blob: 71616250be05ea031c787cd35b0a767157284f23 [file] [log] [blame] [edit]
/*
* Copyright (c) 2016 Intel Corporation.
*
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @file Shim layer for TinyCrypt, making it complaint to crypto API.
*/
#include <tinycrypt/cbc_mode.h>
#include <tinycrypt/ctr_mode.h>
#include <tinycrypt/ccm_mode.h>
#include <tinycrypt/constants.h>
#include <tinycrypt/utils.h>
#include <string.h>
#include <zephyr/crypto/crypto.h>
#include "crypto_tc_shim_priv.h"
#define LOG_LEVEL CONFIG_CRYPTO_LOG_LEVEL
#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(tinycrypt);
#define CRYPTO_MAX_SESSION CONFIG_CRYPTO_TINYCRYPT_SHIM_MAX_SESSION
static struct tc_shim_drv_state tc_driver_state[CRYPTO_MAX_SESSION];
static int do_cbc_encrypt(struct cipher_ctx *ctx, struct cipher_pkt *op,
uint8_t *iv)
{
struct tc_shim_drv_state *data = ctx->drv_sessn_state;
if (tc_cbc_mode_encrypt(op->out_buf,
op->out_buf_max,
op->in_buf, op->in_len,
iv,
&data->session_key) == TC_CRYPTO_FAIL) {
LOG_ERR("TC internal error during CBC encryption");
return -EIO;
}
/* out_len is the same as in_len in CBC mode */
op->out_len = op->in_len;
return 0;
}
static int do_cbc_decrypt(struct cipher_ctx *ctx, struct cipher_pkt *op,
uint8_t *iv)
{
struct tc_shim_drv_state *data = ctx->drv_sessn_state;
/* TinyCrypt expects the IV and cipher text to be in a contiguous
* buffer for efficiency
*/
if (iv != op->in_buf) {
LOG_ERR("TC needs contiguous iv and ciphertext");
return -EIO;
}
if (tc_cbc_mode_decrypt(op->out_buf,
op->out_buf_max,
op->in_buf + TC_AES_BLOCK_SIZE,
op->in_len - TC_AES_BLOCK_SIZE,
op->in_buf, &data->session_key) == TC_CRYPTO_FAIL) {
LOG_ERR("Func TC internal error during CBC decryption");
return -EIO;
}
/* out_len is the same as in_len in CBC mode */
op->out_len = op->in_len;
return 0;
}
static int do_ctr_op(struct cipher_ctx *ctx, struct cipher_pkt *op,
uint8_t *iv)
{
struct tc_shim_drv_state *data = ctx->drv_sessn_state;
uint8_t ctr[16] = {0}; /* CTR mode Counter = iv:ctr */
int ivlen = ctx->keylen - (ctx->mode_params.ctr_info.ctr_len >> 3);
/* Tinycrypt takes the last 4 bytes of the counter parameter as the
* true counter start. IV forms the first 12 bytes of the split counter.
*/
memcpy(ctr, iv, ivlen);
if (tc_ctr_mode(op->out_buf, op->out_buf_max, op->in_buf,
op->in_len, ctr,
&data->session_key) == TC_CRYPTO_FAIL) {
LOG_ERR("TC internal error during CTR OP");
return -EIO;
}
/* out_len is the same as in_len in CTR mode */
op->out_len = op->in_len;
return 0;
}
static int do_ccm_encrypt_mac(struct cipher_ctx *ctx,
struct cipher_aead_pkt *aead_op, uint8_t *nonce)
{
struct tc_ccm_mode_struct ccm;
struct tc_shim_drv_state *data = ctx->drv_sessn_state;
struct ccm_params *ccm_param = &ctx->mode_params.ccm_info;
struct cipher_pkt *op = aead_op->pkt;
if (tc_ccm_config(&ccm, &data->session_key, nonce,
ccm_param->nonce_len,
ccm_param->tag_len) == TC_CRYPTO_FAIL) {
LOG_ERR("TC internal error during CCM encryption config");
return -EIO;
}
if (tc_ccm_generation_encryption(op->out_buf, op->out_buf_max,
aead_op->ad, aead_op->ad_len, op->in_buf,
op->in_len, &ccm) == TC_CRYPTO_FAIL) {
LOG_ERR("TC internal error during CCM Encryption OP");
return -EIO;
}
/* Looks like TinyCrypt appends the MAC to the end of out_buf as it
* does not give a separate hash parameter. The user needs to be aware
* of this and provide sufficient buffer space in output buffer to hold
* both encrypted output and hash
*/
if (aead_op->tag) {
memcpy(aead_op->tag, op->out_buf + op->in_len, ccm.mlen);
}
/* Before returning TC_CRYPTO_SUCCESS, tc_ccm_generation_encryption()
* will advance the output buffer pointer by op->in_len bytes,
* and then increment it ccm.mlen times (while writing to it).
*/
op->out_len = op->in_len + ccm.mlen;
return 0;
}
static int do_ccm_decrypt_auth(struct cipher_ctx *ctx,
struct cipher_aead_pkt *aead_op, uint8_t *nonce)
{
struct tc_ccm_mode_struct ccm;
struct tc_shim_drv_state *data = ctx->drv_sessn_state;
struct ccm_params *ccm_param = &ctx->mode_params.ccm_info;
struct cipher_pkt *op = aead_op->pkt;
if (tc_ccm_config(&ccm, &data->session_key, nonce,
ccm_param->nonce_len,
ccm_param->tag_len) == TC_CRYPTO_FAIL) {
LOG_ERR("TC internal error during CCM decryption config");
return -EIO;
}
/* TinyCrypt expects the hash/MAC to be present at the end of in_buf
* as it doesnt take a separate hash parameter. Ideally this should
* be moved to a ctx.flag check during session_setup, later.
*/
if (aead_op->tag != op->in_buf + op->in_len) {
LOG_ERR("TC needs contiguous hash at the end of inbuf");
return -EIO;
}
if (tc_ccm_decryption_verification(op->out_buf, op->out_buf_max,
aead_op->ad, aead_op->ad_len,
op->in_buf,
op->in_len + ccm_param->tag_len,
&ccm) == TC_CRYPTO_FAIL) {
LOG_ERR("TC internal error during CCM decryption OP");
return -EIO;
}
op->out_len = op->in_len + ccm_param->tag_len;
return 0;
}
static int get_unused_session(void)
{
int i;
for (i = 0; i < CRYPTO_MAX_SESSION; i++) {
if (tc_driver_state[i].in_use == 0) {
tc_driver_state[i].in_use = 1;
break;
}
}
return i;
}
static int tc_session_setup(const struct device *dev, struct cipher_ctx *ctx,
enum cipher_algo algo, enum cipher_mode mode,
enum cipher_op op_type)
{
struct tc_shim_drv_state *data;
int idx;
ARG_UNUSED(dev);
/* The shim currently supports only CBC or CTR mode for AES */
if (algo != CRYPTO_CIPHER_ALGO_AES) {
LOG_ERR("TC Shim Unsupported algo");
return -EINVAL;
}
/* TinyCrypt being a software library, only synchronous operations
* make sense.
*/
if (!(ctx->flags & CAP_SYNC_OPS)) {
LOG_ERR("Async not supported by this driver");
return -EINVAL;
}
if (ctx->keylen != TC_AES_KEY_SIZE) {
/* TinyCrypt supports only 128 bits */
LOG_ERR("TC Shim Unsupported key size");
return -EINVAL;
}
if (op_type == CRYPTO_CIPHER_OP_ENCRYPT) {
switch (mode) {
case CRYPTO_CIPHER_MODE_CBC:
ctx->ops.cbc_crypt_hndlr = do_cbc_encrypt;
break;
case CRYPTO_CIPHER_MODE_CTR:
if (ctx->mode_params.ctr_info.ctr_len != 32U) {
LOG_ERR("Tinycrypt supports only 32 bit "
"counter");
return -EINVAL;
}
ctx->ops.ctr_crypt_hndlr = do_ctr_op;
break;
case CRYPTO_CIPHER_MODE_CCM:
ctx->ops.ccm_crypt_hndlr = do_ccm_encrypt_mac;
break;
default:
LOG_ERR("TC Shim Unsupported mode");
return -EINVAL;
}
} else {
switch (mode) {
case CRYPTO_CIPHER_MODE_CBC:
ctx->ops.cbc_crypt_hndlr = do_cbc_decrypt;
break;
case CRYPTO_CIPHER_MODE_CTR:
/* Maybe validate CTR length */
if (ctx->mode_params.ctr_info.ctr_len != 32U) {
LOG_ERR("Tinycrypt supports only 32 bit "
"counter");
return -EINVAL;
}
ctx->ops.ctr_crypt_hndlr = do_ctr_op;
break;
case CRYPTO_CIPHER_MODE_CCM:
ctx->ops.ccm_crypt_hndlr = do_ccm_decrypt_auth;
break;
default:
LOG_ERR("TC Shim Unsupported mode");
return -EINVAL;
}
}
ctx->ops.cipher_mode = mode;
idx = get_unused_session();
if (idx == CRYPTO_MAX_SESSION) {
LOG_ERR("Max sessions in progress");
return -ENOSPC;
}
data = &tc_driver_state[idx];
if (tc_aes128_set_encrypt_key(&data->session_key, ctx->key.bit_stream)
== TC_CRYPTO_FAIL) {
LOG_ERR("TC internal error in setting key");
tc_driver_state[idx].in_use = 0;
return -EIO;
}
ctx->drv_sessn_state = data;
return 0;
}
static int tc_query_caps(const struct device *dev)
{
return (CAP_RAW_KEY | CAP_SEPARATE_IO_BUFS | CAP_SYNC_OPS);
}
static int tc_session_free(const struct device *dev, struct cipher_ctx *sessn)
{
struct tc_shim_drv_state *data = sessn->drv_sessn_state;
ARG_UNUSED(dev);
(void)memset(data, 0, sizeof(struct tc_shim_drv_state));
data->in_use = 0;
return 0;
}
static int tc_shim_init(const struct device *dev)
{
int i;
ARG_UNUSED(dev);
for (i = 0; i < CRYPTO_MAX_SESSION; i++) {
tc_driver_state[i].in_use = 0;
}
return 0;
}
static struct crypto_driver_api crypto_enc_funcs = {
.cipher_begin_session = tc_session_setup,
.cipher_free_session = tc_session_free,
.cipher_async_callback_set = NULL,
.query_hw_caps = tc_query_caps,
};
DEVICE_DEFINE(crypto_tinycrypt, CONFIG_CRYPTO_TINYCRYPT_SHIM_DRV_NAME,
&tc_shim_init, NULL, NULL, NULL,
POST_KERNEL, CONFIG_CRYPTO_INIT_PRIORITY,
(void *)&crypto_enc_funcs);