/*
* Copyright (C) 2017-2018 Free Software Foundation, Inc.
* Copyright (C) 2018 Red Hat, Inc.
*
* Author: Ander Juaristi, Nikos Mavrogiannopoulos
*
* This file is part of GnuTLS.
*
* The GnuTLS is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>
*
*/
#include "gnutls_int.h"
#include "auth/psk.h"
#include "handshake.h"
#include "kx.h"
#include "secrets.h"
#include "tls13/anti_replay.h"
#include "tls13/psk_ext_parser.h"
#include "tls13/finished.h"
#include "tls13/session_ticket.h"
#include "auth/psk_passwd.h"
#include <ext/session_ticket.h>
#include <ext/pre_shared_key.h>
#include <assert.h>
static int
compute_psk_from_ticket(const tls13_ticket_st *ticket, gnutls_datum_t *key)
{
int ret;
if (unlikely(ticket->prf == NULL || ticket->prf->output_size == 0))
return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);
key->data = gnutls_malloc(ticket->prf->output_size);
if (!key->data) {
gnutls_assert();
return GNUTLS_E_MEMORY_ERROR;
}
key->size = ticket->prf->output_size;
ret = _tls13_expand_secret2(ticket->prf,
RESUMPTION_LABEL, sizeof(RESUMPTION_LABEL)-1,
ticket->nonce, ticket->nonce_size,
ticket->resumption_master_secret,
key->size,
key->data);
if (ret < 0)
gnutls_assert();
return ret;
}
static int
compute_binder_key(const mac_entry_st *prf,
const uint8_t *key, size_t keylen,
bool resuming,
void *out)
{
int ret;
const char ext_label[] = EXT_BINDER_LABEL;
const size_t ext_label_len = sizeof(ext_label) - 1;
const char res_label[] = RES_BINDER_LABEL;
const size_t res_label_len = sizeof(res_label) - 1;
const char *label = resuming ? res_label : ext_label;
size_t label_len = resuming ? res_label_len : ext_label_len;
uint8_t tmp_key[MAX_HASH_SIZE];
/* Compute HKDF-Extract(0, psk) */
ret = _tls13_init_secret2(prf, key, keylen, tmp_key);
if (ret < 0)
return ret;
/* Compute Derive-Secret(secret, label, transcript_hash) */
ret = _tls13_derive_secret2(prf, label, label_len,
NULL, 0, tmp_key, out);
if (ret < 0)
return ret;
return 0;
}
static int
compute_psk_binder(gnutls_session_t session,
const mac_entry_st *prf, unsigned binders_length,
int exts_length, int ext_offset,
const gnutls_datum_t *psk, const gnutls_datum_t *client_hello,
bool resuming, void *out)
{
int ret;
unsigned client_hello_pos, extensions_len_pos;
gnutls_buffer_st handshake_buf;
uint8_t binder_key[MAX_HASH_SIZE];
_gnutls_buffer_init(&handshake_buf);
if (session->security_parameters.entity == GNUTLS_CLIENT) {
if (session->internals.hsk_flags & HSK_HRR_RECEIVED) {
ret = gnutls_buffer_append_data(&handshake_buf,
(const void *) session->internals.handshake_hash_buffer.data,
session->internals.handshake_hash_buffer.length);
if (ret < 0) {
gnutls_assert();
goto error;
}
}
client_hello_pos = handshake_buf.length;
ret = gnutls_buffer_append_data(&handshake_buf, client_hello->data,
client_hello->size);
if (ret < 0) {
gnutls_assert();
goto error;
}
/* This is a ClientHello message */
handshake_buf.data[client_hello_pos] = GNUTLS_HANDSHAKE_CLIENT_HELLO;
/* At this point we have not yet added the binders to the ClientHello,
* but we have to overwrite the size field, pretending as if binders
* of the correct length were present.
*/
_gnutls_write_uint24(handshake_buf.length - client_hello_pos + binders_length - 2, &handshake_buf.data[client_hello_pos + 1]);
_gnutls_write_uint16(handshake_buf.length - client_hello_pos + binders_length - ext_offset,
&handshake_buf.data[client_hello_pos + ext_offset]);
extensions_len_pos = handshake_buf.length - client_hello_pos - exts_length - 2;
_gnutls_write_uint16(exts_length + binders_length + 2,
&handshake_buf.data[client_hello_pos + extensions_len_pos]);
} else {
if (session->internals.hsk_flags & HSK_HRR_SENT) {
if (unlikely(session->internals.handshake_hash_buffer.length <= client_hello->size)) {
ret = gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);
goto error;
}
ret = gnutls_buffer_append_data(&handshake_buf,
session->internals.handshake_hash_buffer.data,
session->internals.handshake_hash_buffer.length - client_hello->size);
if (ret < 0) {
gnutls_assert();
goto error;
}
}
if (unlikely(client_hello->size <= binders_length)) {
ret = gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);
goto error;
}
ret = gnutls_buffer_append_data(&handshake_buf,
(const void *) client_hello->data,
client_hello->size - binders_length);
if (ret < 0) {
gnutls_assert();
goto error;
}
}
ret = compute_binder_key(prf,
psk->data, psk->size, resuming,
binder_key);
if (ret < 0) {
gnutls_assert();
goto error;
}
ret = _gnutls13_compute_finished(prf, binder_key,
&handshake_buf,
out);
if (ret < 0) {
gnutls_assert();
goto error;
}
ret = 0;
error:
_gnutls_buffer_clear(&handshake_buf);
return ret;
}
static int
generate_early_secrets(gnutls_session_t session,
const mac_entry_st *prf)
{
int ret;
ret = _tls13_derive_secret2(prf, EARLY_TRAFFIC_LABEL, sizeof(EARLY_TRAFFIC_LABEL)-1,
session->internals.handshake_hash_buffer.data,
session->internals.handshake_hash_buffer_client_hello_len,
session->key.proto.tls13.temp_secret,
session->key.proto.tls13.e_ckey);
if (ret < 0)
return gnutls_assert_val(ret);
ret = _gnutls_call_keylog_func(session, "CLIENT_EARLY_TRAFFIC_SECRET",
session->key.proto.tls13.e_ckey,
prf->output_size);
if (ret < 0)
return gnutls_assert_val(ret);
ret = _tls13_derive_secret2(prf, EARLY_EXPORTER_MASTER_LABEL, sizeof(EARLY_EXPORTER_MASTER_LABEL)-1,
session->internals.handshake_hash_buffer.data,
session->internals.handshake_hash_buffer_client_hello_len,
session->key.proto.tls13.temp_secret,
session->key.proto.tls13.ap_expkey);
if (ret < 0)
return gnutls_assert_val(ret);
ret = _gnutls_call_keylog_func(session, "EARLY_EXPORTER_SECRET",
session->key.proto.tls13.ap_expkey,
prf->output_size);
if (ret < 0)
return gnutls_assert_val(ret);
return 0;
}
/* Calculate TLS 1.3 Early Secret and the derived secrets from the
* selected PSK. */
int
_gnutls_generate_early_secrets_for_psk(gnutls_session_t session)
{
const uint8_t *psk;
size_t psk_size;
const mac_entry_st *prf;
int ret;
psk = session->key.binders[0].psk.data;
psk_size = session->key.binders[0].psk.size;
prf = session->key.binders[0].prf;
if (unlikely(psk_size == 0))
return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
ret = _tls13_init_secret2(prf, psk, psk_size,
session->key.proto.tls13.temp_secret);
if (ret < 0)
return gnutls_assert_val(ret);
session->key.proto.tls13.temp_secret_size = prf->output_size;
ret = generate_early_secrets(session, session->key.binders[0].prf);
if (ret < 0)
return gnutls_assert_val(ret);
return 0;
}
static int
client_send_params(gnutls_session_t session,
gnutls_buffer_t extdata,
const gnutls_psk_client_credentials_t cred)
{
int ret, ext_offset = 0;
uint8_t binder_value[MAX_HASH_SIZE];
size_t spos;
gnutls_datum_t username = {NULL, 0};
gnutls_datum_t user_key = {NULL, 0}, rkey = {NULL, 0};
gnutls_datum_t client_hello;
unsigned next_idx;
const mac_entry_st *prf_res = NULL;
const mac_entry_st *prf_psk = NULL;
struct timespec cur_time;
uint32_t ticket_age, ob_ticket_age;
int free_username = 0;
psk_auth_info_t info = NULL;
unsigned psk_id_len = 0;
unsigned binders_len, binders_pos;
if (((session->internals.flags & GNUTLS_NO_TICKETS) ||
session->internals.tls13_ticket.ticket.data == NULL) &&
(!cred || !_gnutls_have_psk_credentials(cred, session))) {
return 0;
}
binders_len = 0;
/* placeholder to be filled later */
spos = extdata->length;
ret = _gnutls_buffer_append_prefix(extdata, 16, 0);
if (ret < 0)
return gnutls_assert_val(ret);
/* First, let's see if we have a session ticket to send */
if (!(session->internals.flags & GNUTLS_NO_TICKETS) &&
session->internals.tls13_ticket.ticket.data != NULL) {
/* We found a session ticket */
if (unlikely(session->internals.tls13_ticket.prf == NULL)) {
_gnutls13_session_ticket_unset(session);
ret = gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);
goto cleanup;
}
prf_res = session->internals.tls13_ticket.prf;
gnutls_gettime(&cur_time);
if (unlikely(_gnutls_timespec_cmp(&cur_time,
&session->internals.
tls13_ticket.
arrival_time) < 0)) {
gnutls_assert();
_gnutls13_session_ticket_unset(session);
goto ignore_ticket;
}
/* Check whether the ticket is stale */
ticket_age = timespec_sub_ms(&cur_time,
&session->internals.tls13_ticket.
arrival_time);
if (ticket_age / 1000 > session->internals.tls13_ticket.lifetime) {
_gnutls13_session_ticket_unset(session);
goto ignore_ticket;
}
ret = compute_psk_from_ticket(&session->internals.tls13_ticket, &rkey);
if (ret < 0) {
_gnutls13_session_ticket_unset(session);
goto ignore_ticket;
}
/* Calculate obfuscated ticket age, in milliseconds, mod 2^32 */
ob_ticket_age = ticket_age + session->internals.tls13_ticket.age_add;
if ((ret = _gnutls_buffer_append_data_prefix(extdata, 16,
session->internals.tls13_ticket.ticket.data,
session->internals.tls13_ticket.ticket.size)) < 0) {
gnutls_assert();
goto cleanup;
}
/* Now append the obfuscated ticket age */
if ((ret = _gnutls_buffer_append_prefix(extdata, 32, ob_ticket_age)) < 0) {
gnutls_assert();
goto cleanup;
}
psk_id_len += 6 + session->internals.tls13_ticket.ticket.size;
binders_len += 1 + _gnutls_mac_get_algo_len(prf_res);
}
ignore_ticket:
if (cred && _gnutls_have_psk_credentials(cred, session)) {
gnutls_datum_t tkey;
if (cred->binder_algo == NULL) {
gnutls_assert();
ret = gnutls_assert_val(GNUTLS_E_INSUFFICIENT_CREDENTIALS);
goto cleanup;
}
prf_psk = cred->binder_algo;
ret = _gnutls_find_psk_key(session, cred, &username, &tkey, &free_username);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
if (username.size == 0 || username.size > UINT16_MAX) {
ret = gnutls_assert_val(GNUTLS_E_INVALID_PASSWORD);
goto cleanup;
}
if (!free_username) {
/* we need to copy the key */
ret = _gnutls_set_datum(&user_key, tkey.data, tkey.size);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
} else {
user_key.data = tkey.data;
user_key.size = tkey.size;
}
ret = _gnutls_auth_info_init(session, GNUTLS_CRD_PSK, sizeof(psk_auth_info_st), 1);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
info = _gnutls_get_auth_info(session, GNUTLS_CRD_PSK);
assert(info != NULL);
_gnutls_copy_psk_username(info, &username);
if ((ret = _gnutls_buffer_append_data_prefix(extdata, 16,
username.data,
username.size)) < 0) {
gnutls_assert();
goto cleanup;
}
/* Now append the obfuscated ticket age */
if ((ret = _gnutls_buffer_append_prefix(extdata, 32, 0)) < 0) {
gnutls_assert();
goto cleanup;
}
psk_id_len += 6 + username.size;
binders_len += 1 + _gnutls_mac_get_algo_len(prf_psk);
}
/* if no tickets or identities to be sent */
if (psk_id_len == 0) {
/* reset extensions buffer */
extdata->length = spos;
return 0;
}
_gnutls_write_uint16(psk_id_len, &extdata->data[spos]);
binders_pos = extdata->length-spos;
ext_offset = _gnutls_ext_get_extensions_offset(session);
/* Compute the binders. extdata->data points to the start
* of this client hello. */
assert(extdata->length >= sizeof(mbuffer_st));
assert(ext_offset >= (ssize_t)sizeof(mbuffer_st));
ext_offset -= sizeof(mbuffer_st);
client_hello.data = extdata->data+sizeof(mbuffer_st);
client_hello.size = extdata->length-sizeof(mbuffer_st);
next_idx = 0;
ret = _gnutls_buffer_append_prefix(extdata, 16, binders_len);
if (ret < 0) {
gnutls_assert_val(ret);
goto cleanup;
}
if (prf_res && rkey.size > 0) {
ret = compute_psk_binder(session, prf_res,
binders_len, binders_pos,
ext_offset, &rkey, &client_hello, 1,
binder_value);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
/* Associate the selected pre-shared key with the session */
gnutls_free(session->key.binders[next_idx].psk.data);
session->key.binders[next_idx].psk.data = rkey.data;
session->key.binders[next_idx].psk.size = rkey.size;
rkey.data = NULL;
session->key.binders[next_idx].prf = prf_res;
session->key.binders[next_idx].resumption = 1;
session->key.binders[next_idx].idx = next_idx;
_gnutls_handshake_log("EXT[%p]: sent PSK resumption identity (%d)\n", session, next_idx);
next_idx++;
/* Add the binder */
ret = _gnutls_buffer_append_data_prefix(extdata, 8, binder_value, prf_res->output_size);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
session->internals.hsk_flags |= HSK_TLS13_TICKET_SENT;
}
if (prf_psk && user_key.size > 0 && info) {
ret = compute_psk_binder(session, prf_psk,
binders_len, binders_pos,
ext_offset, &user_key, &client_hello, 0,
binder_value);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
/* Associate the selected pre-shared key with the session */
gnutls_free(session->key.binders[next_idx].psk.data);
session->key.binders[next_idx].psk.data = user_key.data;
session->key.binders[next_idx].psk.size = user_key.size;
user_key.data = NULL;
session->key.binders[next_idx].prf = prf_psk;
session->key.binders[next_idx].resumption = 0;
session->key.binders[next_idx].idx = next_idx;
_gnutls_handshake_log("EXT[%p]: sent PSK identity '%s' (%d)\n", session, info->username, next_idx);
next_idx++;
/* Add the binder */
ret = _gnutls_buffer_append_data_prefix(extdata, 8, binder_value, prf_psk->output_size);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
}
ret = 0;
cleanup:
if (free_username)
_gnutls_free_datum(&username);
_gnutls_free_temp_key_datum(&user_key);
_gnutls_free_temp_key_datum(&rkey);
return ret;
}
static int
server_send_params(gnutls_session_t session, gnutls_buffer_t extdata)
{
int ret;
if (!(session->internals.hsk_flags & HSK_PSK_SELECTED))
return 0;
ret = _gnutls_buffer_append_prefix(extdata, 16,
session->key.binders[0].idx);
if (ret < 0)
return gnutls_assert_val(ret);
return 2;
}
static int server_recv_params(gnutls_session_t session,
const unsigned char *data, size_t len,
const gnutls_psk_server_credentials_t pskcred)
{
int ret;
const mac_entry_st *prf;
gnutls_datum_t full_client_hello;
uint8_t binder_value[MAX_HASH_SIZE];
uint16_t psk_index, i;
gnutls_datum_t binder_recvd = { NULL, 0 };
gnutls_datum_t key = {NULL, 0};
psk_ext_parser_st psk_parser;
psk_ext_iter_st psk_iter;
struct psk_st psk;
psk_auth_info_t info;
tls13_ticket_st ticket_data;
/* These values should be set properly when session ticket is accepted. */
uint32_t ticket_age = UINT32_MAX;
struct timespec ticket_creation_time = { 0, 0 };
bool resuming;
ret = _gnutls13_psk_ext_parser_init(&psk_parser, data, len);
if (ret < 0) {
/* No PSKs advertised by client */
if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
return 0;
return gnutls_assert_val(ret);
}
_gnutls13_psk_ext_iter_init(&psk_iter, &psk_parser);
for (psk_index = 0; ; psk_index++) {
ret = _gnutls13_psk_ext_iter_next_identity(&psk_iter, &psk);
if (ret < 0) {
/* We couldn't find any usable PSK */
if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
return 0;
return gnutls_assert_val(ret);
}
/* This will unpack the session ticket if it is well
* formed and has the expected name */
if (!(session->internals.flags & GNUTLS_NO_TICKETS) &&
(ret = _gnutls13_unpack_session_ticket(session, &psk.identity, &ticket_data)) == 0) {
prf = ticket_data.prf;
session->internals.resumption_requested = 1;
/* Check whether ticket is stale or not */
ticket_age = psk.ob_ticket_age - ticket_data.age_add;
if (ticket_age / 1000 > ticket_data.lifetime) {
gnutls_assert();
tls13_ticket_deinit(&ticket_data);
continue;
}
ret = compute_psk_from_ticket(&ticket_data, &key);
if (ret < 0) {
gnutls_assert();
tls13_ticket_deinit(&ticket_data);
continue;
}
memcpy(&ticket_creation_time,
&ticket_data.creation_time,
sizeof(struct timespec));
tls13_ticket_deinit(&ticket_data);
resuming = 1;
break;
} else if (pskcred &&
psk.ob_ticket_age == 0 &&
psk.identity.size > 0 && psk.identity.size <= MAX_USERNAME_SIZE) {
prf = pskcred->binder_algo;
/* this fails only on configuration errors; as such we always
* return its error code in that case */
ret = _gnutls_psk_pwd_find_entry(session, (char *) psk.identity.data, psk.identity.size, &key);
if (ret < 0)
return gnutls_assert_val(ret);
resuming = 0;
break;
}
}
_gnutls13_psk_ext_iter_init(&psk_iter, &psk_parser);
for (i = 0; i <= psk_index; i++) {
ret = _gnutls13_psk_ext_iter_next_binder(&psk_iter, &binder_recvd);
if (ret < 0) {
gnutls_assert();
/* We couldn't extract binder */
if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
ret = GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
goto fail;
}
}
/* Get full ClientHello */
if (!_gnutls_ext_get_full_client_hello(session, &full_client_hello)) {
ret = GNUTLS_E_INTERNAL_ERROR;
gnutls_assert();
goto fail;
}
/* Compute the binder value for this PSK */
ret = compute_psk_binder(session, prf, psk_parser.binders_len+2, 0, 0,
&key, &full_client_hello, resuming,
binder_value);
if (ret < 0) {
gnutls_assert();
goto fail;
}
if (_gnutls_mac_get_algo_len(prf) != binder_recvd.size ||
gnutls_memcmp(binder_value, binder_recvd.data, binder_recvd.size)) {
gnutls_assert();
ret = GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
goto fail;
}
if (session->internals.hsk_flags & HSK_PSK_KE_MODE_DHE_PSK)
_gnutls_handshake_log("EXT[%p]: selected DHE-PSK mode\n", session);
else {
reset_cand_groups(session);
_gnutls_handshake_log("EXT[%p]: selected PSK mode\n", session);
}
/* save the username in psk_auth_info to make it available
* using gnutls_psk_server_get_username() */
if (!resuming) {
assert(psk.identity.size < sizeof(info->username));
ret = _gnutls_auth_info_init(session, GNUTLS_CRD_PSK, sizeof(psk_auth_info_st), 1);
if (ret < 0) {
gnutls_assert();
goto fail;
}
info = _gnutls_get_auth_info(session, GNUTLS_CRD_PSK);
assert(info != NULL);
_gnutls_copy_psk_username(info, &psk.identity);
_gnutls_handshake_log("EXT[%p]: selected PSK identity: %s (%d)\n", session, info->username, psk_index);
} else {
if (session->internals.hsk_flags & HSK_EARLY_DATA_ACCEPTED) {
if (session->internals.anti_replay) {
ret = _gnutls_anti_replay_check(session->internals.anti_replay,
ticket_age,
&ticket_creation_time,
&binder_recvd);
if (ret < 0) {
session->internals.hsk_flags &= ~HSK_EARLY_DATA_ACCEPTED;
_gnutls_handshake_log("EXT[%p]: replay detected; rejecting early data\n",
session);
}
} else {
_gnutls_handshake_log("EXT[%p]: anti-replay is not enabled; rejecting early data\n",
session);
session->internals.hsk_flags &= ~HSK_EARLY_DATA_ACCEPTED;
}
}
session->internals.resumed = RESUME_TRUE;
_gnutls_handshake_log("EXT[%p]: selected resumption PSK identity (%d)\n", session, psk_index);
}
session->internals.hsk_flags |= HSK_PSK_SELECTED;
/* Reference the selected pre-shared key */
session->key.binders[0].psk.data = key.data;
session->key.binders[0].psk.size = key.size;
session->key.binders[0].idx = psk_index;
session->key.binders[0].prf = prf;
session->key.binders[0].resumption = resuming;
ret = _gnutls_generate_early_secrets_for_psk(session);
if (ret < 0) {
gnutls_assert();
goto fail;
}
return 0;
fail:
gnutls_free(key.data);
return ret;
}
/*
* Return values for this function:
* - 0 : Not applicable.
* - >0 : Ok. Return size of extension data.
* - GNUTLS_E_INT_RET_0 : Size of extension data is zero.
* - <0 : There's been an error.
*
* In the client, generates the PskIdentity and PskBinderEntry messages.
*
* PskIdentity identities<7..2^16-1>;
* PskBinderEntry binders<33..2^16-1>;
*
* struct {
* opaque identity<1..2^16-1>;
* uint32 obfuscated_ticket_age;
* } PskIdentity;
*
* opaque PskBinderEntry<32..255>;
*
* The server sends the selected identity, which is a zero-based index
* of the PSKs offered by the client:
*
* struct {
* uint16 selected_identity;
* } PreSharedKeyExtension;
*/
static int _gnutls_psk_send_params(gnutls_session_t session,
gnutls_buffer_t extdata)
{
gnutls_psk_client_credentials_t cred = NULL;
const version_entry_st *vers;
if (session->security_parameters.entity == GNUTLS_CLIENT) {
vers = _gnutls_version_max(session);
if (!vers || !vers->tls13_sem)
return 0;
if (session->internals.hsk_flags & HSK_PSK_KE_MODES_SENT) {
cred = (gnutls_psk_client_credentials_t)
_gnutls_get_cred(session, GNUTLS_CRD_PSK);
}
if ((session->internals.flags & GNUTLS_NO_TICKETS) && !session->internals.priorities->have_psk)
return 0;
return client_send_params(session, extdata, cred);
} else {
vers = get_version(session);
if (!vers || !vers->tls13_sem)
return 0;
if ((session->internals.flags & GNUTLS_NO_TICKETS) && !session->internals.priorities->have_psk)
return 0;
if (session->internals.hsk_flags & HSK_PSK_KE_MODES_RECEIVED)
return server_send_params(session, extdata);
else
return 0;
}
}
static void swap_binders(gnutls_session_t session)
{
struct binder_data_st tmp;
memcpy(&tmp, &session->key.binders[0], sizeof(struct binder_data_st));
memcpy(&session->key.binders[0], &session->key.binders[1], sizeof(struct binder_data_st));
memcpy(&session->key.binders[1], &tmp, sizeof(struct binder_data_st));
}
/*
* Return values for this function:
* - 0 : Not applicable.
* - >0 : Ok. Return size of extension data.
* - <0 : There's been an error.
*/
static int _gnutls_psk_recv_params(gnutls_session_t session,
const unsigned char *data, size_t len)
{
unsigned i;
gnutls_psk_server_credentials_t pskcred;
const version_entry_st *vers = get_version(session);
int ret;
if (!vers || !vers->tls13_sem)
return 0;
if (session->security_parameters.entity == GNUTLS_CLIENT) {
if (session->internals.hsk_flags & HSK_PSK_KE_MODES_SENT) {
uint16_t selected_identity = _gnutls_read_uint16(data);
for (i=0;i<sizeof(session->key.binders)/sizeof(session->key.binders[0]);i++) {
if (session->key.binders[i].prf != NULL && session->key.binders[i].idx == selected_identity) {
if (session->key.binders[i].resumption) {
session->internals.resumed = RESUME_TRUE;
_gnutls_handshake_log("EXT[%p]: selected PSK-resumption mode\n", session);
} else {
_gnutls_handshake_log("EXT[%p]: selected PSK mode\n", session);
}
/* different PSK is selected, than the one we calculated early secrets */
if (i != 0) {
/* ensure that selected binder is set on (our) index zero */
swap_binders(session);
ret = _gnutls_generate_early_secrets_for_psk(session);
if (ret < 0)
return gnutls_assert_val(ret);
}
session->internals.hsk_flags |= HSK_PSK_SELECTED;
}
}
return 0;
} else {
return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_EXTENSION);
}
} else {
if (session->internals.hsk_flags & HSK_PSK_KE_MODES_RECEIVED) {
if (session->internals.hsk_flags & HSK_PSK_KE_MODE_INVALID) {
/* We received a "psk_ke_modes" extension, but with a value we don't support */
return 0;
}
pskcred = (gnutls_psk_server_credentials_t)
_gnutls_get_cred(session, GNUTLS_CRD_PSK);
/* If there are no PSK credentials, this extension is not applicable,
* so we return zero. */
if (pskcred == NULL && (session->internals.flags & GNUTLS_NO_TICKETS))
return 0;
return server_recv_params(session, data, len, pskcred);
} else {
return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_EXTENSION);
}
}
}
const hello_ext_entry_st ext_mod_pre_shared_key = {
.name = "Pre Shared Key",
.tls_id = PRE_SHARED_KEY_TLS_ID,
.gid = GNUTLS_EXTENSION_PRE_SHARED_KEY,
.client_parse_point = GNUTLS_EXT_TLS,
.server_parse_point = GNUTLS_EXT_TLS,
.validity = GNUTLS_EXT_FLAG_TLS | GNUTLS_EXT_FLAG_CLIENT_HELLO | GNUTLS_EXT_FLAG_TLS13_SERVER_HELLO,
.send_func = _gnutls_psk_send_params,
.recv_func = _gnutls_psk_recv_params
};