s3->server_random, sizeof(ssl->s3->server_random)) ||
!CBB_add_bytes(&body, ssl->s3->server_random, SSL3_RANDOM_SIZE) ||
(ssl->version == TLS1_3_EXPERIMENT_VERSION &&
(!CBB_add_u8_length_prefixed(&body, &session_id) ||
!CBB_add_bytes(&session_id, hs->session_id, hs->session_id_len))) ||
!CBB_add_u16(&body, ssl_cipher_get_value(hs->new_cipher)) ||
(ssl->version == TLS1_3_EXPERIMENT_VERSION && !CBB_add_u8(&body, 0)) ||
!CBB_add_u16_length_prefixed(&body, &extensions) ||
!ssl_ext_pre_shared_key_add_serverhello(hs, &extensions) ||
!ssl_ext_key_share_add_serverhello(hs, &extensions) ||
(ssl->version == TLS1_3_EXPERIMENT_VERSION &&
!ssl_ext_supported_versions_add_serverhello(hs, &extensions)) ||
!ssl_add_message_cbb(ssl, cbb.get())) {
return ssl_hs_error;
}
if (ssl->version == TLS1_3_EXPERIMENT_VERSION &&
!ssl3_add_change_cipher_spec(ssl)) {
return ssl_hs_error;
}
/* Derive and enable the handshake traffic secrets. */
if (!tls13_derive_handshake_secrets(hs) ||
!tls13_set_traffic_key(ssl, evp_aead_seal, hs->server_handshake_secret,
hs->hash_len)) {
return ssl_hs_error;
}
/* Send EncryptedExtensions. */
if (!ssl->method->init_message(ssl, cbb.get(), &body,
SSL3_MT_ENCRYPTED_EXTENSIONS) ||
!ssl_add_serverhello_tlsext(hs, &body) ||
!ssl_add_message_cbb(ssl, cbb.get())) {
return ssl_hs_error;
}
if (!ssl->s3->session_reused) {
/* Determine whether to request a client certificate. */
hs->cert_request = !!(ssl->verify_mode & SSL_VERIFY_PEER);
/* Only request a certificate if Channel ID isn't negotiated. */
if ((ssl->verify_mode & SSL_VERIFY_PEER_IF_NO_OBC) &&
ssl->s3->tlsext_channel_id_valid) {
hs->cert_request = 0;
}
}
/* Send a CertificateRequest, if necessary. */
if (hs->cert_request) {
CBB sigalgs_cbb;
if (!ssl->method->init_message(ssl, cbb.get(), &body,
SSL3_MT_CERTIFICATE_REQUEST) ||
!CBB_add_u8(&body, 0 /* no certificate_request_context. */) ||
!CBB_add_u16_length_prefixed(&body, &sigalgs_cbb) ||
!tls12_add_verify_sigalgs(ssl, &sigalgs_cbb) ||
!ssl_add_client_CA_list(ssl, &body) ||
!CBB_add_u16(&body, 0 /* empty certificate_extensions. */) ||
!ssl_add_message_cbb(ssl, cbb.get())) {
return ssl_hs_error;
}
}
/* Send the server Certificate message, if necessary. */
if (!ssl->s3->session_reused) {
if (!ssl_has_certificate(ssl)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_CERTIFICATE_SET);
return ssl_hs_error;
}
if (!tls13_add_certificate(hs)) {
return ssl_hs_error;
}
hs->tls13_state = state_send_server_certificate_verify;
return ssl_hs_ok;
}
hs->tls13_state = state_send_server_finished;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_server_certificate_verify(SSL_HANDSHAKE *hs) {
switch (tls13_add_certificate_verify(hs)) {
case ssl_private_key_success:
hs->tls13_state = state_send_server_finished;
return ssl_hs_ok;
case ssl_private_key_retry:
hs->tls13_state = state_send_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_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (!tls13_add_finished(hs) ||
/* Update the secret to the master secret and derive traffic keys. */
!tls13_advance_key_schedule(hs, kZeroes, hs->hash_len) ||
!tls13_derive_application_secrets(hs) ||
!tls13_set_traffic_key(ssl, evp_aead_seal, hs->server_traffic_secret_0,
hs->hash_len)) {
return ssl_hs_error;
}
if (ssl->early_data_accepted) {
/* If accepting 0-RTT, we send tickets half-RTT. This gets the tickets on
* the wire sooner and also avoids triggering a write on |SSL_read| when
* processing the client Finished. This requires computing the client
* Finished early. See draft-ietf-tls-tls13-18, section 4.5.1. */
size_t finished_len;
if (!tls13_finished_mac(hs, hs->expected_client_finished, &finished_len,
0 /* client */)) {
return ssl_hs_error;
}
if (finished_len != hs->hash_len) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return ssl_hs_error;
}
/* Feed the predicted Finished into the transcript. This allows us to derive
* the resumption secret early and send half-RTT tickets.
*
* TODO(davidben): This will need to be updated for DTLS 1.3. */
assert(!SSL_is_dtls(hs->ssl));
assert(hs->hash_len <= 0xff);
uint8_t header[4] = {SSL3_MT_FINISHED, 0, 0,
static_cast<uint8_t>(hs->hash_len)};
if (!hs->transcript.Update(header, sizeof(header)) ||
!hs->transcript.Update(hs->expected_client_finished, hs->hash_len) ||
!tls13_derive_resumption_secret(hs) ||
!add_new_session_tickets(hs)) {
return ssl_hs_error;
}
}
hs->tls13_state = state_read_second_client_flight;
return ssl_hs_flush;
}
static enum ssl_hs_wait_t do_read_second_client_flight(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (ssl->early_data_accepted) {
if (!tls13_set_traffic_key(ssl, evp_aead_open, hs->early_traffic_secret,
hs->hash_len)) {
return ssl_hs_error;
}
hs->can_early_write = 1;
hs->can_early_read = 1;
hs->in_early_data = 1;
hs->tls13_state = state_process_end_of_early_data;
return ssl_hs_read_end_of_early_data;
}
hs->tls13_state = state_process_end_of_early_data;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_process_end_of_early_data(SSL_HANDSHAKE *hs) {
hs->tls13_state = state_process_change_cipher_spec;
/* If early data was accepted, the ChangeCipherSpec message will be in the
* discarded early data. */
if (hs->early_data_offered && !hs->ssl->early_data_accepted) {
return ssl_hs_ok;
}
return hs->ssl->version == TLS1_3_EXPERIMENT_VERSION
? ssl_hs_read_change_cipher_spec
: ssl_hs_ok;
}
static enum ssl_hs_wait_t do_process_change_cipher_spec(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (!tls13_set_traffic_key(ssl, evp_aead_open, hs->client_handshake_secret,
hs->hash_len)) {
return ssl_hs_error;
}
hs->tls13_state = ssl->early_data_accepted ? state_process_client_finished
: state_process_client_certificate;
return ssl_hs_read_message;
}
static enum ssl_hs_wait_t do_process_client_certificate(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (!hs->cert_request) {
/* 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;
/* Skip this state. */
hs->tls13_state = state_process_channel_id;
return ssl_hs_ok;
}
const int allow_anonymous =
(ssl->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT) == 0;
if (!ssl_check_message_type(ssl, SSL3_MT_CERTIFICATE) ||
!tls13_process_certificate(hs, allow_anonymous) ||
!ssl_hash_current_message(hs)) {
return ssl_hs_error;
}
ssl->method->next_message(ssl);
hs->tls13_state = state_process_client_certificate_verify;
return ssl_hs_read_message;
}
static enum ssl_hs_wait_t do_process_client_certificate_verify(
SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (sk_CRYPTO_BUFFER_num(hs->new_session->certs) == 0) {
/* Skip this state. */
hs->tls13_state = state_process_channel_id;
return ssl_hs_ok;
}
switch (ssl_verify_peer_cert(hs)) {
case ssl_verify_ok:
break;
case ssl_verify_invalid:
return ssl_hs_error;
case ssl_verify_retry:
hs->tls13_state = state_process_client_certificate_verify;
return ssl_hs_certificate_verify;
}
if (!ssl_check_message_type(ssl, SSL3_MT_CERTIFICATE_VERIFY) ||
!tls13_process_certificate_verify(hs) ||
!ssl_hash_current_message(hs)) {
return ssl_hs_error;
}
ssl->method->next_message(ssl);
hs->tls13_state = state_process_channel_id;
return ssl_hs_read_message;
}
static enum ssl_hs_wait_t do_process_channel_id(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (!ssl->s3->tlsext_channel_id_valid) {
hs->tls13_state = state_process_client_finished;
return ssl_hs_ok;
}
if (!ssl_check_message_type(ssl, SSL3_MT_CHANNEL_ID) ||
!tls1_verify_channel_id(hs) ||
!ssl_hash_current_message(hs)) {
return ssl_hs_error;
}
ssl->method->next_message(ssl);
hs->tls13_state = state_process_client_finished;
return ssl_hs_read_message;
}
static enum ssl_hs_wait_t do_process_client_finished(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (!ssl_check_message_type(ssl, SSL3_MT_FINISHED) ||
/* If early data was accepted, we've already computed the client Finished
* and derived the resumption secret. */
!tls13_process_finished(hs, ssl->early_data_accepted) ||
/* evp_aead_seal keys have already been switched. */
!tls13_set_traffic_key(ssl, evp_aead_open, hs->client_traffic_secret_0,
hs->hash_len)) {
return ssl_hs_error;
}
if (!ssl->early_data_accepted) {
if (!ssl_hash_current_message(hs) ||
!tls13_derive_resumption_secret(hs)) {
return ssl_hs_error;
}
/* We send post-handshake tickets as part of the handshake in 1-RTT. */
hs->tls13_state = state_send_new_session_ticket;
} else {
/* We already sent half-RTT tickets. */
hs->tls13_state = state_done;
}
ssl->method->next_message(ssl);
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_new_session_ticket(SSL_HANDSHAKE *hs) {
/* If the client doesn't accept resumption with PSK_DHE_KE, don't send a
* session ticket. */
if (!hs->accept_psk_mode) {
hs->tls13_state = state_done;
return ssl_hs_ok;
}
if (!add_new_session_tickets(hs)) {
return ssl_hs_error;
}
hs->tls13_state = state_done;
return ssl_hs_flush;
}
enum ssl_hs_wait_t tls13_server_handshake(SSL_HANDSHAKE *hs) {
while (hs->tls13_state != state_done) {
enum ssl_hs_wait_t ret = ssl_hs_error;
enum server_hs_state_t state =
static_cast<enum server_hs_state_t>(hs->tls13_state);
switch (state) {
case state_select_parameters:
ret = do_select_parameters(hs);
break;
case state_select_session:
ret = do_select_session(hs);
break;
case state_send_hello_retry_request:
ret = do_send_hello_retry_request(hs);
break;
case state_process_second_client_hello:
ret = do_process_second_client_hello(hs);
break;
case state_send_server_hello:
ret = do_send_server_hello(hs);
break;
case state_send_server_certificate_verify:
ret = do_send_server_certificate_verify(hs);
break;
case state_send_server_finished:
ret = do_send_server_finished(hs);
break;
case state_read_second_client_flight:
ret = do_read_second_client_flight(hs);
break;
case state_process_end_of_early_data:
ret = do_process_end_of_early_data(hs);
break;
case state_process_change_cipher_spec:
ret = do_process_change_cipher_spec(hs);
break;
case state_process_client_certificate:
ret = do_process_client_certificate(hs);
break;
case state_process_client_certificate_verify:
ret = do_process_client_certificate_verify(hs);
break;
case state_process_channel_id:
ret = do_process_channel_id(hs);
break;
case state_process_client_finished:
ret = do_process_client_finished(hs);
break;
case state_send_new_session_ticket:
ret = do_send_new_session_ticket(hs);
break;
case state_done:
ret = ssl_hs_ok;
break;
}
if (ret != ssl_hs_ok) {
return ret;
}
}
return ssl_hs_ok;
}
} // namespace bssl
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