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/*
* TLS server tickets callbacks implementation
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*/
#include "common.h"
#if defined(MBEDTLS_SSL_TICKET_C)
#include "mbedtls/platform.h"
#include "ssl_misc.h"
#include "mbedtls/ssl_ticket.h"
#include "mbedtls/error.h"
#include "mbedtls/platform_util.h"
#include <string.h>
#if defined(MBEDTLS_USE_PSA_CRYPTO)
/* Define a local translating function to save code size by not using too many
* arguments in each translating place. */
static int local_err_translation(psa_status_t status)
{
return psa_status_to_mbedtls(status, psa_to_ssl_errors,
ARRAY_LENGTH(psa_to_ssl_errors),
psa_generic_status_to_mbedtls);
}
#define PSA_TO_MBEDTLS_ERR(status) local_err_translation(status)
#endif
/*
* Initialize context
*/
void mbedtls_ssl_ticket_init(mbedtls_ssl_ticket_context *ctx)
{
memset(ctx, 0, sizeof(mbedtls_ssl_ticket_context));
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_init(&ctx->mutex);
#endif
}
#define MAX_KEY_BYTES MBEDTLS_SSL_TICKET_MAX_KEY_BYTES
#define TICKET_KEY_NAME_BYTES MBEDTLS_SSL_TICKET_KEY_NAME_BYTES
#define TICKET_IV_BYTES 12
#define TICKET_CRYPT_LEN_BYTES 2
#define TICKET_AUTH_TAG_BYTES 16
#define TICKET_MIN_LEN (TICKET_KEY_NAME_BYTES + \
TICKET_IV_BYTES + \
TICKET_CRYPT_LEN_BYTES + \
TICKET_AUTH_TAG_BYTES)
#define TICKET_ADD_DATA_LEN (TICKET_KEY_NAME_BYTES + \
TICKET_IV_BYTES + \
TICKET_CRYPT_LEN_BYTES)
/*
* Generate/update a key
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_ticket_gen_key(mbedtls_ssl_ticket_context *ctx,
unsigned char index)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char buf[MAX_KEY_BYTES] = { 0 };
mbedtls_ssl_ticket_key *key = ctx->keys + index;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
#endif
#if defined(MBEDTLS_HAVE_TIME)
key->generation_time = mbedtls_time(NULL);
#endif
/* The lifetime of a key is the configured lifetime of the tickets when
* the key is created.
*/
key->lifetime = ctx->ticket_lifetime;
if ((ret = ctx->f_rng(ctx->p_rng, key->name, sizeof(key->name))) != 0) {
return ret;
}
if ((ret = ctx->f_rng(ctx->p_rng, buf, sizeof(buf))) != 0) {
return ret;
}
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_set_key_usage_flags(&attributes,
PSA_KEY_USAGE_ENCRYPT | PSA_KEY_USAGE_DECRYPT);
psa_set_key_algorithm(&attributes, key->alg);
psa_set_key_type(&attributes, key->key_type);
psa_set_key_bits(&attributes, key->key_bits);
ret = PSA_TO_MBEDTLS_ERR(
psa_import_key(&attributes, buf,
PSA_BITS_TO_BYTES(key->key_bits),
&key->key));
#else
/* With GCM and CCM, same context can encrypt & decrypt */
ret = mbedtls_cipher_setkey(&key->ctx, buf,
mbedtls_cipher_get_key_bitlen(&key->ctx),
MBEDTLS_ENCRYPT);
#endif /* MBEDTLS_USE_PSA_CRYPTO */
mbedtls_platform_zeroize(buf, sizeof(buf));
return ret;
}
/*
* Rotate/generate keys if necessary
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_ticket_update_keys(mbedtls_ssl_ticket_context *ctx)
{
#if !defined(MBEDTLS_HAVE_TIME)
((void) ctx);
#else
mbedtls_ssl_ticket_key * const key = ctx->keys + ctx->active;
if (key->lifetime != 0) {
mbedtls_time_t current_time = mbedtls_time(NULL);
mbedtls_time_t key_time = key->generation_time;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
#endif
if (current_time >= key_time &&
(uint64_t) (current_time - key_time) < key->lifetime) {
return 0;
}
ctx->active = 1 - ctx->active;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
if ((status = psa_destroy_key(ctx->keys[ctx->active].key)) != PSA_SUCCESS) {
return PSA_TO_MBEDTLS_ERR(status);
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
return ssl_ticket_gen_key(ctx, ctx->active);
} else
#endif /* MBEDTLS_HAVE_TIME */
return 0;
}
/*
* Rotate active session ticket encryption key
*/
int mbedtls_ssl_ticket_rotate(mbedtls_ssl_ticket_context *ctx,
const unsigned char *name, size_t nlength,
const unsigned char *k, size_t klength,
uint32_t lifetime)
{
const unsigned char idx = 1 - ctx->active;
mbedtls_ssl_ticket_key * const key = ctx->keys + idx;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
const size_t bitlen = key->key_bits;
#else
const int bitlen = mbedtls_cipher_get_key_bitlen(&key->ctx);
#endif
if (nlength < TICKET_KEY_NAME_BYTES || klength * 8 < (size_t) bitlen) {
return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;
}
#if defined(MBEDTLS_USE_PSA_CRYPTO)
if ((status = psa_destroy_key(key->key)) != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
return ret;
}
psa_set_key_usage_flags(&attributes,
PSA_KEY_USAGE_ENCRYPT | PSA_KEY_USAGE_DECRYPT);
psa_set_key_algorithm(&attributes, key->alg);
psa_set_key_type(&attributes, key->key_type);
psa_set_key_bits(&attributes, key->key_bits);
if ((status = psa_import_key(&attributes, k,
PSA_BITS_TO_BYTES(key->key_bits),
&key->key)) != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
return ret;
}
#else
ret = mbedtls_cipher_setkey(&key->ctx, k, bitlen, MBEDTLS_ENCRYPT);
if (ret != 0) {
return ret;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
ctx->active = idx;
ctx->ticket_lifetime = lifetime;
memcpy(key->name, name, TICKET_KEY_NAME_BYTES);
#if defined(MBEDTLS_HAVE_TIME)
key->generation_time = mbedtls_time(NULL);
#endif
key->lifetime = lifetime;
return 0;
}
/*
* Setup context for actual use
*/
int mbedtls_ssl_ticket_setup(mbedtls_ssl_ticket_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
mbedtls_cipher_type_t cipher,
uint32_t lifetime)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t key_bits;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_algorithm_t alg;
psa_key_type_t key_type;
#else
const mbedtls_cipher_info_t *cipher_info;
#endif /* MBEDTLS_USE_PSA_CRYPTO */
#if defined(MBEDTLS_USE_PSA_CRYPTO)
if (mbedtls_ssl_cipher_to_psa(cipher, TICKET_AUTH_TAG_BYTES,
&alg, &key_type, &key_bits) != PSA_SUCCESS) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
if (PSA_ALG_IS_AEAD(alg) == 0) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
#else
cipher_info = mbedtls_cipher_info_from_type(cipher);
if (mbedtls_cipher_info_get_mode(cipher_info) != MBEDTLS_MODE_GCM &&
mbedtls_cipher_info_get_mode(cipher_info) != MBEDTLS_MODE_CCM &&
mbedtls_cipher_info_get_mode(cipher_info) != MBEDTLS_MODE_CHACHAPOLY) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
key_bits = mbedtls_cipher_info_get_key_bitlen(cipher_info);
#endif /* MBEDTLS_USE_PSA_CRYPTO */
if (key_bits > 8 * MAX_KEY_BYTES) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
ctx->f_rng = f_rng;
ctx->p_rng = p_rng;
ctx->ticket_lifetime = lifetime;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
ctx->keys[0].alg = alg;
ctx->keys[0].key_type = key_type;
ctx->keys[0].key_bits = key_bits;
ctx->keys[1].alg = alg;
ctx->keys[1].key_type = key_type;
ctx->keys[1].key_bits = key_bits;
#else
if ((ret = mbedtls_cipher_setup(&ctx->keys[0].ctx, cipher_info)) != 0) {
return ret;
}
if ((ret = mbedtls_cipher_setup(&ctx->keys[1].ctx, cipher_info)) != 0) {
return ret;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
if ((ret = ssl_ticket_gen_key(ctx, 0)) != 0 ||
(ret = ssl_ticket_gen_key(ctx, 1)) != 0) {
return ret;
}
return 0;
}
/*
* Create session ticket, with the following structure:
*
* struct {
* opaque key_name[4];
* opaque iv[12];
* opaque encrypted_state<0..2^16-1>;
* opaque tag[16];
* } ticket;
*
* The key_name, iv, and length of encrypted_state are the additional
* authenticated data.
*/
int mbedtls_ssl_ticket_write(void *p_ticket,
const mbedtls_ssl_session *session,
unsigned char *start,
const unsigned char *end,
size_t *tlen,
uint32_t *ticket_lifetime)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_ssl_ticket_context *ctx = p_ticket;
mbedtls_ssl_ticket_key *key;
unsigned char *key_name = start;
unsigned char *iv = start + TICKET_KEY_NAME_BYTES;
unsigned char *state_len_bytes = iv + TICKET_IV_BYTES;
unsigned char *state = state_len_bytes + TICKET_CRYPT_LEN_BYTES;
size_t clear_len, ciph_len;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
#endif
*tlen = 0;
if (ctx == NULL || ctx->f_rng == NULL) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
/* We need at least 4 bytes for key_name, 12 for IV, 2 for len 16 for tag,
* in addition to session itself, that will be checked when writing it. */
MBEDTLS_SSL_CHK_BUF_PTR(start, end, TICKET_MIN_LEN);
#if defined(MBEDTLS_THREADING_C)
if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0) {
return ret;
}
#endif
if ((ret = ssl_ticket_update_keys(ctx)) != 0) {
goto cleanup;
}
key = &ctx->keys[ctx->active];
*ticket_lifetime = key->lifetime;
memcpy(key_name, key->name, TICKET_KEY_NAME_BYTES);
if ((ret = ctx->f_rng(ctx->p_rng, iv, TICKET_IV_BYTES)) != 0) {
goto cleanup;
}
/* Dump session state */
if ((ret = mbedtls_ssl_session_save(session,
state, (size_t) (end - state),
&clear_len)) != 0 ||
(unsigned long) clear_len > 65535) {
goto cleanup;
}
MBEDTLS_PUT_UINT16_BE(clear_len, state_len_bytes, 0);
/* Encrypt and authenticate */
#if defined(MBEDTLS_USE_PSA_CRYPTO)
if ((status = psa_aead_encrypt(key->key, key->alg, iv, TICKET_IV_BYTES,
key_name, TICKET_ADD_DATA_LEN,
state, clear_len,
state, end - state,
&ciph_len)) != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
goto cleanup;
}
#else
if ((ret = mbedtls_cipher_auth_encrypt_ext(&key->ctx,
iv, TICKET_IV_BYTES,
/* Additional data: key name, IV and length */
key_name, TICKET_ADD_DATA_LEN,
state, clear_len,
state, (size_t) (end - state), &ciph_len,
TICKET_AUTH_TAG_BYTES)) != 0) {
goto cleanup;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
if (ciph_len != clear_len + TICKET_AUTH_TAG_BYTES) {
ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
goto cleanup;
}
*tlen = TICKET_MIN_LEN + ciph_len - TICKET_AUTH_TAG_BYTES;
cleanup:
#if defined(MBEDTLS_THREADING_C)
if (mbedtls_mutex_unlock(&ctx->mutex) != 0) {
return MBEDTLS_ERR_THREADING_MUTEX_ERROR;
}
#endif
return ret;
}
/*
* Select key based on name
*/
static mbedtls_ssl_ticket_key *ssl_ticket_select_key(
mbedtls_ssl_ticket_context *ctx,
const unsigned char name[4])
{
unsigned char i;
for (i = 0; i < sizeof(ctx->keys) / sizeof(*ctx->keys); i++) {
if (memcmp(name, ctx->keys[i].name, 4) == 0) {
return &ctx->keys[i];
}
}
return NULL;
}
/*
* Load session ticket (see mbedtls_ssl_ticket_write for structure)
*/
int mbedtls_ssl_ticket_parse(void *p_ticket,
mbedtls_ssl_session *session,
unsigned char *buf,
size_t len)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_ssl_ticket_context *ctx = p_ticket;
mbedtls_ssl_ticket_key *key;
unsigned char *key_name = buf;
unsigned char *iv = buf + TICKET_KEY_NAME_BYTES;
unsigned char *enc_len_p = iv + TICKET_IV_BYTES;
unsigned char *ticket = enc_len_p + TICKET_CRYPT_LEN_BYTES;
size_t enc_len, clear_len;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
#endif
if (ctx == NULL || ctx->f_rng == NULL) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
if (len < TICKET_MIN_LEN) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
#if defined(MBEDTLS_THREADING_C)
if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0) {
return ret;
}
#endif
if ((ret = ssl_ticket_update_keys(ctx)) != 0) {
goto cleanup;
}
enc_len = MBEDTLS_GET_UINT16_BE(enc_len_p, 0);
if (len != TICKET_MIN_LEN + enc_len) {
ret = MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
goto cleanup;
}
/* Select key */
if ((key = ssl_ticket_select_key(ctx, key_name)) == NULL) {
/* We can't know for sure but this is a likely option unless we're
* under attack - this is only informative anyway */
ret = MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED;
goto cleanup;
}
/* Decrypt and authenticate */
#if defined(MBEDTLS_USE_PSA_CRYPTO)
if ((status = psa_aead_decrypt(key->key, key->alg, iv, TICKET_IV_BYTES,
key_name, TICKET_ADD_DATA_LEN,
ticket, enc_len + TICKET_AUTH_TAG_BYTES,
ticket, enc_len, &clear_len)) != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
goto cleanup;
}
#else
if ((ret = mbedtls_cipher_auth_decrypt_ext(&key->ctx,
iv, TICKET_IV_BYTES,
/* Additional data: key name, IV and length */
key_name, TICKET_ADD_DATA_LEN,
ticket, enc_len + TICKET_AUTH_TAG_BYTES,
ticket, enc_len, &clear_len,
TICKET_AUTH_TAG_BYTES)) != 0) {
if (ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED) {
ret = MBEDTLS_ERR_SSL_INVALID_MAC;
}
goto cleanup;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
if (clear_len != enc_len) {
ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
goto cleanup;
}
/* Actually load session */
if ((ret = mbedtls_ssl_session_load(session, ticket, clear_len)) != 0) {
goto cleanup;
}
#if defined(MBEDTLS_HAVE_TIME)
mbedtls_ms_time_t ticket_creation_time, ticket_age;
mbedtls_ms_time_t ticket_lifetime =
(mbedtls_ms_time_t) key->lifetime * 1000;
ret = mbedtls_ssl_session_get_ticket_creation_time(session,
&ticket_creation_time);
if (ret != 0) {
goto cleanup;
}
ticket_age = mbedtls_ms_time() - ticket_creation_time;
if (ticket_age < 0 || ticket_age > ticket_lifetime) {
ret = MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED;
goto cleanup;
}
#endif
cleanup:
#if defined(MBEDTLS_THREADING_C)
if (mbedtls_mutex_unlock(&ctx->mutex) != 0) {
return MBEDTLS_ERR_THREADING_MUTEX_ERROR;
}
#endif
return ret;
}
/*
* Free context
*/
void mbedtls_ssl_ticket_free(mbedtls_ssl_ticket_context *ctx)
{
if (ctx == NULL) {
return;
}
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_destroy_key(ctx->keys[0].key);
psa_destroy_key(ctx->keys[1].key);
#else
mbedtls_cipher_free(&ctx->keys[0].ctx);
mbedtls_cipher_free(&ctx->keys[1].ctx);
#endif /* MBEDTLS_USE_PSA_CRYPTO */
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_free(&ctx->mutex);
#endif
mbedtls_platform_zeroize(ctx, sizeof(mbedtls_ssl_ticket_context));
}
#endif /* MBEDTLS_SSL_TICKET_C */
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