384 lines
11 KiB
C
384 lines
11 KiB
C
/*
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* DTLS cookie callbacks implementation
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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* These session callbacks use a simple chained list
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* to store and retrieve the session information.
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*/
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#include "common.h"
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#if defined(MBEDTLS_SSL_COOKIE_C)
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#include "mbedtls/platform.h"
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#include "mbedtls/ssl_cookie.h"
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#include "ssl_misc.h"
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#include "mbedtls/error.h"
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#include "mbedtls/platform_util.h"
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#include "mbedtls/constant_time.h"
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#include "mbedtls/legacy_or_psa.h"
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#include <string.h>
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/*
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* If DTLS is in use, then at least one of SHA-256 or SHA-384 is
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* available. Try SHA-256 first as 384 wastes resources
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*/
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#if defined(MBEDTLS_HAS_ALG_SHA_256_VIA_LOWLEVEL_OR_PSA)
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#define COOKIE_MD MBEDTLS_MD_SHA256
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#define COOKIE_MD_OUTLEN 32
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#define COOKIE_HMAC_LEN 28
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#elif defined(MBEDTLS_HAS_ALG_SHA_384_VIA_LOWLEVEL_OR_PSA)
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#define COOKIE_MD MBEDTLS_MD_SHA384
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#define COOKIE_MD_OUTLEN 48
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#define COOKIE_HMAC_LEN 28
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#else
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#error "DTLS hello verify needs SHA-256 or SHA-384"
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#endif
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/*
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* Cookies are formed of a 4-bytes timestamp (or serial number) and
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* an HMAC of timestamp and client ID.
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*/
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#define COOKIE_LEN (4 + COOKIE_HMAC_LEN)
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void mbedtls_ssl_cookie_init(mbedtls_ssl_cookie_ctx *ctx)
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{
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#if defined(MBEDTLS_USE_PSA_CRYPTO)
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ctx->psa_hmac_key = MBEDTLS_SVC_KEY_ID_INIT;
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#else
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mbedtls_md_init(&ctx->hmac_ctx);
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#endif /* MBEDTLS_USE_PSA_CRYPTO */
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#if !defined(MBEDTLS_HAVE_TIME)
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ctx->serial = 0;
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#endif
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ctx->timeout = MBEDTLS_SSL_COOKIE_TIMEOUT;
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#if !defined(MBEDTLS_USE_PSA_CRYPTO)
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#if defined(MBEDTLS_THREADING_C)
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mbedtls_mutex_init(&ctx->mutex);
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#endif
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#endif /* !MBEDTLS_USE_PSA_CRYPTO */
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}
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void mbedtls_ssl_cookie_set_timeout(mbedtls_ssl_cookie_ctx *ctx, unsigned long delay)
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{
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ctx->timeout = delay;
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}
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void mbedtls_ssl_cookie_free(mbedtls_ssl_cookie_ctx *ctx)
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{
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#if defined(MBEDTLS_USE_PSA_CRYPTO)
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psa_destroy_key(ctx->psa_hmac_key);
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#else
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mbedtls_md_free(&ctx->hmac_ctx);
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#if defined(MBEDTLS_THREADING_C)
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mbedtls_mutex_free(&ctx->mutex);
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#endif
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#endif /* MBEDTLS_USE_PSA_CRYPTO */
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mbedtls_platform_zeroize(ctx, sizeof(mbedtls_ssl_cookie_ctx));
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}
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int mbedtls_ssl_cookie_setup(mbedtls_ssl_cookie_ctx *ctx,
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int (*f_rng)(void *, unsigned char *, size_t),
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void *p_rng)
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{
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#if defined(MBEDTLS_USE_PSA_CRYPTO)
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psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
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psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
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psa_algorithm_t alg;
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(void) f_rng;
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(void) p_rng;
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alg = mbedtls_hash_info_psa_from_md(COOKIE_MD);
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if (alg == 0) {
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return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
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}
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ctx->psa_hmac_alg = PSA_ALG_TRUNCATED_MAC(PSA_ALG_HMAC(alg),
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COOKIE_HMAC_LEN);
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psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_VERIFY_MESSAGE |
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PSA_KEY_USAGE_SIGN_MESSAGE);
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psa_set_key_algorithm(&attributes, ctx->psa_hmac_alg);
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psa_set_key_type(&attributes, PSA_KEY_TYPE_HMAC);
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psa_set_key_bits(&attributes, PSA_BYTES_TO_BITS(COOKIE_MD_OUTLEN));
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if ((status = psa_generate_key(&attributes,
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&ctx->psa_hmac_key)) != PSA_SUCCESS) {
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return psa_ssl_status_to_mbedtls(status);
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}
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#else
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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unsigned char key[COOKIE_MD_OUTLEN];
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if ((ret = f_rng(p_rng, key, sizeof(key))) != 0) {
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return ret;
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}
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ret = mbedtls_md_setup(&ctx->hmac_ctx, mbedtls_md_info_from_type(COOKIE_MD), 1);
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if (ret != 0) {
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return ret;
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}
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ret = mbedtls_md_hmac_starts(&ctx->hmac_ctx, key, sizeof(key));
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if (ret != 0) {
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return ret;
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}
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mbedtls_platform_zeroize(key, sizeof(key));
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#endif /* MBEDTLS_USE_PSA_CRYPTO */
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return 0;
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}
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#if !defined(MBEDTLS_USE_PSA_CRYPTO)
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/*
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* Generate the HMAC part of a cookie
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*/
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MBEDTLS_CHECK_RETURN_CRITICAL
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static int ssl_cookie_hmac(mbedtls_md_context_t *hmac_ctx,
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const unsigned char time[4],
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unsigned char **p, unsigned char *end,
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const unsigned char *cli_id, size_t cli_id_len)
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{
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unsigned char hmac_out[COOKIE_MD_OUTLEN];
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MBEDTLS_SSL_CHK_BUF_PTR(*p, end, COOKIE_HMAC_LEN);
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if (mbedtls_md_hmac_reset(hmac_ctx) != 0 ||
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mbedtls_md_hmac_update(hmac_ctx, time, 4) != 0 ||
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mbedtls_md_hmac_update(hmac_ctx, cli_id, cli_id_len) != 0 ||
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mbedtls_md_hmac_finish(hmac_ctx, hmac_out) != 0) {
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return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
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}
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memcpy(*p, hmac_out, COOKIE_HMAC_LEN);
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*p += COOKIE_HMAC_LEN;
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return 0;
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}
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#endif /* !MBEDTLS_USE_PSA_CRYPTO */
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/*
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* Generate cookie for DTLS ClientHello verification
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*/
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int mbedtls_ssl_cookie_write(void *p_ctx,
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unsigned char **p, unsigned char *end,
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const unsigned char *cli_id, size_t cli_id_len)
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{
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#if defined(MBEDTLS_USE_PSA_CRYPTO)
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psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT;
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psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
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size_t sign_mac_length = 0;
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#endif
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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mbedtls_ssl_cookie_ctx *ctx = (mbedtls_ssl_cookie_ctx *) p_ctx;
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unsigned long t;
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if (ctx == NULL || cli_id == NULL) {
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return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
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}
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MBEDTLS_SSL_CHK_BUF_PTR(*p, end, COOKIE_LEN);
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#if defined(MBEDTLS_HAVE_TIME)
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t = (unsigned long) mbedtls_time(NULL);
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#else
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t = ctx->serial++;
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#endif
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MBEDTLS_PUT_UINT32_BE(t, *p, 0);
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*p += 4;
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#if defined(MBEDTLS_USE_PSA_CRYPTO)
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status = psa_mac_sign_setup(&operation, ctx->psa_hmac_key,
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ctx->psa_hmac_alg);
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if (status != PSA_SUCCESS) {
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ret = psa_ssl_status_to_mbedtls(status);
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goto exit;
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}
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status = psa_mac_update(&operation, *p - 4, 4);
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if (status != PSA_SUCCESS) {
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ret = psa_ssl_status_to_mbedtls(status);
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goto exit;
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}
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status = psa_mac_update(&operation, cli_id, cli_id_len);
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if (status != PSA_SUCCESS) {
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ret = psa_ssl_status_to_mbedtls(status);
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goto exit;
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}
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status = psa_mac_sign_finish(&operation, *p, COOKIE_MD_OUTLEN,
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&sign_mac_length);
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if (status != PSA_SUCCESS) {
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ret = psa_ssl_status_to_mbedtls(status);
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goto exit;
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}
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*p += COOKIE_HMAC_LEN;
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ret = 0;
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#else
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#if defined(MBEDTLS_THREADING_C)
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if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0) {
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return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_SSL_INTERNAL_ERROR, ret);
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}
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#endif
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ret = ssl_cookie_hmac(&ctx->hmac_ctx, *p - 4,
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p, end, cli_id, cli_id_len);
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#if defined(MBEDTLS_THREADING_C)
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if (mbedtls_mutex_unlock(&ctx->mutex) != 0) {
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return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_SSL_INTERNAL_ERROR,
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MBEDTLS_ERR_THREADING_MUTEX_ERROR);
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}
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#endif
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#endif /* MBEDTLS_USE_PSA_CRYPTO */
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#if defined(MBEDTLS_USE_PSA_CRYPTO)
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exit:
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status = psa_mac_abort(&operation);
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if (status != PSA_SUCCESS) {
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ret = psa_ssl_status_to_mbedtls(status);
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}
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#endif /* MBEDTLS_USE_PSA_CRYPTO */
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return ret;
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}
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/*
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* Check a cookie
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*/
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int mbedtls_ssl_cookie_check(void *p_ctx,
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const unsigned char *cookie, size_t cookie_len,
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const unsigned char *cli_id, size_t cli_id_len)
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{
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#if defined(MBEDTLS_USE_PSA_CRYPTO)
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psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT;
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psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
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#else
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unsigned char ref_hmac[COOKIE_HMAC_LEN];
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unsigned char *p = ref_hmac;
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#endif
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int ret = 0;
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mbedtls_ssl_cookie_ctx *ctx = (mbedtls_ssl_cookie_ctx *) p_ctx;
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unsigned long cur_time, cookie_time;
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if (ctx == NULL || cli_id == NULL) {
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return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
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}
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if (cookie_len != COOKIE_LEN) {
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return -1;
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}
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#if defined(MBEDTLS_USE_PSA_CRYPTO)
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status = psa_mac_verify_setup(&operation, ctx->psa_hmac_key,
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ctx->psa_hmac_alg);
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if (status != PSA_SUCCESS) {
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ret = psa_ssl_status_to_mbedtls(status);
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goto exit;
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}
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status = psa_mac_update(&operation, cookie, 4);
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if (status != PSA_SUCCESS) {
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ret = psa_ssl_status_to_mbedtls(status);
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goto exit;
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}
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status = psa_mac_update(&operation, cli_id,
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cli_id_len);
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if (status != PSA_SUCCESS) {
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ret = psa_ssl_status_to_mbedtls(status);
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goto exit;
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}
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status = psa_mac_verify_finish(&operation, cookie + 4,
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COOKIE_HMAC_LEN);
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if (status != PSA_SUCCESS) {
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ret = psa_ssl_status_to_mbedtls(status);
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goto exit;
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}
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ret = 0;
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#else
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#if defined(MBEDTLS_THREADING_C)
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if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0) {
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return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_SSL_INTERNAL_ERROR, ret);
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}
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#endif
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if (ssl_cookie_hmac(&ctx->hmac_ctx, cookie,
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&p, p + sizeof(ref_hmac),
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cli_id, cli_id_len) != 0) {
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ret = -1;
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}
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#if defined(MBEDTLS_THREADING_C)
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if (mbedtls_mutex_unlock(&ctx->mutex) != 0) {
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ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_SSL_INTERNAL_ERROR,
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MBEDTLS_ERR_THREADING_MUTEX_ERROR);
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}
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#endif
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if (ret != 0) {
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goto exit;
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}
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if (mbedtls_ct_memcmp(cookie + 4, ref_hmac, sizeof(ref_hmac)) != 0) {
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ret = -1;
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goto exit;
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}
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#endif /* MBEDTLS_USE_PSA_CRYPTO */
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#if defined(MBEDTLS_HAVE_TIME)
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cur_time = (unsigned long) mbedtls_time(NULL);
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#else
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cur_time = ctx->serial;
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#endif
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cookie_time = ((unsigned long) cookie[0] << 24) |
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((unsigned long) cookie[1] << 16) |
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((unsigned long) cookie[2] << 8) |
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((unsigned long) cookie[3]);
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if (ctx->timeout != 0 && cur_time - cookie_time > ctx->timeout) {
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ret = -1;
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goto exit;
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}
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exit:
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#if defined(MBEDTLS_USE_PSA_CRYPTO)
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status = psa_mac_abort(&operation);
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if (status != PSA_SUCCESS) {
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ret = psa_ssl_status_to_mbedtls(status);
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}
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#else
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mbedtls_platform_zeroize(ref_hmac, sizeof(ref_hmac));
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#endif /* MBEDTLS_USE_PSA_CRYPTO */
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return ret;
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}
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#endif /* MBEDTLS_SSL_COOKIE_C */
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