diff options
Diffstat (limited to 'thirdparty/mbedtls/library/ssl_tls13_server.c')
| -rw-r--r-- | thirdparty/mbedtls/library/ssl_tls13_server.c | 3599 |
1 files changed, 3599 insertions, 0 deletions
diff --git a/thirdparty/mbedtls/library/ssl_tls13_server.c b/thirdparty/mbedtls/library/ssl_tls13_server.c new file mode 100644 index 0000000000..2760d76a5d --- /dev/null +++ b/thirdparty/mbedtls/library/ssl_tls13_server.c @@ -0,0 +1,3599 @@ +/* + * TLS 1.3 server-side functions + * + * Copyright The Mbed TLS Contributors + * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later + */ + +#include "common.h" + +#if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_PROTO_TLS1_3) + +#include "debug_internal.h" +#include "mbedtls/error.h" +#include "mbedtls/platform.h" +#include "mbedtls/constant_time.h" +#include "mbedtls/oid.h" +#include "mbedtls/psa_util.h" + +#include "ssl_misc.h" +#include "ssl_tls13_keys.h" +#include "ssl_debug_helpers.h" + + +static const mbedtls_ssl_ciphersuite_t *ssl_tls13_validate_peer_ciphersuite( + mbedtls_ssl_context *ssl, + unsigned int cipher_suite) +{ + const mbedtls_ssl_ciphersuite_t *ciphersuite_info; + if (!mbedtls_ssl_tls13_cipher_suite_is_offered(ssl, cipher_suite)) { + return NULL; + } + + ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(cipher_suite); + if ((mbedtls_ssl_validate_ciphersuite(ssl, ciphersuite_info, + ssl->tls_version, + ssl->tls_version) != 0)) { + return NULL; + } + return ciphersuite_info; +} + +static void ssl_tls13_select_ciphersuite( + mbedtls_ssl_context *ssl, + const unsigned char *cipher_suites, + const unsigned char *cipher_suites_end, + int psk_ciphersuite_id, + psa_algorithm_t psk_hash_alg, + const mbedtls_ssl_ciphersuite_t **selected_ciphersuite_info) +{ + *selected_ciphersuite_info = NULL; + + /* + * In a compliant ClientHello the byte-length of the list of ciphersuites + * is even and this function relies on this fact. This should have been + * checked in the main ClientHello parsing function. Double check here. + */ + if ((cipher_suites_end - cipher_suites) & 1) { + return; + } + + for (const unsigned char *p = cipher_suites; + p < cipher_suites_end; p += 2) { + /* + * "cipher_suites_end - p is even" is an invariant of the loop. As + * cipher_suites_end - p > 0, we have cipher_suites_end - p >= 2 and it + * is thus safe to read two bytes. + */ + uint16_t id = MBEDTLS_GET_UINT16_BE(p, 0); + + const mbedtls_ssl_ciphersuite_t *info = + ssl_tls13_validate_peer_ciphersuite(ssl, id); + if (info == NULL) { + continue; + } + + /* + * If a valid PSK ciphersuite identifier has been passed in, we want + * an exact match. + */ + if (psk_ciphersuite_id != 0) { + if (id != psk_ciphersuite_id) { + continue; + } + } else if (psk_hash_alg != PSA_ALG_NONE) { + if (mbedtls_md_psa_alg_from_type((mbedtls_md_type_t) info->mac) != + psk_hash_alg) { + continue; + } + } + + *selected_ciphersuite_info = info; + return; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("No matched ciphersuite, psk_ciphersuite_id=%x, psk_hash_alg=%x", + (unsigned) psk_ciphersuite_id, psk_hash_alg)); +} + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) +/* From RFC 8446: + * + * enum { psk_ke(0), psk_dhe_ke(1), (255) } PskKeyExchangeMode; + * struct { + * PskKeyExchangeMode ke_modes<1..255>; + * } PskKeyExchangeModes; + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_parse_key_exchange_modes_ext(mbedtls_ssl_context *ssl, + const unsigned char *buf, + const unsigned char *end) +{ + const unsigned char *p = buf; + size_t ke_modes_len; + int ke_modes = 0; + + /* Read ke_modes length (1 Byte) */ + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 1); + ke_modes_len = *p++; + /* Currently, there are only two PSK modes, so even without looking + * at the content, something's wrong if the list has more than 2 items. */ + if (ke_modes_len > 2) { + MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, + MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); + return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; + } + + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, ke_modes_len); + + while (ke_modes_len-- != 0) { + switch (*p++) { + case MBEDTLS_SSL_TLS1_3_PSK_MODE_PURE: + ke_modes |= MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK; + MBEDTLS_SSL_DEBUG_MSG(3, ("Found PSK KEX MODE")); + break; + case MBEDTLS_SSL_TLS1_3_PSK_MODE_ECDHE: + ke_modes |= MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL; + MBEDTLS_SSL_DEBUG_MSG(3, ("Found PSK_EPHEMERAL KEX MODE")); + break; + default: + MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, + MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); + return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; + } + } + + ssl->handshake->tls13_kex_modes = ke_modes; + return 0; +} + +/* + * Non-error return values of + * ssl_tls13_offered_psks_check_identity_match_ticket() and + * ssl_tls13_offered_psks_check_identity_match(). They are positive to + * not collide with error codes that are negative. Zero + * (SSL_TLS1_3_PSK_IDENTITY_MATCH) in case of success as it may be propagated + * up by the callers of this function as a generic success condition. + * + * The return value SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE means + * that the pre-shared-key identity matches that of a ticket or an externally- + * provisioned pre-shared-key. We have thus been able to retrieve the + * attributes of the pre-shared-key but at least one of them does not meet + * some criteria and the pre-shared-key cannot be used. For example, a ticket + * is expired or its version is not TLS 1.3. Note eventually that the return + * value SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE does not have + * anything to do with binder check. A binder check is done only when a + * suitable pre-shared-key has been selected and only for that selected + * pre-shared-key: if the binder check fails, we fail the handshake and we do + * not try to find another pre-shared-key for which the binder check would + * succeed as recommended by the specification. + */ +#define SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH 2 +#define SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE 1 +#define SSL_TLS1_3_PSK_IDENTITY_MATCH 0 + +#if defined(MBEDTLS_SSL_SESSION_TICKETS) +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_key_exchange_is_psk_available(mbedtls_ssl_context *ssl); +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_key_exchange_is_psk_ephemeral_available(mbedtls_ssl_context *ssl); + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_offered_psks_check_identity_match_ticket( + mbedtls_ssl_context *ssl, + const unsigned char *identity, + size_t identity_len, + uint32_t obfuscated_ticket_age, + mbedtls_ssl_session *session) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char *ticket_buffer; +#if defined(MBEDTLS_HAVE_TIME) + mbedtls_ms_time_t now; + mbedtls_ms_time_t server_age; + uint32_t client_age; + mbedtls_ms_time_t age_diff; +#endif + + ((void) obfuscated_ticket_age); + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> check_identity_match_ticket")); + + /* Ticket parser is not configured, Skip */ + if (ssl->conf->f_ticket_parse == NULL || identity_len == 0) { + return SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH; + } + + /* We create a copy of the encrypted ticket since the ticket parsing + * function is allowed to use its input buffer as an output buffer + * (in-place decryption). We do, however, need the original buffer for + * computing the PSK binder value. + */ + ticket_buffer = mbedtls_calloc(1, identity_len); + if (ticket_buffer == NULL) { + return MBEDTLS_ERR_SSL_ALLOC_FAILED; + } + memcpy(ticket_buffer, identity, identity_len); + + ret = ssl->conf->f_ticket_parse(ssl->conf->p_ticket, + session, + ticket_buffer, identity_len); + switch (ret) { + case 0: + ret = SSL_TLS1_3_PSK_IDENTITY_MATCH; + break; + + case MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED: + MBEDTLS_SSL_DEBUG_MSG(3, ("ticket is expired")); + ret = SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE; + break; + + case MBEDTLS_ERR_SSL_INVALID_MAC: + MBEDTLS_SSL_DEBUG_MSG(3, ("ticket is not authentic")); + ret = SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH; + break; + + default: + MBEDTLS_SSL_DEBUG_RET(1, "ticket_parse", ret); + ret = SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH; + } + + /* We delete the temporary buffer */ + mbedtls_free(ticket_buffer); + + if (ret != SSL_TLS1_3_PSK_IDENTITY_MATCH) { + goto exit; + } + + /* + * The identity matches that of a ticket. Now check that it has suitable + * attributes and bet it will not be the case. + */ + ret = SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE; + + if (session->tls_version != MBEDTLS_SSL_VERSION_TLS1_3) { + MBEDTLS_SSL_DEBUG_MSG(3, ("Ticket TLS version is not 1.3.")); + goto exit; + } + +#if defined(MBEDTLS_HAVE_TIME) + now = mbedtls_ms_time(); + + if (now < session->ticket_creation_time) { + MBEDTLS_SSL_DEBUG_MSG( + 3, ("Invalid ticket creation time ( now = %" MBEDTLS_PRINTF_MS_TIME + ", creation_time = %" MBEDTLS_PRINTF_MS_TIME " )", + now, session->ticket_creation_time)); + goto exit; + } + + server_age = now - session->ticket_creation_time; + + /* RFC 8446 section 4.6.1 + * + * Servers MUST NOT use any value greater than 604800 seconds (7 days). + * + * RFC 8446 section 4.2.11.1 + * + * Clients MUST NOT attempt to use tickets which have ages greater than + * the "ticket_lifetime" value which was provided with the ticket. + * + */ + if (server_age > MBEDTLS_SSL_TLS1_3_MAX_ALLOWED_TICKET_LIFETIME * 1000) { + MBEDTLS_SSL_DEBUG_MSG( + 3, ("Ticket age exceeds limitation ticket_age = %" MBEDTLS_PRINTF_MS_TIME, + server_age)); + goto exit; + } + + /* RFC 8446 section 4.2.10 + * + * For PSKs provisioned via NewSessionTicket, a server MUST validate that + * the ticket age for the selected PSK identity (computed by subtracting + * ticket_age_add from PskIdentity.obfuscated_ticket_age modulo 2^32) is + * within a small tolerance of the time since the ticket was issued. + * + * NOTE: The typical accuracy of an RTC crystal is ±100 to ±20 parts per + * million (360 to 72 milliseconds per hour). Default tolerance + * window is 6s, thus in the worst case clients and servers must + * sync up their system time every 6000/360/2~=8 hours. + */ + client_age = obfuscated_ticket_age - session->ticket_age_add; + age_diff = server_age - (mbedtls_ms_time_t) client_age; + if (age_diff < -MBEDTLS_SSL_TLS1_3_TICKET_AGE_TOLERANCE || + age_diff > MBEDTLS_SSL_TLS1_3_TICKET_AGE_TOLERANCE) { + MBEDTLS_SSL_DEBUG_MSG( + 3, ("Ticket age outside tolerance window ( diff = %" + MBEDTLS_PRINTF_MS_TIME ")", + age_diff)); + goto exit; + } +#endif /* MBEDTLS_HAVE_TIME */ + + /* + * All good, we have found a suitable ticket. + */ + ret = SSL_TLS1_3_PSK_IDENTITY_MATCH; + +exit: + if (ret != SSL_TLS1_3_PSK_IDENTITY_MATCH) { + mbedtls_ssl_session_free(session); + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= check_identity_match_ticket")); + return ret; +} +#endif /* MBEDTLS_SSL_SESSION_TICKETS */ + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_offered_psks_check_identity_match( + mbedtls_ssl_context *ssl, + const unsigned char *identity, + size_t identity_len, + uint32_t obfuscated_ticket_age, + int *psk_type, + mbedtls_ssl_session *session) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + ((void) session); + ((void) obfuscated_ticket_age); + *psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL; + + MBEDTLS_SSL_DEBUG_BUF(4, "identity", identity, identity_len); + +#if defined(MBEDTLS_SSL_SESSION_TICKETS) + ret = ssl_tls13_offered_psks_check_identity_match_ticket( + ssl, identity, identity_len, obfuscated_ticket_age, session); + if (ret == SSL_TLS1_3_PSK_IDENTITY_MATCH) { + *psk_type = MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION; + ret = mbedtls_ssl_set_hs_psk(ssl, + session->resumption_key, + session->resumption_key_len); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_set_hs_psk", ret); + return ret; + } + + MBEDTLS_SSL_DEBUG_BUF(4, "Ticket-resumed PSK:", + session->resumption_key, + session->resumption_key_len); + MBEDTLS_SSL_DEBUG_MSG(4, ("ticket: obfuscated_ticket_age: %u", + (unsigned) obfuscated_ticket_age)); + return SSL_TLS1_3_PSK_IDENTITY_MATCH; + } else if (ret == SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE) { + return SSL_TLS1_3_PSK_IDENTITY_MATCH_BUT_PSK_NOT_USABLE; + } +#endif /* MBEDTLS_SSL_SESSION_TICKETS */ + + /* Check identity with external configured function */ + if (ssl->conf->f_psk != NULL) { + if (ssl->conf->f_psk( + ssl->conf->p_psk, ssl, identity, identity_len) == 0) { + return SSL_TLS1_3_PSK_IDENTITY_MATCH; + } + return SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH; + } + + MBEDTLS_SSL_DEBUG_BUF(5, "identity", identity, identity_len); + /* Check identity with pre-configured psk */ + if (ssl->conf->psk_identity != NULL && + identity_len == ssl->conf->psk_identity_len && + mbedtls_ct_memcmp(ssl->conf->psk_identity, + identity, identity_len) == 0) { + ret = mbedtls_ssl_set_hs_psk(ssl, ssl->conf->psk, ssl->conf->psk_len); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_set_hs_psk", ret); + return ret; + } + return SSL_TLS1_3_PSK_IDENTITY_MATCH; + } + + return SSL_TLS1_3_PSK_IDENTITY_DOES_NOT_MATCH; +} + +/* + * Non-error return values of ssl_tls13_offered_psks_check_binder_match(). + * They are positive to not collide with error codes that are negative. Zero + * (SSL_TLS1_3_BINDER_MATCH) in case of success as it may be propagated up + * by the callers of this function as a generic success condition. + */ +#define SSL_TLS1_3_BINDER_DOES_NOT_MATCH 1 +#define SSL_TLS1_3_BINDER_MATCH 0 +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_offered_psks_check_binder_match( + mbedtls_ssl_context *ssl, + const unsigned char *binder, size_t binder_len, + int psk_type, psa_algorithm_t psk_hash_alg) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + unsigned char transcript[PSA_HASH_MAX_SIZE]; + size_t transcript_len; + unsigned char *psk; + size_t psk_len; + unsigned char server_computed_binder[PSA_HASH_MAX_SIZE]; + + if (binder_len != PSA_HASH_LENGTH(psk_hash_alg)) { + return SSL_TLS1_3_BINDER_DOES_NOT_MATCH; + } + + /* Get current state of handshake transcript. */ + ret = mbedtls_ssl_get_handshake_transcript( + ssl, mbedtls_md_type_from_psa_alg(psk_hash_alg), + transcript, sizeof(transcript), &transcript_len); + if (ret != 0) { + return ret; + } + + ret = mbedtls_ssl_tls13_export_handshake_psk(ssl, &psk, &psk_len); + if (ret != 0) { + return ret; + } + + ret = mbedtls_ssl_tls13_create_psk_binder(ssl, psk_hash_alg, + psk, psk_len, psk_type, + transcript, + server_computed_binder); +#if defined(MBEDTLS_USE_PSA_CRYPTO) + mbedtls_free((void *) psk); +#endif + if (ret != 0) { + MBEDTLS_SSL_DEBUG_MSG(1, ("PSK binder calculation failed.")); + return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; + } + + MBEDTLS_SSL_DEBUG_BUF(3, "psk binder ( computed ): ", + server_computed_binder, transcript_len); + MBEDTLS_SSL_DEBUG_BUF(3, "psk binder ( received ): ", binder, binder_len); + + if (mbedtls_ct_memcmp(server_computed_binder, + binder, + PSA_HASH_LENGTH(psk_hash_alg)) == 0) { + return SSL_TLS1_3_BINDER_MATCH; + } + + mbedtls_platform_zeroize(server_computed_binder, + sizeof(server_computed_binder)); + return SSL_TLS1_3_BINDER_DOES_NOT_MATCH; +} + +#if defined(MBEDTLS_SSL_SESSION_TICKETS) +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_session_copy_ticket(mbedtls_ssl_session *dst, + const mbedtls_ssl_session *src) +{ + dst->ticket_age_add = src->ticket_age_add; + dst->ticket_flags = src->ticket_flags; + dst->resumption_key_len = src->resumption_key_len; + if (src->resumption_key_len == 0) { + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + memcpy(dst->resumption_key, src->resumption_key, src->resumption_key_len); + +#if defined(MBEDTLS_SSL_EARLY_DATA) + dst->max_early_data_size = src->max_early_data_size; + +#if defined(MBEDTLS_SSL_ALPN) + int ret = mbedtls_ssl_session_set_ticket_alpn(dst, src->ticket_alpn); + if (ret != 0) { + return ret; + } +#endif /* MBEDTLS_SSL_ALPN */ +#endif /* MBEDTLS_SSL_EARLY_DATA*/ + + return 0; +} +#endif /* MBEDTLS_SSL_SESSION_TICKETS */ + +struct psk_attributes { + int type; + int key_exchange_mode; + const mbedtls_ssl_ciphersuite_t *ciphersuite_info; +}; +#define PSK_ATTRIBUTES_INIT { 0, 0, NULL } + +/* Parser for pre_shared_key extension in client hello + * struct { + * opaque identity<1..2^16-1>; + * uint32 obfuscated_ticket_age; + * } PskIdentity; + * + * opaque PskBinderEntry<32..255>; + * + * struct { + * PskIdentity identities<7..2^16-1>; + * PskBinderEntry binders<33..2^16-1>; + * } OfferedPsks; + * + * struct { + * select (Handshake.msg_type) { + * case client_hello: OfferedPsks; + * .... + * }; + * } PreSharedKeyExtension; + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_parse_pre_shared_key_ext( + mbedtls_ssl_context *ssl, + const unsigned char *pre_shared_key_ext, + const unsigned char *pre_shared_key_ext_end, + const unsigned char *ciphersuites, + const unsigned char *ciphersuites_end, + struct psk_attributes *psk) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + const unsigned char *identities = pre_shared_key_ext; + const unsigned char *p_identity_len; + size_t identities_len; + const unsigned char *identities_end; + const unsigned char *binders; + const unsigned char *p_binder_len; + size_t binders_len; + const unsigned char *binders_end; + int matched_identity = -1; + int identity_id = -1; + + MBEDTLS_SSL_DEBUG_BUF(3, "pre_shared_key extension", + pre_shared_key_ext, + pre_shared_key_ext_end - pre_shared_key_ext); + + /* identities_len 2 bytes + * identities_data >= 7 bytes + */ + MBEDTLS_SSL_CHK_BUF_READ_PTR(identities, pre_shared_key_ext_end, 7 + 2); + identities_len = MBEDTLS_GET_UINT16_BE(identities, 0); + p_identity_len = identities + 2; + MBEDTLS_SSL_CHK_BUF_READ_PTR(p_identity_len, pre_shared_key_ext_end, + identities_len); + identities_end = p_identity_len + identities_len; + + /* binders_len 2 bytes + * binders >= 33 bytes + */ + binders = identities_end; + MBEDTLS_SSL_CHK_BUF_READ_PTR(binders, pre_shared_key_ext_end, 33 + 2); + binders_len = MBEDTLS_GET_UINT16_BE(binders, 0); + p_binder_len = binders + 2; + MBEDTLS_SSL_CHK_BUF_READ_PTR(p_binder_len, pre_shared_key_ext_end, binders_len); + binders_end = p_binder_len + binders_len; + + ret = ssl->handshake->update_checksum(ssl, pre_shared_key_ext, + identities_end - pre_shared_key_ext); + if (0 != ret) { + MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret); + return ret; + } + + while (p_identity_len < identities_end && p_binder_len < binders_end) { + const unsigned char *identity; + size_t identity_len; + uint32_t obfuscated_ticket_age; + const unsigned char *binder; + size_t binder_len; + int psk_ciphersuite_id; + psa_algorithm_t psk_hash_alg; + int allowed_key_exchange_modes; + +#if defined(MBEDTLS_SSL_SESSION_TICKETS) + mbedtls_ssl_session session; + mbedtls_ssl_session_init(&session); +#endif + + MBEDTLS_SSL_CHK_BUF_READ_PTR(p_identity_len, identities_end, 2 + 1 + 4); + identity_len = MBEDTLS_GET_UINT16_BE(p_identity_len, 0); + identity = p_identity_len + 2; + MBEDTLS_SSL_CHK_BUF_READ_PTR(identity, identities_end, identity_len + 4); + obfuscated_ticket_age = MBEDTLS_GET_UINT32_BE(identity, identity_len); + p_identity_len += identity_len + 6; + + MBEDTLS_SSL_CHK_BUF_READ_PTR(p_binder_len, binders_end, 1 + 32); + binder_len = *p_binder_len; + binder = p_binder_len + 1; + MBEDTLS_SSL_CHK_BUF_READ_PTR(binder, binders_end, binder_len); + p_binder_len += binder_len + 1; + + identity_id++; + if (matched_identity != -1) { + continue; + } + + ret = ssl_tls13_offered_psks_check_identity_match( + ssl, identity, identity_len, obfuscated_ticket_age, + &psk->type, &session); + if (ret != SSL_TLS1_3_PSK_IDENTITY_MATCH) { + continue; + } + + MBEDTLS_SSL_DEBUG_MSG(4, ("found matched identity")); + + switch (psk->type) { + case MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL: + psk_ciphersuite_id = 0; + psk_hash_alg = PSA_ALG_SHA_256; + allowed_key_exchange_modes = + MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL; + break; +#if defined(MBEDTLS_SSL_SESSION_TICKETS) + case MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION: + psk_ciphersuite_id = session.ciphersuite; + psk_hash_alg = PSA_ALG_NONE; + ssl->session_negotiate->ticket_flags = session.ticket_flags; + allowed_key_exchange_modes = + session.ticket_flags & + MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL; + break; +#endif + default: + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + psk->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_NONE; + + if ((allowed_key_exchange_modes & + MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL) && + ssl_tls13_key_exchange_is_psk_ephemeral_available(ssl)) { + psk->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL; + } else if ((allowed_key_exchange_modes & + MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK) && + ssl_tls13_key_exchange_is_psk_available(ssl)) { + psk->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK; + } + + if (psk->key_exchange_mode == MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_NONE) { + MBEDTLS_SSL_DEBUG_MSG(3, ("No suitable PSK key exchange mode")); + continue; + } + + ssl_tls13_select_ciphersuite(ssl, ciphersuites, ciphersuites_end, + psk_ciphersuite_id, psk_hash_alg, + &psk->ciphersuite_info); + + if (psk->ciphersuite_info == NULL) { +#if defined(MBEDTLS_SSL_SESSION_TICKETS) + mbedtls_ssl_session_free(&session); +#endif + /* + * We consider finding a ciphersuite suitable for the PSK as part + * of the validation of its binder. Thus if we do not find one, we + * abort the handshake with a decrypt_error alert. + */ + MBEDTLS_SSL_PEND_FATAL_ALERT( + MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR, + MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); + return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; + } + + ret = ssl_tls13_offered_psks_check_binder_match( + ssl, binder, binder_len, psk->type, + mbedtls_md_psa_alg_from_type((mbedtls_md_type_t) psk->ciphersuite_info->mac)); + if (ret != SSL_TLS1_3_BINDER_MATCH) { + /* For security reasons, the handshake should be aborted when we + * fail to validate a binder value. See RFC 8446 section 4.2.11.2 + * and appendix E.6. */ +#if defined(MBEDTLS_SSL_SESSION_TICKETS) + mbedtls_ssl_session_free(&session); +#endif + MBEDTLS_SSL_DEBUG_MSG(3, ("Invalid binder.")); + MBEDTLS_SSL_DEBUG_RET( + 1, "ssl_tls13_offered_psks_check_binder_match", ret); + MBEDTLS_SSL_PEND_FATAL_ALERT( + MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR, + MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); + return ret; + } + + matched_identity = identity_id; + +#if defined(MBEDTLS_SSL_SESSION_TICKETS) + if (psk->type == MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION) { + ret = ssl_tls13_session_copy_ticket(ssl->session_negotiate, + &session); + mbedtls_ssl_session_free(&session); + if (ret != 0) { + return ret; + } + } +#endif /* MBEDTLS_SSL_SESSION_TICKETS */ + } + + if (p_identity_len != identities_end || p_binder_len != binders_end) { + MBEDTLS_SSL_DEBUG_MSG(3, ("pre_shared_key extension decode error")); + MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, + MBEDTLS_ERR_SSL_DECODE_ERROR); + return MBEDTLS_ERR_SSL_DECODE_ERROR; + } + + /* Update the handshake transcript with the binder list. */ + ret = ssl->handshake->update_checksum( + ssl, identities_end, (size_t) (binders_end - identities_end)); + if (0 != ret) { + MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret); + return ret; + } + if (matched_identity == -1) { + MBEDTLS_SSL_DEBUG_MSG(3, ("No usable PSK or ticket.")); + return MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY; + } + + ssl->handshake->selected_identity = (uint16_t) matched_identity; + MBEDTLS_SSL_DEBUG_MSG(3, ("Pre shared key found")); + + return 0; +} + +/* + * struct { + * select ( Handshake.msg_type ) { + * .... + * case server_hello: + * uint16 selected_identity; + * } + * } PreSharedKeyExtension; + */ +static int ssl_tls13_write_server_pre_shared_key_ext(mbedtls_ssl_context *ssl, + unsigned char *buf, + unsigned char *end, + size_t *olen) +{ + unsigned char *p = (unsigned char *) buf; + + *olen = 0; + + int not_using_psk = 0; +#if defined(MBEDTLS_USE_PSA_CRYPTO) + not_using_psk = (mbedtls_svc_key_id_is_null(ssl->handshake->psk_opaque)); +#else + not_using_psk = (ssl->handshake->psk == NULL); +#endif + if (not_using_psk) { + /* We shouldn't have called this extension writer unless we've + * chosen to use a PSK. */ + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + MBEDTLS_SSL_DEBUG_MSG(3, ("server hello, adding pre_shared_key extension")); + MBEDTLS_SSL_CHK_BUF_PTR(p, end, 6); + + MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_PRE_SHARED_KEY, p, 0); + MBEDTLS_PUT_UINT16_BE(2, p, 2); + + MBEDTLS_PUT_UINT16_BE(ssl->handshake->selected_identity, p, 4); + + *olen = 6; + + MBEDTLS_SSL_DEBUG_MSG(4, ("sent selected_identity: %u", + ssl->handshake->selected_identity)); + + mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_PRE_SHARED_KEY); + + return 0; +} + +#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ + +/* From RFC 8446: + * struct { + * ProtocolVersion versions<2..254>; + * } SupportedVersions; + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_parse_supported_versions_ext(mbedtls_ssl_context *ssl, + const unsigned char *buf, + const unsigned char *end) +{ + const unsigned char *p = buf; + size_t versions_len; + const unsigned char *versions_end; + uint16_t tls_version; + int found_supported_version = 0; + + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 1); + versions_len = p[0]; + p += 1; + + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, versions_len); + versions_end = p + versions_len; + while (p < versions_end) { + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, versions_end, 2); + tls_version = mbedtls_ssl_read_version(p, ssl->conf->transport); + p += 2; + + if (MBEDTLS_SSL_VERSION_TLS1_3 == tls_version) { + found_supported_version = 1; + break; + } + + if ((MBEDTLS_SSL_VERSION_TLS1_2 == tls_version) && + mbedtls_ssl_conf_is_tls12_enabled(ssl->conf)) { + found_supported_version = 1; + break; + } + } + + if (!found_supported_version) { + MBEDTLS_SSL_DEBUG_MSG(1, ("No supported version found.")); + + MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION, + MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION); + return MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION; + } + + MBEDTLS_SSL_DEBUG_MSG(1, ("Negotiated version: [%04x]", + (unsigned int) tls_version)); + + return (int) tls_version; +} + +#if defined(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH) +/* + * + * From RFC 8446: + * enum { + * ... (0xFFFF) + * } NamedGroup; + * struct { + * NamedGroup named_group_list<2..2^16-1>; + * } NamedGroupList; + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_parse_supported_groups_ext(mbedtls_ssl_context *ssl, + const unsigned char *buf, + const unsigned char *end) +{ + const unsigned char *p = buf; + size_t named_group_list_len; + const unsigned char *named_group_list_end; + + MBEDTLS_SSL_DEBUG_BUF(3, "supported_groups extension", p, end - buf); + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); + named_group_list_len = MBEDTLS_GET_UINT16_BE(p, 0); + p += 2; + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, named_group_list_len); + named_group_list_end = p + named_group_list_len; + ssl->handshake->hrr_selected_group = 0; + + while (p < named_group_list_end) { + uint16_t named_group; + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, named_group_list_end, 2); + named_group = MBEDTLS_GET_UINT16_BE(p, 0); + p += 2; + + MBEDTLS_SSL_DEBUG_MSG(2, + ("got named group: %s(%04x)", + mbedtls_ssl_named_group_to_str(named_group), + named_group)); + + if (!mbedtls_ssl_named_group_is_offered(ssl, named_group) || + !mbedtls_ssl_named_group_is_supported(named_group) || + ssl->handshake->hrr_selected_group != 0) { + continue; + } + + MBEDTLS_SSL_DEBUG_MSG(2, + ("add named group %s(%04x) into received list.", + mbedtls_ssl_named_group_to_str(named_group), + named_group)); + + ssl->handshake->hrr_selected_group = named_group; + } + + return 0; + +} +#endif /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH */ + +#define SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH 1 + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) +/* + * ssl_tls13_parse_key_shares_ext() verifies whether the information in the + * extension is correct and stores the first acceptable key share and its + * associated group. + * + * Possible return values are: + * - 0: Successful processing of the client provided key share extension. + * - SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH: The key shares provided by + * the client does not match a group supported by the server. A + * HelloRetryRequest will be needed. + * - A negative value for fatal errors. + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_parse_key_shares_ext(mbedtls_ssl_context *ssl, + const unsigned char *buf, + const unsigned char *end) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char const *p = buf; + unsigned char const *client_shares_end; + size_t client_shares_len; + + /* From RFC 8446: + * + * struct { + * KeyShareEntry client_shares<0..2^16-1>; + * } KeyShareClientHello; + * + */ + + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2); + client_shares_len = MBEDTLS_GET_UINT16_BE(p, 0); + p += 2; + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, client_shares_len); + + ssl->handshake->offered_group_id = 0; + client_shares_end = p + client_shares_len; + + /* We try to find a suitable key share entry and copy it to the + * handshake context. Later, we have to find out whether we can do + * something with the provided key share or whether we have to + * dismiss it and send a HelloRetryRequest message. + */ + + while (p < client_shares_end) { + uint16_t group; + size_t key_exchange_len; + const unsigned char *key_exchange; + + /* + * struct { + * NamedGroup group; + * opaque key_exchange<1..2^16-1>; + * } KeyShareEntry; + */ + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, client_shares_end, 4); + group = MBEDTLS_GET_UINT16_BE(p, 0); + key_exchange_len = MBEDTLS_GET_UINT16_BE(p, 2); + p += 4; + key_exchange = p; + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, client_shares_end, key_exchange_len); + p += key_exchange_len; + + /* Continue parsing even if we have already found a match, + * for input validation purposes. + */ + if (!mbedtls_ssl_named_group_is_offered(ssl, group) || + !mbedtls_ssl_named_group_is_supported(group) || + ssl->handshake->offered_group_id != 0) { + continue; + } + + /* + * ECDHE and FFDHE groups are supported + */ + if (mbedtls_ssl_tls13_named_group_is_ecdhe(group) || + mbedtls_ssl_tls13_named_group_is_ffdh(group)) { + MBEDTLS_SSL_DEBUG_MSG(2, ("ECDH/FFDH group: %s (%04x)", + mbedtls_ssl_named_group_to_str(group), + group)); + ret = mbedtls_ssl_tls13_read_public_xxdhe_share( + ssl, key_exchange - 2, key_exchange_len + 2); + if (ret != 0) { + return ret; + } + + } else { + MBEDTLS_SSL_DEBUG_MSG(4, ("Unrecognized NamedGroup %u", + (unsigned) group)); + continue; + } + + ssl->handshake->offered_group_id = group; + } + + + if (ssl->handshake->offered_group_id == 0) { + MBEDTLS_SSL_DEBUG_MSG(1, ("no matching key share")); + return SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH; + } + return 0; +} +#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_client_hello_has_exts(mbedtls_ssl_context *ssl, + int exts_mask) +{ + int masked = ssl->handshake->received_extensions & exts_mask; + return masked == exts_mask; +} + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_client_hello_has_exts_for_ephemeral_key_exchange( + mbedtls_ssl_context *ssl) +{ + return ssl_tls13_client_hello_has_exts( + ssl, + MBEDTLS_SSL_EXT_MASK(SUPPORTED_GROUPS) | + MBEDTLS_SSL_EXT_MASK(KEY_SHARE) | + MBEDTLS_SSL_EXT_MASK(SIG_ALG)); +} +#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ENABLED) +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_client_hello_has_exts_for_psk_key_exchange( + mbedtls_ssl_context *ssl) +{ + return ssl_tls13_client_hello_has_exts( + ssl, + MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY) | + MBEDTLS_SSL_EXT_MASK(PSK_KEY_EXCHANGE_MODES)); +} +#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ENABLED */ + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL_ENABLED) +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_client_hello_has_exts_for_psk_ephemeral_key_exchange( + mbedtls_ssl_context *ssl) +{ + return ssl_tls13_client_hello_has_exts( + ssl, + MBEDTLS_SSL_EXT_MASK(SUPPORTED_GROUPS) | + MBEDTLS_SSL_EXT_MASK(KEY_SHARE) | + MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY) | + MBEDTLS_SSL_EXT_MASK(PSK_KEY_EXCHANGE_MODES)); +} +#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL_ENABLED */ + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_key_exchange_is_psk_available(mbedtls_ssl_context *ssl) +{ +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ENABLED) + return mbedtls_ssl_conf_tls13_is_psk_enabled(ssl) && + mbedtls_ssl_tls13_is_psk_supported(ssl) && + ssl_tls13_client_hello_has_exts_for_psk_key_exchange(ssl); +#else + ((void) ssl); + return 0; +#endif +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_key_exchange_is_psk_ephemeral_available(mbedtls_ssl_context *ssl) +{ +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL_ENABLED) + return mbedtls_ssl_conf_tls13_is_psk_ephemeral_enabled(ssl) && + mbedtls_ssl_tls13_is_psk_ephemeral_supported(ssl) && + ssl_tls13_client_hello_has_exts_for_psk_ephemeral_key_exchange(ssl); +#else + ((void) ssl); + return 0; +#endif +} +#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_key_exchange_is_ephemeral_available(mbedtls_ssl_context *ssl) +{ +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) + return mbedtls_ssl_conf_tls13_is_ephemeral_enabled(ssl) && + ssl_tls13_client_hello_has_exts_for_ephemeral_key_exchange(ssl); +#else + ((void) ssl); + return 0; +#endif +} + +#if defined(MBEDTLS_X509_CRT_PARSE_C) && \ + defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) + +#if defined(MBEDTLS_USE_PSA_CRYPTO) +static psa_algorithm_t ssl_tls13_iana_sig_alg_to_psa_alg(uint16_t sig_alg) +{ + switch (sig_alg) { + case MBEDTLS_TLS1_3_SIG_ECDSA_SECP256R1_SHA256: + return PSA_ALG_ECDSA(PSA_ALG_SHA_256); + case MBEDTLS_TLS1_3_SIG_ECDSA_SECP384R1_SHA384: + return PSA_ALG_ECDSA(PSA_ALG_SHA_384); + case MBEDTLS_TLS1_3_SIG_ECDSA_SECP521R1_SHA512: + return PSA_ALG_ECDSA(PSA_ALG_SHA_512); + case MBEDTLS_TLS1_3_SIG_RSA_PSS_RSAE_SHA256: + return PSA_ALG_RSA_PSS(PSA_ALG_SHA_256); + case MBEDTLS_TLS1_3_SIG_RSA_PSS_RSAE_SHA384: + return PSA_ALG_RSA_PSS(PSA_ALG_SHA_384); + case MBEDTLS_TLS1_3_SIG_RSA_PSS_RSAE_SHA512: + return PSA_ALG_RSA_PSS(PSA_ALG_SHA_512); + case MBEDTLS_TLS1_3_SIG_RSA_PKCS1_SHA256: + return PSA_ALG_RSA_PKCS1V15_SIGN(PSA_ALG_SHA_256); + case MBEDTLS_TLS1_3_SIG_RSA_PKCS1_SHA384: + return PSA_ALG_RSA_PKCS1V15_SIGN(PSA_ALG_SHA_384); + case MBEDTLS_TLS1_3_SIG_RSA_PKCS1_SHA512: + return PSA_ALG_RSA_PKCS1V15_SIGN(PSA_ALG_SHA_512); + default: + return PSA_ALG_NONE; + } +} +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + +/* + * Pick best ( private key, certificate chain ) pair based on the signature + * algorithms supported by the client. + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_pick_key_cert(mbedtls_ssl_context *ssl) +{ + mbedtls_ssl_key_cert *key_cert, *key_cert_list; + const uint16_t *sig_alg = ssl->handshake->received_sig_algs; + +#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) + if (ssl->handshake->sni_key_cert != NULL) { + key_cert_list = ssl->handshake->sni_key_cert; + } else +#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ + key_cert_list = ssl->conf->key_cert; + + if (key_cert_list == NULL) { + MBEDTLS_SSL_DEBUG_MSG(3, ("server has no certificate")); + return -1; + } + + for (; *sig_alg != MBEDTLS_TLS1_3_SIG_NONE; sig_alg++) { + if (!mbedtls_ssl_sig_alg_is_offered(ssl, *sig_alg)) { + continue; + } + + if (!mbedtls_ssl_tls13_sig_alg_for_cert_verify_is_supported(*sig_alg)) { + continue; + } + + for (key_cert = key_cert_list; key_cert != NULL; + key_cert = key_cert->next) { +#if defined(MBEDTLS_USE_PSA_CRYPTO) + psa_algorithm_t psa_alg = PSA_ALG_NONE; +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + MBEDTLS_SSL_DEBUG_CRT(3, "certificate (chain) candidate", + key_cert->cert); + + /* + * This avoids sending the client a cert it'll reject based on + * keyUsage or other extensions. + */ + if (mbedtls_x509_crt_check_key_usage( + key_cert->cert, MBEDTLS_X509_KU_DIGITAL_SIGNATURE) != 0 || + mbedtls_x509_crt_check_extended_key_usage( + key_cert->cert, MBEDTLS_OID_SERVER_AUTH, + MBEDTLS_OID_SIZE(MBEDTLS_OID_SERVER_AUTH)) != 0) { + MBEDTLS_SSL_DEBUG_MSG(3, ("certificate mismatch: " + "(extended) key usage extension")); + continue; + } + + MBEDTLS_SSL_DEBUG_MSG(3, + ("ssl_tls13_pick_key_cert:" + "check signature algorithm %s [%04x]", + mbedtls_ssl_sig_alg_to_str(*sig_alg), + *sig_alg)); +#if defined(MBEDTLS_USE_PSA_CRYPTO) + psa_alg = ssl_tls13_iana_sig_alg_to_psa_alg(*sig_alg); +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + if (mbedtls_ssl_tls13_check_sig_alg_cert_key_match( + *sig_alg, &key_cert->cert->pk) +#if defined(MBEDTLS_USE_PSA_CRYPTO) + && psa_alg != PSA_ALG_NONE && + mbedtls_pk_can_do_ext(&key_cert->cert->pk, psa_alg, + PSA_KEY_USAGE_SIGN_HASH) == 1 +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + ) { + ssl->handshake->key_cert = key_cert; + MBEDTLS_SSL_DEBUG_MSG(3, + ("ssl_tls13_pick_key_cert:" + "selected signature algorithm" + " %s [%04x]", + mbedtls_ssl_sig_alg_to_str(*sig_alg), + *sig_alg)); + MBEDTLS_SSL_DEBUG_CRT( + 3, "selected certificate (chain)", + ssl->handshake->key_cert->cert); + return 0; + } + } + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("ssl_tls13_pick_key_cert:" + "no suitable certificate found")); + return -1; +} +#endif /* MBEDTLS_X509_CRT_PARSE_C && + MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ + +/* + * + * STATE HANDLING: ClientHello + * + * There are three possible classes of outcomes when parsing the ClientHello: + * + * 1) The ClientHello was well-formed and matched the server's configuration. + * + * In this case, the server progresses to sending its ServerHello. + * + * 2) The ClientHello was well-formed but didn't match the server's + * configuration. + * + * For example, the client might not have offered a key share which + * the server supports, or the server might require a cookie. + * + * In this case, the server sends a HelloRetryRequest. + * + * 3) The ClientHello was ill-formed + * + * In this case, we abort the handshake. + * + */ + +/* + * Structure of this message: + * + * uint16 ProtocolVersion; + * opaque Random[32]; + * uint8 CipherSuite[2]; // Cryptographic suite selector + * + * struct { + * ProtocolVersion legacy_version = 0x0303; // TLS v1.2 + * Random random; + * opaque legacy_session_id<0..32>; + * CipherSuite cipher_suites<2..2^16-2>; + * opaque legacy_compression_methods<1..2^8-1>; + * Extension extensions<8..2^16-1>; + * } ClientHello; + */ + +#define SSL_CLIENT_HELLO_OK 0 +#define SSL_CLIENT_HELLO_HRR_REQUIRED 1 +#define SSL_CLIENT_HELLO_TLS1_2 2 + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_parse_client_hello(mbedtls_ssl_context *ssl, + const unsigned char *buf, + const unsigned char *end) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + const unsigned char *p = buf; + const unsigned char *random; + size_t legacy_session_id_len; + const unsigned char *legacy_session_id; + size_t cipher_suites_len; + const unsigned char *cipher_suites; + const unsigned char *cipher_suites_end; + size_t extensions_len; + const unsigned char *extensions_end; + const unsigned char *supported_versions_data; + const unsigned char *supported_versions_data_end; + mbedtls_ssl_handshake_params *handshake = ssl->handshake; + int hrr_required = 0; + int no_usable_share_for_key_agreement = 0; + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) + int got_psk = 0; + struct psk_attributes psk = PSK_ATTRIBUTES_INIT; + const unsigned char *pre_shared_key_ext = NULL; + const unsigned char *pre_shared_key_ext_end = NULL; +#endif + + /* + * ClientHello layout: + * 0 . 1 protocol version + * 2 . 33 random bytes + * 34 . 34 session id length ( 1 byte ) + * 35 . 34+x session id + * .. . .. ciphersuite list length ( 2 bytes ) + * .. . .. ciphersuite list + * .. . .. compression alg. list length ( 1 byte ) + * .. . .. compression alg. list + * .. . .. extensions length ( 2 bytes, optional ) + * .. . .. extensions ( optional ) + */ + + /* + * Minimal length ( with everything empty and extensions omitted ) is + * 2 + 32 + 1 + 2 + 1 = 38 bytes. Check that first, so that we can + * read at least up to session id length without worrying. + */ + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 38); + + /* ... + * ProtocolVersion legacy_version = 0x0303; // TLS 1.2 + * ... + * with ProtocolVersion defined as: + * uint16 ProtocolVersion; + */ + if (mbedtls_ssl_read_version(p, ssl->conf->transport) != + MBEDTLS_SSL_VERSION_TLS1_2) { + MBEDTLS_SSL_DEBUG_MSG(1, ("Unsupported version of TLS.")); + MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION, + MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION); + return MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION; + } + p += 2; + + /* ... + * Random random; + * ... + * with Random defined as: + * opaque Random[32]; + */ + random = p; + p += MBEDTLS_CLIENT_HELLO_RANDOM_LEN; + + /* ... + * opaque legacy_session_id<0..32>; + * ... + */ + legacy_session_id_len = *(p++); + legacy_session_id = p; + + /* + * Check we have enough data for the legacy session identifier + * and the ciphersuite list length. + */ + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, legacy_session_id_len + 2); + p += legacy_session_id_len; + + /* ... + * CipherSuite cipher_suites<2..2^16-2>; + * ... + * with CipherSuite defined as: + * uint8 CipherSuite[2]; + */ + cipher_suites_len = MBEDTLS_GET_UINT16_BE(p, 0); + p += 2; + cipher_suites = p; + + /* + * The length of the ciphersuite list has to be even. + */ + if (cipher_suites_len & 1) { + MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, + MBEDTLS_ERR_SSL_DECODE_ERROR); + return MBEDTLS_ERR_SSL_DECODE_ERROR; + } + + /* Check we have enough data for the ciphersuite list, the legacy + * compression methods and the length of the extensions. + * + * cipher_suites cipher_suites_len bytes + * legacy_compression_methods 2 bytes + * extensions_len 2 bytes + */ + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, cipher_suites_len + 2 + 2); + p += cipher_suites_len; + cipher_suites_end = p; + + /* + * Search for the supported versions extension and parse it to determine + * if the client supports TLS 1.3. + */ + ret = mbedtls_ssl_tls13_is_supported_versions_ext_present_in_exts( + ssl, p + 2, end, + &supported_versions_data, &supported_versions_data_end); + if (ret < 0) { + MBEDTLS_SSL_DEBUG_RET(1, + ("mbedtls_ssl_tls13_is_supported_versions_ext_present_in_exts"), ret); + return ret; + } + + if (ret == 0) { + return SSL_CLIENT_HELLO_TLS1_2; + } + + if (ret == 1) { + ret = ssl_tls13_parse_supported_versions_ext(ssl, + supported_versions_data, + supported_versions_data_end); + if (ret < 0) { + MBEDTLS_SSL_DEBUG_RET(1, + ("ssl_tls13_parse_supported_versions_ext"), ret); + return ret; + } + + /* + * The supported versions extension was parsed successfully as the + * value returned by ssl_tls13_parse_supported_versions_ext() is + * positive. The return value is then equal to + * MBEDTLS_SSL_VERSION_TLS1_2 or MBEDTLS_SSL_VERSION_TLS1_3, defining + * the TLS version to negotiate. + */ + if (MBEDTLS_SSL_VERSION_TLS1_2 == ret) { + return SSL_CLIENT_HELLO_TLS1_2; + } + } + + /* + * We negotiate TLS 1.3. + */ + ssl->tls_version = MBEDTLS_SSL_VERSION_TLS1_3; + ssl->session_negotiate->tls_version = MBEDTLS_SSL_VERSION_TLS1_3; + ssl->session_negotiate->endpoint = ssl->conf->endpoint; + + /* + * We are negotiating the version 1.3 of the protocol. Do what we have + * postponed: copy of the client random bytes, copy of the legacy session + * identifier and selection of the TLS 1.3 cipher suite. + */ + MBEDTLS_SSL_DEBUG_BUF(3, "client hello, random bytes", + random, MBEDTLS_CLIENT_HELLO_RANDOM_LEN); + memcpy(&handshake->randbytes[0], random, MBEDTLS_CLIENT_HELLO_RANDOM_LEN); + + if (legacy_session_id_len > sizeof(ssl->session_negotiate->id)) { + MBEDTLS_SSL_DEBUG_MSG(1, ("bad client hello message")); + return MBEDTLS_ERR_SSL_DECODE_ERROR; + } + ssl->session_negotiate->id_len = legacy_session_id_len; + MBEDTLS_SSL_DEBUG_BUF(3, "client hello, session id", + legacy_session_id, legacy_session_id_len); + memcpy(&ssl->session_negotiate->id[0], + legacy_session_id, legacy_session_id_len); + + /* + * Search for a matching ciphersuite + */ + MBEDTLS_SSL_DEBUG_BUF(3, "client hello, list of cipher suites", + cipher_suites, cipher_suites_len); + + ssl_tls13_select_ciphersuite(ssl, cipher_suites, cipher_suites_end, + 0, PSA_ALG_NONE, &handshake->ciphersuite_info); + + if (handshake->ciphersuite_info == NULL) { + MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, + MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); + return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; + } + ssl->session_negotiate->ciphersuite = handshake->ciphersuite_info->id; + + MBEDTLS_SSL_DEBUG_MSG(2, ("selected ciphersuite: %04x - %s", + ((unsigned) handshake->ciphersuite_info->id), + handshake->ciphersuite_info->name)); + + /* ... + * opaque legacy_compression_methods<1..2^8-1>; + * ... + */ + if (p[0] != 1 || p[1] != MBEDTLS_SSL_COMPRESS_NULL) { + MBEDTLS_SSL_DEBUG_MSG(1, ("bad legacy compression method")); + MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, + MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); + return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; + } + p += 2; + + /* ... + * Extension extensions<8..2^16-1>; + * ... + * with Extension defined as: + * struct { + * ExtensionType extension_type; + * opaque extension_data<0..2^16-1>; + * } Extension; + */ + extensions_len = MBEDTLS_GET_UINT16_BE(p, 0); + p += 2; + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, extensions_len); + extensions_end = p + extensions_len; + + MBEDTLS_SSL_DEBUG_BUF(3, "client hello extensions", p, extensions_len); + handshake->received_extensions = MBEDTLS_SSL_EXT_MASK_NONE; + + while (p < extensions_end) { + unsigned int extension_type; + size_t extension_data_len; + const unsigned char *extension_data_end; + uint32_t allowed_exts = MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_CH; + + if (ssl->handshake->hello_retry_request_flag) { + /* Do not accept early data extension in 2nd ClientHello */ + allowed_exts &= ~MBEDTLS_SSL_EXT_MASK(EARLY_DATA); + } + + /* RFC 8446, section 4.2.11 + * + * The "pre_shared_key" extension MUST be the last extension in the + * ClientHello (this facilitates implementation as described below). + * Servers MUST check that it is the last extension and otherwise fail + * the handshake with an "illegal_parameter" alert. + */ + if (handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY)) { + MBEDTLS_SSL_DEBUG_MSG( + 3, ("pre_shared_key is not last extension.")); + MBEDTLS_SSL_PEND_FATAL_ALERT( + MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, + MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); + return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; + } + + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, extensions_end, 4); + extension_type = MBEDTLS_GET_UINT16_BE(p, 0); + extension_data_len = MBEDTLS_GET_UINT16_BE(p, 2); + p += 4; + + MBEDTLS_SSL_CHK_BUF_READ_PTR(p, extensions_end, extension_data_len); + extension_data_end = p + extension_data_len; + + ret = mbedtls_ssl_tls13_check_received_extension( + ssl, MBEDTLS_SSL_HS_CLIENT_HELLO, extension_type, + allowed_exts); + if (ret != 0) { + return ret; + } + + switch (extension_type) { +#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) + case MBEDTLS_TLS_EXT_SERVERNAME: + MBEDTLS_SSL_DEBUG_MSG(3, ("found ServerName extension")); + ret = mbedtls_ssl_parse_server_name_ext(ssl, p, + extension_data_end); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET( + 1, "mbedtls_ssl_parse_servername_ext", ret); + return ret; + } + break; +#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ + +#if defined(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH) + case MBEDTLS_TLS_EXT_SUPPORTED_GROUPS: + MBEDTLS_SSL_DEBUG_MSG(3, ("found supported group extension")); + + /* Supported Groups Extension + * + * When sent by the client, the "supported_groups" extension + * indicates the named groups which the client supports, + * ordered from most preferred to least preferred. + */ + ret = ssl_tls13_parse_supported_groups_ext( + ssl, p, extension_data_end); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET( + 1, "ssl_tls13_parse_supported_groups_ext", ret); + return ret; + } + + break; +#endif /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH*/ + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) + case MBEDTLS_TLS_EXT_KEY_SHARE: + MBEDTLS_SSL_DEBUG_MSG(3, ("found key share extension")); + + /* + * Key Share Extension + * + * When sent by the client, the "key_share" extension + * contains the endpoint's cryptographic parameters for + * ECDHE/DHE key establishment methods. + */ + ret = ssl_tls13_parse_key_shares_ext( + ssl, p, extension_data_end); + if (ret == SSL_TLS1_3_PARSE_KEY_SHARES_EXT_NO_MATCH) { + MBEDTLS_SSL_DEBUG_MSG(2, ("No usable share for key agreement.")); + no_usable_share_for_key_agreement = 1; + } + + if (ret < 0) { + MBEDTLS_SSL_DEBUG_RET( + 1, "ssl_tls13_parse_key_shares_ext", ret); + return ret; + } + + break; +#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ + + case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS: + /* Already parsed */ + break; + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) + case MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES: + MBEDTLS_SSL_DEBUG_MSG( + 3, ("found psk key exchange modes extension")); + + ret = ssl_tls13_parse_key_exchange_modes_ext( + ssl, p, extension_data_end); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET( + 1, "ssl_tls13_parse_key_exchange_modes_ext", ret); + return ret; + } + + break; +#endif + + case MBEDTLS_TLS_EXT_PRE_SHARED_KEY: + MBEDTLS_SSL_DEBUG_MSG(3, ("found pre_shared_key extension")); + if ((handshake->received_extensions & + MBEDTLS_SSL_EXT_MASK(PSK_KEY_EXCHANGE_MODES)) == 0) { + MBEDTLS_SSL_PEND_FATAL_ALERT( + MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER, + MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); + return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; + } +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) + /* Delay processing of the PSK identity once we have + * found out which algorithms to use. We keep a pointer + * to the buffer and the size for later processing. + */ + pre_shared_key_ext = p; + pre_shared_key_ext_end = extension_data_end; +#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ + break; + +#if defined(MBEDTLS_SSL_ALPN) + case MBEDTLS_TLS_EXT_ALPN: + MBEDTLS_SSL_DEBUG_MSG(3, ("found alpn extension")); + + ret = mbedtls_ssl_parse_alpn_ext(ssl, p, extension_data_end); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET( + 1, ("mbedtls_ssl_parse_alpn_ext"), ret); + return ret; + } + break; +#endif /* MBEDTLS_SSL_ALPN */ + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) + case MBEDTLS_TLS_EXT_SIG_ALG: + MBEDTLS_SSL_DEBUG_MSG(3, ("found signature_algorithms extension")); + + ret = mbedtls_ssl_parse_sig_alg_ext( + ssl, p, extension_data_end); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET( + 1, "mbedtls_ssl_parse_sig_alg_ext", ret); + return ret; + } + break; +#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ + +#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT) + case MBEDTLS_TLS_EXT_RECORD_SIZE_LIMIT: + MBEDTLS_SSL_DEBUG_MSG(3, ("found record_size_limit extension")); + + ret = mbedtls_ssl_tls13_parse_record_size_limit_ext( + ssl, p, extension_data_end); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET( + 1, ("mbedtls_ssl_tls13_parse_record_size_limit_ext"), ret); + return ret; + } + break; +#endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */ + + default: + MBEDTLS_SSL_PRINT_EXT( + 3, MBEDTLS_SSL_HS_CLIENT_HELLO, + extension_type, "( ignored )"); + break; + } + + p += extension_data_len; + } + + MBEDTLS_SSL_PRINT_EXTS(3, MBEDTLS_SSL_HS_CLIENT_HELLO, + handshake->received_extensions); + + ret = mbedtls_ssl_add_hs_hdr_to_checksum(ssl, + MBEDTLS_SSL_HS_CLIENT_HELLO, + p - buf); + if (0 != ret) { + MBEDTLS_SSL_DEBUG_RET(1, ("mbedtls_ssl_add_hs_hdr_to_checksum"), ret); + return ret; + } + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) + /* Update checksum with either + * - The entire content of the CH message, if no PSK extension is present + * - The content up to but excluding the PSK extension, if present. + * Always parse the pre-shared-key extension when present in the + * ClientHello even if some pre-requisites for PSK key exchange modes are + * not met. That way we always validate the syntax of the extension. + */ + if (handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY)) { + ret = handshake->update_checksum(ssl, buf, + pre_shared_key_ext - buf); + if (0 != ret) { + MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret); + return ret; + } + ret = ssl_tls13_parse_pre_shared_key_ext(ssl, + pre_shared_key_ext, + pre_shared_key_ext_end, + cipher_suites, + cipher_suites_end, + &psk); + if (ret == 0) { + got_psk = 1; + } else if (ret != MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY) { + MBEDTLS_SSL_DEBUG_RET( + 1, "ssl_tls13_parse_pre_shared_key_ext", ret); + return ret; + } + } else +#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */ + { + ret = handshake->update_checksum(ssl, buf, p - buf); + if (0 != ret) { + MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret); + return ret; + } + } + + /* + * Determine the key exchange algorithm to use. + * There are three types of key exchanges supported in TLS 1.3: + * - (EC)DH with ECDSA, + * - (EC)DH with PSK, + * - plain PSK. + * + * The PSK-based key exchanges may additionally be used with 0-RTT. + * + * Our built-in order of preference is + * 1 ) (EC)DHE-PSK Mode ( psk_ephemeral ) + * 2 ) Certificate Mode ( ephemeral ) + * 3 ) Plain PSK Mode ( psk ) + */ +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) + if (got_psk && (psk.key_exchange_mode == + MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL)) { + handshake->key_exchange_mode = + MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL; + MBEDTLS_SSL_DEBUG_MSG(2, ("key exchange mode: psk_ephemeral")); + + } else +#endif + if (ssl_tls13_key_exchange_is_ephemeral_available(ssl)) { + handshake->key_exchange_mode = + MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL; + MBEDTLS_SSL_DEBUG_MSG(2, ("key exchange mode: ephemeral")); + + } +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) + else if (got_psk && (psk.key_exchange_mode == + MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK)) { + handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK; + MBEDTLS_SSL_DEBUG_MSG(2, ("key exchange mode: psk")); + } +#endif + else { + MBEDTLS_SSL_DEBUG_MSG( + 1, + ("ClientHello message misses mandatory extensions.")); + MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_MISSING_EXTENSION, + MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER); + return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER; + } + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) + if (handshake->key_exchange_mode & + MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL) { + handshake->ciphersuite_info = psk.ciphersuite_info; + ssl->session_negotiate->ciphersuite = psk.ciphersuite_info->id; + + MBEDTLS_SSL_DEBUG_MSG(2, ("Select PSK ciphersuite: %04x - %s", + ((unsigned) psk.ciphersuite_info->id), + psk.ciphersuite_info->name)); + + if (psk.type == MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION) { + handshake->resume = 1; + } + } +#endif + + if (handshake->key_exchange_mode != + MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK) { + hrr_required = (no_usable_share_for_key_agreement != 0); + } + + mbedtls_ssl_optimize_checksum(ssl, handshake->ciphersuite_info); + + return hrr_required ? SSL_CLIENT_HELLO_HRR_REQUIRED : SSL_CLIENT_HELLO_OK; +} + +#if defined(MBEDTLS_SSL_EARLY_DATA) +static int ssl_tls13_check_early_data_requirements(mbedtls_ssl_context *ssl) +{ + mbedtls_ssl_handshake_params *handshake = ssl->handshake; + + if (ssl->conf->early_data_enabled == MBEDTLS_SSL_EARLY_DATA_DISABLED) { + MBEDTLS_SSL_DEBUG_MSG( + 1, + ("EarlyData: rejected, feature disabled in server configuration.")); + return -1; + } + + if (!handshake->resume) { + /* We currently support early data only in the case of PSKs established + via a NewSessionTicket message thus in the case of a session + resumption. */ + MBEDTLS_SSL_DEBUG_MSG( + 1, ("EarlyData: rejected, not a session resumption.")); + return -1; + } + + /* RFC 8446 4.2.10 + * + * In order to accept early data, the server MUST have accepted a PSK cipher + * suite and selected the first key offered in the client's "pre_shared_key" + * extension. In addition, it MUST verify that the following values are the + * same as those associated with the selected PSK: + * - The TLS version number + * - The selected cipher suite + * - The selected ALPN [RFC7301] protocol, if any + * + * NOTE: + * - The TLS version number is checked in + * ssl_tls13_offered_psks_check_identity_match_ticket(). + */ + + if (handshake->selected_identity != 0) { + MBEDTLS_SSL_DEBUG_MSG( + 1, ("EarlyData: rejected, the selected key in " + "`pre_shared_key` is not the first one.")); + return -1; + } + + if (handshake->ciphersuite_info->id != + ssl->session_negotiate->ciphersuite) { + MBEDTLS_SSL_DEBUG_MSG( + 1, ("EarlyData: rejected, the selected ciphersuite is not the one " + "of the selected pre-shared key.")); + return -1; + + } + + if (!mbedtls_ssl_tls13_session_ticket_allow_early_data(ssl->session_negotiate)) { + MBEDTLS_SSL_DEBUG_MSG( + 1, + ("EarlyData: rejected, early_data not allowed in ticket " + "permission bits.")); + return -1; + } + +#if defined(MBEDTLS_SSL_ALPN) + const char *alpn = mbedtls_ssl_get_alpn_protocol(ssl); + size_t alpn_len; + + if (alpn == NULL && ssl->session_negotiate->ticket_alpn == NULL) { + return 0; + } + + if (alpn != NULL) { + alpn_len = strlen(alpn); + } + + if (alpn == NULL || + ssl->session_negotiate->ticket_alpn == NULL || + alpn_len != strlen(ssl->session_negotiate->ticket_alpn) || + (memcmp(alpn, ssl->session_negotiate->ticket_alpn, alpn_len) != 0)) { + MBEDTLS_SSL_DEBUG_MSG(1, ("EarlyData: rejected, the selected ALPN is different " + "from the one associated with the pre-shared key.")); + return -1; + } +#endif + + return 0; +} +#endif /* MBEDTLS_SSL_EARLY_DATA */ + +/* Update the handshake state machine */ + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_postprocess_client_hello(mbedtls_ssl_context *ssl, + int hrr_required) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + /* + * Server certificate selection + */ + if (ssl->conf->f_cert_cb && (ret = ssl->conf->f_cert_cb(ssl)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "f_cert_cb", ret); + return ret; + } +#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) + ssl->handshake->sni_name = NULL; + ssl->handshake->sni_name_len = 0; +#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */ + + ret = mbedtls_ssl_tls13_key_schedule_stage_early(ssl); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, + "mbedtls_ssl_tls1_3_key_schedule_stage_early", ret); + return ret; + } + +#if defined(MBEDTLS_SSL_EARLY_DATA) + if (ssl->handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(EARLY_DATA)) { + ssl->handshake->early_data_accepted = + (!hrr_required) && (ssl_tls13_check_early_data_requirements(ssl) == 0); + + if (ssl->handshake->early_data_accepted) { + ret = mbedtls_ssl_tls13_compute_early_transform(ssl); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET( + 1, "mbedtls_ssl_tls13_compute_early_transform", ret); + return ret; + } + } else { + ssl->discard_early_data_record = + hrr_required ? + MBEDTLS_SSL_EARLY_DATA_DISCARD : + MBEDTLS_SSL_EARLY_DATA_TRY_TO_DEPROTECT_AND_DISCARD; + } + } +#else + ((void) hrr_required); +#endif /* MBEDTLS_SSL_EARLY_DATA */ + + return 0; +} + +/* + * Main entry point from the state machine; orchestrates the otherfunctions. + */ + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_process_client_hello(mbedtls_ssl_context *ssl) +{ + + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char *buf = NULL; + size_t buflen = 0; + int parse_client_hello_ret; + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> parse client hello")); + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_tls13_fetch_handshake_msg( + ssl, MBEDTLS_SSL_HS_CLIENT_HELLO, + &buf, &buflen)); + + MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_parse_client_hello(ssl, buf, + buf + buflen)); + parse_client_hello_ret = ret; /* Store positive return value of + * parse_client_hello, + * as negative error codes are handled + * by MBEDTLS_SSL_PROC_CHK_NEG. */ + + /* + * Version 1.2 of the protocol has to be used for the handshake. + * If TLS 1.2 is not supported, abort the handshake. Otherwise, set the + * ssl->keep_current_message flag for the ClientHello to be kept and parsed + * as a TLS 1.2 ClientHello. We also change ssl->tls_version to + * MBEDTLS_SSL_VERSION_TLS1_2 thus from now on mbedtls_ssl_handshake_step() + * will dispatch to the TLS 1.2 state machine. + */ + if (SSL_CLIENT_HELLO_TLS1_2 == parse_client_hello_ret) { + /* Check if server supports TLS 1.2 */ + if (!mbedtls_ssl_conf_is_tls12_enabled(ssl->conf)) { + MBEDTLS_SSL_DEBUG_MSG( + 1, ("TLS 1.2 not supported.")); + MBEDTLS_SSL_PEND_FATAL_ALERT( + MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION, + MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION); + return MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION; + } + ssl->keep_current_message = 1; + ssl->tls_version = MBEDTLS_SSL_VERSION_TLS1_2; + return 0; + } + + MBEDTLS_SSL_PROC_CHK( + ssl_tls13_postprocess_client_hello(ssl, parse_client_hello_ret == + SSL_CLIENT_HELLO_HRR_REQUIRED)); + + if (SSL_CLIENT_HELLO_OK == parse_client_hello_ret) { + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_HELLO); + } else { + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HELLO_RETRY_REQUEST); + } + +cleanup: + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= parse client hello")); + return ret; +} + +/* + * Handler for MBEDTLS_SSL_SERVER_HELLO + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_prepare_server_hello(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char *server_randbytes = + ssl->handshake->randbytes + MBEDTLS_CLIENT_HELLO_RANDOM_LEN; + + if ((ret = ssl->conf->f_rng(ssl->conf->p_rng, server_randbytes, + MBEDTLS_SERVER_HELLO_RANDOM_LEN)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "f_rng", ret); + return ret; + } + + MBEDTLS_SSL_DEBUG_BUF(3, "server hello, random bytes", server_randbytes, + MBEDTLS_SERVER_HELLO_RANDOM_LEN); + +#if defined(MBEDTLS_HAVE_TIME) + ssl->session_negotiate->start = mbedtls_time(NULL); +#endif /* MBEDTLS_HAVE_TIME */ + + return ret; +} + +/* + * ssl_tls13_write_server_hello_supported_versions_ext (): + * + * struct { + * ProtocolVersion selected_version; + * } SupportedVersions; + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_write_server_hello_supported_versions_ext( + mbedtls_ssl_context *ssl, + unsigned char *buf, + unsigned char *end, + size_t *out_len) +{ + *out_len = 0; + + MBEDTLS_SSL_DEBUG_MSG(3, ("server hello, write selected version")); + + /* Check if we have space to write the extension: + * - extension_type (2 bytes) + * - extension_data_length (2 bytes) + * - selected_version (2 bytes) + */ + MBEDTLS_SSL_CHK_BUF_PTR(buf, end, 6); + + MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS, buf, 0); + + MBEDTLS_PUT_UINT16_BE(2, buf, 2); + + mbedtls_ssl_write_version(buf + 4, + ssl->conf->transport, + ssl->tls_version); + + MBEDTLS_SSL_DEBUG_MSG(3, ("supported version: [%04x]", + ssl->tls_version)); + + *out_len = 6; + + mbedtls_ssl_tls13_set_hs_sent_ext_mask( + ssl, MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS); + + return 0; +} + + + +/* Generate and export a single key share. For hybrid KEMs, this can + * be called multiple times with the different components of the hybrid. */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_generate_and_write_key_share(mbedtls_ssl_context *ssl, + uint16_t named_group, + unsigned char *buf, + unsigned char *end, + size_t *out_len) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + *out_len = 0; + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED) + if (mbedtls_ssl_tls13_named_group_is_ecdhe(named_group) || + mbedtls_ssl_tls13_named_group_is_ffdh(named_group)) { + ret = mbedtls_ssl_tls13_generate_and_write_xxdh_key_exchange( + ssl, named_group, buf, end, out_len); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET( + 1, "mbedtls_ssl_tls13_generate_and_write_xxdh_key_exchange", + ret); + return ret; + } + } else +#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED */ + if (0 /* Other kinds of KEMs */) { + } else { + ((void) ssl); + ((void) named_group); + ((void) buf); + ((void) end); + ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + return ret; +} + +/* + * ssl_tls13_write_key_share_ext + * + * Structure of key_share extension in ServerHello: + * + * struct { + * NamedGroup group; + * opaque key_exchange<1..2^16-1>; + * } KeyShareEntry; + * struct { + * KeyShareEntry server_share; + * } KeyShareServerHello; + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_write_key_share_ext(mbedtls_ssl_context *ssl, + unsigned char *buf, + unsigned char *end, + size_t *out_len) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char *p = buf; + uint16_t group = ssl->handshake->offered_group_id; + unsigned char *server_share = buf + 4; + size_t key_exchange_length; + + *out_len = 0; + + MBEDTLS_SSL_DEBUG_MSG(3, ("server hello, adding key share extension")); + + MBEDTLS_SSL_DEBUG_MSG(2, ("server hello, write selected_group: %s (%04x)", + mbedtls_ssl_named_group_to_str(group), + group)); + + /* Check if we have space for header and length fields: + * - extension_type (2 bytes) + * - extension_data_length (2 bytes) + * - group (2 bytes) + * - key_exchange_length (2 bytes) + */ + MBEDTLS_SSL_CHK_BUF_PTR(p, end, 8); + MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_KEY_SHARE, p, 0); + MBEDTLS_PUT_UINT16_BE(group, server_share, 0); + p += 8; + + /* When we introduce PQC-ECDHE hybrids, we'll want to call this + * function multiple times. */ + ret = ssl_tls13_generate_and_write_key_share( + ssl, group, server_share + 4, end, &key_exchange_length); + if (ret != 0) { + return ret; + } + p += key_exchange_length; + + MBEDTLS_PUT_UINT16_BE(key_exchange_length, server_share + 2, 0); + + MBEDTLS_PUT_UINT16_BE(p - server_share, buf, 2); + + *out_len = p - buf; + + mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_KEY_SHARE); + + return 0; +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_write_hrr_key_share_ext(mbedtls_ssl_context *ssl, + unsigned char *buf, + unsigned char *end, + size_t *out_len) +{ + uint16_t selected_group = ssl->handshake->hrr_selected_group; + /* key_share Extension + * + * struct { + * select (Handshake.msg_type) { + * ... + * case hello_retry_request: + * NamedGroup selected_group; + * ... + * }; + * } KeyShare; + */ + + *out_len = 0; + + /* + * For a pure PSK key exchange, there is no group to agree upon. The purpose + * of the HRR is then to transmit a cookie to force the client to demonstrate + * reachability at their apparent network address (primarily useful for DTLS). + */ + if (!mbedtls_ssl_tls13_key_exchange_mode_with_ephemeral(ssl)) { + return 0; + } + + /* We should only send the key_share extension if the client's initial + * key share was not acceptable. */ + if (ssl->handshake->offered_group_id != 0) { + MBEDTLS_SSL_DEBUG_MSG(4, ("Skip key_share extension in HRR")); + return 0; + } + + if (selected_group == 0) { + MBEDTLS_SSL_DEBUG_MSG(1, ("no matching named group found")); + return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; + } + + /* Check if we have enough space: + * - extension_type (2 bytes) + * - extension_data_length (2 bytes) + * - selected_group (2 bytes) + */ + MBEDTLS_SSL_CHK_BUF_PTR(buf, end, 6); + + MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_KEY_SHARE, buf, 0); + MBEDTLS_PUT_UINT16_BE(2, buf, 2); + MBEDTLS_PUT_UINT16_BE(selected_group, buf, 4); + + MBEDTLS_SSL_DEBUG_MSG(3, + ("HRR selected_group: %s (%x)", + mbedtls_ssl_named_group_to_str(selected_group), + selected_group)); + + *out_len = 6; + + mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_KEY_SHARE); + + return 0; +} + +/* + * Structure of ServerHello message: + * + * struct { + * ProtocolVersion legacy_version = 0x0303; // TLS v1.2 + * Random random; + * opaque legacy_session_id_echo<0..32>; + * CipherSuite cipher_suite; + * uint8 legacy_compression_method = 0; + * Extension extensions<6..2^16-1>; + * } ServerHello; + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_write_server_hello_body(mbedtls_ssl_context *ssl, + unsigned char *buf, + unsigned char *end, + size_t *out_len, + int is_hrr) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char *p = buf; + unsigned char *p_extensions_len; + size_t output_len; + + *out_len = 0; + ssl->handshake->sent_extensions = MBEDTLS_SSL_EXT_MASK_NONE; + + /* ... + * ProtocolVersion legacy_version = 0x0303; // TLS 1.2 + * ... + * with ProtocolVersion defined as: + * uint16 ProtocolVersion; + */ + MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); + MBEDTLS_PUT_UINT16_BE(0x0303, p, 0); + p += 2; + + /* ... + * Random random; + * ... + * with Random defined as: + * opaque Random[MBEDTLS_SERVER_HELLO_RANDOM_LEN]; + */ + MBEDTLS_SSL_CHK_BUF_PTR(p, end, MBEDTLS_SERVER_HELLO_RANDOM_LEN); + if (is_hrr) { + memcpy(p, mbedtls_ssl_tls13_hello_retry_request_magic, + MBEDTLS_SERVER_HELLO_RANDOM_LEN); + } else { + memcpy(p, &ssl->handshake->randbytes[MBEDTLS_CLIENT_HELLO_RANDOM_LEN], + MBEDTLS_SERVER_HELLO_RANDOM_LEN); + } + MBEDTLS_SSL_DEBUG_BUF(3, "server hello, random bytes", + p, MBEDTLS_SERVER_HELLO_RANDOM_LEN); + p += MBEDTLS_SERVER_HELLO_RANDOM_LEN; + + /* ... + * opaque legacy_session_id_echo<0..32>; + * ... + */ + MBEDTLS_SSL_CHK_BUF_PTR(p, end, 1 + ssl->session_negotiate->id_len); + *p++ = (unsigned char) ssl->session_negotiate->id_len; + if (ssl->session_negotiate->id_len > 0) { + memcpy(p, &ssl->session_negotiate->id[0], + ssl->session_negotiate->id_len); + p += ssl->session_negotiate->id_len; + + MBEDTLS_SSL_DEBUG_BUF(3, "session id", ssl->session_negotiate->id, + ssl->session_negotiate->id_len); + } + + /* ... + * CipherSuite cipher_suite; + * ... + * with CipherSuite defined as: + * uint8 CipherSuite[2]; + */ + MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); + MBEDTLS_PUT_UINT16_BE(ssl->session_negotiate->ciphersuite, p, 0); + p += 2; + MBEDTLS_SSL_DEBUG_MSG(3, + ("server hello, chosen ciphersuite: %s ( id=%d )", + mbedtls_ssl_get_ciphersuite_name( + ssl->session_negotiate->ciphersuite), + ssl->session_negotiate->ciphersuite)); + + /* ... + * uint8 legacy_compression_method = 0; + * ... + */ + MBEDTLS_SSL_CHK_BUF_PTR(p, end, 1); + *p++ = MBEDTLS_SSL_COMPRESS_NULL; + + /* ... + * Extension extensions<6..2^16-1>; + * ... + * struct { + * ExtensionType extension_type; (2 bytes) + * opaque extension_data<0..2^16-1>; + * } Extension; + */ + MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); + p_extensions_len = p; + p += 2; + + if ((ret = ssl_tls13_write_server_hello_supported_versions_ext( + ssl, p, end, &output_len)) != 0) { + MBEDTLS_SSL_DEBUG_RET( + 1, "ssl_tls13_write_server_hello_supported_versions_ext", ret); + return ret; + } + p += output_len; + + if (mbedtls_ssl_tls13_key_exchange_mode_with_ephemeral(ssl)) { + if (is_hrr) { + ret = ssl_tls13_write_hrr_key_share_ext(ssl, p, end, &output_len); + } else { + ret = ssl_tls13_write_key_share_ext(ssl, p, end, &output_len); + } + if (ret != 0) { + return ret; + } + p += output_len; + } + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) + if (!is_hrr && mbedtls_ssl_tls13_key_exchange_mode_with_psk(ssl)) { + ret = ssl_tls13_write_server_pre_shared_key_ext(ssl, p, end, &output_len); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_write_server_pre_shared_key_ext", + ret); + return ret; + } + p += output_len; + } +#endif + + MBEDTLS_PUT_UINT16_BE(p - p_extensions_len - 2, p_extensions_len, 0); + + MBEDTLS_SSL_DEBUG_BUF(4, "server hello extensions", + p_extensions_len, p - p_extensions_len); + + *out_len = p - buf; + + MBEDTLS_SSL_DEBUG_BUF(3, "server hello", buf, *out_len); + + MBEDTLS_SSL_PRINT_EXTS( + 3, is_hrr ? MBEDTLS_SSL_TLS1_3_HS_HELLO_RETRY_REQUEST : + MBEDTLS_SSL_HS_SERVER_HELLO, + ssl->handshake->sent_extensions); + + return ret; +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_finalize_server_hello(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + ret = mbedtls_ssl_tls13_compute_handshake_transform(ssl); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, + "mbedtls_ssl_tls13_compute_handshake_transform", + ret); + return ret; + } + + return ret; +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_write_server_hello(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char *buf; + size_t buf_len, msg_len; + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> write server hello")); + + MBEDTLS_SSL_PROC_CHK(ssl_tls13_prepare_server_hello(ssl)); + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( + ssl, MBEDTLS_SSL_HS_SERVER_HELLO, &buf, &buf_len)); + + MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_server_hello_body(ssl, buf, + buf + buf_len, + &msg_len, + 0)); + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( + ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, msg_len)); + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( + ssl, buf_len, msg_len)); + + MBEDTLS_SSL_PROC_CHK(ssl_tls13_finalize_server_hello(ssl)); + +#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) + /* The server sends a dummy change_cipher_spec record immediately + * after its first handshake message. This may either be after + * a ServerHello or a HelloRetryRequest. + */ + mbedtls_ssl_handshake_set_state( + ssl, MBEDTLS_SSL_SERVER_CCS_AFTER_SERVER_HELLO); +#else + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS); +#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ + +cleanup: + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= write server hello")); + return ret; +} + + +/* + * Handler for MBEDTLS_SSL_HELLO_RETRY_REQUEST + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_prepare_hello_retry_request(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + if (ssl->handshake->hello_retry_request_flag) { + MBEDTLS_SSL_DEBUG_MSG(1, ("Too many HRRs")); + MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, + MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); + return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; + } + + /* + * Create stateless transcript hash for HRR + */ + MBEDTLS_SSL_DEBUG_MSG(4, ("Reset transcript for HRR")); + ret = mbedtls_ssl_reset_transcript_for_hrr(ssl); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_reset_transcript_for_hrr", ret); + return ret; + } + mbedtls_ssl_session_reset_msg_layer(ssl, 0); + + return 0; +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_write_hello_retry_request(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char *buf; + size_t buf_len, msg_len; + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> write hello retry request")); + + MBEDTLS_SSL_PROC_CHK(ssl_tls13_prepare_hello_retry_request(ssl)); + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( + ssl, MBEDTLS_SSL_HS_SERVER_HELLO, + &buf, &buf_len)); + + MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_server_hello_body(ssl, buf, + buf + buf_len, + &msg_len, + 1)); + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( + ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, msg_len)); + + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg(ssl, buf_len, + msg_len)); + + ssl->handshake->hello_retry_request_flag = 1; + +#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) + /* The server sends a dummy change_cipher_spec record immediately + * after its first handshake message. This may either be after + * a ServerHello or a HelloRetryRequest. + */ + mbedtls_ssl_handshake_set_state( + ssl, MBEDTLS_SSL_SERVER_CCS_AFTER_HELLO_RETRY_REQUEST); +#else + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO); +#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ + +cleanup: + MBEDTLS_SSL_DEBUG_MSG(2, ("<= write hello retry request")); + return ret; +} + +/* + * Handler for MBEDTLS_SSL_ENCRYPTED_EXTENSIONS + */ + +/* + * struct { + * Extension extensions<0..2 ^ 16 - 1>; + * } EncryptedExtensions; + * + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_write_encrypted_extensions_body(mbedtls_ssl_context *ssl, + unsigned char *buf, + unsigned char *end, + size_t *out_len) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char *p = buf; + size_t extensions_len = 0; + unsigned char *p_extensions_len; + size_t output_len; + + *out_len = 0; + + MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); + p_extensions_len = p; + p += 2; + + ((void) ssl); + ((void) ret); + ((void) output_len); + +#if defined(MBEDTLS_SSL_ALPN) + ret = mbedtls_ssl_write_alpn_ext(ssl, p, end, &output_len); + if (ret != 0) { + return ret; + } + p += output_len; +#endif /* MBEDTLS_SSL_ALPN */ + +#if defined(MBEDTLS_SSL_EARLY_DATA) + if (ssl->handshake->early_data_accepted) { + ret = mbedtls_ssl_tls13_write_early_data_ext( + ssl, 0, p, end, &output_len); + if (ret != 0) { + return ret; + } + p += output_len; + } +#endif /* MBEDTLS_SSL_EARLY_DATA */ + +#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT) + if (ssl->handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(RECORD_SIZE_LIMIT)) { + ret = mbedtls_ssl_tls13_write_record_size_limit_ext( + ssl, p, end, &output_len); + if (ret != 0) { + return ret; + } + p += output_len; + } +#endif + + extensions_len = (p - p_extensions_len) - 2; + MBEDTLS_PUT_UINT16_BE(extensions_len, p_extensions_len, 0); + + *out_len = p - buf; + + MBEDTLS_SSL_DEBUG_BUF(4, "encrypted extensions", buf, *out_len); + + MBEDTLS_SSL_PRINT_EXTS( + 3, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, ssl->handshake->sent_extensions); + + return 0; +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_write_encrypted_extensions(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char *buf; + size_t buf_len, msg_len; + + mbedtls_ssl_set_outbound_transform(ssl, + ssl->handshake->transform_handshake); + MBEDTLS_SSL_DEBUG_MSG( + 3, ("switching to handshake transform for outbound data")); + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> write encrypted extensions")); + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( + ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, + &buf, &buf_len)); + + MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_encrypted_extensions_body( + ssl, buf, buf + buf_len, &msg_len)); + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( + ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, + buf, msg_len)); + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( + ssl, buf_len, msg_len)); + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) + if (mbedtls_ssl_tls13_key_exchange_mode_with_psk(ssl)) { + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_FINISHED); + } else { + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CERTIFICATE_REQUEST); + } +#else + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_FINISHED); +#endif + +cleanup: + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= write encrypted extensions")); + return ret; +} + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) +#define SSL_CERTIFICATE_REQUEST_SEND_REQUEST 0 +#define SSL_CERTIFICATE_REQUEST_SKIP 1 +/* Coordination: + * Check whether a CertificateRequest message should be written. + * Returns a negative code on failure, or + * - SSL_CERTIFICATE_REQUEST_SEND_REQUEST + * - SSL_CERTIFICATE_REQUEST_SKIP + * indicating if the writing of the CertificateRequest + * should be skipped or not. + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_certificate_request_coordinate(mbedtls_ssl_context *ssl) +{ + int authmode; + +#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) + if (ssl->handshake->sni_authmode != MBEDTLS_SSL_VERIFY_UNSET) { + authmode = ssl->handshake->sni_authmode; + } else +#endif + authmode = ssl->conf->authmode; + + if (authmode == MBEDTLS_SSL_VERIFY_NONE) { + ssl->session_negotiate->verify_result = MBEDTLS_X509_BADCERT_SKIP_VERIFY; + return SSL_CERTIFICATE_REQUEST_SKIP; + } + + ssl->handshake->certificate_request_sent = 1; + + return SSL_CERTIFICATE_REQUEST_SEND_REQUEST; +} + +/* + * struct { + * opaque certificate_request_context<0..2^8-1>; + * Extension extensions<2..2^16-1>; + * } CertificateRequest; + * + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_write_certificate_request_body(mbedtls_ssl_context *ssl, + unsigned char *buf, + const unsigned char *end, + size_t *out_len) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char *p = buf; + size_t output_len = 0; + unsigned char *p_extensions_len; + + *out_len = 0; + + /* Check if we have enough space: + * - certificate_request_context (1 byte) + * - extensions length (2 bytes) + */ + MBEDTLS_SSL_CHK_BUF_PTR(p, end, 3); + + /* + * Write certificate_request_context + */ + /* + * We use a zero length context for the normal handshake + * messages. For post-authentication handshake messages + * this request context would be set to a non-zero value. + */ + *p++ = 0x0; + + /* + * Write extensions + */ + /* The extensions must contain the signature_algorithms. */ + p_extensions_len = p; + p += 2; + ret = mbedtls_ssl_write_sig_alg_ext(ssl, p, end, &output_len); + if (ret != 0) { + return ret; + } + + p += output_len; + MBEDTLS_PUT_UINT16_BE(p - p_extensions_len - 2, p_extensions_len, 0); + + *out_len = p - buf; + + MBEDTLS_SSL_PRINT_EXTS( + 3, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, ssl->handshake->sent_extensions); + + return 0; +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_write_certificate_request(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> write certificate request")); + + MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_certificate_request_coordinate(ssl)); + + if (ret == SSL_CERTIFICATE_REQUEST_SEND_REQUEST) { + unsigned char *buf; + size_t buf_len, msg_len; + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( + ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, + &buf, &buf_len)); + + MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_certificate_request_body( + ssl, buf, buf + buf_len, &msg_len)); + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( + ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, + buf, msg_len)); + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( + ssl, buf_len, msg_len)); + } else if (ret == SSL_CERTIFICATE_REQUEST_SKIP) { + MBEDTLS_SSL_DEBUG_MSG(2, ("<= skip write certificate request")); + ret = 0; + } else { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; + goto cleanup; + } + + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_CERTIFICATE); +cleanup: + + MBEDTLS_SSL_DEBUG_MSG(2, ("<= write certificate request")); + return ret; +} + +/* + * Handler for MBEDTLS_SSL_SERVER_CERTIFICATE + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_write_server_certificate(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + +#if defined(MBEDTLS_X509_CRT_PARSE_C) + if ((ssl_tls13_pick_key_cert(ssl) != 0) || + mbedtls_ssl_own_cert(ssl) == NULL) { + MBEDTLS_SSL_DEBUG_MSG(2, ("No certificate available.")); + MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, + MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); + return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; + } +#endif /* MBEDTLS_X509_CRT_PARSE_C */ + + ret = mbedtls_ssl_tls13_write_certificate(ssl); + if (ret != 0) { + return ret; + } + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CERTIFICATE_VERIFY); + return 0; +} + +/* + * Handler for MBEDTLS_SSL_CERTIFICATE_VERIFY + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_write_certificate_verify(mbedtls_ssl_context *ssl) +{ + int ret = mbedtls_ssl_tls13_write_certificate_verify(ssl); + if (ret != 0) { + return ret; + } + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_SERVER_FINISHED); + return 0; +} +#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ + +/* + * RFC 8446 section A.2 + * + * | Send ServerHello + * | K_send = handshake + * | Send EncryptedExtensions + * | [Send CertificateRequest] + * Can send | [Send Certificate + CertificateVerify] + * app data | Send Finished + * after --> | K_send = application + * here +--------+--------+ + * No 0-RTT | | 0-RTT + * | | + * K_recv = handshake | | K_recv = early data + * [Skip decrypt errors] | +------> WAIT_EOED -+ + * | | Recv | | Recv EndOfEarlyData + * | | early data | | K_recv = handshake + * | +------------+ | + * | | + * +> WAIT_FLIGHT2 <--------+ + * | + * +--------+--------+ + * No auth | | Client auth + * | | + * | v + * | WAIT_CERT + * | Recv | | Recv Certificate + * | empty | v + * | Certificate | WAIT_CV + * | | | Recv + * | v | CertificateVerify + * +-> WAIT_FINISHED <---+ + * | Recv Finished + * + * + * The following function handles the state changes after WAIT_FLIGHT2 in the + * above diagram. We are not going to receive early data related messages + * anymore, prepare to receive the first handshake message of the client + * second flight. + */ +static void ssl_tls13_prepare_for_handshake_second_flight( + mbedtls_ssl_context *ssl) +{ + if (ssl->handshake->certificate_request_sent) { + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE); + } else { + MBEDTLS_SSL_DEBUG_MSG(2, ("skip parse certificate")); + MBEDTLS_SSL_DEBUG_MSG(2, ("skip parse certificate verify")); + + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_FINISHED); + } +} + +/* + * Handler for MBEDTLS_SSL_SERVER_FINISHED + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_write_server_finished(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + ret = mbedtls_ssl_tls13_write_finished_message(ssl); + if (ret != 0) { + return ret; + } + + ret = mbedtls_ssl_tls13_compute_application_transform(ssl); + if (ret != 0) { + MBEDTLS_SSL_PEND_FATAL_ALERT( + MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, + MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE); + return ret; + } + +#if defined(MBEDTLS_SSL_EARLY_DATA) + if (ssl->handshake->early_data_accepted) { + /* See RFC 8446 section A.2 for more information */ + MBEDTLS_SSL_DEBUG_MSG( + 1, ("Switch to early keys for inbound traffic. " + "( K_recv = early data )")); + mbedtls_ssl_set_inbound_transform( + ssl, ssl->handshake->transform_earlydata); + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_END_OF_EARLY_DATA); + return 0; + } +#endif /* MBEDTLS_SSL_EARLY_DATA */ + MBEDTLS_SSL_DEBUG_MSG( + 1, ("Switch to handshake keys for inbound traffic " + "( K_recv = handshake )")); + mbedtls_ssl_set_inbound_transform(ssl, ssl->handshake->transform_handshake); + + ssl_tls13_prepare_for_handshake_second_flight(ssl); + + return 0; +} + +#if defined(MBEDTLS_SSL_EARLY_DATA) +/* + * Handler for MBEDTLS_SSL_END_OF_EARLY_DATA + */ +#define SSL_GOT_END_OF_EARLY_DATA 0 +#define SSL_GOT_EARLY_DATA 1 +/* Coordination: + * Deals with the ambiguity of not knowing if the next message is an + * EndOfEarlyData message or an application message containing early data. + * Returns a negative code on failure, or + * - SSL_GOT_END_OF_EARLY_DATA + * - SSL_GOT_EARLY_DATA + * indicating which message is received. + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_end_of_early_data_coordinate(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + if ((ret = mbedtls_ssl_read_record(ssl, 0)) != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_read_record", ret); + return ret; + } + ssl->keep_current_message = 1; + + if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && + ssl->in_msg[0] == MBEDTLS_SSL_HS_END_OF_EARLY_DATA) { + MBEDTLS_SSL_DEBUG_MSG(3, ("Received an end_of_early_data message.")); + return SSL_GOT_END_OF_EARLY_DATA; + } + + if (ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA) { + if (ssl->in_offt == NULL) { + MBEDTLS_SSL_DEBUG_MSG(3, ("Received early data")); + /* Set the reading pointer */ + ssl->in_offt = ssl->in_msg; + ret = mbedtls_ssl_tls13_check_early_data_len(ssl, ssl->in_msglen); + if (ret != 0) { + return ret; + } + } + return SSL_GOT_EARLY_DATA; + } + + MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE, + MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE); + return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; +} + +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_parse_end_of_early_data(mbedtls_ssl_context *ssl, + const unsigned char *buf, + const unsigned char *end) +{ + /* RFC 8446 section 4.5 + * + * struct {} EndOfEarlyData; + */ + if (buf != end) { + MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, + MBEDTLS_ERR_SSL_DECODE_ERROR); + return MBEDTLS_ERR_SSL_DECODE_ERROR; + } + return 0; +} + +/* + * RFC 8446 section A.2 + * + * | Send ServerHello + * | K_send = handshake + * | Send EncryptedExtensions + * | [Send CertificateRequest] + * Can send | [Send Certificate + CertificateVerify] + * app data | Send Finished + * after --> | K_send = application + * here +--------+--------+ + * No 0-RTT | | 0-RTT + * | | + * K_recv = handshake | | K_recv = early data + * [Skip decrypt errors] | +------> WAIT_EOED -+ + * | | Recv | | Recv EndOfEarlyData + * | | early data | | K_recv = handshake + * | +------------+ | + * | | + * +> WAIT_FLIGHT2 <--------+ + * | + * +--------+--------+ + * No auth | | Client auth + * | | + * | v + * | WAIT_CERT + * | Recv | | Recv Certificate + * | empty | v + * | Certificate | WAIT_CV + * | | | Recv + * | v | CertificateVerify + * +-> WAIT_FINISHED <---+ + * | Recv Finished + * + * The function handles actions and state changes from 0-RTT to WAIT_FLIGHT2 in + * the above diagram. + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_process_end_of_early_data(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_tls13_process_end_of_early_data")); + + MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_end_of_early_data_coordinate(ssl)); + + if (ret == SSL_GOT_END_OF_EARLY_DATA) { + unsigned char *buf; + size_t buf_len; + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_tls13_fetch_handshake_msg( + ssl, MBEDTLS_SSL_HS_END_OF_EARLY_DATA, + &buf, &buf_len)); + + MBEDTLS_SSL_PROC_CHK(ssl_tls13_parse_end_of_early_data( + ssl, buf, buf + buf_len)); + + MBEDTLS_SSL_DEBUG_MSG( + 1, ("Switch to handshake keys for inbound traffic" + "( K_recv = handshake )")); + mbedtls_ssl_set_inbound_transform( + ssl, ssl->handshake->transform_handshake); + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( + ssl, MBEDTLS_SSL_HS_END_OF_EARLY_DATA, + buf, buf_len)); + + ssl_tls13_prepare_for_handshake_second_flight(ssl); + + } else if (ret == SSL_GOT_EARLY_DATA) { + ret = MBEDTLS_ERR_SSL_RECEIVED_EARLY_DATA; + goto cleanup; + } else { + MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); + ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; + goto cleanup; + } + +cleanup: + MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_tls13_process_end_of_early_data")); + return ret; +} +#endif /* MBEDTLS_SSL_EARLY_DATA */ + +/* + * Handler for MBEDTLS_SSL_CLIENT_FINISHED + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_process_client_finished(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + ret = mbedtls_ssl_tls13_process_finished_message(ssl); + if (ret != 0) { + return ret; + } + + ret = mbedtls_ssl_tls13_compute_resumption_master_secret(ssl); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET( + 1, "mbedtls_ssl_tls13_compute_resumption_master_secret", ret); + } + + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_WRAPUP); + return 0; +} + +/* + * Handler for MBEDTLS_SSL_HANDSHAKE_WRAPUP + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_handshake_wrapup(mbedtls_ssl_context *ssl) +{ + MBEDTLS_SSL_DEBUG_MSG(2, ("handshake: done")); + + mbedtls_ssl_tls13_handshake_wrapup(ssl); + +#if defined(MBEDTLS_SSL_SESSION_TICKETS) && \ + defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) +/* TODO: Remove the check of SOME_PSK_ENABLED since SESSION_TICKETS requires + * SOME_PSK_ENABLED to be enabled. Here is just to make CI happy. It is + * expected to be resolved with issue#6395. + */ + /* Sent NewSessionTicket message only when client supports PSK */ + if (mbedtls_ssl_tls13_is_some_psk_supported(ssl)) { + mbedtls_ssl_handshake_set_state( + ssl, MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET); + } else +#endif + { + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER); + } + return 0; +} + +/* + * Handler for MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET + */ +#define SSL_NEW_SESSION_TICKET_SKIP 0 +#define SSL_NEW_SESSION_TICKET_WRITE 1 +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_write_new_session_ticket_coordinate(mbedtls_ssl_context *ssl) +{ + /* Check whether the use of session tickets is enabled */ + if (ssl->conf->f_ticket_write == NULL) { + MBEDTLS_SSL_DEBUG_MSG(2, ("NewSessionTicket: disabled," + " callback is not set")); + return SSL_NEW_SESSION_TICKET_SKIP; + } + if (ssl->conf->new_session_tickets_count == 0) { + MBEDTLS_SSL_DEBUG_MSG(2, ("NewSessionTicket: disabled," + " configured count is zero")); + return SSL_NEW_SESSION_TICKET_SKIP; + } + + if (ssl->handshake->new_session_tickets_count == 0) { + MBEDTLS_SSL_DEBUG_MSG(2, ("NewSessionTicket: all tickets have " + "been sent.")); + return SSL_NEW_SESSION_TICKET_SKIP; + } + + return SSL_NEW_SESSION_TICKET_WRITE; +} + +#if defined(MBEDTLS_SSL_SESSION_TICKETS) +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_prepare_new_session_ticket(mbedtls_ssl_context *ssl, + unsigned char *ticket_nonce, + size_t ticket_nonce_size) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + mbedtls_ssl_session *session = ssl->session; + mbedtls_ssl_ciphersuite_t *ciphersuite_info; + psa_algorithm_t psa_hash_alg; + int hash_length; + + MBEDTLS_SSL_DEBUG_MSG(2, ("=> prepare NewSessionTicket msg")); + + /* Set ticket_flags depends on the advertised psk key exchange mode */ + mbedtls_ssl_tls13_session_clear_ticket_flags( + session, MBEDTLS_SSL_TLS1_3_TICKET_FLAGS_MASK); +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED) + mbedtls_ssl_tls13_session_set_ticket_flags( + session, ssl->handshake->tls13_kex_modes); +#endif + +#if defined(MBEDTLS_SSL_EARLY_DATA) + if (ssl->conf->early_data_enabled == MBEDTLS_SSL_EARLY_DATA_ENABLED && + ssl->conf->max_early_data_size > 0) { + mbedtls_ssl_tls13_session_set_ticket_flags( + session, MBEDTLS_SSL_TLS1_3_TICKET_ALLOW_EARLY_DATA); + session->max_early_data_size = ssl->conf->max_early_data_size; + } +#endif /* MBEDTLS_SSL_EARLY_DATA */ + + MBEDTLS_SSL_PRINT_TICKET_FLAGS(4, session->ticket_flags); + +#if defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_ALPN) + if (session->ticket_alpn == NULL) { + ret = mbedtls_ssl_session_set_ticket_alpn(session, ssl->alpn_chosen); + if (ret != 0) { + return ret; + } + } +#endif + + /* Generate ticket_age_add */ + if ((ret = ssl->conf->f_rng(ssl->conf->p_rng, + (unsigned char *) &session->ticket_age_add, + sizeof(session->ticket_age_add)) != 0)) { + MBEDTLS_SSL_DEBUG_RET(1, "generate_ticket_age_add", ret); + return ret; + } + MBEDTLS_SSL_DEBUG_MSG(3, ("ticket_age_add: %u", + (unsigned int) session->ticket_age_add)); + + /* Generate ticket_nonce */ + ret = ssl->conf->f_rng(ssl->conf->p_rng, ticket_nonce, ticket_nonce_size); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "generate_ticket_nonce", ret); + return ret; + } + MBEDTLS_SSL_DEBUG_BUF(3, "ticket_nonce:", + ticket_nonce, ticket_nonce_size); + + ciphersuite_info = + (mbedtls_ssl_ciphersuite_t *) ssl->handshake->ciphersuite_info; + psa_hash_alg = mbedtls_md_psa_alg_from_type((mbedtls_md_type_t) ciphersuite_info->mac); + hash_length = PSA_HASH_LENGTH(psa_hash_alg); + if (hash_length == -1 || + (size_t) hash_length > sizeof(session->resumption_key)) { + return MBEDTLS_ERR_SSL_INTERNAL_ERROR; + } + + /* In this code the psk key length equals the length of the hash */ + session->resumption_key_len = hash_length; + session->ciphersuite = ciphersuite_info->id; + + /* Compute resumption key + * + * HKDF-Expand-Label( resumption_master_secret, + * "resumption", ticket_nonce, Hash.length ) + */ + ret = mbedtls_ssl_tls13_hkdf_expand_label( + psa_hash_alg, + session->app_secrets.resumption_master_secret, + hash_length, + MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN(resumption), + ticket_nonce, + ticket_nonce_size, + session->resumption_key, + hash_length); + + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(2, + "Creating the ticket-resumed PSK failed", + ret); + return ret; + } + MBEDTLS_SSL_DEBUG_BUF(3, "Ticket-resumed PSK", + session->resumption_key, + session->resumption_key_len); + + MBEDTLS_SSL_DEBUG_BUF(3, "resumption_master_secret", + session->app_secrets.resumption_master_secret, + hash_length); + + return 0; +} + +/* This function creates a NewSessionTicket message in the following format: + * + * struct { + * uint32 ticket_lifetime; + * uint32 ticket_age_add; + * opaque ticket_nonce<0..255>; + * opaque ticket<1..2^16-1>; + * Extension extensions<0..2^16-2>; + * } NewSessionTicket; + * + * The ticket inside the NewSessionTicket message is an encrypted container + * carrying the necessary information so that the server is later able to + * re-start the communication. + * + * The following fields are placed inside the ticket by the + * f_ticket_write() function: + * + * - creation time (ticket_creation_time) + * - flags (ticket_flags) + * - age add (ticket_age_add) + * - key (resumption_key) + * - key length (resumption_key_len) + * - ciphersuite (ciphersuite) + * - max_early_data_size (max_early_data_size) + */ +MBEDTLS_CHECK_RETURN_CRITICAL +static int ssl_tls13_write_new_session_ticket_body(mbedtls_ssl_context *ssl, + unsigned char *buf, + unsigned char *end, + size_t *out_len, + unsigned char *ticket_nonce, + size_t ticket_nonce_size) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char *p = buf; + mbedtls_ssl_session *session = ssl->session; + size_t ticket_len; + uint32_t ticket_lifetime; + unsigned char *p_extensions_len; + + *out_len = 0; + MBEDTLS_SSL_DEBUG_MSG(2, ("=> write NewSessionTicket msg")); + + /* + * ticket_lifetime 4 bytes + * ticket_age_add 4 bytes + * ticket_nonce 1 + ticket_nonce_size bytes + * ticket >=2 bytes + */ + MBEDTLS_SSL_CHK_BUF_PTR(p, end, 4 + 4 + 1 + ticket_nonce_size + 2); + + /* Generate ticket and ticket_lifetime */ +#if defined(MBEDTLS_HAVE_TIME) + session->ticket_creation_time = mbedtls_ms_time(); +#endif + ret = ssl->conf->f_ticket_write(ssl->conf->p_ticket, + session, + p + 9 + ticket_nonce_size + 2, + end, + &ticket_len, + &ticket_lifetime); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "write_ticket", ret); + return ret; + } + + /* RFC 8446 section 4.6.1 + * + * ticket_lifetime: Indicates the lifetime in seconds as a 32-bit + * unsigned integer in network byte order from the time of ticket + * issuance. Servers MUST NOT use any value greater than + * 604800 seconds (7 days) ... + */ + if (ticket_lifetime > MBEDTLS_SSL_TLS1_3_MAX_ALLOWED_TICKET_LIFETIME) { + MBEDTLS_SSL_DEBUG_MSG( + 1, ("Ticket lifetime (%u) is greater than 7 days.", + (unsigned int) ticket_lifetime)); + return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + } + + MBEDTLS_PUT_UINT32_BE(ticket_lifetime, p, 0); + MBEDTLS_SSL_DEBUG_MSG(3, ("ticket_lifetime: %u", + (unsigned int) ticket_lifetime)); + + /* Write ticket_age_add */ + MBEDTLS_PUT_UINT32_BE(session->ticket_age_add, p, 4); + MBEDTLS_SSL_DEBUG_MSG(3, ("ticket_age_add: %u", + (unsigned int) session->ticket_age_add)); + + /* Write ticket_nonce */ + p[8] = (unsigned char) ticket_nonce_size; + if (ticket_nonce_size > 0) { + memcpy(p + 9, ticket_nonce, ticket_nonce_size); + } + p += 9 + ticket_nonce_size; + + /* Write ticket */ + MBEDTLS_PUT_UINT16_BE(ticket_len, p, 0); + p += 2; + MBEDTLS_SSL_DEBUG_BUF(4, "ticket", p, ticket_len); + p += ticket_len; + + /* Ticket Extensions + * + * Extension extensions<0..2^16-2>; + */ + ssl->handshake->sent_extensions = MBEDTLS_SSL_EXT_MASK_NONE; + + MBEDTLS_SSL_CHK_BUF_PTR(p, end, 2); + p_extensions_len = p; + p += 2; + +#if defined(MBEDTLS_SSL_EARLY_DATA) + if (mbedtls_ssl_tls13_session_ticket_allow_early_data(session)) { + size_t output_len; + + if ((ret = mbedtls_ssl_tls13_write_early_data_ext( + ssl, 1, p, end, &output_len)) != 0) { + MBEDTLS_SSL_DEBUG_RET( + 1, "mbedtls_ssl_tls13_write_early_data_ext", ret); + return ret; + } + p += output_len; + } else { + MBEDTLS_SSL_DEBUG_MSG( + 4, ("early_data not allowed, " + "skip early_data extension in NewSessionTicket")); + } + +#endif /* MBEDTLS_SSL_EARLY_DATA */ + + MBEDTLS_PUT_UINT16_BE(p - p_extensions_len - 2, p_extensions_len, 0); + + *out_len = p - buf; + MBEDTLS_SSL_DEBUG_BUF(4, "ticket", buf, *out_len); + MBEDTLS_SSL_DEBUG_MSG(2, ("<= write new session ticket")); + + MBEDTLS_SSL_PRINT_EXTS( + 3, MBEDTLS_SSL_HS_NEW_SESSION_TICKET, ssl->handshake->sent_extensions); + + return 0; +} + +/* + * Handler for MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET + */ +static int ssl_tls13_write_new_session_ticket(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + MBEDTLS_SSL_PROC_CHK_NEG(ssl_tls13_write_new_session_ticket_coordinate(ssl)); + + if (ret == SSL_NEW_SESSION_TICKET_WRITE) { + unsigned char ticket_nonce[MBEDTLS_SSL_TLS1_3_TICKET_NONCE_LENGTH]; + unsigned char *buf; + size_t buf_len, msg_len; + + MBEDTLS_SSL_PROC_CHK(ssl_tls13_prepare_new_session_ticket( + ssl, ticket_nonce, sizeof(ticket_nonce))); + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_start_handshake_msg( + ssl, MBEDTLS_SSL_HS_NEW_SESSION_TICKET, + &buf, &buf_len)); + + MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_new_session_ticket_body( + ssl, buf, buf + buf_len, &msg_len, + ticket_nonce, sizeof(ticket_nonce))); + + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg( + ssl, buf_len, msg_len)); + + /* Limit session tickets count to one when resumption connection. + * + * See document of mbedtls_ssl_conf_new_session_tickets. + */ + if (ssl->handshake->resume == 1) { + ssl->handshake->new_session_tickets_count = 0; + } else { + ssl->handshake->new_session_tickets_count--; + } + + mbedtls_ssl_handshake_set_state( + ssl, MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET_FLUSH); + } else { + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER); + } + +cleanup: + + return ret; +} +#endif /* MBEDTLS_SSL_SESSION_TICKETS */ + +/* + * TLS 1.3 State Machine -- server side + */ +int mbedtls_ssl_tls13_handshake_server_step(mbedtls_ssl_context *ssl) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + if (ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER || ssl->handshake == NULL) { + return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; + } + + MBEDTLS_SSL_DEBUG_MSG(2, ("tls13 server state: %s(%d)", + mbedtls_ssl_states_str((mbedtls_ssl_states) ssl->state), + ssl->state)); + + switch (ssl->state) { + /* start state */ + case MBEDTLS_SSL_HELLO_REQUEST: + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO); + ret = 0; + break; + + case MBEDTLS_SSL_CLIENT_HELLO: + ret = ssl_tls13_process_client_hello(ssl); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_process_client_hello", ret); + } + break; + + case MBEDTLS_SSL_HELLO_RETRY_REQUEST: + ret = ssl_tls13_write_hello_retry_request(ssl); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_write_hello_retry_request", ret); + return ret; + } + break; + + case MBEDTLS_SSL_SERVER_HELLO: + ret = ssl_tls13_write_server_hello(ssl); + break; + + case MBEDTLS_SSL_ENCRYPTED_EXTENSIONS: + ret = ssl_tls13_write_encrypted_extensions(ssl); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, "ssl_tls13_write_encrypted_extensions", ret); + return ret; + } + break; + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) + case MBEDTLS_SSL_CERTIFICATE_REQUEST: + ret = ssl_tls13_write_certificate_request(ssl); + break; + + case MBEDTLS_SSL_SERVER_CERTIFICATE: + ret = ssl_tls13_write_server_certificate(ssl); + break; + + case MBEDTLS_SSL_CERTIFICATE_VERIFY: + ret = ssl_tls13_write_certificate_verify(ssl); + break; +#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ + + /* + * Injection of dummy-CCS's for middlebox compatibility + */ +#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) + case MBEDTLS_SSL_SERVER_CCS_AFTER_HELLO_RETRY_REQUEST: + ret = mbedtls_ssl_tls13_write_change_cipher_spec(ssl); + if (ret == 0) { + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_CLIENT_HELLO); + } + break; + + case MBEDTLS_SSL_SERVER_CCS_AFTER_SERVER_HELLO: + ret = mbedtls_ssl_tls13_write_change_cipher_spec(ssl); + if (ret != 0) { + break; + } + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS); + break; +#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ + + case MBEDTLS_SSL_SERVER_FINISHED: + ret = ssl_tls13_write_server_finished(ssl); + break; + +#if defined(MBEDTLS_SSL_EARLY_DATA) + case MBEDTLS_SSL_END_OF_EARLY_DATA: + ret = ssl_tls13_process_end_of_early_data(ssl); + break; +#endif /* MBEDTLS_SSL_EARLY_DATA */ + + case MBEDTLS_SSL_CLIENT_FINISHED: + ret = ssl_tls13_process_client_finished(ssl); + break; + + case MBEDTLS_SSL_HANDSHAKE_WRAPUP: + ret = ssl_tls13_handshake_wrapup(ssl); + break; + +#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED) + case MBEDTLS_SSL_CLIENT_CERTIFICATE: + ret = mbedtls_ssl_tls13_process_certificate(ssl); + if (ret == 0) { + if (ssl->session_negotiate->peer_cert != NULL) { + mbedtls_ssl_handshake_set_state( + ssl, MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY); + } else { + MBEDTLS_SSL_DEBUG_MSG(2, ("skip parse certificate verify")); + mbedtls_ssl_handshake_set_state( + ssl, MBEDTLS_SSL_CLIENT_FINISHED); + } + } + break; + + case MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY: + ret = mbedtls_ssl_tls13_process_certificate_verify(ssl); + if (ret == 0) { + mbedtls_ssl_handshake_set_state( + ssl, MBEDTLS_SSL_CLIENT_FINISHED); + } + break; +#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */ + +#if defined(MBEDTLS_SSL_SESSION_TICKETS) + case MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET: + ret = ssl_tls13_write_new_session_ticket(ssl); + if (ret != 0) { + MBEDTLS_SSL_DEBUG_RET(1, + "ssl_tls13_write_new_session_ticket ", + ret); + } + break; + case MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET_FLUSH: + /* This state is necessary to do the flush of the New Session + * Ticket message written in MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET + * as part of ssl_prepare_handshake_step. + */ + ret = 0; + + if (ssl->handshake->new_session_tickets_count == 0) { + mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HANDSHAKE_OVER); + } else { + mbedtls_ssl_handshake_set_state( + ssl, MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET); + } + break; + +#endif /* MBEDTLS_SSL_SESSION_TICKETS */ + + default: + MBEDTLS_SSL_DEBUG_MSG(1, ("invalid state %d", ssl->state)); + return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE; + } + + return ret; +} + +#endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_PROTO_TLS1_3 */ |