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7d68a1954c99581059432291b00d1aa332c715ab
mbedtls/library/ssl_ticket.c
Dave Rodgman 7ff7965561 Update headers 
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
2023-11-03 12:04:52 +00:00

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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 "mbedtls/ssl_internal.h"
#include "mbedtls/ssl_ticket.h"
#include "mbedtls/error.h"
#include "mbedtls/platform_util.h"
#include <string.h>
/*
* 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 32 /* 256 bits */
#define TICKET_KEY_NAME_BYTES 4
#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];
mbedtls_ssl_ticket_key *key = ctx->keys + index;
#if defined(MBEDTLS_HAVE_TIME)
key->generation_time = (uint32_t) mbedtls_time(NULL);
#endif
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;
}
/* 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);
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
if (ctx->ticket_lifetime != 0) {
uint32_t current_time = (uint32_t) mbedtls_time(NULL);
uint32_t key_time = ctx->keys[ctx->active].generation_time;
if (current_time >= key_time &&
current_time - key_time < ctx->ticket_lifetime) {
return 0;
}
ctx->active = 1 - ctx->active;
return ssl_ticket_gen_key(ctx, ctx->active);
} else
#endif /* MBEDTLS_HAVE_TIME */
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;
const mbedtls_cipher_info_t *cipher_info;
ctx->f_rng = f_rng;
ctx->p_rng = p_rng;
ctx->ticket_lifetime = lifetime;
cipher_info = mbedtls_cipher_info_from_type(cipher);
if (cipher_info == NULL) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
if (cipher_info->mode != MBEDTLS_MODE_GCM &&
cipher_info->mode != MBEDTLS_MODE_CCM) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
if (cipher_info->key_bitlen > 8 * MAX_KEY_BYTES) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
int do_mbedtls_cipher_setup = 1;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
ret = mbedtls_cipher_setup_psa(&ctx->keys[0].ctx,
cipher_info, TICKET_AUTH_TAG_BYTES);
switch (ret) {
case 0:
do_mbedtls_cipher_setup = 0;
break;
case MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE:
/* We don't yet expect to support all ciphers through PSA,
* so allow fallback to ordinary mbedtls_cipher_setup(). */
do_mbedtls_cipher_setup = 1;
break;
default:
return ret;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
if (do_mbedtls_cipher_setup) {
if ((ret = mbedtls_cipher_setup(&ctx->keys[0].ctx, cipher_info))
!= 0) {
return ret;
}
}
do_mbedtls_cipher_setup = 1;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
do_mbedtls_cipher_setup = 0;
ret = mbedtls_cipher_setup_psa(&ctx->keys[1].ctx,
cipher_info, TICKET_AUTH_TAG_BYTES);
if (ret != 0 && ret != MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE) {
return ret;
}
if (ret == MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE) {
do_mbedtls_cipher_setup = 1;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
if (do_mbedtls_cipher_setup) {
if ((ret = mbedtls_cipher_setup(&ctx->keys[1].ctx, cipher_info))
!= 0) {
return ret;
}
}
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;
*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 = ctx->ticket_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, 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 ((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, end - state, &ciph_len,
TICKET_AUTH_TAG_BYTES)) != 0) {
goto cleanup;
}
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 (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 = (enc_len_p[0] << 8) | enc_len_p[1];
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 ((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;
}
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)
{
/* Check for expiration */
mbedtls_time_t current_time = mbedtls_time(NULL);
if (current_time < session->start ||
(uint32_t) (current_time - session->start) > ctx->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)
{
mbedtls_cipher_free(&ctx->keys[0].ctx);
mbedtls_cipher_free(&ctx->keys[1].ctx);
#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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